Microbio Chapter 11

Vocabulary practice flashcards covering microbial growth, environmental requirements, symbiotic relationships, growth phases, and methods of physical and chemical microbial control from Chapter 11.

Autotroph

Self-feeding organism that starts with single carbon molecules and turns them into multiple carbon organic molecules by fixing carbon (e.g., photosynthesis).

Heterotroph

Organism that must start with already existing multi-carbon organic molecules (e.g., humans).

Phototroph

Organism that obtains its energy from a light source, such as the sun.

Chemotroph

Organism that obtains its energy from food through catabolic reactions (e.g., humans).

Photoautotrophic

Nutritional type characteristic of plants, which use light energy to fix carbon.

Chemoheterotrophic

Nutritional type characteristic of humans and human pathogens.

Minimum Temperature

The lowest temperature at which a microbe can grow, below which growth stops or freezes them.

Optimum Temperature

The ideal, best, or favorite temperature for a microbe to grow.

Maximum Temperature

The highest temperature at which a microbe can grow, above which it will burn up and die.

Human Pathogen Incubator Temperature

Optimal temperature for incubating human pathogens, set at $37^\text{o}\text{C}$ ($98.6^\text{o}\text{F}$), also referred to as a hot box.

Minimum-Optimum-Maximum

-temperature

-pH

-oxygen concentration, etc

Obligate Aerobes

Microbes that love oxygen and require the level of oxygen present in air (20/21\text{\text{%}} $O_2$) to survive.

Obligate Anaerobes

Microbes that hate oxygen and will be killed if $O_2$ is around them.

Microaerophiles

Microbes that require or prefer small amounts of oxygen.

Facultative Anaerobes

Microbes that can function with or without $O_2$, but prefer $O_2$ because growing aerobically produces more ATP.

Aerotolerant Anaerobes

Microbes that can function with or without $O_2$ and do not care whether oxygen is present.

Symbiosis

A close interaction between a host and a symbiont where at least one party always benefits.

Mutualism

A symbiotic relationship in which both the symbiote and the host benefit.

Commensalism

A symbiotic relationship in which the symbiote benefits while the host is neither helped nor harmed.

Parasitism

A symbiotic relationship in which the symbiote benefits and the host is harmed.

Sterilization

A microbial control process that completely kills ALL microbes.

Disinfection

A microbial control process aimed at reducing the total numbers of microbes.

Antisepsis (Degerming)

The removal of microbes from living tissue or skin (e.g., showering to remove microbes or move them somewhere else).

Decontamination (Sanitization)

A cleaning process that reduces microbial load depending on the specific job required.

Antimicrobial Agent

An agent that works against microbes.

Microbicidal Agent

An agent that directly kills microbes.

Microbistatic Agent

An agent that slowly halts or stops the growth of microbes without necessarily killing them.

Broad Spectrum Agent

An antimicrobial agent effective against lots of different types of microbes.

Narrow Spectrum Agent

An antimicrobial agent effective against only a select or few types of microbes.

Microbial Load

The amount or total population of microbes present; a higher population takes longer to kill.

Lag Phase

Bacterial growth phase where microbes are adjusting to their new environment and getting settled.

Log Phase

Bacterial growth phase where microbes grow fast, multiply rapidly through cell division, eat/digest, and are most vulnerable to targeted metabolic antimicrobial agents.

Stationary Phase

Bacterial growth phase where growth slows or stops due to nutrient depletion and waste accumulation, resulting in a balanced rate of new cells and dying cells.

Death Phase (Decline Phase)

Bacterial growth phase where the population crashes and more bacteria are dying than are being produced.

Antimicrobial Agent - Effectiveness depends on: Expose Time

How long it is in contact with the agent

Antimicrobial Agent — Effectiveness depends on: Concentration of Agent

• how concentrated it is

• Heavy metals: you can dilute how much you want but still find microbes

• Some you can dilute, some you can’t

Antimicrobial Agent — Effectiveness depends on: Microbial Load

• the amount of microbes; how many did you start with

• Higher population, the longer it will take

Antimicrobial Agents - to a lesser extent

• temperature

• Local environment (pH, organic matter - decaying leaves, etc) ex: chlorine = halogen (works great with pre low concentration)

• Growth phase of microbes

• Differences in species susceptibility

• Mechanism of action of agent,etc

Antimicrobial Agent - Targets

• cell wall

• Cell membrane

  • Surfactants - keep clean, surface active agents, ex: detergents = good surfactant

• Proteins

  • Inhibition - throw molecules onto it to stick and keep from doing its job/stopping from working

  • Denaturation - unravel protein

• Nucleic acids - done for when something done to it. Radiation - wonderful nucleic acids agents; wonderful disinfectant. Viruses have nucleic acids

