bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct isolation of Yersinia enterocolitica and Yersinia pseudotuberculosis from meat
Authors: Fukushima H
Published: January 2020

Studies were done to determine the usefulness of dilute alkali (KOH) treatment of meat samples for direct isolation of Yersinia enterocolitica and Yersinia pseudotuberculosis, without enrichment. Virulent Y. enterocolitica and Y. pseudotuberculosis in pork contaminated with 10(2), 10(3), and 10(4) cells per g survived the direct KOH treatment and were never recovered by using KOH postenrichment treatment. From 6 (4.8%) of 125 samples of retail ground pork, four biotype 4 serotype O3 and one biotype 3B serotype O3 strains of Y. enterocolitica and one Y. pseudotuberculosis serotype 4b strain were recovered by using direct KOH treatment without enrichment. As these isolations were attained without using enrichment cultural procedures, they represent an important time-saving alternative to simplify and speed isolation of Yersinia spp. from meat.
Growth of Natural Yeast Flora during the Fermentation of Inoculated Wines
Authors: Heard Gillian M. , Fleet Graham H.
Published: January 2020

The growth of yeasts that occur naturally in grape juice was quantitatively examined during the fermentation of four wines that had been inoculated with
Saccharomyces cerevisiae.
Although
S. cerevisiae
dominated the wine fermentations, there was significant growth of the natural species
Kloeckera apiculata, Candida stellata, Candida colliculosa, Candida pulcherrima
, and
Hansenula anomala.
Determination of the molecular mass of bacterial genomic DNA and plasmid copy number by high-pressure liquid chromatography
Authors: Genthner F J , Hook L A , Strohl W R
Published: January 2020

Relatively rapid methods for the determination of relative genome molecular mass (Mr) and the estimation of plasmid copy number have been developed. These methods are based on the ability of the Bio-Rad high-pressure liquid chromatography hydroxylapatite column to separate and quantify single-stranded DNA, double-stranded DNA, and plasmid DNA. Genome Mr values were calculated from reassociation kinetics of single-stranded DNA as measured with the hydroxylapatite column. Bacteriophage T4 DNA was used to establish a C0t (moles of nucleotides times seconds per liter), or standard reassociation value. From this C0t value, C0t values for Escherichia coli B, Beggiatoa alba B18LD, and Streptomyces coelicolor were determined by comparative calculations. From those calculated C0t values, the Mr values of 1.96 X 10(9) for E. coli, 2.02 X 10(9) for B. alba, and 3.28 X 10(9) for S. coelicolor were estimated. Plasmid concentration was determined from cleared lysates by comparing the integrated area under the phosphate buffer-eluted plasmid peak to values obtained with known amounts of plasmid. The plasmid copy number was estimated by multiplying the ratio between the amounts of plasmid and chromosomal DNA by the ratio between the Mr values of the chromosome and the plasmid. A copy number of 29 was obtained from a culture of E. coli HB101 harboring pBR322 grown to a culture density of 1.6 X 10(9) CFU . ml-1.
Ultrastructural localization of an extracellular protease in Pseudomonas fragi by using the peroxidase-antiperoxidase reaction
Authors: Thompson S S , Naidu Y M , Pestka J J
Published: January 2020

An extracellular protease, which previously has been found to correlate with the appearance of bleblike evaginations on the cell wall of Pseudomonas fragi ATCC 4973, was purified 38-fold by ammonium sulfate precipitation and Sephadex chromatography to yield a single band by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Polyclonal rabbit antiserum raised against the purified enzyme had an enzyme-linked immunosorbent assay titer of 4 X 10(7). The peroxidase antiperoxidase method was used to localize the neutral protease in P. fragi at the ultrastructural level. Electron microscopy of cell sections of this organism revealed that high concentrations of positive immunoperoxidase reaction product were located near the cell wall, whereas control sections stained with preimmune or heterologous serum did not show similar deposits to be present. These results are consistent with the hypothesis that blebs appearing on P. fragi contain high concentrations of neutral protease.
Heterokaryosis between Aspergillus oryzae cyclopiazonic acid-defective strains: method for estimating the risk of inducing toxin production among cyclopiazonic acid-defective industrial strains
Authors: Benkhemmar O , Gaudemer F , Bouvier-Fourcade I
Published: January 2020

Aspergillus oryzae strains are used extensively in the food industry. Some of these strains excrete alpha-cyclopiazonic acid (CPA), a mycotoxin which may provoke toxicoses in rats. Physicochemical methods may reveal the presence of this toxin, but they are inadequate to screen CPA-nonproducing (CPA-) strains. CPA production is revealed by either bacterial growth inhibition or alkalinization of the culture medium. This first biological property was used to devise a time-saving screening method to isolate mutants affected in their ability to produce CPA. The second method was used as a further test. After N-methyl-N'-nitro-N-nitrosoguanidine treatment, we isolated CPA- mutants from CPA producer strains (CPA+) and CPA+ mutants from CPA- strains. The mutants unable to produce CPA may be used in the food industry to reduce or eliminate the risk of intoxication in humans. Heterokaryon formation between different mutant strains was carried out to evaluate the risks of obtaining CPA from a mixture of mutants modified in their ability to synthesize this toxin. Pairings between two CPA+ strains always gave rise to CPA+ heterokaryons. Pairings between CPA+ and CPA- strains led, most often, to CPA+ heterokaryons. This could be directly correlated to the more frequent genotype (CPA+) in the heterokaryon. CPA hypoproducer and hyperproducer heterokaryons were obtained. Pairings between CPA- strains always gave rise to CPA- heterokaryons. These results suggest that the risks of producing this toxin from two CPA- individuals are not high.
Effect of Ca2+ ions on plasmid transformation of Streptococcus lactis protoplasts
Authors: von Wright A , Taimisto A M , Sivel� S
Published: January 2020

