bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors Which Increase Acid Production in Milk by Lactobacilli
Authors: Huhtanen C. N. , Williams W. L.
Published: December 2020

The stimulation by yeast extract of acid production in milk by various lactobacilli was studied. It was found that supplementing milk with purine and pyrimidine bases and amino acids allowed nearly maximal acid production by
Lactobacillus bulgaricus
strain 7994,
L. acidophilus
4796, 4356, and 4357, and
L. leichmannii
326 and 327. Further supplementation with deoxyribotides allowed maximal acid production by
L. acidophilus
204, but
L. acidophilus
207 required adenosine or adenylic acid.
L. casei
strain 7469 showed no appreciable response to the amino acids or purine and pyrimidine bases, and is presumed to require an unidentified factor in corn steep liquor.
Survival of Bacteria in Lyophilized Plasma
Authors: Ježková Zdeňka
Published: December 2020

Although lyophilization reduces the bacterial population in plasma, some species survive for several months. Sensitivity or resistance to lyophilization in plasma is a characteristic of each morphological type, with gram-negative species being more sensitive to destruction than cocci or sporulating gram-positive species. Reconstituted preparations of lyophilized plasma must be incubated for 24 hr to prevent false-negative sterility tests. The killing process in lyophilized plasma continues with time if the preparations are stored at room temperature. Strict asepsis must be realized during processing of plasma because lyophilization alone does not destroy the microorganisms present.
Transformation of Steroids by Spores of Microorganisms
Authors: Vézina Claude , Sehgal S. N. , Singh Kartar
Published: December 2020

Conidia of
Aspergillus ochraceus
convert progesterone into 11α-hydroxyprogesterone and 6β, 11α-dihydroxyprogesterone. The conversion ability does not depend on the sporulation medium. Transformation depends on the strain and on the conidia concentration. Adaptation has never been observed. Age and storage of conidia, pH, aeration-agitation, nitrogen source, metal ions, chelating agents, and metabolic activators showed no great influence within wide limits. Mercuric chloride,
p
-chloromercuribenzoate, NaN
3
, and KCN inhibit conversion. Glucose is necessary, but can be replaced completely by
d
(+)-xylose, and partially by some other carbon sources. The ratio mono-/di-hydroxyprogesterone is influenced by progesterone concentration and period of incubation; also, a mutant that accumulates only monohydroxyprogesterone has been produced. Conidia of
A. ochraceus
also hydroxylate a variety of steroids. Spores of certain streptomycetes, phycomycetes (mucors), ascomycetes, and deuteromycetes are active. Most reactions already observed with vegetative cells have been repeated with spores. In general, spores of a particular organism effect fewer reactions than its mycelium, and fewer products accumulate.
Toxic Effect of Staphylococcal Lysins for Goldfish
Authors: Kaplan Milton T. , Appleman Milo D.
Published: December 2020

Goldfish died within 24 hr after intraperitoneal injections of 0.2 ml of Seitz filtrates of hemolytic
Staphylococcus aureus
cultures grown on Dolman and Wilson medium under increased CO
2
pressure for 72 to 96 hr. Two lethal toxins differing in heat sensitivity, antigenicity, and degree of toxicity were demonstrated. Studies of the relationship between the lethal factors and the hemolysins in the filtrates suggested that α- and β-lysin were responsible for the lethal effects. Filtrates of nonhemolytic staphylococcal cultures were innocuous. Goldfish were suitable animals for detecting toxicity in staphylococcal culture filtrates and for quantitative studies of the toxins. The results were highly reproducible.
Microbiological Leaching of Metallic Sulfides
Authors: Razzell W. E. , Trussell P. C.
Published: December 2020

The percentage of chalcopyrite leached in percolators by
Thiobacillus ferrooxidans
was dependent on the surface area of the ore but not on the amount. Typical examples of ore leaching, which demonstrate the role of the bacteria, are presented. In stationary fermentations, changes in KH
2
PO
4
concentration above or below 0.1% decreased copper leaching as did reduction in the MgSO
4
·7H
2
O and increase in the (NH
4
)
2
SO
4
concentration. Bacterial leaching of chalcopyrite was more effective than nonbiological leaching with ferric sulfate; ferric sulfate appeared to retard biological leaching, but this effect was likely caused by formation of an insoluble copper-iron complex. Ferrous sulfate and sodium chloride singly accentuated both bacterial and nonbiological leaching of chalcocite but jointly depressed bacterial action. Sodium chloride appeared to block bacterial iron oxidation without interfering with sulfide oxidation. Bacterial leaching of millerite, bornite, and chalcocite was greatest at pH 2.5. The economics of leaching a number of British Columbia ore bodies was discussed.
Cephalothin, a New Cephalosporin with a Broad Antibacterial Spectrum
Authors: Godzeski C. W. , Brier Gordon , Pavey D. E.
Published: December 2020

Cephalothin is 7-(thiophene-2-acetamido) cephalosporanic acid; it was prepared by
N
-acylation of the nucleus of cephalosporin C, 7-aminocephalosporanic acid. Cephalothin had a broad spectrum of antibiotic activity that was essentially unaffected by human serum or inoculum level, the activity of penicillinase, or pH variation of the growth medium. In vitro development of resistance by staphylococci could not be demonstrated, but the gram-negative organisms did develop a stepwise type of resistance to the antibiotic. Staphylococci made resistant in vitro to 5-methyl-3-phenyl-4-isoxazole penicillin were also resistant to cephalothin and to 6-(2,6-dimethoxybenzamido) penicillin; however, the mechanism of resistance to each antibiotic may have differed. Some complications involved in the laboratory evaluation methods currently in use in the field of antibiotics are examined.
Extracellular Accumulation of Pyrroles in Bacterial Cultures
Authors: Corpe William A.
Published: December 2020

