Effect of Physical Chemical and environmental factors on.ppt

very usefull for microbiology students

1. PRESENTATION ON
EFFECT OF PHYSICAL CHEMICAL AND
ENVIRONMENTAL FACTORS ON GROWTH
OF MICROORGANISMS
SUBMITTED TO: DR. (MRS.) SUNITA DEVI
PRESENTED BY: PUNEET KUMAR
M.Sc. MICROBIOLOGY 1
ST
YEAR
(F-2021-43-M)
COURSE CODE: MICRO 503
COURSE TITLE: MICROBIAL PHYSIOLOGY AND METABOLISM

2. INTRODUCTION
MICROBES
MICROBIAL GROWTH
DIFFERENT FACTORS AFFECTS THE GROWTH
PHYSICAL FACTORS
CHEMICAL FACTORS
ENVIROMENTAL FACTORS

3. Introduction to Microoganisms
Anorganismthatcanbeseenonlythrougha
microscope.Microorganismsincludebacteria,protozoa,
algae,andfungi.Althoughvirusesarenotconsideredliving
organisms,theyaresometimesclassifiedas
microorganisms.
TypesofMicroorganisms
Bacteria
Archaea
Protozoa
Fungi
Mold
Algae
Animals

4. Bacteria
Bacteria–nowsometimescalled“eubacteria”or“truebacteria”to
differentiatethemfromarchaebacteria–arethetypeofmicroorganism
youprobablyhearaboutthemost
Thisisbecausethey’rethetypemostlikelytomakeyousick.Bacteria
arethecauseofmostskininfections,andcanalsocausefood
poisoning,pneumonia,strepthroat,andmanyotherillnesses.
However,bacteriaarealsoveryhelpfultohumans.“Goodbacteria”in
ourdigestivetractshelpustoextractnutrientsfromourfood,andhelp
tofightpathogensthatcouldhurtus
Example:-E.coli,Salmonellasp.,Pseudomonassp.,Clostridiumsp.,etc

5. Archaea
Archaea,orarchaebacteria,wereoncethoughttobepartofthe
bacteriafamily
Archaeacanbefoundinmanyofthesameplacesasbacteria–in
water,insoil,andinsideourdigestivetracts,wheretheyhelpustostay
healthy.
However,archaebacteriacanalsobefoundinsomeunusualplaces–
manyareabletoliveinenvironmentsthatareveryhot,verycold,very
acidic,orverysalty.
Thismakesthemacommonfindinginsidehotspringsandother
placeswhereotherorganismscannoteasilysurvive.
Example:-Methanosarcinasp.,Hyperthermusbutylicus,
Staphylothermussp.,Thermococcussp.etc.

6. Protozoa
Protozoaareadiversegroupofunicellulareukaryoticorganisms.
Likebacteriaandarchaea,theyaresingle-celled;buttheircells
resemblethoseofanimalsandplantsmorethanthoseofbacteriaor
archaea.
Severaldangeroushumandiseasesincludingmalaria,toxoplasmosis,
giardia,African“sleepingsickness,”andChagasdiseasearecausedby
protozoa.
Example:-Amoeba,Paramoecium,Euglena,Trypanosoma,
Plasmodium.

7. Fungi
Thoughsomemicroscopicfungicaninfecthumansjustlikebacteriaor
protozoa,there’sonemicroscopicfungusthatmosthumanslikealot:
yeast.
Yeastisthefungusthatisresponsibleformakingbakedgoodsrise;
andforproducingalcoholicbeveragessuchasbeer,wine,andliquor.
Yeastfeedsonsugarsfoundinfoodsandconvertsitintocarbon
dioxide–andethylalcohol.
Thecarbondioxidecanmakeourbreadsandcakesfluffy.
Example:-yeasts,mildews,molds,andmushrooms.

