bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbial transformation of quinoline by a Pseudomonas sp
Authors: Shukla O P
Published: January 2020

A Pseudomonas sp. isolated from sewage by enrichment culture on quinoline metabolized this substrate by a novel pathway involving 8-hydroxycoumarin. During early growth of the organism on quinoline, 2-hydroxyquinoline accumulated as the intermediate; 8-hydroxycoumarin accumulated as the major metabolite on further incubation. 2,8-Dihydroxyquinoline and 2,3-dihydroxyphenylpropionic acid were identified as the other intermediates. Inhibition of quinoline metabolism by 1 mM sodium arsenite led to the accumulation of pyruvate, whereas inhibition by 5 mM arsenite resulted in the accumulation of 2-hydroxyquinoline as the major metabolite and 2,8-dihydroxyquinoline as the minor metabolite. Coumarin was not utilized as a growth substrate by this bacterium, but quinoline-grown cells converted it to 2-hydroxyphenylpropionic acid, which was not further metabolized. Quinoline, 2-hydroxyquinoline, 8-hydroxycoumarin, and 2,3-dihydroxyphenylpropionic acid were rapidly oxidized by quinoline-adapted cells, whereas 2,8-dihydroxyquinoline was oxidized very slowly. Quinoline catabolism in this Pseudomonas sp. is therefore initiated by hydroxylation(s) of the molecule followed by cleavage of the pyridine ring to yield 8-hydroxycoumarin, which is further metabolized via 2,3-dihydroxyphenylpropionic acid.
Contribution of protozoa to lysine synthesis in the in vitro rumen microbial ecosystem
Authors: Onodera R
Published: January 2020

Isotopic tracer experiments were conducted in vitro to determine contribution of protozoa toward the biosynthesis of lysine in the rumen microbial ecosystem. The presence of protozoa in a rumen microbial suspension always increased lysine synthesis from aspartate. Rumen contents from a faunated goat produced a higher amount of lysine than did those from a defaunated one.
Identification of epsilon-N-mono-, epsilon-N-di-, and epsilon-N-trimethyllysine by high-performance liquid chromatography
Authors: Garcia R , Hiatt W R , Jasinski S , Sypherd P S
Published: January 2020

Dansyl derivatives of epsilon-N-mono-, epsilon-N-di-, and epsilon-N-trimethyllysine were resolved from other amino acids in proteins by the use of high-performance liquid chromatography. The system was tested with amino acid standard combinations as well as with acid-hydrolyzed proteins known to contain methylated residues. In all cases the methylated lysines were well resolved.
Toxicity of organic acids for repair-deficient strains of Escherichia coli
Authors: Sinha R P
Published: January 2020

The wild-type strain and four DNA repair-deficient strains (uvrA6, uvrB5, recA56, and polA1) of Escherichia coli K-12 were treated with acetic acid, lactic acid, and p-aminobenzoic acid at pH 3.5 during their stationary phase of growth. All three acids were highly toxic to the polymerase-deficient strain. The greater sensitivity of the strain carrying the polA1 gene than its isogenic pol+ derivatives suggested that damage caused by acidity requires polA+ gene products for repair.
Production and Use of Monoclonal Antibodies for Identification of Strains of
Rhizobium trifolii
Authors: Wright Sara F. , Foster Joyce G. , Bennett Orus L.
Published: January 2020

We produced a monoclonal antibody against
Rhizobium trifolii
162×95. This antibody in cell culture supernatant was used in an indirect enzyme-linked immunosorbent assay to differentiate strain 162×95 from naturalized strains in the Appalachian region. Nodules crushed in 0.1 to 0.2 ml of phosphate-buffered saline and used to charge enzyme-linked immunosorbent assay plates gave strong absorbance readings. Heat-inactivated and noninactivated portions of 162×95 cultures were strongly reactive, indicating that the antigen is probably a carbohydrate. Of 10 strains from California, where 162×95 was isolated, 6 strongly cross-reacted with the antibody. The cellular protein patterns in a sodium dodecyl sulfate-polyacrylamide gradient gel of cross-reactive strains were essentially identical. A Western blot analysis indicated that the antibody was against a 19.8-kilodalton band. The Western blot analysis also revealed that the polyvalent antiserum contained other strongly reacting antibodies with molecular weights of approximately 20,000, indicating the possibility that other monoclonal antibodies to detect strain 162×95 may be produced. However, the available antibody has been shown to be useful for short-term experiments. Based upon protein profiles and immunological reactions, there are 4 or 5 California strains rather than 10.
Seasonal Population Changes and Characterization of Ice-Nucleating Bacteria in Farm Fields of Central Alberta
Authors: Kaneda Toshi
Published: January 2020

During the summer of 1983 in central Alberta, changes in the bacterial population inhabiting the leaves of field beans (
Phaseolus vulgaris
L.) and canola (
Brassica napus
L. Altex) were studied to determine if ice-nucleating bacteria were present on these plants. Three colony types (white, yellow, and peach-colored) were found on field beans and canola leaves. Approximately 25% of the isolates from the white colony group, which dominated the population, were ice-nucleating bacteria. No ice-nucleating bacteria were present on canola leaves. Out of a total of 76 ice-nucleating bacteria isolated, 5 representative cultures were characterized in detail and identified as
Pseudomonas fluorescens
. The fatty acid composition of these cultures was essentially identical to that of typical
P. fluorescens
cultures and was altered by varying the growth temperature from 10 to 30°C.
Plasmid carriage in Vibrio vulnificus and other lactose-fermenting marine vibrios
Authors: Davidson L S , Oliver J D
Published: January 2020

