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For a general overview of grain in brewing, see [http://www.homebrewtalk.com/wiki/index.php/Grain Homebrew Talk Wiki page on Grain].
The study examined LAB populations specifically due to their potential to help with malt stability and quality <ref>[http://www.researchgate.net/profile/Arja_Laitila/publication/7062169_Lactobacillus_plantarum_and_Pediococcus_pentosaceus_starter_cultures_as_a_tool_for_microflora_management_in_malting_and_for_enhancement_of_malt_processability/links/00b7d529ed5568640a000000.pdf Lactobacillus plantarum and Pediococcus pentosaceus Starter Cultures as a Tool for Microflora Management in Malting and for Enhancement of Malt Processability. ARJA LAITILA, HANNELE SWEINS, ARVI VILPOLA, ERJA KOTAVIITA, JUHANI OLKKU, SILJA HOME, AND AULI HAIKARA. 2006.]</ref>. ''Streptococcus'' was the most abundant genus of bacteria in all samples. In 2010, ''Lactobacillus'' was more abundant than it was in 2011. ''Lactococcus'' and ''Weisella'' were more abundant in 2011 than in 2010. Maltster 1 had a great abundance of both ''Lactococcus'' and ''Weisella'' in 2011 over Maltster 2. In 2010, ''Lactobacillus'' was more abundant for Maltster 2 than it was for Maltster 1. This showed that microbial populations differ not only between harvest years, but also malt houses <ref name="Lievens3"></ref> (~17 mins in).
Another study focused on microbial populations in an American coolship brewery detected only ''Pediococcus'' on grain samples, but the lack of detection of other microbes as attributed to weak amplification <ref>[http://elifesciences.org/content/4/e04634 Mapping microbial ecosystems and spoilage-gene flow in breweries highlights patterns of contamination and resistance. Nicholas A Bokulich, Jordyn Bergsveinson, Barry Ziola, David A Mills. March, 2015.]</ref>.
* [https://lirias.kuleuven.be/bitstream/123456789/323419/2/Juste_et_al._FEMS2011_mout%20definitief.pdf See this study] for a list of microbes that were found on malt using DNA methods.
::<youtube>5mttD027PMU</youtube>
===Mash and Wort===
During mashing, the population of microbes diminishes greatly due to near pasteurization temperatures. However, thermotolerant microbes do survive. These are usually homofermentative LAB <ref name="Bamforth">[http://mmbr.asm.org/content/77/2/157.full#ref-199 The Microbiology of Malting and Brewing. Nicholas A. Bokulicha, and Charles W. Bamforth. June 2013.]</ref>. These microbes can have both positive and negative impact on wort production. Mash acidification by thermotolerant ''L. amylovorus'' has shown to improve enzymatic conversion of starches to sugars, increased extract and fermentability, increased TSN and FAN, and even improved head retention and increased shelf stability <ref>[http://www.asbcnet.org/publications/journal/vol/abstracts/ASBCJ-63-0096.htm Biological Acidification of a Mash Containing 20% Barley Using Lactobacillus amylovorus FST 1.1: Its Effects on Wort and Beer Quality. Deirdre P. Lowe and Helge M. Ulmer. 2005.]</ref>. Bacterial growth during mashing can also have a negative impact. For example, the thermotolerant Gram-positive and facultative anaerobe ''Bacillus coagulans'' can cause the mash to go sour and form nitrosamines. ''B. coagulans'' forms nitrosamines without oxygen between the temperatures of 86°F/30°C and 154°F/68°C, and can withstand a pH of 4.0 or higher <ref>[http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1992.tb01124.x/pdf THE ROLE OF BACILLUS spp. IN N-NITROSAMINE FORMATION DURING WORT PRODUCTION N. A. Smith and P. Smith. 1992.]</ref>. ''Clostridium'', which may not necessarily originate from the malt itself, can create [[Butyric Acid|butyric acid]] off flavors during the mash or during kettle souring <ref>[http://www.asbcnet.org/publications/journal/vol/abstracts/49-02.htm Butyric Acid Off-Flavors in Beer: Origins and Control. D. B. Hawthorne, R. D. Shaw, D. F. Davine, and T. E. Kavanagh, Carlton. 1991.]</ref>. High bacterial growth can cause lautering issues, probably due to the production of dextrans by the bacteria <ref name="Bamforth"></ref>.
==See Also==
===Additional Articles on MTF Wiki===