Insight into the Genome of Staphylococcus xylosus, a Ubiquitous Species Well Adapted to Meat Products

Abstract

Staphylococcus xylosus belongs to the vast group of coagulase-negative staphylococci. It is frequently isolated from meat products, either fermented or salted and dried, and is commonly used as starter cultures in sausage manufacturing. Analysis of the S. xylosus genome together with expression in situ in a meat model revealed that this bacterium is well adapted to meat substrates, being able to use diverse substrates as sources of carbon and energy and different sources of nitrogen. It is well-equipped with genes involved in osmotic, oxidative/nitrosative, and acidic stress responses. It is responsible for the development of the typical colour of cured meat products via its nitrate reductase activity. It contributes to sensorial properties, mainly by the the catabolism of pyruvate and amino acids resulting in odorous compounds and by the limiting of the oxidation of fatty acids, thereby avoiding rancidity.

Keywords: Staphylococcus xylosus; amino acid; antioxidant properties; carbohydrate; iron homeostasis; meat; osmotolerance; starter.

Figure 1

Purine transport, salvage and interconversion in S. xylosus C2a. In red, genes overexpressed in a meat model.

Figure 2

Synthesis of UMP by S. xylosus C2a from pyrimidine and glutamate/glutamine. In red, genes overexpressed in a meat model.

Figure 3

PerR and Fur regulation in S. xylosus C2a. (a) Classic model of PerR and Fur repression of antioxidant response and iron uptake; (b) Impact of reactive nitrogen species (RNS) and reactive oxygen species (ROS), which compete with Fe(II) for PerR and Fur binding, cause antioxidant response and iron uptake.

Figure 4

Pyruvate catabolism in S. xylosus C2a. In red, genes overexpressed in a meat model.

Figure 5

Leucine catabolism in S. xylosus C2a. In red, genes differentially expressed in a meat model.