The effects of Mg2+ and Ca2+ ions on the efficiency of the plasmid transformation of lysozyme-treated Streptococcus lactis protoplasts were compared. A 33-megadalton plasmid, pLP712, coding for lactose fermentation and a 6.5-megadalton plasmid, pGB301, coding for erythromycin and chloramphenicol resistance were used as model plasmids, and S. lactis MG1614 was the recipient. Replacing Mg2+ with Ca2+ in the transformation buffer was found to increase transformant frequency more than 10-fold with both plasmids.
Protease activation of the entomocidal protoxin of Bacillus thuringiensis subsp. kurstaki
Authors: Andrews R E , Bibilos M M , Bulla L A
Published: January 2020

Two isolates of Bacillus thuringiensis subsp. kurstaki were examined which produced different levels of intracellular proteases. Although the crystals from both strains had comparable toxicity, one of the strains, LB1, had a strong polypeptide band at 68,000 molecular weight in the protein from the crystal; in the other, HD251, no such band was evident. When the intracellular proteases in both strains were measured, strain HD251 produced less than 10% of the proteolytic activity found in LB1. These proteases were primarily neutral metalloproteases, although low levels of other proteases were detected. In LB1, the synthesis of protease increased as the cells began to sporulate; however, in HD251, protease activity appeared much later in the sporulation cycle. The protease activity in strain LB1 was very high when the cells were making crystal toxin, whereas in HD251 reduced proteolytic activity was present during crystal toxin synthesis. The insecticidal toxin (molecular weight, 68,000) from both strains could be prepared by cleaving the protoxin (molecular weight, 135,000) with trypsin, followed by ion-exchange chromatography. The procedure described gave quantitative recovery of toxic activity, and approximately half of the total protein was recovered. Calculations show that these results correspond to stoichiometric conversion of protoxin to insecticidal toxin. The toxicities of whole crystals, soluble crystal protein, and purified toxin from both strains were comparable.
Maintenance of Different Mannitol Uptake Systems during Starvation in Oxidative and Fermentative Marine Bacteria
Authors: Davis Claire L. , Robb Frank T.
Published: January 2020

The mannitol uptake systems in marine
Vibrio
and
Pseudomonas
isolates from the kelp beds off the South African west coast were examined. The fermentative
Vibrio
isolate possessed a constitutive rapid mannitol uptake system and also a soluble mannitol-1-phosphate dehydrogenase, indicative of a mannitol phosphotransferase system. An inducible, relatively less active mannitol uptake system was detected in the oxidative
Pseudomonas
isolate, and this strain possessed a mannitol dehydrogenase. The maintenance of these systems during starvation survival was studied. The
Vibrio
isolate maintained its initial uptake system for approximately 5 weeks of starvation, after which time the uptake system was replaced by one with a higher affinity for mannitol. The mannitol transport system of the
Pseudomonas
isolate was depressed early in starvation (30 h) but could be readily induced by exogenous mannitol after 6 weeks of starvation. The relative proportions of mannitol which was incorporated and respired were determined in starved
Vibrio
and
Pseudomonas
strains.
Uptake Hydrogenase Activity Determined by Plasmid pRL6JI in
Rhizobium leguminosarum
Does Not Increase Symbiotic Nitrogen Fixation
Authors: Cunningham Scott D. , Kapulnik Yoram , Brewin Nicholas J. , Phillips Donald A.
Published: January 2020

Six mutants of
Rhizobium leguminosarum
3855 lacking uptake hydrogenase activity (Hup
−
phenotype) as a result of Tn
5-mob
mutagenesis of the
hup
-containing plasmid pRL6JI were tested for symbiotic performance on
Pisum sativum
L. and
Vicia benghalensis
L. Three pea cultivars and one vetch line, which induce four different levels of Hup activity in strain 3855, were grown to flowering under microbiologically controlled conditions in the absence of combined N. Direct Kjeldahl N measurements showed that in every case at least one Hup
−
mutant fixed as much N
2
as the isogenic Hup
+
strain. Measures of C
2
H
2
reduction, H
2
evolution,
3
H
2
incorporation, and plant dry weight were consistent with the interpretation that the oxidation of H
2
produced by the nitrogenase enzyme complex was not necessarily associated with increased N
2
fixation in these symbiotic associations. Tests with a smaller subset of the Hup
−
strains under four different root environments ranging from pH 5.0 to 8.2 likewise showed no significant advantage for the isogenic Hup
+
strain. It was concluded that the improvements in symbiotic N
2
fixation produced by pRL6JI are associated with some trait other than the Hup
+
phenotype.
Degradation of Bermuda and Orchard Grass by Species of Ruminal Bacteria
Authors: Akin Danny E. , Rigsby Luanne L.
Published: January 2020

