bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Oxygen-Supply Rates on Growth of
Escherichia coli
Authors: McDaniel L. E. , Bailey E. G. , Zimmerli A.
Published: December 2020

The effect of oxygen-supply rates on bacterial growth was studied in commercially available unbaffled and baffled flasks with the use of
Escherichia coli
in a synthetic medium as a test system. The amount of growth obtained depended on the oxygen-supply rate. Based on oxygen-absorption rates (OAR) measured by the rate of sulfite oxidation, equal OAR values in different types of flasks did not give equal amounts of growth. However, growth was essentially equal at the equal sulfite-oxidation rates when these were determined in the presence of killed whole cultures. Specific growth rates were reduced only at oxygen-supply rates much lower than those at which the total amount of growth was reduced. For the physical set-up used in this work and with the biological system employed, Bellco 598 flasks and flasks fitted with Biotech stainless-steel baffles gave satisfactory results at workable broth volumes; unbaffled and Bellco 600 flasks did not.
Fate of
Staphylococcus aureus
in Bruised Tissue
Authors: Hamdy M. K. , Barton N. D.
Published: December 2020

This investigation was initiated to determine the fate and behavior of a virulent marker strain of
Staphylococcus aureus
(MS) injected intramuscularly into both control and traumatized tissues. Control tissues appeared to possess a clearing mechanism highly active against this organism, whereas bruised tissues stimulated and supported its growth. This stimulation may be due to the presence of extrastromal hemoglobin in the bruised areas. By use of the disc-sensitivity procedure, extrastromal hemoglobin was found to enhance the growth of
S. aureus
(MS) and this stimulation was linearly dependent on concentration in the range of 0.002 to 0.008 μmole per disc. Physical and physiological factors affecting the fate of staphylococci in poultry tissues were studied. The results showed that the number of viable cells of
S. aureus
(MS) in the initial inoculum exerted little effect on the survival activity patterns of this organism in the traumatized tissues. Control tissues, however, only became infected when a suspension containing 1.34 × 10
9
cells of the marker strain was injected. Regardless of the concentration of cells of this test culture inoculated into bruised areas, the staphylococci did not increase in number above a log of 8.5 organisms per gram of tissue. The extent of both tissue damage and accumulation of blood and fluid seemed to play an important role in the fate of staphylococci in experimentally induced infection. A correlation was noted between the severity of the bruise and the rate of growth and multiplication of virulent staphylococci in the tissue. The rate of growth showed a 100-fold increase in 1 day in the severe bruise, in 2 days in the medium bruise, and in 3 days in the superficial bruise. Time-course studies revealed that virulent
S. aureus
(MS) was able to persist in bruised tissue for long periods of time (18 days) even in the absence of noticeable infection. Therefore, it is believed that bruised tissue is a source of contamination to other birds and a health hazard to man.
Application of a Microtechnique to the Agglutination Test for Leptospiral Antibodies
Authors: Galton Mildred M. , Sulzer Catherine R. , Rosa C. A. Santa , Fields Michael J.
Published: December 2020

A microtechnique has been developed and adapted successfully to the microscopic agglutination test with live antigens for detection of leptospiral antibodies. Simultaneous titrations were performed by the conventional microscopic agglutination test and the microtechnique. When the microtechnique was used to screen 50 unknown leptospiral strains with a battery of hyperimmune sera, 98% agreement was obtained with the conventional procedure. Comparative data on 635 tests on these 50 cultures established the reliability of the microtechnique. Results with the two tests on 46 human sera revealed 93% agreement in the detection of leptospiral antibodies. The validity and reliability of the microtechnique obtained in these comparative studies suggests that it can be used as a valuable screening procedure for the microscopic agglutination test for preliminary cross agglutination studies on unknown strains and for the detection of leptospiral antibodies in human and animal sera.
Chemostatic Concentrated Cultures of Heteroploid Mammalian Cell Suspensions in Dialyzing Fermentors
Authors: Gori Gio B.
Published: December 2020

Concentrated chemostatic cultures of HeLa S3-1, KB, and HEp # 2 cells have been grown in a dialysis fermentor. Stationary cell concentrations of approximately 1.2 × 10
6
cells per ml have been produced at rates of 15 × 10
-3
to 20 × 10
-3
cells per hour for as long as 40 days. The dialysis fermentor appears to be useful in controlling the effects of nutrients on the growth rate of the cultures. Theoretical considerations are offered.
Neisseria gonorrhoeae
Identification in Direct Smears by a Fluorescent Antibody-Counterstain Method
Authors: White Lendell A. , Kellogg Douglas S.
Published: December 2020

Direct smears from female patients have been considered unreliable for the detection of
Neisseria gonorrhoeae
by fluorescent-antibody (FA) methods because of inadequate background contrast of the fluorescent-stained smears and a scarcity of organisms on the smear. Evans blue dye employed as a counterstain eliminated the nonspecific background staining and increased the reliability of the direct FA procedure. Direct smears demonstrating positive fluorescence were obtained from 86% of a group of culturally positive named female contacts. The FA-counterstain technique is as sensitive as the presently recommended cultural procedures.
Effect of Diet on the Activity of Several Enzymes in Extracts of Rumen Microorganisms
Authors: Baldwin R. L. , Palmquist D. L.
Published: December 2020

