Characterization of Enterobacter agglomerans Variants and Their Importance in Brewing. Robert McCaig and Margaret Morrison, Molson Breweries of Canada Limited, Montreal, Quebec, Canada, H2L 2R5. J. Am. Soc. Brew. Chem. 42:0023, 1984.

The coliform bacterium Enterobacter agglomerans can have significant implications in the brewing process. Three brewing isolates demonstrated differences in carbohydrates utilized, enzyme systems possessed, temperatures of growth, and kinds and amounts of metabolites produced. A more detailed study of the isolates' abilities to reduce dimethyl sulfoxide (DMSO) to dimethyl sulfide (DMS) revealed conversion efficiencies of 55-70%. One isolate was found to metabolize S-methylmethionine (DMSP) to DMS at a low conversion rate of 20%. Growth of isolates in ale fermentations did not significantly change pH, specific gravity, yeast in suspension, or DMSP concentration. Changes were noted in concentrations of DMSO, DMS, and vicinal diketone.

Keywords: Beer, Diacetyl, Dimethyl sulfide, Dimethyl sulfoxide, Enterobacter agglomerans, Physiology