Fiber degradation in Bermuda grass and orchard grass was evaluated gravimetrically and by scanning and transmission electron microscopy after incubation with pure cultures of rumen bacteria.
Lachnospira multiparus
D-32 was unable to degrade plant cell wall components.
Butyrivibrio fibrisolvens
49 degraded 6 and 14.9% of the fiber components in Bermuda grass and orchard grass, respectively, and
Ruminococcus albus
7 degraded 11.4% orchard grass fiber but none in Bermuda grass. Both
B. fibrisolvens
and
R. albus
lacked capsules, did not adhere to fiber, and degraded only portions of the more easily available plant cell walls.
R. flavefaciens
FD-1 was the most active fiber digester, degrading 8.2 and 55.3% of Bermuda and orchard grass fiber, respectively. The microbe had a distinct capsule and adhered to fiber, especially that which is slowly degraded, but was able to cause erosion and disorganization of the more easily digested cell walls, apparently by extracellular enzymes. Results indicated that more digestible cell walls could be partially degraded by enzymes disassociated from cellulolytic and noncellulolytic bacteria, and data were consistent with the hypothesis that the more slowly degraded plant walls required attachment. Microbial species as well as the cell wall architecture influenced the physical association with and digestion of plant fiber.
Liquid-phase study of ozone inactivation of Venezuelan equine encephalomyelitis virus
Authors: Akey D H , Walton T E
Published: January 2020

Ozone, in a liquid-phase application, was evaluated as a residue-free viral inactivant that may be suitable for use in an arboviral research laboratory. Commonly used sterilizing agents may leave trace residues, be flammable or explosive, and require lengthy periods for gases or residues to dissipate after decontamination of equipment such as biological safety cabinets. Complete liquid-phase inactivation of Venezuelan equine encephalomyelitis virus was attained at 0.025 mg of ozone per liter within 45 min of exposure. The inactivation of 10(6.5) median cell culture infective doses (CCID50 of Venezuelan equine encephalomyelitis virus per milliliter represented a reduction of 99.99997% of the viral particles from the control levels of 10(7.25-7.5) CCID50/ml. A dose-response relationship was demonstrated. Analysis by polynomial regression of the logarithmic values for both ozone concentrations and percent reduction of viral titers had a highly significant r2 of 0.8 (F = 63.6; df = 1, 16). These results, together with those of Akey (J. Econ. Entomol. 75:387-392, 1982) on the use of ozone to kill a winged arboviral vector, indicate that ozone is a promising candidate as a sterilizing agent in some applications for biological safety cabinets and other equipment used in vector studies with arboviruses.
Occurrence, growth, and suppression of salmonellae in composted sewage sludge
Authors: Hussong D , Burge W D , Enkiri N K
Published: January 2020

Composted sewage sludge may be used to improve soil quality, but there remains some doubt concerning the microbiological safety of the product. Sewage sludge composts from 30 municipalities were sampled, and four samples (12%) contained salmonellae (two contained fewer than 0.3/g, and the other two had 21/g and 1.7 X 10(4)/g). All 30 composts were inoculated with salmonellae; the populations decreased at a specific death rate of about 0.15 h-1 over 24 h at 36 degrees C. In irradiation-sterilized composts inoculated with salmonellae, the salmonellae grew at a rate of 0.65 doublings per h for over 24 h. Growth and death rates were found to be moisture and flora associated. The growth or death rates for antibiotic-resistant salmonellae were not different from those of nonresistant strains. It was concluded that the active indigenous flora of compost establishes a homeostatic barrier to colonization by salmonellae, and in the absence of competing flora, reinoculated salmonellae may grow to potentially hazardous densities. The active microflora of moist composts eliminated contaminating salmonellae (10(5)/g) after 6 weeks.
Potential for Development of Tolerance by
Penicillium digitatum
and
Penicillium italicum
after Repeated Exposure to Potassium Sorbate
Authors: Schroeder Lisa L. , Bullerman Lloyd B.
Published: January 2020

Two strains of
Penicillium digitatum
and one strain of
Penicillium italicum
were exposed to various levels of sorbic acid and potassium sorbate, and the MICs were determined. Selected strains of the molds were then repeatedly exposed to subinhibitory levels of the compounds to determine whether increased tolerance might develop. The MIC of sorbic acid (pH 4.75) to
P. digitatum
was between 0.02 and 0.025%. The MIC of sorbate (pH 5.5) to two strains of
P. digitatum
and
P. italicum
was found to be between 0.06 and 0.08%. Increasing levels of sorbate resulted in increasing growth suppression of the molds. Populations of
P. digitatum
were tested for increased tolerance to sorbic acid, and none was found. Individual molds that started from the same parent colony were examined for increased tolerance to potassium sorbate. Two
P. digitatum
strains developed no observable increased tolerance, but
P. italicum
developed a slight increase in tolerance to sorbate. When spores of
P. italicum
and
P. digitatum
were exposed to higher levels of sorbate for prolonged times, the fungicidal or fungistatic activity of the inhibitor was dependent upon pH, length of exposure time, level of sorbate, and the mold strain.
Butanediol production from cellulose and hemicellulose by Klebsiella pneumoniae grown in sequential coculture with Trichoderma harzianum
Authors: Yu E K , Deschatelets L , Louis-Seize G , Saddler J N
Published: January 2020

The bioconversion of cellulose and hemicellulose substrates to 2,3-butanediol by a sequential coculture approach was investigated with the cellulolytic fungus Trichoderma harzianum E58 and the fermentative bacterium Klebsiella pneumoniae. Vogel medium optimal for the production of the cellulolytic and xylanolytic enzymes of the fungus was found to be inhibitory to butanediol fermentation. This inhibition appeared to be due to a synergistic effect of various ingredients, particularly the salts, present in the fungal medium. The removal or replacement of such ingredients from Vogel medium led to the relief of fermentation inhibition, but the treatments also resulted in a significant decrease in fungal enzyme production. Resting cells of K. pneumoniae could be used for butanediol production in the fungal medium, indicating that the inhibitory effect on solvent production under such conditions was due to the indirect result of growth inhibition of the bacterial cells. The resting-cell approach could be combined with a fed-batch system for the direct conversion of 8 to 10% (wt/vol) of Solka-Floc or aspenwood xylan to butanediol at over 30% of the theoretical conversion efficiencies.
Efficacy of media and methods for detecting and enumerating Campylobacter jejuni in refrigerated chicken meat
Authors: Beuchat L R
Published: January 2020

