Biology subjects

Patin, N. V.

Publications and source records attributed to Patin, N. V..

3 recordsLinked to original sources

bioRxiv2021

Tourmaline: a workflow for rapid and reproducible amplicon sequence analysis using QIIME 2 and Snakemake

BackgroundAmplicon sequencing (metabarcoding) is a common method to survey diversity of environmental communities whereby a single genetic locus is amplified and sequenced from the DNA of whole or partial organisms, organismal traces (e.g., skin, mucus, feces), or microbes in an environmental sample. Several software packages exist for analyzing amplicon data, among which QIIME 2 has emerged as a popular option because of its broad functionality, plugin architecture, provenance tracking, and interactive visualizations. However, each new analysis requires the user to keep track of input and output file names, parameters, and commands; this lack of automation and standardization is inefficient and creates barriers to meta-analysis and sharing of results. FindingsWe developed Tourmaline, a Python-based workflow that implements QIIME 2 and is built using the Snakemake workflow management system. Starting from a configuration file that defines parameters and input files--a reference database, a sample metadata file, and a manifest or archive of FASTQ sequences--it uses QIIME 2 to run either the DADA2 or Deblur denoising algorithm, assigns taxonomy to the resulting representative sequences, performs analyses of taxonomic, alpha, and beta diversity, and generates an HTML report summarizing and linking to the output files. Features include support for multiple cores, automatic determination of trimming parameters using quality scores, representative sequence filtering (taxonomy, length, abundance, prevalence, or ID), support for multiple taxonomic classification and sequence alignment methods, outlier detection, and automated initialization of a new analysis using previous settings. The workflow runs natively on Linux and macOS or via a Docker container. We ran Tourmaline on a 16S rRNA amplicon dataset from Lake Erie surface water, showing its utility for parameter optimization and the ability to easily view interactive visualizations through the HTML report, QIIME 2 viewer, and R- and Python-based Jupyter notebooks. ConclusionsAutomated workflows like Tourmaline enable rapid analysis of environmental and biomedical amplicon data, decreasing the time from data generation to actionable results. Tourmaline is available for download at github.com/aomlomics/tourmaline.

bioinformatics↗

bioRxiv2021

Microbial diversity in tropical marine sediments assessed using culture-dependent and culture-independent techniques

The microbial communities associated with marine sediments are critical for ecosystem function yet remain poorly characterized. While culture-independent (CI) approaches capture the broadest perspective on community composition, culture-dependent (CD) methods can capture low abundance taxa that are missed using CI approaches. The aim of this study was to assess microbial diversity in tropical marine sediments collected from five shallow water sites in Belize using both CD and CI approaches. CD methods captured approximately 3% of the >800 genera detected across the five sites. Additionally, 39 genera were only detected using CD approaches revealing rare taxa that were missed with the CI approach. Significantly different communities were detected across sites, with rare taxa playing an important role in the delineation of sediment communities. This study provides important baseline data describing shallow water sediment microbial communities and evidence that standard cultivation techniques may be more effective than previously recognized. Originality-Significance StatementMarine sediments host some of the most diverse microbial communities on the planet. While these communities are critical for global nutrient cycling, the oceanic food web, and the maintenance of ecosystem dynamics, they remain poorly studied. Studies that have assessed sediment communities typically use culture-independent approaches, which have known biases and can miss ecologically important taxa. Here we describe microbial diversity in marine sediments using both culture-dependent and culture-independent approaches. Our culturing approach, sequencing communities as opposed to individual colonies, revealed an additional 39 genera that were not detected with culture-independent methods. Additionally, we cultured numerous, as-yet undescribed species, suggesting that traditional culturing practices can be more efficient than commonly thought. Moreover, our results indicate rare taxa play an important role in distinguishing microbial communities at different sites, thus highlighting the importance of deep sequencing and incorporating culture-dependent approaches for diversity assessments.

microbiology↗

bioRxiv2020

Gulf of Mexico blue hole harbors high levels of novel microbial lineages

Exploration of oxygen-depleted marine environments has consistently revealed novel microbial taxa and metabolic capabilities that expand our understanding of microbial evolution and ecology. Marine blue holes are shallow karst formations characterized by low oxygen and high organic matter content. They are logistically challenging to sample, and thus our understanding of their biogeochemistry and microbial ecology is limited. We present a metagenomic characterization of Amberjack Hole on the Florida continental shelf (Gulf of Mexico). Dissolved oxygen became depleted at the holes rim (32 m water depth), remained low but detectable in an intermediate hypoxic zone (40-75 m), and then increased to a secondary peak before falling below detection in the bottom layer (80-110 m), concomitant with increases in nutrients, dissolved iron, and a series of sequentially more reduced sulfur species. Microbial communities in the bottom layer contained heretofore undocumented levels of the recently discovered phylum Woesearchaeota (up to 58% of the community), along with lineages in the bacterial Candidate Phyla Radiation (CPR). Thirty-one high-quality metagenome-assembled genomes (MAGs) showed extensive biochemical capabilities for sulfur and nitrogen cycling, as well as for resisting and respiring arsenic. One uncharacterized gene associated with a CPR lineage differentiated hypoxic from anoxic zone communities. Overall, microbial communities and geochemical profiles were stable across two sampling dates in the spring and fall of 2019. The blue hole habitat is a natural marine laboratory that provides opportunities for sampling taxa with under-characterized but potentially important roles in redox-stratified microbial processes.

microbiology↗