T VN

Vi sinh vt (microorganisms) l nhng sinh vt nh b n mc ch c th thy c chng di knh hin vi quang hc hay knh hin vi in t. Vi sinh vt gy ra rt nhiu bnh him ngho cho ngi, cho gia sc, gia cm. Tuy nhin s vi sinh vt gy bnh ch chim mt phn rt nh trong th gii vi sinh vt. T xa xa ngi ta bit ng dng cc vi sinh vt c ch (tuy cha h bit ti s tn ti ca chng) ch bin thc phm ( nh nu ru, lm tng, mm, nc mm, gim, sa chua, chao, mui da, mui c, ...), phn, ngm v cy ly si, xp i t, trng lun canh vi cy h u...; hoc s dng cc bin php ngn chn tc hi ca vi sinh vt (nh p mui tht, c, lm mt, phi kh c ci, tm, c...). Sau vic Leeuwenhoek pht hin ra vi sinh vt v vic Louis Pasteur pht hin ra bn cht ca cc vi sinh vt- t khai sinh ra ngnh Vi sinh vt hc (Microbiology)- th nhn loi bt u quan tm rt nhiu n lnh vc khoa hc mi m ny. Vi sinh vt hc tr thnh nn tng cho s pht trin ca Cng ngh sinh hc(CNSH). Ngi ta chia s pht trin ca CNSH ra thnh 3 giai on: CNSH truyn thng l cc qu trnh dn d nhm ch bin , bo qun cc loi thc phm, x l t ai, phn bn phc v nng nghip... CNSH cn i l qu trnh s dng cc ni ln men cng nghip sn xut quy m ln cc sn phm sinh hc nh m chnh (bt ngt), lizin v cc axt amin khc, cc acid hu c, cc dung mi hu c, cht khng sinh, mt s vitamin (nh vitamin B2, B12, C...), nhiu loi enzym... CNSH hin i chia ra cc lnh vc nh CN di truyn (genetic engineering), cng ngh t bo (cell engineering), cng ngh enzym v protein (enzyme/protein engineering), CN vi sinh vt/ CN ln men (microbial engineering / fermentation), CN mi trng (environmental engineering). CNSH hin i thng gn lin vi cc c th mang gen ti t hp ( recombination gene).

Vi sinh vt hc l khoa hc nghin cu v cc c th hoc cc nhn t qu nh n mc khng thy c bng mt thng, tc l cc vi sinh vt. Vi sinh vt hc ang c ging dy trong rt nhiu trng i hc, Cao ng, Trung hc chuyn nghip v cng c cp n t nhiu bc ph thng. Vi sinh vt hc l nhng kin thc lin quan n cuc sng ca mi ngi. c bit l vi khun hin nay cng ang l vn quan tm. Bi tiu lun Cc phn ng sinh ha gim nh vi khun trong phng th nghim vi mc ch: Nhm a ra cc phng php gim nh vi khun mt cch chnh xc. chng ta c th nghin cu ng loi vi khun, v vic xc nh ny mang li rt

nhiu ngha trong thc tin. Vi mong mun nh vy em rt mong c s ng gp kin t Thy gio v ca tt c cc anh ch, cc bn quan tm n vn ny. Em xin chn thnh cm n nhng kin ng gp t Thy gio, v tt c cc anh ch, cc bn quan tm. Sinh vin: Phm Vn Hng

GII QUYT VN
GII THIU V VI KHUN
Cu trc t bo vi khun: Thnh t bo Thnh t bo (cell wall) gip duy tr hnh thi ca t bo, h tr s chuyn ng ca tin mao (flagellum) , gip t bo khng vi p sut thm thu, h tr qu trnh phn ct t bo , cn tr s xm nhp ca mt s cht c phn t ln, lin quan n tnh khng nguyn , tnh gy bnh, tnh mn cm vi Thc khun th (bacteriophage). Nm 1884 H.Christian Gram ngh ra phng php nhum phn bit phn chia vi khun thnh 2 nhm khc nhau : vi khun Gram dng (G+) v vi khun Gram m (G-). Phng php nhum Gram v sau c s dng rng ri khi nh loi vi sinh vt. Thnh phn ho hc ca 2 nhm ny khc nhau ch yu nh sau : Gram dng Gram m Thnh phn T l % i vi khi lng kh ca thnh t bo Peptidoglycan 30-95 5-20 Acid teicoic (Teichoic acid) Cao 0 Lipid Hu nh khng c 20 Protein Khng c hoc c t Cao Mng sinh cht (plasma membrane); Mng ngoi (outer membrane); Chu cht (Periplasmic space) Peptidoglycan l loi polyme xp, kh bn vng, cu to bi 3 thnh phn: N-Acetylglucosamin ( NAcetylglucosamine, NAG) Acid N-Acetylmuramic (N-Acetylmuramic acid, NAM) Tetrapeptid cha c D- v L- acid amin

