Marinobacter hydrocarbonoclasticus is an aerobic denitrifier

Marinobacter hydrocarbonoclasticus is a marine bacterium widespread in the Mediterranean sea and Atlantic Ocean, and growing at temperate temperatures. This bacterium can perform complete denitrification, reducing nitrate to molecular nitrogen under anaerobic conditions. Here the nitrite concentration, pH and nitrous oxide reductase activity was monitored during bacterial growth, showing that this bacterium can also perform complete denitrification under low oxygen tension, using lactate as carbon source, in the presence of nitrate as alternative electron acceptor. Nitrous oxide reductase activity was observed after 7 h of growth under low oxygen tensions, and is maintained constant after 48h. Nitrite concentration reaches its maximum at mid-exponential phase and in the stationary phase, at lower oxygen tensions is almost non-existent.