A total of 42 clinical and environmental isolates of Vibrio vulnificus were examined for plasmid carriage. Of these, only five (12%) harbored plasmids, which were of various molecular weights. In contrast, 20 of 32 (62.5%) unidentified lactose-fermenting Vibrio spp. were found to possess plasmids with masses of 2.1 to 150 megadaltons. In these isolates, multiple plasmids were common, with an average of 2.25 plasmids per plasmid-containing strain. Attempts to demonstrate a correlation with the plasmids identified in the various Vibrio spp. and a variety of phenotypic traits, production of several enzymes potentially involved in virulence, cytotoxicity for Chinese hamster ovary cells, and mouse lethality were unsuccessful. A correlation was observed, however, between the presence of a 6.5-megadalton plasmid and resistance to pteridine 0/129. It was concluded that V. vulnificus, unlike most other Vibrio spp., shows a general lack of these extrachromosomal elements.
Lethal effect of butylated hydroxyanisole as related to bacterial fatty acid composition
Authors: Post L S , Davidson P M
Published: January 2020

Bacillus cereus, Clostridium perfringens, Staphylococcus aureus, Pseudomonas fluorescens, Pseudomonas fragi, Escherichia coli, and Salmonella "anatum" were challenged with butylated hydroxyanisole (BHA). Susceptibility was measured as the concentration of BHA required to cause a 90% reduction in bacterial survivors. Staphylococcus aureus LP and P. fragi were two of the most resistant species examined; C. perfringens and P. fluorescens were the most susceptible. Gram stain reaction was found not to be a strict indicator of bacterial susceptibility to BHA. There was no obvious relationship between individual fatty acids and susceptibility. The ratio of saturated to unsaturated fatty acids in the total lipid fraction of only the gram-positive species was related to susceptibility. The ratios of saturated to unsaturated fatty acids of other fractions were not related to susceptibility.
Carbon and Nitrogen Content of Natural Planktonic Bacteria
Authors: Nagata Toshi
Published: January 2020

A method of estimating carbon and nitrogen content per unit of natural bacterial cell volume was developed. This method is based on the difference in the retentiveness of bacteria between two kinds of glass fiber filter, GF/C and GF/F (Whatman, Inc., Clifton, N.J.). Biovolume and biomass (carbon and nitrogen content) of bacteria which passed through the GF/C but not the GF/F filter were estimated with an epifluorescence microscopy and a CHN analyzer, respectively. From seasonal determinations of natural planktonic bacteria in epilimnetic waters of a mesotrophic lake, the conversion factors of 106 fg of C/μm
3
and 25 fg of N/μm
3
were derived as average values. By using these values, the contribution of bacteria to the biomass of lake plankton is discussed.
Evidence that polygalacturonic acid may not be a major source of carbon and energy for some colonic Bacteroides species
Authors: McCarthy R E , Salyers A A
Published: January 2020

Five Bacteroides species that are found in the human colon can utilize polygalacturonic acid (PGA) when they are grown in laboratory media: Bacteroides thetaiotaomicron, Bacteroides vulgatus, Bacteroides ovatus, Bacteroides fragilis subsp. a, and Bacteroides sp. strain 3452A (an unnamed DNA-DNA homology group). PGA-degrading enzymes from B. thetaiotaomicron have been isolated and characterized previously. To determine whether a PGA lyase activity in human feces could be attributed to any of these species, we first determined the properties of PGA lyases from the other four Bacteroides species. PGA lyases from all the Bacteroides species were soluble, cell associated, and inducible by PGA. All had similar pH optima (8.4 to 8.8) and similar molecular weights (50,000). All activities were enhanced by calcium. The PGA lyases from the five species differed with respect to isoelectric point: B. thetaiotaomicron (pI 7.5), B. vulgatus (pI 7.7), B. ovatus (pI 5.8, 7.2), B. fragilis subsp. a (pI 6.1), and Bacteroides sp. strain 3452A (pI 7.7). The PGA lyase activity in human feces resembled those of the Bacteroides PGA lyases in that it had a pH optimum of 8.4 to 8.8 and was enhanced by calcium. However, it differed from the Bacteroides PGA lyases both with respect to isoelectric point (pI 4.2 to 4.4) and molecular weight (100,000). On the basis of these findings, it appears that the PGA lyase activity in human feces is not produced by any of the Bacteroides species surveyed in this survey. Moreover, there was no detectable PGA lyase activity in feces that had the same properties as the Bacteroides enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)
Ultrastructural Aspects of Wood Delignification by
Phlebia (Merulius) tremellosus
Authors: Blanchette R. A. , Reid I. D.
Published: January 2020

Wood from aspen and birch that had been decayed for 12 weeks by
Phlebia tremellosus
had averages of 30 and 31% weight loss, respectively, and 70% lignin loss. Digestibility increased from averages of 21 and 13% for sound aspen and birch to 54 and 51% for decayed aspen and birch. Individual wood sugar analyses of decayed birch blocks indicated an average loss of 10% glucose, 45% xylose, and 19% mannose. Micromorphological studies demonstrated the removal of middle lamellae and separation of cells. Vessels also separated at perforation plates. Electron microscopy with OsO
4
-glutaraldehyde-fixed and KMnO
4
-fixed wood showed that lignin was progressively removed first from the secondary cell wall layers, beginning at the lumen surface, and later from the compound middle lamella. Extensive degradation of lignin was found throughout the secondary wall and middle lamella region between cells. In cells with advanced decay, the middle lamella between cells was completely degraded, but cell corner regions remained.
Role of Veratryl Alcohol in Regulating Ligninase Activity in
Phanerochaete chrysosporium
Authors: Faison Brendlyn D. , Kirk T. Kent , Farrell Roberta L.
Published: January 2020

