bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemotactic attraction of Azospirillum lipoferum by wheat roots and characterization of some attractants
Authors: Heinrich D. , Hess D.
Published: May 2010

Media from the in vitro association of wheat and Azospirillum lipoferum and from wheat plants alone proved to be chemotactically active. Medium from wheat plants showed a higher attraction than medium from the association. The main attractants were sucrose, glucose, and fructose. In mineral medium without any added sugars, and in association medium with sucrose supplied, and from wheat roots alone, a sucrose excretion and an active invertase were detected. By cleaving sucrose the chemotactic potential increased. Sucrose can not be metabolized by A. lipoferum, whereas glucose and fructose are. Utilization of glucose and fructose by the bacteria may explain why medium from the association wheat–Azospirillum was less chemotacticaly active than medium from wheat plants alone. Cleavage of sucrose has the additional effect of providing energy sources for bacterial growth and dinitrogen fixation.
Independent development of heat resistance and ascospores of Hansenula anomala
Authors: Su Wanfang , Beuchat L. R. , Worthington R. E.
Published: May 2010

The development of ascospores and heat resistance was determined in McClary's acetate broth in the presence of two sporulation inhibitors, ethanol and erythromycin. The inhibitors delayed sporulation without preventing development of heat resistance. The presence of ethanol in growth media caused cells to have increased heat resistance. The fatty acid and chitin contents of sporulating Hansenula anomala cells were determined. Highest triglyceride content of cells was associated with the initiation of sporulation. This phenomenon was not observed for phospholipid. As the ratio of saturated to unsaturated fatty acids in triglycerides increased, so did the heat resistance. However, the chitin content of cells was not correlated with heat resistance.
Description of an unusual Gram-negative anaerobic rod isolated from periodontal pockets
Authors: Amundrud D. G. , Hamilton I. R. , Bowden G. H.
Published: May 2010

A Gram-negative rod which grew with an unusual colonial "water-drop" form was isolated from periodontal pocket samples from 12 patients. Six strains were characterized by biochemical tests, cell wall analyses, malate dehydrogenase mobilities, protein profiles, and serology. By these criteria, the organisms formed a group of similar strains which were anaerobic, nonmotile, nonsporing, Gram-negative rods resembling Bacteroides. Comparison of the isolates to American Type Culture Collection strains of Bacteroides showed that they represented a closely related group, distinct from the described species of oral Bacteroides. Initial results on the DNA of the isolates suggested a base ratio of 54–57% G + C. Despite the DNA G + C base ratios currently accepted for the Bacteroides (28–61 mol% G + C), many species fall into a narrower range of 40–52 mol% G + C. This range would exclude the organisms described here and suggests that placing them into the genus Bacteroides may be inappropriate.
Effect of ammonium on chloramphenicol production by Streptomyces venezuelae in batch and continuous cultures
Authors: Shapiro S. , Vining L. C.
Published: May 2010

Cultures of Streptomyces venezuelae presented with a mixture of ammonium and an amino acid as nitrogen sources used both compounds together. Absence of ammonium repression of alternative nitrogen assimilation pathways was also observed when ammonium was added to cultures already growing on proline. The presence of ammonium in the medium ab initio depressed the yield of chloramphenicol. However, its addition to a culture growing on proline caused only a temporary inhibition of antibiotic synthesis, even when sufficient ammonium was added to create an excess. Continuous cultures supplied with ammonium as the growth-limiting nutrient showed no significant change in specific antibiotic production at different specific growth rates. The overall results indicate that in S. venezuelae neither nitrogen utilization pathways nor chloramphenicol biosynthesis is controlled by nitrogen repression.
Isolation and characterization of the peptidoglycans from selected Gram-positive and Gram-negative periodontal pathogens
Authors: Barnard M. R. , Holt S. C.
Published: May 2010

The peptidoglycans from several Gram-negative and Gram-positive periodontal pathogens were isolated, purified, and characterized both morphologically and chemically. In addition, the effects of the mureolytic enzymes, lysozyme, M-1 N-acetyl-muramidase, and the AM-3 endopeptidase, on the peptidoglycans were examined. These enzymes were found to be highly effective in the degradation of the purified peptidoglycans; however, a Bacteroides capillus peptidoglycan–protein complex exhibited a greater resistance to these enzymes. Morphologically, the peptidoglycans consisted of large saccular sheets which, when viewed by scanning electron microscopy, contained numerous holes and tears. Chemically, the peptidoglycans consisted of muramic acid, glucosamine, alanine, glutamic acid, and meso-diaminopimelic acid (DAP). One Bacteroides species, Bacteroides gingivalis strain W, contained glycine and LL-DAP, suggestive of an indirectly cross-linked A3γ peptidoglycan.
Lipid utilization of two flower spiroplasmas and honeybee spiroplasma
Authors: Chang C. J.
Published: May 2010

A chemically defined medium (CC-494) was used to study the lipid utilization of two flower spiroplasmas (Spiroplasma florkola and SR-3) and honeybee spiroplasma (AS-576). All three spiroplasmas reached comparable growth yields when lauric acid, myristic acid, or stearic acid replaced palmitic acid; palmitoleic acid, linoleic acid, or linolenic acid replaced oleic acid; and campesterol, ergosterol, β-sitosterol, or stigmasterol replaced cholesterol. None of the spiroplasmas grew when 5A-cholestane replaced cholesterol.
The role of encapsulation in the pathogenesis of anaerobic Gram-positive cocci
Authors: Brook Itzhak , Walker Richard I.
Published: May 2010

