Cloning, expression and characterization of a pectate lyase from Paenibacillus sp. 0602 in recombinant Escherichia coli.

BACKGROUND

Biotechnological applications of microbial pectate lyases (Pels) in plant fiber processing are considered as environmentally friendly. As such, they become promising substitutes for conventional chemical degumming process. Since applications of Pels in various fields are widening, it is necessary to explore new pectolytic microorganisms and enzymes for efficient and effective usage. Here, we describe the cloning, expression, characterization and application of the recombinant Pel protein from a pectolytic bacterium of the genus Paenibacillus in Escherichia coli.

RESULTS

A Pel gene (pelN) was cloned using degenerate PCR and inverse PCR from the chromosomal DNA of Paenibacillus sp. 0602. The open reading frame of pelN encodes a 30 amino acid signal peptide and a 445 amino acid mature protein belonging to the polysaccharide lyase family 1. The maximum Pel activity produced by E. coli in shake flasks reached 2,467.4 U mL⁻¹, and the purified recombinant enzyme exhibits a specific activity of 2,060 U mg⁻¹ on polygalacturonic acid (PGA). The maximum activity was observed in a buffer with 5 mM Ca²⁺ at pH 9.8 and 65°C. PelN displays a half-life of around 9 h and 42 h at 50°C and 45°C, respectively. The biochemical treatment achieved the maximal reduction of percentage weight (30.5%) of the ramie bast fiber.

CONCLUSIONS

This work represents the first study that describes the extracellular expression of a Pel gene from Paenibacillus species in E. coli. The high yield of the extracellular overexpression, relevant thermostability and efficient degumming using combined treatments indicate its strong potential for large-scale industrial production.