Biology subjects

Reintjes, G.

Publications and source records attributed to Reintjes, G..

6 recordsLinked to original sources

bioRxiv2025

Global distribution of microbial carrageenan foraging pathways reveals widespread latent traits within the genetic dark matter of ruminant intestinal microbiomes

Seaweeds represent a promising source of sustainable, alternative feeds for livestock. Despite their increasing popularity in agriculture, the dietary fate of seaweed polysaccharides, such as carrageenan, is unknown. Here, we applied functional microbiome analyses of ruminant gastrointestinal tract microbiomes to discover catabolic enzymes specific for carrageenan digestion from the red seaweed Mazzaella japonica. M. japonica preferentially increased Bacteroides abundance within the distal gut over the rumen, and bacterial isolates had capacity to use carrageenans as a sole carbon source. Carrageenan-active polysaccharide utilization loci (CarPULs) were identified and recombinant enzymes were characterized to provide insights into pathway specialization of divergent CarPULs. Selective enrichment and metagenomic mining revealed that carrageenan catabolism is widespread among geographically and taxonomically distinct ruminants, suggesting it is a globally distributed latent trait within the order Ruminantia and carried within microbiome as part of the microbial "dark matter". These pathways are structurally distinct from those found in marine bacteria, highlighting a complex and ancient evolutionary history of CarPULs in ruminant microbiomes.

microbiology↗

bioRxiv2024

Microbial alginate foraging is conserved in geographically and taxonomically distinct ruminant microbiomes

Seaweed plays a crucial role in carbon cycling and is expected to be a valuable resource for sustainable biomass, with applications in biofuel production, human nutrition, and animal feed. Although seaweed has historically been used as a feed source for livestock grazing near coastlines, the process by which it is digested in the rumen remains unknown. Here, we show how the brown algae Saccharina latissima is catabolized in the rumen ecosystem of two different species using in vivo and in vitro experimental systems. We determined that the ruminal decomposition of alginate, a prominent component of the brown algae cell wall, requires microbial catabolic pathways complete with alginate lyases and transport proteins. Evidence of digestion was obtained through a combination of animal models, bacterial imaging, multilayered meta-omics, and enzyme biochemistry. The evolution of and implications for acquisition of alginate utilization loci within geographically and taxonomically distinct ruminants are considered. Graphical abstractSaccharina latissima is a brown alga commonly found in the North Atlantic, Arctic and Pacific oceans. S. latissima was collected from the west coast and Canada and Norway for microbiome studies. Alginate constitutes a substantial portion of the cell wall of S. latissima (SL), and its digestion requires a specific set of enzymes, alginate lyases. We investigated if and how S. latissima is metabolized in geographically distinct rumen ecosystems through in vivo lamb feeding experiments (2.5 and 5% inclusion, DM basis) and in vitro cattle-based rumen simulation technique, RUSITEC, experiments (up to 50% inclusion). Evidence supporting ruminal degradation of alginate was explored using a combination of multilayered meta-omics, physiology (fluorescently labelled S. latissima hot water extracts (FLA-SLAT)) and biochemical characterization of PL6 alginate lyases. O_FIG O_LINKSMALLFIG WIDTH=161 HEIGHT=200 SRC="FIGDIR/small/628917v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@eebe40org.highwire.dtl.DTLVardef@c6fb8org.highwire.dtl.DTLVardef@7a9b1borg.highwire.dtl.DTLVardef@15d30d7_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2024

Phosphate starvation stops bacteria digesting algal fucan that sequesters carbon

Algae provide a solar powered pathway to capture and sequester carbon by injecting stable fucan made from carbon dioxide into the ocean 1-4. Stability of the pathway is at odds with the presence of marine bacteria with genes of enzymes that can digest fucan and release the carbon dioxide 5. Biochemical explanations for stable fucan remain hypothetical 6. We assembled a biological carbon cycle model and found phosphate limitation enhanced fucan synthesis by algae, stopped digestion by bacteria and thereby stabilized the fucan carbon sequestration pathway. Marine microalgae Glossomastix sp. PLY432 increased synthesis of fucan, a part of its extracellular matrix, under nutrient-growth limiting conditions. Rate and extent of fucan digestion by a marine, isolated bacterium of the Akkermansiaceae family decreased with decreasing phosphate concentration. Phosphate starvation restricted bacterial growth rate, biomass yield and in turn increased the amount of stable fucan. Phosphate is universally required for growth but rare relative to glycan carbon in photosynthesis-derived ecosystems. The fact that phosphate is required for replication, transcription and translation explains why bacteria can digest gigatons of laminarin with a few enzymes, but not fucan during nutrient limited algal blooms. We conclude phosphate starvation constrains the ability of bacteria to digest fucan, which evolves to maintain stability around algal cells and consequentially also to keep carbon dioxide in the ocean.

