Deoxyribonucleic Acid Base Composition of Flavobacteria and Related Gram Negative Yellow Pigmented Rods

DNA base composition analyses on 35 Gram negative yellow pigmented rods indicated two distinct groups. The larger contained 29 strains with G + C contents of between 30·8 and 39·5% and comprise 19 non-gliding, aflagellate strains and 10 gliding strains. The smaller, a heterogenous collection of six strains, had G + C contents in the 51·4–63% range.     

The Metabolism of Amino Compounds by Some Gram Negative Yellow Pigmented Rods

S ummary . The ability of 6 Gram negative, yellow pigmented rods to metabolize various amino compounds was investigated. The strains examined represented 3 groups of organisms of this type. The strains of 2 groups, O and S, had low G+C ratios while those of group Y had high G+C ratios. Strains of groups O and S dissimilated arginine by the dihydrolase pathway but the group Y organisms did not attack arginine. No decarb-oxylase activity was recorded, but the ability to transaminate amino acids in the presence of added keto acids was demonstrated for all the strains examined. The pattern of amino acid degradation produced by strains of the low G+C groups was similar though distinct from that of the high G+C types. In the absence of added keto acids deamination was the main mode of attack on amino compounds.     

An Initial Approach to the Taxonomy of Some Gram Negative Yellow Pigmented Rods

SUMMARY: The responses of various groups of Gram negative, yellow pigmented rods constructed on the basis of classical criteria to a wide range of cultural and biochemical features were examined. The occurrence of a wide area of slime surrounding true growth with isolates which may spread but did not glide is described. The correlation between the classical groups and divisions suggested on the basis of pigment absorption curves was examined.     

The Adansonian Taxonomy and the Deoxyribonucleic Acid Base Composition of some Gram Negative, Yellow Pigmented Rods

S ummary : The numerical taxonomy technique of Sneath (1957) was used to differentiate types of Gram negative, yellow pigmented rods isolated from food products. DNA base ratios were determined for representative isolates from each of the major groups formed. A determinative scheme using features extracted from the data has been suggested. The problems of nomenclature of organisms of this type are discussed.     

Identity of Gram Negative, Yellow Pigmented, Fermentative Bacteria isolated from Plants and Animals

S ummary . Morphological, cultural and biochemical properties of 35 isolates of rod shaped Gram negative, yellow pigmented anaerogenic, fermentative bacteria were compared. The isolates comprised named cultures of Bacterium herbicola, Erwinia lathyri, E. ananas, E. milletiae, E. uredovora and B. typhi flavum , as well as organisms isolated from deer and man which were considered to be related to E. milletiae. The results showed that the organisms were indistinguishable from one another on the basis of the tests employed, and it is concluded that B. herbicola, B. typhi flavum, E. lathyri and E. ananas should be classified as Erwinia herbicola (Düggeli) Dye. Since there was insufficient information regarding the plant pathogenicity of E. milletiae and E. uredovora , it is suggested that they should remain separate species at present. The relationship of this group of organisms to certain coliforms and to flavobacteria is briefly discussed.     

(Symposium on Myxobacteria and Flavobacteria: Paper X). Properties of Some Pectolytic, Yellow pigmented, Gram Negative Bacteria Isolated from Fresh Cauliflowers

Pectolytic, yellow-pigmented, Gram negative bacteria formed 3·3% of the organisms isolated at 23° from fresh cauliflowers, and may contribute to deterioration of this vegetable in storage. The bacteria attacked glucose oxidatively in the Hugh & Leifson (1953) test, were nonmotile and oxidase-positive, conforming to definitions of the genus Flavobacterium. These strains showed differences in morphological and physiological properties from F. pectinovorum NCIB 9059, which has properties resembling those of Cytophaga spp.     

Bioengineered Nisin A Derivatives with Enhanced Activity against Both Gram Positive and Gram Negative Pathogens

Nisin is a bacteriocin widely utilized in more than 50 countries as a safe and natural antibacterial food preservative. It is the most extensively studied bacteriocin, having undergone decades of bioengineering with a view to improving function and physicochemical properties. The discovery of novel nisin variants with enhanced activity against clinical and foodborne pathogens has recently been described. We screened a randomized bank of nisin A producers and identified a variant with a serine to glycine change at position 29 (S29G), with enhanced efficacy against S. aureus SA113. Using a site-saturation mutagenesis approach we generated three more derivatives (S29A, S29D and S29E) with enhanced activity against a range of Gram positive drug resistant clinical, veterinary and food pathogens. In addition, a number of the nisin S29 derivatives displayed superior antimicrobial activity to nisin A when assessed against a range of Gram negative food-associated pathogens, including E. coli, Salmonella enterica serovar Typhimurium and Cronobacter sakazakii. This is the first report of derivatives of nisin, or indeed any lantibiotic, with enhanced antimicrobial activity against both Gram positive and Gram negative bacteria.     