The use of enzymatic techniques to characterize rumen metabolism was investigated. Assays were developed to estimate the activities of 14 enzymes in cell-free extracts of microorganisms collected from rumen contents of cows fed two diets, selected to produce widely different proportions of fermentation end products. The results reflected the differences between the two diets in metabolic potential, fermentation patterns, and microbial populations. The differences between the diets in the relative activities of succinic dehydrogenase and fumaric reductase, for example, indicated a shift in the microbial population favoring organisms of the
Viellonella alcalescens
type on the concentrate diet. The data presented indicate that, if employed carefully, enzymatic criteria can be utilized effectively in studies of rumen metabolism.
Bacteria Responsible for Mucilage-Layer Decomposition in Kona Coffee Cherries
Authors: Frank Hilmer A. , Lum Norma A. , Cruz Amy S. Dela
Published: December 2020

The predominant microbial flora present during decomposition of the mucilage layer of Kona coffee cherries were gram-negative bacteria which fermented lactose rapidly. Cultures isolated from coffee cherries under-going fermentation included species of
Erwinia, Paracolobactrum
, and
Escherichia
. Unblemished cherry surfaces and coffee plantation soil also had a microflora containing a high proportion of bacteria belonging to these three genera. Of 168 isolates tested, the 44 strains capable of demucilaging depulped coffee cherries were all members of
Erwinia dissolvens
. Supernatant growth medium liquids, after removal of
E. dissolvens
cells, actively decomposed the mucilage layer of depulped cherries.
Production of Aflatoxins in Submerged Culture
Authors: Mateles R. I. , Adye J. C.
Published: December 2020

Aflatoxins can be produced on a synthetic medium in submerged culture. Glucose, sucrose, or fructose are the preferred carbon sources, and Casamino Acids are the preferred nitrogen source. Ammonia is almost as good a nitrogen source. Zinc is required at levels of at least 0.4 mg per liter. Concentrations of aflatoxin of 60 to 80 mg per liter (as determined by optical-density measurements of a chloroform extract of the unfiltered broth) can readily be obtained in indented shake flasks; somewhat lower yields were obtained in 5-liter fermentors.
Comparative In Vitro Activities of Lysostaphin and Other Antistaphylococcal Antibiotics on Clinical Isolates of
Staphylococcus aureus
Authors: Harrison Edward F. , Cropp C. Bruce
Published: December 2020

The in vitro activity of lysostaphin against clinical isolates of
Staphylococcus aureus
was determined by conventional tube-dilution methods. For comparison, minimal inhibitory concentration (MIC) values were also determined for penicillin G, ampicillin, methicillin, ristocetin, vancomycin, and erythromycin. Phage type and penicillinase and coagulase production were determined for each isolate. The MIC values for lysostaphin ranged from <0.047 to 12.5 μg/ml; 96% of the penicillinase-positive strains were inhibited by 1.56 μg/ml of lysostaphin, whereas 3.12 μg/ml of vancomycin and methicillin were required to attain the same degree of inhibition.
Use of
Penicillium chrysogenum
Mycelium as Animal Food
Authors: Pathak S. G. , Seshadri R.
Published: December 2020

The mycelial cake of
Penicillium chrysogenum
, when dried and specially processed, has been found to serve as a source of protein in place of soybean meal in the diet of experimental mice. Animals were fed a control diet first, and an increase in weight proved the formulation to be satisfactory. The changeover from the control to the experimental diet was sudden, and initially caused a decrease in the weight of the experimental mice. However, at the end of a 29-day period, the experimental mice showed increases in weight comparable to those of the control animals. This supports the view that dried mycelium can be substituted as a protein source for soybean meal, provided it is made more palatable and less disagreeable in odor.
Physical Properties and Chemical Composition of β-Glucans from Fleshy Fungi
Authors: Wallen L. L. , Rhodes R. A. , Shulke H. Russell
Published: December 2020

Physical properties and chemical structure of two related polysaccharides produced fermentatively by
Plectania occidentalis
NRRL 3137 and by
Helotium
sp. NRRL 3129 were studied. Both polymers were readily recovered as amorphous gels by precipitation from culture liquors with two parts of ethyl alcohol or methanol. Dried polymeric material was redissolved in water with agitation to give uniform aqueous solutions up to about 1.5% by weight. The polymers were similar in physical properties but possessed different chemical structures. The viscosity of aqueous solutions of each polymer varied from about 50 centipoises at 0.1% to approximately 2,200 centipoises at 1.4% concentrations by weight. Highly viscous solutions at concentrations of 1% or greater behaved like thixotropic gels. Mono-, di-, and trivalent salts, except borate, did not affect viscosity of either polymer. The viscosities were slightly increased by the addition of borate. Autoclaving did not alter the physical properties of neutral polymer solutions. The polymers were stable in acid or alkaline solutions at moderate temperatures but degraded under extremes of
p
H at 70 C or above. Each polymer had a specific rotation of +20° in aqueous dimethylformamide (1:1). The results of acid hydrolysis and periodate oxidation, in conjunction with paper and gas chromatography, indicate that both polymers are branched glucans containing appreciable amounts of β-1,3 linkages.
Fate of Bacteria in Chicken Meat During Freeze-Dehydration, Rehydration, and Storage
Authors: May K. N. , Kelly L. E.
Published: December 2020

