Probiotic Potential and Genomic Evaluation of Lactic Acid Bacteria Isolated from Fermented Sorghum-Based Gruel

Abstract

Forty eight isolates were randomly isolated from fermented red sorghum (Sorghum bicolor) and white sorghum-based (Sorghum vulgare) gruel and evaluated for their probiotic abilities. Forty five out of the forty eight isolates were Gram-positive, catalase negative and non-sporulating, which were further evaluated.  Twenty out of the forty five isolates showed tolerance to acid with their ability to survive extreme pH 2.0, 3.0 and 4.0 respectively at different levels. These were further screened for their in vitro inhibition ability against selected test pathogens (Escherichia coli, Salmonella Typhimurium, Bacillus sp., Pseudomonas aeruginosa, and Staphylococcus aureus). Fourteen out of the twenty isolates had antimicrobial activity against the test pathogens at different levels. They were further screened for their antibiotic susceptibility pattern, all the fourteen isolates showed susceptibility to different antibiotics at different levels. These isolates were screened for their bile tolerance ability, all the fourteen isolates showed tolerance to the bile salt concentration (0.3%, 0.5% and 1%) at different levels respectively. The fourteen isolates were also screened for their gastric transit tolerance ability; all the fourteen isolates were able to tolerate gastric transit at 0 minute, 90 minutes and 180 minutes respectively. They were further screened for their in vitro hydrophobicity ability, only six out of the fourteen isolates showed percentage hydrophobicity of 40% and above. These six isolates were identified at the sub-species level using 16S RRNA Sequencing for isolates identification and construction of phylogeny. They were identified as Lactobacillus plantarum strain ST1, Lactobacillus brevis strain SC4, Lactobacillus casei strain 0108, Lactobacillus plantarum strain HASOB9a, Pediococcus pentosaceus strain SH 740 and Lactobacillus plantarum ZJ316 respectively. Out of the six identified isolates, the complete genome of Lactobacillus plantarum ZJ316 had been sequenced and was retrieved alongside with the complete genome data of four other species of Lactobacillus plantarum of industrial importance available in public domain, which was used for the mini comparative genome analysis in this research, using bioinformatics and visual analytics tools (Tableau Desktop). It was revealed that the genome size of Lactobacillus plantarum ZJ316 is second to that of Lactobacillus plantarum 16 and higher than that of the others whose genome had been completely sequenced.