Enrichment and pure cultures of nitrate-reducing bacteria were shown to grow anaerobically with ferrous iron as the only electron donor or additional in presence acetate. The newly observed bacterial process may significantly contribute ferric formation suboxic zone aquatic sediments.

Anaerobic dissimilatory ferric iron-reducing and ferrous iron-oxidizing bacteria gain energy through reduction or oxidation of iron minerals presumably play an important role in catalyzing transformations anoxic environments. Numerous have been isolated from a great diversity environments, including sediments, soils, deep terrestrial subsurfaces, hot springs. In contrast, only few are known so far. At neutral pH, barely soluble, the mechanisms electron transfer to still poorly understood....

In anoxic environments such as swamps, rice fields and sludge digestors, syntrophic microbial communities are important for decomposition of organic matter to CO2 CH4 . The most difficult step is the fermentative degradation short-chain fatty acids propionate butyrate. Conversion these metabolites acetate, , formate hydrogen endergonic under standard conditions occurs only if methanogens keep concentrations intermediate products low. Butyrate pathways include oxidation steps comparably high...

Significance Evidence whether the recently discovered denitrification-dependent methane oxidation (nitrate/nitrite-dependent anaerobic oxidation, n-damo) represents a major sink or an insignificant side aspect in global cycle is scarce. High-resolution microprofiles measured intact sediment cores close to situ conditions, anoxic incubations of sediments, and quantification responsible microorganisms with molecular techniques proved n-damo be Lake Constance, one best-studied freshwater lakes....

The biological and chemical potential for electron shuttling via humic acids was evaluated by analyzing the depth distribution of humic-acid-reducing iron-reducing bacteria in a freshwater sediment, correlating it to redox characteristics iron. Physicochemical analysis profundal sediments Lake Constance revealed distinct stratification, with oxygen respiration, microbial iron sulfate reduction, methanogenesis allocatable defined layers. Among acid-extractable surface layer, ferric (Fe(III))...

A syntrophic acetate-oxidizing bacterium, strain BST (T = type strain), was isolated from a previously described mesophilic triculture that able to syntrophically oxidize acetate and form methane in stoichiometric amounts. Strain with substrates typically utilized by homoacetogenic bacteria. spore-forming, gram-positive, rod-shaped organism which formate, glucose, ethylene glycol, cysteine, betaine, pyruvate. Acetate sometimes formate were the main fermentation products. Small amounts of...

ABSTRACT Denitrification and nitrate ammonification are considered the highest-energy-yielding respiration systems in anoxic environments after oxygen has been consumed. The corresponding free energy changes 7 35% lower than that of aerobic respiration, respectively. Growth yield determinations with pure cultures Paracoccus denitrificans Pseudomonas stutzeri revealed far less is converted via ATP into cell mass expected from above calculations. formate or hydrogen as electron donor yielded...

ABSTRACT Understanding the mechanisms of anaerobic microbial iron cycling is necessary for a full appreciation present‐day biogeochemical and carbon drawing conclusions about these cycles on ancient Earth. Towards that end, we isolated characterized an nitrate‐dependent Fe(II)‐oxidizing bacterium from freshwater sediment. The 16SrRNA gene sequence (strain BoFeN1) places it within β‐Proteobacteria, with Acidovorax sp. strain G8B1 as closest known relative. During mixotrophic growth acetate...

ABSTRACT Anaerobic naphthalene degradation by a sulfate-reducing enrichment culture was studied substrate utilization tests and identification of metabolites gas chromatography-mass spectrometry. In tests, the able to oxidize naphthalene, 2-methylnaphthalene, 1- 2-naphthoic acids, phenylacetic acid, benzoic cyclohexanecarboxylic cyclohex-1-ene-carboxylic acid with sulfate as electron acceptor. Neither hydroxylated or derivatives 2-naphthol nor monoaromatic compounds ortho -phthalic...

In previous studies, three different strains (BrG1, BrG2, and BrG3) of ferrous iron-oxidizing, nitrate-reducing bacteria were obtained from freshwater sediments. All facultative anaerobes utilized a variety organic substrates molecular hydrogen with nitrate as electron acceptor. this study, analyses 16S rDNA sequences showed that strain BrG1 was affiliated the genus Acidovorax, BrG2 Aquabacterium, BrG3 Thermomonas. Previously, similar to these detected techniques in MPN dilution series for...

ABSTRACT Iron-reducing bacteria have been reported to reduce humic acids and low-molecular-weight quinones with electrons from acetate or hydrogen oxidation. Due the rapid chemical reaction of amorphous ferric iron reduced products, redox mediators may play an important role in biological reduction. Since many anaerobic that are not able directly known transfer other external acceptors, such as ferricyanide, 2,6-anthraquinone disulfonate (AQDS), molecular oxygen, we tested several...