Biology subjects

Nijsse, B.

Publications and source records attributed to Nijsse, B..

8 recordsLinked to original sources

bioRxiv2026

Unraveling the metabolic interactions of a Dehalobacter-containinganaerobic mixed culture for bioremediation

Organohalide-respiring bacteria (OHRB), such as Dehalobacter, play key roles in the bioremediation of anoxic environments contaminated with chlorinated aromatic compounds. These obligate anaerobes rely on syntrophic interactions to obtain essential resources--hydrogen, acetate, and corrinoid cofactors--from acetogens and fermenters. However, the metabolic interactions enabling complete reductive dehalogenation of compounds like 1,2,4-trichlorobenzene (1,2,4-TCB) to benzene remain incompletely understood. In this study, we asked: (1) What are the key microbial taxa and their functional roles within a Dehalobacter-containing anaerobic microbial community detoxifying chlorinated benzenes? (2) How do syntrophic interactions enable complete dehalogenation of 1,2,4-TCB to benzene under anaerobic conditions? (3) Can genome-resolved metagenomics and genome-scale metabolic modeling elucidate the metabolic dependencies supporting organohalide respiration in complex consortia? To address these questions, we cultivated microbial communities in batch reactors using methanol as electron donor and either 1,2,4-TCB or monochlorobenzene (MCB) as electron acceptor. In active MCB-fed cultures, benzene increased from 0 to 62.3{micro}mol per bottle while MCB decreased from 88.3 to 22.0{micro}mol per bottle over 120 days, with this pattern repeating across multiple substrate additions. Using genome-resolved metagenomics to identify dominant taxa and select 12 high-quality metagenome-assembled genomes (MAGs) for modeling, we reconstructed genome-scale metabolic models (GEMs) to identify candidate metabolic interactions and predict syntrophic dependencies that may support organohalide respiration in these consortia. Community flux sampling predicted that methanol, H2, acetate, and CO2 formed the dominant exchange backbone of the modeled community, while also indicating competition for shared electron donors between the two Dehalobacter populations. Model-guided minimal-community analysis further identified a narrow dechlorinating core in which all feasible minimal consortia retained a Dehalobacter member together with Methanothrix. These results provide a modeling-informed framework for hypothesis generation and future experimental validation of anaerobic consortia relevant to bioremediation.

systems biology↗

bioRxiv2025

A metadata managed FAIR end-to-end workflow for microbial community Omics data analysis

BackgroundMolecular profiling using high-throughput omics technologies has tremendously increased our ability to interrogate complex microbial communities at the molecular level. In the context of data reuse, the FAIRification of these extensive datasets is frequently perceived as a secondary administrative task, addressed only after data analysis has been completed. However, this approach overlooks the potential benefits of early metadata integration as the procedures for processing and analyzing raw data are primarily dictated by the underlying research design and experimental conditions. Gathering interoperable research metadata at the earliest stages creates a standardized basis for managing, processing, and analyzing data enabling more efficient and reproducible FAIR workflows. ResultsThe single containment principle was used to develop modular containerized reproducible workflows that support the FAIR principles for research software by systematically capturing standardized metadata for each data processing step along with the resulting data products. Using defined mock metagenomic datasets as an example, we show that interoperable research metadata can be used to drive such computational workflows. By processing raw data accordingly, machine-actionable provenance chains are created that enhance the reproducibility and reusability of the resulting data products. ConclusionsA seamless integration of wet lab experiments with computational investigations is essential for a FAIR end-to-end research process. Meta-data-managed workflows prevent the need for unnecessary data manipulation. Workflow provenance registration explicates the complex multi-step methods employed for data processing and analysis. Combining FAIR principles with data provenance registration enhances the reusability of omics datasets by promoting transparency and reproducibility. O_TEXTBOXKey PointsO_LIWe present the first metadata-managed FAIR end-to-end workflow for microbial community Omics data analysis. C_LIO_LIThe framework links experiment metadata with CWL workflows, enabling seamless metadata-driven execution from experiment to data product. C_LIO_LIComprehensive provenance tracking using RDF standards creates machine-actionable chains connecting wet-lab protocols to computational outputs, enhancing reproducibility and supporting automated workflow validation. C_LIO_LIBenchmarking with defined mock communities demonstrates workflow reliability across assembly methods while generating FAIR-compliant research objects suitable for community reuse and comparative studies. C_LI C_TEXTBOX

bioinformatics↗

bioRxiv2024

Comparative genomics of Rickettsiella bacteria reveal variable metabolic traits involved in symbiotic interactions with arthropods

