bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of Woodland Rhizobial Populations from Surface- and Deep-Soil Environments of the Sonoran Desert
Authors: Waldon Hollis B. , Jenkins Michael B. , Virginia Ross A. , Harding Ethelynda E.
Published: January 2020

A collection of 74 rhizobial isolates recovered from nodules of the desert woody legumes
Prosopis glandulosa, Psorothamnus spinosus
, and
Acacia constricta
were characterized by using 61 nutritional and biochemical tests. We compared isolates from
A. constricta
and
Prosopis glandulosa
and tested the hypothesis that the rhizobia from a deep-phreatic rooting zone of a
Prosopis
woodland in the Sonoran Desert of southern California were phenetically distinct from rhizobia from surface soils. Cluster analysis identified four major homogeneous groups. The first phenon contained slow-growing (SG)
Prosopis
rhizobia from surface and deep-phreatic-soil environments. These isolates grew poorly on most of the media used in the study, probably because of their requirement for a high medium pH. The second group of isolates primarily contained SG
Prosopis
rhizobia from the deep-phreatic rooting environment and included two fast-growing (FG)
Psorothamnus
rhizobia. These isolates were nutritionally versatile and grew over a broad pH range. The third major phenon was composed mainly of FG
Prosopis
rhizobia from surface and dry subsurface soils. While these isolates used a restricted range of carbohydrates (including sucrose) as sole carbon sources, they showed better growth on a range of organic acids as sole carbon sources and amino acids as sole carbon and nitrogen sources than did other isolates in the study. They grew better at 36°C than at 26°C. The FG
Acacia
rhizobia from surface-soil environments formed a final major phenon that was distinct from the
Prosopis
isolates. They produced very high absorbance readings on all of the carbohydrates tested except sucrose, grew poorly on many of the other substrates tested, and preferred a 36 to a 26°C incubation temperature. The surface populations of
Prosopis
rhizobia required a higher pH for growth and, under the conditions used in this study, were less tolerant of low solute potential and high growth temperature than were phreatic-soil isolates. SG
Prosopis
rhizobia from phreatic and surface soils were physiologically distinct, suggesting adaptation to their respective soil environments.
Profiling and Quantitation of Bacterial Carotenoids by Liquid Chromatography and Photodiode Array Detection
Authors: Nelis H. J. , De Leenheer A. P.
Published: January 2020

An analytical method for the profiling and quantitative determination of carotenoids in bacteria is described. Exhaustive extraction of the pigments from four selected bacterial strains required treatment of the cells with potassium hydroxide or liquefied phenol or both before the addition of the extracting solvent (methanol or diethyl ether). The carotenoids in the extracts were separated by nonaqueous reversed-phase liquid chromatography in conjunction with photodiode array absorption detection. The identity of a peak was considered definitive only when both its retention time and absorption spectrum, before and after chemical reactions, matched those of a reference component. In the absence of the latter, most peaks could be tentatively identified. Two examples illustrate how in the analysis of pigmented bacteria errors may result from using nonchromatographic procedures or liquid chromatographic methods lacking sufficient criteria for peak identification. Carotenoids of interest were determined quantitatively when the authentic reference substance was available or, alternatively, were determined semiquantitatively.
Comparison of membrane filtration and Autoanalysis Colilert presence-absence techniques for analysis of total coliforms and Escherichia coli in drinking water samples
Authors: Lewis C M , Mak J L
Published: January 2020

Over a 4-month period, 950 samples of treated drinking water were analyzed for total coliforms (TC) and Escherichia coli by both membrane filtration (MF) and Autoanalysis Colilert presence-absence (AC) techniques. The two tests agreed 97% of the time on the basis of presumptive TC results and 98.5% of the time on the basis of verified TC results. Samples which produced disagreement between the two tests were most often TC positive by MF and TC negative by AC. E. coli was recovered four times: twice by MF only, and twice by AC only but without the diagnostic fluorescence reaction. In two samples, E. coli could not be isolated from fluorescence-positive AC tests. On the basis of these results, the AC test was implemented as the routine analytical procedure for TC but not for E. coli.
High-Frequency Transformation, by Electroporation, of
Lactococcus lactis
subsp.
cremoris
Grown with Glycine in Osmotically Stabilized Media
Authors: Holo Helge , Nes Ingolf F.
Published: January 2020

An efficient method for genetic transformation of lactococci by electroporation is presented. Highly competent lactococci for electrotransformation were obtained by growing cells in media containing high concentrations of glycine and 0.5 M sucrose as the osmotic stabilizers. These cells could be stored at −85°C without loss of competence. With
Lactococcus lactis
subsp.
cremoris
BC101, a transformation frequency of 5.7 × 10
7
transformants per μg of pIL253 DNA was obtained, which represents 5% of the surviving cells. All the lactococcal strains tested could be transformed by the present method.
Bacterial sorption of heavy metals
Authors: Mullen M D , Wolf D C , Ferris F G , Beveridge T J , Flemming C A , Bailey G W
Published: January 2020

