bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of
N,N
-Dimethylglycine, Acetic Acid, and Butyric Acid from Betaine by
Eubacterium limosum
Authors: Müller E. , Fahlbusch K. , Walther R. , Gottschalk G.
Published: January 2020

Two bacterial strains that grow anaerobically on betaine were isolated from enrichment cultures and identified as strains of
Eubacterium limosum.
In a mineral medium supplemented with yeast extract and Casitone, the doubling time of
E. limosum
strain 11A on betaine was 6 h at 37°C. The molar growth yield amounted to 9 g of dry cell mass per mol. Betaine was fermented in accordance with the following equation: 7 betaine + 2 CO
2
→ 7
N,N
-dimethylglycine + 1.5 acetate + 1.5 butyrate.
E. limosum
also grew on methanol and choline. The former was converted to acetate and butyrate, and the latter was converted to
N,N
-dimethylethanolamine, acetate, and butyrate. The conditions for the quantitative determination of
N,N
-dimethylglycine by capillary tube isotachophoresis have been determined.
Microbial formation of secondary and tertiary amines in municipal sewage
Authors: Thomas J M , Alexander M
Published: January 2020

Dimethylamine was formed in municipal sewage that was amended with creatinine, and trimethylamine was formed from choline or phosphatidylcholine. The maximum level of product that accumulated was equivalent to 0.13, 0.096, and 6.7% by weight, respectively, of the added chemicals. No dimethylamine or trimethylamine was detected in sewage amended with betaine, and no dimethylamine was found in sewage that was amended with methylamine and methionine.
Inactivation and injury of Yersinia enterocolitica by radiation and freezing
Authors: EL-Zawahry Y A , Grecz N
Published: January 2020

Cell inactivation and cell injury by irradiation and freezing of the potentially enteropathogenic, food-borne gram-negative rod Yersinia enterocolitica strain WA was investigated. The radiation dose necessary to kill 90% of the initial population, i.e., one D-value, was 10.0, 14,3, and 24.0 krad when irradiation was carried out at 2 to 0, -18, and -75 degrees C, respectively. On the other hand, cell injury, i.e., inability to form colonies in agar containing 2.5% NaCl, was 32, 42 and 54% when cells were irradiated to one D-value at 2 to 0, -18, and -75 degrees C, respectively. Freezing alone (without irradiation) at -18 and -75 degrees C for 1 h resulted in 7 and 42% cell inactivation and 55 and 83% cell injury, respectively. These data show that given the same extent of cell inactivation, freezing caused substantially greater cell injury than radiation. For purposes of radiation sterilization, doses of 100 and 150 krad would be sufficient to inactivate 10 log cycles of Y. enterocolitica strain WA if irradiated at 2 to 0 and -18 degrees C, respectively. Presence of 2.5% NaCl may result in a further 50% reduction of the dose required to achieve sterility.
Sediment bacterial indicators in an urban shellfishing subestuary of the lower Chesapeake Bay
Authors: Erkenbrecher C W
Published: January 2020

The objectives of this study were to document the spatial and temporal distributions and compositions of bacteria in the sediments and overlying waters of an important urban shellfishing area in the lower Chesapeake Bay region, the Lynnhaven Estuary. Marked fluctuations were observed in the date of many of the physicochemical parameters and the indicator bacteria. The higher-salinity water and coarser sediment of the inlet site showed lower overall bacterial densities than did the headwater sites, where freshwater runoff and decreased tidal action were characteristic. Densities of benthic indicator bacteria, when expressed on a volumetric basis, were significantly greater than counts in the overlying waters. These counts were indicative of a fecally polluted system and were well above the safe maximum limits for shellfish-growing waters. Significantly fewer total and fecal bacteria were observed in both the water and the sediment during the warm months of May, July, and August. The primary sources of the Lynnhaven's bacterial pollution appeared to be typical of urban and agricultural runoff, although failure of septic tank systems was suspected as a problem in the Lynnhaven's western branch. These results illustrated that sediments in shellfishing areas could serve as a reservoir for high densities of indicator bacteria and that, potentially, pathogens could pose a health hazard.
Isolation and characterization of two new trichothecenes from Fusarium sporotrichioides strain M-1-1
Authors: Ishii K , Ueno Y
Published: January 2020

Two new trichothecenes were isolated along with T-2 toxin, neosolaniol, and HT-2 toxin from the culture filtrate of Fusarium sporotrichioides strain M-1-1. The structures of the new toxins were characterized to be 4 beta, 8 alpha-diacetoxy-12,13-epoxytrichothec-9-ene-3 alpha, 15-diol (designated NT-1) and 4 beta-acetoxy-12,13-epoxy-trichothec-9-ene-3 alpha,8 alpha,15-triol (designated NT-2).
Antimicrobial resistance transfer in transport media
Authors: George B A , Fagerberg D J , Sanem J A
Published: January 2020

Five different transport media (buffered glycerol saline, Amies, Cary and Blair, Stuart, and modified Stuart) were tested to determine if antimicrobial resistance transfer could occur among bacteria in the media. Transfer of resistance occurred in all of the media, except buffered glycerol saline, within 2 h of holding both at room temperature and 4 degrees C.
Uptake of
Vibrio cholerae
Biotype
eltor
from Contaminated Water by Water Hyacinth (
Eichornia crassipes
)
Authors: Spira William M. , Huq Anwarul , Ahmed Qazi Shafi , Saeed Yusuf A.
Published: January 2020

Vibrio cholerae
biotype
eltor
appears to concentrate on the surface of the water hyacinth (
Eichornia crassipes
), thereby enhancing its survival and its potential for transmission through waterways of cholera-endemic regions such as Bangladesh.
Pectic Enzyme Activities of Bacteria Associated with Rotted Onions (
Allium cepa
)
Authors: Obi Samuel K. C. , Umezurike Gabriel M.
Published: January 2020

