BIOL203-Exam 2

increase in number of cells, not cell size

populations and colonies

What are the physical requirements for growth?

temperature

pH

osmotic pressure

What are the chemical requirements for growth?

carbon

nitrogen

sulfur

phosphorus

Trace elements

oxygen

organic growth factor

Psychrotrophs are also known as?

Cold-Loving Microbes

What is the temperature range in which pyschrotrophs grow in?

Grow between 0°C and 20-30°C

Most bacteria grow between pH of?

6.5 and 7.5

Molds and yeasts grow between pH of?

pH 5 and 6

Acidophiles grow in what type of environments

acidic environments

What is osmotic pressure?

The force caused by a solution passing through a semi permeable surface by osmosis

Hypertonic environments, or an increase insalt or sugar, cause

plasmolysis (loss of water from the cell)

Extreme or obligate halophiles (salt-loving)require

high osmotic pressure

Facultative halophiles tolerate high osmoticpressure; do not require

high salt concentration

Active transport requires ___ and ____

transporter protein

ATP

Group translocation requires ____ and ____

tranporter protein

PEP

PEP has the highest energy phosphate bond found in living organisms, and is involved in ____?

glycolysis

PEP group translocation was discovered by who and when?

The system was discovered by Saul Roseman in 1964

PEP group translocation is a method used by bacteria to take _____?

Glucose as a source on energy

PEP group translocation is known as a ________ system, that involves the enzymes of the _____________ and the ___________?

multi-component system

plasma membrane

cytoplasm

Carbon chemical requirements

Structural organic molecules, energy source- Chemoheterotrophs - use organic carbon sources• Heterotroph - an organism deriving its nutritional requirements from complex organic substances- Autotrophs ("self-nourishing") use CO2 as the carbon source

Nitrogen chemical requirements

In amino acids and proteins

-Most bacteria decompose protein

Some bacteria use NH4+ (ammonium) or NO3- (nitrate)

-A few bacteria use N2 in nitrogen fixation• Symbiotic relationship with legumes (i.e., lima beans, peas)

Sulfur chemical requirements

In amino acids, thiamine (vitamin B1), and biotin- Most bacteria decompose proteins- Some bacteria use SO42- (sulfates) or H2S(hydrogen sulfide)

Phosphorus chemical requirements

In DNA, RNA, ATP, and membranes- PO4-3 (phosphate) is a source of phosphorus

Trace elements chemical requirements

Inorganic elements required in small amount

Usually as enzyme cofactors (Mg++, Mn++)

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What are the organic growth factors?/ how can you classify it?

Essential organic compounds that an organism is unable to synthesize

Organic compounds obtained from the environment

Vitamins (act as co-enzymes), amino acids,purines, and pyrimidines

What are the main points to know for biofilms

Microbial communities(not like on plates)

Form slime or hydrogels

Bacteria attracted by chemicals via quorum sensing

Process of cell-cell communication that allows bacteria to share information about cell density and adjust gene expression accordingly

Chemical communication

What do Biofilms share?

nutrients

T of F: Biofilms are sheltered from harmful factors

True

In biofilms microbes are approximately _________ more resistant to microbicides

1000X

What is Culture medium?

nutrients prepared for microbial growth

How can sterile be defined?

no living microbes present

What is Inoculum?

Introduction of microbes into medium or an environment

How can culture be defined ?

Microbes growing in/on culture medium

What is Agar?

Solid media on which bacteria grow

What are some characteristics of Agar?

Complex polysaccharide

Used as solidifying agent for culture media in petri plates, slants, and deeps

Generally not metabolized by microbes

Liquefies at 100°C

Solidifies at ~40°C

What is Chemically defined media?

exact chemical composition is known

What is Complex media?

Extracts and digests of yeasts, meat, or plants

Nutrient broth-

Nutrient agar

What are some Anaerobic Culture Methods?

Reducing media, anaerobic jar, anaerobic chamber

Reducing media:

Contain chemicals (thioglycolate or oxyrase) that combine with dissolved O2 and deplete the O2 in the medium

Heated to drive off O2

A reducing media is used to culture?

anaerobic organisms

anaerobic jar

Used to create anaerobic, microaerophilic, CO2-enriched

conditions depending on specific needs of bacteria being cultivated

anaerobic chamber

An enclosed compartment maintained in an anaerobic environment; a special port is used to add or remove items

What are Capnophiles?

Microbes that require and survive high CO2 conditions

What are some examples of capnophiles

Examples:- Campylobacter species can cause intestinal disorders- Other capnophilic pathogens occur in the Gram-negative Aggregatibacter spp. found in the mouth(e.g., Aggregatibacter actinomycetemcomitans)• These are a cause of aggressive juvenile periodontitis

What are Biosafety Levels (BSLs)?

There are four biosafety levels. Each level has specific controls for containment of microbes and biological agents. The primary risks that determine levels of containment are infectivity, severity of disease, transmissibility, and the nature of the work conducted. Origin of the microbe, or the agent in question, and the route of exposure are also important.

What is the first level of biosafety?

