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Photosynthesis is a biological process used by many cellular organisms to convert light energy into chemical energy, which is stored in organic compounds that can later be metabolized through cellular respiration to fuel the organism's activities. The term usually refers to oxygenic photosynthesis, where oxygen is produced as a byproduct and some of the chemical energy produced is stored in carbohydrate molecules such as sugars, starch, glycogen and cellulose, which are synthesized from endergonic reaction of carbon dioxide with water. Most plants, algae and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies most of the biological energy necessary for complex life on Earth.
Cyanobacteria, also called Cyanobacteriota or Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name cyanobacteria refers to their color, which similarly forms the basis of cyanobacteria's common name, blue-green algae, although they are not usually scientifically classified as algae. They appear to have originated in a freshwater or terrestrial environment. Sericytochromatia, the proposed name of the paraphyletic and most basal group, is the ancestor of both the non-photosynthetic group Melainabacteria and the photosynthetic cyanobacteria, also called Oxyphotobacteria.
Photorespiration (also known as the oxidative photosynthetic carbon cycle or C2 cycle) refers to a process in plant metabolism where the enzyme RuBisCO oxygenates RuBP, wasting some of the energy produced by photosynthesis. The desired reaction is the addition of carbon dioxide to RuBP (carboxylation), a key step in the Calvin–Benson cycle, but approximately 25% of reactions by RuBisCO instead add oxygen to RuBP (oxygenation), creating a product that cannot be used within the Calvin–Benson cycle. This process lowers the efficiency of photosynthesis, potentially lowering photosynthetic output by 25% in C3 plants. Photorespiration involves a complex network of enzyme reactions that exchange metabolites between chloroplasts, leaf peroxisomes and mitochondria.
Chlamydomonas reinhardtii is a single-cell green alga about 10 micrometres in diameter that swims with two flagella. It has a cell wall made of hydroxyproline-rich glycoproteins, a large cup-shaped chloroplast, a large pyrenoid, and an eyespot that senses light.
Diazotrophs are bacteria and archaea that fix gaseous nitrogen in the atmosphere into a more usable form such as ammonia.
Microalgae or microphytes are microscopic algae invisible to the naked eye. They are phytoplankton typically found in freshwater and marine systems, living in both the water column and sediment. They are unicellular species which exist individually, or in chains or groups. Depending on the species, their sizes can range from a few micrometers (μm) to a few hundred micrometers. Unlike higher plants, microalgae do not have roots, stems, or leaves. They are specially adapted to an environment dominated by viscous forces.
Phototrophs are organisms that carry out photon capture to produce complex organic compounds and acquire energy. They use the energy from light to carry out various cellular metabolic processes. It is a common misconception that phototrophs are obligatorily photosynthetic. Many, but not all, phototrophs often photosynthesize: they anabolically convert carbon dioxide into organic material to be utilized structurally, functionally, or as a source for later catabolic processes. All phototrophs either use electron transport chains or direct proton pumping to establish an electrochemical gradient which is utilized by ATP synthase, to provide the molecular energy currency for the cell. Phototrophs can be either autotrophs or heterotrophs. If their electron and hydrogen donors are inorganic compounds they can be also called lithotrophs, and so, some photoautotrophs are also called photolithoautotrophs. Examples of phototroph organisms are Rhodobacter capsulatus, Chromatium, and Chlorobium.
Artificial photosynthesis is a chemical process that biomimics the natural process of photosynthesis to convert sunlight, water, and carbon dioxide into carbohydrates and oxygen. The term artificial photosynthesis is commonly used to refer to any scheme for capturing and storing the energy from sunlight in the chemical bonds of a fuel. Photocatalytic water splitting converts water into hydrogen and oxygen and is a major research topic of artificial photosynthesis. Light-driven carbon dioxide reduction is another process studied that replicates natural carbon fixation.
Algaculture is a form of aquaculture involving the farming of species of algae.
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.
Hydrogen production is the family of industrial methods for generating hydrogen gas. There are four main sources for the commercial production of hydrogen: natural gas, oil, coal, and electrolysis of water; which account for 48%, 30%, 18% and 4% of the world's hydrogen production respectively. Fossil fuels are the dominant source of industrial hydrogen. As of 2020, the majority of hydrogen (~95%) is produced by steam reforming of natural gas and other light hydrocarbons, partial oxidation of heavier hydrocarbons, and coal gasification. Other methods of hydrogen production include biomass gasification and methane pyrolysis. Methane pyrolysis and water electrolysis can use any source of electricity including renewable energy.