Ligninase activity in
Phanerochaete chrysosporium
is stimulated by incubating cultures with various substrates for the enzyme, including veratryl (3,4-dimethoxybenzyl) alcohol, which is a secondary metabolite of this fungus. This study was designed to provide insight into the mechanism involved in this stimulation. Ligninase activity increased 2 to 4 h after the addition of exogenous veratryl alcohol to ligninolytic cultures. This increase was prevented by inhibitors of protein synthesis. Analysis of the extracellular proteins by high-performance anion-exchange liquid chromatography revealed increases in the amounts of some, but not all, ligninase species. The normal rapid decrease in ligninase activity in aging cultures was not prevented or retarded by veratryl alcohol, indicating that veratryl alcohol does not increase ligninase activity by protecting extant enzyme. We conclude that veratryl alcohol probably functions via an induction type of mechanism, affecting only certain ligninase species. Results with an isolated lignin indicate that lignin (or its biodegradation products) functions in the same way that veratryl alcohol does.
Microbial release of 226Ra2+ from (Ba,Ra)SO4 sludges from uranium mine wastes
Authors: Fedorak P M , Westlake D W , Anders C , Kratochvil B , Motkosky N , Anderson W B , Huck P M
Published: January 2020

226Ra2+ is removed from uranium mine effluents by coprecipitation with BaSO4. (Ba,Ra)SO4 sludge samples from two Canadian mine sites were found to contain active heterotrophic populations of aerobic, anaerobic, denitrifying, and sulfate-reducing bacteria. Under laboratory conditions, sulfate reduction occurred in batch cultures when carbon sources such as acetate, glucose, glycollate, lactate, or pyruvate were added to samples of (Ba,Ra)SO4 sludge. No external sources of nitrogen or phosphate were required for this activity. Further studies with lactate supplementation showed that once the soluble SO4(2-) in the overlying water was depleted, Ba2+ and 226Ra2+ were dissolved from the (Ba,Ra)SO4 sludge, with the concurrent production of S2-. Levels of dissolved 226Ra2+ reached approximately 400 Bq/liter after 10 weeks of incubation. Results suggest that the ultimate disposal of these sludges must maintain conditions to minimize the activity of the indigenous sulfate-reducing bacteria to ensure that unacceptably high levels of 226Ra2+ are not released to the environment.
Utilization of Methanol plus Hydrogen by
Methanosarcina barkeri
for Methanogenesis and Growth
Authors: Müller Volker , Blaut Michael , Gottschalk Gerhard
Published: January 2020

Methanosarcina barkeri
grew on methanol plus H
2
. Both substrates were consumed in equimolar amounts. Growth was strictly dependent on the presence of acetate, which was required for the biosynthesis of cellular constituents. Only about 0.4% of the methane produced originated from acetate. By using deuterated methanol, it was demonstrated that methanogenesis from this compound under H
2
did not occur via oxidation of methanol to CO
2
and subsequent reduction but by direct reduction with H
2
. Growth yields with methanol plus H
2
and with methanol alone were not significantly different: 2.8 g of cells per mol of methanol in mineral medium and 4.6 g of cells per mol of methanol in complex medium, respectively. Growth of
M. barkeri
on methanol plus H
2
depended strictly on the presence of sodium ions in the medium. In the presence of 50 mM K
+
the

K
s

for Na
+
was 5 mM.
Influence of Forage Phenolics on Ruminal Fibrolytic Bacteria and In Vitro Fiber Degradation
Authors: Varel Vincent H. , Jung Hans-Joachim G.
Published: January 2020

In vitro cultures of ruminal microorganisms were used to determine the effect of cinnamic acid and vanillin on the digestibility of cellulose and xylan. Cinnamic acid and vanillin depressed in vitro dry matter disappearance of cellulose 14 and 49%, respectively, when rumen fluid was the inoculum. The number of viable
Bacteroides succinogenes
cells, the predominant cellulolytic organism, was threefold higher for fermentations which contained vanillin than for control fermentations. When xylan replaced cellulose as the substrate, a 14% decrease in the digestibility of xylan was observed with vanillin added; however, the number of viable xylanolytic bacteria cultured from the batch fermentation was 10-fold greater than that of control fermentations. The doubling time of
B. succinogenes
was increased from 2.32 to 2.58 h when vanillin was added to cellobiose medium, and absorbance was one-half that of controls after 18 h. The growth rate of
Ruminococcus albus
and
Ruminococcus flavefaciens
was inhibited more by
p
-coumaric acid than by vanillin, although no reduction of final absorbance was observed in their growth cycles. Vanillin, and to a lesser extent cinnamic acid, appeared to prevent the attachment of
B. succinogenes
cells to cellulose particles, but did not affect dissociation of cells from the particles.
B. succinogenes, R. albus, R. flavefaciens
, and
Butyrivibrio fibrisolvens
all modified the parent monomers cinnamic acid,
p
-coumaric acid, ferulic acid, and vanillin, with
B. fibrisolvens
causing the most extensive modification. These results suggest that phenolic monomers can inhibit digestibility of cellulose and xylan, possibly by influencing attachment of the fibrolytic microorganisms to fiber particles. The reduced bacterial attachment to structural carbohydrates in the presence of vanillin may generate more free-floating fibrolytic organisms, thus giving a deceptively higher viable count.
Rates of dissolution and biodegradation of water-insoluble organic compounds
Authors: Thomas J M , Yordy J R , Amador J A , Alexander M
Published: January 2020

