Impact of pH on Changing the Fatty Acid Composition and Growth of Lactobacillus plantarum and Lactobacillus casei

Fatty acid composition and growth of Lactobacillus plantarum and Lactobacillus casei, were studied at different pHs of the culture media in a fermenter with according interest in lactobacillic acid production of the cultures. In this study, we notice, the increasing of total fatty acid content of the bacterial cells with increasing culture age. The production of lactobacillic acid was affected in lactobacillus by culture age and pH of the media, but in a very different manner. In Lb. casei cultures, the relative proportion of lactobacillic acid was highest when the pH was lowest (pH 4.5), whereas in Lb. plantarum cultures, the proportion of lactobacillic acid was highest at pH 7.0. The pH of the medium affected not only the relative proportion of lactobacillic acid, but also biomass production and total fatty acid accumulation of the cultures. Thus, by controlling the pH of the cultures, the volumetric yield of lactobacillic acid could be improved considerably compared to cultures without pH control.