Purification and Characterisation of a Newly Isolated Stable Long-Life Tannase produced by F. subglutinans (Wollenweber and Reinking) Nelson et al.

A stable long-life tannase was synthesised by Fusarium subglutinans and the fermentation processing parameters were optimised. Maximum enzyme production (9.38 U/ml) was recorded after 96 h of incubation at 35°C, initial pH 5, in submerged culture (200 rpm) utilising 2% (w/v) tannic acid as a sole carbon source. The tannase produced was purified to electrophoretic homogeneity through two-step column chromatography and the purified form remained stable in a pH range of 6–8. Its midpoint of thermal inactivation (T _m) was recorded at 70°C after 60 min of exposure. Maximum tannase activity was enabled at pH 6 and 40°C. Ca²⁺, K⁺, Mg²⁺ and Mn⁺ showed a stimulatory effect while Ba²⁺, Co²⁺, Cu²⁺, Fe³⁺ and Zn⁺ showed a competitive inhibitory effect on enzyme activity. Values of K _m, V _max, K _cat and the molecular mass of the purified enzyme were 0.116 μM ml⁻¹ min⁻¹, 3.57 mM, 1.16 μM ml⁻¹ min⁻¹ and 150 kDa, respectively. The participation of the SH group and carbohydrates in the enzyme structure was also suggested by the results. The stability of the purified and partially purified enzyme at −15°C extended to 13 months.