We conducted a study of the relationship between the dissolution rates of organic compounds that are sparingly soluble in water and the biodegradation of these compounds by mixed cultures of bacteria. The rates of dissolution of naphthalene and 4-chlorobiphenyl were directly related to their surface areas. The bacteria caused a decline in the concentration of the soluble substrate. The rate of bacterial growth fell abruptly when 4-chlorobiphenyl or naphthalene was no longer detectable in solution. The population continued to increase in media with different surface areas of insoluble 4-chlorobiphenyl, but the final counts were higher in media in which the surface areas of the substrate were larger. The rates of dissolution of palmitic acid, octadecane, di(2-ethylhexyl) phthalate, and 1-naphthyl N-methylcarbamate were determined in the absence of microorganisms. A mixed culture of microorganisms mineralized palmitic acid, di(2-ethylhexyl) phthalate, and Sevin (1-naphthyl N-methylcarbamate) at a logarithmic rate, but octadecane mineralization was linear. The rates of mineralization at the end of the active phase of the biodegradation were lower than the rate of dissolution of palmitic acid but higher than the rate of dissolution of octadecane in the uninoculated medium. We suggest that spontaneous dissolution rates are only one of the factors that govern the rates of biodegradation.
Effects of microcosm salinity and organic substrate concentration on production of Vibrio cholerae enterotoxin
Authors: Tamplin M L , Colwell R R
Published: January 2020

The effects of aquatic processes on production of cholera toxin by Vibrio cholerae were studied with seawater microcosms. Several salinity and organic nutrient concentrations were employed. At 10 g of organic nutrient per liter of seawater, toxin production increased as the salinity was increased. At lower organic nutrient concentrations, toxin production was markedly enhanced when the salinity was 20 and 25%. Toxin concentration increased with salinity, independent of cell concentration and toxin stability. From the results obtained in this study, it is concluded that physical and chemical parameters of the aquatic environment affect not only the physiological state of V. cholerae, but also its potential pathogenicity.
Production of Deepoxy-Diacetoxyscirpenol in a Culture of
Fusarium graminearum
Authors: Chatterjee K. , Pawlosky R. J. , Mirocha C. J. , Zhu Tong-Xia
Published: January 2020

Deepoxy-diacetoxyscirpenol was isolated from a laboratory culture of
Fusarium graminearum
grown on a solid rice substrate. It was characterized as 3-hydroxy-4,15-diacetoxy-trichothec-9,12-diene by proton nuclear magnetic resonance and mass spectrometry. This is the first report of the occurrence of this metabolite in a fungus culture.
Enterotoxin synthesis by nonsporulating cultures of Clostridium perfringens
Authors: Goldner S B , Solberg M , Jones S , Post L S
Published: January 2020

Chemostat-cultured Clostridium perfringens ATCC 3624 and NCTC 10240, and a nonsporulating mutant strain, 8-5, produced enterotoxin in the absence of sporulation when cultured in a chemically defined medium at a 0.084-h-1 dilution rate at 37 degrees C. The enterotoxin was detected by serological and biological assays. Examination of the chemostat cultures by electron microscopy did not reveal sporulation at any stage. The culture maintained enterotoxigenicity throughout cultivation in a continuous system. The enterotoxin was detected in batch cultures of each strain cultivated in fluid thioglycolate medium and a chemically defined medium. No heat-resistant or light-refractile spores were detected in batch cultures during the exponential growth.
Cloning, Expression, and Purification of Glutamine Synthetase from
Clostridium acetobutylicum
Authors: Usdin Karen P. , Zappe Harold , Jones David T. , Woods David R.
Published: January 2020

A glutamine synthetase (GS) gene,
glnA
, from the gram-positive obligate anaerobe
Clostridium acetobutylicum
was cloned on recombinant plasmid pHZ200 and enabled
Escherichia coli glnA
deletion mutants to utilize (NH
4
)
2
SO
4
as a sole source of nitrogen. The cloned
C. acetobutylicum
gene was expressed from a regulatory region contained within the cloned DNA fragment.
glnA
expression was subject to nitrogen regulation in
E. coli
. This cloned
glnA
DNA did not enable an
E. coli glnA ntrB ntrC
deletion mutant to utilize arginine or low levels of glutamine as sole nitrogen sources, and failed to activate histidase activity in this strain which contained the
Klebsiella aerogenes hut
operon. The GS produced by pHZ200 was purified and had an apparent subunit molecular weight of approximately 59,000. There was no DNA or protein homology between the cloned
C. acetobutylicum glnA
gene and GS and the corresponding gene and GS from
E. coli
. The
C. acetobutylicum
GS was inhibited by Mg
2+
in the γ-glutamyl transferase assay, but there was no evidence that the GS was adenylylated.
Bacteria associated with granular activated carbon particles in drinking water
Authors: Camper A K , LeChevallier M W , Broadaway S C , McFeters G A
Published: January 2020

A sampling protocol was developed to examine particles released from granular activated carbon filter beds. A gauze filter/Swinnex procedure was used to collect carbon fines from 201 granular activated carbon-treated drinking water samples over 12 months. Application of a homogenization procedure (developed previously) indicated that 41.4% of the water samples had heterotrophic plate count bacteria attached to carbon particles. With the enumeration procedures described, heterotrophic plate count bacteria were recovered at an average rate of 8.6 times higher than by conventional analyses. Over 17% of the samples contained carbon particles colonized with coliform bacteria as enumerated with modified most-probable-number and membrane filter techniques. In some instances coliform recoveries were 122 to 1,194 times higher than by standard procedures. Nearly 28% of the coliforms attached to these particles in drinking water exhibited the fecal biotype. Scanning electron micrographs of carbon fines from treated drinking water showed microcolonies of bacteria on particle surfaces. These data indicate that bacteria attached to carbon fines may be an important mechanism by which microorganisms penetrate treatment barriers and enter potable water supplies.
Mechanism of inactivation of enteric viruses in fresh water
Authors: Ward R L , Knowlton D R , Winston P E
Published: January 2020

Fresh water obtained from nine sources was shown to cause inactivation of poliovirus. Further testing with four of these water samples showed that enteric viruses from different genera were consistently inactivated in these freshwater samples. Studies on the cause of inactivation were conducted with echovirus type 12 as the model virus. The results revealed that the virucidal agents in the waters tested could not be separated from microorganisms. Any treatment that removed or inactivated microorganisms caused loss of virucidal activity. Microbial growth in a sterilized creek water seeded with a small amount of stream water resulted in concomitant production of virucidal activity. When individual bacterial isolates obtained from a stream were grown in this sterilized creek water, most (22 of 27) produced a large amount of virucidal activity, although the amount varied from one isolate to the next. Active and inactive isolates were represented by both gram-positive and gram-negative organisms. Examination of echoviruses inactivated in stream water revealed that loss of infectivity first correlated with a slight decrease in the sedimentation coefficient of virus particles. The cause appeared to be cleavage of viral proteins, most notably, VP-4 and, to a lesser extent, VP-1. Viral RNA associated with particles was also cleaved but the rate was slower than loss of infectivity. These results suggest that proteolytic bacterial enzymes inactivate echovirus particles in fresh water by cleavage of viral proteins, thus exposing the viral RNA to nuclease digestion.
Use of geostatistics to predict virus decay rates for determination of septic tank setback distances
Authors: Yates M V , Yates S R , Warrick A W , Gerba C P
Published: January 2020

Water samples were collected from 71 public drinking-water supply wells in the Tucson, Ariz., basin. Virus decay rates in the water samples were determined with MS-2 coliphage as a model virus. The correlations between the virus decay rates and the sample locations were shown by fitting a spherical model to the experimental semivariogram. Kriging, a geostatistical technique, was used to calculate virus decay rates at unsampled locations by using the known values at nearby wells. Based on the regional characteristics of groundwater flow and the kriged estimates of virus decay rates, a contour map of the area was constructed. The map shows the variation in separation distances that would have to be maintained between wells and sources of contamination to afford similar degrees of protection from viral contamination of the drinking water in wells throughout the basin.
Novobiocin-brilliant green-glucose agar: new medium for isolation of salmonellae
Authors: Devenish J A , Ciebin B W , Brodsky M H
Published: January 2020

A new medium, called novobiocin-brilliant green-glucose (NBG) agar, was developed for the isolation of Salmonella spp. and evaluated against other conventionally used media including bismuth sulfite, xylose-lysine decarboxylase, brilliant green-sulfa, hektoen enteric, and salmonella-shigella agars. NBG had recovery rates comparable to the other enteric media tested with pure cultures as well as with naturally contaminated amphibian and reptile waters and fecal specimens. However, NBG, hektoen enteric, and salmonella-shigella agars failed to differentiate Salmonella typhi from a fecal specimen even after enrichment in selenite F. Although Citrobacter freundii could grow and resembled salmonellae on NBG, at no time was the recovery of Salmonella spp. colonies jeopardized by the presence of C. freundii in either seeded or naturally contaminated samples. Confirmation rates of typical colonies from NBG agar also compared favorably to the other media tested; however, bismuth sulfite, although selective, was found to have varied differential characteristics for Salmonella spp. As a result, many more colonies had to be picked, which caused bismuth sulfite agar to have the lowest confirmation rate of the media tested. The distinct advantage that NBG agar offers over the conventional method tested, including bismuth sulfite, is the consistent differential reaction of all Salmonella subgroups including biochemically atypical strains. The medium is inexpensive, easy to prepare, and can be stored for at least 2 weeks at 4 degrees C without loss of selective or differential properties.
Magnesium and Manganese Content of Halophilic Bacteria
Authors: Médicis Eveline De , Paquette Jean , Gauthier Jean-Jacques , Shapcott Dennis
Published: January 2020

Magnesium and manganese contents were measured by atomic absorption spectrophotometry in bacteria of several halophilic levels, in
Vibrio costicola
, a moderately halophilic eubacterium growing in 1 M NaCl,
Halobacterium volcanii
, a halophilic archaebacterium growing in 2.5 M NaCl,
Halobacterium cutirubrum
, an extremely halophilic archaebacterium growing in 4 M NaCl, and
Escherichia coli
, a nonhalophilic eubacterium growing in 0.17 M NaCl. Magnesium and manganese contents varied with the growth phase, being maximal at the early log phase. Magnesium and manganese molalities in cell water were shown to increase with the halophilic character of the logarithmically growing bacteria, from 30 mmol of Mg per kg of cell water and 0.37 mmol of Mn per kg of cell water for
E. coli
to 102 mmol of Mg per kg of cell water and 1.6 mmol of Mn per kg of cell water for
H. cutirubrum
. The intracellular concentrations of manganese were determined independently by a radioactive tracer technique in
V. costicola
and
H. volcanii
. The values obtained by
54
Mn loading represented about 70% of the values obtained by atomic absorption. The increase of magnesium and manganese contents associated with the halophilic character of the bacteria suggests that manganese and magnesium play a role in haloadaptation.
Preliminary Characterization of Bacteriophages Infecting the Thermophilic Actinomycete
Thermomonospora
Authors: Lawrence H. Marie , Merivuori Hannele , Sands Jeffrey A. , Pidcock Kenneth A.
Published: January 2020

