Spatial and temporal diversity of Simulium damnosum s.l. gut microbiota and association with Onchocerca volvulus infection in Cameroon

The isolates' probiotic capacity was assessed based on their tolerance to acid, bile salt, NaCl, stimulated gastric juice, and intestinal fluid.The spot method was used to determine their antagonistic activity in multidrug-resistant Salmonella enterica and Escherichia coli.Results: Four coccobacilli and three rod-shaped isolates were gram positive.They were identified as follows: three Lactobacillus plantarum, two L. buchneri and one L. parabuchneri and one L. fermentum.All isolates were non-haemolytic in defibrinated sheep blood.Five and three isolates could tolerate up to 3% and 4% sodium chloride respectively.L. buchneri2 had the highest mean percentage survival rate (MPSR) at pH 2 after 3 hours (103.67 0.26), while L. plantarum2 decreased to 99.47 0.22.L. plantarum3 had the greatest MPSR (82.35 2.33) in 0.3% bile salt after 3 hours, followed by L. buchneri1 and L. parabuchneri (34.87 3.33 and 31.39 1.15, respectively).The MPSR of Lactobacilli in stimulated gastric juice at pH 2.5 after 4 hours varied between species.L. plantarum3 cells were highly tolerant to stimulated gastric juice at pH 2.5 (131.86 16.3), whereas L. plantarum2 cells showed the least (92.89 1.27).In stimulated intestinal fluid at pH8 after 6hours, the isolate with least MPSR was L. buchneri 1 (57.52 52) while L. plantarum2 was the highest (97.01 0.2).L. plantarum3 was the best Lactobacillus with antibacterial activities against multidrug resistant bacteria; Salmonella enterica (44 0.14), and E. coli (34 1.6).Discussion: The viability of L. plantarum after gastrointestinal fluid treatment and bile salt, among others, is suggestive of a good probiotic candidate, these findings tie with the report Lang et al. (2022), and Hassan et al. (2020).Research is required to explore additional probiotic criteria.Conclusion: L. plantarum could be recommended as the best potential probiotics follow by L. buchneri and L. fermentum that could eliminate multidrug-resistant enteric bacteria in cases of dysbiosis.