BSL-1 - No special precautions• E. coli K-12

What is the second level of biosafety?

BSL-2 - Lab coat, gloves, eye protection• E. coli O157:H7, Salmonella spp.

What is the third level of biosafety?

BSL-3 - Biosafety cabinets to preventairborne transmission• M. tuberculosis, Y. pestis

What is the fourth level of biosafety?

BSL-4 - Sealed, negative pressure; exhaust air is filtered twice• Ebola virus

What is selective media?

Suppress unwanted microbes and encourage desired microbes (Mannitol Salt Agar)

What is differential media?

Differential medium makes it easy to distinguish colonies of different microbes

Enrichment culture encourages ?

growth of desired microbe

Obtaining Pure Cultures

A pure culture contains only one species or strain; genetically pure

What is a colony?

is a population of cells arising froma single cell or spore or from a group ofattached cells

What is a colony often called/referred to as?

often called a colony-forming unit (CFU)

The streak plate method is used to isolate?

pure cultures

Preserving Bacterial Cultures with Deep-freezing what must the temp be ?

-50° to -95°C

Preserving bacteria cultures with Lyophilization (freeze-drying), what must the temp reach/be at?

Frozen (-54°to -72°C) and dehydrated in a vacuum

how is reproduction in prokaryotes done/occurs

binary fission

What are some characteristics of reproduction in prokaryotes

Budding - a small initial outgrowth that enlarges and separates from "mother" cell•

"Chains" of conidiospores (actinomycetes)

Fragmentation of filaments Reproduction in Prokaryotes

How many steps are in binary fission?

4 steps

What are the four steps of binary fission?

1. Cell elongates and DNA is replicated

2. Cell wall and plasma membrane begin to constrict

3. Cross-wall forms, completely separating the two DNA copies

4. Cells separate

What are the steps of budding?

1: bud begins to form on parent cell

2: nucleus copies and divides. The bud receives a copy

3: bud now becomes a separate daughter cell

4:budding produces chains of cells

Generation time

As cells divide, the population increases exponentially• Numerically this is equal to two (because the cell divides into two) raised to the number of times the cell divided (generations)

2 number of generations

Dilution Factor is also known as

Df

Dilution factor=

= the volume of the amount to be diluted the same volume plus the diluent10-Fold Dilution = 1/1 + 9100-Fold Dilution = 1/1 + 991000-Fold Dilution = 1/1 + 999

Plate Counts•: After incubation, count colonies on plates that have ___-_____ colonies (CFUs)

25-250 colonies

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Most Probable Number

A statistical method of measuring bacterial growth used when samples contain too few organisms to give reliable measures by the plate count method

Measuring microbial growth, direct methods

Plate counts

Filtration

MPN

Direct microscopic count

What are the indirect methods for measuring microbial growth?

Turbidity

Metabolic activity (acidproduction)

Dry weight

Turbidity

A measure of how clear water is.

Direct Microscopic Count

Know the formula as seen in the picture

Sepsis refers to?

microbial contamination

Asepsis is the absence of?

significant contamination

Aseptic surgery(ical) techniques prevent microbial contamination of?

wounds

What is sterilization?

Process of removing all microbial life

Commercial sterilization: Enough heat to destroy ___?

C. botulinum endospores- "Botox" FDA Approved in 2002

What is Disinfection?

removing/ removal of pathogenic organisms

What is antisepsis?

Removing pathogens from living tissue

Removing microbes from a limited area is called

Degerming

Sanitization is a process by which

Lowering microbial counts on eating utensils to minimize the chance of disease

Biocide/germicide does what?

kills microbes

Bacteriostasis is what?

Inhibiting, not killing, microbes

The effectiveness of treatment depends on what?

1. Number of microbes

2. Environment

-organic matter (blood, feces) - influence the selection of an antimicrobial agent

Temperature - warmer temperatures are better• Biofilms

3. Time of exposure (consider temp-resistant or spores)

4. Microbial characteristics

If there is a greater number of microbes how might treatment be affected?

greater number means a longer treatment will be needed

T or F: Agar is a polysaccharide?

True

what are the actions of microbial control agents?

1. alteration of membrane permeability

2. damage to proteins

3. damage to nucleic acids

complex media is knowing what you add to it but it is not ____________________?

chemically defined (because it is so complex)

What are examples of a complex media?

nutrient broth and nutrient agar

What is an example of chemically defined media?

glucose salt broth

if you are trying to grow bacteria that can be killed by oxygen what method can be used?

anaerobic culture method

Heating and boiling is used to

drive of oxygen

When we talk about microbial growth, we are really referring to?

the number of cells

Microorganisms are classified into _____ primary groups on the basis of their preferred range of temperature?

3

What are the groups that microorganisms are divided into based on their preferred range of temperature?

psychrophiles (cold-loving microbes)

mesophiles (moderate-temperature-loving microbes)

thermophiles (heat-loving microbes).

True or False: The minimum growth temperature is the lowest temperature at which the species will grow.

True

What is an example of BSL-4

ebola

What is the level at which microorganisms grow best at?

optimum growth temperature