The aerobic bacteria associated with soft rot in onions (
Allium cepa
) were isolated and identified as a
Vibrio
sp.,
Micrococcus epidermidis, Pseudomonas cepacia
, an
Acinetobacter
sp., a
Xanthomonas
sp.,
Bacillus polymyxa
, and
Bacillus megaterium
. With the cup-plate assay method, no pectin hydrolase could be detected from any of these isolates when they were cultured in pectin medium, but lyase and pectinesterases were detectable. Onion tissue cultures showed pectin hydrolase activity for
P. cepacia
and
B. polymyxa
and lyase and pectinesterase activities for all of the isolates, usually at higher levels of activity than those of the pectin medium culture filtrates. In both culture media,
Vibrio
sp. showed the highest lyase and pectinesterase activities. In the viscometric test, all of the isolates achieved at least a 50% decrease in viscosity for lyase enzyme, with
M. epidermidis
and
Vibrio
sp. recording viscosity decreases as high as 83%. The ability to cause soft rot in onion bulbs was demonstrated by
P. cepacia
and
Xanthomonas
sp. Benzoic acid at a concentration of 0.8 mg/ml caused total suppression of enzyme production, whereas sodium benzoate at this concentration reduced pectinesterase production by 71% and lyase production by 72%. The possible use of these preservatives in the control of soft rot in onions is noted.
Mutagenicity testing of some commonly used dyes
Authors: Chung K T , Fulk G E , Andrews A W
Published: January 2020

Seventeen commonly used dyes and 16 of their metabolites or derivatives were tested in the Salmonella-mammalian microsome mutagenicity test. Mutagens active with and without added Aroclor-induced rat liver microsome preparations (S9) were 3-aminopyrene, lithol red, methylene blue (USP), methyl yellow, neutral red, and phenol red. Those mutagenic only with S9 activation were 4-aminopyrazolone, 2,4-dimethylaniline, N,N-dimethyl-p-phenylenediamine, methyl red, and 4-phenyl-azo-1-naphthylamine. Orange II was mutagenic only without added S9. Nonmutagenic azo dyes were allura red, amaranth, ponceau R, ponceau SX, sunset yellow, and tartrazine. Miscellaneous dyes not mutagenic were methyl green, methyl violet 2B, and nigrosin. Metabolites of the azo dyes that were not mutagenic were 1-amino-2-naphthol hydrochloride, aniline, anthranilic acid, cresidine salt, pyrazolone T,R-amino salt (1-amino-2-naphthol-3,6-disulfonic disodium salt), R-salt, Schaeffer's salt (2-naphthol-6-sulfonic acid, sodium salt), sodium naphthionate, sulfanilamide, and sulfanilic acid. 4-Amino-1-naphthalenesulfonic acid sodium salt was also not mutagenic. Fusobacterium sp. 2 could reductively cleave methyl yellow to N,N-dimethyl-p-phenylenediamine which was then activated to a mutagen.
Dichloran as an Inhibitor of Mold Spreading in Fungal Plating Media: Effects on Colony Diameter and Enumeration
Authors: Henson O. Eldon
Published: January 2020

Problems associated with overgrowth by spreading molds are not addressed by currently recommended fungal enumeration media. Twenty-two fungi, including 12 mold and 3 yeast genera, were evaluated for the effects of dichloran (2,6-dichloro-4-nitroaniline), previously identified as a mold-spreading inhibitor, on colony diameter and enumeration. On malt agar or antibiotic-potato-dextrose agar (APDA), colony diameters were effectively reduced when dichloran was added. Colony diameters decreased as the dichloran concentration increased. Counts obtained with mixed mold spore suspensions were lower on APDA supplemented with 25 μg of dichloran per ml than on APDA and were higher than APDA with the addition of 5 μg of dichloran per ml (APDA-D-5). Overall counts of mixed and individual mold spore and yeast suspensions were higher in APDA-D-5 than in APDA. The additional advantages of APDA-D-5 may be useful in routine enumeration of fungi.
Heat Resistance of
Bacillus
Spores at Various Relative Humidities
Authors: Reyes Antolin L. , Crawford Ronald G. , Wehby Albert J. , Peeler James T. , Wimsatt John C. , Campbell Jeptha E. , Twedt Robert M.
Published: January 2020

The thermal resistance characteristics of spores from strains of five different
Bacillus
species were determined in phosphate buffer and at relative humidities ranging from <0.001 to 100% in a closed-can system. Spores tested in the closed-can system showed a marked increase in heat resistance over those in phosphate buffer, with the greatest increases occurring at relative humidities between 1 and 50%. When estimates of the time to reduce the initial spore concentration 99.99% (
F
value) at eight different relative humidities were plotted against temperature, three different types of heat resistance profiles were obtained, with maximum resistances at relative humidities of 1, 7, and 30%. When the various strains of spores were heated at the relative humidity of their maximum heat resistance, their relative order of heat resistance was different from that seen in buffer. Spores from the soil isolate were most resistant under these conditions (
F
121.1
= 99.5 h).
External Microflora of a Marine Wood-Boring Isopod
Authors: Boyle Paul J. , Mitchell Ralph
Published: January 2020

