bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of the fates of the methyl carbons of m-cresol and p-cresol in methanogenic consortia
Authors: Roberts Deborah J. , Fedorak Phillip M. , Hrudey Steve E.
Published: May 2010

The fates of the methyl carbons of 14C-methyl labeled m-cresol and p-cresol in methanogenic consortia were determined. The reduction of [Formula: see text] to 14CH4 by these consortia was also examined. Most (92%) of the methyl carbon of p-cresol was oxidized to [Formula: see text] accompanied by some reduction of [Formula: see text] to CH4 (2% of label). In contrast, 87% of the methyl carbon of m-cresol was converted to CH4 and only 5% was recovered as CO2. No reduction of [Formula: see text] to 14CH4 was observed in m-cresol degrading consortia. Both consortia incorporated small percentages of the methyl label into cellular macro-molecular material.
Separation of cytoplasmic ribosomal proteins of Microsporum canis
Authors: Mandiyan Valsan , Rao G. Ramananda
Published: May 2010

The cytoplasmic ribosomal proteins of Microsporum canis were characterised in basic–acidic and basic–SDS two-dimensional polyacrylamide gel electrophoresis systems. The small subunit contained 28 proteins and the large subunit 38 proteins. The molecular weights of these proteins were in the range of 32 500 to 7600 and 48 000 to 11 000 in the small and large subunits, respectively. The 80S ribosomes showed 65 and 66 protein spots in basic–acidic and basic–SDS gel systems, respectively.
Ultrastructural localization of β-(1 → 4)-D-glucans in two pathogenic fungi and in their host tissues by means of an exoglucanase–gold complex
Authors: Benhamou Nicole , Chamberland Hélène , Ouellette G. B. , Pauze F. J.
Published: May 2010

An exoglucanase, purified from a cellulase produce by the fungus Trichoderma harzianum Rifai., was successfully bound to colloidal gold and used for ultrastructural detection of intracellular cellulosic β-(1 → 4) glucans. These saccharides were found to be present in great amount in the walls of Ophiostoma ulmi (Buism.) Nannf., the Dutch elm disease agent, whereas they were randomly distributed in the walls of Fusarium oxysporum Schlecht f. sp. radicis-lycopersici Jarvis and Shoemaker (FORL), the agent of tomato crown and root rot. In O. ulmi cell walls, the β-(1 → 4) glucans were predominantly concentrated over the central portion of the inner walls. In both colonized elm wood and infected tomato root tissues, the compound middle lamella and secondary walls of parenchyma cells, fibers (absent in tomato roots), and vessel members were always intensely labeled, but gold particles appeared somewhat irregularly distributed. In fibers having an S3 gelatinous layer, the latter was always preferentially labeled. Penetration of O. ulmi in elm wood tissues resulted in the digestion of host wall areas free of labeling. Such areas were not observed in infected tomato tissues; instead, an accumulation of gold particles was noted along the fungal portion that was in close contact with the host wall. Results of this study confirm the potential value of gold-labeled exoglucanase and provide some new information about wall topochemistry during host-pathogen interactions.
Minicell formation by Campylobacter jejuni
Authors: Brock F. M. , Murray R. G. E.
Published: May 2010

Campylobacter jejuni sheds its flagella and varying proportions of the poles of the cell late in the growth cycle, resulting in the production of very small flagellated structures 0.1 to 0.3 μm in diameter. Electron microscopy revealed that these structures were minicells possessing outer membrane, cytoplasmic membrane, flagellar basal complex, and polar membrane; nucleoplasms were not seen. The initial event in the formation of these minicells involved a constriction of the cytoplasmic membrane, segregating the polar regions of the cell. The peptidoglycan layer of the cell wall was not visible, but was presumed to lyse at the separation site of minicell formation, and to reform or remain intact along the main length of the cell because the rods did not spheroplast. Finally, rupture and resealing of the outer membrane component of the wall resulted in the release of fully enclosed minicells and nonflagellated rods.
Microbial transformation of menthol and menthane-3,4-diol
Authors: Shukla O. P. , Bartholomus R. C. , Gunsalus I. C.
Published: May 2010

A bacterium isolated from sewage by enrichment on (−)-menthol will use as sole source of carbon (−)-menthol and the related compounds, (−)-isopulegol, (+)-isomenthol, (±)-neomenthol, geraniol, and menthane-3,4-diol, but not (+)-menthol and (+)-isopulegol. Medium from (−)-menthol grown cells contains menthone, 3,7-dimethyl-6-hydroxyoctanoic acid, and 3,7-dimethyl-6-oxo-octanoic acid. Cell suspensions incubated with (−)-menthol yielded the same intermediates. Metabolism of menthane-3,4-diol by this bacterium yielded the same oxo acid plus 4-hydroxy-3-keto-p-menthane. A pathway is proposed for the oxidation of menthol and menthane-3,4-diol by this organism.
Azospirillum effects on susceptibility to Rhizobium nodulation and on nitrogen fixation of several forage legumes
Authors: Yahalom Eli , Okon Yaacov , Dovrat Amos
Published: May 2010