The pathogenicity of 22 anaerobic and facultative Gram-positive cocci (AFGPC) was investigated by inoculating them into mice and determining their ability to cause subcutaneous abscesses. Only 11 heavily encapsulated isolates (> 50% of the cells were encapsulated) induced abscesses. However, when the other 11 isolates were injected with Bacteroides sp. or facultative and aerobic bacteria, abscesses were formed in 8 of the 11 combinations. The AFGPC recovered from the mixed infections contained many encapsulated cells. Encapsulation also occurred in cocci injected with capsular material or with Formalin-killed cells of Klebsiella pneumoniae or capsule-positive Bacteroides sp. After acquisition of capsules, these strains could induce abscesses on reinoculation in mice.
Nitrosospira, an important ammonium-oxidizing bacterium in fertilized coniferous forest soil
Authors: Martikainen Pertti J. , Nurmiaho-Lassila Eeva-Liisa
Published: May 2010

Among ammonium-oxidizing autotrophic nitrifiers only Nitrosospira was found in two pine forest soils fertilized with urea or wood ash in southern Finland. A strain isolated from an ash-treated soil was partially characterized. The cells were spirals, mostly of one to three turns; they were either flagellated or not and pili were found. The strain grew best at 20–27 °C at Po2 of 0.21 (shortest doubling time, 29 h). Km(O2) at 27 °C was 0.20 mg/L. Activity per cell during exponential growth ranged from 0.0060 to 0.0085 pmol [Formula: see text] and growth yield from 2.53 × 106 to 3.60 × 106 cells/μmol [Formula: see text]. Pure cultures could not be isolated from urea-fertilized soils. Hyphomicrobium- and seliberia-like bacteria were frequent contaminants of enrichment cultures in these soils. Reasons for the persistence of Nitrosospira in forest soil were discussed.
Étude de l'influence du rapport Mg/Ca sur la formation de carbonate par des bactéries telluriques
Authors: Rivadeneyra M. A. , Ramos-Cormenzana A. , Garcia-Cervigon A.
Published: May 2010

An experiment was conducted to study the influence of the Mg/Ca ratio on CaCO3 crystal formation by 96 isolates selected from 204 bacterial strains isolated from soil. Liquid and solid culture media were used with varying ratios of the ions, Mg and Ca; other media were used with similar Mg/Ca ratios, but in which the absolute quantities of the ions were varied. The crystals obtained were purified and identified by X-ray diffraction; in addition thermal differential analysis (ATD) and thermal gravimetric analysis (ATG) were utilized as complementary techniques. Calcite, aragonite, and struvite were identified, plus two different crystalline types, designated X and Y, which were not fully identified. The composition of the culture medium was found to have an influence on the speed and the type of crystals being precipitated. In solid culture media, it was more difficult to obtain aragonite precipitation.
Volatiles of Pseudomonas aeruginosa and related species by automated headspace concentration – gas chromatography
Authors: Zechman James M. , Labows Jr. John N.
Published: May 2010

The volatile metabolites of three strains of Pseudomonas aeruginosa and one strain each of Pseudomonas cepacia, Pseudomonas maltophilia, Pseudomonas fluorescens, and Pseudomonas putida were analyzed using an automated headspace concentrator incorporating a gas chromatograph. The procedure does not require sample preparation and automates the entire analytical sequence to yield reproducible profiles of volatile constituents. Gas chromatographic profiles of the volatile metabolites of each species were obtained using a 20-min concentration period and two fused silica capillary columns of different polarities. The production of headspace metabolites from trypticase soy broth was studied in relationship to culture incubation time and initial cell concentration. The volatiles identified after 24 h incubation consisted of 1-butanol, isopentanol, toluene, 1-undecene, 2-butanone, 2-heptanone, 2-nonanone, and 2-undecanone. Sufficient amounts of specific metabolites were produced after 5 h incubation to provide information of possible diagnostic value. In particular, all P. aeruginosa strains produced a distinctive series of 1-undecene and methyl ketones after 5 h incubation of media inoculated to provide 2 × 106 cells/mL. The results indicate that when growth and analytical conditions are held constant, P. aeruginosa and related species produce characteristic profiles of headspace metabolites. Since conventional bacteriological tests require 24 h or more for the identification of these pseudomonads, automated volatile analysis could provide an alternative means for the rapid detection of these bacteria.
Histochemical changes during conidiogenic germination of sclerotia of Botrytis cinerea
Authors: Backhouse D. , Willetts H. J.
Published: May 2010

Conidiogenic germination of sclerotia of Botrytis cinerea was examined histochemically. During germination reserves of protein, glycogen, and polyphosphate disappeared from medullary hyphae, and the hyphal walls and intercellular matrix of β-glucans disintegrated. Cell breakdown commenced in the centre of sclerotia and continued outwards. Microconidia were produced when almost all of the contents of the sclerotia had been removed.
Cytotoxic effects of culture supernatants of oral bacteria and various organic acids on Vero cells
Authors: Grenier Daniel , Mayrand Denis
Published: May 2010

Dilute culture filtrates of the three asaccharolytic black-pigmented Bacteroides species as well as B. macacae, Fusobacterium nucleatum, and animal strains resembling B. gingivalis were cytotoxic for the African green monkey kidney cell line (Vero cells). Butyric or propionic acid, major metabolic products of these bacteria, seem to be responsible for the characteristic morphological changes observed. Among the organic acids studied, only butyric, propionic, and valeric acids exhibited cytotoxic effects. Finally, cumulative effects (as opposed to synergistic) were observed when mixtures of two organic acids were tested.
Phospholipid enrichment of Saccharomyces cerevisiae and its effect on polyene sensitivity
Authors: Rao T. Venu Gopala , Trivedi Akhilesh , Prasad Rajendra
Published: May 2010

