Microbiology chp 6 notes PDF

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micro chp 6 notes 6.1 essential nutrient Any ingredient such as a certain amino acid, fatty acid, Vitamin, or mineral that cannot be formed by an organism and must be supplied in the diet. A growth factor. macronutrient A chemical substance required in large quantities (phosphate, for example). micronutrient A chemical substance required in small quantities (trace metals, for example). trace elements Micronutrients (zinc, nickel, and manganese) that occur in small amounts and are involved in enzyme function and maintenance of toxin protein structure. heterotroph An organism that relies upon organic compounds for its carbon and energy needs. Autotroph- a microorganism that requires only inorganic nutrients and whole sole source of carbon is carbon dioxide phototrophs Microbes that use photosynthesis to feed. chemotroph Organism that oxidizes compounds to feed on nutrients. photoautotroph An organism that utilizes light for its energy and carbon dioxide chiefly for its carbon needs. chemoautotroph An organism that relies upon inorganic chemicals for its energy and carbon dioxide for its carbon. Also called a chemolithotroph. lithoautotroph Bacteria that rely on inorganic minerals to supply their nutritional needs. Sometimes referred to as chemoautotrophs. chemoheterotroph Microorganisms that derive their nutritional needs from organic compounds. diffusion The dispersal of molecules, ions, or microscopic particles propelled down a concentration gradient by spontaneous random motion to achieve a uniform distribution.

osmosis The diffusion of water across a selectively permeable membrane in the direction of lower water concentration. isotonic Two solutions having the same osmotic pressure such that, when separated by a semipermeable membrane, there is no net movement of solvent in either direction. hypotonic Having a lower osmotic pressure than a reference solution. hypertonic Having a greater osmotic pressure than a reference solution. Active transport- nutrient transport method that requires carrier proteins in the membranes of the living cells and the expenditure of energy phagocyte A class of white blood cells capable of engulfing other cells and particles. pinocytosis The engulfment, or endocytosis, of liquids by extensions of the cell membrane. 6.2 minimum temperature The lowest temperature at which an organism will grow maximum temperature The highest temperature at which an organism will grow. optimum temperature The temperature at which a species shows the most rapid growth rate. psychrophile A microorganism that thrives at low temperature (0°C-20°C), with a temperature optimum of 0°C-15°C. mesophile Microorganisms that grow at intermediate temperatures. facultative Pertaining to the capacity of microbes to adapt or adjust to variations; not obligate. Example: The presence of oxygen is not obligatory for a facultative anaerobe to grow. See obligate. thermophile A microorganism that thrives at a temperature of S0°C or higher. pH The symbol for the negative logarithm of the H ion concentration; p (power) or (H*) A system for rating acidity and alkalinity.

osmophile A microorganism that thrives in a medium having high osmotic pressure. halophile A microbe whose growth is either stimulated by salt or requires a high concentration of salt for growth. radiation Electromagnetic waves or rays, such as those of light given off from an energy source. Barophile- a microorganism that thrives under high (usually hydrostatic) pressure symbiosis An intimate association between individuals from two species; used as a synonym for mutualism. mutualism Organisms living in an obligatory but mutually beneficial relationship. commensalism An unequal relationship in which one species derives benefit without harming the other. parasitism A relationship between two organisms in which the host is harmed in some way while the colonizer benefits. Antagonism- relationship in which microorganisms compete for survival in a common environment by taking actions that inhibit or destroy another organism synergism The coordinated or correlated action by two or more drugs or microbes that results in a heightened response or greater activity. quorum sensing The ability of bacteria to regulate their gene expression in response to sensing bacterial density. 6.3 Binary fission- the formation of two new cells of approximately equal size as the result of parent cell division generation time Time required for a complete fission cycle-from parent cell to two new daughter cells. Also called doubling time.

