The root zone of graminoids: A niche for H-consuming acetogens in a minerotrophic peatland.

The importance of acetogens for H turnover and overall anaerobic degradation in peatlands remains elusive. In the well-studied minerotrophic peatland fen Schlöppnerbrunnen, H-consuming acetogens are conceptualized to be largely outcompeted by iron reducers, sulfate reducers, and hydrogenotrophic methanogens in bulk peat soil. However, in root zones of graminoids, fermenters thriving on rhizodeposits and root litter might temporarily provide sufficient H for acetogens.

Organic carbon from graminoid roots as a driver of fermentation in a fen.

Fen Schlöppnerbrunnen is a moderately acidic methane-emitting peatland overgrown by Molinia caerulea and other wetland graminoids (e.g. Carex rostrata).

Impact of water content and dietary organic carbon richness on gut bacteria in the earthworm .

Many higher and lower animal gut ecosystems have complex resident microbial communities. In contrast, ingested soil is the primary source of the gut microbial diversity of earthworms, invertebrates of fundamental importance to the terrestrial biosphere. Earthworms also harbor a few endemic bacteria including -affiliated Lumbricincola of unknown function.

Amino Acids and Ribose: Drivers of Protein and RNA Fermentation by Ingested Bacteria of a Primitive Gut Ecosystem.

Earthworms are among the most primitive animals and are of fundamental importance to the turnover of organic matter in the terrestrial biosphere. These invertebrates ingest materials that are colonized by microbes, some of which are subject to disruption by the crop/gizzard or other lytic events during gut passage. Protein and RNA are dominant polymers of disrupted microbial cells, and these biopolymers facilitate robust fermentations by surviving ingested bacteria.

Dietary polysaccharides: fermentation potentials of a primitive gut ecosystem.

The alimentary canal of the earthworm is representative of primitive gut ecosystems, and gut fermenters capable of degrading ingested biomass-derived polysaccharides might contribute to the environmental impact and survival of this terrestrial invertebrate. Thus, this study evaluated the postulation that gut microbiota of the model earthworm Lumbricus terrestris ferment diverse biomass-derived polysaccharides. Structural polysaccharides (e.

Fermenters in the earthworm gut: do transients matter?

Earthworms have profound impact on soil-based ecosystems. Although theoretical considerations suggest that most microbes in the earthworm gut are likely ingested and transient, the non-responsiveness of soil microbes to a specific high value gut nutrient and anoxia has made it difficult to demonstrate that responsive gut fermenters are derived from soil. Therefore, soil and gut content of the model earthworm Lumbricus terrestris were examined for their fermentative capabilities.

Protein- and RNA-Enhanced Fermentation by Gut Microbiota of the Earthworm Lumbricus terrestris.

Earthworms are a dominant macrofauna in soil ecosystems and have determinative effects on soil fertility and plant growth. These invertebrates feed on ingested material, and gizzard-linked disruption of ingested fungal and bacterial cells is conceived to provide diverse biopolymers in the anoxic alimentary canals of earthworms. Fermentation in the gut is likely important to the utilization of ingested biopolymer-derived compounds by the earthworm.

Differential Engagement of Fermentative Taxa in Gut Contents of the Earthworm Lumbricus terrestris.

The earthworm gut is an anoxic, saccharide-rich microzone in aerated soils. The apparent degradation of diverse saccharides in the alimentary canal of the model earthworm is concomitant with the production of diverse organic acids, indicating that fermentation is an ongoing process in the earthworm gut. However, little is known about how different gut-associated saccharides are fermented.

Disentangling the influence of earthworms in sugarcane rhizosphere.

For the last 150 years many studies have shown the importance of earthworms for plant growth, but the exact mechanisms involved in the process are still poorly understood. Many important functions required for plant growth can be performed by soil microbes in the rhizosphere. To investigate earthworm influence on the rhizosphere microbial community, we performed a macrocosm experiment with and without Pontoscolex corethrurus (EW+ and EW-, respectively) and followed various soil and rhizosphere processes for 217 days with sugarcane.

Formate-derived H2 , a driver of hydrogenotrophic processes in the root-zone of a methane-emitting fen.

Wetlands are important sources of globally emitted methane. Plants mediate much of that emission by releasing root-derived organic carbon, including formate, a direct precursor of methane. Thus, the objective of this study was to resolve formate-driven processes potentially linked to methanogenesis in the fen root-zone.

Peat: home to novel syntrophic species that feed acetate- and hydrogen-scavenging methanogens.

Syntrophic bacteria drive the anaerobic degradation of certain fermentation products (e.g., butyrate, ethanol, propionate) to intermediary substrates (e.

Anaerobic trophic interactions of contrasting methane-emitting mire soils: processes versus taxa.

Natural wetlands such as mires contribute up to 33% to the global emission of methane. The emission of methane is driven by trophic interactions of anaerobes that collectively degrade biopolymers. The hypothesis of this study was that these interactions in contrasting methane-emitting mire soils are functionally similar but linked to dissimilar taxa.

Methanogenic food web in the gut contents of methane-emitting earthworm Eudrilus eugeniae from Brazil.

