Isolation, characterization and identification of lactic acid bacteria involved in traditional fermentation of borde, an Ethiopian cereal beverage

Abstract

Changes in pH, titratable acidity, Enterobacteriaceae, aerobic mesophiles, lactic acid bacteria (LAB) and yeast counts were investigated during borde fermentation. A rapid decrease in pH was associated with accelerated growth rate of LAB and inhibition of Enterobacteriaceae. Wide diversities of LAB strains were present at early stage of borde fermentation. The number of species reduced as the fermentation progressed. Representatives of LAB involved in borde fermentation were isolated at 6 h intervals, characterized and identified using physiological and biochemical methods including API 50CH kit. The LAB strains were grouped into 3 major and 2 minor clusters. Most of the LAB strains were heterofermentative lactobacillus (79.4%), while pediococcus species dominating the cocci (20.6%). Weissella confusa, Lactobacillus brevis, Lactobacillus viridescens, Pediococcus pentosaceus and P. pentosaceus subsp. intermedius were identified throughout borde fermentation as dominant LAB. The frequency of dominating strains were: W. confusa (30.9%), Lb. viridescens (26.5%), Lb. brevis (10.3%) and P. pentosaceus (7.4%) and P. pentosaceus subsp. intermedius (8.8%), while sporadically isolated species of Lactobacillus curvatus, P. acidilactici, Lactobacillus collinoides, Lactobacillus sanfrancisco, Lactobacillus pontis and Lactobacillus delbrueckii subsp. delbrueckii were 16.3%. The dominating LAB strains can be potential starter cultures for borde fermentation.