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Lactobacillus

7,486 bytes added, 23:47, 9 April 2017
added graphs for hop sensitivity data
| [[Craft Cultures]] || CCYL512 || L. brevis || Heterofermentative || || Typically produces more lactic acid than Lactobacillus delbrueckii. Commercial pitches only.
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| [[White Labs]] || WLP677 || L. delbrueckii (potentially misidentified) || Heterofermentative <ref name="mtf_wiki_shaner">[http://www.milkthefunk.com/wiki/100%25_Lactobacillus_Fermentation Milk The Funk Wiki. 100% Lactobacillus Fermentation Test by Lance Shaner.]</ref><ref name="tmf_cultures">[http://www.themadfermentationist.com/p/commercial-cultures.html ''Commercial Brettanomyces, Lactobacillus, and Pediococcus Descriptions''. The Mad Fermentationist Blog. Michael Tonsmeire. Retrieved 3/4/2015.]</ref> || no stir plate, room temp ||Incubate at > 90°F and < 117°F for 5-7 days for greater lactic acid production. Cell count: 50-80 million cells/mL (1.75-2.8 billion cells in a 35 mL homebrew vial) <ref name="WL_cellcounts">Private correspondence with White Labs Customer Service and Dan Pixley. 10/29/2015.</ref>. Not a good strain for kettle souring, but can produce a "soft" acidity over a longer period of time <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1212455192116026/?comment_id=1212475888780623&reply_comment_id=1212476575447221&comment_tracking=%7B%22tn%22%3A%22R3%22%7D Conversation with Andrew Addkison on MTF. 01/12/2016.]</ref>. White Labs claims that it is tolerant to up to 20 IBU <ref>[http://www.themadfermentationist.com/p/commercial-cultures.html "Commercial Brettanomyces, Lactobacillus, and Pediococcus Descriptions; Commercial Yeast Laboratories." The Mad Fermentationist blog. Michael Tonsmeire. Retrieved 12/12/2016.]</ref>.
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| [[White Labs]] || WLP672 || L. brevis || Heterofermentative <ref name="mtf_wiki_shaner"></ref><ref name="nick">[https://www.facebook.com/groups/MilkTheFunk/permalink/1029638267064387/?comment_id=1030638553631025&offset=0&total_comments=24 Conversation with Nick Impellitteri from The Yeast Bay on the MTF Facebook Group. 3/4/2015.]</ref> || No stir plate, room temp|| Produced by [[The Yeast Bay]]. More hop tolerant than other Lacto strains, however TYB advises to use wort with less than 10 IBU. Temperature range: 70-95°F; 80% attenuation (this may not reflect actual attenuation of wort in a real brewery; see reference <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1031115430250004/?comment_id=1031244193570461&offset=0&total_comments=33 Conversation with Michael Soo and Nick Impellitteri on the Milk The Funk Facebook Group. 3/5/2015.]</ref>). <ref>[http://www.theyeastbay.com/wild-yeast-and-bacteria-products/wlp672-lactobacillus-brevis The Yeast Bay website. Retrieved 3/2/2015.]</ref> Cell count: 50-80 million cells/mL (1.75-2.8 billion cells for 35 mL homebrew vials) <ref name="WL_cellcounts"></ref>.
| [[Wyeast]] || 5335 || L. buchneri || Heterofermentative <ref name="mtf_wiki_shaner"></ref> || 1 liter starter for a 5 gallon batch of beer, 1.020 DME sterile wort, no stir plate, no O2, starter at 90°F if possible 5-7 days || Incubate at 90°F for 5-7 days for greater lactic acid production. Cell count: 1.0 x 10<sup>8</sup> (100 million) cells/mL (10 billion cells in a 100 mL homebrew pouch) <ref name="wyeast_cellcounts">[https://drive.google.com/folderview?id=0B8CshC9nxYHdZmE4MmoyLXA2WVk&usp=sharing Wyeast Specifications 2015 Retail Products. 2015.]</ref>.
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| [[Wyeast]] || 5223-PC || L. brevis || Heterofermentative <ref name="mtf_wiki_shaner"></ref><ref name="nick"></ref> || no stir plate, room temp is fine || Heterofermentative (produces lactic acid, ethanol and CO2), more hop tolerant. Does well at room temperature. AVAILABLE ONLY FROM JULY THROUGH SEPTEMBER 2014 (Michael Dawson from Wyeast indicated that this culture may return at some point). Jamie Daly indicated on MTF that he got almost no sourness after 24 hours at 100°F (37.8°C). He lowered the temperature to 90°F-95°F (32.2°C-35°C) for 36 hours, and the pH of the wort went down to 3.29. Thus, Jamie recommends 90°F-95°F (32.2°C-35°C) for 60 hours for better souring; avoid warmer temperatures. He also aerated his starter of L. brevis (brevis 2L starter of 1.020 dmeDME) and set it on a stir plate at 95°F <ref name="brevis_aeration">[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC547135/ Growth Response of Lactobacillus brevis to Aeration and Organic Catalysts. J. R. Stamer and B. O. Stoyla. Appl Microbiol. Sep 1967; 15(5): 1025–1030.]</ref>. The beer wort was not aerated, and the fermenter was flushed with CO2. These methods need verification. Cell count: 1.0 x 10<sup>8</sup> (100 million) cells/mL (10 billion cells in a 100 mL homebrew pouch) <ref name="wyeast_cellcounts"></ref>.
|-
| [[Omega Yeast Labs]] || OYL-605 || L. brevis, <span style="text-decoration: line-through;">delbrueckii</span>, and plantarum blend || Hetero/Hetero <ref name="mtf_wiki_shaner"></ref> || 1 liter starter for a 5 gallon batch of beer at room temperature for 24-48 hours. No stir plate unless kept anaerobic. || Quick souring. Pitch into 65°F-95°F <ref name="adi_oyl605"></ref>. Holding temperature is not required. No longer contains delbruekii <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1065268213501392/?comment_id=1065669443461269&offset=0&total_comments=18&comment_tracking=%7B%22tn%22%3A%22R%22%7D Conversation with Raymond Wagner of Oso Brewing Co on Milk The Funk. 4/30/2015.]</ref>. Don't use any hops if possible. 2 IBU is a good target if hops must be used <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1092523807442499/?comment_id=1092571350771078&offset=0&total_comments=6&comment_tracking=%7B%22tn%22%3A%22R1%22%7D Conversation with Lance Shaner on MTF in regards to IBU tolerance of OYL-605. 6/15/2015.]</ref>. Contains ~150 billion cells per homebrew pitch <ref name="sbb2.0">[http://sourbeerblog.com/lactobacillus-2-0-advanced-techniques-for-fast-souring-beer/ Lactobacillus 2.0 – Advanced Techniques for Fast Souring Beer. Sour Beer Blog. Matt Miller. 11/18/2015. Retrieved 11/19/2015.]</ref>.
| [[SouthYeast Labs]] || Lactobacillus 2 || Unknown || Homofermentatative || || Source: Prickly pear fruit (South Carolina). Best suits strong sours, and lambic (high acidity).
