bluuebunny/crossref_metadata_2025 huggingface dataset:
Adherence of bacteria, yeast, blood cells, and latex spheres to large-porosity membrane filters
Authors: Zierdt C H
Published: January 2020

Strong adherence of bacteria, yeast, erythrocytes, leukocytes, platelets, spores, and polystyrene spheres to membrane filter materials was noted during filtration through membranes with pore size diameters much larger than the particles themselves. Quantitative recovery on the membrane filters of these particles from low-concentration suspensions was achieved during gravity- or vacuum-assisted filtration through membranes with pore diameters as much as 30 times that of the filtered particles. Mechanical sieving was not responsible. The phenomenon was judged to be electrostatic. It could be partially blocked by pretreating the filter with a nonionic surfactant (Tween 20), and elution of adherent particles was achieved with 0.05% Tween 20. Gram-positive cocci were removed from suspension more efficiently than gram-negative rods. The commonly used cellulose membranes adsorbed more bacteria, blood cells, and other particles than did polycarbonate filters. Of lesser adsorptive capacity were vinyl acetate, nylon, acrylic, and Teflon membranes. Backwashing with saline, serum, 6% NaCl, dextran solutions, or phosphate buffers of varying molality and pH removed only a fraction of adherent particles. Tween 20 (0.05%) eluted up to 45% of adherent particles in a single back-filtration. Selected filters quantitatively removed the particles tested, which then could be washed and subjected to reagents for a variety of purposes. It is important to anticipate the removal of particles during membrane filtration, since it is not a simple mechanical event.
Hydrolytic Enzyme Production by
Rhizobium
Authors: Martinez-Molina Eustoquio , Morales Victor M. , Hubbell David H.
Published: January 2020

Cellulase and hemicellulase activity was detected in temperate (infective and noninfective) and tropical strains (infective) of
Rhizobium.
Hydrolytic enzymes were initially detected by a cup-plate assay. The presence of cellulase and hemicellulase was confirmed by viscometric assay. Implications of the presence of these enzymes in
Rhizobium
are discussed.
Inhibition by sulfide of nitric and nitrous oxide reduction by denitrifying Pseudomonas fluorescens
Authors: Sørensen J , Tiedje J M , Firestone R B
Published: January 2020

The influence of low redox potentials and H2S on NO and N2O reduction by resting cells of denitrifying Pseudomonas fluorescens was studied. Hydrogen sulfide and Ti(III) were added to achieve redox potentials near -200 mV. The control without reductant had a redox potential near +200 mV. Production of 13NO, [13N]N2O, and [13N]N2 from 13NO3- and 13NO2- was followed. Total gas production was similar for all three treatments. The accumulation of 13NO was most significant in the presence of sulfide. A parallel control with autoclaved cells indicated that the 13NO production was largely biological. The sulfide inhibition was more dramatic at the level of N2O reduction; [13N]N2O became the major product instead of [13N]N2, the dominant product when either no reductant or Ti(III) was present. The results indicate that the specific action of sulfide rather than the low redox potential caused a partial inhibition of NO reduction and a strong inhibition of N2O reduction in denitrifying cells.
Alkali method for rapid recovery of Yersinia enterocolitica and Yersinia pseudotuberculosis from foods
Authors: Aulisio C C , Mehlman I J , Sanders A C
Published: January 2020

A new culture method employing a potassium hydroxide treatment was compared with the conventional cold enrichment method for efficacy in recovering Yersinia sp. from naturally and artificially contaminated food. The new method increased the yield of Yersinia sp. fourfold and the sensitivity 100-fold, shortened the incubation period, and appreciably decreased the growth of non-Yersinia bacteria from a variety of meats, shellfish, and vegetables.
Tenax-GC Extraction Technique for Residual Polychlorinated Biphenyl and Polyaromatic Hydrocarbon Analysis in Biodegradation Assays
Authors: Shiaris M. P. , Sherrill T. W. , Sayler G. S.
Published: January 2020

A rapid Tenax-GC extraction technique has been evaluated for use in conjunction with aqueous biodegradation assays for polyaromatic hydrocarbons and polychlorinated biphenyls. The method was quantitatively efficient and reproducible for phenanthrene, but variable and not quantitative for Aroclor 1254 (polychlorinated biphenyls). Aqueous sample volumes and varying concentrations of organic matter influenced polychlorinated biphenyl and polyaromatic hydrocarbon extraction efficiency. Phenanthrene recovery was decreased by soil extract but unaffected by spent bacteriological culture medium. Both types of organic matter caused significant reduction of Aroclor 1254 recovery. Polyaromatic hydrocarbon and polychlorinated biphenyl biodegradation assays, performed with reservoir samples, supported the laboratory evaluation. The study demonstrated the utility of the Tenax-GC extraction technique for phenanthrene analysis in biodegradation assessment; however, Tenax-GC extraction was not appropriate for Aroclor 1254 biodegradation studies.
Anaerobic Methane Oxidation: Occurrence and Ecology
Authors: Zehnder Alexander J. B. , Brock Thomas D.
Published: January 2020

