bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of fecal pollution on Vibrio parahaemolyticus densities in an estuarine environment
Authors: Watkins W D , Cabelli V J
Published: January 2020

Vibrio parahaemolyticus densities in the Narragansett Bay, R.I., estuary were found to significantly correlate with the level of fecal pollution in the water. Results of field investigations showed a definite association between the levels of this organism and those of Escherichia coli, Clostridium perfringens, and enterococci. Densities of V. parahaemolyticus were greatest in the near-surface waters of contaminated areas and decreased sharply with both the distance from the sources of fecal pollution and the depth of the water column. A positive association with the amount of particulate matter in the water and specifically with its zooplankton content also was found. No association was obtained with any of the physical or chemical parameters examined except dissolved oxygen. The results of laboratory studies on the growth of V. parahaemolyticus in collected estuarine waters were consistent with the field observations in that nutrients in sewage did not directly produce any increase in natural or inoculated levels of the organism. Of several particulates added to the water, only chitin and net zooplankters (live or dead) supported the growth of V. parahaemolyticus. The addition of sewage to the water had no measurable effect, whether or not the various particulates also were present. The data show that wastewater effluents have an effect on V. parahaemolyticus densities in this estuary and indicate that the effect is indirect, probably mediated by biostimulation of the food chain and manifested at the level of the microfauna.
Application of a simplified method for recovery of Yersinia enterocolitica from surface waters
Authors: Marinelli G , D'Innocenzo C , Fabiani L , Leoni V
Published: January 2020

Yersinia enterocolitica was recovered from surface water by a simplified method: samples were taken by means of the Moore tampon and, after a short, warm preincubation in peptone-sorbitol-bile salts broth, were quickly passed to an alkali solution. Immediately after this, samples were directly plated on MacConkey agar. Y. enterocolitica was isolated from 60% of the water samples, and the identification confirmation of the strains chosen was 100%.
Probability of recovering pathogenic Escherichia coli from foods
Authors: Hill W E , Ferreira J L , Payne W L , Jones V M
Published: January 2020

The probability of recovering pathogenic Escherichia coli from food by the Bacteriological Analytical Manual method was determined by the effects of several factors: the number of strains per food, the ability of pathogenic strains to survive enrichment, and the frequency of plasmid loss during enrichment. Biochemical patterns indicated the presence of about six E. coli strains per food sample. About half of the strains isolated from humans did not survive enrichment. Among those which grew, plasmid loss, as determined by gel electrophoresis and DNA colony hybridization, ranged from 20 to 95%. The combined effects of failure to survive enrichment and plasmid loss decreased the relative numbers of these strains and reduced the chance of detecting pathogens. To counteract this tendency and obtain a 90 to 95% probability off recovering a given pathogenic strain, 40 to 50 colonies per food sample should be picked during the routine testing of foods.
Dissimilation of Carbon Monoxide to Acetic Acid by Glucose-Limited Cultures of
Clostridium thermoaceticum
Authors: Martin Douglas R. , Misra Arun , Drake Harold L.
Published: January 2020

Clostridium thermoaceticum
was cultivated in glucose-limited media, and the dissimilation of CO to acetic acid was evaluated. We found that cultures catalyzed the rapid dissimilation of CO to acetic acid and CO
2
, with the stoichiometry obtained for conversion approximating that predicted from the following reaction: 4CO + 2H
2
O → CH
3
CO
2
H + 2CO
2
. Growing cultures formed approximately 50 mmol (3 g) of CO-derived acetic acid per liter of culture, with the rate of maximal consumption approximating 9.1 mmol of CO consumed/h per liter of culture. In contrast, resting cells were found not to dissimilate CO to acetic acid.
14
CO was incorporated, with equal distribution between the carboxyl and methyl carbons of acetic acid when the initial cultivation gas phase was 100% CO, whereas
14
CO
2
preferentially entered the carboxyl carbon when the initial gas phase was 100% CO
2
. Significantly, in the presence of saturating levels of CO,
14
CO
2
preferentially entered the methyl carbon, whereas saturating levels of CO
2
yielded
14
CO-derived labeling predominantly in the carboxyl carbon. These findings are discussed in relation to the path of carbon flow to acetic acid.
Transpositional Mutagenesis of
Thiobacillus novellus
and
Thiobacillus versutus
Authors: Davidson Mike S. , Roy Pradosh , Summers Anne O.
Published: January 2020

Transpositional mutagenesis of
Thiobacillus novellus
by Tn
501
was achieved by means of the incompatibility of IncP plasmids. Tn
501
insertion caused three types of mutant phenotypes: isoleucine auxotrophy, lysine auxotrophy, and a reduced ability to oxidize reduced sulfur compounds and to fix CO
2
. Oxidation rates for elemental sulfur (S
0
), thiosulfate (S
2
O
3
2−
), and tetrathionate (S
4
O
6
2−
) in mutants of the latter type were reduced relative to those of the nonmutant control strain. Incorporation of labeled bicarbonate (H
14
CO
3
−
) was also significantly impaired. Although suicide vehicles were not useful for the introduction of transposons into
T. novellus
, this method was effective for the Tn
1721
-induced mutagenesis of
Thiobacillus versutus.
Tn
1721
insertions resulted in the loss of the natural resistance of
T. versutus
to arsenate and gentamicin and in auxotrophies for isoleucine-valine, arginine, phenylalanine, valine, and panthothenate. Transpositional mutagenesis by either method should prove to be a useful tool for further study of these and other members of the genus
Thiobacillus.
Toxic effects of chlorinated and brominated alkanoic acids on Pseudomonas putida PP3: selection at high frequencies of mutations in genes encoding dehalogenases
Authors: Weightman A J , Weightman A L , Slater J H
Published: January 2020

