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MICR3310 > 1 - Planetary Health & Ecosystems > Flashcards

1 - Planetary Health & Ecosystems Flashcards

1
Q

Planetary health

A

The health of human civilisation and the state of the natural systems on which it depends

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2
Q

What is the health of humanity intrinsically linked to

A

The health of the environment

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3
Q

Anthropocene epoch

A

the time during which humans have had a substantial impact on our planet

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4
Q

One health

A

Collaborative approach to achieve optimal health and well-being outcomes, recognizing the interconnections between people, animals, plants and their shared environment

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5
Q

Role of microbes in planetary health

A
  • Responsible for about half of all primary production
  • Drive many important cycles on earth
  • Important roles in health of animals plants and environments
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6
Q

Important cycles driven by microbes

A
  • Generate oxygen
  • Carbon cycling and sequestration
  • Cycling of other nutrients
  • Climate change / global warming
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7
Q

Ecosystem

A
  • A complex of plants, animals and microbial communities and their physical environment
  • Are dynamic and changing
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8
Q

Habitats

A
  • Smaller parts of ecosystem
  • May not be suited to all members of the ecosystem
  • Contain multiple microenvironments
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9
Q

Examples of environments uniquely suited to microbes

A
  • Hot springs
  • Deep ocean thermal vents
  • Acidic environments
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10
Q

Microenvironments

A
  • The space immediately surrounding microbial cells and that they directly experience
  • Conditions can change dramatically over small distances
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11
Q

Layers of soil

A
  • O horizon: Plant material
  • A horizon: Surface soil (high microbial activity)
  • B horizon: Subsoil (Lower microbial activity)
  • C horizon: Soil base (Ver low microbial activity
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12
Q

Microbial composition of a single soil particle

A
  • Microbes in the outer zone consume all the O2 before it can diffuse to the centre
  • Only anaerobic organisms live at the centre, then microaerophiles (low O2), then strict aerobes
  • facultative anaerobes could be distributed throughout
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13
Q

Oxygen in liquid culture and colonies on agar

A

Poor diffusion and rapid consumption

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14
Q

Types of metabolic activities occurring in an ecosystem are a function of

A
  • Species present
  • Population sizes
  • Physiological state
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15
Q

Rates at which metabolic activities occur are a function of

A
  • Nutrient availability
  • GRowth conditions
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16
Q

Why do microbes grow relatively slow in nature

A
  • Resources and conditions are usually suboptimal
  • Nutrients levels may be low
  • Nutrients are not evenly distributed through the environment
  • Microbes typically grow in mixed populations (in competition with other microbes)
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17
Q

Growth rates in nature vs in lab

A
  • Growth rates in nature are well below maximal growth rates measured in labs
  • E.g. E.coli in gut is about 12 hours, in lab 20 mins
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18
Q

Oligotrophic

A
  • Low nutrient environments
  • Therefore most organisms in nature are in state of growth arrest
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19
Q

Growth arrest

A
  • Not actively growing, but also not dying
  • Stressed by lack or nutrients or sub-optimal conditions
  • Organisms must be able to survive starvation
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20
Q

Eutrophication

A
  • Increase in nutrient availability
  • Occurs in freshwater lakes as a result of water run off (causes algal bloom)
  • Input of nutrients results in increased biological oxygen demand
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21
Q

Microbial strategies to cope with starvation

A
  • May produce storage polymers, which they use when starving (e.g. polysaccharides)
  • Decrease cell size (membrane lipids and ribosomes are recycled)
  • Form endospores (Gram positive bacteria)
  • Starvation proteins
  • Enter viable but non-culturable (VBNC) state
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22
Q

Community

A
  • Population of one species living in association with one or more other species
  • Intense competition may occur, but also cooperation
23
Q

Population

A

Group of microbes of same species residing at the same place at the same time

24
Q

Microbiome

A

Comprises all of the genetic material within a microbiota (the entire collection of microorganisms in a specific niche, such as the human gut)

25
Q

Two ways microbial diversity within communities can be expressed

A
  • Species richness and species abundance
  • Can change quickly over short timeframe
26
Q

