Growth characteristics and metabonomics analysis of Lactobacillus rhamnosus GG in Ganoderma lucidum aqueous extract medium

Ganoderma lucidum, with a long history of medicinal use and good nutritional value, is regarded as a health food. The G. lucidum fruiting body extract has been proposed as a fermentation medium to promote the growth of probiotic organisms such as Lactobacilli. However, the effects of G. lucidum on the bioactivity and fermentation metabolites of Lactobacillus rhamnosus GG (LGG) require further studies. In this study, the effects of G. lucidum aqueous extract (GLE) on the growth of LGG were evaluated. During the 48-h fermentation, lactic acid content increased from 0 to 4.64 mg/ml and the pH was reduced from 5.8 to 4.0. The effect of GLE on the key metabolites of LGG was analyzed using non-targeted metabonomics based on LC-MS/MS. Metabonomics analysis identified pyrocatechuic acid, taurocholic acid, estradiol and other differential metabolites with clear physiological functions. These metabolites were significantly enriched over 10 metabolic pathways including pyrimidine metabolism, tyrosine metabolism, alanine, aspartate and glutamate metabolism. These metabolites and metabolic pathways propose that LGG has better probiotic effect when fermented with GLE. These findings provide theoretical support for the application of G. lucidum extract to improve Lactobacilli probiotic benefits.