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The genome of Desulfovibrio gigas

Complete sequence of model sulfate reducing bacterium now available

Oeiras, 28.07.2014

A group of Portuguese and Brazilian researchers have fully sequenced the genome of Desulfovibrio gigas, a sulfate reducing bacteria and a model organism for one of the most ancient forms of life on Earth. The paper, published in Microbiology Open, is dedicated to the memory of Jean LeGall, who isolated and named the bacteria, and of António Xavier, founder of ITQB and a driver of the initials steps of this sequencing project.

Contrary to common believe sequencing a whole genome without a similar reference genome to serve as template is not something that can be done in a couple of days. In that sense, this is the first genome to be fully sequenced in Portugal and also a good example of the cooperation between public and private sectors. Since 2006, researchers from the Genomics and Stress Lab at ITQB and from the company STAB VIDA joined efforts to reveal the complete genomic context of Dessulfovibrio gigas, which was not yet available despite the accumulated information about this a large size bacterium (thus the name gigas). Later, researchers from Fundação Oswaldo Cruz and Universidade Federal de Minas Gerais in Brazil contributed with the bioinformatics analysis that helped make sense of the whole sequencing information.

Resorting to the latest sequencing techniques and bioinformatics tools, researchers were able to obtain a sequence which covers 160 times the genome of D. gigas. This makes the data extremely reliable. The genome is also fully annotated meaning that researchers have a pretty good idea of what the DNA sequence corresponds to. The genome of D. gigas consists of a circular chromosome of 3,693,899 base pairs, the building blocks of the DNA double helix. This sequence contains approximately 3400 genes and most seem to code for proteins.

By analyzing the sequence data, researchers were able to locate the source of several features of D. gigas physiology. For instance, they were able to identify genes accounting for D. gigas’s large size and found almost 1500 genes unique to this organism, which could explain its special capacity to respond to changing environmental conditions. Phylogenetic analysis and comparison with other Desulfovibrio genomes also reveals that D. gigas is probably one of the most ancient genomes. “We are really excited for having completed this task and I think Professor JeanLeGall and Professor António Xavier would be just as happy” says Claudina Rodrigues-Pousada who coordinated the study. “This is a very important bacterium and the more we know about it, the more we can put that knowledge to our own advantage”. Sulphate reducing bacteria like Desulfovibrio gigas play not only a very important ecological role in the sulfur and carbon cycle but represent also an enormous biotechnological potential for bioremediation, something which will certainly benefit from this work.

Original Article

Microbiology Open DOI: 10.1002/mbo3.184

Genome sequence of the model sulfate reducer Desulfovibrio gigas: a comparative analysis within the Desulfovibrio genus

Fabio O. Morais-Silva, Antonio Mauro Rezende, Catarina Pimentel, Catia I. Santos, Carla Clemente, Ana Varela–Raposo, Daniela M. Resende, Sofia M. da Silva, Luciana Márcia de Oliveira, Marcia Matos, Daniela A. Costa, Orfeu Flores, Jerónimo C. Ruiz and Claudina Rodrigues-Pousada

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