bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Methods for Growth Detection in the Search for Extraterrestrial Life
Authors: Merek Edward L. , Oyama Vance I.
Published: December 2020

In the search for life on other planets, experiments designed to detect the growth of microorganisms may prove to be definitive when coupled with chemical characterization and metabolic experiments. If organisms are not abundant, growth provides the only means for obtaining a large mass of biological material suitable for chemical compositional analyses and metabolic assays. Several methods of monitoring growth are described. Of these, optical monitoring in a unique system free of soil particles is advanced as the most appropriate. Theoretical problems related to the formulation of culture media are discussed, and several possible solutions are proposed. The sampling system, the type of monitoring, the size and placement of inoculum, and the medium volume and composition are contingent upon one another and must be integrated without sacrifice to the biological demands.
Variation in Plating Efficiency of Salmonellae on Eight Lots of Brilliant Green Agar
Authors: Read R. B. , Reyes A. L.
Published: December 2020

The plating efficiency of
Salmonella anatum, S. cubana, S. dublin, S. tennessee
, and
S. typhimurium
was determined for eight lots of Brilliant Green Agar made by two manufacturers. Washed cells were used as the inoculum and cultures were incubated at 41.5 C. All lots of Brilliant Green Agar were supplemented with 12 mg of sulfadiazine per 100 ml of medium. Of the eight lots of Brilliant Green Agar tested, average recovery of the test salmonellae in three did not differ from recoveries with Trypticase Soy Agar, which was used as a control to indicate the number of viable salmonellae in the test suspension capable of growth on a nonselective medium. Two lots of Brilliant Green Agar gave salmonellae recoveries with geometric means about 25% lower than, and significantly different from, those of the control agar. The remaining three lots of Brilliant Green Agar were generally unproductive.
Microbiological Deterioration of Frozen Parfried Potatoes upon Holding After Thawing
Authors: Michener H. David , Boyle Frank P. , Notter George K. , Guadagni D. G.
Published: December 2020

Frozen parfried potatoes were thawed and stored at 55, 45, and 34 F (12.8, 7.2, 1.1 C). Significant changes in flavor and texture did not occur at these temperatures until the total bacterial count exceeded 100 million per gram. These sensory changes were produced after 4, 8, and 20 days of storage at 55, 45, and 34 F, respectively. Detectable color change appeared sooner and probably was not of microbial origin. It is unlikely that any health hazard exists under the range of conditions studied. Nevertheless, it seems undesirable to market food with such a high bacterial count. At half the storage periods given above, the count did not exceed 100,000 per gram.
New Ventilated Isolation Cage
Authors: Cook Reginald O.
Published: December 2020

A multifunction lid has been developed for a commercially available transparent animal cage which permits feeding, watering, viewing, long-term holding, and local transport of laboratory rodents on experiment while isolating the surrounding environment. The cage is airtight except for its inlet and exhaust high-efficiency particulate air filters, and it is completely steam-sterilizable. Opening of the cage's feed and water ports causes an inrush of high velocity air which prevents back-migration of aerosols and permits feeding and watering while eliminating need for chemical vapor decontamination. Ventilation system design permits the holding in adjacent cages of animals infected with different organisms without danger of cross-contamination; leaves the animal room odor-free; reduces required bedding changes to twice a month or less, and provides investigators with capability to control precisely individual cage ventilation rates. Forty-eight cages can be conveniently placed on a standard NIH “shoebox” cage rack (60 inches wide × 28 inches deep × 74 inches high) fitted with a simple manifold exhaust system. The entire system is mobile, requiring only an electrical power outlet. Principal application of the caging system is in the area of preventing exposure of animal caretakers to pathogenic substances associated with the animal host, and in reducing handling of animals and their exposure to extraneous contamination.
Gas Consumption and Growth Rate of
Hydrogenomonas eutropha
in Continuous Culture
Authors: Ammann Elizabeth C. B. , Reed Lawrence L. , Durichek John E.
Published: December 2020

The bacterium
Hydrogenomonas eutropha
is under consideration for use in a regenerative life-support system for manned space missions of long duration. A 4-liter continuous culture unit containing the organism was operated for a period of 272 days under autotrophic environmental conditions. The best steady-state run achieved with this unit was observed over a 22-day time interval after 181 days of operation. During this time, the culture consumed an average of 22.9 ± 2.0 ml of carbon dioxide per min, 38.1 ± 3.3 ml of oxygen per min, and 128.5 ± 10.6 ml of hydrogen per min. It required 18.7 ± 1.2 liters of fresh nutrient medium per 24 hr to maintain a constant, preestablished cell population of 1.65 g (dry weight) per liter. The ratio of consumption of carbon dioxide, oxygen, and hydrogen varied from 1:1.2:4.5 to 1:1.9:6.6, with an average of 1:1.7:5.7. Based on these values, approximately 60 liters of the culture would be necessary to balance the gas exchange of one man.
Effect of Lipid Materials on the Production of Lipase by
Torulopsis ernobii
Authors: Yoshida Fumihiko , Motai Hiroshi , Ichishima Eiji
Published: December 2020

The yeast
Torulopsis ernobii
produced approximately 50 units of extracellular lipase (glycerol ester hydrolase, E.C. 3.1.1.3) per ml when grown in 30-liter fermentors at 33 C for 40 hr in a base medium at
p
H 5.0. The addition of fats, oils, triglycerides, or higher fatty acids to this medium at concentrations of 0.2 to 0.6% markedly increased production; twofold increases in yield were obtained when 0.2% olive oil or a mixture of 0.14% oleic acid and 0.04% palmitic acid was added. The production of lipase paralleled growth, and the role of lipid materials in augmenting lipase production appears to be related to cell growth.
Fungi Isolated from Damaged Flue-cured Tobacco
Authors: Welty R. E. , Lucas G. B.
Published: December 2020

