Samuel Temitope Ogunbanwo

Antagonistic activity of bacteriocin produced by Lactobacillus species from ogi, an indigenous fermented food.

Seven Lactobacillus species each with one or more strains were isolated from various fermented cereal gruels (ogi). They were identified as L. plantarum (3 strains), L. delbrueckii (1 strain), L. brevis (2 strains), L. reuteri (2 strains), L. casei (1 strain), L. fermentum (1 strain) and L. acidophilus (1 strain). Bacteriocin production was observed in cell‐free supernatants of 8 of these strains with L. fermentum, L. delbrueckii and L. reuteri strains (white maize ogi) being negative. The bacteriocin produced by the eight strains inhibited the growth of various target organisms with the inhibition strongly noticed using Enterococcus faecalis as indicator. While catalase treatment, pH changes and heat treatment up to 80 °C had no effect on the activity of bacteriocin from these isolates, treatment with trypsin and proteinase K resulted in complete loss of inhibitory activity of the bacteriocins. A reduction in the inhibitory activity of the bacteriocins was also found to occur with increasing concentrations of glucose or peptone in the cultivation medium.

Inhibition of uropathogens by lactic acid bacteria isolated from dairy foods and cow's intestine in western Nigeria

A total of 96 lactic acid bacteria (LAB) were isolated from African indigenous fermented products and cow’s intestines to study their inhibitory capability against multi-drug-resistant uropathogens. Escherichia coli accounted for approximately 45% of isolated uropathogens, followed by Staphylococcus spp. (20%). The Gram negative uropathogens were highly resistant to quinolones, co-trimoxazole, teicoplanin and some β-lactams, while the Staphylococcus spp. showed high resistance to aminoglycosides, β-lactams and macrolides. Twenty-four LAB isolates were selected based on their antimicrobial activity against two uropathogenic Staphylococcus aureus strains and bacteriocin production. LAB strains showing antimicrobial activity were grouped into smaller groups through amplified ribosomal DNA restriction analysis (ARDRA). Representative strains were identified as Weissella spp., Enterococcusfaecium, Lactococcus lactis and Lactobacillus brevis through sequencing of 16S rDNA. The Weissella spp. and L. brevis strains demonstrated remarkable inhibitory activity against seven strains of Gram negative uropathogens. Two strains of L. lactis produced a bacteriocin-like inhibitory substance active against Lactobacillus sakei. In this study, an unusual high rate of co-trimoxazole, quinolones and macrolides resistance among uropathogens from south west Nigeria was discovered. Based on their sensitivity to Weissella spp., there is a potential for using these LAB as a natural approach for the protection against the uropathogens assayed.

Influence of lactic cultures on the quality attributes of tsire, a West African stick meat

Tsire is a popular, traditionally processed West African stick meat. Two lactic acid bacteria (LAB), Pediococcus acidi-lactici and Lactobacillus plantarum were used to inoculate pieces of fresh beef before (TA) and after (TB) grilling followed by incubation at 30 °C for 24 h. TA and TB tsire samples had the lowest coliform count (expressed as log c.f.u./g) of 13.48 and 8.83, Staphylococcus count of 7.90 and 5.76, Pseudomonas count of 10.06 and 5.99 on day 6 of storage period respectively. There was an increase in the population of the inoculated LAB in the TA and TB samples to 10.93 and 12.41 respectively. However, the uninoculated samples (TU) had a relatively high coliform, Staphylococcus and Pseudomonas counts. Biochemical analysis of the tsire products showed the TB samples having the highest crude protein (26.43%), thiobarbituric acid (0.25 mg malonaldehyde/kg) and free fatty acid (0.45 mg KOH/g lipid) values. Polyvinyl chloride was found to be the most suitable packaging material for the products during storage, compared with aluminium foil and newsprint. Organoleptic evaluation of the tsire samples also revealed that the TB samples were rated higher in terms of texture, appearance and flavour, while the uninoculated samples had the lowest scores.

Prevalence and antimicrobial susceptibility of Vibrio parahaemolyticus isolated from seafoods in Lagos Lagoon Nigeria

Abstract In this study, a total of 90 seafood samples; croaker fish (Pseudotolithus senegalensis), shrimps (Penaeus notialis) and blue crab (Callinectes sapidus) collected from landing sites along the Lagos Lagoon in Nigeria were examined for the prevalence of Vibrio parahaemolyticus using both biochemical and molecular methods. Biochemical identification of the isolates was confirmed by Polymerase Chain Reaction (PCR). The presence of the virulence-associated tdh (thermostable direct haemolysin), trh1 (thermostable-related haemolysin) and trh2 genes in the V. parahaemolyticus isolates was also detected by the PCR method. PCR products from the V.16S primers were sequenced. Antibiotics susceptibility of the isolates was also determined. About, eight isolates were presumptively identified as V. parahaemolyticus, PCR identified five and none of the isolates were positive for the genes tdh or trh. The five isolates sequenced were identified as different strains of V. parahaemolyticus. V. parahaemolyticus_RIMD_2210633 = 2MKSHa remained resistant to all antimicrobials tested. However, only V. parahaemolyticus_MP-2_AY911391 = TBSHy showed strong sensitivity to all the antimicrobials with ampicillin (minimum inhibitory concentration-4 μg/ml). In addition, the other three isolates showed sensitivity for Tetracycline, Ciprofloxacin, Gentamicin and Ceftazidime. Ampicillin resistance in most of the isolates suggests low efficiency of ampicillin in management of V. parahaemolyticus infection.