Impact of milk inoculation with Brucella abortus on microbiome profiling of Minas artisanal cheese during ripening

Abstract

The in-depth characterization of the Minas Artisanal Cheese (QMA) microbiome is essential for understanding its sensory identity, fermentation processes, and its role in sanitary safety, especially when produced from raw milk. Considering the zoonotic relevance of Brucella abortus bacteria and the absence of scientific consensus on its behavior in Brazilian artisanal cheeses, this work investigated the microbial dynamics of cheeses produced under controlled conditions and inoculated with different loads of the pathogen (103 and 106 CFU/mL), tracking their evolution over seven ripening periods. Through high-throughput sequencing of the V3–V4 regions of the 16S rRNA gene, coupled with robust bioinformatics analyses (QIIME2) and microbial diversity metrics in R, it was possible to identify 6,888 ASVs distributed among 301 bacterial genera, in addition to quantifying the persistence and decline of B. abortus. A clear microbial succession was observed, driven by the increase of Lactiplantibacillus ASVs and the gradual reduction of Lactococcus, accompanied by significant structural changes in the bacterial community over time, mainly in the group with the highest inoculation. At both inoculation levels, the relative abundance of B. abortus decreased substantially during maturation, evidencing the protective role of the acidified environment and the competitive action of lactic acid bacteria. The results suggest that the ripening process acts as an effective biological barrier against B. abortus, even in high initial load scenarios, contributing relevant scientific evidence for food safety and regulatory policies aimed at artisanal production.