Species of
Aspergillus
were the most prevalent fungi isolated from 51 samples of damaged flue-cured tobacco of the 1966 U.S. crop, comprising 57% of the total isolates. Other prevalent fungi were
Penicillium
(16%),
Alternaria
(8%),
Cladosporium
(4%), and
Chaetomium
(4%). Members of the
Aspergillus glaucus
group were isolated most frequently from samples with moisture contents ranging from 18 to 28%, whereas
Alternaria, Cladosporium
, and
Penicillium
were isolated consistently from samples containing 24 to 32% moisture.
Aspergillus niger
was prevalent in tobacco ranging in moisture content from 18 to 30%.
A Microbiological Assay for Estimating Concentrations of Camptothecin Lactone in Mouse Tissues
Authors: Hunt Dale E. , Pittillo Robert F.
Published: December 2020

The marked sensitivity of the yeast
Hansenula wingei
NRRL Y-2340 strain 5 to a new antineoplastic alkaloid served as the basis for a logarithmic-ratio microbiological assay which has been developed for the estimation of concentrations of camptothecin lactone (or cytotoxic equivalents) in tissues of mice. The utility of this assay has been demonstrated by presenting data which show the concentrations of camptothecin lactone (or cytotoxic equivalents) detected in various tissues of mice at intervals following intraperitoneal injection of a 1 or 0.5
ld
10
dose of this drug.
Metabolic Variations of
Proteus
in the Memphis Area and Other Geographical Areas
Authors: Suter Loyal S. , Ulrich Elizabeth W. , Koelz Byron S. , Street Vera W.
Published: December 2020

The number of strains of
Proteus
studied was 413, and these were obtained from all clinical materials with the exception of fecal specimens. Lactose was fermented by 37 strains (
P. inconstans
, 29%;
P. rettgeri
, 16%;
P. mirabilis
, 4.2%;
P. morganii, 3.6
%; and
P. vulgaris
, 0%) of which 33 were from the genitourinary system. These 33 strains constituted 12.7% of the 260 strains isolated from this source. Biochemically,
P. mirabilis
was the least variable, and
P. rettgeri
was the most variable of the five species of
Proteus
tested.
P. inconstans
and
P. rettgeri
resembled each other more closely than any of the other species of
Proteus
. Comparison of results obtained in the Memphis area with those found in other locations showed that biochemical characteristics varied most with the substances citrate, salicin, xylose, trehalose, and mannitol. In contrast to earlier reports from Israel and England, none of the strains of
P. inconstans
in the present study was able to attack urea. All five species of
Proteus
tested (by the disc method) were highly susceptible to methenamine mandelate.
P. mirabilis, P. morganii
, and
P. vulgaris
were also highly susceptible to nitrofurantoin. All strains of
P. mirabilis
were susceptible to ampicillin.
P. inconstans
was the most resistant species of
Proteus
. Of the other 356 urease-positive strains tested, 79% were susceptible to chloramphenicol, whereas only 3.8% of the 56 urease-negative strains (
P. inconstans
) were susceptible. When tested with streptomycin, 61% of urease-positive strains were susceptible and 1.8% of the urease-negative strains were susceptible. Of 36 lactose-positive strains, 33.8% were susceptible to chloramphenicol, whereas 72.8% of all lactose-negative strains were susceptible. Again, of the lactose-positive strains, 17% were susceptible to streptomycin, whereas 56.3% of all lactose-negative strains were susceptible.
Effect of Different Media on In Vitro Studies of Antibiotic Combinations
Authors: Bulger Roger J. , Nielson Kathleen
Published: December 2020

In an effort to determine the adequacy of a standard broth medium in the evaluation of antibiotic combinations, 20 strains of various bacterial species were studied simultaneously in Mueller-Hinton broth and in freshly drawn human serum from apparently healthy volunteers. Studies of growth dynamics by use of the usual plate dilution technique for quantitating colony-forming units were performed with strains of
Staphylococcus aureus
(methicillin-resistant and methicillin-susceptible),
Streptococcus faecalis, Escherichia coli, Aerobacter, Klebsiella
, and
Proteus mirabilis
. A variety of different antibiotics were investigated. With 19 of the 20 strains, interpretations of synergism or antagonism were the same in both media. Therefore, despite minor variations when the same strain was studied in both serum and broth, it is concluded that Mueller-Hinton broth is an adequate medium for use in studies of chemotherapeutic combinations in vitro. A simplified method for studying bactericidal activity is described, which is deemed practical for clinical microbiology laboratories and which led to the same conclusions regarding the combinations as were obtained by the more arduous plate dilution test.
Nitrogen-deficient Medium in the Differential Isolation of
Klebsiella
and
Enterobacter
from Feces
Authors: Eller Charles , Edwards Fitzroy F.
Published: December 2020

