Project description:Pure cultures of ammonia oxidizing bacterium, Nitrosomonas europaea, are exposed to cyanide in pseudo-steady state batch reactor in presence of ammonia. Nitrosomonas europaea are generally regarded as the most sensitive organism to various inhibitors commonly encountered in the wastewater treatment plants (WWTP). To find stress genes of Nitrosomonas europaea to cyanide known as inhibitor of respiratory process, whole-genome transcript response to cyanide was determined in this research using microarray and qRT-PCR. When 1 uM NaCN inhibits nitrification about 50 %, transcript levels of 35 genes were increased while transcript levels of 29 genes were decreased, showing more than 2-fold in total 2460 genes. moeZ (NE2353), homologue with rhodanases related to detoxification of CN-, showed 7-fold up regulation and gene cluster including moeZ also showed significant up regulation. Keywords: cyanide, stress response, moeZ
Project description:Pure cultures of ammonia oxidizing bacterium, Nitrosomonas europaea, are exposed to cyanide in pseudo-steady state batch reactor in presence of ammonia. Nitrosomonas europaea are generally regarded as the most sensitive organism to various inhibitors commonly encountered in the wastewater treatment plants (WWTP). To find stress genes of Nitrosomonas europaea to cyanide known as inhibitor of respiratory process, whole-genome transcript response to cyanide was determined in this research using microarray and qRT-PCR. When 1 uM NaCN inhibits nitrification about 50 %, transcript levels of 35 genes were increased while transcript levels of 29 genes were decreased, showing more than 2-fold in total 2460 genes. moeZ (NE2353), homologue with rhodanases related to detoxification of CN-, showed 7-fold up regulation and gene cluster including moeZ also showed significant up regulation. Keywords: cyanide, stress response, moeZ The 1 uM NaCN caused more than 50 % inhibition in physiological response for 1 hour incubation. Transcriptional levels of the cells inhibited by cyanide were compared with the cells under control condition.
Project description:Heavy metals have been postulated as significant nitrification inhibitor in wastewater treatment plant. The effect of heavy metals such as Cd2+, Cu2+ and Hg2+ to nitrifying bacterium, Nitrosomonas europaea, was studied in pseudo-steady state batch reactor. Under incubation of Nitrosomonas europaea with 1 ?M CdCl2 for 1 hour, transcripts for 66 of 2460 genes were found at high level, yet transcripts of 50 genes were found at low level. Mercury resistance genes (merACDPT) showed 277-fold up regulation. Keywords: cadmium, stress response, global transcription, mercury resistance genes, merA,
Project description:Global gene expression was compared between Nitrosomonas europaea wild-type and a nitrite reductase-deficient mutant using a genomic microarray. Keywords: wild-type to mutant global transcriptome comparison
Project description:Investigation of the whole genome gene expression level changes relative to exponential phase growth in Nitrosomonas europaea ATCC19718 after 12 hours ammonia starvation, 144 hours ammonia starvation, and 20 minutes following ammonia addition to starved cells. The ammonia monooxygenase of chemolithotrophic ammonia oxidizing bacteria (AOB) catalyzes the first step in ammonia oxidation by converting ammonia to hydroxylamine. The monooxygenase of Nitrosomonas europaea is encoded by two nearly identical operon copies (amoCAB1,2). Several AOB, including N. europaea, also posess a divergent monocistronic copy of amoC (amoC3) of unknown function. Previous work suggested a possible functional role for amoC3 in N. europaea during recovery from extended ammonia starvation as part of the σE- stress response regulon during the recovery of N. europaea from extended ammonia starvation, thus indicating its importance during the exit of cells from starvation. We here used global transcription analysis to show that expression of amoC3 is part of a general post-starvation cellular response system in N. europaea. We also found that amoC3 is required for efficient exit from prolonged ammonia starvation, as deleting this gene impaired growth at elevated temperatures and recovery following starvation under high oxygen tensions. Deletion of the σ32 global stress response regulator demonstrated that the heat shock regulon also plays a significant role in mediating the recovery of N. europaea from starvation. These findings provide the first described phenotype associated with the divergent AmoC3 subunit which appears to function as a stress responsive subunit capable of maintaining ammonia oxidation activity under stress conditions. A twelve chip study using total RNA recovered from four timepoints for each of three biological replicates of wild-type cultures of Nitrosomonas europaea ATCC 19718. Total RNA was obtained from each biological culture replicate during exponential growth, following 12 hours ammonia starvation, 144 hours ammonia starvations, and 20 minutes following ammonia addition to starved cells.