A study was undertaken to compare several enrichment and direct isolation media for their suitability to detect and enumerate five strains of Campylobacter jejuni in refrigerated (5 degrees C) chicken meat. The influence of CO2 on survival at 5 degrees C was also investigated. Selective enrichment media evaluated included Preston broth (PB), selective semisolid brucella medium (SSBM), Campylobacter enrichment broth (CEB), VTP brucella-FBP broth (VTP), Rosef and Kapperud Campylobacter enrichment broth (RKCEB), and Doyle and Roman enrichment broth (DREB). Direct isolation agars included Campy brucella agar (CBAP), blood-free Campylobacter medium (BFCM) and modified Butzler agar (MBA). Comminuted chicken meat was inoculated with C. jejuni, sealed under atmospheric gas or CO2, and stored at 5 degrees C for up to 21 days. Viable population was determined by the most-probable-number technique (PB, SSBM, CEB, VTP, and RKCEB, followed by plating on CBAP, BFCM, and MBA), enrichment on DREB, followed by plating on CBAP, BFCM, and MBA, and direct isolation on CBAP, BFCM, and MBA. Without exception, direct plating of samples was superior to the most-probable-number technique for enumerating C. jejuni; MBA was inferior to CBAP and BFCM, and DREB performed at least as well as other enrichment media evaluated. Carbon dioxide afforded protection against death of three of the five strains of C. jejuni tested.
Use of a species-specific DNA hybridization probe for enumerating Bacteroides vulgatus in human feces
Authors: Kuritza A P , Salyers A A
Published: January 2020

pBV-1, a recombinant plasmid that contains a chromosomal DNA fragment from Bacteroides vulgatus, hybridized to DNA from B. vulgatus but not to DNA from other colonic Bacteroides species. This plasmid was used as a DNA probe to detect and enumerate B. vulgatus in pure culture, in mixed cultures, and in a bacterial fraction from human feces. Bacteria in a pure or mixed culture were lysed by heating the culture in NaOH. The DNA in the disrupted cell suspension was then trapped on nitrocellulose paper by vacuum filtration. If fecal samples were used instead of pure or mixed cultures, it was first necessary to partially purify the DNA by low-speed centrifugation (2,000 X g) and phenol-chloroform extraction before filtering. When 32P-labeled pBV-1 was incubated with filters containg B. vulgatus DNA, the amount of radioactivity that bound to the filters was proportional to the number of B. vulgatus filtered as long as the filtering capacity of the nitrocellulose was not exceeded. Using this procedure, we obtained a value for the concentration of B. vulgatus in human feces (2 X 10(10) to 3 X 10(10) per g of dry weight) that is similar to values obtained by other investigators using conventional bacteriological techniques (3 X 10(10) to 6 X 10(10) per g of dry weight). The advantage of the DNA hybridization method over conventional techniques is that it is not necessary to isolate pure cultures of bacteria from complex specimens such as feces. Furthermore, our method bypasses the cumbersome set of biochemical tests normally used to identify anaerobic bacteria. The major limitation of our method is its sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)
Population Dynamics of Sugar Beets,
Rhizoctonia solani
, and
Laetisaria arvalis
: Responses of a Host, Plant Pathogen, and Hyperparasite to Perturbation in the Field
Authors: Allen Michael F. , Boosalis Michael G. , Kerr Eric D. , Muldoon Anne E. , Larsen Harold J.
Published: January 2020

Rhizoctonia solani
causes crown rot of sugar beets, a severe disease that has destroyed up to 60% of the plants in a test field in western Nebraska.
Laetisaria arvalis
, a natural hyperparasite of
Rhizoctonia
spp., was isolated from fields in western Nebraska. To test for the potential for biological control of
R. solani
, in November 1980 (following harvest) we applied various combinations of a nematicide (Telone II; Dow Chemical Co.), a nutrition source (sugar beet pulp), and an inoculum of
L. arvalis
in a randomized block design. Populations of
R. solani, L. arvalis
, and sugar beets were monitored monthly through October 1981 (just after harvest). In control and nematicide plots, the
R. solani
population did not change significantly through time. In plots inoculated with
L. arvalis
, the
R. solani
populations declined through March, concomitant with an increase in
L. arvalis. L. arvalis
then declined with a corresponding increase in the
R. solani
populations. Beet plant numbers declined significantly in all treatments. We suggest that reduction of the
R. solani
populations with the hyperparasite
L. arvalis
is possible but that a stable equilibrium naturally exists.
Effect of bacterial density and substrate concentration on yield coefficients
Authors: Seto M , Alexander M
Published: January 2020

Measurements were made of the yield coefficient during the aerobic metabolism of glucose by a heterogeneous bacterial mixture. Expressed in terms of carbon, the coefficient was approximately 0.48. The value did not vary with initial bacterial densities ranging from 0.4 pg to 40 micrograms of cell carbon per ml and with glucose concentrations ranging from 43 pg to 100 micrograms of carbon per ml. Under all these circumstances, about 44% of the glucose carbon was converted to CO2, and 7.4% was excreted as organic products. The significance of uncharacterized organic substrates contaminating the medium to the coefficients calculated for low glucose concentrations is discussed.
Disinfecting capabilities of oxychlorine compounds
Authors: Noss C I , Olivieri V P
Published: January 2020