Azospirillum brasilense Cd cell concentration of 105–107 colony-forming units (cfu)/mL applied 24 h before Rhizobium (106 cfu/mL), increased nodule formation in the non root hair zone, more than twofold, in pouch-grown Medicagopolymorpha and Macroptilium atropurpureum seedlings, compared with Rhizobium alone. The increase in nodule formation in pouch-grown Trifolium alexandrinum following preinoculation with Azospirillum was 20%. The percentage of nodulated seedlings rose from 0 to 25% when Medicago polymorpha was preinoculated with Azospirillum followed by the application of 10 cfu/mL Rhizobium meliloti, a level which by itself was not sufficient to initiate nodule formation. Acetylene reduction activity in Medicago polymorpha and Macroptilium atropurpureum seedlings after inoculation with Azospirillum–Rhizobium was markedly increased. A possible reason for the increased susceptibility to Rhizobium infection may be that Azospirillum stimulates the formation of a larger number of epidermal cells that differentiate into infectable root hairs.
Effect of 3-substituted D-glucose and D-allose derivatives on growth of Botrytis cinerea
Authors: Brown Robert G. , Grindley T. Bruce , Reimer Gerald , Kralovec Jaroslav , Anderson Max
Published: May 2010

Ten 3-substituted D-glucose and D-allose derivatives were tested for their ability to inhibit growth of Botrytis cinerea. The results obtained indicate the importance of oxygen at position 3 for inhibitory activity. 3-Fluoro-3-deoxy-D-glucose was the most inhibitory analogue.
Octopine and octopinic acid utilization in a nonfluorescent Pseudomonas sp.: enhancement by spontaneous mutation and lack of effect from curing of a plasmid
Authors: Boivin Rodolphe , Lebeuf Hélène , Dion Patrice
Published: May 2010

An octopine-utilizing bacterium isolated from soil, named strain 92, was identified to the genus level as a nonfluorescent Pseudomonas. Utilization of octopine by strain 92 depended upon the presence of an alternative carbon source, while octopinic acid was not utilized. A mutant derivative, strain RB100, acquired simultaneously the capacity to utilize octopine as the sole carbon and nitrogen source and octopinic acid as the nitrogen source. The mutation rate was estimated to be about 10−8 per cell per generation. Both the wild type and mutant carried the 68.5-kilobase cryptic plasmid pDLB 1. When the plasmid present in strain RB100 was labelled with Tn5 and transferred to strain 92, the phenotype of the recipient was not modified with respect to octopine utilization, suggesting that this phenotype was not determined by pDLB1. This suggestion was confirmed by using unstable derivatives of pDLB1 to cure strain RB100 and showing that the cured strain was not affected in its capacity to utilize opines.
Wall turnover deficiency of Bacillus subtilis Nil5 is due to a decrease in teichoic acid
Authors: Vitković Ljubiša
Published: May 2010

Bacillus subtilis Ni15 is deficient in cell wall turnover. This deficiency is removed if the medium contains 0.2 M NaCl, which does not affect growth. The levels of amidase and glucosaminidase, the most likely enzymes involved in turnover, were, in stationary phase Nil5 cells, similar to those in late-exponential phase cells of a standard strain. The Nil5 enzymes were not salt sensitive. However, the Nil5 walls contained 4.7-fold less phosphorus than the walls of the standard strain. Since the phosphorus content of B. subtilis walls reflects the level of teichoic acid, it is proposed that the turnover deficiency of this strain is due to a decrease in wall teichoic acid.
O-linked but not N-linked glycosylation is necessary for the secretion of endoglucanases I and II by Trichoderma reesei
Authors: Kubicek C. P. , Panda T. , Schreferl-kunar G. , Gruber F. , Messner R.
Published: May 2010

The effect of inhibiting protein glycosylation was studied in nongrowing mycelia and protoplasts of Trichoderma reesei which secreted two endoglucanases (I and II) upon addition of sophorose. Tunicamycin (40 μg∙mL−1) inhibited incorporation of N-acetylglucosamine into secreted protein, but had no effect on secretion of total protein or endoglucanases. The secreted endoglucanases I and II exhibited relative molecular masses of 58 and 45 kilodaltons, respectively, irrespective of the presence of tunicamycin. On the other hand 2-deoxy-D-glucose inhibited the biosynthesis of extracellular as well as intracellular protein over a wide range of concentrations; at 50 μg∙mL−1, however, it inhibited the synthesis of extracellular protein more strongly. The synthesis of endoglucanases I and II was decreased accordingly under these conditions. SDS–PAGE did not reveal the secretion of endoglucanases with smaller molecular weights. When the two endoglucanases were purified and subjected to Endo H treatment or β-elimination, the former had no detectable effect, whereas the latter released all carbohydrate from the protein. Nevertheless, endoglucanases I and II contained 1.3 and 0.5 mol of glucosamine per mol enzyme, respectively. It is concluded that endoglucanases I and II from T. reesei contain mainly O-linked neutral carbohydrate, which is required for their secretion.
An electron microscope study of kidney basement membrane changes in the mouse by lipoteichoic acid from Streptococcus pyogenes
Authors: Leon Ofra , Panos Charles
Published: May 2010

Mice injected repeatedly, intraperitoneally or intravenously, for approximately 1 month with a total of 1.04 mg lipoteichoic acid from a nephritogenic strain of Streptococcus pyogenes lost weight. Analysis by electron microscopy revealed that they also exhibited extensive kidney changes in basement membrane morphology which resembled, in part, those observed in human poststreptococcal glomerulonephritis. For example, the glomerular basement membrane became electron dense and exhibited at least a twofold increase in width sporadically within the same preparation after exposure to lipoteichoic acid. Also, whereas appreciable loss or reduction in epithelial foot processes as a result of fusion was clearly evident, epithelial slits and slit membranes or diaphragms between normal foot processes were not selectively affected. In addition, another mostly thickened, highly coiled or serpentinelike basement membrane with amorphous nodules appeared in these preparations. This type membrane was not observed surrounding the capillary lumina and was the most pronounced abnormality apparent in almost all preparations from mice exposed to lipoteichoic acid. Likewise, the proximal tubular basement membrane became variable in width and increased in electron density in mice given lipoteichoic acid as compared with controls. In addition, this membrane was often punctuated with various morphological protrusions originating from only its thickened areas and which extended away from, and not into, the capillary space. This change was only associated with the basement membrane of the proximal tubular capillaries. All membrane changes persisted but gradually subsided, with normal kidney membrane morphology reappearing on the 4th day following the last injection of lipoteichoic acid. The use of mice and minute amounts of lipoteichoic acid to study membrane damage or change in the fine structure of the glomerular or proximal tubular areas at the immediate presymptomatic, and very early symptomatic, phase of streptococcal glomerulonephritis is noted.
Temperature, pH, and cations affect the ability of Escherichia coli to mobilize plasmids in L broth and synthetic wastewater
Authors: Khalil Taher A. , Gealt Michael A.
Published: May 2010

