bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic recombination in Micromonospora rosaria by protoplast fusion
Authors: Ryu D D , Kim K S , Cho N Y , Pai H S
Published: January 2020

Auxotrophic strains of Micromonospora rosaria were isolated by N-methyl-N'-nitro-N'-nitrosoguanidine mutagenesis and used in intraspecific recombination by protoplast fusion. High-frequency fusion of protoplasts of M. rosaria strains was induced by polyethylene glycol (molecular weight, 1,000) (PEG 1,000). The optimum concentration of PEG 1,000 for fusion of M. rosaria was 50% (wt/vol). PEG 4,000 was slightly better than PEG 1,000 at concentrations lower than 50% (wt/vol). The recombinant frequency did not increase after treatment with PEG 1,000 (50% [wt/vol]) for longer than 20 min. Under these conditions, fusion with many auxotrophic strains of M. rosaria resulted in a high frequency of formation of true recombinants (sometimes more than 10%). Additionally, when ros (rosamicin nonproducing) strains were crossed by protoplast fusion; about 5% of the resultant prototrophic recombinants were shown to have the ros+ (rosamicin producing) characteristic restored. Rosamicin production by M. rosaria colonies was clearly distinguished by the broth overlay method. The results of fusion experiments between ros and ros+ strains indicated that either the chromosomal mutation or pleiotrophic effect of some auxotrophic markers is involved.
Seasonal variation in survival of Escherichia coli exposed in situ in membrane diffusion chambers containing filtered and nonfiltered estuarine water
Authors: Anderson I C , Rhodes M W , Kator H I
Published: January 2020

Human fecal Escherichia coli isolates were exposed over a seasonal cycle to estuarine water in diffusion chambers filled with double-filtered (0.45 and 0.2 microns) and nonfiltered water. Laboratory manipulations of E. coli cultures before estuarine exposure were reduced to minimize sublethal stress, and nonselective or resuscitative enumeration techniques were employed to maximize recovery of stressed cells. E. coli was capable of extended survival during in situ exposure to estuarine water, provided eucaryotes were excluded from diffusion chambers. Survival was directly related to temperature in absence of the eucaryote component of the natural microbiota. Although it was not possible to prevent eventual bacterial contamination in double-filtered water, there was no direct evidence that such contamination affected E. coli survival. Conversely, E. coli disappearance was most pronounced at warmer temperatures in the presence of the natural microbiota, and decline coincided with increasing eucaryote densities. In contrast, the decline of E. coli during winter was similar in both filtered and nonfiltered seawater.
Anaerobic Oxalate Degradation: Widespread Natural Occurrence in Aquatic Sediments
Authors: Smith Richard L. , Oremland Ronald S.
Published: January 2020

Significant concentrations of oxalate (dissolved plus particulate) were present in sediments taken from a diversity of aquatic environments, ranging from 0.1 to 0.7 mmol/liter of sediment. These included pelagic and littoral sediments from two freshwater lakes (Searsville Lake, Calif., and Lake Tahoe, Calif.), a hypersaline, meromictic, alkaline lake (Big Soda Lake, Nev.), and a South San Francisco Bay mud flat and salt marsh. The oxalate concentration of several plant species which are potential detrital inputs to these aquatic sediments ranged from 0.1 to 5.0% (wt/wt). In experiments with litter bags, the oxalate content of
Myriophyllum
sp. samples buried in freshwater littoral sediments decreased to 7% of the original value in 175 days. This suggests that plant detritus is a potential source of the oxalate within these sediments. [
14
C]oxalic acid was anaerobically degraded to
14
CO
2
in all sediment types tested, with higher rates evident in littoral sediments than in the pelagic sediments of the lakes studied. The turnover time of the added [
14
C]oxalate was less than 1 day in Searsville Lake littoral sediments. The total sediment oxalate concentration did not vary significantly between littoral and pelagic sediments and therefore did not appear to be controlling the rate of oxalate degradation. However, depth profiles of [
14
C]oxalate mineralization and dissolved oxalate concentration were closely correlated in freshwater littoral sediments; both were greatest in the surface sediments (0 to 5 cm) and decreased with depth. The dissolved oxalate concentration (9.1 μmol/liter of sediment) was only 3% of the total extractable oxalate (277 μmol/liter of sediment) at the sediment surface. These results suggest that anaerobic oxalate degradation is a widespread phenomenon in aquatic sediments and may be limited by the dissolved oxalate concentration within these sediments.
Iron-Chelating Compounds Produced by Soil Pseudomonads: Correlation with Fungal Growth Inhibition
Authors: Vandenbergh Peter A. , Gonzalez Carlos F. , Wright Ann M. , Kunka Blair S.
Published: January 2020

Strains of
Pseudomonas putida, Pseudomonas
sp., and
Pseudomonas aeruginosa
were examined for their ability to grow in the presence of the iron chelator, ethylenediamine-di-(
o
-hydroxyphenylacetic acid). In vitro fungal inhibition assays showed that the isolates varied in their ability to inhibit the growth of representative fungal plant pathogens. Fungal inhibition in vitro was superior to that of previously reported
Pseudomonas
sp. Studies with
Fusarium oxysporum
forma sp.
lycopersici
and a susceptible tomato cultivar demonstrated that
Pseudomonas putida
PPU3.1 was able to significantly reduce wilt disease.
Improved Colorimetric Determination of Cell Wall Chitin in Wood Decay Fungi
Authors: Chen George C. , Johnson Bruce R.
Published: January 2020