Bacteria associated with the marine wood-boring isopod
Limnoria lignorum
were enumerated by acridine orange epifluorescence microscopy and by plate counts on several media; the plate-viable bacteria were isolated and identified. Similar procedures were followed to enumerate and identify bacteria associated with the wood substrate from which the isopods were collected and with the surrounding water from the isopod habitat. Approximately 1.4 × 10
7
bacterial cells were associated with each individual
L. lignorum. Aeromonas hydrophila, Pseudomonas
, and
Vibrio
were the most common genera in the isopod microflora. Wood from
L. lignorum
burrows had an associated bacterial flora of 1.6 × 10
7
cells per mg (damp weight).
A. hydrophila
also predominated in the wood microflora. The water from which the isopod population was collected contained 2.3 × 10
6
bacteria per ml.
Pseudomonas
and
Vibrio
species were very common in the water microflora, but
A. hydrophila
was not detected. Interactions between the isopod, its associated microorganisms, and the microorganisms within the wood substrate are discussed in the light of the known absence of a resident digestive tract microflora in these animals.
Isolation and Genetic Characterization of Bacteria That Degrade Chloroaromatic Compounds
Authors: Vandenbergh Peter A. , Olsen Ronald H. , Colaruotolo Joseph F.
Published: January 2020

Bacteria were isolated from a landfill site previously used for disposal of chlorinated organic wastes. These soil isolates were capable of utilizing various chloroaromatic compounds. One such bacterial strain, designated
Pseudomonas cepacia
HCV (2,6-DCT) and growing on 2,6-dichlorotoluene, transferred this trait to a catechol-1,2-oxygenase mutant of
Pseudomonas aeruginosa.
Denitrification Associated with Periphyton Communities
Authors: Triska Frank J. , Oremland Ronald S.
Published: January 2020

Scrapings of decomposing
Cladophora
sp. mats (periphyton) covering stream bed rocks produced N
2
O when incubated under N
2
plus 15% C
2
H
2
. Denitrification (N
2
O formation) was enhanced by NO
3
−
and was inhibited by autoclaving, Hg
2+
, and O
2
. No N
2
O was formed in the absence of C
2
H
2
(air or N
2
atmosphere). Chloramphenicol did not block N
2
O formation, indicating that the enzymes were constitutive. In field experiments, incubation of periphyton scrapings in the light inhibited denitrification because of algal photosynthetic O
2
production. The diurnal periphyton-associated denitrification rate was estimated to be 45.8 μmol of N
2
O·m
−2
·day
−1
, as determined by averaging light, aerobic plus dark, and anaerobic rates over a 24-h period.
Influence of tricarboxylic acid cycle intermediates and related metabolites on the biosynthesis of aflatoxin by resting cells of Aspergillus flavus
Authors: Shantha T , Murthy V S
Published: January 2020

Resting cells of Aspergillus flavus synthesized aflatoxin from acetate as the sole carbon source after 36 h of incubation. Addition of pyruvate (5.5 mg/m) as cosubstrate to [1-14C]acetate and unlabeled acetate considerably reduced toxin production but increased the radioactivity on the tricarboxylic acid intermediates. This suggests that high tricarboxylic acid activity drastically affected toxin synthesis.
Limulus amoebocyte lysate and direct sampling methods for surveillance of operating nebulizers
Authors: Reinhardt D J , Nabors W , Kennedy C , Malecka-Griggs B
Published: January 2020

The Limulus amoebocyte lysate test for detection of endotoxin (Pyrogent; Mallinckrodt Chemical Co.) and the Easicult method (Orion Diagnostica) for detection of bacteria were compared with direct dilution sampling, a standardized technique for respiratory therapy surveillance previously developed in our laboratory. Tests of 206 reservoirs of nebulizers were done in three hospitals in Georgia. Forty-five percent of all reservoirs sampled were contaminated. Gram-negative, nonfermentative bacilli were the predominant contaminants. The results of the Limulus test and the Easicult system were in agreement with those of the direct dilution sampling tests approximately 84 and 90% of the time, respectively. Direct dilution of water samples onto blood agar plates was the most sensitive, reliable, and informative method for detecting viable bacteria. The Easicult and Limulus systems were sensitive enough to detect greater than or equal to 10(3) colony-forming units per ml. Positive Limulus tests and negative culture tests, reflecting detection of endotoxin but not of viable gram-negative bacteria, occurred in 20 of 206 (9.7%) instances. Positive cultures and negative Limulus tests were noted in 13 of 206 (6.8%) samplings. The Limulus test is a valuable procedure, for it can detect moderate-to-heavy microbial contamination within 1 h of testing and affords the opportunity to remove contaminated equipment from patients within minutes of a positive test result. These results demonstrate the potential value of the Easicult and Limulus tests for selective surveillance of operating nebulizers.
Production of Italian Dry Salami: Effect of Starter Culture and Chemical Acidulation on Staphylococcal Growth in Salami Under Commercial Manufacturing Conditions
Authors: Metaxopoulos J. , Genigeorgis C. , Fanelli M. J. , Franti C. , Cosma E.
Published: January 2020

The effect of starter culture and chemical acidulation on the growth and enterotoxigenesis of
Staphylococcus aureus
strain S-6 in Italian dry salami under commercial manufacturing conditions was studied. The experimental design included two levels of
S. aureus
(10
4
and 10
5
/g), three levels of starter culture (0, 10
5
, and 10
6
/g), three levels of initial pH (pH
0
) (6.1, 5.5, and 4.8), two manufacturing plants, and three replications.
S. aureus
growth in the salami was affected significantly (
P
< 0.005) by pH
0
, initial levels of
S. aureus
(staph
0
) and lactic acid bacteria (LAB
0
), day of fermentation, and by the interactions of pH
0
× day, pH
0
× LAB
0
, LAB
0
× staph
0
, pH
0
× staph
0
, and pH
0
× location of fermentation. In general, the lower the pH
0
and the higher the LAB
0
, the greater the inhibition of
S. aureus
. The LAB levels during the fermentation were affected significantly (
P
< 0.005) by pH
0
, LAB
0
, day of fermentation, location, LAB
0
× pH
0
, and LAB
0
× day. Derived regression equations related level of
S. aureus
and LAB at any day of fermentation to a number of microbiological and chemical variables. Close similarity of observed and predicted levels of
S. aureus
and LAB growth demonstrated the usefulness of the experimental approach in evaluating the safety of a process. No detectable enterotoxin or thermonuclease was found at any stage of processing even when
S. aureus
reached levels of 10
7
/g of salami.
Conjugal Transfer of Lactose-Fermenting Ability Among
Streptococcus cremoris
and
Streptococcus lactis
Strains
Authors: Snook René J. , McKay Larry L.
Published: January 2020

