Isolation of a Bacillus cereus strain HBL‐AI and its application for production of T rans ‐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 transformed 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. Significance and Impact of the Study: A Bacillus cereus capable of biotransforming l‐proline to Trans‐4‐hydroxy‐l‐proline (trans‐Hyp) was isolated from the air for the first time. Trans‐Hyp‐producing engineering Escherichia coli was constructed utilizing proline‐4‐hydroxylase in it, which exhibited a high ability on trans‐Hyp production from glucose by one‐step process. This study provides a green and environmentally friendly hydroxylase candidate for the efficient industrial production of trans‐Hyp.