Thnh t bo vi khun Gram dng

Thnh t bo vi khun Gram m Mng sinh cht Mng sinh cht hay Mng t bo cht (Cytoplasmic membrane, CM) vi khun cng tng t nh cc sinh vt khc. Chng cu to bi 2 lp phospholipid (PL), chim 3040% khi lng ca mng, v cc protein (nm trong, ngoi hay xen gia mng), chim 60-70% khi lng ca mng. u phosphat ca PL tch in, phn cc, a nc ; ui hydrocarbon khng tch in, khng phn cc, k nc. CM c cc chc nng ch yu sau y: Khng ch s qua li ca cc cht dinh dng, cc sn phm trao i cht Duy tr p sut thm thu bnh thng trong t bo. L ni sinh tng hp cc thnh phn ca thnh t bo v cc polyme ca bao nhy (capsule). L ni tin hnh qu trnh phosphoryl oxy ho v qu trnh phosphoryl quang hp ( vi khun quang t dng) L ni tng hp nhiu enzym, cc protein ca chui h hp. Cung cp nng lng cho s hot ng ca tin mao

Sinh vin in ch thch theo hng dn ca gio vin Cu trc ca u v ui ca phospholipid T bo cht T bo cht (TBC-Cytoplasm) l phn vt cht dng keo nm bn trong mng sinh cht, cha ti 80% l nc. Trong t bo cht c protein, acid nucleic, hydrat carbon, lipid, cc ion v c v nhiu nhiu cht khc c khi lng phn t thp. Bo quan ng lu trong TBC l ribosom (ribosome). Ribosom nm t do trong t bo cht v chim ti 70% trng lng kh ca TBC. Ribosom gm 2 tiu phn (50S v 30S), hai tiu phn ny kt hp vi nhau to thnh ribosom 70S. S l n v Svedberg- i lng o tc lng khi ly tm cao tc. Cu trc ca ribosom vi khun so vi ribosom 80S cc sinh vt nhn tht (nm, thc vt, ng vt) c trnh by trong bng sau y (Gio vin ging sinh vin ch thch vo hnh bng ting Vit) Ribosom vi khun

So snh Ribosom Vi khun v cc Sinh vt nhn tht (Eukaryotic ribosome) Trong t bo cht ca vi khun cn c th gp cc cht d tr nh cc ht glycogen, ht PHB (Poly--hydroxybutyrat), Cyanophycin, Phycocyanin, cc ht d nhim sc (metachromatic body), cc git lu hunh... loi vi khun dit cn trng Bacillus thuringiensis v Bacillus sphaericus cn gp tinh th c (parasoral body) hnh qu trm, c bn cht protein v cha nhng c t c th git hi trn 100 loi su hi (tinh th c ch gii phng c t trong mi trng kim do cc vi khun ny hon ton v hi vi ngi, gia sc, gia cm, thu hi sn- c hi i vi tm). Bacillus sphaericus c th dit cung qung ca cc loi mui. Bo t (spore) v Tinh th c (Crystal) Bacillus thuringiensis (tri) v Bacillus sphaericus (phi). Th nhn Th nhn ( Nuclear body) vi khun l dng nhn nguyn thu, cha c mng nhn nn khng c hnh dng c nh, v v vy cn c gi l vng nhn. Khi nhum mu t bo bng thuc nhum Feulgen c th thy th nhn hin mu tm. l 1 nhim sc th (NST, chromosome) duy nht dng vng cha 1 si ADN xon kp ( X khun Streptomyces c th gp nhim sc th dng thng). NST vi khun Escherichia coli di ti 1mm (!), c khi lng phn t l 3.109, cha 4,6.106 cp base nit. Th nhn l b phn cha ng thng tin di truyn ca vi khun.
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Th nhn trong t bo vi khun Escherichia coli. Ngoi NST, trong t bo nhiu vi khun cn gp nhng ADN ngoi NST. l nhng ADN xon kp c dng vng khp kn, c kh nng sao chp c lp, chng c tn l Plasmid. Bao nhy Bao nhy hay Gip mc (Capsule) gp mt s loi vi khun vi cc mc khc nhau: Bao nhy mng ( Vi gip mc, Microcapssule) Bao nhy (Gip mc, Capsule) Khi nhy ( Zooglea)