Anoxic sediments and digested sewage sludge anaerobically oxidized methane to carbon dioxide while producing methane. This strictly anaerobic process showed a temperature optimum between 25 and 37°C, indicating an active microbial participation in this reaction. Methane oxidation in these anaerobic habitats was inhibited by oxygen. The rate of the oxidation followed the rate of methane production. The observed anoxic methane oxidation in Lake Mendota and digested sewage sludge was more sensitive to 2-bromoethanesulfonic acid than the simultaneous methane formation. Sulfate diminished methane formation as well as methane oxidation. However, in the presence of iron and sulfate the ratio of methane oxidized to methane formed increased markedly. Manganese dioxide and higher partial pressures of methane also stimulated the oxidation. The rate of methane oxidation in untreated samples was approximately 2% of the CH
4
production rate in Lake Mendota sediments and 8% of that in digested sludge. This percentage could be increased up to 90% in sludge in the presence of 10 mM ferrous sulfate and at a partial pressure of methane of 20 atm (2,027 kPa).
Association of
Azospirillum
with Grass Roots
Authors: Umali-Garcia Mercedes , Hubbell David H. , Gaskins Murray H. , Dazzo Frank B.
Published: January 2020

The association between grass roots and
Azospirillum brasilense
Sp 7 was investigated by the Fahraeus slide technique, using nitrogen-free medium. Young inoculated roots of pearl millet and guinea grass produced more mucilaginous sheath (mucigel), root hairs, and lateral roots than did uninoculated sterile controls. The bacteria were found within the mucigel that accumulated on the root cap and along the root axes. Adherent bacteria were associated with granular material on root hairs and fibrillar material on undifferentiated epidermal cells. Significantly fewer numbers of azospirilla attached to millet root hairs when the roots were grown in culture medium supplemented with 5 mM potassium nitrate. Under these growth conditions, bacterial attachment to undifferentiated epidermal cells was unaffected. Aseptically collected root exudate from pearl millet contained substances which bound to azospirilla and promoted their adsorption to the root hairs. This activity was associated with nondialyzable and proteasesensitive substances in root exudate. Millet root hairs adsorbed azospirilla in significantly higher numbers than cells of
Rhizobium, Pseudomonas, Azotobacter, Klebsiella
, or
Escherichia.
Pectolytic activities, including pectin transeliminase and endopolygalacturonase, were detected in pure cultures of
A. brasilense
when this species was grown in a medium containing pectin. These studies describe colonization of grass root surfaces by
A. brasilense
and provide a possible explanation for the limited colonization of intercellular spaces of the outer root cortex.
Evaluation by electron microscopy and anaerobic culture of types of rumen bacteria associated with digestion of forage cell walls
Authors: Akin D E
Published: January 2020

Different morphological types of rumen bacteria which degraded cell walls of forage grasses with various in vitro digestibilities were evaluated with electron microscopy. The majority of these bacteria (i.e., about 70% or more) consisted of two distinct types: (i) encapsulated cocci and (ii) irregularly shaped bacteria, resembling major fiber digesters found in the rumen. Each type was capable of degrading structurally intact cell walls. Differences (P less than or equal to 0.02) in the percent ratio of encapsulated cocci to irregularly shaped bacteria were observed between Bermuda grass and fescue; the ratio of encapsulated cocci to irregularly shaped bacteria between Bermuda grass and orchard grass was similar and variations were high. The proportion of irregularly shaped bacteria usually increased with increased time of digestion. Differences (P greater than 0.1) were not found in the percentage ratio of encapsulated cocci to irregularly shaped bacteria attached to specific tissue types in either Bermuda grass or fescue. However, encapsulated cocci tended to be more prevalent on sclerenchyma than other tissues in Bermuda grass, but less prevalent on sclerenchyma than other tissues in fescue. Transmission electron microscopy of tissue digestion of rapidly degraded orchard grass blades revealed that mesophyll, parenchyma bundle sheath, and parts of the epidermal cell wall apparently were degraded without direct attachment of bacteria although bacteria were near the cell walls undergoing digestion. Anaerobic growth studies showed that the total culturable bacteria developing on medium 10 and media containing carbohydrates similar to those in forage cell walls (i.e., pectin, xylan, and cellobiose) were 80% higher from rumen bacterial populations adapted in vitro to cell walls of orchard grass compared to those from Bermuda grass; the number of colonies from the orchard grass-adapted population was significantly (P less than or equal to 0.05) greater on the medium containing xylan. Filter paper tests showed that the cellulolytic activity of populations adapted to fescue was greater than that of orchard grass or Bermuda grass.
Technique for determining total bacterial virus counts in complex aqueous systems
Authors: Ewert D L , Paynter M J
Published: January 2020

A direct method is described for measuring bacteriophage concentrations in complex aqueous systems. Conditions for sample clarification, phage recognition, and recovery were optimized. In contrast to the plaque assay, this procedure permits quantitation of total numbers of phages independent of bacterial host. Also, the modifications increase the sensitivity of the sedimentation assay, permitting detection of particles at a minimum concentration of 10(4) per ml. Maximal total phage concentrations in the aqueous phase of sewage and activated sludge mixed liquor were 1.3 x 10(6) and 4.3 x 10(7) per ml, respectively.
Potential Health Hazards from Microbial Aerosols in Densely Populated Urban Regions
Authors: Cronholm Lois S.
Published: January 2020