The Svennerholm modification of the Elson-Morgan method for glucosamine analysis was evaluated for its applicability to the rapid determination of chitin in wood decay fungi. The evaluation included extent of chromogen interference, sensitivity, color stability, and hydrolysis conditions for maximum release of glucosamine from fungal cell walls. With our further modification, the Svennerholm method was shown to be suitable for rapid quantitative determination of fungal chitin without chromatographic separation of hydrolysate chromogens.
Reduction of interfering cytotoxicity associated with wastewater sludge concentrates assayed for indigenous enteric viruses
Authors: Hurst C J , Goyke T
Published: January 2020

Washing, freon extraction, and cationic polyelectrolyte precipitation were compared for their ability to reduce cytotoxicity associated with virus concentrates derived from beef extract eluates of wastewater sludges. Eluates concentrated by hydroextraction were usually much more toxic than those concentrated by organic flocculation. This difference may be due entirely to nondialyzable material naturally present in the beef extract which did not precipitate during flocculation at pH 3.5. Washing inoculated cell monolayers with saline containing calf serum before the addition of agar overlay media was most effective in reducing cytotoxicity, although it resulted in a greater virus loss, as compared with freon extraction and cationic polyelectrolyte precipitation.
Multiple antibiotic resistance indexing of Escherichia coli to identify high-risk sources of fecal contamination of foods
Authors: Krumperman P H
Published: January 2020

Escherichia coli isolates taken from environments considered to have low and high enteric disease potential for humans were screened against 12 antibiotics to determine the prevalence of multiple antibiotic resistance among the isolates of these environments. It was determined that multiple-antibiotic-resistant E. coli organisms exist in large numbers within the major reservoirs of enteric diseases for humans while existing in comparatively low numbers elsewhere. These differences provide a method for distinguishing high-risk contamination of foods by indexing the frequency with which multiple-antibiotic-resistant E. coli organisms occur among isolates taken from a sample.
Degradation of Phenolic Compounds and Ring Cleavage of Catechol by
Phanerochaete chrysosporium
Authors: Leatham Gary F. , Crawford R. L. , Kirk T. Kent
Published: January 2020

POL-88, a mutant of the white-rot fungus
Phanerochaete chrysosporium
, was selected for diminished phenol-oxidizing enzyme activity. A wide variety of phenolic compounds were degraded by ligninolytic cultures of this mutant. With several
o
-diphenolic substrates, degradation intermediates were produced that had UV spectra consistent with muconic acids. Extensive spectrophotometric and polarographic assays failed to detect classical ring-cleaving dioxygenases in cell homogenates or in extracts from ligninolytic cultures. Even so, a sensitive carrier-trapping assay showed that intact cultures degraded [
U
-
14
C]catechol to [
14
C]muconic acid, establishing the presence of a system capable of 1,2-intradiol fission. Significant accumulation of [
14
C]muconic acid into carrier occurred only when evolution of
14
CO
2
from [
14
C]catechol was inhibited by treating cultures with excess nutrient nitrogen (e.g.,
l
-glutamic acid) or with cycloheximide.
l
-Glutamic acid is known from past work to repress the ligninolytic system in
P. chrysosporium
and to mimic the effect of cycloheximide. The results here indicate, therefore, that the enzyme system responsible for degrading ring-cleavage products to CO
2
turns over faster than does the system responsible for ring cleavage.
Removal of bacteria from water by adhesion to cross-linked poly(vinylpyridinium halide)
Authors: Kawabata N , Hayashi T , Matsumoto T
Published: January 2020

Cross-linked poly(vinylpyridinium halide) was found to have a novel and remarkable ability to remove bacteria from water. For example, when 10 g (wet weight) of cross-linked poly(N-benzyl-4-vinylpyridinium bromide) was contacted with 20 ml of suspensions of Escherichia coli (9.7 X 10(4) to 9.7 X 10(7)/ml), Salmonella typhimurium (8.0 X 10(6) to 1.1 X 10(7)/ml), Streptococcus faecalis (5.0 X 10(7)/ml), Staphylococcus aureus (8.1 X 10(7)/ml), and Pseudomonas aeruginosa (3.2 X 10(5)/ml) under stirring in sterilized physiological saline at 37 degrees C, 99% of the viable cells of these bacteria were removed in 2 to 6 h. When suspensions of these bacteria (10(5) to 10(8) cells per ml) were passed through a column (20 mm by 100 cm) of cross-linked poly(N-benzyl-4-vinylpyridinium bromide) at 37 degrees C with a flow rate of 0.8 to 1.4 bed volumes per h, 97 to 100% of the viable cells were eliminated from the suspensions during the treatment. Mechanistic studies demonstrated that cross-linked poly(vinylpyridinium halide) irreversibly captured these bacteria alive during the treatment. That is, total organic carbon was removed during the treatment, and the bacteria which adhered to the resin proliferated on the bacterial medium. The adhesion capacity was estimated to be 10(10) cells per g (dry weight). Total organic carbon was also removed even when the bacteria were killed by heat treatment before the column studies.
Growth and Plating Efficiency of Methanococci on Agar Media
Authors: Jones W. Jack , Whitman William B. , Fields Robert D. , Wolfe Ralph S.
Published: January 2020

Plating techniques for cultivation of methanogenic bacteria have been optimized for two members of the genus
Methanococcus. Methanococcus maripaludis
and
Methanococcus voltae
were cultivated on aerobically and anaerobically prepared agar media. Maintenance of O
2
levels below 5 μl/liter within an anaerobic glove box was necessary during plating and incubation for 90% recovery of plated cells. Under an atmosphere of H
2
, CO
2
, and H
2
S (79:20:1), 2 to 3 days of incubation at 37°C were sufficient for the formation of visible colonies. The viability of plated cells was significantly affected by the growth phase of the culture, H
2
S concentration, and the volume of medium per plate. In addition, colony size of methanococci was affected by agar type, as well as by the concentrations of agar, H
2
S, and bicarbonate.
Influence of sewage treatment and urbanization on selection of multiple resistance in fecal coliform populations
Authors: Bell J B , Elliott G E , Smith D W
Published: January 2020

