Finding of Agr Phase Variants in Staphylococcus aureus.

is an important human pathogen whose success is largely attributed to its vast arsenal of virulence factors that facilitate its invasion into, and survival within, the human host. The expression of these virulence factors is controlled by the quorum sensing accessory gene regulator (Agr) system. However, a large proportion of clinical isolates are consistently found to have a mutationally inactivated Agr system.

Adjacent-possible ecological niche: growth of Lactobacillus species co-cultured with Escherichia coli in a synthetic minimal medium.

In certain conditions, members of the Lactobacillus genus are auxotrophs that have fastidious requirements for growth. Notably, Lactobacillus cannot grow in M9 medium, a minimal synthetic medium used for Escherichia coli. However, we found that some Lactobacillus strains can be grown in M9 when co-cultured with E.

Listeria monocytogenes σH Contributes to Expression of Competence Genes and Intracellular Growth.

Unlabelled: The alternative sigma factor σ(H)has two functions in Gram-positive bacteria: it regulates sporulation and the development of genetic competence. Listeria monocytogenes is a nonsporulating species in which competence has not yet been detected. Nevertheless, the main competence regulators and a series of orthologous genes that form the competence machinery are present in its genome; some of the competence genes play a role in optimal phagosomal escape.