bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Cold Temperatures on the Viability of
Chromobacterium violaceum
Authors: Efthimion Mary H. , Corpe William A.
Published: December 2020

The effect of low, nonfreezing temperatures on the viability of five strains of
Chromobacterium violaceum
was studied. The viability of cultures grown at 30 C was determined after exposure to various diluents held at 0 to 2 C. A culture diluted at its growth temperature served as the control. Cells of strain N were most sensitive in the early part of the exponential phase of growth. Cells of strains 252 and 341 were most sensitive in the late exponential, early stationary phase of growth. Cells of strain 9 showed greatest loss of viability during the maximal stationary phase. Strain 69 was completely resistant throughout its growth cycle to cold injury. Cell viability was much greater in buffered salts solution than in distilled water, broth, or physiological saline, whether cultures were diluted at room temperature or in the cold. The proportion of cells surviving after exposure to cold, however, was the same regardless of the composition of the diluent. Loss of viability was progressive at 0 to 2 C and reached a maximum after 2 hr. There was no loss of viability of cells exposed to 20 C, but there was some loss at 12 C. Strain 341 cultivated at 15 C was much less sensitive to 0 to 2 C than when it was cultivated at 30 C. The composition of the growth medium seemed to have no effect on the survival of cells exposed to cold. The polyamines, spermine and trimethylenediamine, as well as erythritol and sucrose, exerted some protective action against the effects of cold but not uniformly for all strains studied.
Virucidal Effect of Transient Electric Arcs in Aqueous Systems
Authors: Singh M. P , Hermodsson S. , Edebo L.
Published: December 2020

Bacterial and animal viruses were inactivated by high voltage electrical discharges in water. The sensitivity of phages to the immediate component of this effect was correlated to the sensitivity to ultraviolet radiation. Transient electrical arcs in weak electrolytes also generated chemical compounds which were virucidal against phages T3, T5, and ϕX174 but were only slightly virucidal against phages T2 and T4.
New Medium for Blood Cultures
Authors: Morello Josephine A. , Ellner Paul D.
Published: December 2020

A new medium suitable for blood cultures is described. It contains dextrose, cysteine, iron, and magnesium, in a tris(hydroxymethyl)aminomethane buffer, and a mixture of peptones derived from animal tissues, casein, and yeast. In comparison with Trypticase Soy Broth, the growth rate constants of
Staphylococcus aureus, Streptococcus
(Viridans group), enterococcus, and
Escherichia coli
were higher in this medium, and growth appeared earlier in a significant number of clinical blood cultures.
Micromethod for Assaying Serum Levels of Erythromycin
Authors: Bell Stanley C. , Hamman J. Wayne , Grundy Walton E.
Published: December 2020

A micromethod for assaying serum levels of erythromycin is described. The assay had the following characteristics: detection of 0.03 to 0.035 μg/ml, a long-range curve which minimizes sample dilution, 0.04 ml for a single measurement (0.3 ml required for full coverage), and utility for a variety of body fluids. The method employs radial diffusion from small paper discs which were saturated by capillary action rather than by dipping or pipetting. Although the method was designed to handle serum in which the sample volume is limited, statistical analysis demonstrated that the method has satisfactory precision for routine use. A study of 10 consecutive assays indicates a precision of ±12% at the 95% confidence limits. The method of least squares was used to calculate the line of best fit, and the statistics were developed on this basis. The assay method is applicable to a variety of antibiotics.
Patulin Production by
Penicillium urticae
Bainier in Batch Culture
Authors: Norstadt Fred A. , McCalla T. M.
Published: December 2020

A still, batch-culture method, with potato dextrose medium and
Penicillium urticae
Bainier, produced patulin yields of 1.2 to 1.7 g/liter of medium. Incubation was at 25 C for 14 days. Ethyl acetate extraction of condensed culture filtrate and drying with anhydrous MgSO
4
, followed by solvent change to dry ethyl ether and purification on alumina (
p
H 4.5), produced pure crystalline patulin. The use of 2-liter, round-bottom flasks and a rotating vacuum evaporator provided versatile equipment and easy manipulation in the operations. Soil from wheat fields provided a convenient natural
P. urticae
source. Potato dextrose medium was superior to potato sucrose or Raulin-Thom media.

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Estimating the Size and Concentration of Unicellular Microorganisms by Light Scattering
Authors: Merek Edward L.
Published: December 2020

The optical density of suspensions of microorganisms was measured at two different positions in a spectrophotometer cuvette compartment. From these two measurements, the particle size and the particle concentration could be estimated. Estimates of particle numbers were not significantly different from those obtained by direct microscopic counting.
Surfactants as Stimulants of Enzyme Production by Microorganisms
Authors: Reese E. T. , Maguire Anne
Published: December 2020

The addition of Tween 80 and sucrose monopalmitate, nonionic surfactants, to fungal cultures resulted in marked increases in yields of the enzymes cellulase, amylase, sucrase, β-1 → 3 glucanase, xylanase, purine nucleosidase, and benzoyl esterase. The action appears to be an effect of the surfactant on cell permeability.
Marine Microorganisms Associated with the Food of Young Salmon
Authors: Seki Humitake
Published: December 2020

The biomass of microorganisms in the digestive tracts of young salmon in the sea of Saanich Inlet was examined by (i) the direct microscopic method, (ii) the plate count method and (iii) the physiological method (microbial biomass assumed from the release of carbon dioxide). By all methods, most microbial biomass in foods was shown to decrease during its stay in the digestive organ. This observation was supported by the detection of many bacteria at different stages of digestion. The microbial biomass was quantitatively influenced by the composition of food ingested and by the sampling time.
Effect of Shaking Speed and Type of Closure on Shake Flask Cultures
Authors: McDaniel L. E. , Bailey E. G.
Published: December 2020