Sensitivity to polyene antibiotics, e.g., nystatin, amphotericin B, and filipin, was determined in phosphatidylcholine (PC) or phosphatidylethanolamine (PE) or phosphatidylserine (PS) enriched Saccharomyces cerevisiae cells, using glutamic acid, phenylalanine, glycine, and lysine transport as an index of polyene antibiotic action. As compared with normal cells, phospholipid-enriched cells acquired resistance towards different polyenes. However, the sensitivity of glutamic acid transport towards nystatin remained unaffected in PC-, PE-, or PS-enriched cells. In contrast to nystatin, the other two polyenes were more effective in checking the influx of amino acids. Results demonstrated that the specific enrichment of PC, PE, or PS could selectively protect S. cerevisiae cells from polyene antibiotic action.
Model studies on a membrane filtration method for the enumeration of coagulase-positive staphylococci in swimming-pool water using rabbit plasma – bovine fibrinogen agar
Authors: Havelaar A. H. , During M.
Published: May 2010

The recovery of Staphylococcus aureus from swimming-pool water by membrane filtration was studied in model experiments. On the nonselective medium tryptone soya agar (TSA) there was no difference in counts of noninjured S. aureus with all membrane filters tested and with pour plates. Chlorine-injured S. aureus was enumerated most efficiently on TSA by Gelman Tuffryn HT-450 and Sartorius SM 13806 filters. Tuffryn filters were also most productive when used in combination with the selective medium rabbit plasma – bovine fibrinogen agar (RPFA). Other filters, particularly Gelman GN-6 and Millipore HAWP, when used on RPFA were shown to have a synergistic inhibitory effect on both noninjured and chlorine-injured S. aureus. This effect was not found on Baird-Parker agar. Using Tuffryn filters, counts on RPFA were equal to those on TSA for noninjured S. aureus and 0.1–2.0 log units less for chlorine-injured S. aureus. Despite this, the possibility for reading the in situ coagulase reaction for individual colonies on RPFA is considered such an advantage of this medium that its general use for enumeration of S. aureus in swimming pools is recommended. Further studies should be carried out to allow better resuscitation.
Lipid profiles of Aspergillus niger and its unsaturated fatty acid auxotroph, UFA2
Authors: Chattopadhyay Panchanon , Banerjee Santu Kumar , Sen Kalyani , Chakrabarti Parul
Published: May 2010

A comparative study of the mycelial lipid composition of a wild strain (V35) and one unsaturated fatty acid auxotroph (UFA2) of Aspergillus niger has been performed. The lipid composition of both strains are qualitatively the same but quantitatively different. All the strains contain the following phospholipids: cardiolipin, phosphatidylethanolamine, phosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylcholine, and phosphatidylserine; and triglycerides, diglycerides, mono-glycerides, ergosterol, and sterol esters as the neutral lipids; mono- and di-galactosyl diglyceride as the major glycolipids along with small amounts of the corresponding mannose analogs. Phosphatidylethanolamine and phosphatidylcholine constitute the bulk of the phospholipids. The mutant (UFA2) contains a higher level of glycerides and lower levels of sterol (both free and esterified form), phospholipids, and glycolipids than the wild type. Aspergillus niger contains C16 to C18 saturated and unsaturated fatty acids. Small amounts of long-chain (C20 to C24) and short-chain (C10 to C14) saturated and unsaturated acids are also present. Linoleic, oleic, and palmitic are the major acids, stearic and linolenic acids being minor ones. UFA2 grows only in the presence of unsaturated fatty acid (C16 or C18) and accumulates a higher concentration of supplemented acid which influences its fatty acid profile.
Transformation of hamster embryo cells by chymotrypsin-treated and untreated polyoma virus: characterization of transformants
Authors: Chlumecky Vera , Stranks Donald C. , Colter John S.
Published: May 2010

The ability of chymotrypsin-treated (chymo+) and untreated (chymo−) polyoma virus to transform cultured hamster embryo fibroblasts was examined. The data show that exposure to this protease reduces the ability of the virus to transform non-permissive cells to essentially the same extent as it reduces its ability to replicate in permissive cells. Twenty-five lines of transformed cells were established from colonies growing in soft agar, and after 20 in vitro passages, cells of all lines were characterized with respect to their ability to form colonies in soft agar and their tumorigenicity in hamsters. While the studies showed that there are striking differences among the lines with respect to colony-forming ability, and real, though less striking differences in tumorigenicity, they failed to reveal any obvious differences between the groups of cell lines transformed by chymo− and chymo+ polyoma virus. Of 13 lines examined, all were found to express both middle and small polyoma T antigens, none express significant levels of large T antigen, and 11 express some form of what is probably a truncated large T antigen, the most common species having a molecular weight of 67 000.
Xylitol as a carbon source for growth and ethanol production by Pachysolen tannophilus
Authors: Neirinck Leonard G. , Tsai C. S. , Labelle John L. , Schneider Henry
Published: May 2010

