ch 5 microbial growth
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jessieannsmith on April 17, 2012
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104 terms
Terms | Definitions |
|---|---|
 growth | an orderly increase of all major chemical constituents of an organism 1. increase in total mass is not necessarily growth since it may be due to accumulation of cellular reserve material 2. growth normally results in cellular multiplication except for coenocytic (multinulciated) organisms 3. multicellular organism results in an increase of size of the individual unicellular organisms result in an increase in the number or indivuals |
| cell growth | depends on a large number of chemical reactions; metabolism |
| biosynthesis | sythesize small molecules; building blocks, coenzymes, vitamins |
| fueling | transform energy |
| polymerization | most significant reaction that makes the macromolecules |
| assembled | as molecules are sythesized and accumulated in cells, they are assembled into cell structures and cell grows in size and eventually divides |
| transverse or binary fission | most common means of unicellular microbial reproduction two cells arise from one cells elongate to twice thier length, form a partition, and seperate into two cells septum results from invagination |
| septum | forms in the middle of the undivided cell results from invaination inward growth of cytoplasmic membrane and cell wall from opposing direction |
| Fts | filamentous temperature sensitive proteins essential for division mutations in genes encoding these cause the cells to not divid normally-long filamentous cells that fail to divide fts intract to form divisome |
| fts formation of divisome | formation begins with attachement of molecules of FtsZ in ring around center of cell; attracts other divisome proteins ring defines cell division plate |
| Zip A | anchor that connects FtsZ ring to cytoplasmic membrane |
| FtsA | protein that also helps connect FtsZ ring to cytoplasmic membrane |
| FtsI | proteins needed for peptidoglycan sythesis (penicillin binding protein) activity blocked by pencillin (ie. stop growth) |
| FtsZ ring | DNA replicates before FtsZ ring is formed ring forms in space between nucleoids Min proteins ensure that the ring forms only at cell center cell constricts -> ring depolarizes, triggering inward growth of wall materials to form septum GTP hydrolysis provides engery |
| Min proteins | ensures that FtsZ ring forms only at cell center |
| FtsK & other proteins | help the two copies of chromosome pull apart |
| energy for cell division | GTP hydrolysis |
| divisome | cells already elongating and DNA is replicating before divisome is formed divisome responsible for regulating sythesis of new cell membrane & wall material produces divisome septum, at center of dividing cell, until it reaches twice its length & divides yielding two daughter cells |
| FtsZ Ring & Divisome | 1. FtsZ ring not yet formed 2. FtsZ ring appears as nucleoids start to segregate 3. full FtsZ ring forms as cell elongate 4. breakdown of FtsZ ring and cell division |
| Protein MinE | directs formation of the FtsZ ring and divisome complex at the cell division plate |
| MinC & MinD | most abundant at the cell poles prevent cell division & at poles |
| MreB | cytoskeleton protein actin analog that winds as coil through the long axis of rod shaped cells making contact with the cell membrane at sites of sythesis |
| Crescentin | shape determing protein |
| peptidoglycan sythesis | sythesis of new peptidoglycan during growth -cut preexisting peptidoglycan; autolysins -simultaneous insertion of peptidoglycan precursors cell wall is outside of membrane; thus peptidoglycan precursors must be transported through cell membrane transpeptidation; final step |
| autolysins | cut preexisting peptidoglycan |
| bactoprenol | C55 lipid binds peptidoglycan precursors transports through membrane to be inserted into growing point in cell wall glycolases make glycosidic bonds |
| glycolases | make glycosidic bonds in peptidoglycan sythesis |
| transpeptidation | final step of peptidoglycan synthesis inhibited by penicillin penicillin binds to FtsI and other penicillin binding proteins in absence of crosslinks and new cell wall sythesis, continue activity of autolysins weakens cell wall causing osmotic lysis |
| osmotic lysis | caused by the absence of crosslinks and new cell wall sythesis, continue activity of autolysins that weaken the cell wall |
| FtsI | thought to be important in catalyzing transpeptidase reaction involved in peptidoglycan sythesis penicillin binding protein activity blocked by penicillin |
| budding | in yeast type of division that results in unequal distribution of cellular material newly sythesized in bud & original cell |
| binary fission | in yeast equal distribution of cellular materials in division |
| measurement of cell growth | quanitative measurement of two different parameters usually equivlant bc of nonsynchronous growth; cell number or cell mass expressed #cells/mL or mg cells/mL |
| cell mass vs. cell division | cell mass is continuous cell division is discontinuous proved by synchronous growth |