On a nitrogen-deficient agar medium, the tribe
Klebsielleae
formed large, glistening, mucoid colonies which were easily distinguished from other colony types. Of 113
Klebsielleae
isolates from human feces which were characterized,
Klebsiella
accounted for 88% of the total; 75% were
K. pneumoniae; K. ozaenae
(13%) was isolated from one individual only. The remaining strains (12%) were identified as
Enterobacter cloacae
. Counts (for the tribe) ranged from 10
2
to 10
6
, with a median of 10
4
; 9 of 53 stool specimens were negative.
K. pneumoniae
was also isolated from 6 of 41 frozen foil-pack foods. Anaerobic studies at room temperature and 37 C revealed no appreciable differences from aerobic plates. The nitrogen-deficient medium appeared better than E M B for isolation of
Klebsielleae
when they were present in low numbers relative to other coliforms; slime production by
Klebsielleae
concomitant with minimal growth of other bacteria is involved.
Fungal Susceptibility of Polyurethanes
Authors: Darby Richard T. , Kaplan Arthur M.
Published: December 2020

One hundred laboratory-synthesized polyurethanes were tested by a mixed-culture petri dish method for susceptibility to fungus attack. Polyether polyurethanes were moderately to highly resistant to fungal attack, whereas all polyester polyurethanes tested were highly susceptible. The susceptibility of the polyethers was related to the number of adjacent methylene groups in the polymer chain. At least two such groups were required for appreciable attack to occur. The presence of side chains on the diol moiety of the polyurethane reduced susceptibility.
Production of Enterotoxin A in Milk
Authors: Donnelly C. B. , Leslie J. E. , Black L. A.
Published: December 2020

Enterotoxin A production in milk was studied by use of variables of milk quality, initial numbers of enterotoxigenic staphylococci, incubation temperature, and time. In both raw and pasteurized milks having a low total viable count, enterotoxin was detected in minimal incubation times of 6 to 9 hr at 35 C, 9 to 12 hr at 30 C, 18 hr at 25 C, and 36 hr at 20 C, after inoculation with 10
6
Staphylococcus aureus
cells per ml. When similar milks were inoculated with 10
4
S. aureus
cells per ml, enterotoxin was detected in 12 hr at 35 C, 18 hr at 30 C, 24 to 36 hr at 25 C, and 48 to 96 hr at 20 C. In high-count raw milk, enterotoxin was detected only in samples inoculated with 10
6
S. aureus
cells per ml and incubated at 35 C. Generally, a concentration of 5 × 10
7
S. aureus
cells per ml of milk was reached before enterotoxin A was detected.
Diagnostic Key to Mycobacteria Encountered in Clinical Laboratories
Authors: Wayne Lawrence G. , Doubek Joseph R.
Published: December 2020

A diagnostic key has been developed which will permit identification of most mycobacteria encountered in clinical laboratories. The key is based on performance of a few simple tests. The efficiency and accuracy of the key was evaluated in terms of correlation between identifications based on the few tests and those arrived at through application of the techniques of numerical taxonomy, which involves a large battery of tests. Of 679 cultures of mycobacteria other than
Mycobacterium tuberculosis
, 86.5% were correctly identified by use of the key, and only 1.8% of the cultures were erroneously identified. The remaining cultures required further examination.
Use of the Scanning Electron Microscope for Viewing Bacteria in Soil
Authors: Hagen C. A. , Hawrylewicz E. J. , Anderson B. T. , Tolkacz Vivian K. , Cephus Marjorie L.
Published: December 2020

Scanning electron microscopy was used for viewing
Bacillus cereus
and
Staphylococcus aureus
in three different soils. Both organisms were detected in the test soils at an approximate concentration of 10
7
cells per gram of soil; theoretically, the minimal number of microorganisms required for detection with the scanning electron microscope technique was between 10
7
and 10
10
cells per gram of soil. Because the concentration of cells was critical, the use of scanning electron microscopy as an extraterrestrial life detection instrument would be limited with soils containing more than 10
7
bacteria per gram of soil.
Rapid, Sensitive Assay for Staphylococcal Enterotoxin and a Comparison of Serological Methods
Authors: Silverman Sidney J. , Knott Allen R. , Howard Mary
Published: December 2020

Reversed passive hemagglutination was used to assay enterotoxin in culture filtrates and in food samples. With cells tanned and then sensitized with antitoxin globulin and preserved with either formaldehyde or pyruvic aldehyde, as little as 0.0007 μg of enterotoxin was detectable. The results of hemagglutination tests compared well with those obtained by quantitative precipitin tests or by immunodiffusion, but hemagglutination was 50 to 100 times more sensitive than the immunodiffusion technique. In addition, results of the hemagglutination test were available within a few hours, and neither elimination of interfering proteins from food extracts nor concentration of the sample, both of which are necessary for immunodiffusion, was required for this procedure.
Bloater Formation by Gas-forming Lactic Acid Bacteria in Cucumber Fermentations
Authors: Etchells J. L. , Borg A. F. , Bell T. A.
Published: December 2020

The formation of “bloaters” (hollow stock) in cucumbers brined for salt-stock purposes at 5 to 10% salt has been associated with gaseous fermentation caused chiefly by yeasts. Recently, serious early bloater damage, not attributable to yeasts, has been observed in commercial-scale experiments on control of bloaters in overnight dill pickles brined in 50-gal barrels at 3.0 to 4.5% salt. Growth of fermentative species of yeasts was effectively controlled by the addition of 0.025, 0.05, and 0.1% sorbic acid or its sodium salt. In contrast to this, the fermenting brines showed extremely high populations of acid-forming bacteria, identified as
Lactobacillus plantarum, L. brevis
, and
Pediococcus cerevisiae
. The gas-forming species (i.e.,
L. brevis
) constituted a high proportion of the total populations. Representative isolates from 36 barrels of overnight dill pickles were tested for their ability to produce bloaters in 1-quart jars of pasteurized cucumbers equilibrated at 4 to 5% salt, 0.25% lactic acid, and
p
H 4.0. Bloaters, identical with those made by yeast cultures, were produced in all jars inoculated with
L. brevis
. No bloaters were produced by
L. plantarum
and
P. cerevisiae
. These results suggest that the control of bloater damage in cucumber fermentations, particularly at low salt concentrations, may necessitate inhibition of gas-forming lactic acid bacteria.
Effect of Complement and Viral Filtration on the Neutralization of Respiratory Syncytial Virus
Authors: Baughman Richard H. , Fenters James D. , Marquis George S. , Holper Jacob C.
Published: December 2020

