Relationships between bacterial diversity and environmental variables in a tropical marine environment, Rio de Janeiro

Abstract

This study is the first to apply a comparative analysis of environmental chemistry, microbiological parameters and bacterioplankton 16S rRNA clone libraries from different areas of a 50 km transect along a trophic gradient in the tropical Guanabara Bay ecosystem. Higher bacterial diversity was found in the coastal area, whereas lower richness was observed in the more polluted inner bay water. The significance of differences between clone libraries was examined with LIBSHUFF statistics. Paired reciprocal comparisons indicated that each of the libraries differs significantly from the others, and this is in agreement with direct interpretation of the phylogenetic tree. Furthermore, correspondence analyses showed that some taxa are related to specific abiotic, trophic and microbiological parameters in Guanabara Bay estuarine system.

Bacterial Diversity in an Amazonian Mangrove Ecosystem

“…The represented bacterial groups are Proteobacteria, Bacterioidetes, Actinobacteria, Acidobacteria, Firmicutes, Chloroflexi, Spirochaetes, Cyanobacteria, and unclassified bacteria (Figures 5 and 6). These phyla are relatively common in the mangrove systems of southeastern Brazil (Almeida et al, 2009;Gomes et al, 2010;Santos et al, 2011;Silveira et al, 2011) and in other tropical and subtropical countries, such as India, China, Australia, and the United States (Zhang et al, 2008;Zhou et al, 2009), both aquatic and sedimentary communities Vieira et al, 2008).…”

“…Mangroves support the trophic network of coastal systems by tidal nutrients (Nedwell et al, 1994). The species composition of mangrove ecosystems is strongly influenced by physicochemical factors, particularly salinity (Lozupone & Knight, 2007;Vieira et al, 2008;Silveira et al, 2011). Microorganisms play a fundamental role in ecosystem processes, such as the decomposition of organic matter (leaves and trees).…”

Metagenomics in Polluted Aquatic Environments

“…Higher mean nutrient concentrations are found in the inner bay margins, due to sewage runoff and less efficient water renewal. At these same sites significant differences are observed in nutrient concentration between surface and bottom waters while nutrient levels are strongly reduced towards the bay's entrance Vieira et al, 2008).…”

“…The input of organic and inorganic nutrients promotes shifts in the diversity and abundance of microbial species that, in turn, are involved in biogeochemical cycles. Different sites from Guanabara Bay present distinct levels of bacterial production and abundance (Vieira et al, 2008), which can be associated with the impact levels that each of those sites is subjected. To further understand how pollution affects the metabolism of these microbial communities a better understanding of the complex biochemical pathways that undergo in the Bay is still necessary therefore new generation sequencing techniques may play an important role in the process of expanding knowledge in this area in the near future.…”

“…UniFrac can be used for comparing microbial communities through principal component analysis, allowing several datasets to be compared at once, which helps in the detection of distribution patterns in communities of microorganisms and to correlate them with environmental variants (Lozupone & Knight, 2005). Correspondence analysis is a similar approach, which helps to quantify how much of the microbial diversity is explained by environmental variables, with major applications for pollution studies as it determines the extent to which microbial communities are affected by pollutants (Vieira et al, 2008). Concerning microbial community diversity, DOTUR can be used as a tool to assign sequences as operational taxonomic units (OTUs) (Schloss & Handelsman, 2005).…”