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| [[Inland Island Brewing & Consulting|Inland Island Yeast Laboratories]] || INISBC-991 || L. brevis || Heterofermentative || || Produces more lactic acid at higher temperatures and in low hop worts. 70-95 F Temperature Range
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| [[Inland Island Brewing & Consulting|Inland Island Yeast Laboratories]] || INISBC-992 || L. delbruekii || Homofermentative || || Produces more lactic acid at higher temperatures and in low hop worts. 70-95 F Temperature Range
|-
| [[Inland Island Brewing & Consulting|Inland Island Yeast Laboratories]] || INISBC-932 || L. fermentum || Heterofermentative || ||
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| [[Escarpment Laboratories]] || Lactobacillus Blend || L. brevis and L. plantarum || Heterofermentative || || This blend is designed to be usable at a wide range of temperatures, and is especially suited for kettle souring/sour worting. We recommend pre-acidifying wort to 4.5 with lactic acid, then pitching the Lactobacillus blend in a CO2-purged kettle or fermentor at 32-42°C.
| [[Escarpment Laboratories]] || Lactobacillus brevis || L. brevis || Heterofermentative || || This strain is moderately hop-tolerant, and as such it can also be used for long-term souring of <10IBU beers. It also performs well in kettle souring/sour worting where fast and clean lactic acidity is desired. We recommend pre-acidifying wort to 4.5 with lactic acid, then pitching the Lactobacillus blend in a CO2-purged kettle or fermentor at 35-45°C.
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| [[The Yeast Bay]] || Lactobacillus Blend || L. plantarum, L. brevis, and an unidentified ''Lactobacillus'' species || Heterofermentative || || The Lactobacillus Blend includes three strains: Lactobacillus plantarum, Lactobacillus brevis and a strain of Lactobacillus isolated from a very unique brewer of American sour beers the returned a sequencing result of "uncultured Lactobacillus". Sure to please anyone with a knack for creating sour beers, it can quickly produce acidity across a wide range of temperatures. This blend can be used on its own for kettle souring prior to pitching yeast to create acidity quickly, or co-pitched with yeast to create sourness over time. It will produce a pronounced and rounded acidity that is the foundation of any complex sour beer. We recommend holding the IBU on the low end (< 2-3) if you'd like to use this blend to create acidity in a shorter time frame. Higher IBUs may result in very slow or no souring (testing is still ongoing to determine IBU at which lactic acid production is inhibited). Temperature: 70-100°F90°F. Cell count: 50-80 million cells/mL (1.75-2.8 billion cells for 35 mL homebrew vials) <ref name="WL_cellcounts"></ref><ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1280135442014667/?comment_id=1280341068660771&reply_comment_id=1280498695311675&comment_tracking=%7B%22tn%22%3A%22R1%22%7D Conversation with Nick Impellitteri on MTF regarding TYB Lactobacillus Blend cell counts. 04/08/2016.]</ref>. Recommended temperature range for fastest acid production for kettle souring is 85-90°F, although if kept in the 70's it should produce good acidification in 48-72 hours. A major drop off of in acid production is seen above 90°F <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1616265398401668/?comment_id=1617001948328013&comment_tracking=%7B%22tn%22%3A%22R%22%7D Impellitteri, Nick. Milk The Funk Facebook group. 03/17/2017.]</ref>.
|}
====[[White Labs]] on WLP672====
"It is intended for secondary, so you only need to do a starter if you are doing a primary fermentation with it. DME would be the best substrate... Since its a Lacto species, you don't really want to aerate it. A slow stir-plate would be good, to keep it moving, but not much more than that." - Sarah Neel, White Labs, Sales and Customer Service (quoted with permission).
 
Since WLP672 is meant for long term aging, it is not preferred to use for kettle souring/wort souring. See also [[100%25_Lactobacillus_Fermentation#History|100% ''Lactobacillus'' fermentation]].
===General Advice===
Another thing to consider is that achieving a pH of 4 as fast as possible is advisable for preventing off-flavors from contaminating microbes <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1180630378631841/?comment_id=1181674265194119&reply_comment_id=1181715048523374&comment_tracking=%7B%22tn%22%3A%22R7%22%7D Conversation with Bryan of Sui Generis Blog on MTF regarding speed of acid production with Lacto. 11/20/2015.]</ref>. Larger pitch rates tend to achieve a lower pH faster <ref name="bryan_lacto_starters"></ref>. Therefore, unless using [[Lactobacillus#Samuel_Aeschlimann.27s_Starter_Procedures|Samuel Aeschlimann's starter procedure]], pitching 0.5-1 liters of starter for 5 gallons of wort is advisable in general. Even when using [[Lactobacillus#Samuel_Aeschlimann.27s_Starter_Procedures|Samuel Aeschlimann's starter procedure]], over-pitching ''Lactobacillus'' is not a concern (pitching an overly massive starter wort could produce undesirable flavors), so the same pitch rate should still be considered unless the brewer is confident that high growth rate has been achieved in the starter. Other factors that might affect the effectiveness of a volume based starter is the species/strain of the ''Lactobacillus'' being used, how much yeast contamination has occurred, and how old the ''Lactobacillus'' starter is. Some species/strains may require a larger volume of starter, as well as if yeast has contaminated the starter or wort (see [[Lactobacillus#100.25_Lactobacillus_Fermentation|100% Lactobacillus Fermentation]]). If a ''Lactobacillus'' culture is older than 1 month, then a fresh starter should be made. Keeping a separate Erlenmeyer flask for ''Lactobacillus'' starters can help to prevent yeast contamination <ref>Private correspondence with Richard Preiss to Dan Pixley. 11/20/2015.]</ref>, as well as using sterilization equipment such as an autoclave or pressure cooker.
