Abstract:Starting with a bacterium capable of producing pyrroloquinoline quinone（PQQ），single mutagenesis was initially performed using ultraviolet，microwave，and lithium chloride treatments individually，followed by a combined treatment of ultraviolet-microwave-lithium chloride.Research results showed that the optimal conditions were achieved with ultraviolet irradiation for 50 s，microwave exposure（at 350 W）for 60 s，and 0.4% lithium chloride concentration，leading to the isolation of mutant strain C5Y-6-4，which exhibited a shake flask yield of 134.9 mg/L，1.32 times higher than the starting strain. High-throughput screening using a 96-well plate and analysis via high-performance liquid chromatography revealed that the compound mutagenesis approach significantly increased the production of PQQ. Mutant strain C5Y-6-4 showed good genetic stability.