Total plate counts were determined on boneless cooked, cubed chicken meat obtained from a commercial processor. Survival of the natural flora was determined after the meat was freeze-dehydrated and rehydrated at room temperature for 30 min and 50, 85, and 100 C for 10 min. Total counts of bacteria in the rehydrated samples were determined during storage of the meat at 4, 22, and 37 C until spoilage odor was detectable. Meat samples were inoculated with
Staphylococcus aureus
, then dried, rehydrated, and stored at the same temperatures. Numbers of surviving organisms in the inoculated samples were determined with use of both selective and nonselective media. Representative genera surviving the various rehydration treatments were determined. Approximately 32% of the bacteria in the meat survived during dehydration and rehydration at room temperature. Many numbers and types of vegetative bacteria also survived rehydration at 50 C. When meat was rehydrated at 85 or 100 C, the initial count was less than one per gram. The only organisms isolated from samples rehydrated at 85 or 100 C were of the genus
Bacillus. S. aureus
in inoculated samples survived dehydration and rehydration at 60 C. Storage of all rehydrated samples at 4 C gave a good shelf life (18 or more days). The study indicates that freeze-dehydrated meat should be produced with adequate microbiological control and that such meat should be rehydrated in very hot water.
Second Survey of Market Poultry for
Salmonella
Infection
Authors: Sadler W. W. , Corstvet R. E.
Published: December 2020

On 34 days over a period of 30 months, samplings were made of randomly selected birds slaughtered in randomly chosen processing plants. Methods were designed so that
Salmonella
and paracolon bacteria isolated were indigenous to the intestinal tract of the selected bird. Incidence rates were 5.25% for turkeys, 0.54% for chicken hens, and 1.05% for chicken fryers. Infected birds, providing the potential for contamination, were processed on 58% (turkeys), 25% (chicken hens), and 43% (chicken fryers) of the days. Combined data from the present and previous surveys represent a total of 9,851 carcasses sampled on 94 separate days over a 4.5-year period; these data provide a more accurate analysis of incidence rates and days that positive birds were being slaughtered. For turkeys, chicken hens, and chicken fryers, incidence rates were 4.16, 0.65, and 1.42%, respectively, and days positive were 56, 14, and 32%.
Ultracentrifugation in the Concentration and Detection of Enteroviruses
Authors: Cliver Dean O. , Yeatman John
Published: December 2020

Ultracentrifugation has been evaluated as a method of concentrating enteroviruses from suspensions whose initial titers ranged from 1.7 × 10
8
to 1.6 × 10
-2
plaque-forming units (PFU) per ml. A technique employing a “trap” of 0.1 ml of 2% gelatin solution at the point at which the pellet forms in tubes for the number 30 and number 50 rotors of the Spinco model L preparative ultracentrifuge has been tested and found to have a number of advantages. Qualitative studies have been performed to determine the sensitivity of the ultracentrifuge technique in detecting the presence of enteroviruses in very dilute suspensions. There was found to be at least a 50% probability of detecting virus present initially at levels as low as 0.12 PFU per ml by means of the number 50 rotor. The input level for similar results with the number 30 rotor was found to be 0.025 PFU per ml.
Comparison of the Elution and Absorption of Picornaviruses by Cotton and Calcium Alginate Wool Swabs
Authors: Phillips C. Alan , Grim Catherine A.
Published: December 2020

The recovery of picornaviruses by cotton and calcium alginate wool swabs was studied by use of prototype strains of poliovirus 1, echovirus 1, coxsackievirus A9, and rhinovirus 16/60. No significant differences in recovery of viruses by the two types of swabs could be demonstrated. It is suggested that use of cotton swabs in the virus laboratory be continued, since wool swabs may favor the recovery of undesirable bacterial contaminants. Adsorption of viruses by cotton and wool swabs was similar from virus-buffer mixtures at
p
H 4.0, 7.0, and 8.0 at 24 and 37 C. Elution of virus from cotton and wool swabs was also studied. There was no significant difference in the amount of virus eluted at
p
H 5.5, 7.1, or 8.4.
Diversifications in the Tube Dilution Test for Antibiotic Sensitivity of Microorganisms
Authors: Branch Arnold , Starkey D. H. , Power Edna E.
Published: December 2020

The tube dilution method of performing antibiotic sensitivity tests is commonly employed as an accurate method for defining the minimal inhibitory concentration in relation to pathogenic organisms. It is also used as a reference for comparing minimal inhibitory concentrations with the size of the zone of inhibition in the agar diffusion test. Although surveys have shown that there is no standardized method and technique of performing the tube dilution test, it is generally assumed that all of the diversified methods will yield the same results and interpretations. With the assistance of five experts, seven different tube dilution methods were compared; 16 antibiotics, and three organisms for each antibiotic, were used. The conclusions drawn are that, although the accuracy of a single method within its own confines is acknowledged, the minimal inhibitory concentrations and interpretations cannot be interpolated from one laboratory to another where a different technique is employed. The results are frequently discrepant. It is suggested that a uniform method be developed and promulgated for general use.
Nature and Role of Bacterial Contaminants in Mass Cultures of Thermophilic
Chlorella pyrenoidosa
Authors: Blasco Richard J.
Published: December 2020

A study was made of bacterial contaminants isolated from an algal mass-culture unit. The study was performed specifically to determine the dependence of the size of bacterial population on algal density and the nature of any association of the contaminants with the algal cell. Growth of the bacterial contaminants on standard medium was also investigated. An estimate was made of the O
2
uptake of the bacterial population under normal operating conditions of the algal massculture system. Viable numbers of bacteria tended to increase with increased algal density. Bacteria were found imbedded in the surface of algal cells when the cultures of algae were characterized by subnormal rates of growth and photosynthetic gas exchange. Bacterial isolates failed to grow in standard medium alone, thus implying a dependency of bacterial growth on material(s) produced by the algae. A slight inhibitory effect on algal growth was noted in the case of two of three of the bacterial isolates. Manometric studies demonstrated that the bacterial population normally found in the algal cultures did not appreciably effect total gas exchange.
Thermal Destruction Kinetics of a Lactic Streptococcal Bacteriophage
Authors: Daoust Donald R. , El-Bisi Hamed M. , Litsky Warren
Published: December 2020