Mun quan st bao nhy thng ln tiu bn vi mc tu, bao nhy c mu trng hin ln trn nn ti.

Thnh phn ch yu ca bao nhy l polysaccarid, ngoi ra cng c polypeptid v protein. Trong thnh phn polysaccarid ngoi glucose cn c glucozamin, ramnose, acid 2-keto-3-deoxygalacturonic, acid uronic, acid pyruvic, acid axetic... ngha sinh hc ca bao nhy l: Bo v vi khun trong iu kin kh hn, bo v vi khun trnh b thc bo (trng hp Ph cu khun-Diplococcus pneumoniae) Cung cp cht dinh dng cho vi khun khi thiu thc n L ni tch lu mt s sn phm trao i cht (dextran, xantan...) Gip vi khun bm vo gi th ( trng hp cc vi khun gy su rng nh Streptococcus salivarrius, Streptococcus mutans...)

Vi khun Acetobacter xylinum c bao nhy cu to bi cellulose. Ngi ta dng vi khun ny nui cy trn nc da ch to ra Thch da (Nata de coco). da (Nata de coco) Vi khun Leuconostoc mesenteroides c bao nhy dy cha hp cht polyme l Dextran c tc dng thay huyt tng khi cp cu m thiu huyt tng. Sn phm ny rt quan trng khi c chin tranh. Vi khun ny thng gp cc nh my ng v gy tn tht ng trong cc b cha nc p ma. Nh enzym dextransuccrase m ng saccarose b chuyn thnh dextran v fructose. Vi khun Leuconostoc mesenteroides Mt s bao nhy ca vi khun cn c dng sn xut Xantan (Xanthane) dng lm cht ph gia trong cng nghip du m. Tin mao v khun mao Tin mao (Lng roi, flagella) khng phi c mt mi vi khun, chng quyt nh kh nng v phng thc di ng ca vi khun. Tin mao l nhng si lng di, di knh hin vi quang hc ch c th thy r khi nhum theo phng php ring. Di knh hin vi in t c th thy rt r cu trc ca tng si tin mao. xc nh xem vi khun c tin mao hay khng cn c cch th gin tip nhm bit kh nng di ng ca chng. Cy bng que cy nhn u vo mi trng thch ng cha 0.4% thch (agar-agar), cn gi l mi trng thch mm. Nu thy vt cy lan nhanh ra xung quanh th chng t l vi khun c tin mao, c kh nng di ng. Tin mao c th gc (basal body), gm 1 tr nh c gn vi 4 a trn (vi khun G - ) c dng vng nhn (ring), k hiu l cc vng L,P,S v M. Vng L nm ngoi cng,

tng ng vi lp liposaccarid ca mng ngoi ; vng P tng ng vi lp peptidoglycan, vng S tng ng vi lp khng gian chu cht ; vng M nm trong cng. Vi khun G+ ch c 2 vng : 1 vng nm ngoi tng ng vi thnh t bo v 1 vng trong tng ng vi mng sinh cht. Xuyn gia cc vng l 1 tr nh (rod) c ng knh 7nm. Bao bc tin mao phn pha ngoi l mt bao ngn m v c ng knh c hnh mc (hook). Si tin mao (filament) di khong 10-20 khong 13-20nm. ng knh ca bao hnh mc l 17nm. Khong cch gia vng S v vng M l 3mm, gia vng P v vng L l 9nm, gia vng P v vng S l 12nm. ng knh ca cc vng l 22nm, ng knh cc l cc vng l 10nm. Khong cch t mt ngoi ca vng L n mt trong ca vng M l 27nm. Si tin mao cu to bi loi protein c tn l flagellin, c trng lng phn t l 30 000-60 000. Mt s vi khun c bao lng (sheath) bao bc sut chiu di si, nh trng hp chi Bdellovibrio hay vi khun t Vibrio cholera. Tin mao v khun mao vi khun

