Chapter 7: Microbial Nutrition, Ecology, and Growth

what are all organisms composed of

matter

what is matter

something that takes up space and has mass

cells are 70 percent

water

what is 97 percent of dry cell weight due to

organic compounds with the most prevalent being proteins

what is 96 percent of a cell composed of

Carbon, Hydrogen, Oxygen, Phosphorous, Sulfur, and Nitrogen

how much of trace elements do cells require

only minute amounts

what is nitrogen fixation

the reduction of N2 to organic nitrogen

what can prokaryotes use that eukaryotes cannot

inorganic nitrogen that is not in forms available for eukaryotes

all naturally produce organic nitrogen is of what origin

prokaryotic origin

how is a nitrogen cycle carried out

by aerobes or anaerobes

what do aerobes use in a nitrogen cycle

a variety of strategies to protect nitrogenase from oxygen

what are carbon acquiring prokaryotes

autotrophs and heterotrophs

what are energy source prokaryotes

phototrophs and chemotrophs

what are electron source prokaryotes

lithographs and organotrophs

what are autotrophs

organisms that use CO2 as a source for carbon, and have energy acquired from other sources mostly the sun

what are heterotrophs

organisms that use a variety of carbon source and acquire energy from organic molecules

what are phototrophs

organisms that acquire nutrients from light

what are chemotrophs

organisms that obtain energy from oxidation of chemical compounds

what are lithotrophs

organisms that acquire nutrients from reduced inorganic substances

what are organotrophs

organisms that acquire nutrients by obtaining electrons from organic compounds

what is an example of a photoautotroph

cyanobacteria

what is an example of a photoheterotroph

heliobacteria in waterlogged soil, both photosynthesizing and absorbing organic

what is an example of a chemoorganoautotroph

methylomonas bacteria

what is an example of a chemoorganoheterotroph

e coli bacteria (yeasts, nonphotosynthetic microbes)

what is an example of a chemolithoautotroph

ocean dwelling nitrosopumilus maritimus (sulfur, hydrogen, iron oxidizing bacteria, methanogens, nitrifying bacteria)

what is an example of a chemolithoheterotroph

beggiatoa bacteria

(sulfur oxidizing)

if species gains a fitness benefit

it is positive

is the species incurs a fitness cost

it is negative

what are the types of microbial interactions

mutualism, cooperation, commensalism, amensalism, predation, parasitism, competition

what are the two interaction types

intraspecific and interspecific

what is intraspecific interactions

only competition, when two organisms of the same species interact

what is interspecific interaction

all other interaction types apart from competition

what do most microbes form

symbiosis

what is symbiosis

an association of two or more different species of organisms, a relationship in which two different organisms live together often interdependently

what is a symbiont

organism that has a specific relation with another that can be characterized as mutualism, parasitism, commensalism, or amensalism

what are the two types of symbionts

ectosymbionts and endosymbionts

what is an ectosymbiont

an organism located on the surface of another usually larger organism

what is an endosymbiont

organism located within another organism

what is mutualism

a symbiotic relationship between two or more species where both parties benefits. this can be written as +/+

when is something considered mutualism over cooperation

when its species fitness depends on the interaction, mutualism is essential to an organisms success

what is an example of a mutualistic relationship

tube worm bacterial relationships

what is cooperation

symbiosis, human microbiome, all microbes that "share our body space"

when is something generally considered cooperation

when the interaction is not species to species dependent for fitness

what is commensalism

a symbiotic relationship where one party benefits while the other is not affected. this can be written as +/0.

what does commensalism involve

spatial proximity, modification by one organism making it more suited for another organism

what are example of commensalism

microbial succession during spoilage of milk since fermenting bacteria promote growth of acid tolerant species, and formation of biofilms which the initial colonizer helps other microorganisms attach

what is amensalism

1 to 20 percent of culturable soil microbiota

what does amensalism do

produce geosmin which is a volatile substance that is the source of moist earth odor, and aerobically degrade many resistant substances like pectin, lining, and chitin

what does amensalism produce

vast array of antibiotics, other bioactive compounds, and antibiotic resistance genes

most amensalism are what

nonpathogenic saprophytes

what is predation

predation is a +/- relationship between the predator and prey species. the predator survives by killing and eating prey. predators are always in a higher trophic level than their prey

what is parasitism

parasitism is a +/- symbiotic relationship. in parasitism, one organism (the parasite) benefits, while the other (the host) is harmed. parasites often live exclusively on or in their host organism.

