A high-throughput screening procedure for enhancing pyruvate production in Candida glabrata by random mutagenesis

Candida glabrata is one of the most promising pyruvate producers. A series of experiments was conducted to enhance pyruvate production by C. glabrata via metabolic and genetic engineering. Here, a novel screening strategy, which combined atmospheric and room temperature plasma-based random mutagenesis and high-throughput screening (HTS), was used to screen for high pyruvate-producing mutants that could use cheap industrial raw materials as nitrogen sources. A high-titer pyruvate producer (H6) was obtained form 30,000 mutants after 30 rounds of mutagenesis and HTS. Compared with a wild-type strain, pyruvate production by the H6 mutant was 32.2 and 35.4% higher in 500-mL shake flasks and 3-L fermenter, respectively, when cheap peptone was used as the nitrogen source in the seed culture stage. The HTS process significantly improved the screening efficiency and reduced fermentation cost. This procedure could also easily be applied to screen for strains that produce high titers of similar organic acids.