| bacterial growth curve | represents ONE SELECTED PORTION of a normal growth curve NOT the normal pattern of bacterial growth logarithmic or exponential phase |
| exponential growth | characteristic of microbial populations does not normally continue for long periods of time the pattern of population increase where the number of calls double during each unit of time period |
| phases of bacterial gorwth; entire growth cycle | lag phase exponential or log phase stationary phase death phase |
| lag phase | does not always occur in growth of bacterial population, when it does, the duration can vary considerably k=0 when a microbial population is inoculated into fresh medium, growth usually does not take place immeditatly, but only after a period of time called the lag phase occurs because for the growth to occur in a particular medium, the cells must have complete completion of enzymes for synthesis for the essential metabolites not present in that medium metabolism occurs in the lag phase I, II, III, and IV no increase in cell number as IV occurs, the cell gets larger and prepares to divide as cell divides it transitions to exponentail phase |
| when can lag phase occur? | 1. incolate cells from stationary or death phase into fresh medium 2. incoluate cells from exponentail phase into a fresh medium of a DIFFERENT chemical composition |
| when can lag phase NOT occur? | incoluated cells growing exponentially into a fresh medium of same chemical compostion |
| biphasic growth | stationary culture cells and incoluated into a memdium containing both glucose and lactose growth first on most rapidly metabloized C source, glucose then lag pahes last, growth on lactose |
| exponential phase | the pattern of population increase where the number of calls double during each unit of time period Nt=1 n=0 Nt=2 n=1 Nt=4 n=2 Nt=8 n=3 Nt=16 n=4 Nt=32 n=5 Nt=64 n=6 |
| g= | g=.301t/(logNt-logNo) |
| stationary phase | in a tube or flask, with limited nutrients, exponential growth cannot occur indefinently primarily occurs because 1. an essential nutrient of the medium is used up 2. waste by product of the organism builds up to an ihibitory level there is no net increase or decrease in cell number but many cell functions can continue |
| death phase | when cells are no longer able to find the nutrients needed then cells can die also exponential, but slower than growth exopential rate |
| microscopic count | method for measuring bacterial growth enumeration of bacteria in milk and vaccines |
| plate count | method for measuring bacterial growth same as membrane or molecular filter enumeration of bacteria in milk, water, food, soil cultures, ect. |
| membrane or molecular filter | method for measuring bacterial growth same as plate count enumeration of bacteria in milk, water, food, soil cultures, ect. |
| turidmetric measurements | method for measuring bacterial growth microbioal assays estimation of cell crop in broth cultures or aq solutions |
| nitrogen determination | method for measuring bacterial growth same as wight determination measurement of cell crop from heavy culture suspension to be used in metabolism |
| weight determination | method for measuring bacterial growth same as nitrogen determination measurement of cell crop from heavy culture suspensions to be used for research in metabolism |
| measurement of biochemical activity | microbiological assays |
| turbidity | optical density in stationary phase spectrophotometer nepholometer |
| spectrophotometer | measures light passing through the solution |
| nepholometer | measures scattered light |
| procedure for direct microscopic count | 1. a small portion (0.01 to 0.02 mL) of a bacterial suspension is smeared on a glass slide in a prescribed area 2. the film is stained and the # of microorganisms per microscopic field is recorded it is desirable to have 1-2 MO per field and to count 50 microscopic fields if more than that number is present, fewer fields may be counted |
| Petroff-Hauser slide | alternative procedure for direct microscopic count a special slide and cover slip which contain a known volume is used |
| Microscopif factor MF= | MF=Af/Amf Af= area of the film Amf= area of the mircoscopic field |
| spread-plate method | 1. sample if pipetted onto surface of agar plate 2. sample is spread evenly over surface of agar using sterile glass spreader 3. incubation 4. surface colonies |
| pour-plate method | 1. sample is pipetted into sterile plate 2. sterile medium is added and mixed well with inoculum 3. incubation 4. surface colonies & subsurface colonies |
| environmental effects on growth | rates of growth and total amount of growth are governed by physical and chemical environment of the cell 1. physical environment 2. chemical environment 3. any marked change in the environment produces a corresponding change in the morphological and/or physiological characteristics of the organism 4. knowledge of conditions that govern growth for total concentration and survival is directly applied to control microorganisms of the product that they produce microbial nutrition 1. different types of media; sythetic, natural, selective, diffential, or enrichment |
