A Novel Enterococcus faecalis Heme Transport Regulator (FhtR) Senses Host Heme To Control Its Intracellular Homeostasis.

is a commensal Gram-positive pathogen found in the intestines of mammals and is also a leading cause of severe infections occurring mainly among antibiotic-treated dysbiotic hospitalized patients. Like most intestinal bacteria, does not synthesize heme (in this report, heme refers to iron protoporphyrin IX regardless of the iron redox state). Nevertheless, environmental heme can improve fitness by activating respiration metabolism and a catalase that limits hydrogen peroxide stress.

Visualization of the role of host heme on the virulence of the heme auxotroph Streptococcus agalactiae.

Heme is essential for several cellular key functions but is also toxic. Whereas most bacterial pathogens utilize heme as a metabolic cofactor and iron source, the impact of host heme during bacterial infection remains elusive. The opportunist pathogen Streptococcus agalactiae does not synthesize heme but still uses it to activate a respiration metabolism.

HrtBA and menaquinones control haem homeostasis in Lactococcus lactis.

Lactococcus lactis is a fermenting Gram-positive bacterium widely used for production of dairy products. Lacking haem biosynthesis genes, L. lactis can still shift to an energetically favourable respiratory metabolism by activating a terminal cytochrome bd oxidase when haem is added to an aerated culture.