Coincubations of plasmid donor and recipient cells in L broth and in synthetic wastewater demonstrated that a large number of environmental factors must be taken into account when measuring the potential for the dissemination of plasmid-encoded genes in natural environments. These include salts and detergents in the medium as well as other factors, e.g., pH and temperature. Complex interactions between and among agents were observed, indicating that simple additive effects may not be assumed. Mobilization of genetically engineered nonconjugative plasmid pHSV106 was inhibited by the same compounds that affected conjugative plasmid movement.
Infection of immature soybean pods and seeds by Phomopsis longicolla
Authors: Baker Daniel M. , Minor Harry C. , Brown M. F. , Brown E. A.
Published: May 2010

Phomopsis longicolla Hobbs, a causal agent of Phomopsis seed decay, colonizes the seed coats and embryos of mature soybean (Glycine max (L.) Merr.) seeds. The mode of infection of immature soybean pods and seeds by P. longicolla was examined using scanning electron microscopy. Phomopsis longicolla penetrated directly through pod walls by appressoria. Penetration through stomata in the pod surface was not observed. Immature seeds were also penetrated directly. Heavily infected immature seeds showed extensive colonization of the seed coats and embryos.
Suitability of the BLCR medium for isolating Azospirillum brasilense
Authors: Horemans S. , Demarsin S. , Neuray J. , Vlassak K.
Published: May 2010

The suitability of an improved selective culture medium (BLCR) for the isolation of Azospirillum brasilense was verified. Of seven A. brasilense isolates, only three grew on the medium. Strains RO7, S631, and our own isolates 85M74 and 85M78 did not grow. The use of this medium in studies on natural populations of Azospirillum brasilense therefore may not be a suitable practice.
Relation between pigment intensity and penetrating ability in appressoria of Colletotrichum lagenarium
Authors: Kubo Yasuyuki , Furusawa Iwao , Shishiyama Jiko
Published: May 2010

Mutant 8004 of Colletotrichum lagenarium formed slightly pigmented appressoria. The appressoria germinated laterally on glass slides, but could penetrate nitrocellulose membranes. The slightly pigmented appressoria of the albino mutant 79215 were observed to behave in a similar manner when treated with 100 μM scytalone. The appressorial pigmentation of mutant 8004 was increased by the application of scytalone, and mature appressorial pigmentation, indistinguishable from that of the parent strain 104-T, was observed when appressoria were treated with 100 μM scytalone, a lower concentration than that needed for mature pigmentation of the albino mutant. The sensitivity to tricyclazole of appressorial pigmentation of mutant 8004 was higher than that of the parent strain 104-T. These results suggest that, although melanin biosynthesis is essential for appressorial penetration, slight pigmentation is sufficient.
Effect of ultraviolet light irradiation on viability and aflatoxin production by Aspergillus parasiticus
Authors: Moreno Miguel A. , Ramos María del Carmen , González Andrés , Suárez Guillermo
Published: May 2010

The effect of ultraviolet light irradiation (254 nm) on both the viability and the aflatoxin-producing ability of the fungus Aspergillus parasiticus NRRL 2999, a good aflatoxin-producing strain, was studied. This strain showed noticeable resistance and irradiation for more than 10 min was necessary to reduce survival to under 10%, while the white mutants were more susceptible (5 min of irradiation reduced survival to under 1%). Induction of mutants with complete loss of aflatoxigenicity was rare and only 3 of the 1463 survivors tested were aflatoxinless.
Characterization of manganese-oxidizing (MnII→MnIV) bacteria from Negev Desert rock varnish: implications in desert varnish formation
Authors: Hungate B. , Danin A. , Pellerin N. B. , Stemmler J. , Kjellander P. , Adams J. B. , Staley J. T.
Published: May 2010

A collection of 79 bacterial isolates was obtained by plating scrapings and swabs from five rock varnish samples of the Negev Desert, Israel. Of the bacterial isolates which were obtained, 74 were able to oxidize manganese (MnII→MnIV) under laboratory conditions. The manganese-oxidizing bacteria were characterized and identified, when possible, to genus. The predominant genera were Bacillus, Geodermatophilus, Arthrobacter, and Micrococcus. Examples of all of these genera were found from more than one rock. These same genera have been reported from manganese-rich rock varnish samples from the Sonoran and Mojave Deserts of North America; however, many of the strains (species?) from the Negev appear to be different from those of the American Southwest. A single manganese-oxidizing actinomycete was also isolated. The high percentage of manganese-oxidizing bacteria to total cultivable bacteria (83 to 100% depending upon sample) from the Negev suggests that they are involved in desert varnish formation.
Isoenzyme and protein patterns of pentose-fermenting yeasts
Authors: Jeng Robert S. , Yu Shiyuan , Wayman Morris
Published: May 2010

