• Journal of Microbiology and Biotechnology
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• v.28 no.3
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• pp.439-447
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• 2018

The aromatic compound p-hydroxybenzoate (PHBA) is an important material with multiple applications, including as a building block of liquid crystal polymers in chemical industries. The cytochrome P450 (CYP) enzymes are beneficial monooxygenases for the synthesis of chemicals, and CYP53A15 from fungus Cochliobolus lunatus is capable of executing the hydroxylation from benzoate to PHBA. Here, we constructed a system for the bioconversion of benzoate to PHBA in Escherichia coli cells coexpressing CYP53A15 and human NADPH-P450 oxidoreductase (CPR) genes as a redox partner. For suitable coexpression of CYP53A15 and CPR, we originally constructed five plasmids in which we replaced the N-terminal transmembrane region of CYP53A15 with a portion of the N-terminus of various mammalian P450s. PHBA productivity was the greatest when CYP53A15 expression was induced at $20^{\circ}C$ in $2{\times}YT$ medium in host E. coli strain ${\Delta}gcvR$ transformed with an N-terminal transmembrane region of rabbit CYP2C3. By optimizing each reaction condition (reaction temperature, substrate concentration, reaction time, and E. coli cell concentration), we achieved 90% whole-cell conversion of benzoate. Our data demonstrate that the described novel E. coli bioconversion system is a more efficient tool for PHBA production from benzoate than the previously described yeast system.

• Microbiology and Biotechnology Letters
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• v.23 no.3
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• pp.255-262
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• 1995

Intact cells of Acinetobacter sp. T5-7 completely degraded trichloroethylene (TCE) following growth with phenol. This strain could grow on at least eleven aromatic compounds, e.g., benzaldehyde, benzene, benzoate, benzylalochol, catechol, caffeic acid, 2.4-D, p-hydroxybenzoate, phenol, protocatechuate and salicylate, and did grow on alkane, such as octane. But except phenol, other aromatic compounds did not induced TCE degradation. Phenol biotransformation products, catechol was identified in the culture media. However, catechol-induced cells did not degrade TCE. So we assumed that phenol hydroxylase was responsible for the degradation of TCE. The isolate T5-7 showed growth in MM2 medium containing sodium lactate and catechol rather than phenol, but did not display phenol hydroxyalse activity, suggesting induction of enzyme synthesis by phenol. Phenol hydroxylase activity was independent of added NADH and flavin adenine dinucleotide but was dependent on NADPH addition. Degradation of phenol produced catechols which are then cleaved by meta-fission. We identified catechol-2.3-dioxygenase by active staining of polyacrylamide gel.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2076-2086
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• 2016

Fungal cytochrome P450 (CYP) enzymes catalyze versatile monooxygenase reactions and play a major role in fungal adaptations owing to their essential roles in the production avoid metabolites critical for pathogenesis, detoxification of xenobiotics, and exploitation avoid substrates. Although fungal CYP-dependent biotransformation for the selective oxidation avoid organic compounds in yeast system is advantageous, it often suffers from a shortage avoid intracellular NADPH. In this study, we aimed to investigate the use of bacterial glucose dehydrogenase (GDH) for the intracellular electron regeneration of fungal CYP monooxygenase in a yeast reconstituted system. The benzoate hydroxylase FoCYP53A19 and its homologous redox partner FoCPR from Fusarium oxysporum were co-expressed with the BsGDH from Bacillus subtilis in Saccharomyces cerevisiae for heterologous expression and biotransformations. We attempted to optimize several bottlenecks concerning the efficiency of fungal CYP-mediated whole-cell-biotransformation to enhance the conversion. The catalytic performance of the intracellular NADPH regeneration system facilitated the hydroxylation of benzoic acid to 4-hydroxybenzoic acid with high conversion in the resting-cell reaction. The FoCYP53A19+FoCPR+BsGDH reconstituted system produced 0.47 mM 4-hydroxybenzoic acid (94% conversion) in the resting-cell biotransformations performed in 50 mM phosphate buffer (pH 6.0) containing 0.5 mM benzoic acid and 0.25% glucose for 24 h at $30^{\circ}C$. The "coupled-enzyme" system can certainly improve the overall performance of NADPH-dependent whole-cell biotransformations in a yeast system.