Aerobacter aerogenes, Paracolobactrum aerogenoides, Spirillum serpens
, and gelatinous strains of
Chromobacterium violaceum
produced an extracellular, ether-soluble, Ehrlich-positive substance when grown in media prepared with gelatin hydrolysate. The substance has been tentatively identified as pyrrole-2-carboxylic acid. Both hydroxy-
l
-proline and allo-
d
-hydroxyproline have been shown to be precursors of the material. Gelatinous strains of
Chromobacterium violaceum
, but not the other positive cultures, produced two ether-insoluble pyrroles as well, the precursors of which occur in gelatin hydrolysate but have not yet been identified. The property of pyrrole formation in bacteria and its possible use as an aid in identification of bacteria was discussed.
Repression of
Staphylococcus aureus
by Food Bacteria
Authors: Troller John A. , Frazier W. C.
Published: December 2020

Two food bacteria,
Serratia marcescens
and
Pseudomonas
sp. CS-1, inhibited an enterotoxigenic strain of
Staphylococcus aureus
, apparently by out-competing it for nutrients. Five others,
Bacillus cereus, Proteus vulgaris, Escherichia coli
H-52,
Aerobacter aerogenes
, and
Achromobacter
sp., inhibited by means of antibiotic substances which were Seitz-filterable, dialyzable, and stable at 90 C for 10 min. Inhibition was not caused by changes in pH, oxidation-reduction potential, or production of peroxide or fatty acids. The concentrated antibiotic material from
E. coli
H-52 contained amino acids but not peptides and was especially effective against staphylococci and micrococci.
Selective Isolation of Aerobic Actinomycetes
Authors: El-Nakeeb Moustafa A. , Lechevalier Hubert A.
Published: December 2020

The composition of an arginine-glycerol-salt medium (AGS), suitable for the selective isolation of aerobic actinomycetes, was given. When soil samples were treated with calcium carbonate and plated on the AGS medium, higher total and relative plate counts of actinomycetes were obtained than when other media and methods were used.
Antifungal Activity of Ring Poly-Chlorinated Pyrimidines: Structure Activity Relationships
Authors: Gershon Herman , Parmegiani Raulo
Published: December 2020

A total of 48 ring chlorinated pyrimidines was screened against strains of five fungi by the disc-plate method, in liquid culture, and for activity of the vapors of the compounds. Correlations of the results obtained by the three methods were made, and structure to activity relationships were discussed. The outstanding members of this series were found to be 2,4,5-trichloropyrimidine, 4,5,6-trichloropyrimidine, and 2-chloromethyl-4,5,6-trichloropyrimidine, in this screening system.
Effect of Radiation Environment on the Thermal Resistance of Irradiated Spores of
Bacillus subtilis
Authors: Licciardello J. J. , Nickerson J. T. R.
Published: December 2020

The degree of heat sensitization induced in spores of
Bacillus subtilis
by irradiation with gamma rays was not changed when irradiation was carried out at low oxygen tension (1 mm of Hg) as compared with irradiation in an air atmosphere. The degree of heat sensitization appeared to be slightly greater at pH 7.0 than at pH 4.5. The substrate was found to influence the degree of induced heat sensitivity with less of an effect produced in complex organic substrates.
Microbial Degradation of Asphalt
Authors: Phillips U. A. , Traxler R. W.
Published: December 2020

Organisms of the genera
Pseudomonas, Chromobacterium
, and
Bacillus
capable of degrading asphalt were isolated by enrichment cultures. The asphalt degradation by these organisms varied from 3 to 25% after incubation for 1 week. The effects of temperature, pH, and atmosphere of incubation on asphalt degradation were investigated and were shown to vary with different organisms on the same substrate.
Evaluation of a New Bactericidal Spray Effective against
Staphylococcus aureus
Authors: Andersen Ariel A.
Published: December 2020

A new germicidal spray consisting of an active ingredient, 2-chloro-4-phenylphenol, solvent, and propellant was evaluated against aerosols of
Staphylococcus aureus
and spores of
Bacillus subtilis
. The method of evaluation consisted of determining the decay rate of the bacterial aerosols in a small chamber, with and without the aerial germicide present. The method is unique in that the effect of very short exposures of airborne bacteria to aerial germicides can be measured accurately. By use of the method outlined, extremely potent aerial germicides may be evaluated against highly sensitive organisms. The 2-chloro-4-phenylphenol spray was found to be extremely effective against
S. aureus
but only moderately effective against spores of
B. subtilis
.
Production of Oxalic Acid by a Wood-Rotting Fungus
Authors: Tsao George Tsu-Ning
Published: December 2020

The wood-rotting fungus
Pleurotus ostreatus
NRRL 2366 was grown successfully in submerged shaker cultures in which it produced oxalic acid from simple carbohydrates as efficiently as did
Aspergillus niger. P. ostreatus
also produced oxalic acid from mixtures of sawdust and CaCO
3
, and from the solid residue from the acid hydrolysis of wood when the culture was supplemented with inorganic nutrients.
A. niger
produced oxalic acid from the liquid hydrolysate.
Production of Oxalic Acid by a Strain of
Agaricus campestris
Authors: Tsao George Tsu-Ning
Published: December 2020