Starter mediums that brewers have used include unhopped DME wort starters and apple juice starters. These tend to be adequate for many brewers. However, [https://eurekabrewing.wordpress.com/2015/05/18/evaluate-starter-media-to-propagate-lactobacillus-sp/ Samuel Aeschlimann from Eureka Brewing Blog] showed that using DME with a little bit of apple juice, chalk, and yeast nutrients provides close to optimal cell densities that match MRS media cell densities. See [[Lactobacillus#Samuel_Aeschlimann.27s_Starter_Procedures|Samuel Aeschlimann's Starter Procedures]]. Specific nutrients that will increase growth is thiamine (vitamin B1), or a combination of thiamine and riboflavin (vitamin B2). For example, it has been shown that thiamine is required in order for ''L. brevis'' to efficiently convert pyruvate into lactic acid and ethanol. The addition of these nutrients can help encourage growth <ref>[http://onlinelibrary.wiley.com/doi/10.1002/jib.385/full The influence of thiamine and riboflavin on various spoilage microorganisms commonly found in beer. Barry Hucker, Melinda Christophersen, Frank Vriesekoop. 2017.]</ref>.
Although more experiments and probably needed, agitation is believed to be an important factor for both yeast and bacteria in general. Gentle stirring on a stir plate or orbital shaker, or frequent gentle manual agitation leads to faster growth and a higher number of organisms. Agitation keeps the microbes in solution. It also maximizes the microbes' access to nutrients and disperses waste evenly. In a non-agitated starter, the microbes are limited to the diffusion rate of nutrients, leading to a slower and more stressful growth <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1168024059892473/?comment_id=1174865305875015&reply_comment_id=1176092372418975&total_comments=1&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Conversation with Bryan of Sui Generis Blog about starters and agitation. 11/09/2015.]</ref>. If agitation is not possible for whatever reason, a successful starter can be made without agitation. Sam Aeschlimann reported good success with ''Lactobacillus'' starters that are not agitated <ref name="Sam_starter2"></ref>.
Although ''Lactobacillus'' are tolerant of oxygen and oxygen usually does not negatively affect their growth (except in the case of ''L. plantarum'', which has been shown to produce acetic acid when exposed to oxygen <ref name="Quatravaux_plantarum">[http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2672.2006.02955.x/full Examination of Lactobacillus plantarum lactate metabolism side effects in relation to the modulation of aeration parameters. S. Quatravaux, F. Remize, E. Bryckaert, D. Colavizza, J. Guzzo. 2006]</ref><ref name="microbewiki_plantarum"></ref>), it is also generally not needed (an exception to this may be ''L. brevis'', which has been shown to increase growth rates in the presence of oxygen <ref name="brevis_aeration"></ref>). Therefore, it is generally best practice to prevent aerating the starter with an airlock for ''Lactobacillus'' starters. If exposure to air occurs, and the starter does not smell like it has been contaminated by the exposure, then the starter can still be used.
 
* For information on mixed culture starters, see [[Mixed_Cultures#Starters_and_Other_Manufacturer_Tips|Mixed Culture Starters]].
=====Samuel Aeschlimann's Starter Procedures=====
Although 100% apple juice or 100% DME starters will "work" for ''Lactobacillus'' starters, they do not provide optimal growth conditions. [https://eurekabrewing.wordpress.com/2015/05/18/evaluate-starter-media-to-propagate-lactobacillus-sp/ Samuel Aeschlimann from Eureka Brewing Blog] ran a set of experiments that found a DME based recipe for starter wort that produces a very high cell density similar to that of MRS media, which provides optimal growth rates for ''Lactobacillus''.
The recipe for this starter wort is: '''1.040 SG (10°P) Dried Malt Extract wort with 10% apple juice + 20 grams of chalk (CaCO3) per liter + yeast nutrients'''. Regarding the use of chalk, it is the preferred buffer because it does not react with CO2 (unlike baking soda), so it won't be consumed by exposure to air due to CO2 production by the Lacto. It also has a pKa (maximum buffering capacity) of around 4.6, which is ideal for ''Lactobacillus'' growth. The fact that it easily precipitates out also makes it ideal to use as a buffer <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1180630378631841/?comment_id=1181674265194119&reply_comment_id=1181743348520544&comment_tracking=%7B%22tn%22%3A%22R%22%7D Conversation with Bryan of Sui Generis Blog regarding the use of chalk as a buffer in Lacto starters. 11/20/2015.]</ref>. Jeff Mello from [[Bootleg Biology]] suggests and Nick Impellitteri from [[The Yeast Bay]] suggest that using the smaller amount of 2 grams of CaCO3 per liter is preferable because that amount is easier to precipitate out of the starter and avoid pitching into the beer (the growth differences from using less chalk has not been tested though) <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1369904163037794/?comment_id=1370329352995275&reply_comment_id=1372184639476413&comment_tracking=%7B%22tn%22%3A%22R%22%7D Conversation with Jeff Mello on MTF regarding using less chalk in LAB starters. 08/10/2016.]</ref><ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1619935741367967/?comment_id=1619986154696259&reply_comment_id=1619991214695753&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Impellitteri, Nick. Milk The Funk Facebook group. 03/19/2017.]</ref>. To create a 1 liter starter for 20 liters of wort, follow these directions:
# Add 100 grams of DME to around 900 mL of water and heat pasteurize/boil as you would normally do for a starter. This should make 1.040 SG (10°P) starter wort.
<blockquote>
There is a fair bit of research into hop tolerance out there; its it's not a simple topic as a number of factors come into play to produce hop tolerance. To make things even more complicated, hop tolerance is an inducable inducible trait in many ''Lactobacillus'' species - meaning that a seemingly susceptible strain can become resistant by culturing in ever-increasing doses, and a seemingly resistant strain can become susceptible after a generation or four in a hop-free media.
I've been trying to generate a permanently high-alpha acid resistant lacto strain for a few months now. I've been culturing ''L. brevis '' in escalating IBU wort (starting at 10, currently at 25). Every 4th generation (1 generation = a subculture of a stationary-phase lacto culture, not as in # cell divisions) I pass it through 2 generations of an IBU-free media to try and select for strains which maintain this resistance. This seems to have worked up to ~18 IBU (update: 20-30 IBU), but past that point the resistance appears to remain inducableinducible. I'm hoping a few more generations will provide me with a permanently tolerant strain. Update: I had made a strong (~80ibu) wort that I diluted with unhopped wort. I would grow the ''Lactobacillus'' for a few passages (1 passage = grow culture to completion, then dilute ~1:100 into fresh wort to start next passage) at a set the IBU level, then passage to a wort 3 or so IBU higher. I did 50-60 generations before I got to the high IBU levels (~3 months, 1-2 days per generation). I never did anything to determine how much of that resistance was inheritable <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1421792324515644/?comment_id=1422244054470471&reply_comment_id=1422263561135187&comment_tracking=%7B%22tn%22%3A%22R6%22%7D Conversation 3 with Bryan of Sui Generis Blog on Milk The Funk regarding Lactobacillus hop tolerance. 09/30/2016.]</ref>.
