Nutritional requirements and simplified cultivation medium to study growth and energetics of a sourdough lactic acid bacterium Lactobacillus fermentum Ogi E1 during heterolactic fermentation of starch

Aims: Nutritional requirements of Lactobacillus fermentum Ogi E1 were studied in order to define a simplified fermentation medium. Methods and Results: When grown with MRS-medium in 21 bioreactors, a biphasic pattern of growth and metabolite production was observed. Study of nutritional requirements resulted in a simplified medium (SYAM) that allowed, under anaerobiosis, similar results to be obtained as in MRS medium, but without biphasic fermentation kinetics. The best substrates for both growth and amylase production were starch and maltose. Although melibiose, raffinose, fructose, sucrose and glucose also supported growth, lower amylase activity was observed. Conclusions: The physiology of the strain can be investigated with SYAM medium, using either starch or maltose as substrate. The strain also presented potential for alpha -galactoside fermentation. Significance and Impact of the Study: Lactobacillus fermentum was one of the dominant bacteria of African maize dough fermentations. Amylolytic strains with activity against other compounds (i.e. raffinose) suggested a potential to be used as starter for cereal fermentation.