Carnitine acts as a compatible solute in Brevibacterium linens

Carnitine is a trimethyl amino acid found at relatively high concentrations in materials of animal origin. Exogenously provided L-carnitine was found to stimulate growth of Brevibacterium linens ATCC 19391 in media with inhibitory osmotic strength. Its osmoprotective ability was as potent as that of glycine betaine. Electrophoretic and spectroscopic (NMR) analysis showed that this compound is only transiently accumulated, but in significant amounts, by B. linens under hyperosmotic stress and is converted into glycine betaine. The L-carnitine/glycine betaine pathway is inducible by L-carnitine in B. linens. The D-enantiomer did not improve growth of B. linens, even though this solute is accumulated by B. linens at the same level as glycine betaine. The two isomeric forms of carnitine repress the build-up of ectoine, the main endogenous osmolyte in B. linens.