bluuebunny/crossref_metadata_2025 huggingface dataset:
Pectin decomposition and associated nitrogen fixation by mixed cultures of Azospirillum and Bacillus species
Authors: Khammas K. M. , Kaiser P.
Published: May 2010

Cocultures of different Azospirillum species with Bacillus polymyxa or Bacillus subtilis allow the efficient utilization of pectin as carbon and energy sources for nitrogen fixation. The nitrogenase activity obtained with cocultures was as high as 30–80 nmol C2H4 h−1 mL−1, a much higher value than that obtained with pure cultures of either Azospirillum (up to 13 nmol C2H4 h−1 mL−1) or B. polymyxa (up to 2 nmol C2H4 h−1 mL−1) alone. To establish to what extent each partner contributed to nitrogenase activity, acetylene reduction was assayed as a function of time and it was also measured on Azospirillum cultivated in the cultures filtrates of the Bacillus. The results suggested that the nitrogenase activity was mostly produced by Azospirillum. The nitrogenase activity occurred at the expense of the degradation and fermentation products of the pectin. The new pectinolytic species, Azospirillum irakense, utilized both degradation and fermentation products of pectin, whereas the nonpectinolytic strains (Azospirillum brasilense, Azospirillum lipoferum, Azospirillum amazonense) utilized only the fermentation products of pectin, including acetic and succinic acids. These cocultures can be considered as metabolic associations, where the Bacillus produces degradation and fermentation products of pectin, which can be used by Azospirillum species. Key words: cocultures, nitrogen fixation, pectin degradation, Azospirillum, Bacillus, metabolic association.
Decolorization of the polymeric dye Poly R-478 by wood-inhabiting fungi
Authors: Freitag Michael , Morrell Jeffrey J.
Published: May 2010

Decolorization of the polymeric dye Poly R-478, an indicator of phenoloxidase activity, was examined as a potential method for separating white- and brown-rot fungi taxonomically and for screening for ligninolytic capability. In plate tests, decolorization proceeded more slowly than radial growth, which indicates that decolorizing enzymes are associated with growing and developed hyphae. Strains of the same species differed in decolorizing ability, but as expected, there were no differences between monokaryons and dikaryons of the same species. Raising the temperature from 20 to 40 °C usually increased the decolorization rate, but less than it increased the growth rate. Most brown-rot, soft-rot, or xylophilous fungi did not decolorize the dye, but 16 of 47 brown-rot fungi weakly decolorized the dye at 20 or 30 °C. Aspergillus niger and one Henningsomyces sp. also decolorized the dye. Studies with the brown-rot fungi Gloeophyllum trabeum and Fomitopsis pinicola on liquid media revealed no lignin peroxidase or manganese-dependent peroxidase activity, although nonspecific peroxidase activity was detected. Poly R-478 proved useful for selecting most white-rot fungi; however, some brown-rot fungi also reacted positively in these tests. Further studies on the pathways and mechanisms of dye decolorization by brown-rot fungi are recommended. Key words: brown rot, white rot, polymeric dyes, lignin peroxidase, manganese peroxidase.
Identification of Salmonella typhimurium invasiveness loci
Authors: Betts Janice , Finlay B. Brett
Published: May 2010

Salmonella typhimurium is capable of entering into (invading) nonphagocytic host cells. To systematically identify the bacterial genes necessary for this process, 15 000 Tn10dCm random transposon mutants of S. typhimurium were individually screened for invasiveness, using the human colonic epithelial Caco-2 cell line. Four hundred and eighty-eight mutants had decreased levels of invasiveness; most were nonmotile. However, five mutants, representing four loci, were completely motile. Further characterization of these five mutants showed that they were also unable to enter the dog kidney epithelial cell line MDCK and the mouse macrophage line J774.A1. In contrast to the parental strain, they were unable to disrupt the transepithelial resistance of polarized epithelial monolayers, nor were they able to penetrate across these epithelial barriers. Three of the four classes of mutants remained virulent in mice. The results confirm several aspects of S. typhimurium invasiveness: (i) intact motility enhances invasiveness of cultured cells; (ii) S. typhimurium invasiveness is multifactorial, and at least six distinct genetic loci are involved; and (iii) invasion loci involved in uptake into epithelial cells are also needed for uptake into cultured phagocytic cells. The results also emphasize that decreased levels of invasiveness eliminate bacterial penetration of polarized epithelial barriers and invasiveness loci mutants are not necessarily avirulent. Key words: Salmonella typhimurium, invasion, penetration, virulence, pathogenesis, invasiveness.
Identification of a DNA region required for growth of Pseudomonas syringae pv. tomato on tomato plants
Authors: Jackson Dennis P. , Gray Douglas A. , Morris Vincent L. , Cuppels Diane A.
Published: May 2010

The prototrophic Pseudomonas syringae pv. tomato mutant DC3481, which is the result of a single-site Tn5 insertion, cannot grow and cause disease on tomato plants and cannot use the major organic acids of tomato, i.e., citric, malic, succinic, and tartaric acids, as sole carbon sources. Although nonpathogenic, strain DC3481 can still induce a hypersensitive reaction in nonhost plants. We have identified a 30-kb fragment of P. syringae pv. tomato wild-type DNA that can complement this mutant. EcoRI fragments from this region were subcloned and individually subjected to functional complementation analysis. The 3.8-kb fragment, which was the site of the Tn5 insertion, restored pathogenicity and the ability to use all the major organic acids of tomato as carbon sources. It shares sequence homology with several P. syringae pathovars but not other bacterial tomato pathogens. Our results indicate that sequences on the 3.8-kb EcoRI fragment are required for both the ability to grow on tomato leaves (and thus cause disease) and the utilization of carboxylic acids common to tomato. The 3.8-kb fragment may contain a sequence (or sequences) that regulates both traits. Key words: Pseudomonas syringae pv. tomato, phytopathogenicity, Tn5, tricarboxylic acid metabolism, bacterial speck, growth in planta.
Immuno-scanning electron microscopic localization of extracellular wood-degrading enzymes within the fibrillar sheath of the brown-rot fungus Postia placenta
Authors: Green III Frederick , Clausen Carol A. , Larsen Michael J. , Highley Terry L.
Published: May 2010

Extracellular wood-degrading enzymes of the brown-rot fungus Postia placenta were localized using colloidal gold labeled monoclonal antibodies to the β-1,4-xylanase (32 to 36 kDa) fraction of P. placenta. Postia placenta was grown from agar onto glass cover slips, immunolabeled with or without prior fixation, and examined by scanning electron microscopy. Enzymes were localized on the hyphal surface and on the clumped fibrillar elements mycofibrils of the hyphal sheath following fixation with glutaraldehyde. If fixation was omitted, labeling was diffuse and not localized on individual or clumped mycofibrils. We conclude that extracellular decay enzymes are weakly bound (noncovalently) to, but not identical with, the linear mycofibrillar elements of the hyphal sheath. The linear structural elements of the hyphal sheath may play an important role in transport and presentation of wood-degrading enzymes during the decay process. Key words: brown-rot fungi, enzymes, mycofibrils, hyphal sheath, immunolabeling, monoclonal antibodies, colloidal gold, scanning electron microscopy.
The role of extracellular polysaccharide in cell viability and nitrogenase activity of Beijerinckia derxii
Authors: Barbosa H. R. , Alterthum F.
Published: May 2010

Cells of Beijerinckia derxii grown on NH4+ or N2 as the nitrogen source were treated to remove their extracellular polysaccharide layer without loss of viability. An adequate method for extracellular polysaccharide extraction was established. After extracellular polysaccharide removal N2-grown cells showed reduced nitrogenase activity, and when stirred for 90 min at 200 rpm, suffered a total loss of viability. In contrast, NH4+-grown cells were not affected when submitted to the same conditions. However, these cells showed a high sensitivity to saline solution. Key words: extracellular polysaccharide, nitrogenase, Beijerinckia derxii, exopolysaccharide.
Incorporation of cysteine by Borrelia burgdorferi and Borrelia hermsii
Authors: Sambri Vittorio , Cevenini Roberto
Published: May 2010

The growth rate of Borrelia burgdorferi and Borrelia hermsii in BSK II medium prepared with cysteine-free or cysteine-containing (0.185–5.92 mM) CMRL 1066 medium was studied. In media with cysteine-free CMRL 1066, growth of borreliae was detectable, although it was reduced by approximately 80%. Bacterial growth was maximal when the concentration of cysteine in CMRL 1066 reached 1.48 mM, which represents the standard cysteine concentrations of the medium; higher concentrations inhibited the growth of borreliae. Cysteine incorporation, measured by the uptake of radiolabeled cysteine, showed that cysteine enters B. burgdorferi and B. hermsii cells by passive diffusion. Labeling studies of borreliae with [35S]cysteine indicated that B. burgdorferi has several cysteine-containing proteins, including ones at 22, 30 (OspA), and 34 kDa (OspB), whereas B. hermsii showed only two [35S]cysteine-incorporating proteins, at 22 and 24 kDa, which were exposed onto the outer cell surface. In addition, most of the cysteine-incorporating proteins could be biosynthetically radiolabeled when bacterial cells were grown in vitro with [3H]palmitate, and the differences in cysteine incorporation observed between B. burgdorferi and B. hermsii were found to be correlated with differences in lipoproteins. Key words: Borrelia burgdorferi, Borrelia hermsii, cysteine, cysteine uptake, lipoproteins, outer surface proteins.
Structural and physicochemical surface properties of Serratia marcescens strains
Authors: Mei Henny C. Van der , Cowan Marjorie M. , Genet Michel J. , Rouxhet Paul G. , Busscher Henk J.
Published: May 2010

Serratia marcescens is an important pathogen with noteworthy hydrophobicity characteristics as assessed by microbial adhesion to hydrocarbons. However, the present knowledge on the surface characteristics of S. marcescens strains does not include physicochemical properties relevant for adhesion such as surface free energy and zeta potential. Also, little attention has been paid hitherto to the structural features and chemical composition of the cell surface. Therefore, as a primary aim of this paper, we characterized S. marcescens strains by means of contact angle and zeta potential measurements, X-ray photoelectron spectroscopy, and infrared spectroscopy. In addition, transmission electron microscopy on negatively stained (methylamine tungstate) and ruthenium red stained cells was employed to study structural features on the cell surface. Furthermore, as a secondary aim of this paper, the power of the various techniques to discriminate between strains was evaluated. Negative staining showed that S. marcescens RZ almost completely lost its surface fibrils upon increasing the growth temperature from 30 to 37 °C. This loss of surface fibrils was accompanied by a decrease in hydrophobicity, as measured by water contact angles on bacterial lawns. No significant differences in hexadecane contact angles were observed. Zeta potentials were only different for S. marcescens 3164, showing a considerably higher isoelectric point (IEP = 3.9) than the other strains involved (IEP about 2.5). X-ray photoelectron spectroscopy yielded differences in O/C, N/C, and P/C surface concentration ratios, which related with the IEPs of the strains, despite the fact that X-ray photoelectron spectroscopy is done on fully dehydrated cells, whereas zeta potentials are measured on cells in their physiological state. Infrared spectroscopy was not sufficiently surface sensitive to discriminate between these strains. N/C surface concentration ratios by X-ray photoelectron spectroscopy, which probes approximately 5 nm deep from the surface, were slightly higher for the pigmented, prodigiosin-containing strains RZ30 and 3164, although the presence of prodigiosin did not influence the cell surface hydrophobicity. Thus the prodigiosin is probably confined in deeper layers than probed by contact angles (approximately 0.3–0.5 nm). Key words: Serratia marcescens, fibrils, surface properties, hydrophobicity, zeta potential.
Characterization of monoclonal antibodies to the outer membrane protein (OmpD) of Salmonella typhimurium
Authors: Pai Suresh R. , Upshaw Yvonne , Singh Shiva P.
Published: May 2010

A panel of monoclonal antibodies, seven against the trimeric and seven against the monomeric forms to outer membrane protein D (OmpD) of Salmonella typhimurium were produced. The specificities of these monoclonal antibodies for the porin proteins of S. typhimurium and their cross-reactions with Salmonella porins OmpC and OmpF were determined by Western immunoblotting and enzyme-linked immunosorbent assay. We observed that OmpD shared more epitopes and had greater structural similarity with OmpC than with OmpF. Key words: Salmonella typhimurium, outer membrane protein, monoclonal antibody, trimeric, monomeric.
Isolation of Clostridium acetobutylicum strains and the preliminary investigation of the hemicellulolytic activities of isolate 3BYR
Authors: Trudeau D. G. , Bernier R. L. , Gannon D. J. , Forsberg C. W.
Published: May 2010

Thirty-nine xylanolytic bacteria tentatively identified as Clostridia were isolated from a selection of agricultural and forest soil samples, and water–sediment–fibre samples from acidic springs in the Yellowstone National Park. Screening for xylan hydrolysis was performed using an enriched agar medium at pH 5.5 with Remazol–xylan as the indicator, with or without an initial enrichment using xylan as the major carbon source. From 13 of the most highly xylanolytic strains, 9 were tentatively identified as Clostridium acetobutylicum, 2 as Clostridium butyricum, and 2 as Clostridium beijerinckii. The C. acetobutylicum isolate 3BYR utilized 80% of oat spelt xylan as a carbon source during growth. The bacterium exhibited very high extracellular xylanase and xylosidase activities and, as well, α-L-arabinofuranosidase and α-glucuronidase activities. Glucuronidase activity was documented by the release of 4-O-methyl-α-D-glucuronic acid from birchwood xylan. The results of this work indicate the ubiquity of xylanolytic Clostridia, and that the previously unreported activity, α-glucuronidase, has been demonstrated in C. acetobutylicum. Key words: α-glucuronidase, xylanase, Clostridium acetobutylicum, xylan.
Detection of equine herpesvirus and differentiation of equine herpesvirus type 1 from type 4 by the polymerase chain reaction
Authors: Wagner Wania N. , Bogdan Jaret , Haines Deborah , Townsend Hugh G. G. , Misra Vikram
Published: May 2010

Although both equine herpesvirus type 1 (EHV-1) and equine herpesvirus type 4 (EHV-4) can be associated with respiratory disease, epizootics caused by EHV-1 are much more serious because the virus can cause abortions and paralysis. It is, therefore, important to identify the type of EHV involved in an outbreak by a test that is quick, sensitive, and reliable. We have adapted the polymerase chain reaction (PCR) to detect and distinguish between EHV-1 and EHV-4 in the same reaction. Primers for PCR were designed from the sequences of the glycoprotein B genes of EHV-1 and EHV-4. The PCR products derived from EHV-1 and EHV-4 were 135 and 326 base pairs, respectively, and could be readily separated by electrophoresis. The identity of the PCR products was confirmed by determining their nucleotide sequence, which agreed with the published sequence of the gB genes. The test could be performed directly on virus pelleted from small volumes (300 μL) of medium in which nasal swabs were transported and did not rely on the presence of infectious virus. The PCR was unaffected by conditions that reduced the infectivity of a virus preparation by 99%. The PCR detected EHV-4 in 5 of 10 nasal mucous samples taken from an outbreak of respiratory disease in race horses. Virus isolation in indicator cells was successful in detecting virus in four of the five samples positive by PCR. Key words: equine herpesvirus types 1 and 4, polymerase chain reaction, equine respiratory disease.
Effect of temperature on sclerotium induction in Paxillus involutus
Authors: Moore A. E. P. , Peterson R. L.
Published: May 2010

Paxillus involutus (Batsch.: Fr.) Fr., an ectomycorrhizal fungus, is capable of forming sclerotia, resistant vegetative propagules. Sclerotia were induced in vitro on agar-solidified modified Melin Norkrans medium by exposure of the mycelium to temperatures between 6 and 14 °C. The number and size of sclerotia varied greatly with temperature. Mycelium exposed to either 6 or 8 °C produced many smaller sclerotia (less than 1.0 mm in diameter) lacking droplets of exudate, whereas mycelium exposed to temperatures between 10 and 14 °C formed fewer, larger sclerotia (1.0 mm or more in diameter) with abundant exudate. Sclerotia were not induced from mycelium grown in liquid medium at 10 or 25 °C or from mycelium on agar-solidified medium maintained at 25 °C under a variety of conditions, including changes in medium composition and volume. Key words: sclerotia, Paxillus involutus, temperature, ectomycorrhiza, in vitro.
A phosphatidylinositol-specific phospholipase C from Cytophaga: production, purification, and properties
Authors: Artursson Elisabet , Puu Gertrud
Published: May 2010

An extracellular phosphatidylinositol-specific phospholipase C was isolated from a Cytophaga species. The growing conditions were optimized for the production of the enzyme and a purification scheme was developed. The enzyme is small and is not dependent on metal ions for activity. It has a rather low apparent Michaelis constant, 0.2 mM, for phosphatidylinositol and is not stimulated by deoxycholate or extra phospholipid. It releases alkaline phosphatase from rat kidney and cholinesterase from plaice muscle tissue but not acetylcholinesterase from intact rat or pig erythrocytes. Key words: phosphatidylinositol specific, phospholipase, Cytophaga.
Coordinate increase in activity of proteinase subunits of the 1300-kDa megaproteinase of Frankia strain BR: role of carbon source depletion and extracellular metabolites
Authors: Benoist Patrick , Müller Angeles , Diem Hoang Gia
Published: May 2010

We have recently described the presence of a high molecular mass multicatalytic proteinase complex (megaproteinase; 28 S, 1300 kDa) in Frankia strain BR. The complex dissociates into 11 low molecular mass proteinase subunits (40–19 kDa) when subjected to sodium dodecyl sulfate – gelatin – polyacrylamide gel electrophoresis. We show here that the activity of these proteinase subunits strongly increased after cessation of growth in stirred BAP-PCM mineral medium. Subsequent addition of either BAP medium components or sodium propionate alone, as carbon source, to a Frankia culture at the end of the exponential growth phase was found to prolong growth for 1 additional day, and to delay the increase in activity of the proteinase subunits for 3 days after cessation of growth. Addition of ammonium chloride alone, as nitrogen source, had no effect. On the other hand, when Frankia cells in the late exponential phase (3 days) were resuspended in a culture filtrate recovered from a 5-day-old culture and supplemented with BAP-PCM medium components, the biomass yield decreased to about 50%. Also, the activity of the proteinase subunits increased as soon as growth ceased. The ability of this culture filtrate to inhibit growth and stimulate the activity of proteinase subunits was partially lost by heating or was largely removed by DEAE-cellulose treatment. Thus, our findings indicate an extracellular control of Frankia megaproteinase activity, suggesting that carbon source depletion and probably accumulation of heat-sensitive growth-inhibiting metabolites in the medium are determining factors.Key words: Frankia, proteinases, megaproteinase, proteasome, proteolysis, autolysis.
Renodulation and nitrogen fixing potential of Acacia nilotica inoculated with Rhizobium isolates
Authors: Lal Banwari , Khanna Sunil
Published: May 2010

Renodulation and nitrogen fixation potential of indigenous and exotic isolates of Rhizobium were studied in a field experiment with Acacia nilotica from July 1990 to June 1991. The inoculum isolates belonged to different serotypes and did not show cross-reaction with the native population of Rhizobium. Nitrogenase activity of root nodules observed at 4-month intervals covering three seasons snowed a decline during winter months, which corresponded with the senescence of the nodules. Maximal renodulation as checked by serotyping and antibiotic resistance pattern was observed with isolate AB 3 followed by AD 4 and USDA 3325. The highest nitrogenase activity was exhibited in plants inoculated with AD 4 at 12 months. Plants inoculated with Rhizobium isolate USDA 3325 showed the highest increase in dry-matter yield at 12 months. Except for AB 3, dual inoculation with Rhizobium isolates and Glomus fasciculatum did not enhance dry matter production as compared with uninoculated controls or single inoculation of either Rhizobium isolate or G. fasciculatum.Key words: Rhizobium, Acacia nilotica, nitrogenase activity, renodulation.
Construction and preliminary characterization of a nondefective herpes simplex virus recombinant bearing the genome of human papillomavirus type 16
Authors: Salloukh Hashem , Lavery Carol , Smiley James R. , Rawls William E.
Published: May 2010

Studies of the molecular biology of human papillomavirus type 16 have been limited by the lack of a tissue culture system that is fully permissive for virus replication; as a result, high-titre stocks of infectious virus are not readily available. Therefore, studies of viral gene expression have relied on analysis of transformed or tumour cell lines harbouring latent or integrated viral genomes, or on the behaviour of transfected reporter gene constructs. To provide a method of efficiently delivering papillomavirus information into the nuclei of mammalian cells, we constructed a herpes simplex virus type 1 recombinant bearing the entire human papillomavirus type 16 genome. The resulting recombinant was capable of lytic replication and induced the accumulation of papillomavirus mRNAs initiated from the p97 early promoter during infection of Vero cells. This and other herpes simplex – papillomavirus recombinants should facilitate molecular analysis of the life cycle of human papillomavirus type 16.Key words: herpes simplex virus, vectors, human papillomavirus, transcription.
1, 3, 5-Trihydroxybenzene biodegradation by Rhodococcus sp. BPG-8
Authors: Armstrong S. , Patel T. R.
Published: May 2010

The metabolic pathway used by Rhodococcus sp. BPG-8 isolated from oil-rich soil in Newfoundland for the degradation of 1, 3, 5-trihydroxybenzene (phloroglucinol) as a sole source of carbon and energy was determined. Culture filtrate of cells grown on phloroglucinol detected 1, 2, 3, 5-tetrahydroxybenzene when extracted and analyzed using gas chromatography - mass spectrometry, thin-layer chromatography, and ultraviolet spectrophotometry. Nonaromatics were either derivatized with 2, 4-dinitrophenylhydrazine and compared against authentic standards by the above methods, or detected by chemical and enzymatic methods. Extracts of cells grown on phloroglucinol contained phloroglucinol hydroxylase activity, and a dioxygenase that carried out ortho-cleavage of 1, 2, 3, 5-tetrahydroxybenzene. The extract also showed inducible activity for further metabolism of acetopyruvate leading to accumulation of formate in the supernatant. A tentative degradative pathway for phloroglucinol by Rhodococcus sp. BPG—8 is proposed.Key words: phloroglucinol, 1, 2, 3, 5-tetrahydroxybenzene, degradation, Rhodococcus.
Levels of small molecules in dormant spores of Sporosarcina species and comparison with levels in spores of Bacillus and Clostridium species
Authors: Loshon Charles A. , Setlow Peter
Published: May 2010

Dormant spores of Sporosarcina halophila and Sporosarcina ureae contained no detectable ATP, significant levels of ADP, even higher levels of AMP, and a large pool of 3-phosphoglyceric acid, similar to what is found in dormant spores of Bacillus and Clostridium species. Sporosarcina halophila and S. ureae spores also contained significant pools of free amino acids, in particular glutamic acid, as in the case with spores of Bacillus but not Clostridium species. Levels of monovalent and divalent inorganic cations were comparable in spores of Sporosarcina, Clostridium, and Bacillus species, and cation levels in spores of the slight halophile S. halophila were similar to those in S. ureae spores. These data suggest that levels of small molecules are generally similar in spores of all Gram-positive organisms, and further suggest that these levels reflect fundamental and conserved features of the sporulation process and dormant spores in these organisms. The data are also consistent with the proposed close evolutionary relationship between Bacillus and Sporosarcina species.Key words: Bacillus, Clostridium, small molecules, spores, Sporosarcina.
Functional analysis of seven ribosomal systems from extremely halophilic archaea
Authors: Sanz José L. , Marín Irma , Ureña Dionisio , Amils Ricardo
Published: May 2010

The sensitivity of seven extremely halophilic archaeal protein synthesis systems to 42 inhibitors with different domain (kingdom), functional, and structural specificity has been studied. The results obtained underline the functional variability of archaeal ribosomes when compared with bacterial and eukaryotic reference systems. Halophilic ribosomes are sensitive to some of the specific inhibitors of bacteria, such as thiostrepton, carbomycin A, and griseoviridin, or of eukaryotes, such as anisomycin and bruceantin, and extremely sensitive to some of the universal inhibitors, such as puromycin and sparsomycin. Suitable control experiments allow us to postulate that some negative inhibitory results may be caused by competition between positively charged antibiotics and the high ionic conditions required for halophilic protein synthesis.Key words: protein synthesis inhibitors, halophilic archaea, ribosomes.
Cereal grain digestion by selected strains of ruminal fungi
Authors: McAllister T. A. , Dong Y. , Yanke L. J. , Bae H. D. , Cheng K.-J. , Costerton J. W.
Published: May 2010

The ruminal fungi Orpinomyces joyonii strain 19-2, Neocallimastix patriciarum strain 27, and Piromyces communis strain 22 were examined for their ability to digest cereal starch. All strains digested corn starch more readily than barley or wheat starch. Orpinomyces joyonii 19-2 exhibited the greatest propensity to digest starch in wheat and barley, whereas the digestion of these starches by N. patriciarum 27 and P. communis 22 was limited. Media ammonia concentrations were lower when fungal growth was evident, suggesting that all strains assimilate ammonia. Fungi formed extensive rhizoidal systems on the endosperm of corn, but O. joyonii 19-2 was the only strain to form such systems on the endosperm of wheat and barley. All strains penetrated the protein matrix of corn but did not penetrate starch granules. Starch granules from all three cereals were pitted, evidence of extensive digestion by extracellular amylases produced by O. joyonii 19-2. Similar pitting was observed on the surface of corn starch granules digested by N. patriciarum 27 and P. communis 22, but not on wheat and barley starch granules. The ability of ruminal fungi to digest cereal grains depends on both the strain of fungus and the type of grain. The extent to which fungi digest cereal grain in the rumen remains to be determined.Key words: ruminal fungi, cereal grain, starch digestion, ruminant.
Occurrence of Actinomadura phage in organic mulches used for avocado plantations in Western Australia
Authors: Kurtböke D. I. , Wilson C. R. , Sivasithamparam K.
Published: May 2010

Phage infecting Actinomadura verrucosospora, Actinomadura pusilla, and Nocardiopsis flava were isolated from mulches applied to avocado trees at the University of Western Australia experimental plots. The physiochemical properties, plaque morphology, host range, and particle morphology of the phage isolated are described. Taxonomic implications of the reactions of some cell wall chemotype III actinomycetes to Actinomadura phage are also discussed.Key words: Actinomadura phage.
Pulsed-field gel electrophoresis applied for comparing Listeria monocytogenes strains involved in outbreaks
Authors: Buchrieser C. , Brosch R. , Catimel B. , Rocourt J.
Published: May 2010

Recent food-borne outbreaks of human listeriosis as well as numerous sporadic cases have been mainly caused by Listeria monocytogenes serovar 4b strains. Thus, it was of interest to find out whether a certain clone or a certain few clones were responsible for these cases and especially for outbreaks., We used pulsed-field gel electrophoresis of large chromosomal DNA restriction fragments generated by ApaI, SmaI, or NotI to analyse 75 L. monocytogenes strains isolated during six major and eight smaller recent listeriosis outbreaks. These strains could be divided into 20 different genomic varieties. Thirteen of 14 strains isolated during major epidemics in Switzerland (1983–1987), the United States (California, 1985) and Denmark (1985–1987) demonstrated indistinguishable DNA restriction patterns. In contrast, strains responsible for the outbreaks in Canada (Nova Scotia, 1981), the United States (Massachusetts, 1983), France (Anjou, 1975–1976), New Zealand (1969), and Austria (1986) and some smaller outbreaks in France (1987, 1988, 1989) were each characterized by particular combinations of DNA restriction patterns. Seventy-seven percent of the tested strains could be classified into the previously described ApaI group A (Brosch et al. 1991), demonstrating a very close genomic relatedness. Because 49% of the epidemic strains selected for this study belonged to phagovar 2389/2425/3274/2671/47/108/340 or 2389/47/108/340, fifty-six additional strains of these phagovars, isolated from various origins, were also typed to determine whether differences in DNA restriction profiles between epidemic and randomly selected strains of the same phagovars could be pointed out. Variations in DNA patterns appeared more frequently within randomly selected strains than within epidemic strains.Key words: Listeria monocytogenes, listeriosis, typing, pulsed-field gel electrophoresis, epidemic.
Superoxide dismutase activity in root-colonizing pseudomonads
Authors: Katsuwon J. , Zdor R. , Anderson A. J.
Published: May 2010

Several saprophytic fluorescent pseudomonads that are aggressive root colonizers express similar specific activities of superoxide dismutase during growth in liquid culture. The pseudomonads have the potential to produce hydrogen peroxide sensitive and hydrogen peroxide insensitive isoforms of superoxide dismutase with distinct mobilities in nondenaturing polyacrylamide gel electrophoresis. Synthesis of the hydrogen peroxide insensitive form is enhanced by limited iron availability, by exposure to Mn2+, and to a lesser extent by external sources of superoxide anion. Unlike Pseudomonas aeruginosa, a root-colonizing strain of Pseudomonas putida did not show regulation of isoform pattern by phosphate availability. A plasmid potentially encoding the pseudomonad hydrogen peroxide sensitive form complemented the superoxide dismutase deficiency in a mutant of Escherichia coli lacking expression of both Fe and Mn genes. Contact between the plant root and pseudomonad or E. coli cells that lack or express superoxide dismutase did not influence superoxide anion production from root surface enzymes. The pseudomonad and the superoxide dismutase deficient and producing E. coli strains survived exposure to the root equally well. Only the hydrogen peroxide sensitive isoform of superoxide dismutase was detected in P. putida cells associated with bean root surfaces.Key words: pseudomonads, activated oxygen, root surface colonization.
Kasugamycin inhibition of nonsense suppression by thymine-requiring strains of Escherichia coli K12
Authors: Tiganos E. , Herrington M. B.
Published: May 2010

Thymine-requiring strains of Escherichia coli suppress nonsense and frame-shift mutations. This appears to occur during translation, suggesting that the lack of activity of an enzyme thymidylate synthase, required for the synthesis of a DNA precursor, alters the fidelity of translation. The aminoglycoside antibiotic kasugamycin, which enhances translational accuracy in vitro, prevents thymine-requiring cells from suppressing. The inhibition of suppression by kasugamycin is not prevented by the introduction of two different kasugamycin-resistance mutations, although the dose required for inhibition increases. These observations support the conclusion that suppression occurs during translation.Key words: suppression, kasugamycin, translation, thymine-requiring.
The second messenger cyclic 3′, 5′ -adenosine monophosphate in pathogenic microorganisms with special reference to protozoa
Authors: Castro Solange L. De , Luz Mauricio R. M. P.
Published: May 2010

There is a growing body of information on signal transduction components in microorganisms. Elements of the cyclic 3′, 5′-adenosine monophosphate signaling system and molecules similar to hormones and receptors have been identified in the majority of prokaryotes and unicellular eukaryotes that have been studied. The presence of ligand- and receptor-like molecules in parasitic microorganisms raises the possibility that these molecules may interact with host communication systems. Adrenergic control of proliferation, differentiation, and infectivity has been described in the flagellate protozoan Trypanosoma cruzi, the etiological agent of Chagas' disease. Interactions between host and parasitic systems could also be antibody mediated, with antigenic cross-reactivity between components of their cAMP-dependent systems. In this review, we discuss these possibilities and summarize the existing data in this area.Key words: cAMP, pathogenic microorganisms, Trypanosoma cruzi, signaling systems.
Mutations in the fifth-position glutamate in Pseudomonas aeruginosa pilin affect the transmethylation of the N-terminal phenylalanine
Authors: Macdonald D. L. , Pasloske B. L. , Paranchych W.
Published: May 2010

The pili of Pseudomonas aeruginosa are composed of 15-kDa pilin monomers that are synthesized in the cytoplasm and assembled in the membrane. Processing occurs between the synthesis and assembly steps. The propilin is cleaved by a unique leader peptidase encoded by pilD, which is adjacent to the pilin structural gene pilA. This generates an N-terminal phenylalanine that is subsequently methylated by an as yet uncharacterized transmethylase. The pili of P. aeruginosa belong to the type IV class of pilins, which share a highly conserved N-terminal region 35 amino acids in length, containing a short leader of 6 or 7 amino acids. Two site-specific mutants in the N-terminal region of the mature pilin were constructed. Reestablishing the fifth-position glutamate in a four amino acid deletion mutant (amino acids 4–7) restored the leader peptidase cleavage but not the methylation. A mutation of the fifth-position glutamate to alanine decreased the degree of methylation of the N-terminal phenylalanine. Pili were not assembled by these mutants as assessed by electron microscopy and sensitivity to pilus-specific bacteriophage. Methylation may be required for recognition of the pilin by the assembly machinery and is not residue specific. The fifth-position glutamate appears to play an important role in transmethylase recognition of the pilin subunit.Key words: Pseudomonas aeruginosa, pilin, transmethylase.
Caffeine tolerance in Schizosaccharomyces pombe: physiological adaptation and interaction with theophylline
Authors: Benkö Z. , Sipiczki M.
Published: May 2010

Caffeine at concentrations of 8 mM or higher inhibited cell propagation and killed a fraction of the population. Cell inactivation increased incrementally with increasing concentrations. The survivors developed tolerance by physiological adaptation that enabled them to propagate in the presence of the drug, but the tolerance could easily be lost if the cells grew in the absence of caffeine for a few generations. Theophylline was found to diminish the toxic effect of caffeine. Possible mechanisms for the observed cellular response and its implications for studies of the effects of these drugs in eukaryotes are discussed.Key words: Schizosaccharomyces pombe, caffeine, theophylline, adaptation.
A two-part energy burden imposed by growth of Enterobacter cloacae and Escherichia coli in sodium dodecyl sulfate
Authors: Aspedon Arden , Nickerson Kenneth W.
Published: May 2010

Enterobacter cloacae, like most enteric bacteria, can grow in the presence of 10% sodium dodecyl sulfate (SDS). The bacteria tolerate the detergent and do not metabolize it. In a defined glucose–salts medium the growth rate remained unchanged (G = 55 min) as the detergent concentration was increased from 0 to 10% SDS. However, growth in SDS exhibited a two-part energy dependence. In part 1, the SDS-grown cells underwent rapid lysis when they ran out of energy. Cells that had entered stationary phase owing to carbon limitation lysed, while those that had entered owing to nitrogen or phosphorus limitation did not. We attribute part 1 of the energy dependence to SDS as a detergent. In part 2, the cells grown in 5 or 10% SDS exhibited longer lag periods, potassium accumulation, decreased cell yields, and higher oxygen consumption. The higher oxygen consumption occurred during both exponential phase and nitrogen-limited stationary phase. However, the decreased cell yield and higher oxygen consumption of SDS-grown cells were mimicked by cells grown in equivalent concentrations of sucrose or polyethylene glycol. We attribute part 2 of the energy dependence to SDS as a solute. Finally, with regard to the as yet unidentified bacterial osmotic stress detector, we used the micelle-forming nature of SDS to conclude that the detector was responding to turgor pressure – water activity rather than to osmolarity itself.Key words: sodium dodecyl sulfate, bacterial detergent resistance, osmotic stress, oxygen consumption, energy-dependent cell lysis.
Bioenergetic studies of Methanosphaera stadtmanae, an obligate H2–methanol utilising methanogen
Authors: Sparling Richard , Blaut Michael , Gottschalk Gerhard
Published: May 2010

In Methanosphaera stadtmanae producing methane from the reduction of methanol with H2, sodium (> 0.3 mM Na+) was not required for methanogenesis or ATP synthesis. The ATPase inhibitor N,N′-dicyclohexylcarbodiimide inhibited both ATP synthesis and methanogenesis, but was only effective in the presence of low Na+ (< 1 mM). The observed N,N′ -dicyclohexylcarbodiimide inhibition of methanogenesis was relieved by the addition of the protonophore 3,3′,4′,5-tetrachlorosalicylanilide. 3,3′,4′,5-Tetrachlorosalicylanilide itself caused a rapid decrease in the intracellular ATP concentration and stimulated methanogenesis. This stimulation was enhanced when the cells were incubated in the presence of NaCl. The effects of Na+ on the effectiveness of N,N′-dicyclohexylcarbodiimide and 3,3′,4',5-tetrachlorosalicylanilide cannot yet be explained. Ionophores (3,3′,4′,5-tetrachlorosalicylanilide, SF6847, monensin, and gramicidin) caused decreases in the membrane potential and the intracellular ATP concentration while stimulating methanogenesis. The data presented are consistent with the coupling of the last step of methanogenesis to ATP synthesis via a proton motive force in a representative of the Methanobacteriales.Key words: methanogenesis, proton motive force, membrane potential.
Characterization of cell surface properties in agglutinable and nonagglutinable mutants of Pseudomonas putida
Authors: Buell C. R. , Whetton R. , Tari P. , Anderson A. J.
Published: May 2010

Cells of an aggressive, root-colonizing isolate of Pseudomonas putida are agglutinated by a root surface glycoprotein. The agglutination phenotype in P. putida isolate Corvallis is lacking in mutants (Agg−) derived by Tn5 insertion and chemical mutagenesis. Specific mutation in the aggA locus by Tn5 insertion results in loss of agglutinability that is complemented in trans by a wild-type copy of the P. putida aggA locus. We examined the biochemical bases of agglutination in P. putida by comparing cell surface features in Agg+, Agg− mutants, and a genetically restored aggA mutant. No changes in gross cell surface features involving hydrophobic or hydrophilic binding or net negative charge were observed. Three macromolecular features, pili, flagella, and lipopolysaccharide size, did not differ between Agg+ and Agg− mutants. Protein profiles of cell envelope, periplasmic, and outer membrane preparations revealed pleiotropic effects of mutation in agglutination phenotype including alterations of an outer membrane protein of 47 000 molecular weight and periplasmic proteins of 56 000 and 60 000 molecular weight. The protein alterations seen in the aggA::Tn5 Agg− mutant 5123 reverted to wild-type patterns upon introduction of a wild-type copy of the aggA locus. These data suggest agglutinability may be conditioned by more than one proteinaceous component associated with the bacterial envelope layers.Key words: cell surface, binding, recognition.
Geosmin-producing species of Streptomyces and Lyngbya from aquaculture ponds
Authors: Schrader Kevin K. , Blevins Willard T.
Published: May 2010