Mutant strains of Pseudomonas putida PP3 capable of utilizing monochloroacetate (MCA) and dichloroacetate (DCA) as the sole sources of carbon and energy were isolated from chemostat cultures. The mutants differed from the parent strain in that they could grow on products of MCA and DCA dehalogenation (catalyzed by inducible dehalogenases I and II) and were resistant to growth inhibition by the two substrates. The growth inhibition of strain PP3 by MCA, DCA, and other halogenated alkanoic acids was studied. Sensitivity to dehalogenase substrates was related to the expression of the dehalogenase genes. For example, mutants producing elevated levels of one or both of the dehalogenases were sensitive to 2-monochloropropionate and 2-monochlorobutanoate at concentrations which did not affect the growth of strain PP3. P. putida PP1, the parent of strain PP3, was resistant to the inhibitory effects of MCA and DCA. Spontaneous mutants of strain PP3, also resistant to MCA and DCA, were selected at high frequency, and four different classes of these strains were distinguished on the basis of dehalogenase phenotype. All dehalogenase-producing mutants were inducible; no constitutive mutant has yet been isolated. Most of the resistant mutants examined did not produce one or both of the dehalogenase, and over half of those tested failed to revert back to the parental (strain PP3) phenotype, indicating that the observed mutations involved high-frequency deletion of DNA base sequences affecting expression of genes encoding dehalogenases and associated permease(s).
Klebsiella pneumoniae in orange juice concentrate
Authors: Fuentes F A , Hazen T C , López-Torres A J , Rechani P
Published: January 2020

Fecal coliform-positive, capsule-forming Klebsiella pneumoniae cells were observed in high densities (10(4) to 10(8) CFU/100 ml) in two commercial batches of frozen orange juice concentrate at a cannery in Puerto Rico. Contamination of both lots was gross and included off colors and odors. Isolates of K. pneumoniae from these concentrates revealed growth at 4, 25, and 34 degrees C with generation times from 0.39 to 1.84 h.
pULB113, an RP4::mini-Mu plasmid, mediates chromosomal mobilization and R-prime formation in Erwinia amylovora, Erwinia chrysanthemi, and subspecies of Erwinia carotovora
Authors: Chatterjee A K , Ross L M , McEvoy J L , Thurn K K
Published: January 2020

The RP4::mini-Mu plasmid pULB113, transferred from Escherichia coli strain MXR, was stable and transfer proficient in Erwinia amylovora strain EA303, E. carotovora subsp. atroseptica strain ECA12, E. carotovora subsp. carotovora strain ECC193, and E. chrysanthemi strain EC183. The plasmid mobilized an array of Erwinia sp. chromosomal markers (E. amylovora: his+,ilv+,rbs+,ser+,thr+;E. chrysanthemi:arg+,his+,ilv+,leu+; E. carotovora subsp. atroseptica: arg+,gua+,leu+,lys+,pur+,trp+; E. carotovora subsp. carotovora: arg+,gua+,leu+,lys+,out+[export of enzymes],pur+,trp+), suggesting random interactions of the plasmid with the chromosomes. In E. carotovora subsp. carotovora, pULB113-mediated two-factor crosses revealed linkage between three auxotrophic markers and the out loci. The export of pectate lyase, polygalacturonase, and cellulase and the maceration of potato tuber tissue occurred with Out+, but not Out-, strains of E. carotovora subsp. carotovora, indicating the importance of enzyme export in plant tissue maceration. Erwinia sp. donors harboring pULB113 complemented mutations in various biosynthetic and catabolic genes (arg, gal, his, leu, met, pro, pur, thy) in Escherichia coli recA strains. Escherichia coli transconjugants harbored pULB113 primes as indicated by the cotransfer of Erwinia genes and pULB113 markers and a change in plasmid mass. Moreover, the PstI and SmaI cleavage patterns of selected pULB113 primes were different from those of pULB113. pULB113 primes carried DNA insertions ranging from 3 to about 160 kilobases. These findings indicate that pULB113 is useful for in vivo gene cloning and genetic analysis of various enterobacterial phytopathogens.
Metabolism of the benzidine-based azo dye Direct Black 38 by human intestinal microbiota
Authors: Manning B W , Cerniglia C E , Federle T W
Published: January 2020

Benzidine-based azo dyes are proven mutagens and have been linked to bladder cancer. Previous studies have indicated that their initial reduction is the result of the azo reductase activity of the intestinal microbiota. Metabolism of the benzidine-based dye Direct Black 38 was examined by using a semicontinuous culture system that simulates the lumen of the human large intestine. The system was inoculated with freshly voided feces, and an active flora was maintained as evidenced by volatile fatty acid and gas production. Within 7 days after exposure to the dye, the following metabolites were isolated and identified by gas chromatography-mass spectrometry:benzidine, 4-aminobiphenyl, monoacetylbenzidine, and acetylaminobiphenyl. Benzidine reached its peak level after 24 h, accounting for 39.1% of the added dye. Its level began to decline, and by day 7 the predominant metabolite was acetylaminobiphenyl, which accounted for 51.1% of the parent compound. Formation of the deaminated and N-acetylated analogs of benzidine, which have enhanced mutagenicity and lipophilicity, previously has not been attributed to the intestinal microbiota.
Isolation and Characterization of a Moderately Halophilic Methanogen from a Solar Saltern
Authors: Mathrani Indra M. , Boone David R.
Published: January 2020

