Abstract

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In order to utilize phosphorus and other nutrients efficiently, monogastric animals require an exogenous supply of phytase to hydrolyze phytate present in feed. However, the stability and efficacy of phytase may be grossly compromised in the event of non compliance by veterinary marts and farmers to storage directives from manufacturers. To overcome this challenge, it is envisaged that live phytase producing microorganisms may be used as feed supplement. The aim of this study was to screen some phytase-producing bacteria strains for pathogenicity, and thereafter evaluate the antimicrobial sensitivity and gastrointestinal tract (GIT) tolerance of selected strain in vitro. Four phytase-producing bacteria strains previously isolated from top soils from Lagos dumpsites, and identified as Enterobacter cloacae ODS 29, Bacillus amyloliquefaciens ODS 33, Bacillus amyloliquefaciens FDS 10 and Bacillus subtilis FDS 16 (MH879829, MH879830, MH879831 and MH879832 respectively) were screened for pathogenic ability by microbiological methods. Pathogen-negative strain was evaluated for susceptibility against ten standard antimicrobials over 24 h and thereafter evaluated for tolerance to GIT conditions (pH 1-4 over 2 h, bile concentrations 0.1 to 2% (w/v) over 5 h, gastric juice over 6 h and simulated GIT condition over 4 h respectively). Results of pathogen test revealed only Enterobacter cloacae ODS 29 as non pathogenic strain of bacteria. Evaluation of its sensitivity to various antimicrobials revealed susceptibility to all ten antimicrobials. Result of GIT tolerance showed E. cloacae ODS 29 to survive pH < 2, bile concentration 2% (w/v), gastric juice and simulated GIT conditions. As such, E. cloacae ODS 29 is considered safe and having potential for probiotic use as feed supplement.

Keywords: : Antimicrobial sensitivity, E. cloacae, GIT condition, Hemolysin, Phytase.