Isolation of A Bacillus cereus Strain HBL-AI and its Application for Production of Trans-4-hydroxy-L-proline

A new trans-4-Hydroxy-L-proline (trans-Hyp) producing Bacillus cereus HBL-AI, was isolated from the air, which was screened just using L-proline as carbon and energy sources. This strain exhibited 73.4% bioconversion rate from initial L-proline (3 g l^-1 ) to trans-Hyp. By sequencing the genome of this bacterium, 6244 coding sequences were obtained. Genome annotation analysis and functional expression were used to identify the proline-4-hydroxylase (BP4H) in HBL-AI. This enzyme belonged to a family of 2-oxoglutarate-related dioxygenases, which required 2-oxoglutarate and O₂ as co-substrates for the reaction. Homologous modelling indicated that the enzyme had two monomers and contained conserved motifs, which included a distorted 'jelly roll' β strand core and the residues (HXDXnH and RXS). The engineering Escherichia coli 3 Δ W3110 / pTrc99a-proba-bp4h was constructed using BP4H, which transform glucose to trans-Hyp in one step with high concentration of 46.2 g l^-1 . This strategy provides a green and efficient method for synthesis of trans-Hyp and thus has a great potential in industrial application.

Keywords: Bacillus cereus; Bioconversion; Genomic sequence; Proline-4-hydroxylase; Trans-4-hydroxy-L-proline.