REGULARLY ARRANGED PROTEIN ON THE SURFACES OF GRAM-NEGATIVE BACTERIA

• 1 Many species of Gram-negative bacteria carry a layer of regularly arranged sub-units on the outer surface of their outer membrane. The subunits are arranged tetra-gonally or hexagonally and have centre-to-centre spacings ranging from 4 to 35 nm, depending on the bacterial species.
• 2 The regularly arranged layer has been detected by electron microscopy in whole cells, cell walls, outer membranes and assemblies of isolated subunits. The regular arrays can be seen in intact cells by shadowing or freeze-etching and, occasionally, in thin sections or after negative-staining. Freeze-etching and negative-staining have been used to show the regular arrays in isolated cell walls and outer membranes. Negative-staining is used in the examination of assembled isolated subunits.
• 3 Optical diffraction of electron micrographs provides more detailed information of the fine structure of the subunits in the regular array.
• 4 The regularly arranged surface layer can be removed by protein perturbants, by chelation of divalent cations with EDTA and EGTA, by cation substitution or by acidification.
• 5 The two surface subunits which have so far been purified have been found to be acidic proteins with molecular weights of 67000 (Acimtobacter 199A) and 140000 (Spirillum serpens).
• 6 In Acinetobacter 199A the surface protein is attached to the protein of the outer membrane through a salt bridge involving Ca²⁺ or Mg²⁺. Evidence exists that there may be a similar mode of attachment in other species.
• 7 Isolated surface proteins from Acinetobacter 199A and from Spirillum spp. have the ability to reassemble into the same pattern as that seen on the bacterial surface, either in isolation or in the presence of cell-wall fragments to act as nucleating agents. Self-assembly of Acinetobacter 199A a-protein requires chloride ions.
• 8 Acinetobacter 199A a-protein can only be incorporated onto the bacterial surface if an intact lipopolysaccharide membrane is formed first to receive the intrinsic membrane proteins to which the a-protein attaches. Impairment of lipopolysaccharide synthesis by bacitracin prevents incorporation of a-protein and other membrane proteins into the outer membrane.
• 9 Continuing incorporation of pre-formed radioactive a-protein into the outer membrane in Acimtobacter 199A can be detected for 10 min after transference from radioactive to non-radioactive growth medium.
• 10 Spirillum metamorphum, Flexibacter sp. and Acinetobacter 199A synthesize more surface protein than is required to cover the cell surface. The excess is secreted into the growth medium.
• 11 The regularly arranged surface protein of Acinetobacter 199A provides partial protection against isolated lysosomal proteinases from polymorphonuclear leucocytes. Spirillum spp. is protected from Bdellovibrio invasion by the surface protein.
• 12 Secreted a-protein from Acimtobacter 199A has phospholipase A, activity. No phospholipase activity can be detected when the a-protein is bound to the bacterial surface.

     

COLD-TOLERANT FERMENTATIVE GRAM-NEGATIVE ORGANISMS FROM MEAT AND OTHER SOURCES

SUMMARY: From various chilled meats, twenty-eight strains of coli-aerogenes bacteria and one Aeromonas were isolated which grew well at +1±5° and some at −1±5°. The optimum growth temperature for most of these strains was nearer 37° than 30°. Nine strains (including the Aeromonas ) fermented lactose rapidly, the remainder slowly or not at all. All the strains which fermented lactose rapidly with the production of gas gave positive presumptive coli-aerogenes tests in MacConkey's broth at 30°, but only five were positive at 37°; none was positive at 44°. Because such organisms can attain populations of millions/cm², they could confuse the interpretation of presumptive coli-aerogenes tests made on chilled meat.     

产酶革兰阴性杆菌致医院感染与耐药特性

目的：了解超广谱β-内酰胺酶(ESBLs)与诱导型β-内酰胺酶革兰阴性杆菌致医院感染的检出率及耐药特点,对产酶与不产酶菌株进行耐药性对比分析,为临床用药提供依据。方法：双纸片试验检测ESBLs与诱导酶,Etest ESBLs试条确定产ESBLs菌株,对临床分离的960株细菌采用K—B法进行药物敏感试验。结果：哌拉西林、头孢培南、亚胺培南、环丙沙星对296株铜绿假单胞菌的抗菌活性较强;肺炎克雷伯菌和大肠埃希菌对亚胺培南100％敏感,对氨基糖苷类、氟喹诺酮类、磺胺类药物,产ESBLs与不产ESBLs菌株之间呈现交叉耐药。结论：常规药敏试验不能完全反映产诱导酶的铜绿假单胞菌耐药特点,Etest ESBLs试条可提高检测ESBLs的阳性率和准确性,产ESBLs革兰阴性杆菌的耐药性高于非产酶菌株,ESBLs菌引起的感染,应用亚胺培南、头霉素类进行治疗。     

发酵蓝靛果汁抑菌作用实验研究

目的：观察发酵蓝靛果汁对各种不同细菌的抑菌作用。方法：以药敏试验管碟法检测三种不同浓度发酵蓝靛果汁（蓝靛果原汁,75%蓝靛果汁,50%蓝靛果汁）对10种细菌的抑菌效果。结果：三种不同浓度的发酵蓝靛果汁对10种细菌均有明显的抑制作用。结论：发酵蓝靛果汁具有广谱抗菌作用。     

THE DIFFERENTIATION OF PSEUDOMONAS FROM OTHER GRAM-NEGATIVE BACTERIA ON THE BASIS OF ARGININE METABOLISM

SUMMARY: Of 391 Gram-negative bacteria isolated from chicken meat spoiled at a low temperature and classified by the commonly used methods, 156 were considered to be Pseudomonas and 188 Achromobacter , and 47 others belonged to the coli-aerogenes group or remained unclassified. A test for the production of alkaline conditions in an arginine medium incubated under a vaseline seal gave positive results for 155 of the Pseudomonas isolates, and negative results for 1 Pseudomonas and all the 188 Achromobacter strains. When named strains from culture collections were tested under these conditions, 63 Pseudomonas strains produced alkalinity while two plant pathogenic Pseudomonas species and two non-pigmented strains did not. These last two, which produced no acid from glucose, could not be regarded as typical Pseudomonas. All the Achromobacter strains gave negative results, as did four Alcaligenes , but one species, Alcaligenes bookeri , produced slightly alkaline conditions. One strain of Chromobacterium and three of Vibrio were also positive. These could be distinguished from Pseudomonas by their metabolism of glucose.     

香菇C91—3菌发酵液的抑菌作用的初不探讨

香菇C91－3菌是课题组经过多年筛选出的一株经生物发酵后,其发酵液具有明显的抗菌作用的真菌。研究结果表明该菌发酵液与青霉素、链霉素对比试验证明,该菌发酵液具有明显的抑制革兰阴性菌的作用,对大肠埃希菌、伤寒沙门菌、痢疾志贺菌有较好的抑制作用。     

中华鳖病原性维隆气单胞菌的分离及药敏试验

中华鳖(Trionyxsinensis)是我国主要淡水养殖名优品种之一。但随着中华鳖养殖规模的扩大和集约化程度的提高,导致鳖病暴发流行,阻碍了养鳖业的进一步发展。迄       

人类口腔菌的一个新属

牙周病是人类的一种常见病、多发病,其致病菌具有多样性和复杂性,有关该病的致病菌和病因学的研究,对防治工作具有重要意义。作者从牙周病患者的病灶处分离到了一株细菌（90-1）,并对其进行了鉴定,现将结果报告如下。