Bacterial Succession through the Artisanal Process and Seasonal Effects Defining Bacterial Communities of Raw-Milk Adobera Cheese Revealed by High Throughput DNA Sequencing

Abstract

The bacterial community of the artisanal Adobera cheese from Los Altos de Jalisco was described through high-throughput sequencing of 16S rRNA gene libraries. Samples were collected in two different seasons (dry and rainy) during four key steps of the manufacturing process (raw milk, fresh curd, matured curd, and cheese). Bacterial diversity was higher in early steps in comparison with the final elaboration stages. Firmicutes and Proteobacteria were the most abundant phyla, strongly represented by the Streptococcaceae, Enterobacteriaceae and Lactobacillaceae families, and core bacteria genera such as Streptococcus spp., Lactococcus spp., and Lactobacillus spp. Undesirable bacteria, including Pseudomonas spp. and Acinetobacter spp., were also detected in raw milk but almost undetectable at the end of the cheese manufacturing process, and seemed to be displaced by lactic-acid bacteria-related genera. Seasonal effects were observed on the community structure but did not define the core microbiota composition. Predictive metabolism was related to membrane transport, and amino-acid, lipid, and carbohydrate metabolism pathways. Our results contribute to deduce the role of bacteria involved in Adobera cheese manufacturing in terms of the metabolism involved, cheese microbial safety, and how undesirable bacterial populations could be regulated by process standardization as a potential tool to improve safety.

Genetic characterization of the microbiota of artisan fresh cheese from the Papaloapan region

“…According to Klaenhammer et al (2002), the main genres of the BAL group present in cheese are Lactococcus, Lactobacillus, Leuconostoc, Enterococcus, and Streptococcus. Concordantly, our results also confirmed the presence of these kinds of microorganisms in samples of fresh artisan cheeses (Ruvalcaba-Gómez et al, 2020;Sánchez-Juanes et al, 2020;Yeluri Jonnala et al, 2018). Some strains were found because of the processing of the raw milk, raw milk from the origin to produce the fresh cheeses.…”

“…Undesirable bacteria, including Pseudomonas spp. and Acinetobacter spp., were also detected in raw milk but almost undetectable at the end of the cheese manufacturing process (Ruvalcaba-Gómez et al, 2020). Similarly, the season for sampling was considered to characterize the artisanal Aro cheese.…”

Graduate Student Literature Review: Farm management practices: Potential microbial sources that determine the microbiota of raw bovine milk

“…Seasonality in the diversity of raw milk microbiota has been widely demonstrated (Kable et al, 2016;Li et al, 2018;Ruvalcaba-Gómez et al, 2020). In a longitudinal study involving 10 dairy farms, Li et al (2018) showed that milk microbial communities sampled throughout 12 mo clustered into 2 groups, one comprising fall and spring, and the other summer and winter samples.…”

“…Accordingly, although the abundances of Chitinophaga and Niastella were associated with low humidity, greater temperature and humidity levels generally favored the proliferation of most bacteria (Li et al, 2018). Ruvalcaba-Gómez et al (2020) analyzed the microbial composition of raw milk samples across dry (from November to May) and rainy (from June to October) seasons and found greater abundances of Streptococcaceae and Lactococcus in the dry season, whereas Aeromonadaceae and Acinetobacter were more abundant in the rainy season. Although weather conditions, including temperature and humidity, seem to consistently modulate bacterial groups such as mesophilic or psychrotrophic bacteria, a core microbiota may exist for raw milk.…”

“…, 2007b;Kable et al, 2016;Vithanage et al, 2016;Kmiha et al, 2017;Li et al, 2018;Ruvalcaba-Gómez et al, 2020 Soil Doyle et al, 2016 …”