Improved secretory production of calf prochymosin by codon optimization and disruption of PMR1 in Kluyveromyces lactis GG799

Chymosin as an important industrial enzyme used widely in cheese manufacture. In our preliminary study, low yields (80 U mL -1 ) were obtained when Kluyveromyces lactis GG799 was used to express chymosin. We investigated whether this poor secretion could be improved by codon optimization and disruption of PMR1 gene in K. lactis GG799. Our study shows that combination of codon optimization and disruption of the PMR1 gene resulted in secretion level of chymosin that was increased 10-fold. Our results show that codon optimization and disruption of the PMR1 gene synergistically stimulate the secretion of calf prochymosin in K. lactis GG799. Key words: Kluyveromyces lactis, codon optimization, PMR1, prochymosin.