Growth of microorganisms and biosynthesis of microbial products in shake flasks may be limited by operating conditions which provide inadequate supplies of oxygen. Methods are described for meeting the oxygen requirements of test organisms by using standard baffled flasks with pad-type closures and shaking at relatively high speeds. Growth of
Escherichia coli B
in a rich medium and production of candidin by
Streptomyces viridoflavus
were the test systems used. Flasks shaken at 230 to 385 rev/min gave sulfite oxidation rates of 1 to 8 mmoles of oxygen per liter per min over a useful working volume range (40 to 150 ml in 300-ml flasks). These rates are as high as those obtained in agitated fermentors under usual operating conditions.
Pyocine Typing of Clinical Strains of
Pseudomonas aeruginosa
Authors: Zabransky Ronald J. , Day Fred E.
Published: December 2020

A total of 954 clinical isolates of
Pseudomonas aeruginosa
were typed by their ability to produce pyocines. The strains of
Pseudomonas
were isolated from urines, bloods, sputa, stools, and miscellaneous infectious exudates or tissue of patients of the Mayo Clinic and four associated hospitals. About 80% of the typable strains could be grouped into three major pyocine types: A (30.9%), B (34.8%), and D (14.1%). These large groups could be divided into subtypes by using additional indicator strains. There was no significant difference in the distribution of types by either institutional or specimen source, except that urine specimens yielded the highest percentage of one type. By this procedure, 93% of all isolates could be typed. Repeated typing of serially transferred strains indicated that the procedure has a high degree of reliability. Several strains exhibited extreme fluctuation in inhibition pattern. The procedure is a simple and reliable method to monitor the patterns of nosocomial infections due to
P. aeruginosa
.
Effect of
p
H on Growth and Survival of Three Avian and One Saprophytic
Mycoplasma
Species
Authors: DaMassa A. J. , Adler H. E.
Published: December 2020

The ability of
Mycoplasma meleagridis, M. laidlawii
, an unnamed, nonpathogenic avian species, and three isolates of
M. gallisepticum
to grow and survive in liquid media of various
p
H values was investigated. All species grew over a
p
H range that was generally about two units. The most significant finding was that cultures initiated in media within a
p
H range of approximately 8.5 to 8.9 remained viable for 45 to 60 days at 37 C, whereas cultures initiated at lower values survived for shorter periods.
Production of Alcohol Oxidase by Several Basidiomycetes
Authors: Kerwin Richard M. , Ruelius Hans W.
Published: December 2020

An Amber MPH-Cerelose medium was devised on which the unidentified basidiomycete B 191039 produced high titers of alcohol oxidase in shake cultures. Another, fully synthetic medium was developed on which the production was nearly as good, but very slow. No cofactors were required to produce this flavine adenine dinucleotide-containing enzyme. The B 191039 organism underwent frequent mutations. The mutant forms were morphologically distinct from the parent strain and elaborated little or no alcohol oxidase. Several other basidiomycetes were shown to produce alcohol oxidase in submerged culture.
Fluorescent-Antibody Technique in Detection of Salmonellae in Animal Feed and Feed Ingredients
Authors: Laramore C. R. , Moritz C. W.
Published: December 2020

Comparative studies of fluorescent antibody procedure and a cultural method for the detection of
Salmonella
were made on 1,013 feed and feed-ingredient samples. The agreement between the two methods was 92.1%. There were more false positives (5.7%) than false negatives (2.2%). Of the 22 false negatives, 15 (68%) were obtained on meat meal. Of the total number of samples, 37% were meat meal. An additional study of 73 samples of meat meal indicated that correlation between methods was better than correlation between samples.
Effect of Vaccine, Route, and Schedule on Antibody Response of Rabbits to
Pasteurella tularensis
Authors: Nutter John E.
Published: December 2020

The response of the rabbit to viable or killed whole-cell
Pasteurella tularensis
vaccines was studied. The most practical preparation for the production of anti-
P. tularensis
antibodies was viable organisms of the live vaccine strain (LVS). The intravenous route of administration proved superior to either the subcutaneous or intradermal routes, and incorporation of LVS into Freund's adjuvants did not result in increased levels of antibody. Short-term hyperimmunization, three injections at weekly intervals, constituted the most efficient method for increasing levels of the antibodies.
Production of Thermostable Alkaline Proteases by Thermophilic
Streptomyces
Authors: Mizusawa Kiyoshi , Ichishima Eiji , Yoshida Fumihiko
Published: December 2020

Conditions for the production of thermostable proteases (alkaline proteinase and carboxypeptidase) by a thermophilic streptomycete (
Streptomyces rectus
var.
proteolyticus
) were investigated in 20-liter volumes. Proteinase production was affected by the concentration of defatted soybean powder, its optimum being 1.2% in medium containing 2.0% soluble starch. Relatively high concentration of phosphate (0.3 to 0.4% K
2
HPO
4
) was needed for the maximum enzyme production. A large inoculum size (5 to 10%) was favorable, but the inoculum age did not significantly influence the production. The yield increase of 20 to 30% was obtained by feeding of medium during fermentation. The optimal temperature for proteinase production was 50 C, at which the maximal rate of production was 66.2 proteinase units per ml per hr, whereas at 40 C it was 9.0. Production at 50 C reached the maximum within 12 to 16 hr. The optimal agitation rate was different for the production of proteinase and carboxypeptidase, 400 rev/min for the former and 500 rev/min for the latter. The optimal aeration for proteinase production was 20 to 30 liters/min at 400 rev/min, whereas carboxypeptidase production was not markedly affected by aeration rate. The possibility that carboxypeptidase production was correlated with the shear of mycelium was discussed.
Effects of Tween 80 and Freon 113 on Measles Virus
Authors: Parisius Wolf , Macmorine Hilda G.
Published: December 2020

