A bet-hedging strategy for denitrifying bacteria curtails their release of N ₂ O

Abstract

Significance Denitrifying microorganisms reduce nitrate to N 2 via nitrite, NO, and N 2 O under hypoxic/anoxic conditions. Since these organisms are the main sources and sinks for N 2 O in the environment, their regulatory biology controls the emission of this potent greenhouse gas. We demonstrate bet hedging in Paracoccus denitrificans when facing hypoxia: a minority of the cells synthesize NIR + NOR, the N 2 O source, while all synthesize NOS, the N 2 O sink, hence the population becomes a strong net sink for N 2 O. Bet hedging is prominent below 20 °C and data indicate that it is widespread in soil organisms. This suggests a prominent role of bet hedging in controlling N 2 O emissions that can now be tested for in other strains and in natural environments.