RESUMO
Microbial diversity in the sediments of the Kara Sea shelf and the southern Yenisei Bay, differing in pore water mineralization, was studied using massive parallel pyrosequencing according to the 454 (Roche) technology. Members of the same phyla (Cyanobacteria, Verrucomicrobia, Actinobacteria, Proteobacteria, and Bacteroidetes) predominated in bacterial communities of the sediments, while their ratio and taxonomic composition varied within the phyla and depended on pore water mineralization. Increasing salinity gradient was found to coincide with increased share of the γ-Proteobacteria and decreased abundance of α- and ß-Proteo- bacteria, as well as of the phyla Verrucomicrobia, Chloroflexi, Chlorobi, and Acidobacteria. Archaeal diversity was lower, with Thaumarchaeota predominant in the sediments with high and low mineralization, while Crenarchaeota predominated in moderately mineralized sediments. Microbial communities of the Kara Sea shelf and Yenisei Gulf sediments were found to contain the organisms capable of utilization of a broad spectrum of carbon sources, including gaseous and petroleum hydrocarbons.
Assuntos
Archaea/genética , Bactérias/genética , Baías/microbiologia , Biodiversidade , Metagenoma/fisiologia , Microbiologia da ÁguaRESUMO
The existence of the cluster of duplicated sit silicon transporter genes in the chromosome of the diatom Synedra acus subsp. radians was shown for the first time. Earlier, the localization of sit genes in the same chromosome and cluster formation caused by gene duplication was shown only for the marine raphid pennate diatom P. tricornutum. Only non-clustered sit genes were found in the genomes of other diatoms. It is reasonable to assume that sit tandem (sit-td) and sit triplet (sit-tri) genes of S. acus subsp. radians occurred as a result of gene duplication followed by divergence of gene copies.
Assuntos
Proteínas de Algas/genética , Diatomáceas/genética , Proteínas de Membrana Transportadoras/genética , Proteínas de Algas/metabolismo , Diatomáceas/metabolismo , Técnicas de Genotipagem , Proteínas de Membrana Transportadoras/metabolismo , RNA Mensageiro/metabolismo , SilícioRESUMO
High-throughput method of sequencing was applied to determine the complete nucleotide sequence of an araphid pennate diatom Synedra acus subsp. radians from Lake Baikal (East Siberia). The assembled genome has a total length of 98 Mbp, the mean coverage is 33x. Structure-functional annotation of the genome was performed.
Assuntos
Diatomáceas/genética , Núcleo Celular/genética , Genoma , Lagos , Modelos Genéticos , Análise de Sequência , Sibéria , SoftwareRESUMO
Pyrosequencing of amplicons V3-V4 of the 16S rRNA gene of 30 samples from the photic layer across the three basins of Lake Baikal has revealed 44 958 sequences of the domain Bacteria. The most representative phylums among all classified sequences in the samples were Actinobacteria, Bacteroidetes, Verrucomicrobia, Proteobacteria, Acidobacteria, and Cyanobacteria. As much as 38.5% of the total number of sequences has been determined to the level of genus. The taxonomic composition of bacterial communities was similar regardless of some differences in the composition and abundance of spring phytoplankton. Closely related or identical sequences of bacteria inhabiting the epilimnion of other lakes worldwide have been discovered for most sequences. This confirms the similarity of microbial communities in freshwater ecosystems.
Assuntos
Bactérias/classificação , Lagos/microbiologia , Microbiota , Filogenia , Fitoplâncton/microbiologia , Bactérias/genética , Bactérias/isolamento & purificação , Genoma Bacteriano , RNA Ribossômico 16S/genética , Estações do Ano , SibériaAssuntos
Proteínas de Algas/metabolismo , Diatomáceas/metabolismo , Diatomáceas/ultraestrutura , Água Doce , Ácido N-Acetilneuramínico/metabolismo , Proteínas de Algas/química , Sequência de Aminoácidos , Transporte Biológico , Immunoblotting , Microscopia Imunoeletrônica , Dados de Sequência MolecularRESUMO
Sequencing of fragments of genes coding for silicic acid transport (SIT) proteins of diatoms of evolutionary distant classes (centric Chaetoceros muelleri Lemmermann, pennate araphid Synedra acus Kützing, pennate raphid Phaeodactylum tricornutum Bohlin, and pennate with keeled raphe system Cylindrotheca fusiformis Reimann et Lewin), revealed the presence in these proteins of a conservative amino acid motif CMLD. Hydropathy profiles suggest that CMLD occupies a position between two transmembrane strands which do not contain lysine and arginine residues. The two strands are good candidates for the role of the channel along which transport of silicic acid occurs. CMLD is a rare motif. Diatoms are known to need Zn2+ for the incorporation of silica. Presumably, CMLD is the site of Zn2+ binding of SITs. We found that the growth of diatoms is inhibited by a negatively charged alkylating reagent 5-(2-iodoacetamidoethyl)aminonaphtalene-1-sulfonic acid which cannot penetrate through the cell membrane. Cysteine of CMLD can be a target of this reagent. Synthetic peptide NCMLDY forms a complex with Zn2+, as revealed by the fact that the ion considerably reduces the rate of alkylation of the peptide.
