Biology subjects

Sloan, W.

Publications and source records attributed to Sloan, W..

5 recordsLinked to original sources

bioRxiv2026

Activity-resolved microbial community profiling using rpoB gene and transcript sequencing

Determining which members of a microbial community are metabolically active remains a central challenge in microbial ecology. Although the 16S rRNA gene is the dominant marker for bacterial community profiling, it cannot reliably distinguish active cells from dormant or dead populations. As a result, complementary phylogenetic markers whose transcript abundance more closely reflects cellular activity are needed. Here, we systematically evaluated 80 Bacterial protein-coding marker genes and identified rpoB, encoding the beta subunit of bacterial RNA polymerase, as the optimal candidate. We designed a new primer pair (1528F 2041R) from a curated database of 305,274 unique rpoB sequences and validated it for quantitative PCR and amplicon sequencing of DNA and RNA templates. The rpoB qPCR assay achieved a limit of quantification two orders of magnitude lower than the benchmark 16S rRNA assay, for which a limit of detection could not be determined because of no-template-control amplification. In soil and sediment communities, rpoB recovered community composition comparable to 16S rRNA while providing a quantitative activity signal: rpoB cDNA:DNA ratios correlated significantly with taxon-level transcript abundance (R squared between 0.22 and 0.29, p < 0.001), whereas 16S rRNA ratios did not (p > 0.5). In a biological activated carbon biofilter experiment, rpoB transcript abundance tracked the decline in dissolved organic carbon removal rates across a 72 hour time series (correlation coefficients between 0.84 and 0.99), whereas 16S rRNA transcripts were uninformative (correlation coefficients between -0.4 and 0.98). These results establish rpoB as a quantitatively robust, activity-responsive complement to 16S rRNA for linking community composition to ecosystem processes.

microbiology↗

bioRxiv2024

The probability and duration of immigration in microbial communities

Immigration is a fundamental feature of microbial communities. We propose a method to determine the probability (Pi) that a number of immigrants (i) can attain an abundance N using the ratio of the probabilities of death q and division or "birth" p and the gamblers ruin equation: Pi= (1-(q/p)i/(1-(q/p)N). We estimate the probability of successful bioaugmentation or transplantation, the fate of a mutation infection and extinction. For example, an inoculum of 108 bacteria with a q/p of 1.00000001 has a 10-43 chance of attaining an abundance of 1010. The immigration parameter used in neutral models, m is 1/(1-q/p). We calculated the long-term average value of m and q/p in a wastewater treatment plant. The value of m varies by >5 orders of magnitude, with a curious bimodal distribution. However, all the values of q/p are very close to, but greater than, 1. We expect the long-term average value of q/p to be [~]1 in all stable microbial communities. In the absence of migration, bacterial populations with a q/p [≥]1 will go extinct with probability 1. The link between q/p and infectious dose is known and we demonstrate that, in principle, the gamblers ruin equation can estimate the infectious dose in naturally occurring infections, using Vibrio cholerae "carriers" to illustrate the point. We use the ratio q/p to estimate the time (measured in events or solar time) for a given change in abundance to happen. When q/p=1, extinction in even a small microbial population will take thousands of years.

microbiology↗

bioRxiv2021

Deploying an in vitro gut model to assay the impact of a mannan-oligosaccharide prebiotic, Bio-Mos(R) on the Atlantic salmon (Salmo salar) gut microbiome.

Mannose-oligosaccharide (MOS) pre-biotics are widely deployed in animal agriculture as immunomodulators as well as to enhance growth and gut health. Their mode of action is thought to be mediated through their impact on host microbial communities and the associated metabolism. Bio-Mos is a commercially available pre-biotic currently used in the agri-feed industry. To assess Bio-Mos for potential use as a prebiotic growth promotor in salmonid aquaculture, we have modified an established Atlantic salmon in vitro gut model, SalmoSim, to evaluate its impact on the host microbial communities. Inoculated from biological triplicates of adult farmed salmon pyloric caeca compartments, the microbial communities were stabilised in SalmoSim followed by a twenty-day exposure to the prebiotic and in turn followed by an eight day wash out period. Dietary inclusion of MOS resulted in a significant increase in formate (p=0.001), propionate (p=0.037) and isovalerate (p=0.024) levels, correlated with increased abundances of several, principally, anaerobic microbial genera (Fusobacterium, Agarivorans, Pseudoalteromonas). DNA metabarcoding with the 16S rDNA marker confirmed a significant shift in microbial community composition in response to MOS supplementation with observed increase in lactic acid producing Carnobacterium. In conjunction with previous in vivo studies linking enhanced volatile fatty acid production alongside MOS supplementation to host growth and performance, our data suggests that Bio-Mos may be of value in salmonid production. Furthermore, our data highlights the potential role of in vitro gut models to augment in vivo trials of microbiome modulators. ImportanceIn this paper we report the results of the impact of prebiotic (MOS supplementation) on microbial communities within recently developed Atlantic salmon gut microbiome in vitro simulator. Our data suggest that Bio-Mos may be of value in salmonid production as it enhances volatile fatty acid production in the Atlantic salmon gut and correlates with a significant shift in microbial community composition with observed increase in lactic acid producing Carnobacterium. In conjunction with previous in vivo studies linking enhanced volatile fatty acid production alongside MOS supplementation to host growth and performance, our data suggest that Bio-Mos may be of value in salmonid production. Furthermore, our data highlights the potential role of in vitro gut models to augment in vivo trials of microbiome modulators.

