Microbiology 230 Chapter 6

Prokaryotic Binary Fission

1. Cell replicates its chromosomes. 2. Cell elongates and growth between attachment sites pushes chromosomes apart. 3. Forms a new membrane and wall across the midline (septum) 4. When septum is complete, daughter cells may remain attached or separate.

Biofilm Developement

1. Settled onto a surface and attached itself 2. Produced a sticky extracellular polymeric substance or matrix 3. Matrix adheres cell to one another and the surface; secretes quorum-sensing molecules 4. Quorum sensing triggers cells to change biochemistry and shape 5. Microbes assume different roles in different areas of the biofilm 6. Some individual cells or groups of cells in streamers may leave the biofilm

Colony

An aggregation of cells arising from a single parent cell is called a ________.

Lithotrophs

Autotrophic organisms that acquire electrons from inorganic molecules are called ________.

pH-Sensitive Dyes

Bacteria can be distinguished based on their ability to metabolize certain sugars using differential media containing ________ ________.

Growth Factors

Microorganisms that require small amounts of certain organic chemicals that they cannot synthesize are called _______ ________. Example: Vitamins

Organotrophs

Heterotrophs that acquire electrons from the same organic molecule that provides them carbon are called ________.

Membrane Filtration

In ________ ________, a large sample is poured through a filter small enough to trap cells. - Useful for low density populations.

Stationary Phase

New organisms are produced at the same rate at which they are dying. - Metabolic rate of surviving cells decline WHAT PHASE IS THIS?

Anaerobes

Obligate ________ cannot tolerate oxygen and uses an electron acceptor other than oxygen.

Aerobes

Obligate ________ require oxygen as the final electron acceptor of the electron transport chain.

Death Phase

Organisms are dying more quickly than they can be replaced by new organisms. - All cells may die, but some may survive as endospores, a resting stage. WHAT PHASE IS THIS?

Aerotolerant Anaerobes

Organisms that do not use aerobic metabolism, but can tolerate oxygen because they have some of the enzymes that detoxify oxygen's poisonous forms are called ________ ________.

Faculative Anaerobes

Organisms that maintain life via fermentation or anaerobic respiration are called ________ ________. - Metabolic efficiency is often reduced in the absence of oxygen.

Fastidious

Organisms that require a large number of nutrients are termed ________.

Trace Elements

Selenium and Zinc are required in small amounts. They are considered to be ________ ________.

Alpha-Hemolysis

Streptococcus pneumoniae partially digests red blood cells, creating a greenish-brown decoloration around its colonies, denoted ________. [Differential Media]

Beta-Hemolysis

Streptococcus pyrogenes completely digests red blood cells, creating clear zones around its colonies, denoted ________. [Differential Media]

Limiting Nutrient

The absence of a ________ ________ can halt metabolism. * Hydrogen is never a ________ ________.

Maximum Growth Temperature

The highest temperature at which an organism continues to metabolize is called ________ ________ ________.

Minimum Growth Temperature

The lowest temperature at which an organism is able to conduct metabolism is called ________ ________ ________.

Lag Phase

The organisms are not growing, the cells are adjusting to their new environment by actively synthesizing enzymes to utilize novel nutrients in the medium. WHAT PHASE IS THIS?

Singlet Oxygen, Superoxide Radical, Peroxide Radical, and Hydroxyl Radical

WHAT ARE THE FOUR TOXIC FORMS OF OXYGEN?

Carbon Source, Source of Energy, and Source of Electrons or Hydrogen Atoms

WHAT ARE THE THREE REQUIREMENTS TO CONDUCT METABOLISM?

Hydrostatic Pressure

Water that exerts pressure in proportion to its depth is called the ________ ________. - For every additional 10m depth, water pressure increases by 1 atmosphere.

Semilogarithmic Scale

When microbial growth is plotted on a ________ ________, the plot of the population's growth results in a straight line. - Replaces the arithmetic scale on the y-axis with a logarithmic scale, accommodating small numbers at the lower end and large numbers at the upper end of the graph.

