THE ISOLATION OF LACTIC ACID-PRODUCING BACTERIA FROM BEER

Abstract

The authors are engaged upon a study of “beer disease” bacteria with the principal object of gaining information concerning the control by hops of their development. This subject of beer stability in relation to hops may also involve consideration of the effects of certain other factors, adjustable within limits (e.g., PH value, alcohol content, oxygen tension), which, as the case may be, can operate so as to diminish or to enhance the effect due to hops. For the purposes of this enquiry a representative selection of “beer disease” bacteria in pure culture was required and, in the present paper, a description is given of the isolation from different ales and beers of organisms capable of growth under anaerobic conditions. Nine different beers and one sample of a pitching yeast yielded 34 different cultures. The great majority of these were found to be Lactobacilli but in several cases, where strictly anaerobic conditions were not employed, Acetobacter species were isolated from amongst the preponderating anaerobes. Acetobacter species are not hop-sensitive but, as some of these are virulent “beer disease” organisms, it has been considered of interest to study their characteristics and behaviour and the cultures are being retained for this purpose. Some preliminary observations concerning the principal characteristics of the isolated organisms are recorded. It is proposed to select a number of the more interesting types for purposes of future experimental work.