The addition of 10 hemolytic units of guinea pig complement has been shown to enhance the neutralizing capacity of respiratory syncytial (RS) immune sera produced in guinea pigs and ferrets. This same immune sera, when tested without complement, had little or no neutralizing capacity. The addition of complement to RS immune horse serum did not significantly increase its neutralizing capacity. Immune horse serum effectively neutralized RS virus without complement. Other studies indicated that a 50% tissue culture infective dose of between 30 and 100 should be used in RS serum neutralization tests and that incubation should be for 90 to 105 min at room temperature. The neutralizing capacity of guinea pig immune serum was not increased by the use of filtered virus. The rate of virus neutralization, however, was increased with the addition of 10 hemolytic units of complement. The neutralizing capacity of RS immune horse serum was much greater for filtered than for unfiltered RS virus. The addition of complement increased the rate of virus neutralization but did not increase the neutralizing capacity of the horse immune serum.
Correlations Between Free Radical Production and Viability of Lyophilized Bacteria
Authors: Heckly Robert J. , Dimmick R. L.
Published: December 2020

When
Serratia marcescens
cultures were treated with dilute solutions of phenol or hydrogen peroxide before drying or by lyophilization at suboptimal
p
H, the log of the number of cells surviving lyophilization was correlated with subsequent free radical production by the dried cells. Since the rate of free radical production and rate of death were similarly affected by temperature, the log of the number of cells surviving after 6 days was inversely related to the free radical concentration at that time. Free radicals were produced in proportion to the log of oxygen pressure, and viability was inversely related to oxygen tension; again, free radical concentration appeared to be correlated with the death of organisms.
Microbiological Studies on the Performance of a Laminar Airflow Biological Cabinet
Authors: Mcdade Joseph J. , Sabel Fred L. , Akers Ronald L. , Walker Robert J.
Published: December 2020

Engineering and microbiological tests indicated that a typical, commercial laminar airflow cabinet was not effective in providing either product protection or agent containment. The cabinet was modified and tested through a series of alternate configurations to establish a set of design criteria. A mock-up cabinet was developed from these design criteria. The mock-up unit was evaluated for efficiency in providing both product protection and agent containment. In these evaluations, challenge methods were developed to simulate normal, in-use laboratory operations. Controlled bacterial or viral aerosol challenges were used at higher than normal levels to provide stringent test conditions. Test results indicated that the mock-up unit was considerably better in preventing agent penetration (0.1 to 0.2 particles per 100 ft
3
of air) than the commercial cabinet (5 to 6 particles per 100 ft
3
of air) during product protection tests. Similarly, agent containment was considerably better in the new cabinet (particle escape of 2 to 3 per 100 ft
3
of air at only one of the five test sites) than in the commercial cabinet (particle escape of 2 to 14 per 100 ft
3
of air at three of the five test sites).
Instrument for Study of Microbial Thermal Inactivation
Authors: Dickerson R. W. , Read R. B.
Published: December 2020

An instrument was designed for the study of thermal inactivation of microorganisms using heating times of less than 1 sec. The instrument operates on the principle of rapid automatic displacement of the microorganism to and from a saturated steam atmosphere, and the operating temperature range is 50 to 90 C. At a temperature of 70 C, thermometric lag (time required to respond to 63.2% of a step change) of the fluid sample containing microorganisms was 0.12 sec. Heating time required to heat the sample to within 0.1 C of the exposure temperature was less than 1 sec, permitting exposure periods as brief as 1 sec, provided the proper corrections are made for the lethal effect of heating. The instrument is most useful for heat exposure periods of less than 5 min, and, typically, more than 500 samples can be processed for microbial inactivation determinations within an 8-hr period.
Nonspecific Toxicities in the Mouse Assay Test for Botulinum Toxin
Authors: Segner W. P. , Schmidt C. F.
Published: December 2020

In inoculated pack experiments on
Clostridium botulinum
type E, unirradiated and 0.1-Mrad irradiated haddock fillets often gave nonspecific toxicities by the mouse assay test for botulinum toxin. Samples given 0.2-Mrad radiation failed to produce nonspecific reactions. Nonspecific deaths sometimes occurred within 24 hr after injection, although deaths between 24 and 48 hr were more common. The symptoms and the pattern of these deaths suggested a septicemia. Heart-blood cultured from mice showing nonspecific symptoms indicated an infectious process. Among 23 isolates from the blood, eight were identified as
Proteus vulgaris
, two
P. morganii
, one
P. rettgeri
, one Providence subgroup B, two
Aerobacter aerogenes
, one
Actinobacillus
, three enterococci, one
Alcaligenes marshalli
, and four
Erysipelothrix insidiosa
. The
E. insidiosa, Aerobacter
, Providence group, and most of the
Proteus
isolates were infectious for mice when injected by the intraperitoneal route. But the enterococci,
Alcaligenes
, and
Actinobacillus
isolates were not infectious and probably represent secondary invaders. The cultural characteristics of the
E. insidiosa
isolates conform to those described in the literature, with the exception that the four strains grew in the temperature range 50 F (10 C) to 40 F (4.4 C). Nonspecific toxicities were avoided in assays for botulinum toxin by the protection of mice with chloramphenicol and oxytetracycline.
Comparative Inhibition of Methicillin-resistant Strains of
Staphylococcus aureus
by Lysostaphin and Otner Antibiotics
Authors: Zygmunt Walter A. , Harrison Edward F. , Browder Henry P. , Tavormina Peter A.
Published: December 2020

