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GENERAL MICROBIOLOGY

GENERAL MICROBIOLOGY. CHAPTER 6 MICROBIAL GROWTH-. INCREASE IN _________ OF MICROBIAL _______. PHYSICAL temperature _______ __________ CHEMICAL Carbon (C) Oxygen (O) Nitrogen (N) Sulfur (S). Phosphorus Organic growth factors Trace elements.

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GENERAL MICROBIOLOGY

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  1. GENERAL MICROBIOLOGY CHAPTER 6MICROBIAL GROWTH- INCREASE IN _________ OF MICROBIAL _______

  2. PHYSICAL temperature _______ __________ CHEMICAL Carbon (C) Oxygen (O) Nitrogen (N) Sulfur (S) Phosphorus Organic growth factors Trace elements MICROBIAL GROWTH REQUIREMENTS

  3. PHYSICAL REQUIREMENTS for GROWTH : TEMPERATURE • _________GROWTH TEMPERATURE • Lowest temperature at which a species will grow • __________GROWTH TEMPERATURE • Temperature at which species will grow ____ • MAXIMUM GROWTH TEMPERATURE • _______ temperature at which growth is possible

  4. CLASSIFICATION OF MICROBES: TEMPERATURE RANGE of GROWTH • PSYCHROPHILES - coldloving microbes • Optimum growth temperature: _________ • Capable of growing at 0oC, but not at 250C • Found in ocean depths, polar regions • Psychrotrophs-less temperature sensitive, some food spoilage • ___________ - moderate temperature loving microbes • Optimum growth temperature: __________ • Most common microbes • Food spoilage and disease • THERMOPHILES - _____loving microbes • Optimum growth temperature: 50-60oC • Minimum growth temperature: 45oC • Found in hot springs, compost piles

  5. ACID BASE CHEMISTRY pH scale - logarithmic scale used to measure H+ concentration • ____ – a substance that dissociates into hydrogen ions (H+) and negative ions in aqueous solution Ex. Hydrochloric acid, citric acid • ____ – a substance that dissociates into hydroxide ions (OH-) and positive ions in aqueous solution Ex. Sodium hydroxide

  6. PHYSICAL REQUIREMENTS for GROWTH cntd.:pH • Most bacteria grow between pH __________ • Molds and yeast grow between pH _________ • Acidophiles grow in acidic environments _______ – compounds that keep ___ from changing drastically; ex. peptones, amino acids, phosphate salts-very important in the preparation of microbial media!!

  7. PHYSICAL REQUIREMENTS for GROWTH cntd. Osmotic Pressure the force used by a solvent in moving from an area with a lower _____concentration to an area of higher __________concentration • _____ environments - concentration of solute (ex. salt or sugar) is higher outside cell, causes plasmolysis • Results in loss of water from a cell • Inhibits ______________ • Used to preserve food, ex.Salted fish __________ - require higher salt concentrations in their environment and therefore high osmotic pressure

  8. ________ REQUIREMENTS for GROWTH • Carbon • Structural organic molecules, energy source Chemoheterotrophs use _______________ sources Ex. Humans, fungi, protozoa, most bacteria, helminths Autotrophs -use ______ as carbon source Ex. Plants • Nitrogen • In amino acids, proteins • Sulfur • In amino acids, thiamine, biotin • Some bacteria use SO42 or H2S • Phosphorus • In DNA, RNA, ATP, and membranes • PO43is a source of phosphorus • Trace Elements • Inorganic elements required in small amounts: Fe, Cu, Mb, Zn • Organic Growth Factors • Organic compounds obtained from the environment • Vitamins, amino acids, purines, pyrimidines

  9. CHEMICAL REQUIREMENTS for GROWTH cntd. - OXYGEN

  10. _______ FORMS of OXYGENProduced in small amounts during normal metabolic processes-harmful to cells Some Forms of Toxic Oxygen • Superoxide free radicals (O2-1) – very unstable, steal electrons from cellular molecules • Peroxide anion (O2-2) – contained in hydrogen peroxide • Hydroxyl radicals (OH-) – most reactive MECHANISMS of ELIMINATION Superoxide free radicals (02-1) 02- + 02- + 2H+superoxide _____ + 02 dismutase Peroxide anions (02-2) 2H2O2________ 2H2O + O2 H2O2 + 2H+ peroxidase 2H2O