Four bacteria, Bacillus cereus, B. subtilis, Escherichia coli, and Pseudomonas aeruginosa, were examined for the ability to remove Ag+, Cd2+, Cu2+, and La3+ from solution by batch equilibration methods. Cd and Cu sorption over the concentration range 0.001 to 1 mM was described by Freundlich isotherms. At 1 mM concentrations of both Cd2+ and Cu2+, P. aeruginosa and B. cereus were the most and least efficient at metal removal, respectively. Freundlich K constants indicated that E. coli was most efficient at Cd2+ removal and B. subtilis removed the most Cu2+. Removal of Ag+ from solution by bacteria was very efficient; an average of 89% of the total Ag+ was removed from the 1 mM solution, while only 12, 29, and 27% of the total Cd2+, Cu2+, and La3+, respectively, were sorbed from 1 mM solutions. Electron microscopy indicated that La3+ accumulated at the cell surface as needlelike, crystalline precipitates. Silver precipitated as discrete colloidal aggregates at the cell surface and occasionally in the cytoplasm. Neither Cd2+ nor Cu2+ provided enough electron scattering to identify the location of sorption. The affinity series for bacterial removal of these metals decreased in the order Ag greater than La greater than Cu greater than Cd. The results indicate that bacterial cells are capable of binding large quantities of different metals. Adsorption equations may be useful for describing bacterium-metal interactions with metals such as Cd and Cu; however, this approach may not be adequate when precipitation of metals occurs.
Trichloroethylene degradation by Escherichia coli containing the cloned Pseudomonas putida F1 toluene dioxygenase genes
Authors: Zylstra G J , Wackett L P , Gibson D T
Published: January 2020

Toluene dioxygenase from Pseudomonas putida F1 has been implicated as an enzyme capable of degrading trichloroethylene. This has now been confirmed with Escherichia coli JM109(pDTG601) that contains the structural genes (todC1C2BA) of toluene dioxygenase under the control of the tac promoter. The extent of trichloroethylene degradation by the recombinant organism depended on the cell concentration and the concentration of trichloroethylene. A linear rate of trichloroethylene degradation was observed with the E. coli recombinant strain. In contrast, P. putida F39/D, a mutant strain of P. putida F1 that does not contain cis-toluene dihydrodiol dehydrogenase, showed a much faster initial rate of trichloroethylene degradation which decreased over time.
Beneficial Effects of Nickel on
Pseudomonas saccharophila
under Nitrogen-Limited Chemolithotrophic Conditions
Authors: Barraquio Wilfredo L. , Knowles Roger
Published: January 2020

Addition of nickel stimulated growth and nitrogenase activity of
Pseudomonas saccharophila
under nitrogen-limited chemolithotrophic conditions, apparently because of a significant increase in expression of uptake hydrogenase activity. Inhibition of hydrogenase expression by 50 μM EDTA was relieved by nickel over a wide concentration range (1 to 200 μM). Co
2+
, Zn
2+
, Mn
2+
, and Cu
2+
stimulated expression of hydrogenase activity, but to a much lesser degree than nickel, and Fe
2+
, Mg
2+
, SeO
4
2−
, and SeO
3
2−
did not increase expression. Nickel in individual combination with Mg
2+
, Fe
2+
, SeO
3
2−
, and SeO
4
2−
resulted in activities that were essentially the same as that with nickel alone. Hydrogenase synthesis required the presence of nickel, and repression by O
2
was alleviated by increasing the concentration of added nickel. Cells placed under hydrogenase derepression conditions showed progressive incorporation of radioactive nickel to a much greater extent than did cells which were not derepressed.
Expression of the insecticidal protein gene from Bacillus thuringiensis subsp. aizawai in Bacillus subtilis and in the thermophile Bacillus stearothermophilus by using the alpha-amylase promoter of the thermophile
Authors: Nakamura K , Imanaka T
Published: January 2020

Expression of the insecticidal protein gene from Bacillus thuringiensis subsp. aizawai IPL7 in B. subtilis MI113 and B. stearothermophilus SIC1 was examined. Production of the protein (130 kilodaltons [KDa]) was analyzed by its reaction with antibody against the insecticidal proteins of the parental B. thuringiensis. When the original gene containing its own promoter was subcloned in B. subtilis, only a small amount of the protein was produced. Therefore, both the promoter for the B. stearothermophilus alpha-amylase gene and the insecticidal protein gene were inserted in a repA (low-copy-number) plasmid to yield the recombinant plasmid pTBT-Pamy. B. subtilis MI113 carrying pTBT-Pamy produced more of the 130-kDa protein (about 10(4) molecules per cell) at 37 degrees C. In contrast, B. stearothermophilus SIC1 carrying pTBT-Pamy produced a small amount of 130-kDa protein (10(2) to 10(3) molecules per cell) at 55 degrees C.
Lyophilization of rumen fluid for use in culture media
Authors: Dehority B A , Tirabasso P A
Published: January 2020

The supernatant from centrifugation at 1,000 x g of strained rumen fluid was lyophilized, and the residue and sublimate fractions were used to replace fresh rumen fluid in a complete roll tube medium for enumeration of total rumen bacteria. Most of the growth-supporting nutrients in fresh rumen fluid were found in the residue fraction. With one exception, no significant differences were found in total bacterial numbers either by roll tube or most-probable-number procedures when lyophilized rumen fluid residue was substituted for fresh rumen fluid. Lyophilized rumen fluid residue was stable for at least 5 months at room temperature. Rumen fluid supernatant from centrifugation at 1,000 x g had a mean density of 1.005 +/- 0.03 g/ml and contained 1.56% +/- 0.30% dry matter. On the basis of these values, 15.68 mg of lyophilized rumen fluid residue is equivalent to 1 ml of rumen fluid supernatant from centrifugation at 1,000 x g.
Isolation of microorganisms capable of degrading isoquinoline under aerobic conditions
Authors: Aislabie J , Rothenburger S , Atlas R M
Published: January 2020

