Microbiology - Ch. 6-10

Essential nutrient

Any substance that must be provided to an organism

Macronutrients

Required in large quantities and play principal roles in cell structure and metabolism:

• Carbon, hydrogen, and oxygen

Micronutrients

Present in smaller amounts and are involved in enzyme function and maintenance of protein structure:

• Trace elements; manganese, zinc, nickel

Organic nutrients

• Contain carbon and hydrogen atoms and are usually the products of living things

• Simple organic molecules such as methane

• Large polymers (carbohydrates, lipids, proteins, nucleic acids)

Inorganic nutrients

• An atom or simple molecule that contains a combination of atoms

• Metals and their salts (magnesium sulfate, ferric nitrate, sodium phosphate)

• Gases (oxygen, carbon dioxide) and water

• Found in the earth’s crust, bodies of water, and the atmosphere

Heterotroph vs. Autotroph vs. Phototroph vs. Chemotroph

Heterotroph: must obtain its carbon in an organic form

Autotroph: uses inorganic CO2 as its carbon source

Phototroph: photosynthesizes

Chemotroph: gets energy from chemical compounds

Autotroph Energy Sources: Photoautotrophs vs. Chemoautotrophs

Photoautotrophs:

• Photosynthetic

• Produce organic molecules using CO2 that can be used by themselves and by heterotrophs

Chemoautotrophs:

• Chemoorganic autotrophs: use organic compounds for energy and inorganic compounds as a carbon source

• Lithoautotrophs: rely totally on inorganic minerals and require neither sunlight nor organic nutrients

Heterotroph Energy Sources

Parasites:

• Derive nutrients from the cells or tissues of a living host

Parasites: pathogens vs. Ectoparasites vs. Endoparasites vs. Obligate parasites

• Pathogens: cause damage to tissues or even death

• Ectoparasites: live on the body

• Endoparasites: live in the organs and tissues

• Obligate parasites: unable to grow outside of a living host

Carbon

Proteins, carbohydrates, lipids, and nucleic acids

Hydrogen

• Helps cells maintain their pH

• Useful for forming hydrogen bonds between molecules

• Serves as a source of free energy in respiration.

Oxygen

Major component of organic compounds such as carbohydrates, lipids, nucleic acids, and proteins

• Plays an important role in the structural and enzymatic functions of the cell.

Nitrogen

Indispensable to the structure of proteins, DNA, RNA, and ATP

Phosphorus

• Key component of nucleic acids and is therefore essential to the genetics of cells and viruses

• Found in ATP, serves in cellular energy transfers

Sulfur

Essential component of some vitamins (vitamin B1) and the amino acids methionine and cysteine

How Microbes Eat: Transport Mechanisms

• Transport of necessary nutrients occurs across the cytoplasmic membrane, even in organisms with cell walls

Transport Processes in Cells: Passive vs. Active

Passive:

1. Simple diffusion

2. Facilitated diffusion

Active:

1. Carrier-mediated active transport

Cardinal temperatures: Minimum vs. Maximum vs. Optimum temperature

1. Minimum: lowest temperature that permits growth and metabolism

2. Maximum: highest temp. that permits growth and metabolism

3. Optimum: intermediate between the minimum and the maximum that promotes fastest rate of growth and metabolism

Psychrophiles

Obligate with respect to cold

• Natural habitats of psychrophilic bacteria, fungi, and algae are lakes, rivers, snowfields, polar ice, and the deep ocean

• Rarely pathogenic

Mesophiles

• Majority of medically significant microorganisms

• Staphylococcus aureus is psychotolerant - can grow in fridge

Thermoduric Microbes

• Can survive short exposure to high temperatures but are normally mesophiles

• Common contaminants of heated or pasteurized foods

• Ex: heat-resistant endospore formers (Bacillus and Clostridium)

Thermophiles

• Grow optimally at high temperatures

• Live in soil and water associated with volcanic activity, compost piles, and in habitats directly exposed to the sun

Gases; O2

O2 is an important respiratory gas and a powerful oxidizing agent

How Microbes Process Oxygen: Singlet oxygen (O) vs. Superoxide ion (O2-) vs. Hydrogen peroxide (H2O2) vs. Hydroxyl radical (OH-)

• Singlet oxygen (O): extremely reactive molecule that can damage and destroy a cell by the oxidation of membrane lipids

  • Phagocytes

• Superoxide ion (O2–): highly reactive

• Hydrogen peroxide (H2O2): toxic to cells and used as a disinfectant

• Hydroxyl radical (OH–): also highly reactive

How do Microbes Protect Themselves Against Damage from Oxygen By-products?