A moderately halophilic methanogenic bacterium was enriched with trimethylamine and isolated from the sediment of a solar salt pond (total dissolved solids of pond water, 250 g/liter; pH 7.5). The isolate (strain SF1, DSM 3243) was an irregular coccus which stained gram negative, with a diameter of 1 μm and a thin monolayered cell wall. The organism grew singly, in pairs, and in irregular clumps. Colonies were tannish yellow, circular, with entire edges, and about 1 mm in diameter within 1 week. Only methylamines or methanol was used for growth and methanogenesis. Most rapid growth (doubling time, 10.2 h) occurred at a temperature of 37°C and a pH of 7.4. The optimum NaCl concentration was 2.1 M. Yeast extract or rumen fluid was required. The isolate was lysed by sodium dodecyl sulfate (0.1 g/liter) and was sensitive to chloramphenicol. The G+C content of the DNA was 41 (±1) mol%.
Regulation of β-1, 4-Glucosidase Expression by
Candida wickerhamii
Authors: Freer S. N. , Detroy R. W.
Published: January 2020

Candida wickerhamii
NRRL Y-2563 expressed β-glucosidase activity (3 to 8 U/ml) constitutively when grown aerobically in complex medium containing either glycerol, succinate, xylose, galactose, or cellobiose as the carbon source. The addition of a high concentration of glucose (>75 g/liter) repressed β-glucosidase expression (<0.3 U/ml); however, this yeast did produce β-glucosidase when the initial glucose concentration was ≤50 g/liter. When grown aerobically in medium containing glucose plus the above-listed carbon sources, diauxic utilization of the carbon source was observed and the expression of β-glucosidase was glucose repressed. Surprisingly, glucose repression did not occur when the cells were grown anaerobically. When grown anaerobically in medium containing 100 g of glucose per liter,
C. wickerhamii
produced 6 to 9 U of enzyme per ml and did not demonstrate diauxic utilization of glucose-cellobiose mixtures. To our knowledge, this is the first report of apparent derepression of a glucose-repressed enzyme by anaerobiosis.
Microbial incidence in upper respiratory tracts of workers in the paper industry
Authors: Niemelä S I , Väätänen P , Mentu J , Jokinen A , Jäppinen P , Sillanpää P
Published: January 2020

The incidence of microbes in the nasal cavities of workers in three paper and board mills was investigated. A total of 234 persons exposed to microbial aerosols and splashes from paper machine wires and debarker drums formed the exposed group. The control group consisted of 294 workers from the dry working areas: the winding and packing sections. Chi-square analysis was used to test the differences in the frequency of microbial incidence and various symptoms between the exposed and control groups. The nasal cavities of many workers, particularly workers in the debarkers, proved to be contaminated by Klebsiella pneumoniae, other coliforms, yeasts, and molds; usually only one microbe was involved, but sometimes two or several species were found. Nasal bacteria and yeasts were largely derived from the mill and debarker air; the microbes in the air came mainly from process waters. Lack of association of nasopharyngeal symptoms with either exposure to aerosols or nasal microbial contamination was interpreted as an indication of host defenses that were adequate to protect workers from harmful microbial colonization in paper mill environments.
Genetic Recombination in the Lignin-Degrading Basidiomycete
Phanerochaete chrysosporium
Authors: Alic Margaret , Gold Michael H.
Published: January 2020

Heterokaryons made from auxotrophic strains of the lignin-degrading basidiomycete
Phanerochaete chrysosporium
were induced to fruit. The isolation of wild-type and double-mutant phenotypes from these crosses indicated that genetic recombination had occurred. Cytological studies demonstrated that more than 90% of the basidiospores from the wild-type and auxotrophic strains and from forced heterokaryons were binucleate. Colonies of the wild-type strain of
P. chrysosporium
arising from single, predominantly uninucleate conidia were all capable of producing fruit bodies and basidiospores.
Degradation of the Isoflavone Biochanin A and Its Glucoside Conjugates by
Ascochyta rabiei
Authors: Kraft Birgit , Barz Wolfgang
Published: January 2020

Strains of
Ascochyta rabiei
which are pathogenic to chickpea (
Cicer arietinum
L.) readily catabolized the main chickpea isoflavone biochanin A (5,7-dihydroxy-4′-methoxyisoflavone). 3′-Hydroxylation and O-demethylation reactions led to the isoflavones pratensein, genistein, and orobol, which were rapidly further degraded. Dihydrogenistein and
p
-hydroxyphenylacetic acid were also identified as catabolites. Biochanin A-7-
O
-glucoside was degraded, leading to aglycone and pratensein. Biochanin A-7-
O
-glucoside-6″-
O
-malonate, the main phenolic constituent of chickpea, was very slowly degraded without subsequent accumulation of catabolites.
Composition and Toxicity of the Inclusion of
Bacillus thuringiensis
subsp.
israelensis
Authors: Insell J. P. , Fitz-James P. C.
Published: January 2020

The multisegmented ovoidal inclusion of
Bacillus thuringiensis
subsp.
israelensis
was found to be composed of two structurally and biochemically distinct components. Electron microscopy of the inclusion revealed it to be composed mainly of osmiophobic or lightly stained segments crystallized in a lattice showing a repeat of approximately 4.3 nm. These light segments of the inclusions were shared by osmiophylic darkly stained segments with a crystal lattice repeat of approximately 7.8 nm. The lightly stained segments were soluble at pH 9.2 in sodium dodecyl sulfate-dithiothreitol-Tris-hydrochloride. The extracts of lightly stained segments were lytic to mammalian erythrocytes, and the precipitate obtained by lowering the pH to 5.2 was toxic to the larvae of
Aedes egypti.
The dark inclusion segments remaining, besides being much less toxic to larvae, were nonlytic to erythrocytes and were soluble at pH 10.5 in sodium dodecyl sulfate-dithiothreitol-Tris-hydrochloride. The light segment was composed of two major polypeptide doublets with molecular weights of 145,000 and 135,000, and 27,000 and 26,500, and the dark segments were composed of a single major polypeptide with a molecular-weight of 70,000. Hence, the inclusion of
B. thuringiensis
subsp.
israelensis
is more complex than previously reported, and we conclude that the toxin may be the polypeptide with a molecular weight of 27,000 and 26,500.
Degradation and Mineralization of the Polycyclic Aromatic Hydrocarbons Anthracene and Naphthalene in Intertidal Marine Sediments
Authors: Bauer James E. , Capone Douglas G.
Published: January 2020