贺兰山岩黄耆及其近缘种的分类学研究

依据植物野外和腊叶标本形态观察以及小叶脉序观察,对贺兰山岩黄耆(豆科)及其近缘种进行了分类学研究。结果表明:贺兰山岩黄耆及其近缘种之间较为稳定的差别体现在花器官的形态方面。贺兰山岩黄耆与短翼岩黄耆的主要区别特征是小苞片长为萼筒的1～2倍,旗瓣与龙骨瓣近等长,而后者的小苞片长为萼筒的0.5～0.8倍,旗瓣长为龙骨瓣的0.8倍。贺兰山岩黄耆与华北岩黄耆和费尔干岩黄耆的主要区别是翼瓣长为龙骨瓣的0.3～0.5倍,而后二者的翼瓣长均为龙骨瓣的0.7～0.8倍。在小叶脉序特征方面,贺兰山岩黄耆与短翼岩黄耆和华北岩黄耆近似,均为小叶一级脉纤细,二级脉不分支,二级脉环外有较多网结三级脉,具少量复合二级间脉或不明显,而费尔干岩黄耆小叶一级脉粗,二级脉多分支,二级脉环外有少量网结三级脉,具明显的简单二级间脉。此外,小叶脉序特征可能在岩黄耆属组间关系的探讨中发挥作用。     

Computer-aided Numerical Identification of Gram negative Fermentative Rods on a Desk-top Computer

One hundred and sixty-three strains of Gram negative fermentative rods isolated from humans and 60 isolated from diseased snails were identified by a conventional method and by numerical identification on a desk-top computer. The two methods gave the same identities with 133 'human strains' and 33 'snail strains'. The possible sources of the differences in identifications are discussed. The study showed that numerical identification done on a desk-top computer can be a useful method for routine medical microbiological laboratories.     

Standard Test Set and a Computer-generated Diagnostic Register for Gram negative Fermentative Rods

A simple two-step method for the identification of Gram negative fermentative rods is based on interpretation of test results by means of a computer-generated diagnostic register. The first step is based on 10 tests, the second on six. Of 1451 strains routinely isolated in clinical laboratories 84% were identified in the first step. If the second step was included, the efficacy of the system rose to 99.17%. Disagreements with the conventional method in the first step are discussed.     

Differentiation of Gram Positive and Gram Negative Bacteria in Transparent Acrylic Resin Emulsion Replicas of Surfaces of Plants

When acrylic resin emulsion (Rohm & Haas Primal AC-33) is allowed to dry on a leaf surface, it can be peeled off to give a transparent replica of the surface with bacteria and fungi embedded in it. The distribution of micro-organisms in the replica appears to reflect the patterns in which they occur naturally on the surface. The resin replicas may be stained by a variety of microscopical stains, the best of which is phenol-acetic-aniline blue, and are suitable for high power light microscopy.
Acrylic resin emulsion differs from widely used cellulose-based materials in that permanent differentiated preparations of Gram positive and Gram negative stained bacteria may be produced from a wide variety of types of surface.     

The Hydrolysis of Dextran by Gram Negative Non-sporing Anaerobic Bacilli

The ability of Gram negative anaerobic bacilli to hydrolyse dextran was determined in liquid and solid media containing Blue Dextran 2000. Released blue chromophore in the liquid medium was detected spectrophotometrically. Results obtained with 334 strains of Bacteroidaceae grown on the solid medium indicated that most strains did not hydrolyse the substrate. Hydrolysis of Blue Dextran 2000 occurred with certain strains of Bacteroides thetaiotaomicron , B. melaninogenicus ss. melaninogenicus, B. oralis, B. ovatus and B. ochraceus.     

A Taxonomic Study of the Micrococcaceae

Recent proposals for new species in the genera Staphylococcus and Micrococcus prompted the present numerical taxonomic survey. The API 50E and API 20E identification strips have been used together with a few conventional tests to examine the Micrococcaceae. Many of the proposed species formed good distinct clusters and one group could be the basis for a new genus.     