A number of yeasts that produce ethanol from D-xylose also coproduce xylitol. Such coproduction is undesirable if ethanol is the desired product because of the detrimental effect on yield. The utilization of xylitol, thought to be the first catabolite of D-xylose, has been reported not to lead to the formation of appreciable amounts of ethanol. As part of an effort to improve the yield of ethanol, the use of xylitol for growth and ethanol formation by Pachysolen tannophilus under aerobic conditions was reinvestigated. The polyol was found to be used for ethanol formation. However, the conditions required for this process, as well as for growth, were more stringent than with D-xylose. Notably, xylitol supported growth only when its concentration was relatively high, while ethanol formation occurred over a range of concentrations, provided high cell densities were used.
Production of RNA-dependent haemolysin by Haemophilus pleuropneumoniae
Authors: Martin P. G. , Lachance P. , Niven D. F.
Published: May 2010

Five strains of Haemophilus pleuropneumoniae, out of eight strains tested, produced extracellular haemolysin(s) when grown in liquid culture in the presence, but not in the absence, of RNA. The haemolysin produced by the neotype strain was unstable, heat labile, and sensitive to degradation by pronase, trypsin, and chymotrypsin; moreover, trypan blue treated haemolysin preparations were less effective at causing erythrocyte lysis than were untreated preparations. Following growth in the absence of RNA, washed suspensions of the neotype strain produced extracellular haemolysin when incubated in the presence of RNA, glucose, and casein acid hydrolysate; extracellular haemolysin could not be detected if the incubation mixture contained chloramphenicol. The haemolysin produced by washed bacterial suspensions was similar to that produced by growing cultures in that it was unstable, heat labile, and sensitive to inactivation by the same complement of enzymes. Erythrocyte lysis induced by either haemolysin preparation was preceded by a prelytic phase, the duration of which was dependent upon haemolysin concentration and the initial temperature of the haemolysin–erythrocyte mixture. It is concluded that the haemolysin(s) produced by the neotype strain of H. pleuropneumoniae is distinct from, but closely related to both streptolysin S and the haemolysin produced by Treponema hyodysenteriae.
Factors favouring the accumulation of arabinitol in the yeast Debaryomyces hansenii
Authors: Nobre M. Fernanda , Costa Milton S. da
Published: May 2010

Culture conditions which lead to the intracellular accumulation of arabinitol were investigated in Debaryomyces hansenii. Arabinitol, detected in very low concentrations during the exponential phase of growth, accumulated during the stationary phase of growth in yeast extract – peptone – 1% (w/v) glucose medium. This polyol was retained intracellularly even after depletion of exogenous glucose, but was rapidly depleted during regrowth in fresh glucose medium. The accumulation of arabinitol was also favoured in media containing 1% (w/v) D-fructose, sucrose, L-arabinose, glycerol, and sodium acetate. High mannitol levels accumulated in stationary phase cells derived from growth in 1% (w/v) D-mannitol, and in these cultures only traces of arabinitol were detectable. Intracellular mannitol was also retained after the extracellular mannitol had been consumed, and was rapidly depleted during regrowth in glucose medium. Arabinitol did not accumulate in basal medium with no added carbon source, nor in media with nonmetabolizable carbon sources (D-arabinose or D-ribose). On the other hand, arabinitol accumulation was independent of the initial glucose concentration between 1% (w/v) and about 9% (w/v).
Évaluation de la dégradation de deux types de tanin condensé par des bactéries isolées d'écorces en décomposition
Authors: Deschamps A. M.
Published: May 2010

Forty-eight bacterial strains isolated from decaying bark were cultivated in a mineral medium with added quebracho and mimosa tannin extracts as carbon sources. The degradation of the two condensed tannins by each bacterial strain was compared by means of two dosage methods permitting estimations of the astringent capacity losses and the attack of the flavane-3-ols groups. For an even incubation period, tannin from mimosa was more strongly degraded than that from quebracho, and depolymerization was much more important than the attack of monomeric structures. These results confirmed the aptitude of those bacteria to degrade condensed tannins, and thus practical utilisation can be foreseen for such strains.[Translated by the journal]
Inhibition of chlamydospore production in Fusarium oxysporum by ammonia and high ion concentrations
Authors: Löffler H. J. M. , Schippers B.
Published: May 2010

NH4Cl in a Tris–HCl buffered solution inhibited chlamydospore production in germinated macroconidia of Fusarium oxysporum. KCl, CaCl2, and buffer solutions at higher concentrations were also inhibitory but to a lesser extent. At fixed concentrations of NH4Cl and KCl mixed at different ratios, chlamydospore production decreased with increasing concentrations of [Formula: see text]. This effect was stronger at pH 8.5 than at pH 7.5, suggesting that NH3 is the active component. In conclusion, both NH3 and high ion concentrations can be inhibitory to the production of chlamydospores in salt solutions. No qualitative differences were found between chlamydospores formed at different concentrations of ammonia.
Two types of xylanases of alkalophilic Bacillus sp. No. C-125
Authors: Honda H. , Kudo T. , Ikura Y. , Horikoshi K.
Published: May 2010

One alkalophilic Bacillus sp. strain C-125 (FERM No. 7344) was isolated from soil. From this organism, two types of xylanases, designated xylanase A and xylanase N, were purified by an ammonium sulfate precipitation followed by Biogel P-30 gel filtration, DEAE-cellulose chromatography, and Sephadex G-75 gel filtration. The molecular weights of xylanase A and N were estimated as 43 000 and 16 000, respectively. Immunological experiments indicated that xylanase A and xylanase N were entirely different protein molecules. Xylanase N was most active at pH 6.0–7.0, but xylanase A had a very broad pH activity curve (pH 6–10) and was still active even at pH 12.0. The maximum hydrolysis of xylan by the enzymes was about 25%. Both enzymes split xylan and yielded xylobiose and higher oligosaccharides but could hydrolyze neither xylobiose nor xylotriose. Trans xylosidation activities were detected in both enzymes.
Levains lactiques: corrélation entre les dénombrements sur gélose et l'ATP cellulaire
Authors: Roy R. , Goulet J.
Published: May 2010