The aim of the study was to elucidate the kinetics of thermal destruction of a lactic streptococcal bacteriophage, and to determine the effect of varied propagation and heating conditions on its thermoresistance. The propagation medium and temperature affect the degree of thermostability of the phage produced; higher incubation temperature enhances thermostability. The composition and reaction of the heating menstruum are also of significance. Phage thermoresistance increased significantly with the phosphate and whey levels. The effect of various minerals was difficult to resolve, mainly because of the bimodal nature of the survival curve. Thermoresistance was highest at
p
H 6, intermediate at
p
H 7, and lowest at
p
H 8. The kinetics of inactivation of this phage deviated from those of a first-order reaction. Consequently, a special treatment of the data was required in order to compute the various thermodynamic parameters that define the reaction. The high positive values of Q
10
, energy of inactivation, and entropy appear to indict protein denaturation as the cause of phage destruction.
Destruction of Various Kinds of Mycobacteria in Milk by Pasteurization
Authors: Harrington Rube , Karlson Alfred G.
Published: December 2020

Various strains of unclassified mycobacteria,
Mycobacterium tuberculosis
(including H37Rv strains),
M. bovis, M. avium, M. fortuitum
, and bacille Calmette-Guerin, were exposed to the temperature and time of pasteurization in skim milk in test tubes. Of the 195 strains tested, there were a few surviving colonies among 6 of 33 skotochromogens, 1 of 26 photochromogens, 10 of 79 nonchromogens, and 1 of 9 rapid growers. Subcultures of the surviving colonies failed to resist the pasteurization tests on subsequent trials.
Factors Affecting the Development of
Clostridium botulinum
in Whole Milk
Authors: Kaufmann O. W. , Marshall R. S.
Published: December 2020

This study was undertaken to determine the effect of the sterilization process and the age of the medium at the time of inoculation on the development of
Clostridium botulinum
type 62A. Whole milk was autoclaved at 121 C for 18 or 30 min and inoculated with
C. botulinum
so as to contain 2,000 to 5,000 spores per milliliter. No effort was made to remove dissolved oxygen or to reduce the oxidation-reduction (O/R) potential of the medium by adding sodium thioglycolate. A 3- and a 5-day-old medium were used to study the influence of aging. Eh determinations were made periodically on inoculated and uninoculated samples. Culture development was followed by use of an oval tube counting procedure. The technique used to sterilize the milk influenced the initial O/R potential as well as the autoreductive capacity of the medium. The initial Eh of whole milk sterilized in 500-ml volumes for 18 min was 234 mv. In milk sterilized for 30 min it was 192 mv. The lag phase was 7 days in the former and 5 days in the latter. The exponential growth phases were similar. Autoreduction occurred in sterilized milk. The Eh of uninoculated milk sterilized for 18 min decreased 45 mv in 6 days. In milk sterilized for 30 min the decrease was 63 mv. In milk inoculated 3 or 5 days after sterilization the lag phase was shorter than when the medium was inoculated within 2 hr after autoclaving, regardless of the sterilization procedure employed. The autoreductive property of sterilized whole milk plays a major role in the development of
C. botulinum
type 62A.
Gas Exchange of Algae
Authors: Ammann Elizabeth C. B. , Lynch Victoria H.
Published: December 2020

Continuously growing cultures of
Chlorella pyrenoidosa
Starr 252, operating at constant density and under constant environmental conditions, produced uniform photosynthetic quotient (PQ = CO
2
/O
2
) and O
2
values during 6 months of observations. The PQ for the entire study was 0.90 ± 0.024. The PQ remained constant over a threefold light-intensity change and a threefold change in O
2
production (0.90 ± 0.019). At low light intensities, when the rate of respiration approached the rate of photosynthesis, the PQ became extremely variable. Six lamps of widely different spectral-energy distribution produced no significant change in the PQ (0.90 ± 0.025). Oxygen production was directly related to the number of quanta available, irrespective of spectral-energy distribution. Such dependability in producing uniform PQ and O
2
values warrants a consideration of algae to maintain a constant gas environment for submarine or spaceship use.
Characterization of Certain Gram-Negative Bacteria from Surface Waters
Authors: Hoadley A. W. , McCoy Elizabeth
Published: December 2020

Cultures of gram-negative bacteria with oxidative glucose metabolism were isolated from surface waters by a highly selective technique, and were classified into 11 types. The predominant type, making up about 50% of the isolated cultures, was cytochrome oxidase-positive, produced fluorescent pigment, and failed to grow at 37 C. A similar type, which differed in being cytochrome oxidase-negative, constituted about 10% of the isolates. Both types of bacteria probably were composed of more than one species. A third type, composed of purple-pigmented pseudomonads, made up approximately 30% of the isolated cultures, and probably represented the predominant species. Other bacterial types isolated constituted less than 10% of the cultures examined.
Effect of Diet and Strain Difference on the Virulence of
Staphylococcus aureus
for Mice
Authors: Nutini Leo G. , Berberich Norbert J.
Published: December 2020

