LIGHT-INDUCED NITROSOMONAS INHIBITION

This study evaluates and verifies the impact of light exposure on an enriched Nitrosomonas culture. Resting cells maintained under aerobic conditions without an exogenous ammonium-nitrogen source were fully inhibited within a 10 min period of ambient light contact (i. e. , fluorescent and indirect natural room light). These cells were, however, protected against this inhibitive phenomenon during active respiration periods and during anoxic exposure conditions. Recovery, albeit partial, from such light induced inhibition was initiated after a 'dark' contact period of approx. 2. 5-3 h without exogenous ammonium presence. Research involving enriched or pure Nitrosomonas cultures (e. g. batch bioassay testing) should consequently be completed under environmental conditions designed to obviate this problem.