bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical alterations in cell envelopes of Pseudomonas aeruginosa upon exposure to polymyxin: a possible mechanism to explain adaptive resistance to polymyxin
Authors: Gilleland Jr. H. E. , Champlin F. R. , Conrad Robert S.
Published: May 2010

Polymyxin-susceptible cells of Pseudomonas aeruginosa were exposed for 10, 30, and 60 min to growth medium containing 6000 units of polymyxin per millilitre. Exposure for 10 min resulted in lipid alterations in the cell envelope. A large reduction in the content of both phosphatidylethanolamine and phosphatidylglycerol with a large increase in both diphosphatidylglycerol and free fatty acids was found upon analysis by thin-layer chromatography. The cellular percentage of readily extractable lipid (REL) was reduced, and the phospholipid proportion of the REL decreased with polymyxin exposure. Polymyxin exposure for 30 and 60 min only slightly enhanced these chemical alterations. The cell envelope alterations found were characteristic for strains which become adaptively resistant to polymyxin. Treatment of the cells with chloramphenicol or KCN prior to polymyxin exposure did not prevent the lipid alterations from occurring. These observations suggest that the polymyxin-susceptible cell population adapts to polymyxin resistance by the rapid alteration of the cell envelopes of the entire cell population. We propose the theory that cell envelope phospholipases and proteases play a major role in the adaptive response and that the cation content of the cell envelope may be a critical controlling factor in the process.
The expression of nitrate reductase in free-living Rhizobium sp.
Authors: Gollop Rachel , Avissar Yael J.
Published: May 2010

Nitrate reductase activity is expressed in bacteroids of peanut nodules but is absent in log phase cultures of Rhizobium sp. grown in the absence of nitrate. The assay of enzyme activity in free-living cells in vivo revealed a brief period of activity in early stationary phase and a recovery of activity upon prolonged microaerobic incubation of stationary cell suspensions. The expression of enzyme activity did not necessitate concurrent differentiation of rhizobia to bacteriods or the induction of nitrogenase.
A turbidimetric and electron microscopic study of the effects of several parameters on the lysis of Streptococcus faecalis by lysozyme
Authors: Carvalho M. Egídia , Gonçalves M. Helena , Silva M. T.
Published: May 2010

The lytic effect of lysozyme on Streptococcus faecalis ATCC 9790 was studied by spectrophotometry and electron microscopy and it was found to be highly dependent on the ionic strength of the suspending media and on the ratio lysozyme to bacterial cell mass. When 7.2 × 108 bacteria/mL are exposed to 0.4 mg/mL of lysozyme in media with low ionic strength, the enzyme is bound in great amounts, as deduced from protein determinations and sodium dodecyl sulfate – polyacrylamide gel electrophoresis (SDS–PAGE); the binding prevents bacteriolysis in spite of the removal of the cell wall. Extensive lysis of S. faecalis could be obtained by reducing the ratio of lysozyme to bacterial cell mass. Stabilization of S. faecalis by lysozyme was also observed when exponential phase cells incubated under conditions that promote spontaneous autolysis (incubation in 0.05 M tris(hydroxymethyl)aminomethane buffer, pH 8.0, ionic strength = 0.01675) do not lyse and do not leak material which absorbs at 260 nm when lysozyme was present at the highest concentration.
Tricarboxylate transport in a Cit+Escherichia coli: evidence for the role of an outer membrane protein
Authors: Tomás Juan. M. , Kay William W.
Published: May 2010

A strain of Escherichia coli of bovine origin able to use tricarboxylates as single carbon source is described. Tricarboxylate utilization (Cit+) and fluorocitrate sensitivity (FCs) could be transferred conjugatively to E. coli K12 and were not plasmid borne. No evidence was found for tct gene products of Salmonella typhimurium. A citrate-inducible outer membrane protein of 21–22 kilodaltons (kd) was found only in Cit+ strains. A protein (21–22 kd) protein was also found in wild-type E. coli K12 and in fluorocitrate-resistant mutants of Cit+ strains, but it was present in a cryptic form no longer inducible by citrate. Fluorocitrate-resistant mutants of Cit+ strains were still able to transport citrate by a fuorocitrate-insensitive system. High levels of the 22-kd protein correlated with reduced growth induction times on citrate and with the ability to effectively transport citrate.
Rapid screening for bacteriuria with a laser nephelometer
Authors: Bayardelle Paul , Richet Hervé
Published: May 2010

Detection of significant bateriuria with a laser nephelometer was evaluated in this study and compared with the results obtained by the quantitative loop method. We screened 1002 urine specimens and 220 (21.95%) were found to be positive at ≥ 105 colony-forming units (CFU)/mL of urine by the standard method. Of the 220 positive specimens, 210 (95.4%) were detected in 6 h or less and 177 (80.4%) were detected within 3 h. The false-positive rate was 2.3% at 3 h and 19.7% at 6 h. These findings suggest that a 6-h procedure is necessary to detect 95% or more of significant bacteriuria. Laser nephelometer is versatile and can be used for rapid screening of bacteriuria.
Differential characteristics of catalase-positive Campylobacters correlated with DNA homology groups
Authors: Roop II R. Martin , Smibert Robert M. , Johnson John L. , Krieg Noel R.
Published: May 2010

