bluuebunny/crossref_metadata_2025 huggingface dataset:
Mixed bacteriophage infection of Escherichia coli: exclusion of superinfecting T4 by T7
Authors: Loewen R. R. , Miller Jr. R. C. , Warren R. A. J.
Published: April 2010

Escherichia coli was infected with T7, then with T4. When the time between the addition of the two phages was 5 or more minutes, T4 was excluded and most of the infective centres yielded T7 progeny. The DNA of excluded T4 was injected, but it did not replicate nor was it degraded extensively. Transcription of this T4 DNA was largely inhibited, and the transcripts produced were not translated. A variety of T7 amber mutants was examined for the capacity to exclude T4. Amongst the early T7 genes, only the product of gene 1, the T7 RNA polymerase, was essential for T4 exclusion. None of the late genes examined was essential for exclusion.
Virus detection in soils: a comparison of four recovery methods
Authors: Bitton Gabriel , Charles M. Judith , Farrah Samuel R.
Published: April 2010

Among nine eluents tested, 0.5% (w/v) isoelectric casein at pH 9.0 and 0.5% (w/v) non-fat dry milk (pH 9.0) were the most efficient in eluting poliovirus type 1 (Sabin) from Eustis fine sand. However, no significant difference was found between the overall (elution followed by concentration) virus recoveries by non-fat dry milk, isoelectric casein, beef extract, and glycine–EDTA methods.High overall recovery (75%) of low input (200 PFU) of viruses from 100 g of soil was achieved by the isoelectric casein method. It was found that the recovery efficiency of this method was not significantly affected by the soil type, following examination of four Florida soils. The mean overall recovery for the four soils was 50%. For other enteroviruses, the overall recovery for coxsackie B3 was 88% but was significantly lower (23%) for echovirus 4. Examintion of the efficiency of the casein method under field conditions showed that it was possible to recover low poliovirus numbers from soil (0.9–1.3 PFU/g soil).
Adherence of bacteria to leaves
Authors: Leben Curt , Whitmoyer Robert E.
Published: April 2010

Members of seven genra of bacteria, pathogens and nonpathogens of plants, adhered to young leaves when leaves were suspended in cell suspensions for 10 min. With Pseudomonas lachrymans, the adherence rate (cells applied vs. cells adhering) to host (cucumber) and nonhost (chrysanthemum) leaves was a straight-line, log–log function, as was the adherence of Escherichia coli and Serratia marcescens to cucumber leaves. Adhering cells of these three bacteria were washed with water from cucumber leaves at a straight-line, log–log rate. Adhered cells of P. lachrymans were most commonly found near veins on cucumber leaves. There appeared to be a polymeric surface layer on this bacterium and on the cucumber leaf when leaves bearing bacteria were stained with ruthenium red and viewed in thin section.
Soil populations of Rhizoctonia solani from areas of healthy and diseased beets within four sugarbeet fields differing in soil texture
Authors: Roberts D. L. , Herr L. J.
Published: April 2010

Both debris isolation and beet seed colonization methods were used to ascertain Rhizoctonia solani populations in areas of healthy (AH) and rhizoctonia crown rot diseased (DA) sugarbeets within four fields differing in soil texture over a 1-year period (August 1976 to July 1977). Inoculum densities were initially (August–October) higher in DA than in AH, but declined over the winter to levels similar to AH by June. As ascertained by the debris isolation method, AH populations remained low (mostly < 30 colonies/50 g soil) throughout the year. High (90–422 colonies/50 g soil) DA inoculum densities were apparently sustained by active parasitism. Seasonal R. solani populations were postulated to consist of groupings of propagules differing in capacities for survival. Inoculum densities in AH and DA were similar in June indicating that factors other than inoculum density per se may initiate DA within beet fields. Soil textural differences did not adversely affect R. solani populations. Assays based on debris isolation depicted populations more accurately than did beet seed colonization assays. Most colonies developing in debris isolation plates originated from sclerotia.
The fate of aflatoxin in naturally contaminated corn during the ethanol fermentation
Authors: Lillehoj E. B. , Lagoda A. , Maisch W. F.
Published: April 2010

Corn naturally contaminated with aflatoxin was used as a substrate in the ethanol fermentation. Distribution of toxin in several process and recovery fractions was identified. Although little degradation of the mycotoxin occurred during fermentation, no toxin appeared in the distilled alcohol. As accumulation of toxin in spent grains represents a potential problem in use of the material as animal feed, several decontamination procedures were tested. Sodium hydroxide, ammonium hydroxide, sodium hypochlorite, and hydrogen peroxide were identified as efficient agents of toxin degradation.
Identification of clinical isolates of selected species of Bacteroides: production of phenylacetic acid
Authors: Mayrand D.
Published: April 2010

A total of 132 human clinical isolates were identified and tested for the production of phenylacetic acid. With the exception of B. vulgatus. B. melaninogenicus ss. melaninogenicus, and B. melaninogenicus ss. intermedius, all other species under study produced phenylacetic acid. This property can thus serve as a basis for faster characterization of the strains in clinical laboratories.
Evaluation of bactericidal assay in serotyping Neisseria meningitidis group A
Authors: Quan Alice L. , Sippel John E.
Published: April 2010

Seventeen of 22 group A meningococcal strains were separated into four serotypes by a microbactericidal assay using group A antisera. In addition. 6 of 19 of these strains were killed by a group B antiserum and similar cidal patterns were obtained with a group C antiserum. There was little correlation between type and case or carrier isolates, or between types and geographical location.
Production of alkaline phosphatase by epithelial cells and adherent bacteria of the bovine rumen and abomasum
Authors: Fay J. P. , Cheng K. J. , Costerton J. W.
Published: April 2010

Three distinct bacterial populations have been defined in the bovine rumen: the rumen fluid population; the population associated with food particles: and the population adherent to the rumen epithelium. Alkaline phosphatase activity has been reported in cells of the first two populations and here we report that assays of rumen epithelial samples containing both tissue and bacteria also contain the enzyme. The reaction product technique has localized the enzyme both in adherent bacteria and in cells of the stratified squamous rumen epithelium. The epithelium of the abomasum shows much lower levels of alkaline phosphatase activity.
Observation d'un sol forestier (rendzine) en microscopie electronique
Authors: Kilbertus G. , Proth J.
Published: April 2010

Scanning electron microscopy was used to evidence the aggregated structure of a forest soil as well as the presence of fungal hyphae external to soil aggregates.The supernatant of soil suspension in water mainly contained isolated bacteria, while ultrathin sections of aggregates frequently revealed groups of bacteria surrounded by a sheath of mucilage with adhering clay minerals on the outside.These results confirm the existence of two particular biotopes in the soil studied: one is located inside aggregates, and the other, in the inter-aggregate spaces. [Translated by the journal]
Suppression of PHA-stimulated lymphocyte transformation in cynomolgus monkeys following infection with Coxiella burnetii
Authors: Kishimoto R. A. , Gonder J. C.
Published: April 2010

Phytohemagglutin (PHA) induced blstogenesis of peripheral blood lymphocytes from cynomolgus monkeys infected with C. burnetii was suppressed between 14 and 28 days after infection. Lymphocytes became responsive to PHA again on day 35 with an increase in stimulation index when cultured with specific antigens. In contrast, production of specific humoral anlibodies was not diminished during the acute and early convalescent stages of infection.
ICMSF methods studies. XII. Comparative study for the enumeration of Clostridium perfringens in feces
Authors: Hauschild A. H. W. , Desmarchelier P. , Gilbert R. J. , Harmon S. M. , Vahlefeld R.
Published: April 2010

As the second phase of an international comparative study for the enumeration of Clostridium perfringens, four methods were compared for "total" and spore counts of C. perfringens in fecal specimens: the SFP (Shahidi-Ferguson perfringens) agar (A), TSC (tryptose–sulfite–cycloserine) agar (B), SC (sulfite–cycloserine) agar (C), and neomycin blood agar (D) methods. In both the total and spore count procedures, the confirmed C. perfringens counts in method D were lower than in methods A, B, and C. Little differences among methods were found in the percentages of presumptive colonies confirmed as C. perfringens. The nonspecific counts in methods A and D were generally greater than in B and C, but nonspecific microorganisms did not interfere in the enumeration of C. perfringens spores by any of the four methods. In overall performance, methods B and C were superior to A and D. The mean C. perfringens spore count was only 0.17 log lower than the mean total count. Spore counts alone are, therefore, adequate in investigations of C. perfringens outbreaks.
Effect of a bacteriophage on the colonisation and nodulation of clover roots by a strain of Rhizobium trifolii
Authors: Evans J. , Barnet Y. M. , Vincent J. M.
Published: April 2010

The presence of a virulent bacteriophage in the root zone of clover growing in seedling agar under controlled environments (14–17 and 19–23 °C) produced changes in the persistence and symbiotic effectiveness of a susceptible strain of Rhizobium trifolii. The phage reduced the rhizoplane population of rhizobia and led to the appearance of variant substrains which were less susceptible to the bacteriophage and mostly ineffective in symbiotic nitrogen fixation. Some were also changed in colonial morphology and nutritional requirements. At the higher temperature, the frequency of bacterial variants increased and the number of nodules due to the parent strain decreased. A large initial population of bacteriophage was able to reduce, but generally did not completely suppress, nodulation.
Effect of a bacteriophage on colonisation and nodulation of clover roots by paired strains of Rhizobium trifolii
Authors: Evans J. , Barnet Y. M. , Vincent J. M.
Published: April 2010

The effect of a virulent bacteriophage on the competitive behaviour of paired strains of Rhizobium trifolii in the root zone of clover plants was examined. The presence of bacteriophage reduced the population density of susceptible strains on the root surface and, in nodulation, favoured resistant or even partially resistant strains which were otherwise less able to form nodules. These effects occurred with different growth temperatures, host species, and ratios of strains in the inoculum.
A modified tube method for the cultivation and enumeration of anaerobic bacteria
Authors: Ogg James E. , Lee Sun Y. , Ogg Betty J.
Published: April 2010

A new type of tube (the Lee tube) has been developed for use in the cultivation and enumeration of obligate anaerobes. The Lee tube is a double-walled, screw-capped tube which allows the formation of a thin cylinder of agar medium between the two walls. Anaerobiosis is achieved through deoxygenation of the deep cylinder of agar during sterilization, a minimum of head space, and use of a reducing agent to absorb oxygen introduced during the inoculation procedure. For several species of Clostridium, Bacteroides fragilis, Fusobacterium necrophorum, Veillonella alcalescens, and Pectinatus cerevisiiphilus, colony counts of cultures in the Lee tubes were comparable with those obtained in pour plates incubated in a BBL GasPak system and in anaerobic roll tubes.
Differentiation of rapidly growing mycobacteria with Trimethoprim (Tmp)
Authors: Laszlo A. , Eidus L.
Published: April 2010

Inhibition of Mycobacterium smegmatis, M. vaccae, and M. diernhoferi by Trimethoprim (Tmp) in both liquid and solid media is described. Other mycobacteria were not inhibited by the same concentrations. The selective inhibition of the above strains, particularly M. smegmatis, by Tmp could be used for differentiation of these species from other fast-growing acid-fast bacteria.
Investigations on the photosynthetic sulfur bacterium Chlorobium phaeobacteroides causing seasonal blooms in Lake Kinneret
Authors: Bergstein T. , Henis Y. , Cavari B. Z.
Published: April 2010

Between May and December, the annual stratification period in Lake Kinneret, sulfide is formed and accumulates in the hypolimnion. In July–August a large population (up to 106 cells/mL) of green, photosynthetic, sulfur bacteria develops at the boundary of the oxidative and reductive zones of the water column lasting for 3–8 weeks. These bacteria were isolated from the lake and identified as Chlorobium phaeobacteroides. Optimal growth conditions included 160 mg S=L−1 and light intensities of 5–0 μEinstein (μE) m−2s−1. Glucose and acetate augmented growth when added to the mineral medium. The lowest light intensity which still supported growth was 0.3 μE m−2s−1 when acetate was present and 1.0 μE m−2s−1 when no organic substrate was present. Under complete darkness, either with or without organic substrate, the bacteria die. Photosynthetic activity was higher when no organic compound was added to the medium. Uptake of acetate was light-dependant.In the lake the photosynthetic activity of the bacteria is low because of the limited light intensity (0.3 μE m−2s−1) at the bloom layer. It is suggested that the appearance and the disappearance of the bloom are caused by the influence of the daily internal seiche.
Effect of divalent cations on the inhibition of alkylsulfatase induction and the generation of ATP in Pseudomonas aeruginosa after exposure to exogenous uridine 5′-triphosphate
Authors: Stewart Gregory J. , Fitzgerald John W.
Published: April 2010

In the absence of added Mg2+, alkylsulfatase induction in resting cells of Pseudomonas aeruginosa was inhibited 17% by exogenous 0.05 mM UTP. Under these conditions, the cells converted UTP to ATP and rapid degradation of these nucleotides did not occur. In the presence of 0.73 mM Mg2+, 0.05 mM UTP repressed the synthesis of the enzyme by 71%. Under these conditions, the cells rapidly degraded both ATP derived from UTP as well as residual UTP. In the presence of Mg2+ and 0.1 mM UTP, full repression of alkylsulfatase formation occurred whereas Mg2+-depleted cell suspensions were still capable of synthesizing 47% of the enzyme under these conditions compared with control levels. The inhibition of alkylsulfatase induction was highly specific for UTP. Some inhibition was observed with exogenous uracil, uridine, and pyrophosophate but only at concentrations > 1.0 mM. Exogenous UMP and UDP (2 mM) had no effect.
DNA base composition, nature of intracellular DNA, morphology, and classification of bacteriophages infecting Micrococcus luteus
Authors: Compton Scott W. , Mayo John A. , Ehrlich Melanie , Ackermann H. W. , Tremblay Lise , Cords C. E. , Scaletti J. V.
Published: April 2010

Ten bacteriophages infecting Micrococcus luteus have been characterized. All phages contain double-stranded DNA, of 64.3–73.5 mol% guanine plus cytosine (GC). The DNA of phage N7 has the highest GC content reported for any bacterial virus. No unusual bases have been found. The intracellular replicating DNAs of six phages are covalently closed circular molecules. All 10 phages have isometric, probably icosahedral, heads and long, flexible, noncontractile tails and can be sorted into two morphological groups based on size and presence or absence of a collar. Host-range studies indicate six host-range groups.
The occurrence of Candida albicans in Lake Ontario bathing beaches
Authors: Sherry J. P. , Kuchma S. R. , Dutka B. J.
Published: April 2010

There are inherent weaknesses associated with currently used bacterial fecal pollution indicator systems. Fecal pollution indicator data would be more meaningful if supplemented with information relating to the occurrence of pathogens in recreational water. Through surveys of four bathing beaches on Lake Ontario, it was established that the opportunistically pathogenic yeast Candida albicans occurs in near shore waters. The beaches surveyed could be differentiated on the basis of bacterial fecal pollution indicator levels and numbers of the pathogens C. albicans and Pseudomonas aeruginosa. The occurrence of C. albicans and P. aeruginosa appeared to be related to elevated fecal pollution indicator levels. Maximum numbers of all parameters were observed in July and August in association with peak bather loads at the beaches. In only one instance does the data suggest that a beach was subjected to human fecal contamination.
Low molecular weight substitutes for beef extract as eluents for poliovirus adsorbed to membrane filters
Authors: Farrah Samuel R. , Bitton Gabriel
Published: April 2010

Basic solutions of beef extract and casein were able to elute poliovirus adsorbed to four membrane filters with different chemical compositions. Hydrolyzed protein and individual amino acids were able to elute virus adsorbed to certain filters but were unable to elute virus adsorbed to other filters efficiently. A solution of 4 M urea buffered at pH 9 with 0.05 M lysine was able to elute greater than 60% of the virus adsorbed to each of the filters tested. Certain solutions of amino acids were capable of eluting virus adsorbed to one filter but permitted adsorption of virus to another filter with a different chemical composition. Acidic amino acids could interfere with elution of virus from membrane filters. Aromatic compounds with an amino group attached to the ring were good eluents for virus adsorbed to epoxy–fiberglass membrane filters. In contrast, aromatic compounds with other substituents were generally poor eluents.
Quantitative determination of cytomegalovirus IgG antibody by enzyme-linked immunosorbent assay (ELISA)
Authors: Chia W. K. , Spence L.
Published: April 2010

Quantitative determination of cytomegalovirus (CMV) human IgG antibody by ELISA performed in polystyrene trays was carried out and compared with results obtained by the routine complement fixation (CF) test. The antibody titres of all the sera determined by ELISA were higher than those detected by the CF test. Of the 27 sera negative (< 1:8) by the CF test, 22 of them were also negative (< 1:50) by ELISA. The other five CF negative sera were found to have low levels of antibody by ELISA. ELISA is a sensitive and specific assay for CMV antibody. The CMV antigen adsorbed readily to the microtitre plates and the test was simple to perform. The results of ELISA could be obtained in 5 to 6 h.A description of the test procedure is given including the method of CMV antigen attachment to the plates. The possibility of using paired sera at a single dilution in the ELISA test to detect seroconversion is discussed.
The effect of nickel on the growth, photosynthesis, and nitrogenase activity of Anabaena inaequalis
Authors: Stratton Glenn W. , Corke Charles T.
Published: April 2010

Anabaena inaequalis was sensitive to nickel ion in the order of decreasing sensitivity of growth, photosynthesis, and acetylene reduction. At a culture density of 9 × 104 cells per millilitre, growth after 12 days was completely inhibited by 0.125 ppm (μg/mL) Ni2+. Nickel caused the increase of both the lag phase of growth and the culture doubling time, and caused the retardation phase to be sooner. Photosynthesis and acetylene reduction were completely inhibited by 10 and 20 ppm Ni2+, respectively, at a cell concentration of 1.3 × 106 cells per millilitre. Preincubation for 24 h in the presence of nickel ion significantly increased the sensitivity of photosynthesis and acetylene reduction. Under these conditions acetylene reduction was more sensitive than photosynthesis. Nickel ion reduced culture growth by 35% at a level of 0.05 ppm and inhibited that culture's acetylene-reducing ability by 29% while leaving photosynthesis unaffected. Nickel caused some damage to filament apical cells and induced pigment bleaching in aged cultures. Nickel toxicity was proposed to be due to poisoning of intracellular enzyme systems by nickel ions.
A liquid medium for the production of Kabatiella zeae conidia
Authors: Reifschneider Francisco J. B. , Arny Deane C.
Published: April 2010

A liquid medium, designated as Kabatiella zeae medium (KZM), containing 10.0 g of carboxymethylcellulose, 5.0 g of maltose, 1.5 g of peptone, 1.0 g of monobasic potassium phosphate, 1 L of distilled water, is described. Peptone was found to be the component most influential in stimulating sporulation. The optimum temperature for conidial production was 25 °C. In shake culture about 107 conidia/mL were produced in 5 days at room temperature (about 21 °C) when KZM was seeded with 4-day-old colony plugs. The optimum for conidial production was pH 5 with only a slight gradual reduction to pH 9. However, fungal development was abnormal at pH values of 4 and 5. Of the 29 isolates tested, only two did not sporulate in KZM or in any other medium. Because of the high yield of conidia in a short time, the ease of preparation and use, and its low cost, KZM is especially useful where large amounts of inoculum are needed.
A medium for commercial production of the halophilic Micrococcus nuclease
Authors: Kamekura Masahiro , Onishi Hiroshi
Published: April 2010

A simple synthetic medium (glutamate–sucrose medium) was devised for production, during growth in shaken flasks, of extracellular halophilic nuclease (nuclease H) by a moderate halophile, Micrococcus varians subsp. halophilus. A simple medium consisting of 0.7% ammonium sulfate, 1.0% glucose, minerals, three vitamins, and 2 M NaCl gave good growth and excellent production of nuclease H in a jar fermentor when the pH was adjusted to 7.5 to 8.0 during cultivation.
An in vitro comparison of some biochemical and biological properties of California and Morocco isolates of Spiroplasma citri
Authors: Igwegbe E. C. K. , Stevens Clauzell , Hollis Jr. John J.
Published: April 2010

California (CI) and Morocco (MI) isolates of Spiroplasma citri incubated at 4, 24, or 32 °C yielded typical mycoplasma colonies on agar at each passage. MI but not CI incubated at 37 °C yielded a few colonies at first passage only, but both isolates did not survive 42 °C for 3 days. In liquid and solid media, best growth of both isolates occurred between pH 7.0 and pH 8.5 and the optimum pH for growth in liquid medium was 7.5 (CI) and 8.5 (MI). The sensitivity of CI or MI to 21 antimicrobial substances was identical in most cases. Corn stunt spiroplasma (CSS) and CI had similar antimicrobial substance spectrum, although CSS was much more sensitive to any given substance than CI. CI fermented the following with acid production: cellobiose, dextrose, galactose, trehalose, fructose, mannitol. maltose, and sucrose. MI fermented all these in addition to arabinose, mannose. sorbitol, and raffinnose. Arginine but not urea was hydrolyzed by both isolates. CI or MI failed to reduce potassium tellurite, methylene blue, or tetrazolium chloride.
Biological effects of magnetic fields: studies with microorganisms
Authors: Moore Richard L.
Published: April 2010

Five bacteria and one yeast were grown in magnetic fields of 50–900 gauss with frequencies of 0–0.3 Hz and square, triangular, or sine waveform. Growth of these microorganisms could be stimulated or inhibited depending upon the field strength and frequency of the pulsed magnetic field. Spore germination and mutation frequency were unaffected by the magnetic fields used in this study.
The function of fimbriae in Myxococcus xanthus. I. Purification and properties of M. xanthus fimbriae
Authors: Dobson W. J. , McCurdy H. D.
Published: April 2010

Myxococcus xanthus fimbriae have been purified and characterized as part of a study of the function of fimbriae in this prokaryote. Myxococcus xanthus produced two types of fimbriae, termed flaccid (F) and rigid (R) on the basis of electron microscopy. F and R fimbriae differed slightly in their response to pH and freeze–thaw regimes but were similar in their resistance to hydrolytic enzymes, amino acid composition, molecular weight, carbohydrate content, and antigenic determinants. Although the precise relationship between F and R fimbriae is unknown, the possibility is considered that F fimbriae might represent a "contracted" form of the R type. Studies designed to determine fimbriae function in M. xanthus are described in an accompanying report.
Amino acid uptake systems in Bacteroides ruminicola
Authors: Stevenson Roselynn M. W.
Published: April 2010

Uptake of amino acids by Bacteroides ruminicola was observed in cells grown in a complete defined medium, containing ammonia as the nitrogen source. A high rate of uptake occurred only in fresh medium, as an inhibitory substance, possibly acetate, apparently accumulated during growth. All amino acids except proline were taken up and incorporated into cold trichloroacetic acid precipitable material. Different patterns of incorporation and different responses to 2,4-dinitrophenol and potassium ferricyanide indicated multiple uptake systems were involved. Kinetic inhibition patterns suggested six distinct systems were present for amino acid uptake, with specificities related to the chemical structures of the amino acids. Thus, the failure of free amino acids to act as sole nitrogen sources for growth of B. ruminicola is not due to the absence of transport systems for these compounds.
Partial characterization of a new C3-type capsule-dissolving phage of Streptococcus cremoris
Authors: Saxelin Maija-Liisa , Nurmiaho Eeva-Liisa , Korhola M. P. , Sundman Veronica
Published: April 2010

A viscous, ropy, sour milk product, called 'viili,' is produced in Finland. Capsule-forming strains of Streptococcus cremoris are the typical starters for this product. Occasionally fermentation fails and results in a non-ropy clot. The reasons for these failures, however, are obscure. In one batch of spoiled 'viili,' a new C3-type bacteriophage, termed KSY1, was isolated. The head of the phage was about 230 nm long and about 50 nm wide and the tail was 35 nm long and carried a complex collar structure. Upon infection of a number of encapsulated cultures of S. cremoris with KSY1, the cocci, though not serving as a host of the phage, lost their capsules. A capsuleless strain, S. cremoris 249, served as a host. The latent period was about 150 min and the average burst size 80. The buoyant density of KSY1 was 1.436 g/cm3.
A modified method for testing inositol assimilation by Cryptococcus species
Authors: Paliwal D. K. , Randhawa H. S. , Kowshik T.
Published: April 2010

The proposed method for rapid testing of inositol assimilation incorporates shake cultures in an indicator-based broth containing inositol (1%). yeast nitrogen base (0.067%), bromocresol purple, and a heavy inoculum. Of 153 yeast isolates investigated, inositol assimilation was shown with the modified method, as also by the Adams–Cooper procedure, in all of the 123 isolates, representing 11 species of Cryptococcus. The results were negative by both the methods in the remaining 30 isolates belonging to Candida, Rhodotorula, Torulopsis, Pichia, Saccharomyces, and Sporoholomyces. The modified method was found to be significantly more effective than the Adams–Cooper procedure; the results could be read within 36 h by the former as against 336 h by the latter method. The superiority of the modified method to the Adams–Cooper procedure is attributed to increased aeration in shake cultures, a heavier inoculum, and reduced concentration of yeast nitrogen base.
Effet de la synthèse d'acide 2 céto-gluconique sur la production d'exopolysaccharides par une souche de Rhizobium meliloti
Authors: Courtois B. , Hornez J. P. , Derieux J. C.
Published: April 2010

Two categories of carbon substrates are defined for Rhizobium meliloti: the first favours the synthesis of exopolysaccharides (fructose belongs to this category) while the other is not suitable (glucose belongs to this category).With fructose, resting cells synthesize polysaccharides during more than 100 h and this synthesis is at its best in aerobic conditions at 30 °C. With glucose, 2-ketogluconic acid accumulates and rapidly stops the synthesis. The method used to stop this acidification allows with glucose a synthesis which can be compared to the one obtained with fructose.
The transformation of arsenicals by Candida humicola
Authors: Cullen William R. , McBride Barry C. , Pickett A. Wendy
Published: April 2010

An analytical procedure for the separation, detection, and identification of some of the compounds produced by a cell preparation of the fungus Candida humicola from 74As-arsenate, [14C]-methylarsonate, and [14C]-dimethylarsinate has been devised and tested. It has been possible to detect five distinct 74As-containing compounds following the incubation of 74As-arsenate with a broken cell homogenate, three of which have been identified as arsenite, methylarsonate, and dimethylarsinate. With [14C]methylarsonate as substrate, [14C]dimethylarsinate and [14C]trimethylarsine oxide are produced. Products from [14C|dimethylarsinate include [14C]methylarsonate and [14C]trimethylarsine oxide as well as an unknown species. The absence of any transformation when buffer replaces the cell preparation implicates these various compounds as intermediates in a biological synthesis of trimethylarsine.
Regulation of peptidoglycan biosynthesis in relA+ and relA− strains of Escherichia coli during diauxic growth on glucose and lactose
Authors: Ishiguro Edward E.
Published: April 2010

In both relA+ and relA− derivatives, the biosynthesis of peptidoglycan, lipid intermediates, and nucleotide precursors abruptly halted at the onset of diauxic lag from glucose to lactose with a concomitant accumulation of guanosine 5′-diphosphate 3′-diphosphate (ppGpp). These results are consistent with the proposal that ppGpp is involved in inhibiting the incorporation of disaccharide-pentapeptide into peptidoglycan and in regulating nucleotide precursor synthesis.
Polioviruses as indicator of virological quality of water
Authors: Payment Pierre , Larose Yolande , Trudel Michel
Published: April 2010

Viruses were found in 47 out of 53 samples of raw domestic sewage collected over a 13-month period from a high socioeconomic level community. At least 39 out of these 47 samples contained polioviruses as was expected in a population where children were receiving Sabin live-attenuated vaccine. Polioviruses could then be used as a suitable indicator of the virological quality of water in communities where Sabin vaccine is used.
Demonstration of positive chemotaxis to cyclic GMP and 5′-AMP in Myxococcus xanthus by means of a simple apparatus for generating practically stable concentration gradients
Authors: Ho J. , McCurdy H. D.
Published: April 2010

A simple apparatus is described for the generation of stable concentration gradients in agar for the study of chemotaxis in gliding bacteria. Myxococcus xanthus was found to be positively chemotactic for guanosine 3′:5′-cyclic monophosphate (cGMP) and adenosine-5′-monophosphate (AMP).
Comparative studies of the mosquito-larval toxin of Bacillus sphaericus SSII-1 and 1593
Authors: Myers Paula , Yousten Allan A. , Davidson Elizabeth W.
Published: April 2010

Two strains of Bacillus sphaericus, SSII-1 and 1593, were bioassayed for toxic activity against second-instar larvae of the mosquito Culex pipiens quinquefasciatus. It was found that strain 1593 developed a level of toxicity 3000 times that of strain SSII-1. Although the toxic activity of B. sphaericus SSII-1 was relatively unchanged throughout growth, an increase in activity of strain 1593 occurred as the bacteria began to sporulate. Strain differences were examined by (i) growth cycle experiments, (ii) bioassays of the toxicity of oligosporogenous mutants, and (iii) manganese limitation experiments. The toxin of strain 1593 was shown to be more stable than that of strain SSII-1. Unlike the spores of strain SSII-1, the spores of B. sphaericus 1593 were found to be highly toxic. Thin sections of SSII-1 or 1593 cells did not reveal the presence of any inclusion body that might be related to toxicity.
Effects of oxygen tension on the lipid composition of Azotobacter chroococcum
Authors: Reczek Edward B. , Burton David N.
Published: April 2010

Lipid content and composition were determined in Azotobacter chroococcum grown, under nitrogen-fixing conditions, in continuous culture with intense aeration under atmospheres containing between 5 and 40% O2. Total lipid content remained almost constant at approximately 9% of dry weight.Phospholipid content was maximal at 20% O2 where it accounted for 92% of total lipid, and was minimal at 40% O2. Phosphatidylethanolamine was the only species of phosphatide detected in this fraction. Neutral lipid content was minimal at 20% O2 and maximal at 40% O2 where it represented approximately 30% of the total lipid. Glycolipid remained between 2 and 13% of total lipid throughout. The principal fatty acids of A. chroococcum were hexadecanoic (C16:0), hexadecenoic (C16:1), and octadecenoic acid (C18:1) at all O2 tensions, but C18:1 increased at the expense of C16:1 at higher O2 tensions, particularly in free fatty acid and phospholipid fractions. [U-14C]acetate was readily incorporated into lipid at both 20 and 40% O2 but total incorporation was much greater at 20% O2.
Differential toxicities of mercury to bacteria and bacteriophages in sea and in lake water
Authors: Babich H. , Stotzky G.
Published: April 2010

Mixtures of anionic HgCl3−/HgCl42− comhplexes were less toxic to terrestrial bacteria (Erwinia herbicola, Agrobacterium tumefaciens), to marine bacteria (Acinetobacter sp., Aeromonas sp.), and to bacteriophages ([Formula: see text] 11M15 of Staphylococcus aureus and P1 of Escherichia coli) than were equivalent concentrations of Hg as cationic Hg2+. The toxicity of 1 ppm Hg to A. tumefaciens, Aeromonas sp., and ([Formula: see text] 11M15 was less in seawater than in lake water. Inasmuch as the Hg–Cl species are formed in environments of high chloride concentration, it was postulated that the lower toxicity of Hg in seawater was a result of the formation of HgCl3−/HgCl42− complexes.
Selective infection of maize roots by streptomycin-resistant Azospirillum lipoferum and other bacteria
Authors: Döbereiner Johanna , Baldani Vera Lucia Divan
Published: April 2010

The percentage of low-level streptomycin-resistant (20 μg/mL) bacteria in surface-sterilized or washed maize roots was more than a thousand times higher than that in soil populations. There was also a higher incidence of resistant bacteria in rhizosphere as compared with non-rhizosphere soil and bacteria isolated from maize roots were relatively tolerant to several other antibiotics. Azospirillum lipoferum was predominant in surface-sterilized roots of field-grown maize and was low-level streptomycin-resistant while most soil isolates were sensitive. Inoculation with A. brasilense isolated from wheat roots was unsuccessful in terms of establishment even when streptomycin-resistant strains were used. Unidentified causes of specific plant–bacteria affinities therefore transcend the role of antibiotic resistance in maize root infection.
Isolation of lignocellulose-decomposing actinomycetes and degradation of specifically 14C-labeled lignocelluloses by six selected Streptomyces strains
Authors: Phelan Mary Beth , Crawford Don L. , Pometto III Anthony L.
Published: April 2010

Forty-two actinomycete strains were isolated by enrichment techniques from soils and other lignocellulose-containing natural habitats. Isolates were screened for their lignocellulose-decomposing abilities using a substrate weight loss – 14C-labeled lignocellulose degradation assay which determined the relative abilities of each isolate to attack lignin versus glucan components of lignocellulose. Six Streptomyces strains were selected for further study, based upon their abilities to decompose significantly both lignin and glucan components of lignocellulose. The selected strains were examined under defined cultural conditions for their abilities to decompose 14C-labeled lignocelluloses prepared from Douglas fir. The 14C-labeled lignocellulose substrates included specifically lignin-labeled or glucan-labeled lignocelluloses, and two [14C]lignin lignocelluloses labeled specifically in only the lignin side chain or ring components. Results showed that the Streptomyces strains decomposed substantial amounts of both lignin and glucan components to 14CO2, and 14C-labeled water-soluble products. As compared with previously described lignocellulose-degrading streptomycetes, these strains were generally more efficient decomposers of the lignin component of lignocellulose, but were similar in their abilities to decompose the glucan component. Characterization of growth on specifically labeled lignins showed that aromatic ring structures within the lignin were cleaved and a substantial percentage of the ring carbons were released as CO2. In contrast, side-chain components were attacked to only a limited degree. These streptomycetes were similar to other recently characterized lignin-decomposing bacteria in their overall abilities to degrade lignin, but their specificity of attack on the structural components of lignin appears to be different.
Synthesis of a selective agar medium for Yersinia enterocolitica
Authors: Schiemann D. A.
Published: April 2010

A new agar medium for isolation of Yersinia enterocolitica was formulated based on growth studies which defined an optimum basal, and the evaluation of selective chemical agents, dyes, and antibiotics. The final formulation, designated cefsulodin–irgasan–novobiocin (CIN) agar, provided quantitative recovery of 40 different strains of Y. enterocolitica in 24 h using incubation at 32 °C or with 48 h of incubation at 22 °C. The medium was highly selective, especially against Pseudomonas aeruginosa, Escherichia coli. Klebsiella pneumoniae, and Proteus mirabilis. Colony morphology coupled with a differential reaction resulting from mannitol fermentation permitted discrimination of Y. enterocolitica from most of those Gram-negative bacteria that were able to grow on the medium. Recovery and selective characteristics of CIN agar were stable during storage at room temperature for 9 days. CIN agar gave a higher recovery of Y. enterocolitica from feces both direct and with cold enrichment (0.4/1.5%) than Salmonella-Shigella (0.0/0.7%) and MacConkey (0.0/0.9%) agars while significantly reducing the level of background organisms.
ICMSF methods studies. XIII. An international comparative study of the MPN procedure and the Anderson–Baird–Parker direct plating method for the enumeration of Escherichia coli biotype I in raw meats
Authors: Rayman M. K. , Jarvis G. A. , Davidson C. M. , Long S. , Allen J. M. , Tong T. , Dodsworth P. , McLaughlin S. , Greenberg S. , Shaw B. G. , Beckers H. J. , Qvist S. , Nottingham P. M. , Stewart B. J.
Published: April 2010

The most probable number (MPN) and a direct membrane-plating (DP) method were compared for enumeration of Escherichia coli biotype I in raw meats by 11 laboratories. The DP method yielded higher counts of E. coli than the MPN method for frozen samples but neither method consistently gave higher counts for non-frozen samples. The DP method was less variable and gave a higher rate of detection of low numbers of E. coli in frozen samples. Despite the inability of the DP method to enumerate E. coli biotype II and intermediate types, which comprise only 3–5% of the Escherichia strains (Ewing 1972), the method is preferable to the MPN method for enumerating E. coli in raw meats because of its lower variability, better recovery from frozen samples, rapidity, decreased requirement for media, and decreased costs for analysts' time.
The effects of a pesticide program on microbial populations from apple leaf litter
Authors: Andrews John H. , Kenerley Charles M.
Published: April 2010

The leaf litter microbial community was quantitatively and qualitatively changed when a standard pesticide schedule that comprised an insecticide, a bactericide, and a fungicide was applied to McIntosh apple trees in the summer. Effects were observed for two winters by four indirect assays and three direct methods. Populations were altered qualitatively both years, but the most striking difference was the quantitative impact from year to year. Bacteria, filamentous fungi, and yeasts from treated leaves were reduced 10- to 10 000-fold between November 1976 and April 1977 and did not recover until snow cover had melted in March. Reductions in 1977–1978 were negligible. The marked seasonal difference is attributed to meteorological influences. Fluorescent pseudomonads were among the bacteria depressed by chemicals. Of the 49 genera of fungi and yeasts isolated, Coniothyrium sp., Penicillium spp., Arthrobotrys spp., and Nodulisporium sp. were appreciably reduced, whereas Typhula spp., Pleurophomella sp., Sporobolomyces spp., and Rhodotorula spp. were substantially enhanced by the spray program.
The effect of L-α-amino-n-butyric acid on growth and production of extracellular isoleucine and valine by Eubacterium ruminantium and a related rumen isolate
Authors: Stevenson I. L.
Published: April 2010

Two anaerobic rumen bacteria, Eubacterium ruminantium and a closely related isolate, were studied to determine the effect of the valine antimetabolite α-aminobutyric acid on growth and production of extracellular isoleucine and valine in an amino acid free medium. In the absence of α-aminobutyrate, these organisms actively excreted valine during growth (90–195 μg/mL) but only accumulated limited concentrations of isoleucine (3–7 μg/mL) in the culture broth. Growth of both organisms was reduced in the presence of 0.5–1.5% α-aminobutyrate but this inhibition was largely overcome by the use of preadapted inoculum. Metabolism of α-aminobutyrate was also increased using preadapted inoculum. During growth in the presence of 0.5–1.5% α-aminobutyrate both organisms accumulated high concentrations of isoleucine (100–225 μg/mL) while the normal accumulation of valine was unaffected. α-Ketobutyrate, a product of α-aminobutyrate metabolism, also stimulated isoleucine excretion by these organisms. The results are discussed in relation to the regulation of the biosynthetic pathways of isoleucine and valine in these rumen anaerobes and the potential significance of this amino acid excretion in ruminant nutrition.
Uptake of [14C]methylammonium by plankton communities: a comparative assay for ammonium transport systems in natural waters
Authors: Vincent Warwick F.
Published: April 2010

A diverse range of freshwater plankton communities were tested for their ability to take up [14C]methylammonium. Uptake occurred at low substrate levels by high-affinity, energy-requiring, transport systems which were competitively inhibited by ammonium but not by L-amino acids or nicotinamide. A simple competitive inhibition model was used to examine the effects of increasing ammonium levels on uptake in a eutrophic lake. Apparent Kt values for the labelled substrate markedly increased with increasing ammonium. The transport systems had an approximately five-fold greater affinity for ammonium than for methylammonium. The Vmax for methylammonium uptake was relatively insensitive to large changes in ambient ammonium levels. This kinetic parameter may be a useful comparative measure of ammonium transport capacity in natural waters, particularly where low ambient ammonium concentrations preclude the use of 15N.
Biosynthesis of chloramphenicol in Streptomyces species 3022a: the nature of the arylamine synthetase system
Authors: Francis M. M. , Westlake D. W. S.
Published: April 2010

The arylamine synthetase which catalyses the conversion of chorismic acid to p-aminophenylalanine in Streptomyces species 3022a was separated from aminotransferase by DEAE-cellulose chromatography. Recovered activity was stimulated by the addition of the aminotransferase and pyridoxal phosphate. Activity was further fragmented into three separate components by passage through a Sephadex G-100 column. Only one component produced p-aminophenylalanine but in combination the three stimulated each other's activity. Although the products of the other two components were unstable, an infrared spectrum of one of them was obtained and confirmed the presence of an aromatic amine, but other functional groups could not be ascertained. This product was not recognized as a substrate by the arylamine synthetase complex and it was suggested that it may be a degradation product of an intermediate of p-aminophenylalanine biosynthesis or an unknown intermediate of later biosynthetic steps of the chloramphenicol pathway. It is further suggested that arylamine compounds produced by this organism are the result of interaction of a core protein with other macromolecules and small molecular weight effector molecules.
Aggregation during sexual development in Dictyostelium discoideum
Authors: O'Day Danton H.
Published: April 2010

A microcinematographic analysis of the behaviour and movements of cells and cell masses in mated cultures (NC4 × V12) of Dictyostelium discoideum indicates that a chemotactic process directs cell aggregation during macrocyst development. Zygote giant cells form before aggregation begins and act as the aggregation centres. Young multicellular macrocyst stages are sources of cyclic AMP, and amoebae from macrocyst cultures orient chemotactically to cyclic AMP. The data, coupled with other characteristics such as pulsatile streaming, suggest that the aggregation process leading to macrocyst development is the same as that occurring during fruit construction. Other aspects of sexual development are also discussed. Based upon these data, we propose a model for the sequence of events leading to macrocyst development in D. discoideum.
Asparagine metabolism and asparaginase activity in a euryhaline Chlamydomonas species
Authors: Paul John H. , Cooksey Keith E.
Published: April 2010

A Chlamydomonas species isolated from a marine environment possesses an L-asparaginase, an enzyme not yet reported in the microalgae. This enzyme enabled the organism to grow as well with asparagine as sole nitrogen source as with inorganic nitrogen sources (NO3−, NH4+). Only the amide nitrogen was used for growth since growth did not occur on aspartate and aspartate accumulated in the media when cells were either grown on asparagine or during short-term incubations with L-[U-14C]asparagine. Cells grown on NO3−, NH4+. or L-asparagine in batch culture possessed equivalent asparaginase activities. However, nitrogen-limited cells possessed four times the activity of cells grown with sufficient nitrogen for normal growth, regardless of the source of nitrogen (NO3−, NH4+ or L-asparagine). In batch culture experiments, cells in log phase possessed the lowest activity per cell, while lag phase and stationary phase cells possessed greater activity. The enzyme behaved like a periplasmic space enzyme since (1) breaking the cells did not release into solution more activity than was shown by whole cells and (2) whole cells converted L-[U-14C]asparagine to [14C]aspartate with little intracellular accumulation of radioactivity. Cell-free preparations of the enzyme possessed a Km value for asparagine of 1.1 × 10−4 M, with no glutaminase activity.