基礎(chǔ)微生物學革蘭氏染色原理課件

G﹢菌：細胞壁厚，肽聚糖網(wǎng)狀分子形成一種透性障，當乙醇脫色時，肽聚糖脫水而孔障縮小，故保留結(jié)晶紫-碘復合物在細胞膜上。呈紫色。Gˉ菌：肽聚糖層薄，交聯(lián)松散，乙醇脫色不能使其結(jié)構(gòu)收縮，其脂含量高,乙醇將脂溶解，縫隙加大，結(jié)晶紫-碘復合物溶出細胞壁，沙黃復染后呈紅色。革蘭氏染色原理：結(jié)晶紫使菌體著上紫色碘和結(jié)晶紫形成脂溶性大分子復合物，分子大，能被細胞壁阻留在細胞內(nèi)。酒精脫色，細胞壁成分和構(gòu)造不同，出現(xiàn)不同的反應。沙黃復染，增加脫色菌與背景的反差并區(qū)別于未脫色菌。溶菌酶對細胞壁的作用◆可切斷NAM和NAG之間的—1，4糖苷鍵，引起細菌裂解。

◆對Gˉ菌，在EDTA存在下，受溶菌酶作用?！羧芫柑幚砗蟮木毎麘４嬖谌醺邼B（0.1~0.2M）蔗糖液中。青霉素對細菌細胞壁的作用Penicillium與轉(zhuǎn)肽酶結(jié)合，而使該酶失活，抑制了側(cè)鏈末端的丙氨酸與五肽橋的連接，破壞了細菌細胞壁的完整性（即抑制肽聚糖的合成），因此，Penicillium僅對正在生長著的細菌，且主要是對G+菌有效。Table8.RepresentativeperiplasmicproteinsinE.coli.

Bindingproteins

Foraminoacids(e.g.histadine,arginine)

Forsugars(e.g.glucose,maltose)

Forvitamins(e.g.thiamine,vitaminB12)

Forions(e.g.phosphate,sulfate)

Biosyntheticenzymes

Formureinassembly(e.g.transglycosylases,carboxypeptidases,transpeptidases)

Forfimbrialsubunitsecretionandassembly(e.g.chaperonins)

Degradativeenzymes

phosphatases

proteases

Detoxifyingenzymes

Beta-lactamases(e.g.penicillinase)

Aminoglycoside-phosphorylatingenzymes﹙7﹚細胞壁缺損型細菌①原生質(zhì)體protoplast②球形體spheroplast③L型細菌L-form★原生質(zhì)體的特點：1、無細胞壁，為圓球形2、對環(huán)境敏感：滲透壓，震蕩，離心，易溶菌3、有鞭毛，而不能運動4、不被噬菌體感染（因為失去吸附位點）﹙二﹚細胞膜(cytoplasticmembrane）1.概念：細胞膜是緊貼細胞壁內(nèi)側(cè)包圍細胞質(zhì)的一層柔軟，富有彈性的半透明薄膜。2.觀察分離方法：（1)質(zhì)壁分離(2)選擇性染色(3)電鏡技術(shù)(4)溶菌酶處理Figure10.Fluidmosaicmodelofabiologicalmembrane.Inaqueousenvironmentsmembranephospholipidsarrangethemselvesinsuchawaythattheyspontaneouslyformafluidbilayer.Membraneproteins,whichmaybestructuralorfunctional,maybepermanentlyortransientlyassociatedwithonesideortheotherofthemembrane,orevenbepermanentlybuiltintothebilayer,whileotherproteinsspanthebilayerandmayformtransportchannelsthroughthemembrane.

Table6.Functionsoftheprocaryoticplasmamembrane.

1.Osmoticorpermeabilitybarrier

2.Locationoftransportsystemsforspecificsolutes(nutrientsandions)

3.Energygeneratingfunctions,involvingrespiratoryandphotosyntheticelectrontransportsystems,establishmentofprotonmotiveforce,andtransmembranous,ATP-synthesizingATPase

4.Synthesisofmembranelipids(includinglipopolysaccharideinGram-negativecells)

5.Synthesisofmurein(cellwallpeptidoglycan)

6.Assemblyandsecretionofextracytoplasmicproteins

7.CoordinationofDNAreplicationandsegregationwithseptumformationandcelldivision

8.Chemotaxis(bothmotilityperseandsensingfunctions)

9.Locationofspecializedenzymes