Production of chitinases with Trichoderma harzianum isolates using solid substrate fermentation
2004
Viviana Nagy | Gyorgy Szakacs | Ashok Pandey
Over forty Trichoderma harzianum isolates have been screened in solid substrate fermentation (SSF) for chitinase production. Strains were isolated from Asian soil and tree bark samples. Identification was performed in Canada and Austria by classical and molecular taxonomical methods.Four SSF media were used for the screening. They contained wheat bran, crude chitin from crab shells (SIGMA) and different salt solutions for wetting of the substrate.In a five day fermentation at 30 ℃ the best chitinase producers were T. harzianum TUB F-691, TUB F-693, TUB F-699, TUB F-700, TUB F-927, TUB F-947 and TUB F-972 isolates (TUB=Technical University of Budapest culture collection). The best producers yielded between 3.5-5.5 International Unit/g dry matter (DM) chitinase.T. harzianum TUB F-947 was selected for further optimization. This strain was isolated from a soil of Thailand. The optimum moisture content (67%), optimal alternative substrate-carrier for SSF (wheat straw) and chitin content of the substrate (30%) were determined. Temperature and pH optima of chitinase produced by T. harzianum TUB F-947 were found to be at 50 ℃ and 5.0, respectively. The enzyme complex was thermally not stable at 50 ℃. Medium optimization experiments to enhance the chitinase production using statistical methods also have been performed.
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