Assessment of dominant bacterial strains isolated from Ntoba mbodi, an indigenous African alkaline-fermented food, and their potential enzyme activities

Ntoba mbodi is a stable and long-life alkaline-fermented food and the domestic-scale production depends upon microorganisms from the local environment. Previous studies on bacteria in Ntoba mbodi have reported the presence of Bacillus related species and other bacterial taxa. But the abundance of these bacteria in Ntoba mbodi still needs to be determined to assess their ecological importance in this particular environment. In the present study, we used an extinction dilution approach for isolation and taxonomic affiliation of the dominant isolates obtained from the highest positive dilution of Ntoba mbodi. We also tested the hypothesis that there is a convergence in the bacterial community profile in Ntoba mbodi, irrespective of the origins of the food, by assessing the set of dominant bacteria that was found in all the samples studied. The density of the bacteria ranged from 1.67×1010 to 2.8×1010 CFU g-1. Eleven distinct morphotypes were isolated at the highest positive dilution of Ntoba mbodi and identified using 16S rRNA gene sequencing followed by phylogenetic analyses. Eight isolates were classified as Bacillus related species. A set of five strains was shared between all samples of Ntoba mbodi which were closest to Bacillus altitudinis, Bacillus sp. C-32, Staphylococcus sciuri and Bacterium NLAE-Ê«-H375. Of the eleven predominant isolates, eight showed cellulase activity and five showed xylanase and β-glucosidase activity.