Bacterial Morphology and Structure

8/17/2019 Bacterial Morphology and Structure

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Bacterial Morphology and StructureBacterial Morphology and Structure

Xiao-Kui Guo PhD

http://basic.shsmu.edu.cn/passw/micro2/index.asp

http://basic.shsmu.edu.cn/passw/micro2/index.asphttp://basic.shsmu.edu.cn/passw/micro2/index.asphttp://basic.shsmu.edu.cn/passw/micro2/index.asphttp://basic.shsmu.edu.cn/passw/micro2/index.asphttp://basic.shsmu.edu.cn/passw/micro2/index.asphttp://basic.shsmu.edu.cn/passw/micro2/index.asphttp://basic.shsmu.edu.cn/passw/micro2/index.asphttp://basic.shsmu.edu.cn/passw/micro2/index.asphttp://basic.shsmu.edu.cn/passw/micro2/index.asphttp://basic.shsmu.edu.cn/passw/micro2/index.asp


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SIZE OF BACTERIASIZE OF BACTERIA

Unit for measurement :

Micron or micrometer!m:"!m#"$-%mm

&i'e:

(aries with )inds of bacteria and

a*so re*ated to their a+e and externa*en,ironment.

occi: sphere "!m

aci**i: rods $.-" !m in width -% !m in *en+th

&pira* bacteria: "0% !m in *en+th and $.%-$.1 !m in width


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Structure of BacteriaStructure of Bacteria

Particular structures

capsule

flagella 鞭毛

pili菌毛

spore 芽胞

Essential structuresEssential structurescell wallcell wall

细胞壁胞壁

cell membranecell membrane细胞

胞

CytoplasmCytoplasm细胞质

胞质

nuclear materialnuclear material 核质

质


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Gram +

Gram -

Cell wall

Cell (inner) membrane Outer membrane

Ribosomes

Granule

Cell wall

NucleoidCell membrane

Capsule

Flagellum

Pili

Gram, C. 1884. Ueber die isolirteGram, C. 1884. Ueber die isolirteFarbung der Schizomyceten inFarbung der Schizomyceten in

SchnittÄund Trocen!ra!araten.SchnittÄund Trocen!ra!araten.Fortschritte der MedicinFortschritte der Medicin, "ol. #, !ages, "ol. #, !ages

1884:1884: Christian GramChristian Gram' First !ublication (or the Gram stain method)' First !ublication (or the Gram stain method)

Editor's note: I would like to testify that I have found the Gram method to be one ofEditor's note: I would like to testify that I have found the Gram method to be one of

the best and for many cases the best method which I have ever used for stainingthe best and for many cases the best method which I have ever used for staining

Schizomycetes.Schizomycetes.


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Cell wallCell wall

&ituation:outmost portion.

"-%$nm in

thic)ness "$-

2 of dr3wei+ht.


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e wae wa : ommon pep og ycanommon pep og ycanlayer layer

A backbone of N-acetyl glucosamine and N-acetylmuramic acid : Both discovered

in Gram positive and Gram negative bacteria.

A set of identical tetrapeptide side chain attached to N-acetyl-muramic acid:

different components and binding modes in Gram positive and Gram negative

bacteria.

A set of identical peptide cross bridges: only in Gram positive bacteria


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Special components ofSpecial components of

Gram positive cell wall Gram positive cell wall Teichoic acid

&P4 / M P56789


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ecial components of Gramecial components of Gram

negative cell wall negative cell wall


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FunctionsFunctions of Cell Wall of Cell Wall Maintainin+ the ce**s characteristic shape- the ri+id

wa** compensates for the f*exibi*it3 of the phospho*ipid membrane and )eeps the ce** fromassumin+ a spherica* shape

ounterin+ the effects of osmotic pressure

Pro,idin+ attachment sites for bacteriopha+es

Pro,idin+ a ri+id p*atform for surface appenda+es-flagella fimbriae and pili a** emanate from thewa** and extend be3ond it

P*a3 an essentia* ro*e in ce** di,ision

e the sites of ma;or antigenic determinants of thece** surface。

Resistance of ntibiotics

ll l f f


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all!less forms ofall!less forms of

"acteria "acteria ..

*hen bacteria are treated +ith 1) enzymes that are lytic (or

the cell +all e.g. lysozyme or #) antibiotics that inter(ere +ithbiosynthesis o( !e!tidoglycan, +all%less bacteria are o(ten!roduced.

Usually these treatments generate non%iable organisms.

