Microbial community diversity associated with Tibetan kefir grains and its detoxification of Ochratoxin A during fermentation

Tibetan kefir grains (TKG) are multi-functional starter cultures used in foods and have been applied in various fermentation systems. This study aimed to investigate the microbial community composition of TKG, the detoxification abilities of TKG and their isolates towards common mycotoxins, and the potential for applying TKG and their associated microbial populations to avoid mycotoxin contamination in dairy products. Cultivation-independent high-throughput sequencing of bacterial and fungal rDNA genes indicated that Lactobacillus kefiranofaciens and Kazachstania turicensis were the most abundant bacterial and fungal taxa, respectively. In addition, 27 total isolates were obtained using cultivation methods. TKG removed more than 90% of the Ochratoxin A (OTA) after 24 h, while the isolate Kazachstania unisporus AC-2 exhibited the highest removal capacity (~46.1%). Further, the isolate exhibited good resistance to acid and bile salts environment. Analysis of the OTA detoxification mechanism revealed that both adsorption and degradation activities were exhibited by TKG, with adsorption playing a major detoxification role. Furthermore, the addition of OTA did not affect the microbial community structure of TKG. These results indicate that TKG-fermented products can naturally remove mycotoxin contamination of milk and could potentially be practically applied as probiotics in fermentation products.