Eighty-four strains of catalase-positive campylobacters could be placed into seven distinct DNA homology groups (species), corresponding to Campylobacter fetus, "C. hyointestinalis," C. jejuni, C. coli, "C. laridis," "C. fecalis," and aerotolerant Campylobacters. The biochemical and physiological characteristics of the strains were examined for their correlation with the homology groups. The characterization tests that provided the most reliable differentiation at the species and subspecies level were growth at 25 and 42 °C, sensitivity to cephalothin and nalidixic acid, growth in semisolid media containing 1% glycine and 3.5% NaCl, growth on plates containing 1.5% NaCl, growth in a semisolid minimal medium, anaerobic growth in the presence of 0.1% trimethylamine-N-oxide, hydrogen sulfide production in SIM medium and triple-sugar iron agar, hippurate hydrolysis, nitrite reduction, and growth on plates under an air atmosphere.
Dialysis culture for the production of Pseudomonas saccharophila α-amylase
Authors: Kadam Sunil K. , Fogarty William M.
Published: May 2010

Growth and α-amylase synthesis of Pseudomonas saccharophila was shown to be inhibited by the accumulation of a mixture of nonvolatile fatty acids during nondialysis cultivation. Using dialysis culture a 9-fold increase in the level of biomass and an 8.5-fold increase in α-amylase yield was achieved.
Characteristics and nitrogenase activity (acetylene reduction) of microaerophilic bacteria from roots of aquatic angiosperms
Authors: Ogan M.
Published: May 2010

Three strains of microaerophilic, N2-fixing bacteria isolated from Phalaris arundinacea L, Polygonum amphibium L, and Phragmites australis (Cav.) Trin. were tentatively identified as Azospirillum or Campylobacter. N2 fixation was studied by the C2H2 reduction and Kjeldahl digestion methods. Starter nitrogen-amended, semisolid agar mannitol medium supported higher growth and C2H2 reduction rates than similar media containing sugars or organic acids. The isolates reduced C2H2 maximally at between 25 and 27 °C, and at pH values between 5.6 and 7.3 compared with an optimum pH of 5.5 for C2H2 reduction by their habitat plant organs incubated under similar conditions. Isolates tolerated elevated levels of [Formula: see text] with concentrations of up to 57 μM enhancing C2H2 reduction and growth. C2H2-reducing phosphorus-starved cells responded to added [Formula: see text] after a lag (2.5–4 h).
Distribution of bdellovibrios in the water column of an estuary
Authors: Williams Henry N. , Falkler Jr. William A.
Published: May 2010

The distribution of bdellovibrios in the water column of the Miles River has been studied. Water samples were collected every 4 h over a 24-h period from five depths in the water column. The samples were cultured for the recovery of bdellovibrios lytic against Vibrio parahaemolyticus. Environmental parameters, i.e., salinity, temperature, turbidity, and dissolved oxygen (DO) were measured for each sample. Bdellovibrios were observed to be uniformly distributed at all depths measured in the water columns. There were no significant differences between the number of bdellovibrios recovered at the various depths. There were significant differences between the number of bdellovibrios recovered at various sampling times. However, no basis for these significant differences could be established. No association was found between the number of bdellovibrios recovered and the environmental parameters measured. Of interest was the observation that the distribution of the aerobic bdellovibrios did not correlate with DO measurements. The results suggest that neither depth nor DO content influenced the recovery of bdellovibrios from the Miles River.
Adherence of Candida albicans to buccal and vaginal epithelial cells: ultrastructural observations
Authors: Calderone Richard A. , Lehrer Nurith , Segal Esther
Published: May 2010

The adherence of Candida albicans to human buccal and vaginal epithelial cells was studied by transmission electron microscopy. Adherence to epithelial cells was confirmed by both a radiometric assay as well as direct microscopic examination of stained cell preparations. Ultramicroscopic preparations revealed that yeast cells were closely appressed to epithelial cell surfaces and were often partially enclosed within phagocyticlike invaginations of the epithelial cells. A murine model of vaginitis caused by C. albicans was also used to study adherence to epithelial cells and to follow the course of colonization. Ultramicroscopic preparations of murine vaginal tissue revealed that within 2 h postinfection, yeast cells could be seen adhering to epithelial cells. At 6 h postinfection, hyphae and yeast cells were not only found on the epithelial cell surface but also within the submucosal tissue. When observed on the epithelial cell surface, Candida cells were either attached to host cells, or when infected tissue was stained with ruthenium red, Candida cells were observed on the epithelial surface embedded within an electron-dense matrix. Fungal elements were abundant in the submucosa at 24 h postinfection and were still observed on the epithelial cell surface; all of this was accompanied by an inflammatory response.
Experimental meningococcal infection in neonatal animals: models for mucosal invasiveness
Authors: Salit Irving E. , Melle Elaine Van , Tomalty Lewis
Published: May 2010

A more complete understanding of meningococcal disease has been hampered by lack of an appropriate animal model. We subjected 5-day-old guinea pigs, rats, and mice to intranasal challenge with meningococci and we measured rates of bacteremia as a marker of mucosal invasion. After a single intranasal instillation of 107 serotype 2 meningococci, positive blood cultures were found in 0% of guinea pigs, 16% of rats, and 39% of mice, and so mice were used for further studies. Death occurred in 4% of mice and was associated with a purulent leptomeningitis and ventriculitis. Forty percent of mice had nasopharyngeal colonization which increased to 65% with repeated injections. Carrier strains were avirulent, a nonserotype 2 disease strain had low invasiveness, and serotype 2 strains were most virulent. Iron dextran increased rates of bacteremia after challenge with serotype 2 strains. Adult animals were not susceptible to bacteremia after intranasal challenge. The neonatal mouse model fulfills most of the criteria for an appropriate experimental model of meningococcal disease.
Relationship between group JK corynebacteria and the biotypes of Corynebacterium genitalium and Corynebacterium pseudogenitalium
Authors: Evangelista Alan T. , Coppola Karen M. , Furness Geoffrey
Published: May 2010

