Changes

Most studies on microbe populations on malt have been done using lab media such as agar plates, which are thought to not be as effective at analyzing the overall population as recent DNA sequencing approaches, such as "454 amplicon pyrosequencing". A recent study took this approach to measuring bacterial diversity on barley and malt (fungi was not analysed). This study looked at two malting houses during two different years (2010 and 2011). It found that on malt, the largest communities of bacteria were found to include ''Enterobacter'', ''Sphingobacterium'', ''Weissella'', ''Lactobacillus'', ''Lactococcus'', ''Streptococcus'', ''Acinetobacter'', and ''Strenotrophomonas'', ''Leuconostoc'', ''Pseudomonas'', ''Wautersiella'', ''Cryseobacterium'', ''Curtobacterium'', and ''Propionobacterium'' <ref name="Lievens2">[http://www.ncbi.nlm.nih.gov/pubmed/24387850 Bacterial community dynamics during industrial malting, with an emphasis on lactic acid bacteria. A. Justé, S. Malfliet, M. Waud, S. Crauwels, L. De Cooman, G. Aerts, T.L. Marsh, S. Ruyters, K. Willems, P. Busschaerta, B. Lievens. 2014.]</ref>.  ''Enterobacter spp'' specifically has been identified as a beer spoilage agent, which produces high amounts of 2,3-Butanediol (buttery taste <ref>[http://www.thegoodscentscompany.com/data/rw1161171.html The Good Scents Co. 2,3-butane diol. Retrieved 10/15/2015.]</ref>), as well as acetoin, lactic acid, acetic acid, succinic acid, high alcohols such as n-propanol, iso-butanol, D-amyl-alcohol, isoamyl alcohol, and sulfur compounds such as dimethyl sulfide (DMS), all under both aerobic and semi-aerobic conditions <ref>[http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1992.tb01126.x/epdf Synthesis of Aroma Compounds By Wort Enterobacteria During First Stage of Lambic Fermentation. H. Martens, E. Dawoud, and H. Verachtert. Jan 1992.]</ref><ref name="Bamforth"></ref>. ''Enterobacter'' is not inhibited by hops, but is inhibited by ethanol and a pH of 4.4. ''Acinetobacter'' has also been shown to produce DMS in wort, however they are strictly aerobic and encountered in much smaller amounts than ''Enterobacter'' in brewing <ref>[http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1974.tb03629.x/abstract WORT ENTEROBACTERIA—A REVIEW. F. G. Priest, M. A. Cowbourne and J. S. Hough. 2013.]</ref>.