Oxygen control also determines the functional profile of starter cultures

Oxygen is not a secondary variable when cultures for fermented meats are being developed. A study from the Vrije Universiteit Brussel examined *Staphylococcus shinii* IMDO-S216, a species isolated from fermented meat and genetically close to *S. xylosus*. In a laboratory medium at pH 7.0 and 30 °C, the researchers tracked menaquinone production and transcriptomic responses for 48 hours under high oxygen supply. Intense aeration proved unfavourable for the production of MK-7, a form of vitamin K2. Intracellular MK-7 concentrations declined over time, whereas concentrations in the supernatant remained stable. The pattern was not explained by lower expression of biosynthesis genes. The authors interpret it primarily as oxidative degradation, supported by increased activity of genes associated with oxidative stress and detoxification of reactive oxygen species. The MK-6/MK-7 ratio also increased. The paper proposes that this may reflect a bacterial adaptation strategy, although that remains a hypothesis to be tested in food systems. The design does not replicate a fermented sausage, nor does it show that a factory can directly alter a product’s vitamin content through aeration. Its value is in identifying a mechanism and a process variable that are often overlooked. For starter-culture development, the implication is specific: strain, oxygen and function cannot be specified independently. Where stability, fermentation, colour, aroma or a menaquinone profile are targeted, process atmosphere must be part of the technical specification. Transfer to actual meat matrices requires further trials incorporating salt, nitrite, microbial competition and ripening conditions.