Lecture_8_Microbial_Ecology_UPDATED

Learning Objectives in Microbial Ecology

• Biotic and Abiotic Factors: Recognize factors affecting microbes, including biological (biotic) interactions and environmental (abiotic) conditions.

• Symbiosis: Define and provide examples of symbiotic relationships:

  • Parasitism: One organism benefits at the expense of another.

  • Mutualism: Both species benefit from the relationship.

  • Commensalism: One species benefits while the other is neither helped nor harmed.

• Purpose of Ecology: Understand ecology in relation to microbes and how it affects community dynamics and functions.

• Ecosystem Components:

  • Define communities, populations, guilds, niches, habitats, species richness, and abundance.

  • Ecosystem Services: Identify and list examples relevant to microbiology.

  • List factors influencing microbial growth rates in natural habitats.

• Biofilms: Define biofilms and explain the relationship between their structure and function. Contrast them with microbial mats.

• Soil Particle Habitat: Sketch and label a habitat diagram emphasizing microbial presence.

• Microbial Environments:

  • Differentiate between surface and subsurface environments regarding their microbial inhabitants.

  • Freshwater Ecosystems: Describe and label freshwater ecosystems, addressing seasonal changes and human impacts.

• Eutrophication: Compare and contrast eutrophication processes in lakes and rivers.

• Microbial Growth in Habitats: Evaluate growth in freshwater vs. marine environments, identifying key influencing factors.

• Response to Oil Spill: Discuss microbial responses to the Deepwater Horizon oil spill.

• Marine Microbial Type Comparison: Contrast marine phototrophs and heterotrophs and discuss the abundance of marine viruses versus marine bacteria.

• Biological Oxygen Demand: Define biological oxygen demand (BOD) and productivity.

Microbial Ecology Overview

• Interactions: Microbial ecology studies interactions between microbes and other organisms and their environments, focusing on community dynamics and abiotic factors.

• Essential Activities: Microbes play vital roles that support life on Earth, shaping ecosystems and biogeochemical cycles.

Symbiotic Relationships

• Types of Symbiosis:

  • Parasitism: Harmful relationship for one organism.

  • Mutualism: Beneficial for both organisms involved.

  • Commensalism: One benefits, no harm or benefit for the other.

Ecosystems and Habitats

• Ecosystems: Comprised of plants, animals, microbes, and abiotic components.

• Habitats: Microbes can inhabit extreme environments where other organisms cannot survive. They constitute approximately 50% of Earth's biomass.

Microbial Diversity and Activity

• Microbial Activities: Dependent on species presence, population sizes, and environmental conditions. Nutrient availability and growth conditions like temperature and moisture significantly influence microbial activities.

• Population Dynamics:

  • Population: Microorganisms of the same species in a specific area.

  • Community: Interacting populations of different species in a shared environment.

  • Species Diversity: Expressed as species richness (number of different species) and species abundance (percentage representation of each species).

Microbial Guilds and Niche

• Guilds: Groups of metabolically related microorganisms that interact with other organisms and abiotic factors within a niche.

• Niche: Habitat shared by a guild that provides necessary nutrients and growth conditions.

Biogeochemistry and Nutrient Cycling

• Biogeochemistry: Study of biologically mediated chemical transformations within ecosystems.

• Nutrient Cycles: Transformations of important elemental cycles (e.g., carbon, nitrogen) driven by microbial activities.

Microenvironments and Biofilms

• Microenvironment: Immediate surroundings of microbial cells that undergo rapid physicochemical changes.

• Biofilms: Aggregated microbial cells adhered to surfaces, important for nutrient retention and protection.

  • Formed via attachment and gene expression that initiates matrix development via intercellular signaling (quorum sensing).

Freshwater and Marine Ecosystems

• Freshwater Habitats: Conditions are influenced by climate, with phytoplankton playing a crucial role in photosynthesis and respiration balance.

  • Seasonal stratification leads to differing oxygen levels, impacting species communities.

• Marine Environment: Characterized by low nutrient availability, higher salinity compared to freshwater, and significant microbial activity impacting global carbon cycles.

  • Eutrophication in coastal areas and effects of anthropogenic activities lead to dead zones.

Microbial Loop in Marine Ecosystems

• Relationship between phytoplankton, heterotrophic bacteria, and viruses is vital for nutrient cycling and carbon flow in oceanic systems.