| physical environmental factors | temp, hydrostatic pressure, osmotic pressure, surface tension, visible radiation, uv radiation, gravity, adsorption phenomena, viscosity |
| chemical environmental factors | water activity, water structure, pH, inorganic nutrients quantity and quality, gasses quality and quantity, hormones, growth regulations, metabolic control substances, poisons, inhibitors and nutrient analogs, ox-red potential |
| sterlization | treatment which frees objects of all living organisms inculding enospores autoclaving 15 mintues @ 121 C, 2 ATM |
| death | irreversible loss of the ability to reproduce |
| temperature effects | as temp rise, chemical and enzymatic reactions in the cell increase and growth becomes faster the rate of an enzymic rxn increases 2-3X for ever 10C increase in temp above certain temp, particular proteins may be irreversibly damaged |
| cerdinal temperatures | minimum temperature optimum temperature maximum temperature |
| minimum temperature | below which no growth occurs membrane gelling transport processes so slow that growth cannot occur |
| optimum temperature | growth is most rapid always closer to the max temp than the min temp enzymatic reactions occuring at maximal possible rate |
| maximum temperature | above which growth is not possible protein denaturation collapse of the cytoplasmic membrane thermal lysis |
| psychrophile | low temp optimum of 15C or lower max. below 20C min. below 0C ex. snow algea & polarmonas vacuolata (4C) if grow at 0C but optimum 20-40C then psychrotolerant & more widely distributed |
| mesophiles | optimum above 15C to approx. 40C (slightly above human body temp) ex. escherichia coli (35C) |
| thermophile | optimum exceeds 45C ex. bacilius stearothermophilus (60C) |
| hyperthermophiles | optimum often above 80C ex. thermococcus celer (80C) & pyrolobus fumarii (106C) -soil surfaces in sun can get to 50-70C; hot springs |
| acidophiles | increasing acidity |
| alkalinphiles | increase alkanility (basidity) |
| pH= | pH=-loh[H+] |
| Aw= | water activity=Psoln/Pwater most bacteria grow above .95 Aw is always less than or equal to 1 |
| nonhalophile | ex. escherichia coli |
| halotolerant | ex. staphylococcus aureus |
| halophile | ex. vibrio fischeri |
| exterme halophile | ew. holabacterium salinarum |
| compatible solutes | solutes used inside the call for adjustment of cytoplasmic water activity staph uses amino acid proline (7.5%) glycine bacteria in halophilic bacteria & cyano bacteria |
| compatible solute for staph | amino acid proline(7.5%) |
| glycine is a compatible solute for.. | halophilic bacteria & cyano bacteria |
| oxygen classes | aerobes & anaerobes |
| aerobes | species capable of growth at full oxygen tensions (air is 21% O2) many can tolerate elevated concentrations of oxygen (hyperbaric oxygen) 1. obligated aerobes 2. microaerophiles 3. facultative aerobes |
| obligated aerobes | aerobes that require O2 for growth growth at top of medium only have enzymes catalase and SOD (superoxide dismutase |
| microaerophiles | aerobes that can use O2 only when it is present at levels reduced from that in air (lower than 21%) usually because of thier limited capacity to respire or because they contain some oxygen-sensitive molecule required, but at levels below atmosphere levels growth mostly at top but slightly spreading down |
| facultative aerobes | aerobes that, under appropriate nutrient and culture conditions, can grow in EITHER aerobic or anaerobic conditions O2 not required but grow better with it growth throughout the medium have enzymes catalase and SOD (superoxide dismutase) |
| anaerobes | organisms that cannot respire oxygen (O2) 1. aerotolerant anaerobes (facultative anaerobes) 2. obligate (strict) anaerobes |
| aerotolerant anaerobes | aka facultative anaerobes can tolerate oxygen and grow in its presence even through they can not use it not required, and grow no better with it growth through out lack enzyme catalase but have SOD (superoxide dismutase) |
| obligate anaerobes | aka strict anaerobes inhibited or even killed by oxygen harmful or lethal growth only on bottom lack enzymes catalase & SOD (superoxide dismutase) ex. clostridia, methanobacteria, and ruminococci |
| superoxide by product of electron tansport to oxygen | O2 + e- -> O2- |
| hydrogen peroxide by product of electron tansport to oxygen | O2- + e- + 2H+ -> H2O2 |
| hydroxyl radical | H2O2 + e- + H+ -> H2O + OH. |
| water by product of electron tansport to oxygen | Oh. + e- + H+ -> H2O |
| enzymes to remove toxic by products of oxygen metabolism | catalase peroxidase superoxide dismutase superoxide dismutase/catalase in combination superoxide reductase |
| catalase | H2O2 + H2O2 -> 2H2O + O2 |
| peroxidase | H2O2 + NADH + H+ -> H2O2 + O2 |
| superoxide dismutase | O2- + O2- +2H+ -> H2O2 + O2 |
| superoxide dismutase/catalase in combination | 4O2- + 4H+ -> 2H2O + 3O2 |
| superoxide reductase | O2- + 2H+ + cytcreduced -> H2O2 +cytcoxidized |
| enzymes | obligate and faculative aerobes have both catalase and SOD (superoxide dismutase) aerotolerant anaerobes lack catalase but have SOD obligated anaerobes lack both ex. clostridia, methanobacteria, and ruminococci |
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