Physical Methods of Microbial Control: Heat

• Heat - microcidal

  • Dry heat - Bunsen burner

  • Moist heat - boiling, autoclave - heat tolerant, steam

Physical Methods of Microbial Control: Low temperatures

• microstatic

• Refrigerator/freezer

• Freeze water = freeze microbes

Physical Methods of Microbial Control: Desiccation/lyohilization

• desiccation - suck eater in liquid form

• Lyohilization - freeze dying/solid (easier); stops microbes

• Ice is less dense than liquid; less dense = easier to suck out

• Microstatic

Physical Methods of Microbial Control: Osmotic pressure

• high osmotic pressure = no microbes will grow in that

• Hypertonic environment

• Microstatic

Physical Methods of Microbial Control: Filtration

• microstatic

• Liquids/gas —> filter will trap microbes going through it

Physical Methods of Microbial Control: Radiation

• microcidal

• Good nucleic acid targeting agent

• Ionizing radiation ( ex: x-rays, y-rays)

  • Short wavelength, high frequency, can penetrate most solid barriers

• Non-ionizing radiation (ex: UV rays)

  • Isn’t as harsh, cannot penetrate solider barriers

    • Pyrimidine (Thymine) Dimers

      • UV light —> 2 thymines stick together —> DNA damage —> repair needed

      • More means DNA is less useable

Chemical Methods of Microbial Control:

• concentration of agent often primary factor

• Often disinfection, not sterilization —> can’t on human skin

• May be solid or gas but usually liquid

Evaluating Effectiveness of Chemical Agents: Phenol Coefficient

How a chemical works compared to phenol

Evaluating Effectiveness of Chemical Agents: Filter Paper Method

• put substance on paper —> place it on Bacteria —> see if it stops bacterial growth

• The larger the zone, the more effective the substance is at inhibiting that bacterium

Evaluating Effectiveness of Chemical Agents: Use Dilution Test

• need 1g to see microbial activity

• Use liquid media to see how well microbes work in a liquid media

Evaluating Effectiveness of Chemical Agents: MIC values

• minimum inhibitory concentration; needed to see microbial activity

Chemical Methods of Microbial Control: Phenol/Phenolics

• damage membranes + denatures proteins —> control/kill microbes

• Triclosan - antibacterial.antifungal agent to stop or slow the growth of microbes like bacteria/mold

Chemical Methods of Microbial Control: Chlorhexidine

• used as a skin disinfectant

• Used for iodine allergic

Chemical Methods of Microbial Control: halogens

• chlorine —> makes bleach active, iodine

Chemical Methods of Microbial Control: Alcohols

• hand sanitizer (isopropyl alcohol or ethanol)

• Put it on, does its job, evaporates

• Have to be heavily concentrated to be effective

Chemical Methods of Microbial Control: Heavy Metals

• can dilute the hell out of and still be effective

• Oligodynamic Action

  • Small concentration = still very effective

Chemical Methods of Microbial Control: Soaps/Detergants

• loosen remove microbes from surfaces and skin

• Surfactants - targeting cell membranes, phospholipid bilayer

Chemical Methods of Microbial Control: Oxidizing Agents

• work better against anaerobes

• Gains or accepts electrons in a oxidation reduction reaction, causing another substance to be oxidized

Chemical Methods of Microbial Control: Gaseous Agents (ETO gas)

• damages DNA + proteins —> sterilizing equipment

• ETO —> ethologies oxide —> sterilizing agent, kills microorganisms by damaging their DNA + proteins’

• Heat sensitive solid

Surfactants

Surface-active agents (e.g., soaps, detergents) that target cell membranes and the phospholipid bilayer to loosen and remove microbes.

Ionizing Radiation

Microcidal radiation with short wavelengths and high frequency (e.g., X-rays, gamma rays) that can penetrate most solid barriers to damage nucleic acids.

Non-ionizing Radiation

Radiation (e.g., UV rays) that cannot penetrate solid barriers and damages DNA by forming pyrimidine dimers.

Pyrimidine (Thymine) Dimers

DNA damage caused by UV light where two adjacent thymines stick together, making DNA less usable and requiring repair.

Filter-Paper Method

A test for chemical effectiveness where a substance is placed on paper on a bacterial plate to observe the zone of inhibition; a larger zone indicates a more effective substance.

Minimum Inhibitory Concentration (MIC)

The minimum concentration of an antimicrobial agent needed to observe microbial inhibition activity.

Chlorhexidine

A chemical agent used as a skin disinfectant, particularly for patients who are allergic to iodine.

Oligodynamic Action

The property of heavy metals (such as silver) where a very small concentration is still very effective at controlling microbes.

Ethylene Oxide (ETO Gas)

A gaseous sterilizing agent used on heat-sensitive solids and equipment that kills microorganisms by damaging their DNA and proteins.