Bacteriophages lysing strains of
Thermomonospora alba
and
T. fusca
were isolated, following specific enrichment, from vegetable composts. Four
Thermomonospora
phages were distinguished by plaque morphology and host range. Electron microscopy of phage particles, termperature inactivation profiles, and electrophoretic analyses of major virion proteins and genomic DNA were used in the comparison and initial characterization of these phages. The four phages studied possessed polyhedral heads and long tails; genomes were linear double-stranded DNA molecules, 35 to 45 kilobases in length, which probably contain cohesive ends. Transfection of
Thermomonospora
protoplasts with purified genomic DNA from one of the phages was demonstrated.
Measurement of Glucose Utilization by
Pseudomonas fluorescens
That Are Free-Living and That Are Attached to Surfaces
Authors: Fletcher Madilyn
Published: January 2020

The assimilation and respiration of glucose by attached and free-living
Pseudomonas fluorescens
were compared. The attachment surfaces were polyvinylidene fluoride, polyethylene, and glass. Specific uptake of [
14
C]glucose was determined after bacterial biomass was measured by (i) microscopic counts or (ii) prelabeling of cells by providing [
3
H]leucine as substrate, followed by dual-labeling scintillation counting. The glucose concentration was 1.4, 3.5, 5.5, 7.6, or 9.7 μM. Glucose assimilation by cells which became detached from the surfaces during incubation with glucose was also measured after the detached cells were collected by filtration. The composition of the substratum had no effect on the amount of glucose assimilated by attached cells. Glucose assimilation by attached cells exceeded that by free-living cells by a factor of between 2 and 5 or more, and respiration of glucose by surface-associated cells was greater than that by free-living bacteria. Glucose assimilation by detached cells was greater than that by attached bacteria. Measurements of biomass by microscopic counts gave more consistent results that those obtained with dual-labeling, but in general, results obtained by both methods were corroborative.
Detection of hepatitis A virus in seeded estuarine samples by hybridization with cDNA probes
Authors: Jiang X , Estes M K , Metcalf T G , Melnick J L
Published: January 2020

The development and trials of a nucleic acid hybridization test for the detection of hepatitis A virus (HAV) in estuarine samples within 48 h are described. Approximately 10(4) physical particles of HAV per dot could be detected. Test sensitivity was optimized by the consideration of hybridization stringency, 32P energy level, probe concentration, and nucleic acid binding to filters. Test specificity was shown by a lack of cross-hybridization with other enteroviruses and unrelated nucleic acids. Potential false-positive reactions between bacterial DNA in samples and residual vector DNA contamination of purified nucleotide sequences in probes were eliminated by DNase treatment of samples. Humic acid at concentrations of up to 100 mg/liter caused only insignificant decreases in test sensitivity. Interference with hybridization by organic components of virus-containing eluates was removed by proteinase K digestion followed by phenol extraction and ethanol precipitation. The test is suitable for detecting naturally occurring HAV in samples from polluted estuarine environments.
Elimination of overgrowth in delayed-incubation membrane filter test for total coliforms by m-ST holding medium
Authors: Chen M , Hickey P J
Published: January 2020

Two holding media were compared for their effects on total coliform recovery by the delayed-incubation membrane filter procedure. LES-MF holding medium contains tryptone, m-Endo broth, dipotassium hydrogen phosphate, sodium benzoate, sulfanilamide, para-aminobenzoic acid, and cycloheximide (pH 7.0). m-ST holding medium contains ethanol, sodium monophosphate, dipotassium hydrogen phosphate, sulfanilamide, and Tris (pH 8.6). In tests with natural water and wastewater samples from various sources, recovery with LES-MF and m-ST were similar after a 1-day holding period. With LES-MF, however, after a 2- or 3-day holding period, coliform bacteria frequently were partially or totally overgrown by noncoliforms, causing significant reductions in coliform counts. No significant overgrowth was observed with m-ST. We propose that m-ST be used for all holding periods longer than 1 day.
Inhibition of Ammonium Oxidation by Nitrapyrin in Soil and Liquid Culture
Authors: Powell Steven J. , Prosser James I.
Published: January 2020

Inhibition of growth of axenic cultures of
Nitrosomonas europaea
by nitrapyrin was investigated in liquid culture and in soil. In liquid culture, exponentially growing cells were more sensitive than stationary-phase cells, possibly due to a requirement for uptake of nitrapyrin, metabolism of nitrapyrin, or both before inhibition. Differences in sensitivity were observed between the parent strain and two strains,
sp1
and
sp2
, that were selected through repeated subculturing. These differences were reflected in the length of the lag period induced by nitrapyrin and in the specific growth rate and were due to different bactericidal and bacteriostatic effects. Soil provided significant protection from inhibition, with concentrations of nitrapyrin approximately one order of magnitude greater than those required for equivalent inhibition in liquid culture. The data show that strain differences alone do not explain differences in sensitivity between nitrification in soil and in liquid culture and suggest that the inhibitor may be more effective against actively nitrifying soils.
Gram-Negative Versus Gram-Positive (Actinomycete) Nonobligate Bacterial Predators of Bacteria in Soil
Authors: Zeph Lawrence R. , Casida L. E.
Published: January 2020