The fecal coliform populations found in the raw sewages and final sewage effluents of mechanical treatment plants, a long-term retention lagoon, shorter-term retention lagoons, a remote northern Canada river, and a heavily urbanized prairie river were examined for antibiotic resistance and the possession of R factors. It was determined that there was a decrease in the percentage of multiresistant fecal coliform populations in the mechanical sewage treatment plants and shorter-term retention lagoons; however, there was an increase in populations from the long-term retention lagoon. The percentage of the populations possessing transmissible R factors was constant in the mechanical treatment and shorter-term retention facilities; however, the ability to transmit was lost in 50% of the infective population of the long-term retention facility. A striking contrast was found between the populations of the remote northern Slave River and those of the urbanized Red River. Of the fecal coliforms in the Slave River, 7.1% were multiresistant, and only 0.79% possessed transmissible R factors. The Red River fecal coliform populations were 52.9% multiresistant, and 18.77% of the total population possessed transmissible R factors. The influence of urbanization and the type of sewage treatment have been shown to affect the selection and survival of multiresistant fecal coliforms and R+ fecal coliforms. Determination of other factors influencing the development and the survival of these populations is needed for rational wastewater management and water quality consideration.
Psychrotrophic Brocothrix thermosphacta bacteriophages isolated from beef
Authors: Greer G G
Published: January 2020

A total of 15 wild-type Brocothrix thermosphacta strains isolated from beef and the type strain, B. thermosphacta ATCC 11509, were used as hosts for the isolation of bacteriophages under psychrotrophic conditions (7 degrees C). A total of 21 virulent, psychrotrophic phages were successfully isolated and purified from aqueous extracts of spoiled rib steaks. Phage plaque size and plating efficiency significantly increased as incubation temperature was reduced from 25 to 1 degree C. Electron microscopy of two homologous B. thermosphacta phages showed the virions to consist of hexagonal heads and tails, with terminal appendages clearly visible on one of the phages. On the basis of culture and biochemical data, the wild-type B. thermosphacta strains had characteristics identical to those of strain ATCC 11509. However, specific differences in the pattern of susceptibilities to the phages revealed the presence of 14 distinct phage lysotypes. Phage typing may provide a rapid and sensitive means of differentiating B. thermosphacta strains.
Effect of pH on conjugal transfer at low temperatures
Authors: Singleton P , Anson A E
Published: January 2020

The inhibitory effects of nonoptimal temperature and nonoptimal pH on F-type conjugal transfer were found to be synergistic. This finding is briefly discussed in an environmental context.
Amplification of the aroA gene from Escherichia coli results in tolerance to the herbicide glyphosate
Authors: Rogers S G , Brand L A , Holder S B , Sharps E S , Brackin M J
Published: January 2020

The predominant cellular target of the herbicide glyphosate is thought to be the enzyme 5-enolpyruvylshikimate-3-phosphoric acid synthase (EPSP synthase). As a means of biologically testing this finding, we cloned a segment of DNA from Escherichia coli that encodes this enzyme. Clones carrying the gene for EPSP synthase were identified by genetic complementation. Cells that contain a multicopy plasmid carrying the EPSP synthase gene overproduce the enzyme 5- to 17-fold and exhibit at least an 8-fold increased tolerance to glyphosate. These experiments provide direct biological evidence that EPSP synthase is a major site of glyphosate action in E. coli and that, in an amplified form, it can serve as a selectable glyphosate resistance marker.
Inhibitory Effect of Solar Radiation on Amino Acid Uptake in Chesapeake Bay Bacteria
Authors: Bailey Carmela A. , Neihof Rex A. , Tabor Paul S.
Published: January 2020

The effect of solar radiation on a natural bacterial population from the Chesapeake Bay was evaluated from measured changes in numbers of organisms engaged in amino acid uptake. From July through May, freshly collected water samples were exposed in quartz containers to 3.5 h of total sunlight both with and without UV-absorbing filters. Water samples were subsequently incubated with tritiated amino acids, and the uptake-active bacteria were assayed by microauto-radiography-epifluorescence microscopy. The survival index, defined as the fraction of the uptake-active population that remained active after the exposure to sunlight, ranged from 0.93 to 0.20. Decreased survival was correlated with increased solar intensity. The inhibition of amino acid uptake was attributed not only to the UV-B component of the solar spectrum (280 to 320 nm), but also to longer UV and visible wavelengths.
Characterization of Gypsy Moth (
Lymantria dispar
) Nuclear Polyhedrosis Virus
Authors: Stiles Brad , Burand John P. , Meda Marta , Wood H. A.
Published: January 2020

Characterization of the proteins and nucleic acid of the gypsy moth nuclear polyhedrosis virus isolated in Ithaca, N.Y. (LdNPV-IT) is presented. A total of 29 viral structural proteins were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis when the virus was isolated in the absence of alkaline protease activity. Fourteen surface envelope viral proteins were identified by lactoperoxidase iodination. Eleven proteins were associated with nucleocapsids prepared by Nonidet P-40 detergent treatment. Distinct alterations of viral proteins were documented when virions were purified in the presence of occlusion body-associated alkaline protease(s). Restriction enzyme digests of viral DNA indicated that this isolate was composed of a large number of genetic variants. On the basis of the major molar fragments resulting from
Eco
RI,
Bam
HI,
Bgl
II, and
Hin
dIII digests, the molecular weight of the LdNPV genome was approximately 88 � 10
6
.
Toxicity of Bacillus thuringiensis subsp. israelensis to adult Aedes aegypti mosquitoes
Authors: Klowden M J , Held G A , Bulla L A
Published: January 2020