Soluble proteins were extracted from the vegetative cells of four pentose-fermenting yeasts, Candida shehatae, Pichia stipitis, R-1, and R-2, the R strains being of uncertain taxonomy, while the other two are culture collection yeasts. Isoenzyme patterns, protein patterns, and two-dimensional polypeptide mapping of these four strains were compared by polyacrylamide gel electrophoresis. The two R strains showed great similarity in two-dimensional polypeptide mapping, the pattern of sodium dodecyl sulfate – polyacrylamide gel electrophoresis, isoelectrofocusing, and isoenzymes, and may be one species. Each of the other two yeasts had its own characteristic electrophoretic pattern. The R strains showed the presence of three alcohol dehydrogenase isoenzymes compared with one for the culture collection yeasts, as well as much higher activity of malate dehydrogenase, isocitrate dehydrogenase, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase, which further the formation of pyruvate and ethanol.
The perforate component of the regularly structured (RS) layer of Lampropedia hyalina
Authors: Austin John W. , Murray R. G. E.
Published: May 2010

The regularly structured (RS) layer of Lampropedia hyalina was found to consist of two components; of these, the inner perforate layer was easily isolated from cell envelopes by dissolution of attached material by incubation in 2% sodium dodecyl sulfate at room temperature. The layer consisted of a 31.5-kilodalton polypeptide arranged in p6 symmetry so that, in negative stain, it appeared to be a sheet full of regularly arranged holes with a repeat frequency of 13 nm. The layer was stable in chelating and reducing agents, and in various detergents. Dissolution of the perforate layer occurred in boiling sodium dodecyl sulfate, 6 M guanidine–HCl, 8 M urea, 90% formic acid, and in buffers below pH 4 and above pH 11. In its dissociated state, the component polypeptide was sensitive to hydrolysis by endoproteinase glu-C, while the assembled polypeptide was not affected, suggesting that the acidic amino acid residues are hidden from the protease in the assembled state.
Effect of chlorine injury on heat-labile enterotoxin production in enterotoxigenic Escherichia coli
Authors: Walsh Suzanne M. , Bissonnette Gary K.
Published: May 2010

Heat-labile enterotoxin (LT) production was examined in chlorine-injured and noninjured populations of enterotoxigenic Escherichia coli (ETEC) by passive immune hemolysis and Y-1 mouse adrenal tumor cell assays. Sublethally injured populations showed reduced LT production after 1, 2.5, and 4 h incubation in trypticase soy broth plus 0.25% glucose, pH 8.0. Reduction was observed during injury, resuscitation, and for at least 1.5 h following repair. LT levels comparable with that present in noninjured cells were found after 24 h incubation in the same medium, indicating delayed toxigenesis rather than permanent damage. Chlorinated populations failed to incorporate [14C]glucose until repair was completed suggesting a possible explanation for delayed toxin production. The results indicate a temporary loss of virulence among sublethally injured ETEC in chlorinated waters.
Evaluation of Bacillus subtilis C186 as a potential biological control of sapstain and mould on unseasoned lumber
Authors: Seifert Keith A. , Hamilton Wendy E. , Breuil Colette , Best Maureen
Published: May 2010

Bacillus subtilis C186 was evaluated as a potential biological control agent for sapstain and mould growth on unseasoned lumber. The strain produces antibiotics that are fungistatic to many pine-inhabiting fungi. Although pine blocks precolonized with C186 and subsequently inoculated with staining fungi were generally less discoloured than blocks inoculated only with fungi, discolouration was not sufficiently prevented to warrant further consideration of this strain as a biological control agent. The disappointing performance of C186 is traced to its poor colonization of wood.
A simplified, defined medium for growth of Entomophaga aulicae protoplasts
Authors: Nolan Richard A.
Published: May 2010

A defined medium, which allowed growth in both stationary and shaken cultures in the absence of fetal calf serum, was developed for protoplasts of the fungus Entomophaga aulicae. The protein "requirement" was obviated and growth was enhanced by the addition of hematin (0.5 μg/mL) and oleic acid (1.0 μg/mL). The utilization and production of ninhydrin-positive compounds was monitored at various stages of medium simplification. The protoplasts were autotrophic for all vitamins and organic acids. Fructose was not required for protoplast growth; however, it could function as a carbon source. The optimum nitrogen level was 635.08 mg N/L, and the optimum carbon level was 280 mg C/L under the conditions utilized. The protoplasts did not utilize either inorganic nitrogen (ammonium ion) or sulfur (sulfate ion) at the levels tested. No amino acid could function as a sole nitrogen source. Analysis of the amino acid composition of a general (> 14 000 molecular weight) protein extract gave no evidence of a skewed amino acid content. The final simplified medium included 8 amino acids (aspartic acid, glutamic acid, glycine, histidine, leucine, methionine, phenylalanine, and threonine) of the 21 in the original medium. This medium is useful in isolating vitamin auxotrophs for use as markers in virulence and in protoplast fusion studies, and in studies on the chemical nature of the limiting membrane and its outer surface.
A modified m-CP medium for enumerating Clostridium perfringens from water samples
Authors: Armon Robert , Payment Pierre
Published: May 2010

Medium m-CP, designed for the isolation of Clostridium perfringens from water samples, contains indoxyl β-D-glucoside, an expensive chemical that is present at a high concentration in this medium. The use of m-CP with three concentrations of indoxyl β-D-glucoside was tested at 0, 60, and 600 mg/L. Lowering the amount of indoxyl β-D-glucoside to 60 mg/L (1/10 the recommended concentration) reduced the cost of this medium without affecting its sensitivity.
The effect of cyclosporin A on Trypanosoma musculi infection of mice
Authors: Roger Michel , Vigeant Pierre , Viens Pierre
Published: May 2010