Members of the Rickettsiella genus (order: Legionellales) are emerging as widespread bacteria associated with insects, arachnids, and crustaceans. While some Rickettsiella strains are highly virulent pathogens, others are maternally inherited endosymbionts that manipulate arthropod phenotypes, including the induction of defensive symbiosis and cytoplasmic incompatibility. However, the genomic diversity of Rickettsiella remains largely unexplored, and their genetic potential to induce complex phenotypes in arthropods is only partially understood. In this study, we sequenced five new Rickettsiella genomes isolated from three tick species. Through comparative genomics, we observed that Rickettsiella members share similar metabolic capabilities, and collectively lack virulence genes from pathogenic Legionellales. Additional analysis of Rickettsiella genomes revealed significant variability in metabolic properties related to endosymbiosis. Specifically, their capacity to biosynthesize certain B vitamins and heme varies, suggesting a functional role of some Rickettsiella strains in the nutrition of their arthropod hosts. Some Rickettsiella genomes harbour homologs of Wolbachia cif genes, the cause of Wolbachia-induced cytoplasmic incompatibility,, suggesting that Rickettsiella may use a similar molecular mechanism to manipulate the reproduction of their arthropod hosts. Phylogenomics further revealed that tick-borne Rickettsiella exhibit distinct evolutionary origins within the genus, indicating that Rickettsiella have undergone repeated horizontal transfers between ticks and other arthropods.

evolutionary biology↗

bioRxiv2024

Deep sequencing of 16 Ixodes ricinus ticks unveils insights into their interactions with endosymbionts.

BackgroundIxodes ricinus ticks act as vectors for numerous pathogens that present substantial health threats. Additionally, they harbour vertically transmitted symbionts, some of which have been linked to diseases. The difficulty of isolating and cultivating these symbionts has hampered our understanding of their biological role, their potential to cause disease, and their modes of transmission. To expand our understanding on the tick symbiont Midichloria mitochondrii and on Rickettsia helvetica, which has been linked to disease in humans, we utilized deep sequencing on sixteen individual adult female ticks collected from coastal dune and forested areas in the Netherlands. ResultsBy employing a combination of second and third-generation sequencing techniques, we successfully reconstructed the complete genomes of M. mitochondrii from eleven individuals, R. helvetica from eight individuals and the mitochondrial genome from all ticks. Additionally, we visualised the location of R. helvetica in tick organs and constructed genome-scale metabolic models (GEMs) of both symbionts to study their environmental dependencies. Our analysis revealed a strong cophylogeny between M. mitochondrii and mitochondrial genomes, suggesting frequent maternal transmission. In contrast, the absence of cophylogeny between R. helvetica and the mitochondrial genomes, coupled with its presence in the receptaculum seminis of I. ricinus females, raises the possibility of paternal transmission of R. helvetica. Notably, the genetic diversity of R. helvetica was found to be very low, except for the rickA virulence gene, where the presence of up to thirteen insertions of a33nt-long repeat led to significant variability. However, this variation could not account for the differences in infection prevalence observed across eight distinct locations in the Netherlands. ConclusionsBy employing deep sequencing, it becomes feasible to extract complete genomes and genetic data of symbionts directly from their host organisms. This methodology serves as a robust means to gain fresh insights into their interactions. Our observations, which suggest paternal transmission of R. helvetica, a relatively unexplored mode of transmission in ticks, require validation through experimental investigations. The genetic variations identified in the rickA virulence gene of R. helvetica have the potential to influence the infectivity and transmission dynamics of R. helvetica

microbiology↗

bioRxiv2024

Improved genome sequence and annotation of Cutaneotrichosporon oleaginosus ATCC 20509

Cutaneotrichosporon oleaginosus is an oleaginous yeast with a high content of fatty acids and can accumulate more than 40% of its weight in lipids. It can grow on a wide range of carbon sources and side streams such as crude glycerol. The genome sequence of C. oleaginosus ATCC 20509 is reported here to contribute to its development as a biotechnological platform for producing microbial oils.

microbiology↗

bioRxiv2022

FAIR Data Station for Lightweight Metadata Management & Validation of Omics Studies