A strain of the common mushroom
Agaricus campestris
was grown on a mixture of composted sawdust and CaCO
3
. On incubation for 47 days, the organism produced 20.5 g of oxalic acid per 100 g of initial dry compost solids.
Versatile Medium for the Enumeration of Sulfate-Reducing Bacteria
Authors: Postgate John R.
Published: December 2020

A lactate-yeast extract-sulfate medium, making use of both thioglycolate and ascorbate to poise the E
n
gave valid colony counts of sulfate-reducing bacteria with both pure cultures and natural samples.
Comparison of Enterococci and Coliform Microorganisms in Commercially Produced Pecan Nut Meats
Authors: Hyndman James B.
Published: December 2020

Pecan nut meats in the unbroken shell are sterile for enteric microorganisms. Recovery of coliform microorganisms or enterococci from finished pecan nut meats indicated contact contamination, assuming the tempering procedures to be satisfactory. Results of specific studies, designed toward developing background data on the sanitary significance of enterococci and coliform microorganisms in the production of pecan meats are reported. Unbroken pecan nuts or nut meats from various stages of shelling operations were diluted with a phosphate-buffered diluent. Serial dilutions were inoculated into Lactose Broth and Azide Dextrose Broth. The lactose fermentors were carried through indole, methyl red, Voges-Proskauer, and citrate reactions; the positive Azide Dextrose cultures were confirmed in Ethyl Violet Azide Broth and microscopically. Viable plate counts were obtained. Enterococci were found resistant to many deterrent factors affecting coliforms. Recoveries of enterococci were detected long after pollution had occurred. Little correlation was found between enterococcal recovery and observed insanitary practices in commercial shelling operations. Using the coliaerogenes group and, specifically,
Escherichia coli
as a sanitation index, microorganisms allowed accurate appraisal of tempering, personnel practices, and contact surface contaminating factors. It is felt this was due, in part, to the more delicate growth characteristics of
E. coli
. The fact that other pathogenic microorganisms, capable of causing gastrointestinal upsets, are associated with the presence of
E. coli
introduces a health factor which is important to regulatory agencies concerned with consumer protection.
Statistical Study of the Spot-Plate Technique for Viable-Cell Counts
Authors: Gaudy A. F. , Abu-Niaaj F. , Gaudy E. T.
Published: December 2020

A statistical study of the spot-plate technique was made for the purpose of establishing an acceptable counting range. The organism used in these studies was
Micrococcus lysodeikticus
. Standard deviations and coefficients of variation were computed for counts ranging from 20 to 440. The lower and upper limits for acceptable counts, based on coefficients of variation of 10 and 5.8, respectively, were chosen as 100 and 300.
Psychrophilic and Mesophilic Fungi in Frozen Food Products
Authors: Kuehn Harold H. , Gunderson Millard F.
Published: December 2020

The mold flora of certain frozen pastries and chicken pies was investigated. Molds were determined qualitatively or quantitatively, or both, by preparing pour plates of the blended product and incubating the plates at various temperatures. The mesophilic fungal flora developed on plates incubated at 10 and 20 C, whereas psychrophilic fungi were obtained on plates incubated at 0 and 5 C. About 2,000 cultures of fungi, representing about 100 different species, were isolated from various products. Four different brands of blueberry, two brands of cherry pastries, two brands of apple, and one brand of raspberry pastries were examined. In addition, two brands of chicken pies were studied. Blueberry pastries had a much higher total fungal population than the other products, although different brands of blueberry pastries varied considerably. Blueberry pastries had from 347 to 1,586 psychrophilic fungi per g. Cherry pastries had about 70 to 110 psychrophiles per g, and apple pastries had 19 to 92 psychrophiles per g. Chicken pies contained very few psychrophilic fungi, about 15 per g.
Aureobasidium pullulans
was recovered most frequently. About 90% of the psychrophilic fungi found in blueberry products was
A. pullulans
. Depending upon the brand of cherry pastry, either
Phoma
spp. or
A. pullulans
was the most common fungus present. Apple pastries also displayed brand variation, but were unique in having many mesophilic aspergilli. This genus was generally absent from other products. The
Penicillium
content of apple pastries was also rather high; 50% of the psychrophilic flora was represented by this genus. The psychrophilic fungal flora of chicken pies was composed primarily of penicillia (50%) and
Chrysosporium pannorum
(46%).
Sorbic Hydroxamic Acid, an Antifungal Agent Effective over a Wide pH Range
Authors: Dudman W. F.
Published: December 2020

Sorbic hydroxamic acid was prepared from sorbic acid by esterification and treatment with hydroxylamine (mp 133 to 135 C, pK
a
8.8). Its ultraviolet spectrum in acid solution had a single absorption maximum at 262 mμ; in alkaline solution the maximal absorption shifted to 255 mμ and significant absorption appeared at 280 to 300 mμ. At concentrations of 0.1% (w/v), sorbic hydroxamic acid prevented the growth of
Aspergillus niger, Penicillium notatum, Botrytis cinerea, Cladosporium herbarum
, and a
Rhizopus
species in grape juice over the pH range 3.6 to 9.2, although sorbic acid was not effective at pH 5.7 and above.
Sporicidal Activity of Alkaline Alcoholic Saturated Dialdehyde Solutions
Authors: Pepper Rollin E. , Chandler Velma L.
Published: December 2020