  • Organic material (DOC) released through bacterial lysis and detritus contributes to the microbial food web.

Special Environments: Hydrothermal Vents

• Support specialized bacterial communities that thrive in extreme conditions using inorganic materials from the vents, critical for sustaining animal life in those ecosystems.

Learning Objectives in Microbial Ecology

Biotic and Abiotic Factors

• Recognize and analyze factors affecting microbial life, including biological (biotic) interactions among organisms, such as competition and predation, and environmental (abiotic) conditions like temperature, pH, salinity, and nutrient availability.

Symbiosis

• Define and provide comprehensive examples of various types of symbiotic relationships:

  • Parasitism: A relationship where one organism, the parasite, benefits at the expense of the host organism, leading to potential harm or even death of the host. Examples include tapeworms in animals and certain fungi that affect plants.

  • Mutualism: Both species involved in the interaction benefit, such as bees pollinating flowers while obtaining nectar, and mycorrhizal fungi assisting plant roots in nutrient uptake while receiving carbohydrates from the plants.

  • Commensalism: One organism benefits while the other is neither helped nor harmed, as seen with barnacles that attach to whales; the barnacles gain mobility to food-rich waters while the whale remains unaffected.

Purpose of Ecology

• Understand the overarching purpose of ecology, especially in relation to microbial life, and how microbial interactions influence community dynamics, ecosystem functions, and biogeochemical cycles crucial for sustaining life on Earth.

Ecosystem Components

• Define key ecological concepts including communities, which consist of various populations interacting in a given area; populations, which are groups of individuals of the same species; guilds, which are groups of metabolically similar organisms; niches, which represent the role an organism plays in its ecosystem; habitats, the physical environment where organisms live; and concepts of species richness (the number of different species within a community) and abundance (the total number of individuals per species).

Ecosystem Services

• Identify, categorize, and list examples of ecosystem services relevant to microbiology, including nutrient cycling, soil formation, waste decomposition, and the role of microbes in carbon sequestration.

Factors Influencing Microbial Growth Rates

• List and elaborate on crucial factors influencing microbial growth rates in natural habitats, such as nutrient concentrations, temperature, moisture levels, and the presence of other organisms (specific interactions or predation).

Biofilms

• Define biofilms as structured communities of microorganisms adhering to surfaces, often embedded in a self-produced matrix of polymeric substances. Explain the relationship between their structure and function, noting how their complex architecture allows for increased nutrient retention, protection from environmental stressors, and enhanced resistance to antimicrobial agents. Contrast biofilms with microbial mats, which are layered microbial communities found in aquatic environments.

Soil Particle Habitat

• Sketch and label a habitat diagram emphasizing the presence and role of microbes within soil, highlighting the interactions between soil structure, microbial diversity, and ecological functions within the soil ecosystem.

Microbial Environments

• Differentiate between surface and subsurface environments regarding their microbial inhabitants, explaining how these habitats affect the diversity and metabolic activities of the microbial communities present.

Freshwater Ecosystems

• Describe and label various types of freshwater ecosystems (lakes, rivers, wetlands) and discuss how seasonal changes such as stratification influence oxygen levels, nutrient dynamics, and species composition, as well as the impact of anthropogenic activities like pollution and damming.

Eutrophication

• Compare and contrast the processes of eutrophication in lakes and rivers, emphasizing the roles of nutrient runoff, algal blooms, oxygen depletion, and subsequent impacts on aquatic life.

Microbial Growth in Habitats

• Evaluate microbial growth conditions in freshwater versus marine environments, identifying key influencing factors such as salinity differences, nutrient availability, and temperature variations, thus affecting microbial biodiversity and productivity.

Response to Oil Spill

• Discuss the specific microbial responses to the Deepwater Horizon oil spill, highlighting the roles of hydrocarbon-degrading bacteria in bioremediation processes, the factors influencing their effectiveness, and implications for recovery of marine ecosystems.

Marine Microbial Type Comparison

• Contrast marine phototrophs (such as phytoplankton that utilize sunlight for photosynthesis) with heterotrophs (organisms that consume organic matter), and discuss the abundance of marine viruses in comparison to marine bacteria, noting their ecological significance in regulating microbial populations and nutrient cycling.

Biological Oxygen Demand

• Define Biological Oxygen Demand (BOD) as a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water, and explain its importance as an indicator of water quality and productivity in aquatic ecosystems.