Production, optimization and characterization of esterase isolated from a new endophytic Trichoderma afroharzianum strain AUMC 16,433 and its applications in dye decolorization.

Background and aim: Synthetic dyes in the textile industry pose risks to human health and environmental safety. The current study aims to examine the efficacy of a novel esterase derived from an endophyte fungus in decolorizing diverse dyes, focusing on its production, purification, optimization, and characterization.

Results: Trichoderma afroharzianum AUMC16433, a novel fungal endophyte with esterase-producing ability, was first detected from the cladodes of Opuntia ficus indica by ITS-rRNA sequencing. Furthermore, several fermentation variables that augment esterase production were improved by utilising the Plackett-Burman design and RSM. Ammonium sulphate precipitation at 60% and Sephacryl S300 HR gel filtration were employed to purify the isolated esterase to a specific activity of 1372.1 U/mg with a 2.29-fold increase and a recovery of 42.87%. The enzyme's molecular weight was ascertained to be 43 kDa via SDS-PAGE. The isolated esterase revealed peak activity at 40 °C and pH 8. The kinetic characteristics of esterase were Vmax = 2.717 U/mL and Km = 3.33 mM. The half-life time was 54.4% at 50 °C after 4 h, and the enzyme still retained 14.7% of its activity after 24 h at 50 °C. Esterase decolorized several synthetic dyes used industrially, with the highest decolorization rate in malachite green after 24 h with 66%, and successfully degraded both bromothymol blue and tartrazine with 65.5% and 65.3%, respectively, in the same time frame. Crystal violet and methyl red showed moderate decolorization, with decolorization rates of 57.1% and 43.1%, respectively.

Conclusions: The esterase enzyme isolated for the first time from the new endophytic Trichoderma afroharzianum has a high dyes decolorization potential, which offers it a sustainable strategy for addressing environmental contamination issues.