During a search for a sporicidal agent to equal or surpass formaldehyde in activity, a group of saturated dialdehydes ranging from two to six carbons was discovered. These dialdehydes exerted a surprisingly high degree of activity in isopropanol buffered with a carbonate or bicarbonate. Without the proper buffer, practically no activity was observed. A solution of 1% glutaraldehyde, 0.3% NaHCO
3
, and 70% isopropanol sterilized stainless-steel penicylinders contaminated with standardized numbers of four spore types in a shorter time than did commercially available 8% formaldehyde solution. Both glyoxal and glutaraldehyde in isopropanol destroyed spores in a relatively short time. Care was taken to eliminate bacteriostasis. Various tests were performed to evaluate accurately experimental and formaldehyde solutions.
Testing Air-Filtering Systems
Authors: Songer Joseph R. , Sullivan James F. , Hurd James W.
Published: December 2020

A procedure was developed for evaluating high-efficiency filters mounted in exhaust ducts at the National Animal Disease Laboratory. An aerosol of the test organism,
Escherichia coli
B T
3
bacteriophage, was generated in a chamber attached to a ceiling exhaust register in concentrations of at least 1000 viable organisms per ft
3
of air. Samples were collected from both the pre- and postfilter areas, and the number of organisms per ft
3
of air was determined. The efficiency of the filter was calculated from these figures. A total of 269 high-efficiency filters were tested. Of these, 249 had efficiencies of 98% or greater. The remaining 20, with efficiencies of less than 98%, were repaired and retested. No filter was accepted with an efficiency of less than 98%.
Inactivation of the Radiation-Resistant Spoilage Bacterium
Micrococcus radiodurans
Authors: Duggan D. E. , Anderson A. W. , Elliker P. R.
Published: December 2020

A simplified technique permitting the pipetting of raw puréed meats for quantitative bacteriological study is described for use in determining survival of these non-sporing bacteria, which are exceptionally resistant to radiation. Survival curves, using gamma radiation as the sterilizing agent, were determined in raw beef with four strains of
Micrococcus radiodurans
. Survival curves of the R
1
strain in other meat substrates showed that survival was significantly greater in raw beef and raw chicken than in raw fish or in cooked beef. Resistance was lowest in the buffer. Cells grown in broth (an artificial growth medium) and resuspended in beef did not differ in resistance from cells that had been grown and irradiated in beef. Survival rate was statistically independent of the initial cell concentration, even though there appeared to be a correlation between lower death rate and lower initial cell concentrations. The initial viable count of this culture of the domesticated R
1
strain in beef was reduced by a factor of about 10
-5
by 3.0 megarad, and 4.0 megarad reduced the initial count by a factor of more than 10
-9
. Data suggest that
M. radiodurans
R
1
is more resistant to radiation than spore-forming spoilage bacteria for which inactivation rates have been published.
Bacterial Vaccine in Multidose Tablet Form for Parenteral Use
Authors: Berman Sanford , Lowenthal Joseph P. , Grogan Earl W. , Altieri Patricia L. , Benenson Abram S.
Published: December 2020

Dried typhoid vaccines were prepared by freeze-drying of heat-inactivated phenolized-cell suspensions and by an acetone-killed and dried technique. Portions of the dried powder obtained by each method were compressed into tablets. Tests with the products showed that drying and making of tablets did not affect the ability of the vaccines to protect mice or elicit antibodies in rabbits.
Gas Exchange with Mass Cultures of Algae
Authors: Hannan P. J. , Patouillet Constance
Published: December 2020

The performance of a small photosynthetic gas exchanger is described in which simultaneous measurements of suspension density, O
2
production, and CO
2
absorption are readily accomplished. The volume of suspension was 6200 ml. With the Sorokin strain of
Chlorella pyrenoidosa
7-11-05, this unit produced 4500 cc of O
2
per hr at a light intensity of 34,000 ft-c from each of six Quartzline lamps. At any given light intensity, the O
2
production was proportional to the rate of CO
2
input up to a maximum. The impetus for this study was the consideration of the algal system as a means of oxygen generation in a submarine. Based on the performance of this unit, the power requirement per man for a system having the geometry described would be 52 kw, but reasons are given for the hope that this may be reduced to less than 5 kw.
Kinetics of Heat Activation and of Thermal Death of Bacterial Spores
Authors: Shull James J. , Cargo Gerald T. , Ernst Robert R.
Published: December 2020

Hypotheses concerning kinetics of heat activation and of thermal death of bacterial spores were formulated, and were employed to derive equations describing nonlogarithmic thermal death curves. The equations permitted evaluation of the validity of experimental data and provided a means for testing the hypotheses presented.
Influence of Agar on the Morphology and Pigmentation of Streptomycetes
Authors: Okami Yoshiro , Arima Shigezumi , Suzuki Motoko
Published: December 2020

The effect of various agar preparations in a chemically defined medium on promoting the development of taxonomic characteristics of streptomycetes was studied. Various agar products gave different results. Agar purified to a certain extent was favorable for good, constant development of such characteristics. The presence of certain metals played a great role in this domain. Agar purified to a high degree may give poor results unless supplemented with the proper metals. Recommendations were made for the standardization of agar media used for the study of characteristics of streptomycetes.
Violet-Pigmented Pseudomonads With Antifungal Activity From the Rhizosphere of Beans
Authors: Ayers W. A. , Papavizas G. C.
Published: December 2020

