Chapter 26 Flashcards
Ecosystem
consists of populations of species plus their habitat or environment
population
is a group of individuals of one species living in a common location
niche
within an ecosystem, each population of organisms fills this
set of traits that enable living and enable living and interacting with others
assimilation
converts carbon from CO2 into biomass
dissimilation
breaks down biomass
physical factors limit microbial growth
oxygen, salinity, pH
biochemical oxygen demand (BOD)
is the amount of O2 removed from the water through aerobic respiration.
BOD goes up when the number of heterotrophic microbes increases, due to
Increase in organic compounds (sewage)
Increase in other nutrients (nitrates)
eutrophic
lakes (excessive nutrients present) have increased BOD
algal bloom
In a eutrophic lake, the nutrients support growth of algae and bacteria to high densities
Algal blooms increasingly threaten our water supplies worldwide.
Fertilizer runoff can cause algal blooms.
Algal blooms are associated with climate change.
Microbes in marine environments
Oceans are two-thirds of Earth with variations in depth.
Coastal ecosystems-high concentration of nutrients
Heterotrophs, photoautotrophs
Deep ocean ecosystems
lithotrophic
bacteria at thermal vents support life in the deep ocean
dead zones
fish and invertebrates can’t survive
mutualism
a relationship where species require each other for survival
synergism
a relationship where species grow better when together but can grow independently
commensalism
an interaction that benefits one partner species without harm to the other
amensalism
an interaction that harms one partner nonspecifically, without harming the other
parasitism
a relationship that benefits one member and causes harm to the other
gut microbes are being seen as an “organ” that influences the function of other body systems
immune system
endocrine system
nervous system
zoonotic
parasites may cause human diseases
Zoonotic diseases are infectious diseases of animals that can “cross over” into humans.
Animals are reservoirs; humans are typically dead-end hosts.
Rarely humans may become reservoirs of zoonotic diseases and person-to-person transmission occurs.
Example: H5N1 (avian) influenza
fermentation
Microbes turn sugars into acids and/or alcohol during glycolysis/fermentation.
Uses of fermentation
Food preservation
Acid, alcohol and ammonia produced by microbes
Improves digestibility of fibrous foods
Increases levels of some nutrients in food, such as vitamins (B12)
Improves food flavor by adding esters and sulfur compounds
alcoholic fermentation
yeasts ferment sugars to ethyl alcohol
enzymatic processes
naturally break down complex organic compounds to simpler ones
chemical reactions with the environment
such as oxidation reactions
microbial contamination
of food and their growth produces metabolites that contribute to food spoilage
dehydration and freeze-drying
physical methods of food preservation
removal of water prevents microbial growth
refrigeration and freezing
food preservation
refrigeration temp. slows microbial growth
freezing halts growth of most microbes, which might grow again when food is thawed
controlled or modified atmosphere
food preservation
food packed in low O2 or high CO2 limits growth and prevents abiotic oxidation
pasteurization
food preservation
short-term heat treatment decreases microbe number but does not affect food quality or texture
canning
food preservation
cooking food under pressure destroys the majority of microbial forms, including endospores, without harming food quality
food irradiation
food preservation
food is exposed to ionizing radiation , which sterilizes food and improves shelf life
unknown effects of radiation on food chemistry
hazards to workers involved in the irradiation process
acids
food preservation
lowering the pH of a food through fermentation or addition of acids
other organic compounds with antimicrobial activity
food preservation
cinnamon, cloves, and other plant-based compounds inhibit microbial growth
inorganic compounds
food preservation
salts, phosphate, nitrites, sulfite inhibit aerobic respiration
may have harmful effects on humans (toxicity, allergy)
wastewater
Human society contributes organic wastes (human sewage, industrial effluents) to the water cycle.
Introduction of these compounds into an ecosystem disrupts the ecological balance, leading to eutrophication and dead zones.
wastewater treatment
remove organic carbon and nitrogen from water before it returns to aquatic systems and the oceans.