The degradation of the polynuclear aromatic hydrocarbons (PAHs) anthracene and naphthalene by the microbiota of intertidal sediments was investigated in laboratory studies. No mineralization of either PAH was observed in the absence of oxygen. Both rates and total amounts of PAH mineralization were strongly controlled by oxygen content and temperature of the incubations. Inorganic nitrogen and glucose amendments had minimal effects on PAH mineralization. The rates and total amounts of PAH mineralized were directly related to compound concentration, pre-exposure time, and concentration. Maximum mineralization was observed at the higher concentrations (5 to 100 μg/g [ppm]) of both PAHs. Optimal acclimation to anthracene and naphthalene (through pre-exposures to the compounds) occurred at the highest acclimation concentration (1,000 ppm). However, acclimation to a single concentration (100 ppm) resulted in initial relative mineralization rates over a range of re-exposure concentrations (1 to 1,000 ppm) being nearly identical. Maximum mineralization of both PAHs occurred after intermediate periods (1 to 2 weeks) of pre-exposure. The fraction of the total heterotrophic population capable of utilizing anthracene or naphthalene as sole carbon source was also greatest after 2 weeks.
Cellulolytic Activity of
Clostridium acetobutylicum
Authors: Lee Song F. , Forsberg Cecil W. , Gibbins L. N.
Published: January 2020

Clostridium acetobutylicum
NRRL B527 and ATCC 824 exhibited extracellular and cell-bound endoglucanase and cellobiase activities during growth in a chemically defined medium with cellobiose as the sole source of carbohydrate. For both strains, the endoglucanase was found to be mainly extracellular (70 to 90%) during growth in continuous or batch cultures with the pH maintained at 5.2, whereas the cellobiase was mainly cell associated (60 to 90%). During continuous cultivation of strain B527 with cellobiose as the limiting nutrient, maximum production of the endoglucanase and cellobiase occurred at pH values of 5.2 and 4.8, respectively. In the carbon-limited continuous cultures, strain 824 produced similar levels of endoglucanase, cellobiosidase, and cellobiase activities regardless of the carbon source used. However, in ammonium- or phosphate-limited cultures, with an excess of glucose, only 1/10 of the endoglucanase was produced, and neither cellobiosidase nor cellobiase activities were detectable. A crude extracellular enzyme preparation from strain B527 hydrolyzed carboxymethylcellulose and phosphoric acid-swollen cellulose readily and microcrystalline cellulose (A vicel) to a lesser extent. Glucose accounted for more than 90% of the reducing sugar produced by the hydrolysis of acid-swollen cellulose and Avicel. Strain B527 did not grow in medium with acid-swollen cellulose as the sole source of carbohydrate, although it grew readily on the products obtained by hydrolyzing the cellulose in vitro with a preparation of extracellular cellulase derived from the same organism.
Methane Fermentation of Ferulate and Benzoate: Anaerobic Degradation Pathways
Authors: Grbić-Galić D. , Young L. Y.
Published: January 2020

The anaerobic biodegradation of ferulate and benzoate in stabilized methanogenic consortia was examined in detail. Up to 99% of the ferulate and 98% of the benzoate were converted to carbon dioxide and methane. Methanogenesis was inhibited with 2-bromoethanesulfonic acid, which reduced the gas production and enhanced the buildup of intermediates. Use of high-performance liquid chromatography and two gas chromatographic procedures yielded identification of the following compounds: caffeate,
p
-hydroxycinnamate, cinnamate, phenylpropionate, phenylacetate, benzoate, and toluene during ferulate degradation; and benzene, cyclohexane, methylcyclohexane, cyclohexanecarboxylate, cyclohexanone, 1-methylcyclohexanone, pimelate, adipate, succinate, lactate, heptanoate, caproate, isocaproate, valerate, butyrate, isobutyrate, propionate, and acetate during the degradation of either benzoate or ferulate. Based on the identification of the above compounds, more complete reductive pathways for ferulate and benzoate are proposed.
Effects of Chemical Speciation on the Mineralization of Organic Compounds by Microorganisms
Authors: Madsen E. L. , Alexander Martin
Published: January 2020

The mineralization of 1.0 to 100 ng each of four complexing compounds—oxalate, citrate, nitrilotriacetate (NTA), and EDTA—per ml was tested in media prepared in accordance with equilibrium calculations by a computer program so that the H, Ca, Mg, Fe, or Al complex (chemical species) was predominant. Sewage microorganisms mineralized calcium citrate more rapidly than iron, aluminum, or hydrogen citrate, and magnesium citrate was degraded slowest. Aluminum, hydrogen, and iron oxalates were mineralized more rapidly than calcium oxalate, and magnesium oxalate was decomposed slowest. Sewage microorganisms mineralized calcium NTA but not aluminum, magnesium, hydrogen, or iron NTA or any of the EDTA complexes.
Pseudomonas
sp. mineralized calcium and iron citrates but had no activity on hydrogen, aluminum, or magnesium citrate.
Pseudomonas pseudoalcaligenes
mineralized calcium, iron, hydrogen, and aluminum citrates but had little activity on magnesium citrate.
Pseudomonas alcaligenes
used calcium, iron, hydrogen, and aluminum oxalates readily, but it used magnesium oxalate at a slower rate.
Listeria
sp. destroyed calcium NTA but had no effect on hydrogen, iron, or magnesium NTA. Increasing the Ca concentration in the medium enhanced the breakdown of NTA by
Listeria
sp. The different activities of the bacterial isolates were not a result of the toxicity of the complexes or the lack of availability of a nutrient element. NTA mineralization was not enhanced by the addition of Ca to Beebe Lake water, but it was enhanced when Ca and an NTA-degrading inoculum were added to water from an oligotrophic lake. The data show that chemical speciation influences the mineralization of organic compounds by naturally occurring microbial communities and by individual bacterial populations.
Enumeration, Isolation, and Characterization of N
2
-Fixing Bacteria from Seawater
Authors: Guerinot Mary Lou , Colwell Rita R.
Published: January 2020