There are some other options; I've purified (but didn't keep - doh) some pretty resistant strains from grain by by making plates where you half-fill a plate, on an angle, with a high-IBU wort, and then overlay that with a no-IBU wort. This gives you a gradient plate, with low-IBUs on the end where the hopped-wort layer is thinnest and high IBUs where it is thickest. Some of those strains were resistant to over 30IBU, but being early in my yeast farming days I didn't bother keeping those <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1002795743081973/?comment_id=1003625646332316&offset=0&total_comments=16&comment_tracking=%7B%22tn%22%3A%22R%22%7D Conversation 1 with Bryan of Sui Generis Blog on Milk The Funk regarding Lactobacillus hop tolerance. 01/19/2015.]</ref>.
Hops contain multiple compounds which are bacteriostatic. Alpha acids are the best understood, but other compounds such as beta acids, a number of polyphenols (e.g. xanthohumol), and even some of the aromatic oils (e.g. humulene) have been found to have some inhibitory effects on ''lactobacilli''. The later compounds (especially the beta acids) are why aged hops retain inhibitory characteristics, despite being nearly devoid of alpha acids. In all cases these compounds appear to inhibit the bacteria in the same way - all of these compounds contain fairly large, flat-ish, hydrophobic regions. These regions do not "like" to be in water, and thus will be driven into the hydrophobic core of the bacterial plasma membrane. This opens minute holes in the membrane which prevents the bacteria from maintaining ion (in particular, proton) gradients, leading to suppression of growth and even death of the bacteria.
Hop resistance is generally due to the induced expression of "multi-drug transport" (MDT) genes, which are "pumps" that recognize the general chemical signature of membrane-disruptive compounds, and then pump them out of the cell. Other mechanisms may also be involved - a few papers have identified changes in the lipid make-up of the plasma membrane, which may increase stability. This change also occurs in response to alcohol (to improve stability), so its not clear if that particular change has anything to do with hop resistance.
Lactobacilli usually don't have these MDT genes 'on', which is why a lot of strains won't do well with hops in the first batch of beer, but over time become more and more tolerant as they increase expression of the MDT's. The overall MDT expression level, in theory, determines the maximum resistance of the bacteria. In the case of my experiments, I'm looking for mutants whose MDT's are permanently stuck 'on' for the resistant strain and 'off' for the sensitive strain <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1143165635711649/?comment_id=1155715074456705&offset=0&total_comments=50&comment_tracking=%7B%22tn%22%3A%22R0%22%7D Conversation 2 with Bryan of Sui Generis Blog on Milk The Funk regarding Lactobacillus hop tolerance. 09/28/2015.]</ref>.
</blockquote>
 
Hop tolerance is not only species dependent, but is also strain dependent. For example, a dissertation by F.J. Methner measured the pH drop of wort that started at a pH of 5.55 from day 3 to day 14 for several strains of ''L. brevis'' at different IBU levels (7,9,11,13 and 18 IBU's). One strain of ''L. brevis'' eventually got down to a pH of 3.8 at day 14 with 7 IBU's, while another strain got down to 3.3 pH at day 14 (with other strains in-between those numbers). At 18 IBU, the relatively hop intolerant ''L. brevis'' strain got down to only 4.2 pH, while another strain got down to 3.7. In general, the higher the IBU, the slower the pH drop. Interestingly, another species called ''L. coryniformis'' was shown to be more hop tolerant than ''L. brevis''. ''L. coryniformis'' dropped the 18 IBU wort down to 3.6 pH over 14 days <ref name="Methner">[https://www.facebook.com/groups/MilkTheFunk/permalink/1537381402956735/ Methner, F.D. Uber Die Aromabildung beim berliner weissebier unter besonderer berucksichtigung von sauren and estern (data reported and translated by Benedikt Rausch on Milk THe Funk Facebook group). 1987.]</ref>.
 
Methner's data is shown below; graphs created by Benedikt Rausch <ref name="Methner" />. Y axis = pH, X axis = days.
 
<gallery>
File:Methner 18IBU.JPG|'''7 IBU'''
File:Methner 18IBU.JPG|'''9 IBU'''
File:Methner 18IBU.JPG|'''11 IBU'''
File:Methner 18IBU.JPG|'''13 IBU'''
File:Methner 18IBU.JPG|'''18 IBU'''
</gallery>
::'''L70''': ''L. coryniformis''
::'''L14, L18, L22, L29, L88, L92''': ''L. Brevis''
See also:
* [[Hops#Antimicrobial_Properties|Hops antimicrobial properties]].
* [http://www.garshol.priv.no/blog/337.html How hops prevent infection, by Lars Garshol].
* [https://www.youtube.com/watch?v=J2g5P7ZlGn4 Per Buer's Video Demonstration of how dry hopping inhibits ''Lactobacillus''.]
* [https://www.ratebeer.com/forums/lab-and-hops_289071.htm "CLevar" on Ratebeer.com data point on ''Lactobacillus'' being inhibited by hops, but not as much by iso-alpha acid hop extract.]
====Storage====
* See [http://basementbrewlab.com/lab/lab-media/sla/ Rogosa SL Agar (Lactobacillus); Basement Brew Lab, by Dustin Metzger] for more information.
 
====Effects on Mixed Fermentation====
The presence of ''Lactobacillus'' can stall or slow yeast fermentation. This is likely a combination of low pH as well as the ability of lactic acid to change the way yeast ferments. Normally, yeast will ferment glucose first before any other sugars that are also available. The presence of lactic acid appears to change the way yeast ferments by allowing them to consume multiple types of sugars regardless of whether or not glucose is preset. See [[Lactic Acid]] for more information.
