RESUMO

A functional screening of 1152 clones from a plasmid library constructed with DNA extracted from Brazilian mangrove sediments revealed 3 positive clones for ester-hydrolyzing enzymes, or about one lipolytic gene per 1.2 Mb DNA, which corroborates the idea that oil-contaminated mangroves are a good source of novel microbial lipases/esterases. The partial sequence of the clone LipG7 (1179 bp) showed 30.2% of predicted structure identity with a known esterase, confirming LipG7 as a new member of family VIII esterases. LigG7 shared 80% sequence identity with 1,4-butanediol diacrylate esterase from the Gammaprotebacteria Porticoccus hydrocarbonoclasticus, suggesting it belongs to the Porticoccaceae family. LipG7 was heterologously expressed in Escherichia coli Rosetta-Gami DE3; the purified recombinant enzyme exhibited a predicted molecular weight of 45.2 kDa and exceptional activity towards 4-nitrophenyl butyrate, compared with other recombinant esterases, highlighting its enormous potential for biological applications.

Assuntos

Carboxilesterase/genética , Carboxilesterase/isolamento & purificação , Gammaproteobacteria/genética , Sequência de Aminoácidos/genética , Bactérias/genética , Bactérias/metabolismo , Sequência de Bases/genética , Brasil , Butiratos/metabolismo , Carboxilesterase/metabolismo , Esterases/metabolismo , Gammaproteobacteria/metabolismo , Expressão Gênica/genética , Biblioteca Gênica , Metagenoma/genética , Filogenia , Plasmídeos/genética , Alinhamento de Sequência/métodos , Análise de Sequência de DNA/métodos , Especificidade por Substrato/genética , Áreas Alagadas

RESUMO

We investigated the relationship among environmental variables, composition, and structure of bacterial communities in different habitats in a mangrove located nearby to an oil exploitation area, aiming to retrieve the natural pattern of bacterial communities in this ecosystem. The T-RFLP analysis showed a high diversity of bacterial populations and an increase in the bacterial richness from habitats closer to the sea and without vegetation (S1) to habitats covered by Avicennia schaueriana (S2) and Rhizophora mangle (S3). Environmental variables in S1 and S2 were more similar than in S3; however, when comparing the bacterial compositions, S2 and S3 shared more OTUs between them, suggesting that the presence of vegetation is an important factor in shaping these bacterial communities. In silico analyses of the fragments revealed a high diversity of the class Gammaproteobacteria in the 3 sites, although in general they presented quite different bacterial composition, which is probably shaped by the specificities of each habitat. This study shows that microhabitats inside of a mangrove ecosystem harbor diverse and distinct microbiota, reinforcing the need to conserve these ecosystems as a whole.