RESUMO
The microorganisms living on the phyllosphere (the aerial part of the plants) are in contact with the lignocellulosic plant cell wall and might have a lignocellulolytic potential. We isolated a Saccharibacillus strain (Saccharibacillus WB17) from wheat bran phyllosphere and its cellulolytic and hemicellulolytic potential was investigated during growth onto wheat bran. Five other type strains from that genus selected from databases were also cultivated onto wheat bran and glucose. Studying the chemical composition of wheat bran residues by FTIR after growth of the six strains showed an important attack of the stretching C-O vibrations assigned to polysaccharides for all the strains, whereas the C = O bond/esterified carboxyl groups were not impacted. The genomic content of the strains showed that they harbored several CAZymes (comprised between 196 and 276) and possessed four of the fifth modules reflecting the presence of a high diversity of enzymes families. Xylanase and amylase activities were the most active enzymes with values reaching more than 4746 ± 1400 mIU/mg protein for the xylanase activity in case of Saccharibacillus deserti KCTC 33693 T and 452 ± 110 mIU/mg protein for the amylase activity of Saccharibacillus WB17. The total enzymatic activities obtained was not correlated to the total abundance of CAZyme along that genus. The Saccharibacillus strains harbor also some promising proteins in the GH30 and GH109 modules with potential arabinofuranosidase and oxidoreductase activities. Overall, the genus Saccharibacillus and more specifically the Saccharibacillus WB17 strain represent biological tools of interest for further biotechnological applications.
Assuntos
Bacillales , Fibras na Dieta , Polissacarídeos Bacterianos , Amilases , Fibras na Dieta/microbiologia , Genômica , Filogenia , Bacillales/classificação , Bacillales/isolamento & purificação , Polissacarídeos Bacterianos/químicaRESUMO
Microorganisms have developed copper-resistance mechanisms in order to survive in contaminated environments. The abundance of the copper-resistance genes cusA and copA, encoding respectively for a Resistance Cell Nodulation protein and for a P-type ATP-ase pump, was assessed in copper and non-copper-impacted Chilean marine sediment cores by the use of molecular tools. We demonstrated that number of copA and cusA genes per bacterial cell was higher in the contaminated sediment, and that copA gene was more abundant than cusA gene in the impacted sediment. The molecular phylogeny of the two copper-resistance genes was studied and reveals an impact of copper on the genetic composition of copA and cusA genes.
Assuntos
Proteínas de Bactérias/genética , Cobre/toxicidade , Genes Bacterianos , Variação Genética , Sedimentos Geológicos/microbiologia , Proteínas de Membrana Transportadoras/genética , Poluentes Químicos da Água/toxicidade , Adaptação Fisiológica , Proteínas de Bactérias/análise , Sequência de Bases , Chile , Cobre/análise , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Proteínas de Membrana Transportadoras/análise , Dados de Sequência Molecular , Poluentes Químicos da Água/análiseRESUMO
Cultivation and molecular-based approaches were used to study microbial diversity in two Chilean marine sediments contaminated with high (835 ppm) and very high concentrations of copper (1,533 ppm). The diversity of cultivable bacteria resistant to copper was studied at oxic and anoxic conditions, focusing on sulfate-, thiosulfate-, and iron-reducing bacteria. For both sediments, the cultivable bacteria isolated at oxic conditions were mostly affiliated to the genus Bacillus, while at anoxic conditions the majority of the cultivable bacteria found were closely related to members of the genera Desulfovibrio, Sphingomonas, and Virgibacillus. Copper resistance was between 100 and 400 ppm, with the exception of a strain affiliated to members of the genus Desulfuromonas, which was resistant up to 1,000 ppm of copper. In parallel, cloning and sequencing of 16S rRNA was performed to study the total bacterial diversity in the sediments. A weak correlation was observed between the isolated strains and the 16S rRNA operational taxonomic units detected. The presence of copper resistance genes (copA, cusA, and pcoA) was tested for all the strains isolated; only copA was detected in a few isolates, suggesting that other copper resistance mechanisms could be used by the bacteria in those highly copper-contaminated sediments.
Assuntos
Bactérias/isolamento & purificação , Biodiversidade , Cobre/análise , Sedimentos Geológicos/microbiologia , Poluentes da Água/análise , Bactérias/classificação , Bactérias/genética , Chile , Biblioteca Gênica , Genes Bacterianos , Sedimentos Geológicos/química , Filogenia , RNA Ribossômico 16S/genética , Água do Mar/química , Água do Mar/microbiologia , Bactérias Redutoras de Enxofre/classificação , Bactérias Redutoras de Enxofre/genética , Bactérias Redutoras de Enxofre/isolamento & purificação , Microbiologia da ÁguaRESUMO
We studied the abundance and diversity of the sulfate-reducing prokaryotes (SRPs) in two 30-cm marine chilean sediment cores, one with a long-term exposure to copper-mining residues, the other being a non-exposed reference sediment. The abundance of SRPs was quantified by qPCR of the dissimilatory sulfite reductase gene ß-subunit (dsrB) and showed that SRPs are sensitive to high copper concentrations, as the mean number of SRPs all along the contaminated sediment was two orders of magnitude lower than in the reference sediment. SRP diversity was analyzed by using the dsrB-sequences-based PCR-DGGE method and constructing gene libraries for dsrB-sequences. Surprisingly, the diversity was comparable in both sediments, with dsrB sequences belonging to Desulfobacteraceae, Syntrophobacteraceae, and Desulfobulbaceae, SRP families previously described in marine sediments, and to a deep branching dsrAB lineage. The hypothesis of the presence of horizontal transfer of copper resistance genes in the microbial population of the polluted sediment is discussed.