Breeding of mycoparasitic Trichoderma strains for heavy metal resistance

Aims: This study was designed to investigate the effects of 10 heavy metals on the in vitro activities of beta -glucosidase, cellobiohydrolase, beta - xylosidase and endoxylanase enzymes for six strains of Trichoderma, and to isolate and characterize heavy metal-resistant mutants. Methods and Results: At a concentration of 1 mmol, only mercury showed sign ificant inhibitory effects on the in vitro enzyme activities; in all other cases, the enzymes remained active. A total of 177 heavy metal-resistant mu tants were isolated and tested for cross-resistance to other heavy metals. Some mutants were effective antagonists of Fusarium, Pythium and Rhizoctoni a strains, even on media containing the respective heavy metals. Conclusions: Trichoderma strains could be developed as biocontrol agents th at are effective against plant pathogenic fungi, even under heavy metal str ess. Significance and Impact of the Study: Trichoderma mutants resistant to heav y metals might be of value for use with heavy metal-containing pesticides, as part of an integrated plant protection system.