Microbio 4000.01 - Environmental and Food Microbiology

included in Exam 4

ecosystem

consists of populations of species plus their habitat or environment

population

group of individuals of one species living in a common location

• each population of organisms fills a specific niche

Assimilation

Primary producers - convert carbon from CO₂ into biomass

Dissimilation

Decomposers - break down biomass

Wetland

region of land that undergoes seasonal fluctuations in water level

• fluctuation between dry/oxygenated and wet/anoxic states = complex microbial ecosystem that can filter the freshwater supply (filtered by microbes)

• has the highest biomass production of all ecosystem

oceans

microbes are the major producers in oceans - fix CO₂ into biomass

• this biomass feeds larger animals

Coastal ecosystems

contains photoautotrophs and heterotrophs

• highest conc. of nutrients and living organisms

deep ocean ecosystems

contains oligotrophs and lithotrophs

• extreme pressure, low temp, low conc. of nutrients and organisms

Biochemical oxygen demand

amount of oxygen removed from the water through aerobic

• increases when microbial levels increase due to

  • excess carbon cources

  • excess in other nutrients

Eutrophic lakes

have excess nutrients to support growth of both algae and bacteria in high densities - algal blooms

• eventually forms dead zones - kills fish and other animals

Biogeochemical cycle

carbon cycle and nitrogen cycle, etc.

carbon cycle

1. phototrophs and lithotrophs (autotrophs) fix CO₂ as biomass to produce O₂

2. oxygen is used by all heterotrophs to break down biomass into CO₂

most carbon is present in Earth’s crust → life relies on carbon in the form of atmospheric / oceanic CO₂

excess CO₂ is stored in the atmosphere as a reservoir and is produced faster than the biosphere can recycle

nitrogen cycle

bacteria and archaea are required for nitrogen cycle

1. N₂ in the atmosphere are fixed by microbes - now, the Haber Process accounts for 50% of all fixed nitrogen.

2. excess nitrates dissolve in bodies of water - creates dead zones

this cycle is the most disrupted biogeochemical cycle

wastewater treatment plants

removes organic carbon and nitrogen from water before it returns to aquatic systems and causes eutrophication and dead zones

1. filter out solids

2. use aerobic and anaerobic microbial descomposition

3. chlorination kills bacteria

fermented foods

biochemically modified microbial growth - is self-limiting

• predominantly from anaerobic fermentation

• lowers pH

• prevents growth of other harmful microbes

food spoilage

microbial changes that render a product unfit for consumption

• enzymatic processes - naturally break down

• chemical reactions with the environment - ex. oxidation rxns

• microbial processes - consume food and generate chemical products

food contamination

the presence of human pathogens in food, causing food-borne illness

physical means of preservation

colder temps - slow down growth but does not inhibit it