Adult female Aedes aegypti mosquitoes were killed by the parasporal crystals of Bacillus thuringiensis subsp. israelensis (ONR-60A) when the crystals were introduced into the insect midgut as an enema. The 50% lethal dose for intact parasporal crystals was 0.21 microgram/mg of mosquito (wet weight), and for solubilized crystals the 50% lethal dose was 0.04 microgram/mg. These values were compared with 50% lethal concentrations in a free-feeding larval mosquito bioassay of 0.018 and 1.28 microgram/ml for intact and solubilized crystals, respectively. Preparations from B. thuringiensis subsp. kurstaki were ineffective against both adult and larval mosquitoes. An adult mosquito bioassay is suggested as a direct means of screening potential mosquito control agents.
Improved Microfouling Assay Employing a DNA-Specific Fluorochrome and Polystyrene as Substratum
Authors: Paul John H. , Loeb George I.
Published: January 2020

With a direct count assay, 10 fouling bacterial isolates have been characterized for their ability to adhere to glass cover slips and polystyrene dishes. Although most adhered in greater numbers to polystyrene, the preference was statistically significant for only seven isolates at the 95% confidence level, due in part to the greater variability in cell attachment to glass (coefficient of variation, 32.3% for glass compared with 10.0% for polystyrene). Employing polystyrene dishes, a novel microfouling assay was developed, based on the extraction and fluorometric determination of DNA. The assay was rapid, enabled the detection of as little as 0.15 μg of DNA per dish (∼5,000 cells per mm
2
), and showed good agreement with the direct count assay. The DNA method resulted in less variability among three replicates (average coefficient of variation, 7.06%) and allowed for estimation of bacterial density over a larger surface area per sample (1.89 � 10
3
mm
2
) than was feasible with epifluorescence microscopy (0.06 to 0.1 mm
2
).
Investigation of the survival characteristics of Rhodococcus coprophilus and certain fecal indicator bacteria
Authors: Oragui J I , Mara D D
Published: January 2020

Rhodococcus coprophilus and Clostridium perfringens survived in fresh water samples held at 5, 20, and 30 degrees C for over 17 weeks, whereas Escherichia coli and fecal streptococci disappeared after 5 weeks at all three temperatures. R. coprophilus survived for more than 8 months in sterilized sewage and deionized water at all three temperatures, whereas in normal sewage held at 20 degrees C, the survival time was 12 to 26 weeks. In samples held at 30 degrees C, survival times were shorter, probably because of interbacterial competition or protozoal predation. The results indicate that R. coprophilus may be a useful indicator of the presence of remote fecal pollution of farm animal origin, but not of recent pollution, when enumerated alone in polluted waters or wastewaters.
Effect of Methyl Substitution on Microbial Degradation of Linear Styrene Dimers by Two Soil Bacteria
Authors: Higashimura Toshinobu , Sawamoto Mitsuo , Hiza Tae , Karaiwa Masato , Tsuchii Akio , Suzuki Tomoo
Published: January 2020

The microbial degradation of 10 linear unsaturated dimers (I to IV) prepared from styrene and
o
-,
m
-, or
p
-methylstyrene was investigated with two soil bacteria,
Alcaligenes
sp. strain 559 and
Pseudomonas
sp. strain 419. The two strains decomposed styrene dimer I and all styrene-methylstyrene codimers II and III, but methylstyrene homodimers IV remained intact. The degradation rates of codimers II and III of
o
- and
m
-methylstyrenes were found to depend on both their structure and the strain used; i.e.,
Alcaligenes
sp. strain 559 decomposed III faster than II, whereas the reverse order (II > III) was obtained with
Pseudomonas
sp. strain 419. In biodegradation by the former strain, the codimers were degraded faster in the presence of styrene dimer I than in its absence, but no such effect of dimer I was observed with the latter.
Characterization of Two Extracellular Polysaccharides from Marine Bacteria
Authors: Boyle C. David , Reade Austin E.
Published: January 2020

Two bacterial isolates from the intertidal zone produced significant quantities of extracellular polysaccharide with interesting properties. One polysaccharide was named PS 3a24; the other was named PS 3a35. The relative proportion of sugars in PS 3a35 was 51.6% glucose, 39.0% galactose, 3.1% mannose, and 6.3% rhamnose, with a trace of an unidentified sugar. PS 3a24 was composed of 40.2% glucose, 57.2% galactose, and 2.6% mannose. PS 3a35 contained 6% pyruvate, whereas PS 3a24 contained no pyruvate. Both exhibited high specific viscosity, pseudoplasticity, and stability over a wide range of pH in the presence of a variety of salts. The viscosity of PS 3a35 was relatively insensitive to increasing temperature, whereas that of PS 3a24 showed an irreversible drop on heating.
Production of aflatoxin by an Aspergillus flavus isolate cultured under a limited oxygen supply
Authors: Clevstr�m G , Ljunggren H , Tegelstr�m S , Tideman K
Published: January 2020

