MCB3020 Week 5: Microbial Ecology

Biotic factors

Some _ that affect microbes are; other organisms, their community dynamics, and activities

Abiotic factors

Some that affect microbes are; their environment

Symbiosis

Two or more species working together

Parasitism

One member in the relationship is harmed, and the other benefits

Mutualism

Both species in a relationship benefit

Commensalism

One species benefits, and the other is neither harmed or helped in the relationship

Ecology

The purpose of relating to microbes is species diversity and abundance

Community

Populations of one species living in association with populations of one or more other species

Population

Group of microorganisms of the same species residing in the same place at the same time

Guild

Metabolically related microbial populations, where sets of form microbial communities that interact with macroorganisms and abiotic factors in the ecosystem

Niche

Habitat shared by a guild, supplies nutrients as well as conditions for growth

Habitat

Microbes inhabit any plant or animal , but microbes also inhabit __ where plants and animals cannot survive

Species richness

Total number of different species present in an ecosystem

Species abundance

Proportion of each species in an ecosystem

Biogeochemistry

The study of biologically mediated chemical transformations

Biogeochemical cycle

Defines the transformations of a key element by biological or chemical agents, typically proceeds by oxidation-reduction reactions (redox reactions)

Microenvironment

The immediate environmental surroundings of a microbial cell or group of cells

Growth rates

In natural habitats, these are influenced by physiochemical conditions or resources available whether in feast or famine.

Surfaces

Important microbial habitats as it allows for nutrients to adsorb to them, and microbial cells can attach to these; common location of biofilms.

Biofilm

Cells adhered to surface, stick with polysaccharides. They trap nutrients for microbial growth which help prevent detachment of cells. They are 1000x more resistant to antibiotics in the body and chemicals to decontaminate other surfaces

Biofilm formation

Happens by attachment, then expression of biofilm formation specific genes, relies on intercellular communication to help develop and maintain a biofilm

Pseudomonas aeruginosa

Problem for medical device biofilms which can cause periodontis, chronic wounds, tuberculosis, and more

Acylated homoserine lactones

Major intercellular signaling molecules in biofilms, where lactones activate biofilm formation gene expression

Microbial mats

Very thick biofilms built by phototrophic and/or chemolithotrophic bacterias, grows on sediment surface where anoxic water rich in H2S meets oxic water

Beggiatoa

Species mostly found in chemolithotrophic mats which contain filamentous sulfur-oxidizing bacteria.

O horizon

Soil layer containing undecomposed plant materials

A horizon

Soil layer containing surface soil, high in organic matter, dark in color, tilled for agriculture, plants and many microorganisms grow here with there being high microbial activity

B horizon

Soil layer containing subsoil, has minerals, little organic matter, there's some microbial activity but not as much as A horizon

C horizon

Soil layer containing the soil base, develops directly from underlying bedrock, very low microbial activity

Soil

Composed of mostly air and water, inorganic mineral matter, organic matter, and living organisms

Soil aggregates

Contains many different microenvironments supporting the growth of many types of microbes, where water availability is a variable in growth as is oxygen. There's less oxygen in waterlogged soil, and low carbon availability in arid lands

Surface soils

The availability of water is the most important factor influencing microbial activity in __

Subsurface environments

Nutrient availability is the most important factor in _, where only archaea and bacteria exist in deep subsurface and is anoxic

Oxygen and carbon cycles

The balance between photosynthesis and respiration controls these

Phytoplankton

Oxygenic phototrophs suspended freely in water, includes algae and cyanobacteria

Benthic species

Attached to the bottom or sides of a lake or stream

Oxygenic

Phototrophs are typically _, and produce organic material and oxygen (reducing power from H2O) and includes cyanobacteria and algae

Anoxygenic

Phototrophs like this are usually benthic or in anoxic waters like sulfur springs, and produce organic material but NOT oxygen (reducing power from H2S)

Rivers

Due to the rapid water flow, these are well mixed and likely to be more oxygenated all throughout compared to a less mixed body of water like a lake. Can still suffer from oxygen deficiencies due to there being a large amount of organic matter from sewage and pollution

Biochemical oxygen demand (BOD)

The microbial oxygen-consuming capacity of a body of water

Open ocean

Compared to freshwater environments, this environment is saline, low in nutrients (particularly nitrogen, phosphorous, iron) and is cooler in temperature

Upwelling

These areas have higher nutrients compared to the open ocean

Dead zone

Eutrophic open ocean areas that may lead to oxygen depletion, creating a ___

Deepwater Horizon Oil Spill

Largest marine oil spill where oil was released as a plume at great depths, blooming hydrocarbon-degrading Gammaproteobacteria, Colwellia, and Cycloclasticus which may have helped reduced the environmental impact

Prochlorococcus

Prokaryotic cyanobacteria that dominates the open ocean, very small, 40% of the biomass of marine phototrophs and has 50% of the net primary production

Trichodesmium

Found in some areas (tropical Atlantic, Gulf of Mexico) that fixes nitrogen, nutrient input to marine ecosystem, looks like sawdust on the ocean surface

Productivity

Eukaryotic phytoplankton dominate higher _ waters

SAR11

Most abundant group of heterotrophic bacteria are from this clade, and are abundant in pelagic marine waters

Oligotroph

Organism that grows best at very low nutrient concentrations

Peligibacter

Representative of the SAR11 clade, has small cells and a small genome, has proteorhodopsin

Proteorhodopsin

Allows cells to use light energy to drive ATP synthesis, not considered phototrophic as ATP production is supplemental

Marine viruses

Very abundant, act as bacteriophages and enhance nutrient turnover by consuming many bacteria

Microbial loop

Organisms are DOC/DOM (dissolved organic material/carbon) from bacterial lysis and dead cells; carbon cycling by bacteria/viruses as a major part of the ocean's carbon cycle

Detritovores

Bacteria consumes detritus (dead material)

Chemolithotrophic

This type of bacteria predominates deep-sea hydrothermal vents, utilizing the inorganic materials from the vents