Aerosolized bacteria were recovered up to 930 m downwind of three sewage treatment plants in Jefferson County, Ky. This distance includes homes in the proximity of several hundred such plants in that county. Bacterial counts were elevated on foliage near activated sludge tanks; although these counts decreased rapidly, at 48 h after exposure they were significantly higher than the counts on unexposed leaves. The 50% lethal dose of aerosolized
Klebsiella pneumoniae
was comparable to the 50% lethal dose of a virulent clinical isolate, and enteric bacteria were recovered from the respiratory organs of mice after forced inhalation adjacent to an aerated sludge tank. The coliform density in the effluents of the plants tested was inversely related to the airborne bacterial load at those plants. This relationship was attributed to the correlation between effluent quality and extent of aeration of activated sludge. Wind direction and distance influenced the airborne counts, but the extreme variation in counts indicates that it is not possible to predict emission rates accurately in an open ecosystem. Airborne enteric bacteria also were isolated near a decorative fountain used by humans for wading. The discovery of these sources of aerosolized microorganisms from polluted waters in densely populated areas suggests that a potential health hazard may be created by the increased probability of inhaling and ingesting microorganisms of fecal origin.
Kinetics of Manganese Oxidation by Cell-Free Extracts of Bacteria Isolated from Manganese Concretions from Soil
Authors: Douka Catherine E.
Published: January 2020

A study of the kinetics of Mn
2+
oxidation catalyzed by cell extracts of two bacterial isolates (E
1
,
Pseudomonas
III [new isolate] and E
4
,
Citrobacter freundii
) isolated from the core of manganese concretions from Greek soils is presented. The reaction velocity of Mn
2+
oxidation was determined from the rate of consumption of Mn
2+
. The oxidation of Mn
2+
was followed by measuring changes in Mn
2+
concentration by activation analysis and by atomic absorption spectrophotometry. The reaction velocity was directly proportional to cell extract concentration when the reaction time was 1 h. At longer reaction times, the relationship deviated from linearity because substrate concentration became limiting. The rate of Mn
2+
oxidation increased with the Mn
2+
concentration. Analysis of the results by application of the integrated Michaelis equation for determining Michaelis constants and maximal velocities either in the presence (
K

m

= 3.33 μmol/ml and
V
max
= 1.25 μmol/ml·h) or in the absence of maleate buffer (
K

m

= 2.52 μmol/ml and
V
max
= 2.04 μmol/ml·h) indicated a strong affinity between the oxidizing system and manganese. All results in this study are consistent with an enzymatic manganese-oxidizing system and give an indication of the mechanism of biological Mn
2+
oxidation in soil which differs from that in the marine environment.
Digestion of algin by Pseudomonas maltophilia and Pseudomonas putida
Authors: von Riesen V L
Published: January 2020

Pseudomonas maltophilia and Pseudomonas putida were identified as alginolytic species. Two media used for demonstrating alginolytic activity are described. The applied aspects of the ability of these two species to digest algin are discussed.
Antibiotic Resistance and Its Transfer Among Clinical and Nonclinical
Klebsiella
Strains in Botanical Environments
Authors: Talbot Henry W. , Yamamoto Deborah K. , Smith Martin W. , Seidler Ramon J.
Published: January 2020

A total of 183 isolates of
Klebsiella
from drinking water, market vegetables, wood, sawdust, industrial effluents, and human and animal origin were examined for susceptibility to 10 antibacterial agents. Incidence of resistance to two or more antibiotics tested was: 65% of the human clinical isolates, 59% among bovine mastitis, and 24% among the nonclinical isolates. The five different multiple resistance patterns among nonclinically derived
Klebsiella
were also found among the human and bovine mastitis isolates. Statistical analyses revealed that patterns of resistance among
Klebsiella
isolates from drinking water, market vegetables, and industrial effluents were highly correlated with each other and with resistance patterns of human clinical isolates. Antibiotic resistance was transferred between
Klebsiella
growing in two habitat-simulated environments (growing radish plants and aqueous sawdust suspensions). Transconjugants were detected in 5 of 21 and 6 of 21 mating pairs, respectively. Average transconjugants/donor ranged from 10
−3
to 10
−6
in Penassay broth, from 10
−6
to 10
−7
on radish plants, and from 10
−5
to 10
−8
in sawdust suspensions. Although antibiotic resistance transfer under simulated environmental conditions can occur, regrowth of clinical strains is probably the major cause for the widespread occurrence of antibiotic-resistant
Klebsiella
in the nonclinical environment.
Planktonic Marine Luminous Bacteria: Species Distribution in the Water Column
Authors: Ruby E. G. , Greenberg E. P. , Hastings J. W.
Published: January 2020

Luminous bacteria were isolated from oceanic water samples taken throughout the upper 1,000 m and ranged in density from 0.4 to 30 colony-forming units per 100 ml. Generally, two peaks in abundance were detected: one in the upper 100 m of the water column, which consisted primarily of
Beneckea
spp.; and a second between 250 and 1,000 m, which consisted almost entirely of
Photobacterium phosphoreum.
The population of
P. phosphoreum
remained relatively stable in abundance at one station that was visited three times over a period of 6 months. However, the abundance of luminous
Beneckea
spp. isolated from the upper waters fluctuated considerably; they were, as high as 30 colony-forming units per 100 ml in the spring and were not detected in the winter. Water samples from depths of 4,000 to 7,000 m contained less than 0.1 luminous colony-forming unit per 100 ml. The apparent vertical stratification of two taxa of oceanic luminous bacteria may reflect not only differences in physiology, but also depth-related, species-specific symbiotic associations.
Electrochemical detection and counting of Escherichia coli in the presence of a reducible coenzyme, lipoic acid
Authors: Junter G A , Lemeland J F , Selegny E
Published: January 2020

