(Ch .5) Microbial Growth (Quantifying Organisms) Class & Lab

At which temperatures do bacteria survive best?

0°C or over 100°C, depending on the species.

Heterotroph: Chemolithotrophic heterotroph ("mixotroph")

1) Inorganic (Energy) 2) Organic (Carbon) 3) Ex: Desulphovibrio: aqua enivronments 4) Gram-

Heterotroph: Photoheterotroph

1) Light(Energy) 2) Organic (Carbon) Ex: Purple and green photosynthetic bacteria, e.g. Rhodospirillum Ca

Chemoorganotrophic autotroph

1) Organic (Energy) 2) Inorganic (Carbon) Ex: Pseudomonas oxalaticus

Heterotroph: (Chemo)heterotroph

1) Organic (Energy) 2) Organic (Carbon) 3) E. coli 4) Gram-

Into which groups are bacteria classified according to their temperature requirements?

3 temperatures at which they grow best A) Psychrophilic bacteria, or psychrophiles 1) ( 5°C and 20°C), 2) Psychrophiles are known to cause refrigerated foods to spoil (as in spoiled milk), but they generally do not grow at human body temperatures. B) Mesophilic bacteria, or mesophiles. 1) 20°C and 40°C, and they include the species that grow at body temperature (37°C). Many pathogenic bacteria are in this group. C) Thermophilic bacteria, or thermophiles. 1) 40°C and 80°C, and some tolerate temperatures as high as 110°C. 2) Many thermophiles grow at temperatures at which milk is pasteurized and they survive the pasteurization process. 3) Found in hot springs, geysers, and thermal vents found at the bottoms of oceans. Many of the archaea are also thermophiles.

At what pH levels can various types of bacteria grow?

A) Acidophiles 1) pH 0 to 5.0. (0) 2) Diary products B) Neutrophiles 1) pH of 5 to 8.5 are (7) 2) Most of the human pathogens are neutrophiles. 3) Cytoplasm C) Alkalinophiles. 1) ph 7.0 to 11.5. (14) 2) Many soil bacteria live at these higher pH harsh environments. 3) Lakes

Do all bacteria require oxygen for growth? (Oxygen Requirements)

A) Aerobic; that is, they require oxygen to grow and perform the biochemical reactions of their metabolism. 1) Final e- acceptor B) Anaerobic and are cultivated in a special apparatus where the oxygen has been removed. 1)These bacteria (known as anaerobes) live in the absence of oxygen 2) Found in the muddy bottom of swamps, landfills, and soil. Some anaerobes are obligate anaerobes C) Facultative anaerobes, meaning that they live with or without oxygen.

What is a microbial colony?

A) Cause disease or fermentation B) When a microorganism such as a bacterium divides in a population, the eventual result of many divisions is a visible mass of cells called a colony.

Nitrogen Requirements

A) Essential Element in Amino Acid B) Production of protein & nucleotide for DNA C) Acquire organic or inorganic sources. D) Photosynthetic Organisms 1) Can Reduce nitrate & ammonium, can be used in biosynthesis. E) Nitrogen Fixation 1) Taken from gas to form N2 & reduce NH3 2) Bacteria: Cyanobacteria ulize this process.

Which microbial forms can survive in moisture-free environments?

A) Fungi produce spores certain protozoa produce resistant cysts. B) Bacteria produce the most resistant structures known to science, the bacterial spores. C) Bacterial spores can exist at extreme environments for centuries or longer. When they are placed on a nutritious culture medium, they revert to vegetative cells that grow and multiply as normal bacterial cells.

How can the numbers of bacteria be measured in a bacterial population or colony?

A) Generally, the medium contains agar, a polysaccharide from marine algae that solidifies the medium, and a source of nutrients. B) To determine the number of bacteria within a population, dilutions of a population are made in a sterile water or saline solution, and predetermined amounts are placed on plates of agar medium. C) The bacteria will form colonies during incubation, and by measuring the number of colonies in a particular dilution, one can calculate backward to find the number of bacteria in the original population. This method is referred to as the plate count method.

Nutritional Requirements: (Energy Source)

A) Heterotroph 1) Chemoheterotroph 2) Photoheterotroph 3) Chemolithotrophic heterotroph 4)(Chemo)heterotroph B) Authotrophs 1) Photoautotroph 2) Chemolithotrophic autotroph (chemoautotroph)

Forms of Oxygen:

A) Hydroxyl Radical 1) A very toxic from of oxygen and highly reactive. 2) OH- comes from incomplete reduction of hydrogen peroxide. 3) Not an issue for anaerobic cells. B) Peroxide Anion 1) Very reactive oxidant. 2) Responsible for antimicrobial activity of Hydrogen peroxide C) Superoxide Radical: 1) Results of incomplete reaction of (O2) during e- transport in aerobes & anaerobes during metabolism 2) The enzyme superoxide dismutase, presents only in aerobes 3) Dexoftfys in the O2- radical.