Measles vaccines were prepared from the same virus fluids by inactivation with formaldehyde or by extraction with ether, ethyl acetate, or Freon 113 in the presence of Tween 80. Tests of antigenic potency, based on antibody levels in guinea pigs, showed that the formaldehyde-inactivated vaccines were more potent than the solvent-inactivated preparations and had the additional advantage of long shelf life. Residual Tween 80 in the solvent-extracted vaccines resulted in marked loss of immunogenic potency without significant loss of hemagglutinating activity. Neither extraction with organic solvents nor exhaustive dialysis efficiently removed Tween 80 from aqueous solutions.
Role of the Kidney in Staphylococcal Enterotoxemia
Authors: Staab Edward V. , Niederhuber John , Rhoda David A. , Faulkner Charles S. , Beisel William R.
Published: December 2020

Highly purified staphylococcal enterotoxin B (SEB) is known to accumulate rapidly within the kidneys of experimental animals. The present study was performed to determine whether the predominant renal localization of SEB was of fundamental pathophysiologic importance in the development of lethal shock after the intravenous administration of this toxin to monkeys. Eight bilaterally nephrectomized
Macaca mulatta
given 10 μg of SEB per kg survived for an average time period less than half that of nephrectomized control animals (P < 0.001). Their survival time, however, was similar to that of control, sham-nephrectomized monkeys given an equal amount of SEB. Thus, no evidence was obtained to suggest that the kidney converted purified SEB to a more potent toxin. The glomerular filtration and proximal tubule cell accumulation of SEB possibly occurred as a nonspecific consequence of its molecular size, and such localization within the kidney might have served to reduce the quantity of SEB reaching some other site of toxic activity. Similar pathological and clinical findings were demonstrated in monkeys from both experimental and control groups; these could not be ascribed to SEB alone.
Antagonistic Effect of Fatty Acids Against
Salmonella
in Meat and Bone Meal
Authors: Khan Mahmood , Katamay Michael
Published: December 2020

The purpose of this study was to determine whether fatty acids have an antagonistic effect on the growth and viability of
Salmonella
organisms. Thirty-two different lipid materials were used, utilizing a wide range of short and long free fatty acid chains expressed as per cent oleic acid.
In Vitro Antimicrobial Activity and Human Pharmacology of Cephalexin, a New Orally Absorbed Cephalosporin C Antibiotic
Authors: Thornhill Thomas S. , Levison Matthew E. , Johnson Warren D. , Kaye Donald
Published: December 2020

Concentrations of cephalexin (an orally absorbed derivative of cephalosporin C) in serum and urine were determined in normal volunteers and patients. The in vitro antibacterial activity was also studied. All strains of group A β-hemolytic streptococci and
Diplococcus pneumoniae
were inhibited by 3.1 μg/ml. Of the
Staphylococcus aureus
strains, 88% were inhibited by 6.3 μg/ml, and 12.5 μg/ml was inhibitory for all
S. aureus
, 80% of
Escherichia coli
, 72% of
Klebsiella-Aerobacter
, and 56% of
Proteus mirabilis
strains. About 90 to 96% of
E. coli, Klebsiella Aerobacter
, and
P. mirabilis
strains were inhibited by 25 μg of cephalexin per ml.
Pseudomonas
and indole-positive
Proteus
strains proved to be quite resistant to cephalexin. Cephalexin was well absorbed after oral administration. A peak serum concentration of cephalexin of at least 5 μg/ml was achieved in each volunteer with 250 and 500-mg doses. A mean peak serum concentration of 7.7 μg/ml was achieved with 250-mg doses; 12.3μg/ml was achieved with 500-mg doses of antibiotic. Food did not interfere with absorption. Probenecid enhanced both the peak serum concentration and the duration of antibiotic activity in the serum. Over 90% of the administered dose was excreted in the urine within 6 hr. The mean peak serum concentration of cephalexin after an oral dose of 500 mg was adequate to inhibit all group A streptococci,
D. pneumoniae
, and
S. aureus
, 85% of
E. coli
, and about 40 to 75% of
Klebsiella-Aerobacter
and
P. mirabilis
strains. Levels of cephalexin in urine were adequate to inhibit over 90% of
E. coli
, and
P. mirabilis
and 80 to 96% of
Klebsiella-Aerobacter
strains.
Density-Gradient and Chromatographic Fraction of Leptospiral Lipase
Authors: Berg Robert N. , Green Stanley S. , Goldberg Herbert S. , Blenden Donald C.
Published: December 2020

Fractionation of leptospiral lipase by CsCl density gradients and G-200 Sephadex chromatography yielded five active protein peaks. Two were obtained from the density gradients and three from G-200 Sephadex columns. Esterase activity of these fractions was demonstrated by electrophoretic examination. Several protein bands were visible when disc electrophoresis was performed on the respective fractions. Lipolytic and esterolytic activities were both present, and the overlapping of these activities was discussed.
Preservation of Primary Bovine Embryonic Kidney Cells with Dimethyl Sulfoxide
Authors: Lindsey Norma J. , Chow T. L.
Published: December 2020

Primary bovine embryonic kidney cells frozen with dimethyl sulfoxide can be recultured with satisfactory results.
Heat Resistance of
Salmonella
in Various Egg Products
Authors: Garibaldi J. A. , Straka R. P. , Ijichi K.
Published: December 2020

