Isolation And Screening Of Soil Microorganisms From Cassava Farmland In Umudike For Antibiotic Production

ABSTRACT

The lack of new therapeutic options to replace many antimicrobial agents that are losing their efficacy against resistant bacteria is a growing concern. The search for new antimicrobials from rare and/or existing sources have thus become a worthwhile effort in recent years. Soil samples collected from Umudike were studied in an effort to screen for novel antibiotics produced by soil microbes. A total of 45 bacterial and 19 fungal isolates were successfully obtained from the soil samples. Antibiotic activity screening using the paper disc diffusion technique was used to evaluate the antagonistic potentials of the isolates against ATCC Strains of bacteria including Staphylococcus aureus (ATCC 25923), Salmonella typhi, Escherichia coli (ATCC 25922). Of the 64 isolates, 6.25% (4/64) were active against eight of the test organisms with diameter zones of clearing that ranged from 10.0mm to 17.0mm. Isolate VC7 exhibited the strongest antibacterial activity against S. typhi and E. coli with diameter zones of clearing of 17mm and 11.0mm respectively followed by VC29 which recorded a zone of inhibition of 14mm and 10mm against E. coli and S. aureus respectively. VC7 was tentatively identified as an Enterobacter species based on their colonial morphology and biochemical tests results. Among the isolates which demonstrated antagonism against the test bacteria, VC18, VC26, and VC7were identified as Bacillusspp., Penicillium spp and Enterobacter spp respectively.