Six strains of Trichoderma species isolated from soil and air samples were screened for extracellular L-glutaminase production. The highest enzyme producing isolate, Trichoderma longibrachiatum was subjected to screening and nutrients optimization experiments under solid state fermentation using a constant weight of African locust beans as substrate. A specific activity of 54.96 U/mg was achieved at 1% (w/v) glutamine, 0.5% (w/v) glucose, 1% (w/v) NaCl, pH 3.0 and 1.4 ml inoculums size respectively after 3 days of incubation at 27°C as the optimum condition for L–glutaminase production. Asides glutamine, other nitrogen sources; malt extract and ammonium sulphate had a negative influence on enzyme production likewise the supplemented sources of metal ions; zinc and iron (II) ions.
Key words: Trichoderma, L-glutaminase, fermentation, African locust beans.
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