Years of intensive investigations in our laboratories on staphylococcal infections in mice have indicated a gradual decrease in the virulence of
Staphylococcus aureus
for this animal, particularly the strain we were using, the random-bred BT mouse. The present investigations, based on changes in diet and strain differences in mice, were undertaken in an attempt to improve susceptibility of our stock strain, on the one hand, and to determine whether susceptibility was influenced by genetic strain differences, on the other. In the first series of experiments, littermate mice of the BT strain were placed on different diets: one group received a commercial diet; the other, a basic diet previously established in our laboratories as adequate for growth requirements of the animals. An increase in the susceptibility of the animals to staphylococcal infection was noted in the mice receiving the basic diet. In the second series of investigations, three other strains of mice (the Swiss albino, the C3H/HeJ, and the C57B1) previously not used by our laboratories in staphylococcal experiments were studied for staphylococcal susceptibility. These experiments revealed that all of these strains of mice were highly susceptible to the infection, even though they were maintained on a commercial diet.
Vitamin K
5
as a Fungistatic Agent
Authors: Merrifield Larry S. , Yang H. Y.
Published: December 2020

The effectiveness of vitamin K
5
in controlling the growth of different molds at varying
p
H levels in a culture medium, in tomato juice, and in several berry purees was studied. The molds studied were
Aspergillus, Botrytis, Hormodendrum, Mucor
, and
Penicillium
. The results showed that vitamin K
5
was effective as a fungistatic agent at concentrations ranging from 0.006 to 0.02%.
Some Surface-Active Agents and Their Virucidal Effect on Foot-and-Mouth Disease Virus
Authors: Fellowes O. N.
Published: December 2020

Selected cationic and anionic surface-active compounds were tested to determine their virucidal effect on the foot-and-mouth disease virus, type O, strain M11, propagated in primary calf kidney cells. The chemical inactivation of the virus was tested with 0.5, 1.0, 2.0, and 5.0% concentrations of the selected compounds. Virus controls with
p
H adjusted to cover the expected range of the mixtures of the chemicals and virus were also tested. The absence of virus from the mixtures of chemical and virus after reaction at 28 C for 2 hr was assayed by inoculating suckling mice with the mixtures. One cationic compound, alkyl methyl isoquinilinium chloride, showed considerable antiviral activity due largely to
p
H effect. The use of the surface-active agents investigated in this study, in the presence of organic material, would not be recommended as virucides.
Bacteriophage Types and Antibiotic Sensitivity of Staphylococci from Bovine Milk and Human Nares
Authors: Jones R. H. , Bennett F. W.
Published: December 2020

The number, phage types, and antibiotic sensitivity of coagulase-positive staphylococci from grade A raw milk samples produced on 40 farms in the Athens, Ga., milkshed were determined. Counts of mannitol-positive staphylococci in milk ranged from 100 to 3,580 per milliliter, with an arithmetic mean of 1,047. Examination of the nares of 48 dairymen on 34 of the farms also revealed that 13 (27%) were carriers of coagulase-positive staphylococci. Isolates from milk (412) and from nares (39) were tested against the Coles, Seto-Wilson, and International phage sets and 87, 68, and 56%, respectively, proved typable. Nine isolates were not typable. Each of the 33 phages used lysed one or more of the isolates. Staphylococcal phage types per milk sample ranged from 0 to 5, 0 to 7, and 0 to 8, with arithmetic means of 1.9, 2.3, and 2.3, respectively. Of the 13 narial carriers, 7 harbored staphylococci of one or more of the same phage types as those isolated from the milk at the respective farms. Randomly selected isolates were tested against high and low concentrations of 12 common antibiotics. All were either moderately sensitive or resistant to polymixin B. Over 30% were moderately sensitive or resistant to dihydrostreptomycin and penicillin individually. With but few exceptions, all isolates were sensitive to chlortetracycline, bacitracin, carbomycin, chloramphenicol, erythromycin, neomycin, novobiocin, oxytetracycline, and tetracycline individually.
Radiation Injury of
Clostridium botulinum
Spores in Cured Meat
Authors: Greenberg Richard A. , Bladel B. O. , Zingelmann W. J.
Published: December 2020

Cans of chopped ham, inoculated with spores of
Clostridium botulinum
strains 33A and 41B at levels of 2,500 and 250 per gram, were subjected to an enzyme-inactivating heat treatment and irradiation with 0.5, 1.5, 2.5, or 3.5 Mrad of Co
60
. A portion of the pack was not irradiated, and received a commercial thermal process (F
0
= 0.2). Viable spores were enumerated after treatment and after 6 months of incubation at 30 to 37.7 C. Toxic spoilage occurred at 0 and 0.5, but not at 1.5, 2.5, or 3.5 Mrad. More spoilage and toxin formation occurred in the product irradiated at 0.5 Mrad than in identical product receiving no radiation treatment. Confirmed botulinal spores were isolated from all of the radiation variables of 2,500 per gram-inoculated product and from all but the 3.5 Mrad low-inoculum cans. However, neither growth nor toxin was observed in unspoiled product. The “injury” phenomenon previously described in thermally processed cured meats (survival of botulinal spores without capacity for multiplication or toxigenesis) apparently occurs also in irradiated cured meats.
Effects of Animal Alimentary Passage on the Heat Resistance of
Clostridium perfringens
Authors: Canada James C. , Strong Dorothy H.
Published: December 2020