Genetic Method

- Used for isolating unique DNA sequences representing uncultured prokaryotic species genetic techniques, such as polymerase chain reaction and hybridization of DNA that codes for rRNA. WHAT METHOD IS THIS?

Dry Weight

- Suitable for broth cultures - Organisms are filtered from their culture medium, dried, and weighed. - Organisms are killed during process Example: Filamentous Microorganisms WHAT METHOD IS THIS?

Physical Requirements

- Temperature. - PH. - Osmolarity. - Pressure. WHAT ARE THESE REQUIREMENTS?

Indirect Methods

- Turbidity - Metabolic Activity - Dry Weight - Genetic Methods WHAT ARE THESE METHODS?

Chemotrophs

________are organisms that acquire energy from redox reactions, involving inorganic and organic chemicals.

Obligate halophiles

- Adapted to grow under high osmotic pressure. Examples: Great Salt Lake and small Salt Ponds

Turbidity

- As bacteria reproduce in a broth culture, the broth often becomes cloudy. - Estimates the growth of a microbial population by measuring changes in ________ using a spectrophotometer.

Pour-Plate

- CFUs are separated from each other using a series of dilutions. - Final dilutions are mixed with warm agar in petri dishes - Micropipettes can be utilized

Metabolic Activity

- Can indirectly estimate the number of cells in a culture by measuring changes in nutrient utilization, waste production, or pH. WHAT METHOD IS THIS?

Nutrient Broth

- Common medium. - Contains powdered beef extract and peptones dissolved in water - Used as broths

Streak-Plate

- Commonly used isolation technique. - Uses a sterile inoculating loop to spread an inoculum across the solid medium in petri dishes. - Colonies develop from each isolate after incubation.

Complex Media

- Contains a variety of growth factors. - Can support a wider variety of microbes. - Commonly prepared from partially digested materials: yeasts, beef, or casein. - Blood is often added to produced additional growth factors. Examples: Trypticase soy agar and MacConkey agar

Selective Media

- Contains substances that either favor the growth of particular microbes or inhibit the growth of desired microbes. - Can become selective when a single crucial nutrient is left out of it, glucose. Examples: Enrichment Culture and Cold Enrichment

Microscopic Counts

- Counting organisms directly through a microscope. - suitable for stained prokaryotes and large eukaryotes. - A cell counter is utilized. - Advantageous with more than 10,000,000 cells per milliliter or when a speedy estimate of population is required. WHAT METHOD IS THIS?

Pure Cultures

- Cultures composed of cells arising from a single progenitor called colony-forming unit (CFU). - All media, instruments, and vessels must be sterile in order to obtain this culture. Alternative Name: Axenic Cultures

Faculative Halophiles

- Do not require high salt concentrations, but can tolerate them.

Low-Oxygen Culture

- Favors the growth of microbes that thrive in environments intermediate between strictly aerobic and anaerobic. - Uses carbon dioxide incubators to provide an environment suitable from many microbes from various sites in the body. - Uses candle jars or chemical packs to reduce oxygen and permit the growth of aerotolerant, microaerophilic, and capnophiles. [Special Culture Technique]

Thermophiles

- Grow best above 45°C Examples: Compost piles and Hot springs

Hyperthermophiles

- Grow best above 80°C; some can live at or above 100°C

Psychrophiles

- Grow best at 15°C; can continue to grow below 0°C - Cannot survive above 20°C - Do not cause disease in humans

Neutrophiles

- Grow best between pH 6.5 and pH 7.5 Examples: Bacteria, Protozoa, and Pathogens

Mesophiles

- Grow best from 20°C to about 40°C; can survive at higher or lower temperature - Can cause disease in humans Example: Thermoduric Organisms

Acidophiles

- Grow best in acidic environments when pH can range as low as 0.0

Nitrogen

- Growth-limiting nutrient - Acquired from organic and inorganic nutrients - Constitutes about 79% of the atmosphere

Alkalinophiles

- Live in alkaline soils and water up to pH 11.5

Direct Methods without Incubation

- Microscopic Counts - Electronic Counters WHAT METHODS ARE THESE?