Marine pelagic N
2
-fixing bacteria have not, in general, been identified or quantified, since low or negligible rates of N
2
fixation have been recorded for seawater when blue-green algae (cyanobacteria) are absent. In the study reported here, marine N
2
-fixing bacteria were found in all samples of seawater collected and were analyzed by using a most-probable-number (MPN) method. Two different media were used which allowed growth of microaerophiles, as well as that of aerobes and facultative anaerobes. MPN values obtained for N
2
-fixing bacteria ranged from 0.4 to 1 � 10
3
per liter for water collected off the coast of Puerto Rico and from 2 to 5.5 � 10
2
per liter for Chesapeake Bay water. Over 100 strains of N
2
-fixing bacteria were isolated from the MPN tubes and classified, yielding four major groups of NaCl-requiring bacteria based on biochemical characteristics. Results of differential filtration studies indicate that N
2
-fixing bacteria may be associated with phytoplankton. In addition, when N
2
-fixing bacteria were inoculated into unfiltered seawater and incubated in situ, nitrogenase activity could be detected within 1 h. However, no nitrogenase activity was detected in uninoculated seawater or when bacteria were incubated in 0.2-μm-filtered (phytoplankton-free) seawater. The ability of these isolates to fix N
2
at ambient conditions in seawater and the large variety of N
2
-fixing bacteria isolated and identified lead to the conclusion that N
2
fixation in the ocean may occur to a greater degree than previously believed.
Oxygen Responses and Mat Formation by
Beggiatoa
spp
Authors: M�ller Mogens M. , Nielsen Lars P. , J�rgensen Bo B.
Published: January 2020

The behavioral response of single
Beggiatoa
sp. filaments moving on a gas-permeable membrane was studied by the combined use of microscopy and oxygen microelectrodes during controlled oscillations of oxygen tension. The bacteria reacted to increasing oxygen by reversing the direction of movement. The same step-up phobic response to oxygen was observed when a filament tip or loop glided into a stable microgradient of increasing oxygen. The response was sensitive to a change in oxygen tension of <5% of air saturation min
−1
. The response time was 20 to 50 s. Frequently, only part of the filament responded, which led to the formation of sharp bends, loops, and coils. This partial response facilitated the positioning of the long filaments within the narrow O
2
-H
2
S interface. The structure of whole
Beggiatoa
mats on sediment surfaces varied from loose to dense in relation to shallow or steep oxygen gradients in the 0.3- to 2-mm-thick, unstirred boundary layer. In an illuminated sediment
Beggiatoa
spp. lived together with photosynthetic organisms and migrated vertically in accordance with light/dark variations. The combined effect of phobic responses to light and oxygen can explain this migration.
Relationship between Rapid, Firm Adhesion and Long-Term Colonization of Roots by Bacteria
Authors: James Douglas W. , Suslow Trevor V. , Steinback Katherine E.
Published: January 2020

For rhizobacteria to exert physiological effects on plant growth, the bacteria must first effectively colonize the root surface. To examine the relationship between long-term colonization of root systems and adherence to roots in the short term, a binding assay was developed. Adherence was determined by incubating roots of intact radish seedlings with bacteria, washing and homogenizing the roots, and dilution plating the resulting homogenate. Irreversible binding of bacteria was rapid, reaching half-maximum by 5 min. All of the rhizosphere bacteria tested showed similar, concentration-dependent binding (ranging from 10
4
to 10
8
CFU/ml), as well as long-term colonization of radish roots under sterile conditions.
Escherichia coli
, which is not a root colonizer, showed about 10-fold less binding, but still demonstrated concentration-dependent binding and rapid kinetics of adherence at high concentrations (10
6
to 10
8
CFU/ml). The bacteria tested were very different with respect to source or habitat and plant response, yet they showed similar concentration-dependent binding. There was no correlation between the relative hydrophobicities of the cell surfaces of strains and the adherence of the strains to roots. Binding of
Pseudomonas fluorescens
E6-22 was promoted by divalent cations (Ca
2+
and Mg
2+
) at concentrations of 5 to 10 mM, whereas monovalent cations (Na
+
and K
+
) had little effect; electrostatic phenomena may partially explain adherence in the short term, an important prelude to long-term colonization of root surfaces.
Inoculant Production with Diluted Liquid Cultures of
Rhizobium
spp. and Autoclaved Peat: Evaluation of Diluents,
Rhizobium
spp., Peats, Sterility Requirements, Storage, and Plant Effectiveness
Authors: Somasegaran P.
Published: January 2020

