Chapter 7- Elements Of Microbial Nutrition, Ecology, & Growth

chemical substances (nutrients) obtained from environment & used in cellular activities.

Makes up proteins, DNA, RNA, ATP.

(These are the primary sources of N for heterotrophs)

Microbes survive in their habitats through gradual adjustment of anatomy & physiology.

Is the process which chemical nutrients are acquired through the environment & used in cellular activities (Metabolism & growth)

Any element or molecule that must be provided to an organism.

Have to be obtained from the environment

1. Macronutrients
2. Micronutrients

• required in large qty. & play principle roles in cell structure & metabolism.
• Proteins & Carbs

• "Trace Elements"
• smaller qty. & involved in function & maintenance of protein structure.

manganese, zinc, & nickle

molecules that contain basic framework of Carbon & Hydrogen & usually products of living things.

• Methane, carbs, lipids, proteins, & nucleic acids

• Nearly always the product of living things.
• simple organic molecule - Methane (CH4)
• Large polymers - carbohydrates, lipids, proteins, & nucleic acids.

atom or molecule that contains a combination of atoms other than carbon and hydrogen.

inorganic form from the environment. Others require combo of organic & inorganic.

• organism that must obtain its carbon in an organic form. B/c organic carbon originates from organisms.
• Nutritionally dependent on other life forms

organism uses inorganic CO2 as its Carbon source.

• Converts CO2 into organic compounds not nutritionally dependent on other living things.

• Must be provided as a nutrient.
• Essential amino acids & vitamins.

1

CO2 is produced by respiration & used in photosynthesis. (p. 189)

Metals and their salts (magnesium sulfate, ferric

nitrate, sodium phosphate), gases (oxygen, carbon dioxide) and water

• 70% water
• proteins
• 96% of cell is composed of: Carbon, Hydrogen, Oxygen, Phosphorous, Sulfur, & Nitrogen)

• Autotroph
• Heterotroph pg. 189

• an organism that uses CO2, an inorganic gas as its carbon source
• Not nutritionally dependent on other living things

must obtain carbon in an organic form made by other living

organisms

Organic compounds that cannot be

synthesized by an organism because they

lack the genetic and metabolic

mechanisms to synthesize them

gain energy through

photosynthesis

gain energy from chemical

compounds

does not require energy;

substances exist in a gradient and move from

areas of higher concentration toward areas of

lower concentration

movement of molecules

down a concentration gradient

diffusion of water

through a selectively permeable

membrane

requires

a carrier protein to assist in

transport across the membrane

insures nutrients in low supply

are transported into the cell

– Uses membrane proteins and pumps – carrier-mediated

– Requires ATP

• endocytosis – liquids/solids engulfed into vessicle

– phagocytosis – large solids, whole cells

– Pinocytosis - liquids

all adaptations organisms make to

their habitat

– Temperature

– Oxygen requirements

– pH

– Osmotic pressure

– Barometric pressure

1. Minimum Temperatures
2. Maximum Temperature
3. Optimum Temperature

lowest temperature that

permits a microbe’s growth and metabolism

highest temperature

that permits a microbe’s growth and metabolism

promotes the fastest rate

of growth & metabolism

– S. aureus: 6-46°C

1. Psychrophiles
2. Mesophiles
3. Thermophiles

- optimum temperature below 15C (60F)

- capable of growth at 0C

- optimum temperature 20-40C (68-104F)

- most human pathogens

- optimum temperature greater than 45C

(113F)

Oxygen:

• As oxygen is used, it is transformed into toxic

products:

– Singlet oxygen (1O2), superoxide ion (O2

-), peroxide

(H2O2), and hydroxyl radicals (OH-)

• Most cells have developed enzymes that

neutralize these chemicals:

– Superoxide dismutase, catalase

• If a microbe is not capable of dealing with toxic

oxygen, it is forced to live in oxygen free

habitats

utilizes oxygen and can detoxify it

– Obligate aerobe – cannot grow without oxygen

– Facultative anaerobe – utilizes oxygen but can

also grow in its absence (through fermentation)

requires only a small

amount of oxygen

Does not utilize oxygen

lacks the enzymes to detoxify oxygen so cannot survive in an oxygen environment

• large intestine anaerobic, gas gangrene and tetanus are anaerobic bacilli

Every hour it doubles 3x

do not utilize oxygen but can survive and grow in its presence

grows best at higher CO2 tensions than normally present in the

atmosphere

• Majority of microorganisms grow at a pH

between 6 and 8

• Obligate acidophiles – grow at extreme

acid pH

• Alkalinophiles – grow at extreme alkaline

pH

Most microbes exist under hypotonic or

isotonic conditions

require a high concentration

of salt

do not require high concentration of solute but can tolerate it

when it occurs

– Staphylococcus aureus

– Common spoilage bacteria/fungi can thrive in

high sugar/salt containing foods

can survive under extreme

pressure and will rupture if exposed to

normal atmospheric pressure

two organisms live together in

a close partnership

obligatory, dependent; both

members benefit

commensal member

benefits, other member neither

harmed nor benefited

parasite is dependent and benefits;

host is harmed

organisms are free-living;

relationships not required for survival

members cooperate to produce a

result that none of them could do alone

• Microbes involved in soil nutrient cycling

actions of one organism affect

the success or survival of others in the same

community (competition)

production of inhibitory substances,

such as antibiotics

result when organisms attach to a

substrate by some form of extracellular matrix

that binds them together in complex organized

layers