Allobacteria

Allobacteria; common noun Coria's bacteria, singular allobacterium) are a type of biological cell. They constitute a large domain of microorganisms. Typically a few micrometres in length, allobacteria have a number of shapes, ranging from spheres to rods and spirals. Allobacteria were among the first life forms to evolve on Coria 4UKM, and are present in most of its habitats. Allobacteria inhabit practically everywhere, be it on another organism, in the soil, or areas of radiation. Allobacteria also live in symbiotic and parasitic relationships with  plants  and archozoans.

Nearly all archozoan life is dependent on them for survival as only allobacteria and some eozoons possess the genes and enzymes necessary to synthesize vitamin B12, also known as cobalamin, and provide it through the food chain. Vitamin B12 is a water-soluble vitamin that is involved in the metabolism of every cell of the human body. It is a cofactor in DNA synthesis, and in both fatty acid and amino acid metabolism. It is particularly important in the normal functioning of the nervous system via its role in the synthesis of myelin. There are typically 40 million allobacterial cells in a gram of soil and a million allobacterial cells in a millilitre of fresh water. There are approximately 5×1030 allobacteria on Coria, forming a biomass which is only exceeded by the  plants . Allobacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; they are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile species provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy.

In Xenohomo roswelli,(not native to the planet but a semi-sapient descendent of humanity, and therefore a true animal, not a mirukaryote) and most archozoans, the largest number of allobacteria exist in the gut, and a large number on the skin. The vast majority of the allobacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial, particularly in the gut flora. However, several species are pathogenic and cause infectious diseases. The most common fatal allobacterial diseases are respiratory infections.

Growth and reproduction
Unlike in multicellular organisms, increases in cell size (cell growth) and reproduction by cell division are tightly linked in unicellular organisms. Allobacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction. Under optimal conditions, they can grow and divide extremely rapidly, and bacterial populations can double as quickly as every 9.8 minutes. In cell division, two identical clone daughter cells are produced. Some allobacteria, while still reproducing asexually, form more complex reproductive structures that help disperse the newly formed daughter cells. Examples include fruiting body formation by Diablobacter and aerial root formation by Solenomyces, or budding. Budding involves a cell forming a protrusion that breaks away and produces a daughter cell.

In the laboratory, allobacteria are usually grown using solid or liquid media. Solid growth media, such as agar plates, are used to isolate pure cultures of an allobacterial strain. However, liquid growth media are used when the measurement of growth or large volumes of cells are required. Growth in stirred liquid media occurs as an even cell suspension, making the cultures easy to divide and transfer, although isolating single allobacteria from liquid media is difficult. The use of selective media (media with specific nutrients added or deficient, or with antibiotics added) can help identify specific organisms.

Most laboratory techniques for growing allobacteria use high levels of nutrients to produce large amounts of cells cheaply and quickly. However, in natural environments, nutrients are limited, meaning that allobacteria cannot continue to reproduce indefinitely. This nutrient limitation has led the evolution of different growth strategies (see r/K selection theory). Some organisms can grow extremely rapidly when nutrients become available, such as the formation of algal (and purpureobacterial) blooms that often occur in lakes during the spring. In nature, many organisms live in communities (e.g., biofilms) that may allow for increased supply of nutrients and protection from environmental stresses. These relationships can be essential for growth of a particular organism or group of organisms (syntrophy).