Sixteen methicillin-resistant strains of
Staphylococcus aureus
obtained from Europe were found to be sensitive to the lytic activity of lysotaphin. With only minor exceptions, the strains were found to be sensitive to novobiocin, erythromycin, fusidic acid, and lincomycin, and slightly less sensitive to vancomycin and chloramphenicol. All strains were resistant to tetracycline, penicillinase-sensitive penicillins (benzylpenicillin, ampicillin, and propicillin), penicillinase-resistant penicillins (methicillin, nafcillin, ancillin, oxacillin, cloxacillin, and dicloxacillin), and two cephalosporin antibiotics (cephalothin and cephaloridine).
Detoxification of Liquid Cultures of
Bordetella pertussis
by Forced Aeration at High
p
H
Authors: Lane A. G.
Published: December 2020

Cultures of
Bordetella pertussis
cultivated in shake flasks were invariably highly toxic for mice, but cultures of the same strain grown in vortex-aerated vessels were nontoxic at the time of harvest. Results reported here indicate that toxin is present during the early log phase in vortex-aerated cultures, but is lost as the cultivation proceeds. The loss of toxicity is apparently due to denaturation of the toxin by the combined influence of vigorous aeration and elevated
p
H.
Factors Influencing Aflatoxin Accumulation in Peanut Kernels and the Associated Mycoflora
Authors: Pettit Robert E. , Taber Ruth Ann
Published: December 2020

Accumulation of aflatoxin in Spanish peanut kernel samples from different geographical areas in Texas during 1966, as detected by the thin-layer chromatographic method, was relatively low. Analysis of samples obtained from growers using artificial drying equipment (forced air and supplemental heat), when windrow conditions were unfavorable for rapid drying, suggests that this practice reduces the possibility of aflatoxin accumulation. In general, peanuts harvested from land planted to peanuts the previous year were more highly infested with fungi and contained more aflatoxin than peanuts grown on land planted with rye, oats, melons, or potatoes the previous year. Aflatoxin incidence tended to decrease from south to north Texas. These findings verify previous research observations that moist tropical climates are conducive to fungal infestation and aflatoxin accumulation. Detection of aflatoxin in sound mature kernels (kernels screened for minimal size) indicates that the practice of screening for removal of small immature kernels and removal of obviously damaged kernels does not completely eliminate aflatoxin contamination.
Clostridium perfringens
Type A Infection of Ligated Intestinal Loops in Lambs
Authors: Hauschild A. H. W. , Niilo L. , Dorward W. J.
Published: December 2020

Clostridium perfringens
type A suspended in fresh medium was injected into ligated intestinal loops of lambs. Within 7 hr after inoculation, the fluid volume of the loops increased up to seven times. No significant accumulation of fluid occurred in loops receiving grown culture, culture supernatant fluid, or medium alone. α-Antitoxin injected along with
C. perfringens
in fresh medium into intestinal loops did not prevent the accumulation of fluid. It is concluded that α-toxin plays no major role in
C. perfringens
type A enteritis.
Effect of Cell Moisture on the Thermal Inactivation Rate of Bacterial Spores
Authors: Hoffman Robert K. , Gambill Vernon M. , Buchanan Lee M.
Published: December 2020

Thermal inactivation rates were determined for two strains of
Bacillus subtilis
var.
niger
spores after equilibration to various relative humidity (RH) levels. In these tests, small thin stainless-steel squares were each inoculated with a drop of spore suspension and equilibrated to 11, 33, or 85% RH. Following equilibration, the squares were placed on a hot plate preheated to 108, 125, 136, 164, or 192 C for various exposure times and then assayed for surviving organisms. The results revealed that spores of the A strain of
B. subtilis
were least resistant if preequilibrated to 11% RH and most resistant if preequilibrated to 85% RH. The same trend was obtained at all temperatures except 192 C, at which, no difference was noted, probably because the rapid kill time approaches the heat-up time of the stainless-steel square. The B strain of
B. subtilis
spores showed an opposite RH effect; that is, the cells preequilibrated to 11% RH were the most resistant. Because the two strains of spores were grown on different media, further studies were conducted at 136 C after subculturing the cells on different media. When the B strain was subcultured on the A strain medium, the pattern was reversed; the cells preequilibrated to low RH were then least resistant. Although it was not possible to reverse these cells to the original pattern by subculturing on the original B strain medium again, the pattern was altered to the point that there was no significant difference in heat resistance of these cells regardless of the preequilibration RH. The same result was obtained when the A strain was grown on the B strain medium; that is, the thermal resistance could not be reversed, but it was altered from the point where the low RH equilibrated cells were least resistant initially to the point where there was no significant difference in any of the cells regardless of what RH was used for preequilibration. The thermal resistance of spores seemed to be dependent on (i) the medium on which the spores are grown, (ii) the RH on which they are exposed before heating, and (iii) some genetic characteristic of the cell.
Production of Highly Labeled Adenoviruses
Authors: Burnett J. Paul , Summers A. O. , Harrington J. A. , Dwyer A. C.
Published: December 2020

