Fungi Trichoderma harzianum

HC-Toxin and victorin are produced by Helminthosporium carborum, which is a pathogen on maize, whilst another peptide, AM-toxin, is produced by Alternaria alternata, which causes a blotch disease on apples. The peptabiols, produced by Trichoderma harzianum, affect the development of other fungi. 

Trichoderma harzianum Rifai (Hypocreaceae) is a widespread soil Ascomycotina known to produce antibiotics active against other microscopic fungi. This species was found in a sponge Mycale cecilid) collected in Japan. The strain, when cultured in seawater, proved capable of producing substances different from those obtained in freshwater medium, including trichoharzin (38) (a colorless glassy solid identified by MS, NMR spectroscopy and chemical conversion extraction yield 0.5 mg/1), which is a new oktaketide with a decalin fi-amework [79]. 

Kitomoto, Y, Moii, N., Yamamoto, M., Ohiwa, T, Ichiwaka, Y. A simple method of protoplast formation and protoplast regeneration fiom various fungi using an enzyme from Trichoderma harzianum. Appl Microbiol Biotechnol 1988,28,445—450. 

An antibiotic inhibition zone often appears around Trichoderma spp. interacting with other fungi. The genus contains many species which produce secondary metabolites. Claydon et al. (23) have identified an antibiotic from T. harzianum as a volatile, 6-n-pentyl-2H-pyran-2-one this was recently shown to be an active antibiotic from T. koningii (24). The volatile appeared to be the factor responsible for the coconut smell of some biocontrol-effective strains of T. harzianum (25). However, in a Petri-plate assay, it can be difficult to be certain that antibiosis is involved. As well as competitive growth, lytic enzymes could also contribute to the action and Trichoderma has been shown to produce / -l,3-glucanase and chitinase (26-29). 

It has been proposed that the production of xylanases and cellulases is under separate regulatory control in some filamentous fungi (1). Hrmova et al. (42) reached a similar conclusion after monitoring the daily production of these enzymes in Trichoderma reesei QM 9414. Xylanase and cellulase activities followed independent production profiles during fungal growth. The same effect has been observed in batch cultures of T. harzianum. We have observed peak xylanase activity on the third day of growth whereas the cellulase activity peaked after day five or six (unpublished). 

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