Streptococcus cremoris
C3 was found to transfer lactose-fermenting ability to LM2301, a
Streptococcus lactis
C2 lactose-negative streptomycin-resistant (Lac
−
Str
r
) derivative which is devoid of plasmid deoxyribonucleic acid (DNA); to LM3302, a Lac
−
erythromycin-resistant (Ery
r
) derivative of
S. lactis
ML3; and to BC102, an
S. cremoris
B
1
Lac
−
Ery
r
derivative which is devoid of plasmid DNA.
S. cremoris
strains R1, EB
7
, and Z8 were able to transfer lactose-fermenting ability to LM3302 in solid-surface matings. Transduction and transformation were ruled out as mechanisms of genetic transfer. Chloroform treatment of donor cells prevented the appearance of recombinant clones, indicating that viable cell-to-cell contact was responsible for genetic transfer. Transfer of plasmid DNA was confirmed by agarose gel electrophoresis. Transconjugants recovered from EB
7
and Z8 matings with LM3302 exhibited plasmid sizes not observed in the donor strains. Transconjugants recovered from R1, EB
7
, and Z8 matings with LM3302 were able to donate lactose-fermenting ability at a high frequency to LM2301. In
S. cremoris
R1, EB
7
, and Z8 matings with LM2301, streptomycin resistance was transferred from LM2301 to the
S. cremoris
strains. The results confirm genetic transfer resembling conjugation between
S. cremoris
and
S. lactis
strains and present presumptive evidence for plasmid linkage of lactose metabolism in
S. cremoris.
Catalase-Aminotriazole Assay, an Invalid Method for Measurement of Hydrogen Peroxide Production by Wood Decay Fungi
Authors: Highley Terry L.
Published: January 2020

The catalase-aminotriazole assay for determination of hydrogen peroxide apparently cannot be used for measuring hydrogen peroxide production in crude preparations from wood decay fungi because of materials in the crude preparations that interfere with the test.
Recovery of indigenous enteroviruses from raw and digested sewage sludges
Authors: Goddard M R , Bates J , Butler M
Published: January 2020

We examined different types of raw sewage sludge treatment, including consolidation, anaerobic mesophilic digestion with subsequent consolidation, and aerobic-thermophilic digestion. Of these, the most efficient reduction in infectious virus titer was achieved by mesophilic digestion with subsequent consolidation, although a pilot-scale aerobic-thermophilic digester was extremely time effective, producing sludges with similarly low virus titers in a small fraction of the time. Although none of the treatments examined consistently produced a sludge with undetectable virus levels, mesophilic digestion alone was found to be particularly unreliable in reducing the levels of infectious virus present in the raw sludge.
Dynamics of Bacterial Sulfate Reduction in a Eutrophic Lake
Authors: Ingvorsen K. , Zeikus J. G. , Brock T. D.
Published: January 2020

Bacterial sulfate reduction in the surface sediment and the water column of Lake Mendota, Madison, Wis., was studied by using radioactive sulfate (
35
SO
4
2−
). High rates of sulfate reduction were observed at the sediment surface, where the sulfate pool (0.2 mM SO
4
2−
) had a turnover time of 10 to 24 h. Daily sulfate reduction rates in Lake Mendota sediment varied from 50 to 600 nmol of SO
4
2−
cm
−3
, depending on temperature and sampling date. Rates of sulfate reduction in the water column were 10
3
times lower than that for the surface sediment and, on an areal basis, accounted for less than 18% of the total sulfate reduction in the hypolimnion during summer stratification. Rates of bacterial sulfate reduction in the sediment were not sulfate limited at sulfate concentrations greater than 0.1 mM in short-term experiments. Although sulfate reduction seemed to be sulfate limited below 0.1 mM, Michaelis-Menten kinetics were not observed. The optimum temperature (36 to 37°C) for sulfate reduction in the sediment was considerably higher than in situ temperatures (1 to 13°C). The response of sulfate reduction to the addition of various electron donors metabolized by sulfate-reducing bacteria in pure culture was investigated. The degree of stimulation was in this order: H
2
>
n
-butanol >
n
-propanol > ethanol > glucose. Acetate and lactate caused no stimulation.
Occurrence of Rhodococcus coprophilus and associated actinomycetes in feces, sewage, and freshwater
Authors: Mara D D , Oragui J I
Published: January 2020

Freshwater, sewage, and fecal samples from various sources were examined for Rhodococcus coprophilus, associated actinomycetes, Escherichia coli, and fecal streptococci. Rhodococcus coprophilus was isolated consistently from feces of farm animals, poultry reared in proximity to farm animals, freshwater, and wastewater polluted with animal fecal wastes. It was not isolated from samples of human feces. The ratio of R. coprophilus total actinomycetes was higher in feces from cattle, sheep, ducks, and geese than in specimens from pigs, horses, and fowl. In samples from two freshwater streams polluted by fecal material from farm animals, the ratios of R. copropilus to total actinomycetes were similar to those found in fecal specimens from cattle and sheep. Ratios of fecal coliform to fecal streptococci could not distinguish between fresh human and animal fecal samples and, furthermore, were not reflected in the stream waters polluted by animal fecal material. R. coprophilus has potential in water and dairy bacteriology as a specific indicator organism of fecal pollution due to farm animal wastes.
Immunodiffusion method for detection of type A Clostridium botulinum
Authors: Ferreira J L , Hamdy M K , Zapatka F A , Hebert W O
Published: January 2020

A simple gel immunodiffusion agar procedure was developed for detecting toxigenic strains of Clostridium botulinum type A. The method consisted of overlaying colonies grown on thin-layer tryptone-peptone-glucose-yeast extract agar with gel diffusion agar containing desired levels of C. botulinum type A antitoxin. Concentric precipitin zones formed around colonies of C. botulinum type A. Strains of C. botulinum type A were detected by this procedure. However, C. botulinum type B reacted to a lesser degree with this system. No reaction was noted with types E, F, Langeland, F8G, Clostridium perfringens, or with strains of nontoxigenic Clostridium sporogenes. Thickness of the plating medium, incubation time and temperature, environmental growth conditions, and levels of both agar an antitoxin were important factors affecting the efficiency of the procedure, whereas the age of the culture (used as inoculum) was not critical. Thin agar medium (5 ml per plate [15 by 100 mm]) containing 1.5% agar gave consistent results, but more agar limited diffusion, and lower levels encouraged spreaders. The optimal concentration of antitoxin incorporated in to the gel diffusion agar overlay was 1.2 IU/ml gel diffusion agar. Rabbit type A antitoxin prepared with purer immunizing agent gave similar reactions. The addition of type A antitoxin in tryptone-peptone-glucose-yeast extract agar medium before inoculation with type A C. botulinum showed promising results.
Kinetic Explanation for Accumulation of Nitrite, Nitric Oxide, and Nitrous Oxide During Bacterial Denitrification
Authors: Betlach Michael R. , Tiedje James M.
Published: January 2020

The kinetics of denitrification and the causes of nitrite and nitrous oxide accumulation were examined in resting cell suspensions of three denitrifiers. An
Alcaligenes
species and a
Pseudomonas fluorescens
isolate characteristically accumulated nitrite when reducing nitrate; a
Flavobacterium
isolate did not. Nitrate did not inhibit nitrite reduction in cultures grown with tungstate to prevent formation of an active nitrate reductase; rather, accumulation of nitrite seemed to depend on the relative rates of nitrate and nitrite reduction. Each isolate rapidly reduced nitrous oxide even when nitrate or nitrite had been included in the incubation mixture. Nitrate also did not inhibit nitrous oxide reduction in
Alcaligenes odorans
, an organism incapable of nitrate reduction. Thus, added nitrate or nitrite does not always cause nitrous oxide accumulation, as has often been reported for denitrifying soils. All strains produced small amounts of nitric oxide during denitrification in a pattern suggesting that nitric oxide was also under kinetic control similar to that of nitrite and nitrous oxide. Apparent

K
m

values for nitrate and nitrite reduction were 15 μM or less for each isolate. The

K
m

value for nitrous oxide reduction by
Flavobacterium
sp. was 0.5 μM. Numerical solutions to a mathematical model of denitrification based on Michaelis-Menten kinetics showed that differences in reduction rates of the nitrogenous compounds were sufficient to account for the observed patterns of nitrite, nitric oxide, and nitrous oxide accumulation. Addition of oxygen inhibited gas production from
13
NO
3
−
by
Alcaligenes
sp. and
P. fluorescens
, but it did not reduce gas production by
Flavobacterium
sp. However, all three isolates produced higher ratios of nitrous oxide to dinitrogen as the oxygen tension increased. Inclusion of oxygen in the model as a nonspecific inhibitor of each step in denitrification resulted in decreased gas production but increased ratios of nitrous oxide to dinitrogen, as observed experimentally. The simplicity of this kinetic model of denitrification and its ability to unify disparate observations should make the model a useful guide in research on the physiology of denitrifier response to environmental effectors.
Gram-negative, aerobic, enteric pathogens among intestinal microflora of wild turkey vultures (Cathartes aura) in west central Texas
Authors: Winsor D K , Bloebaum A P , Mathewson J J
Published: January 2020

The prevalence of gram-negative bacterial species in the intestines of 20 apparently healthy turkey vultures (Cathartes aura) was determined. Edwardsiella tarda, Plesiomonas shigelloides, Salmonella, and Arizona hinshawii (Salmonella arizonae) were each recovered from 15% of these birds. Turkey vultures may be important reservoirs of these bacterial pathogens.
Short incubation of presumptive media for detection of fecal coliforms in shellfish
Authors: Hastback W G
Published: January 2020

Positive fecal coliform most-probable number results were compiled from 7,701 shellfish samples examined over 9 years. Generally, less than 2% of all positive reactions in EC medium are results of inoculations from presumptive media positive at the maximum (48-h) incubation period.
Production of Alcohol from Apple Pomace
Authors: Hang Y. D. , Lee C. Y. , Woodams E. E. , Cooley H. J.
Published: January 2020

Production of ethyl alcohol from apple pomace with a Montrachet strain of
Saccharomyces cerevisiae
is described. More than 43 g of the ethyl alcohol could be produced per kg of apple pomace fermented at 30°C in 24 h. The fermentation efficiency of this process was approximately 89%.
Mutants of Corynebacterium diphtheriae PW8 that produce toxin in medium with excess iron
Authors: Ishii-Kanei C , Uchida T , Yoneda M
Published: January 2020

Two mutants that produce toxin in medium with excess iron were isolated from the PW8 strain of Corynebacterium diphtheriae. These mutants produced as much toxin in medium containing excess iron (3 mug of Fe2+ per ml) as did the parent PW8 strain in iron-depleted medium, and they will be very useful for easy production of toxin.
Survival of
Rhizobium
in Acid Soils
Authors: Lowendorf Henry S. , Baya Ana Maria , Alexander Martin
Published: January 2020

A
Rhizobium
strain nodulating cowpeas did not decline in abundance after it was added to sterile soils at pH 6.9 and 4.4, and the numbers fell slowly in nonsterile soils at pH 5.5 and 4.1. A strain of
R. phaseoli
grew when added to sterile soils at pH 6.7 and 6.9; it maintained large, stable populations in soils of pH 4.4, 5.5, and 6.0, but the numbers fell markedly and then reached a stable population size in sterile soils at pH 4.3 and 4.4. The abundance of
R. phaseoli
added to nonsterile soils with pH values of 4.3 to 6.7 decreased similarly with time regardless of soil acidity, and the final numbers were less than in the comparable sterile soils. The minimum pH values for the growth of strains of
R. meliloti
in liquid media ranged from 5.3 to 5.9. Two
R. meliloti
strains, which differed in acid tolerance for growth in culture, did not differ in numbers or decline when added to sterile soils at pH 4.8, 5.2, and 6.3. The population size of these two strains was reduced after they were introduced into nonsterile soils at pH 4.8, 5.4, and 6.4, and the number of survivors was related to the soil pH. The
R. meliloti
strain that was more acid sensitive in culture declined more readily in sterile soil at pH 4.6 than did the less sensitive strain, and only the former strain was eliminated from nonsterile soil at pH 4.8; however, the less sensitive strain also survived better in limed soil. The cell density of the two
R. meliloti
strains was increased in pH 6.4 soil in the presence of growing alfalfa. The decline and elimination of the tolerant, but not the sensitive, strain was delayed in soil at pH 4.6 by roots of growing alfalfa.
Influence of pH and electrolyte composition on adsorption of poliovirus by soils and minerals
Authors: Taylor D H , Moore R S , Sturman L S
Published: January 2020

The pH and the nature an concentration of simple electrolytes influenced the interaction of poliovirus type 2 with three soils, a sand, and a clay mineral. In electrolytes above pH 9 the virus was not adsorbed extensively to the substrates, but below pH 7 almost all virus was bound. For each adsorbent there was a characteristic pH region of transition from strong to weak uptake. Differences between the soils in virus uptake were shown to parallel their pH-dependent mineral. In electrolytes above pH 9 the virus was not adsorbed extensively to the substrates, but below pH 7 almost all virus was bound. For each adsorbent there was a characteristic pH region of transition from strong to weak uptake. Differences between the soils in virus uptake were shown to parallel their pH-dependent mineral. In electrolytes above pH 9 the virus was not adsorbed extensively to the substrates, but below pH 7 almost all virus was bound. For each adsorbent there was a characteristic pH region of transition from strong to weak uptake. Differences between the soils in virus uptake were shown to parallel their pH-dependent charge properties, as determined by whole-particle microelectrophoresis. Only when the pH was close to or above the critical region was uptake increased with electrolyte concentration. The transition region for all substrates was above pH 7.5 the isoelectric point of the virus. Thus, it appears that when both the virus and substrate are highly negative charged, repulsive electrostatic effects may exceed inherent attractive interactions, thereby inhibiting adsorption.
Evidence for Coexistence of Two Distinct Functional Groups of Sulfate-Reducing Bacteria in Salt Marsh Sediment
Authors: Banat Ibrahim M. , Lindström E. Börje , Nedwell David B. , Balba M. Talaat
Published: January 2020

Oxidation of acetate in salt marsh sediment was inhibited by the addition of fluoroacetate, and also by the addition of molybdate, an inhibitor of sulfate-reducing bacteria. Molybdate had no effect upon the metabolism of acetate in a freshwater sediment in the absence of sulfate. The inhibitory effect of molybdate on acetate turnover in the marine sediment seemed to be because of its inhibiting sulfate-reducing bacteria which oxidized acetate to carbon dioxide. Sulfide was not recovered from sediment in the presence of molybdate added as an inhibitor of sulfate-reducing bacteria, but sulfide was recovered quantitatively even in the presence of molybdate by the addition of the strong reducing agent titanium chloride before acidification of the sediment. Reduction of sulfate to sulfide by the sulfate-reducing bacteria in the sediment was only partially inhibited by fluoroacetate, but completely inhibited by molybdate addition. This was interpreted as showing the presence of two functional groups of sulfate-reducing bacteria—one group oxidizing acetate, and another group probably oxidizing hydrogen.
Transit time of epithelial cells in the small intestines of germfree mice and ex-germfree mice associated with indigenous microorganisms
Authors: Savage D C , Siegel J E , Snellen J E , Whitt D D
Published: January 2020

Germfree mice housed in isolators under controlled environmental and nutritional conditions were associated with an intestinal microflora. These associated animals and germfree mice drawn from the same population were tested for the rate at which the epithelial cells transited from the crypts of Lieberkuhn to the tips of the villi in their small intestines. The method for estimating the rate of transit of epithelial cells involved the use of liquid scintillation counting to determine the amount of radioactivity entering the cells while the animals were being injected with [3H]thymidine and statistical analysis of th data with a computer program developed for the purpose. As estimated by that method, the cells transited from the crypts to the villous tips in germfree mice in about 115 h and in the associated animals in about 53 h. In monoassociated mice, a strain of a Lactobacillus sp. had no effect on the transit time of the epithelial cells. A strain of Torulopsis pintolopesii stimulated uptake of 3[H]thymidine by the small bowel mucosae in mice monoassociated with the organisms for 5 weeks. In animals monoassociated with the yeast fo 3, 4, and 6 weeks, however, the radioactive compound was incorporated into the bowel mucosae to the same extent as the mucosae of germfree mice. Therefore, similarly to the Lactobacillus strain, T. pintolopesii has no obvious influence on the transit rate of small bowel epithelial cells.
Effect of Temperature on Heterotrophic Glucose Uptake, Mineralization, and Turnover Rates in Lake Sediments
Authors: Toerien Danie F. , Cavari Benzion
Published: January 2020