Bean rhizosphere bacteria antagonistic to four root-infecting fungi and an antibiotic produced by these bacteria were studied. The bacteria were violet-pigmented gram-negative rods, probably belonging to the genus
Pseudomonas
. The antibiotic, which was localized largely in the bacterial cell mass, was easily extracted with acetone. It was selectively active against a wide variety of plant-pathogenic and saprophytic fungi tested in vitro but was relatively inactive against bacteria. The compound, partially purified by chromatography, was soluble in all organic solvents tried, but nearly insoluble in water. It demonstrated no characteristic ultraviolet- or visible-absorption spectrum and was chemically unidentified. The antagonistic bacteria or crude antibiotic applied to buried buckwheat segments suppressed the colonization of this substrate by
Rhizoctonia
spp. The data suggested that the bacteria or the antibiotic may play a role in the suppression of root-infecting fungi in soil.
Prodigiosin-Producing Bacteria from Marine Sources
Authors: Lewis S. M. , Corpe W. A.
Published: December 2020

Two aerobic, gramnegative, red-pigmented, rod-shaped bacteria were compared morphologically and physiologically with
Serratia
species, which they resembled superficially. The pigment produced by the marine isolates was shown to be similar to prodigiosin, the red pigment of
S. marcescens
. The isolates had a single polar flagellum, were oxidative, and did not produce acetoin from glucose or reduce nitrates, which made them distinct from both
S. marcescens
and
S. marinorubra
. The latter conformed well to the descriptions of
S. marcescens
in
Bergey's Manual
. The marine isolates displayed an absolute growth requirement for sea water or its equivalent. The growth requirement for sea water was replaced by sea-water levels of sodium, potassium, and magnesium chloride. Pigment was produced only when this salt mixture was further supplemented with calcium chloride. Neither sea water nor a high salt level was required for growth or prodigiosin synthesis by the
Serratia
species examined.
Comparison of Direct Plating Media for the Isolation and Enumeration of Enterococci in Certain Frozen Foods
Authors: Burkwall Mary K. , Hartman Paul A.
Published: December 2020

A total of 15 agar media were examined for their yield, selectivity, readability, and simplicity of preparation and use. A thallium medium of Barnes was selected as the better of the high yield-fair selectivity type of medium and an azide-citrate medium of Reinbold appeared to be the better of the low yield-high selectivity type of medium. Sodium carbonate (optimal concentration, 0.20%) was found to increase recovery substantially when added to certain media, especially in the presence of 0.05% Tween 80. When these two ingredients were incorporated into a medium modified after Slanetz and Bartley, the resultant medium was superior to other media for the isolation and enumeration of enterococci in certain frozen foods, such as peas and hamburger, by the direct plating method.
Single-Stage Impaction Device for Particle Sizing Biological Aerosols
Authors: Malligo John E. , Idoine Leon S.
Published: December 2020

A single-stage impactor device, capable of fractionating a bacterial aerosol into its component mass size classes while preserving the viability of sensitive vegetative cells against the deleterious effects of desiccation and impaction, is described. Among the valuable features of the impactor are its negligible wall loss, ease of fabrication and use, and relative inexpensiveness.
Preparation of Axenic Cultures of Algae by Use of a French Press
Authors: Middlebrook J. B. , Bowman R. O.
Published: December 2020

The differences in fragility of microorganisms when treated in the French press are useful for destroying bacteria and mold contaminants, and assist in the preparation of axenic cultures of
Chlorella
.
Degradation of Wood Preservatives by Fungi
Authors: Duncan Catherine G. , Deverall Flora J.
Published: December 2020

Wood-inhabiting fungi, not necessarily responsible for major decay, are shown to be capable of degrading a toxic compound into a less potent form, thus rendering it less effective in protecting wood from decay by less-tolerant basidiomycetous wood-destroyers. Sweetgum or pine sapwood blocks treated with preservatives (ammoniacal copper arsenate, fluor-chrome-arsenate-dinitrophenol, a creosote or pentachlorophenol) were exposed progressively to two different wood-inhabiting fungi with sterilization between the first and second exposure. The fungus in the first exposure was usually an Ascomycete or a Fungi Imperfecti—
Chaetomium globosum, Phoma, Orbicula, Graphium, Pestalozzia
, or
Trichoderma
species, isolated from wood below the ground. In one experiment, the fungus in the first exposure was a basidiomycete,
Lenzites trabea
or
Polyporus versicolor
. The second fungus, a prominent Basidiomycete—
Coniophora puteana, Lentinus lepideus
, or
Lenzites trabea
—was the bioassay fungus, since its purpose was to show whether the first fungus had degraded the preservative. Generally, the treated block, except where exposed to another fungus, remained virtually untouched by the bioassay fungus. Clearly, therefore, the first fungus had rendered the preservative ineffective but without appreciably decaying the wood itself Chemical analyses of treated blocks indicated that in the first exposure the fungi had substantially depleted sodium arsenate and pentachlorophenol.
Staphylococci in Competition
Authors: Peterson A. C. , Black J. J. , Gunderson M. F.
Published: December 2020