Reduction of lipoic acid by bacteria coupled to oxygen consumption during glucose absorption can be followed potentiometrically with a pair of gold and reference electrodes in a minimal culture medium. The variations in potential as a function of time have the shape of a wave. A theoretical expression was derived relating the size of the original inoculum to the time preceding the appearance of the wave. The validity of that relation was experimentally verified with Escherichia coli, and the time needed for a drop of 100 mV was determined. Detection of small inocula, e.g., down to a range of 10 viable E. coli per liter, is possible in about 11 h by yeast extract stimulation. The method, technically simple and adequately sensitive, suggests the possibility of automated detectors of bacterial contaminations.
Effect of Carbon Dioxide on Growth of Meat Spoilage Bacteria
Authors: Gill C. O. , Tan K. H.
Published: January 2020

The ability of CO
2
to inhibit respiration and growth of representative strains of seven species of meat spoilage bacteria was examined.
Enterobacter
and
Microbacterium thermosphactum
were unaffected by CO
2
. Both respiration and growth of the other species were inhibited. With four of the species (fluorescent and nonfluorescent
Pseudomonas, Alteromonas putrefaciens
, and
Yersinia enterocolitica
), the inhibition pattern in a complex medium was similar, and inhibition was incomplete and reached a maximum level at comparatively low concentrations of CO
2
. With
Acinetobacter
, inhibition continued to increase with increasing CO
2
concentration. The degree of inhibition with a constant concentration of CO
2
in solution increased with decreasing temperature for all CO
2
-susceptible species except the nonfluorescent
Pseudomonas.
Anaerobic growth of CO
2
-susceptible facultative anaerobes was unaffected by CO
2
.
Laboratory Comparison of the Effectiveness of Several Algicides on Isolated Swimming Pool Algae
Authors: Adamson R. P. , Sommerfeld M. R.
Published: January 2020

The most frequently encountered species of algae found in swimming pools in the Phoenix metropolitan area were used to evaluate the laboratory effectiveness of five commercially available pool chemicals used for algal control. The pool algae used were the xanthophyte
Pleurochloris pyrenoidosa
, the chlorophyte
Oocystis
sp., and the cyanophytes
Phormidium minnesotense
and
Plectonema
sp. Pad Algae Kill (a chlorine derivative) was effective in the control of all test organisms. Algaedyn, a silver-containing algicide, was effective on
P. minnesotense
and
Plectonema
sp., but caused only a slight inhibition in the growth of
P. pyrenoidosa
and
Oocystis
sp. Quarternary ammonium (Padicide) was more effective in controlling the growth of
Phormidium
and
Plectonema
than
Pleurochloris
and
Oocystis.
Algimycin (herbicide) only reduced the growth of
Oocystis
and was ineffective on the other species. Bio-Gard (copper) reduced the growth of
Pleurochloris
, but had no effect on the other test organisms. The technique used to quantify the influence of algicides on isolated pool algae appears to be adaptable to those algae that form distinct colonies on an agar substratum.
Effect of Short-Term Chilling of Rumen Contents on Viable Bacterial Numbers
Authors: Dehority Burk A. , Grubb Jean A.
Published: January 2020

Anaerobic storage of whole rumen contents at 0°C for 8 and 24 h resulted in viable colony counts which were 113 and 92%, respectively, of the colony count obtained with an unstored sample. No significant differences in the percentages of the total population capable of utilizing glucose, cellobiose, starch, or xylose occurred with storage. Numerous factors were investigated as possible explanations for the increase in bacterial numbers observed after storage for 8 h in ice. Growth and multiplication of bacteria, subsampling of rumen contents, susceptibility to oxygen, lysis of protozoa with the release of viable bacteria, and rumen sampling time did not appear to be involved. Compilation of the data from all 29 of the above experiments gave a mean value for samples stored for 8 h in ice which was 134.8% of the control (P < 0.005). The effect of storage time at 0°C indicated that a significant increase in colony count occurred after 4 h, and, based on these data, 6 h was subsequently used as the standard cold-storage period. Circumstantial evidence supported the hypothesis that storage of rumen contents for 6 h at 0°C appears to alter or to break down the material responsible for cell-to-cell or cell-to-particulate matter attachment. Addition of a surfactant to the anaerobic dilution solution significantly increased total colony count of rumen contents to an extent similar to chilling in ice for 6 h. However, an additive effect was observed when surfactant-containing anaerobic dilution solution was used with samples stored for 6 h at 0°C.
Specific Strains of
Bacteroides
Species in Human Fecal Flora as Measured by Deoxyribonucleic Acid Homology
Authors: Johnson John L.
Published: January 2020

Membrane competition homology experiments were used to compare
Bacteroides uniformis
and
Bacteroides vulgatus
isolates obtained from fecal samples from different individuals and isolates obtained from fecal samples of single individuals. Isolates of
B. uniformis
, when isolated from different individuals, had interstrain deoxyribonucleic acid homology values that ranged from 63 to 95%, with most of the values being in the 70 to 85% range. When isolates obtained from a single individual were compared, each species was represented by one or two groups of very closely related organisms, with each group having essentially 100% interstrain homology. When strains from two groups were compared with each other, the homology values were in the same range as when organisms were isolated from different individuals. Isolates which have nearly 100% homology with each other persisted in fecal samples collected over a 5- to 6-month period. It appears that the colon of each person may be populated by bacterial strains that are specific for that individual. Somatic antigen serotyping has been used as an indicator for specific
Escherichia coli
strains in fecal samples. Two isolates having the same O, K, and H antigens had 99% homology, but when only O and H antigens were in common, the homology values were in the 70 to 85% range. It seems that isolates of a given serotype, when isolated from a single individual, may represent a unique strain, but isolates of a given serotype, when isolated from different individuals, probably do not.
Density Centrifugation Method for Recovering
Rhizobium
spp. from Soil for Fluorescent-Antibody Studies
Authors: Wollum A. G. , Miller R. H.
Published: January 2020