The
V
max
and turnover rates (TR) of [
U
-
14
C]glucose uptake and mineralization of Lake Kinneret (Israel) sediment are temperature dependent. The following activation energies were determined: glucose uptake, ∼15,000 cal (62,760 J); TR of glucose uptake, ∼10,000 cal (41,840 J); glucose mineralization, 7,500 to 15,000 cal (31,380 to 62,760 J); and TR of glucose mineralization, ∼15,000 cal.
Q
10
values varied as follows: glucose uptake, ∼2.3; TR of glucose uptake, ∼1.8; and glucose mineralization, ∼2.5.
K
+
S

n

values increased slightly with temperature and might reflect an increased
K
with increased temperatures. Glucose respiration/uptake ratios were low (9.5 to 12%) and were apparently not greatly influenced by the presence or absence of oxygen or by different assay temperatures. Aerobic or anaerobic sediments assayed under either aerobic or anaerobic conditions did not exhibit greatly different
V
max
, TR, or
K
+
S

n

values.
Production and properties of cyanobacterial endotoxins
Authors: Keleti G , Sykora J L
Published: January 2020

Lipopolysaccharides (LPS) were isolated from four species of cyanobacteria (Anabaena flos-aquae UTEX 1444. A. cylindrica, Oscillatoria tenuis, and O. brevis) frequently occurring in drinking-water supplies. The cyanobacterial LPS contained glucose, xylose, mannose, and rhamnose, but differed from the LPS derived from most gram-negative bacteria because of the variable presence of 2-keto-3-deoxyoctonate, heptose, galactose, and glucosamine. Cyanobacterial lipid A is characterized by long-chain saturated an unsaturated fatty acids and hydroxy fatty acids which show great diversity. Unlike lipid A from heterotrophic gram-negative bacteria, lipid A from cyanobacteria usually lacks phosphates. The detection of distinct O-antigen chemotypes indicates that LPS may be used for taxonomic classification. Isolated cyanobacterial LPS always induced Limulus amoebocyte lysate gelation. A. flos-aquae LPS gave a positive Schwartzman reaction. Endotoxins from A. cylindrica and O. brevis were toxic to mice when injected intraperitoneally. The cyanobacterial endotoxins showed generally lower biological activity than did LPS derived from common heterotrophic gram-negative bacteria. Nevertheless, cyanobacteria in algal blooms may be a significant source of endotoxins in water supplies.
Assimilatory Sulfur Metabolism in Marine Microorganisms: Considerations for the Application of Sulfate Incorporation into Protein as a Measurement of Natural Population Protein Synthesis
Authors: Cuhel Russell L. , Taylor Craig D. , Jannasch Holger W.
Published: January 2020

The sulfur content of residue protein was determined for pure cultures of
Nitrosococcus oceanus, Desulfovibrio salexigens
, 4 mixed populations of fermentative bacteria, 22 samples from mixed natural population enrichments, and 11 nutritionally and morphologically distinct isolates from enrichments of Sargasso Sea water. The average 1.09 ± 0.14% (by weight) S in protein for 13 pure cultures agrees with the 1.1% calculated from average protein composition. An operational value encompassing all mixed population and pure culture measurements has a coefficient of variation of only 15.1% (
n
= 41). Short-term [
35
S]sulfate incorporation kinetics by
Pseudomonas halodurans
and
Alteromonas luteoviolaceus
demonstrated a rapid appearance of
35
S in the residue protein fraction which was well modelled by a simple exponential uptake equation. This indicates that little error in protein synthesis determination results from isotope dilution by endogenous pools of sulfur-containing compounds. Methionine effectively competed with sulfate for protein synthesis in
P. halodurans
at high concentrations (10 μM), but had much less influence at 1 μM. Cystine competed less effectively with sulfate, and glutathione did not detectably reduce sulfate-S incorporation into protein. [
35
S]sulfate incorporation was compared with [
14
C]glucose assimilation in a eutrophic brackish-water environment. Both tracers yielded similar results for the first 8 h of incubation, but a secondary growth phase was observed only with
35
S. Redistribution of
14
C from low-molecular-weight materials into residue protein indicated additional protein synthesis. [
35
S]sulfate incorporation into residue protein by marine bacteria can be used to quantitatively measure bacterial protein synthesis in unenriched mixed populations of marine bacteria.
Bacillus subtilis "rec assay" test with isogenic strains
Authors: Mazza G
Published: January 2020

The Bacillus subtilis "rec assay" test, widely used for the detection of DNA-damaging agents, was studied in detail, using an isogenic set of strains carrying different mutations in repair or recombination functions or both. recE4 and rec-45 mutations turned out to confer on the cells the highest sensitivity to known mutagens. The recE4 strain and its isogenic rec+ strain have been tested and validated by several rec assay procedures for preferential killing by known DNA-damaging agents. The use of purified spores of the tester strains offers advantages for standardization of the assay.
Isolation of Methanobrevibacter smithii from human feces
Authors: Miller T L , Wolin M J , de Macario E C , Macario A J
Published: January 2020

Fecal specimens from nine adults were examined for the presence of methanogenic bacteria. Enrichment cultures of five specimens produced methane in 5 days. Of these five specimens, three were tested and produced methane during a short-term incubation. Four specimens did not produce methane in either short-term incubation or in enrichment culture. Each methanogenic culture contained methanogens similar in morphology to organisms of the genus Methanobrevibacter and showed factor-420 fluorescence by fluorescence microscopy. Pure cultures were obtained from four of the five methanogenic enrichment cultures. Each isolate grew and formed methane from either H2-CO2 or formate, but growth obtained with formate was poor. None of the isolates used acetate, methanol, or trimethylamine. All isolates grew in the presence of bile salts. In immunological studies, each isolate was closely related to the type strain of Methanobrevibacter smithii, a finding consistent with the physiological and morphological similarities between the isolates and the type strain.
Effects of Chlorine Concentration on the Structure of Poliovirus
Authors: Alvarez Maria E. , O'Brien R. T.
Published: January 2020

