Project description:Azoarcus sp. BH72 is able to communicate via cell density-dependent gene regulation. Here, the impact of cell-free conditioned culture supernatants, obtained from stationary phase Azoarcus wild type cultures, on gene expression was investigated determining changes in transcript profiles when early exponential aerobic cultures were incubated with cell-free culture supernatants for one and four hours. Bacterial communication via quorum sensing (QS) is involved in the regulation of several cellular mechanisms such as metabolic processes, microbe-host interactions or biofilm formation. The nitrogen-fixing model endophyte of grasses Azoarcus sp. strain BH72 shows density-dependent gene regulation in the absence of common hydrophobic autoinducers for pilA encoding the structural protein of type IV pili that are essential for plant colonization. Here, we used a transcriptomic approach to identify target genes differentially regulated under QS conditions in conditioned supernatants in comparison to standard growth conditions.
Project description:Endophytic colonization is a very complex process which is not yet completely understood. Molecules exuded by the plants may act as signals which influence the ability of the microbe to colonize the host or survive in the rhizosphere. Here we investigated whether root exudates of the host might play a role in initiating the endophyte-rice interaction. The whole genome microarray approach was used to investigate the response of the diazotrophic model endophyte, Azoarcus sp. strain BH72, to exudates of O. sativa cv. Nipponbare in order to identify differentially regulated genes. Azoarcus sp. strain BH72 was grown in the presence or absence of root exudates of Oryza sativa cv. Nipponbare for two different time points, and differences in the gene expression profile were monitored.
Project description:Azoarcus sp. BH72 is able to communicate via cell density-dependent gene regulation. Here, the impact of cell-free conditioned culture supernatants, obtained from stationary phase Azoarcus wild type cultures, on gene expression was investigated determining changes in transcript profiles when early exponential aerobic cultures were incubated with cell-free culture supernatants for one and four hours. Bacterial communication via quorum sensing (QS) is involved in the regulation of several cellular mechanisms such as metabolic processes, microbe-host interactions or biofilm formation. The nitrogen-fixing model endophyte of grasses Azoarcus sp. strain BH72 shows density-dependent gene regulation in the absence of common hydrophobic autoinducers for pilA encoding the structural protein of type IV pili that are essential for plant colonization. Here, we used a transcriptomic approach to identify target genes differentially regulated under QS conditions in conditioned supernatants in comparison to standard growth conditions. Analysis used RNA from the early exponential growth phase as control samples for comparison to the quorum-sensing condition samples taken at one hour and four hours after incubation with cell-free culture supernatants.
Project description:Low oxygen tensions are often encountered in flooded soils of rice fields by root-associated, strictly respiratory, beta proteobacterium, Azoarcus sp. BH72 which fixes nitrogen only under microaerobic condition. In this study, genome wide oligonucleotide microarrays were used compare the global transcription profile of Azoarcus sp. BH72 under microaerobic condition with cells grown under aerobic condition, both with ammonia as sole nitrogen source. The outcome of this study will provide a better insight about the establishment of this endophyte in the microaerobic environment, probably prevailing inside of the rice root niche .