The heat-resistance characteristics of
Salmonella typhimurium
Tm-1, a reference strain in the stationary phase of growth, were determined at several temperatures in the major types of products produced by the egg industry. The time required to kill 90% of the population (D value) at a given temperature in specific egg products was as follows: at 60 C (140 F), D = 0.27 min for whole egg; D = 0.60 min for whole egg plus 10% sucrose; D = 1.0 min for fortified whole egg; D = 0.20 min for egg white (
p
H 7.3), stabilized with aluminum; D = 0.40 min for egg yolk; D = 4.0 min for egg yolk plus 10% sucrose; D = 5.1 min for egg yolk plus 10% NaCl; D = 1.0 min for scrambled egg mix; at 55 C (131 F), D = 0.55 min for egg white (
p
H 9.2); D = 1.2 min for egg white (
p
H 9.2) plus 10% sucrose. The average Z value (number of degrees, either centigrade or fahrenheit, for a thermal destruction time curve to traverse one logarithmic cycle) was 4.6 C (8.3 F) with a range from 4.2 to 5.3 C. Supplementation with 10% sucrose appeared to have a severalfold greater effect on the heat stabilization of egg white proteins than on
S. typhimurium
Tm-1. This information should be of value in the formulation of heat treatments to insure that all egg products be free of viable salmonellae.
Purification and Concentration of Influenza Types A and B by Chromatography on Calcium Phosphate
Authors: Lapidus M.
Published: December 2020

A rapid chromatographic method for the isolation of types A and B influenza virus from allantoic fluid was described. The adsorbent was prepared from calcium dihydrogen orthophosphate monohydrate [Ca(H
2
PO
4
)
2
�H
2
O] by alkali treatment. The addition of sodium trimetaphosphate to the influenza-infected allantoic fluid afforded a 67 to 100% viral recovery and a 26 to 43-fold increase in purity.
Biological Activity of Aflatoxin B
2a
Authors: Lillehoj E. B. , Ciegler A.
Published: December 2020

The toxicity of alfatoxin B
2a
(hydroxydihydro-aflatoxin B
1
) was studied in several biological systems. Aflatoxin B
2a
is the monohydroxylated derivative obtained from addition of water to the double bond of the terminal furan of B
1
. Examination of the sensitivity of a group of microorganisms to B
2a
demonstrated that the inhibitory spectrum was similar to aflatoxin B
1
. However, the toxicity of B
2a
was markedly lower than B
1
, as measured by the initiation of bile duct hyperplasia in ducklings. Binding of aflatoxin to deoxyribonucleic acid (DNA) was determined by measuring the hypochromicity produced by the nucleic acid at 363 nm and the capacity of increasing amounts of DNA to quench the fluorescence of the toxin was also used as a measure of the binding of toxin to nucleic acid. These tests showed that the DNA-binding capacity of B
2a
was lower than B
1
.
Accelerated Procedure for
Salmonella
Detection in Dried Foods and Feeds Involving Only Broth Cultures and Serological Reactions
Authors: Sperber W. H. , Deibel R. H.
Published: December 2020

A procedure has been developed in which
Salmonella
can be detected in dried foods and feeds within 50 hr. This includes preenrichment (18 hr), selective enrichment (24 hr), elective enrichment (6 to 8 hr), and serological testing (2 hr). The procedure is as sensitive as the more time-consuming, traditional (plating, biochemical, and serological) procedure which may require at least 4 to 5 days. The new procedure is rapid and accurate in comparison to traditional procedures. Moreover, it is simple and inexpensive to perform. As described, the procedure does not necessitate the isolation of pure cultures, but this step is performed easily if desired.
Incidence Study of Spores of
Clostridium botulinum
in Convenience Foods
Authors: Insalata N. F. , Witzeman S. J. , Fredericks G. J. , Sunga F. C. A.
Published: December 2020

The objective of this study was to gather data on the incidence of
Clostridium botulinum
spores in selected consumer-convenience food products. The incidence of spores of
C. botulinum
in 100 samples of each of four categories of commercially available convenience foods was determined. These categories included (i) “boil-in-the-bag” foods, (ii) vacuum-packed foods, (iii) pressurized foods, and (iv) dehydrated and freeze-dried foods. Of the 400 samples analyzed, one was found to contain the spores of
C. botulinum
. This occurred in vacuum-packed frank-furters and was identified as type B.
Standardized Procedure for Determination of Staphylocoagulase
Authors: Wegrzynowicz Z. , Jeljaszewicz J. , Lipinski B.
Published: December 2020

A simple standardized procedure for the determination of staphylocoagulase, based on thrombin clotting time measurement with euglobulin, has been developed. A standard euglobulin solution containing 0.25% of clottable protein, 0.01 M ε-aminocaproic acid, and 20 units of heparin per ml is employed. One unit of staphylocoagulase is defined as the amount of the enzyme which clots this standard euglobulin solution in 25 sec.
Markers Differentiating Type 3 Parainfluenza Virus Grown at 25 and 37 C
Authors: Frickey Paul H.
Published: December 2020

Serial passage of the 64-2389 strain of type 3 parainfluenza virus in cercopithecus monkey kidney tissue cultures at low temperatures resulted in the selection of a variant which had a higher efficiency of plaque formation at 25 C than the parent line grown at 37 C. The cold variant, unlike the parent strain, plaqued readily at 25 C, and at 37 C it produced significantly larger plaques. Virus titers of the cold variant in hamster lungs were significantly lower and this was probably caused by the stimulation of interferon by the cold variant during the early phase of the infection. The cold variant, like the virus grown at 37 C, also induced the synthesis of interferon late in the infection. Hamsters responded to the intranasal inoculation of each virus line by the development of hemagglutinating-inhibiting antibodies in the sera.
Microneutralization Test for Determination of Rhinovirus and Coxsackievirus A Antibody in Human Diploid Cells
Authors: Kriel Robert L. , Wulff Herta , Chin Tom D. Y.
Published: December 2020

