Preliminary Screening of Bacteria Isolated from Insects Living in Poultry for Antibiotic Production

Aim: This present study was conducted to isolate antibiotic producing bacteria from insects living in poultry.

Place and Duration of Study: Insects living in poultry were collected from poultry farms within Onitsha metropolis in Anambra State between April 2018 and September 2018.

Methodology: The gut of one hundred insects; (Musca domestica and Alphitobius diaperinus) were analyzed. The insects were dissected and emulsified in 10ml of peptone water. The dilutions were cultured on Nutrient agar and Blood agar for 24 h. The bacterial isolates were characterized using molecular identification. The DNA was extracted from the identified isolates and analyzed by 16S rRNA. In preliminary screening, the isolates were inoculated into Muller Hinton agar using agar plug. The promising isolate showing antagonism was subjected to submerged fermentation method and the secondary metabolites were extracted. Screening of the secondary metabolites extract was done using agar well diffusion. The minimum inhibitory concentration (MIC) of the secondary metabolite was determined using broth dilution method at different concentrations. The inhibitory activity of the organism was checked against four bacteria namely; Bacillus subtilis, Salmonella serovar typhi, Escherichia coli and Staphylococcus aureus.

Results: The sequence analysis revealed the strains to be Lysinibacillus macroides, Paealcaligenes hermetiae, Bordetella flabilis, Bacillus aerophilus, Klebsiella variicola. Lysinibacillus macroides showed antagonism against the test bacteria during the preliminary test. After fermentation, the secondary metabolite extracts from Lysinibacillus macroides exhibited antibacterial activities against Salmonella Serovar Typhi, Staphyloccus aureus and Bacillus subtilis at different concentrations.

Conclusion: The extracts from bacterial isolate; Lysinibacillus macroides exhibited antibacterial activities against Bacillus subtilis, Salmonella serovar typhi and Staphylococcus aureus. The extracts may serve as a new drug molecule produced from natural source when purified.