As is generally known, custards have been frequently involved in staphylococcal food poisonings and are regarded by some as an ideal culture medium. Previous studies showed that high carbohydrate concentrations repressed the growth of competing saprophytic species, allowing the growth of staphylococci in a mixture rather than stimulating the growth of the staphylococci. In an extension of those studies, the influence of the egg constituent of custard was investigated to determine its role in affecting the growth of pathogenic staphylococci in a competing mixture of psychrotrophic saprophytes. The normal competitive effect of the saprophytes on the growth of staphylococci was very slightly affected by the addition of 25% whole egg to the growth media. Approximately 9% egg yolk alone added to the medium resulted in a slight increase in the length of the lag period of the psychrotrophs and a slight increase in the number of staphylococci which grew. Addition of 25% whole egg plus 14.5% sucrose resulted in repression of saprophyte growth similar to that seen in high sucrose concentrations. Staphylococcal growth was more extensive in the presence of both whole egg and sucrose than in the presence of either ingredient alone. Incorporation of 4% corn oil in media was effective in repressing growth of the saprophytes at 37 C only. This allowed the staphylococci to dominate the population. At lower temperatures, staphylococci were unable to compete effectively. Buffering media of high carbohydrate content resulted in lengthened lag periods for the psychrotrophs and the appearance of very large staphylococcal populations.
Enhancing Effect of Feces on Isolation of Salmonellae From Selenite Broth
Authors: Silliker J. H. , Deibel R. H. , Fagan P. T.
Published: December 2020

The addition of feces to selenite broth significantly enhanced the ability of this medium to select for salmonellae in an environment initially containing overwhelming numbers of coliform bacteria. Either heat-sterilized or Seitz-filtered feces produced this effect. In most experiments, the selectivity of selenite broth was unaffected by unsterile feces. Human blood and plasma markedly reduced selenite efficiency. In a base medium supporting both coliform and
Shigella
growth, heat-sterilized feces imposed a measure of selectivity for
Shigella
.
Leaching of Chalcopyrite with
Thiobacillus ferrooxidans
: Effect of Surfactants and Shaking
Authors: Duncan D. W. , Trussell P. C. , Walden C. C.
Published: December 2020

The rate of leaching of chalcopyrite by
Thiobacillus ferrooxidans
has been greatly accelerated by using shaken flasks in place of stationary bottles or percolators. A further increase in rate and extent of leaching was obtained by the use of Tween 20, 40, 60, and 80, Triton X-100, Quaker TT 5386, and Hyamine 2389. Tween 20 was the most effective surfactant. No individual component of the Tween molecule was responsible for the improved leaching. The Tween-to-chalcopyrite ratio is more important than the Tween-to-medium ratio. The effect of the surfactants is probably due to increased contact between the mineral surface and the organism, and shaking provides the necessary oxygen. Rates and yields obtained by use of surfactants and shaking as aids to microbiological leaching approach those obtained with acidified erric sulfate leaching.
Comparison of the Recovery of
Escherichia coli
from Frozen Foods and Nutmeats by Confirmatory Incubation in EC Medium at 44.5 and 45.5 C
Authors: Fishbein Morris , Surkiewicz Bernard F.
Published: December 2020

The productivity of confirmatory EC broth for the isolation of fecal
Escherichia coli
was determined at 44.5 and 45.5 C. A variety of frozen pre-cooked foods and an assortment of nutmeats were examined after primary incubation in Lauryl Sulfate Tryptose (LST) broth. In 85.3% of the cases, the parallel tubes of EC broth incubated for 24 hr at 44.5 and 45.5 C gave rise to identical
E. coli
responses of positive, false positive, and negative. The remaining 14.7% of the reactions represent the qualitative difference between the two temperatures. The EC test at 45.5 C was more specific for
E. coli
, since two- to threefold fewer false positives were produced at this temperature than at 44.5 C. However, fecal
E. coli
recoveries were slightly higher (4%) at the lower temperature. Incubating the EC tubes from the interval of 24 to 48 hr gave rise to an additional 4.3% of
E. coli
recovery, but this was accompanied by an excessive production of false positives (75.9%), representing a 3.5-fold decrease in specificity. It is recommended that, in the confirmatory use of EC broth in the examination of frozen foods and nutmeats for the recovery of fecal
E. coli
, the test be made at 45.5 C in a water bath and limited to 24 hr of incubation only, to insure optimal specificity. During the study, a “fixed” productivity ratio was noted;
E. coli
+
/LST
+
equaled approximately one-fourth or 25%. The significance of this ratio is discussed.
Inactivation of Viruses by Benzalkonium Chloride
Authors: Armstrong J. A. , Froelich E. J.
Published: December 2020

Benzalkonium chloride (as Roccal or Zephiran) was found to inactivate influenza, measles, canine distemper, rabies, fowl laryngotracheitis, vaccinia, Semliki Forest, feline pneumonitis, meningopneumonitis, and herpes simplex viruses after 10 min of exposure at 30 C or at room temperature. Poliovirus and encephalomyocarditis virus were not inactivated under the same conditions. It was concluded that all viruses tested were sensitive except members of the picorna group. The literature was reviewed.
Airborne Microorganisms in Broiler Processing Plants
Authors: Kotula Anthony W. , Kinner Jack A.
Published: December 2020

Concentrations of total aerobic bacteria, molds, yeasts, coliforms, enterococci, and psychrophiles were determined in the air of two poultry processing plants with Andersen samplers and a mobile power supply. Total aerobic bacterial counts were highest in the dressing room, with diminishing numbers in the shackling, eviscerating, and holding rooms, when sampling was carried out during plant operation. The average counts per ft
3
of air in these four rooms were 2,200; 560; 230; and 62, respectively. (Each value is the average of 36 observations.) The number of organisms increased in the shackling and dressing rooms once processing was begun. Average total aerobic bacterial counts increased from 70 to 870 to 3,000 in the shackling room and from 310 to 4,900 to 7,000 in the dressing room when sampling was carried out at 5:00
am
(before plant operations), 9:00
am
, and 2:00
pm
, respectively. (Each value is the mean of 12 observations.) Airborne molds might originate from a source other than the poultry being processed.
Selection of a Microbiological Corrosion System for Studying Effects on Structural Aluminum Alloys
Authors: Hedrick H. G. , Miller C. E. , Halkias J. E. , Hildebrand J. E.
Published: December 2020