Chlorine concentrations below 0.8 mg/liter inactivated poliovirus without causing separation of the viral components. These results indicate that the release of RNA from the capsids is the result, not the cause, of virus inactivation by chlorine.
Failure of Legionella pneumophila sensitivities to predict culture results from disinfectant-treated air-conditioning cooling towers
Authors: England A C , Fraser D W , Mallison G F , Mackel D C , Skaliy P , Gorman G W
Published: January 2020

The disinfection of cooling towers based on manufacturers' treatment protocols, as employed in units installed at various public gathering places in Dallas, Tex. (hotels, municipal auditorium), and at the city health department, was evaluated for effectiveness in controlling Legionella pneumophila and compared with previous laboratory studies. In specimens collected in September and December, 1978, L. pneumophila was isolated from 2 of 4 specimens from untreated cooling towers, 2 of 4 specimens from towers treated with agents deemed ineffective in earlier laboratory tests, 6 of 11 specimens from towers treated with putatively effective agents, and 0 of 4 specimens from towers treated with an agent unknown efficacy. These results suggest the need for further studies to identify biocidal agents effective in eliminating L. pneumophila from air-conditioning cooling towers.
Production of Maltase by Wild-Type and a Constitutive Mutant of
Saccharomyces italicus
Authors: Schaefer Eugene J. , Cooney Charles L.
Published: January 2020

The production of maltase, an inducible and repressible catabolic enzyme in
Saccharomyces italicus
, was studied and compared in batch, fed-batch, and continuous fermentations. Tight genetic controls on maltase synthesis limited the effect of environmental manipulations such as fed-batch or continuous culture in enhancement of maltase synthesis, and neither approach was able to improve the performance above the batch process for maltase production.
S. italicus
was mutated, and a constitutive producer of maltase was isolated. The mutant was detected by its ability to grow on sucrose, which is a noninducing substrate that is hydrolyzed by maltase;
S. italicus
does not possess invertase and will not normally grow on sucrose. Maltase production by this mutant was studied during growth on sucrose in batch and continuous cultures and marked improvement in enzyme productivity was observed. The specific activity of maltase produced by this mutant was more than twice that of the parent wild type: 2,210 and 1,370 U/g of cells for the mutant versus 890 and 510 U/g of cells for the wild type in batch and continuous cultures, respectively. Maltase specific productivity was increased from 74 to 288 U/g of cells per h by switching from batch growth of the wild type to continuous cultivation of the mutant.
Membrane Filter Method for Enumeration of
Acinetobacter calcoaceticus
from Environmental Waters
Authors: LaCroix Steven J. , Cabelli Victor J.
Published: January 2020

A membrane filter method was developed and evaluated for the quantitative recovery of
Acinetobacter calcoaceticus
from environmental waters. The procedure utilized a mineral medium, with sodium acetate and potassium nitrate as the carbon and nitrogen sources, respectively. Formic acid was included to enhance the recovery of
A. calcoaceticus
and to inhibit background growth. The medium was incubated for 46 h at 30°C, after which fermentation and cytochrome oxidase tests were performed on the colonies as they appeared on the membrane. Background microbial growth decreased on the average by 1.77 orders of magnitude. An essentially quantitative recovery relative to that on nutrient agar spread plates was obtained from freshly prepared suspensions of eight
A. calcoaceticus
strains in filter-sterilized pond water and from suspensions of five of the strains held for up to 96 h in filter-sterilized pond water at 15 and 22°C. Markedly reduced relative recoveries were obtained with the three remaining strains. However, these three strains, in contrast to the first five, not only did not grow, but also decreased in number in the eutrophic, filter-sterilized pond water. The confirmation rate of presumptive
A. calcoaceticus
colonies was 95%, whereas 8% of the presumptively negative colonies were
A. calcoaceticus
. The precision of the method did not exceed that expected from random error alone. Densities of
A. calcoaceticus
in freshwaters ranged from <1 to 7.9 × 10
4
organisms per 100 ml and were about 10
6
organisms per 100 ml in raw sewage.
Rapid detection of Salmonella spp. in food by use of the ISO-GRID hydrophobic grid membrane filter
Authors: Entis P , Brodsky M H , Sharpe A N , Jarvis G A
Published: January 2020

A rapid hydrophobic grid-membrane filter (HGMF) method was developed and compared with the Health Protection Branch cultural method for the detection of Salmonella spp. in 798 spiked samples and 265 naturally contaminated samples of food. With the HGMF method, Salmonella spp. were isolated from 618 of the spiked samples and 190 of the naturally contaminated samples. The conventional method recovered Salmonella spp. from 622 spiked samples and 204 unspiked samples. The isolation rates from Salmonella-positive samples for the two methods were not significantly different (94.6% overall for the HGMF method and 96.7% for the conventional approach), but the HGMF results were available in only 2 to 3 days after sample receipt compared with 3 to 4 days by the conventional method.
Isolation of Plasmid DNA from
Butyrivibrio fibrisolvens
Authors: Teather Ronald M.
Published: January 2020

A procedure based on successive precipitation of cell lysates with sodium dodecyl sulfate-NaCl and polyethylene glycol 6000 was developed which allows the isolation of plasmid DNA from
Butyrivibrio fibrisolvens.
A survey of
B. fibrisolvens
strains isolated from the bovine rumen showed that plasmids are a common feature of this species.