Heterofermentative metabolism of glucose and ribose and utilisation of citrate by the smooth biotype of Lactobacillus amylovorus NCFB 2745

Lactobacillus amylovorus NCFB 2745 exhibits a rough colony morphology, ferm ents glucose homofermentatively and cannot utilise ribose. After five trans fers in de Man Rogosa and Sharpe media (containing glucose and citrate) Lb. amylovorus 2745 appears smooth on agar plates; smooth cultures reverted to rough by culturing in aerobic conditions. The smooth type shows patterns o f fermentation that are typical of a heterofermentative lactobacillus. Thus , the smooth morphotype produces CO2 and ethanol in addition to lactate and is able to ferment ribose. The switch in metabolism to the smooth form is accompanied by an increase in phosphoketolase and a reduction in aldolase e nzyme activities. Citrate also has effects on growth rates and end-metaboli tes.