Cyclosporin A treatment of mice infected with Trypanosoma musculi mimicked the effect of T-cell deprivation in increasing the parasitemia and lowering the antibody responses. However, in contrast to T-cell deprivation, cyclosporin A treated mice were still able to clear the parasites from the blood. As expected, T-cell deprived mice were not responsive to cyclosporin A. It is suggested that antibodies against T-independent antigens of the parasite are ineffective in promoting elimination of the trypanosomes. These findings support the importance of T-helper cells in the final elimination of T. musculi from the blood of mice.
Protoplast production and regeneration from mycorrhizal fungi and their use for isolation of mutants
Authors: Hébraud Michel , Fèvre Michel
Published: May 2010

Methods were developed for the reproducible production of high yields of stable protoplasts from monokaryotic and dikaryotic mycelia of Hebeloma cylindrosporum. This is a prerequisite for mutation, cell fusion, and transformation of this mycorrhizal fungus. Protoplasts from Hebeloma cylindrosporum, Hebeloma edurum, Hebeloma sinapizans, and Suillus bellini were released by using cellulase Onozuka R 10 and driselase as lytic enzymes. Production was strongly influenced by the nature and molarity of the osmotic stabilizer and by the mycelial age. In spite of the high percentage of anucleate protoplasts (42%) produced, the regeneration rate averaged 15%. Fungicide-resistant mutants from monokaryotic mycelia of H. cylindrosporum were isolated following ultraviolet irradiation of protoplasts. This indicates that protoplasts will be useful to select physiological mutants from nonsporulating mycelia and to create new strains by mating complementary mycelia or by interspecific cell fusion.
Influence of legume cover crops and conservation tillage on soil populations of selected fungal genera
Authors: Rothrock C. S. , Hargrove W. L.
Published: May 2010

The influence of winter legume cover crops and of tillage on soil populations of fungal genera containing plant pathogenic species in the subsequent summer sorghum crop were examined in field studies. Legume cover crops significantly increased populations of Pythium spp. throughout the sorghum crop compared with a rye cover crop or no cover crop. This stimulation of the populations of Pythium spp. was not solely due to colonization of cover-crop residue, as populations were significantly greater at the time the legume cover crop was desiccated. Removal of aboveground residue generally decreased populations of Pythium spp. in soil. Incorporation of residue by tillage increased populations of Pythium spp. at some sampling dates. Legumes differed in the magnitude of stimulation, with hairy vetch stimulating Pythium spp. more than crimson clover. Cover crop treatments did not consistently influence soil populations of Fusarium spp., Rhizoctonia solani, Rhizoctonia-like binucleate fungi, or Macrophomina phaseolina. Macrophomina phaseolina populations were significantly greater under no tillage.
Purification of extracellular amylolytic enzymes from the thermophilic fungus Thermomyces lanuginosus
Authors: Jensen Bo , Olsen Jorgen , Allermann Knud
Published: May 2010

When grown in static culture it appears as if Thermomyces lanuginosus has a biphasic secretion of the extracellular starch-degrading activity. This could be due to the presence of at least two different amylases. By ion-exchange chromatography on DEAE-Trisacryl an α-amylase (EC 3.2.1.1) and a glucoamylase (EC 3.2.1.3) were separated and purified from the extracellular protein from 14-day-old static cultures grown on soluble starch. The hydrolysis of soluble starch by the purified glucoamylase resulted in only glucose as the end product, whereas the α-amylase gave maltose as the smallest end product. The molecular weights and isoelectric points of the enzymes were for glucoamylase 70 000 – 76 000 and pH 4.0, and for α-amylase 54 000 – 57 000 and pH 3.4. An α-glucosidase (EC 3.2.1.20) with a molecular weight of 44 000 – 48 000 and an isoelectric point at pH 3.8 was eluted close to the α-amylase fraction on the DEAE-Trisacryl column.
Establishment of ciliate protozoa in the rumen of conventional and conventionalized lambs: influence of diet and management conditions
Authors: Fonty Gérard , Senaud Jean , Jouany Jean-Pierre , Gouet Philippe
Published: May 2010

The establishment of ciliate protozoa in the rumen was studied in conventional lambs reared under different conditions of management. The role of the microflora in the kinetics of this establishment was also investigated in conventionalized lambs. In lambs reared under farm conditions ciliate protozoa appeared in the following order: Entodinium (15-20 days), Polyplastron, Eudiplodinium, and Epidinium (20–25 days), and Isotricha (50 days). Entodinium was the most abundant (105–106 ciliates mL−1). During the 3rd month, ciliates disappeared spontaneously in about 60% of the lambs during a period that varied from 1 to 4 weeks. In lambs fed only cow's milk Entodinium spp. and Polyplastron multivesiculatum became established at low levels. The results obtained with the conventionalized lambs demonstrate that the establishment of the ciliates in the rumen requires that the bacterial flora be well established beforehand.
Metabolism of acetylene and acetaldehyde by Rhodococcus rhodochrous
Authors: Germon J. C. , Knowles R.
Published: May 2010