Fully grown broth cultures of various fast- and slow-growing rhizobia were deliberately diluted with various diluents before their aseptic incorporation into autoclaved peat in polypropylene bags (aseptic method) or mixed with the peat autoclaved in trays (tray method). In a factorial experiment with the aseptic method, autoclaved and irradiated peat samples from five countries were used to prepare inoculants with water-diluted cultures of three
Rhizobium
spp. When distilled water was used as the diluent, the multiplication and survival of rhizobia in the peat was similar to that with diluents having a high nutrient status when the aseptic method was used. In the factorial experiment, the mean viable counts per gram of inoculant were log 9.23 (strain TAL 102) > log 8.92 (strain TAL 82) > log 7.89 (strain TAL 182) after 24 weeks of storage at 28�C. The peat from Argentina was the most superior for the three
Rhizobium
spp., with a mean viable count of log 9.0 per g at the end of the storage period. The quality of inoculants produced with diluted cultures was significantly (
P
= 0.05) better with irradiated than with autoclaved peat, as shown from the factorial experiment. With the tray method, rhizobia in cultures diluted 1,000-fold or less multiplied and stored satisfactorily in the presence of postinoculation contaminants, as determined by plate counts, membrane filter immunofluorescence, and plant infection procedures. All strains of rhizobia used in both the methods showed various degrees of population decline in the inoculants when stored at 28�C. Fast- and slow-growing rhizobia in matured inoculants produced by the two methods showed significant (
P
< 0.01) decline in viability when stored at 4�C, whereas the viability of some strains increased significantly (
P
< 0.01) at the same temperature. The plant effectiveness of inoculants produced with diluted cultures and autoclaved peat did not differ significantly from that of inoculants produced with undiluted cultures and gamma-irradiated peat.
Incidence of bacteremia in stressed and unstressed populations of the blue crab, Callinectes sapidus
Authors: Welsh P C , Sizemore R K
Published: January 2020

The incidence of bacteremia in the blue crab, Callinectes sapidus, is reported to be in excess of 80%. Because these results have been controversial, a field study was initiated to determine the effect of commercial capture and handling stresses on the incidence and levels of infection in blue crabs. The majority (75%) of "unstressed" crabs which were captured individually and bled immediately upon removal from the water were bacteremic, with a geometric mean level of infection of 14 CFU/ml of hemolymph. Crabs collected by crab pot, confined within these pots for as long as 24 h, and sampled immediately after removal from the water had a similar mean level of infection. Crabs subjected to the stresses of commercial capture, handling, and transport showed a higher incidence of infection (91%) and a mean infection level of 46 CFU/ml. Injuries sustained by crabs during commercial handling are thought to be associated with the higher incidence of infection. Vibrio spp. were primarily responsible for progressive infections in commercially stressed crabs and were the predominant bacterial type in heavily infected crabs. Our results indicated that uninjured healthy crabs do not have sterile hemolymph but instead harbor low-level bacterial infections.
Effect of cleaning, milling, and baking on deoxynivalenol in wheat
Authors: Abbas H K , Mirocha C J , Pawlosky R J , Pusch D J
Published: January 2020

Samples of wheat naturally infected by Fusarium graminearum Schwabe were obtained from mills in Oklahoma, Missouri, Kansas, and Minnesota and fields in Nebraska and Kansas in 1982; they were analyzed for deoxynivalenol (DON). The wheat was milled, and DON was found throughout all the milling fractions (bran, shorts, reduction flour, and break flour). The DON recoveries for each mill run ranged from 90 to 98%. These samples, regardless of DON concentration, also gave similar fractional distributions of DON. The greatest (21 ppm [21 micrograms/g]) concentration of DON was found in the bran, and the smallest (1 ppm) was found in the break flour. Cleaning and milling were not effective in removing DON; DON was not destroyed in the bread baked from the naturally contaminated whole wheat flour, but the effect on its concentration in the samples analyzed varied, the reduction ranging from 19 to 69%. The percent reduction found in the cleaned wheat ranged from 6 to 19%. DON concentrations in the following commercially made breads, caraway rye, seedless rye, and pumpernickel, were 45 ppb (ng/g), 39 ppb, and 0 ppb, respectively. The limits of detection by gas chromatography-mass spectrometry and high-pressure liquid chromatography for DON were 0.5 and 10 ng, respectively.
Production of cloned human leukocyte interferon by Bacillus subtilis: optimal production is connected with restrained growth
Authors: Meyer H P , Fiechter A
Published: January 2020

Bacillus subtilis, transformed with a plasmid containing the human alpha-2 (leukocyte) interferon gene, was cultivated in batch and continuous culture in a complex medium. In continuous culture with dissolved oxygen of less than 10% of air saturation, the extracellular interferon titer decreased sharply when the growth rate was lower or higher than the optimal one (mu = 0.14 h-1). Thus, a relatively low growth rate was best for extracellular interferon production, and oxygen limitation enhanced interferon production. The mean output rate in batch culture after successful harvest was 20 X 10(6) IU/liter per h and the maximal output rate in continuous culture was 14 X 10(6) IU/liter per h.
Bacterial Biomass, Metabolic State, and Activity in Stream Sediments: Relation to Environmental Variables and Multiple Assay Comparisons
Authors: Bott T. L. , Kaplan L. A.
Published: January 2020