*all%less bacteria that can not re!licate are re(erred to ass!hero!lasts -+hen an outer membrane is !resent) or!roto!lasts -i( an outer membrane is not !resent).

ccasionally +all%less bacteria that can re!licate are

generated by these treatments -/ (orms).


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CellCell

membranemembrane

< !ite of bios"nthesis of #N$ cell wall pol"mers and membrane lipids% !electi&epermeabilit" and transport of solutes into cells

< 'lectron transport and oidati&e phosphor"lation< 'cretion of h"drol"tic eoen"mes


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MesosomesMesosomes

• Mesosomes are specialized structuresformed by convoluted inveigh-nationsof cytoplasmic membrane, and dividedinto septal and lateral mesosome.


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CytoplasmCytoplasm

omposed *ar+e*3 of water to+ether with proteins nuc*eic

acid *ipids and sma** amount of su+ars and sa*ts

Ribosomes: numerous "-2$nm in diameter with =$&>

distributed throu+hout the c3top*asm> sensiti,e to

streptom3cin and er3throm3cin site of protein s3nthesis

Plasmids: extrachromosoma*

+enetic e*ements

Inclusions: sources of stored

ener+3 e+ ,o*utin


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Pla!idPla!id P*asmids aresma**， circu*ar/*ine， extrachromosoma*， doub*e-stranded D94 mo*ecu*es。 6he3are capab*e of se*f-rep*ication and contain

+enes that confer some properties， such asantibiotic resistance， ,iru*ence factors。P*asmids are not essentia* for ce**u*ar

sur,i,a*. 8nc*usions of8nc*usions of

acteriaacteria

*nclusions areaggregates of &ariouscompounds that arenormall" in&ol&ed instoring energ"reser&es or building

blocs for the cell%*nclusions accumilatewhen a cell is grownin the presence ofecess nutrients andthe" are often

obser&ed underlaborator"

granulose


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NucleusNucleus

?ac)in+ nuc*ear

membrane absence

of nuc*eo*i hence

)nown as nuc*eicmateria* or nuc*eoid

one to se,era* per

bacterium.


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Ca#sules and slime layersCa#sules and slime layers

$hese are structures surrounding the outside of the cell envelo#e. $heyusually consist of #olysaccharide% however& in certain bacilli they arecom#osed of a #oly#e#tide #olyglutamic acid(. $hey are not essential tocell viability and some strains within a s#ecies will #roduce a ca#sule&

whilst others do not. Ca#sules are often lost during in vitro culture.

)ttachment

*rotection from #hagocyticengulfment.

+esistance to drying.

,e#ot for waste #roducts. +eservoir for certain

nutrients. #rotection


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FlagellaFlagella

Monotrichate/4mphitrichate/?ophotrichate/Peritrichate

Identification

of Bacteria Pathogenesis

Motility of

bacteria

Some bacterial s#ecies are mobile and #ossesslocomotory organelles ! flagella. -lagella consist of anumber of #roteins including flagellin

6he diameter of a f*a+e**um is thin 2$ nm and*on+ with some ha,in+ a *en+th "$ times the

diameter of ce**. Due to their sma** diameterf*a+e**a cannot be seen in the *i+ht microscopeun*ess a specia* stain is app*ied. acteria can ha,eone or more f*a+e**a arran+ed in c*umps or spreada** o,er the ce**.


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PiliPili

*ili are hair!like #roections of the cell & $hey areknown to be rece#tors for certain bacterial viruses.

Chemical nature is #ilin

Classification and -unction

a. ommon pi*i or fimbriae: fine ri+id numerous

re*ated to bacteria* adhesion

b. &ex pi*i: *on+er and coarser on*3 "-@ re*ated to

bacteria* con;u+ation


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'ndospores'ndospores

(spores)(spores)

< #ormant cell#ormant cell< Resistant to ad&erseResistant to ad&erse

conditionsconditions

- high temperatures- high temperatures

- organic sol&ents- organic sol&ents

< Produced when star&edProduced when star&ed< Contain calcium dipicolinateContain calcium dipicolinate

#P$#P$ ##ipicolinic acidipicolinic acid

< Bacillus Bacillus andand ClostridiumClostridium

8dentification of

acteria

Patho+enesis Aesistance


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,icroscope

?i+ht Microscope 7*ectron Microscope

Dar)fie*d Microscope

Phase ontrast Microscope

B*uorescence Microscope

ofoca* Microscope）

,ethods

!taining ,ethods

&imp*e stainin+>Differentia* stainin+ C Gram

stain 4cid-fast stain

&pecia* stainin+C 9e+ati,e stain

&pore stain B*a+e**a stain

Bacterial Morphology and Structure

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