Sulfur-reducing bacteria are microorganisms able to reduce elemental sulfur (S0) to hydrogen sulfide (H2S). These microbes use inorganic sulfur compounds as electron acceptors to sustain several activities such as respiration, conserving energy and growth, in absence of oxygen. The final product or these processes, sulfide, has a considerable influence on the chemistry of the environment and, in addition, is used as electron donor for a large variety of microbial metabolisms. Several types of bacteria and many non-methanogenic archaea can reduce sulfur. Microbial sulfur reduction was already shown in early studies, which highlighted the first proof of S0 reduction in a vibrioid bacterium from mud, with sulfur as electron acceptor and H
2 as electron donor. The first pure cultured species of sulfur-reducing bacteria, Desulfuromonas acetoxidans, was discovered in 1976 and described by Pfennig Norbert and Biebel Hanno as an anaerobic sulfur-reducing and acetate-oxidizing bacterium, not able to reduce sulfate. Only few taxa are true sulfur-reducing bacteria, using sulfur reduction as the only or main catabolic reaction. Normally, they couple this reaction with the oxidation of acetate, succinate or other organic compounds. In general, sulfate-reducing bacteria are able to use both sulfate and elemental sulfur as electron acceptors. Thanks to its abundancy and thermodynamic stability, sulfate is the most studied electron acceptor for anaerobic respiration that involves sulfur compounds. Elemental sulfur, however, is very abundant and important, especially in deep-sea hydrothermal vents, hot springs and other extreme environments, making its isolation more difficult. Some bacteria – such as Proteus, Campylobacter, Pseudomonas and Salmonella – have the ability to reduce sulfur, but can also use oxygen and other terminal electron acceptors.
In biology, syntrophy, synthrophy, or cross-feeding is the phenomenon of one species feeding on the metabolic products of another species to cope up with the energy limitations by electron transfer. In this type of biological interaction, metabolite transfer happens between two or more metabolically diverse microbial species that live in close proximity to each other. The growth of one partner depends on the nutrients, growth factors, or substrates provided by the other partner. Thus, syntrophism can be considered as an obligatory interdependency and a mutualistic metabolism between two different bacterial species.
Alcanivorax borkumensis is an alkane-degrading marine bacterium which naturally propagates and becomes predominant in crude-oil-containing seawater when nitrogen and phosphorus nutrients are supplemented.
Gallaecimonas is a recently described genus of bacteria. The first described species of this genus was Gallaecimonas pentaromativorans gen. nov., sp. nov. isolated by Rodríguez Blanco et al. in 2010 from intertidal sediments of the ria of Corcubión. It is a Gram-negative, rod-shaped, halotolerant bacterium in the class Gammaproteobacteria. It can degrade high molecular mass polycyclic aromatic hydrocarbons of 4 and 5 rings. The 16S rRNA gene sequences of the type strain CEE_131(T) proved to be distantly related to those of Rheinheimera and Serratia. Its G+C content was 41.7 mol%.
Oxalobacter vibrioformis is an oxalate-degrading anaerobic bacterium that was isolated from anoxic freshwater sediments. O. vibrioformis is a Gram-negative, non-spore-forming, motile, vibrioid rod which belongs to the genus Oxalobacter. O. vibrioformis uses oxalate and oxamate as its sole source of energy and acetate as its main source of carbon.
Cupriavidus basilensis is a gram-negative soil bacterium of the genus Cupriavidus and the family Burkholderiaceae. The complete genome sequence of its type strain has been determined and is publicly available at DNA Data Bank of Japan, European Nucleotide Archive and GenBank, under the accession numbers CP062803, CP062804, CP062805, CP062806, CP062807, CP062808, CP062809 and CP062810.
Sphingomonas yanoikuyae is a short rod-shaped, strictly aerobic, Gram-negative, non-motile, non-spore-forming, chemoheterotrophic species of bacteria that is yellow or off-white in color. Its type strain is JCM 7371. It is notable for degrading a variety of aromatic compounds including biphenyl, naphthalene, phenanthrene, toluene, m-, and p-xylene. S. yanoikuyae was discovered by Brian Goodman on the southern coast of Papua New Guinea. However, Sphingomonas have a wide distribution across freshwater, seawater, and terrestrial habitats. This is due to the bacteria's ability to grow and survive under low-nutrient conditions as it can utilize a broad range of organic compounds.
