Chapter 22: Physiology of Bacteria
five classes of bacteria based on their oxygen requirements
1. obligate (strict) aerobes 2. obligate (strict) anaerobes 3. microaerophilic bacteria 4. facultative 5. aerotolerant
light affects the growth of microbes in one of three ways:
1. some molds and yeasts favor darker areas to thrive because they don't have chlorophyll and don't use light to make food 2. some bacteria need light to create food 3. ultraviolet light will destroy some bacteria
autotrophic bacteria produce how much of Earth's oxygen?
20%
most bacteria that cause disease in humans thrive in
a neutral pH level many survive as long as the pH level of their cytoplasm doesn't change
thermophiles
bacteria that grow best at high temperatures between 40-70 degrees C (104-158 degrees f)
mesophiles
bacteria that prefer moderate temperatures and grow best between 25-40 degrees C (77-104 degrees F)
psychrophiles
bacteria that prefer the cold, thriving at temperatures between 0-25 degrees C (32-77 degrees F)
cyanobacteria
blue green bacteria that makes up the majority of scum found at the edge of ponds and lakes
facultative
can adjust to changes in oxygen levels
aerotolerant
can grow in the presence or absence of oxygen gains no benefits from presence of oxygen streptococcus pyogenes
obligate (strict) aerobes
can only live in the presence of oxygen as they need it to metabolize sugars for energy escherichia coli and campylobacter jejuni
obligate (strict) anaerobes
can only survive in environments devoid of oxygen oxygen is toxic to them and denature them listeria, clostridium botulinum, Clostidium perfringes
autotrophic bacteria obtain nutritional value from
carbon in carbon dioxide
small changes in osmotic pressure prompt bacterial cells to compensate by producing
certain amino acids to help maintain necessary water levels inside itself
large changes in osmotic pressure will separate the cell wall from the cell membrane and
collapse the bacterial cell inward, killing it
some heterotrophs are integral to the process of
fermentation
synergism
harmonious action of two microorganisms produce an effect neither could product alone
faculative
heterotrophic bacteria that can adapt to different sources of nutrients
strict (obligate) parasites
heterotrophic bacteria that completely depend on their living host for nutrients
strict (obligate) saprophytes
heterotrophic bacteria that only survive on dead or decaying organic matter
bacteria that cause diseases in humans need
high levels of moisture to grow this is why most bacterial diseases occur in the body's tissues
antagonism
inhibition of one microorganism's growth by the presence of another
molds and yeasts require
little moisture this is why most fungal diseases occur on the body's surface
all microorganisms require a certain amount of
moisture to survive
osmotic pressure is high in many embalming fluids creating what kind of environment?
non-hospitable for bacterial growth
commensalism
one organism gains some benefit while the host is left unharmed
autotrophic bacteria coverts carbon dioxide into nutrients via
photosynthesis
heterotrophic bacteria
requires complex organic food from a carbon source to grow and develop causes diseases in humans
microaerophilic bacteria
requires little free oxygen (2-10%) neisseria meningitis, N. gonorrhea, helicobacter pylori
autotrophic bacteria
self nourishing bacteria capable of growing in the absence of organic compounds
three types of heterotrophic bacteria
strict (obligate) saprophytes strict (obligate) parasites faculative
parasitism
symbolic relationship where the host is harmed and the parasites receives some benefit
mutualism
two different species live in close association to the mutual benefit of each other best kind- type of organism in yogurt
symbiosis
two or more different species of organisms live together in close association distinguished by the degree to which the host organism is harmed
