Project description:A specific interaction between the mold Scopulariopsis and S. equorum shifts the composition of the Staphylococcus community from dominance by a strong competitor, S. xylosus, to dominance by a weak competitor, S. equorum. To better understand specific genes and pathways involved with Scopulariopsis stimulation of S. equorum, we used RNA-seq to identify CDS that were up- and down-regulated in the genome of S. equorum in the presence and absence of the mold Scopulariopsis. We compared the effect of Scopulariopsis on the S. equorum transcriptome to the effect of Penicillium on the S. equorum transcriptome to determine why Scopulariopsis had such strong growth promotion effects relative to Penicillium. In the presence of both molds, Methionine biosynthesis and uptake pathways are strongly down-regulated, while Thiamine biosynthesis is up-regulated, suggesting that bacterial-fungal interactions alter the availability of free amino acids and nutrients in cheese environment for both partners. In the presence of Scopulariopsis only, there is a decrease in expression of genes involved with iron acquisition and the production of siderophores, notably the staphyloferrin B operon.
2016-09-27 | GSE75505 | GEO
Project description:RNA-sequencing of Staphylococcus equorum co-cultured with Penicillium species on cheese
Project description:RNA-seq was used in combination with various analytical chemistry approaches to identify the chemical and genetic basis of pigment production of the bacterium Glutamicibacter arilaitensis when growing on cheese. This bacterium commonly found in cheese rinds where it co-occurs with Penicillium species and other molds. Pinkish-red pigments are produced by the bacterium in response to growth with Penicillium. Both chemical analyses and RNA-seq point to coproporphyrin III as the major metabolite leading to pigment formation.
Project description:Effect of the presence of Lactococcus lactis on Staphylococcus aureus transcriptome in cheese matrix. S. aureus was co-cultured with L. lactis LD61 in cheese matrix during 7 days. RNA samples were extracted at different time points (6 h, 8 h, 10 h, 24 h and 7 days) in order to monitor the dynamic response of S. aureus MW2 in cheese matrix in presence of L. lactis
Project description:The rate, timing, and mode of species dispersal is recognized as a key driver of the structure and function of communities of macroorganisms, and may be one ecological process that determines the diversity of microbiomes. Many previous studies have quantified the modes and mechanisms of bacterial motility using monocultures of a few model bacterial species. But most microbes live in multispecies microbial communities, where direct interactions between microbes may inhibit or facilitate dispersal through a number of physical (e.g., hydrodynamic) and biological (e.g., chemotaxis) mechanisms, which remain largely unexplored. Using cheese rinds as a model microbiome, we demonstrate that physical networks created by filamentous fungi can impact the extent of small-scale bacterial dispersal and can shape the composition of microbiomes. From the cheese rind of Saint Nectaire, we serendipitously observed the bacterium Serratia proteamaculans actively spreads on networks formed by the fungus Mucor. By experimentally recreating these pairwise interactions in the lab, we show that Serratia spreads on actively growing and previously established fungal networks. The extent of symbiotic dispersal is dependent on the fungal network: diffuse and fast-growing Mucor networks provide the greatest dispersal facilitation of the Serratia species, while dense and slow-growing Penicillium networks provide limited dispersal facilitation. Fungal-mediated dispersal occurs in closely related Serratia species isolated from other environments, suggesting that this bacterial-fungal interaction is widespread in nature. Both RNA-seq and transposon mutagenesis point to specific molecular mechanisms that play key roles in this bacterial-fungal interaction, including chitin utilization and flagellin biosynthesis. By manipulating the presence and type of fungal networks in multispecies communities, we provide the first evidence that fungal networks shape the composition of bacterial communities, with Mucor networks shifting experimental bacterial communities to complete dominance by motile Proteobacteria. Collectively, our work demonstrates that these strong biophysical interactions between bacterial and fungi can have community-level consequences and may be operating in many other microbiomes.
Project description:Aside from their amino acid content, dairy proteins are valuable for their ability to carry encrypted bioactive peptides whose activities are latent until released by digestive enzymes or endogenous enzymes within the food. Peptides can possess a wide variety of functionalities, such as antibacterial, antihypertensive, and antioxidative properties, as demonstrated by in vitro and in vivo studies. This phenomenon raises the question as to what impact various traditional cheese-making processes have on the formation of bioactive peptides in the resulting products. In this study, we have profiled the naturally-occurring peptides in two hard and two soft traditional cheeses and have identified their known bioactive sequences. While past studies have typically identified fewer than 100 peptide sequences in a single cheese, we have used modern instrumentation to identify between 2900 and 4700 sequences per cheese, an increase by a factor of about 50. We demonstrated substantial variations in proteolysis and peptide formation between the interior and rind of each cheese, which we ascribed to the differences in microbial composition between these regions. We identified a total of 111 bioactive sequences among the four cheeses, with the greatest number of sequences, 89, originating from Mimolette. The most common bioactivities identified were antimicrobial and inhibition of the angiotensin-converting enzyme. This work revealed that cheese proteolysis and the resulting peptidomes are more complex than originally thought in terms of the number of peptides released, variation in peptidome across sites within a single cheese, and variation in bioactive peptides among cheese-making techniques.