Two laboratory methods, a metal-strip test and a tank test, were evaluated as microbiological corrosion systems for producing corroded test specimens on a structural aluminum alloy. The results show that corrosion of the test alloy occurred best in the metal-strip test in a deionized water-fuel medium inoculated with a mixture of microorganisms under aerated conditions. The metal-strip test was more successful for producing large numbers of corroded test specimens and proved more economical than the tank-type test, since less structural material is needed to obtain a specimen with sufficient corrosion areas, and since the corrosion can more easily be restricted by maskants to certain areas for specific test purposes.
Microbial Incorporation of Fatty Acids Derived From
n
-Alkanes Into Glycerides and Waxes
Authors: Davis J. B.
Published: December 2020

When
n
-alkanes with 13 to 20 carbon atoms were fed to a
Nocardia
closely related to
N. salmonicolor
, the produced cellular triglycerides and aliphatic waxes invariably contained fatty acids with an even or an odd number of carbon atoms subject to this feature of the
n
-alkane substrate. Beta-oxidation and C
2
addition are both operative, as evidenced by the spectra of fatty acids incorporated into the cellular lipid components. There is no distinction in the rate of microbial incorporation of the odd-or even-numbered carbon chains. The fatty acids are apparently directly derived from the long chain
n
-alkanes, rather than synthesized via the classic C
2
-condensation route. The alcohol component of waxes produced by the
Nocardia
is invariably of the same chain length as the
n
-alkane substrate.
Rifamycin
Authors: Thiemann J. E. , Hengeller C. , Virgilio A. , Buelli O. , Licciardello G.
Published: December 2020

Five phages, β, γ, 17, 112, and 156, isolated from lysed broth cultures and active on
Streptomyces mediterranei
were characterized with respect to serological inactivation, pH stability, and thermal inactivation rates. With the aid of five antisera, two serological groups, termed A and B and comprising the following phages, could be formed: group A, 156; group B, β, γ, 17, and 112. On the basis of serological similarities, the phages of group B are considered as mutants derived from an identical ancestor. Thermal inactivation rates and pH stability alone do not permit a clear-cut classification of the phages, but are useful as an aid in distinguishing among phages belonging to the same serological group.
Amino Acid Composition of Bulk Protein of
Euglena
Grown in Waste Water
Authors: Kott Yehuda , Wachs A. M.
Published: December 2020

The amino acid content of bulk protein in a sewage-grown
Euglena
sp. was examined. Concentrations of the essential amino acids, threonine, histidine, tryptophan, and valine, were similar to those found in other algae. The concentration of alanine was much higher. Methionine was not found at all, proline only in traces, and other amino acids at low concentrations. These results indicate that the amino acid content of bulk protein of the species of
Euglena
studied resembles that of plants far more closely than that of animals.
Aerosols as a Source of Widespread
Mycoplasma
Contamination of Tissue Cultures
Authors: O'Connell Robert C. , Wittler Ruth G. , Faber John E.
Published: December 2020

Mycoplasma
isolates were cultured from 15 antibiotic-free cell cultures obtained from a single laboratory. Complement-fixation tests showed that these isolates were antigenically related to each other but were unrelated to
M. hominis
type 1,
M. hominis
type 2,
M. arthritidis, M. laidlawii
type B,
Mycoplasma
sp. H.Ep. #2 (Barile), or
M. salivarium
. Examination of serum used to feed the infected cell lines revealed no
Mycoplasma
. Infection resulting from cross-contamination by a single
Mycoplasma
strain from one cell culture to another was investigated. Although the organisms were not found in the air over the work area, aerosols containing these contaminants were produced in tissue culture bottles during the trypsinization of cell monolayers. The minimal infectious dose of
Mycoplasma
for tissue cultures was measured, and it was determined that one organism was capable of initiating an infection in a tissue culture. The pattern of contamination and the small dose required for infection indicated that
Mycoplasma
contamination was spread from one tissue culture to another via aerosols. It was demonstrated that
Mycoplasma
can be transferred from one cell culture to another through the use of a common burette for dispensing medium.
Agar-Gel Precipitin Technique in Anthrax Antibody Determinations
Authors: Ray John G. , Kadull Paul J.
Published: December 2020

A modification of the agar-gel precipitation inhibition technique of Thorne and Belton for detecting anthrax antibodies reduces inconsistency of visually determined end points on the same sera observed by different technicians. Determination of the minimal reacting concentrations of the anthrax antigen and antibody reagents, modifications of the visualization apparatus, methods for combining reagents, and length of incubation periods contribute to the ease of the end-point determinations and the uniformity of results. When compared with the previous technique, the modified procedure is less time-consuming while retaining satisfactory reproducibility, simplicity, specificity, and sensitivity.
Improved Staphylococcus Medium No. 110
Authors: Smuckler Stan A. , Appleman Milo D.
Published: December 2020

Most media have been unreliable when used to determine the number of coagulase-positive staphylococci in meat pot pies in the presence of overwhelming numbers of
Bacillus
cells. Various metabolic inhibitors were tested to determine whether they would suppress the growth of
Bacillus
cells without appreciably affecting the staphylococcal growth. The use of Staphylococcus Medium No. 110 modified by the addition of 0.75 mM sodium azide appears to be practical for the isolation of small numbers of coagulase-positive staphylococci from frozen meat pot pies.
Enzymes Induced in a Bacterium by Growth on Sodium Dodecyl Sulfate
Authors: Williams Joy , Payne W. J.
Published: December 2020