Propionivibrio dicarboxylicus is a gram negative, strictly anaerobic, non-spore-forming bacterium from the genus of Propionivibrio which was isolated from anaerobic mud from the Lake Kasumigaura in Japan.
Propionivibrio pelophilus is a bacterium from the genus of Propionivibrio. Propionibacter pelophilus has been reclassified to Propionivibrio pelophilus.
Pelobacter venetianus is a species of bacteria that degrade polyethylene glycol. It is strictly anaerobic, Gram-negative, and nonspore-forming.
Holophaga foetida is a bacterium, the type species of its genus. It is a homoacetogenic bacterium degrading methoxylated aromatic compounds. It is gram-negative, obligately anaerobic and rod-shaped, with type strain TMBS4. Its genome has been sequenced. It is known for its ability to anaerobically degrade aromatic compounds and the production of volatile sulfur compounds through a unique pathway.
Propionigenium modestum is a species of gram-negative, strictly anaerobic bacteria. It is rod-shaped and around 0.5-0.6 x 0.5-2.0μm in size. It is important in the elucidation of mechanism of ATP synthase.
Sphingomonas formosensis is a Gram-negative and short rod-shaped bacteria from the genus of Sphingomonas which has been isolated from agricultural soil in Kaohsiung County in Taiwan. Sphingomonas formosensis has the ability to degrade polycyclic aromatic hydrocarbon compounds.
Dyadobacter is a genus of gram negative rod-shaped bacteria belonging to the family Spirosomaceae in the phylum Bacteroidota. Typical traits of the genus include yellow colony colour, positive flexirubin test and non-motile behaviours. They possess an anaerobic metabolism, can utilise a broad range of carbon sources, and test positive for peroxide catalase activity. The type species is Dyadobacter fermentans, which was isolated from surface sterilised maize leaves,.
Filibacter limicola is a Gram-negative bacterium from the genus of Filibacter which has been isolated from lake sediment from the English Lake District in Blelham Tarn in England.
Methanogens are a group of microorganisms that produce methane as a byproduct of their metabolism. They play an important role in the digestive system of ruminants. The digestive tract of ruminants contains four major parts: rumen, reticulum, omasum and abomasum. The food with saliva first passes to the rumen for breaking into smaller particles and then moves to the reticulum, where the food is broken into further smaller particles. Any indigestible particles are sent back to the rumen for rechewing. The majority of anaerobic microbes assisting the cellulose breakdown occupy the rumen and initiate the fermentation process. The animal absorbs the fatty acids, vitamins and nutrient content on passing the partially digested food from the rumen to the omasum. This decreases the pH level and initiates the release of enzymes for further breakdown of the food which later passes to the abomasum to absorb remaining nutrients before excretion. This process takes about 9–12 hours.
Roseivirga echinicomitans is a species of Gram-negative bacteria that belongs to the family Flammeovirgaceae. It is a strictly aerobic, heterotrophic, pink-pigmented, non-motile bacterium from the genus Roseivirga. It was first isolated from the sea urchin Strongylocentrotus intermedius.
Ilyobacter insuetus is a mesophilic and anaerobic bacterium from the genus of Ilyobacter which has been isolated from marine anoxic sediments from Venice in Italy.
Aminobacterium mobile is a Gram-negative, anaerobic, mesophilic, non-spore-forming and motile bacterium from the genus of Aminobacterium which has been isolated from anaerobic lagoon from a dairy wastewater treatment plant in Colombia. Dissimilar to Aminobacterium colombiense, Aminobacterium mobile has a marginally lower DNA GC-content Aminobacterium mobile is motile and ferments Serine to Acetate and Alanine. Aminobacterium mobile is both a Heterotroph and Asaccharolytic. Its adverse effects on both animals and humans are not yet known, but because of the ability of Aminobacterium mobile to degrade amino acids and peptides, the possibility of harmful effects cannot be excluded.
Halanaerobium praevalens is a moderately alkaliphilic, extremely halophilic bacterium that was first isolated from surface sediments of the Great Salt Lake, Utah and described by J.G. Zeikus et al. in 1983, with IJSB validation in 1984.