The resistance to heat, as measured by
D
values and phantom thermal death time curves, was observed to increase for one of three strains of
Clostridium perfringens
type A subsequent to animal passage. Animal passage was accomplished by the force-feeding of germ-free mice with bacterial suspensions of the organism, followed by the force-feeding of additional gnotobiotic mice with the contaminated feces. For the one strain in which an increase in heat resistance was noted, the result could not be attributed to mouse feces per se, since the presence of sterile germ-free mouse feces in a suspending medium did not protect
C. perfringens
spores from elevated temperature destruction.
Production of Proteinase on Noncarbohydrate Carbon Sources by
Pseudomonas aeruginosa
Authors: Morihara Kazuyuki
Published: December 2020

Proteinase production by
Pseudomonas aeruginosa
was studied in medium containing noncarbohydrate materials, especially various hydrocarbons, as the sole carbon source. On heavy oil, kerosene,
n
-paraffinic hydrocarbon of C
12
, C
14
, or C
16
, and propylene glycol, the bacteria grew well and high protinase production was observed. However, production on paraffinic hydrocarbon differed remarkably with strains of varied origins. The elastase-positive strain, IFO 3455, showed abundant growth and high proteinase production on medium containing a paraffin of C
12
, C
14
, or C
16
, whereas the elastase-negative strain, IFO 3080, showed little growth on the same medium. Neither elastase-positive nor elastase-negative strains, however, utilized
n
-paraffins of C
5
to C
10
, or various aromatic hydrocarbons such as benzene, naphthalene, phenanthrene, and anthracene. The proteinases produced on the noncarbohydrate medium were identical with those produced in glucose medium.
Comparison of Methods of Extracting Intracellular Proteases from Bacteria
Authors: Vadehra D. V. , Wallace D. L. , Harmon L. G.
Published: December 2020

Five commonly used methods of disintegrating bacterial cells were compared by use of
Bacillus subtilis, Pseudomonas putrefaciens
, and
Streptococcus durans
as the test organisms. These methods were: (i) sonic treatment, (ii) grinding, (iii) freezing and thawing, (iv) acetone-powder, and (v) toluene. Sonic treatment and grinding yielded more protein in the cell-free extracts than did the other methods. Likewise, the protease activities (micrograms of tyrosine liberated per milliliter of extract) of sonically disrupted and ground cell extracts on casein substrates were far greater than those in extracts from cells disintegrated by the other methods. When the specific activity was based on the amount of tyrosine liberated per milligram of protein in the extract, the acetone-powder method yielded the most active protease extract, whereas the extract obtained by sonic treatment was least active. Other methods yielded extracts with intermediate specific activity.
Titration and Neutralization of Poliovirus in Micro Tissue Culture Under Increased Carbon Dioxide
Authors: Kende Meir , Robbins Mary Louise
Published: December 2020

Modification of the micro tissue culture technique, including incubation under increased CO
2
, resulted in prolongation of the viability of the cells. As a consequence, satisfactory titrations of poliovirus and of poliovirus antiserum have been achieved by the micro method. The technique offers a number of advantages over conventional methods.
Ecology of
Micrococcus radiodurans
Authors: Krabbenhoft K. L. , Anderson A. W. , Elliker P. R.
Published: December 2020

An ecological study of
Micrococcus radiodurans
indicated that microorganisms possessing the same morphological and radiation-resistance characteristics as that organism could be isolated from ground beef and from pork sausage. Further studies showed that such organisms also could be isolated from beef hides and from water from a creek adjacent to the packing plant from which the meat samples were obtained. Similar microorganisms were not isolated, however, from a limited number of samples of soil, hay, and fecal material. The use of high levels of γ-radiation in the initial isolation procedures proved to be advantageous in inactivating most of the other microflora and facilitating the isolation of
M. radiodurans
. Control experiments indicated that
M. radiodurans
did not compete well with the microflora present in ground meat, soil, and beef hides. Preincubation before irradiation of meat and soil samples or enrichment culture techniques did not enhance the isolation of
M. radiodurans
. The presence of
M. radiodurans
in creek water suggested one possible source of this organism.
Production of the Enzyme Naringinase by
Aspergillus niger
Authors: Bram B. , Solomons G. L.
Published: December 2020

The formation of naringinase, a glycolytic enzyme produced by
Aspergillus niger
, is repressed by glucose. Production of the enzyme is decreased below
p
H 4.0 and is stimulated by the presence of substrate. Fermentation conditions are described which cause the formation of the enzyme in approximately a fivefold greater concentration than that previously described.
Thermal Inactivation Characteristics of
Bacillus subtilis
Spores at Ultrahigh Temperatures
Authors: Edwards J. L. , Busta F. F. , Speck M. L.
Published: December 2020

The thermal inactivation characteristics of
Bacillus subtilis
A spores suspended in skim milk with the use of large-scale ultrahigh temperature (UHT) processing equipment were investigated in terms of survival as measured with two plating media. Data on survival immediately after UHT treatments were recorded in temperature-survivor curves, time-survivor curves, and decimal reduction time (DRT) curves. The temperature-survivor curves emphasized that inactivation is accelerated more by increases in the treatment temperature than by increases in the exposure time. Time-survivor curves and DRT curves were not linear. Generally, exceedingly concave time-survivor curves were observed with the standard plating medium; however, only slightly concave curves were observed when CaCl
2
and sodium dipicolinate were added to the medium. For a given UHT sample, larger
D
values were obtained by use of the medium with the added CaCl
2
and sodium dipicolinate. The DRT curves of all data were concave and appeared to have two discrete slopes (
z
D
values). The
z
D
values observed in the upper UHT range (above 260 F; 127 C) were twice those observed at lower test temperatures.
Heat Injury of
Bacillus subtilis
Spores at Ultrahigh Temperatures
Authors: Edwards J. L. , Busta F. F. , Speck M. L.
Published: December 2020