  11. _________ CULTURE METHODS 1. Reducing media contains chemicals (sodium thioglycolate) that combine with O2 Media is heated to drive off O2 3. ANAEROBIC JAR 4. ANAEROBIC CHAMBER 2. OxyPlates _________________ that reduces oxygen to water is added to growth media, transforms petri plate into an anaerobic chamber

  12. _______________ Def.: Bacteria that require high ______ concentration

  13. ____________ • Microbial communities • Form _____ or hydrogels • Bacteria attracted by _________ via quorum sensing • Share nutrients • Sheltered from harmful factors Figure 6.5

  14. CULTURE MEDIAimportant terms • Culture Medium: ________ (or any material) prepared for the growth of microbes in a laboratory • Sterile: No________ microbes • Inoculate: Introduction of microbes into medium • Culture: Microbes growing in/on culture medium • _____ culture -contains only one species or strain of bacteria • Agar: Complex _________ (from marine algae) • Used as solidifying agent for culture media in Petri plates, slants, and deeps • Generally not metabolized by microbes • Liquefies at 100°C • Solidifies ~40°C

  15. CULTURE MEDIA Chemically Defined Media: Exact chemical composition is known ____________Media: Exact chemical composition not known; Extracts and digests of yeast, meats (organs), or plants Ex. Nutrient broth, nutrient agar

  16. CULTURE MEDIUM for __________ MICROORGANISMS

  17. SELECTIVE MEDIA • ___________unwanted microbes and encourage desired microbes. Ex. Eosin Methylene Blue Agar(EMB) and MacConkey agar-allows Gram (-) bacteria to grow but not Gram (+) bacteria. EMB Agar EMB Agar Figure 6.9b, c

  18. DIFFERENTIAL MEDIA • Used to _________ colonies of different microbes based on specific properties such as: lactose fermenting bacteria from lactose non-fermenting bacteria; Ex.: MacConkey and EMB agar Lactose nonfermenter on MacConkey Agar Lactose Fermenter on Mac Conkey Agar Figure 6.9a

  19. BOTH SELECTIVE and DIFFERENTIAL MEDIA 1.__________ Agar SELECTIVEfor Gram (-) bacteria DIFFERENTIAL 2. ___________________ (EMB )Agar SELECTIVE for Gram (-) bacteria DIFFERENTIAL

  20. ___________ MEDIAnutritionally fortified media which encourages the growth of a wide range of microorganisms Blood Agar Plate also differential

  21. ____________ METHOD ISOLATED COLONIES on AGAR PLATE PROCEDURE for STREAKING for ISOLATION Colony- a population of cells arising from a single cell or spore or from a group of attached cells A colony is often called a colony-forming unit (CFU)

  22. PRESERVING BACTERIALCULTURES • Deep-freezing: -50°to -95°C • Lyophilization (_______________): Frozen (-54° to -72°C) and dehydrated in a vacuum

  23. ____________ in PROKARYOTES ________________ • ________________ • Budding • Conidiospores (actinomycetes) • Fragmentation of filaments

  24. Bacterial _______________ Curve GENERATION TIME: Time required for a cell to____________ Figure 6.13

  25. FOUR TYPICAL PHASES of __________ GROWTH BACTERIAL GROWTH CURVE Figure 6.14

  26. DIRECT _______________* Filtration Most Probable Number (MPN) Direct _____________ Count* INDIRECT ______________ Measurements* Dry Weight Determination Metabolic Activity Measurements* METHODS to DETECT and MEASURE BACTERIAL __________ (__________)

  27. Direct __________ Method Plate Count Method • Inoculate Petri plates from ____________ • Used to count _________ bacterial cells ________ Figure 6.16

  28. DIRECT ____________ COUNT The number of microbes in a _____________ of bacterial suspension are counted using a special slide Ex.: PETROFF HAUSSER Does not distinguish between ______________________

  29. Estimating Bacterial Numbers by Indirect Methods :IndirectlyMeasures number of cells present, ____________ ________ Figure 620

  30. Estimating Bacterial Numbers by Indirect Methods • Metabolic activity • Amount of certain metabolic products is in direct proportion to number of bacteria present • Examples: • _____________ • ___________ Production • Dry weight • Weight of packed cell mass is proportional to the number of cells in culture • Used for _________________

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