Effect of Hormones and Biogenic Amines on Growth and Survival of Enterococcus durans.

Lactic acid bacteria (LAB) are important components of the human microbiome. While they are capable both of synthesis and response to the signals of the human humoral regulatory system (hormones and neuromediators), the phenomenology and mechanisms of the LAB response to these mediators are insufficiently studied. This work showed estrogen to hinder the growth and development of E. durans, while norepinephrine, estrogen, and the brain natriuretic peptide caused dose-dependent extension of the stationary growth phase. This is the first report on stimulation of E. durans biofilm formation by the atrial natriuretic peptide and estrogen. The frequency of persister formation depended on the type of bacterial growth (planktonic or biofilm one) and was higher in the case of biofilm growth. Epinephrine and norepinephrine exhibited dose-dependent stimulation of persister formation in planktonic LAB cultures, while other tested hormones inhibited it. The effect on persister formation in biofilms was different: natriuretic peptides exhibited dose-dependent stimulation of persister formation, and none of the hormones inhibited it significantly. After several months of incubation, E. durans persister cells matured to anabiotic dormant forms with the typical ultrastructural features. The population of E. durans dormant forms was first shown to contain the form with different dormancy depth, including the viable uncultured ones. [ABSTRACT FROM AUTHOR]