bioengineering↗

bioRxiv2020

Circular Economy of Anaerobic Biofilm Microbiomes: A Meta-Analysis Framework for Re-exploration of Amplicon Sequencing Data

Use of high-throughput sequencing is widespread in efforts to understand the microbial communities in natural and engineered systems. Many built ecosystems, in particular those used for engineered wastewater treatment, have harnessed the metabolic capacity of complex microbial communities for the effective removal and recovery of organic pollutants. Recent efforts to better understand and precisely engineer such systems have increasingly used high-throughput sequencing to map the structure and function of wastewater treatment microbiomes. An enormous amount of data is readily available on online repositories such as the National Center for Biotechnology Information Short Read Archive (NCBI SRA). Here, we describe and provide an optimised meta-analysis workflow to utilise this resource to collate heterogenous studies together for anaerobic digestion research. We analysed 16S rRNA gene Illumina Miseq amplicon sequencing data from 31 anaerobic digestion studies (from high-rate digesters), including >1,300 samples. Additionally, we compare several methodological choices: extraction method, v-region, taxonomical database, and the classifier. We demonstrate that collation of data from multiple v-regions can be achieved by using only the taxa for which sequences are available in the reference databases, without losses in diversity trends. This is made possible by focusing on alternative strategies for taxonomic assignments, namely, bayesian lowest common ancestor (BLCA) algorithm which offers increased resolution to the traditional naive bayesian classifier (NBC). While we demonstrate this using an anaerobic digestion wastewater treatment dataset, this methodology can be translated to perform meta-analysis on amplicon sequences in any field. These findings not only provide a roadmap for meta-analysis in any field, but additionally provide an opportunity to reuse extensive data resources to ultimately advance knowledge of wastewater treatment systems. ImportanceIn this study, we have combined sequencing data from 31 individual studies with the purpose of identifying a meta-analysis workflow which can accurately collate data derived from sequencing different v-regions with minimal data loss and more accurate diversity patterns. While we have used Anaerobic Digestion (AD) communities for our proof-of-concept, our workflow (Fig 1) can be translated to any Illumina MiSeq meta-analysis study, in any field. Thereby, we provide the foundation for intensive data mining of existing amplicon sequencing resources. Such data-mining can provide a global perspective on complex microbial communities. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/424166v1_fig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@11fe518org.highwire.dtl.DTLVardef@f9a6eeorg.highwire.dtl.DTLVardef@3e5af0org.highwire.dtl.DTLVardef@1c45734_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1.C_FLOATNO Overview of the meta-analysis workflow to assess the protocols used in the analysis of AD microbiomes. C_FIG Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/424166v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@1392216org.highwire.dtl.DTLVardef@1ecd922org.highwire.dtl.DTLVardef@a35894org.highwire.dtl.DTLVardef@c7fc0_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2020

Unpicking the mysterious symbiosis of mycoplasmas in salmonids

Lacking a peptidoglycan cell wall, mycoplasmas are the smallest self-replicating life forms. Members of this bacterial genus are known to parasitise a wide array of metazoans including vertebrates. Whilst much research has been significant targeted at parasitic mammalian mycoplasmas, very little is known about their role in other vertebrates. In the current study, we aim to explore the biology and evolution of Mycoplasma in salmonids, including cellular niche, genome size structure and gene content. Using Fluorescence in-situ hybridisation (FISH), mycoplasmas were identified in epithelial tissues across the digestive tract (stomach, pyloric caecum and midgut) during the developmental stages (eggs, parr, subadult) of farmed Atlantic salmon (Salmo salar), showing a high abundance in acidic compartments. With high throughput sequencing from subadults farmed Atlantic salmon, we assembled a nearly complete genome (~0.57 MB) via shotgun-metagenomics. The phylogenetic inference from the recovered genome revealed successful taxonomic proximity to Mycoplasma penetrans (~1.36 Mb) from the recovered genome. Although, no significant correlation between genome size and its phylogeny was observed, we recovered functional signatures, especially, riboflavin encoding genes pathway and sugars transporters, suggesting a symbiotic relationship between Mycoplasma and the host. Though 247 strains of Mycoplasma are available in public databases, to the best of our knowledge, this is the first study to demonstrate ecological and functional association between Mycoplasma and Salmo salar which delineates symbiotic reductive evolution and genome erosion primarily and also serves as a proxy for salmonid health in aquaculture processes (cell lines, in vitro gut models).

evolutionary biology↗