We studied the ability of a soil bacterium, identified as Rhodococcus rhodochrous, to grow on acetylene and to accumulate acetaldehyde. Its maximum growth rate on acetylene was obtained at about 30 °C (μ = 0.11 h−1) and was independent of the concentration of this gas in air from 0.14 to 16% (v/v). During growth, acetylene was quantitatively transformed to acetaldehyde, ethanol, acetate, CO2, and biomass in proportions which varied with culture age and temperature. Growth was completely inhibited by acetaldehyde at a concentration of 10 mM. The inhibitory effect was relieved by addition of acetate. Growth on ethanol up to 140 mM did not result in acetaldehyde accumulation. Acetylene consumption was constitutive with apparent Km and Vmax equal to 250 μM and 800 nmol∙min−1∙(mg protein)−1, respectively. In resting cell suspensions, acetylene consumption rates decreased more rapidly under air than under nitrogen. The inhibitory effect of acetaldehyde was enhanced in the presence of oxygen. Acetaldehyde accumulation in aerobic resting cell conditions did not exceed 10 mM (440 mg/L), but under anaerobic conditions it attained more than 70 mM (3.08 g/L).
Coaggregation among periodontal pathogens, emphasizing Bacteroides gingivalis –Actinomyces viscosus cohesion on a saliva-coated mineral surface
Authors: Ellen Richard P. , Schwarz-Faulkner Susanne , Grove David A.
Published: May 2010

Teeth offer nonshedding surfaces on which a wide range of bacterial species accumulate as thick, cohesive plaques. Intergeneric coaggregation mediated by specific recognition between surface "cohesins" is thought to contribute to both the cohesiveness of plaque and the sequence in which bacteria colonize the tooth surface. There is some evidence that Gram-positive species, like the efficient tooth colonizer Actinomyces viscosus, enhance subsequent tooth colonization by the more virulent periodontal pathogen Bacteroides gingivalis. To study their mechanism of cohesion, we have developed an in vitro assay that measures the sequential binding of tritium-labeled B. gingivalis to A. viscosus adsorbed to saliva-coated hydroxyapatite beads, mimicking teeth (actinobeads). The assay yields equilibrium and kinetics data amenable to statistical analysis. The presence of A. viscosus significantly increased the number of B. gingivalis cells bound. Inhibition studies were conducted to test the sensitivity of binding to heat; to various saccharides and sugar amines; to proteolytic treatment of Bacteroides; and to incorporation of various chaotropic agents, increased KCl, and saliva in the suspension buffer. Heating the Bacteroides cells but not the actinobeads diminished Bacteroides adherence. Proteolysis and various saccharides had little, if any, effect. Among chaotropic agents, NaSCN and LiCl reduced numbers of cells bound by 40%, but tetramethylurea had no effect. Increasing the ionic concentration of KCl reduced binding by 50 to 60%. Diluted saliva showed a concentration-dependent inhibition of B. gingivalis adherence to actinobeads. To begin examining B. gingivalis surface molecules significant to these reactions, lipopolysaccharide was extracted by the phenol–water method and analyzed by biochemical assays and polyacrylamide gel electrophoresis. Both homologous and heterologous lipopolysaccharides partially inhibited binding in a concentration-dependent manner, but actual binding of B. gingivalis lipopolysaccharide to A. viscosus cells could not be demonstrated. While heat, lipopolysaccharide, chaotropic agents, and concentrated KCl interfered to a limited extent with B. gingivalis – A. viscosus interactions on a surface mimicking teeth, the actual mechanism of cohesion is currently obscure and under investigation. The relevance of in vitro coaggregation experiments to colonization by periodontal and other pathogens was discussed.
Lactobacillus inhibitor production against Escherichia coli and coaggregation ability with uropathogens
Authors: Reid Gregor , McGroarty Jacqueline A. , Angotti Rosanne , Cook Roger L.
Published: May 2010

Previous investigations have shown that certain strains of lactobacilli can competitively exclude uropathogens from attaching to uroepithelial cells and from causing urinary tract infection in animals. The finding of an inhibitory effect produced by Lactobacillus casei ssp. rhamnosus GR-1 against the growth of uropathogens was investigated further using two Escherichia coli indicator strains Hu 734 and ATCC 25922. There were two phases to the inhibitor studies. The first one using an agar sandwich technique showed that the inhibitor activity was heat stable and inhibitory to the E. coli. The second phase showed that MRS broth provided optimum lactobacilli growth and inhibitor production. In addition, the inhibition was present under conditions buffering for acid and pH. The data indicated that the inhibitory effect was not due to bacteriophages or hydrogen peroxide. Strain GR-1 was found to coaggregate with E. coli ATCC 25922 in urine, a phenomenon that has not previously been reported for urogenital bacteria. An in vitro assay system was developed to study the coaggregation of various lactobacilli and uropathogens. The results demonstrated that highest coaggregation scores occurred after 4 h incubation at 37 °C with lactobacilli and two type-1 fimbriated E. coli strains. Of the nine lactobacilli strains tested, each was found to coaggregate with 2 or more of the 13 uropathogens. The dominance of inhibitor-producing lactobacilli on the urogenital epithelium and the ability of these organisms to interact closely with uropathogens would constitute an important host defense mechanism against infection.
Coccus-shaped Bacillus subtilis cells are inhibited at stage 0 of sporulation
Authors: Cheung Hon-Yeung , Vitković Ljubiša
Published: May 2010

RodA and rodB mutations cause rod-shaped Bacillus subtilis cells to become coccus-shaped when the growth temperature is increased from 30 to 45 °C. At 30 °C four rod strains sporulated as well as the genetically closely related rod+ strains. In contrast, at 45 °C the sporulation frequencies of rod strains decreased approximately 102- to 104-fold, while those of rod+ strains remained either unchanged or decreased only slightly. Temperature shift experiments and ultrastructural data indicated that coccus-shaped cells were unable to form prespore septa and were, therefore, inhibited at stage 0 of sporulation.
Biological control of damping-off of sugar-beet and cotton with Chaetomium globosum or a fluorescent Pseudomonas sp.
Authors: Walther D. , Gindrat D.
Published: May 2010