Do all microorganisms require moisture for growth?

A) In order to grow, the reactions of metabolism such as glycolysis, chemiosmosis, and protein synthesis must take place in the cytoplasm of the microorganism, and these reactions take place in water. B) Therefore, a water environment is necessary for growth to occur. However, many microorganisms have the capacity to survive in moisture-free environments, but they do not grow in these environments.

B) Authotrophs 2) Chemolithotrophic autotroph (chemoautotroph)

A) Make Organic Molecules from CO2 B) organisms which use only inorganic nutrients, e.g. plants. C) Do not eat from other organisms to get their carbon

Can any bacteria live in a reduced oxygen atmosphere?

A) Microaerophilic. These bacteria grow best when a small (low levels) amount of oxygen is present. 1) Found in such environments as the urinary and digestive tracts in humans 2) Species can cause infections in these systems. 3) Many microaerophiles are dependent on carbon dioxide for their metabolism. These organisms are called capnophiles. B) Aerotolerant Anaerobes: Organisms that can tolerant low levels of oxygen. Prefer anaerobic conditions 1) found in Human gut

Temperature Range

A) Minimum Growth Temperature 1) Lowest temp that an organism still conducts metabolic processes. 2) Membranes are less fluid and transport molecules are slow B) Optimum Growth Temperature 1)Temp at which the organism thrives (best). 2) Metabolic processes & transport of molecules is efficient & optimal. C) Maximum Growth Temperature 1) The cells continue to live; but, w/ difficulty. 2)Membranes become more fluid & effected 3) Many protein are partially denature or processed being denture & losing functionally.

Do protozoa form colonies?

A) Naegleria and Acanthamoeba, protozoa cannot be cultivated on solid culture media, so they are unable to form colonies. B) However, they can be cultivated in liquid media, where they form cultures consisting of a single protozoan species. This is called an axenic culture.

Are microorganisms restricted to the particular environment in which we find them?

A) Obligate B) Facultative.

In what unusual environmental conditions can microorganisms be found?

A) Oceans, there exist thousands of species of marine microorganisms, which thrive in saltwater. B) At the bottoms of the oceans barophilic microorganisms (or barophiles), which survive the intense pressures of the water above them. C) Radiation, in environments where there are high osmotic pressures, and in environments where there are exceptional quantities of salt. D) The latter microorganisms as well as the marine microorganisms are known as halophilic microorganisms or halophiles.

Heterotroph

A) Organic compounds either directly or indirectly by ingesting other organisms or their products B) Catabolize reduce organic molecules. 1) Organisms which require organic carbon sources 2) Catabolize, Proteins, Carbs, & Amino Acids 3) D0 eat from other organisms to to get their Carbon Ex: Animals.

Hydrostatic Pressure: Barophiles

A) Organisms that thrives in High Pressure 1) When the pressure is relaxed, their membrane & protein denature Ex: deep sea bacteria or archaea. They are generally found on ocean floor

Chemolithotrophic autotroph (chemoautotroph)

A) Prokaryotes that require energy & e- from all Inorganic molecules. 1) Inorganic (Energy) 2) Inorganic (Carbon) Ex: Nitrobacter

At which temperatures do protozoa and fungi survive best?

A) Protozoa, fungi, and unicellular algae commonly exist under environmental temperatures that are fairly restricted. B) 25°C to 37°C. These microorganisms are generally involved in human disease. C) Colder 5°C found in the refrigerator. The growth of a mold on a refrigerated piece of food is evidence of this ability to grow at this colder temperature.

Photoautotroph

A) Use light a s photosynthesis 1) Light (Energy) 2) Inorganic (Carbon) Ex: Most photosynthetic bacteria, e.g. Chromatium (anaerobic), Cyanobacteria (aerobic)

In what sorts of environments can microorganisms live?

A) microorganisms can grow 1) Ice or in hot springs 2) Freshwater or in saltwater 3) W/or W/O oxygen 4) Highly acidic to highly alkaline environments. B) Microorganisms inhabit virtually all environments on Earth.

Nutritional Requirements:

Classifications

Litotrophs

Organisms that require e- from inorganic sources Ex: Fe2, H2S, No2, H2