RESUMO
Mangroves are located in coastal wetlands and are susceptible to the consequences of oil spills, what may threaten the diversity of microorganisms responsible for the nutrient cycling and the consequent ecosystem functioning. Previous reports show that high concentration of oil favors the incidence of epoxide hydrolases and haloalkane dehalogenases in mangroves. This finding has guided the goals of this study in an attempt to broaden the analysis to other hydrolases and thereby verify whether oil contamination interferes with the prevalence of particular hydrolases and their assigned microorganisms. For this, an in-depth survey of the taxonomic and functional microbial diversity recovered in a fosmid library (Library_Oil Mgv) constructed from oil-impacted Brazilian mangrove sediment was carried out. Fosmid DNA of the whole library was extracted and submitted to Illumina HiSeq sequencing. The resulting Library Oil_Mgv dataset was further compared with those obtained by direct sequencing of environmental DNA from Brazilian mangroves (from distinct regions and affected by distinct sources of contamination), focusing on hydrolases with potential use in biotechnological processes. The most abundant hydrolases found were proteases, esterases and amylases, with similar occurrence profile in all datasets. The main microbial groups harboring such hydrolase-encoding genes were distinct in each mangrove, and in the fosmid library these enzymes were mainly assigned to Chloroflexaceae (for amylases), Planctomycetaceae (for esterases) and Bradyrhizobiaceae (for proteases). Assembly and analysis of Library_Oil Mgv reads revealed three potentially novel enzymes, one epoxide hydrolase, one xylanase and one amylase, to be further investigated via heterologous expression assays.
Assuntos
Bactérias/classificação , Sedimentos Geológicos/microbiologia , Hidrolases/genética , Metagenômica/métodos , Bactérias/enzimologia , Bactérias/genética , Bactérias/isolamento & purificação , Proteínas de Bactérias/genética , Biodiversidade , Brasil , Biblioteca Genômica , Sequenciamento de Nucleotídeos em Larga Escala , Poluição por Petróleo/efeitos adversos , Filogenia , Análise de Sequência de DNA , Microbiologia do Solo , Áreas AlagadasRESUMO
The mangrove ecosystem is an unexplored source for biotechnological applications. In this unique environment, endemic bacteria have the ability to thrive in the harsh environmental conditions (salinity and anaerobiosis), and act in the degradation of organic matter, promoting nutrient cycles. Thus, this study aimed to assess the cellulolytic activities of bacterial groups present in the sediment from a mangrove located in Ilha do Cardoso (SP, Brazil). To optimize the isolation of cellulolytic bacteria, enrichments in two types of culture media (tryptone broth and minimum salt medium), both supplemented with 5% NaCl and 1% of cellulose, were performed. Tests conducted with the obtained colonies showed a higher occurrence of endoglycolytic activity (33 isolates) than exoglycolytic (19 isolates), and the degradation activity was shown to be modulated by the presence of NaCl. The isolated bacteria were clustered by BOX-PCR and further classified on the basis of partial 16S rRNA sequences as Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, Firmicutes or Bacteroidetes. Therefore, this study highlights the importance of studies focusing on the endemic species found in mangroves to exploit them as novel biotechnological tools for the degradation of cellulose.
Assuntos
Bactérias/enzimologia , Sedimentos Geológicos/microbiologia , Glicosídeo Hidrolases/metabolismo , Áreas Alagadas , Brasil , Bactérias/isolamento & purificação , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Glicosídeo Hidrolases/genética , Dados de Sequência Molecular , Filogenia , /genética , Análise de Sequência de DNA , Cloreto de Sódio/metabolismoRESUMO
The mangrove ecosystem is an unexplored source for biotechnological applications. In this unique environment, endemic bacteria have the ability to thrive in the harsh environmental conditions (salinity and anaerobiosis), and act in the degradation of organic matter, promoting nutrient cycles. Thus, this study aimed to assess the cellulolytic activities of bacterial groups present in the sediment from a mangrove located in Ilha do Cardoso (SP, Brazil). To optimize the isolation of cellulolytic bacteria, enrichments in two types of culture media (tryptone broth and minimum salt medium), both supplemented with 5% NaCl and 1% of cellulose, were performed. Tests conducted with the obtained colonies showed a higher occurrence of endoglycolytic activity (33 isolates) than exoglycolytic (19 isolates), and the degradation activity was shown to be modulated by the presence of NaCl. The isolated bacteria were clustered by BOX-PCR and further classified on the basis of partial 16S rRNA sequences as Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, Firmicutes or Bacteroidetes. Therefore, this study highlights the importance of studies focusing on the endemic species found in mangroves to exploit them as novel biotechnological tools for the degradation of cellulose.