In a previous experiment on the preservation of hay of high moisture content with formic acid, among other agents, aflatoxin was formed in the hay, and aflatoxin-forming strains of Aspergillus flavus were isolated from this hay after incubation in air as well as in an anaerobic jar. One isolate from the anaerobic jar was cultivated in a chemostat (Bioflo model C 30; New Brunswick Scientific Co.) in a defined medium with added B vitamins, yeast extract, or formic acid, with or without gas flow (air or nitrogen). In all cases where spore germination occurred, aflatoxin was formed in the cultures with gas flow, and small quantities of aflatoxins B1 and B2 occurred even in an atmosphere of nitrogen. Addition of B vitamins and supply of traces of air gave an approximately 15-fold increase in the amount of aflatoxin in 2 days. Carbon dioxide enrichment hindered aflatoxin formation on the defined medium even in the presence of B vitamins, but when formic acid was added, small quantities (5 to 15 micrograms/liter) were formed, and this low level remained constant until the gas flow was started.
Broth medium for enrichment of Vibrio fluvialis from the environment
Authors: Nishibuchi M , Roberts N C , Bradford H B , Seidler R J
Published: January 2020

A medium was designed for the enrichment and enumeration of Vibrio fluvialis from environmental samples. The medium contains 1% peptone plus 4% sodium chloride and 5 micrograms of novobiocin per ml, pH 8.5. This V. fluvialis enrichment medium (FEM) was tested, in comparison with alkaline peptone (AP), in field samplings. A total of 177 samples (estuarine waters and sediment, sewage, and crabs) collected over a 14-month period were examined with FEM and with AP broth. Results showed that FEM was more effective than AP in detecting V. fluvialis, particularly from water and sewage samples with low salinities (less than 6%). The best recovery of V. fluvialis occurred when both enrichment media were used simultaneously.
Fungus invasion of legs of the tanner crab, Chionoecetes bairdi
Authors: Hoskin G P
Published: January 2020

Histological examination of tissues from the legs of tanner crabs, Chionoecetes bairdi, infected with black mat fungus, Trichomaris invadens, showed that hyphae penetrated the cuticle of the crab, extensively invaded the epidermis, and extended into the muscle tissue.
Survival of enteric viruses adsorbed on electropositive filters
Authors: Keswick B H
Published: January 2020

Three viruses (poliovirus type 1, rotavirus SA-11, and bacteriophage f2) adsorbed on electropositive microporous filters survived at least 5 weeks at 4 degrees C. Poliovirus type 1 and bacteriophage f2 also survived at least 6 weeks at -20 degrees C. Rotavirus SA-11 was not recovered after 1 week at -20 degrees C. The stability of viruses adsorbed on electropositive filters may enable extensive monitoring of viruses in water.
Relation of rumen ATP concentration to bacterial and protozoal numbers
Authors: Nuzback D E , Bartley E E , Dennis S M , Nagaraja T G , Galitzer S J , Dayton A D
Published: January 2020

Cultures of Streptococcus bovis and mixed populations of rumen bacteria were used to investigate the concentration of ATP and rumen bacterial numbers at various stages of growth. ATP, extracted with Tris buffer, was analyzed using the firefly luciferin-luciferase bioluminescent reaction. ATP concentrations of S. bovis and mixed cultures of rumen bacteria significantly correlated with live cell counts during the log phase of growth but not during the stationary phase. The average cellular ATP concentration of rumen bacteria was calculated to be 0.3 fg of ATP per cell. Studies done with in vivo artificial rumen apparatus revealed that the protozoal contribution to rumen fluid ATP pool size was much more substantial than was the bacterial contribution. The rumen fluid ATP concentration was greater in cattle with protozoa than in those that were defaunated. Differences in ATP concentration due to size differences of ciliate protozoa were observed. Due to the unbalanced distribution of ATP in rumen microbes, ATP appears to be an unsuitable indicator of rumen microbial biomass.
Highly Efficient Mutagenesis of
Claviceps purpurea
by Using Protoplasts
Authors: Keller Ullrich
Published: January 2020

Claviceps purpurea
ATCC 20102, which is aconidial under laboratory conditions, was grown in submerged culture in the presence of mutagens and various nutritional additives. Protoplasts from such cultures were prepared and regenerated on solid medium to obtain colonies from single cell units. Frequencies of auxotrophs and high alkaloid producers were on the order of 1 to 2%. Some of the auxotrophic mutants derived from strain ATCC 20102 were constantly segregating prototrophs. High-alkaloid-producing derivatives showed sclerotia-like morphology and violet-brown pigmentation, in contrast to the parent strain; some of them also showed segregation sectors when grown as giant colonies. Mutagenesis of strain 1029, isolated during this study and having an increased level of alkaloid synthesis and sclerotia-like cell morphology, was done in the same fashion as with the original parent strain, ATCC 20102. Mutants obtained from this strain were all stable with respect to their genotypes. However, a large proportion of colonies derived from regenerated protoplasts, even in the mutagen-free controls, showed a lowered level of alkaloid production and were morphologically more similar to the original wild type, ATCC 20102. The influence of protoplast preparation or regeneration or both on the stability of genes involved in differentiation is discussed.
Cell Wall Composition of
Neurospora crassa
Under Conditions of Copper Toxicity
Authors: Subramanyam C. , Venkateswerlu G. , Rao S. L. N.
Published: January 2020