Species richness

A

Total number of different species present

27
Q

How can species richness be measured

A

By culturing species in the lab or using molecular nucleic acid techniques to determine diversity of phylotypes

28
Q

Species abundance

A

Proportion of each species within the community

29
Q

What is richness and abundance functions of

A
  • Prevailing conditions
  • Types of nutrient available
30
Q

Example of high species richness

A
  • Undisturbed, organic-rich soils
  • Lots of diverse nutrients (supports many different
    species)
31
Q

Example of low species richness

A
  • Extreme environments
  • Conditions only allow proliferation of select microbes
32
Q

Examples of resources that govern microbial growth in nature

A
  • Carbon
  • Nitrogen (organic and inorganic)
  • Other macronutrients (S, P, K)
  • Electron donors and acceptors
33
Q

Examples of conditions that govern microbial growth in nature

A
  • Temperature
  • Water potential (dry, moist, wet)
  • pH
  • Light
  • Osmotic conditions
34
Q

Two broad groups of soil

A

Mineral soils (Weathered rock, major group) and organic soil (derived from sedimentation in marshes and bogs)

35
Q

Composition of soil

A
  • Inorganic mineral matter (~40% by volume)
  • Organic material (~5%)
  • Air and water (~50%)
  • Micro- and macro-organisms (~5%)
36
Q

Factors limiting microbial growth

A
  • Phosphorous
  • Nitrogen
  • oxygen
  • Water availability
37
Q

Rhizosphere

A

Soil surrounding plant roots that receives plant secretions

38
Q

Where is microbial activity highest

A

Rhizosphere and surface layers (rich in organic material)

39
Q

Examples of freshwater environments

A
  • Lakes, streams, rivers, glaciers
  • Resources and conditions vary widely
  • o2 most important factor as does not dissolve well in water
40
Q

Freshwater as microbial habitat

A
  • Both O2 producing and O2 consuming organisms are present
  • Balance between photosynthesis (O2 producing) and respiration (O2 consuming)
  • Controls cycles of carbon, O2 and other nutrients
41
Q

Main primary producers in freshwater

A

Oxygenic phototrophs

42
Q

Oxygenic phototrophs

A
  • Produce O2 and new organic material (fix carbon)
  • Obtain energy from light, use water as an electron
    donor
  • Includes algae and cyanobacteria
43
Q

Layers of freshwater

A
  • Epilimnion
  • Thermocline
  • Hypolimnion
44
Q

Epilimnion

A
  • Surface layer, warmer, less dense
  • Higher in organic matter, oxygen
  • Dominated by aerobic or facultative organisms
  • Consume most organic nutrients and 02
45
Q

Thermocline

A

Transition zone

46
Q

Hypolimnion

A
  • Bottom layer, cooler, denser
  • o2 depleted, less organic nutrients
  • Dominated by anaerobes
47
Q

Why is running water harder to sample

A

Populations may be transient, therefore most studies focused on lakes

48
Q

Major prokaryotic groups observed in freshwater (from largest to smallest)

A
  • Proteobacteria
  • Actinobacteria
  • Bacteroidetes
  • Cyanobacteria
49
Q

Ocean vs freshwater as microbial habitat

A
  • Nutrient levels in open ocean are comparatively lower (besides oxygen)
  • Water temperature is generally cooler
  • Total cell numbers typically 10-fold lower than in lakes
  • Typically have smaller cells (due to nutrient poor environment, more energy efficient)
50
Q

Ocean microbial communities varying according to water depth

A
  • Phototrophic microbes use the sun’s energy in the top 200 m of the water column
  • In deeper zones the microbes use organic and
    inorganic chemicals for energy
51
Q

Three seasonal microbial communities in ocean water

A
  1. Spring surface water bloom
  2. Summertime community in upper water column
  3. Deeper, more stable community
52
Q

Primary production in oceans

A

Prochlorophytes

53
Q

Prochlorophytes

A
  • Tiny, photosynthetic prokaryotic phototrophs
  • Type of cyanobacteria
  • Contain chlorophylls alpha and beta but no phycobilin
  • 4 strains with distinct ecotypes (each ecotype photosynthesises at different light intensities)

MICR3310 (28 decks)

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