Isoquinoline-degrading microbial cultures were isolated from oil- and creosote-contaminated soils. The establishment of initial enrichment cultures required the use of emulsified isoquinoline. Once growth on isoquinoline was established, isoquinoline emulsification was no longer required for utilization of isoquinoline as the sole source of carbon and nitrogen by these cultures. An isoquinoline-degrading Acinetobacter strain was isolated from one of the enrichment cultures. The degradation of isoquinoline was accompanied by the accumulation of a red cell-associated pigment and of 1-hydroxyisoquinoline, which was further degraded to unknown intermediary ring-cleavage products and carbon dioxide.
DNA Probe for Identification of the Take-All Fungus,
Gaeumannomyces graminis
Authors: Henson Joan M.
Published: January 2020

A 4.3-kilobase mitochondrial DNA fragment was cloned from
Gaeumannomyces graminis
var.
tritici
, the causative agent of take-all disease of wheat. Although this DNA fragment hybridized with all three varieties of
G. graminis
, it showed little homology with DNA from other fungi and thus should be useful for identification of
Gaeumannomyces
sp. recovered from infected plants.
Purification and characterization of three parathion hydrolases from gram-negative bacterial strains
Authors: Mulbry W W , Karns J S
Published: January 2020

Three unique parathion hydrolases were purified from gram-negative bacterial isolates and characterized. All three purified enzymes had roughly comparable affinities for ethyl parathion and had broad temperature optima at ca. 40 degrees C. The membrane-bound hydrolase of Flavobacterium sp. strain ATCC 27551 was composed of a single subunit of approximately 35,000 daltons (Da) and was inhibited by sulfhydryl reagents such as dithiothreitol (DTT) and by metal salts such as CuCl2. The cytosolic hydrolase of strain B-1 was composed of a single subunit of approximately 43,000 Da and was stimulated by DTT and inhibited by CuCl2. The membrane-bound hydrolase of strain SC was composed of four identical subunits of 67,000 Da and was inhibited by DTT and stimulated by CuCl2. The substrate ranges of the three enzymes also differed, as evidenced by their relative affinities for parathion and the related organophosphate insecticide O-ethyl-O-4-nitrophenyl phenylphosphonothioate (EPN). The B-1 hydrolase displayed equal affinity for both compounds, the Flavobacterium enzyme showed twofold-lower affinity for EPN than for parathion, and the SC hydrolase displayed no activity toward EPN. The range in characteristics of these three enzymes can be exploited in different waste disposal strategies.
Carbohydrate metabolism in the mosquito pathogen Bacillus sphaericus 2362
Authors: Russell B L , Jelley S A , Yousten A A
Published: January 2020

Bacillus sphaericus 2362 is pathogenic for mosquito larvae and is being considered for large-scale production as a larvicide. The inability of the bacteria to metabolize carbohydrates requires that they be grown on proteinaceous media. This bacterium was found to be unable to transport glucose or sucrose into the cell, and it lacked glucokinase and hexokinase activity. In addition, it lacked phosphoglucose isomerase, phosphofructokinase, and glucose 6-phosphate dehydrogenase, which are early enzymes of the Embden-Myerhof-Parnas and hexose monophosphate pathways. The presence of other enzymes in these pathways was indicated by assay, by the metabolism of glycerol to acetate, and by growth on acetate and gluconate as sole carbon sources. Critical enzymes of the Entner-Doudoroff pathway were also shown to be absent.
Simple method for the detoxification of wastewater ultrafiltration concentrates for rotavirus assay by indirect immunofluorescence
Authors: Oragui J I , Mara D D
Published: January 2020

A simple method for the detoxification of ultrafiltration concentrates of wastewaters for rotavirus assay by the indirect immunofluorescence technique has been developed. Polyacrylamide (Bio-Gel) or dextran (Sephadex G50) beads were mixed with concentrates (0.5 g/10 ml, wt/vol) of wastewaters seeded with simian rotavirus SA11 and allowed to stand for 2 h. The supernatant was decontaminated with antibiotics and then assayed for rotaviruses. Concentrates from raw sewage and treated effluents seeded with SA11 were used to infect MA104 or LLC MK2 cell lines. The concentrates, particularly those from raw sewage and anaerobic waste stabilization ponds, were very toxic to the tissue culture cells. These toxic effects were determined by the detachment and subsequent loss of cells after incubation with concentrates and assay medium for 24 h. They were either completely eliminated or were reduced by greater than 80% after treatment with beads.
Transformation by Complementation of an Adenine Auxotroph of the Lignin-Degrading Basidiomycete
Phanerochaete chrysosporium
Authors: Alic Margaret , Kornegay Janet R. , Pribnow David , Gold Michael H.
Published: January 2020

Swollen basidiospores of an adenine auxotroph of
Phanerochaete chrysosporium
were protoplasted with Novozyme 234 and transformed to prototrophy by using a plasmid containing the gene for an adenine biosynthetic enzyme from
Schizophyllum commune.
Transformation frequencies of 100 transformants per μg of DNA were obtained. Southern blot analysis of DNA extracted from transformants demonstrated that plasmid DNA was integrated into the chromosomal DNA in multiple tandem copies. Analysis of conidia and basidiospores from transformants demonstrated that the transforming character was mitotically and meiotically stable on both selective and nonselective media. Genetic crosses between double mutants transformed for adenine prototrophy and other auxotrophic strains yielded Ade
−
progeny, which indicated that integration occurred at a site(s) other than the resident adenine biosynthetic gene.
3-Nitrobenzenesulfonate, 3-Aminobenzenesulfonate, and 4-Aminobenzenesulfonate as Sole Carbon Sources for Bacteria
Authors: Locher Hans H. , Thurnheer Thomas , Leisinger Thomas , Cook Alasdair M.
Published: January 2020