A method is described for increasing the incorporation of radioactive thymidine into adenovirus deoxyribonucleic acid by the use of amethopterin. In addition, a modified procedure is presented for the preparation of highly purified adenoviruses. This procedure, which employs enzymatic digestion of cellular debris, obviates the necessity for fluorocarbon treatment of crude virus suspensions, and routinely provides excellent recovery of virus.
Disruption of Bacterial Cells by a Synthetic Zeolite
Authors: Wistreich George , Lechtman Max D. , Bartholomew J. W. , Bils R. F.
Published: December 2020

The use of a synthetic zeolite (type 4A, Union Carbide Corp., Linde Div., New York, N.Y.) in a procedure for the preparation of pure cell wall fractions proved successful for many gram-positive, gram-negative, and acid-fast bacteria, as well as for some fungi. The technique, however, was found to be limited in effectiveness for
Rhodospirillum rubrum, Gaffkya tetragena
, and
Sarcina lutea
, and not applicable to preparations of heat killed microorganisms. The possible mechanisms of zeolite action, together with the effect of the disruptive procedure on the chemical composition of cell wall fragments, were investigated also.
Production of Nuclease-forming 5′-Nucleotide by
Aspergillus quercinus
in a Low Phosphate Medium
Authors: Ohta Yoshiyuki , Ueda Seinosuke
Published: December 2020

The production of ribonucleic acid (RNA)-depolymerase-forming 5′-nucleotides (5′-nuclease) was investigated with the fungus
Aspergillus quercinus
in media containing 68, 10, 5, 3, 1, and 0.5 mg of phosphorus per 100 ml. Yields were maximal with 5 mg of phosphorus per 100 ml. RNA-depolymerase-forming 3′-nucleosides (3′-nuclease) and phosphomonoesterase were maximal in media containing 1 and 0.5 mg of phosphorus per 100 ml. The 5′-nuclease was purified approximately 530-fold with a recovery of 84% by column chromatography on diethylaminoethyl-cellulose and by gel filtration through Sephadex G-100. The purified enzyme was capable of acting on both deoxyribonucleic acid and RNA, and the 5′-mononucleotides produced were identified by paper chromatography. The enzyme 5′-nuclease appears to be one of the repressible exonucleases that are active in the production of 5′-mononucleotides.
Effect of Interferon, Polyacrylic Acid, and Polymethacrylic Acid on Tail Lesions in Mice Infected with Vaccinia Virus
Authors: De Clercq E. , De Somer P.
Published: December 2020

Intravenous inoculation of mice with vaccinia virus produced characteristic lesions of the tail surface which were suppressed by intraperitoneal administration of interferon and polyacrylic acid (PAA). Polymethacrylic acid (PMAA) stimulated the formation of vaccinia virus lesions. For full activity, both interferon and PAA must be given prior to infection. PAA was still significantly effective at small dose levels (3 mg/kg) and achieved protection for at least 4 weeks. Protection increased with increasing molecular weight of the polymer. The mode of action of PAA is discussed.
Growth of Mixed Cultures on Mixed Substrates
Authors: Chian S. K. , Mateles R. I.
Published: December 2020

Continuous culture on mixed glucose-lactose or glucose-butyrate media inoculated with river water led to a population composed of a pseudomonad and a coliform. The glucose was used preferentially to the other carbon source, and the utilization of the secondary carbon source was greatly reduced at high growth rates. Significant amounts of acetate were excreted even though the cultures were limited by the carbon source, rather than by oxygen or other nutrients. At high growth rates, the pseudomonad dominated the population, whereas at low and moderate growth rates the coliform was dominant. A syntrophic relationship was shown by the fact that the pseudomonad could not grow alone on the glucose-butyrate medium.
Hemagglutinating Property of
Haemophilus aegyptius
Authors: Mann Jerry M. , Rheins Melvin S.
Published: December 2020

Extracts possessing the capacity to hemagglutinate normal human erythrocytes were recovered from
Haemophilus aegyptius
by treatment with either diethylene glycol or acetone. Antisera prepared against these extracts or the unextracted bacterial cell inhibited hemagglutination by homologous and heterologous antigens. Microgel diffusions indicated the presence of identical components in each extract as expressed by lines of identity between antisera to each fraction. The hemagglutinin was identified as a lipopolysaccharide, 42% lipid and 57% carbohydrate. The determination of 6% phosphorus in the lipid fraction identified it as containing phospholipid.
Regeneration of Oxidative Assimilation Capacity by Intracellular Conversion of Storage Products to Protein
Authors: Goel K. C. , Gaudy A. F.
Published: December 2020

Previous studies have shown that the capacity of a heterogeneous microbial population for oxidative assimilation of glucose can be renewed by periodically subjecting the sludge (or a portion of it) to endogenous respiration in the presence of an exogenous source of nitrogen. Further study of this system led to a modification of the activated sludge process for nitrogen-deficient wastes. However, it was not known whether renewal of oxidative assimilation capacity was possible for substrates which required the presence of inducible enzyme(s) or for substrates which were not carbohydrates. Therefore, studies with lactose and acetate as carbon sources were designed. Both carbon sources were removed under conditions of oxidative assimilation, and the storage products (or a portion of these products) were converted into protein when the sludge was subjected to a period of endogenous respiration (with respect to carbon source) in the presence of an exogenous supply of ammonium sulfate. The “regenerated” sludge exhibited a renewed capacity for oxidative assimilation, thereby indicating that requisite inducible enzymes (e.g., β-galactosidase in the case of lactose; iso-citritase and malate synthetase in the case of acetate) were not diluted out in the endogenous phase to a degree sufficient to hamper renewed oxidative assimilation capacity. The results also indicated that a noncarbohydrate carbon source can be successfully removed from the medium with this process. However, in the case of acetate, the oxidative assimilation capacity after “regeneration” was not fully restored to the initial level.
Extracellular Proteinases of Yeasts and Yeastlike Fungi
Authors: Ahearn D. G. , Meyers S. P. , Nichols R. A.
Published: December 2020

