Construction of p-cresol reduction recombinant lactic acid bacterium to decrease p-cresol in Chinese liquor fermentation

Abstract:

[Background] p-cresol is an off-odor in a variety of fermented foods. With low threshold, ppm’s p-cresol can adversely affect the flavor of Chinese liquor. [Objective] Recombinant lactic acid bacterium with p-cresol reduction capability was constructed and tested in Chinese liquor fermentation. [Methods] The genes (creI and creH) coding 4-methylbenzyl phosphate synthase were cloned from Corynebacterium glutamicum and ectopically expressed in Lactobacillus brevis. The reduction capability of creIH overexpression strain was determined in Chinese liquor fermentation. [Results] The creIH overexpression strain eliminated p-cresol up to 2 130 μg/L in liquid medium and 530 μg/kg in simulated solid-state fermented grains. The reduction rate in simulated solid-state fermentation reached 37.9%. [Conclusion] This is the first report that lactic acid bacterium with p-cresol reducing capability was constructed. It provides a novel strategy to eliminate p-cresol in Chinese liquor fermentation.

Key words:p-cresol, Off-odor, Lactic acid bacteria, Chinese liquor fermentation