Study on the effect of fermented dairy products on human gut bacteria

Abstract

Milk was introduced as a major component of diet since Neolithic era when dairy newlinepastoralism became a subsistence practice worldwide. Milk revolution was the prime newlinefactor in displacing hunter gatherer cultures. Milk and its various fermented products newlineprovide complete nutrition to humans. Modernization has brought different dairy newlineproducts with a global commercial value of US$ 45/ton. Fermented dairy products newline(FDP) harbor beneficial microbes that provide several health benefits, such as protection newlineagainst diarrhoea, regulating blood pressure, and cholesterol. Curd, also best known as newlineyogurt, is the most popular fermented dairy product consumed worldwide, but the newlinemethod of preparation varies across the world. Few ethnic tribes still practice the newlineartisanal approach of fermenting milk. In Assam, people prefer curds which are newlineprepared using the traditional method using raw milk. This study aimed to understand newlinethe microbial and metabolite profiles of curd which is widely consumed in Assam, newlineIndia. Further, to know the impact of such dairy consumption on health, the gut newlinemicrobiome composition of curd consumers was also studied. The culture-dependent newlinebacterial analysis revealed that raw milk (RM) harbor lactic acid and non-lactic acid newlinebacteria, while boiled milk (BM) harbors mostly bacteria from the environment. Curd newlineprepared from raw milk (RMC) was enriched with lactic acid bacteria whose abundance newlinewas found to be less in RM. While curd prepared from boiled milk (BMC) didn t share newlineany isolated genera with the milk. RMC and BMC shared common lactic acid bacterial newlinegenera. However, a denaturing gradient gel electrophoresis (DGGE) revealed that the newlinemicrobial profile of RMC was much different and diverse than BMC. To overcome the newlinelimitation of conventional methods, representative samples were subjected to next newlinegeneration sequencing (NGS) on Illumina platform for 16S rDNA amplicon sequencing. newlineIt was observed that the microbial diversity in the dairy products was farm-specific. newlineFew important uncultivable bacterial genera