Agar

- Most microbes cannot digest ________. - Powdered ________ dissolves in water at 100°C - ________ solidifies at temperatures below 40°C - Solid _______ does not melt below 100°C

Barophiles

- Organisms that can live under extreme pressures - Die quickly if brought to the surface because their proteins denature.

Logarithmic Growth

- Produces dramatically different yields than simple addition, arithmetic growth. - Cells produced by binary fission is calculated as 2^n, where n is the number of generations. - Large numbers are expressed as powers of 10. Alternative Name: Exponential Growth

Direct Methods with Incubation

- Serial Dilution and Viable Plate Counts - Membrane Filtration - Most Probable Number (MPN) WHAT METHODS ARE THESE?

Anaerobic Media

- Uses a straight inoculating wire into the anoxic depths of solid media to form a stab culture. - Reducing media; contains compounds, such as sodium thioglycolate, that chemically combine with free oxygen and removes it from the medium.

Animal and Cell Culture

- Viruses and obligate intracellular parasites must reproduce inside the cell; Mammals, bird eggs, and cultures of living cells are used. - Allows for the growth of microbes for which artificial media are inadequate. [Special Culture Technique]

Cell Counter

A ________ ________ is a special glass slide composed of an etched grid positioned beneath a glass cover slip. - Designed to hold the cover slip 0.02nm above the grid. Alternative Name: Petroff-Hausser Counting Chamber

Nutrient

A ________ is any chemical required for growth of microbial populations. Examples: Carbon, Oxygen, Nitrogen, and Hydrogen

Spectrophotometer

A ________ measures the amount of light transmitted through a culture under standardized conditions. - Does not distinguish between living and dead cells. - Less useful for bacteria that form a pellicle or sediment.

Biofilms

A collection of microbes living on a surface in a complex community are called ________.

Medium

A collection of nutrients is called a ________.

Electronic Counters

A device that counts cells as they interrupt an electrical current flowing across a narrow tube held in front of an electronic detector. - Useful for counting larger cells of yeasts, unicellular algae, and protozoa. - Can use flow cytometry, a variation using fluorescent dyes or antibodies to count cells. Alternative Name: Coulter Counters WHAT METHOD IS THIS?

Nitrogen Fixation

A few bacteria can reduce nitrogen gas to ammonia via _________ ________. - Essential for life on earth Example: Photosynthetic Organisms

Growth Curve

A graph that plots the number of bacteria growing in a population over time is called a ________.

Defined Medium

A medium for which the precise chemical composition is known is called a ________ ________. Alternative Name: Synthetic Medium

Binary Fission

A process in which a cell grows to twice its normal size and then divides in half to produce two daughter cells of equal size is called ________.

Quorum Sensing

A process in which microorganisms respond to the density of nearby microorganisms is called ________ ________.

Inoculum

A substance used for inoculation is called an ________.

Catalase Test

A test used to determine the presence of catalase by adding a sample to a drop of hydrogen peroxide. - Production of bubbles indicates a positive reaction.

Colonies

Cultures that are grown and visible on a surface of solid media are called ________. - Display distinctive characteristics

Broths

Cultures that are grown in liquid media are called ________.

Gamma-Hemolysis

Enterococcus faecalis does not digest red blood cells, creating little change around its colonies, denoted ________. - No hemolysis occurs [Differential Media]

Osmotic Pressure

Pressure exerted on a membrane by a solution containing solutes that cannot freely cross the membrane is called ________ ________.

Log Phase

The organisms population is actively growing; the reproductive rate reaches a constant as DNA and protein syntheses are maximized. - More susceptible to antimicrobial drugs that interfere with metabolism - Preferred for gram staining, industrial, and laboratory purposes. WHAT PHASE IS THIS?

Optimum Growth Temperature

The temperature at which an organism's metabolic activities produce the highest growth rate is called ________ ________ ________.

Generation Time

The time required for a bacterial cell to grow and divide is its ________ ________. - Dependent on chemical and physical conditions. - Most have a ________ ________ of 1 to3hrs; but under optimal conditions, some have 20mins or less.

Growth

To indicate an increase in a population of microbes rather than an increase is size describes ________. [Colony or Biofilms]

Serial Dilution and Viable Plate Counts

When population densities are high, microbiologists use ________ ________ and ________ ________ ________ to estimate the size of a microbial population based on the number of colonies formed when diluted samples are planted onto agar media.

