BIOCHEMICAL PHYSIOLOGY OF OBESUMBACTERIUM PROTEUS, A COMMON BREWERY CONTAMINANT

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Abstract
In defined media, arginine plus either glutamate or aspartate supports growth of Obesumbaeterium proteus but additional amino acids enhance yields. Glucose, fructose, mannose and galactose are rapidly utilized; maltose and starch give slower growth. Fermentation products include acetic, formic, 2-oxoglutaric, pyruvic and succinic acids. With brewer's wort as growth medium, the concentrations of arginine, lysine, NH3, aspartate, serine, tyrosine and leucine decrease whereas several other amino acids increase in concentration. Fermentation products include acetoin, ethanol, lactic acid, fusel alcohols, some volatile acids and dimethylsulphide. Measurements of oxygen uptake by washed suspensions in the presence of a variety of substrates suggest synthesis of (i) a terminal electron transfer chain that is repressed anaerobically and (ii) a glucose oxidase complex. Radio-respirometry indicates that the EMP is not the sole pathway for glucose metabolism. Cytochrome b1 is detected in the bacterial cells but not cytochromes a and c. Glucose represses the activities of several enzymes of the EMP and HMP, but not lactate dehydrogenase and 3 enzymes of the citric acid cycle.