Aerobic, carbon-limited, enrichment cultures containing 3-aminobenzenesulfonate or 3-nitrobenzenesulfonate as the sole source of carbon and energy yielded growth and complete substrate disappearance. Pure cultures of putative pseudomonads were isolated which utilized these compounds quantitatively. Degradation was compared with that of 2- and 4-aminobenzenesulfonate.
Comparison of the presence-absence and membrane filter techniques for coliform detection in small, nonchlorinated water distribution systems
Authors: Bancroft K , Nelson E T , Childers G W
Published: January 2020

The traditional membrane filter (American Public Health Association, Standard Methods for the Examination of Water and Wastewater, 16th ed., American Public Health Association, Washington, D.C., 1985) and presence-absence (P-A) (J. A. Clark, Can. J. Microbiol. 14:13-18, 1968) techniques for the detection of coliform bacteria were compared in a small nonchlorinated drinking water distribution system by using total positive samples and frequency-of-occurrence analyses. No significant differences (P less than 0.05) were found in detection of the presence of coliform bacteria or in changes in the frequency of occurrence with time. A reduction in P-A sample volume (to 50 ml) was not found to statistically affect the comparative results of traditional membrane filter and P-A tests.
Scanning Electron Microscopy of Invasion of Apple Leaves and Blossoms by
Pseudomonas syringae
pv.
syringae
Authors: Mansvelt E. Lucienne , Hattingh M. J.
Published: January 2020

Scanning electron microscopy indicated that
Pseudomonas syringae
pv.
syringae
L795 entered leaves through stomata and multiplied in the substomatal chambers. Strain L195 applied to blossoms colonized stigmas and also occurred in intercellular spaces of styles. Nonpathogenic strain L796 failed to colonize blossoms. This study suggests that inoculum of pathogenic
P. syringae
pv.
syringae
builds up on apple leaves and blossoms.
Simple, rapid method for direct isolation of nucleic acids from aquatic environments
Authors: Somerville C C , Knight I T , Straube W L , Colwell R R
Published: January 2020

Direct isolation of nucleic acids from the environment may be useful in several respects, including the estimation of total biomass, detection of specific organisms and genes, estimations of species diversity, and cloning applications. We have developed a method that facilitates the concentration of microorganisms from aquatic samples and the extraction of their nucleic acids. Natural water samples of 350 to greater than 1,000 ml are concentrated on a single cylindrical filter membrane (type SVGS01015; Millipore Corp., Bedford, Mass.), and cell lysis and proteolysis are carried out within the filter housing. Crude, high-molecular-weight nucleic acid solutions are then drawn off the filter. These solutions can be immediately analyzed, concentrated, or purified, depending on the intended application. The method is simple, rapid, and economical and provides high-molecular-weight chromosomal DNA, plasmid DNA, and speciated RNAs which comigrate with 5S, 16S, and 23S rRNAs. The methods presented here should prove useful in studying both the ecology and the phylogeny of microbes that resist classical culture methods.
Isolation and Characterization of a Bacteriophage Lytic for
Desulfovibrio salexigens,
a Salt-Requiring, Sulfate-Reducing Bacterium
Authors: Kamimura Kazuo , Araki Michio
Published: January 2020

A bacteriophage that lysed
Desulfovibrio salexigens
cells was isolated from marine sediments and preliminarily characterized by electron microscopy and electrophoretic analysis of structural proteins and genomic nucleic acid. The bacteriophage had an icosahedral head and a long flexible tail, and the buoyant density of the bacteriophage particles was 1.468 g/ml in cesium chloride. The particles consisted of a double-stranded DNA molecule about 33 kilobase pairs long and at least 11 structural proteins.
Combined effect of water activity and pH on inhibition of toxin production by Clostridium botulinum in cooked, vacuum-packed potatoes
Authors: Dodds K L
Published: January 2020

The effects of water activity (aw, 0.955 to 0.970), pH (4.75 to 5.75), and storage time (up to 60 days) on toxin production by Clostridium botulinum in cooked, vacuum-packed potatoes were studied by using factorial design experiments and most-probable-number methodology. Samples were inoculated with 10(3), 10(4), or 10(5) spores of a mixture of five type A and five proteolytic type B strains, incubated at 25 degrees C, and analyzed for toxin production. Toxin was produced at pH levels of greater than or equal to 4.75 when the aw was greater than or equal to 0.970, pH greater than 5.25 when the aw was 0.965, and pH greater than or equal to 5.75 at an aw of 0.960. No toxin was detected when the aw was 0.955. The probability of toxigenesis was significantly affected (P less than 0.0001) by storage time, aw, pH, and the interactions aw.pH and aw.storage time. The response to a decrease in pH was linear, while the response to a decrease in aw was curvilinear. Using multiple linear regression, equations were derived which could predict the length of time until toxin production and the probability of toxigenesis by a single spore under defined conditions.
Use of a biotinylated DNA probe to detect bacteria transduced by bacteriophage P1 in soil
Authors: Zeph L R , Stotzky G
Published: January 2020

Presumptive bacteriophage P1 transductants of Escherichia coli, isolated from soil inoculated with lysates of transducing phage P1 and E. coli, were confirmed to be lysogenic for phage P1 by hybridization with a biotinylated DNA probe prepared from the 1.2-kilobase-pair HindIII 3 fragment of bacteriophage P1. No P1 lysogens of indigenous soil bacteria were detected with the DNA probe. The sensitivity and specificity of the DNA probe were assessed with purified and dot blot DNA, respectively. In addition, two techniques for the lysis and deproteinization of bacteria and bacteriophages on nitrocellulose filters were compared. These studies indicated that biotinylated DNA probes may be an effective alternative to conventional radiolabeled DNA probes for detecting specific gene sequences in bacteria indigenous to or introduced into soil.
Continuous Production of Thermostable β-Amylase with
Clostridium thermosulfurogenes
: Effect of Culture Conditions and Metabolite Levels on Enzyme Synthesis and Activity
Authors: Nipkow A. , Shen G.-J. , Zeikus J. G.
Published: January 2020

