Molecular characterization of bacterial communities in sheep cheese through 16S rRNA gene sequencing

Abstract

25The production of sheep's milk cheese has grown in recent years since it is a high value-26 added product with excellent properties. As such, it is necessary to provide data on the 27 microbiota and organoleptic characteristics of this product, as well as the influence of 28 these microorganisms on public health. Thus, the aim of the present study was to 29 characterize the microbial community of different types of sheep cheeses using high-30 throughput sequencing of the 16S rRNA gene. The study was conducted with four groups 31 of cheese: colonial, fresh, feta, and pecorino (n = 5 samples per group). The high-32 throughput 16S rRNA amplicon sequencing revealed 55 operational taxonomic units in 33 the 20 samples, representing 9 genera of the two bacterial phyla Firmicutes and 34 Proteobacteria. The predominant genera in the samples were Streptococcus and 35 Lactobacillus. When evaluating alpha diversity by the indexes of Simpson, Chao1, 36Shannon, and Skew no significant differences were observed between the groups. 37Evaluating of the beta diversity using Bray-Curtis dissimilarity, the group of colonial 38 cheeses presented a significant difference when compared to the feta (q = 0.030) and 39 pecorino groups (q = 0.030). Additionally, the fresh group differed from the pecorino 40 group (q = 0.030). The unweighted Unifrac distance suggests that the colonial cheese 41 group differed from the others. Moreover, the feta cheese group differed from the fresh 42 group. The distance-weighted Unifrac suggests that no significance exists between the 43 groups. According to this information, the microbiota characterization of these cheese 44 groups was useful in demonstrating the bacterial communities belonging to each group, 45 its effects on processing, elaboration, maturation, and public health. 46Sheep cheese production has been increasing globally and represents a major 50 economic driver in many countries, especially in Europe. In Brazil, the main sheep 51 cheeses produced are colonial (locally produced cheese), fresh (not matured), pecorino, 52 and feta. Sheep cheeses are good sources of protein, energy, fat, minerals, and vitamins 53 [1], which have a direct relation to the taste, odor, and texture of the products. Sheep 54 cheeses have a thin, delicate dough, a mild and slightly acidic flavor, thus resembling the 55 typical taste of sheep's milk. The soft cheeses (fresh and feta) have a relatively high 56 moisture content (44,6% to 45,9%) with a more pronounced acidity, while hard cheeses 57 (colonial and pecorino) have a more solid texture and lower moisture content (35,9% to 58 38,3%). Apart from these differences in composition, the organoleptic characteristics of 59 these cheeses may vary according to the producing farm, season, animal feeding regimen, 60 and animal breed [2]. Moreover, the microbiota composition also influences cheese 61 characteristics and may have an impact on consumer health. Moreover, the microbial 62 communities of these cheeses represent largely unexplored reservoirs of genetic and 63...

The Ambiguous Nature of some Non-Starter Lactic Acid Bacteria Actively Participating in Cheese Ripening

“…Different CNS species have been identified as a part of the dominant and subdominant microflora of many kinds of traditional cheeses [106,107] (Table 1). M. sciuri, despite being mainly associated with the ripening of fermented meat products such as cured meats and saussages [88,108,109], it has also been found in French smear cheeses [106], German cheeses [107], Brazilian cheeses [110] and the traditional Middle East Surk cheese [111] (Table 1).…”