Approximately 800 yeasts and other fungi, representing over 70 species, were tested for extracellular caseinolysis. Isolates of a variety of genera, including
Aureobasidium, Cephalosporium, Endomycopsis, Kluyveromyces
, and numerous sporobolomycetes, demonstrated significant proteolytic activity. Caseinolysis was not necessarily correlated with gelatin liquefaction or with albuminolysis. Numerous fungi showed significant proteolysis at 5 C. The most active organisms were isolates of
Candida lipolytica, Aureobasidium pullulans, Candida punicea
, and species of
Cephalosporium
. Taxonomic and ecological implications of proteolytic activity are discussed.
Automatic Sample Collector for Continuous Cultures
Authors: Eisler William J.
Published: December 2020

An automatic sample collector is described that samples growing cultures sequentially. It can be programmed to collect at preselected intervals (usually several hours apart) for a prescribed period (usually from minutes to hours). Samples are collected serially but during intermediate time periods; when the sample is not required, it is disposed of by diverting it into a discard reservoir. This device collects culture samples on a predetermined schedule and stores them under refrigeration for study at a later time.
Damage to
Escherichia coli
on Exposure to Moist Heat
Authors: Russell A. D. , Harries Diann
Published: December 2020

The effects of temperatures of 50 to 60 C on suspensions of a strain of
Escherichia coli
are described. At these temperatures, the substances which leaked from the cells were determined as pentoses; the amount leaked over a 30-min period increased with increasing temperature. The leakage materials from suspensions heated in water, sodium chloride, sucrose, and sucrose plus Mg
++
were examined spectrophotometrically, and the ratios of the absorbances at 280 and 260 nm (the 280 to 260 nm ratio) were determined. It was not possible to determine protein by this method, as the ratio was always <0.7. When saline was the suspending medium, the ratio was lower than when water was used, and there was a greater leakage of 260 nm absorbing material. When suspended in sucrose or in sucrose plus Mg
++
, penicillin-induced spheroplasts did not undergo lysis, but became less regular in shape, and there was an increase in the extinction at 500 nm. The overall effects of high temperatures on nonsporeforming bacterial cells are discussed; in view of the available evidence, it is concluded that ribonucleic acid degradation is an event which is probably closely related to thermally induced bacterial death.
Inactivation of Poliovirus Type 1 by the Kelly-Purdy Ultraviolet Seawater Treatment Unit
Authors: Hill William F. , Hamblet Frederick E. , Benton William H.
Published: December 2020

Three experiments were conducted to determine the effect of ultraviolet (UV) radiation on poliovirus-contaminated seawater. In two of the experiments, the effectiveness of the Kelly-Purdy UV Seawater Treatment Unit to inactivate poliovirus type 1 (T
1
) suspended in continuously flowing seawater was determined. In experiment 1, the observed survival ratio of poliovirus T
1
was 2.3 × 10
-4
(99.98% reduction) in 15.7 sec. No virus was detected (<0.2 plaque-forming unit/ml) in 20.6 seconds. The calculated half-life value was 1.29 sec. In experiment 2, the observed survival ratio of poliovirus T
1
was 5.9 × 10
-4
(99.94% reduction) in 11.7 sec. No virus was detected in 15.7 sec. The calculated half-life value was 1.37 sec. In experiment 3, a laboratory-controlled UV experiment designed to closely simulate the geometry of the continuously flowing seawater system, the observed survival ratios of poliovirus T
1
were 9.7 × 10
-3
(99.03% reduction) and 3.6 × 10
-4
(99.96% reduction) in 15 and 30 sec, respectively; the calculated half-life value was 2.38 sec. A statistically significant difference was found between the inactivation rates of poliovirus T
1
in the two test systems. This rate difference was attributed primarily to UV dosage and stirring effects. The data indicated that UV radiation effectively inactivated poliovirus T
1
in flowing seawater. These results validate the efficacy of the Kelly-Purdy UV Seawater Treatment Unit for use in commercial depuration systems.
Effects on Growth and Toxin Production of Exposure of Spores of
Clostridium botulinum
Type F to Sublethal Doses of Gamma Irradiation
Authors: Williams-walls N. J.
Published: December 2020