The following three criteria indicated that
Bacillus subtilis
A spores were injured, but not completely inactivated, by ultrahigh temperature treatment. (i) Significant reductions in survivors were observed when spores were enumerated with a standard medium but not when the medium contained added CaCl
2
and sodium dipicolinate. (ii) After a damaging heat treatment, more survivors were enumerated with the standard medium after incubation at 32 C than at 45 C, which was opposite to the result with untreated or slightly heated spores. (iii) Apparent numbers of survivors increased during the initial period of 3 C storage when enumerated with the standard medium at 45 C. No injury was evident when survivors were enumerated at either incubation temperature with the medium containing added CaCl
2
and sodium dipicolinate. Heat activation of the spores did not significantly influence the appearance of heat injury. The data suggested that the heat injury occurred in a germination system which was required in the absence of CaCl
2
and sodium dipicolinate.
Production of Egg Yolk Coloring Material by a Fermentation Process
Authors: Schwarz Y. , Margalith P.
Published: December 2020

Rhodotorula mucilaginosa
was cultivated in a yeast propagator, for the production of biomass and carotenoids. A spray-dried preparation of the yeast was incorporated into the diets of laying chickens for the promotion of egg yolk color. Several aspects of the effect of media on growth and carotenogenesis of pigmented yeast were examined. Addition of 1 to 2% of
Rhodotorula
yeast to the feeding mixture considerably improved egg yolk color. The possibility of using carotenogenic yeasts as a feed supplement is suggested.
Polysaccharide Produced by the Genus
Pullularia
Authors: Ueda Seinosuke , Kono Haruyoshi
Published: December 2020

Acetone cells of
Pullularia
sp. were incubated with maltose, and the saccharides produced were fractionated on a charcoal column. The fractions were subjected to paper-chromatographic analysis and enzymatic assay. By these methods, the saccharides have been shown to include glucose, maltose, maltotriose, panose, and the lower members of glucose polymers containing the 1,4- and 1,6-α-glucosidic linkages, but neither isomaltose nor dextrantriose. The use of glucose oxidase results in the formation of the higher members of glucose polymer.
Level and Specificity of Antibodies Evoked by Crude and Purified Antigens of Poliovirus I and Echovirus 7
Authors: Frommhagen Laurence H.
Published: December 2020

Preparations of poliovirus I and echovirus 7, purified by density gradient centrifugation, liquid-phase partition, and anion exchange (diethylaminoethyl) chromatography, have been shown to evoke high antibody levels of substantial specificity in the complement-fixation assay. Certain practical aspects of the three purification methods are discussed. These results argue for the use of purified viral antigens, particularly in view of the simplicity of the purification methods now available.
Basis for the Exclusion of
Escherichia coli
from the Rumen Ecosystem
Authors: Hollowell C. A. , Wolin M. J.
Published: December 2020

The possible causes for the exclusion of
Escherichia coli
from the rumen ecosystem were investigated. Evidence presented indicates that oxidation-reduction potential, temperature,
p
H, CO
2
, volatile fatty acids, traces of heavy metals, and bacteriophage are not environmental factors which select against
E. coli
in the rumen ecosystem. The feeding of nutrients utilizable by
E. coli
to an artificially inoculated continuous-culture rumen ecosystem did not prevent the washout of the
E. coli
from the continuous cultures. The presence of an inhibitor of
E. coli
growth was demonstrated. High concentrations of rumen fluid (50 to 100%) were necessary to inhibit growth in Antibiotic Medium 3. The inhibitor may operate to control the growth of
E. coli
in the rumen ecosystem. Because of the presence of an inhibitor, the possibility that rumen fluid is deficient in nutrients to support the growth of
E. coli
cannot be eliminated.
Agar-Gel Precipitin-Inhibition Technique for Plague Antibody Determinations
Authors: Ray John G. , Kadull Paul J.
Published: December 2020

An application of the agar-gel precipitin-inhibition technique we described previously can be used to detect plague antibodies in human and animal sera after a series of plague vaccine inoculations or after exposure to
Pasteurella pestis
. Determination of the minimal reacting concentrations of the plague antigen and antibody reagents, methods for combining reagents, and length of incubation periods are discussed.
Antimicrobial Activity of Several Bis-Methanethiolsulfonates
Authors: Wolf Paul A. , Riley W. H. , Pollock Marlene
Published: December 2020

We determined the inhibitory end point of a series of bis-methanethiolsulfonates, CH
3
SO
2
S(CH
2
)
n
SSO
2
CH
3
(n = 2 to 6), and correlated the structures with antimicrobial activity. Eleven microorganisms were used in the evaluation, and the maximal activity occurred when the methylene chain length was five or six. The effect of CH
3
SO
2
S(CH
2
)
5
SSO
2
CH
3
(PMTS) on respiration of
Aerobacter aerogenes
and
Staphylococcus aureus
was studied at various stages of their growth cycles. The effect on viability was correlated with that of respiration in the case of
A. aerogenes
. Respiratory inhibition caused by PMTS varied with the growth phase of both organisms, being most pronounced when the cells tested were taken during the period of transition from the log to stationary phase. The lethal effect on
A. aerogenes
was also greatest at this time. During the period of increased sensitivity, the antimicrobial activity of PMTS appears to be closely related to cell respiration. The delayed rate of kill otherwise observed may reflect an impairment of protein metabolism through reaction with sensitive SH groups.
Effects of Related Anionic Detergents on Flagellation, Motility, Swarming, and Growth of
Proteus
Authors: Kopp Rudolf , Müller Johannes
Published: December 2020

