Cobalt-dependent inhibition of nitrite oxidation in Nitrobacter winogradskyi

Publication date: Available online 24 April 2019Source: Journal of Bioscience and BioengineeringAuthor(s): Richard Metzner, Taiji Nomura, Naoki Kitaoka, Akinori Ando, Jun Ogawa, Yasuo KatoNitrobacter winogradskyi is an abundant, intensively studied autotrophic nitrite-oxidizing bacterium, which is frequently used as a model strain in the two-step nitrification of ammonia (NH3) to nitrate (NO3−) via nitrite (NO2−), either in activated sludge, agricultural field studies or more recently in artificial microbial consortia for organic hydroponics. We observed a hitherto unknown cobalt ion-dependent inhibition of cell growth and NO2− oxidation activity of N. winogradskyi in a mineral medium, which strongly depended on accompanying Ca2+ and Mg2+ concentrations. This inhibition was bacteriostatic, but susceptible to natural chelators. l-Histidine effectively restored cell growth and NO2− oxidation activity of N. winogradskyi in mineral media containing Co2+ with>90% recovery. Our results suggest that Co2+ competed with alkaline earth metals during uptake and that its toxicity was significantly reduced by complexation.Graphical abstract
Source: Journal of Bioscience and Bioengineering - Category: Biomedical Science Source Type: research