The bacterial virus f2 was inactivated by chlorine dioxide at acidic, neutral, and alkaline pH values. The rate of inactivation increased with increasing pH. Chlorine dioxide disproportionation products, chlorite and chlorate, were not active disinfectants. As chlorine dioxide solutions were degraded under alkaline conditions, they displayed reduced viricidal effectiveness, thereby confirming the chlorine dioxide free radical as the active disinfecting species.
Predominance of Fast-Growing
Rhizobium japonicum
in a Soybean Field in the People's Republic of China
Authors: Dowdle Stephen F. , Bohlool B. Ben
Published: January 2020

Soybean rhizobia were isolated from two soils with different cropping histories from Hubei province in central China. The first, from Honghu county, has been under soybean cultivation for decades. All of the isolates obtained from nodules on soybeans growing in this soil were fast-growing, acid-producing rhizobia. However, slow-growing, alkali-producing isolates were obtained at higher dilutions of the same soil. The second soil, from Wuchang county, has been under rice cultivation with no record of previous soybean cultivation. All of the soybean rhizobia recovered from this soil, and at higher dilutions of the soil, were typical slow-growing, alkali-producing isolates. The isolates from both soils were grouped by using intrinsic antibiotic resistance, gel immunodiffusion, and fluorescent-antibody procedures. Representative isolates were tested for symbiotic effectiveness with four soybean cultivars (Peking, Davis, Williams, and Ai Jiao Zao) in a pot experiment. There were significant cultivar-rhizobial interactions. Moreover, on each cultivar, there was at least one fast-growing isolate among these new rhizobia that was as effective as the highly effective slow-growing reference strain USDA 110.
Synthetic oligodeoxyribonucleotide probes for detecting heat-stable enterotoxin-producing Escherichia coli by DNA colony hybridization
Authors: Hill W E , Payne W L , Zon G , Moseley S L
Published: January 2020

DNA colony hybridization was used to identify and enumerate enterotoxigenic Escherichia coli strains in foods. The cells were identified and enumerated by using synthetic polynucleotide probes for the heat-stable enterotoxin genes. These 22-base oligonucleotides, made from known nucleotide sequences of the genes for the heat-stable enterotoxins of human and porcine strains of E. coli, contain two mismatches between the two heat-stable enterotoxins. Colonies were replicated from agar medium onto paper filters and lysed with alkali followed by steam; probes were end labeled. After overnight hybridization at 40 degrees C and washing at 50 degrees C, autoradiograms were exposed at -70 degrees C. Results were consistent with suckling-mouse tests for heat-stable enterotoxins. A stronger signal was obtained on paper filters than on nitrocellulose filters. Enterotoxigenic E. coli cells were detected when mixed with a 1,000-fold excess of nonenterotoxigenic E. coli cells. This procedure appears to be more acceptable for routine testing than the use of cloned DNA fragments, labeling by nick translation, and lysing colonies on nitrocellulose filters.
Selective detection and enumeration of fecal coliforms in water by potentiometric measurement of lipoic acid reduction
Authors: Jouenne T , Junter G A , Charriere G
Published: January 2020

Water samples of various origins were inoculated into a specific coliform-selective lactose broth provided with lipoic (thioctic) acid, and the time evolution of the redox potential of the cultures was monitored during incubation at 41 degrees C by use of gold versus reference electrodes. Positive potential-time responses, i.e., 100-mV potential shifts recorded within 20 h of inoculation, were related to the initial number of fecal coliforms in the broth determined by control enumeration techniques, and the organisms responsible were isolated and identified by conventional procedures. A total of 30 samples of wastewater, 38 of surface water, 553 of groundwater, and 110 of drinking water were tested successively. A total of 240 natural water samples, including 172 groundwater samples, and 1 drinking water sample were found to be positive in the potentiometric test. The majority (i.e., 92.5%) of the relevant potentiometric detection times were shorter than 15 h, and 96% of these could be attributed to Escherichia coli. Fifteen hours corresponded to the limit for detecting 1 E. coli cell per 100 ml of water. About 78% of the potentiometric responses occurring after 15 h were induced by fecal coliforms other than E. coli (Enterobacter cloacae, Klebsiella pneumoniae, and Citrobacter freundii). Calibration curves relating detection times shorter than 15 h to fecal coliform (i.e., E. coli) concentrations were constructed for the natural water samples tested. There were minor variations in the average growth rate of the organisms in the relation to the contamination level of the water tested. The number of false-positive samples in the potentiometric test was equivalent to that of false-negative samples (groundwater or drinking water).
Characterization of dysgonic, heterotrophic bacteria from drinking water
Authors: Spino D F
Published: January 2020

Only a small percentage of the heterotrophic bacteria encountered in water distribution systems are identifiable, because of these organisms fail to grow on the conventional media used for biochemical characterization. Organisms that would not subculture from the same standard plate count agar used for initial isolation were successfully subcultured on a low-nutrient medium, R3A. These cultures were then inoculated to a modified O/F base medium containing specific substrates. This, combined with a lower incubation temperature (30 degrees C), increased the enzymatic activity of many of the organisms. These reactions established a groundwork for tentative taxonomy.
Isolation and partial characterization of the extracellular polysaccharides and lipopolysaccharides from fast-growing Rhizobium japonicum USDA 205 and its Nod- mutant, HC205, which lacks the symbiotic plasmid
Authors: Carlson R W , Yadav M
Published: January 2020

