IN-VITRO ANTIMICROBIAL ACTIVITY OF AEROMONAS SPP ISOLATED FROM ESTUARY USING DIFFERENT SCREENING PROTOCOLS

Screening is important in investigating antimicrobial activities of bacteria in a quest to discover new antimicrobials. Various protocols are readily available and employed by researchers worldwide studying microbiostatic and microbicidal activities of bacterial. This research therefore aims at evaluating available protocols and suggesting a standardized model. For the purpose of these research, antimicrobial ability of Aeromonas spp isolated from estuary was investigated using agar well diffusion method, deferred method and agar disc diffusion method respectively. Result obtained reveals that five isolates were positive to antimicrobial production among fifteen bacteria screened. Result was depended on the protocol utilized. Agar well diffusion produced a visible result when compared to others. Next to this was agar disc method. Deferred method involving both cross streaking and spot on lawn could not produce result as of swarming nature of the positive isolates tested. Based on our results, protocols utilized were grouped into preliminary screening test (PST) and confirmatory tests (CT) respectively. Preliminary screening protocol (PST) consists of deferred method – perpendicular cross streaking and spot-on-lawn while confirmatory protocols (CT) are agar well diffusion and agar disc diffusion methods. Preliminary protocols are not enough to conclude existence or non-existence of antimicrobial activity in bacteria. Conclusively, both preliminary and confirmatory protocols should be employed while screening bacteria for antimicrobials as suggested in our   model.