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Learning objectives

  • Explain why the study of fungi such as yeast and molds is within the discipline of microbiology
  • Describe the unique characteristics of fungi
  • Describe examples of asexual and sexual reproduction of fungi
  • Compare the major groups of fungi in this chapter, and give examples of each
  • Identify examples of the primary causes of infections due to yeasts and molds
  • Identify examples of toxin-producing fungi
  • Classify fungal organisms according to major groups

The fungi comprise a diverse group of organisms that are heterotrophic and typically saprozoic. In addition to the well-known macroscopic fungi (such as mushrooms and molds), many unicellular yeasts and spores of macroscopic fungi are microscopic. For this reason, fungi are included within the field of microbiology.

Fungi are important to humans in a variety of ways. Both microscopic and macroscopic fungi have medical relevance, with some pathogenic species that can cause mycoses (illnesses caused by fungi). Some pathogenic fungi are opportunistic, meaning that they mainly cause infections when the host’s immune defenses are compromised and do not normally cause illness in healthy individuals. Fungi are important in other ways. They act as decomposers in the environment, and they are critical for the production of certain foods such as cheeses. Fungi are also major sources of antibiotics, such as penicillin from the fungus Penicillium .

Characteristics of fungi

Fungi have well-defined characteristics that set them apart from other organisms. Most multicellular fungal bodies, commonly called molds , are made up of filaments called hyphae . Hyphae can form a tangled network called a mycelium and form the thallus (body) of fleshy fungi. Hyphae that have walls between the cells are called septate hyphae ; hyphae that lack walls and cell membranes between the cells are called nonseptate or coenocytic hyphae ). ( [link] ).

Molds can have septate hyphae - long strands with cell walls separating the nuclei. Or they can have coenocytic (nonseptate) hyphae - long strands with no cell wall separating the nuclei. Or they can have pseudohyphae which look like chains of cells with small clusters at intervals
Multicellular fungi (molds) form hyphae, which may be septate or nonseptate. Unicellular fungi (yeasts) cells form pseudohyphae from individual yeast cells.

In contrast to molds, yeasts are unicellular fungi. The budding yeasts reproduce asexually by budding off a smaller daughter cell; the resulting cells may sometimes stick together as a short chain or pseudohypha ( [link] ). Candida albicans is a common yeast that forms pseudohyphae; it is associated with various infections in humans, including vaginal yeast infections, oral thrush, and candidiasis of the skin.

Some fungi are dimorphic, having more than one appearance during their life cycle. These dimorphic fungi may be able to appear as yeasts or molds, which can be important for infectivity. They are capable of changing their appearance in response to environmental changes such as nutrient availability or fluctuations in temperature, growing as a mold, for example, at 25 °C (77 °F), and as yeast cells at 37 °C (98.6 °F). This ability helps dimorphic fungi to survive in diverse environments. Histoplasma capsulatum , the pathogen that causes histoplasmosis , a lung infection, is an example of a dimorphic fungus ( [link] ).

Questions & Answers

what is fermentation example ?
Sonal Reply
is proceess in which an agent couses of an oganic substances breakdown into simpler substance,especially in aneorobic breakdown of suger into alcohol.
Okashat
is it better to study microbiology and then medicine it makes no difference to go directly to medicine?
Jessee Reply
Dray's mathdme cell wall konse color k hote he
Jinal Reply
what is dray's mathdme cell wall
Prabhat
I confused. please help me
Karen
just confused
Raj
l don't understand it please explain it for me.
Karen Reply
epitopes are present on the surface of
Rohit Reply
at the tip of variable region on the antibody...where antigen and antibody binding sites combine...
Fiza
The term that is used refer to moving microbes under a microscope are referred to as?
Lee Reply
Members of the genus Neisseria cause which of the folowing human diseases?
Farah Reply
genital infections
Kamaluddeen
gonorrhoea
sandip
gonorrhoea
Jessee
4. Which of the following specimens should not be refrigerated? a. Urine b. Urogenital swab
Zahraa Reply
urine
Muuse
urine
Agatha
Urine
Tean
urine
Yasser
Urine
Ebtehal
urine
anamika
urine
Puja
urine
Inemesit
urine
Samuel
Urine
Muhammad
Details about McConkey agar
Muhammad
urine
SK
urine
what is bacteria
anamika Reply
a member of large number of unicellular microorganism which have cell wall but lack of cell organelles an oranised nucleus including somewhat can cause disease
Sukhdeep
Bacteria are usually composed of one cell onl to that are neither plants nor animals, microscopic, that may cause diseases or may be beneficial(in gut)... it depends upon their weapons. Nearly all animal life is dependent on Bacteria for their survival
Fiza
thanks
anamika
what factor make bacteria colony large and how could we sterlise it in large scale
fatty
nutrient concentration temp gaseous conc ph ion or salt concentration mositure condition factors contribute to make large colony. by autoclaving we will sterilize bactetia
Sukhdeep
Colony is actually visible growth of Bacteria that is as a result of suitable environment for growth i.e optimal conditions for growth, temperature, moisture etc. there're many methods to get rid of bacteria. If We stop giving them optimal conditions for living Bacteria will die soon .
Fiza
what's the difference between an antigen and a pathogen?
Pathogens are organisms that cause disease in other organisms whereas Antigen is a part of a pathogen that triggers the immune response..
Rajat
so it is the antigen that dendritic cells present to the T cells and not the pathogen itself?
no no antigen are the west product or part of the pathogen. in such case bacteria it self fight with over immune response & in another case bacteria release antigens
vasava
& other antigen like pollan grain, dust particles etc.....
vasava
pathogen are microbes that can infect the body and causw illness....antigens are the part of pathogens that alert the body to an infection
Sukhdeep
antigen is a part of blood and pathogen is foreign particle which causes diseases
Yogyata
antigen could be non microorganism.... where as pathogen is mixroorganism
tadesse
Thanks
Karen
a pathogen is a disease causing organism while an antigen is a protein in the white blood cells which combats pathogens.
Jessee
what type of widal test
sobhit Reply
this test determine for typhoid in this test if H,O antigen are present that indicate the positive test bac. are salmonella typhy
vasava
what h.o denotes
Iqra
o: body of bacteria, h: flagellate
Explain Mould
Chinenye Reply
Explain mycoses and it's classification
Chinenye
why do we have hiccups?
Manisha Reply
shakey diaphragm
Curlisse
The antibody binding site is formed primarily by:
Asalla Reply
How many types of MICROORGANISMS do we have?
Hope Reply
Hello friends
Hope
microorganisms are divided into seven type Bacteria archaea protozoa algae fungi virus and multicellular animal parasites
Raj

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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