BIOL229: Chapter 6

microbial growth

increase in population of microbes

growth requirements

use of variety of nutrients for energy needs

photo-

energy source from light

chemo-

energy source from chemical compounds

auto-

carbon source from carbon dioxide

hetero-

carbon source from organic compounds

aerobe

undergoes aerobic respiration

anaerobe

doesn’t use aerobic metabolism

obligate aerobe

oxygen is essential

obligate anaerobe

oxygen is deadly (O2 creates deadly byproducts)

facultative anaerobes

can maintain life with/without O2 (cell respiration, fermentation)

aerotolerant anaerobes

no aerobic metabolism, enzymes break down deadly O2

microaerophiles

require 2-10% O2 levels

nitrogen requirements

nitrogen fixation (N2 to ammonia), limiting factor, denitrification (soil nitrate to atmospheric N2)

temperature requirement

effect on protein (3D shape) and membrane

psychrophiles

cold environments

mesophiles

~37°C

thermophiles

hot environments

hyperthermophiles

very hot environments

neutrophiles

pH 6.5-7.5

acidophiles

acidic environments (<7 pH)

alkalinophiles

up to pH 11.5 (>7 pH)

water requirements

dissolve enzymes/nutrients required in metabolism

hypotonic

H2O into cell

hypertonic

H2O out of cell

obligate halophiles

grow in 30% salt

facultative halophiles

tolerates high salt environments

barophiles

organisms that live under extreme pressure

biofilms

closely related group of bacteria attached to a surface

quorum sensing

release of signals/transcription factors in biofilm (antibiotic resistance)

antagonism

work against each other

synergism

work together

symbiosis

depend on each other

defined

exact; all concentrations and quantities are known

complex

TSA/TSB, mixture of many things, composition unknown

selective

selected for a certain type, inhibits some, allows others to grow

differential

allows differentiation between different bacteria (by color/appearance)

anaerobic (media)

selects for obligate anaerobes

transport

preserves microbes during transfer

refrigeration

preservation for short periods of time

deep freezing

preservation for years

lyophilization

preservation for decades

generation time

time required for bacterial cell to grow and divide (dependent on chemical/physical conditions)

• low = faster, more efficient

• high = slower, less efficient

lag phase

testing if environment is suitable

log phase

exponential growth, dividing > dying

stationary phase

nutrients gone, threshold reached, dividing = dying

death

no nutrients, dividing < dying