Combination of ARTP mutagenesis and color-mediated high-throughput screening to enhance 1-naphthol yield from microbial oxidation of naphthalene in aqueous system

Strain QCG of the aerobic bacteria Bacillus cereus is capable of producing 1-naphthol from naphthalene, this strain was first isolated and characterized in this study. Strain QCG was mutagenized to enhance 1-naphthol production, using atmospheric and room temperature plasma (ARTP) technology. Then, a microbial clone screening system was used to accelerate the operation. Meanwhile, a novel color-mediated high-throughput screening using 4-aminoantipyrine was performed to screen mutants. The optimal mutant strain QCG4 produced 19.58±0.34 mg∙L⁻¹ 1-naphthol from naphthalene that was 47.32% higher than that of the original strain (13.29±0.28 mg∙L⁻¹). In addition, the optimal conditions for 1-naphthol production via whole-cell catalysis of strain QCG4 were determined to be an OD₆₀₀ of 40,150 mg∙L⁻¹ naphthalene, and 7.5% dimethyl formamide as a co-solvent at pH 7.5 and 26°C for 3 h, resulting in 41.18±0.12 mg-L⁻¹ 1-naphthol, i.e., the mutant strain produces a 2.1-fold higher yield compared to the original strain.[Figure not available: see fulltext.]