Isolation and Screening of L-Asparaginase Producing Bacteria from Rhizosphere of Medicinal Plants in Botanical Garden, University of Ibadan, Ibadan

Abstract

Microorganisms are the largest of all the organisms on earth and exist almost everywhere. They contribute maximally in occurrence of nature and their functions in provisions of life essential element cannot be underestimated. Different taxa of organisms have been reported to be Lasparaginase producers, which being produce in huge amount. However, the exploration of Lasparaginase from terrestrial habitat is reducing and there is increase in the rate at which this enzyme is needed in the biomedical field. It is therefore necessary to explore the rhizosphere of some medicinal plant for isolation of L-asparaginase producers. This study aims to isolate Lasparaginase producing microorganisms from medicinal plant rhizosphere. Bacteria were isolated from rhizospheric soil of matured medicinal plant (Azadirachta indica, Moringa oleacea, Alstona boonei and Khaya senegalensis) in the botanical garden, University of Ibadan, and were screened for L-asparaginase activity using plate assay method. The best six L-asparaginase producers were identified using morphological, biochemical and molecular methods. In this present study, 145 bacterial isolates were obtained from rhizosphere of four medicinal plants and screened out for production of L- asparaginase. Out of them, sixty-seven (67) bacterial isolates showed positive L-asparaginase activity on Glycerol Asparagine Medium and modified M9 medium. Six positive L-asparaginase-producers produced high yield when subjected to secondary screening by submerged fermentation and were identified as Amycolatopsis japonica, Stenotrophomonas pavani, Sphingobium yanoikuyae, Paenibacillus cineris, Sphingobacterium caenis and Actinomycetal bacterium. Rhizospheric soil of matured plant from botanical garden, University of Ibadan is a good reservoir for diverse L-asparaginase producing microorganism, and it could be greatly explored for abundance availability of the enzyme.