doubling time Time required for a complete fission cycle-from parent cell to two new daughter cells. Also called generation time. exponential Pertaining to the use of exponents, numbers that are typically written as a superscript to indicate how many times a factor is to be multiplied. Exponents are used in scientific notation to render large, cumbersome numbers into small workable quantities. growth curve A graphical representation of the change in population size over time. This graph has four periods known as lag phase, exponential or log phase, stationary phase, and death phase. growth factor An organic compound such as a vitamin or amino acid that must be provided in the diet to facilitate growth. An essential nutrient. lag phase The early phase of population growth during which no signs of growth occur. logarithmic or log phase Maximum rate of cell division during which growth is geometric in its rate of increase. Also called exponential growth phase. stationary growth phase Survival mode in which cells either stop growing or grow very slowly. death phase End of the cell growth due to lack of nutrition, depletion of environment, and accumulation of wastes. Population of cells begins to die. viable nonculturable (VNC) A description of a state in which bacteria are alive but are not metabolizing at an appreciable rate and will not grow when inoculated onto laboratory medium. turbid Cloudy appearance of nutrient solution in a test tube due to growth of microbe population. direct or total cell count 1. Counting total numbers of individuals cells being viewed with magnification. 2. Counting isolated colonies of organisms growing on a plate of media as a way to determine population y size.

polymerase chain reaction (PCR) A technique that amplifies segments of DNA for testing. Using denaturation, primers, and heat-resistant DNA polymerase, the number can be increased several-million-fold. Acidophilic- thriving in low-pH environments Chapter Summary 6.1 Microbial Nutrition • Nutrition is a process by which all living organisms obtain substances from their environment to convert to metabolic • Nutrients are categorized by the amount required (macronutrients or micronutrients), by chemical structure (organic of uses. inorganic), and by their importance to the organism's survival (essential or nonessential). • Microorganisms are classified both by the chemical form of their nutrients and the energy sources they utilize. • Although the chemical form of nutrients varies widely, all organisms require six elements-carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur-to survive, grow, and reproduce. • Nutrients are transported into microorganisms by two kinds of processes: active transport that expends energy and passive transport that does not need energy input. 6.2 Environmental Factors That Influence Microbes • The environmental factors that control microbial growth are temperature; gases; pH; osmotic, hydrostatic, and atmospheric pressure; radiation; and other organisms in their habitats. • Environmental factors control microbial growth mainly by their influence on microbial enzymes. • Three cardinal temperatures for a microorganism describe its temperature range and the temperature at which it grows best. These are the minimum temperature, the maximum temperature, and the optimum temperature. • Microorganisms are classified by their temperature requirements as psychrophiles, psychrotrophs, mesophiles, thermophiles, or extreme thermophiles.

• Most eukaryotic microorganisms are aerobic, whereas bacteria vary widely in their oxygen requirements from obligately aerobic to anaerobic. • Microorganisms live in symbiotic or nonsymbiotic association with other species that range from mutualism to parasitism and antagonism. • Biofilms are examples of complex synergistic communities of microbes that behave differently than free-living microorganisms. 6.3 The Study of Bacterial Growth • The splitting of a parent bacterial cell to form a pair of similar- size daughter cells is known as binary fission. • Microbial growth refers both to increase in cell size and increase in number of cells in a population. • The generation time is a measure of the growth rate of a microbial population. It varies in length according to environmental conditions and species of microbe. • Microbial cultures in a nutrient-limited batch environment exhibit four distinct stages of growth: the lag phase, the exponential growth (log) phase, the sta- tionary phase, and the death phase. • Microbial cell populations show distinct phases of growth in response to changing nutrient and waste conditions. • Population growth can be quantified by counting colony numbers, measuring the turbidity of a solution, and doing direct cell counts.

Chapter 6 Learning Objectives •List the essential nutrients of a bacterial cell ● ● ● ● ● ● ● ● ●

CHONPS Carbon Hydrogen Oxygen Phosphorus Potassium Nitrogen Sulfur Calcium

● ● ● ●

Iron Sodium Chlorine Magnesium

• Differentiate between macronutrients and micronutrients Macro: HOC Ex: Carbon, Oxygen, hydrogen: Large quantities used in cell structure and metabolism. Micro aka: trace elements: MN-Z EX) Zinc, Manganese, Nickel: Used in smaller amounts involved in enzyme function and maintenance of protein structure. • List and define four terms that describe an organism’s sources of carbon and energy - Carbohydrates -Lipids -Nucleic Acids -Proteins • Explain why the term parasite can be an oversimplification Parasites: Live on the bodies of living animals or plants • Compare and contrast diffusion and osmosis Osmosis only allows solvent molecules to move freely, but diffusion allows both solvent and solute molecules to move freely. ... Osmosis happens when molecules move from higher to lower concentrations, but diffusion happens when it is reversed.

