RESUMEN
Thousands of people living in semi-arid regions face problems of drought and loss of water quality. In addition, high incidence of acute diarrheal diseases related to water consumption has been responsible for a high number of deaths and high economic costs for human health. Many of the diseases can be caused by the presence of enterobacteria in reservoirs that serve for multiple purposes. This study aimed to confirm the presence of potentially harmful bacteria, which was highlighted in other articles, and to reveal non-identified genera by culture-dependent methods and pyrosequencing. Twenty-three genera of the Enterobacteriaceae family were detected, with emphasis on Escherichia genus and confirmation of the presence of species such as Salmonella enterica and Enterobacter cloacae. The abundance of heterotrophic prokaryotes and the physical and chemical data show an expected average for this type of environment due to the numbers historically presented in previous articles. The unprecedented detection of the presence of some potentially pathogenic species can alert and raise awareness of the populations that use stored water in the semi-arid regions. Consequently, as a result of the peculiar characteristics of reservoirs under this climate influence, there is a cosmopolitanism of enterobacteria that may be related to the alarming numbers of infections from Waterborne Diseases.
Asunto(s)
Enterobacteriaceae/química , Contaminación del Agua/análisis , Contaminación del Agua/legislación & jurisprudencia , Agua/análisisRESUMEN
The occurrence of bacteria with a reduced genome, such as that found in Mycoplasmas, raises the question as to which genes should be enough to guarantee the genomic stability indispensable for the maintenance of life. The aim of this work was to compare nine Mycoplasma genomes in regard to DNA repair genes. An in silico analysis was done using six Mycoplasma species, whose genomes are accessible at GenBank, and M. synoviae, and two strains of M. hyopneumoniae, whose genomes were recently sequenced by The Brazilian National Genome Project Consortium and Southern Genome Investigation Program (Brazil) respectively. Considering this reduced genome model, our comparative analysis suggests that the DNA integrity necessary for life can be primarily maintained by nucleotide excision repair (NER), which is the only complete repair pathway. Furthermore, some enzymes involved with base excision repair (BER) and recombination are also present and can complement the NER activity. The absence of RecR and RecO-like ORFs was observed only in M. genitalium and M. pneumoniae, which can be involved with the conservation of gene order observed between these two species. We also obtained phylogenetic evidence for the recent acquisition of the ogt gene in M. pulmonis and M. penetrans by a lateral transference event. In general, the presence or nonexistence of repair genes is shared by all species analyzed, suggesting that the loss of the majority of repair genes was an ancestral event, which occurred before the divergence of the Mycoplasma species.
Asunto(s)
Reparación del ADN , Genoma Bacteriano , Mycoplasma/genética , Reparación del ADN/genética , Genes Bacterianos , Mycoplasma/química , Mycoplasma/clasificación , Filogenia , Recombinación GenéticaRESUMEN
Chromobacterium violaceum is a Gram-negative beta-proteobacterium that inhabits a variety of ecosystems in tropical and subtropical regions, including the water and banks of the Negro River in the Brazilian Amazon. This bacterium has been the subject of extensive study over the last three decades, due to its biotechnological properties, including the characteristic violacein pigment, which has antimicrobial and anti-tumoral activities. C. violaceum promotes the solubilization of gold in a mercury-free process, and has been used in the synthesis of homopolyesters suitable for the production of biodegradable polymers. The complete genome sequence of this organism has been completed by the Brazilian National Genome Project Consortium. The aim of our group was to study the DNA repair genes in this organism, due to their importance in the maintenance of genomic integrity. We identified DNA repair genes involved in different pathways in C. violaceum through a similarity search against known sequences deposited in databases. The phylogenetic analyses were done using programs of the PHILYP package. This analysis revealed various metabolic pathways, including photoreactivation, base excision repair, nucleotide excision repair, mismatch repair, recombinational repair, and the SOS system. The similarity between the C. violaceum sequences and those of Neisserie miningitidis and Ralstonia solanacearum was greater than that between the C. violaceum and Escherichia coli sequences. The peculiarities found in the C. violaceum genome were the absence of LexA, some horizontal transfer events and a large number of repair genes involved with alkyl and oxidative DNA damage.