Twenty-six strains of group JK corynebacteria had the same colonial morphology and biological reactions as the biotypes of the biovars of Corynebacterium genitalium and C. pseudogenitalium. Therefore, group JK corynebacteria can be assigned to the biovars of C. genitalium or C. pseudogenitalium. Although the strains differed in sensitivity to 16 antibiotics tested by Sensi-Discs or by the Micro-Media technique, they are uniformly sensitive to 4–5 μg/mL of vancomycin. Medium containing 10 μg vancomycin/mL was bactericidal and the killing time was dependent on the concentration. The rate of mutation to resistance to 10 μg vancomycin was greater than 1 in 1010 corynebacteria. Therefore, vancomycin sensitivity is a stable characteristic of these corynebacteria which also indicates that group JK corynebacteria are strains of either C. genitalium or C. pseudogenitalium. Since group JK corynebacteria are considered pathogens, this finding supports the belief that C. genitalium is a pathogen and suggests that some biotypes of the commensal C. pseudogenitalium may infect compromised hosts.
The antibacterial activity of some naturally occurring 2,5-dihydroxy-l,4-benzoquinones
Authors: Brewer D. , Jen W.-C. , Jones G. A. , Taylor A.
Published: May 2010

Polyporic acid, atromentin, bovinone, and oosporein are common metabolic products of a number of species of fungi. The related compound cochliodinol and its congeners are produced by several Chaetomium spp. These quinonoid metabolites have been shown to inhibit the growth and metabolism of a range of bacterial genera. The antibiotic activity of the quinones depends on the substituents at the 3 and 6 positions of the 2,5-dihydroxy-1,4-benzoquinone ring; in aerobic systems the activity appears to be inversely proportional to the polarity of the metabolite. It has been shown that reduction of the quinone to the hydroquinone changes the antibiotic activity of these metabolites but does not abolish it. Contrary to previous reports, the activity of these hydroquinones is not reversed by cysteine.
Experimental studies of the pathogenesis of infections owing to Pseudomonas aeruginosa: elastase, an IgG protease
Authors: Holder Ian Alan , Wheeler Robert
Published: May 2010

Pseudomonas aeruginosa elastase, but not alkaline protease, degraded pooled, normal, human IgG in vitro and this degraded IgG lost its protective effect when used to treat burned, P. aeruginosa infected mice. Plasma IgG levels in burned, uninfected mice declined immediately postburning, but remained relatively constant thereafter; the levels in burned, P. aeruginosa infected mice continued to decline until death ensued. Infection of burned mice with an elastase+ strain caused the IgG decline, while infection with an elastase− strain did not, suggesting that elastase production caused the in vivo decline in plasma IgG. Local treatment with the protease inhibitor α2-macroglobulin, of burned mice infected with an elastase+ organism, reduced the IgG decline observed in control mice. These data support the hypothesis that P. aeruginosa elastase acts as an IgG protease both in vitro and in vivo and gives insight into how this enzyme may act as a virulence factor in P. aeruginosa.
Serology and plasmid carriage in Vibrio cholerae
Authors: Newland J. W. , Voll M. J. , McNicol L. A.
Published: May 2010

Vibrio cholerae strains of the 01 serovar, isolated from both clinical and environmental sources, had a much lower frequency of plasmid carriage (2/112 = 2%) than clinical and environmental non-01 serovar isolates (46/187 = 25%). The cryptic plasmids found in non-01 strains were all of low molecular weight and were shown by hybridization analysis to consist of two unrelated subgroups. Each subgroup was observed to be present in strains isolated from both clinical and environmental sources. One 01 serovar (ATCC 14033) carried a small cryptic plasmid, belonging to one of these plasmid groups, while a second (25728) contained a high molecular weight multiple antibiotic resistance plasmid which did not hybridize to either plasmid subgroup.
Acidic exopolysaccharide from Penicillium allahabadense
Authors: Rupérez P. , Gomez-Miranda B. , Leal J. A.
Published: May 2010

Penicillium allahabadense grown statically in liquid medium formed an extracellular polysaccharide which was collected by precipitation with ethanol (fraction A). The mycelium mat retained a considerable amount of polysaccharide extractable with water, which did not precipitate with ethanol but precipitated with FeCl3 (fraction B). Both fractions were formed mainly by glucose and malonic acid. Their optical rotation values and infrared spectra indicated β configuration. From fraction A was obtained the polysaccharide in the acid form (fraction C), whose equivalent weight is 425, and the demalonylated polysaccharide (fraction D). The main linkage type among glucose residues in the demalonylated polysaccharide, determined after Smith degradation, was 1 → 6. The main component obtained by methylation analysis was 2,3,4-tri-O-methyl-glucitol.
ELISA evaluation of the competitive abilities of two Rhizobium meliloti strains
Authors: Rice W. A. , Olsen P. E. , Page W. J.
Published: May 2010

The double antibody sandwich enzyme-linked immunosorbent assay (DAS-EL1SA) was used to determine the competitive abilities of Rhizobium meliloti strains BALSAC and NRG-185 which are used in commercial alfalfa inoculants for eastern and western Canada, respectively. The ratio of NRG-185:BALSAC in the inoculum applied to aseptically grown alfalfa (Medicago sativa L.) was adjusted to 0:100, 1:99, 50:50, 90:10, 99:1, or 100:0. The ratios between nodules containing only the BALSAC strain and nodules containing only strain NRG-185 were similar to their respective inoculum strain ratios. Nodules containing both strains occurred only with the inoculum strain ratio of 50:50. Total plant weights were highest with the two single strain inocula and were decreased 5–19% with dual strain inoculation. The decrease in total plant weight was significantly correlated with decreases in nodule number and nodule weight. The results suggest that R. meliloti strains BALSAC and NRG-185 have equal competitive abilities, but are somewhat antagonistic, resulting in decreased nodulation and plant growth when both are present in an inoculum.
Essai de mise en évidence d'une activité protéolytique d'origine intracellulaire chez Aeromonas hydrophila LP 50
Authors: Denis Françoise , Veillet-Poncet Louise
Published: May 2010