The effects of a series of sodium alkyl sulfates (C
4
to C
16
) on flagellation, motility, swarming, and growth of
Proteus
were examined. The concentrations of the various sodium alkyl sulfates completely inhibiting the swarming phenomenon (on solid medium) and motility (in liquid medium) were in the same order of magnitude. The inhibiting effect of the detergents examined increased from sodium hexyl sulfate (inhibitory concentration, 20 to 30 mmoles per liter) to sodium tetradecyl sulfate (inhibitory concentration, 0.1 to 0.5 mmoles per liter). Flagella were produced neither in liquid nor on solid medium at these concentrations as could be observed by electron microscopy. At concentrations where motility was not impaired, intact flagellation could be observed. At a concentration of 0.1 mmole per liter, sodium tetradecyl sulfate completely inhibited the motility of
Proteus
in the liquid medium employed without impairing growth.
Effect of Several Environmental Conditions on the “Thermal Death Rate” of Endospores of Aerobic, Thermophilic Bacteria
Authors: Yokoya Fumio , York George K.
Published: December 2020

The composition of the recovery medium affected the apparent heat resistance of
Bacillus stearothermophilus
when the
p
H of the medium was 7.0 but not when the
p
H was 6.5. The rate of thermal death at 110 C was exponential. Deviations from exponential rates of thermal death during the initial phases of heating at 96 C were observed with endospores of
B. coagulans
under different conditions of sporulation. Additionally, the apparent heat resistance was influenced by the composition of the media used for sporulation and recovery and by the composition of the suspending menstruum. The presence of 0.001
m
sorbic acid in the suspending menstruum at
p
H 7.0 and the temperature of incubation of the cultures after heating did not affect the apparent heat resistance of
B. coagulans
. Several explanations are discussed for the observed deviations from exponential thermal death rates and the effect of the environment on the apparent heat resistance of
B. coagulans
.
Direct Fluorescent Labeling of Microorganisms as a Possible Life-Detection Technique
Authors: Pital Abe , Janowitz Sheldon L. , Hudak Charles E. , Lewis Evelyn E.
Published: December 2020

Microorganisms and selected proteinaceous substances were directly tagged with fluorescein isothiocyanate. This approach suggested a possible application for detection of extraterrestrial life. A stable and apparently specific linkage was formed with protein, and nonprotein substances were readily destained. Soil and atmospheric debris did not exhibit any significant affinity for the dye.
Effect of Coliform and
Proteus
Bacteria on Growth of
Staphylococcus aureus
Authors: DiGiacinto J. V. , Frazier W. C.
Published: December 2020

Cultures of coliform and
Proteus
bacteria, mostly from foods, were tested for their effect on growth of
Staphylococcus aureus
in Trypticase Soy Broth. Inhibition of the staphylococcus by these competitors increased with increasing proportions of inhibiting (effector) bacteria in the inoculum and decreasing incubation temperatures (37 to 10 C). Time required for 2 × 10
4
staphylococci to increase to 5 × 10
6
cells per milliliter, the minimal number assumed to be necessary for food poisoning, varied with the species of effector, the original ratio of effector bacteria to staphylococci in the medium, and the incubation temperature. When the original ratio was 100:1, the staphylococci did not reach 5 × 10
6
cells per milliliter at 10, 15, 22, or 30 C (with one exception), when growing with cultures representing six species of coliform bacteria and two of
Proteus
. When the ratio was 1:1, all effectors either greatly delayed the staphylococcus or prevented it from reaching hazardous numbers at 15 C, six of the eight caused a delay of 2 to 3 hr at 22 C, and only
Escherichia coli
delayed the coccus at 30 C. All effectors were ineffective at 22 and 30 C when original numbers of effectors and staphylococci were in the ratio 1:100. Greatest overall inhibition was by
E. coli, E. freundii
, and
Proteus vulgaris
, and these species were more effective than the others at 22 and 30 C.
Aerobacter cloacae
and
Paracolobactrum aerogenoides
were more effective at 15 C. In general, results were similar with different strains of a species. Except for
Aerobacter aerogenes, Klebsiella
sp., and
P. aerogenoides
, which apparently did not compete for nutrients, inhibition of the staphylococcus was by a combination of antibiotic substances and competition for nutrients.
Microbiology of Ensiled High-Moisture Corn
Authors: Burmeister Harland R. , Hartman Paul A. , Saul Robert A.
Published: December 2020

The effects of gaseous environment and temperature on the microbial populations of ensiled high-moisture corn were investigated. Molds, coliform bacteria, mesophilic aerobic bacteria, and yeasts were enumerated at intervals during ensiling. The numbers of aerobic bacteria were similar in structures containing different concentrations of gas and held at different temperatures. Coliform bacteria could not be detected after 10 days of ensiling. Mold numbers were relatively low, but were important in the deterioration of corn at the surface of the silos. Yeast and bacterial numbers increased rapidly following an initial aeration period, but no increase was observed after a second aeration series. Lack of a growth response to the second aeration series is believed related to the depletion of an assimilable carbon source.