Spores of the Langeland strain of
Clostridium botulinum
type F were grown at 30 or 10 C after exposure to 0.0, 0.1, or 0.2 megarad of cesium-137 gamma irradiation. When incubated at 30 C, cultures irradiated at the 0.2-megarad level reached the stationary growth phase 15 hr earlier than the 0.0 or 0.1 megarad-irradiated cultures. This was not the result of earlier or more frequent germination of the irradiated spores, the formation of larger individual cells, filament formation, or cell clumping. It appeared to result from elimination of a lytic phenomenon noted in 0.0 and 0.1 megarad-irradiated cultures after 26 and 29 hr of incubation, respectively, which was followed by a second exponential-growth response 5 hr later in these cultures. The time of toxin appearance in culture supernatant fractions was independent of prior irradiation treatment and occurred after 36 hr of incubation. Toxin release was essentially logarithmic until maximal titers were reached and maximal toxin titers were higher in irradiated than in unirradiated cultures. The higher toxin level was sustained over a period of 23 days of 30 C. Toxin produced in the 30 C cultures could not be trypsin-activated. An incubation temperature of 10 C resulted in no outgrowth of spores subjected to 0.2 megarad of irradiation, although spore germination did occur. At 10 C, outgrowth of the 0.1-megarad culture was faster with slightly higher quantities of a more stable toxin than was seen in the unirradiated control. At 10 C, trypsinization was necessary to demonstrate the toxin present in the cultures.
Oxygen-tolerant Strain of
Chlorella sorokiniana
Authors: Wagner Fred W. , Welch B. E.
Published: December 2020

An oxygen-tolerant strain (OTS) of
Chlorella sorokiniana
was isolated by growing and continuously subculturing the oxygen-sensitive strain (OSS) in growth medium bubbled continuously with 95% O
2
-5% CO
2
. Under these conditions, 6 to 8 hr were required before the OSS began to grow. The growth rates of the OTS and the OSS were the same when grown in an atmosphere of air-5% CO
2
, and the growth rate of the OTS was the same when aerated with 95% O
2
-5% CO
2
and air-5% CO
2
. The adaptive process was irreversible since serial transfers of the OTS grown with air-5% CO
2
did not alter the ability of the OTS to grow with 95% O
2
-5% CO
2
. Inasmuch as photosynthesis in the OTS and the OSS was inhibited to a similar extent by oxygen and the adaptive process occurred heterotrophically in the absence of photosynthesis, it was concluded that the adaptive process was independent of photosynthesis. Morphological differences between the OTS and the OSS are presented and discussed with respect to the adaptive process.
Laboratory Identification of
Rothia dentocariosa
and Its Occurrence in Human Clinical Materials
Authors: Brown June M. , Georg Lucille K. , Waters Linda C.
Published: December 2020

Fifty isolates of
Rothia dentocariosa
from diverse clinical sources were characterized by 28 separate tests. An attempt was made to select practical tests that could be completed in a minimal length of time.
Rothia
is also compared with
Actinomyces
and
Nocardia
with which it is often confused. Of the isolates 100% were positive in the following reactions: catalase production, nitrate and nitrite reduction, esculin hydrolysis, and acid production from glucose, sucrose, maltose, salicin, and glycerol. The importance of recognizing this organism is based on the fact that it is frequently isolated from human clinical materials and must be differentiated from morphologically similar organisms of the genera
Actinomyces
and
Nocardia,
which contain pathogenic members.
Immunological Properties of Friend Virus from Mouse Spleen Obtained by Gel Filtration
Authors: Chan S. P. , Chirigos M. A. , Hook W. A.
Published: December 2020

Gel filtration, with Sephadex G-200, was utilized to obtain Friend virus (FV) from infected spleen homogenate. Highly infectious and immunologically active material was eluted as a large initial protein peak, whereas hemoglobin and other noninfectious materials were found in two subsequent peaks. Fractions that made up the first peak were reactive in serological tests with antiserum towards FV. Formalinized fractions from the first peak, when combined with Freund's complete adjuvant, were able to protect mice against subsequent FV challenge. Further purification of antigen was carried out by sucrose gradient ultracentrifugation.
Vacuum Probe: New Approach to the Microbiological Sampling of Surfaces
Authors: Whitfield W. J. , Beakley J. W. , Dugan V. L. , Hughes L. W. , Morris M. E. , McDade J. J.
Published: December 2020

The need for a device to sample large areas that are lightly contaminated with microorganisms motivated the development of the vacuum probe. The intended use of the instrument is to sample clean surfaces in laminar flow clean rooms, but the device could be used for sampling surfaces in other clean environments. Such a device was designed, fabricated, and tested at Sandia Laboratories, Albuquerque, N.M. In these tests, the vacuum probe removed a mean of 89% and assayed a mean of 67% of bacterial spores, approximately 1 μm in length, settled on smooth surfaces which were free from viscous films.
Method for Testing Virus Stocks for Viral Contaminants
Authors: Hampil Bettylee , Melnick Joseph L.
Published: December 2020

A practical method for testing the purity of virus stocks has been developed and applied to reference stocks of enteroviruses. The method requires the use of a reference antiserum that is substantially free from heterotypic antibody. When selected dilutions of this antiserum are reacted with high concentrations of virus, virus intentionally allowed to escape neutralization is recovered and then identified. A contaminating virus present as a minor component of the population has a far greater probability of being revealed under the conditions of this “breakthrough” test than under the commonly used virus identity tests which customarily employ approximately 100 TCD
50
of virus and, therefore, only identify the major component of the virus population. The breakthrough test described has been used for tests of 104 reference stocks of all the enteroviruses that propagate in monkey kidney cells and human amnion cells. Although all the materials had been previously tested and approved by the commonly employed virus identity test, the breakthrough test in two instances revealed contaminating heterotypic enteroviruses present at a very low titer in the stocks. Without resorting to the stringent, elaborate, and expensive tests for absolute purity, such as those that are required to assure safety of vaccines, the use of the breakthrough test described provides reasonable assurance of purity for stock viruses to be employed as diagnostic reagents or for general laboratory research purposes where a multiplicity of viral agents and antisera are required.