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3 resultados encontrados para: AUTOR: De los Santos Briones, César
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Metagenomics is a culture-independent technology that allows access to novel and potentially useful genetic resources from a wide range of unknown microorganisms. In this study, a fosmid metagenomic library of tropical underground water was constructed, and clones were functionally screened for extracellular proteolytic activity. One of the positive clones, containing a 41,614-bp insert, had two genes with 60% and 68% identity respectively with a peptidase S8 of Chitinimonas koreensis. When these genes were individually sub-cloned, in both cases their sub-clones showed proteolytic phenotype, confirming that they both encode functional proteases. These genes -named PrAY5 and PrAY6- are next to each other. They are similar in size (1845bp and 1824bp respectively) and share 66.5% identity. An extensive in silico characterization showed that their ORFs encode complex zymogens having a signal peptide at their 5'end, followed by a pro-peptide, a catalytic region, and a PPC domain at their 3' end. Their translated sequences were classified as peptidases S8A by sequence comparisons against the non-redundant database and corroborated by Pfam and MEROPS. Phylogenetic analysis of the catalytic region showed that they encode novel proteases that clustered with the sub-family S8_13, which according to the CDD database at NCBI, is an uncharacterized subfamily. They clustered in a clade different from the other three proteases S8 found so far by functional metagenomics, and also different from proteases S8 found in sequenced environmental samples, thereby expanding the range of potentially useful proteases that have been identified by metagenomics. I-TASSER modeling corroborated that they may be subtilases, thus possibly they participate in the hydrolysis of proteins with broad specificity for peptide bonds, and have a preference for a large uncharged residue in P1.


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Although detergents are major environmental pollutants for soil and water, their impact in bacterial community structures has not been addressed. We compared the bacterial community structures as well as several edaphic parameters between severely detergent-contaminated soils and noncontaminated soils in the State of Yucatán, México. The results indicate that sodium concentration, salinity, and electrical conductivity were significantly higher in contaminated samples, and that this correlates with different bacterial community structures. The most important differences were that (i) samples with detergent presented a lower species richness; (ii) Proteobacteria was the most abundant phylum in soils with detergent, while Actinobacteria and Acidobacteria were the most abundant phyla in soils without detergent; (iii) Rhodomicrobium, Hydrogenophaga, and Thiobacillus were the most abundant genera in soils with detergent, while Acidobacteria dominated soils without detergent. With the continual increase of the human population without access to a proper disposal of waste waters, these modifications may contribute to bringing about changes in the ecological parameters of the region.


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Resumen en inglés

Marine invertebrate-associated microbial communities are interesting examples of complex symbiotic systems and are a potential source of biotechnological products. Results: In this work, pyrosequencing-based assessment from bacterial community structures of sediments, two sponges, and one zoanthid collected in the Mexican Caribbean was performed. The results suggest that the bacterial diversity at the species level is higher in the sediments than in the animal samples. Analysis of bacterial communities’ structure showed that about two thirds of the bacterial diversity in all the samples belongs to the phyla Acidobacteria and Proteobacteria. The genus Acidobacterium appears to dominate the bacterial community in all the samples, reaching almost 80% in the sponge Hyrtios. Conclusions: Our evidence suggests that the sympatric location of these benthonic species may lead to common bacterial structure features among their bacterial communities. The results may serve as a first insight to formulate hypotheses that lead to more extensive studies of sessile marine organisms’ microbiomes from the Mexican Caribbean.