Molecular Identification of Cultured Microbial Population and Metabolic Impacts on Traditional Fermented Motoho From Different Regions of South Africa.

Sorghum motoho is a fermented sorghum porridge produced through natural fermentation or backslopping. To understand the in situ microbial population and their metabolic roles during fermentation, water, tomoso (traditional starter culture), and motoho samples were collected from eight areas in the Free State and Eastern Cape provinces of South Africa. The highest lactic acid bacteria (LAB) population was 6.81 Log CFU/g in motoho (pH 3.97) from Area 3 and 6.78 Log CFU/g in tomoso (pH 4.43) from Area 6, whereas the lowest yeast population was 3.09 Log CFU/g in tomoso (pH 3.16) from Area 5. The highest population was 6.78 Log CFU/g in motoho (pH 3.93) from Area 8. Overall, the LAB population (5.74 Log CFU/g) was frequently isolated in tomoso, whereas the yeast population (5.36 Log CFU/g) was isolated in motoho. Selected LAB and yeast isolates were differentiated using RAPD-PCR analysis using M13 primer; 15 and 23 distinct groups were observed among the 27 and 31 LAB and yeast isolates, respectively. Analysis of the 16S rDNA identified Schleiferilactobacillus harbinensis, Levilactobacillus brevis, Lactiplantibacillus plantarum, and Limosilactobacillus fermentum across seven areas, with L. brevis frequently isolated from tomoso samples of the six areas studied. Analysis of the D1D2 domain of the 26S rDNA identified the yeasts Candida sake, Kazachstania unispora, Pichia kudriavzevii, Pichia fermentans, and Saccharomyces boulardii, which the latter three were frequently isolated in tomoso and motoho from six areas. When compared with species from different regions and products, the motoho LAB isolates clustered together, whereas the yeast isolates clustered into eight groups on the neighbor-joining phylogenetic tree. In the tomoso and motoho samples from all areas, the lactic acid concentration was detected between 0.04 and 1.97 mg/100 g, whereas the acetic concentration was below 0.36 mg/100 g. None of the LAB were amylolactic while the yeasts Saccharomyces cerevisiae, C. sake, and S. boulardii fermented maltose. The study revealed that the tomoso possessed a diverse microbial population, which consisted of different non-Saccharomyces yeast species that survived the fermentation conditions.