Most cells have developed enzymes that scavenge and neutralize reactive oxygen by-products

Superoxide ions are converted into ________ ________ by ________ ________

Hydrogen peroxide; Superoxide dismutase

Hydrogen peroxide is converted into harmless ________ and ________ by ________

Water and oxygen; catalase

Aerobes use ….

Examples?

Gaseous oxygen in their metabolism and possess the enzymes needed to process toxic oxygen products

• Ex: Most fungi, protozoa, and many bacteria, such as Bacillus species and Mycobacterium tuberculosis

Microaerophiles are harmed by …

Examples?

Normal atmospheric concentrations of oxygen but require a small amount of it in metabolism

• Ex: Organisms that live in soil or water or in mammalian hosts, not directly exposed to atmosphere; Helicobacteri pylori, Borrelia burgdorferi

________ ________ do not require oxygen for metabolism but use it when it is present. Examples?

Facultative anaerobes

Ex: Many gram-negative bacteria, staphylococci

__________ lack the metabolic enzyme systems for using oxygen in respiration. Examples?

Anaerobes; many oral bacteria, intestinal bacteria

________ ________ do not utilize O2 but can survive and grow to a limited extent in its presence

Aerotolerant anaerobes

________ are organisms that grow best at a higher CO2 tension than is normally present in the atmosphere; Example?

Capnophiles; Steptococcus pneumoniae

pH is the degree of ________ or ________ of a solution. What is the pH of pure water? Physiological? Decreasing toward 0 means …. Increasing …

Acidity or alkalinity; 7; 7.4; Acidity increases; Alkalinity increases

Helicobacter decomposes urine and creates ________ conditions

Alkaline

Osmophiles live in habitats with ________ solute concentration

High

________ prefer high concentrations of salt

Halophiles

Obligate vs. Facultative halophiles

• Obligate halophiles: Halobacterium and Halococcus grow optimally at solutions of 25% NaCl but require at least 9% NaCl

• Facultative halophiles: remarkably resistant to salt, even though they do not normally reside in high salt environments

• Staphylococcus aureus can grow on NaCl media ranging from 0.1% to 20%

Nonphotosynthetic microbes tend to be damaged by …

The toxic oxygen products produced by contact with light

________ use visible light rays as an energy source

Phototrophs

Barophiles thrives in ________ pressure zones

High

Symbiosis and Symbionts

Two organisms live together in a close partnership; members of a symbiosis

What are the 3 types of symbiosis?

Mutualism, commensalism, and parasitism

Symbiosis: Mutualism

Organisms live in an obligatory but mutually beneficial relationship

Symbiosis: Commensalism

Partner called the commensal receives benefits, while its partner is neither harmed nor benefited

Symbiosis: Parasitism

The host organism provides the parasitic microbe with nutrients and a habitat; host suffers from the relationship

Antagonism

Association between free-living species that arises when members of a community compete

Ambiosis

Producing inhibitory compounds (antibiotics) into the surrounding environment which inhibit or destroy another microbe in the same habitat

What is the interrelationship between two organisms that benefits them but is not necessary for survival called?

Synergism

Binary fission is when …

One cell becomes two

Steps in Binary Fission

1. A young cell

2. Chromosome is replicated and new and old chromosomes move to different sides of cell

3. Protein band forms in center of cell

4. Septum formation begins

5. When septum is complete, cells are considered divided. Some species will separate completely, while others remain attached, forming chains or doublets

What is generation?

Increasing the population by a factor or two

A predictable pattern of a bacterial population growth in a closed system is a …

Growth curve

Stages in normal grown curve (4)

1. Lag

2. Exponential growth

3. Stationary growth

4. Death phase

The ________ phase is a “flat” period of growth due to:

Lag; Cells not multiplying at max rate, pop of cells is sparse or diluted that sampling misses them

The ________ growth (________) phase is when the growth curve increases geometrically

Exponential; logarithmic/log

The ________ growth pase is when cell birth and cell death rates are equal, cell division rate is slowing down

Stationary

The ________ phase is when cells begin to die at an exponential rate

Death

Viable nonculturable state is when ….

