Project description:Members of the bacterial phylum Spirochaetes are primarily studied for their commensal and pathogenic roles in animal hosts. However, Spirochaetes are also frequently detected in anoxic hydrocarbon-contaminated environments but their ecological role in such ecosystems has so far remained unclear. Here we provide a functional trait to these frequently detected organisms with an example of a sulfate-reducing, naphthalene-degrading enrichment culture consisting of a sulfate-reducing deltaproteobacterium Desulfobacterium naphthalenivorans and a novel spirochete Rectinema cohabitans. Using a combination of genomic, proteomic, and physiological studies we show that R. cohabitans grows by fermentation of organic compounds derived from biomass from dead cells (necromass). It recycles the derived electrons in the form of H2 to the sulfate-reducing D. naphthalenivorans, thereby supporting naphthalene degradation and forming a simple microbial loop. We provide metagenomic evidence that equivalent associations between Spirochaetes and hydrocarbon-degrading microorganisms are of general importance in hydrocarbon- and organohalide-contaminated ecosystems. We propose that environmental Spirochaetes form a critical component of a microbial loop central to nutrient cycling in subsurface environments. This emphasizes the importance of necromass and H2-cycling in highly toxic contaminated subsurface habitats such as hydrocarbon-polluted aquifers.
Project description:The opportunistic pathogen Streptococcus gallolyticus is one of the few intestinal bacteria that has been consistently linked to colorectal cancer (CRC). This study aimed to identify S. gallolyticus-induced pathways that could on the long-term add to CRC progression. Transcription profiling of S. gallolyticus-exposed CRC-cells revealed the persistent induction of enzymes involved in biotransformation pathways. Specifically, a diffusible factor of S. gallolyticus (SGF-X) interacts with the aryl hydrocarbon receptor thereby inducing CYP1 enzymes that catalyze the bioactivation of polycyclic aromatic hydrocarbons (PAHs) into toxic intermediates. Importantly, priming CRC-cells with SGF-X containing medium increased the DNA damaging effect of the PAH 3-methylcholanthrene, which was not observed for other intestinal bacteria. In conclusion, this study shows for the first time that bacteria can modulate the biotransformation capacity of CRC-cells that offers a novel theory for a contributing role of S. gallolyticus in the etiology of sporadic CRC. Key words : Colorectal cancer cells, Streptococcus bovis, streptococcus gallolyticus, host-pathogen interactions, Cytochrome P4501A1, DNA-damage, polycyclic aromatic hydrocarbons
Project description:The application of chemical dispersants during marine oil spills can affect the community composition and activity of native marine microorganisms. Several studies have indicated that certain marine hydrocarbon-degrading bacteria, such as Marinobacter spp., can be inhibited by chemical dispersants, resulting in lower abundances and/or reduced hydrocarbon-biodegradation rates. In this respect, a major knowledge gap exists in understanding the mechanisms underlying these observed physiological effects. Here, we performed comparative proteomics of the Deepwater Horizon isolate Marinobacter sp. TT1 grown under different conditions that varied regarding the supplied carbon sources (pyruvate vs. n-hexadecane) and whether or not dispersant (Corexit EC9500A) was added, or that contained crude oil in the form of a water-accommodated fraction (WAF) or chemically-enhanced WAF (CEWAF). We characterized the proteins associated with alkane metabolism and alginate biosynthesis in strain TT1, report on its potential for aromatic hydrocarbon biodegradation and present a proposed metabolism of Corexit components as carbon substrates for the strain. Our findings implicate Corexit in affecting hydrocarbon metabolism, chemotactic motility, biofilm formation, and inducing solvent tolerance mechanisms like efflux pumps in strain TT1. This study provides novel insights into dispersant impacts on microbial hydrocarbon degraders that should be taken into consideration for future oil spill response actions.
Project description:Polycyclic aromatic hydrocarbons (PAHs) can alter gene expression by acting through the aryl hydrocarbon receptor (AHR). In a previous phenotypic screen of over 120 PAHs, we identified four PAHs that induce an ectopic caudal fin (called X-fin) in larval zebrafish: benzo[k]fluoranthene (BkF), dibenzo[b,k]fluoranthene, dibenzo[a,h]anthracene, and benzo[j]fluoranthene. We investigated several plausible mechanisms of X-fin formation using the most potent X-fin inducer, BkF. The X-fin phenotype was dependent on the AHR paralog Ahr2, and we performed RNA sequencing to identify altered gene expression patterns. Transcriptional profiles of distal trunk tissue, where the phenotype was manifest, were generated for animals exposed to 1% DMSO (control) or 12 μM BkF. Four time points of X-fin development were considered for transcriptomics: prior to visual emergence of X-fin (48 hpf), during manifestation of disrupted caudal fin fold development (60 and 72 hpf), and after emergence of X-fin (96 hpf).
Project description:Nitrate-reducing iron(II)-oxidizing bacteria are widespread in the environment contribute to nitrate removal and influence the fate of the greenhouse gases nitrous oxide and carbon dioxide. The autotrophic growth of nitrate-reducing iron(II)-oxidizing bacteria is rarely investigated and poorly understood. The most prominent model system for this type of studies is enrichment culture KS, which originates from a freshwater sediment in Bremen, Germany. To gain insights in the metabolism of nitrate reduction coupled to iron(II) oxidation under in the absence of organic carbon and oxygen limited conditions, we performed metagenomic, metatranscriptomic and metaproteomic analyses of culture KS. Raw sequencing data of 16S rRNA amplicon sequencing, shotgun metagenomics (short reads: Illumina; long reads: Oxford Nanopore Technologies), metagenome assembly, raw sequencing data of shotgun metatranscriptomes (2 conditions, triplicates) can be found at SRA in https://www.ncbi.nlm.nih.gov/bioproject/PRJNA682552. This dataset contains proteomics data for 2 conditions (heterotrophic and autotrophic growth conditions) in triplicates.
2021-05-17 | PXD023186 | Pride
Project description:Transcriptomic analysis in the halophile Aspergillus sydowii: understanding polycyclic aromatic hydrocarbon metabolism under hypersaline conditions
Project description:Degradation of polycyclic aromatic hydrocarbons (PAHs) such as naphthalene by anaerobic microorganisms is poorly understood. Strain NaphS2, an anaerobic sulfate reducing marine delta-proteobacterium is capable of using naphthalene and the aromatic compound benzoate, as well as pyruvate, as an electron donors in the presence of sulfate. In order to identify genes involved in the naphthalene degradation pathway, we compared gene expression in NaphS2 during growth on benzoate vs. pyruvate, naphthalene vs. pyruvate, and naphthalene vs benzoate.
Project description:We demonstrate the feasibility of total RNA-SIP in experiments where microbes from a hydrocarbon-contaminated aquifer were studied in microcosms with 13C-labelled-toluene to understand their adaptation to the simultaneous availability of low levels of different electron acceptors. SIP successfully resolved the involvement of microaerobic vs. aerobic and anaerobic populations. Under microoxic, nitrate-amended conditions hydrocarbon degradation was actually stimulated, but transcripts of denitrification showed no signs of 13C-labelling. The expression of distinct oxygenase-based catabolic pathways for toluene degradation was clearly apparent in 13C-labelled mRNA. We discuss how these direct insights into the gene expression and adaptation mechanisms within complex degrader communities can guide more integrated approaches in monitoring and restoration of contaminated sites.