Seed treatment with ascospores of Chaetomium globosum reduced damping-off of sugar-beet caused by seed-borne Phoma betae and soil-borne Pythium ultimum or Rhizoctonia solani in growth chamber experiments. Seed treatment with a fluorescent Pseudomonas sp. controlled Ph. betae and P. ultimum but not R. solani. Coating cotton seeds with ascospores controlled P. ultimum and R. solani damping-off. In some experiments, biological seed treatments were equally or more effective than seed treatment with captan. However, greater variability in disease control occurred with the antagonists than with captan. Fifty percent of freshly harvested ascospores of C. globosum germinated in 8 h on water agar. When ascospores were stored under air-dried conditions for 3 days to 2.5 years, germination increased to > 90%. Under same storage conditions, survival of Pseudomonas sp. was detected after 4 months. Antagonistic activities observed in vitro were hyphal coiling of C. globosum on R. solani, and mycostasis was induced by C. globosum or Pseudomonas sp. on agar and soil. The presumed cause of mycostasis is the diffusible antifungal metabolites which may also be involved in the biological control of damping-off.
Nile red fluorescence demonstrates lipid in the envelope of vesicles from N2-fixing cultures of Frankia
Authors: Lamont Hayes C. , Silvester Warwick B. , Torrey John G.
Published: May 2010

Using Nile red as a fluorescent stain for lipid, we investigated the composition of the envelope of vesicles of Frankia strain HFPCcI3 from cultures induced in N-free medium at 1 and 20 kPa O2. Vesicles and nitrogenase activity appeared in the cultures at both pO2; on average, vesicles viewed by dark-field microscopy were larger and had thicker envelopes at 20 kPa O2 than at 1 kPa O2. Envelopes of Nile red-stained vesicles fluoresced red under incident green light. When samples of CcI3 were extracted through a lipid-solvent series and then stained, vesicles still fluoresced red but lacked a distinct peripheral fluorescent ring. These results are consistent with the view that the envelope of Frankia vesicles consists largely of lipid and serves as a barrier to diffusion of O2.
Bacterial tolerance of 100% dimethyl sulfoxide
Authors: Fedorka-Cray Paula J. , Cray Jr. William C. , Anderson Gary A. , Nickerson Kenneth W.
Published: May 2010

Viable bacteria were found in six bottles of dimethyl sulfoxide (DMSO) at a concentration of approximately one bacterium per 4.4 mL. The 18 bacterial isolates appeared to be tolerating the DMSO rather than metabolizing it. No fungi were detected. DMSO must be assumed to be nonsterile unless it has been previously sterilized.
Indoxyl-β-D-glucuronide, a novel chromogenic reagent for the specific detection and enumeration of Escherichia coli in environmental samples
Authors: Ley Arthur Newton , Bowers Raymond John , Wolfe Saul
Published: May 2010

About 97% of Escherichia coli strains produce β-glucuronidase, but almost all other Enterobacteriaceae lack this enzyme. A D-glucopyranosiduronic acid (glucuronide) possessing a readily detectable β-linked aglycone should, therefore, constitute a specific reagent for the detection of this organism. For this purpose, the title compound has been synthesized for the first time. The synthesis proceeds in eight steps from readily available D-glucuronolactone, anthranilic acid, and chloroacetic acid and can be carried out on a large scale. The compound has the predicted properties: when included in the standard membrane filter test for the analysis of water, indoxyl-β-D-glucuronide allows specific detection of E. coli through the formation of blue colonies that are the result of rapid conversion of the liberated aglycone to indigo. The recovery of E. coli is easily measured and almost quantitative.
Symbiotic gene probes hybridize to cryptic plasmids of indigenous Rhizobium meliloti
Authors: Barran L. R. , Bromfield E. S. P.
Published: May 2010

DNA probes for host specific nodulation (hsn) common nodulation (nod), exopolysaccharide (exo), nodule development (ndv) and nitrogenase structural (nif) genes were used to examine a collection of symbiotically effective, genotypically distinct isolates of indigenous Rhizobium meliloti for reiteration of symbiotic DNA sequences on cryptic plasmids. Nineteen of 30 isolates possessed at least one cryptic plasmid with reiterated DNA sequences, and of these isolates 15, 5, and 1 contained cryptic plasmids that hybridized to hsn, nif, and nod gene probes respectively; both hsn and nif probes hybridized to a single cryptic plasmid in each of two isolates. The exo and ndv probes did not hybridize to cryptic plasmids in any of the 30 isolates of R. meliloti.
Variation des stérols chez Kluyveromyces lactis et chez un mutant résistant par culture en présence de doses sublétales d'amphotéricine B
Authors: Hakkou A. , Coulon J. , Mpona-Minga M. , Bonaly R.
Published: May 2010

A mutant strain of Kluyveromyces lactis resistant to amphothericin B and weakly to nystatin has been isolated from subcultures of the wild strain grown in the presence of sublethal doses of amphothericin B. The mutant and the wild strain were equally sensitive to pimaricin, filipin, and candicidin. The efficacy of fungizone was very low. In comparison with the wild strain the level of sterols was two times lower in the resistant strain but the composition of these sterols was about the same in the two strains. The action of sublethal doses of amphothericin B on the composition of the sterols was the same in these two yeasts and brought a 40% decrease of the total sterol level and a modification in their distribution. This variation cannot fully explain the resistance of the yeast but it may be associated to other changes of the membranes. [Journal translation]
In vitro interactions between Blastomyces dermatitidis and other zoopathogenic fungi
Authors: Chaturvedi Vishnu P. , Randhawa Harbans S. , Chaturvedi Sudha , Khan Zia U.
Published: May 2010