== Commercially available Lactobacillus strains and their pH change over time ==
| Enterococcus faecalis <ref name="fao"></ref> || ||
|}
 
===Sugar Utilization===
''Lactobacillus'' generally prefers glucose, fructose, and maltose, and does not ferment maltotriose. Some species may prefer certain types of sugars over others. For example ''L. plantarum'' ferments glucose first, and then fructose if it is available. ''L. reuteri'' ferments maltose first, while ''L. brevis'' feeds on maltose, glucose, and fructose. Disaccharides such as sucrose and maltose enter the cells through specific types of membrane transport proteins called permeases, and are broken down into monosaccharides through phosphorolysis before they enter the normal carbohydrate metabolic pathway <ref name="peyer_review"></ref>. Peak sugar consumption without competition from yeast is typically 48 hours, and very little alcohol or CO2 is produced (around 0.10-0.30% ABV, far less than the 0.5% required for non-alcoholic drinks). Consumption of sugars occurs mainly during the 48 hour growth period, but also occurs after growth has stopped. No more than 0.5-1°P worth of sugar is consumed by ''Lactobacillus''. Rather than high residual sugar concentration being the limiting factor on growth it is thought that low pH and other metabolic byproducts weaken and finally stop the growth of ''Lactobacillus'' <ref name="Peyer"></ref>. For a chart and in depth discussion on what types of sugars are fermentable by different species of ''Lactobacillus'', as well as charts on secondary metabolites, see [http://phdinbeer.com/2015/04/13/physiology-of-flavors-in-beer-lactobacillus-species/ Matt Humbard's ''Physiology of Flavors in Beer – Lactobacillus Species'' blog article].
 
A small number of strains of ''Lactobacillus'' can also break down polysaccharides and starches. They are referred to as "amylolytic LAB". They generally belong to the species ''Lb. manihotivorans'', ''L. fermentum'', ''L. amylovorus'', ''L. amylophilus'', ''L. plantarum'' or ''L. amylolyticus''. This seems to be associated with a gene called "amyA", which encodes for extracellular alpha-amylase activity, as well as alpha-glucosidase, neopullulanase, amylopectin phosphorylase, and maltose phosphorylase. This activity is limited by high amounts of glucose, maltose, or sucrose <ref name="peyer_review"></ref>. Some species can also produce beta-glucosidase capable of breaking down monoglycosides (see [[Glycosides]]), but not diglycosides. The activity of both alpha and beta-glucosidase enzymes are stable at low pH ranges of 3-4, are generally encouraged by increasing percentages of alcohol all the way up to 12% v/v, and are optimal at 35-45°C (depending on strain) <ref>[http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2672.2005.02707.x/full Screening of Lactobacillus spp. and Pediococcus spp. for glycosidase activities that are important in oenology. A. Grimaldi, E. Bartowsky, V. Jiranek. 2005. DOI: 10.1111/j.1365-2672.2005.02707.x.]</ref>.
 
====100% Lactobacillus Fermentation====
The amount of CO2 produced is very small in heterofermentative species. Lance Shaner of Omega Yeast Labs noted that although ''L. brevis'' is classified as obligatory heterofermentative, the human eye cannot detect any CO2 production in the Omega Yeast Lactobacillus blend (OYL-605). Lance still needs to test this blend to see if it produces any CO2 at all. There have been reliable reports of pure ''Lactobacillus brevis'' cultures producing a layer of bubbles on the surface of wort if roused <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1354678291227048/?comment_id=1354678411227036&reply_comment_id=1355288821165995&notif_t=group_comment_reply&notif_id=1468974761019794# Conversation with Richard Preiss on MTF regarding pure Lactobacillus fermentation. 07/19/2016.]</ref>. It is clear though that any type of ''Lactobacillus'', regardless of whether it is heterofermentative or homofermentative, cannot produce a krausen. Krausens are sometimes seen even with the use of commercially available ''Lactobacillus'' cultures and good sanitation techniques. If a krausen develops in wort when it is the only culture that is pitched, this is indicative of cross contamination of ''Saccharomyces'' or ''Brettanomyces'' in either the wort, or the ''Lactobacillus'' culture itself <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1083842231643990/?comment_id=1084646124896934&offset=0&total_comments=26&comment_tracking=%7B%22tn%22%3A%22R8%22%7D Discussion with Lance Shaner on MTF. 6/7/2015.]</ref>. In addition to this, heterolactic fermentation by ''Lactobacillus'' can only produce 10-20% of the ethanol that Saccharomyces can produce <ref name="PhysioLacto">[http://phdinbeer.com/2015/04/13/physiology-of-flavors-in-beer-lactobacillus-species/ Humbard, Matt. Physiology of Flavors in Beer – Lactobacillus Species. Retrieved 6/14/2015.]</ref>, therefore a high level of attenuation cannot be achieved by ''Lactobacillus'' and is again a sign of cross contamination by yeast.
Recent studies on lactic acid fermented malt beverages shows that ''Lactobacillus'' produces only about 0.1% ABV, producing "non-alcoholic" fermented malt beverages <ref name="Dongmo" /><ref name="Peyer" />. Elde Arendt, a brewing scientist that specializes in ''Lactobacillus'' presented her work at the Belgian Brewing Conference 2015. In it she explained that LAB will only ferment 0.5°P of wort regardless of the gravity of that wort. When asked at the end of the presentation why ''Lactobacillus'' only ferments ~0.5°P (note that Shaner's experiment shows ''Lactobacillus'' fermenting ~1°P, although this may be due to a margin of error since Shaner only performed this experiment once), considering that ''Lactobacillus'' ferments maltose and there is plenty of maltose in wort, Arendt responded that she believes that the bacteria reaches max cell density in the wort with relatively little sugar requirements (~16 mins in and ~25 mins in):
<youtube>9a-ZpF2LDm8</youtube>
* See also [[100% Lactobacillus Fermentation]].
===Sugar Utilization and Primary/Secondary Metabolites=======Primary Metabolites====Lactic acid is the primary metabolite for ''Lactobacillus'' generally prefers glucose, fructose, as well as CO2 and maltoseethanol/acetate (acetic acid) in heterofermentative species. Acid production is at it's highest during the exponential growth phase, but continues into the stationary and does not ferment maltotriosedecline phases. Typically just under 50% of the lactic acid produced is L-lactic acid (more nutritionally relevant) while the slight majority is D-lactic acid <ref name="Peyer"></ref>. Some The amount of lactic and acetic acids produced varies from species to species may prefer certain types of sugars over others. For example , the referenced study showed that ''L. plantarum'' ferments glucose firstproduces more than twice the amount of lactic acid than ''L. brevis'', and then fructose if it is available. ''L. reuteri'' ferments maltose first, while produced slightly more lactic acid than ''L. brevis'' feeds on maltose, glucose, and fructose. Disaccharides such ''L. reuteri'' produced around twice as sucrose and maltose enter the cells through specific types of membrane transport proteins called permeasesmuch acetic acid than ''L. brevis'', and are broken down into monosaccharides through phosphorolysis before they enter the normal carbohydrate metabolic pathway <ref name="peyer_review"></ref>''L. Peak sugar consumption without competition from yeast is typically 48 hours, and plantarum'' produced very little alcohol or CO2 is produced (around 0.10-0.30% ABV, far less than the 0.5% required for non-alcoholic drinks)acetic acid. Consumption The small amount of sugars occurs mainly acetic acid produced by ''L. plantarum'' in this study was explained by oxygen exposure during sampling, while the 48 hour growth period, but also occurs after growth has stopped. No more than 0.5-1°P worth of sugar is consumed by obligate heterofermentative species (''LactobacillusL. reuteri''. Rather than high residual sugar concentration being the limiting factor on growth it is thought that low pH and other metabolic byproducts weaken and finally stop the growth of ''LactobacillusL. brevis'' ) produced acetic acid as a direct result of their heterolactic fermentation <ref name="Peyer"></ref>. For a chart and in depth discussion on what types of sugars are fermentable by different species of ''Lactobacillus'', as well as charts on secondary metabolites, see [http://phdinbeer.com/2015/04/13/physiology-of-flavors-in-beer-lactobacillus-species/ Matt Humbard's ''Physiology of Flavors in Beer – Lactobacillus Species'' blog article].
