Milk kefir maintains the microbiological count with probiotic activity throughout the cultivation with a predominance of Lactococcus and Aspergillus genera

Abstract

Kefir is a fermented drink produced from the addition of kefir grains to the cultivation substrate, traditionally milk. The microorganism’s composition present in kefir depends on several factors, such as origin and fermentation time. Its composition classifies it as a probiotic, capable of providing health benefits if regularly consumed. Thus, the present study is aimed to evaluate the microbiological count stability of the kefir over the period of 35 days, pH, and nutritional composition, in addition to analyzing the bacterial and fungal microbiota. To produce fermented milk, kefir grains were cultivated in pasteurized whole milk at a ratio of 1:10, and the bacteria and yeast counting was performed by the surface plating method. Total genomic DNA was extracted and 16S rRNA and ITS amplicon libraries were generated for each sample, which was sequenced on the Illumina MiSeq platform. According to the lactic acid bacteria and yeasts count, the evaluated kefir presented probiotic count, and both the centesimal composition and the mean pH values turned up to be appropriate over time, even with small pH variations. The main bacterial genera found in kefir were Lactococcus, Bacteroides, and Prevotellaceae_UCG-001, and Aspergillus, Beauveria, and Saccharomyces were the predominant fungal genera. The results indicate that the minimum microbiological counts of kefir milk are maintained during the analysis period, with a predominance of Lactococcus and Aspergillus genera.