The mycelia of
Neurospora crassa
grown in the presence of high concentrations of copper were blue in color, but only on a medium containing inorganic nitrate and phosphate as the nitrogen and phosphate sources, respectively. The cell wall isolate of the blue mycelia contained large amounts (12%) of copper and higher amounts of chitosan, phosphate, and amino groups, with a 42% decrease in the chitin content. Although all the glucosamine of the cell wall of control cultures could be released within 6 h of hydrolysis with acid, that of the blue mycelium required prolonged hydrolysis for 24 h. On removal of copper, the cell wall of the blue mycelium could quantitatively bind again to copper as well as to zinc. Although zinc binding was fivefold greater, copper alone was preferentially bound from a mixture of the two metal ions. Supplementation of iron along with copper in the culture medium resulted in the disappearance of the blue color of the mycelium and restoration of normal growth and composition of the cell wall, probably by limiting the uptake of copper from the medium. The possibility of the cell wall being a specific site of lesion in copper toxicity in the mold is discussed.
Metabolic activity and enzyme induction in rat fecal microflora maintained in continuous culture
Authors: Mallett A K , Bearne C A , Rowland I R
Published: January 2020

The enzyme activity of the rat hindgut microflora maintained in an anaerobic two-stage continuous culture was compared with that of rat cecal contents. A qualitative comparison (API ZYM) showed a high degree of similarity between the two populations. Quantitative determinations showed that azoreductase, beta-glucosidase, nitrate reductase, and nitroreductase activities were comparable, and that beta-glucuronidase activity was very low in the culture. beta-Glucuronidase, beta-glucosidase, and nitrate reductase activities were induced within the culture by their respective substrates. Bile acids influenced microbial activity in vitro, with cholic acid inducing beta-glucosidase, azoreductase, and beta-glucuronidase activities and decreasing nitrate reductase activity. Chenodeoxycholic acid increased beta-glucosidase and beta-glucuronidase activities and decreased azoreductase, nitrate reductase, and nitroreductase activities in vitro. These studies demonstrate that the rat hindgut microflora may be successfully cultured in vitro and suggest control mechanisms that regulate the metabolic activity of these organisms in vivo.
Inactivation of hepatitis A virus and indicator organisms in water by free chlorine residuals
Authors: Grabow W O , Gauss-Müller V , Prozesky O W , Deinhardt F
Published: January 2020

Hepatitis A virus (HAV) and selected indicator organisms were mixed together in chlorine-demand-free buffers at pH 6, 8, or 10 and exposed to free chlorine residuals, and the survival kinetics of individual organisms were compared. HAV was enumerated by a most-probable-number dilution assay, using PLC/PRF/5 liver cells for propagation of the virus and radioimmunoassay for its detection. At all pH levels, HAV was more sensitive than Mycobacterium fortuitum, coliphage V1 (representing a type of phage common in some sewage-polluted waters), and poliovirus type 2. Under certain conditions, HAV was more resistant than Escherichia coli, Streptococcus faecalis, coliphage MS2, and reovirus type 3. It was always more resistant than SA-11 rotavirus. Evidence is presented that conditions generally specified for the chlorine disinfection of drinking-water supplies will also successfully inactivate HAV and that HAV inactivation by free chlorine residuals can reliably be monitored by practical indicator systems consisting of appropriate combinations of suitable indicators such as coliform and acid-fast bacteria, coliphages, the standard plate count, and fecal streptococci.
Deoxynivalenol, acetyl deoxynivalenol, and zearalenone formation by Canadian isolates of Fusarium graminearum on solid substrates
Authors: Greenhalgh R , Neish G A , Miller J D
Published: January 2020

Three isolates of Fusarium graminearum (DAOM 180377, 180378, and 180379) were screened for their ability to produce mycotoxins on the solid substrates corn and rice. They all produced deoxynivalenol and zearalenone on corn. On rice, only DAOM 180378 and 180379 produced significant amounts of these mycotoxins, with levels of deoxynivalenol being much higher than those of zearalenone. The effects of the initial moisture content before autoclaving, incubation temperature, and time were studied with isolate DAOM 180378. At 19.5 degrees C the main product was zearalenone, whereas at 25 degrees C both deoxynivalenol and zearalenone were formed. Higher incubation temperatures (28 degrees C) favored deoxynivalenol formation, the maximum amount being 515 ppm (515 micrograms/g) formed after 24 days at an initial moisture content of 40%. The maximum level of zearalenone produced at the same temperature was 399 ppm, but at an initial moisture content of 35%. Other factors, such as pH, oxygen and carbon dioxide concentrations, and size of the culture flask also appeared to affect the production of mycotoxins.
Detection and enumeration of virulent Yersinia enterocolitica in food by DNA colony hybridization
Authors: Hill W E , Payne W L , Aulisio C C
Published: January 2020

A portion of a 44-megadalton plasmid found in Yersinia enterocolitica 8081 was used as a genetic probe to differentiate virulent and nonvirulent strains of the species. A DNA colony hybridization technique was employed. Three BamHI restriction endonuclease fragments labeled with 32P by nick translation were hybridized to lysed colonies of pure cultures, mixtures of virulent and nonvirulent cells, and portions of a food sample artificially contaminated with virulent Y. enterocolitica. The results of the colony hybridization test for virulence were the same as those obtained by the autoagglutination and suckling mouse tests. DNA colony hybridization detects pathogenic Y. enterocolitica in foods without the need for enrichment or pure cultures.
Enterotoxin production by Vibrio cholerae and Vibrio mimicus grown in continuous culture with microbial cell recycle
Authors: Spira W M , Fedorka-Cray P J
Published: January 2020