A Composite Arginine Glucose Medium for the Characterization of Pseudomonas aeruginosa and other Gram Negative Bacilli

SUMMARY: A composite agar medium is described for the characterization of Pseudomonas aeruginosa and other Gram negative bacilli. Glucose oxidation and the production of ammonia by the arginine dihydrolase system are demonstrable in one tube. This arginine glucose (AG) medium also indicates the evolution of gas by glucose fermenting Gram negative bacilli.     

Characterization of Nonfermentative Nonfastidious Gram Negative Bacteria encountered in Medical Bacteriology

More than 90 morphological and physiological characters of 546 strains of nonfermentative, nonfastidious, Gram negative bacteria isolated from clinical specimens were examined to determine those features most useful for the identification of these bacteria. The species examined included Moraxella osloensis, Mor. lacunata, Acinetobacter anitratum, Ac. haemolyticus subsp. haemolyticus, Ac. haemolyticus subsp. alcaligenes, Ac. Iwoffi, Alcaligenes faecalis, Alc. odorans var. viridans, Pseudomonas fluorescens, Ps. putida, Ps. pseudomallei, Ps. maltophilia, Ps. stutzeri, Ps. acidovorans, Ps. alcaligenes , and atypical strains of Ps. aeruginosa.     

黄渤海甲壳类的分类多样性

为了解黄渤海甲壳类的分类多样性特征, 我们统计了2010-2015年中国水产科学研究院黄海水产研究所调查捕获的黄渤海甲壳类(软甲纲: 十足目与口足目)物种名录。结合历史文献, 进一步系统整理得到黄渤海甲壳类物种总名录。基于这2个名录, 应用分类阶元包含指数(the inclusion index at taxonomic level, TINCL_i)、平均分类差异指数(average taxonomic distinctness index, Δ⁺)和分类差异变异指数(variation in taxonomic distinctness index, Λ⁺)研究了其分类多样性特征。结果显示: 2010-2015年调查名录中, 甲壳类共93种, 隶属于2目39科66属, 其中10种为新分布种; 对虾科、藻虾科、长臂虾科、梭子蟹科和弓蟹科的物种数最多, 合计占总物种数的38.71%; TINCL_i分别为1.41种/属和2.38种/科; Δ⁺和Λ⁺分别为50.25和35.20。总名录中, 甲壳类共228种, 隶属于2目53科123属, 其中藻虾科、豆蟹科、对虾科、弓蟹科和鼓虾科的物种数最多, 合计占总物种数的30.70%; TINCL_i分别为1.85种/属和4.30种/科, Δ⁺和Λ⁺分别为50.18和30.87。对虾科的相对丰富度指数(the relative richness index, R_r)最高(100), 其次是梭子蟹科(71.43)和长臂虾科(62.50), 豆蟹科最低(6.25)。黄渤海甲壳类的平均分类差异指数(Δ⁺)明显小于鱼类(P < 0.05)。2010-2015年调查的Δ⁺计算值高于理论值, 且在理论值的95%置信区间内, 说明黄渤海甲壳类群落正处在中等程度的干扰中。     

Gram Negative Wound Infection in Hospitalised Adult Burn Patients-Systematic Review and Metanalysis-

Background

Gram negative infection is a major determinant of morbidity and survival. Traditional teaching suggests that burn wound infections in different centres are caused by differing sets of causative organisms. This study established whether Gram-negative burn wound isolates associated to clinical wound infection differ between burn centres.

Methods

Studies investigating adult hospitalised patients (2000–2010) were critically appraised and qualified to a levels of evidence hierarchy. The contribution of bacterial pathogen type, and burn centre to the variance in standardised incidence of Gram-negative burn wound infection was analysed using two-way analysis of variance.

Primary Findings

Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumanni, Enterobacter spp., Proteus spp. and Escherichia coli emerged as the commonest Gram-negative burn wound pathogens. Individual pathogens’ incidence did not differ significantly between burn centres (F (4, 20) = 1.1, p = 0.3797; r2 = 9.84).

Interpretation

Gram-negative infections predominate in burn surgery. This study is the first to establish that burn wound infections do not differ significantly between burn centres. It is the first study to report the pathogens responsible for the majority of Gram-negative infections in these patients. Whilst burn wound infection is not exclusive to these bacteria, it is hoped that reporting the presence of this group of common Gram-negative “target organisms” facilitate clinical practice and target research towards a defined clinical demand.     

A Taxonomic Study of Fritillaria from Xinjiang

In the present paper the genus Eritillaria in Xinjiang is revised. There are altogether eleven species and four varieties recognized in this region, of which four species and four varietie are new to science, and one species is new to Chinese flora