Saprotrophic nutrition or lysotrophic nutrition is a process of

chemoheterotrophic A Chemotroph is an organism that obtains energy by the oxidation of electron donors in their environments. These molecules can be organic ( chemoorganotrophs) or inorganic (chemolithotrophs). The chemotroph designation is in contrast to phototro ...

extracellular digestion Extracellular phototropic digestion is a process in which saprobionts feed by secreting enzymes through the cell membrane onto the food. The enzymes catalyze the digestion of the food ie diffusion, transport, osmotrophy or phagocytosis. Since dige ...

involved in the processing of decayed (dead or waste)

organic matter Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have c ...

. It occurs in saprotrophs, and is most often associated with

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

(for example ''

Mucor ''Mucor'' is a microbial genus of approximately 40 species of molds in the family Mucoraceae. Species are commonly found in soil, digestive systems, plant surfaces, some cheeses like Tomme de Savoie, rotten vegetable matter and iron oxide re ...

'') and soil

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

. Saprotrophic microscopic fungi are sometimes called saprobes; saprotrophic plants or bacterial flora are called saprophytes ( sapro- 'rotten material' + -phyte 'plant'), although it is now believed that all plants previously thought to be saprotrophic are in fact parasites of microscopic fungi or other plants. The process is most often facilitated through the

active transport In cellular biology, ''active transport'' is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellul ...

of such materials through endocytosis within the internal mycelium and its constituent hyphae. states the purpose of saprotrophs and their internal nutrition, as well as the main two types of fungi that are most often referred to, as well as describes, visually, the process of saprotrophic nutrition through a diagram of hyphae, referring to the Rhizobium on damp, stale whole-meal bread or rotting fruit. Various word roots relating to decayed matter (''detritus'', '' sapro-''), eating and nutrition ('' -vore'', '' -phage''), and plants or life forms ('' -phyte'', ''-obe'') produce various terms, such as detritivore, detritophage, saprotroph, saprophyte, saprophage, and saprobe; their meanings overlap, although technical distinctions (based on physiologic mechanisms) narrow the

senses A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of stimuli. (For example, in the human body, the brain which is part of the central nervous system rec ...

. For example,

usage The usage of a language is the ways in which its written and spoken variations are routinely employed by its speakers; that is, it refers to "the collective habits of a language's native speakers", as opposed to idealized models of how a language ...

distinctions can be made based on macroscopic swallowing of detritus (as an

earthworm An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. Th ...

does) versus microscopic

lysis Lysis ( ) is the breaking down of the membrane of a cell, often by viral, enzymic, or osmotic (that is, "lytic" ) mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a ''lysate''. In molecular bio ...

of detritus (as a

mushroom A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is t ...

does).

Process

As matter decomposes within a medium in which a saprotroph is residing, the saprotroph breaks such matter down into its composites. *

Protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s are broken down into their

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...

composites through the breaking of peptide bonds by

protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...

s., fig 14.16—Diagram detailing the re-absorption of substrates within the hypha. *

Lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...

s are broken down into

fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, ...

s and

glycerol Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...

by lipases. * Starch is broken down into pieces of simple disaccharides by

amylase An amylase () is an enzyme that catalyses the hydrolysis of starch (Latin ') into sugars. Amylase is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Foods that contain large amounts of ...

s. *

Cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell w ...

, a major portion of plant cells, and therefore a major constituent of decaying matter is broken down into glucose These products are re-absorbed into the hypha through the cell wall by endocytosis and passed on throughout the mycelium complex. This facilitates the passage of such materials throughout the organism and allows for growth and, if necessary, repair.

Conditions

In order for a saprotrophic organism to facilitate optimal growth and repair, favourable conditions and nutrients must be present., fig 14.17—A diagram explaining the optimal conditions needed for successful growth and repair. Optimal conditions refers to several conditions which optimise the growth of saprotrophic organisms, such as; # Presence of water: 80–90% of the mass of the fungi is composed of water, and the fungi require excess water for absorption due to the evaporation of internally retained water. # Presence of oxygen: Very few saprotrophic organisms can endure anaerobic conditions as evidenced by their growth above media such as water or soil. # Neutral-acidic pH: The condition of neutral or mildly acidic conditions under pH 7 are required. # Low-medium temperature: The majority of saprotrophic organisms require temperatures between 1 °C and 35 °C (33.8 °F and 95 °F), with optimum growth occurring at 25 °C (77 °F). The majority of nutrients taken in by such organisms must be able to provide carbon, proteins, vitamins and in some cases,

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

s. Due to the carbon composition of the majority of organisms, dead and organic matter provide rich sources of disaccharides and polysaccharides such as maltose and starch, and of the monosaccharide

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

. In terms of nitrogen-rich sources, saprotrophs require combined protein for the creation of proteins, which is facilitated by the absorption of amino acids, and usually taken from rich soil. Although both ions and vitamins are rare, thiamine or ions such as potassium, phosphorus, and magnesium aid the growth of the mycelium.

Process

Conditions

See also

References

Further reading