Aeromonas hydrophila LP 50, isolated from packaged pasteurized milk, was grown in glucose–polypeptone medium at 30 °C. The proteolytic activity of A. hydrophila LP 50, optimum at the stationary phase of growth, is attributed to extracellular or membrane protease; no intracellular proteolytic activity was shown.
Immunological and enzymatic properties of the Desulfovibrio desulfuricans hydrogenase
Authors: Ziomek E. , Martin W. G. , Williams R. E.
Published: May 2010

Affinity-purified antibodies specific for the purified, active periplasmic hydrogenase of Desulfovibrio desulfuricans were prepared. Immunodiffusion and enzyme-linked immunosorbent assay (ELISA) methods showed distinct differences between the native form of hydrogenase and the enzyme modified by heat, acid, active-site, and group-specific chemical treatments. The ELISA method indicated two zones of sensitivity, one for a native form of enzyme and another for irreversibly inactivated hydrogenase. The ELISA technique was also used to estimate the maximum specific activity of the enzyme in cell extracts. Immunoglobulins directed towards only the inactive form could not be obtained. A mixed immunoglobulin population directed towards both active and inactive forms of the enzyme was obtained by affinity chromatography on inactive hydrogenase – Sepharose. Immunological and enzymatic studies of the periplasmic hydrogenases in the Desulfovibrio genus showed strain dependence of the enzyme concentration in these microorganisms. The hydrogenases of two strains of Escherichia coli and several other bacteria were examined and showed strong cross-reaction with the hydrogenase of Desulfovibrio desulfuricans. It was found that the periplasmic and membrane-bound hydrogenases of Desulfovibrio desulfuricans ATCC 7757 differed in both enzymatic and immunological properties.
Superoxide dismutase, catalase, and peroxidase in ammonium-grown and nitrogen-fixing Azospirillum brasilense
Authors: Clara Richard W. , Knowles Roger
Published: May 2010

Superoxide dismutase (SOD), catalase (CAT), and peroxidase (PER) activities were studied in ammonium-grown and N2-fixing batch cultures of Azospirillum brasilense Sp7. PER activity, as measured using o-dianisidine or 3,3′-diaminobenzidine as the H donor, was not significant in most growth conditions. SOD activity increased in response to higher O2 concentrations but was also present in cells grown anaerobically with nitrate [Formula: see text] or nitrous oxide (N2O) as electron acceptor. CAT activity increased at lower O2 concentrations and was highest in cells grown anaerobically with [Formula: see text] as electron acceptor. Polyacrylamide gel electrophoresis of cell-free extracts revealed only one band of SOD activity under each of the physiological conditions employed, compared with three for aerobically grown Escherichia coli K12. This band proved to be iron-containing SOD (FeSOD) on the basis of inhibitor sensitivity.
Properties of cell wall peptidoglycan synthesized by amino acid deprived relA mutants of Escherichia coli
Authors: Vanderwel Désirée , Ishiguro Edward E.
Published: May 2010

Cell wall peptidoglycan synthesis in Escherichia coli is under stringent control. During amino acid deprivation, peptidoglycan synthesis is inhibited in re1A+ bacteria but not in re1A mutants. The relaxed synthesis of peptidoglycan by amino acid deprived re1A bacteria was inhibited by Several β-lactam antibiotics at concentrations which inhibited cell elongation in growing cultures suggesting that the transpeptidase activity of penicillin-binding protein (PBP-1B) was involved in this process. Structural studies on the peptidoglycan also indicated the involvement of transpeptidation in relaxed peptidoglycan synthesis. The peptidoglycan synthesized during amino acid deprivation was cross-linked to the existing cell wall peptidoglycan, and the degree of cross-linkage was the same as that of peptidoglycan synthesized by growing control cells. The relaxed synthesis of peptidoglycan was also inhibited by moenomycin, an inhibitor of the in vitro transglycosylase activities of PBPs, but the interpretation of this result depends on whether the transglycosylases are the sole targets of moenomycin in vivo. Most of the peptidoglycan lipoprotein synthesized by histidine-deprived re1A+ bacteria was in the free form as previously reported, possibly because of the restriction in peptidoglycan synthesis. In support of this proposal, most of the lipoprotein synthesized during histidine deprivation of re1A mutants was found to be covalently linked to peptidoglycan. Nevertheless, the peptidoglycan synthesized by amino acid deprived re1A bacteria was apparently deficient in bound lipoprotein as compared with peptidoglycan synthesized by normal growing control bacteria suggesting that the rate of lipoprotein synthesis during amino acid deprivation may be limiting.
Comparison of commercial beef extracts and similar materials for recovering viruses from environmental samples
Authors: Hurst Christon J. , Dahling Daniel R. , Safferman Robert S. , Goyke Tamara
Published: May 2010

Microbiological- and food-grade beef extracts, protein hydrolytic, enzymatic and autolytic digestion products, and whole protein materials were examined for their potential effectiveness for eluting adsorbed enteroviruses from membrane filters with observed efficiencies ranging from less than 1 to 69%. Concentration of enteroviruses from solutions of these protein and protein-derived products by organic flocculation ranged in efficiency from 2 to 125%. Both elution and concentration were dependent upon virus type, as well as nature, source, and production lot of the material being tested. Determining the efficiency of virus concentration was complicated by virus aggregation and apparent virus inactivation by low pH. Effectiveness of concentrating viruses by organic flocculation from solutions prepared with the various test materials seemed independent of the amount of precipitate produced during the flocculation procedure. Quality assurance tests were proposed by which solutions prepared from beef extracts, whole protein, and protein-derived materials could be evaluated for use in eluting adsorbed viruses from membrane filters and for concentrating viruses by organic flocculation. Food-grade beef extract seemed equal to microbiological-grade beef extract in terms of both virus elution and concentration. Several of the nonbeef extract materials evaluated were as effective as beef extract for virus concentration, but were less effective for virus elution.
Effect of synthetic iron chelates on population densities of Fusarium oxysporum and the biological control agent Pseudomonas putida in soil
Authors: Scher F. M. , Dupler M. , Baker R.
Published: May 2010

