Microbiology Unit 2

2 types protozans

Trophozoite and cyst

Trophizoite

the active, motile feeding stage of protozoa found in hosts

Cyst

dormant, resting stage when conditions in the environment become unfavorable

Virulence factor in cysts

resistant to heat, drying, and chemicals

Trichomonas vaginalis

a common STD, does not form cysts and must be transmitted by intimate contact

Entamoeba histolytica

form cysts and are readily transmitted in contaminated water and foods

Entamoeba histolytica (disease)

Amoebiasis (intestinal and other symptoms)

Entamoeba histolytica (source)

humans, water and food

Balantidium coli (disease)

Balantidiosis (intestinal and other symptoms)

Balantidium coli (source)

waste of pigs, cattle, primates

Giardia lamblia (disease)

Giardiasis (intestinal distress)

Giardiasis lamlbia (source)

animals, water, and food

Trichonmonas vaginalis (disease)

trichomoniasis (vaginal symptoms)

Trichomonas vaginalis (source)

human (sex)

Cryptosporidium (disease)

Cryptosporidiosis (intestinal and other symptoms)

Cryptosporidium (source)

water, food

Helminths include:

tapeworms, flukes, roundworms

Where do disease-causing helminths spend part of their lives:

gastrointestinal tract

Enterobius (worm, host requirement, spread by)

pinworm; humans; close contact

Trichinella (worm, host requirement, spread to humans by)

trichina worm, pigs/ wild mammals, consumption of meat containing larvae

Taenia sodium (worm, host requirement, spread to humans by)

pork tapeworm; humans/swine; consumption of undercooked or raw pork

Diphyllobothrium (worm, host requirement, spready to humans by)

fish tapeworm; humans/fish; consumption of undercooked or raw fish

How do pinworms spread?

must transmit an infective form (egg or larva)

Life cycle of the pineworm

humans can ingest eggs that migrates to small intestine and become a worm; women lay their eggs in the anal area

What is the number one helminth infection in the US?

pinworm

Heterotroph

an organism that must obtain carbon in an organic form

Autotroph

an organism that uses inorganic CO2 as its carbon source (can convert CO2 to organic compounds)

Phototroph

microbe that photosynthesizes

Chemotroph

microbe that gets its energy from chemical compounds

Photoautotroph (energy source; carbon source; example)

sunlight; CO2; photosynthetic organisms (algae, plants, cyanobacteria)

Chemoheterotroph (energy source, carbon source, example)

metabolic conversion of the nutrients from other organisms; organic; protozoa, fungi, many bacteria, animals, humans

Chemoheterotroph: Saprobe (energy source; carbon source; example)

metabolizing the organic matter of dead organisms; organic; fungi, bacteria (decomposers)

Chemoheterotroph: Parasite (energy source, carbon, example)

utilizing the tissues, fluids of a live host; organic; various parasites and pathogens (bacteria, fungi, protozoa, animals)

Parasites:

derive nutrients from the cells or tissues of a living host

Parasites range from:

viruses to helminths

Intracellular parasites:

live within cells

Obligate parasites:

unable to grow outside of a living host

What are examples of obligate intracellular parasites?

leprosy bacillus and syphilis spirochete

Carbon

requirement are proteins, carbohydrates, lipids, and nucleic acid

Hydrogen

major element of water; hydrogen helps cells maintain their pH

Oxygen

is a major component of organic compounds such as carbohydrates, lipids, nucleic acids, and proteins; O2 makes up 20% of the atmosphere

Nitrogen

makes up 79% of the earth's atmosphere; structure of proteins, DNA, RNA, and ATP; some bacteria can utilize inorganic nitrogenous nutrients

Phosphate

Because it is found in ATP, it serves in cellular energy transfers

Sulfur

sulfur is an essential component of some vitamins and the amino acids methionine and cysteine

Type of passive transport

diffusion, facilitated diffusion, osmosis

Types of active transport

active transport, exocytosis, carrier-mediated transport

Simple diffusion (what goes through)

Gases: CO2, O2, N; small lipids

Facilitated diffusion (what goes through)

water, ions (NA+, K+)

What is cardinal temperature?

the minimum, optimum, and maximum temperatures at which an organism grows

Minimum temperature:

the lowest temperature that permits a microbe's continued growth and metabolism; below this temperature, its activities stop

Maximum temperature:

the highest temperature at which growth and metabolism can proceed before proteins are denatured

Optimum temperature:

an intermediate between the minimum and the maximum that promotes the fastest rate of growth and metabolism

Psychrophiles (optimum growth and capable of growth)

Their optimum temperature is below 15 degrees C

capable of growth at 0 degrees C

How do psychrophiles act in a refrigerator?

