Fundamental vs Realized Niche
Fundamental: the theoretical range of environments where a given microbe could live
Realized: the range of environments where that microbe actually lives in the real world
Symbiosis
close, long-term interaction between different organisms; often involve co-evolution; often physical interaction
T or F. Many important interactions are transient and not true symbiosis
T!
Lichens are microbial communities comprised of two dominant organisms
1) fungus (eukaryote)
2) an alga (eukaryote) and/or a cyanobacterium
Microbial consortium
Two or more microbes living in a symbiotic relationship
“Chlorochromatium aggregatum”
- not single species
- green sulphur bacteria (phototrophs)
- beta-proteobacterium (motile)
- consortium always found together but not singular species
Cross-feeding
one organism’s waste is another’s food
Community-level metabolic processes
metabolic processes that require many distinct organisms to complete
Direct combat
antimicrobial mechanisms
- kill other microbes or slow them down to acquire the desired substance
Complex interactions
- not true symbiosis
- dynamic
- cross-feeding
community-level metabolic processes - direct combat
Bacteriocins
- protein toxins produced by bacteria
- similar to antibiotics and T6SS
- strain to strain variation
- immunity proteins protect producers
Nisins
- bacteriocins
- used for food preservation
- targets cell wall synthesis and is active against a broad spectrum of gram positive bacteria
- 11 genes required
- enzymes can modify this
“Killer Yeasts”
produce toxins that kill other yeasts
LCV
Legionella containing vacuoles
