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Bacteriology is the branch and specialty of biology that studies the morphology, ecology, genetics and biochemistry of bacteria as well as many other aspects related to them. This subdivision of microbiology involves the identification, classification, and characterization of bacterial species. Because of the similarity of thinking and working with microorganisms other than bacteria, such as protozoa, fungi, and viruses, there has been a tendency for the field of bacteriology to extend as microbiology. The terms were formerly often used interchangeably. However, bacteriology can be classified as a distinct science.
The purple sulfur bacteria (PSB) are part of a group of Pseudomonadota capable of photosynthesis, collectively referred to as purple bacteria. They are anaerobic or microaerophilic, and are often found in stratified water environments including hot springs, stagnant water bodies, as well as microbial mats in intertidal zones. Unlike plants, algae, and cyanobacteria, purple sulfur bacteria do not use water as their reducing agent, and therefore do not produce oxygen. Instead, they can use sulfur in the form of sulfide, or thiosulfate (as well, some species can use H2, Fe2+, or NO2−) as the electron donor in their photosynthetic pathways. The sulfur is oxidized to produce granules of elemental sulfur. This, in turn, may be oxidized to form sulfuric acid.
Nitrosomonas is a genus of Gram-negative bacteria, belonging to the Betaproteobacteria. It is one of the five genera of ammonia-oxidizing bacteria and, as an obligate chemolithoautotroph, uses ammonia as an energy source and carbon dioxide as a carbon source in presence of oxygen. Nitrosomonas are important in the global biogeochemical nitrogen cycle, since they increase the bioavailability of nitrogen to plants and in the denitrification, which is important for the release of nitrous oxide, a powerful greenhouse gas. This microbe is photophobic, and usually generate a biofilm matrix, or form clumps with other microbes, to avoid light. Nitrosomonas can be divided into six lineages: the first one includes the species Nitrosomonas europea, Nitrosomonas eutropha, Nitrosomonas halophila, and Nitrosomonas mobilis. The second lineage presents the species Nitrosomonas communis, N. sp. I and N. sp. II, meanwhile the third lineage includes only Nitrosomonas nitrosa. The fourth lineage includes the species Nitrosomonas ureae and Nitrosomonas oligotropha and the fifth and sixth lineages include the species Nitrosomonas marina, N. sp. III, Nitrosomonas estuarii and Nitrosomonas cryotolerans.
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 of 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.
Polyphosphate-accumulating organisms (PAOs) are a group of microorganisms that, under certain conditions, facilitate the removal of large amounts of phosphorus from their environments. The most studied example of this phenomenon is in polyphosphate-accumulating bacteria (PAB) found in a type of wastewater processing known as enhanced biological phosphorus removal (EBPR), however phosphate hyperaccumulation has been found to occur in other conditions such as soil and marine environments, as well as in non-bacterial organisms such as fungi and algae. PAOs accomplish this removal of phosphate by accumulating it within their cells as polyphosphate. PAOs are by no means the only microbes that can accumulate phosphate within their cells and in fact, the production of polyphosphate is a widespread ability among microbes. However, PAOs have many characteristics that other organisms that accumulate polyphosphate do not have that make them amenable to use in wastewater treatment. Specifically, in the case of classical PAOs, is the ability to consume simple carbon compounds without the presence of an external electron acceptor by generating energy from internally stored polyphosphate and glycogen. Many bacteria cannot consume carbon without an energetically favorable electron acceptor and therefore PAOs gain a selective advantage within the mixed microbial community present in the activated sludge. Therefore, wastewater treatment plants that operate for enhanced biological phosphorus removal have an anaerobic tank prior to the other tanks to give PAOs preferential access to the simple carbon compounds in the wastewater that is influent to the plant.
Burkholderia pseudomallei is a Gram-negative, bipolar, aerobic, motile rod-shaped bacterium. It is a soil-dwelling bacterium endemic in tropical and subtropical regions worldwide, particularly in Thailand and northern Australia. It was reported in 2008 that there had been an expansion of the affected regions due to significant natural disasters, and it could be found in Southern China, Hong Kong, and countries in America. B. pseudomallei, amongst other pathogens, has been found in monkeys imported into the United States from Asia for laboratory use, posing a risk that the pathogen could be introduced into the country.
Microbial metabolism is the means by which a microbe obtains the energy and nutrients it needs to live and reproduce. Microbes use many different types of metabolic strategies and species can often be differentiated from each other based on metabolic characteristics. The specific metabolic properties of a microbe are the major factors in determining that microbe's ecological niche, and often allow for that microbe to be useful in industrial processes or responsible for biogeochemical cycles.