Although soil conducive to Fusarium wilt diseases was previously induced to become suppressive by addition of FeEDDHA (ferric ethylenediaminedi-o-hydroxyphenylacetic acid), addition of FeEDTA (ferric ethylenediaminetetraacetic acid) or FeEDDHA to soil infested with F. oxysporum f. sp. conglutinans (the radish wilt pathogen) did not significantly affect inoculum densities in rhizosphere soil in this study. Addition of 100 μg FeEDTA/g soil significantly decreased levels of Pseudomonas putida in rhizosphere soil; however, addition of 100–1000 μg FeEDDHA/g soil significantly increased population densities of P. putida in fallow and rhizosphere soils. The suggested mechanism was that Fe3+ available to the Fusarium was reduced by competition with EDDHA and that such competition in soil may give selective advantage to siderophore-producing antagonists such as P. putida.
Effect of several nitrification inhibitors on carbon monoxide and methane oxidation by ammonium oxidizers
Authors: Jones Ronald D. , Morita Richard Y.
Published: May 2010

The effects of nine inhibitors of chemolithotrophic nitrification on carbon monoxide, methane, and ammonia oxidation by Nitrosomonas europaea, Nitrosococcus oceanus, and Nitrosomonas sp. 4W30 (a marine isolate) were examined. CH4 and [Formula: see text] oxidation were inhibited to a greater extent than the oxidation of CO. A concentration of 10 μg/mL of N-Serve was sufficient to completely inhibit [Formula: see text] oxidation in all three species, while a concentration of 100 μg/mL was necessary to completely inhibit CO oxidation. The three organisms used in this study showed widely differing susceptibilities to the inhibitors examined. CO and [Formula: see text] oxidation by Nitrosomonas europaea and Nitrosomonas sp. 4W30 were inhibited by >90% in the presence of 100 μg/mL amino-1,2,4-triazole, while Nitrosococcus oceanus was not inhibited. Terrazole at a concentration of 10 μg/mL inhibited carbon monoxide oxidation by Nitrosococcus oceanus 98.9%, while Nitrosomonas europaea and Nitrosomonas sp. 4W30 were only inhibited by 80.2 and 87.1%, respectively. At 100 μg/mL terrazole inhibition was complete. The results of this study emphasize the necessity of careful selection of nitrification inhibitors and concentrations to be used when examining ammonium oxidizers in natural samples. It also indicates that there arc subtle differences in the physiology of ammonium oxidizers that should be taken into consideration when studying the metabolism of these organisms.
Serotype distribution of meningococci isolated in South Australia 1971 through 1980
Authors: Ashton F. E. , Ryan A. , Diena B. B. , Hansman D.
Published: May 2010

The serotypes of meningococci isolated from 76 sporadic cases of meningococcal disease in South Australia during the years 1971 through 1980 were determined. Thirty-four (56%) of the 61 group B strains were nontypable; the remainder were of five serotypes namely 8 (16%), 1 (13%), 2 (2a and 2b) (9%), 12 (3%), and 15 (3%). Four of the five group B type 2 strains were serotype 2b. Serotype 2a accounted for four of seven group C strains and four of five group W135 strains. Overall serotypes 2 (2a and 2b) (17%), 8 (13%), and 1 (10%) occurred most frequently amongst the typable strains, whereas 40 (53%) of the 76 strains were nontypable. The results indicate that several serotypes and many nontypable strains were responsible for the sporadic disease occurring during a 10-year period in Australia.
Resting sporangium of Synchytrium endobioticum: partial characterization of the cell wall protein
Authors: Patel T. R. , Bal A. K. , Hampson M. C.
Published: May 2010

The resting sporangium wall of Synchytrium endobioticum has a Triton X-100 extractable protein component, which is rich in glycine and has a molecular weight of 26 000.
Microbial resolution of DL-N-benzyloxycarbonyl-p-hydroxyphenylglycine by Streptomyces zaomyceticus
Authors: Suhara Yasuji , Itoh Sayuri , Yokose Kazuteru , Ninomiya Rieko , Watanabe Kimihiro , Maruyama Hiromi B.
Published: May 2010

Using DL-p-hydroxyphenylglycine umbelliferone carbamate as the probe, screening from soil was carried out for microbes capable of hydrolysing urethane-type derivatives. Out of 71 strains positive for umbelliferone liberation (fluorescent), 8 strains were able to hydrolyze DL-N-benzyloxycarbonyl-4-hydroxyphenylglycinc (I). One of such soil organism identified as Streptomyces zaomyceticus carried out this reaction in an enantio-selective manner. Optically active, pure D-N-benzyloxycarbonyl-4-hydroxyphenylglycine and L-4-hydroxyphenylglycine were obtained in crystalline form in 83 and 80% yields, respectively, after a 5-day incubation of the substrate (300 mg/100 mL) with this organism. In contrast to conventional L-acylase (EC 3.5.1.14) which can hydrolyze N-pbenylacetyl-4-hydroxyphenylglycine but not I, the enzymes responsible for the above resolution could cleave both substrates, indicating that they represent a unique type of amidohydrolase.
Transduction of bacteriophage resistance in Streptococcus pyogenes with coinfection lysates of the virulent phage A25ts1-2 and a temperate bacteriophage 2511
Authors: Stuart James G. , Rogel Rene , Morton Tom
Published: May 2010

