Lowering induction temperature for enhanced production of polygalacturonate lyase in recombinant Pichia pastoris

Various effects of temperature on heterologous alkaline polygalacturonate lyase produced in recombinant Pichia pastoris were investigated. The results indicated that PGL activity could be improved significantly by decreasing the cultivation temperature. It was reached 931 U/mL with temperature lowered to 22 °C at the beginning of induction phase, which were 2.1-fold and 2.9-fold increase compared to that at 30 and 26 °C. The mechanisms behind the temperature effect on recombinant PGL production may be ascribed to poor cell viability, decrease of intracellular adenosine phosphate levels, of AOX activity but increase of extracellular proteases activities. Our study demonstrated that cultivation at lower temperatures resulted in higher cell viability, significant improvement of PGL stability and an increase intracellular AOX activity, but a lower activity of released host proteases which possibly caused the degradation of recombinant PGL. In addition, the evidence of higher intracellular adenosine phosphate levels but lower energy charge level was provided at a lower temperature induction.