Cellular ATP concentrations from six commercial cheddar cheese starter cultures propagated in skim milk under varying growth conditions were estimated. High correlations (r ≥ 0.98) were obtained between cellular concentrations from a specific culture and its corresponding plate counts at various phases of growth. However, major discrepancies were noticed in ATP concentrations from one starter culture to another at similar growth stages: no significant correlation could be found between ATP concentrations and corresponding plate counts when data from all six starter cultures were pooled. No significant correlation could be obtained for the same starter culture propagated under varying growth conditions.[Translated by the journal]
Development of a cell wash buffer that minimizes nucleic acid loss from Clostridium perfringens 10543 A
Authors: Blaschek Hans P. , Klacik Michael A.
Published: May 2010

Autolytic activity and nucleic loss from Clostridium perfringens 10543 A was demonstrated during successive cell washes in hypotonic TES buffer. Autolysis increased nearly sixfold and nucleic acid loss nearly twofold when 10 mM EDTA was added to 0.3 M Tris–sucrose buffer. Attempts to minimize both autolysis and nucleic acid loss from C. perfringens during routine washing steps were unsuccessful when the effects of sucrose concentration, pH, CaCl2 addition, or wash temperature were examined independently. However, autolytic activity was eliminated and nucleic acid loss reduced to less than 5% when C. perfringens cells were washed at 4 or 25 °C in 1.0 M sucrose, 50 mM Tris–HCl, and 25 mM CaCl2 at pH 5.7.
Chemical and enzymatic variation in the cell walls of pathogenic Candida species
Authors: Lyon Frank L. , Domer Judith E.
Published: May 2010

Cell walls, isolated from seven pathogenic species of Candida, were lipid extracted and fractionated by treatment with ethylenediamine or enzymatically hydrolyzed using chitinase and laminarinase. Two different chitinase preparations were used, one from Streptomyces sp. which had some β-1,3-glucanase activity, and another from Serratia marcescens which did not have glucanase activity. Laminarinase was a commercial preparation. The monosaccharide constituents of whole cell walls and the fractions derived from them were determined qualitatively and quantitatively by gas–liquid chromatography of the products of a mild acid hydrolysis and by the phenol – sulfuric acid assay of the products of a stronger acid hydrolysis. The monomeric constituents of the enzymatic hydrolyses were analyzed using gas–liquid chromatography. Approximately 50% of all walls was soluble in ethylenediamine. Glucose and mannose were the only monosaccharides found in all of the fractions derived from ethylenediamine extraction examined. Similarities among the strains, based upon relative amounts of glucose and mannose, were more apparent than differences, but statistical analyses of the data revealed a general trend of decreasing similarity in the following order, C. albicans and C. stellatoidea, C. tropicalis and C. parapsilosis, and C. pseudotropicalis, C. guilliermondii, and C. krusei. In the enzymatic assays, mannose and glucose were released by laminarinase, whereas glucose and N-acetyl-D-glucosamine or N-acetyl-D-glucosamine alone were released by the chitinases. These assays supported the trend in relationships cited above, with the data being somewhat more definitive.
An initial test of a method for the estimation of real mean particle size from shadowed samples
Authors: Willison J. H. M.
Published: May 2010

During shadowing, a "cap" of metal develops on small particles. This cap increases, apparent particle width (measured normal to the shadowing direction) by an extent which cannot be predetermined. The extent of this increase in particle size (here defined as the "cap," X) is estimated in the present method by using opposite (180° sample rotation) bidirectional shadowing. It is argued that the bidirectional cap is the sum of the two unidirectional caps, and therefore that X = 2A − (B + C), where A is the mean bidirectionally shadowed particle size, and B and C are the two mean unidirectionally shadowed particle sizes. As a validation of the method, the mean diameter of air-dried ferritin was estimated and the results appear to confirm the hypothesis (mean diameter by present method, 10.7 ± 0.2 nm; mean diameter by previous methods, 10.89 nm).
Production of the reserve material poly-β-hydroxybutyrate and its function in Azospirillum brasilense Cd
Authors: Tal Sara , Okon Yaacov
Published: May 2010

Azospirillum brasilense Cd was grown in ammonium–malate mineral salts medium in batch culture and in chemostat continuous culture. It was found that poly-β-hydroxybutyrate synthesis was favored under oxygen limitation in chemostat culture and under high C/N ratios towards the end of exponential growth in batch culture. The degradation and synthesis of poly-β-hydroxybutyrate under starvation conditions occurred in a biphasic pattern and was affected by the poly-β-hydroxybutyrate content of the cells. During a 7-day incubation period in phosphate buffer, the survival and respiration rate of bacteria containing about 40% poly-β-hydroxybutyrate (dry weight) were higher than those of cells containing about 5% poly-β-hydroxybutyrate. Polymer-rich cells fixed atmospheric nitrogen in the absence of exogenous carbon and combined nitrogen. Biphasic nitrogenase activity was observed during starvation. When nitrogenase activity was high, hydroxybutyrate dehydrogenase activity was low and vice versa. Aerotactic response was higher in polymer-rich cells. In the presence of stress factors such as ultraviolet irradiation, dessication, and osmotic pressure poly-β-hydroxybutyrate-poor cells died more rapidly than poly-β-hydroxybutyrate-rich cells.
Isozyme patterns of Armillaria intersterility groups occurring in British Columbia
Authors: Morrison D. J. , Thomson A. J. , Chu D. , Peet F. G. , Sahota T. S. , Rink U.
Published: May 2010

