HOMOLOGOUS TRANSFORMATION OF TRICHODERMA-HAMATUM WITH AN ENDOCHITINASE ENCODING GENE, RESULTING IN INCREASED LEVELS OF CHITINASE ACTIVITY

A 42-kDa endochitinase encoding gene, Tham-ch, was cloned by screening the genomic library of Trichoderma hamatum strain Tam-61 with a PCR-a mplified chitinase sequence from the same fungus. Tham-ch with its own regulatory sequences was reintroduced into the host strain. The integ ration of the transforming construct was stable only in one copy. Homo logous integration occurred in nine transformants, while non-homologou s integration was detected in one transformant. All but one transforma nt expressed higher levels of chitinase activity in comparison to the wild-type recipient strain; the maximum level of increase was 5-fold. Duplicating the copy number of the highly conserved similar to 42-kDa endochitinase encoding gene appears to be one potential means by which the biocontrol capability of the Trichoderma mn species might be impr oved. (C) 1998 Federation of European Microbiological Societies. Publi shed by Elsevier Science B.V. All rights reserved.