Storage at refrigerator temperatures causes them to grow rather than inhibiting them

Natural habitats of psychrophiles:

lakes, fungi, snowfields, polar ice, and the deep oceans

Are psychrophiles pathogenic?

No, psychrophiles are rarely pathogenic

Psychrotrophs

Grow slowly in the cold but have an optimum temperature between 15 and 30 degrees Celsius

Examples of psychotrophs

Staphylococcus aureus and Listeria monocytogenes (can cause food borne illness)

Mesophiles

contain the majority of medically significant microorganisms

grow at intermediate temperatures between 20-40 degrees Celcius

Where do mesophiles inhabit?

inhabit animals and plants as well as soil and water in temperate, subtropical, and tropical regions

What are the optimal temperature for human pathogens?

between 30 and 40 degrees Celsius

Thermoduric microbes

can survive short exposure to high temperature but are normally mesophiles

common contaminants of heated or pasteurized foods

Examples of thermoduric microbes?

heat-resistant endospore formers such as Bacillus and Clostridium

Thermophiles

grow optimally at temperatures greater than 45 degrees Celsius

Where do thermophiles live?

in soil and water associated with volcanic activity, compost piles, and in habitats directly exposed to the sun

Range that thermophiles can live in:

45 to 80 degrees Celsius

What temperatures can most eukaryotic forms can't survive?

above 60 degrees Celsius

What range can extreme thermophiles grow between?

80 to 121 degrees Celsius

What gases can influence microbial growth?

O2 and CO2

What gas has the greatest impact on microbial growth?

oxygen as it's an important respiratory gas and a powerful oxidizing agent

3 categories microbes fall into:

those that use oxygen and detoxify it

those that can neither use oxygen nor detoxify it

those that do not use oxygen but can detoxify it

How do microbes protect themselves against damage from oxygen by-products?

most cells have developed enzymes that can scavenge and neutralize reactive oxygen-by products (2 step process)

What two enzymes are required for breakdown of oxygen by-products

Superoxide dismutase and catalase

Describe the detoxification process

Superoxide ion is converted into hydrogen peroxide by superoxide dismutase, then hydrogen peroxide is converted into harmless water and oxygen by catalase

Aerobes

can use gaseous oxygen in their metabolism and possess the enzymes needed to process toxic oxygen products

Obligate aerobe

an organism that cannot grow without oxygen

Examples of aerobes

Most fungi, protozoa, and many bacteria, such as Bacillus species and Mycobacterium tuberculosis

Microaerophiles

are harmed by normal atmospheric concentrations of oxygen but require a small amount of it in metabolism

examples of microaerophiles

organisms that live in soil or water or in mammalian hosts, not directly exposed to atmosphere; helicobacter pylori

Facultative aerobes

do not require oxygen for metabolism but use it when it is present

examples of facultative anaerobes

Many gram-negative intestinal bacteria, staphylococci

Anaerobes

lack the metabolic enzyme systems for using oxygen in respiration

obligate anaerobes

also lack the enzymes for processing toxic oxygen and die in its presence

Examples of anaerobes

many oral bacteria, intestinal bacteria

Aerotolerant anaerobes

do not utilize oxygen but can survive and grow to a limited extent in its presence; they possess peroxides and superoxide

Examples of aerotolerant anaerobes

certain lactobacilli and streptococci, clostridial species

Capnophiles

organisms that grow the best at a higher CO2 tension than is normally present in the atmosphere

Examples of capnophiles:

Neisseria and streptococcus pneumoniae

What are acidic pH

values that decreases toward 0, the acidity increases

What are majority of organisms normal pH range

between pH 6 and 8

Acidophiles

organisms that thrive in acidic environments

Euglena mutabilis

grows in acid pools between pH 0 and 1

Thermoplasma

lives in coal piles at a pH of 1 or 2

Picrophilus

thrives at a pH of 7, but can live at a pH of 0

Alkalinophiles

organisms that thrive in alkaline conditions

Natronomonas

live in hot pools and soils up to pH 12

Proteus

can create alkaline conditions to neutralize urine and colonize and infect the urinary system

Osmophiles

live in habitats with high solute concentration

Halophiles

prefer high concentrations of salt

Falculative halophiles

remarkably resistant to salt, even through they do not normally reside in high salt conditions