High Level of Interaction between Phages and Bacteria in an Artisanal Raw Milk Cheese Microbial Community.

Microbial starter cultures are used in the production of many cheeses around the world, such as Parmigiano-Reggiano, in Italy, Époisses, in France, and Canastra, in Brazil, providing many of the unique features of these cheeses. Bacteriophages (phages) are ubiquitous and well known to modulate the structure of bacterial communities, and recent data indicate that cheeses contain a high abundance of naturally occurring phages. Here, we analyze the viral and bacterial metagenomes of Canastra cheese: a traditional artisanal Brazilian cheese produced using an endogenous starter culture and raw milk. Over 1,200 viral operational taxonomic units were recovered using both isolated viral-like particles and complete metagenomic DNA. Common viral families identified included Siphoviridae and Myoviridae, with 40% of putative phage genomes unidentified at the family level of classification. We observed very high phage diversity, which varied greatly across different cheese producers, with 28% of phage genomes detected in only one producer. Several metagenome-assembled genomes were recovered for lactic acid-producing bacteria, as well as nonstarter bacterial species, and we identified several phage-bacterium interactions, at the strain level of resolution, varying across distinct cheese producers. We postulate that at least one bacterial strain detected could be endogenous and unique to the Canastra cheese-producing region in Brazil and that its growth seems to be modulated by autochthonous phages present in this artisanal production system. This phage-host relationship is likely to influence the fermentation dynamics and ultimately the sensorial profile of these cheeses, with implications for other similar cheese production systems around the world. IMPORTANCE Our work demonstrated a dynamic yet stable microbial ecosystem during cheese production using an endogenous starter culture. This was observed across several distinct producers and was marked by genomic evidence of continued phage-bacterium interactions, such as the presence of bacterial defense mechanisms. Furthermore, we provide evidence of unique microbial signatures for each individual cheese producer studied in the region, a fact that may have profound consequences on product traceability. This was the first effort to describe and understand the bacteriophage composition and ecological dynamics within the Brazilian Canastra cheese production system. The study of this prototypical backslopping production system provides a solid background for further mechanistic studies of the production of many cheeses around the world.

Caracterização da microbiota de queijos artesanais provenientes da Serra da Canastra - MG e da cultura iniciadora natural utilizada em sua produção / Microbiota characterization of artisanal cheeses from Serra da Canastra - MG and their endogenous starter culture

O queijo Canastra possui grande importância na cultura e economia local, é parte do Patrimônio Imaterial do Brasil (IPHAN, 2014) e recebeu o selo de produto com designação de origem em 2012 (INPI, 2016). Sua produção utiliza leite, sal, coalho e uma cultura iniciadora natural, chamada popularmente de pingo. Esse estudo visou a caracterização da microbiota presente no queijo maturado da Serra da Canastra e no pingo utilizado em sua produção utilizando técnicas avançadas de sequenciamento em larga escala para identificação das bactérias e fungos ali presentes. Nossos dados da microbiota bacteriana foram comparados com dados da microbiota de outros queijos brasileiros e do mundo disponíveis na literatura. As principais bactérias encontradas em amostras de pingo pertencem aos gêneros Lactococcus (45.6%), Streptococcus (30.3%), Staphylococcus (5.1%), e em amostras de queijo aos gêneros Lactococcus (22.5%), Streptococcus (27.2%), Corynebacterium (18.8%), Staphylococcus (13.6%), Leuconostoc (6.3%) e Weissella (6%). Os principais gêneros de fungos encontrados nos queijos foram Debaryomycesa (78.6%), Trichosporona (7.8%). Nosso estudo foi capaz de separar a microbiota dos queijos produzidos na Serra da Canastra de outros queijos na Europa e América do Norte, sendo o pH um possível fator de segregação. Também foi observada uma diferença entre a microbiota do queijo Canastra com outros queijos Brasileiros. Além disso, visualizamos que a distância geográfica entre produtores e a sazonalidade possuem um efeito sobre a microbiota dos pingos e queijos. A partir da análise de todos os microrganismos encontrados na microbiota bacteriana, foram detectados táxons que discriminam produtores por suas aplicações de boas práticas de fabricação e por sua infraestrutura. Observamos proporções menores de um táxon de Kocuria Kristinae nos pingos e um de Streptococcus nos queijos e proporções maiores de um táxon de Staphylococcus nos queijos. Também pudemos observar uma diminuição nas proporções de táxons de Debaryomycesa e aumento na proporção de táxons de Trichosporona na composição fúngica dos queijos, possivelmente devido a transição sazonal do período seco para o chuvoso. Usando técnicas moleculares de sequenciamento em larga escala, demonstramos que há uma diferença na microbiota presente em diferentes áreas da Serra da Canastra, um possível efeito da sazonalidade na composição fúngica e bacteriana. E evidenciamos que táxons de Streptococcus, Staphylococcus e Kocuria estão correlacionados às boas práticas de produção e elucidamos a conexão existente entre a microbiota do pingo e a do queijo. Estes resultados podem influenciar o desenvolvimento de métodos de rastreamento de sub-regiões específicas da Canastra e auxiliar os produtores na produção de queijos de boa qualidade, mantendo as características específicas de sua região

The Canastra cheese has great importance for the local culture and economy, being part of the Intangible Heritage of Brazil (IPHAN, 2014). It has received the protected designation of origin certification in 2012 (INPI, 2016). It's made using milk, salt, rennet and a endogenous starter culture, popularly called as "pingo". This study aimed to characterize the microbiota present in the Serra da Canastra's cheese and the pingo used in its production. In order to conduct this research we used next generation sequencing to identify the bacteria and fungi present there. Our bacterial microbiota dataset was compared with microbiota datasets from other Brazilian and world cheeses available in the literature. The main bacteria found were Lactococcus (45.6%), Streptococcus (30.3%) and Staphylococcus (5.1%) in the endogenous starter samples and Lactococcus (22.5%), Streptococcus (27.2%), Corynebacterium (18.8 %), Staphylococcus (13.6%), Leuconostoc (6.3%) and Weissella (6%) in cheese samples. The main fungi found in the cheeses were Debaryomycesa (78.6%) and Trichosporona (7.8%). We were able to separate the microbiota from Serra da Canastra cheeses and other cheeses in Europe and North America, being the pH a possible segregation factor. Furthermore, a difference was also observed between the microbiota of Canastra and other Brazilian cheeses. In addition, we observed that the geographical distance between producers and the seasonality could be affecting the pingos and cheeses microbiota. We found bacterial taxa that could discriminate producers by their good manufacturing practices and their local infrastructure. Low levels of good manufacturing practices (GMPs) were assigned to bigger proportions of a Kocuria Kristinae taxon in the pingos and a Staphylococcus taxon in the cheeses. Also, higher levels of GMPs were assigned to smaller proportions of Streptococcus taxons in the cheeses. Furthermore We could observe a decrease of Debaryomycesa and an increase of Trichosporona proportions in the fungal composition of cheeses. This could be due to a climate transition: from the dry season to the rainy season. Using large-scale sampling coupled with molecular sequencing techniques, we observe a connection between pingo and cheeses microbiota. We show that the microbiota of different areas in Serra da Canastra is different, also, there is a possible effect of seasonality on fungal and bacterial composition. Furthermore, we could see that Streptococcus, Staphylococcus and Kocuria taxons are correlated with good practices. These results may influence the development of tracking methods for specific Canastra subregions and assist producers to manufacture good quality cheeses while maintaining the specific characteristics of their region