A method for determination of serum-neutralizing antibody titers to rhinovirus type 16 and coxsackievirus type A-4 in human diploid cells (WI-38) grown in Microtiter plates is described. A good correlation was observed when comparing neutralization tests in WI-38 and other cells. The WI-38 Microtiter method is relatively simple and economical. It is suitable for those laboratories which are required to conduct large-scale serological evaluation of antibodies for rhinoviruses and coxsackie A viruses. This system also can be used for cytomegalovirus and varicella-zoster virus, which grow relatively slowly.
Paraformaldehyde for Surface Sterilization and Detoxification
Authors: Taylor Larry A. , Barbeito Manuel S. , Gremillion Gardner G.
Published: December 2020

Paraformaldehyde powder, depolymerized by heat, produced formaldehyde gas that was effective in sterilizing laboratory rooms, a mobile laboratory trailer, various surfaces, fiberglass filter medium, and specialized laboratory equipment. A sporulating and nonsporulating strain of bacteria, a virus, and a bacterial toxin were used as test agents. The dissemination procedures and equipment, the assay techniques, and the facilities and equipment sterilized were described.
Minicultures of Mammalian Cells in a New Plastic Plate
Authors: Fuccillo David A. , Catalano Louis W. , Moder Flora L. , Debus David A. , Sever John L.
Published: December 2020

A new disposable micro tissue culture plate was developed and tested for use in virological procedures. Miniature mammalian cell cultures (minicultures) were grown in these plates. Each plate contained 96 circular cultures in flat wells (7 mm in diameter). Replicate titrations of a number of viruses were performed in various tissues. Excellent reproducibility was demonstrated. Mean infectivity titers determined by miniculture methods were generally within 0.6 log
10
/ml of macro tube titrations. Standard tissue culture assay techniques such as hemadsorption, interference titration, and microneutralization were easily carried out with this method and were very reproducible. Development of this noncytotoxic disposable micro tissue culture plate now permits the routine performance of rapid, reliable, and reproducible tissue culture tests at a very significant reduction in cost and labor.
Identification of Group A Streptococci by Direct Fluorometry
Authors: Moody Max D. , Webb C. Douglas
Published: December 2020

A simple direct fluorometric method for rapid identification of group A streptococci is described. The method permits the detection of the organism in mixed cultures without the aid of a microscope and is amenable to automated processing of specimens. Experience with the indirect fluorometric method revealed that nontrypsinized cells from a 10-fold dilution of overnight broth cultures could be stained with uniform brilliance with fluorescent antibody (1:15 dilution) and that fluorescent antibody dissociated from such cells at 55 C for 20 min gave serologically specific fluorometric values. With this information, it was possible to develop a simpler fluorometric test which gave results comparable to those obtained by conventional cultural-precipitin grouping techniques. In the direct test described, cultures from throat swabs were incubated overnight, and cells from a 10-fold dilution were stained with specific fluorescent antibody (1:50 dilution) and then rinsed. The stained specimens were transferred to a continuous-filter paper strip (Whatman 3 MM) and read serially in a Turner 110 fluorometer with Corning 5840 and Wratten 2A filters in place. The reagents used required careful standardization and testing to assure that fluorometric readings above a specified value would be indicative of the presence of group A streptococci.
Thermostability of Rubella Hemagglutination-inhibiting Antibody
Authors: Phillips C. A. , O'Brien L.
Published: December 2020

The thermostability of serum rubella antibody is such that serum specimens may be shipped to clinical laboratories at ambient temperature.
Apparatus for Preparation of Bacterial Extracellular Enzymes
Authors: Millner Seymon N.
Published: December 2020

A method is described for the growth of bacteria within dialysis tubing to yield extracellular enzymes, or, possibly, other nondialyzable extracellular products, in concentrated form.
Microbiological and Pharmacological Behavior of 7-Chlorolincomycin
Authors: Meyers Burt R. , Kaplan Kenneth , Weinstein Louis
Published: December 2020

Replacement of the 7-(R) hydroxyl group of lincomycin by a 7-chloro-substituent produced a compound with greater in vitro activity than the parent. Laboratory studies of this compound showed it to be highly active against all of the following strains of gram-positive organisms examined, including penicillinase- and nonpenicillinase-producing staphylococci,
Diplococcus pneumoniae, Streptococcus viridans
and
Streptococcus pyogenes
. The enterococci, as well as all the gram-negative organisms tested, with the exception of some strains of
Haemophilus
, were uniformly insensitive to this agent. The activity of 7-chlorolincomycin was not affected by serum or inoculum size. Resistance developed in a slow stepwise pattern. Peak levels of approximately 2 μg/ml were achieved in the serum of volunteers after ingestion of 150 mg either in the fasting state or after a meal. No untoward effects were noted. The antibiotic appears to be of potential value in the treatment of infections due to gram-positive organisms, with the exception of enterococcus.
Statistical Approach to Evaluating the Method of Morgan and Vryonis for Enumerating
Treponema pallidum
Authors: Artley Charles W. , Clark John W.
Published: December 2020