A small number of strains ====Secondary Metabolites====Both primary and secondary metabolites play a large role in the flavor and aroma profile of wort fermented with ''Lactobacillus'' can also break down polysaccharides and starches. They Secondary metabolites are compounds that are referred not directly related to as "amylolytic LAB"the growth of an organism, but often assist with survival <ref>[http://www.ncbi.nlm.nih.gov/pubmed/11036689 The natural functions of secondary metabolites. They generally belong to the species ''Lb. manihotivorans''Demain AL, ''LFang A. fermentum'', ''L2000. amylovorus'', ''L]</ref>. amylophilus'' These secondary metabolites are produced by the pathways mentioned above, ''Land different strains probably regulate the enzymes involved in various pathways differently and produce different secondary metabolites <ref>Private correspondence with Richard Preiss from Dan Pixley. plantarum'' or ''L 12/29/2015. amylolyticus''</ref>. This seems Thus, different species and strains can produce a wide variety of flavors and aromas (compare this to be associated with a gene called "amyA", food grade lactic acid in which encodes for extracellular alpha-amylase activity, as well as alpha-glucosidase, neopullulanase, amylopectin phosphorylase, and maltose phosphorylasenone of these secondary metabolites exist). This activity is limited by high amounts These secondary metabolite are the result of glucose, maltose, or sucrose carbohydrate fermentation and amino acid metabolism <ref name="peyer_review"></ref>. Major secondary metabolites that
Many strains of An example from one study showed that ''LactobacillusL. plantarum'' and other lactic acid bacteria can produce tannaseproduced significantly more diacetyl, which is an enzyme that breaks down a certain class of tannins called "hydrolizable tannins" acetoin (for exampleyogurt-like flavor), tannic acid). The enzymatic breakdown of tannins provides a food source for the and acetaldehyde than ''LactobacillusL. reuteri''. In the cited study, a strain of and ''L. plantarumbrevis'' was selected out . These three compounds were associated with dairy-related notes of 47 other tannase producing "buttery", "lactic", and "yogurt" flavors identified during sensory testing <ref name="Peyer"></ref>. Some LAB as being can release these compounds through the highest producer catabolism of this enzymecitric acid, which is found in wort. Although the optimum pH for tannase Ester production is 5-8generally insignificant, although significant ester formation has been found during malolactic fermentation in red wines, it is also at least 50% active at a pH of 3-7 and a temperature of 15-30°C. Tannase ethyl acetate has been found to be produced as a product for removing haze in food products such as iced tea, wine, and beer malt based beverages <refname="peyer_review">[http://www.asbcnetsciencedirect.org/publicationscom/journalscience/volarticle/2016pii/Pages/ASBCJ-2016-4298-01.aspx Purification and Characteristics of Tannase Produced by S0924224415300625 Lactic Acid Bacteria, Lactobacillus plantarum H78as Sensory Biomodulators for Fermented Cereal-Based Beverages. Mari MatsudaLorenzo C. Peyer , Yayoi HiroseEmanuele Zannini , and Makoto KanauchiElke K. Arendt. 2016.]</ref>. Some strains may also produce fusel alcohols and other off-flavors. For example the referenced study found an accumulation of the fusel alcohol n-Porponal in the sample of ''L. reuteri'', and a small decrease of isovaleric acid coupled with a small increase of [https://en.wikipedia.org/wiki/Hexanoic_acid hexanoic acid] by ''L. brevis'', ''L. plantarum'', and ''L. reuteri'' (only 0.25-0.32 mg/L was found, and the flavor threshold of hexanoic acid is 5.4 mg/L <ref>[http://www.beveragedailyleffingwell.com/R-Dodorthre.htm Leffingwell & Associates website. Odor Thresholds. Retrieved 12/30/2015.]</ref>) <ref name="Peyer"></New-enzyme-aims-to-take-ref>. Heterofermentative species can also produce [[Tetrahydropyridine|tetrahydropyridines (THP)]], which is the-haze-out-cause of"mousy" off-iced-tea flavors <ref name="Costello">[http://wwwpubs.beveragedailyacs.comorg/doi/abs/R-D10.1021/Newjf020341r Mousy Off-enzymeFlavor of Wine:  Precursors and Biosynthesis of the Causative N-aimsHeterocycles 2-toEthyltetrahydropyridine, 2-takeAcetyltetrahydropyridine, and 2-theAcetyl-haze1-out-of-iced-tea"pyrroline by Lactobacillus hilgardii DSM 20176. BeveragedailyPeter J.comCostello and Paul A. Henschke. Guy Montague-James2002. 04]</04/2011ref>. Retrieved 011/09/2016.]Aldehydes (2-methyl-1-propanal, 2-methyl-1-butanal, 3-methyl-1-butanal) and their associated non-fusel alcohols (2-methyl-1-propanol, 2-methyl-1-butanol, and 3-methyl-1-butanol) can be produced from amino acids such as leucine, isoleucine, and valine to form fruity flavors <ref name="peyer_review"></ref>. Some A few species, especially most strains of ''LactobacillusL. fermentum'' , and some strains could therefore have a positive effect on beer clarity by breaking down some haze forming tannins <ref>[https://wwwof ''L.facebookdelbrueckii subsp.com/groups/MilkTheFunk/permalink/1464383586923184/?comment_id=1465361093492100&reply_comment_id=1465496463478563&comment_tracking=%7B%22tn%22%3A%22R3%22%7D Review bulgaricus'', can produce ropiness in the form of this entry by Mike Lentz via MTF. 11/10/2016.exopolysaccharides, similar to [[Pediococcus]]<ref name="peyer_review"></ref>.
