ch. 25 Flashcards
why would fungi produce antibiotics?
- developing antibiotics serves as an adaption to enhance surivival
- protection from bacterial pathogens in the soil
what was fungi was penicillin discovered from? who discovered it?
- penicillium
- Alexander Fleming
how does penicillin work?
- reduces bacterial growth but not generally toxic to humans or other animals
- blocks cell wall synthesis of gram-positive bacteria
penicillin characteristics
- first “miracle drug”; cheap, effective, readily available
- cannot be chemically synthesized because it is cheaper and faster to grow the fungi
- semisynthetic: amoxicillin, ampicillin, methicillin (slight modification of penicillin)
what are drawbacks to using penicillin?
overuse has led to antibiotic resistance
- allergen presents in small percentage
other antibiotics from fungi?
- streptomycin from streptomyces
why is there continued research for antibiotic and antifungals derived from fungi and bacteria?
to battle antibiotic resistance
how has increased antibitoic resistance developed?
- bacterial have mechanisms to develop resistance factors towards antibiotics
- mutations can occur to develop genes for antibiotic resistance
- selection pressures also have an influence
mycotoxins
- produced by fungi in contaminated food
- often toxic and carcinogenic
- over 300 forms have been identified
- no safe levels
- ex. aflatoxin from aspergillus flavus; cause increased liver cancer in Asian and African populations
what can be done to protect the food supply from mycotoxins?
- keep food dry, seal well, and keep in adequate environment
Ergotism (mycotoxin case study)
- Fungus Claviceps purpurea infects cereal grains, ground in flour
- fungi produces toxic alkaloids
- alkaloids cause vasoconstriction (muscle pain and burning sensation) and CNS effects (hallucinations and death)
- influence in Salem witch trials: being possessed was confused with the hallucinations caused by the fungi
LSD
- ergot produced lysergic acid alkaloids which is the basis for synthesis of lysergic acid diethylamide (LSD)
- most potent psychoactive drug known
- interferes with NT seratonin
what do toadstools present?
- there is no universal way to distinguish edible from poisonous fungi
amatoxins
- deadly poisons in various fungi genera
- inhibit mRNA synthesis: this does not allow protein synthesis to occur, resulting in deadly and harmful effects for cells because they cannot produce necessary proteins for survival and functions
amatoxins
amanita genus
- causes 95% of mushroom fatalities
- release amatoxins
hallucinogenic fungi
amanita muscaria
- causes: loss of coordination, vivid dreams, and distortions
- used for 1000’s of years throughout the world
- used and reused by Siberian natives
hallucinogenic fungi
psilocybe genus
- causes: affects NT serotonin, hallucinations, depression, paralysis
- uses: religious and healing uses by Aztecs
- “magic mushrooms” (can be confused with amatoxin containing species). psilocin looks similar to NT serotonin
what is the evolutionary advantage for mushrooms to produce toxic or psychoactive compouds?
- increases survival and reproduction
- keeps predators away
types of hallucinogenic fungi
- amanita muscaria
- psilocybe genus
dermatophytes
- fungi that metabolize keratin on skin, hair, and nails
- spores transferred person to person
types of dermatophytes
- tinea captitis
- tinea pedis (medical condition)
- candida albicans
dermatophytes
tinea captitis
- ringworm; on scalp caused by various fungal species (not worms)
dermatophytes
tinea pedis
athletes foot fungi
dermatophytes
candida albicans
- normal part of body’s ‘flora’, can overgrow to cause yeast infections in mouth (thrush in infants), armpits, or vagina
- infest in moist areas
systemic mycoses
- fungal pathogens that infect tissue below the skin- typically chronic, slow developing
types of systemic mycoses
- histoplasmosis
- coccidioidomycosis
systemic mycoses
histoplasmosis
- fungal spores from bird and bat dung are inhaled
- infect the lungs and cause TB like symptoms
- Eastern and Mid USA
systemic mycoses
coccidioidomycosis
- decomposing fungi in soil found in SW USA
- spores infect the lungs
- symptoms: none, flue like valley, can be fatal
fungal spore allergens
- spores can exceed 100k/m2 outside
- nonseasonal: whenever ground is not covered in ice snow. unlike plants that are seasonal
- indoor moist contamination is increasing because houses are sealed, holding moisture.
sick building syndrome: poor ventilation leading to accumulation of chemical and biological contaminants. - occupying damp/moldy buildings increases the risk of respiratory problems and allergic reactions