The contributions of four components to the error in the microscopic enumeration of spirochetes (
Treponema pallidum
) by the method of Morgan and Vryonis were determined. Where N

s

= the number of slides counted, N

r

= the number of recounts of 50 fields per slide, N

p

= the number of pipettes used, and N

e

= the total number of counts of 50 fields made, the coefficient of variation is 2 times the square root of (17.5
2
/N

s

+ 18.6
2
/N

r

+ 14.8
2
/N

p

+ 6.1
2
/N

e

) with 95% confidence.
Detection of Group A Streptococci in Throat Swabs by Direct Fluorometry
Authors: Webb C. Douglas , Moody Max D.
Published: December 2020

A direct fluorometric test for the rapid detection of group A streptococci from throat swabs was compared with the microscopic fluorescent-antibody test. Formalinized throat swab cultures (490) were examined by the two methods, and the results agreed on 84% of the specimens. In another comparison, 15-hr broth cultures of 103 freshly taken throat swabs were tested by both methods. Of the specimens tested, 101 (98%) were either positive or negative by both methods. In all cases, the latter results correlated with the demonstration of presence or absence of group A streptococci in the specimens by cultural isolation and precipitin grouping tests. It may be feasible to use the direct fluorometric test in a diagnostic laboratory as described or possibly to adapt it for automatic processing of throat swab cultures.
Survival of Lyophilized
Bacillus popilliae
in Soil
Authors: Lingg A. J. , McMahon K. J.
Published: December 2020

Survival of lyophilized vegetative
Bacillus popilliae
in dry soil and in soil kept in atmospheres with different relative humidities (RH) was determined. Cells survived for at least 1 year when the RH was 22% or lower, but an RH of 33% or higher reduced viability. At 33% RH, no bacteria were recovered after 5 months of storage; at 42% or above, no bacteria were recovered after 1 month of storage.
Lomofungin, a New Antibiotic Produced by
Streptomyces lomondensis
sp. n
Authors: Johnson Leroy E. , Dietz Alma
Published: December 2020

Lomofungin is a new antimicrobial agent obtained from the culture broth of
Streptomyces lomondensis
sp. n. UC-5022. Lomofungin is an acidic, olive-yellow, crystalline compound which inhibits, in vitro, a variety of pathogenic fungi, yeasts, and gram-positive and gram-negative bacteria.
Ochratoxin A: Occurrence as Natural Contaminant of a Corn Sample
Authors: Shotwell Odette L. , Hesseltine C. W. , Goulden Marion L.
Published: December 2020

Ochratoxin A was detected as a natural contaminant for the first time. It was present in a corn sample.
Selective Medium for Growth of
Rhizobium
Authors: Graham P. H.
Published: December 2020

A new medium has been developed for selectively isolating strains of
Rhizobium
from soil.
Evaluation of a Method of Measuring Fermentation Rates and Net Growth of Rumen Microorganisms
Authors: el-Din Manal Zaki , el-Shazly K.
Published: December 2020

The method of el-Shazly and Hungate for measuring gas production in rumen contents was slightly modified and used throughout this investigation. The variation in the fermentation rates due to samples collected separately from a sheep fed on hay was less than 2%. When samples obtained through a stomach tube were compared with samples collected through the rumen fistula, the variation was about 3%. The rates of gas and acid production were approximately similar in samples obtained from the rumen at the same time when no sodium bicarbonate was added. During in vitro incubation of whole ruminal contents, there was a highly significant correlation between the net growth rate values (obtained by using fermentation capacity as an index) and the change in concentration of viable rumen bacteria or total ciliate protozoa.
Antiviral and Antitumor Antibiotics. XIV. Effects of Ascochlorin and Other Respiration Inhibitors on Multiplication of Newcastle Disease Virus in Cultured Cells
Authors: Takatsuki Akira , Tamura Gakuzo , Arima Kei
Published: December 2020

Antiviral activity on Newcastle disease virus was examined with some respiration inhibitors including ascochlorin, rotenone, antimycin A
3
, piericidin A, dicoumarol, 2, 4-dinitrophenol, pentachlorophenol, and fatty acids. Of the chemicals tested, ascochlorin and rotenone showed significant inhibitory effect on the viral growth in cultured cells as determined by the plate and tube assay methods. Dose response of ascochlorin and rotenone was observed in rate and final yield of hemagglutinin synthesis. Ratio of infectivity for hemagglutinin was nearly equal at any test concentrations of ascochlorin. Thus, the possibility of inhibition of virus maturation by the antibiotic was excluded. Ascochlorin had no activity on virus particles and on viral adsorption onto host cells.
Stabilities of Dried Suspensions of Influenza Virus Sealed in a Vacuum or Under Different Gases
Authors: Greiff Donald , Rightsel Wilton A.
Published: December 2020

Suspensions of purified influenza virus, dried to a 1.4% content of residual moisture by sublimation of ice in vacuo, were sealed in a vacuum or under different gases of high purity. The stabilities of the several preparations were determined by an accelerated storage test. Based on the times predicted for the dried preparations stored at different temperatures to lose 1 log of infectivity titer, the order of stabilities in relation to sealing in vacuum or under different gases was as follows: helium > hydrogen > vacuum > argon > nitrogen > oxygen > carbon dioxide.
Coagulase Production by Injured
Staphylococcus aureus
MF-31 During Recovery
Authors: Pariza M. W. , Iandolo J. J.
Published: December 2020

