microbial applications (environment and food) Flashcards
what is assimilation and what types of microbes act on this process?
converts carbon from CO2 into biomass
type of microbe: producers
what do ecosystems in balance do?
produce food webs that equally balance assimilation and dissimilation
what is dissimilation and what types of microbes act on this process?
breaks down biomass
type of microbe: decomposers
what 3 factors mediate microbial growth in all environments?
1- oxygen
2- salinity
3- pH
biochemical oxygen demand (BOD)
the amount of O2 removed from the water through aerobic respiration
2 major factors that increase BOD
it increases when microbial levels increase
1- increases in organic compounds (sewage)
2- increases in other nutrients (nitrates)
what is the effect on the environment when BOD increases
eutrophic lakes (have excess nutrients to support growth of algae and bacteria in high densities (algal blooms)
Dead zones
when sewage or nitrates are introduced into the ocean there are hypotoxic regions of the ocean devoid of fish and intervertebraes
primary producers on land? in water?
plants, microbes
in the ocean where are you most likely to find phototrophs and heterotrophs?
coastal ecosystems
in the ocean where are you most likely to find oligotrophs and lithotrophs
deep ocean ecosystems
oligotrophs
can survive in areas of low nutrients
what do we appreciate about soil?
it is essential dead organic matter from plants, contains the densest sources of microbes on earth
what are the primary producers and decomposers in soil?
plants are the producers (co2 into biomass) fungi and bacteria are the decomposers (break down biomass) which feeds protists and nematodes which feed larger invertebrates and vertebrates
what are the sources of O2 and CO2 in soil?
respiration that occurs underground for CO2 and O2 comes into play through producers fixing CO2
wetlands
region of land that undergoes seasonal fluctuations in water level
what do we appreciate about wetlands?
wetlands produce biomass at the highest rate of all ecosystems due to the constant access to rich minerals, oxygen, and sunlight all at once
what are the carbon and nitrogen cycles?
biogeochemical cycles because they depend on both biotic (living components) and abiotic (non-living component) processes
carbon cycle (roughly)
life relies on carbon in the form of atmospheric or oceanic CO2.
phototrophs and lithotrophs will fix CO2 which create biomass that produces O2 which is then used by heterotrophs to break it back down into CO2, excess goes into atmospheric stores as a reservoir or sink
nitrogen cycle (roughly)
accessible nitrogen is in the atmosphere as N2 but needs to be fixed by microbes (bacteria and archaea) into a usable form which requires a lot of energy.
humans do what
act as a rapid decomposer ( breaking down biomass) and produce excess Co2 that the producers are unable to recycle back into biomass.
why is excess Co2 a problem
it is being stored which is accumulating faster than the biosphere can recycle heating the earth
what forms of life can fix N2?
bacteria and archaea
why is the Harber process amazing for agriculture but disastrous for the nitrogen cycle?
amazing- mass-produce fertilizers?
disastrous- large excess of nitrates dissolved in lakes, rivers, and oceans permits algal blooms then dead zones, nitrogen cycle is the most disrupted
fermented goods
biochemically modified by microbial growth
what are foods best fermented under?
anaerobic conditions
3 main benefits of food fermentation
1- preserves food
2- improves digestibility
3- adds nutrients and flavor
what waste product of fermentation reacts with milk to form solids? and what makes up these solids
bacterial lactic acid; coagulated milk protein- curd
Milk fermentation
converts a liquid solution of proteins and carbohydrates to a semisolid (yogurt) or solid (Cheese) product
aging
incubating under controlled humidity for months to develop flavor
brining
treated with concentrated salt to limit bacterial growth and develop flavor
ripening
inoculation with mold
major benefits of soybean fermentation
it allows the indigestible parts of the soybean to be digested increasing the availability of its proteins and nutrients
alcoholic beverages = ?
yeast fermentation
what are the products fermented by yeast in beer?
fermenting grains
what are the products fermented by wine in beer?
fermenting fruit
what are the resulting chemicals released by fermentation?
glucose -> ethanol + CO2
alcohol dehydrogenase
produced by the liver breaks down the alcohol produced by our gut microbiota
what are the major classes of food change?
1- enzymatic processes
2- chemical reactions with the environment
3- microbiological processes
when do food changes contribute to food spoilage?
microbial changes that render a product unfit for consumption
1- enzymatic processes
after plants and animals die, organic molecules begin to break down
2- chemical reactions with the environment
most commonly oxidation by air, which can generate rancid odors
3- microbiological processes
microbes on the surface begin to consume it, generating a wide range of chemical products
food contamination
presence of human pathogens in food
physical food preservation methods
dehydration or freeze-drying
refrigeration or freezing
modified atmosphere
pasteurization
canning
ionizing radiation
food preservation
methods to prevent spoiling due to microbial contamination
chemical food preservation methods
salt
sugar
acids
other organic compounds
inorganic compounds
why do we care about treating human and industrial/agricultural waste?
all water will eventually end up back in the water cycle, so it is critical to minimize contamination of aquatic systems.
highly concentrated organic waste is oxidized faster than oxygen, causing hypotonic conditions due to high BOD
three treatments in wastewater treatment plants
primary- filtering of solids
secondary- aerobic and anaerobic microbial decomposition
tertiary-chlorination and other chemicals