Biohydrogen is H2 that is produced biologically. Interest is high in this technology because H2 is a clean fuel and can be readily produced from certain kinds of biomass, including biological waste. Furthermore some photosynthetic microorganisms are capable to produce H2 directly from water splitting using light as energy source.
The Micro-Ecological Life Support System Alternative (MELiSSA) is a European Space Agency (ESA) initiative with the aim to develop the technology for a future regenerative life support system for long-term human space missions. Initiated in 1989, the design is inspired by a terrestrial ecosystem. As of 2023, MELiSSA is a consortium made up of 30 organisations across Europe.
Scenedesmus is a genus of green algae, in the class Chlorophyceae. They are colonial and non-motile. They are one of the most common components of phytoplankton in freshwater habitats worldwide.
Phototrophic biofilms are microbial communities generally comprising both phototrophic microorganisms, which use light as their energy source, and chemoheterotrophs. Thick laminated multilayered phototrophic biofilms are usually referred to as microbial mats or phototrophic mats. These organisms, which can be prokaryotic or eukaryotic organisms like bacteria, cyanobacteria, fungi, and microalgae, make up diverse microbial communities that are affixed in a mucous matrix, or film. These biofilms occur on contact surfaces in a range of terrestrial and aquatic environments. The formation of biofilms is a complex process and is dependent upon the availability of light as well as the relationships between the microorganisms. Biofilms serve a variety of roles in aquatic, terrestrial, and extreme environments; these roles include functions which are both beneficial and detrimental to the environment. In addition to these natural roles, phototrophic biofilms have also been adapted for applications such as crop production and protection, bioremediation, and wastewater treatment.
An autotroph is an organism that produces complex organic compounds using carbon from simple substances such as carbon dioxide, generally using energy from light (photosynthesis) or inorganic chemical reactions (chemosynthesis). They convert an abiotic source of energy into energy stored in organic compounds, which can be used by other organisms. Autotrophs do not need a living source of carbon or energy and are the producers in a food chain, such as plants on land or algae in water. Autotrophs can reduce carbon dioxide to make organic compounds for biosynthesis and as stored chemical fuel. Most autotrophs use water as the reducing agent, but some can use other hydrogen compounds such as hydrogen sulfide.
A soda lake or alkaline lake is a lake on the strongly alkaline side of neutrality, typically with a pH value between 9 and 12. They are characterized by high concentrations of carbonate salts, typically sodium carbonate, giving rise to their alkalinity. In addition, many soda lakes also contain high concentrations of sodium chloride and other dissolved salts, making them saline or hypersaline lakes as well. High pH and salinity often coincide, because of how soda lakes develop. The resulting hypersaline and highly alkalic soda lakes are considered some of the most extreme aquatic environments on Earth.
Microalgae or microscopic algae grow in either marine or freshwater systems. They are primary producers in the oceans that convert water and carbon dioxide to biomass and oxygen in the presence of sunlight.
Cyanothece is a genus of unicellular, diazotrophic, oxygenic photosynthesizing cyanobacteria.
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.
References
- 1 2 "Anastasios Melis - Department of Plant & Microbial Biology". pmb.berkeley.edu. Retrieved 2015-06-15.
- ↑ Roberts, Paul (2004). The End of Oil. Great Britain: Bloomsbury. pp. 188–198. ISBN 0747570752.
- ↑ "A REPORT ON UNIVERSITY OF CALIFORNIA RESEARCH FOR THE DEPARTMENT OF ENERGY" (PDF). www.ucop.edu (Archived). Office of Research, UC Office of the President. 2000. Archived from the original (PDF) on February 12, 2012. Retrieved 2015-06-15.
- ↑ Gartner, John (19 August 2002). "Algae: Power Plant of the Future?". WIRED. Retrieved 2015-06-15.
- ↑ Melis, Anastasios. "CURRICULUM VITAE ANASTASIOS (Tasios) MELIS, Ph.D" (PDF). pmb.berkeley.edu. Retrieved 2015-06-15.