The anoxic saccharide-rich conditions of the earthworm gut provide an ideal transient habitat for ingested microbes capable of anaerobiosis. It was recently discovered that the earthworm Eudrilus eugeniae from Brazil can emit methane (CH4) and that ingested methanogens might be associated with this emission. The objective of this study was to resolve trophic interactions of bacteria and methanogens in the methanogenic food web in the gut contents of E.

Temperature impacts differentially on the methanogenic food web of cellulose-supplemented peatland soil.

The impact of temperature on the largely unresolved intermediary ecosystem metabolism and associated unknown microbiota that link cellulose degradation and methane production in soils of a moderately acidic (pH 4.5) fen was investigated. Supplemental [(13) C]cellulose stimulated the accumulation of propionate, acetate and carbon dioxide as well as initial methane production in anoxic peat soil slurries at 15°C and 5°C.

Consumers of 4-chloro-2-methylphenoxyacetic acid from agricultural soil and drilosphere harbor cadA, r/sdpA, and tfdA-like gene encoding oxygenases.

Microbial degradation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) in soil is enhanced by earthworms and initiated by tfdA-like, cadA and r/sdpA gene encoding oxygenases. Copy numbers of such genes increased during MCPA degradation in soil, and MCPA stimulated transcription of tfdA-like and r/sdpA genes up to 4×. Transcription of cadA was detected in the presence of MCPA only.

Methanol oxidation by temperate soils and environmental determinants of associated methylotrophs.

The role of soil methylotrophs in methanol exchange with the atmosphere has been widely overlooked. Methanol can be derived from plant polymers and be consumed by soil microbial communities. In the current study, methanol-utilizing methylotrophs of 14 aerated soils were examined to resolve their comparative diversities and capacities to utilize ambient concentrations of methanol.

Microbiology of Lonar Lake and other soda lakes.

Soda lakes are saline and alkaline ecosystems that are believed to have existed throughout the geological record of Earth. They are widely distributed across the globe, but are highly abundant in terrestrial biomes such as deserts and steppes and in geologically interesting regions such as the East African Rift valley. The unusual geochemistry of these lakes supports the growth of an impressive array of microorganisms that are of ecological and economic importance.

Emission of nitrous oxide and dinitrogen by diverse earthworm families from Brazil and resolution of associated denitrifying and nitrate-dissimilating taxa.

The anoxic earthworm gut augments the activity of ingested microorganisms capable of anaerobiosis. Small earthworms (Lumbricidae) emit denitrification-derived N(2)O, whereas the large Octochaetus multiporus (Megascolecidae) does not. To examine this paradox, differently sized species of the families Glossoscolecidae (Rhinodrilus, Glossoscolex, Pontoscolex), Megascolecidae (Amynthas, Perionyx), Acanthodrilidae (Dichogaster), and Eudrilidae (Eudrilus) from Brazil were analyzed.

Emission of methane by Eudrilus eugeniae and other earthworms from Brazil.

Earthworms emit denitrification-derived nitrous oxide and fermentation-derived molecular hydrogen. The present study demonstrated that the earthworm Eudrilus eugeniae, obtained in Brazil, emitted methane. Other worms displayed a lesser or no capacity to emit methane.

Impairment of cellulose- and cellobiose-degrading soil Bacteria by two acidic herbicides.

Herbicides have the potential to impair the metabolism of soil microorganisms. The current study addressed the toxic effect of bentazon and 4-chloro-2-methylphenoxyacetic acid on aerobic and anaerobic Bacteria that are involved in cellulose and cellobiose degradation in an agricultural soil. Aerobic saccharide degradation was reduced at concentrations of herbicides above environmental values.

Defluviimonas denitrificans gen. nov., sp. nov., and Pararhodobacter aggregans gen. nov., sp. nov., non-phototrophic Rhodobacteraceae from the biofilter of a marine aquaculture.

Three Gram-negative bacterial strains were isolated from the biofilter of a recirculating marine aquaculture. They were non-pigmented rods, mesophiles, moderately halophilic, and showed chemo-organoheterotrophic growth on various sugars, fatty acids, and amino acids, with oxygen as electron acceptor; strains D9-3(T) and D11-58 were in addition able to denitrify. Phototrophic or fermentative growth could not be demonstrated.

Novel [NiFe]- and [FeFe]-hydrogenase gene transcripts indicative of active facultative aerobes and obligate anaerobes in earthworm gut contents.

The concomitant occurrence of molecular hydrogen (H(2)) and organic acids along the alimentary canal of the earthworm is indicative of ongoing fermentation during gut passage. Fermentative H(2) production is catalyzed by [FeFe]-hydrogenases and group 4 [NiFe]-hydrogenases in obligate anaerobes (e.g.

Trophic links between the acetogen Clostridium glycolicum KHa and the fermentative anaerobe Bacteroides xylanolyticus KHb, isolated from Hawaiian forest soil.

Isolate KH was obtained from Hawaiian forest soil and found to be composed of two functionally linked anaerobes, KHa and KHb. Gene analyses (16S rRNA, fhs, cooS) identified KHa as an acetogenic strain of Clostridium glycolicum and KHb as Bacteroides xylanolyticus. KHb fermented xylan and other saccharides that KHa could not utilize and formed products (e.