Pediococcus

Pediococcus (often referred to as Pedio) are gram positive lactic acid bacteria (LAB) used in the production of Belgian style beers where additional acidity is desirable. They are often found in gueuze and other Belgian styles of sour beer. Due to their continued metabolism of longer chain polysaccharides, acid production will increase with storage time. Pediococcus species are generally more tolerant of antimicrobial hop acids and higher levels of acidity than Lactobacillus. Pedio can form a pellicle.

Pediococcus may also cause “ropiness” (also called a "sick beer") due to the production of exopolysaccharides. "Ropy" or "sick" beer is more viscous and, in extreme circumstances, can form strands. Sickness effects mostly the mouthfeel and appearance of beer, and may have no influence on the flavor. Pediococcus species can also produce diacetyl with extended storage time. Brettanomyces can break down exopolysaccharides and diacetyl produced by Pediococcus and the two are often used together.

See Lactobacillus, Brettanomyces, Saccharomyces, and Mixed Cultures charts for other commercially available cultures.

Commercial Pediococcus Cultures

Name	Mfg#	Taxonomy	Note
White Labs	WLP661	damnosus	High diacetyl producer and slow growing. Fermentation temp: 70-85°F (21-29.4° C). Attenuation: 65%
Wyeast	5733	damnosus	May cause “ropiness” and produce low levels of diacetyl with extended storage time. Temp range: 60-95° F (15-35° C).
RVA Yeast Labs	RVA 601	damnosus	Lactic acid bacteria used in souring Belgian-style beers such as gueze and Lambic. Acid production increases with storage. Temperature range is 60-95º F.

Manufacturer Tips

Wyeast on 5733

"If using 1 pack of 5733 per 5 gallon batch; and either adding to secondary after alcoholic fermentation is complete, or co-inoculating with a Sacch' strain, then a starter would not be necessary. If you did want or need to propagate, I'd recommend 2 liters of 1.030-1.040 wort per pack, incubated at 80-90*F, without agitation." - Michael Dawson, Wyeast.

"For propagation, we recommend using 1.040 OG wort and incubating at 30-35*C without aeration for 48-96 hours; pH drop will indicate when it's ready to pitch. For co-inoculation or post-primary addition, we recommend 0.5 million cells per mL, which is the equivalent of 1 pack in 5 gallons/20 liters. For larger volumes, you can propagate and inoculate with the starter culture at a rate 2.5-5% of the total volume of the main batch." - Michael Dawson, Wyeast.

White Labs on WLP661

"That one does well in 70-85 deg F. You can do a starter, but you shouldn't have to if you are doing a 5 gallon batch. It does take a while to sour, so just be patient and let it do it's thing." Sarah Neel, Sales and Customer Service, White Labs

Tips From MTF

The Rare Barrel

"We just performed an interesting experiment at The Rare Barrel with pedio. Jay, our head brewer and blender, wanted a more acidic beer that we could use as a blending component while also growing up our diminishing pedio culture. So we racked 2 oak barrels of gold fermented with Brettanomyces claussenii and White Labs Pediococcus damnosus (WLP661) into one of our 30 bbl batches of 12*p gold wort that had been acidified to about 4.5 pH in the kettle using lactic acid (our first hot side experiment!). No oxygen, really wanted to encourage the bacteria. Within 10 days the pH was 3.6 and the gravity 10.7. We were all surprised how quickly the pedio was working. We eventually racked a "splash" of fermenting gold with BSI Brett D and BSI Lacto D to drop the gravity. The beer had a bright acidity quickly and I was surprised at how well rounded the flavors were when we racked into barrels after a month in the fermenting vessel.

This might be a little harder to do at home, but I think there's potential for interesting results. Pediococcus shines long term traditionally so I agree with the posts above, if you're going for quick acidity I'd go lacto, but I plan on playing around with early Pediococcus fermentations at home." - Mike Makris from The Rare Barrel .

Metabolism

Growth and Environment

One study showed that by starting growth in a medium (MRS media that began with a pH of 6.7, and allowing the pH to drop to 4.14 naturally from fermentation, that better growth was observed. The addition of bacteriological peptone, MnSO4, and Tween 80 also increased activity .

P. damnosus is sensitive to environments that contain NaCl, and will not grow with concentrations of 4% NaCl. This species requires an anaerobic environment for growth .

See Also

Additional Articles on MTF Wiki

• Alternative Bacteria Sources