Lactic acid is the primary metabolite for [http://www.sciencedirect.com/science/article/pii/S0308814617302911#t0005 Dongmo et al. (2017)] found 56 volatile flavor compounds, including various esters, alcohols, ketones, aldehydes, acids, ethers compounds, sulfur compounds, heterocyclic compounds, phenols, terpenes, lactones, and several unidentified compounds. Key compounds produced by ''Lactobacillus''include acetaldehyde, β-Damascenone, furaneol, phenylacetic acid, 2-phenylethanol, 4-vinylguaiacol, sotolon, methional, vanillin, as well as CO2 and ethanol/acetate (acetic acid) in heterofermentative species, nor-furaneol, guaiacol and ethyl 2-methylbutanoate. Acid production is at it's highest during Acetaldehyde was the exponential growth phase, but continues into the stationary most impactful aroma compound found followed by propan-1-ol and decline phasesγ-dodecalactone. Typically just under 50% of the lactic acid Acetaldehyde was generally produced is in much higher amounts (~23-64 µg/L-lactic acid (more nutritionally relevant) while by the slight majority is D-lactic acid <ref name="Peyer"></ref>. The amount select strains of lactic and acetic acids produced varies from species to species. For example, the referenced study showed that ''L. plantarum'' produces more than twice the amount of lactic acid than , while ''L. brevisamylolyticus'', and ''L. reuteribrevis'' produced slightly more lactic acid than ''only 1.5-3 µg/L. brevis'' In fact, the levels of all of these compounds differed significantly based on the species and strain. The selected strains of ''L. reuteribrevis'' produced around twice were associated as much having worse aromas that were dominated by methional (cooked potatoes), acetic acid than ''L. brevis''(vinegar), and nor-furaneol (caramel-like). The ''L. plantarum'' produced very little acetic acidstrains selected were identified as producing more positive aromas from compounds such as β-damascenone (apple/fruit juice), furaneol (strawberry), 2-phenylethanol (rose/caramel) and ethyl 2-methylbutanoate (citrus) Small but significant amounts of linalool and geraniol were also found, which are normally terpenes found in [[Hops|hops]]. The small amount of acetic Vanillan is formed from ferulic acid produced by some ''L. plantarumLactobacillus'' in this study was explained by oxygen exposure during sampling, while the obligate heterofermentative species ('as well as 'L. reuteri'Oenococcus oeni' and ''L. brevis'') produced acetic acid as a direct result of their heterolactic fermentation <ref name="PeyerDongmo">[http://www.sciencedirect.com/science/article/pii/S0308814617302911 Key volatile aroma compounds of lactic acid fermented malt based beverages – impact of lactic acid bacteria strains. Sorelle Nsogning Dongmo, Bertram Sacher, Hubert Kollmannsberger, Thomas Becker. 2017. doi:http://dx.doi.org/10.1016/j.foodchem.2017.02.091.]</ref>.
Both primary The type of grain that the ''Lactobacillus'' is fermented in may also play a role in the types and amounts of secondary metabolites play that are produced. One study compared volatile acids produced by a probiotic strain of ''L. plantarum'' (NCIMB 8826) when fermented in oats, barley, malted barley, and wheat. In oats, there was slight increase in oleic acid and linoleic acid and a large role decrease when fermented in wheat, barley, or malted barley. In malted barley, there were small increases in the flavor active compounds such as furfural ("almond" flavor), 2-ethoxyethyl acetate and aroma profile of wort isoamyl alcohol, but little to none detected when fermented with in oats, wheat, or unmalted barley. Acetic acid production was higher in barley and malted barley than it was in oats and wheat. Many other organic acids in the oats, wheat, barley, and malted barley were supposedly taken up by the ''LactobacillusL. plantarum''during fermentation. Secondary metabolites are compounds In barley, there were trace amounts of new acids created that are were not directly related to growth of an organism, but often assist with survival already in the barley itself <ref>[http://www.ncbisciencedirect.nlm.nih.govcom/science/pubmedarticle/11036689 The natural functions of secondary metabolites. Demain AL, Fang A. 2000.]<pii/ref>. These secondary metabolites are S0308814609004373 Volatile compounds produced by the pathways mentioned aboveprobiotic strain Lactobacillus plantarum NCIMB 8826 in cereal-based substrates Ivan Salmeron, and different strains probably regulate the enzymes involved in various pathways differently and produce different secondary metabolites <ref>Private correspondence with Richard Preiss from Dan PixleyPablo Fuciños, Dimitris Charalampopoulos, Severino S. Pandiella. 12/29/20152009.]</ref>. ThusSome species of ''Lactobacillus'', different species including ''L. lactis'' and strains can ''L. plantarum'', produce a wide variety of flavors and aromas diacetyl (compare this which can be reduced to food grade lactic acid in which none of these secondary metabolites existacetoin and 2,3-butanediol)as an intermediate metabolite from consuming sugar, citrate, and amino acids. These secondary metabolite However, citrate levels are the result of carbohydrate fermentation rather low in malted barley (but higher in sorghum), and diacetyl production has been observed to be very low in barley and amino acid metabolism oat based worts <ref name="peyer_review"></ref>.
