High-level expression and characterization of a lipase from Trichosporon fermentans Y3 and its application as an aquafeed additive for grouper (Epinephelus coioides)

Abstract

A lipase gene was cloned from Trichosporon fermentans Y3, subcloned into pPICZαA, and then expressed in Pichia pastoris X33. The lipase (lipRT), which was obtained using a 50-L bioreactor, had maximum activity of 6000 U/mL. It had an optimum pH 8.0 and remained stable between pH 3.0 and 11.0, while its optimum temperature was 45 °C, maintaining more than 55% of optimum activity between 20 and 35 °C. To evaluate the potential application of lipRT as an aquafeed additive for juvenile grouper (Epinephelus coioides), fish with initial weight 13.31 ± 0.26 g were randomly divided into 12 sea cages and fed five formulated diets (labeled diets 1 to 4). Diets 1–4 were formulated to include 8% crude lipid and serial levels of lipRT (0 U/kg, 50 U/kg, 500 U/kg, and 1000 U/kg). The results showed that WG, FE, and PER of fish as well as ACH50, LSZ, and O2− production ratio in serum of fish on diets 3 and 4 were significantly (P < 0.05) higher than those on diets 1 and 2. The present data suggests that lipRT could improve the utilization of lipid and some nonspecific immunological parameters, and therefore could potentially be used as an aquafeed additive.