Isozyme patterns for esterase and polyphenol oxidase were determined for diploid isolates of the six Armillaria intersterility groups collected in British Columbia. Factor analysis of digitized isozyme banding patterns separated A. bulbosa, A. ostoyae, and groups V and IX of Anderson and Ullrich. Results suggest that isozyme patterns may be used to identify subgroups within intersterility groups and to identify closely related intersterility groups.
Effect of relative humidity, atmospheric temperature, and suspending medium on the airborne survival of human rotavirus
Authors: Ijaz M. Khalid , Sattar Syed A. , Johnson-Lussenburg C. Margaret , Springthorpe V. Susan , Nair Rama C.
Published: May 2010

The Wa strain of human rotavirus, grown in MA-104 cells, was suspended either in tryptose phosphate broth or feces from a case of rotaviral diarrhea. It was then aerosolized into a rotating drum using a Collison nebulizer. The drum air was sampled using an all-glass impinger containing tryptose phosphate broth as collecting fluid. At 20 ± 1 °C, the virus aerosolized from tryptose phosphate broth was found to survive best at 50 ± 5% relative humidity, where its half-life was 44.2 ± 6.3 h. At 30 ± 5% and 80 ± 5% relative humidity, the half-life of the virus was 24.5 ± 3.5 and 3.8 ± 1.0 h, respectively. At 6 ± 1 °C, the airborne survival of the virus at the mid and low relative humidity levels was further enhanced, but at the high relative humidity it remained very similar to that seen at 20 ± 1 °C. When aerosols of fecally suspended human rotavirus were held at 20 ± 1 °C with 50 ± 5% relative humidity, nearly 80% of the airborne virus particles remained infectious even at the aerosol age of 24 h. These findings may help in our understanding of the epidemiology of rotaviral infections.
Role of trap lectins in the specificity of nematode capture by fungi
Authors: Rosenzweig W. D. , Premachandran D. , Pramer D.
Published: May 2010

Seven adhesive-producing nematode-trapping fungi were tested for their ability to capture nine different nematodes. The nematodes included species that are free living as well as plant and insect parasites. The fungi displayed no selectivity. Each fungus was able to trap and consume all of the different nematodes tested. A study of cuticle surface saccharides of five of the nematodes revealed the presence on all the nematodes of glucose–mannose and N-acetylgalactosamine residues. L-Fucose residues were not found on any of the nematodes. The involvement of lectins in the capture of prey by nematode-trapping fungi is discussed.
Evidence that the mechanisms of fungitoxicity of 8-quinolinol and its bischelate with copper(II) are different
Authors: Gershon Herman , Grefig Anthony T. , Cady David J.
Published: May 2010

The copper(II) contents of the growth media, Sabouraud dextrose and Czapek–Dox broths, and of the spore inocula of Aspergillus niger (ATCC 1004), Aspergillus oryzae (ATCC 1011), Trichoderma viride (ATCC 8678), and Myrothecium verrucaria (ATCC 9095) were determined by atomic absorption spectrophotometry in a graphite furnace. The test systems composed of Sabouraud dextrose broth and spore inocula of the four fungi contained only a little over 3% of the copper(II) required to form a minimal inhibitory concentration of bis(8-quinolinolato)copper(II). The test system of Czapek–Dox broth and A. oryzae contained slightly less than 65% of the copper(II) required to form a minimal inhibitory concentration of the bischelate of 8-quinolinol with copper(II). When the minimal inhibitory concentrations of 8-quinolinol and bis(8-quinolinolato)copper(II) were added simultaneously to the test system of Czapek–Dox broth and A. oryzae, 10% of the combined mixture of toxicants caused complete inhibition of growth indicating synergism between the toxicants. These results together with the observation that α-lipoic acid as well as small aliphatic thiol-containing compounds (cysteine, glutathione, dithioerythritol, and dithiothreitol) reversed the toxicity of 8-quinolinol but not the toxicity of bis(8-quinolinolato)copper(II) led to the conclusion that the mechanisms of fungitoxicity of both toxicants are different.
The production of constitutive invertase and inulinase by the mushroom Panaeolus papillonaceus in submerged culture
Authors: Mukherjee (Chakraborty) Khana , Sengupta S.
Published: May 2010

Five different mushrooms were screened for extracellular inulinase and invertase activities. The enzymes were found to be produced constitutively by the mushrooms, but the carbon source, glucose, sucrose, and starch, in the medium influenced the production of individual enzymes. The highest producers of inulinase and invertase were Panaeolus papillonaceus growing in starch medium and Agaricus bisporus growing in glucose medium, respectively. A medium for the optimum production of invertase and inulinase by P. papillonaceus was developed by determining the optimum concentrations of suitable carbon and nitrogen sources. Some of the physicochemical properties of the enzymes present in the culture filtrate were studied. Both of the activities have pH optima at 6.5 and temperature optima at 60 °C. Km values for both enzyme activities were found to be identical at 2.5 mg of substrate/mL, whereas the νm for the inulinase activity was more than two times greater than that for invertase activity.
Oxidative pathway for L-rhamnose degradation in Pullularia pullulans
Authors: Rigo Liu Un , Marechal L. R. , Vieira Muriel M. , Veiga L. A.
Published: May 2010