Two new mutants of Streptococcus pyogenes designated KS107 and KS136 were shown to allow adsorption of a virulent bacteriophage KV1, but replication of viral DNA did not occur in these mutants. The novel observation was made that coinfection of donor ceils with phages A25ts1-2 and 2511 enhanced transduction of phage resistance and of antibiotic resistance. Mixed donor lysates did not give enhanced transduction. Antiserum to A25ts1-2 blocked transduction, suggesting that the presence of 2511 promoted packaging of chromosomal DNA into A25ts1-2 particles. Phage 2511 was isolated by induction of a clinical strain, but it behaved as a lytic phage in laboratory strains. Phage KV1 was isolated from sewage and was found to be closely related to A25ts1-2, whereas 2511 was clearly different. The phage resistance gene of KS107 was not linked to any of three antibiotic resistance genes by cotransduction tests.
Growth inhibition of Neisseria gonorrhoeae isolates by L-phenylalanine and its analogues in defined media
Authors: Hendry A. T. , Dillon J. R.
Published: May 2010

Growth inhibition by phenylalanine (0.25 mmol/L in defined agar media) was present in about 1% of over 1000 clinical isolates of Neisseria gonorrhoeae isolates tested. Turbidometry of several phenylalanine-sensitive isolates showed that their growth rates decreased in proportion to phenylalanine concentrations up to about 1 mmol/L. The growth rate was unaffected if 0.04 mmol/L tyrosine was also present. The phenylalanine analogue DL-3-fluorophenylalanine inhibited the growth of all 23 isolates further tested on agar. This inhibition was derepressed by phenylalanine in all 17 phenylalanine-resistant isolates. Phenylalanine plus tyrosine were required to derepress the analogue inhibition in the other six phenylalanine-sensitive isolates. Phenylalanine-sensitive isolates may have a defect in aromatic amino acid synthesis, not involving auxotrophy, but manifested through regulation of the pathways. Phenylalanine effectively repressed tyrosine and phenylalanine synthesis. In 125 isolates including 85 β-lactamase producers (PPNG) and 32 phenylalanine-sensitive isolates, phenylalanine inhibited 63.2% of 38 PPNG isolates carrying the 3.2 megadalton (Md) plasmid, but only one of 47 PPNG isolates carrying the 4.5 Md plasmid. PPNG isolates are most often of the proline, ornithine, or nonrequiring auxotypes. Phenylalanine sensitivity did not appear to be auxotype dependent.
Xylose metabolism in Pachysolen tannophilus: purification and properties of xylose reductase
Authors: Ditzelmüller Günther , Kubicek Christian P. , Wöhrer Wilfried , Röhr Max
Published: May 2010

Xylose reductase (xylitol: NADP oxidoreductase, EC 1.1.1.139) has been purified from D-xylose grown cells of the yeast Pachysolen tannophilus by application of DEAE-cellulose ion exchange chromatography, 2′,5′-ADP-Sepharose affinity chromatography, Biogel P200 gel filtration, and dextran blue Sepharose chromatography to approximately 95% homogeneity. It consists of a single polypeptide chain with a relative molecular weight of 35 000–40 000 and an isoelectric point of pH 4.9. The enzyme has a broad substrate specificity similar to that of aldose (or aldehyde) reductases from mammalian tissues. It exhibits Michaelis–Menten type kinetics (Km D-xylose, 162 mM; Km D-xylitol, 212 mM; Km NADPH, 0.059 mM; [Formula: see text], 0.071 mM). The enzyme is specific for NADPH; activity with NADH is below 0.5% of Vmax observed with NADPH. The reduction of xylose is inhibited by NADP, the anabolic reduction charge (NADPH/NADP + NADPH), and also in a complex manner by ATP. At physiological pH values the equilibrium is Keq = 10−10. The importance of these findings for the physiology of xylose fermentation by this yeast is discussed.
Effect of various inhibitors on sporulation of Bacillus subtilis crs mutants
Authors: Takahashi I. , Sun Dongxu
Published: May 2010

The effect of aliphatic alcohols, cerulenin, and NaCl on sporulation of various catabolite-resistant (crs) mutants of Bacillus subtilis was studied. Mutants carrying crsA or crsF mutations were able to sporulate in the presence of these agents. Other crs mutants were resistant to at least one of the inhibitors. Electron microscopic examination revealed that cerulenin blocks sporulation at stage 0 in wild-type cells, suggesting that early sporulation functions are affected by this antibiotic. The results obtained so far suggest that the functions altered in the crs mutants may be related to the membrane.
Analyse ultrastructurale et biochimique de mutants pléiotropes de Bacillus subtilis affectés dans le contrôle de la sporulation
Authors: Zucca Joseph , Renaudin Serge
Published: May 2010

Derived from a Bacillus subtilis unstable mutant strains which hyperproduce extracellular proteases were found to contain mutations at loci scoC, scoD, or scoE; these were observed by transmission electron microscopy. In scoC and scoD strains, spores formed overproduced spore coat proteins and the spore ultrastructure was deeply altered. In scoE strains, stage III of the sporulation was blocked. The pleiotropic effect of scoC mutations was either positive or negative. In unstable strains, mutations at the scoC locus stimulated α-amylase and levane sucrase hyperproduction. In stable strains, the same mutations led to an absence of α-amylase synthesis but to a normal levane sucrase production. ScoD mutations only induced α-amylase hyperproduction, while scoE mutations allowed neither levane sucrase production nor spore coat protein synthesis.
Ubiquinone in hydrogen metabolism by Azotobacter vinelandii
Authors: Kow Yoke W.
Published: May 2010