• Identify the effects of isotonic, hypotonic, and hypertonic conditions on a cell with cell wall isotonic - water levels are equal on the inside and outside of the cell. hypotonic-water goes into cell and cell wall prevents cell wall from bursting hypertonic - water diffuses and shrinks protoplast from cell wall without cell wall -isotonic- rates of diffusion are equal in both directions -hypotonic- diffusion of water into the cell causes it to swell and may or may not burst if no mechanism exists to remove water -hypertonic- water diffusing out of the cell causes it to shrink and become distorted • Name 2 types of passive transport and 1 type of active transport • List and define 5 terms to express the temperature-related growth capabilities of microbes 1) Psychrophiles- -optimum temperature below 15 degrees celsius -capable of growth at 0 degrees celsius (freezing) -obligate with respect to cold and cannot grow above 20 degrees Celsius (room temperature) -storage at refrigerator temperature incubates rather than inhibits them -natural habitats of psychrophilic bacteria, fungi, and algae are lakes, rivers, snowfields, polar ice, and the deep ocean.

2) Psychrotrophs- -Grow slowly in the cold but have an optimum temperature between 15 degrees Celsius and 30 degrees Celsius -Staphylococcus aureus and Listeria monocytogenes are able to gorwn at refrigerator temperatures and cause food-borne disease 3) Mesophiles- -Majority of medical significant microorganisms -Grow at intermediate temperatures between 20 degrees Celsius and 40 degrees Celsius -Inhabit animals and plants as well as soil and water in temperature, subtropical, and tropical regions -Human pathogens have optimal temperatures between 30 degrees Celsius and 40 degrees Celsius 4) Thermoduric- -Can survive short exposure to high temperatures but are normally mesophiles -Common contaminants of heated or pasteurized foods. Examples: Are heat resistant cysts such as Giardia -Sporeformers such as Bacillus and Clostridium 5) Thermophile- Grows optimally at temperatures greater than 45 degrees Celsius -Live in soil and water associated with volcanic activity, compost piles, and in habitats directly exposed to the sun.

-Vary in heat requirements with a range of growth of 45 degree Celsius to 80 degrees Celsius -Most eukaryotic forms cannot survive above 60 degrees Celsius -Extreme thermophiles grow between 80 degrees Celsius and 121 degrees Celsius • Summarize 3 ways microorganisms function in the presence of differing oxygen conditions -Those that use oxygen -Those that neither use oxygen nor detoxify it -Those that use oxygen but can detoxify it • Identify 3 important environmental factors that microorganisms must cope with a) pH b) Osmotic Pressure c) Radiation and Hydrostatic/ atmospheric pressure • List and describe the 5 types of associations microbes can have with their hosts a) Mutualism: both members benefit b) Commensalism: one partner benefits, the other member is not harmed c) Parasitism: parasite is dependent and benefits, the host is harmed

d) Synergism: members cooperate and share nutrients e) Antagonism: some members are inhibited or destroyed by others • Discuss characteristics of biofilms that differentiate them from planktonic bacteria Biofilms are mixed communities of bacteria and other microbes that are attached to a surface and each other. They form a multilayer conglomerate of cells and intracellular material. The attached cells are stimulated to release chemicals as the cell population grows. Ex: biofilm grown on a gauze bandage • Define doubling time and describe how it leads to exponential growth Doubling time: The time required for a complete fission cycle- from parent cell to two new daughter cells. Generation increases the population by a factor of two. As long as the environment remains favorable, the doubling effect continues at a constant rate. The growth pattern is exponential and population numbers can be expressed in terms of logarithms. • Identify one culture-based and one non-culture based method for analyzing bacterial growth Culture-based - Length of Generation Time: measure of growth rate; environmental bacteria measured in months. Population Growth/Exponential Growth: how bacteria grow is looked at through population; population gets larger as time goes on.

Counting Bacterial Cells: counts living cells through Viable Plate Count: allows you to count # of living cells in any population BUT you must know what you're looking for and how to maintain it. Non-culture based - Turbidity: (fast way to count cells through measurement) nutrient solid becomes turbid, or cloudy, as microbes grow; the greater the turbidity, the larger the population -- turbidimeter. Direct Cell Count: measured microscopically to count cells in a population; disadvantage --> counts living & dead cells!!...