Study on Purification and Some Properties of Endo-1,4-β-Glucanases of Trichoderma harzianum UzCF-28

The purpose of this study was to isolate, purify, and study the biochemical properties of cellulolytic enzymes synthesised by the Trichoderma harzianum UzCF-28 strain. During submerged cultivation in liquid culture on modified Mandels nutrient medium with wheat straw as a carbon source, strain UzCF-28 demonstrated high cellulolytic activity. When enzyme activity was studied dynamically for 10 days, maximum activity endo-1,4- -glucanase (5.2 units/ml) and xylanase (7.65 units/ml) of the fungus detected after 3 days of culturing. High activity of exo-1,4- -glucanase was observed on day 4 and was found to be 2.96 units/ml. As a result of purification by precipitation with ammonium sulfate and further ion exchange chromatography, two isoforms of endo-1,4- -glucanase-EG II and EG III with molecular weight of 135 and 75 kDa respectively were revealed. The pH optimum for EG I and EG III was 4.5, while EG II was 4.7, regardless of the substrate used—CMC or "Whatman filter" paper. Heating up to 40oC of EG III did not result in its inactivation, but rather increased its activity by more than three times when compared to the initial activity of the enzyme, indicating that the thermostability of EG III among tested enzymes varied significantly.