BackgroundThe Life sciences is an interdisciplinary field of research and one of the the biggest suppliers of scientific data. Reusing and connecting this data can uncover hidden insights and lead to new concepts, provided there is machine-actionable metadata available about the scientific experiments conducted with a degree of completeness that reflect the FAIR guiding principles. While stakeholders have embraced the FAIR principles, in practice there are a limited number of easy to adopt practical implementations available that fulfil the needs of data producers. FindingsWe developed the FAIR Data Station, a lightweight application written in Java, that aims to support researchers in managing research metadata according to the FAIR principles. It uses the ISA metadata framework and metadata standards to capture experimental metadata. The FAIR Data Station metadata registration workflow consists of three main modules. Based on the minimal information checklist(s) selected by the user, a web-based "form generation module" creates a standardized metadata template Excel workbook which is used as a familiar environment for offline sample metadata registration. A web-based "validation module" checks the format of the metadata recorded in the workbook. The "resource module" subsequently exports the validated set of recorded metadata into an RDF data file, enabling (cross-project) meta data searches. ConclusionsTurning FAIR into reality requires the availability of easy to adopt data FAIRification workflows that provide immediate beneficial incentives to the individual researcher. As such the FAIR Data Station provides in addition to the means to correctly FAIRify sequence data, the means to build searchable databases of (local) projects and can assists in ENA metadata submission of sequence data. The FAIR Data Station is available at http://fairbydesign.nl.

bioinformatics↗

bioRxiv2019

Metagenomic- and cultivation-based exploration of anaerobic chloroform biotransformation in hypersaline sediments as natural source of chloromethanes

Chloroform (CF) is an environmental contaminant that can be naturally formed in various environments ranging from forest soils to salt lakes. Here we investigated CF removal potential in sediments obtained from hypersaline lakes in Western Australia. Reductive dechlorination of CF to dichloromethane (DCM) was observed in enrichment cultures derived from sediments of Lake Strawbridge, which has been reported as a natural source of CF. The lack of CF removal in the abiotic control cultures without artificial electron donors indicated that the observed CF removal is a biotic process. Metabolite analysis with 13C labelled CF in the sediment-free enrichment cultures (pH 8.5, salinity 5%) revealed that increasing the vitamin B12 concentration from 0.04 to 4 M enhanced CF removal, reduced DCM formation, and increased 13CO2 production, which is likely a product of CF oxidation. Known organohalide-respiring bacteria and reductive dehalogenase genes were neither detected by quantitative PCR nor metagenomic analysis. Rather, members of the order Clostridiales, known to co-metabolically transform CF to DCM and CO2, were detected in the enrichment cultures. Genome-resolved metagenome analysis indicated that their genomes encode enzymatic repertoires for the Wood-Ljungdahl pathway and cobalamin biosynthesis that are known to be involved in co-metabolic CF transformation. ImportanceMore than 90% of the global CF emission to the atmosphere originates from natural sources, including saline environments such as salt lake sediments. However, knowledge about the microbial metabolism of CF in such extreme environments is lacking. Here we showed CF transformation potential in a hypersaline lake that was reported as a natural source of CF production. Application of interdisciplinary approaches of microbial cultivation, stable isotope labelling, and metagenomics aided in defining potential chloroform transformation pathways. This study indicates that microbiota may act as a filter to reduce CF emission from hypersaline lakes to the atmosphere, and expands our knowledge of halogen cycling in extreme hypersaline environments.

microbiology↗

bioRxiv2019

Organohalide-respiring Desulfoluna species isolated from marine environments

The genus Desulfoluna comprises two anaerobic sulfate-reducing strains, D. spongiiphila AA1{top} and D. butyratoxydans MSL71{top} of which only the former was shown to perform organohalide respiration (OHR). Here we isolated a third member of this genus from marine intertidal sediment, designed D. spongiiphila strain DBB. All three Desulfoluna strains harbour three reductive dehalogenase gene clusters (rdhABC) and corrinoid biosynthesis genes in their genomes. Brominated but not chlorinated aromatic compounds were dehalogenated by all three strains. The Desulfoluna strains maintained OHR in the presence of 20 mM sulfate or 20 mM sulfide, which often negatively affect OHR. Strain DBB sustained OHR with 2% oxygen in the gas phase, in line with its genetic potential for reactive oxygen species detoxification. Reverse transcription-quantitative PCR (RT-qPCR) revealed differential induction of rdhA genes in strain DBB in response to 1,4-dibromobenzene or 2,6-dibromophenol. Proteomic analysis confirmed differential expression of rdhA1 with 1,4-dibromobenzene, and revealed a possible electron transport chain from lactate dehydrogenases and pyruvate oxidoreductase to RdhA1 via menaquinones and either RdhC, or Fix complex (electron transfer flavoproteins), or Qrc complex (Type-1 cytochrome c3:menaquinone oxidoreductase).

microbiology↗