Identification and functional properties of dominant lactic acid bacteria isolated at different stages of solid state fermentation of cassava during traditional gari production.

摘要

A culture-based technique was used to determine the dominant lactic acid bacteria (LAB) in and study bacterial population dynamics during cassava fermentation for production of gari. LAB were consistently isolated from the fermented mash with a viable count of 6.00 log cfu/g found at 12 h. The aerobic viable count of amylolytic lactic acid bacteria was higher than that of other groups of LAB throughout the fermentation up to 96 h with the highest viable count of 8.08 log cfu/g. Phenotyping combined with 16S rDNA gene sequencing identified the dominant LAB species as Lactobacillus plantarum, L. fermentum and Leuconostoc mesenteroides while PFGE determined that the strains were genotypically heterogeneous. The sugar fermentation profiles of the isolates showed that indigestible sugars such as raffinose and stachyose could be fermented by the strains. Information was also generated about the functional properties of the strains. Only L. plantarum strain 9st0, isolated at 0 h of the fermentation, produced bacteriocin with antagonistic activity against closely related indicator strains. The highest amylase activity was produced by strain L. plantarum 7st12, while appreciable amylase was also produced by L. fermentum 1st96. These results show that selection of mixed starter cultures of bacteriocin- and amylase-producing L. plantarum and L. fermentum have potential as starter cultures during intermediate and large-scale gari production.