The extracellular polysaccharides and lipopolysaccharides (LPSs) from two fast-growing Rhizobium japonicum strains, USDA 205 and HC205, were isolated and partially characterized. Strain HC205 is a Nod- mutant of USDA 205 which lacks the symbiotic plasmid. The extracellular polysaccharides from both strains are very similar in composition, having galactose, glucose, glucuronic acid, and acyl groups. The extracellular polysaccharides do not contain detectable levels of pyruvate. Methylation analysis shows that the extracellular polysaccharides from both strains have the same glycosyl linkages. The LPSs were purified by a modified phenol-water extraction procedure and gel filtration chromatography. The LPSs from USDA 205 and HC205 elute as broad peaks from the gel filtration column and contain 2-keto-3-deoxyoctonic acid as one of the major sugar components. Each broad 2-keto-3-deoxyoctonic acid-containing peak has a distinct shoulder on its leading edge. The shoulder and the remainder of the broad peak are separated and labeled LPSI and LPSII, respectively. Glucose (and 2-keto-3-deoxyoctonic acid) is a major sugar in the LPSI fractions. Both the LPSII fractions contain 2-keto-3-deoxyoctonic acid as the major sugar (about 20% of the mass). There are a number of quantitative differences in these LPS fractions between strain USDA 205 and HC205. Polyacrylamide gel electrophoresis shows that the LPSs are heterogeneous molecules but less heterogeneous than the LPSs from Salmonella minnesota or Rhizobium leguminosarum. The LPSI fractions from both USDA 205 and HC205 show a single lower-molecular-weight band and a higher-molecular-weight banding region which contains several bands. No bands are observed for the LPSII fractions from either USDA 205 or HC205.
Detoxification of mercury, cadmium, and lead in Klebsiella aerogenes NCTC 418 growing in continuous culture
Authors: Aiking H , Govers H , van 't Riet J
Published: January 2020

Klebsiella aerogenes NCTC 418 growing in the presence of cadmium under glucose-, sulfate-, or phosphate-limited conditions in continuous culture exhibited sulfide formation and Pi accumulation as the only demonstrable detoxification mechanisms. In the presence of mercury under similar conditions only HgS formation could be confirmed, by an increased sensitivity to mercury under sulfate-limited conditions, among others. The fact that the cells were most sensitive to cadmium under conditions of phosphate limitation and most sensitive to mercury under conditions of sulfate limitation led to the hypothesis that these inorganic detoxification mechanisms generally depended on a kind of "facilitated precipitation". The process was coined thus because heavy metals were probably accumulated and precipitated near the cell perimeter due to the relatively high local concentrations of sulfide and phosphate there. Depending on the growth-limiting nutrient, mercury proved to be 25-fold (phosphate limitation), 75-fold (glycerol limitation), or 150-fold (sulfate limitation) more toxic than cadmium to this organism. In the presence of lead, PbS formation was suggested. Since no other detoxification mechanisms were detected, for example, rendering heavy metal ions innocuous as metallo-organic compounds, it was concluded that formation of heavy metal precipitates is crucially important to this organism. In addition, it was observed that several components of a defined mineral medium were able to reduce mercuric ions to elemental mercury. This abiotic mercury volatilization was studied in detail, and its general and environmental implications are discussed.
Molecular analysis confirms food source and simultaneous involvement of two distinct but related subgroups of Salmonella typhimurium bacteriophage type 10 in major interprovincial Salmonella outbreak
Authors: Bezanson G S , Khakhria R , Duck D , Lior H
Published: January 2020

More than 2,000 confirmed cases of food poisoning occurred in the four Atlantic provinces of Canada and in Ontario during the second and third quarters of 1984. Salmonella typhimurium phage type 10 was identified as the etiologic agent, and cheddar cheese was implicated as the source of infection. Strains isolated from infected humans and from cheese were indistinguishable by biotyping, antibiotic resistance typing, and phage typing. Plasmid analysis confirmed cheese as the source of infection and revealed the presence of two molecular subgroups of bacteriophage type 10. Group I strains carried 57-, 22.3-, and 3.4-kilobase (kb) plasmids; group II strains carried 57-, 4.6-, and 3.4-kb plasmids. Digestion with endonucleases HaeIII, HpaII, and AvaIII indicated that the 3.4-kb plasmids were identical. This outbreak was, therefore, caused by a mixed infection with two distinct but related bacteria. Group I strains are fairly common among Canadian S. typhimurium phage type 10 isolates, whereas group II strains appeared to be unique to this outbreak.
Effect of the rehydration medium on the recovery of freeze-dried lactic acid bacteria
Authors: de Valdez G F , de Giori G S , de Ruiz Holgado A P , Oliver G
Published: January 2020

Sixteen cultures of lactic acid bacteria were freeze-dried in 10% nonfat skim milk plus 0.75 M adonitol and rehydrated by using different rehydration media. Marked variations in their capacity to repair cellular damage after freeze-drying were observed among the species and strains under consideration.
Factors associated with Pseudomonas pickettii intrinsic contamination of commercial respiratory therapy solutions marketed as sterile
Authors: Anderson R L , Bland L A , Favero M S , McNeil M M , Davis B J , Mackel D C , Gravelle C R
Published: January 2020

Laboratory investigations were conducted to study the growth dynamics of Pseudomonas pickettii in commercial 0.9% sodium chloride solution under various environmental conditions and to determine the retention of these organisms after challenge through a 0.2-micron cartridge filter system. Low numbers of P. pickettii (1 to 10 CFU/ml of test solution) inoculated into commercial vials containing 5 ml of 0.9% sodium chloride solution and 500-ml volumes of 0.9% sodium chloride solution were shown to proliferate over a 168-h incubation period. These organisms demonstrated growth over a wide range of temperatures (15 to 42 degrees C) in this salt solution, and survival studies at 50, 55, and 60 degrees C indicated that this strain was not unusually resistant to heat (with the times required at a given temperature to reduce the surviving microbial population 10-fold [D-values] being 26.0, 1.9, and 0.7 min, respectively). A challenge test demonstrated that P. pickettii organisms were not completely retained by a 0.2-micron cartridge filter. The number of organisms detected increased from 1 CFU/liter of effluent at 1 to 2 min to a maximum of 176 CFU/liter at 4 to 5 min. Our results indicate that P. pickettii can penetrate a 0.2-micron filtration system and that the passage of organisms and subsequent microbial growth in the filter effluent probably are the mechanisms by which these organisms were recovered from "sterile" commercial 0.9% sodium chloride solution.
Growth and persistence of pathogens on granular activated carbon filters
Authors: Camper A K , LeChevallier M W , Broadaway S C , McFeters G A
Published: January 2020

Three enteric pathogens Yersinia enterocolitica O:8, Salmonella typhimurium, and enterotoxigenic Escherichia coli, were examined for their ability to colonize granular activated carbon (GAC) in pure cultures and in the presence of autochthonous river water organisms. All three organisms readily colonized sterile GAC and maintained populations of ca. 10(5) to 10(7) CFU g-1 for 14 days when suspended in sterile river water. Exposure of pathogen biofilms on GAC to unsterile river water resulted in a gradual decline in pathogens on the carbon (0.08 to 0.14 log day-1). When pathogens were introduced to sterile GAC in the presence of heterotrophic plate count organisms, they attached at levels similar to those in the pure cultures and then decreased (0.10 to 0.22 log day-1). When added with heterotrophic plate count bacteria to GAC supporting a mature biofilm of native river water bacteria, they attached at a lower level (1.0 X 10(4) to 4.6 X 10(4) CFU g-1) and decreased at a more rapid rate (0.11 to 0.70 log day-1).
Characterization and distribution of Vibrio alginolyticus and Vibrio parahaemolyticus isolated in Indonesia
Authors: Molitoris E , Joseph S W , Krichevsky M I , Sindhuhardja W , Colwell R R
Published: January 2020

Previous studies have shown that Vibrio alginolyticus and Vibrio parahaemolyticus can be isolated from similar types of marine samples. In this report, the results of an examination of 567 V. alginolyticus and V. parahaemolyticus strains, isolated from seawater in Jakarta Bay and from more than 30 types of seafood from markets in Jakarta, Indonesia, are presented. Most isolates were from mackerel, shrimp, or squid. Numerical taxonomic analyses clustered 337 isolates and three V. alginolyticus reference strains at S greater than or equal to 80%. These strains produced acid from sucrose, but only approximately 80% produced acetoin or grew in the presence of 10% NaCl. The frequency of occurrence of V. alginolyticus in seawater samples ranged from 0% (in February and March 1972) to 100% (in September and December 1972) and was highest in seafood samples from August to December 1972. A second cluster of 230 isolates and seven V. parahaemolyticus reference strains was observed at S greater than or equal to 82%. These strains did not produce acetoin or acid from sucrose, and approximately 20% grew in the presence of 10% NaCl. V. parahaemolyticus was detected in seawater samples each month, with the highest frequency of occurrence (83.3%) in May 1972. Twenty-nine K antigen serotypes were demonstrated in V. parahaemolyticus isolates, and another 40% were untypable. The modal antibiotic resistance pattern for each species included five drugs. Only 12% of the V. parahaemolyticus strains were Kanagawa positive, and 10% elicited fluid accumulation in ligated rabbit ileal loops. All of the 7 V. alginolyticus strains and 94 (70%) of the V. parahaemolyticus strains tested killed mice when inoculated intraperitoneally.(ABSTRACT TRUNCATED AT 250 WORDS)
Purification and Characterization of Extracellular Amylolytic Enzymes from the Yeast
Filobasidium capsuligenum
Authors: De Mot Ren� , Verachtert Hubert
Published: January 2020

The extracellular amylolytic system of
Filobasidium capsuligenum
consisted of an α-amylase (1,4-α-
d
-glucan glucanhydrolase, EC 3.2.1.1) and two forms of glucoamylase (1,4-α-
d
-glucan glucohydrolase, EC 3.2.1.3). The enzymes were purified by ammonium sulfate fractionation, repeated ion-exchange chromatography (DEAE-Sephadex A-50), and gel filtration (Sephadex G-25, Sephadex G-100 sf). α-Amylase had an optimum pH of 5.6 and an optimum temperature of 50�C but was rapidly inactivated at higher temperature. The molecular weight was estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be 64,000. An acarbose concentration of 20 μg/ml was required for 50% inhibition of the α-amylase. Both glucoamylases are glycoproteins of identical molecular weight (60,000) and produce only glucose by exohydrolysis. The debranching activity of the glucoamylases was evidenced with substrates containing α-1,6 linkages. The pH optima were 5.0 to 5.6 for glucoamylase I and 4.8 to 5.3 for glucoamylase II. Glucoamylase I had a higher optimum temperature (55�C) than glucoamylase II (50�C) and was also more resistant to thermal inactivation. Only low acarbose concentrations (<0.1 μg/ml) were required to reduce the activity of the glucoamylases by 50%.
Temporal Occurrence of
Vibrio
Species and
Aeromonas hydrophila
in Estuarine Sediments
Authors: Williams Leslee A. , LaRock Paul A.
Published: January 2020

