FURTHER OBSERVATIONS ON THE BEHAVIOUR OFACETOBACTER TURBIDANS

Open Access
Publisher Website
Google Scholar
Abstract
In a recent communication (this Journ., 1941, 382; 1942, 82) the authors described the principal characteristics of A. turbidans, a virulent beer disease organism. Further study has now been made of its activities, especially in media produced from malt and from yeast, for its ability to thrive in yeast pressings indicates how readily, having gained access to a brewery, it might establish itself in association with the pitching yeast. Inter alia, the experiments now reported have brought to light additional facts concerning the tolerance of A. turbidans towards hop antiseptic and towards ethyl alcohol. The effect of concentration of yeast-water on the oxidation of alcohol by A. turbidans in a yeast water medium has been ascertained, and the behaviour of the organism towards various sugars in the presence of yeast-water has been studied quantitatively. Although A. turbidans is not suppressed either by a high hop rate or by a high percentage of alcohol in fermentation media, it can be killed in beer by exposure to a temperature of 54°C. (122°F.) for 5 minntes, or to a temperature of 52°C. (125.6°F.) for 10 minutes; hence it could not survive the process of pasteurisation of beer as normally conducted. If young cultures of A. turbidans growing in malt-wort are raised in temperature to 40°C. (104°F.), and maintained at that temperature they give rise to involution forms. A photomicrograph showing such abnormal cells is reproduced at the end of this communication.

This publication has 0 references indexed in Scilit: