chapter 20 Flashcards
What is an ecosystem?
All organisms and abiotic factors in an environment.
What is a habitat?
A part of the ecosystem where a community could survive.
What is a microbial population?
Same species, place, and time.
What is a microbial community?
A combination of different species living together.
Species richness
variety of species
Species abundance
proportion of each
species
Richness and abundance is due to
nutrients in a habitat
What are abiotic factors?
Non-living elements that affect microbial life.
Name 3 key abiotic factors.
Oxygen level, nutrients (like nitrogen), temperature.
What other abiotic factors influence microbes?
Salinity, pH, and minerals (e.g., phosphorus, sulfur).
Biogeochemistry
biologically mediated
chemical transformations
Biogeochemical cycle
transformation of an
element by biological agents
(involves oxidation-reduction reactions Recycle elements to living systems)
What are guilds?
Metabolically related microbial populations.
What do different guilds form?
Microbial communities.
What is a niche?
A habitat shared by a guild.
How do microbial communities interact?
With macroorganisms and abiotic factors.
What is a realized (prime) niche?
The ideal environment for an organism.
What is a microenvironment?
The immediate surroundings of a microbial cell where conditions can change rapidly.
What do nutrients do in biofilm formation?
Adsorb to surfaces, attracting microbes.
What is a biofilm?
A group of bacterial cells stuck to a surface, surrounded by a sticky matrix.
What is the matrix in a biofilm made of?
Usually polysaccharides secreted by the cells.
What do biofilms do?
Trap nutrients and prevent cell detachment.
What starts biofilm formation?
A cell attaches and expresses biofilm-specific genes.
What do biofilm genes trigger?
Signal production and matrix formation.
What type of communication is key in biofilms?
Quorum sensing.
What is the main signaling molecule in quorum sensing?
Acylated homoserine lactones (AHLs).
Does quorum sensing happen between different species?
Yes, both intraspecies and interspecies signaling occur.
How do biofilms help with self-defense?
Protect against forces, phagocytosis, and toxins/drugs.
How do biofilms help with survival?
Let cells stay in a favorable niche.
What’s a community benefit of biofilms?
Bacteria live close together for easier communication and cooperation.
Advantages of biofilm formation
Self-defense against
Against physical forces
Against phagocytosis
Against toxins/drugs
Name a dental condition caused by biofilms.
Periodontal disease.
Name some medical conditions linked to biofilms.
Kidney stones, tuberculosis, Legionnaires’ disease, Staph and Pseudomonas infections.
How do biofilms affect industrial systems?
They slow liquid flow in pipes and accelerate corrosion.
What are the main types of terrestrial environments?
Soils and the subsurface.
Why are soils important microbial habitats?
They support diverse microbial communities and play key roles in nutrient cycling.
What are soils?
The outer part of Earth’s surface that supports microbial life.
What are the two broad types of soils?
Organic soils and mineral soils.
How do organic soils form?
From sedimentation in bogs and marshes.
How do mineral soils form?
From rock weathering and inorganic substances.
What are the main components of soil?
Inorganic mineral matter, organic matter, air and water, and living organisms.
What percentage of soil volume is inorganic mineral matter
Approximately 40%.
What percentage of soil volume is organic matter
Approximately 5%.
What percentage of soil volume is air and water?
Approximately 50%.
What living organisms are present in soil?
Microorganisms like bacteria, fungi, and small animals.
What is the rhizosphere?
The soil surrounding a plant root.
What do microbes in the rhizosphere receive from plant roots?
Microbes receive substances (like nutrients and exudates) from the root
What are mycorrhizae?
Symbiotic relationships between fungi and plant roots, enhancing nutrient and water uptake.
What is the difference between ectomycorrhizae and endomycorrhizae?
Ectomycorrhizae colonize the rhizoplane, but fungal mycelia do not penetrate the root.
Endomycorrhizae penetrate plant cells, forming a more intimate association
How do mycorrhizae benefit plants?
They enhance plant uptake of water and minerals and help distribute organic substances among different plants.
What is the most important factor for microbial populations in surface soils?
Water availability is the most important factor for microbial populations in surface soils.
What is the most important factor for microbial populations in the subsurface?
Nutrient availability is the most important factor for microbial populations in the subsurface.
How does the diversity of microbial populations in soil vary?
Diversity varies based on soil type and geographical location.
How deep have microbes been detected in groundwater?
Microbes have been detected as deep as 3 kilometers in regions with water.
What are the two main types of aquatic environments?
Freshwater and Marine environments.
What organisms are typically found in marine environments?
Marine phototrophs, such as phytoplankton, and other marine organisms like fish and microbes.
What are marine phototrophs?
Microorganisms in marine environments that conduct photosynthesis, like algae and cyanobacteria
What are pelagic organisms?
rganisms that live in the open water column, away from the shore or sea floor
What is the significance of the deep sea?
The deep sea is characterized by high pressure, low temperature, and limited light, but hosts unique microbial life adapted to extreme conditions.
What are hydrothermal vents?
Underwater geysers that release hot, mineral-rich water, supporting specialized microbial ecosystems.
What controls the oxygen and carbon cycles in freshwater environments?
The balance between photosynthesis and respiration
What are phytoplankton in freshwater environments?
Oxygenic phototrophs suspended freely in water, including algae and cyanobacteria
What are benthic species in freshwater environments?
Species that are attached to the bottom or sides of a lake or stream
What factors influence oxygen concentrations in aquatic systems?
Oxygen concentrations are dependent on the amount of organic matter present and the physical mixing of the system
Why can the deep layers of freshwater lakes become anoxic?
Oxygen has limited solubility in water, and the deep layers can become anoxic once the oxygen is consumed.
What happens to water in many temperate lakes during the summer
The water column becomes stratified, meaning the water layers separate, with warmer water on top and cooler water below.
Why are rivers often well-mixed?
Rivers may be well-mixed due to the rapid water flow.
How can rivers still suffer from oxygen deficiencies?
Rivers can suffer from oxygen deficiencies due to high inputs of organic matter from sewage, agricultural, and industrial pollution.
What is Biochemical Oxygen Demand (BOD)?
BOD refers to the microbial oxygen-consuming capacity of a body of water.
How does the marine environment compare to most freshwater environments?
The marine environment is saline, low in nutrients (especially nitrogen, phosphorus, and iron), and cooler
Why are microbial activities in the ocean significant?
Microbial activities in the ocean are major factors in Earth’s carbon balance due to the size of the oceans
Near-shore marine waters typically contain higher microbial numbers than the open ocean because of
higher nutrient levels
What was the Deepwater Horizon oil spill?
The Deepwater Horizon oil spill was the largest marine oil spill ever, where oil was released as a plume at great depths
How did the growth of hydrocarbon-degrading bacteria affect the environment?
The early growth of these bacteria may have reduced the environmental impact of the oil spill.
Which bacteria were involved in the oil degradation during the Deepwater Horizon spill?
Hydrocarbon-degrading bacteria such as Gammaproteobacteria, Colwellia, and Cycloclasticus bloomed during the spill.
What are Oxygen Minimum Zones (OMZ)?
OMZs are regions of oxygen-depleted waters at intermediate depths in the ocean.
Why do OMZs have high oxygen demand?
OMZs are nutrient-rich areas, leading to high microbial activity, which increases the oxygen demand.
What processes are common in OMZs?
Denitrification and anammox are common processes in OMZs, as they occur in the absence of oxygen.
What is happening to OMZs over time?
OMZs are expanding, likely due to increasing nutrient levels and changing environmental conditions.
What organisms are responsible for most of the primary productivity in the open oceans?
Prochlorophytes are responsible for most of the primary productivity in the open oceans.
What is Trichodesmium, and where is it found?
Trichodesmium is a planktonic filamentous cyanobacterium found in tropical and subtropical oceans. It is an abundant phototroph.
What are Ostreococcus, and where do they live
Ostreococcus are small phototrophic eukaryotes that inhabit coastal and marine waters and are likely important primary producers.
What are aerobic anoxygenic phototrophs?
Aerobic anoxygenic phototrophs are marine microbes that use light energy for ATP synthesis but do not fix carbon dioxide.
How do aerobic anoxygenic phototrophs use light energy?
They use light energy for ATP synthesis via a process called photophosphorylation.
What type of prokaryotes are abundant in pelagic zones of the ocean?
Small planktonic heterotrophic prokaryotes are abundant in pelagic zones.
How does the density of prokaryotes in the open ocean change with depth?
Prokaryote densities in the open ocean decrease with depth.
Which organisms dominate surface waters in the ocean?
Bacterial species tend to dominate surface waters.
How do the populations of Bacteria and Archaea compare in deeper waters?
In deeper waters, Bacteria and Archaea are near equal in number.
What is the most abundant marine heterotroph?
The most abundant marine heterotroph is Pelagibacter, an oligotroph.
What unique feature do Pelagibacter and other marine heterotrophs contain?
They contain proteorhodopsin, a form of rhodopsin that allows cells to use light energy to drive ATP synthesis.
What are the most abundant microorganisms in the oceans?
Viruses are the most abundant microorganisms in the oceans.
How do viruses affect marine life?
Viruses affect prokaryotic populations and are highly diverse.
What percentage of all ocean water is considered deep sea?
> 75% of all ocean water is deep sea.
What are the main challenges faced by organisms in the deep sea?
Organisms in the deep sea must deal with low temperature, high pressure, low nutrient levels, and absence of light energy.
What types of communities thrive around deep-sea hydrothermal vents?
Animal and microbial communities thrive around deep-sea hydrothermal vents.
What types of microbes are found in the deep sea?
Psychrophilic (cold-loving) or psychrotolerant (cold-tolerant) microbes and piezophilic (pressure-loving) or piezotolerant (pressure-tolerant) microbes.
What are the two types of hydrothermal vents?
Warm diffuse and very hot vents.
What types of bacteria are predominant at hydrothermal vents?
Chemolithotrophic bacteria predominate at hydrothermal vents.
What types of organisms are present at hydrothermal vents due to the extreme conditions?
Thermophiles and hyperthermophiles are present at hydrothermal vents.
How do chemolithotrophic prokaryotes survive at hydrothermal vents?
They utilize inorganic materials from the vents for energy.