Suspensions of
Staphylococcus aureus
MF-31 injured by heat treatment at 54 C for 15 min produced coagulase during recovery in Trypticase Soy Broth. Coagulase also was produced by injured cells during recovery in a medium that did not support growth. Coagulase synthesis during recovery was independent of the molar strength of the buffer in which the cells were injured, the age of the cells, and the degree of injury. Return of salt tolerance and coagulase production required glucose, amino acids, and phosphate in the recovery medium. Vitamins stimulated coagulase production, but did not affect recovery. Although coagulase production was not necessary for repair of thermal injury to
S. aureus
MF-31, its detection was interpreted as an indicator of protein synthesis.
Microbial Hydrocarbon Co-oxidation. III. Isolation and Characterization of an α, α′-Dimethyl-
cis, cis-
Muconic Acid-producing Strain of
Nocardia corallina
Authors: Jamison V. W. , Raymond R. L. , Hudson J. O.
Published: December 2020

A soil isolate identified as a strain of
Nocardia corallina
accumulated α, α′-dimethyl-
cis, cis-
muconic acid under co-oxidation conditions employing
n
-hexadecane for growth and
p
-xylene as the co-oxidizable substrate.
N. corallina
V-49 was postulated to have two pathways for the oxidation of
p
-xylene. One pathway proceeds through
p
-benzyl alcohol,
p
-tolualdehyde, and
p
-toluic acid to 2, 3-dihydroxy-
p
-toluic acid, and the other pathway results in ortho ring cleavage of 3, 6-dimethylpyrocatechol and hence accumulation of α,α′-dimethyl-
cis, cis-
muconic acid.
Simple Method for Anesthetizing Small Animals for Intranasal Inoculations
Authors: Pindak Frank F. , Kendrick Jerry Z.
Published: December 2020

By administration of methoxyflurane, aerosolized with a stream of air or oxygen, groups of animals can be conveniently prepared for intranasal inoculations.
Relationship Between Amino Sugars and Meat Microbial Quality
Authors: Shelef Leora A. , Jay James M.
Published: December 2020

The amino sugar content of spoiling beef increased with the microbial count and appeared to be responsible for the increased hydration capacity of spoiled meats.
Effect of Pertussis Vaccination on the Sensitivty of Mice to Insulin, Bicarbonate, and CO
2
Authors: Lane A. G.
Published: December 2020

Prior pertussis vaccination increased the sensitivity of mice to intraperitoneal injections of insulin and of sodium bicarbonate, but it reduced their sensitivity to high levels of inhaled carbon dioxide.
Safe Procedure for Opening Evacuated Glass Ampoules Containing Dried Pathogens
Authors: Greiff Donald
Published: December 2020

A simple, safe, closed system for opening evacuated, sealed glass ampoules and removing dried pathogens is described.
In Vitro Antiviral Activity of Mycophenolic Acid and Its Reversal by Guanine-Type Compounds
Authors: Cline J. C. , Nelson Janet D. , Gerzon K. , Williams R. H. , Delong D. C.
Published: December 2020

With the agar diffusion test and BS-C-1 cells, mycophenolic acid was found to give a straight-line dose-response activity in inhibiting the cytopathic effects of vaccinia, herpes simplex, and measles viruses. Plaque tests have shown 100% reduction of virus plaques by mycophenolic acid over drug ranges of 10 to 50 μg/ml and virus input as high as 6,000 plaque-forming units (PFU) per flask. Back titration studies with measles virus inhibited by mycophenolic acid have indicated that extracellular virus titers were reduced by approximately 3 logs
10
and total virus was reduced by 1 log
10
. The agar diffusion test system lends itself readily to drug reversal studies. Mycophenolic acid incorporated into agar at 10 μg/ml gave 100% protection to virus-infected cells. Filter paper discs impregnated with selected chemical agents at concentrations of 1,000 μg/ml (20 μg per filter paper disc) were placed on the agar surface. Reversal of the antiviral activity of mycophenolic acid was indicated by virus breakthrough in those cells in close proximity to the filter paper disc. Chemicals showing the best reversal of the antiviral activity of mycophenolic acid were guanine, guanosine, guanylic acid, deoxyguanylic acid, and 2,6-diaminopurine. The reversal of antiviral activity was confirmed by titrations of virus produced with various amounts of both mycophenolic acid and guanine present and by isotope tracer methods with uptakes of labeled uridine, guanine, leucine, and thymidine in treated and nontreated, infected and noninfected cells as parameters. All antiviral effects of mycophenolic acid at 10 μg/ml could be reversed to the range shown by untreated controls by the addition of 10 μg/ml of those chemicals exhibiting reversal activity.
Modified Microbiological Assay for Rapid Estimation of Antibiotic Concentrations in Human Sera
Authors: Stroy S. Ann
Published: December 2020

Antibiotic concentrations in human sera were estimated in 5 to 6 hr by a modified microbiological assay. By using
Staphylococcus aureus
and
Streptococcus pyogenes
as the assay organisms, the seeded assay plates were preincubated for 2 to 6 hr and then were stored at 4 C until used for assay. Paper discs saturated with the specimen were placed on the preincubated assay plates with reference discs saturated with known concentrations of antibiotic. After 5 to 6 hr of incubation, zones of antibacterial activity were measured and compared with a standard curve for estimation of antibiotic concentration. Results from this rapid assay method compared favorably with those from the commonly used 24-hr assay.
Resistance of Spores of
Clostridium botulinum
33A to Combinations of Ultraviolet and Gamma Rays
Authors: Durban E. , Grecz N.
Published: December 2020

