Topic: Microbial group
Notes:
1) Microbial growth is based on the growth of population and not individual growth.
2) There are four physical growth requirements of microbial growth:
- light
-temperature
(Mesophiles 25 degree celcius to 40 degree celcius, Psychrophiles 0 degree celcius to 20 degree celcius, psychrotrophs 20 degree celcius to 30 degree celcius, thermophiles 45 degree celcius to 50 degree celcius)
-pH
(most bacteria pH 5-9, most fungi pH 2-9)
- water activity and water pressure
(water activity is the amount of water found in substrate for the microorganisms to grow)
(maximum water activity for biomolecules is 1)
(bacteria live in higher water activity habitat 0.91 while fungi live in lower water activity habitat is 0.7 )
3) There are six chemical growth requirements:
- water
- carbon
- oxygen
(microaerophiles - need little amount of oxygen, facultative anaerobes -can live with oxygen or without oxygen, aerotolerant - can live in with oxygen and without oxygen)
- nitrogen, phosphorus and sulfur
(nitrogen can obtained from atmosphere, phosphorus can obtained from inorganic source, sulfur can obtained from organic or inorganic molecules)
- special growth factors
(Legionella pneumophila require L-cystein and iron to grow and L-cystein are provided by algae and amoebas)
- trace elements
4) Nutritional types:
- Photoautotrophs (E:light, C: CO2)
- Photochemotrophs (E:light, C: organic molecules)
- Chemoautotrophs (E:light, C:inorganic molecules)
- Chemoheterotrophs (E: organic molecules, C: organic molecules)
5) Population strategies are either r strategists or K strategists.
- r strategists have high rate of reproduction rate, short generation time, population are subject to extreme fluctuation
- K strategists have low rate or reproduction, large size, large storage, successful in resource limited environments and they are more stable populations
6) They are four types of succession:
- Preemptive colonization - pioneer organisms alters condition in a way that discourages further succession
- Autogenic succession - microorganisms modify the habitat in a way that permits in a new population to develop
- Allogenic population - Microbial species succession occurs because the habitat is altered by environmental factors.
- Climax community - achieved when succession ends however it is rarely achieved.
7) Biofilm composed of living. reproducing microorganisms, such as bacteria that exist as a community. Biofilm can trap nutrient and prevent detachment from surfaces. The disadvantages of biofilm are unavailable for attack by immune system, dental caries, slow the flow of water through pipelines and accelerate the corrosion of pipes.
Activity:
No other activity except for teaching...^^
My own explorace:
1) Biology control agent is the use of natural enemies to reduce the populations of pests such as insects and weeds.
2) We can know the temperature where the microorganisms used to grow based on the temperature of their habitat.
3) To isolate a microorganisms, we need to know the habitat of the microorganisms. Suitable media need to prepare and dilution pf the culture is necessary before we incubate in the media. After verify the cingle colony of the target microorganisms, we need to do sub culture to transfer the microorganisms to a fresh new media for them to grow.
4) We need to test at different temperature is the isolated microorganisms didn't grow well in the expected temperature.
5) Gnotobiotic animals are animals in which only certain known strains of bacteria and other microorganisms are present. They are only exposed to those microorganisms that the researchers wish to have present in the animal. Animals reared in a gnotobiotic colony often have poorly developed immune systems, lower cardiac output, thin intestinal walls and high susceptibility to infectious pathogens.
6) Diazotrophs are bacteria and archaea that fix atmospheric oxygen into a more usable form such as ammonia. Even within a species that can fix nitrogen there may be strains that do not fix nitrogen. Fixation is shut off when other sources of nitrogen are available, and, for many species, when oxygen is at high partial pressure. Azotobacter vinelandii is one of the diazotroph that can fix nitrogen while growing aerobically.
7) Biofilm can act as indicator ( same with the function of lichens) because the habitat of biofilm is always unpolluted.
8) We can obtain the enzymes at the lag phase of bacterial growth while we can obtain the secondary metabolites at between log phase and stationary phase.
9) Termite gut exhibits complex microbial community as in rumen. Since termite feed on diet that is rich in carbon but poor in nitrogen, therefore nitrogen fixers is essential to supply a sufficient amount of nitrogen in termite gut. Treponema, Citobacter, Enterobacter, and Spirochaeta are some of the responsible nitrogen fixers. The prokayotes in termite guts usually associated with protists as symbionts. Treponema spirochete bacteria attached to the plasma membrane of mixotricha and contributes the movement of mixotricha. Treponema also benefits on living within mixotricha where hydrogen and carbon dioxide nutrients are easily to access by the production from mixotricha.
Reflection:
Amazing microbial community! I can't imagine the small termite gut contain so many microorganisms. I think we really can't live without microbes. My friends from the department of biomolecules created an article for the event "life without microbes" and the title of the articles is MICRO-AVENGERS. I like this title because people will know that human can't live without microbes based on this title.
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