Betaproteobacteria are a class of Gram-negative bacteria, and one of the eight classes of the phylum Pseudomonadota.
Paracoccus denitrificans, is a coccoid bacterium known for its nitrate reducing properties, its ability to replicate under conditions of hypergravity and for being a relative of the eukaryotic mitochondrion.
Nitrospira translate into “a nitrate spiral” is a genus of bacteria within the monophyletic clade of the Nitrospirota phylum. The first member of this genus was described 1986 by Watson et al. isolated from the Gulf of Maine. The bacterium was named Nitrospira marina. Populations were initially thought to be limited to marine ecosystems, but it was later discovered to be well-suited for numerous habitats, including activated sludge of wastewater treatment systems, natural biological marine settings, water circulation biofilters in aquarium tanks, terrestrial systems, fresh and salt water ecosystems, and hot springs. Nitrospira is a ubiquitous bacterium that plays a role in the nitrogen cycle by performing nitrite oxidation in the second step of nitrification. Nitrospira live in a wide array of environments including but not limited to, drinking water systems, waste treatment plants, rice paddies, forest soils, geothermal springs, and sponge tissue. Despite being abundant in many natural and engineered ecosystems Nitrospira are difficult to culture, so most knowledge of them is from molecular and genomic data. However, due to their difficulty to be cultivated in laboratory settings, the entire genome was only sequenced in one species, Nitrospira defluvii. In addition, Nitrospira bacteria's 16S rRNA sequences are too dissimilar to use for PCR primers, thus some members go unnoticed. In addition, members of Nitrospira with the capabilities to perform complete nitrification has also been discovered and cultivated.
Caballeronia zhejiangensis is a Gram-negative, non-spore-forming, rod-shaped bacterium from the genus Caballeronia, which was isolated from a wastewater treatment system in China. Caballeronia zhejiangensis has the ability to degrade methyl parathion.
Rhodovulum sulfidophilum is a gram-negative purple nonsulfur bacteria. The cells are rod-shaped, and range in size from 0.6 to 0.9 μm wide and 0.9 to 2.0 μm long, and have a polar flagella. These cells reproduce asexually by binary fission. This bacterium can grow anaerobically when light is present, or aerobically (chemoheterotrophic) under dark conditions. It contains the photosynthetic pigments bacteriochlorophyll a and of carotenoids.
Acidobacterium capsulatum is a bacterium. It is an acidophilic chemoorganotrophic bacterium containing menaquinone. It is gram-negative, facultative anaerobic, mesophilic, non-spore-forming, capsulated, saccharolytic and rod-shaped. It is also motile by peritrichous flagella. Its type strain is JCM 7670.
Lysinibacillus fusiformis is a gram-positive, rod-shaped bacterium of the genus Lysinibacillus. Scientists have yet to completely characterize this microbe's pathogenic nature. Though little is known about this organism, several genome sequencing projects for various strains of L. fusiformis are currently underway.
Ethanoligenens harbinense is a strictly anaerobic bacterium. It is Gram-positive, non-spore-forming, mesophilic and motile, its cells being regular rods. Its type strain is YUAN-3T.
Marinobacter vinifirmus is a Gram-negative, moderately halophilic, non-spore-forming and motile bacterium from the genus of Marinobacter which has been isolated from wine-barrel-decalcification wastewater in France.
Xenophilus azovorans is a bacterium from the genus Xenophilus which has been isolated from soil in Switzerland.
Cloacibacillus evryensis is a Gram-negative, anaerobic, mesophilic, rod-shaped and non-motile bacterium from the genus of Cloacibacillus which has been isolated from sewage sludge from a wastewater treatment plant in Évry, France.
Coprothermobacter platensis is a species of moderately thermophilic and strictly anaerobic bacterium belonging to the family Coprothermobacteraceae within the phylum Coprothermobacterota.
Haloimpatiens lingqiaonensis is a Gram-positive, peritrichous, non-spore-forming and rod-shaped bacterium from the genus of Haloimpatiens which has been isolated from wastewater from a paper mill.
References
- Allen, Toby D.; et al. (2006). "Cloacibacterium normanense gen. nov., sp. nov., a novel bacterium in the family Flavobacteriaceae isolated from municipal wastewater". International Journal of Systematic and Evolutionary Microbiology. 56 (Pt 6): 1311–1316. doi: 10.1099/ijs.0.64218-0 . PMID 16738108.
- Peterson, Althea (2006-06-17). "Tiny discovery made in Norman". The Norman Transcript. Retrieved 9 February 2016.