8. Molds
Moldsaremicroorganismsthatsharesomepropertiesoffungi,butare
nottruefungi.
Theseincludepathogenicmoldsthatinfectplantsandhavecaused
devastatingcropfailuressuchastheGreatIrishFamineofthe1840s.
Theyalsoincludethefantasticallyweirdclassofslimemolds–single-
celledorganismsthatarecapableofcooperationsoimpressivethat,
duringonestageoftheirlifecycle,manyslimemoldcellsgather
togetherandoperatelikeasingleorganism.
Slimemoldintercellularcooperationissoimpressivethatscientists
havebeenusingslimemoldstostudyintelligenceandproblem-solving.
Example:-Rhizopussp.,Alternariasp.,Aspergillussp.,
Fusariumsp.,Penicilliumsp.Etc

9. Algae
Microscopicalgaewereoncethoughttobeplants,butrecentstudies
haveshownthatalgaedon’tfitintotheplantfamily.Instead,these
single-celledphotosyntheticorganismsarethoughttoberelativesof
thelineagethatledtolandplants.
Throughouthistory,algaehavebeenimportantphotosynthesizers.They
likelyevolvedbeforelandplantsdid,andhelpedtopumpoxygeninto
Earth’satmospherealongwiththeirancestors,thecyanobacteria.
Todayalgaecanbothhelpandhurthumans–somespeciesclean
waterandproduceoxygen,whileothersproducedangeroustoxinsthat
canendupinourseafoodanddrinkingwater.
Example:-Chlorophyta,Rhodophyta,Xanthophyta

10. Animals
Several types of animals come in microscopic varieties,
including:
Arthropods (dust mites, spider mites)
Rotifers (a type ofzooplankton)
Nematodes

11. GROWTH
AnOrderlyincreaseinthequantityofallthecellularconstituents.
Thegrowthofmicroorganismsisinfluencedbyvariousphysicaland
chemicalfactorsoftheirenvironment.
Physicalfactors-Temperature,pH,osmoticpressure,
hydrostaticpressureandradiation.
Chemicalfactors-Oxygen,carbon,nitrogen,phosphorus,
sulfur,etc.

12. Microbial Growth
CultureMedium:Nutrientmaterialpreparedformicrobial
growthinthelaboratory.
Requirements:
Mustbesterile
Containappropriatenutrients
Mustbeincubatedatappropriatetemperature
Culture:Microbesthatgrowandmultiplyinoronaculture
medium.

13. SolidMedia:Nutrientmaterialthatcontainsa
solidifyingagent(plates,slants,deeps).
Themostcommonsolidifierisagar,firstusedbyRobertKoch.
UniquePropertiesofAgar:
Meltsabove95*C.
Oncemelted,doesnotsolidifyuntilitreaches40*C.
Cannotbedegradedbymostbacteria.
Polysaccharidemadebyredalgae.
Originallyusedasfoodthickener(FannieHesse)

14. ChemicallyDefinedMedia:Nutrientmaterial
whoseexactchemicalcompositionisknown.
•Forchemoheterotrophs,mustcontainorganicsource
ofcarbonandenergy(e.g.:glucose,starch,etc.).
•Mayalsocontainaminoacids,vitamins,andother
importantbuildingblocksrequiredbymicrobe.
•Notwidelyused.
•Expensive.

15. ComplexMedia:Nutrientmaterialwhoseexactchemical
compositionisnotknown.
Widelyusedforheterotrophicbacteriaandfungi.
Madeofextractsfromyeast,meat,plants,proteindigests,etc.
Compositionmayvaryslightlyfrombatchtobatch.
Energy,carbon,nitrogen,andsulfurrequirementsareprimarilymet
byproteinfragments(peptones).
Vitaminsandorganicgrowthfactorsprovidedbymeatandyeast
extracts.
Twoformsofcomplexmedia:
•Nutrientbroth:Liquidmedia
•Nutrientagar:Solidmedia

16. SelectiveMedia:Usedtosuppressthegrowthofunwanted
bacteriaandencouragethegrowthofdesiredmicrobes.
Saboraud’sDextroseAgar:pHof5.6discouragesbacterial
growth.Usedtoisolatefungi.
BrilliantGreenAgar:Greendyeselectivelyinhibitsgram-positive
bacteria.Usedtoisolategram-negativeSalmonella.
BismuthSulfiteAgar:UsedtoisolateSalmonellatyphi.Inhibits
growthofmostotherbacteria.