Extraction with n-heptane abolished over 95% of the NADH oxidase and the hydrogenase activity in membrane preparations from Azotobacter vinelandii. Incorporation of ubiquinone-8 or plastoquinone restored each reaction to about 55% of its original activity.
Metabolism of α-terpineol by Pseudomonas incognita
Authors: Madyastha K. Madhava , Renganathan V.
Published: May 2010

Details of the metabolism of α-terpineol by Pseudomonas incognita are presented. Degradation of α-terpineol by this organism resulted in the formation of a number of acidic and neutral metabolites. Among the acidic metabolites, β-isopropyl pimelic acid, 1-hydroxy-4-isopropenyl-cyclohexane-1-carboxylic acid, 8-hydroxycumic acid, oleuropeic acid, cumic acid, and p-isopropenyl benzoic acid have been identified. Neutral metabolites identified were limonene, p-cymene-8-ol, 2-hydroxycineole, and uroterpenol. Cell-free extracts prepared from α-terpineol adapted cells were shown to convert α-terpineol, p-cymene-8-ol, and limonene to oleuropeic acid, 8-hydroxycumic acid, and perillic acid, respectively, in the presence of NADH. The same cell-free extract contained NAD+-specific dehydrogenase(s) which converted oleuropyl alcohol, p-cymene-7,8-diol, and perillyl alcohol to their corresponding 7-carboxy acids. On the basis of various metabolites isolated from the culture medium, together with the supporting evidence obtained from enzymatic and growth studies, it appears that P. incognita degrades α-terpineol by at least three different routes. While one of the pathways seems to operate via oleuropeic acid, a second may be initiated through the aromatization of α-terpineol. The third pathway may involve the formation of limonene from α-terpineol and its further metabolism.
The effects of chlorate- and streptomycin-resistance mutations on nitrofurantoin resistance in Escherichia coli K-12
Authors: Obaseiki-Ebor Emmanuel E. , Breeze Anthony S.
Published: May 2010

Chlorate-resistant mutants with none of the usual pleiotropic effects such as defective nitrate reductase activity were isolated from Escherichia coli K-12. These chlorate-resistant mutants (designated chlHW) did not yield strains with a high level of nitrofurantoin resistance following selection with nitrofurantoin. The chlorate-resistance mutation reduced the nitrofurantoin resistance of high-level mutants to an intermediate level. Further mutation to resistance to streptomycin and other aminoglycoside antibiotics suppressed the effect of chlHW on the level of nitrofurantoin resistance. Other chlorate-resistance genes examined did not have the same effect on nitrofurantoin resistance as chlHW. The gene was cotransducible (P1) with intermediate-level nitrofurantoin resistance and proC. It is suggested that the chlHW mutation may enhance the accumulation of nitrofurantoin inside the cell since it is known that a multiple aminoglycoside-resistance mutation with pleiotropic effects on the cell membrane can also confer high-level resistance to nitrofurantoin.
Metabolism of carbaryl and carbofuran by soil-enrichment and bacterial cultures
Authors: Rajagopal B. S. , Rao V. R. , Nagendrappa G. , Sethunathan N.
Published: May 2010

Metabolism of side chain and ring 14C-labelled carbaryl and carbofuran in a mineral salts medium by soil-enrichment cultures and a Bacillus sp. was studied. A change in the substrate of the medium from carbaryl to carbofuran led to a marked shift in the dominant bacterium from Bacillus sp. to Arthrobacter sp. although carbaryl-enrichment culture was the primary inoculum in both media. Hydrolysis was the major route of microbial degradation of both carbamate insecticides. During carbaryl degradation by enrichment cultures and Bacillus sp., 1-naphthol and 1,4-naphthoquinone accumulated in the medium. Of the three metabolites formed from carbofuran, 3-hydroxycarbofuran and 3-ketocarbofuran were further metabolized rapidly, while carbofuran phenol was resistant to further degradation. Evolution of 14CO2 and other gaseous 14C-labelled products from both side chain and ring labels was negligible. This and slow degradation of the hydrolysis products led to significant accumulation of 14C in the medium even after prolonged incubation.
Purification and properties of ι-carrageenase from a marine bacterium
Authors: Greer C. W. , Yaphe W.
Published: May 2010

An ι-carrageenase has been purified from the cell-free culture medium of a marine bacterium grown in ι-carrageenan. The enzyme hydrolyzes the β1 → 4 linkages in ι-carrageenan; the major end products, as identified by 13C nuclear magnetic resonance spectroscopy, are ι-neocarratetraose sulfate and ι-neocarrahexaose sulfate. The enzyme was purified by fractionation on Sephacryl S-200 in 2.0 M NaCl and hydrophobic interaction chromatography on Phenyl-Sepharose CL-4B. The purified enzyme had an apparent molecular weight of 57 000, and optimum activity was expressed at pH 8.0, 40 °C, in 0.1 M Na+. The enzyme was stable for at least 6 months at 4 °C in 1.0 M NaCl. Removal of the salt, freezing, or lyophilization destroyed enzyme activity. Membrane fractions, prepared by discontinuous sucrose density gradient centrifugation, also exhibited ι-carrageenase activity. Properties of ι-carrageenase suggest an association with cell wall components.
Properties of chitin synthase from mucoraceous hosts of a mycoparasite
Authors: Manocha M. S. , Begum A.
Published: May 2010