An example from one study showed that ''L. plantarum'' Aging has a large impact on the aromas and flavors produced significantly more diacetyl, acetoin (yogurt-like flavor), and acetaldehyde than by ''L. reuteriLactobacillus'' fermentation over time and ''L. brevis''. These three compounds were associated with dairy-related notes is typically influenced by temperature of "buttery"the environment, "lactic"oxygen exposure, and "yogurt" flavors identified during sensory testing <ref name="Peyer"></ref>. Some LAB can release these compounds through the catabolism byproducts of citric acid, which is found in wortfermentation. Ester production is generally insignificantGenerally, although significant ester formation fermentation has been found during malolactic fermentation in red wines, a positive effect on preserving some aroma and ethyl acetate has been found to be produced in malt based beverages <ref name="peyer_review">[http://www.sciencedirect.com/science/article/pii/S0924224415300625 Lactic Acid Bacteria as Sensory Biomodulators for Fermented Cereal-Based Beveragesflavor compounds. Lorenzo C. Peyer , Emanuele Zannini Other compounds may change, Elke K. Arendt. 2016.]</ref>. Some strains may also produce fusel alcohols causing aroma and other off-flavorsflavor changes. For example the referenced , one study found an accumulation of the fusel alcohol n-Porponal in the sample of characterized wort freshly fermented with ''L. reuteriplantarum''as "butter" and honey", and a small decrease of isovaleric acid coupled with a small increase of [https://enwhen aged as "yogurt" and "sour".wikipedia.org/wiki/Hexanoic_acid hexanoic acid] by ''L. brevis'' In the same study, ''L. plantarum'', and ''L. reuteri'' (only 0.25-0.32 mg/L was found, and the flavor threshold of hexanoic acid is 5.4 mg/L <ref>[http://www.leffingwell.com/odorthre.htm Leffingwell & Associates website. Odor Thresholds. Retrieved 12/30/2015.]</ref>) <ref name=characterized as "Peyersour"></ref>. Heterofermentative species can also produce [[Tetrahydropyridine|tetrahydropyridines (THP)]]when fresh, which is the cause of "mousy" off-flavors <ref name=and "Costellohoney">[http://pubs.acs.org/doi/abs/10.1021/jf020341r Mousy Off-Flavor of Wine:  Precursors and Biosynthesis of the Causative N-Heterocycles 2-Ethyltetrahydropyridine, 2-Acetyltetrahydropyridine, and 2-Acetyl-1-pyrroline by Lactobacillus hilgardii DSM 20176. Peter J. Costello and Paul A. Henschke. 2002.]</ref>. Aldehydes (2-methyl-1-propanal, 2-methyl-1-butanal, 3-methyl-1-butanal) and their associated non-fusel alcohols (2-methyl-1-propanol, 2-methyl-1-butanol, and 3-methyl-1-butanol) can be produced from amino acids such as leucine, isoleucine, and valine to form fruity flavors <ref name="peyer_reviewpungent"></ref>when aged. A few species, especially most strains of ''L. fermentumbrevis''was characterized as "soy sauce" when fresh, and some strains of ''L. delrueckii subsp. bulgaricus'', can produce ropiness in the form of exopolysaccharides, similar to [[Pediococcus]] "yeasty" and "cider" when aged <ref name="peyer_reviewPeyer"></ref>.
The type Many strains of grain that the ''Lactobacillus'' and other lactic acid bacteria can produce tannase, which is fermented in may also play an enzyme that breaks down a certain class of tannins called "hydrolizable tannins" (for example, tannic acid). The enzymatic breakdown of tannins provides a role in food source for the types and amounts of secondary metabolites that are produced''Lactobacillus''. One In the cited study compared volatile acids produced by , a probiotic strain of ''L. plantarum'' (NCIMB 8826) when fermented in oats, barley, malted barley, and wheatwas selected out of 47 other tannase producing LAB as being the highest producer of this enzyme. In oatsAlthough the optimum pH for tannase is 5-8, there was slight increase in oleic acid and linoleic acid it is also at least 50% active at a pH of 3-7 and a decrease when fermented in wheat, barley, or malted barleytemperature of 15-30°C. In malted barley, there were small increases Tannase has been produced as a product for removing haze in flavor active compounds food products such as furfural ("almond" flavor), 2-ethoxyethyl acetate and isoamyl alcohol, but little to none detected when fermented in oatsiced tea, wheatwine, or unmalted barley. Acetic acid production was higher in barley and malted barley than it was in oats and wheat. Many other organic acids in the oats, wheat, barley, and malted barley were supposedly taken up by the ''L. plantarum'' during fermentation. In barley, there were trace amounts of new acids created that were not already in the barley itself beer <ref>[http://www.sciencedirectasbcnet.comorg/publications/journal/sciencevol/article2016/piiPages/S0308814609004373 Volatile compounds produced ASBCJ-2016-4298-01.aspx Purification and Characteristics of Tannase Produced by the probiotic strain Lactic Acid Bacteria, Lactobacillus plantarum NCIMB 8826 in cereal-based substrates Ivan SalmeronH78. Mari Matsuda, Pablo FuciñosYayoi Hirose, Dimitris Charalampopoulos, Severino S. Pandiellaand Makoto Kanauchi. 20092016.]</ref><ref>[http://www.beveragedaily. Some some species com/R-D/New-enzyme-aims-to-take-the-haze-out-of ''Lactobacillus'', including ''L-iced-tea "http://www. lactis'' and ''Lbeveragedaily. plantarum'', produce diacetyl (which can be reduced com/R-D/New-enzyme-aims-to acetoin and 2,3-butanediol) as an intermediate metabolite from consuming sugar, citrate, and amino acidstake-the-haze-out-of-iced-tea". Beveragedaily.com. Guy Montague-James. 04/04/2011. However, citrate levels are rather low in malted barley (but higher in sorghum), and diacetyl production has been observed to be very low in barley and oat based worts <ref name="peyer_review">Retrieved 011/09/2016.]</ref>.  Aging has a large impact on the aromas and flavors produced by Some ''Lactobacillus'' fermentation over time and is typically influenced by temperature of the environment, oxygen exposure, and the byproducts of fermentation. Generally, fermentation has strains could therefore have a positive effect on preserving beer clarity by breaking down some aroma and flavor compoundshaze forming tannins <ref>[https://www. Other compounds may change, causing aroma and flavor changesfacebook. For example, one study characterized wort freshly fermented with ''L. plantarum'' as "butter" and honey", and when aged as "yogurt" and "sour"com/groups/MilkTheFunk/permalink/1464383586923184/?comment_id=1465361093492100&reply_comment_id=1465496463478563&comment_tracking=%7B%22tn%22%3A%22R3%22%7D Review of this entry by Mike Lentz via MTF. In the same study, ''L11/10/2016. reuteri'' was characterized as "sour" when fresh, and "honey" and "pungent" when aged. ''L. brevis'' was characterized as "soy sauce" when fresh, and "yeasty" and "cider" when aged <ref name="Peyer">]</ref>.
See the [[Lactobacillus#100.25_Lactobacillus_Fermentation|Elke Arendt video presentation above]] on the referenced study, starting at ~14:45.
===External Resources===
* [https://www.microbes.info/resource-topic/lactobacillus-eubacteria-microorganisms-general-microbiology Microbes.info links to species databases and microbiology resources.]
* [https://matthumbard.wordpress.com/2015/04/13/physiology-of-flavors-in-beer-lactobacillus-species/ Physiology of Flavors in Beer – Lactobacillus Species] - Matt Humbard's overview of different species of Lactobacillus physiology, discussion on homofermentative vs heterofermentative physiology, which species can ferment different types of sugars, and secondary metabolites. Extensive data points included.
* [http://phdinbeer.com/2015/08/05/beer-microbiology-lactobacillus-ph-expeirment/ Beer Microbiology – Lactobacillus pH experiment] - Matt Humbard's experiment to determine final pH of individual ''Lactobacillus'' strains used in the graphs on this page.
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