Tron Frede Thingstad (born 1946) is a Norwegian scientist. Professor Thingstad is leading a research group on marine microbiology at the Department of Biology, University of Bergen. His work has facilitated understanding the role of microbes in marine ecosystems, including the microbial loop.
In 2009, Thingstad was awarded the prestigious ERC Advanced Investigators Grant to the project "MINOS" (MIcrobial Network OrganiSation), which is focused on microbial networks in the ocean.In 2010, Thingstad received the "Prize for Outstanding Research" of the Norwegian Research Council (informally known as the "Møbius Prize"). According to the jury, his research "has contributed to deeper understanding of topics within marine microbiology, biodiversity, climate research, and ocean acidification". He is also a member of the Norwegian Academy of Science and Letters.
Aeroplankton are tiny lifeforms that float and drift in the air, carried by wind. Most of the living things that make up aeroplankton are very small to microscopic in size, and many can be difficult to identify because of their tiny size. Scientists collect them for study in traps and sweep nets from aircraft, kites or balloons.
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.
The sea surface microlayer (SML) is the boundary interface between the atmosphere and ocean, covering about 70% of the Earth’s surface. With an operationally defined thickness between 1 and 1000 µm, the SML has physicochemical and biological properties that are measurably distinct from underlying waters. Recent studies now indicate that the SML covers the ocean to a significant extent, and evidence shows that it is an aggregate-enriched biofilm environment with distinct microbial communities. Because of its unique position at the air-sea interface, the SML is central to a range of global biogeochemical and climate-related processes.
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.
Aerobic anoxygenic phototrophic bacteria (AAPBs) are alphaproteobacteria and gammaproteobacteria that are obligate aerobes that capture energy from light by anoxygenic photosynthesis. Anoxygenic photosynthesis is the phototrophic process where light energy is captured and stored as ATP. The production of oxygen is non-existent and, therefore, water is not used as an electron donor. They are widely distributed marine plankton that may constitute over 10% of the open ocean microbial community. They can be particularly abundant in oligotrophic conditions where they were found to be 24% of the community. Aerobic anoxygenic phototrophic bacteria are photoheterotrophic (phototroph)microbes that exist in a variety of aquatic environments. Photoheterotrophs, are heterotrophic organisms that use light to produce energy, but are unable to utilize carbon dioxide as their primary carbon source. Most are obligately aerobic, meaning they require oxygen to grow. One remarkable aspect of these novel bacteria is that they, unlike other similar bacteria, are unable to utilize BChl (bacteriochlorophyll) for anaerobic growth. The only photosynthetic pigment that exists in AAPB is BChl a. Anaerobic phototrophic bacteria, on the contrary, can contain numerous species of photosynthetic pigments like bacteriochlorophyll a, b, c, d, e, f, etc. There is still a large void in the areas regarding the abundance and genetic diversity of the AAPB, as well as the environmental variables that regulate these properties.
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 biologically active entities such as viruses and viroids as microorganisms, but others consider these as non-living.
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.
A holobiont is an assemblage of a host and the many other species living in or around it, which together form a discrete ecological unit, though there is controversy over this discreteness. The components of a holobiont are individual species or bionts, while the combined genome of all bionts is the hologenome. The holobiont concept was initially introduced by the German theoretical biologist Adolf Meyer-Abich in 1943, and then apparently independently by Dr. Lynn Margulis in her 1991 book Symbiosis as a Source of Evolutionary Innovation. The concept has evolved since the original formulations. Holobionts include the host, virome, microbiome, and any other organisms which contribute in some way to the functioning of the whole. Well-studied holobionts include reef-building corals and humans.
Corina Brussaard is a leading scientist for Antarctic viral ecology working for the Royal Institute of Sea Research (NIOZ) and is a Special Professor of Viral Ecology at the Institute for Biodiversity and Ecosystem Dynamics of the University of Amsterdam (UvA).
The "Kill the Winner" hypothesis (KTW) is a model of population growth involving prokaryotes, viruses and protozoans that links trophic interactions to biogeochemistry. It is based on the concept of prokaryotes taking one of two reactions to limited resources: "competition", that is, that priority directed to growth of the population, or a "winner"; and "defense", where the resources are directed to survival against attacks. It is then assumed that the better strategy for a phage, or virus which attacks prokaryotes, is to concentrate on the "winner", the most active population. This tends to moderate the relative populations of the prokaryotes, rather than the "winner take all". The model is related to the Lotka–Volterra equations. Current understanding on KTW stems from our knowledge of lytic viruses and their host populations.
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.
Bacterioplankton counting is the estimation of the abundance of bacterioplankton in a specific body of water, which is useful information to marine microbiologists. Various counting methodologies have been developed over the years to determine the number present in the water being observed. Methods used for counting bacterioplankton include epifluorescence microscopy, flow cytometry, measures of productivity through frequency of dividing cells (FDC), thymidine incorporation, and leucine incorporation.
Sea Ice Microbial Communities (SIMCO) refer to groups of microorganisms living within and at the interfaces of sea ice at the poles. The ice matrix they inhabit has strong vertical gradients of salinity, light, temperature and nutrients. Sea ice chemistry is most influenced by the salinity of the brine which affects the pH and the concentration of dissolved nutrients and gases. The brine formed during the melting sea ice creates pores and channels in the sea ice in which these microbes can live. As a result of these gradients and dynamic conditions, a higher abundance of microbes are found in the lower layer of the ice, although some are found in the middle and upper layers. Despite this extreme variability in environmental conditions, the taxonomical community composition tends to remain consistent throughout the year, until the ice melts.
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.
Compared to terrestrial environments, marine environments have biomass pyramids which are inverted at the base. In particular, the biomass of consumers is larger than the biomass of primary producers. This happens because the ocean's primary producers are tiny phytoplankton which grow and reproduce rapidly, so a small mass can have a fast rate of primary production. In contrast, many significant terrestrial primary producers, such as mature forests, grow and reproduce slowly, so a much larger mass is needed to achieve the same rate of primary production.
All animals on Earth form associations with microorganisms, including protists, bacteria, archaea, fungi, and viruses. In the ocean, animal–microbial relationships were historically explored in single host–symbiont systems. However, new explorations into the diversity of marine microorganisms associating with diverse marine animal hosts is moving the field into studies that address interactions between the animal host and a more multi-member microbiome. The potential for microbiomes to influence the health, physiology, behavior, and ecology of marine animals could alter current understandings of how marine animals adapt to change, and especially the growing climate-related and anthropogenic-induced changes already impacting the ocean environment.
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.
Jennifer B. H. Martiny is an American ecologist who is a Professor at the University of California, Irvine. Her research considers microbial diversity in marine and terrestrial ecosystems. In 2020 she was elected a Fellow of the American Association for the Advancement of Science.
The holobiont concept is a renewed paradigm in biology that can help to describe and understand complex systems, like the host-microbe interactions that play crucial roles in marine ecosystems. However, there is still little understanding of the mechanisms that govern these relationships, the evolutionary processes that shape them and their ecological consequences. The holobiont concept posits that a host and its associated microbiota with which it interacts, form a holobiont, and have to be studied together as a coherent biological and functional unit to understand its biology, ecology, and evolution.