ScLi9- Identify type оf reseаrch in reseаrch аrticles The fоllоwing is an excerpt of the study The Diversity of Sulfide Oxidation and Sulfate Reduction Genes Expressed by the Bacterial Communities of the Cariaco Basin, Venezuela performed by Dr. Maria Jose Rodriguez Mora, professor in our bio department. "The Cariaco Basin, off the coast of Venezuela, is the largest truly marine permanently anoxic basin in the world. [...] [...]a localized sulfur cycle has been postulated for the redoxcline/anoxic zones of the Cariaco Basin [...]: a portion of the carbon fixed by chemoautotrophic microorganisms could be oxidized by sulfate-reducing microorganisms [...] The dissimilatory sulfite reductase, encoded by the dsrAB genes [13], is ubiquitous to all known sulfate-reducing prokaryotes. [...] The diversity of either sqr or dsrA has not yet been studied in the Cariaco Basin. [...] Therefore, in order to build a cloning library for both DNA and mRNA of the sqr and dsrAB genes, a novel sampling devise “Deep-SID” was used and, as a result, the diversity and expression of the two sulfur metabolism genes in the Cariaco Basin redox transition zone were ascertained. [...] Bacterioplankton samples were collected during the Car153 cruise on January 13th 2009 at station A (10.30°N, 64.40°W), [...] situated in the eastern sub-basin, with a depth of 1400 m. [...] The dsrA gene from sulfate-reducing microorganisms was amplified using primers designed to target conserved regions of the gene, based on multiple alignments of cultured and environmental SRB sequences retrieved from GenBank. dsrA1FM [...] To perform phylogenetic analyses of the cloned genes, alignments were built that included sequences of respective genes from several representatives of known cultured bacteria as well as sequences from the closest cultured and non-cultured relatives identified by BLASTn. [...] What type of study is this?