The existence of nonobligate bacterial predators of bacteria in soil has been previously reported. Several additional predators were isolated from soil and tested for predation in situ in soil by use of the indirect bacteriophage analysis technique. The trials were conducted with nutritionally poor and nutritionally enriched soil. Certain of the predators that were gram negative were found to attack a range of both gram-positive and gram-negative host cell species, including at least some of the other predator bacteria, both gram positive and gram negative. The attack occurred in both the nutritionally poor and rich soils, but in some instances it was somewhat depressed in the rich soil. This may be due to the nonobligate nature of the predation. The gram-positive predators attacked a relatively narrow range of prey species, and the attack occurred only in the nutritionally rich soil. In addition, the gram-positive predators were subject to attack by certain of the gram-negative predators. These gram-negative predators therefore appeared to play a dominant role in the control of bacterial numbers in soil.
Factors affecting sensitivity of Staphylococcus aureus 196E to polyphosphates
Authors: Jen C M , Shelef L A
Published: January 2020

The effect of polyphosphates (eight compounds) on growth of Staphylococcus aureus 196E in brain heart infusion broth was studied. The organism was sensitive (in decreasing order) to chain polyphosphates with 21, 3, 13, and 15 PO4 groups, and bactericidal effects were observed with 0.5% of these compounds. No inhibition was effected by PPi or a metaphosphate. The inhibitory effects were pH dependent, and bacterial sensitivity was highest at pH greater than 7.4. Initial populations affected the number of survivors. No growth was observed after 24 h at 35 degrees C when the initial cell population was less than 10(4) CFU/ml, and a 100- to 1,000-fold decline in cell numbers occurred when initial populations were higher than 10(4) CFU/ml. Sodium tripolyphosphate produced less inhibition after heat sterilization (15 min, 121 degrees C) than after filter sterilization, whereas sodium hexametaphosphate (n = 21) retained most of its antimicrobial activity after heat sterilization. Supplementation of broth with Mg2+ was effective in overcoming inhibition by 0.5% sodium tripolyphosphate, and an addition of 0.25 to 1.0 mM cation restored most of the growth. Inhibition was partially eliminated by Ca2+ and Fe2+, but not by Zn2+ or Mn2+.
Rapid Colored-Nodule Assay for Assessing Root Exudate-Enhanced Competitiveness of
Bradyrhizobium japonicum
Authors: Ayanaba Abateni , Haugland Richard A. , Sadowsky Michael J. , Upchurch Robert G. , Weiland Karen D. , Zablotowicz Robert M.
Published: January 2020

The effects of root exudate (RE) treatment on nodule occupancy by
Bradyrhizobium japonicum
were investigated by a rapid colored-nodule assay, which is based on the observation that
B. japonicum
L-110 and its antibiotically marked derivatives form dark-red nodules on certain soybean (
Glycine max
) cultivars, whereas other strains form beige nodules. The efficacy of the assay was confirmed by direct immunofluorescence and by antibiotic platings of nodule bacteria. Both logarithmic- and stationary-phase cultures of the reference strain, L-110Nal, were used in paired-competition studies with RE-treated or untreated cells of seven challenge strains. On the basis of field and greenhouse competition studies, these strains were placed into three competitiveness groups: high (AN-11, AN-16aStrRif, and AN-6), intermediate (AN-3 and 122SR), and low (I-110ARS and AN-18). Seedlings of
G. max
cv. Centennial were inoculated with two ratios of challenge to reference strain, 1:1 and 1:9, and nodule occupancy was determined after the V4 to V5 stage of ontogeny. Two of the strains showed increased occupancy in response to RE treatment at the 1:1 inoculation ratio. Logarithmic- and stationary-phase cultures of AN-6 showed increased occupancy, from 22 to 38% (
P
< 0.10) and from 23 59 39% (
P
< 0.05), respectively. While the maximum increase for stationary-phase cultures of AN-16aStrRif was from 34 to 47% (
P
< 0.05), logarithmic-phase cultures failed to respond to RE treatment. The results of these studies indicate that RE treatment increases the nodule occupancy of some, but not all,
B. japonicum
strains and that the colored-nodule assay could be rapidly and reliably used to determine the competitive ability of
B. japonicum.
Automation of microbial enumeration: development of a disposable hydrophobic grid-membrane filter unit
Authors: Tsuji K , Bussey D M
Published: January 2020

A disposable filter unit containing a hydrophobic grid-membrane filter (HGMF) was developed. The unit is liquid tight to serve as a specimen transport container and, by removal of the funnel extender (175- or 300-ml capacity), the unit becomes less than the height of two stacked petri plates to save space during in situ incubation. The polyethylene mesh which supports the HGMF facilitates rinse removal of any substance(s) that would interfere with microbial growth. The correlations between a pour plate, a conventional square HGMF, and a disposable filter unit on microbial enumeration were examined. Characteristics (e.g., clumping, spreading, etc.) of some microorganisms limit the linear counting range to less than 1,000 CFU per filter.
Method for Assessing Heterogeneity in Turnover Rates within Microbial Communities
Authors: Laws Edward A. , Jones David , Karl David M.
Published: January 2020

