Fungi examples Flashcards
humongous fungi
Amillaria species.
true pathogen
biomass under soil and attacks roots of tree.
100tonnes of biomass
over15000 years old.
Yeast
Saccharomyces cerevisae (balers yeast)
Schizosaccharomyces pombe (a model laboratory organism)
agent that causes thrush
Candida albicans
Ascomycetes examples
‘Saccharomyces cerevisiae’ was the first eukaryotic genome to be sequenced and work performed using ‘Neurospora crassa’ was awarded the Noble prize for the proposal of “one gene one protein” hypothesis
plant pathogens in this group; for example, ‘Claviceps’ and ‘Erysiphie’ species.
basidiomycetes examples
lignin decomposes (Serpula lacrymans is dry rot). They are important food sources in the form of mushrooms
(Agaricus bisporus is the common mushroom found in the UK).
They are also important crop pathogens including Puccinia species which causes rust disease – the brown marks are necrosis of cells which gives the appearance of rust.
deuteromycetes examples
important food spoilers (Aspergillus flavus) and the industrial workhorse, ‘Aspergillus niger’ for the production of medicines and foodstuffs
What is aflatoxin produced by
Aspergillus flavus) to protect its food source
true pathogen disease and pathogen example
Histoplasmosis
pathogen is Histoplasma capsulatum
Most common in the USA and leads to less than 50 deaths per year. In the filamentous form, it appears as a brown colony on the growth plate and at 37 Celsius it converts to a white waxy yeast form. The spores (from the filamentous form) have small appendages on them that help them to be dispersed by the wind.
The infection cycle starts mainly from bird droppings, the spores are easily inhaled and the infection is local to the lung. In the lung, the spore grows as a yeast which then forms endospores and the cycle of infection continues. In most cases the phagocytes are able to limit and remove the infection however, if the infection spreads it can affect the heart lung and liver tissues and become fatal.
True pathogen example and pathogen alkaline example.
coccidiodiomycosis caused by Coccidioides immitis.
It is most common in alkaline soils of the southwest of the USA. Most cases are asymptomatic but it can lead to fever in approximately 40% of infections. It produces arthrospores and these are the infectious agent. In the body, they grow as sporangia and release spores in the lung and leads to infection which is usually cleared by the immune system.
If the host is immunocompromised then it can cause complication leading to meningitis and rashes. However, it is generally well controlled by the host cell.
Examples of opportunistic pathogen.
Aspergillus fumigatus, they are isolated from compost heaps which are very warm and of course the host is running at high temperature and Aspergillus fumigatus is adapted to that temperature from its natural environment. They can cause a range of severity of infection up to chronic systemic infection and the prognosis (likely course uncertain) in this case is very poor! The mortality rate is high. Causes aspergillosis.
produces mycelium in the lung called an aspergilloma.
Candida albicans that causes candidiasis or thrush(common in babies).
(20% of us carry it as a commensal organism)
dermatophytes example
ring worm caused by the Trichophyta species which also cause athletes foot
pathogens of immature tissue example
Pythium and Phytothphora genera which are actually oomycetes – they were originally classed as fungi but with modern molecular techniques they are more closely related to algae and have been reclassified as protists). They aggressively invade the roots tips (the new cells have weaker cell walls and are the site of infection) and are associated with water-logged soils and they are known as damping-off diseases. The infection cause necrosis of the root tip and stunt growth
necrotrophic pathogen of mature tissue example
necrotrophic pathogen of mature tissue is the honey fungus (Amillaria mellea). It is a major root pathogen of broad leaved trees. It uses rhizomorphs to attack the plant and target the phloem tissue
biotrophic pathogen of mature tissue example.
Ersyphie graminis and Puccinia graminis that infect wheat species
maintain the host cell viability – they do not kill the plant but compromise the growth of the plant. They have limited tissue invasion and the infection does not evoke a resistance mechanism (i.e. the plant is not aware of the infection!)
Erysiphie, the infection is in the epidermis of the leave and they produce these haustoria in these cells. In both cases the infection hyphae “punch” a hole in the cell wall of the infected cell!
controlling insect pests examples
Mycotal (for whitefly and thrips) and Vertalec (for aphids) and they are different formulations of the same fungal species spores.
fungus is Verticllium lecanii and the difference between the formulations is the addition of oil to Vertalec, which enables more efficient infection of aphids
can produce spores in liquid fermenter
spores are produced at the ends of specialised hyphal cells
germinate in high relative humidity and at a strict temperature range making suitable for glasshouses only.
