Functional characterization of CYP52G3 fromAspergillus oryzaeand its application for bioconversion and synthesis of hydroxyl flavanone and steroids

Production of 11α-hydroxysteroids from sterols in a single fermentation step by Mycolicibacterium smegmatis

11α-hydroxylated steroid synthons are one of the most important commercially pharmaceutical intermediates used for the production of contraceptive drugs and glucocorticoids. These compounds are currently produced by biotransformation using fungal strains in two sequential fermentation steps. In this work, we have developed by a rational design new recombinant bacteria able to produce 11α-hydroxylated synthons in a single fermentation step using cholesterol (CHO) or phytosterols (PHYTO) as feedstock. We have designed a synthetic operon expressing the 11α-hydroxylating enzymes from the fungus Rhizopus oryzae that was cloned into engineered mutant strains of Mycolicibacterium smegmatis that were previously created to produce 4-androstene-3,17-dione (AD), 1,4-androstadiene-3,17-dione (ADD) from sterols. The introduction of the fungal synthetic operon in these modified bacterial chassis has allowed producing for the first time 11αOH-AD and 11αOH-ADD with high yields directly from sterols in a single fermentation step. Remarkably, the enzymes of sterol catabolic pathway from M. smegmatis recognized the 11α-hydroxylated intermediates as alternative substrates and were able to efficiently funnel sterols to the desired hydroxylated end-products.

Engineering the Steroid Hydroxylating System from Cochliobolus lunatus in Mycolicibacterium smegmatis

14α-hydroxylated steroids are starting materials for the synthesis of contraceptive and anti-inflammatory compounds in the steroid industry. A synthetic bacterial operon containing the cytochrome P450 CYP103168 and the reductase CPR64795 of the fungus Cochlioboluslunatus able to hydroxylate steroids has been engineered into a shuttle plasmid named pMVFAN. This plasmid was used to transform two mutants of Mycolicibacterium smegmatis named MS6039-5941 and MS6039 that accumulate 4-androstene-3,17-dione (AD), and 1,4-androstadiene-3,17-dione (ADD), respectively. The recombinant mutants MS6039-5941 (pMVFAN) and MS6039 (pMVFAN) were able to efficiently express the hydroxylating CYP system of C.lunatus and produced in high yields 14αOH-AD and 14αOH-ADD, respectively, directly from cholesterol and phytosterols in a single fermentation step. These results open a new avenue for producing at industrial scale these and other hydroxylated steroidal synthons by transforming with this synthetic operon other Mycolicibacterium strains currently used for the commercial production of steroidal synthons from phytosterols as feedstock.

Co-metabolic enzymes and pathways of 3-phenoxybenzoic acid degradation by Aspergillus oryzae M-4

As an intermediate metabolite of pyrethroids, 3-phenoxybenzoic acid (3-PBA) is more toxic than its parent compounds and has been detected in milk, soil, and human urine. 3-PBA can be metabolized through microbial degradation, but the microbial co-metabolic enzymes and pathways involved in 3-PBA degradation are unclear. This study investigated the enzymes types and possible pathways in the co-metabolic degradation of 3-PBA by Aspergillus oryzae M-4. The enzymes involved in co-metabolic degradation of 3-PBA and its intermediate metabolites were induced, and existed extracellularly and intracellularly except the catechol-degrading enzyme. Inhibitors and inducers of these oxidases were used to examine the enzymes required for co-metabolic degradation of 3-PBA and its intermediate metabolites. 3-PBA is hydroxylated to produce 3-hydroxy-5-phenoxy benzoic acid through the catalytic actions of lignin peroxidase (LiP). Phenol and gallic acid, the metabolites of 3-PBA, are produced via cleavage of an ether bond under the catalytic actions of cytochrome P450 (CYP450) and LiP. Phenol can be converted to catechol by LiP; catechol and gallic acid are cleaved to form long-chain olefin acid or olefin aldehyde by dioxygenase and LiP. In corn flour, some of these enzyme activators such as FeCl₃, 4-cumaric acid, veratryl alcohol and sodium periodate appeared to improve 3-PBA degradation. The results provide a reliable pathway and characteristics for co-metabolic microbial degradation of 3-PBA in food and the environment.

Identification of fungal enzymes involving 3-phenoxybenzoic acid degradation by using enzymes inhibitors and inducers

Pyrethroid residues in food and the environment can be bio-transformed into 3-phenoxybenzoic acid (3-PBA); It is more toxic than the parent compounds, and has been detected in milk, soil, and human urine. In this study, when incubated at 30 °C and 180 rpm for 48 h, mycelial pellets during logarithmic growth phase were obtained and washed 2 times by phosphate buffer. The cell debris solutions and filter liquor from inducible and non-inducible samples were cultured with 3-PBA and its intermediate metabolites at same condition, and the location and induction of enzymes were analyzed by the degradation. Then Cytochrome P450 (CYP450), lignin peroxidase (LiP), laccase, manganese peroxidase (MnP), and dioxygenase were selected as candidate enzymes due to these oxidases existing in the fungi and capable of degrading the contaminants with similar structures of these compounds, and CuSO₄, NaN₃, AgNO₃, EDTA or piperonyl butoxide (PBO) were used as the enzymes inhibitors and inducers. The degradation of 3-PBA and its intermediate metabolites and the fungal biomass in presence of enzymes inhibitors and inducers was arranged to analyze the possible degrading-enzymes, and the co-metabolic enzymes and pathways can be reasoned. This study provided a promising method for studying the co-metabolic enzymes of 3-PBA degradation by fungi.

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The presented MethodsX was conducted for co-metabolic enzymes and pathways of 3-PBA degradation.

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The culturing condition for presenting enzyme properties were investigated.

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The candidate enzymes were analyzing based on location, induction of enzymes, fungal enzyme systems and chemical structures of these compounds.