Spores of
Clostridium botulinum
33A exhibit a sigmoidal survival curve if subjected to gamma radiation. The present investigation was concerned with two questions: (i) what is the form of an ultraviolet (UV)-survival curve and (ii) what is the combined effect of UV- and gamma radiation? The UV-survival curve was found to be of sigmoidal type with a “shoulder” width of 675 ergs/mm
2
and a D
10
(exp) of 2,950 ergs/mm
2
. To test the combination effect, spores were subjected to UV doses of 225, 450, 675, and 900 ergs/mm
2
followed by a series of increasing doses of gamma rays from 200 to 2,000 krad in 200-krad steps. The gamma ray-survival curves showed that increasing UV pretreatment caused a gradual loss of the “Prodiginine” yielding straight line exponential survival curves after preirradiation with UV doses of 675 ergs/mm
2
and above. Simultaneously the D
10
value for gamma-ray irradiation was reduced, e.g. UV preirradiation with 900 ergs/mm
2
reduced the D
10
by 40%. This observation emphasizes the potential practical advantage of combining UV and gamma rays for sterilization of heat-sensitive commodities.
L-Asparaginase Production by
Erwinia aroideae
Authors: Peterson R. E. , Ciegler A.
Published: December 2020

Maximum yields of 1,250 IU (international unit)/g (dry weight of cells) of L-asparaginase were obtained in 8 hr from
Erwinia aroideae
NRRL B-138. Partial purification and concentration of the extracted L-asparaginase yielded a preparation with an activity of 275 IU/ml. Only one L-asparaginase was present as determined by electrophoresis, and the enzyme exhibited a
p
H optimum of 7.5 and a
K
m
of 3 × 10
-3
M.
Growth of
Staphylococcus aureus
MF 31 on the Top and Cut Surfaces of Southern Custard Pies
Authors: Preonas D. L. , Nelson A. I. , Ordal Z. John , Steinberg M. P. , Wei L. S.
Published: December 2020

A
Staphylococcus
strain was inoculated on the top and cut surfaces of freshly baked Southern custard pies which were then packaged in a pasteboard carton and held at 30 C. Daily plate counts of surface sections 0.3 inch (0.76 cm) in thickness were made. The top surface inoculum showed a 24-hr lag time. This was due to the protective action of a top cakelike layer as shown by homogenization of the mix and coating of the surface. Substitution of all sweeteners with dextrose completely inhibited growth on the top surface. Further addition of dextrose to lower water activity (Aw) to 0.9 prevented growth on the cut surface as well, but such pies were organoleptically unacceptable. Growth on the top surface could also be prevented by 80 μg of undissociated sorbic acid per g in combination with 100 μg of undissociated propionic acid per g in the baked pie. Growth on the cakelike top surface was always retarded longer than on the cut surface provided the packaging allowed evaporation of surface moisture. Reducing the Aw of a different type of cream pie to 0.907 prevented top surface growth. It was concluded that baked cream pies with a cakelike top layer could be marketed with a “refrigerate after opening” label, provided the package maintains the moisture gradient caused by the surface skin and either a combination of 80 μg of undissociated sorbic acid per g and 100 μg undissociated propionic acid per g is present in the baked pie or the Aw of the baked pie is 0.920 or lower.
Identification of Human Strains of
Actinomyces viscosus
Authors: Gerencser Mary A. , Slack John M.
Published: December 2020

Catalase-positive actinomycetes which closely resemble the “hamster organism” described by Howell have been isolated from dental calculus and other human sources. These cultures could not be distinguished from the hamster strains on the basis of morphology, oxygen requirements, biochemical reactions, or cell wall composition. These human isolates have been classified with the hamster strains as
Actinomyces viscosus
. The strains from hamster and human sources fell into two serotypes. Serotype 1 contains the hamster strains plus one strain of unknown origin, whereas serotype 2 contains all of the human strains.
Medical Applications of Dust-free Rooms. III. Use in an Animal Care Laboratory
Authors: McGarrity Gerard J. , Coriell Lewis L. , Schaedler Russell W. , Mandle Robert J. , Greene Arthur E.
Published: December 2020

Bacterial air sampling in an animal care laboratory showed that dense aerosols are generated during cage changing and cage cleaning. Reyniers and Andersen sampling showed that the airborne bacteria numbered 50 to 200 colony-forming units (CFU)/ft
3
of air. Of the viable particles collected by Andersen samplers, 78.5% were larger than 5.5 μm. A low velocity laminar air flow system composed of high-efficiency particulate air (HEPA) filters and a ceiling distribution system maintained the number of airborne viable particles at low levels, generally less than 2 CFU/ft
3
. Vertical air flow of 15 ft/min significantly reduced the rate of airborne infection by a strain of
Proteus mirabilis
. Other factors shown to influence airborne infection included type of cage utilized, the use of bedding, the distance between cages, and the number of animals per cage.
Biological Evaluation of Carpeting
Authors: Anderson Roger L.
Published: December 2020

Studies of microbial contamination were carried out on a carpet strip (acrilan) installed in a laboratory corridor and on two carpet strips (acrilan and wool) installed in two rooms in a pediatric hospital. A sampling procedure of randomly removing 8-mm plugs from the carpets was used for subsequent enumeration and identification of contaminating microorganisms. Microbial counts increased with time, reached a “plateau” at about 4 weeks, and appeared to be related to the amount of activity present in the carpeted area. Vacuuming of carpets showed only a slight reduction in the number of recoverable microorganisms. Qualitative studies on a strip of acrilan carpet installed in a hospital room indicated that
Staphylococcus epidermidis
and gram-positive nonsporeforming rods were the predominating microorganisms. Coagulase-positive
S. aureus
organisms were isolated during every sampling period, and gram-negative rods were also regularly isolated. Most nitrate-reducing gram-negative rods belonged to the
Enterobacter
and
Escherichia
groups. Survival studies conducted on carpet strips after hospital installation showed relatively constant levels of contamination for about 6 weeks, followed by a gradual reduction in numbers; coagulase-positive
S. aureus
were found for 35 days, whereas the proportions of most organisms remained relatively constant with time.