GENERAL MICROBIOLOGY INCREASE IN ________ OF MICROBIAL CELLS CHAPTER 6 MICROBIAL GROWTH-

MICROBIAL GROWTH REQUIREMENTS PHYSICAL –___________ –pH –osmotic pressure CHEMICAL –Carbon (C) –Oxygen (O) –____________ –Sulfur (S) Phosphorus _________________ factors Trace elements

PHYSICAL REQUIREMENTS for GROWTH : MINIMUM GROWTH TEMPERATURE –_______ temperature at which a species will grow OPTIMUM GROWTH TEMPERATURE –Temperature at which species will grow ____ MAXIMUM GROWTH TEMPERATURE –_______ temperature at which growth is possible TEMPERATUR E

CLASSIFICATION OF MICROBES: __________PHILES - ________ loving microbes Optimum growth temperature: 15 o C Capable of growing at 0 o C, but __________ Found in ocean depths, polar regions –Psychrotrophs-less temperature sensitive, some food spoilage ______PHILES - moderate temperature loving microbes –Optimum growth temperature: o C –Most common microbes –Food spoilage and disease ________PHILES heat loving microbes Optimum growth temperature: o C Minimum growth temperature: 45 o C Found in hot springs, compost piles TEMPERATURE RANGE of GROWTH

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

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

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

CHEMICAL REQUIREMENTS for GROWTH Carbon –Structural organic molecules, energy source Chemo__________ use _________ carbon sources Ex. Humans, fungi, protozoa, most bacteria, helminths Autotrophs -use CO 2 as carbon source Ex. Plants Nitrogen –In amino acids, proteins Sulfur –In __________, thiamine, biotin –Some bacteria use SO 4 2  or H 2 S Phosphorus –In DNA, RNA, ATP, and membranes –PO 4 3  is a source of phosphorus __________ 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

CHEMICAL REQUIREMENTS for GROWTH cntd. - OXYGEN Obligate _______-O 2 is required for growth Facultative anaerobes- growth ____ _______ when O 2 not present, O 2 preferred Obligate anaerobes -no growth when O 2 present- _________ O 2 ____tolerant anaerobes- can tolerate O 2 but can’t use it for growth Micro- aerophiles need ________ O 2 concentrations

_______ FORMS of OXYGEN Produced in small amounts during normal metabolic processes-harmful to cells Some Forms of Toxic Oxygen –Superoxide free radicals (O 2 -1 ) – very unstable, steal electrons from cellular molecules –Peroxide anion (O 2 -2 ) – contained in hydrogen peroxide –Hydroxyl radicals (OH - ) – most reactive MECHANISMS of ELIMINATION Superoxide free radicals ( ) H + superoxide H dismutase Peroxide anions ( ) 2H 2 O 2 __________ 2H 2 O + O 2 H 2 O 2 + 2H+ peroxidase 2H 2 O

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

_________PHILES Def.: Bacteria that require _________ concentration

Figure 6.5 ____________ Microbial communities Form slime or hydrogels –Bacteria attracted by chemicals via quorum sensing Share ____________ Sheltered from harmful factors Involved of infections –________, heart ________, contact lenses, dental caries

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 ________ 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 CULTURE MEDIA important terms

CULTURE MEDIA Chemically Defined Media: Exact chemical composition is known -Fastidious microorganisms- they require many growth factors provided in chemically defined media. _________ Media: Exact chemical composition _______; Extracts and digests of yeast, meats (organs), or plants Ex. Nutrient broth, nutrient agar

CULTURE MEDIUM for __________ MICROORGANISMS

________ 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 SELECTIVE MEDIA Figure 6.9b, c EMB Agar

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 DIFFERENTIAL MEDIA Figure 6.9a Lactose nonfermenter on MacConkey Agar Lactose Fermenter on___________ Agar

BOTH SELECTIVE and DIFFERENTIAL MEDIA 1.MacConkey Agar 2. Eosin Methylene Blue (EMB )Agar DIFFERENTIAL SELECTIVE for Gram (-) bacteria DIFFERENTIAL SELECTIVE for Gram (-) bacteria

ENRICHED MEDIA nutritionally fortified media which ___________ the growth of a wide range of microorganisms __________ Plate also differential

STREAK PLATE METHOD PROCEDURE for STREAKING for ISOLATION ISOLATED COLONIES on AGAR PLATE ______- a population of cells arising from a __________ or spore or from a group of attached cells A colony is often called a colony-forming unit (CFU)

Deep-freezing: -50°to -95°C Lyophilization (____________): Frozen (-54° to -72°C) and dehydrated in a vacuum PRESERVING BACTERIAL CULTURES

REPRODUCTION in PROKARYOTES ___________ Budding Conidiospores (actinomycetes) Fragmentation of filaments BINARY FISSION

Figure 6.13 Bacterial Exponential Growth Curve ____________ TIME: Time required for a cell to ______________

Figure 6.15 FOUR PHASES of TYPICAL ___________GROWTH

METHODS to DETECT and MEASURE BACTERIAL GROWTH (Numbers) DIRECT –___________* –Filtration –Most Probable Number (MPN) –Direct Microscopic Count* __________ –____________ Measurements* –_____________ Determination –Metabolic Activity Measurements*

DIRECT __________ METHOD Inoculate Petri plates from serial __________ of sample Used to count _______ bacterial cells only

______ MICROSCOPIC COUNT The number of microbes in a specific volume of bacterial suspension are counted using a special slide Ex.: PETROFF HAUSSER Does not distinguish between living and dead cells

________ Estimating Bacterial Numbers by Indirect Methods Figure 620 :_______ Measures number of cells present, dead or alive

Estimating Bacterial Numbers by Indirect Methods ____________ activity –Amount of certain metabolic products is in direct proportion to number of bacteria present –Examples: »O 2 Consumption »Acid Production Dry weight –Weight of packed cell mass is proportional to the number of cells in culture –Used for filamentous fungi