Growth of the fungus Pullularia pullulans on L-rhamnose induces the synthesis of L-rhamnofuranose dehydrogenase and other enzymes active in dissimilation of L-rhamnose (6-deoxy-L-mannose). The present findings indicate that at pH 7.0 a lactonase is active in the hydrolysis of L-rhamnono-γ-lactone. The resulting L-rhamnonate is then dehydrated into 2-keto-3-deoxy-L-rhamnonate by an L-rhamnonate dehydratase. It is also shown that, in the extracts, 2-keto-3-deoxy-L-rhamnonate aldolase participates in the catalysis of the cleavage of 2-keto-3-deoxy-L-rhamnonate to form pyruvate and L-lactaldehyde. The presence of D-glucose (0.2%) together with the inducer in the induction medium gives rise to approximately 50% repression of dehydrogenase synthesis, 80% repression of dehydratase synthesis, and 87% repression of aldolase synthesis. Induction of the enzymes of this nonphosphorylative pathway is completely inhibited in the presence of high levels of D-glucose (2%). It is suggested that these enzymes are active in the metabolism of L-rhamnose by the following pathway: L-rhamnose → L-rhamnono-γ-lactone → L-rhamnonate → 2-keto-3-deoxy-L-rhamnonate → pyruvate plus L-lactaldehyde, and that this is believed to be the route for L-rhamnose dissimilation in this microorganism.
Immuno-electron microscopic identification of Methanosarcina spp. in anaerobic digester fluid
Authors: Robinson Ralph W. , Erdos Gregory W.
Published: May 2010

Whole cell antibodies against Methanosarcina mazei strain S6 were used with protein A – colloidal gold to identify bacteria in thin sections of samples from anaerobic methane producing digesters. It was possible to identify bacteria at the genus level and to show relatedness at the species and strain levels. Heavy labelling was observed on thin sections of the immunogenic strain S6. Lighter labelling was observed with pure cultures of M. mazei strain LYC. Pure cultures of Methanococcus voltae or Methanobacterium thermoautotrophicum did not label. In samples from mesophilic sewage digesters, sarcinal colonies of bacteria similar to Methanosarcina showed heavy labelling per cell while colonies from 55 °C digesters show lighter labelling. A few free cocci, which were released from the sarcinal colonies, also labelled. Labelling was not observed on other bacterial forms in either set of digesters. These studies indicate that a collection of bacterial antibodies can be used to identify and map bacteria in situ in mixed samples.
Growth of Vibrio costicola and other moderate halophiles in a chemically defined minimal medium
Authors: Kamekura Masahiro , Wallace Rebecca , Hipkiss Alan R. , Kushner Donn J.
Published: May 2010

A simple chemically defined minimal medium consisting of sodium glutamate, glucose, vitamins, and salts was devised to support growth of the moderate halophile, Vibrio costicola, over as wide a range of NaCl concentrations as the complex medium, proteose peptone + tryptone. The lag period at higher NaCl concentrations was longer in the chemically defined minimal medium than in proteose peptone + tryptone. Chemically defined minimal medium also supported the growth of an unidentified moderate halophile, HX, and of Vibrio alginolyticus and Vibrio cholerae. The Mg2+ concentration required for good growth changed with the growth temperature for both V. costicola and HX.
Possible regulatory roles of ATP:citrate lyase, malic enzyme, and AMP deaminase in lipid accumulation by Rhodosporidium toruloides CBS 14
Authors: Evans Christopher Thomas , Ratledge Colin
Published: May 2010

The properties of ATP:citrate lyase, malic enzyme, and AMP deaminase have been investigated in Rhodosporidium toruloides CBS 14. ATP:citrate lyase had a molecular size of 480 000 daltons and apparent Km for citrate and ATP of 0.19 mM and 0.15 mM, respectively. The enzyme was inhibited by ADP, glucose 6-phosphate, palmitoyl-CoA, and oleoyl-CoA. [Formula: see text] ions showed a 95% stimulation of activity at nonsaturating concentrations (0.1 mM) of citrate. Malic enzyme had a molecular size of 205 000 daltons and an apparent Km for malate of 0.7 mM. The enzyme was only weakly inhibited by citrate, pyruvate, oxaloacetate, and ATP but no metabolite was found which exerted a significant regulatory control over the enzyme. However this enzyme could be used as the principal, if not sole, source of NADPH needed for fatty acid biosynthesis. The role of this enzyme and the central position of malate as a key metabolite in determining how lipid accumulation could be initiated and then sustained is discussed. AMP deaminase was detected in low activities but was fourfold higher in nitrogen-limited cells. The possible role of this enzyme in degrading AMP, regulating cellular energy charge, and supplementing [Formula: see text] pools in this yeast is also discussed.
Oxygen defense systems in obligately thermophilic bacteria
Authors: Allgood Gregory S. , Perry Jerome J.
Published: May 2010

Ten strains of Gram-negative, aerobic, obligately thermophilic bacteria were examined for their response to oxygen toxicity by comparing static with shaken cultures. All of the organisms tested had measurable levels of superoxide dismutase, catalase, and peroxidase. Aeration generally did not result in an increased level of superoxide dismutase in any of the thermophiles. Aeration of organisms obligate for n-alkane substrate caused an increase in cellular peroxidase levels and a corresponding decrease in catalase. The thermophiles that grew on either n-alkanes or complex media did not grow on the hydrocarbon in aerated culture but on a complex medium, aeration effected an increased level of catalase. With the exception of a pink-pigmented thermophile which, when aerated, did not have an increased level of the three oxygen defense enzymes, most of the thermophiles surveyed had an increased level of catalase or peroxidase when exposed to increased oxygen tension. The activity of the enzymes was determined at temperatures from 25 to 65 °C and the former temperature was satisfactory for these experiments.
Swarmer cell differentiation of Proteus mirabilis in fluid media
Authors: Dick H. , Murray R. G. E. , Walmsley S.
Published: May 2010

