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MICR 3050 > Microbial Ecology > Flashcards

Microbial Ecology Flashcards

1
Q

ecosystem

A
  • sum of all the organisms and abiotic factors in a particular environment
  • made up of communities
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2
Q

population

A

a group of organisms of the same species in the same place at the same time

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3
Q

community

A
  • two or more cell populations coexisting in a certain areas at a given time
  • made up of guilds
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4
Q

habitat

A

portion of an ecosystem where a community could reside

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5
Q

guild

A

metabolically related microbial population

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6
Q

niche

A
  • habitat shared by a guild

- metabolically related things survive here

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7
Q

alpha diversity

A
  • diversity within a community (sample)

- richness, abundance, evenness

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8
Q

richness

A

the total number of different species present in a particular area

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9
Q

abundance

A

the proportion of each species

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10
Q

evenness

A

how similar the abundances are (relative abundance of different species)

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11
Q

beta diversity

A

comparison of samples (between community diversity)

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12
Q

gamma diversity

A

the total species diversity for the different ecosystems within a region (landscape diversity)

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13
Q

nitrification

A

the oxidation of ammonia to nitrate

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14
Q

denitrification

A

the reduction of nitrate to nitrogen gas

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15
Q

nitrogen fixation

A

the reduction of nitrogen gas to ammonia

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16
Q

ammonification

A

the release of ammonia during the decomposition of organic nitrogen compounds

17
Q

anammox

A

the anaerobic oxidation of ammonia to nitrogen gas

18
Q

What is the role of the nitrogen cycle in nature?

A
  • nitrogen is an essential nutrient for sustaining life

- the nitrogen cycle helps convert inert nitrogen gas into a usable form for plants

19
Q

legume-root nodule symbiosis

A
  • plant-bacterial mutualism
  • legumes: plants with seeds that grow in pods such as soybeans, clover, alfalfa, beans, peas, peanuts
  • legumes grow well in nitrogen deficient soils
  • legumes play a key role in crop rotation by replenishing nitrogen to the soil
  • infection of legume roots by nitrogen fixing bacteria rhizobid leads to the formation of root nodules
  • legumes with the bacteria grow better in nitrogen deficient soil and do not need nitrogen fertilizers
20
Q

ruminants

A
  • herbivorous animals that possess a rumen

- cows, sheep, goats, etc

21
Q

rumen

A

digestive organ within which cellulose and other plant polysaccharides are digested by microbes

22
Q

What happens in the rumen?

A
  • rumen contains 10^10-10^11 microbes/g
  • cellulolytic microbes hydrolyze cellulose to free sugars
  • fermentation of sugars yields volatile fatty acids (acetate, propionate, butyrate) that pass through the rumen wall into the bloodstream and serve as the ruminant’s main energy source
  • CO2 and CH4 are released via erucatation (burping)
23
Q

microenvironments

A
  • microbial environments in nature
  • complex
  • constantly changing
  • conditions determined in part by metabolic activities of the community
  • resources and growth conditions highly variable and often suboptimal
  • competition and cooperation occurs
  • “feast or famine” existence
24
Q

biofilms

A
  • assemblages of bacterial cells attached to a surface
  • heterogeneous community
  • enclosed in adhesive matrix
  • trap nutrients for microbial growth and help prevent detachment of cells
  • provide protection
  • microbes can interact with one another
25
Q

How are biofilms formed?

A
  1. Substratum preconditioning by ambient molecules
  2. Cell deposition
  3. Cell adsorption/desorption
  4. Cell to cell signaling and onset of exopolymer production
  5. Convective and diffusive transport of O2 and nutrients
  6. Replication and growth
  7. Secretion of polysaccharide matrix
  8. Detachment, erosion, and sloughing
26
Q

What are problems associated with biofilms?

A
  • can be found on medical devices and can cause disease
  • biofilms on teeth can cause cavities
  • biofilms can cause pneumonia
  • can be found on industrial devices and interfere with fluid distribution
  • potential for corrosion
27
Q

quorum sensing

A
  • the regulation of gene expression in response to fluctuations in cell population density
  • bacteria secrete chemical messengers that affect bacterial behavior
  • ex: can make cells competent so that they can uptake DNA, increasing genetic diversity
  • ex: to kill other cells to get their DNA or use them as a source of nutrients
  • bacteria act differently on their own than they do in a biofilm

MICR 3050 (18 decks)

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