Alkyl sulfatase was induced by growth on nutrient broth plus sodium dodecyl sulfate (SDS) in a bacterium we have designated
Pseudomonas
C12B. Measurement of the radioactivity of S
35
O
4
=
released from SDS
35
by the enzyme in cell-free extracts provided an effective assay technique. The barium chloranilate assay for release of SO
4
=
from SDS was somewhat less sensitive but effective if analyzed at 332 mμ. This test was only approximately 55% as sensitive if analyzed at 530 mμ. The activity of the glyoxylate bypass enzymes, isocitrate lyase and malate synthetase, was significantly stimulated by growth of the bacteria on SDS as the sole carbon source, but not by growth on nutrient broth or nutrient broth plus SDS.
Evaluation of the Extract-Release Volume Phenomenon as a Rapid Test for Detecting Spoilage in Beef
Authors: Jay James M. , Kontou Kalliopi S.
Published: December 2020

Ground beef of several grades, obtained fresh and held refrigerated until spoiled, was presented to a test panel for scoring on color, odor, and tactile response (tackiness) as to degree of acceptance. Panel scores were correlated with total bacterial counts, ninhydrin-reactive substances, and ERV (extract-release volume) on the same meat. ERV correlated highest with bacterial counts the largest number of times; tackiness, odor, ninhydrin, and color followed in that order. Correlation between bacterial numbers and organoleptic qualities was best, with tackiness followed closely by odor, and then by color. Correlation between tackiness and odor was high. The degree of correlation between bacterial numbers, tackiness, and ERV was high enough to warrant the use of the ERV phenomenon as a rapid test of microbial quality of beef. An ERV value of 25 under the conditions of the test was supported as a divider between acceptable and unacceptable ground beef.
Growth of
Chlamydomonas mudana
in the Presence of Different Synthetic Chelators
Authors: Maciasr Frank M.
Published: December 2020

Six synthetic chelators were investigated in culture media for
Chlamydomonas mundana
. The effects on growth of chelator-iron ratios in the range 25 to 400 μM were studied in relation to Ca, heavy metal concentrations, and incubation time. Effects ranged from none through stimulation to inhibition. The most delicate balance of trace metal requirements with any given chelator was established by growth determinations. The behavior of chelators as they affect trace metals in culture media was best understood by consideration of absolute as well as relative stabilities of their metal chelates. Although all the chelators tested, when properly supplemented with microelements, allowed excellent growth, diethylenetriaminepentaacetic acid and diaminocyclohexanetetraacetic acid were least affected by additions of heavy metals and are recommended for use at 50 to 100 μM.
Environmental Stresses on Spore Populations of
Bacillus stearothermophilus
Authors: Fields M. L.
Published: December 2020

Heat-shocking spores at 110 C in 20% sucrose solutions decreased the percentage of the rough variant in a mixed population (rough and smooth variants) of strain M. Heat-shocking spores of the rough variant of strain NCA 1518 in 20% sucrose produced a decline in the number which germinated, whereas the smooth variant of strain NCA 1518 increased in the number which germinated. By the use of phase microscopy and plate counts, from the same incubated spore suspension in distilled water, heat-induced dormancy was demonstrated at 52 C. Dormancy also occurred in 20% sucrose solutions when held at room temperatures. Heat-shocking spores of strain M in 20% sucrose solutions and plating immediately after 24- and 48-hr holding periods at 25 C produced a decline in the total population with the percentage of rough variant increasing with time. A second heat shock produced only an increase in the rough variant.
Inactivation of Airborne Viruses by Ultraviolet Irradiation
Authors: Jensen Marcus M.
Published: December 2020

Aerosolized viruses were passed through a high-intensity ultraviolet (UV) cell. This cell consisted of a long cylindrical aluminum tube [diameter, 7 in. (17.7 cm); length, 36 in. (91.4 cm)] with a highly reflective inner surface and a longitudinally extending helical baffle system which directed airborne particles in close proximity to a centrally located UV lamp. After having been passed through the UV cell, viral aerosols were collected with an Andersen sampler, and viral concentrations were determined by plaque assay methods on tissue cultures. Inactivation rates of greater than 99.9% were obtained for Coxsackie, influenza, Sindbis, and vaccinia viruses, and slightly less for adenovirus (96.8%), when the aerosols passed through the UV cell at 100 ft
3
/min. At aerosol flow rates of 200 ft
3
/min, inactivation rates were slightly lower; 91.3 for adenovirus, 97.5 and 96.7 for Coxsackie and Sindbis, respectively, and greater than 99.9% for influenza and vaccinia viruses.
Milk-Clotting Enzymes From Microorganisms
Authors: Srinivasan R. A. , Iyengar M. K. K. , Babbar I. J. , Chakravorty S. C. , Dudani A. T. , Iya K. K.
Published: December 2020

A total of 230 cultures of fungi and 43 cultures of bacteria, isolated from such sources as soil, butter, and milk, were screened for their milk-clotting activity. The fungi were cultivated on semisolid media, and the bacteria were grown in milk media in shake culture. Phytic acid, added as calcium phytate, was found to stimulate production of the enzyme in most of the bacterial isolates. Proteolytic activity was invariably found to be associated with the milk-clotting enzyme in bacterial isolates. There was considerable variation in the ratio of the two enzymes from strain to strain.