After 3–4 h in a rich fluid medium such as brain–heart infusion broth, motile nonseptate filaments developed from normal short rods and formed about 80% of the cell mass of Proteus mirabilis PM23. This developmental pattern was not observed in any of the other nine representatives of the species. These filaments were considered to be equivalent to swarmer cells formed on agar media because these cells ceased tumbling (i.e., chemotaxis was repressed), they developed large numbers of flagella (i.e., flagella synthesis and insertion was derepressed), and the distribution of nuclei in the filaments indicated that there was normal segregation. The population of cells grown in a minimal medium supplemented with amino acids and nicotinic acid consisted only of short cells with tumbling motility, despite the production of long cells and swarming on the same medium solidified with ordinary agar (refined agar was not effective). These short cells differentiated in 1–1.5 h in brain–heart infusion broth at 37 °C after an initial division. The requirements for initiation of differentiation were good basal nutrition, suitable cations (probably Ca2+ and Na+, or K+), and unknown heat-stable organic factors (molecular weight < 10 000) present in crude agar and yeast extract. Other components of media promoted swarmer differentiation if it was initiated and these included organic acids (lactate), amino acids (proline or serine), phosphate, and an appropriate ionic environment. Comparison of the observed sequence of length classes in brain–heart infusion broth culture with computer generated growth models suggested that, at the outset of growth, 50% of the products of each short cell division ceased septation but grew in length for about five doubling periods and then divided cells from each end at a faster rate (3–5 times per hour) for return to the short cell pool.
Expression of Campylobacter genes for proline biosynthesis in Escherichia coli
Authors: Lee Eileen C. , Walker Richard I. , Guerry Patricia
Published: May 2010

Cloned DNA from Campylobacter jejuni was found to complement auxotrophic defects in proline metabolism in several strains of Escherichia coli. A 4.4-kilobase fragment of Campylobacter DNA encodes the genes analogous to the proA and B genes of E. coli and Salmonella typhimurium.
Trypsin-susceptible cell surface characteristics of Streptococcus sanguis
Authors: Oakley J. David , Taylor K. Grant , Doyle R. Jennings
Published: May 2010

The adherence of Streptococcus sanguis to saliva-coated hydroxylapatite was markedly reduced by treatment of the cells with trypsin. In Scatchard plots of adherence data, protease-treated S. sanguis did not exhibit the characteristic positive slopes, suggesting that trypsin prevented cooperative interactions between the cells and artificial pellicle. Trypsin also reduced the tendency of S. sanguis to bind to hexadecane and to octyl-Sepharose. When sodium dodecyl sulfate was used to elute S. sanguis from columns of octyl-Sepharose, it was observed that the elution profiles of trypsin-treated cells were more complex than those of control cells. Water and salts were incapable of removing the cells from octyl-Sepharose. The results suggest that adherence to saliva-coated hydroxylapatite, binding to hexadecane and to octyl-Sepharose depend on trypsin-susceptible cell surface molecules.
Isolation and characterization of syringacin W-1, a bacteriocin produced by Pseudomonas syringae pv. syringae
Authors: Smidt Mary L. , Vidaver Anne K.
Published: May 2010

Syringacin W-1, a bacteriocin produced by Pseudomonas syringae pathovar syringae strain PsW-1, is a 20 × 75 nm rod-shaped particle composed of an inner core and outer sheath. Production of syringacin W-1 in broth was induced with 0.1 μLg/mL mitomycin C. The bacteriocin was purified from culture lysates using ultrafiltration, rate zonal centrifugation in sucrose gradients, and DEAE-cellulose chromatography. Purity was evaluated by subjecting syringacin W-1 preparations to electrophoresis in polyacrylamide gels under nondenaturing and denaturing conditions. The chemical composition was principally protein (67.2%), and also comigrating nonessential carbohydrate (10–35%). The physical properties of purified syringacin W-1 were a sedimentation coefficient of 104 for rod-shaped particles, pH stability of 5.2–8.2, and temperature stability from −20 to 40 °C. The bacteriocin was resistant to proteases and to 12 of 13 surfactants tested.
Lipopolysaccharide changes and cytoplasmic polyphosphate granule accumulation in Pseudomonas aeruginosa during growth on hexadecane
Authors: Miguez Carlos B. , Beveridge Terry J. , Ingram Jordan M.
Published: May 2010

Pseudomonas aeruginosa ATCC 9027 grew on 0.5% (v/v) hexadecane as a sole carbon source in a chemically defined medium which required the addition of Fe3+ and Ca2+. There was a variable and extended lag period before an active growth rate was attained. Visible light microscopic evidence revealed that the bacteria did not adhere to hexadecane droplets suggesting the absence of a bioemulsifier. When compared with glucose-grown cells, hexadecane-grown cells produced 75% less lipopolysaccharide (on a total protein basis); this lipopolysaccharide contained 30–40% less carbohydrate, yet 50–75% more 2-keto-3-deoxyoctonate. These chemical changes made the cell surface appear more hydrophobic when tested in a biphasic hydrophobicity index system. Electron microscopy of thin sections and freeze etchings revealed hexadecane-grown cells contained granules which were judged to be polyphosphate by energy dispersive X-ray analysis. There was no apparent major morphological envelope alteration within the two cell types.