New efficient amylase-producing strains of Lactobacillus plantarum and L. fermentum isolated from different Nigerian traditional fermented foods

Abstract

Amylolytic lactic acid bacteria (ALAB) were isolated from Nigerian traditional fermented foods (fufu, burukutu, ogi-baba and kunu-zakki) with the aim of selecting efficient amylase-producing strains. Nine isolates were characterized on the basis of their phenotypic and taxo-molecular characteristics. Three groups could be distinguished by their fermentation profiles and this was confirmed by DNA restriction analysis. Though fermentation profiles gave good identification of strain K9 (unique representative of group III) as Lactobacillus fermentum, they could not be used to ascertain the taxonomic position of strains of groups I and II. Analysis of partial 16S rRNA sequences led to the identification of these groups as L. plantarum strains and confirmed the species of strain K9 as L. fermentum. The two distinct phenotypic groups of L. plantarum differed in their use of d-xylose, l-arabinose, melibiose and were different from the previously described amylolytic L. plantarum A6 isolated from retted cassava in Congo. L. fermentum K9 was different from L. fermentum OgiE1 and Mw2 isolated from Benin maize sourdough and it is the first amylolytic L. fermentum described from Nigerian fermented products. Enzymatic profiles showed some differences between the strains of a similar fermentation group. One of the most relevant characteristics of the isolates was a higher yield of amylase production than those reported for previously described ALAB grown under the same conditions. Furthermore, all isolates were tolerant to an exposure at pH 2 and to bile salts.