microbiology↗

bioRxiv2023

Visualizing and identifying selfish bacteria: a hunting guide

Polysaccharides are dominant components of plant biomass, whose degradation is typically mediated by heterotrophic bacteria. These bacteria use extracellular enzymes to hydrolyze polysaccharides to oligosaccharides that are then also available to other bacteria. Recently, a new mechanism of polysaccharide processing - selfish uptake - has been recognized, initially among gut-derived bacteria. In selfish uptake, polysaccharides are bound at the outer membrane, partially hydrolyzed, and transported into the periplasmic space without loss of hydrolysis products, thus limiting the availability of smaller sugars to the surrounding environment. Selfish uptake is widespread in environments ranging from the oceans cool, oxygen-rich, organic carbon-poor waters to the warm, carbon-rich, anoxic environment of the human gut. We provide a detailed guide of how to hunt for selfish bacteria, including how to rapidly visualize selfish uptake in complex bacterial communities, identify selfish organisms, and distinguish the activity of selfish organisms from other members of the community.

microbiology↗

bioRxiv2020

Quantifying fluorescent glycan uptake to elucidate strain-level variability in foraging behaviors of rumen bacteria

Gut microbiomes have vast catabolic potential and are essential to host health and nutrition. An in-depth understanding of the metabolic pathways in these ecosystems will enable us to design treatments (i.e. prebiotics) that influence microbiome structure and enhance host physiology. Currently, the investigation of metabolic pathways relies on inferences derived from metagenomics or in vitro cultivations, however, novel approaches targeting specific cell physiologies can illuminate the functional potential encoded within microbial (meta)genomes to accurately assess metabolic abilities. Here, we present a multi-faceted study using complimentary next-generation physiology and omics approaches to characterize the microbial adaptation to a prebiotic in the rumen ecosystem. Using fluorescently labeled polysaccharides, we identified bacteria that actively metabolize a glycan prebiotic in the rumen microbiome ex vivo. Subsequently, we characterized strain-level variability in carbohydrate utilization systems and predict metabolic strategies of isolated bovine-adapted strains of Bacteroides thetaiotaomicron using comparative whole genome sequencing, RNA-Seq, and carbohydrate-active enzyme fingerprinting.

microbiology↗

bioRxiv2020

Short-term changes in polysaccharide utilization mechanisms of marine bacterioplankton during a spring phytoplankton bloom

Spring phytoplankton blooms in temperate environments contribute disproportionately to global marine productivity. Bloom-derived organic matter, much of it occurring as polysaccharides, fuels biogeochemical cycles driven by interacting autotrophic and heterotrophic communities. We tracked changes in the mode of polysaccharide utilization by heterotrophic bacteria during the course of a diatom-dominated bloom in the German Bight, North Sea. Polysaccharides can be taken up in a selfish mode, where initial hydrolysis is coupled to transport into the periplasm, such that little to no low molecular weight (LMW) products are externally released to the environment. Alternatively, polysaccharides hydrolyzed by cell-surface attached or free extracellular enzymes (external hydrolysis) yield LMW products available to the wider bacterioplankton community. In the early bloom phase, selfish activity was accompanied by low extracellular hydrolysis rates of a few polysaccharides. As the bloom progressed, selfish uptake increased markedly, and external hydrolysis rates increased, but only for a limited range of substrates. The late bloom phase was characterized by high external hydrolysis rates of a broad range of polysaccharides, and reduced selfish uptake of polysaccharides, except for laminarin. Substrate utilization mode is related both to substrate structural complexity and to the bloom-stage dependent composition of the heterotrophic bacterial community. Originality statementThe means by which heterotrophic bacteria cooperate and compete to obtain substrates is a key factor determining the rate and location at which organic matter is cycled in the ocean. Much of this organic matter is high molecular weight (HMW), and must be enzymatically hydrolyzed to smaller pieces to be processed by bacterial communities. Some of these enzyme-producing bacteria are selfish, processing HMW organic matter without releasing low molecular weight (LMW) products to the environment. Other bacteria hydrolyze HMW substrates in a manner that releases LMW products to the wider bacterial community. How these mechanisms of substrate hydrolysis work against a changing background of organic matter supply is unclear. Here, we measured changing rates and mechanisms of substrate processing during the course of a natural phytoplankton bloom in the North Sea. Selfish bacteria generally dominate in the initial bloom stages, but a greater supply of increasingly complex substrates in later bloom stages leads to external hydrolysis of a wider range of substrates, increasing the supply of LMW hydrolysis products to the wider bacterial community.

microbiology↗