Effects of flavonoids on membrane adaptation of food-associated bacteria.

The effects of naringenin and the biflavonoids amentoflavone and tetrahydroamentoflavone on select bacterial lipids (carotenoids, fatty acids, and menaquinones) and membrane fluidity based on Laurdan generalized polarization were investigated. For this purpose, the pigment-forming food-associated microorganisms Staphylococcus xylosus (DSM 20266 and J70), Staphylococcus carnosus DSM 20501, and Micrococcus luteus (ATCC 9341 and J3) were studied. The results suggest an envelope stress response by microorganisms due to flavonoids and an employment of adaptive mechanisms using carotenoids, fatty acids, and menaquinones.

Engineered CRISPR/Cas9 System for Transcriptional Gene Silencing in Arthrobacter Species Indicates Bacterioruberin is Indispensable for Growth at Low Temperatures.

Pink-pigmented Arthrobacter species produce the rare C carotenoid bacterioruberin, which is suspected to be part of the cold adaptation mechanism. In silico analysis of the repertoire of genes encoded by the Arthrobacter agilis and Arthrobacter bussei genome revealed the biosynthetic pathway of bacterioruberin. Although genetic analysis is an essential tool for studying the physiology of Arthrobacter species, genetic manipulation of Arthrobacter is always time and labor intensive due to the lack of genetic engineering tools.

Exogenous fatty acids affect membrane properties and cold adaptation of Listeria monocytogenes.

Listeria monocytogenes is a food-borne pathogen that can grow at very low temperatures close to the freezing point of food and other matrices. Maintaining cytoplasmic membrane fluidity by changing its lipid composition is indispensable for growth at low temperatures. Its dominant adaptation is to shorten the fatty acid chain length and, in some strains, increase in addition the menaquinone content.

The C carotenoid bacterioruberin regulates membrane fluidity in pink-pigmented Arthrobacter species.

Carotenoids have several crucial biological functions and are part of the cold adaptation mechanism of some bacteria. Some pink-pigmented Arthrobacter species produce the rare C carotenoid bacterioruberin, whose function in these bacteria is unclear and is found mainly in halophilic archaea. Strains Arthrobacter agilis DSM 20550 and Arthrobacter bussei DSM 109896 show an increased bacterioruberin content if growth temperature is reduced from 30 down to 10 °C.

Menaquinone-mediated regulation of membrane fluidity is relevant for fitness of Listeria monocytogenes.

Listeria monocytogenes is a food-borne pathogen with the ability to grow at low temperatures down to - 0.4 °C. Maintaining cytoplasmic membrane fluidity by changing the lipid membrane composition is important during growth at low temperatures.

sp. nov., a pink-coloured organism isolated from cheese made of cow's milk.

A pink-coloured bacterium (strain KR32) was isolated from cheese and assigned to the ' group'. Members of the 'pink group' form a stable clade (100 % bootstrap value) and contain the species , and , which share ≥99.0 % 16S rRNA gene sequence similarity.

Increased Isoprenoid Quinone Concentration Modulates Membrane Fluidity in Listeria monocytogenes at Low Growth Temperatures.

is a food pathogen capable of growing at a broad temperature range from 50°C to refrigerator temperatures. A key requirement for bacterial activity and growth at low temperatures is the ability to adjust the membrane lipid composition to maintain cytoplasmic membrane fluidity. In this study, we confirmed earlier findings that the extents of fatty acid profile adaptation differed between strains.

Electron Accepting Units of the Diheme Cytochrome c TsdA, a Bifunctional Thiosulfate Dehydrogenase/Tetrathionate Reductase.

The enzymes of the thiosulfate dehydrogenase (TsdA) family are wide-spread diheme c-type cytochromes. Here, redox carriers were studied mediating the flow of electrons arising from thiosulfate oxidation into respiratory or photosynthetic electron chains. In a number of organisms, including Thiomonas intermedia and Sideroxydans lithotrophicus, the tsdA gene is immediately preceded by tsdB encoding for another diheme cytochrome.