We have examined the effect of complete cell recycle on the production of cholera toxin (CT) by Vibrio cholerae and CT-like toxin by Vibrio mimicus in continuous culture fermentations. Complete cell recycle was obtained by filtering culture fluids through Amicon hollow fibers with an exclusion limit of 100,000 daltons (H1P100-20) and returning the concentrated cell slurry to the fermentor. A single 1-liter laboratory fermentor system modified with this recycle loop was capable of producing over 20 liters of cell-free culture filtrate per day. Toxin production in this system was compared with yields obtained in traditional continuous cultures and in shake flask cultures. Yields of CT from V. cholerae 569B in the recycle fermentor were highest at the highest dilution rate employed (1.0 vol/vol per h). The use of complete cell recycle dramatically increased yields over those obtained in continuous culture and equaled those obtained in shake flasks. The concentration of CT in the filtrate was slightly less than half of that measured in culture fluids sampled at the same time. Similarly, V. mimicus 61892 grown in the presence of 50 micrograms of lincomycin per ml produced 280 ng of CT per ml in the recycle fermentor, compared with 210 ng/ml in shake flasks under optimal conditions. The sterile filtrate from this fermentation contained 110 ng/ml.
Analysis of Distributed Growth of
Saccharomyces cerevisiae
Cells Immobilized in Polyacrylamide Gel
Authors: Burrill Hugh N. , Bell Laurel E. , Greenfield Paul F. , Do Duong D.
Published: January 2020

A technique is described for the quantitative determination of the distributed growth of
Saccharomyces cerevisiae
immobilized in polyacrylamide gel. Gel specimens were embedded in paraffin or gelatin and paraffin before sectioning and staining. Photomicrographs of specimen sections were enlarged, and cell microcolony volumes were determined as a function of position in the gel by grid transparency analysis. Overall cell densities within the gel were calculated for a quantitative comparison with values measured by a second spectrophotometric method. The results show good agreement and demonstrate the sigmoidal growth of the immobilized cells, reaching a maximum steady-state value. The technique shows promise as a general method for following the transient growth of organisms immobilized within gel particles.
Bacterial degradation of lignified wood cell walls in anaerobic aquatic habitats
Authors: Holt D M , Jones E B
Published: January 2020

Test blocks of beech (Fagus sylvatica) and Scots pine (Pinus sylvestris) were buried in fresh, brackish, and seawater anaerobic muds for periods ranging between 1 and 18 months. At appropriate time intervals the test blocks were recovered and examined for changes in weight and for bacterial attack of lignified wood cell walls. Only small weight losses occurred. Scanning electron microscopy studies revealed that there was extensive superficial bacterial erosion of beech wood cell walls. The decay patterns are illustrated by micrographs and discussed in relation to other types of bacterial attack.
Binding of metallic ions to the outer membrane of Escherichia coli
Authors: Hoyle B , Beveridge T J
Published: January 2020

The binding of metal ions by the outer membrane of Escherichia coli K-12 strain AB264 was investigated by using outer membrane obtained after Triton X-100 extraction of purified cell envelopes. Binding studies, conducted under saturating conditions, indicated a selective trapping of certain metallic ions. Low-dose electron microscopy of metal-loaded samples revealed an aggregative deposition of lead on one surface of the membrane which suggests that at least one distinctive binding site is asymmetrically arranged in these outer membrane vesicles.
Conjugal Transfer of Broad-Host-Range Plasmid pAMβ1 into Enteric Species of Lactic Acid Bacteria
Authors: Vescovo M. , Morelli L. , Bottazzi V. , Gasson M. J.
Published: January 2020

The broad-host-range plasmid pAMβ1, which codes for erythromycin and lincomycin resistance, was transferred by conjugation into
Lactobacillus acidophilus, Lactobacillus reuteri
, and
Lactobacillus salivarius.
A novel 17-megadalton plasmid molecule was detected in the transconjugants, confirming the introduction of pAMβ1 into each species.
Fungal Toxicity of Mobilized Soil Aluminum and Manganese
Authors: Firestone M. K. , Killham K. , McColl J. G.
Published: January 2020

Inhibition of
Aspergillus flavus
growth from spores was used as a simple bioassay for toxicity of Al and Mn mobilized by simulated acid precipitation. Al was identified as being toxic in soil leachates resulting from acid inputs of pH less than 2.7. Inhibition by Mn was not detectable. The addition of fluoride significantly reduced Al toxicity, suggesting that biotoxicity of Al is partially dependent on the anionic composition of the soil solution.
Identification of Low-Molecular-Weight Nucleic Acid-Related Substances Secreted by
Streptomyces aureofaciens
Authors: De Carvalho Alírio , Molinari Rubens
Published: January 2020

Streptomyces aureofaciens
growth in chemically defined medium is actively associated with the secretion of low-molecular-weight nucleic acid-related substances and is linked to low availability of phosphate. Thirteen pure compounds were isolated, of which seven were identified.
Relationship between colonization of hospital building with Legionella pneumophila and hot water temperatures
Authors: Plouffe J F , Webster L R , Hackman B
Published: January 2020

Legionella pneumophila was isolated from four hospital buildings that maintained hot water storage temperatures at 43 to 45 degrees C. Two adjacent hospital buildings with negative cultures maintained temperatures at 58 to 60 degrees C.
Effect of Microorganisms on In Situ Uranium Mining
Authors: Yates Marylynn V. , Brierley James A. , Brierley Corale L. , Follin Steven
Published: January 2020

