A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells.
The microbial loop describes a trophic pathway where, in aquatic systems, dissolved organic carbon (DOC) is returned to higher trophic levels via its incorporation into bacterial biomass, and then coupled with the classic food chain formed by phytoplankton-zooplankton-nekton. In soil systems, the microbial loop refers to soil carbon. The term microbial loop was coined by Farooq Azam, Tom Fenchel et al. in 1983 to include the role played by bacteria in the carbon and nutrient cycles of the marine environment.
Farooq Azam is a researcher in the field of marine microbiology. He is a Distinguished Professor at the Scripps Institution of Oceanography, at the University of California San Diego. Farooq Azam grew up in Lahore and received his early education in Lahore. He attended University of Punjab, where he received his B.Sc. in chemistry. He later he received his M.Sc. from the same institution. He then went to Czechoslovakia for higher studies. He received his PhD in microbiology from the Czechoslovak Academy of Sciences. After he received his PhD, Farooq Azam moved to California. Azam was the lead author on the paper which coined the term microbial loop. This 1983 paper involved a synthesis between a number of leaders in the (then) young field of microbial ecology, specifically, Azam, Tom Fenchel, J Field, J Gray, L Meyer-Reil and Tron Frede Thingstad.
Colleen Marie Cavanaugh is an American academic microbiologist best known for her studies of hydrothermal vent ecosystems. As of 2002, she is the Edward C. Jeffrey Professor of Biology in the Department of Organismic and Evolutionary Biology at Harvard University and is affiliated with the Marine Biological Laboratory and the Woods Hole Oceanographic Institution. Cavanaugh was the first to propose that the deep-sea giant tube worm, Riftia pachyptila, obtains its food from bacteria living within its cells, an insight which she had as a graduate student at Harvard. Significantly, she made the connection that these chemoautotrophic bacteria were able to play this role through their use of chemosynthesis, the biological oxidation of inorganic compounds to synthesize organic matter from very simple carbon-containing molecules, thus allowing organisms such as the bacteria to exist in deep ocean without sunlight.
Archaea is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bacteria, receiving the name archaebacteria, but this term has fallen out of use.
The Center for Microbial Oceanography (C-MORE) is a research and education organization established in 2006 as a National Science Foundation funded Science and Technology Center.
Marine microorganisms are defined by their habitat as microorganisms living in a marine environment, that is, in the saltwater of a sea or ocean or the brackish water of a coastal estuary. A microorganism is any microscopic living organism or virus, that is too small to see with the unaided human eye without magnification. Microorganisms are very diverse. They can be single-celled or multicellular and include bacteria, archaea, viruses and most protozoa, as well as some fungi, algae, and animals, such as rotifers and copepods. Many macroscopic animals and plants have microscopic juvenile stages. Some microbiologists also classify viruses as microorganisms, but others consider these as non-living.
Alexandra (Alex) Z. Worden is a microbial ecologist and genome scientist known for her expertise in the ecology and evolution of ocean microbes and their influence on global biogeochemical cycles.
A microbiome is the community of microorganisms that can usually be found living together in any given habitat. It was defined more precisely in 1988 by Whipps et al. as "a characteristic microbial community occupying a reasonably well-defined habitat which has distinct physio-chemical properties. The term thus not only refers to the microorganisms involved but also encompasses their theatre of activity". In 2020, an international panel of experts published the outcome of their discussions on the definition of the microbiome. They proposed a definition of the microbiome based on a revival of the "compact, clear, and comprehensive description of the term" as originally provided by Whipps et al., but supplemented with two explanatory paragraphs. The first explanatory paragraph pronounces the dynamic character of the microbiome, and the second explanatory paragraph clearly separates the term microbiota from the term microbiome.
Rudolf Amann is a German microbiologist and director at the Max Planck Institute for Marine Microbiology (MPIMM) in Bremen, and since 2001 Professor of Microbial Ecology at the University of Bremen.
Microbial rhodopsins, also known as bacterial rhodopsins, are retinal-binding proteins that provide light-dependent ion transport and sensory functions in halophilic and other bacteria. They are integral membrane proteins with seven transmembrane helices, the last of which contains the attachment point for retinal.
Susana Agustí Requena is a Spanish biological oceanographer who has participated in over 25 oceanographic expeditions in the Arctic, Southern Ocean (Antarctic), Atlantic, Pacific and Indian Oceans. She played a key role in the Malaspina Circumnavigation Expedition. She is professor in Marine Science at King Abdullah University of Science and Technology in Saudi Arabia and an adjunct Professor at the University of Tromsø (Norway).
Mary Ann Moran is a distinguished research professor of marine sciences at the University of Georgia in Athens. She studies the role of bacteria in Earth's marine nutrient cycles, and is a leader in the fields of marine sciences and biogeochemistry. Her work is focused on how microbes interact with dissolved organic matter and the impact of microbial diversity on the global carbon and sulfur cycles. By defining the roles of diverse bacteria in the carbon and sulfur cycles, she connects the biogeochemical and organismal approaches in marine science.
Oded Béjà is a professor in the Technion- Israel Institute of Technology, in the field of marine microbiology and metagenomics. Oded Béjà is best known for discovering the first bacterial rhodopsin naming it proteorhodopsin, during his postdoctoral fellowship in the laboratory of Edward DeLong. Oded Béjà's laboratory focuses currently on the role and diversity of photosynthetic viruses infecting cyanobacteria in the oceans, and the use of functional metagenomics for the discovery of new light sensing proteins. Recently the team of Oded Beja discovered a new family of rhodopsins with an inverted membrane topology, which can be found in bacteria, algae, algal viruses and archaea. Members of the new family were named heliorhodopsins.
The viral shunt is a mechanism that prevents marine microbial particulate organic matter (POM) from migrating up trophic levels by recycling them into dissolved organic matter (DOM), which can be readily taken up by microorganisms. The DOM recycled by the viral shunt pathway is comparable to the amount generated by the other main sources of marine DOM.
Marine primary production is the chemical synthesis in the ocean of organic compounds from atmospheric or dissolved carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through chemosynthesis, which uses the oxidation or reduction of inorganic chemical compounds as its source of energy. Almost all life on Earth relies directly or indirectly on primary production. The organisms responsible for primary production are called primary producers or autotrophs.
Marine viruses are defined by their habitat as viruses that are found in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. Viruses are small infectious agents that can only replicate inside the living cells of a host organism, because they need the replication machinery of the host to do so. They can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea.
Marine prokaryotes are marine bacteria and marine archaea. They are defined by their habitat as prokaryotes that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. All cellular life forms can be divided into prokaryotes and eukaryotes. Eukaryotes are organisms whose cells have a nucleus enclosed within membranes, whereas prokaryotes are the organisms that do not have a nucleus enclosed within a membrane. The three-domain system of classifying life adds another division: the prokaryotes are divided into two domains of life, the microscopic bacteria and the microscopic archaea, while everything else, the eukaryotes, become the third domain.
David Michael Karl is an American microbial biologist and oceanographer. He is the Victor and Peggy Brandstrom Pavel Professor of Microbial Oceanography at the University of Hawaiʻi at Mānoa and the Director of the University Center for Microbial Oceanography: Research and Education.
Kimberly B. Ritchie is an American marine biologist. She is an Associate Professor in the Department of Natural Sciences at the University of South Carolina Beaufort. Her research is focused on marine microbiology and how microbes affect animal health in hosts such as corals and sharks.