A β-amylase-overproducing mutant of
Clostridium thermosulfurogenes
was grown in continuous culture on soluble starch to produce thermostable β-amylase. Enzyme productivity was reasonably stable over periods of weeks to months. The pH and temperature optima for β-amylase production were pH 6.0 and 60°C, respectively. Enzyme concentration was maximized by increasing biomass concentration by using high substrate concentrations and by maintaining a low growth rate. β-Amylase concentration reached 90 U ml
−1
at a dilution rate of 0.07 h
−1
in a 3% starch medium. A further increase in enzyme activity levels was limited by acetic acid inhibition of growth and low β-amylase productivity at low growth rates.
Factors Affecting Activity and Stability of the
Kluyveromyces lactis
Killer Toxin
Authors: Wilson C. , Whittaker P. A.
Published: January 2020

A number of physical parameters determining the activity and stability of the killer toxin produced by the yeast
Kluyveromyces lactis
have been investigated. The toxin was active over a relatively narrow pH range of 4.4 to 5.8, with a maximum at the lower end of the range. However, it was stable up to at least pH 8.0 but appeared to be irreversibly inactivated below pH 4.4. The toxin was stable at 40°C but rapidly inactivated at 50°C. Strong agitation caused the inactivation of the toxin in one medium but not another; this seemed to be due to oxygen-mediated disulfide bond formation, which could be prevented by sulfhydryl protecting agents.
Use of the Chrome Azurol S Agar Plate Technique To Differentiate Strains and Field Isolates of
Rhizobium leguminosarum
biovar
trifolii
Authors: Ames-Gottfred N. P. , Christie B. R. , Jordan D. C.
Published: January 2020

Identification of
Rhizobium
and
Bradyrhizobium
strains and especially of indigenous isolates continues to be one of the major difficulties associated with competition studies. Because there is no universally accepted method, the method of choice depends on preference, experience, and equipment. Here, an agar plate technique was used to distinguish strains and field isolates of
Rhizobium leguminosarum
biovar
trifolii
to provide a basis for identifying nodule occupants in further competition studies. A rapid plate technique, based on differential growth characteristics, complements other techniques such as serological reactions, particularly when antisera cross-react with nonhomologous strains. The technique involves culturing strains and isolates on chrome azurol S agar. Although similar responses were observed among some strains, the response was highly reproducible and was considered an ideal complementary technique used in conjunction with serological procedures. Strains with similar responses could often be differentiated by varying media components, such as the source of carbon.
Positive Pressure Effect on Manganese Binding by Bacteria in Deep-Sea Hydrothermal Plumes
Authors: Cowen James P.
Published: January 2020

A positive pressure effect (1.4 to 3.3×) on the binding of Mn
2+
by a natural population of bacteria in a deep-sea hydrothermal plume was discovered over the intermediate pressure range of 1 to 200 atm (1 to 200 bars; ca. 1.01 × 10
2
to 2.03 × 10
4
kPa). The data suggest Mn
2+
binding is functionally barophilic rather than simply barotolerant.
National field evaluation of a defined substrate method for the simultaneous detection of total coliforms and Escherichia coli from drinking water: comparison with presence-absence techniques
Authors: Edberg S C , Allen M J , Smith D B
Published: January 2020

A defined substrate method was applied to drinking water to simultaneously enumerate total coliforms and total Escherichia coli directly from samples. After incubation at 35 degrees C for 24 h, the development of yellow in an initially colorless solution was specific for total coliforms; fluorescence at 366 nm in the same tube(s) or vessel demonstrated the presence of E. coli. No confirmatory or completed steps were necessary. Known as autoanalysis colilert (AC), this method was constituted as a presence-absence test and compared with the methods described in Standard Methods (SM) in the P-A format. Seven water utilities representing a wide geological and hydrological spectrum participated in the evaluation. A total of 702 split drinking water samples were analyzed. Of these, 358 were negative in both tests (SM- and AC-); 302 were positive (SM+ and AC+); and 42 were mixed (SM+ and AC-, 20; AC+ and SM-, 22). The overall agreement rate was 94%. Comparison of the SM and AC results by nonparametric statistics demonstrated no differences. Heterotrophic plate count bacteria exerted no discernible effect on the AC test. By subculture, each time the AC test was yellow, a total coliform was present; when the test was fluorescent, E. coli was isolated.
Thermophilic Bacillus sp. that shows the denitrification phenotype of Pseudomonas aeruginosa
Authors: Gokce N , Hollocher T C , Bazylinski D A , Jannasch H W
Published: January 2020

A thermophilic Bacillus sp. of marine origin was observed to grow anaerobically on nitrite, nitrous oxide (N2O) in the presence of nitrite, and N2O alone for a few hours after exhaustion of nitrite. This represents the second example of a denitrification phenotype originally observed to occur with Pseudomonas aeruginosa.
Gas Vacuolate Bacteria from the Sea Ice of Antarctica
Authors: Staley James T. , Irgens Roar L. , Herwig Russell P.
Published: January 2020

Gas-vacuolate heterotrophic bacteria from marine habitats are reported here for the first time. They have been isolated from Antarctic sea ice microbial communities and the underlying water column. The predominant gas-vacuolate bacterium from the sea ice is filamentous and pigmented, whereas those of the water column are unicellular and nonpigmented. The highest concentrations of bacteria in sea ice were found in conjunction with the highest algal (chlorophyll
a
) concentrations.
Biosynthesis of fusarochromanone and its monoacetyl derivative by Fusarium equiseti
Authors: Xie W P , Mirocha C J , Pawlosky R J , Wen Y C , Xu X G
Published: January 2020