Crude chitin synthase extracted from young (24 h) hyphae of Choanephora cucurbitarum and Phascolomyces articulosus, susceptible and resistant hosts, respectively, to the mycoparasite, Piptocephalis virginiana, was identified and characterized by measuring the incorporation of the substrate [14C]UDP – N-acetylglucosamine into chitin. The enzyme activity was mainly associated with the mixed membrane fraction. Properties of the enzyme preparation such as activation with proteases, N-acetylglucosamine, magnesium, inhibition with polyoxin D, Vmax, apparent Km value for UDP – N-acetyl-D-glucosamine (UDP-GlcNAc), and response to pH were examined. Enzyme activity from both fungi displayed basically the same features as the corresponding enzymes reported from other mucoraceous fungi. However, the two enzyme preparations (from P. articulosus and C. cucurbitarum) differed from each other in their response to various proteases and storage at 4 °C. Enzyme preparation from P. articulosus was activated by all proteases, whereas the C. cucurbitarum preparation was activated by acid protease, slightly activated by trypsin over a narrow concentration range, and was inhibited by neutral protease. Enzyme preparation from C. cucurbitarum showed a rapid decrease in activity within the first 5 h of storage at 4 °C and also exhibited relatively higher activity of endogenous proteases than that from P. articulosus.
Detection and functional characterization of early appearing antibodies in rabbits with experimental syphilis
Authors: Rice Marianne , Fitzgerald T. J.
Published: May 2010

Following testicular infection of rabbits with Treponema pallidum, different antibodies become detectable initially at the time of healing. Experiments were performed to determine a functional role for these antibodies. Rabbits were sacrificed after 4–8 days. Treponemal numbers steadily increased for 10–12 days. Thereafter, host defenses were sufficiently stimulated to begin clearing the organisms. Antibodies in serum and antibodies localized at the site of infection were quantitated using radioimmunoassay and enzyme-linked immunosorbent assay (ELISA) techniques. Anti-treponemal lgG was detected as early as day 4. Quantities of antibody correspondingly increased with time following infection. Treponema pallidum was harvested 7 and 14 days postinfection and tested for surface antibodies. With increasing days postinfection, more antibody was found on the organisms. Two functional properties of these antibodies were shown. Sera from 24 of 45 rabbits infected for 14 days immobilized T. pallidum in the presence of complement and 14-day sera blocked the attachment of T. pallidum to tissue culture cells. We suggest that antibody-mediated, complement-dependent immobilization of T. pallidum and blockage of attachment are at least partially responsible for healing of testicular lesions.
Extracellular enzymes of Phytophthora infestans: endo-cellulase, β-glucosidases, and 1,3-β-glucanases
Authors: Bodenmann Jakob , Heiniger Ursula , Hohl Hans R.
Published: May 2010

An endo-cellulase, two β-glucosidases, and two 1,3-β-glucanases from Phytophthora infestans were partially purified from the culture filtrate and their biochemical properties determined. The molecular weights were estimated by chromatography on Sephacryl S-200 and were 21 000 (endo-cellulase), 160 000 – 230 000 and 32 000 (β-glucosidases I and II), 160 000 – 230 000 and 21 000 (β-glucanases I and II). The optimal pH of the endocellulase was 6.0. The other enzymes showed the following optimal pH and temperature values: β-glucosidase 1,5.5 and 48 °C; β-glucosidase II, 5.25 and 30 °C; 1,3-β-glucanase 1, 7.0and40 °C; and 1,3-β-glucanase II, 4.5 and 45 °C. The β-glucosidase II was unstable above 30 °C, while the other enzymes remained stable to 43 °C. The β-glucosidase I did not show Michaelis–Menten kinetics for p-nitrophenyl-glucopyranoside (pNPG) and gentiobiose as substrates. The extrapolated Km value for pNPG was 1.1 mmol/L and the Km value for cellobiose was 280 mmol/L. The Km values of the β-glucosidase II were 34 mmol/L for pNPG, 340 mmol/L for cellobiose, and 42 mmol/L for gentiobiose. Finally, the Km value of the 1,3-β-glucanase II for laminarin was 0.29 g/L. The isoelectric point of the enzymes were 3.2 (endo-cellulase), 3.3 (β-glucosidase I), 4.7 (β-glucosidase II), and 3.4 (the two 1,3-β-glucanases). At 10 mmol/L, Cu2+ inhibited the β-glucosidase I by 90%, and the β-glucosidase II by about 50%. The 1,3-(3-glucanase II was inhibited 75% by Mn2+ and 35% by Cu2+.
Preparation of protoplasts from mycelium and arthroconidia of Geotrichum candidum
Authors: Jacobsen Tomas , Jensen Bo , Olsen Jørgen , Allermann Knud
Published: May 2010

Protoplasts were released from mycelium and the cylindrical type of arthroconidia from Geotrichum candidum by a lytic enzyme (Novozym 234). This enzyme was unable to release protoplasts from the ellipsoidal type of arthroconidia, which reflects a difference in the cell walls of the two types of conidia. The conditions necessary to obtain stable protoplasts were determined. Magnesium sulphate (0.8 M) was the best osmotic stabilizer for the formation of protoplasts, whereas both mannitol and magnesium sulphate could be used for regeneration. The regeneration was faster with mannitol than with magnesium sulphate.
Loss of a cytoplasmic factor through ethidium bromide and elevated temperature treatments in Nectria haematococca
Authors: Daboussi Marie-Josée
Published: May 2010

The invasive sector modification of Nectria haematococca, associated with a cytoplasmic factor σ, is characterized by an alteration of growth and an hyperproduction of pigments. To obtain insight into the molecular nature of this factor, we devised a curing protocol for cells which carry it. We tested the effect of elevated temperatures and drugs on the maintenance or the replication of the σ factor as estimated by the frequency of cultures which have lost the modified character. Modified cultures were converted into normal cultures when grown at 34 °C or in the presence of ethidium bromide, but not in the presence of cycloheximide or 5-fluorouracil. These results are discussed in connection with the possible involvement of a DNA plasmid in the control of sector modifications.