Microbiology Chapter 7: Fundamentals of Microbial Growth and Control

microbial growth

cell division that produces new (daughter) cells and increases the total cell population

generation time

The time that it takes for a cells population to double

exponential growth

As bacteria divide by binary fission, they exhibit\______________.

20 minutes

Generation time for E. Coli is what?

15-20 hours

Generation time for mycobacterium tuberculosis is?

Lag phase

What is phase one of the bacteria growth phases

Phase one-lag phase

Which phase is the delay that occurs while cells adjust to their new environment?

log phase

What is phase two of the bacteria growth phases

Phase two- log phase

Which is the period of rapid exponential growth

Phase Three- stationary phase

Which occurs when the nutrients are depleted & waste accumulates? During this phase, population growth rate levels are off.

stationary phase

What is phase three of the bacteria growth phases?

death phase

What is the fourth phase of the bacteria growth phases?

Phase four- death phase

Which phase occurs when waste builds up, nutrients decease, & the cells begin to die?

low temperature

Decreases enzymatic reactions

increased temperature

What property speeds up enzymatic reaction and increase growth rate

high temperatures

what denatures cell proteins?

optimal temperature

Temperature where cellular growth is the highest

Psychrophiles

Thrive between -20 and 10 degrees Celsius

Psychrotrophs

Bacteria that grow at about 0-30 degrees Celsius and are associated with foodborne illness

Mesophiles

grow best around 10-50 degrees Celsius and are associated with most pathogens

Thermophiles

grow around 40-75 degrees Celsius are associated with compost piles and hot spring

Extreme thermophiles

thrive in very hot environments are grown around 65-120 degrees Celsius

Listeriosis

usually food borne infection; can be transmitted to fetus, reproduces in phagocytes, is a psychrotroph and can grow at refrigerator temps

Acidophiles

grow at PH 1 (or less) to PH 5, live in areas such as sulfur hot springs & volcanic vents are often maintain a fairly neutral cytoplasmic PH

Neutralophiles

grow best in a PH range of 5-8 make up majority of microorganisms

Alkaliphiles

grow in the basic PH range of 9-11 are associated with soda lakes

Halophiles

thrive in high salt environments are associated with the Dead Sea and the great salt lake of Utah

Facultative halophiles

tolerate higher salt but may not grow well. EX. staphylococcus aureus

Plasmolysis

Normal cells undergo ______, which is the process of cell losing water when placed in a hypertonic solution.

Cold

The suffix "psychro" means.......

Obligate aerobes

Organism with an absolute dependence on O2 for cellular processes

Microaerophiles

organisms that use only a small amount of O2 live in low O2 settings

falcultative anaerobes

organisms that grow with and without O2 and switch between using O2 and fermentation

aerotolerant anaerobes

organisms that tolerate O2, but don't use it and have ways to deactivate ROS

obligate anaerobes

Organisms that Do Not use O2 in their metabolism and can’t eliminate ROS; Tend to die in aerobic environments

Essential Nutrients

Elements such as sulfur, phosphorus, hydrogen, carbon, nitrogen, etc. that cell are required to have to build new cell.

Macronutrients

essential nutrients that are needed in large quantities for the cell, usually compose most of the dry weight.

Micronutrients

Nutrients used in very small amounts

Nutrients

Microbes use\__________from the environment go divide, and to build structural components, enzymes, and other factors.

90%

About\_______of a cells dry weight is carbon, hydrogen, nongaseous oxygen, and nitrogen.

Carbon

\_______is required by all organisms to form structural organic molecules and as a energy source.

Heterotroph & Autotroph

Two categories of organisms based on how they obtain organic carbon

Heterotrophs

Require and external source of organic carbon ( sugars, lipids, protiens)

Autotrophs

Do not require an external source of organic carbon and use carbon fixation to convert inorganic carbon into organic carbon

Nitrogen

\________is the limiting factor in many ecosystems and is found in amino acids and protiens

Sulfur

Found in amino acids, thiamine, and biotin

Phosphorus

Found in DNA, RNA, ATP, and membranes

growth factors

The necessary substances that a cell can't make on its own are called\_____________.

fastidious

Organisms that need multiple growth factors are said to be________.

phototrophs and chemotrophs

In order to carry out functions & construction, cells require energy including.....

