Limits...
Anthropogenic impact on diazotrophic diversity in the mangrove rhizosphere revealed by nifH pyrosequencing.

Jing H, Xia X, Liu H, Zhou Z, Wu C, Nagarajan S - Front Microbiol (2015)

Bottom Line: The metabolic capacities of these diazotrophs indicate the potential for bioremediation and resiliency of the ecosystem to anthropogenic impact.In heavily polluted locations, the diazotrophic community structures were markedly different and the diversity of species was significantly reduced when compared with those in a pristine location.This, together with the increased abundance of Marinobacterium, which is a bioindicator of pollution, suggests that anthropogenic activity has a negative impact on the genetic diversity of diazotrophs in the mangrove rhizosphere.

View Article: PubMed Central - PubMed

Affiliation: Sanya Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences Sanya, China.

ABSTRACT
Diazotrophs in the mangrove rhizosphere play a major role in providing new nitrogen to the mangrove ecosystem and their composition and activity are strongly influenced by anthropogenic activity and ecological conditions. In this study, the diversity of the diazotroph communities in the rhizosphere sediment of five tropical mangrove sites with different levels of pollution along the north and south coastline of Singapore were studied by pyrosequencing of the nifH gene. Bioinformatics analysis revealed that in all the studied locations, the diazotroph communities comprised mainly of members of the diazotrophic cluster I and cluster III. The detected cluster III diazotrophs, which were composed entirely of sulfate-reducing bacteria, were more abundant in the less polluted locations. The metabolic capacities of these diazotrophs indicate the potential for bioremediation and resiliency of the ecosystem to anthropogenic impact. In heavily polluted locations, the diazotrophic community structures were markedly different and the diversity of species was significantly reduced when compared with those in a pristine location. This, together with the increased abundance of Marinobacterium, which is a bioindicator of pollution, suggests that anthropogenic activity has a negative impact on the genetic diversity of diazotrophs in the mangrove rhizosphere.

No MeSH data available.


A NJ tree to show the phylogenetic relationship of the most abundant 50 OTUs with affiliated canonical nifH clusters (Chien and Zinder, 1996) indicated by colored branches. Bootstrap value greater than 50% is shown (calculated 1,000 times).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4612719&req=5

Figure 4: A NJ tree to show the phylogenetic relationship of the most abundant 50 OTUs with affiliated canonical nifH clusters (Chien and Zinder, 1996) indicated by colored branches. Bootstrap value greater than 50% is shown (calculated 1,000 times).

Mentions: Phylogenetic trees constructed using NJ and maximum-likelihood methods had congruent tree topology. The NJ phylogenetic tree for the 20 most abundant OTUs demonstrated that 13 of them fell into cluster I, and the rest were in cluster III (Figure 3). Among the cluster I OTUs, seven were affiliated with Marinobacteium lutimaris, Vibrio diazotrophicus, and Pseudomonas stutzeri, which belong to the class of β/γ-Proteobacteria; one was affiliated with Scytonema sp., a cyanobacterial diazotroph; two were affiliated with Azorhizobium doebereinerae and Gluconacetobacter diazotrophicus in the α-Proteobacteria class; and two were closely related to Pelobacter carbinolicus in the δ-Proteobacteria class. Within cluster III, four OTUs grouped with Desulfobotulus alkaliphilus, whereas the remaining three were clustered with Desulfovibrio sp. In addition, a phylogenetic tree based on the 50 most abundant OTUs (Figure 4) indicated that several (i.e., OTU18, 29, 39, and 43) fell into Cluster II, and were affiliated with Azomonas macrocytogenes.


Anthropogenic impact on diazotrophic diversity in the mangrove rhizosphere revealed by nifH pyrosequencing.

Jing H, Xia X, Liu H, Zhou Z, Wu C, Nagarajan S - Front Microbiol (2015)

A NJ tree to show the phylogenetic relationship of the most abundant 50 OTUs with affiliated canonical nifH clusters (Chien and Zinder, 1996) indicated by colored branches. Bootstrap value greater than 50% is shown (calculated 1,000 times).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4612719&req=5

Figure 4: A NJ tree to show the phylogenetic relationship of the most abundant 50 OTUs with affiliated canonical nifH clusters (Chien and Zinder, 1996) indicated by colored branches. Bootstrap value greater than 50% is shown (calculated 1,000 times).
Mentions: Phylogenetic trees constructed using NJ and maximum-likelihood methods had congruent tree topology. The NJ phylogenetic tree for the 20 most abundant OTUs demonstrated that 13 of them fell into cluster I, and the rest were in cluster III (Figure 3). Among the cluster I OTUs, seven were affiliated with Marinobacteium lutimaris, Vibrio diazotrophicus, and Pseudomonas stutzeri, which belong to the class of β/γ-Proteobacteria; one was affiliated with Scytonema sp., a cyanobacterial diazotroph; two were affiliated with Azorhizobium doebereinerae and Gluconacetobacter diazotrophicus in the α-Proteobacteria class; and two were closely related to Pelobacter carbinolicus in the δ-Proteobacteria class. Within cluster III, four OTUs grouped with Desulfobotulus alkaliphilus, whereas the remaining three were clustered with Desulfovibrio sp. In addition, a phylogenetic tree based on the 50 most abundant OTUs (Figure 4) indicated that several (i.e., OTU18, 29, 39, and 43) fell into Cluster II, and were affiliated with Azomonas macrocytogenes.

Bottom Line: The metabolic capacities of these diazotrophs indicate the potential for bioremediation and resiliency of the ecosystem to anthropogenic impact.In heavily polluted locations, the diazotrophic community structures were markedly different and the diversity of species was significantly reduced when compared with those in a pristine location.This, together with the increased abundance of Marinobacterium, which is a bioindicator of pollution, suggests that anthropogenic activity has a negative impact on the genetic diversity of diazotrophs in the mangrove rhizosphere.

View Article: PubMed Central - PubMed

Affiliation: Sanya Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences Sanya, China.

ABSTRACT
Diazotrophs in the mangrove rhizosphere play a major role in providing new nitrogen to the mangrove ecosystem and their composition and activity are strongly influenced by anthropogenic activity and ecological conditions. In this study, the diversity of the diazotroph communities in the rhizosphere sediment of five tropical mangrove sites with different levels of pollution along the north and south coastline of Singapore were studied by pyrosequencing of the nifH gene. Bioinformatics analysis revealed that in all the studied locations, the diazotroph communities comprised mainly of members of the diazotrophic cluster I and cluster III. The detected cluster III diazotrophs, which were composed entirely of sulfate-reducing bacteria, were more abundant in the less polluted locations. The metabolic capacities of these diazotrophs indicate the potential for bioremediation and resiliency of the ecosystem to anthropogenic impact. In heavily polluted locations, the diazotrophic community structures were markedly different and the diversity of species was significantly reduced when compared with those in a pristine location. This, together with the increased abundance of Marinobacterium, which is a bioindicator of pollution, suggests that anthropogenic activity has a negative impact on the genetic diversity of diazotrophs in the mangrove rhizosphere.

No MeSH data available.