17. Microbial Growth Phases.

18. DIAUXIC GROWTH

19. DIFFERENT FACTORS AFFECT
THE GROWTH OF MICROBS
•PHYSICAL FACTORS
•CHEMICAL FACTORS
•ENVIROMENTAL FACTORS

20. Physical factors influencing the
growth of microorganisms
Temperature pH
Osmotic
Pressure
Hydrostatic
Pressure
Radiation

21. Temperature
Temperatureisthemostimportantfactorthatdetermines
therateofgrowth,multiplication,survival,anddeathof
alllivingorganisms.
Hightemperaturesdamagemicrobesbydenaturing
enzymes,transportcarriers,andotherproteins
Microbialmembranearedisruptedbytemperature
extremes.
Atverylowtemperaturesmembranesalsosolidifyand
enzymesalsodonotfunctionproperly.

22. Types of temperature
Minimum
growth
temperature
Maximum
growth
Temperature
Optimum
growth
temperature

23. 1.Minimumgrowthtemperature
Thelowesttemperatureatwhichorganismsgrowistheminimum
growthtemperature.
2.Optimumgrowthtemperature
Thetemperatureatwhichthemostrapidrateofmultiplicationoccurs.
3.Maximumgrowthtemperature
Thehighesttemperatureatwhichgrowthoccurs.
Atemperatureonlyslightlyabovethispointfrequentlykillsthe
microorganismsbyinactivatingcriticalenzymes.

33. MostbacteriapreferneutralpH(6.5-7.5).
MoldsandyeastgrowinwiderpHrange,butpreferpH
between5and6.
Acidityinhibitsmostmicrobialgrowthandisused
frequentlyforfoodpreservation(e.g.:pickling).
Alkalinityinhibitsmicrobialgrowth,butnotcommonly
usedforfoodpreservation.
Acidicproductsofbacterialmetabolisminterferewith
growth.
BufferscanbeusedtostabilizepH.

37. OsmoticPressure:Cellsare80to90%water.
A.Hypertonicsolutions:Highosmoticpressure
removeswaterfromcell,causingshrinkageofcell
membrane(plasmolysis).
Usedtocontrolspoilageandmicrobialgrowth.
Sugarinjelly.
Saltonmeat.
B.Hypotonicsolutions:Lowosmoticpressurecauses
watertoenterthecell.Inmostcasescellwallprevents
excessiveentryofwater.
Microbemaylyseorburstifcellwallisweak

41. Chemical factors influencing the growth
of microorganisms
Carbon
Nitrogen
Sulfur
Oxygen
Phosphorus

42. Carbon:Makesup50%ofdryweightofcell.
Structuralbackboneofallorganiccompounds.
Chemoheterotrophs:Obtaincarbonfromtheirenergy
source:lipids,proteins,andcarbohydrates.
ChemoautotrophsandPhotoautotrophs:Obtain
carbonfromcarbondioxide.

43. Nitrogen:
Nitrogen:Makesup14%ofdrycellweight.Usedtoform
aminoacids,DNA,andRNA.
Sourcesofnitrogen:
Protein:Mostbacteria
Ammonium:Foundinorganicmatter
Nitrogengas(N
2):ObtainNdirectlyfromatmosphere.
Importantnitrogenfixingbacteria,livefreeinsoilor
associatedwithlegumes(peas,beans,alfalfa,clover,
etc.).Legumecultivationisusedtofertilizesoilnaturally.
Nitrates:SaltsthatdissociatetogiveNO
3-

44. Sulfur:Usedtoformproteinsandsomevitamins
(thiamineandbiotin).
Sourcesofsulfur:
Protein:Mostbacteria
Hydrogensulfide
Sulfates:SaltsthatdissociatetogiveSO
4
2-
Phosphorus:UsedtoformDNA,RNA,ATP,and
phospholipids.
Sources:Mainlyinorganicphosphatesaltsandbuffers.
Oxygen:Organismsthatusemolecularoxygen(O
2),
producemoreenergyfromnutrientsthananaerobes.
Canclassifymicroorganismbasedontheiroxygen
requirements:

45. ObligateAerobes:Requireoxygentolive.
Disadvantage:Oxygendissolvespoorlyinwater.
Example:Pseudomonas,commonnosocomialpathogen.
FacultativeAnaerobes:Canuseoxygen,butcangrowinitsabsence.
Havecomplexsetofenzymes.
Examples:E.coli,Staphylococcus,yeasts,andmanyintestinalbacteria.
ObligateAnaerobes:Cannotuseoxygenandareharmedbythepresence
oftoxicformsofoxygen.
Examples:Clostridiumbacteriathatcausetetanusandbotulism.
AerotolerantAnaerobes:Can’tuseoxygen,buttolerateitspresence.
Canbreakdowntoxicformsofoxygen.
Example:Lactobacilluscarriesoutfermentationregardlessofoxygen
presence.
Microaerophiles:Requireoxygen,butatlowconcentrations.Sensitiveto
toxicformsofoxygen.
Example:Campylobacter.