A method is presented for determining both the average turnover rate and the standard deviation of the average turnover rate of the adenine nucleotide (AN) pool within a population of microorganisms. The method requires the calculation of the initial slope and curvature of a plot of AN specific activity versus time following the introduction of [
3
H]adenine. An analysis of noise-corrupted data indicated that the method is capable of detecting a lack of uniformity in the turnover rate when the coefficient of variation of the turnover rate exceeds 39%. An analysis of field data revealed a significant lack of uniformity in the turnover rates of microbial communities in a marine sediment sample and freshwater pond but no significant nonuniformity in the turnover rates of microbial communities in a seawater sample and in a second freshwater pond. Although the method has been applied only to the analysis of AN turnover rates, it is applicable to any intracellular pool for which a suitable radioactive precursor exists.
Bacteroides pectinophilus sp. nov. and Bacteroides galacturonicus sp. nov.: two pectinolytic bacteria from the human intestinal tract
Authors: Jensen N S , Canale-Parola E
Published: January 2020

Studies on the physiological characteristics of two obligately anaerobic, rod-shaped bacteria from the human intestinal tract indicated that the organisms represented two previously undescribed species of Bacteroides, for which we propose the names Bacteroides pectinophilus (type strain, N3) and Bacteroides galacturonicus (type strain, N6). Both strains were pectinophilic; that is, they utilized as fermentable substrates for growth only pectin and a few related compounds. The two species differed significantly from each other in guanine plus cytosine content of the DNA, in substrate utilization patterns, and in other phenotypic characteristics. Both species deesterified pectin by means of an extracellular pectinesterase (EC 3.1.1.11) activity. Polygalacturonate (the main component of deesterified pectin) was depolymerized extracellularly with formation of unsaturated products by both species. The depolymerizing activity required Ca2+, functioned at a higher rate when polygalacturonate was the substrate as compared with pectin, and had an alkaline pH optimum. These data, as well as viscosity decrease studies and identification of products formed from polygalacturonate, indicated that the extracellular depolymerizing activity of either species was characteristic of an exopectate (exopolygalacturonate) lyase. The exopectate lyase activity had an unusual action pattern that resulted in terminal cleavage of unsaturated trigalacturonic acid units from polygalacturonate. An unsaturated trimer was the major product that accumulated in cell-free reaction mixtures, where it was not cleaved further. Growing cells of both Bacteroides species released the exopectate lyase into the external environment by processes that did not involve cell lysis to any significant extent.(ABSTRACT TRUNCATED AT 250 WORDS)
Synthesis of [
14
C]Cellobiose with
Clostridium thermocellum
Cellobiose Phosphorylase
Authors: Ng Thomas K. , Zeikus J. G.
Published: January 2020

Cellobiose labeled either at the reducing end (4-
O
-β-
d
-glucopyranosyl-
d
-[U-
14
C]glucopyranose) or at the nonreducing end (4-
O
-β-
d
-[U-
14
C]glucopyranosyl-
d
-glucopyranose) was synthesized with
Clostridium thermocellum
cellobiose phosphorylase at greater than 98% purity. The radioactive cellobioses were identical to authentic cellobiose in melting point, optical rotation, isotopic dilution, and chromatographic properties.
Fractionation and Estimation of Particle-Attached and Unattached
Bradyrhizobium japonicum
Strains in Soils
Authors: Ozawa Takashi , Yamaguchi Masurou
Published: January 2020

Rhizobial cells attached or unattached to soil particles were estimated. Nonsterile soils into which antibiotic-resistant mutants of
Bradyrhizobium japonicum
had been introduced were fractionated by a centrifugation technique into two fractions: A, which contained mainly rhizobial cells attached to soil particles, and F, which contained mainly rhizobial cells unattached to them. Rhizobial counts decreased in both fractions during incubation of the soil at 30°C, with a concomitant decrease in the proportion of the count of fraction F to that of fraction A. Sonication of fraction A of the soil incubated for more than 3 weeks caused an increase in the rhizobial count. The ratio of the count of fraction A estimated by the plant infection method to that estimated by the dilution plate method increased after 5 days of soil incubation. More than 90% of the indigenous rhizobia in an agricultural field existed in fraction A. These results suggest that the majority of rhizobial cells are attached to soil particles.
Isolation and Characterization of Linear DNA Elements from the Mitochondria of
Gaeumannomyces graminis
Authors: Honeyman Allen L. , Currier Thomas C.
Published: January 2020

Different
Gaeumannomyces graminis
strains of diverse geographic origin contain one or two small DNAs ranging in size from 7.2 to 10 kilobases. These DNAs exhibit different degrees of homology with each other. We have characterized these low-molecular-weight DNAs from one strain, Ha-01. These small DNAs, E1 and E2, are mitochondrial in origin and were isolated as linear molecules which exhibited an intrinsic difference in density from the high-molecular-weight DNA.
Defined medium for Moraxella bovis
Authors: Juni E , Heym G A
Published: January 2020

A defined medium (medium MB) for Moraxella bovis was formulated. Nineteen strains grew well on medium MB. One strain was auxotrophic for asparagine, and another was auxotrophic for methionine. Strains of M. equi and M. lacunata also grew on medium MB. All strains had an absolute requirement for thiamine and were stimulated by or actually required the other growth factors in the medium.
Evaluation of the diagnostic application of an enzyme immunoassay for Clostridium perfringens type A enterotoxin
Authors: Jackson S G , Yip-Chuck D A , Brodsky M H
Published: January 2020

The diagnostic application of an enzyme immunoassay for Clostridium perfringens type A enterotoxin was evaluated. Test results from 100 individuals associated with C. perfringens gastroenteritis outbreaks and 111 control individuals were included. The assay sensitivity was 93.7%, and the assay specificity was 98.7%.