Water and sediment samples collected monthly from six aquaculture ponds in east-central Alabama were analyzed for the presence of actinomycetes and cyanobacteria capable of producing geosmin and (or) 2-methylisoborneol, which cause earthy–musty off-flavors in fish. Six actinomycetous isolates were identified as geosmin producers, five of which were capable of producing 2-methylisoborneol. The one actinomycetous isolate producing geosmin but not 2-methylisoborneol was identified as Streptomyces halstedii. Only one of several cyanobacterial isolates was found to produce geosmin. This isolate was identified as Lyngbya cf. subtilis and was prevalent throughout the sampling period in a pond with a history of off-flavor problems. None of the cyanobacterial isolates produced 2-methylisoborneol in laboratory culture.Key words: geosmin, Streptomyces, Lyngbya, off-flavor, aquaculture.
Étude comparative de la flore bactérienne de la rhizosphère de deux cultivars de palmier dattier sensible et résistant à la fusariose
Authors: Lamari Lynda , Sabaou Nasserdine
Published: May 2010

This report deals with the qualitative and quantitative distributions of bacterial populations in the rhizosphere of two date-palm cultivars, one sensitive and one resistant to fusariosis, and with the antagonistic capacity of these bacteria against the pathogen Fusarium oxysporum f.sp. albedinis. In the external zones of young roots, bacterial growth was stimulated more by the sensitive cultivar than by the resistant one. A survey of 665 isolates permitted the bacteria to be grouped in two main genera, Pseudomonas and Bacillus, and in a coryneform group composed of Arthrobacter, Brevibacterium, and Pimelobacter. The generic and specific composition differed between the two cultivars and varied with root age (young or old) and the root zones considered (internal or external). In external zones, Pseudomonas caryophylli and Pseudomonas gladioli were the most abundant for the sensitive cultivar. In the endorhizosphere, Bacillus firmus was more abundant in the resistant cultivar, and Pseudomonas fluorescens biovar II in the sensitive one. Difference were also noted in the percentages of antagonistic bacteria against F.o. albedinis. The present study confirms the findings of several authors that plants are capable of controlling their own rhizosphere bacterial populations.Key words: bacteria, rhizosphere, systematics, fusariosis, date palm.[Journal translation]
Fibrobacter succinogenes S85 possesses at least nine distinct glucanase genes
Authors: Malburg Jr. Laercio M. , Forsberg Cecil W.
Published: May 2010

The construction of genomic libraries of Fibrobacter succinogenes S85 in λ-Dash, λ-DashII, and pUC19, and the screening of recombinant clones for carboxymethylcellulose hydrolysis yielded 38 glucanase clones. These clones along with a collection of 10 glucanase clones in pUC8, were compared by restriction fragment and Southern hybridization analyses. Seven distinct glucanase clones (pCe14, pCe15, and pCe17 in pUC8, pCe16 in pUC19, and LCe18, LCel10, and LCel12 in λ-Dash) were identified, which were nonhomologous to previously studied cel3, lichenase, and cello-dextrinase genes from F. succinogenes S85. Specific activities of the encoded enzymes expressed in Escherichia coli were higher for carboxymethyl cellulose, barley β-glucan, and lichenan, and lower for acid-swollen cellulose, laminarin, and xylan. The enzymes were predominantly acidic, with pIs between 3.5 and 5.2, with the exception of the pCe16 enzyme, which was basic with a pI of about 8.4. As determined by zymogram analysis after SDS-PAGE, the LCe18 enzyme was 97 kDa, the pCel10 enzyme exhibited components of 70 and 45 kDa, and the pCel12 enzyme components were 69 and 65 kDa. These seven new glucanase clones, along with the cel3 and lichenase genes, indicate that F. succinogenes S85 possesses at least nine distinct endoglucanase genes.Key words: Fibrobacter succinogenes, rumen bacteria, cellulolytic, endoglucanases, glucanases, genes.
Antibacterial activity of multilayer silver–copper surface films on catheter material
Authors: McLean Robert J. C. , Hussain A. A. , Sayer Michael , Vincent Peter J. , Hughes David J. , Smith Timothy J. N.
Published: May 2010

The antimicrobial activity of Ag, Cu, and layered Ag–Cu surface films, sputter-coated onto several types of catheter material, against clinical isolates of Staphylococcus epidermidis and Staphylococcus aureus was evaluated. When 20 μL of a suspension of S. epidermidis or S. aureus (2.68 × 106 colony-forming units/mL) was applied onto Ag–Cu- or Cu-coated butyl rubber, bacterial numbers were greatly reduced within 10 h, and eliminated within 24 h. In contrast, antibacterial activity was significantly less on uncoated or Ag-coated surfaces. Ag–Cu- or Cu-coated silicon rubber, polyvinylchloride, and teflon were even more effective than Ag–Cu- or Cu-coated butyl rubber. Ag–Cu layered surface films also showed antibacterial activity against Pseudomonas aeruginosa biofilm formation. Multiple metal surface film combinations show great promise in lowering the incidence of device-associated nosocomial infections.Key words: copper, silver, antimicrobial surface coating, catheter, nosocomial infections, metallic thin film combinations.
Change in electrosurface properties of Methylomonas rubra cells at contact interaction with particles of silicon dioxide
Authors: Gordienko A. S. , Zbanatskaya I. V. , Kurdish I. K.
Published: May 2010

The addition of highly dispersed silicon dioxide to a suspension of Methylomonas rubra cells under defined conditions resulted in an increasing negative charge in the cells. This phenomenon is not explained in terms of the known conceptions of adsorption processes, in spite of the fact that it is probably a consequence of the contact interaction between cells and silicon dioxide particles.Key words: contact interaction, electrosurface property, silicon dioxide, Methylomonas rubra.