Bacterial biomass, metabolic condition, and activity were measured over a 16-month period in the surface sediments of the following four field sites with differing dissolved organic matter regimes: a woodlot spring seep, a meadow spring seep, a second-order stream, and a third-order stream. Total bacterial biomass was measured by lipid phosphate and epifluorescence microscopic counts (EMC), and viable biomass was measured by
14
C most probable number, EMC with 2-(
p
-iodophenyl)-3-(
p
-nitrophenyl)-5-phenyl tetrazolium chloride reduction, and ATP. Bacterial metabolic condition was determined from the percentage of respiring cells, poly-β-hydroxybutyrate concentrations, and adenylate energy charge. Activity measures included
14
C-lipid synthesis,
32
P-phospholipid synthesis, the rate of uptake of algal lysate dissolved organic carbon, and respiration, from which biosynthesis was calculated (dissolved organic carbon uptake corrected for respiration). Total bacterial biomass (from EMC) ranged from 0.012 to 0.354 μg of C/mg of dry sediment and was usually lowest in the third-order stream. The percentage of cells respiring was less than 25% at all sites, indicating that most bacteria were dormant or dead. Adenylate energy charge was measured only in the third-order stream and was uniformly low. Poly-β-hydroxybutyrate concentrations were greater in the woodlot spring seep than in the second- and third-order streams. Uptake of algal lysate dissolved organic carbon ranged from undetectable levels to 166 mg of C � m
−2
� h
−1
. Little community respiration could be attributed to algal lysate metabolism. Phospholipid synthesis ranged from 0.006 to 0.354 pmol � mg of dry sediment
−1
� h
−1
. Phospholipid synthesis rates were used to estimate bacterial turnover at the study sites. An estimated 375 bacterial generations per year were produced in the woodlot spring seep, and 67 per year were produced in the third-order stream.
Determination of the Hydrogenase Status of Individual Legume Nodules by a Methylene Blue Reduction Assay
Authors: Lambert Grant R. , Hanus F. Joe , Russell Sterling A. , Evans Harold J.
Published: January 2020

We adapted a method for the rapid screening of colonies of free-living
Rhizobium japonicum
for hydrogenase activity to determine the hydrogenase status of individual soybean nodules. Crude bacteroid suspensions from nodules containing strains known to be hydrogen uptake positive (Hup
+
) caused a localized decolorization of filter paper disks, whereas suspensions from nodules arising from inoculation with hydrogen uptake-negative (Hup
−
) mutants or strains did not decolorize the disks. The reliability of the method was demonstrated by its successful application to 29 slow-growing rhizobia. The Hup phenotype on methylene blue filters agreed with that determined amperometrically with either methylene blue or oxygen as the electron acceptor.

Images
Low-Temperature Production of Urocanic Acid by Spoilage Bacteria Isolated from Mahimahi (
Coryphaena hippurus
)
Authors: Baranowski J. D.
Published: January 2020

Urocanic acid production was studied in 166 bacterial cultures isolated from mahimahi which had been stored for 14 days on ice in seawater. After 4 days of incubation at 10°C in histidine-supplemented Trypticase soy broth (BBL Microbiology Systems, Cockeysville, Md.), urocanic acid was measured by thin-layer chromatography. Fifty-eight of the cultures were positive for urocanic acid, with the eight most active isolates producing ca. 10 mg/100 ml. These observations, coupled with a report that urocanic acid may be the predominant histidine metabolite in fish held at low temperatures, all suggest that urocanic acid may be a useful alternative to histamine as a spoilage index in scombroid and other fish that are rich in endogenous histidine.
Toxigenic Potential of Some
Fusarium
Isolates from Southeast Asia
Authors: Greenhalgh Roy , Miller J. David , Neish Gordon A. , Schiefer H. Bruno
Published: January 2020

The isolation and characterization of 10 isolates of six
Fusarium
spp. from plant and soil samples collected in Southeast Asia is reported. The ability of these isolates to produce trichothecenes both in liquid cultures (CZ, GYEP, and MYRO) and on rice was assessed, and their toxigenic potential was examined by skin assay and gavage studies with culture filtrates. Although culture filtrates of all the isolates caused minor damage to test animals, only that of
F. equiseti
DAOM 189762 produced trichothecenes.
Multiphasic Kinetics for Transformation of Methyl Parathion by
Flavobacterium
Species
Authors: Lewis David L. , Hodson Robert E. , Freeman L. F.
Published: January 2020

Transformation rates of an insecticide, methyl parathion, in pure cultures of
Flavobacterium
sp. followed multiphasic kinetics involving at least two systems (I and II). System I was a high-affinity, low-capacity system, and system II was a low-affinity, high-capacity system. Data from rate experiments suggested that metabolites formed via system II inhibited system I such that only one system operated at a time. System I operated at approximately 20 μg liter
−1
and less; system II operated at approximately 4 mg liter
−1
and less. These results show that xenobiotic chemicals, like naturally occurring substrates, can be transformed via multiple uptake and transformation systems even by a pure culture. Furthermore, computer simulation models of pollutant transformation rates based on kinetic constants determined in this study show that large errors can occur in predicted rates when the multiphasicity of kinetics is neglected.
Nectaries as Entry Sites for
Aspergillus flavus
in Developing Cotton Bolls
Authors: Klich M. A. , Chmielewski M. A.
Published: January 2020

Cotton flowers in replicate plots in two fields near Phoenix, Ariz., were tagged in June at the beginning of the flowering period. Flowers or developing bolls from these tagged flowers were inoculated on the involucral (bracteal) nectaries with dry spores of
Aspergillus flavus.
The bolls were harvested as they matured in August, and the seeds were assessed for the presence of the fungus. The number of infected seed from flowers and bolls inoculated up to 25 days after anthesis was significantly higher than that in uninoculated controls. Seeds from bolls inoculated after 25 days postanthesis did not differ significantly from controls in degree of infection. We postulate that the sharp decline in the ability of the fungus to infect the plant and seed is a result of physical or biochemical changes in the boll as it reaches physiological maturity or biochemical changes in the entire plant as it develops.
Reassembly of a fimbrial hemagglutinin from Pseudomonas solanacearum after purification of the subunit by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis
Authors: Young D H , Stemmer W P , Sequeira L
Published: January 2020

