Community dynamics of coagulase-negative staphylococci during spontaneous artisan-type meat fermentations differ between smoking and moulding treatments

Coagulase-negative staphylococci (CNS) that are naturally present in the raw meat batter of fermented sausages or that originate from the addition of a starter culture play a role in flavour development. A wide species diversity of CNS can be present in fermented meats, but it is not fully clear yet how specific process parameters select for specific CNS by affecting their community dynamics. Therefore, the influence of smoking and moulding treatments on the CNS community dynamics in spontaneously fermented, artisan-type sausages was investigated. During the fermentation stage, the meat batter was in all cases dominated by Staphylococcus saprophyticus, in addition to Lactobacillus sakei as governing lactic acid bacterium. Following fermentation, the bacterial communities were not perturbed by the smoking treatment, since both L. sakei and S. saprophyticus remained dominant throughout the ripening stage and prevailed in the end-products. Yet, when fermentation was followed by a moulding step with Penicillium nalgiovense, a shift of the CNS communities towards dominance by Staphyloccocus equorum was seen, despite a similar evolution of L. sakei. This effect was possibly due to a pH rise caused by the mould, a hypothesis which was reinforced by the finding that the isolated strain S. equorum DBX-S-17 was more sensitive to low pH than the isolated strain S. saprophyticus DFL-S-12 during growth experiments in brain heart infusion (BHI). Differences in CNS communities may affect sausage flavour, due to intraspecies variations in metabolic conversions of, for instance, amino acids. The fact that 3-methyl-butanal was only found in the moulded sausage, which was dominated by S. equorum, may be related to the finding that the isolated strain of this species was able to produce this compound in BHI medium, whereas the isolated strain of S. saprophyticus was not.