Tin mao VK Gram dng Tin mao VK Gram m

Tin mao vi khun G + Tin mao vi khun G Cc tiu phn (subunit) ca flagellin c tng hp t cc ht ribosom nm gn mng sinh chy tng hp nn v i qua li m to dn thnh si tin mao Tin mao ca vi khun c cc loi khc nhau tu tng loi : Khng c tin mao (v mao, atrichia) C 1 tin mao mc cc ( n mao, monotricha) C 1 chm tin mao mc cc ( chm mao, lophotricha) C 2 chm tin mao mc 2 cc ( song chm mao, amphitricha) C nhiu tin mao mc khp quanh t bo (chu mao, peritricha)

C loi tin mao mc gia t bo nh trng hp vi khun Selenomonas ruminantium. Cc loi tin mao vi khun

Kiu sp xp tin mao lin quan n hnh thc di ng ca vi khun. Tin mao mc cc gip vi khun di ng theo kiu tin- li. Chng o ngc hng bng cch o ngc hng quay ca tin mao. Vi khun chu mao di ng theo hng no th cc tin mao chuyn ng theo hng ngc li. Khi tin mao khng t li v mt hng th vi khun chuyn ng theo kiu nho ln. Tc di chuyn ca vi khun c tin mao thng vo khong 20-80m/giy, ngha l trong 1 giy chuyn ng c mt khong cch ln hn gp 20-80 ln so vi chiu di ca c th chng. Cc chi vi khun thng c tin mao l Vibrio, Spirillum, Pseudomonas, Escherichia, Shigella, Salmonella, Proteus... cc chi Clostridium, Bacterium,Bacillus, ...c loi c tin mao c loi khng. cu khun ch c 1 chi (Planococcus) l c tin mao Xon th c mt dng tin mao c bit gi l tin mao chu cht (periplasmic flagella), hay cn gi l si trc ( axial fibrils), xut pht t cc t bo v qun quang c th. Chng gip xon th chuyn ng c nh s un vn t bo theo kiu vn nt chai. Xon th (Spirochete) quan st di knh hin vi nn en.

AF: Si trc PC: ng nguyn sinh cht OS: V ngoi IP: L ni C ch chuyn ng un vn t bo Xon th ( OS, AF, PC- xem ch thch hnh trn). Khun mao v Khun mao gii Khun mao (hay Tim mao, Nhung mao , Fimbriae) l nhng si lng rt mnh, rt ngn mc quanh b mt t bo nhiu vi khun Gram m. Chng c ng knh khong 7-9nm, rng rut (ng knh trong l 2-2,5nm), s lng khong 250-300 si/ vi khun. Kt cu ca khun mao gin n hn nhiu so vi tin mao. Chng c tc dng gip vi khun bm vo gi th ( nhiu vi khun gy bnh dng khun mao bm cht vo mng nhy ca ng h hp, ng tiu ho, ng tit niu ca ngi v ng vt). Khun mao vi khun E.coli C mt loi khun mao t bit gi l Khun mao gii (Sex pili, Sex pilus-s nhiu) c th gp mt s vi khun vi s lng ch c 1-10/ vi khun. N c cu to ging khun mao , ng knh khong 9-10nm nhng c th rt di. Chng c th ni lin gia hai vi khun v lm cu ni chuyn vt cht di truyn (ADN) t th cho (donor) sang th nhn (recipient). Qu trnh ny c gi l qu trnh giao phi (mating) hay tip hp (conjugation). Mt s thc khun th (bacteriophage) bm vo cc th th (receptors) khun mao gii v bt u chu trnh pht trin ca chng

Chnh nh cu trc ca vi khun nh vy m quyt nh n nhng phn ng sinh ha c th xt nghim v gim nh c vi khun. Ly t http://tusach.thuvienkhoahoc.com/wiki/Ph%C6%B0%C6%A1ng_ph %C3%A1p_gi%C3%A1m_%C4%91%E1%BB%8Bnh_vi_khu%E1%BA %A9n_trong_PTN