Marine sediments were assayed for their concentration of
Vibrio
spp. and
Aeromonas hydrophila
over 1 year. A temporal variation was observed in which
A. hydrophila
, and to a lesser degree
V. fluvialis
, were found in the winter months,
V. parahaemolyticus
and
V. vulnificus
predominated in the spring and summer, with non-O-1
V. cholerae
and
V. alginolyticus
detected in the late summer and fall. These organisms were found in greatest numbers in the top 5 cm of sediment, but were detectable down to 15 cm. Epidemiological data revealed a predominance of non-O-1
V. cholerae
infections at the time the organisms were observed to flourish in the sediments.
Survival of
Bacillus thuringiensis
Spores in Soil
Authors: Petras Stephen F. , Casida L. E.
Published: January 2020

Bacillus thuringiensis
spores and parasporal crystals were incubated in natural soil, both in the laboratory and in nature. During the first 2 weeks, the spore count decreased by approximately 1 log. Thereafter, the number of spore CFU remained constant for at least 8 months.
B. thuringiensis
did not lose its ability to make the parasporal crystals during its residence in soil. Spore survival was similar for a commercial spore-crystal preparation (the insecticide) and for laboratory-grown spores. In contrast to these results, spores that were produced in situ in soil through multiplication of added vegetative cells survived for only a short time. For spore additions to soil, variations in soil pH had little effect on survival for those spores that survived the first 2 weeks of incubation. Also without effect were various pretreatments of the spores before incubation in soil or nutritional amendment or desiccation of the soil. Remoistening of a desiccated soil, however, caused a decrease in spore numbers. Spores incubated in soil in the field did not show this, but the degree of soil desiccation in nature probably never reached that for the laboratory samples. The good survival of
B. thuringiensis
spores after the first 2 weeks in soil seemed to be a result of their inability to germinate in soil. We found no evidence for the hypothesis that rapid germination ability for spores in soil conferred a survival advantage.
Arylglycerol-γ-Formyl Ester as an Aromatic Ring Cleavage Product of Nonphenolic β-
O
-4 Lignin Substructure Model Compounds Degraded by
Coriolus versicolor
Authors: Kawai Shingo , Umezawa Toshiaki , Higuchi Takayoshi
Published: January 2020

4-Ethoxy-3-methoxyphenylglycerol-γ-formyl ester (compound IV) was identified as a degradation product of both 4-ethoxy-3-methoxyphenylglycerol-β-syringaldehyde ether (compound I) and 4-ethoxy-3-methoxyphenylglycerol-β-2,6-dimethoxyphenyl ether (compound II) by a ligninolytic culture of
Coriolus versicolor
. An isotopic experiment with a
13
C-labeled compound (compound II′) indicated that the formyl group of compound IV was derived from the β-phenoxyl group of β-
O
-4 dimer as an aromatic ring cleavage fragment. However, compound IV was not formed from 4-ethoxy-3-methoxyphenylglycerol-β-guaiacyl ether (compound III). γ-Formyl arylglycerol (compound IV) could be a precursor of 4-ethoxy-3-methoxyphenylglycerol (compound VI), because 3-(4-ethoxy-3-methoxyphenyl)-1-formyloxy propane (compound VII) was cleaved to give 3-(4-ethoxy-3-methoxyphenyl)-1-propanol (compound VIII) by
C. versicolor
. 4-Ethoxy-3-methoxyphenylglycerol-β,γ-cyclic carbonate (compound V), previously found as a degradation product of compound III by
Phanerochaete chrysosporium
(T. Umezawa, and T. Higuchi, FEBS Lett., 25:123-126, 1985), was also identified from the cultures with compound I, II, and III and degraded to give the arylglycerol (compound VI). An isotopic experiment with
13
C-labeled compounds II′ and III′ indicated that the carbonate carbon of compound V was derived from the β-phenoxyl groups of β-
O
-4 substructure.
Effect of Temperature on Composting of Sewage Sludge
Authors: Nakasaki Kiyohiko , Shoda Makoto , Kubota Hiroshi
Published: January 2020

The effect of temperature on the composting reaction of sewage sludge was investigated at 50, 60, and 70�C. The total amount of CO
2
evolved and the final conversion of volatile matter were maximum at 60�C., suggesting that the optimal temperature for composting was around 60�C. The specific CO
2
evolution rate (moles of CO
2
evolved per hour per viable cell) was maximum at 70�C. The isolated thermophilic bacterium which was dominant at 60�C but did not grow at 70�C showed that the rate of O
2
consumption measured on the agar plate at 70�C was four times higher than that at 60�C. This showed that the energy yielded from catabolism is rather uncoupled with the anabolism at 70�C in the metabolism of microorganisms indigenous in the compost. A higher respiratory quotient was observed at 70�C than at any other temperature.
Association of a 13.6-Megadalton Plasmid in
Pediococcus pentosaceus
with Bacteriocin Activity
Authors: Daeschel Mark A. , Klaenhammer Todd R.
Published: January 2020

Pediococcus pentosaceus
FBB61 and L7230, isolated from cucumber fermentations, produced a bacteriocin, designated pediocin A, which had identical activity spectra against species of
Pediococcus, Clostridium, Staphylococcus
, and
Streptococcus
. Both strains possessed a 13.6-megadalton plasmid (pMD136). Plasmid curing experiments suggested that both bacteriocin immunity and production determinants were encoded by pMD136. Use of pediocin-producing strains in food fermentations is discussed.

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Interaction of
Pseudomonas putida
ATCC 12633 and Bacteriophage gh-1 in Berea Sandstone Rock
Authors: Chang Philip Lee , Yen Teh Fu
Published: January 2020

Measurements of the passage of
Pseudomonas putida
ATCC 12633 and a phage-resistant mutant through Berea sandstone rock were made. When bacteriophage gh-1 was adsorbed within the rock matrix, a reduction in the passage of the susceptible but not the resistant cells through the rock was observed.