Gram stain yog siv dav hauv microbiology vim nws yog ib txoj hauv kev yooj yim tshaj plaws los faib cov kab mob sib txawv raws li qhov muaj pes tsawg leeg ntawm lawv cov phab ntsa ntawm tes. Raws li Gram, tag nrho cov kab mob tuaj yeem muab faib ua gram-positive (Gram (+)) thiab gram-negative (Gram (-)). Txoj kev Gram stain tau tsim nyob rau xyoo 1884 thiab tsis tau poob qhov chaw txij thaum ntawd los, txawm hais tias nws tau hloov kho ob peb zaug.
Cell wall structure
Gram staining qhia seb tus kab mob puas yog Gram-positive lossis Gram-negative. Kev faib cov kab mob rau hauv Gram (+) thiab Gram (-) yog ua raws li cov qauv ntawm lawv cov phab ntsa ntawm tes.
Cov phab ntsa ntawm tes muaj ntau tshaj plaws ntawm peptidoglycan (murein) - ib qho khoom siv nyuaj, uas suav nrog peptapeptide thiab glycan. Lub glycan muaj alternating residues ntawm N-acetylglucosamine thiab N-acetylmuramic acid txuas rau ib leeg los ntawm β-1,4-glycosidic bonds. Peptidoglycan muab kev saib xyuas ntawm tes, kev tiv thaiv osmotic, thiab kev ua haujlwm antigenic.
Qhov sib txawv ntawm Gram-positive thiab Gram-negative bacteria
Cov kab mob sib txawv muaj qhov sib txawv peptidoglycan txheej thicknesses. Hauv cov kab mob uas tau muab cais ua gram-zoo, nws nyob ntawm 15 txog 80 nm, thaum nyob rau hauv gram-tsis zoo nws yog los ntawm 2 mus rau 8 nm. Nyob rau tib lub sijhawm, cov kab mob Gram-tsis zoo muaj cov qauv tshwj xeeb hauv qab peptidoglycan txheej, uas cov kab mob Gram-zoo tsis muaj - qhov chaw periplasmic. Qhov chaw no tau ntim nrog hydrolytic enzymes - β-lactamase, ribonuclease 1, phosphatase. Nws yog cov enzymes no uas yog lub luag haujlwm rau kev tiv thaiv kab mob Gram-tsis zoo rau ntau cov tshuaj tua kab mob.
Cov Gram (-) peptidoglycan txheej ntawm cov kab mob yog khi rau lipopolysaccharide, ib qho qauv antigenic uas muaj endotoxin. Hauv Gram(+) kab mob, teichoic acids ua haujlwm zoo sib xws.
Cov kab mob Gram-negative muaj cov qauv ntxiv - cov txheej txheem sab nrauv.
Qhov tseem ceeb ntawm txoj kev staining
Ua ntej koj pib staining, smears ntawm cov kab mob kawm tau npaj. Ua li no, dej yog dripped mus rau lub iav swb thiab kab lis kev cai ntawm cov kab mob kis tau ntxiv nrog rau cov kab mob. Tom qab ntawd, tom qab cov dej tau qhuav tag, cov smear yog tsau - lub iav swb yog nqa ob peb zaug hla cov nplaim taws. Gram staining muaj txiaj ntsig zoo dua li cov kab mob muaj sia nyob - zas molecules khi zoo dua rau cov hlwb tuag.
Xim ua tiav hauv ntau theem:
- Cov ntawv me me ntawm cov ntawv lim tau muab tso rau ntawm cov smear ruaj khov thiab cov xim tseem ceeb yog nchuav - gentian violet lossis methylene xiav.
- Tom qab 3-5 feeb, tshem cov ntawv lim xim thiab sau cov smear nrog Lugol cov tshuaj rau 1 feeb. Nyob rau hauv rooj plaub no, qhov kev npaj darkens.
- Cov tshuaj Lugol yog drained thiab smear yog kho nrog ntshiab ethyl cawv: ob peb tee yog dripped mus rau qhov kev npaj, drained tom qab 20 vib nas this. Cov txheej txheem rov ua dua 2-3 zaug.
- Yau qhov ntsuas swb nrog dej distilled.
- Tsim cov staining ntxiv - ua tiav qhov kev npaj nrog fuchsin. Tom qab 1-2 feeb, cov xim yog ntxuav tawm.
- Tom qab dej qhuav, tshuaj xyuas cov smear hauv qab lub tshuab ntsuas. Cov kab mob Gram-positive yuav xiav-violet, Gram-negative kab mob yuav liab los yog liab.
Ua kom muaj xim sib txawv
Raws li tau piav qhia saum toj no, Gram-staining ntawm cov kab mob stains Gram-positive bacteria blue-violet, thaum Gram-negative bacteria stain red or pink. Yog vim li cas rau qhov sib txawv staining ntawm cov kab mob los ntawm txoj kev no yog tias tom qab daim ntawv soluble ntawm gentian violet nkag mus rau hauv lub xovtooj, cov dye nkag mus rau hauv daim ntawv insoluble iodine. Thaum kho cov kab mob nrog ethyl cawv, lipids raug rho tawm los ntawm daim nyias nyias nyob rau hauv qhov kev txiav txim ntawm cov kuab tshuaj uas tsis yog-polar. Tom qab ntawd lub membrane yuav ntxeem tau thiab tsis yog ib qho tseem ceeb barrier rau dye leaching. Txawm li cas lospeptidoglycan tiv taus ntau dua rau cov kuab tshuaj uas tsis yog-polar, suav nrog cawv. Nws yog tus uas tiv thaiv kev ntxuav tawm ntawm cov dye, yog li cov kab mob uas muaj txheej murein tuab tig xiav-violet (gram-zoo), thiab tom qab kho nrog cawv lawv tsis hloov xim.
Nyias murein txheej ntawm cov kab mob gram-negative tsis tuaj yeem tuav cov dye molecules hauv lub cell, yog li tom qab kev ua ntawm cawv lawv ua tsis muaj xim - stain gram-negative.
Tom qab raug smear rau fuchsin, cov kab mob Gram-stained tseem xiav-violet, thaum Gram-negative kab mob ua liab-liab.
Piv txwv ntawm Gram(+) thiab Gram(-) kab mob
kab mob Gram-negative muaj xws li cyanobacteria, sulfur kab mob, kab mob hlau, chlamydia, rickettsia, kab mob acetic, ntau cov kab mob methylobacteria, thionic kab mob, arsenitobacteria, carboxybacteria.
Bifidobacteria, ntau cov kab mob hauv dej, streptococci thiab staphylococci yog Gram-positive.
