Impact of container type on the microbiome of airag, a Mongolian fermented mare's milk

Airag, a fermented mare's milk in Mongolia, exhibits diverse flavors and microbiota due to distinct production processes and environments in nomadic households. Recently, there has been a shift from the traditional cow skin container, 'khokhuur', to a plastic container for airag production, potentially impacting the microbiota and quality. To address this notion, we aimed to elucidate the differences in the microbiota between airag samples from a plastic container and those from a khokhuur. We collected airag samples produced using either a plastic container or khokhuur from three houses in Mogod Sum (county) in Bulgan Aimag (province) and analyzed the chemical and microbiome properties of the obtained samples. Compared with the khokhuur, the plastic containers exhibited high heat retention at night and boosted lactate production, which sustained a lower pH level in airag. A series of alpha diversity indices of airag microbiota were significantly higher in airag produced in khokhuurs than in those produced in the plastic containers. In particular, Lactobacillus helveticus was the most dominant species, accounting for more than 90% of the total population in airags produced in the plastic containers and khokhuur, whereas some other lactic acid bacteria species and environmental bacteria more colonized airags produced in khokhuurs. The khokhuur itself is likely a source of these bacterial species and likely provides a niche, and the wider volatility of temperature may allow the growth of this wide range of bacteria while maintaining a lower level of lactic acid fermentation.