Slants

When warm agar media are poured into tubes that are then placed at an angle and left to cool until the agar solidifies are called ________.

Most Probable Number

________ ________ ________ is a statistical estimating technique based on the fact that more bacteria are in a sample, the more dilutions are required to reduce their number to zero. - Dilution is used to inoculate a set of tubes - Useful for counting microbes that do not grow on solid media, etc...

Transport Media

________ ________ are chemically formulated to maintain the relative abundance of different microbial species or to maintain an anaerobic environment.

Superoxide Radicals

________ ________ are formed during the incomplete reduction of oxygen during electron transport in aerobes and during metabolism in anaerobs in the presence of oxygen. - Detoxified by ________ dismutase.

Clinical Specimens

________ ________ are taken from patients and handled in ways that facilitate the examination of microbes or testing for their presence. - Need to be properly labeled and transported to avoid death and growth of normal microbiota. Examples: Feces, Saliva, Cerebrospinal fluid, and Blood

Environmental Specimens

________ ________ are taken from such sources as ponds, streams, soil, and air.

Acid-Tolerant Microbes

________ ________ can survive in neutral pH conditions.

Differential Media

________ ________ distinguishes either the presence of visible changes in the medium or the differences in the appearance of colonies. - Helps microbiologists differentiate among the different kinds of bacteria growing on the medium. Example: Blood agar and pH-sensitive dyes

Peroxide Anion

________ ________ is a component of hydrogen peroxide, which is formed during reactions catalyzed by superoxide dismutase. - The enzymes catalase and peroxidase convert _______ ________ to nontoxic compounds.

Singlet Oxygen

________ ________ is a molecular oxygen with electrons that have been boosted to a higher energy state, typically during aerobic metabolism. Example: Phototrophic microorganisms prevent toxicity by removing the excess energy of ________ ________ via carotenoids.

Nutrient Agar

________ ________ is nutrient broth to which 1.5% agar has been added. - Media made solid

Enrichment Culture

________ ________ is the use of a selective medium to specifically promote the growth of desired microbes to observable levels.

Obligate Acidophiles

________ ________ requires an acid environment to survive.

Cold Enrichment

________ ________ requires the incubation of a specimen in a refrigerator, allowing for the enrichment of the culture with cold-tolerant species. Examples: Stool and Water Specimens

Hydroxyl Radicals

________ ________ result from ionizing radiations and from the incomplete reduction of hydrogen peroxide. - Most reactive of the four toxic oxygen forms, but threat is eliminated by catalase and peroxidase in aerobic cells.

Photoheterotrophs

________ acquire energy from light and acquires nutrients via catabolism of organic compounds.

Capnophiles

________ are organisms that grow best with high carbon dioxide levels, 3% to 10%, in addition to low oxygen levels.

Phototrophs

________ are organisms that use light as an energy source.

Peroxidase

________ breaks down hydrogen peroxide using a reducing agent, coenzyme NADH.

Culture

________ can refer to the act of cultivating microorganisms or the microorganisms that are cultivated.

Heterotrophs

________ catabolize organic molecules they require from other organisms. Examples: Proteins, Carbohydrates, Amino acids, and Fatty acids

Catalase

________ converts hydrogen peroxide to water and oxygen.

pH

________ is a measure of the concentration of hydrogen ions in a solution. - Measure of acidity or alkalinity of a substance

Temperature

________ plays a role in microbial life through its effects on three-dimensional configurations of biological molecules.

Microaerophiles

________ require oxygen levels of 2% to 10%. - Concentration found in the stomach - Damaged by 21% concentration of oxygen in the air.

Photoautotrophs

________ use carbon dioxide as a carbon source and uses light as an energy source.

Chemoautotrophs

________ use carbon dioxide as a carbon source but obtains energy from redox reactions, involving organic and inorganic chemicals.

Chemoheterotrophs

________ use organic compounds for both energy and carbon.

Autotrophs

________ utilize an inorganic source of carbon, carbon dioxide, as their source of carbon.