Trichoderma is a genus of mold found in many different parts of the world. These molds are ubiquitous in a wide variety of different environments. They have been known to commonly show up in soil, forests, wood, and paper.
Humans find interest in the molds ability as a beneficial symbiotic partner for plants. This is particularly the case crops, though it should be noted that members of this genus do have some other uses and benefits for humans. These molds typically grow on the roots of living plants. Once there they promote abundant root growth, allowing them to have plenty of roots to grow on. Trichoderma also eliminate other fungi so that they do not have to struggle with potential competitors. This is beneficial to the plants they colonize. Some farmers and gardeners even add Trichoderma to their soil before planting for its symbiotic benefits. Trichoderma is commonly cultivated on an industrial scale in several industries because of its potential uses.
Trichoderma form colonies of mold that start out transparent, becoming white to yellowish over time. When the mold matures and starts to produce spores, it darkens becoming green to gray. Some species of Trichoderma have a distinctive sweet scent which is often compared to that of coconuts. Colonies are fast growing, and typically mature within five days. Trichoderma molds tend to prefer moderate temperatures, which allows them to thrive in a variety of climates. Several species also have teleomorphs or sexually-reproducing forms in the genus Hypocrea.
In an indoor environment, Trichoderma can be commonly found on gypsum board, water saturated wood, wallpaper, carpet and mattress dust, paint, and air-conditioning filters. A common house mold, Trichoderma longibrachiatum, produces small toxic peptides containing amino acids not found in common proteins called trilongins. They become toxic to humans due to being absorbed into cells as well as the production of nano-channels that obstruct vital ion channels that ferry potassium and sodium ions across the cell membrane. This affects the cells action potential profile leading to conduction defects. Trilongins are highly resistant to heat and antimicrobials making primary prevention the best management option. Human infection by a species of Trichoderma is limited to individuals with severely weakened immune systems. However, some species such as T. harzianum and T. viride are producers of potent mycotoxins. Generally, Trichoderma species require a higher level of water activity when compared to some other indoor molds, such as Penicillium or Aspergillus.