The results of in vitro interactions between colonies of Blastomyces dermatitidis and six other zoopathogenic fungi are reported. The interactions were found to range from neutral with Histoplasma capsulatum and Candida albicans to strongly antagonistic with Microsporum gypseum, Pseudallescheria boydii, and Sporothrix schenckii, and including lysis by Cryptococcus neoformans. These observations suggest that interactions between zoopathogenic fungi may be one of the biotic factors likely to influence the occurrence of B. dermatitidis in natural systems.
Cultivar-specific growth promotion of spring wheat (Triticum aestivum L.) by coexistent Bacillus species
Authors: Chanway C. P. , Nelson L. M. , Holl F. B.
Published: May 2010

Seven bacterial strains belonging to the genus Bacillus were isolated from rhizosphere soil of spring wheat (Triticum aestivum L.) cv. Katepwa. The plants from which the microorganisms were isolated were collected from a field that had been continuously cropped with spring wheat for the past 27 years. Cultivar Katepwa had been grown for the last 5 years whereas the closely related cv. Neepawa had been cultivated for the 12 previous years. When tested as single strain inoculum in a sterilized sand and Turface (montmorillonite clay) mix, six of seven isolates promoted root growth of cv. Katepwa spring wheat (p < 0.05), but none promoted that of cv. Neepawa or of the more distant genetic relative cv. HY320. Shoot height was also increased in cv. Katepwa (p < 0.1), but shoot weight of all three cultivars was unaffected by inoculation. Consequently, the root to shoot weight ratio of cv. Katepwa was also greater because of bacterization. These results indicate that beneficial bacteria may be isolated by employing a natural plant cultivar enrichment technique.
Insights into the cell envelope of Paracoccus denitrificans, a member of the α-subdivision of purple bacteria, through studies of its lysozyme susceptibility
Authors: Wee Sechan , Wilkinson Brian J.
Published: May 2010

Exponential-phase Paracoccus denitrificans cells grown in a complex medium are known to be lysozyme susceptible without pretreatment with outer membrane perturbing agents. Stationary-phase cells are more lysozyme resistant, but simple washing of these cells with moderate concentrations (154 mM) of monovalent inorganic cations (NaCl, KCl, or LiCl), or 100 mM Tris(hydroxymethyl)aminomethane-HCl (Tris–HCl) rendered them lysozyme susceptible. Subsequent washing with divalent cations reversed the enhanced lysozyme susceptibility. Cells grown in succinate–salts medium were not rendered lysozyme susceptible by NaCl washing. Supplementation of complex medium with various salts used in succinate–salts medium showed that Mg2+ and Ca2+ supplementation resulted in increased growth yields and in cells that were not rendered lysozyme susceptible by NaCl washing. Measurement of the Mg2+ and Ca2+ content of peptone and yeast extract revealed Mg2+ and Ca2+ were present at 50–80 and 15–30 μM concentrations, respectively, in complex medium. Omission of Ca2+ or reduction of Mg2+ from 810 to 50 μM in succinate–salts medium resulted in cells that became lysozyme susceptible after NaCl washing. Incubation of cells grown in succinate–salts medium with Tris–HCl – ethylenediaminetetraacetate – sucrose caused them to become lysozyme susceptible, indicating that their lack of lysozyme susceptibility was due to a more effective outer membrane barrier than that of complex medium grown cells, rather than a lysozyme-resistant peptidoglycan. The protein composition of outer membranes from complex and complex + Mg2+ + Ca2+ grown cells was similar, suggesting that divalent cations did not have a major influence on protein production related to outer membrane stability. The results indicate that certain complex bacteriological media may be deficient in divalent cations for maximum cell envelope stability and growth yield. This might be particularly significant for soil bacteria such as P. denitrificans, which may have evolved to have outer membranes more dependent on divalent cations for structural integrity than animal host adapted bacteria such as enteric bacteria. The results also draw attention to NaCl as an outer membrane perturbing agent.
Mineralization of monosubstituted aromatic compounds in unsaturated and saturated subsurface soils
Authors: Federle Thomas W.
Published: May 2010

The mineralization of benzoic acid, phenol, and benzylamine was determined as a function of depth in two 20-m sandy soil profiles, one of which was adjacent to a leach field receiving wastewater from a laundromat. Soil samples were collected aseptically, adjusted to 20–25% water content and amended with a trace level (50 ng/g soil) of the 14C-ring-labeled compounds. Evolution of CO2 was followed with time. First-order rate constants and the extents of mineralization were estimated from the resulting data by nonlinear regression. All three compounds were mineralized in every sample examined without a lag period. In general, phenol was mineralized more rapidly than benzoic acid, which was more rapidly mineralized than benzylamine. Benzylamine had the highest sorption coefficient; phenol had the lowest. Average half-life was 0.56 days for phenol, 0.84 days for benzoic acid, and 1.31 days for benzylamine. Mineralization rates did not correlate with bacterial number, fluorescein diacetate hydrolysis rate, or any soil characteristic. The ultimate percentage of all three compounds mineralized was lowest in the upper 3 m of both soil profiles. The total amounts of phenol and benzoic acid mineralized negatively correlated with cation-exchange capacity and silt content. Statistical analysis (2-level nested ANOVA) revealed that only the rate of phenol mineralization varied significantly as a function of soil profile, but rates for all three compounds varied significantly as a function of depth within a profile.