Micro ch 4--Dynamics of Prokaryotic Growth

Binary fission

split in half, how they repicated

Generation time

the time required for a cell to divide in half; anywhere from 20 minutes to 3 hours

biofilms

communities of bacteria surrounded and encased in mesh-like plymers; form channels for nutrient and waste movement; protection from disinfectants and medicines to become more of a disease threat

bacterial growth curve and phases

number of bacteria vs a unit of time

lag phase, log phase, stationary phase, and decline phase

lag phase

slow increase but little reproduction

log phase

lot of active reproduction

stationary phase

nutrients are exhausted, waste products build and reproduction slows

decline phase

cells start to die due to no nutrients and too much waste

psychophiles

microbes that grow at cold temps

mesphiles

microbes that grow between room temp and body temp; 25-45 C

termophiles

microbes that grow in hot temps

acidophiles

microbes that grow at low pH

alkaliphiles

microbes that grow at high pH

neutrophiles

microbes that grow at pH of 7

halophiles

microbes that require salt/can grow in the presence of a lot of salt

how does refridgeration affect bacteria

slows microbe reproduction; used to preserve food and microbial cultures

obligate aerobes

require oxygen

facultative anaerobes

with or without oxygen

obligate anaerobes

harmed by oxygen

microaerophiles

require less oxygen than the amount found in the air

aerotolerant microbes

cant use oxygen, but is not harmed by it

three toxic oxygen containing molecules

superoxide free radical (O2)—found in the immune system, kills ingested bacteria,

hydroxide (OH)—capable of killing microbes, and

Hydrogen peroxide (H2O2)—disinfectant

plasmolysis

shrinkage of the cell membrane caused by water loss

photoautotrophs

use light at energy source and CO2 as carbon source

plants, algae, some bacteria

photoheterotrophs

use light as energy source and organic compounds as carbon source

green and purple bacteria

chemoautotrophs

inorganic substances for energy source (sulfer, hydrogen, ammonia, iron) and CO2 as carbon source

unusual bacteria

chemoheterotrophs

used glucose as energy and carbon source

most bacteria, all fungi, protozoa, and animals

culture medium

nutritious material that microbes grow in or on

culture

when microbes are growing in a container of medium

agar

jelly-like polysaccharide taken from algae, microbes grow on surface

complex medium

the exact chemical comp varies from batch to batch

chemically defined medium

exact chemical comp is known

selective media

causes certain microbes to grow while suppressing others

differential media

reacts with different microbes to grow while supressing others

enrichment culture

provides conditions that enhance the growth of a particular species

3 ways to preserve a culture

refridgeration

deep freezing— -50 to -95 C

lyophilization—freeze drying

5 ways to measure the growth or population number

hemocytometer

coulter counter and flow cytometer

plate counts

most probable number

turbidity

hemocytometer

counts cells using a gradient, pick some square, count and average

coulter counter and flow cytometer

a machine that has a laser beam, counts how many times a cell blocks the light; computer counts

plate counts

determine the number of colonies on a petri dish

most probable number

estimate based on dilutions and cloudiness

turbidity

cloudiness seen in a vial of bacteria