Many cells in a culture in the death phase stay alive but are dormant

Microbes in the exponential growth phase are more vulnerable to …

Antimicrobial agents and heat

Cells in the growth phase are more vulnerable to conditions that disrupt …

Cell metabolism and binary fission

In general, actively growing cells are more vulnerable to …

Growth inhibition and destruction

A clear nutrient solution becomes …, or cloudy, as microbes grow in it

Turbid

Metabolism pertains to all …

Chemical reactions and physical workings of the cell

Anabolism vs. Catabolism

Anabolism: Requires energy input

Catabolism: Releases energy

Anzymes are biological …

Catalysts

Catalysts increase the ________ of chemical reactions and are not …

Rate; consumed in the process

Holoenzyme vs. Apoenzyme vs. Cofactors

• Holoenzyme: is a combination of a protein and one or more cofactor

• Apoenzyme: protein portion of a holoenzyme

• Cofactors: either organic molecules called coenzymes or inorganic elements (metal ions)

The need of microorganisms for ________ ________ arises from their roles as cofactors for enzymes. Examples?

Trace elements; iron, copper, magnesium, zinc, cobalt, selenium, etc

________ ________ work in conjunction with an apoenzyme

Organic compounds

Many coenzymes are derived from ________

Vitamins

Activity of enzymes are influenced by …

The cell’s environment

Changes in the normal conditions cause enzymes to be …

Unstable or labile

Denaturation is when … causes …

Weak bonds that maintain the native shape of the apoenzyme are broken; distortion

Enzyme repression vs. Induction

1. Enzyme repression

   • Genetic apparatus responsible for replacing enzymes is automatically suppressed

2. Enzyme induction

   • Enzymes appear (are induced) only when suitable substrates are present

E. coli enables the organism to utilize …

A variety of nutrients

Energy is stored as …

ATP

Exergonic vs. Endergonic reactions

Exergonic - releases energy as it goes forward

Endergonic - require input of energy

Energy released during exergonic reactions is stored in … in ATP

High-energy phosphate bonds

Aerobic respiration utilizes … relies on …

Glycolysis, Krebs cycle, and the respiratory chain; free oxygen as the final electron and hydrogen acceptor

Anaerobic respiration involves … uses …

Glycolysis, Krebs cycle, and the electron transport chain; ocidized compounds as terminal electron acceptors

Fermentation is the …

Incomplete oxidation of glucose

Fermentation: Oxygen is ________

Not required

Fermentation: Organic componds are …

Terminal electron acceptors

A chain of special redox carriers are embedded in the …

Cytoplasmic membrane in bacteria

In the final step of the aerobic respiration, … producing water

Oxygen accepts electrons and hydrogen

Aerobes have ________ enzymes to deal with toxic oxygen products (Steptococcus)

Neutralizing

The terminal step in anaerobic respiration utilizes … rather than free oxygen, as the final electron acceptor

Inorganic, oxygen-containing ions

________ ________ catalyzes the removal of oxygen from nitrate, leaving nitrite and water as products

Nitrate reductase

Denitrification: Some species of … possess enzymes that can further reduce nitrite to nitric oxide (NO), nitrous oxide2(N O) , and even nitrogen gas2(N )

Pseudomonas and Bacillus

Fermentation is the incomplete oxidation of glucose or other carbohydrates in the ..

Absence of oxygen

Fermentation uses … as the terminal electron acceptors

Organic compounds

Fermentation yields a ________ amount of ATP

Small

The methods of microbial control used outside of the body are designed to result in four possible outcomes …

1. Sterilization - autoclave

2. Disinfection - not bacteria endospores; bleach, iodine, heat

3. Decontamination (also called sanitization); soaps, detergents

4. Antisepsis - living tissues; alcohol, surgical hand scrubs

Bacterial Endospores

Have been considered the most resistant microbial entities

The goal of any sterilization process is the destruction of …

Endospores

Chemical that destroys bacteria except for those in the endospore stage

Bacteristatic

Fungicide vs. Virucide vs. Sporicide vs. Germicide/microbicide

• Fungicide: chemical that can kill fungal spores, hyphae, yeasts

• Virucide: chemical known to inactivate viruses, especially on living tissue

• Sporicide: an agent capable of destroying bacterial endospores

• Germicide/microbicide: chemical agents that kill microorganisms

The growth of microorganisms in the blood and other tissues

Bacteremia

Antiseptics: chemical agents applied ________ to exposed body surfaces, wounds, and surgical incisions

Directly