Distilled water homogenates of Pseudomonas solanacearum B1, a highly fimbriated strain, strongly agglutinated human group A erythrocytes. The fimbriae and hemagglutinating activity were precipitated from the crude extract with 1% acetic acid, redissolved at pH 10, and precipitated again with 20 mM CaCl2 at pH 6.9. Ca2+, Mg2+, and Zn2+ had similar ability to precipitate the fimbrial hemagglutinin, but Na+ and K+ were much less effective. The fimbrial protein in the precipitate was purified to homogeneity by preparative gel electrophoresis in sodium dodecyl sulfate. The major protein band was eluted, and sodium dodecyl sulfate was removed by chromatography on ion retardation resin (AG 11A8) in 6 M urea. After dialysis against 10 mM sodium acetate (pH 4.5) to remove the urea, the protein reassembled to yield long fibers. These fibers were identical to fimbriae in the crude extract in diameter (6 nm) and in their ability to cause hemagglutination. The purified fimbriae contained no carbohydrates and wee similar to other bacterial fimbriae in amino acid composition, with hydrophobic amino acids comprising 41.8% of the total.
Comparison of gauze swabs and membrane filters for isolation of Campylobacter spp. from surface water
Authors: el-Sherbeeny M R , Bopp C , Wells J G , Morris G K
Published: January 2020

The epidemiology of Campylobacter jejuni indicates that waterborne transmission is important; the organism has been isolated from seawater, fresh water, and estuarine sites. Membrane filtration, with and without use of an enrichment broth, has been the most common method for isolating C. jejuni from water. We evaluated two methods for isolating C. jejuni from water: membrane filtration and gauze filtration. The membrane filters evaluated included 0.22- and 0.45-micron-pore Millipore filters (Millipore Corp., Bedford, Mass.), 0.2- and 0.4-micron-pore Nuclepore filters (Nucleopore Corp., Pleasanton, Calif.), and a 0.45-micron-pore Zetapor filters (AMF Cuno, Meridian, Conn.). The gauze filters included both Moore and Spira swabs. Of the membrane filters evaluated, the 0.45-micron-pore Millipore and Zetapor filters were the most sensitive for recovery of C. jejuni from seeded waters. The 0.45-micron-pore Millipore filter placed in Oosterom broth was better for recovery of C. jejuni from seeded stationary surface waters than either the Spira or Moore swab. However, the 0.45-micron-pore Millipore filter placed on a plate or in enrichment broth was equivalent to the Spira gauze swab when used to examine water from Atlanta area streams. C. jejuni organisms were isolated from 9 of 24 surface water samples representing 5 of 12 streams.
Application of cross-linked carboxymethyl cellulose degradation by beta-glucosidase and vaginal microbes to toxic shock syndrome
Authors: Sierks M R , Reilly P J
Published: January 2020

Eleven bacterial and two yeast strains, four of which were previously identified as having activity on a lightly cross-linked carboxymethyl cellulose (CLD-2) found in one type of superabsorbent tampon, were grown on a variety of substrates, most containing cellulosics. None produced detectable amounts of cellulases, but all elaborated beta-glucosidase. None of these 13 strains nor 3 commercially obtained beta-glucosidase preparations could hydrolyze CLD-2, although a commercial cellulase and two other bacterial preparations known to produce cellulases could. Based on these results, it appears that previous work suggesting that the degradation of CLD-2 by vaginal microbes and beta-glucosidase is implicated in the production by Staphylococcus aureus of toxin causing toxic shock syndrome must be reevaluated.
Parameters for the Operation of Bacterial Thiosalt Oxidation Ponds
Authors: Silver M.
Published: January 2020

Shake flask and pH-controlled reactor tests were used to determine the mathematical parameters for a mixed-culture bacterial thiosalt treatment pond. Values determined were as follows:

K
m

and
V
max
(thiosulfate), 9.83 g/liter and 243.9 mg/liter per h, respectively;

K
i

(lead), 3.17 mg/liter;

K
i

(copper), 1.27 mg/liter;
Q
10
between 10 and 30°C, 1.95. From these parameters, the required bioxidation pond volume and residence time could be calculated. Soluble zinc (0.2 g/liter) and particulate mill products and by-products (0.25 g/liter) were not inhibitory. Correlation with an operating thiosalt biooxidation pond showed the parameters used to be valid for thiosalt concentrations up to at least 2 g/liter, lead concentrations of at least 10 mg/liter, and temperatures of >2°C.
Structures of deepoxytrichothecene metabolites from 3'-hydroxy HT-2 toxin and T-2 tetraol in rats
Authors: Yoshizawa T , Sakamoto T , Kuwamura K
Published: January 2020

3'-Hydroxy HT-2 toxin and T-2 tetraol, in vivo metabolites of T-2 toxin, were orally administered to Wistar rats, and four metabolites having a trichothec-9,12-diene nucleus, which were termed deepoxytrichothecenes, were newly found in the excreta. Their structures were confirmed as 3'-hydroxy-deepoxy HT-2, 3'-hydroxy-deepoxy T-2 triol, 15-acetyl-deepoxy T-2 tetraol, and deepoxy T-2 tetraol on the basis of mass and nuclear magnetic resonance spectroscopy. Resolution of T-2 metabolites and corresponding deepoxytrichothecenes by gas-liquid and thin-layer chromatography was also described.
Ultrastructure of Sporulating
Bacillus larvae
in a Broth Medium
Authors: Bakhiet Nouna , Stahly Donald P.
Published: January 2020

An electron microscopic study of sporulation of
Bacillus larvae
, a honeybee pathogen, in TMYGP broth (D. W. Dingman and D. P. Stahly, Appl. Environ. Microbiol. 46:860-869, 1983) was conducted. No parasporal structures were evident in the sporangial cytoplasm. The stages of sporulation were similar to those observed in other sporeformers. A rather unusual inner coat layer consisting of seven lamellae was apparent.