A density centrifugation procedure has been developed as a replacement for soil flocculation and clarification steps employed in quantitative fluorescent-antibody studies on
Rhizobium
in soils. Near-quantitative recovery of added cells of two strains of
Rhizobium japonicum
and two strains of
R. phaseoli
was achieved from six soils with various properties. It is proposed that this technique may prove useful in separating other soil microorganisms from soil particles in ecological studies employing fluorescent-antibody techniques.
Controlled formaldehyde fumigation system
Authors: Ackland N R , Hinton M R , Denmeade K R
Published: January 2020

A comparative study of formaldehyde (HCHO) fumigation was carried out by controlled vaporization, using an electric vapor generator, and by the Formalin-permanganate method. Determination of vapor levels as well as bactericidal action showed the generator to be more effective. Maximum achievable fumigant levels were temperature dependent and related to the equilibrium vapor concentration of HCHO. At a room temperature of 21 degrees C, vaporization of more than 2,000 micrograms of HCHO per liter resulted in conversion of HCHO to paraformaldehyde, which condensed on surfaces and contributed to prolonged residual vapor levels. An electronic monitor is described which is capable of detecting HCHO levels as low as 10 microgram/liter and can be used to monitor the complete fumigation process.
Specific Inhibition of Nitrite Oxidation by Chlorate and Its Use in Assessing Nitrification in Soils and Sediments
Authors: Belser L. W. , Mays E. L.
Published: January 2020

A method was developed to determine the ammonium oxidation rate (potential) of unenriched natural samples by measuring the nitrite produced in shaken slurries. Addition of chlorate to the samples prevented nitrite from being oxidized to nitrate. The effectiveness and specificity of chlorate were tested with pure cultures of nitrite and ammonium oxidizers, as well as in soil and sediment slurries. It was concluded that chlorate had relatively little inhibitory effect on ammonium oxidation. However, under some conditions chlorate was not completely effective in blocking nitrite oxidation, and the causes of this were investigated. The technique was designed to check for incomplete blockage.
Cell Surface Measurements in Hydrocarbon and Carbohydrate Fermentations
Authors: Neufeld R. J. , Zajic J. E. , Gerson D. F.
Published: January 2020

Acinetobacter calcoaceticus
was grown in 11-liter batch fermentations with hexadecane or sodium citrate as the sole source of carbon. Surface and interfacial tension measurements of the microbial broth indicated that surface-active compounds were being produced only during growth on the hydrocarbon substrate. Contact angle measurements of an aqueous drop on a smooth lawn of cells in a hexadecane bath indicated a highly hydrophobic surface of the cells in the initial stages of the hydrocarbon fermentation (120° contact angle). At this stage, the entire cell population was bound to the hydrocarbon-aqueous interface. The contact angle dropped rapidly to approximately 45° after 14 h into the fermentation. This coincided with a shift of the cell population to the aqueous phase. Thus, the cells demonstrated more hydrophilic characteristics in the later stages of the fermentation. Contact angles on cells grown on sodium citrate ranged from 18 to 24° throughout the fermentation. The cells appear to be highly hydrophilic during growth on a soluble substrate. From the contact angle and aqueous-hydrocarbon interfacial tension, the surface free energy of the cells was calculated along with the cell-aqueous and cell-hydrocarbon interfacial tension. The results of these measurements were useful in quantitatively evaluating the hydrophobic nature of the cell surface during growth on hydrocarbons and comparing it with the hydrophilic nature of the cell surface during growth on a soluble substrate.
Fixation of Dinitrogen-15 Associated with Rice Plants
Authors: Ito Osamu , Cabrera Delfin , Watanabe Iwao
Published: January 2020

Rice plants (IR26 and Latisail) obtained at near heading stage from a wetland field were transferred to water culture and exposed to
15
N
2
in a gas-tight growth chamber for 7 days to measure N
2
-fixing activities associated with the rice. The activities measured varied from 6.5 to 11.6 μmol of N
2
fixed per hill per day. The outer leaf sheath had about 2.5 times higher N
2
-fixing activities per unit weight than the root. Slight activities were also found in the basal node and inner leaf sheath. Wrapping basal parts of the stem with aluminum foil did not decrease the activities of N
2
fixation in these parts. Thus, the outer leaf sheath as well as the root are N
2
-fixing sites in rice plants. N
2
fixation found in above-ground parts is not due to photoautotrophic organisms. Less than 10% of the fixed nitrogen was translocated from the fixing sites to the leaf blades and the young panicles.
Microbial metabolism of N-nitrosodiethanolamine in lake water and sewage
Authors: Yordy J R , Alexander M
Published: January 2020

