Abstract:[Objective] This study aims to elucidate the interactions between Lactobacillus crispatus CCFM1298 and Lactobacillus gasseri CCFM1201 in a co-culture system, thereby providing a theoretical basis for the development of multi-strain probiotic preparations. [Method] By the design of selective counting medium, the viable cell counts of the two probiotic strains in the co-culture system were monitored, and the interactions of the two strains were elucidated based on the results. [Result] Adjusting the osmotic pressure of the medium to 1 600 mOsmol/kg enabled effective isolation and accurate counting of the two probiotic strains in the co-culture system. Regardless of the initial inoculation ratio, after co-culture in the MRS broth, Lactobacillus gasseri CCFM1201 always emerged as the dominant strain, which was attributed to its shorter generation time than that of Lactobacillus crispatus CCFM1298 (P<0.01). The experiment aiming to balance the generation time showed that fructooligosaccharides effectively alleviated the competition for nutrient niches between the two strains, thereby preventing imbalanced growth. [Conclusion] The study preliminarily reveals the interaction between the two probiotic strains and the method to effectively mitigate the imbalanced growth. The findings provide new strategies for the rational design and functional optimization of subsequent multi-strain probiotic preparations.
