Week 3 Flashcards
What are microorganisms?
- the oldest form of life on Earth
- They have evolved to preform critical functions that sustain the biosphere
How old is the Earth?
4.6 billion years old
when did microbial cells first appear?
between 3.8 and 4.3 billion years ago
During the first 2 billion years of earth…
its atmosphere was anoxic (O2 was absent), and only nitrogen carbon dioxide and a few other gases were present
What was the Earth’s origin like
sterile and anoxic
what was present 3.8 billion years ago?
bacteria and archaea
what caused Earth to become oxygenated over time
- The evolution of phototrophic bacteria called cyanobacteria
When were current levels of atmospheric O2 achieved?
500-800 million years ago
phototrophic microorganisms
organisms that harvest energy from sunlight
When did phototrophic microorganisms evolve?
within 1 billion years of the formation of Earth
what were the first phototrophs?
anoxygenic
Cyanobacteria
oxygen-producing phototrophs
When did cyanobacteria evolve
nearly a billion years later and began the slow process of oxygenating Earth’s atmosphere
Microbial Mats
Microbial Mats: The structures that these early phototrophs lived in structures and are still found on Earth today
Multicellular Life:
Evolved after the oxygenation of Earth’s atmosphere, culminating in the plants and animals we know today
How long have plants and animals existed?
about half a billion years
How much of life’s history was exclusively microbial?
80%
What can Earth be considered?
A microbial planet
Three major lineages of microbial cells:
- The Bacteria
- The Archaea
- The Eukarya
How many genes are present in cells of all 3 domains
approx 60 genes
- last universal common ancestor (LUCA):
- examination of the common genes reveals that all three domain have descended from a common ancestor
- Microorganisms fill every habitable environment on Earth
what constitutes a major fraction of global biomass?
Microbials
How many stars are there in space?
7x10 to the power of 22 stars
How many microbial cells are there on Earth?
2x10 to the power of 30 microbial cells
How much nitrogen and phosphorus are present within microbial cells
almost 4 times that in all plant and animal cells combined
Extremophiles
properties define the physiochemical limits to life
Microbes are abundant in:
- volcanic hot springs
- glaciers
- ice-covered regions
- high-salt environments
- extremely acidic or alkaline habitats
- deep in the sea
- deep in the earth at extremely high pressure
Metabolic activities
metabolic activities of microorganisms can see the change the habitats which they live, both chemically and physically, and these changes can affect other organisms
How can we predict and minimize the effects of human activity on the biosphere that sustains us?
only by understanding microorganisms and microbiology
why are microorganisms contributions easy to overlook?
because of their small sizes
How many microbial genes are present for every human gene?
more than 200 microbial genes
what do microbial genes do
provide benefits and services that are essential to human health
What are microbes important to?
myriad issues of global importance to humans including climate change, agricultural productivity, and even energy policy
Microbiologists study
- microorganisms function
- Advanced human health and welfare
- in food and agriculture
- produce valuable human products
- generate energy
- clean up the environment
Microbio has fuelled advances in:
- medicine such as vaccination and antibiotic therapy
- advances in engineering such as water and wastewater treatment
- advances in food safety such as pasteurization
- a better understanding of how microorganisms are transmitted
Agriculture
- the cycling of nitrogen, sulfur, and carbon
Legumes
- a diverse family of plants that include major crop species such as soybeans, peas, and lentils, among others
What do legumes live in close association with?
- legumes live in close association with bacteria that form structures called nodules on their roots
What does the bacteria that is in close relations with leagues do?
- these bacteria convert atmospheric nitrogen into ammonia through the process of nitrogen fixation. is the major nutrient found in fertilizer
what does the rumen contain
dense and diverse community of symbiotic microorganisms that digest and ferment cellulose
What other things are ruminants
- many domesticated and wild herbivorous mammals - including deer, bison, camels, giraffes, and goats
what does the GI tract rely on
- rely on microbial partners for our nutrition
how many microbial cells foes the colon contain
- the colon contains about 10 to the power of 11 microbial cells per gram of colonic contents
why do humans rely on our gut microbiome for this purpose
- human enzymes lack the ability to break down complex carbohydrates (which can represent 10-30% of food energy)
where are microbial cells low?
- low in the very acidic (pH 2) stomach (about per gram)
where do microbial cells increase
- increase to about per gram near the end of the small intestine (pH 4-5)
Where do maximal microbial cells live?
- Reach maximal numbers in the colon (pH 7)
What do microbial cells do?
- in the digestion of complex carbohydrates
- synthesize vitamins and other nutrients essential to host nutrition
- The gut microbiome develops from birth, but it can change over time with the human host
What food are microorganisms present in?
- food spoilage
- foodborne disease
- improve food safety and preserve foods
- for baking
- for the production of alcoholic beverages
what is a large focus in the food industry
- microbial food safety and prevention of food spoilage is a major focus of the food industry and a major cause of economic loss every year
what foods have microbial production
- microbial production of lactic acid in cheeses, yogurt, and buttermilk are all produced by microbial fermentation of dairy products
what does microbial lactic acid do?
improves the shelf life of fermented products and prevent the growth of foodborne pathogens
Lactic acid definition
- Lactic acid - producing bacteria are used to produce a variety of sour-tasting foods, including sauerkraut, kimchi, pickles, and even certain sausages even the production of chocolate and coffee rely on microbial fermentation
Industrial microbiology
- the use of microorganisms as tools for major industries such as pharmaceuticals and brewing
bioreactors called fermentors make large amounts of products:
- antibiotics
- enzymes
- alcohol
- certain other chemicals
Biotechnology
- employs genetically engineered microorganisms to synthesize products of high commercial value, such as insulin or other human proteins, usually on a small scale
Natural gas (methane)
product of the anerobic metabolism of methanogenic Archaea
what alcohol is a major fuel supplement
ethyl alchohol (ethanol) major fuel supplement, which microbial fermentation of glucose obtained from carbon-rich feedstocks such as sugarcane, corn, or rapidly growing grasses
what should biofuels do?
- biofuels should help cool our planet and are one facet of the “green revolution” many countries support today
Wastewater treatment
waterborne diseases such as cholera and typhoid (major killer before the blossoming of microbiology
Bioremediation: microbes can be used to clean up industrial pollution into nontoxic forms:
- Spilled oil
- Solvents
- Pesticides
- Heavy metals
- Other environmentally toxic pollutants
Where are biofilms:
- in pipes and drains can cause fouling
- blockages in factory settings and pipelines
- in sewers
- in water distribution systems
- ship’s hulls can caused marked reductions in speed and efficiency
- in tanks that store oil and fuel, leading to spoilage of these products
- on implanted medical devices can cause infections that are extremely difficult to treat
Who is Robert Hooke
- english mathematician and natural historian
What did Robert Hooke write?
his famous Micrographia, the first book devoted to microscopic observations
Hooke illustrated many microscopic images including the fruiting structures of molds this was the first known description of microorganisms
Microscopy
- bright-field
- phase-contrast
- differential interference contrast
- dark-field
- Fluorescence
Numerical Aperture
- The limit of resolution for a light microscope is a function of the wavelength of light used and the light-gathering ability of the objective lens
What is there a correlation between
between the magnification of a lens and its numerical aperture
lenses with higher magnification….
typically have higher numerical apertures
Oil immersion lenses
Immersion oil increases the light-gathering ability of a lens; that is, it increases the amount of light that is collected and viewed by the lens.