The extraction of some metal values, e.g., uranium or copper, may be accomplished by using solutions to remove metals from ore bodies without practicing conventional mining. This process is referred to as in situ leaching and has been used industrially to recover uranium. The growth of microbial populations during in situ leaching is believed to be one of the causes of flow path plugging in the ore body, which results in decreased uranium production. Leach solution and solid samples from well casings and submersible pumps were collected from an in situ mining operation experiencing plugging problems.
Bacillus
sp.,
Micrococcus
sp., pseudomonads, and xanthomonads were isolated from these samples in concentrations of 10
5
CFU ml
−1
. A mixed culture of these organisms was inoculated into a uranium core specimen in the laboratory to assess the role of microbes in the plugging problem. A one-third decrease in permeability was effected in 16 days. Hydrogen peroxide (0.2 g liter
−1
) killed the microorganisms in the core and alleviated the plugging problem. Periodically injecting hydrogen peroxide into the ore body through the production wells may reduce microbial plugging problems.
Elution of viruses from coastal sediments
Authors: Tsai S C , Ellender R D , Johnson R A , Howell F G
Published: January 2020

Enteric viruses were eluted from estuarine sediments by using four organic mixtures; these solutions, with or without various supplements, were compared by determining their abilities to desorb virus from sediments taken from shellfish-harvesting sites. The least effective eluents consisted of glycine buffer, milk preparations, and beef extract paste. When virus type and sediment composition were taken into consideration, higher percentages of virus recovery were achieved with isoelectric casein, powdered beef extract, and nutrient broth mixtures. In addition to the type of eluent used, variations in virus recovery were due to the pH of the eluent, the composition of the sediment, and the type of virus being extracted. No clear distinction between the values of protein and inorganic ion supplements could be made.
Competition of
Rhizobium japonicum
Strains in Early Stages of Soybean Nodulation
Authors: Kosslak Renee M. , Bohlool B. Ben , Dowdle Stephen , Sadowsky Michael J.
Published: January 2020

The effects of preexposure of soybean (
Glycine max
L. Merrill) roots to
Rhizobium japonicum
strains and subsequent establishment of other strains in the nodules were investigated by using combinations of effective strains (USDA 110 and USDA 138) and effective-ineffective strains (USDA 110 and SM-5). Strain USDA 110 was a better competitor than either USDA 138 or SM-5 on cultivars Lee and Peking. However, when either of the two less-competitive strains was inoculated into 2-day-old seedlings before USDA 110 was, their nodule occupancy increased significantly on both cultivars. With USDA 138 as the primary inoculum and USDA 110 delayed for 6, 48, and 168 h, the incidence of USDA 138 nodules increased on cultivar Peking from 6% (at zero time) to 28, 70, and 82% and on cultivar Lee from 17% (at zero time) to 32, 88, and 95% for the three time delays, respectively. Preexposure of 2-week-old roots of cultivar Lee to USDA 138 had essentially the same effect: the incidence of USDA 138 nodules increased from 23% at zero time to 89 and 97% when USDA 110 was delayed for 24 and 72 h, respectively. When the ineffective strain SM-5 was used as the primary inoculum, followed by USDA 110 72 h later, the percentage of nodules containing SM-5 increased from 7 to 76%. These results indicate that the early events in the nodulation process of soybeans are perhaps the most critical for competition among
R. japonicum
strains.
Occurrence of Lactic Acid Bacteria During the Different Stages of Vinification and Conservation of Wines
Authors: Lafon-Lafourcade S. , Carre E. , Ribéreau-Gayon P.
Published: January 2020

We showed that the growth of lactic acid bacteria during alcoholic fermentation depends on the composition of the must. We illustrated how the addition of sulfur dioxide to the must before fermentation and the temperature of storage both affect the growth of these bacteria in the wine. Whereas species of
Lactobacillus
and
Leuconostoc mesenteroides
were isolated from grapes and must,
Leuconostoc oenos
was the only species isolated after alcoholic fermentation. This organism was responsible for the malolactic fermentation. Isolates of this species varied in their ability to ferment pentoses and hexoses. The survival of
Leuconostoc oenos
in wines after malolactic fermentation depended on wine pH, alcohol concentration, SO
2
concentration, and temperature of storage.
2-Aminoethylphosphonic acid concentrations in some rumen ciliate protozoa
Authors: Whitelaw F G , Bruce L A , Eadie J M , Shand W J
Published: January 2020

The concentration of 2-aminoethylphosphonic acid has been measured in seven genera of rumen ciliate protozoa. Expressed as milligrams per gram of total nitrogen, 2-aminoethylphosphonic acid concentrations ranged from 17.2 in Ophryoscolex spp. to 72.4 in Eremoplastron spp.
Microplate fecal coliform method to monitor stream water pollution
Authors: Maul A , Block J C
Published: January 2020

A study has been carried out on the Moselle River by means of a microtechnique based on the most-probable-number method for fecal coliform enumeration. This microtechnique, in which each serial dilution of a sample is inoculated into all 96 wells of a microplate, was compared with the standard membrane filter method. It showed a marked overestimation of about 14% due, probably, to the lack of absolute specificity of the method. The high precision of the microtechnique (13%, in terms of the coefficient of variation for log most probable number) and its relative independence from the influence of bacterial density allowed the use of analysis of variance to investigate the effects of spatial and temporal bacterial heterogeneity on the estimation of coliforms. Variability among replicate samples, subsamples, handling, and analytical errors were considered as the major sources of variation in bacterial titration. Variances associated with individual components of the sampling procedure were isolated, and optimal replications of each step were determined. Temporal variation was shown to be more influential than the other three components (most probable number, subsample, sample to sample), which were approximately equal in effect. However, the incidence of sample-to-sample variability (16%, in terms of the coefficient of variation for log most probable number) caused by spatial heterogeneity of bacterial populations in the Moselle River is shown and emphasized. Consequently, we recommend that replicate samples be taken on each occasion when conducting a sampling program for a stream pollution survey.