46. Toxic Forms of Oxygen:
Singlet Oxygen
Superoxide Free Radicals (O
2-)
Hydrogen Peroxide (H
2O
2)

47. Other Elements: Potassium, magnesium, and calcium
are often required as enzyme cofactors. Calciumis
required for cell wall synthesis in Gram positive bacteria.
Trace Elements: Many are used as enzyme
cofactors.
Commonly found in tap water.
Iron
Copper
Molybdenum
Zinc

48. Environmental factors influencing the
growth of microorganisms
Moisture
Temperature
Oxygen pH
Carbon
Dioxide
Light

49. Moisture:
Waterisanessentialcomponentforthegrowthofthebacteria.
80%ofthebacterialcellismadeupofwater.
Therefore,thepresenceofafreewatermoleculeisimportant
fortheoptimumgrowthofthemicroorganism.
Apartfromthatdesiccationordryinghasasevereeffecton
microbes.
ForexampleTreponemapallidum,Neisseriagonorrhoeaecan
dieeasilyduetodesiccation
WhilebacterialpathogenslikeM.tuberculosis,S.aureuscan
survivedesiccationforseveralweeks

50. Temperature
Itisanessentialenvironmentalfactorthatcaninfluencethe
growthoftheorganisms.Mostofthepathogensgrowat
37
0
C(bodytemperature).Bacteriaarecategorizedunder
threegroupsonthebasisoftheoptimumtemperature
range
•Mesophile:Theoptimumtemperaturerangefor
mesophilesis25
0
Cto40
0
CMostofthepathogenicbacteria
comeunderthisgroup.
•Psychrophile:Theoptimumtemperaturefor
psychrophilesisbelow20
0
C
•Thermophile:Theoptimumtemperaturerangefor
thermophilesis55
0
Cto80
0
CEg:Bacillus
stearothermophilus.

51. Carbon Dioxide
Mostofthebacteriarequireasmallamountofcarbon
dioxideforgrowth.Thiscarbondioxideisusuallyprovided
bytheenvironmentoritcanbeproducedbythebacteria
duetocellularmetabolism.
BacteriathatrequireahighlevelofCarbondioxidefor
growthareknownascapnophilicbacteria.

52. Oxygen
Onthebasisofrequirementofoxygen,bacteriaareclassified
underthree groups
Aerobes:Oxygenisstrictlyrequiredforthegrowthofthese
bacteria.Eg:Pseudomonasaeruginosa.
FacultativeAnaerobes:Thesearethegroupofbacteriathat
cangrowbothunderthepresenceandabsenceofoxygen.Most
ofthepathogenicbacteriaarefacultativeanaerobes.Eg:E.coli.
Anaerobes:Thesearealsoknownasobligateanaerobesas
theycan’tgrowinthepresenceofoxygenattheenvironment.
Eg:Clostridiumtetani.
Apartfromthese,thereisanothergroupcalledmicroaerophilic
whichgrowsinthepresenceofatraceamountofoxygen.
Eg:Helicobacterpylori.

53. pH
pHisanessentialfactorforthegrowthofthemicrobes.
Maybacteriaareabletoproduceseveralorganicacids
whichreducethepHofthemediumandalsorestrictthe
growthofotherbacteria.
Apartfromthatsomemediaconstituentscanbeaffected
bylowpH.
Therefore,maintaintheoptimumpHishighlyimportantto
obtainadequategrowthoftheorganisms.
PathogensaremostlyrequiringneutralpH(7.2).
However, industriallyimportantbacteriasuch
asLactobacilluslactisrequiresalowerpHforoptimum
growth.

54. Light
Phototrophicbacteriarequirelightforthegrowth.However,
mostofthebacteriacangrowwellindarkness.
Thepresenceofultravioletraysandradiationcan
reducebacterialgrowth.
Photochromogenicmycobacteriumisaunique
speciesthatproducepigmentsonlyatthepresenceoflight.