Racemization in reverse: evidence that D-amino acid toxicity on Earth is controlled by bacteria with racemases.

ABSTRACT: D-amino acids are toxic for life on Earth. Yet, they form constantly due to geochemical racemization and bacterial growth (the cell walls of which contain D-amino acids), raising the fundamental question of how they ultimately are recycled. This study provides evidence that bacteria use D-amino acids as a source of nitrogen by running enzymatic racemization in reverse. Consequently, when soils are inundated with racemic amino acids, resident bacteria consume D- as well as L-enantiomers, either simultaneously or sequentially depending on the level of their racemase activity. Bacteria thus protect life on Earth by keeping environments D-amino acid free.

SUBMITTER: Zhang G 

PROVIDER: S-EPMC3960212 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature