Types of Bacteria

A presentation on the types of bacteria (and archaea) based on various parameters.

1. TYPES OF BACTERIA
BASED ON VARIOUS PARAMETERS
SYED MUHAMMAD KHAN
(BS HONS. ZOOLOGY)

2. INTRODUCTION
Bacteria and Archaeacan be categorized on the basis of the following:
Domain
Optimumtemperature
Oxygenrequirement
Flagellararrangement
Modeofnutrition
OptimalpHforgrowth
Shape
Sporeformation
Extremenutrientconc.
Saltrequirement
Gramstaining
Capsule

3. TYPES OF PROKARYOTES ON THE
BASIS OF DOMAIN
•Archaea
•Bacteria (Eubacteria)

4. ARCHAE
Archaea/Arachaeobacteriaareprimitiveunicellularprokaryoteswhichare
foundinextremeenvironments(theyareextremophiles)suchasindeepsea,
hotsprings,alkalineoracidwater.
Theyhavemembranelipidsthatarebranchedhydrocarbonchainsattachedto
glycerolbyetherlinkages.
ThepresenceoftheseetherlinkagesinArchaeaaddstotheirabilityto
withstandextremetemperaturesandhighlyacidicconditions,althoughmany
archeaeliveinmildenvironments.
Archaeaevolvedmanycellsizes,butallarerelativelysmall.Theirsizeranges
from0.1μmto15μmdiameterandupto200μmlong.
Theyareaboutthesizeofbacteria,orsimilarinsizetothemitochondria
foundineukaryoticcells.

5. ARCHAE
Archaealso differ from bacteria in their cell wall composition, i.e. their cell
walls are made up of pseudomurein, proteins, heteropolysaccharides, etc.
Cell Walls of various Archae

6. ARCHAE
Archaeaareofthreetypes:
1.Methanogens:Thesearchaeacanproducemethane(byreducing
carbondioxide)andareobligateanaerobes.Theyarefoundinthe
intestinaltractsofanimalsandhumans,andinsewagewater.
ExamplesincludeMethanococcusspp.andMethanobacteriumspp.
2.Halophiles:Thesearchaeaarefoundinsaltenvironmentssuchasthe
DeadSeaandtheGreatSaltLake.ExamplesincludeHalococcusspp.
andHalobacteriumspp.
3.Thermoacidophiles:Thesearchaeathriveinextremelyhotand
acidicenvironmentssuchasvolcanoesandhydrothermalvents.
ExamplesincludeSulfolobusspp.andThermoplasmaspp.

7. EUBACTERIA
EubacteriaincludeallprokaryotesexceptArchaea.
Theyaremorecomplexandcomparativelymoremodernthan
Archaea.
Theycanliveinbothharshconditionsandnormalconditions.
Eubacteriamembranelipidsareesterlinked.
Eubacteriahavephotosyntheticmembers,asopposedto
Archaeawhichdon’t.
Transcriptionfactorsareneededforproteinsynthesisin
eubacteria,asopposedtoArchaea.

8. EUBACTERIA
Mycoplasmaspp.→smallesteubacteriaandthesmallestliving
cells(lackacellwall).
Thiomargaritanamibiensis→ largesteubacteria(Gram-
negativecoccoidwhichisfoundintheoceansedimentsofthe
continentalshelfofNamibia).Thecellsarelargeenoughtobe
visibletothenakedeye.
Epulopisciumfishelsoni→secondlargesteubacteria(Gram-
positivebacteriathathaveasymbioticrelationshipwith
surgeonfish).Itgrowsslightlylonger,butnarrowerthanthe
biggestbacteriumThiomargaritanamibiensis.

9. Colony of Mycoplasmaspp.
(the smallest bacterium)
Epulopisciumfishelsoni
(the second largest bacterium,
being compared with
Parameciumspp.)
Thiomargaritanamibiensis
(the largest bacterium)

10. TYPES OF BACTERIA ON THE BASIS
OF MODE OF NUTRITION
•Autotrophs (Photolithotrophic& ChemolithotrophicAutotrophs)
•Heterotrophs (Photoorganotrophic& Chemoorganotrophic Heterotrophs)

11. STUDY THESE POINTS BEFORE-HAND
Typesoforganismsbasedonenergysource
1.Phototrophs:gainenergyfromlight.
2.Chemotrophs:gainenergyfromchemicalcompounds.
Typesoforganismsbasedonelectronsource
1.Lithotrophs:usereducedinorganicsubstancesastheirelectronsource.
2.Organotrophs:extractelectronsfromorganiccompounds.
Typesoforganismsbasedoncarbonsource
1.Autotrophs:maketheirownfood,byfixingCO
2.
2.Heterotrophs:consumeothersforfood,i.eusecarboncontainingmolecules.

12. AUTOTROPHS
ThesebacteriauseCO
2asthesolesourceofcarbontopreparetheir
food.
Autotrophsareoftwotypes:
1.Photo-lithotrophicAutotrophs:TheyarealsocalledPhoto-litho-
autotrophsandPhoto-autotrophs.Theyperformphotosynthesis.They
gettheirenergyfromlight,electronsfromreducedinorganichydrogen-
containingmoleculesandcarbonfromCO
2,i.e.Cyanobacteria.
2.Chemo-lithotrophicAutotrophs:TheyarealsocalledChemo-litho-
autotrophsandChemo-autotrophs.Theyuseinorganicmoleculesas
theirenergysource,reducedinorganichydrogen-containingmolecules
aselectronsourceandCO
2asacarbonsource,i.e.Thiobacillusspp.

13. HETEROTROPHS
Thesebacteriauseorganiccompoundsascarbonsource.
TheylacktheabilitytofixCO
2.
Mostofthehumanpathogenicbacteriaareheterotrophicinnature.
Basedonthesourceofenergy,theyaresubdividedintotwotypes:
1.Photo-organotrophicHeterotrophs:TheyarealsocalledPhoto-
organo-heterotrophsandPhoto-heterotrophs.Theygettheirenergy
fromlight,electronsfromreducedorganichydrogen-containing
moleculesandcarbonfromorganiccarbonsources,i.e.Purpleand
greennon-sulfurbacteria.

14. HETEROTROPHS
2.Chemo-organotrophicHeterotrophs:TheyarealsocalledChemo-
organo-heterotrophsandChemo-heterotrophs.Theygettheirenergy
fromorganicmolecules,electronsfromreducedorganichydrogen-
containingmoleculesandcarbonfromorganiccarbonsources,i.e.
mostnon-photosyntheticbacteria(includingmostpathogens).
Basedonnutritionalrequirements,heterotrophsaresubdividedinto
twotypes:
1.SimpleHeterotrophs:Theyhavesimplenutritionalrequirements.
2.FastidiousHeterotrophs:Theyrequirespecialnutrientsfortheir
growth,i.e.Neisseriaspp.needshemolyzedbloodtogrow.

15. TYPES OF BACTERIA ON THE BASIS
OF OPTIMUM TEMPERATURE
•Psychrophiles
•Mesophiles
•Thermophiles

16. PSYCHROPHILES
TheseBacteriacangrowat0°Corbelow.
Optimumtemperatureofgrowthis15°Corbelow.
Maximumtolerabletemperatureis20°C.
Theyhavepolyunsaturatedfattyacidsintheircellmembranewhichgives
fluidnaturetothecellmembraneevenatlowtemperature.
Examples:Vibriopsychroerythrus,Vibriomarinus,Polaromonas
vaculata,etc.
Psychrotrophs:Theyarefacultativepsychrophiles,theycangrowin
coldtemperatures(0°C),buttheoptimumtemperaturefortheirgrowth
is20-30°C,theyspoilrefrigeratedgoods,i.e.Pseudomonasspp.,Bacillus
spp.,Clostridiumspp.,etc.

17. MESOPHILES
Thesebacteriacangrowbestbetween25-40°C.
Optimumtemperatureforgrowthis37°C.
Mostofthehumanpathogensaremesophilicinnature.
Examples:Escherichiacoli,Salmonellaspp.,Klebsiella
spp.,Staphylococcispp.,etc.

18. THERMOPHILES
Thesebacteriathatcanbestgrowabove45°C.
Theycontainsaturatedfattyacidsintheircellmembranesotheircell
membranedoesnotbecometoofluidevenathighertemperature.
Therearethreetypesofthermophiles:
1.FacultativeThermophiles:Thesethermophilesarecapableofgrowingin
mesophilicrangeaswell,i.e.Streptococcusthermophilus.
2.Steno-thermophiles:Theseareobligate/truethermophilesandcan’tgrow
inmesophilicrange,i.e.Thermusaquaticus.
3.Hyper-thermophiles:Thesebacteriahaveoptimumtemperatureofgrowth
above80°C,mostlyarcheobacteriaarehyperthermophiles,i.e.
Thermodesulfobacteriumspp.,Pyrolobusfumari,Thermotogaspp.,etc.

19. TYPES OF BACTERIA ON THE BASIS
OF OPTIMUM PH
•Acidophiles
•Alkaliphiles
•Neutrophiles

20. ACIDOPHILES
ThesebacteriagrowbestinacidicpH(bellow5.0).
Thecytoplasmofthesebacteriaisacidicinnature.
Examples:Thiobacillusthioxidans,Thiobacillus
ferroxidans,etc.
Thermoacidophiles:Theseacidopilesarealso
thermophilicinnature,i.e.Thermoplasmaspp.,
Sulfolobusspp.,etc.

21. ALKALIPHILES
These bacteria grow best at alkaline pH (above 8.0)
Example:Vibrio cholera(optimum pH = 8.2)

22. NEUTROPHILES
ThesebacteriagrowbestatneutralpH(6.5-7.5).
Thesearethemostcommonofthethreetypesofbacteria
(basedonpH).
Example:Escherichiacoli

23. TYPES OF BACTERIA ON THE BASIS
OF SALT REQUIREMENT
•Halophiles
•Halotolerant

24. HALOPHILES
ThesebacteriarequirehighconcentrationofNaClforgrowth.
Thecellmembraneofhalophilicbacteriaismadeupof
glycoproteinswithhighcontentofnegativelychargedglutamic
acidandasparticacids,hencehighconcentrationofNa
+
ion
concentrationisrequiredtoshieldthenegativecharge.
RedExtremeHalophiles:Thesearearchaeobacteriathatcan’t
growwithlessthan12-15%NaClintheirenvironment.Their
colonieshaveared-orangecolorduetothecarotenoidspresent
intheircells.
Examples:Halobacteriumspp.,Halococcusspp.,etc.

25. HALOTOLERANT
ThesebacteriadonotrequireNaClbutcantoleratelow
concentrationofit,i.e.intheenvironmentorgrowth
medium.
Example:Manycyanobacteriathatliveinhyper-saline
waters.

26. TYPES OF BACTERIA ON THE BASIS
OF OXYGEN REQUIREMENT
•ObligateAerobes
•Facultative Anaerobes
•AerotolerantAnaerobes
•Microaerophiles
•ObligateAnaerobes

27. OBLIGATE AEROBES
These bacteria require oxygen and cannot grow in its
absence.
They can only carry out oxidative type of metabolism.
Examples:Mycobacterium spp., Bacillus spp., etc.

28. FACULTATIVE ANAEROBES
ThesebacteriadonotrequireO
2butcanuseitifavailable.
GrowthofthesebacteriabecomesbetterinpresenceofO
2.
Theycancarryoutbothoxidativeandfermentativetypeof
metabolism.
Examples:Escherichiacoli,Klebsiellaspp.,Salmonellaspp.,
etc.

29. AEROTOLERANTANAEROBES
These bacteria do not require O
2for growth but can
tolerate its presence.
Growth of these bacteria is not affected by the presence
of O
2.
They can only carry out fermentative type of metabolism.
Example:Lactobacillus spp.

30. MICROAEROPHILES
ThesebacteriarequireO
2forgrowthbutonlyinlower
concentrations(lessthanthatoftheatmosphere).
Atatmosphericlevelofoxygen,theirgrowthisinhibited.
Theycanonlycarryoutoxidativetypeofmetabolism.
Capnophiles:Thesebacteriarequirecarbondioxideforgrowth
(theythriveinhighCO
2concentrations).Mostofthemicro-
aerophilesarecapnophilicinnature,i.e.Campylobacterspp.
Examples:Campylobacterspp.,Helicobacterpylori,Brucella
abortus,etc.

31. OBLIGATE ANAEROBES
These bacteria can only grow in the absence of oxygen.
Oxygen is harmful to them.
They can only carry out fermentative type of metabolism.
Examples:Clostridium spp., Methanococcusspp.,etc.

33. TYPES OF BACTERIA ON THE BASIS
OF SHAPE
•Cocci
•Bacilli
•Spiral Shaped Bacteria
•FilamentousBacteria
•Star Shaped Bacteria
•RectangleShaped Bacteria
•Pleomorphic Bacteria

34. COCCI
Thesebacteriaaresphericalorovalinshape.
Onthebasisofarrangement,cocciarefurtherclassifiedas:
1.Coccus:Asinglecoccus.
2.Diplococcus:Cocciinpair,i.e.Streptococcuspneumonia.
3.Streptococcus:Cocciinchain,i.e.Streptococcussalivarius.
4.Tetrad:Cocciingroupoffour,i.e.Tetragenococcusspp.
5.Sarcina:Cocciincubicalarrangementofcell,i.e.Sarcinaureae.
6.Staphylococcus:Cocciinbunch(irregular),i.e.Staphylococcus
aureus.

36. BACILLI
Thesearerodshapedbacteria,theyarefurtherclassifiedas:
1.Bacillus:Asinglerod-shapedbacillus,i.e.Bacilluscereus.
2.Diplobacilli:Apairofbacillijoinedendtoend,i.e.Klebsiella
rhinoscleromatis.
3.Streptobacilli:Itisachainofrodshapebacteria,i.e.Bacillussubtilis.
4.Palisades:Thebacillibendatthepointsofdivisionfollowingthecell
divisions,resultinginapalisadearrangementresemblingapicketfenceand
angularpatternsthatlooklikeChineseletters,i.e.Corynebacterium
diphtheriae.
5.Cocco-bacilli:Theirshapeisintermediatetococciandbacilli,i.e.
Haemophilusinfluenzae.

38. SPIRAL
SHAPED BACTERIA
Thesearecurvedandspiralshaped.
Theyareofthefollowingtypes:
1.Vibrio:Thesearecommashapedbacteriawithlessthanonecompleteturnor
twistinthecell,i.e.Vibriocholarae.
2.Spirilla:Theyhaverigidspiralstructure,theylackanoutersheathand
endoflagella,buthavetypicalbacterialflagella,i.e.Campylobacterjejuni.
3.Spirochetes:Theyhaveahelicalshapeandflexiblebody,theymoveby
meansofaxialfilaments,whichlooklikeflagella,i.e.Treponemapallidum.

39. FILAMENTOUS BACTERIA
Theyhavefilamentousor
branching structure
(myceliumlikestructure).
Theyresemblemoreclosely
tofungithanbacteria.
Examples: Streptomyces
spp.,Candidatusspp.,etc.
Filamentous structure
of a bacterium

40. STAR SHAPED BACTERIA
Thesebacteriahavea
star-likeshape.
Example:Stellaspp.
Star shaped bacterium

41. RECTANGLE SHAPED BACTERIA
Thesebacteriahavea
rectangularshape.
Example:Haloarculaspp.
Rectangle shaped bacterium

42. PLEOMORPHIC BACTERIA
Thesebacteriadonot
haveanycharacteristic
shape.
Theycanchangetheir
shape.
Theylackacellwall.
Example: Mycoplasma
pneumonia
Pleomorphic bacterium

43. TYPES OF BACTERIA ON THE BASIS
OF GRAM STAINING
•Gram Positive Bacteria
•Gram Negative Bacteria
•Gram Variable Bacteria
•GramIndeterminate Bacteria

44. GRAM POSITIVE BACTERIA
Thecellwallofthesebacteriaismainlycomposedofpeptidoglycan.
Ingramstaining,theyretaincrystalvioletdye(primarydye)andstain
darkvioletorpurple,theyremaincoloredwithgramstainwhen
washedwithalcoholsolution.
Theyhavevirtuallynolipidorlipoproteincontentintheircellwalls.
Teichoicacidsmaybepresent.
Periplasmicspaceisabsent.
Theymainlyproduceexotoxins.
Theyaremuchmoresusceptibletoantibiotics.
Examples:Staphylococcusspp.,Streptococcusspp.,etc.

45. GRAM NEGATIVE BACTERIA
Theircellwalliscomposedmainlyoflipopolysaccharides.
Ingramstaining,theycanbedecolorizedtoacceptcounterstain
(SafraninorFuchsine)andstainredorpink,theydon'tretainthe
gramstainwhenwashedwithalcoholsolution.
Theyhaveahighlipidandlipoproteincontent.
Teichoicacidsareabsent.
Periplasmicspaceispresent.
Theymainlyproduceendotoxins.
Theyarecomparativelymoreresistanttoantibiotics.
Examples:Escherichiacoli,Salmonellaspp.,etc.

47. GRAM VARIABLE BACTERIA
Thesebacteria,afterstainingwiththeGramstain,yieldaGram-
variablepattern:amixofpinkandpurplecellsareseen.
Itiscausedbyadecreaseinpeptidoglycanthicknessduringgrowth,
whichcoincideswithanincreaseinthenumberofcellsthatstain
Gram-negative.
Examples:Bacillusspp.,Butyrivibriospp.,andClostridiumspp.

48. GRAM INDETERMINATE BACTERIA
ThesebacteriadonotrespondpredictablytoGramstaining.
TheycannotbedeterminedaseitherGram-positiveorGram-negative,
butcanbedetectedviaacid-faststaining,hencetheyarerefferedto
as“acid-fastbacteria”.
Examples:ManyspeciesofthegenusMycobacterium,includingM.
tuberculosisandM.leprae.

49. TYPES OF BACTERIA ON THE BASIS
OF ARRANGEMENT OF FLAGELLA
•MonotrichousBacteria
•LophotrichousBacteria
•AmphitrichousBacteria
•PeritrichousBacteria
•AtrichousBacteria

50. MONOTRICHOUSBACTERIA
Thesebacteriahavea
singleflagellumatone
endofthecell.
Examples:Vibriocholera,
Pseudomonasaerogenosa,
etc.

51. LOPHOTRICHOUSBACTERIA
Thesebacteriahavea
bundleofflagellaatone
endofthecell.
Example:Pseudomanas
fluroscence

52. AMPHITRICHOUSBACTERIA
Thesebacteriaeither
haveasingleflagellumor
aclusterofflagellaat
bothendsofthecell.
Example:Aquaspirillium
spp.

53. PERITRICHOUSBACTERIA
Thesebacteriahave
flagellaalloverthecell
surface.
Examples: Escherichia
coli,Salmonellaspp.,
Klebsiellaspp.,etc.

54. ATRICHOUSBACTERIA
Thesebacteriadon’t
possessanyflagella.
Example:Shigellaspp.

55. TYPES OF BACTERIA ON THE BASIS
OF SPORE FORMATION
•Spore-forming Bacteria
•Non Spore-forming Bacteria

56. SPORE FORMING BACTERIA
Thesebacteriaproducesporesduringunfavorableconditions.
Thesearecomparativelytougher.
Theyaremostlygrampositive.
Theyaregenerallypathogenic.
Theyarefurthersubdividedintotwogroup:
1.EndosporeFormingBacteria:Theyproducesporeswithinthe
bacterialcell,i.e.Bacillusspp.,Clostridiumspp.,Sporosarcinaspp.,
etc.
2.ExosporeFormingBacteria:Theyproducesporesoutsidethecell
body,i.e.Methylosinusspp.

57. NON-SPORE FORMING BACTERIA
Thesebacteriadonotproducespores.
Theyarenotastoughasspore-formingbacteria.
Theyaremostlygramnegative.
Theyarenotgenerallypathogenic.
Examples:Escherichiacoli,Salmonellaspp.,etc.

58. TYPES OF BACTERIA ON THE BASIS
OF CAPSULE
•Capsular Bacteria
•Non Capsular Bacteria

59. CAPSULAR BACTERIA
Thesebacteriahaveapolysaccharide
layerthatliesoutsidethecell
envelope.
Sometimes,thesecretionthatmakes
upthecapsule,diffusesintothe
surroundingmediumandformsa
loosematrixknownasaslimelayer.
Capsuleandslimelayerare
sometimessummarizedunderthe
termglycocalyx.
Capsuleisavirulencefactor,i.e.it
enhancestheabilityofbacteriato
causedisease(e.g.prevents
phagocytosis).
A typical capsular bacterium

60. CAPSULAR BACTERIA
Capsulesalsocontainwaterwhichprotectsthebacteriaagainst
desiccation.
Theyalsoexcludebacterialvirusesandmosthydrophobictoxic
materialssuchasdetergents.
Capsulesalsohelpcellsadheretosurfaces.
Examples:Gram-negativecapsularbacteriainclude:Escherichiacoli
(insomestrains),Neisseriameningitides,Klebsiellapneumoniaand
Haemophilusinfluenzae.Gram-positivecapsularbacteriainclude:
Bacillusmegaterium,Streptococcuspyogenes,Streptococcus
pneumoniaandStaphylococcusaureus.

61. NON CAPSULAR BACTERIA
Thesebacterialackacapsule.
Theycanhideincomplexbiofilmswithotherorganismsthatproduce
capsuleorpolysaccharidematrix.
Alternatively,theymayproducesurfaceproteinsthatare
antiphagocyticforprotectingthemselves.
Examples:MostGram-negativeHaemophilusinfluenzaestrainsare
unencapsulated.