One fluorescent compound previously named TDP-2 was isolated and purified from a rice culture of Fusarium equiseti (Alaska 2-2). Mass spectral and nuclear magnetic resonance data indicated that it is a C-3'-N-acetyl derivative of fusarochromanone, a newly discovered mycotoxin. Time course studies of synthesis of these two compounds on autoclaved rice and Czapek-Dox medium enriched with soybean peptone indicated that fusarochromanone was converted to TDP-2 in the cultures. A high concentration of peptone in the liquid medium may stimulate both fusarochromanone synthesis and its conversion to TDP-2.
Virulence studies based on plasmid profiles of the fish pathogen Vibrio salmonicida
Authors: Wiik R , Andersen K , Daae F L , Hoff K A
Published: January 2020

Strains of Vibrio salmonicida isolated from Atlantic salmon (Salmo salar) and rainbow trout (Salmo gairdneri) suffering from cold-water vibriosis could be divided on the basis of plasmid profiles into four different categories. Of 32 strains, 19% harbored three plasmids of 24, 3.4, and 26 megadaltons (MDa), 69% harbored the 24- and 3.4-MDa plasmids but not the 2.6-MDA plasmid, and 9% harbored only the 24-MDA plasmid. The fourth category, which consisted of only one strain, harbored a plasmid of 10 MDa. In spite of different plasmid patterns, the strains of V. salmonicida were very similar with respect to biochemical reactions. The one-third of the V. salmonicida strains which were serotyped were of the same type. The 50% lethal doses, which were determined by intraperitoneal injection, ranged from 4 x 106 to 1 x 108 CFU per fish.
pH-controlled continuous cultivation of mycoplasmas
Authors: Krebs B , Schütz M , Fischer M , Sommer G , Kirchhoff H
Published: January 2020

The continuous cultivation of mycoplasmas in a pH-controlled metabolistat was investigated with the fermentative strain Mycoplasma mobile 163K and the nonfermentative strain Mycoplasma arthritidis ISR1. The addition of medium and the removal of culture suspension were regulated by acid production from glucose by M. mobile 163K and by ammonium production from arginine by M. arthritidis ISR1, respectively. For both strains the optimal pH for continuous growth was 7.0. The steady state could be maintained for at least 21 days. With CFU of 8.4 X 10(9) ml-1 (M. mobile 163K) and 3.2 X 10(9) ml-1 (M. arthritidis ISR1), the cell concentrations were slightly higher than those obtained in batch cultures. The dependence on the adjusted pH values was measured for several parameters, such as flow rate, CFU, glucose fermentation or production of ammonia, and gliding velocity. Since the long lag phases of batch cultures can be avoided, pH-controlled continuous cultures provide an appropriate system for the production of mycoplasma cells.
Characterization of the bacterial population structure in an anaerobic-aerobic activated sludge system on the basis of respiratory quinone profiles
Authors: Hiraishi A , Masamune K , Kitamura H
Published: January 2020

Bacterial respiratory quinones were used as biomarkers for studying the bacterial population structure, especially the content of Acinetobacter species, in a laboratory-scale anaerobic-aerobic activated sludge system and in the standard aerobic system. All tested sludges contained both ubiquinone and menaquinone, with a molar ratio of about 1:0.5. High-performance liquid chromatography showed that ubiquinone with eight isoprene units (Q-8) was present as the predominant ubiquinone, Q-10 was the second most common type, and Q-9 and other homologs were minor components in the anaerobic-aerobic sludge and the standard aerobic sludge. Bacteriological examination indicated that, in both sludge systems, Q-8-containing bacteria constituted a large proportion of the aerobic heterotrophic bacterial flora, but only a few strains with Q-9 were found. These findings demonstrate that the population of Acinetobacter species, which contain Q-9 as the major quinone, is negligible in those environments. The present results suggest that the introduction of anaerobic conditions into the aerobic batch process has little influence on the bacterial community structure.
Comparative Replication of
Lymantria dispar
Nuclear Polyhedrosis Virus Strains in Three Continuous-Culture Cell Lines
Authors: Lynn D. E. , Dougherty E. M. , McClintock J. T. , Shapiro M.
Published: January 2020

We compared the replication of the gypsy moth (
Lymantria dispar
) nuclear polyhedrosis virus in two new cell lines, from embryos and fat body of
L. dispar
, and in a previously available ovarian cell line. Three virus isolates (the Hamden strain [LDP-67] used commercially as GYPCHEK, a plaque-purified clone of Hamden [5-7d], and an isolate from Abington, Mass. [Ab]) were each tested on the three cell lines. The fat-body-derived cell line proved best in terms of occlusion body production for all three virus strains, with the highest yield produced by the Abington strain. On the basis of these results, we conclude that a more efficient in vitro production of gypsy moth virus can be obtained by using the fat body cell line in conjunction with the Abington strain of the virus.
Vertical and Horizontal Variations in the Physiological Diversity of the Aerobic Chemoheterotrophic Bacterial Microflora in Deep Southeast Coastal Plain Subsurface Sediments
Authors: Balkwill D. L. , Fredrickson J. K. , Thomas J. M.
Published: January 2020

