Project description:The mangrove ecosystem harbors a complex microbial community that plays crucial role in biogeochemical cycles. In this study, we analyzed mangrove sediments from India using de novo whole metagenome next generation sequencing (NGS) and compared their taxonomic and functional community structures to mangrove metagenomics samples from Brazil and Saudi Arabia. The most abundant phyla in the mangroves of all three countries was Proteobacteria, followed by Firmicutes and Bacteroidetes. A total of 1,942 genes were found to be common across all the mangrove sediments from each of the three countries. The mangrove resistome consistently showed high resistance to fluoroquinolone and acriflavine. A comparative study of the mangrove resistome with other ecosystems shows a higher frequency of heavy metal resistance in mangrove and terrestrial samples. Ocean samples had a higher abundance of drug resistance genes with fluoroquinolone and methicillin resistance genes being as high as 28.178%?±?3.619 and 10.776%?±?1.823. Genes involved in cobalt-zinc-cadmium resistance were higher in the mangrove (23.495%?±?4.701) and terrestrial (27.479%?±?4.605) ecosystems. Our comparative analysis of samples collected from a variety of habitats shows that genes involved in resistance to both heavy metals and antibiotics are ubiquitous, irrespective of the ecosystem examined.
Project description:This study reports the analyses of the rhizospheric microbiome of the terrestrial mangrove fern Acrostichum aureum Linn. from the Indian Sunderbans. Samples were collected using standard protocols and 16S rRNA gene V3-V4 region amplicon sequencing was performed to identify the microbial communities prevalent in the rhizosphere. A total of 1,931,252 quality checked reads were assembled into 204,818 contigs and were analysed using QIIME to reveal the abundance of Proteobacteria, Acidobacteria and Planctomycetes. The data is available at the NCBI - Sequence Read Archive with accession number: SRX2660456. This is the first report of the rhizospheric microbiome belonging to a fern species.
Project description:Diaphorina citri (Hemiptera: Psyllidae), the Asian citrus psyllid, is the insect vector of Ca. Liberibacter asiaticus, the causal agent of citrus greening disease. Sequencing of the D. citri metagenome has been initiated to gain better understanding of the biology of this organism and the potential roles of its bacterial endosymbionts. To corroborate candidate endosymbionts previously identified by rDNA amplification, raw reads from the D. citri metagenome sequence were mapped to reference genome sequences. Results of the read mapping provided the most support for Wolbachia and an enteric bacterium most similar to Salmonella. Wolbachia-derived reads were extracted using the complete genome sequences for four Wolbachia strains. Reads were assembled into a draft genome sequence, and the annotation assessed for the presence of features potentially involved in host interaction. Genome alignment with the complete sequences reveals membership of Wolbachia wDi in supergroup B, further supported by phylogenetic analysis of FtsZ. FtsZ and Wsp phylogenies additionally indicate that the Wolbachia strain in the Florida D. citri isolate falls into a sub-clade of supergroup B, distinct from Wolbachia present in Chinese D. citri isolates, supporting the hypothesis that the D. citri introduced into Florida did not originate from China.
Project description:The global knowledge of microbial diversity and function in Sundarbans ecosystem is still scarce, despite global advancement in understanding the microbial diversity. In the present study, we have analyzed the diversity and distribution of bacteria in the tropical mangrove sediments of Sundarbans using 16S rRNA gene amplicon sequencing. Metagenome is comprised of 1,53,926 sequences with 108.8 Mbp data and with 55 ± 2% G + C content. Metagenome sequence data are available at NCBI under the Bioproject database with accession no. PRJNA245459. Bacterial community metagenome sequences were analyzed by MG-RAST software representing the presence of 56,547 species belonging to 44 different phyla. The taxonomic analysis revealed the dominance of phyla Proteobacteria within our dataset. Further taxonomic analysis revealed abundance of Bacteroidetes, Acidobactreia, Firmicutes, Actinobacteria, Nitrospirae, Cyanobacteria, Planctomycetes and Fusobacteria group as the predominant bacterial assemblages in this largely pristine mangrove habitat. The distribution of different community datasets obtained from four sediment samples originated from one sampling station at two different depths providing better understanding of the sediment bacterial diversity and its relationship to the ecosystem dynamics of this pristine mangrove sediment of Dhulibhashani in, Sundarbans.
Project description:<h4>Background</h4>The human microbiota are complex systems with important roles in our physiological activities and diseases. Sequencing the microbial genomes in the microbiota can help in our interpretation of their activities. The vast majority of the microbes in the microbiota cannot be isolated for individual sequencing. Current metagenomics practices use short-read sequencing to simultaneously sequence a mixture of microbial genomes. However, these results are in ambiguity during genome assembly, leading to unsatisfactory microbial genome completeness and contig continuity. Linked-read sequencing is able to remove some of these ambiguities by attaching the same barcode to the reads from a long DNA fragment (10-100?kb), thus improving metagenome assembly. However, it is not clear how the choices for several parameters in the use of linked-read sequencing affect the assembly quality.<h4>Results</h4>We first examined the effects of read depth (C) on metagenome assembly from linked-reads in simulated data and a mock community. The results showed that C positively correlated with the length of assembled sequences but had little effect on their qualities. The latter observation was corroborated by tests using real data from the human gut microbiome, where C demonstrated minor impact on the sequence quality as well as on the proportion of bins annotated as draft genomes. On the other hand, metagenome assembly quality was susceptible to read depth per fragment (C<sub>R</sub>) and DNA fragment physical depth (C<sub>F</sub>). For the same C, deeper C<sub>R</sub> resulted in more draft genomes while deeper C<sub>F</sub> improved the quality of the draft genomes. We also found that average fragment length (?<sub>FL</sub>) had marginal effect on assemblies, while fragments per partition (N<sub>F/P</sub>) impacted the off-target reads involved in local assembly, namely, lower N<sub>F/P</sub> values would lead to better assemblies by reducing the ambiguities of the off-target reads. In general, the use of linked-reads improved the assembly for contig N50 when compared to Illumina short-reads, but not when compared to PacBio CCS (circular consensus sequencing) long-reads.<h4>Conclusions</h4>We investigated the influence of linked-read sequencing parameters on metagenome assembly comprehensively. While the quality of genome assembly from linked-reads cannot rival that from PacBio CCS long-reads, the case for using linked-read sequencing remains persuasive due to its low cost and high base-quality. Our study revealed that the probable best practice in using linked-reads for metagenome assembly was to merge the linked-reads from multiple libraries, where each had sufficient C<sub>R</sub> but a smaller amount of input DNA. Video Abstract.