Trichoderma longibrachiatum Rifai, Mycol. Pap. 116: 42 (1969) A - pustules, B, D - conidiophores; C - shape of conidia (not scaled). Image credits: Samuels, G.J., Chaverri, P., Farr, D.F., & McCray, E.B. Trichoderma Online, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved February 22, 2012.

The cosmopolitan filamentous fungus Trichoderma longibrachiatum is the genetically distinct agamospecies belonging to the Longibrachiatum clade of Trichoderma (teleomorph Hypocrea, Ascomycota, Dikarya). T. longibrachiatum is usually a common component of Trichoderma communities isolated from soil and other environments such as mushrooms and food rotting fungi, marine and soil animals and dead wood. It appears to be abundant in indoor environments such as water-damaged buildings or mushroom farms infected by green mould disease. Consequently, T. longibrachiatum has also been detected in sputum and sinus of healthy humans. More importantly, it is (together with the closely related Hypocrea orientalis) the only Trichoderma spp. that is able to attack immunocompromised humans. It was shown that this species is able to control plant-pathogenic nematodes in soil.

T. longibrachiatum is phylogenetically very close to Trichoderma reesei(teleomorph Hypocrea jecorina), and has – like the latter – been used as a source for production of plant biomass degrading enzymes. Notably, it has been confused with T. reesei between 1984 and 1996, and several cellulase preparations from T. reesei are still sold under the name “T. longibrachiatum”. Its genome sequence and comparative analysis with other Trichoderma species is therefore expected to yield understanding what made an environmental opportunistic fungus an opportunistic human pathogen, and to complement the genetic resources for industrial enzyme production.