Aerobic chemoheterotrophic bacteria were isolated from surface soils and coastal plain subsurface (including deep aquifer) sediments (depths to 265 m) at a study site near Aiken, S.C., by plating on concentrated and dilute media. Morphologically distinct colonies were purified, and their responses to 21 selected physiological tests were determined. These isolates were quite diverse; 626 physiologically distinct types (i.e., types with a unique pattern of responses to the 21 tests) were detected among the 1,112 isolates obtained. Physiologically distinct types were isolated on concentrated and dilute media (only 11% overlap between the groups); isolates from surface soils and subsurface sediments were also quite different (only 3% overlap). The surface soil isolates more readily utilized all but 1 of 12 carbon sources offered, and a significantly larger proportion of them hydrolyzed esculin and gelatin. Only 4% of the subsurface isolates fermented glucose, even though 82% of them could use it aerobically.
l
-Malate and
d
-gluconate were utilized by at least 75% of the subsurface isolates, and seven other carbon sources were used by at least 40% of them. Subsurface isolates from different geological formations (depths) and, to a lesser extent, from the same geological formation at different boreholes differed distinctly in their group responses to certain physiological tests. Moreover, sediments from different depths and boreholes contained physiologically distinct types of bacteria. Thus, considerable bacterial diversity was observed in coastal plain subsurface sediments, even within defined geological formations.
Fermentation products and plant cell wall-degrading enzymes produced by monocentric and polycentric anaerobic ruminal fungi
Authors: Borneman W S , Akin D E , Ljungdahl L G
Published: January 2020

Five anaerobic fungal isolates from the bovine rumen were grown on Coastal Bermuda grass (CBG) leaf blades and monitored over a 9-day period for substrate utilization, fermentation products, cellulase, and xylanase activities. Two of the fungal isolates showed monocentric growth patterns; one (isolate MC-1) had monoflagellated zoospores and morphologically resembled members of the genus Piromyces; the other (isolate MC-2) had multiflagellated zoospores and resembled members of the genus Neocallimastix. Three other isolates (PC-1, PC-2, and PC-3) exhibited polycentric growth and have not yet been described in the literature; these isolates were characterized by differences in morphology. All of the isolates degraded CBG to approximately the same extent (70% [dry weight]) in 9 days. Fermentation product accumulation was concurrent with substrate utilization. The major fermentation products for all isolates were formate, acetate, D-(-)-lactate, L-(+)-lactate, ethanol, carbon dioxide, and hydrogen. Succinate was produced by all cultures, with the exception of MC-1. Fermentation balances revealed different profiles for each isolate. As a group, monocentric isolates produced a greater ratio of oxidized to reduced products when grown on glucose or CBG than did the polycentric isolates, which produced a nearly equal ratio of these products. All isolates exhibited cellulolytic and xylanolytic activities, including endoglucanase, exoglucanase, beta-glucosidase, xylanase, and beta-xylosidase activities. Increasing enzyme activity correlated with the accumulation of fermentation products and substrate utilization. The optimum pH for the enzymatic activity of polycentric isolates was within a more narrow range (pH 6.4 to 7.0) than that of the monocentric isolates (pH 5.5 to 7.5). Activity toward cellulosic substrates was not detected until after the disappearance of reducing sugars. Xylanase activity was found to be five to seven times that of carboxymethyl cellulase activity for all cultures grown on CBG.
Free-living pathogenic and nonpathogenic amoebae in Maryland soils
Authors: Sawyer T K
Published: January 2020

Tests for potentially pathogenic amoebae were carried out on soil samples from the following sites: (i) farmlands fertilized with municipal sewage wastes, (ii) a stream receiving sewage effluent from a sludge lagoon, (iii) a ravine receiving storm runoff from a cattle farm, (iv) farmlands not fertilized with sewage wastes, and (v) a vegetated shoreline of a waterfront estate not used for farming or livestock production. Study sites were located on the eastern shore of Maryland, bordered to the north by Delaware and to the south by Virginia. Twenty-four species of soil amoebae, including five potentially pathogenic Acanthamoeba species (members of the family Acanthamoebidae), were identified. All of the sites yielded two or more of the potential pathogens.
Physical Modeling of the Composting Ecosystem
Authors: Hogan J. A. , Miller F. C. , Finstein M. S.
Published: January 2020

A composting physical model with an experimental chamber with a working volume of 14 × 10
3
cm
3
(0.5 ft
3
) was designed to avoid exaggerated conductive heat loss resulting from, relative to field-scale piles, a disproportionately large outer surface-area-to-volume ratio. In the physical model, conductive flux (rate of heat flow through chamber surfaces) was made constant and slight through a combination of insulation and temperature control of the surrounding air. This control was based on the instantaneous conductive flux, as calculated from temperature differentials via a conductive heat flow model. An experiment was performed over a 10-day period in which control of the composting process was based on ventilative heat removal in reference to a microbially favorable temperature ceiling (temperature feedback). By using the conduction control system (surrounding air temperature controlled), 2.4% of the total heat evolved from the chamber was through conduction, whereas the remainder was through the ventilative mechanisms of the latent heat of vaporization and the sensible temperature increase of air. By comparison, with insulation alone (the conduction control system was not used) conduction accounted for 33.5% of the total heat evolved. This difference in conduction resulted in substantial behavioral differences with respect to the temperature of the composting matrix and the amount of water removed. By emphasizing the slight conduction system (2.4% of total heat flow) as being a better representative of field conditions, a comparison was made between composting system behavior in the laboratory physical model and field-scale piles described in earlier reports. Numerous behavioral patterns were qualitatively similar in the laboratory and field (e.g., temperature gradient, O
2
content, and water removal). It was concluded that field-scale composting system behavior can be simulated reasonably faithfully in the physical model.