Phototrophs

obtain energy from light

Chemotrophs

organisms that break down chemicals compounds for energy

Media

We classify\____________by their physical state, chemical composition, and their function.

liquid media

Ideal for growing large batches of microbes

solid media

Useful for isolating colonies and observing specific culture characteristics

semisolid media

Useful for motility testing of bacteria species

defined media

Synthetic media that has a precise chemical composition that is known and quantified to growth cultures

complex media

Media with a mixture of nutrients that are not fully defined and are used to grow fastidious organisms (EX. extracts and digests of yeasts, meat, or plants)

differential media

media formulated to visually distinguish one microbe from another

Blood Agar

Useful for distinguishing Steptococcus pyogenes

Beta hemolysis

Break down red blood cells

Alpha hemolysis

Partial breakdown of red blood cells by oxidation of hemoglobin

Gamma hemolysis

do not lyse red blood cells

selective media

suppress unwanted microbes and encourage desired microbes

Mannitol Salt Agar

selective due to its high salt content and differentiates organisms based on their ability to ferment a sugar called "mannitol"

Eosin Methylene Blue Agar (EMB)

dyes eosin and methylene blue limit gram-positive bacterial growth and differentiates based on ability to ferment lactose

38%

On average, anaerobes make up\_______of the bacterial population in a wound.

thioglycate

Reducing agent used for anaerobic organism; converts O2 to water

aseptic techniques

Methods designed to prevent introducing contaminating microbes to a patient, clinical sample, or others in the healthcare setting.

streak plate technique

most commonly used technique to isolate bacteria whose method is to dilute a culture on an agar plate

colony

As cells divide, their population increases to form a mound of cells called a\____________.

Direct Methods

Involve counting individual cells or colonies (plate counts)

Indirect Methods

rely on secondary reflections of overall population size

What are the consideration made when collecting clinical samples?

A patient primary diagnosis, stage & site of infection all affect how and when a sample is taken further more **Aseptic techniques**, **equipment used**, **taking a** **specific sample site** are all important to implement in the collection process.

Turbidity

The fast and easy way to indirectly measure cell numbers is to measure the\___________.

cloudiness

The term "turbidity" refers to.....

Physical Analysis

Involves staining and microscopy to observe morphological features

Biochemical analysis

Involves a collection of media that assess metabolic properties

Genetic methods

helps to quickly identify microbes and probes, PCR, DNA "fingerprinting", electrophoresis separation methods

Decontamination

Measures that remove or reduce microbial populations to render an object safe for handling

Sterilization

A measure that eliminates ALL bacteria, viruses, and endospores. Is required for drugs, objects used for medical procedures, and for lab media & glassware

Disinfection

Reduces microbial numbers on surfaces or objects and is used for cosmetics, foods, surfaces, and external medical equipment

Antiseptics

used to destroy pathogens on living tissue

Heat

Most microbes are sensitive to\__________.

Decimal Reduction Time (DRT)

The time, in minutes, it takes to kill 90% of a population of bacteria at a given temperature and is associated with disinfection

Thermal death time (TDT)

Shortest period of time at a certain temperature needed to kill all microbes in a sample

Thermal death point (TDP)

The minimum temperature needed to kill all microbes in a sample within 10 minutes

Autoclave

A machine that applies steam heat along with pressure to sterilize is used for microbiological media & assorted medical or lab equipment

20 minutes

Most substances are sterile after \________ using the standard autoclave settings.

What is autoclaving?

Steaming an object at 121 degrees Celsius (294 degrees Fahrenheit) with 15 pounds of pressure

Boiling

A highly affective decontaminating method used on heat resistant equipment **NOT** **sterilization**, that eliminates most microbial numbers, **BUT NOT** endospores.

Boiling water

\______________ for 5 minutes eliminates most pathogenic bacteria, protozoan, and viruses.

Pasteurization

Eliminates pathogens and reduces harmless microbes in dairy products that cause milk spoilage. EX. listeria, salmonella, and E. Coli

Incineration (dry heat)

\_________ or hot air ovens can also be used to sterilization or disinfection.

Radiation

Some physical decontamination methods involve __________, or high energy waves. Can serve as a disinfectant or sterilization tool depending on the protocol (either ionizing or non-ionizing).

Non-ionizing radiation

(ultraviolet light) causes thymine diners by altering structure of DNA leading to mutation used in sanitize drinking water & swimming pools, disinfecting surfaces in operating rooms, and disinfect biosafety cabinet surfaces

Ionizing radiation

generate reactive ions that kill microbes and inactivate viruses using gamma rays and x-rays but can damage nucleic acids. Can be used to in food (spices, meats, vegetables)and pharmaceutical industry, sterilizing medical supplies that cannot be autoclaved.

High-efficiency particulate air (HEPA) filters

Remove microbes and allergens from the air is made of randomly arranged fibers hat remove 99.97% of airborne substances (does not sterilize the air)

Membrane filters

liquids can be sterilized using \_________________. (pore sizes range from 0.1 mm to filter out bacteria, to 0.01 mm to remove viruses)

"lifeStraws"

0.2 mm filters that remove pathogens from drinking water