how is parasitism and predation different

parasites do not kill their host

what is an example of a parasitic relationship

parasitic ascomycota (zombie ants)

how do you make zombie ants

infection when an ant gets infected by a microscopic spore dropped by a mature fungus, death grip when the fungus grows and the ant bites onto a leaf until it eventually dies, fungal growth when the fungus consumes the ant, killing zone when the fungus releases spores and the spore create a 10 square feet killing zone to attack new ants

when are interactions stronger

when theres more overlap between individual's niches

when does interspecific competition occur

when two organisms try to acquire or use the same resource

what are the two possible outcomes of competition

share or not share

what occurs when sharing happens

resource partitioning, species reduce competition by reducing overlap in fundamental niches (natural solution and evolution required)

what can long term competition be a stimulus for

natural selection and evolution

long term interactions result in what

coevolution, in response to an evolutionary system, continuing adaptation Is needed in order for a species to maintain its relative fitness amongst the systems its coevolving with (red queen hypothesis)

what happens when not sharing occurs

competitive exclusion, occurs when two organism try to acquire or use the sam resource, on organism dominates, if the fundamental niches overlap fully, one species goes to extinction

what is an example of a complex interaction

fungal farming ants

what are biofilms

prokaryotes (eubacteria generally major players) can adhere to solid surfaces to form a slimy, slippery coat called a biofilm

what can biofilms do

they are complex permanently attached communities of prokaryotes can can cause environmental problems or chronic bacterial infections in humans

how are biofilms formed

microbes reversibly attach to conditioned surfaces, release polysaccharides, proteins and DNA to form the extracellular polymeric substances (EPS)

what do mature biofilms exhibit

heterogeneity, complexity, and are dynamic in community composition of microorganisms

what do biofilms and bacteriophages present

an important challenge to medical care because bacteria is found in medical devices

why are biofilms and bacteriophages difficult to treat

slime can be difficult to penetrate

what is quorum sensing

cell to cell communication mediated by small signaling molecules

what does quorum sensing do

couples cell density and intercellular communication to transcription regulation between prokaryotic species

what does quorum sensing play an essential role in

in the regulation of genes whose products are needed for the establishment of virulence, symbiosis, biofilm production, and morphological differentiate in a wide range of bacteria, (archaea, and even some eukaryotes)

how do most bacterial and archaeal cells reproduce

by binary fission

what are three phases of reproduction for Domain Eubacteria and Archaea

period of growth, chromosome replication and partition, and cytokinesis

what makes cytokinesis more complicated

cell walls

what is septation

formation of a cross wall between two daughter cells

what are the steps of cytokinesis

selection of site for septum, assembly of Z ring (composed of protein FtsZ), assembly of cell wall synthesizing machinery, and constriction of cell and septum formation

what does protein FtsZ do

forms Z-ring

what is Z ring linked to

the plasma membrane (division of cell wall linked to plasma membrane)

what do associated proteins do in cell wall growth and cell shape

assure the z ring is in the center of the cell

what occurs after the z ring is in the center of the cell

cell wall synthesizing machinery is assembled

what results in division

constriction of the z ring

what does bacterial growth refer to

population growth rather than growth of individual cells, increase in cell number and increase in cell size

how many phases are there to bacterial growth

5

what occurs in the 1st phase, lag phase

cell synthesizing new components, for example to replenish spent material or to adapt to a new medium or other conditions, it can vary in length can be very short or even absent

what occurs in the 2nd phase, exponential phase

(log phase) rate of growth and division is constant and maximal, nutrient availability is not limiting, and the population is most uniform in terms of chemical and physical properties

what occurs in the 3rd phase, stationary phase

closed system population growth eventually ceases, total number of viable cells remain constant and active cells stop reproducing or reproductive rate is balanced by death rate, the population may cease to divide but remains metabolically active

what are possible reason for the stationary phase

nutrient limitation, limited oxygen availability, toxic waste accumulation, critical population density is reached

what occurs in the 4th phase, death phase

number of viable cells declines exponentially, cells dying at a constant rate, detrimental environmental changes such as nutrient deprivation, and build of toxic wastes cause irreparable harm to the cells

what occurs in the 5th phase, long term stationary phase

doesn't occur for all populations, process marked by successive waves of genetically distinct variants, natural selection occurs, bacterial population continually evolves

what is generation (doubling) time

time required for the population to double in size, varies depending on species of microorganisms and environmental conditions

what is the equation for calculating population size over time

Nf = (Ni)2^n, Nf is total number of cells in the population, Ni is starting number of cells, and exponent n denotes generation time

what do most bacterial organisms need

moderate environmental conditions

many exceptional extremophiles (archaean) are what

prokaryotic

what environmental factors affect growth rate

temp, oxygen concentrations, pH, osmotic pressure, barometric pressure, and radiation

what can some microbes not do

regulate their internal temperature because they contain enzymes that have functionally optimal temperature ranges and bacteria exhibit distinct cardinal growth temperatures due to temperature

what are some adaptations of thermophiles

stabilized protein/enzyme structures because of increased number of H bonds where their membrane is stabilized by more saturated, more branched and higher molecular weight lipids and ether linkages

what does growth in presence of different oxygen concentration depend on

a microbes metabolic processes, electron transport chains, and terminal electron acceptor used

what is an aerobe

grows in presence of atmospheric oxygen which is 20 percent O2