The carcinogenic nitrosamine, N-nitrosodiethanolamine (NDElA), was degraded in samples of sewage and two lake waters, and microorganisms were responsible for the transformation. However, the rate of NDElA disappearance was slow. In the samples of lake water, the rate and extent of NDElA metabolism varied with the time of year, and no disappearance occurred in samples taken in winter. The products formed from NDEIA were persistent in lake water. In sewage, no seasonal effect on the microbial conversion was evident, and the products of metabolism were slowly mineralized. NDElA is apparently converted to the same organic products in samples of all three environments. Although the products were not identified, the data suggest that they were modified dimers of NDElA.
Gas-liquid chromatography for evaluating polysaccharide degradation by Ruminococcus flavefaciens C94 and Bacteroides succinogenes S85
Authors: Collings G F , Yokoyama M T
Published: January 2020

Two predominant rumen cellulolytic bacteria, Ruminococcus flavefaciens C94 and Bacteroides succinogenes S85, were incubated with ground filter paper (Whatman no. 1), cattle manure fiber, wheat straw, Kentucky bluegrass, alfalfa, and corn silage as substrates. Analyses of the initial substrate and the recovered residue after 48 h of static incubation showed that R. flavefaciens C94 was quantitatively more effective than B. succinogenes S85 in degrading total dry matter (32.3% versus 16.1%). However, B. succinogenes S85 demonstrated a qualitative advantage in degrading the hemicellulose and hemicellulosic sugars of particular substrates. R. flavefaciens degraded a mean 29.7% of the cellulose and 35.6% of the hemicellulose in the various substrates, whereas B. succinogenes degraded a mean 17.9 and 31.6% of these fractions, respectively. Gas-liquid chromatography was an important aid in characterizing the polysaccharide-degrading capabilities of these rumen species.
Enumeration of Bacteriophages and Host Bacteria in Sewage and the Activated-Sludge Treatment Process
Authors: Ewert Donald L. , Paynter M. J. B.
Published: January 2020

Bacteriophage populations in an activated-sludge sewage treatment plant were enumerated. A newly developed assay for quantitation of total phages, employing direct electron microscopic counts, was used in conjunction with the plaque assay. The total concentration of phages was significantly higher in reactor mixed liquor and effluent than in influent sewage, indicating a net production of phages within the reactor. Maximum total phage concentrations in the fluid phase of sewage, activated-sludge mixed liquor, and reactor effluent were 2.2 × 10
7
, 9.5 × 10
7
, and 8.4 × 10
7
/ml, respectively. Conditions were optimized for isolation of predominant heterotrophic aerobic bacteria from sewage and mixed liquor. Blending at ice water temperatures was superior to ultrasound or enzyme treatments for maximum release of viable bacteria from microbial floc. A solidified extract of mixed liquor was superior to standard media for cultivating maximum numbers of heterotrophic bacteria. The highest culture counts for sewage and mixed liquor were 1.4 × 10
7
and 1.3 × 10
9
/ml, respectively, which represented only 3 and 6.8% of the total microscopic cell counts. Only 3 out of 48 dominant bacterial isolates from either mixed liquor or sewage were hosts for phages present in the system. The sum of phage populations infecting these three hosts accounted for, at best, 3.8% (sewage) and 0.2% (mixed liquor) of the total number of phages present. Generally, specific phage titers were lower in mixed liquor than in sewage, indicating that these hosts were not responsible for the net production of phages in the reactor. This study emphasizes the limitations of the plaque assay for ecological studies of phages, and it suggests that bacteria responsible for phage production in activated-sludge mixed liquor are either minor components of the heterotrophic population, floc-producing strains, or members of other physiological groups.
Distribution and Characterization of Kepone-Resistant Bacteria in the Aquatic Environment
Authors: Orndorff S. A. , Colwell R. R.
Published: January 2020

Effects of the chlorinated insecticide Kepone on the ecology of Chesapeake Bay and James River bacteria were studied. Kepone-resistant bacteria present in a given environment were found to reflect the degree of fecal and/or high organic pollution of the sampling sites, based on total numbers and generic composition of the populations of Kepone-resistant bacteria. The presence of Kepone-resistant bacteria was found to be correlated (α = 0.01) with total coliforms, fecal coliforms, and total aerobic viable heterotrophic bacteria, but not with Kepone concentration, since Kepone-resistant bacteria were present in locations where Kepone could not be detected by the analytical methods used in this study. Only gram-negative bacteria, predominantly
Pseudomonas, Vibrio
, and
Aeromonas
spp., were found to be resistant to ≥10 μg of Kepone per ml. Gram-positive bacteria, i.e.,
Bacillus
and
Corynebacterium
spp., were generally sensitive to ≥0.1 μg of Kepone per ml. From results of cluster analysis of taxonomic data, we determined that characteristics of Kepone-resistant bacteria included: resistance to pesticides and heavy metals; degradation of oil; positive oxidase and catalase reactions; and nitrate reduction. From results of the ecological and taxonomic analyses, we conclude that Kepone resistance in estuarine bacteria is due to the physicochemical composition of the gram-negative cell wall and not prior exposure to Kepone. Therefore, the presence of Kepone-resistant bacteria cannot serve as an indicator of Kepone contamination in the aquatic environment where gram-negative bacteria are predominant.
Computer analysis of Staphylococcus aureus phage typing data from 1957 to 1975, citing epidemiological trends and natural evolution within the phage typing system
Authors: Zierdt C H , Robertson E A , Williams R L , MacLowry J D
Published: January 2020

Computer analysis of Staphylococcus aureus phage ty ping data collected for over 18 years in a large research hospital showed a drastic decrease in the number of hospital epidemic strains. Phage lysis patterns gradually modified from those of earlier years and were a reflection of changes within the S. aureus reservoir, and not within the typing phages, since the typing phages were used from stable lyophilized stocks. There was increasing cross-lysis of S. aureus strains by phages of lytic groups I, II, and III, such that this grouping was no longer epidemiologically valid. A 61% increase in unique strains occurred from the period 1957 to 1975. Disappearance of the widely recognized epidemic strains was followed by a proliferation of unique strains with individual phage patterns. These increased from 38% in the period 1957 to 1962 to 62% in the period 1969 to 1975, indicating a trend toward a "one patient-one strain" situation. Nontypable strains decreased in more recent years from 16% (1957 to 1975) to 7% in 1978, following introduction of phages 94, 96, 292, and D-11. Pandemic S. aureus strain 80/81 first appeared in this hospital in 1959, 5 years after it was first reported in the United States. Strain 80/81 disappeared from the hospital in 1963, partly due to the advent of methicillin.
Growth of Iron-Oxidizing Thiobacilli in the Presence of Chalcopyrite and Galena
Authors: Kingma J. G. , Silver M.
Published: January 2020

Iron-oxidizing thiobacilli were adapted to grow on a chalcopyrite and a galena ore concentrate. When grown on the chalcopyrite concentrate, the bacteria exhibited a doubling time of 38.4 ± 2.9 h, with a final cellular protein concentration of 185 μg/ml and solubilization of 10.3 g of copper per liter. When grown on the galena ore concentrate, the generation time was 39.6 ± 2.7 h, with a final cellular protein concentration of 120 μg/ml. Galena was converted to lead salts soluble in 1 M ammonium acetate to a concentration of 20.2 g of lead per liter. X-ray diffraction and refractive-image analysis indicated that the smaller-sized particles were favored in this process. Galena was converted to anglesite, and soluble copper was liberated from chalcopyrite with the concurrent formation of jarosite.
Biology of
Azospirillum
-Sugarcane Association: Enhancement of Nitrogenase Activity
Authors: Berg R. Howard , Tyler Max E. , Novick Norman J. , Vasil Vimla , Vasil Indra K.
Published: January 2020

Azospirillum brasilense
was reisolated from associations with callus tissue cultures of sugarcane and compared with stock cultures of the inoculated bacterium and related strains. Although the reisolate had a growth rate similar to stock cultures, it exhibited a severalfold increase in maximum specific activity of nitrogenase. The reisolate and the parent culture had similar ultrastructure. The general ultrastructure of
Azospirillum
is described. The bacterium was capsulated when grown on nitrogen-free nutrient agar plates and on callus, but was not capsulated when growing in a subsurface zone in N-free semisolid nutrient agar, except rarely in aging cultures. Capsulation may be a protective mechanism against unfavorable pO
2
under dinitrogen-fixing conditions. Pleomorphism occurred in capsulated forms, and the ultrastructure of these forms is described.
New methods to assess bacterial injury in water
Authors: Zaske S K , Dockins W S , Schillinger J E , McFeters G A
Published: January 2020

Two methods are described for measurement of bacterial injury in water. Laboratory time preceding cell division measured with slide cultures and spheroplast formation after lysozyme treatment were accurate and rapid measurements of bacterial damage.
Simultaneous concentration of Salmonella and enterovirus from surface water by using micro-fiber glass filters
Authors: Rolland D , Block J C
Published: January 2020

A method using micro-fiber glass filters (8-micrometers porosity) at pH 3.5 was successfully used for simultaneous concentration of Salmonella and enterovirus from Meurthe River samples, collected 8 km south of Nancy, France. A concentration of 10-liter samples was indispensable and permitted recovery of several enterovirus and Salmonella serotypes in concentrations of 1.3 most probable number of cytopathogenic units per liter and 18 bacteria per liter, respectively.
Evaluation of various soil water samplers for virological sampling
Authors: Wang D S , Lance J C , Gerba C P
Published: January 2020

Two commercially available soil water samplers and a ceramic sampler constructed in our laboratories were evaluated for their ability to recover viruses from both tap water and secondary sewage effluent. The ceramic sampler consistently gave the best recoveries of viruses from water samples. Soil columns containing ceramic samplers at various depths provide a simple method for studying virus transport through sewage-contaminated soils.
Loss of effectiveness of preservative systems of mascaras with age
Authors: Bhadauria R , Ahearn D G
Published: January 2020

The preservative systems of unused, anhydrous mascaras were challenged periodically with microorganisms, using a modified membrane procedure. Shelf life of preservative activity against Pseudomonas aeruginosa varied for different brands from as little as 1 month to over 36 months. Generally, P. aeruginosa grew in mascaras after the mascaras were challenged first with Staphylococcus epidermidis or Candida albicans.
Carbon and Electron Flow in Mud and Sandflat Intertidal Sediments at Delaware Inlet, Nelson, New Zealand
Authors: Mountfort Douglas O. , Asher Rodney A. , Mays Edward L. , Tiedje James M.
Published: January 2020

An investigation of carbon and electron flow in mud and sandflat intertidal sediments showed that the terminal electron acceptor was principally sulfate and that the carbon flow was mainly to CO
2
. Studies with thin layers of sediment exposed to H
2
showed that methane production accounted for virtually none of the H
2
utilized, whereas sulfate reduction accounted for a major proportion of the gas uptake. At all sampling sites except one (site B7), rates of methanogenesis were low but sulfate concentrations in the interstitial water were high (>18 mM). At site B7, the sulfate concentrations declined with depth from 32 mM at 2 cm to <1 mM at 10 cm or below, and active methanogenesis occurred in the low-sulfate zone. Sulfate-reducing activity at this site initially decreased and then increased with depth so that elevated rates occurred in both the active and nonactive methanogenic zones. The respiratory index (RI) [RI =
14
CO
2
/(
14
CO
2
+
14
CH
4
)] for [2-
14
C]acetate catabolism at site B7 ranged from 0.98 to 0.2 in the depth range of 2 to 14 cm. Addition of sulfate to sediment from the low-sulfate zone resulted in an increase in RI and a decrease in methanogenesis. At all other sites examined, RI ranged from 0.97 to 0.99 and was constant with depth. The results suggested that although methanogenesis was inhibited by sulfate (presumably through the activity of sulfate-reducing bacteria), it was not always limited by sulfate reduction.
Microbial Oxidation of Gaseous Hydrocarbons: Production of Secondary Alcohols from Corresponding
n
-Alkanes by Methane-Utilizing Bacteria
Authors: Patel Ramesh N. , Hou C. T. , Laskin A. I. , Felix A. , Derelanko P.
Published: January 2020

Over 20 new strains of methane-utilizing bacteria were isolated from lake water and soil samples. Cell suspensions of these and of other known strains of methane-utilizing bacteria oxidized
n
-alkanes (propane, butane, pentane, hexane) to their corresponding secondary alcohols (2-propanol, 2-butanol, 2-pentanol, 2-hexanol). The product secondary alcohols accumulated extracellularly. The rate of production of secondary alcohols varied with the organism used for oxidation. The average rate of 2-propanol, 2-butanol, 2-pentanol, and 2-hexanol production was 1.5, 1.0, 0.15, and 0.08 μmol/h per 5.0 mg of protein in cell suspensions, respectively. Secondary alcohols were slowly oxidized further to the corresponding methylketones. Primary alcohols and aldehydes were also detected in low amounts (rate of production were 0.05 to 0.08 μmol/h per 5.0 mg of protein in cell suspensions) as products of
n
-alkane (propane and butane) oxidation. However, primary alcohols and aldehydes were rapidly metabolized further by cell suspensions. Methanol-grown cells of methane-utilizing bacteria did not oxidize
n
-alkanes to their corresponding secondary alcohols, indicating that the enzymatic system required for oxidation of
n
-alkanes was induced only during growth on methane. The optimal conditions for in vivo secondary alcohol formation from
n
-alkanes were investigated in
Methylosinus
sp. (CRL-15). The rate of 2-propanol and 2-butanol production was linear for the 40-min incubation period and increased directly with cell protein concentration up to 12 mg/ml. The optimal temperature and pH for the production of 2-propanol and 2-butanol were 40°C and pH 7.0. Metalchelating agents inhibited the production of secondary alcohols. The activities for the hydroxylation of
n
-alkanes in various methylotrophic bacteria were localized in the cell-free particulate fractions precipitated by centrifugation between 10,000 and 40,000 ×
g
. Both oxygen and reduced nicotinamide adenine dinucleotide were required for hydroxylation activity. The metal-chelating agents inhibited hydroxylation of
n
-alkanes by the particulate fraction, indicating the involvement of a metal-containing enzyme system in the oxidation of
n
-alkanes. The production of 2-propanol from the corresponding
n
-alkane by the particulate fraction was inhibited in the presence of methane, suggesting that the subterminal hydroxylation of
n
-alkanes may be catalyzed by methane monooxygenase.
Bacterial Contamination of Drinking Water Supplies in a Modern Rural Neighborhood
Authors: Lamka Karla G. , LeChevallier Mark W. , Seidler Ramon J.
Published: January 2020

On six occasions during a 15-month period, the private well and spring water supplies in a modern rural neighborhood of 78 households were examined for total coliforms, fecal coliforms,
Staphylococcus aureus
, and standard plate count bacteria. More than one-third of the water supplies were unsatisfactory on at least one occasion as judged by standard plate counts over 10
3
/ml and the presence of coliforms, fecal coliforms, and/or
S. aureus. Citrobacter freundii, Klebsiella pneumoniae
, and
Escherichia coli
were the most frequently isolated total coliforms. At least 12 other genera of bacteria were identified from standard plate count agar. Coliform contamination was found to be higher after periods of rainfall, and high standard plate counts were more prevalent during warmer weather. These observations probably reflect leakage of surface water into improperly sealed wells or aquifer contamination during winter and the lack of chlorination to control microbial regrowth during the warm season. An inverse correlation was found between the presence of high standard plate counts and incidence of coliforms. Consumer education and at least a twice yearly monitoring of private water supplies (winter and summer) are suggested methods to signal that treatment may be necessary to reduce the risk of waterborne disease.
Production of Eremofortins A, B, and C Relative to Formation of PR Toxin by
Penicillium roqueforti
Authors: Moreau S. , Lablache-Combier A. , Biguet J.
Published: January 2020

The production of various eremophilane-type sesquiterpenes by
Penicillium roqueforti
strains has allowed us to propose a biochemical pathway for PR toxin synthesis. A time-course study of
P. roqueforti
metabolite production by high-performance liquid chromatography was performed to check this hypothetical pathway. The results obtained suggested that eremofortin C was the direct precursor of PR toxin in the
P. roqueforti
cell. Attempts to determine the amount of PR toxin in the mycelium failed. It was shown that the absence of PR toxin in mycelium was due to its instability during the extraction procedure.