Production of the PGA in Pichia pastoris: the role of the cell physiology in secretion of heterologous penicillin G acylase
Abstrakt
The design and implementation of an efficient process for industrial production of penicillin G acylase (PGA) is of great relevance, since it is used for kinetically-controlled and environmentally-friendly synthesis of β-lactam antibiotics. Established production processes using bacterial expression systems involve laborious purification steps.
As an economically feasible alternative, heterologous production of recombinant PGA with Pichia pastoris promises efficient secretion of correctly folded protein into the culture supernatant. In a process with recombinant Pichia pastoris producing PGA from E. coli, the specific product formation rate (qp) was found to be a nonlinear function of the specific growth rate (µ) with maximum productivity between 0.05 and 0.08 h-1.
In contrast to expectations, a large proportion of active enzyme (40-80%) was not secreted and remained associated with the cell. The efficiency of secretion tended to be time dependent and the ratio of intra- to extracellular active enzyme decreased with cultivation time.
In-depth studies of the physiology and behaviour of the host strain in a production process is therefore necessary to facilitate the development of an appropriate cultivation strategy to produce PGA in amounts that are feasible for large-scale manufacturing.