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Comparison of fecal microflora of elderly persons in rural and urban areas of Japan
Authors: Benno Y , Endo K , Mizutani T , Namba Y , Komori T , Mitsuoka T
Published: January 2020

The Fecal microflora of 15 healthy elderly persons with a median age of 84 years in a rural area whose inhabitants tend to be long-lived (Yuzurihara-area, Uenohara, Yamanashi Prefecture) was compared with the microflora of individuals with a median age of 68 years in an urban area (Tokyo). The diet of the elderly persons in the Yuzurihara area is characterized by a high intake of dietary fiber. Total numbers of anaerobic bacteria were significantly smaller in the elderly persons in the Yuzurihara area than those in the Tokyo area. A significantly large number of bifidobacteria, but not of lecithinase-negative clostridia, was observed in the elderly persons in the Yuzurihara area. Large numbers and high incidences of bacilli and lecithinase-positive clostridia (mainly Clostridium perfringens) were found in the elderly persons in the Tokyo area. Twenty-five genera and over 81 species were isolated from the elderly persons in the Yuzurihara area, and 25 genera and over 92 species were isolated from the elderly persons in the Tokyo area. Furthermore, significantly larger numbers of Bifidobacterium adolescentis and Fusobacterium mortiferum strains were found in the Yuzurihara group, but significant reductions in the Bacteroides buccae-oris group, B. thetaiotaomicron, Bacteroides spp., C. coccoides, C. paraputrificum, and Clostridium spp. were observed in the same group. A significantly higher isolation rate of Bacillus subtilis was observed in the elderly persons in the Tokyo area. The difference in the fecal microflora between elderly persons in Yuzurihara and those in the Tokyo area might be due to a difference in the intake of dietary fiber.
Hydrogenase synthesis in Bradyrhizobium japonicum Hupc mutants is altered in sensitivity to DNA gyrase inhibitors
Authors: Novak P D , Maier R J
Published: January 2020

In the Hupc mutants of Bradyrhizobium japonicum SR, regulation of expression of hydrogenase is altered; the mutants synthesize hydrogenase constitutively in the presence of atmospheric levels of oxygen. The DNA gyrase inhibitors nalidixic acid, novobiocin, and coumermycin were used to inhibit growth of wild-type and mutant cells. For each inhibitor tested, growth of mutant and wild-type strains was equally sensitive. However, in contrast to the wild type, the Hupc mutants synthesized hydrogenase in the presence of high levels of any inhibitor. Cells were incubated with the drugs and simultaneously labeled with 14C-labeled amino acids, and hydrogenase was immunoprecipitated with antibody to the large subunit of the enzyme. Fluorograms of antibody blots then were scanned to determine the relative amount of hydrogenase (large subunit) synthesized in the presence or absence of the gyrase inhibitors. The amount of hydrogenase synthesized by the Hupc mutants in the presence of 300 micrograms of nalidixic acid per ml was near the level of enzyme synthesized in the absence of the inhibitor. No hydrogenase was detected in antibody blots of wild-type cultures which were derepressed for hydrogenase in the presence of 100 micrograms of coumermycin or novobiocin per ml. In contrast, hydrogenase was synthesized by the Hupc mutants in the presence of 100 micrograms of either drug per ml. The amount synthesized ranged from 5 to 32% and 20 to 49%, respectively, of that in the absence of those inhibitors, but nevertheless, hydrogenase synthesis was detected in all of the mutants examined.(ABSTRACT TRUNCATED AT 250 WORDS)
Hyperexpression of a Bacillus circulans xylanase gene in Escherichia coli and characterization of the gene product
Authors: Yang R C , MacKenzie C R , Bilous D , Narang S A
Published: January 2020

A 4.0-kilobase (kb) fragment of Bacillus circulans genomic DNA inserted into pUC19 and encoding endoxylanase activity was subjected to a series of subclonings. A 1.0-kb HindIII-HincII subfragment was found to code for xylanase activity. Maximum expression levels were observed with a subclone that contained an additional 0.3-kb sequence upstream from the coding region. Enhancer sequences in the upstream region are thought to be responsible for these high expression levels. Southern hybridization analyses revealed that the cloned gene hybridized with genomic DNA from Bacillus subtilis and Bacillus polymyxa. Xylanase activity expressed by Escherichia coli harboring the cloned gene was located primarily in the intracellular fraction. Levels of up to 7 U/ml or 35 mg/liter were obtained. The protein product was purified by ion exchange and gel permeation chromatography. The xylanase had a molecular weight of 20,500 and an isoelectric point of 9.0.
Molecular cloning of genes from Ruminococcus flavefaciens encoding xylanase and beta(1-3,1-4)glucanase activities
Authors: Flint H J , McPherson C A , Bisset J
Published: January 2020

Clones expressing activity against xylan or beta(1-3,1-4)glucan (lichenan) were isolated from a library of Ruminococcus flavefaciens 17 DNA made in bacteriophage lambda EMBL3. Hybridization analyses indicated the recovery of four separate genes encoding xylanases that showed no detectable associated carboxylmethylcellulase activity. One of these genes was associated with clones that also expressed beta(1-3,1-4)glucanase and beta-xylosidase activities.
Styrofoam Cup-Membrane Assembly for Studying Microorganism-Root Interactions
Authors: Hartel Peter G. , Billingsley Jean W. , Williamson Joseph W.
Published: January 2020

An assembly consisting of Styrofoam cups with membranes of varying porosities was developed to study microorganism-root interactions. The assembly permitted uniform distribution of a bacterium in soil and was simple, easy to use, and disposable. In tests with the bacterium
Pseudomonas solanacearum
, little difference in
P. solanacearum
survival was observed in the rhizosphere or nonrhizosphere of tomato.