Many lactic acid bacteria (LAB) were isolated from "Shermout", a popular Sudanese fermented beef product intended for long storage. An isolate that demonstrated significant antibacterial activity was identified as Lactobacillus plantarum PM4 based on phenotypic, physiological and biochemical characteristics and carbohydrate utilization patterns. The inhibitory activity of the partially purified bacteriocin was completely arrested by the proteolytic enzymes proteinase-k and pepsin but not by α-amylase, asserting its proteinaceous nature. The activity was not due to H 2 O 2 as similar inhibition was obtained by cell-free supernatant (CFS) produced under anaerobic conditions. The bacteriocin showed a molecular weight in the range of 3 -5 kDa and had a bactericidal mode of action. No significant reduction in activity was observed on heating to 60˚C for 60 min, but activity was lost on heating to 100˚C or autoclaving. Highest inhibitory activity was at pH 5.5 and there was appreciable reduction in activity at pH 3, 7 or 9. There was no drop in activity at −80˚C or −20˚C up to four weeks of storage. However, at 4˚C and 35˚C, a gradual decline in activity was observed. Lb. plantarum PM4 exhibited bactericidal activity against Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Escherichia coli ATCC25922, Klebsiella pneumoniae and Proteus vulgaris. Bacteriocin production generally coincided with the phase of maximum growth and the best combination for maximum production of inhibitory activity was at pH 5.5 for 48 h whether incubated at 25˚C, 30˚C or 37˚C.

Lactobacillus curvatus M3 and Pediococcus pentosaceus N2, isolated from fermented beef and infant faeces, respectively, exhibited antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Escherichia coli ATCC25922, Klebsiella pneumonia, Proteus vulgaris, Pseudomonas aeruginosa and Salmonella typhi. The activity was not due to H2O2 as similar inhibition was obtained by supernatants produced under aerobic or anaerobic growth conditions. The active ingredients were identified as bacteriocins of molecular mass of 3-4 kDa. The two bacteriocins were sensitive to proteinase-k and pepsin but were not affected by α-amylase, and experienced little reduction in activity on heating to 100˚C for 30min but were destroyed by autoclaving. Both bacteriocins exhibited highest inhibitory activity at pH 5.0. The bacteriocin from Lb. curvatus M3 was bactericidal while that from N2 was bacteriostatic to Staph. aureus. Kinetics of growth and bacteriocin production showed that maximal inhibitory activity coincided with the phase of optimal growth and with a drop in the pH of the growth medium to 4.2-4.5. Citation: Elyass ME, Altayar MA, Mahdi AA, Abdelrawaf SS, Shigidi MT, et al. (2015) Keywords: Lactobacillus curvatus, Pediococcus pentosaceus, Bacteriocins Characterization and Evaluation of Antimicrobial Activity of Bacteriocins from Lactobacillus Curvatus and Pediococcus Pentosaceus. J Infect Non Infect Dis 1: 001.• examined for Gram reaction, catalase production, cell morphology using phase contrast microscopy, gas production from glucose, hydrolysis of arginine, growth at pH 4.4 and 9.6, salt tolerance and growth at 10°C and 45°C.Gas production from glucose was determined in modified MRS broth containing inverted Durham tubes with diammonium citrate replaced by ammonium sulphate [13]. Glucose was sterilized separately (115°C for 10min) and was aseptically added to the medium. Hydrolysis of arginine was tested in MRS broth without glucose or meat extract but containing 0.3% arginine and 0.2% sodium citrate instead of ammonium citrate. Ammonia was detected using Nessler's reagent [14]. Growth at pH 4.4 and 9.6 was tested in MRS broth adjusted to these pH values using 1N HCl. Salt tolerance was tested in MRS broth supplemented with 6.5% NaCl. Growth at different temperatures was observed in MRS broth after incubation for 3 days at 15°C and 45°C.Ultimately, the two isolates were identified to specific level through biochemical profiling using the KB009 HiCarbohydrate identification kit (HiMedia Laboratories, Mumbai, India), which makes use of the patterns of utilization of 35 sugars. Screening for antagonistic activityThe antagonistic activities of the two isolates against four indicator bacteria (Staphylococcus aureus ATCC43306, Bacillus subtilis NCTC8236, Enterococcus faecalis ATCC10541 and Escherichia coli ATCC25922) were initially screened by the direct spot-on-lawn method [15] which was afterwards confirmed by the agar-well diffusion method [16].In the spot-on-lawn method, aliquots ...

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In a bioassay of the toxicity of four local isolates and a reference (HD-1) strain of Bacillus thuringiensis subsp. kurstaki (Bt kurstaki) to larvae of the spotted bollworm (Erias vittella), different concentrations of spore-crystal mixture were offered to third-instar larvae of the spotted bollworm (Erias vitella) utilizing okra seeds as diet. The number of dead larvae and the time of death were recorded, and corrected mortality was computed using SunShepard formula. Most isolates exhibited LT50 values far lower than the reference strain after 24 and 48 h of incubation. One such isolate (BO5) required just 22.54 h to kill 50% of E. vittella larvae when used at 2.4x10 9 spore-crystals/mL. Similarly, most isolates exhibited LC50 values lower than the reference strain at 24 and 48 h. However, despite the unsatisfactory performance by the reference strain at 24 and 48 h, it showed much improved performance at 72h, where only one isolate (K21) showed relative potency (RP) value higher than the reference strain, while another (KO9) was almost as potent as the reference strain. It is concluded that continued search for and evaluation of Bt isolates obtained from different environments could uncover great capabilities in these isolates.