Determination of lytic enzyme activities of indigenous Trichoderma isolates from Pakistan

Abstract This study investigated lytic enzyme activities in three indigenous Trichoderma strains namely, Trichoderma asperellum, Trichoderma harzianum and Trichoderma sp. Native Trichoderma strains and a virulent strain of Rhizoctonia solani isolated from infected bean plants were also included in the study. Enzyme activities were determined by measuring sugar reduction by dinitrosalicylic acid (DNS) method using suitable substrates. The antagonists were cultured in minimal salt medium with the following modifications: medium A (1 g of glucose), medium B (0.5 g of glucose + 0.5 g of deactivated R. solani mycelia), medium C (1.0 g of deactivated respective antagonist mycelium) and medium D (1 g of deactivated R. solani mycelia). T asperellum showed presence of higher amounts of chitinases, β-1, 3-glucanases and xylanases in extracellular protein extracts from medium D as compared to medium A. While, the higher activities of glucosidases and endoglucanses were shown in medium D extracts by T. harzianum. β-glucosidase activities were lower compared with other enzymes; however, activities of the extracts of medium D were significantly different. T. asperellum exhibited maximum inhibition (97.7%). On the other hand, Trichoderma sp. did not show any effect on mycelia growth of R. solani on crude extract.

Antifungal activity of metabolites of the endophytic fungus Trichoderma brevicompactum from garlic

The endophytic fungus strain 0248, isolated from garlic, was identified as Trichoderma brevicompactum based on morphological characteristics and the nucleotide sequences of ITS1-5.8SITS2 and tef1. The bioactive compound T2 was isolated from the culture extracts of this fungus by bioactivity-guided fractionation and identified as 4β-acetoxy-12,13-epoxy-Δ9-trichothecene (trichodermin) by spectral analysis and mass spectrometry. Trichodermin has a marked inhibitory activity on Rhizoctonia solani, with an EC50 of 0.25 µgmL-1. Strong inhibition by trichodermin was also found for Botrytis cinerea, with an EC50 of 2.02 µgmL-1. However, a relatively poor inhibitory effect was observed for trichodermin against Colletotrichum lindemuthianum (EC50 = 25.60 µgmL-1). Compared with the positive control Carbendazim, trichodermin showed a strong antifungal activity on the above phytopathogens. There is little known about endophytes from garlic. This paper studied in detail the identification of endophytic T. brevicompactum from garlic and the characterization of its active metabolite trichodermin.

Glycerol production from holocellulose by a mixed culture system of TViride and S cerevisiae Y-1347

Production of glycerol by S. cerevisiae y-1347 through the fermentation of holocellulose by T. viride was studied. The accumulation and the yield of glycerol was dependent on the holocellulose level, pH control, nitrogen source and its level. The addition of trace elements during the fermentation resulted in a decrease in production of glycerol

Glycerol production by immobilized mixed culture of TViride and S cerevisiae Y-1347

Calcium alginate as an entrapping gel at a 2% concentration attains higher bioconversion activities and glycerol yields [700 mg%] by immobilized mixed cultures of T. viride and S. cervisae y-1347. the entrapped mixed cultures could be repeatedly used in batch wise bioconversion successfully for at least six times as suspended in diluted nutrient medium. However, entrapped mixed cultures could be reused three times only when suspended in distilled water and must then be reactivated in nutrient medium to be reused