Module 4 - Microbial Ecosystems Flashcards
The specific functional role of an organism within an ecosystem is called?
Niche
What are the 3 factors pertaining to resources that help define a niche?
- Type
- Quality
- Quantity
What is the general rule in ecology?
No two populations of organisms can occupy the same niche and co-exist sustainably
Which archaeal and bacterial pair can coexist stably within the same gut habitats?
Methanobrevibacter smithii and E.coli
E.coli is the … in the colon
Fermenter
M. smithii is a … in the colon
Methanogen
Structured communities held together by extracellular polysaccharides are called?
Biofilms
How does biofilm growth provide an advantage for microorganisms?
Nutrients bind to solid surfaces; enables higher cell concentrations
What are the first microorganisms adhering to a surface? Give an example
- Appendaged bacteria
- Caulobacter or Hyphomicrobium
Species that divide and form microcolonies are called?
Primary colonizers
Species that join the growing biofilms are called?
Secondary colonizers
What forms a gel-like matrix that is important for biofilm formation?
Exopolyssacharides (EPS)
What are the functions of the gel-like matrix?
- Aids in the formation of water-filled channels
- Facilitates the transport of nutrients and waste through the biofilm
Using a culture medium and conditions designed to favor the growth of a particular microorganisms is called?
Cultivation-Dependent Techniques
What is the name of the aerobic N2-fixing bacteria?
Azotobacter
Characterizing inhabitants of microbial ecosystems, including microorganisms that we cannot grow readily are called?
Cultivation-Independent Techniques
Minerals, gases, and water are known as what kind of factors?
Abiotic factors
How do organisms become specialized for their prime niches?
- Evolutionary pressures of selection
- Competition
Why can’t two populations of organisms occupy the same niche?
One population will always outcompete
What do we call environments in which conditions change over short distances?
Microenvironments
What experiment demonstrated the importance of EPS production?
EPS production by Escherichia coli K12 during biofilm formation
Which bacterium is use to understand the practical concerns associated with biofilms?
Pseudomonas aeruginosa
What human disease are characterized by biofilm formation?
Cystic Fibrosis
What is the unit that estimates the number of bacterial or fungal cells in a sample which are viable, able to multiply?
Colony-forming unit
Using molecular techniques such as sequencing and analysis of nucleic acids extracted from environmental samples is known as what?
Cultivation-Independent Techniques
What are some examples of Indirect method for characterizing microbial ecosystems?
- Denaturing gradient gel electrophoresis
- Terminal restriction fragment length polymorphism (T-RFLP)
- Stable Isotope Probing
- Fluorescence-activated cell sorting (FACS)
Method used to separate small PCR-amplified DNA fragments of 200-700 base pairs that have been obtained from an environmental sample
Denaturing gradient gel electrophoresis
Technique in which microbial communities are examined by the position of a restriction site closest to a labeled end of an amplified gene
Terminal restriction fragment length polymorphism (T-RFLP)
Technique in which fluorescence can be used to screen cells
Fluorescence-activated cell sorting (FACS)
Technique in which microorganisms are examined to see if they are capable of metabolizing a given compound by using stable isotopes
Stable-isotope probing
What made it possible to learn an enormous amount about the types of microorganisms present in the environment and their relationship to one another
SSU rRNA
What is a tool that involves the construction of gene libraries from DNA extracted directly from the environment?
Metagenomics
What are the three major zones of the ocean?
- Surface Zone
- Dark Mid-water Zone
- Deep Sea Zone
What zone is caused by the scarcity of key nutrients like nitrogen and phosphorus that limits photosynthesis?
Dead Zones
What kind of organisms can reside at the depths of the Deep Sea Zone?
- Microorganisms that can withstand extremely high atmospheric pressures
- Piezophiles or barophiles
What zone experiences agricultural activities such as runoff?
Dead Zones
What zone does photosynthetic microbes inhabit?
Surface Zone
Which non-photosynthetic microbe graze on primary producers and other microbes in the surface zone?
Zooplankton
Which zone does photosynthesis not occur and microbial life is fed by the organic matter produced in the upper surface waters?
Dark Mid-water Zone
Which zone exhibits extremely high atmospheric pressures?
Deep Sea Zones
What happens to the plasma fluidity and enzyme function in the Deep Sea Zone?
Decreases
What role does viruses play in the oceans?
- Control the microbial communities that exist within the marine water column
- Cyanobacteria lyse and fragments of plasma membrane, DNA, proteins, and nutrients are released into the environment
What is the term called when seawater samples are diluted so that very few cells remain in each aliquot?
Dilution to extinction
What is the thin band over the terrestrial surface of Earth that contains more microbial diversity and activity than any other microbial system called?
Soil
What distinguishes biomes?
Temperature and precipitation
What factors are influenced by biomes?
- Latitude
- Elevation
- Geological features
What biome plays a central role in the dominant primary producers, providing nutrients to the soil via microbial decomposition and photosynthesis- derived root exudates?
Terrestrial biomes
Which horizon contains inorganic matter, and closest to bedrock?
C Horizon
Which horizon contains subsoil and some organic matter?
B Horizon
Which horizon contains topsoil?
A Horizon
Which horizon composes the organic matter on the surface of the soil?
O Horizon
What is the result from incomplete breakdown of plant biomass called?
Humic material
Which part of the soil immediately surrounds the plant roots, and represent a distinct and important ecosystem?
Rhizosphere
Which contains higher numbers of microbes, bulk soil or rhizosphere?
Rhizosphere
What are chemicals that are not naturally found or produced by organisms and are detrimental to human and animal health called?
Xenobiotics
