bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Reagent-impregnated Paper Strips and Conventional Tests for Distinguishing
Escherichia
from
Aerobacter
: Correlation with Colonial Morphology
Authors: Amsterdam Daniel , Wolfe Marian W.
Published: December 2020

The means for distinguishing
Escherichia
from
Aerobacter
(
Enterobacter
) differ in laboratories and range from complete dependence on colonial reactions on typical gram-negative media to reliance on one or more of the classical indole, methyl red, Voges-Proskauer, citrate (IMViC) parameters. Three colonial types (one prejudged as
Escherichia
) of lactose-positive rods were catalogued on each of the most commonly used selective media, MacConkey Agar, Endo Agar, and E M B Agar. Each cultural type was presumptively diagnosed and then compared with the expected outcome of individual IMViC tests. The distribution of preliminary identifications was similar from growth patterns on MacConkey Agar and E M B Agar, but it differed markedly from Endo Agar. When organisms initially diagnosed by cultural methods were compared by single IMViC tests, it was found that for each colonial type one of the biochemical parameters was best suited. Thus, for those types initially considered
Escherichia
, the methyl red or Voges-Proskauer test results agreed most consistently; for other types, the citrate reaction was most satisfactory. In addition, when newly formulated reagent-impregnated paper strip methods for indole, Voges-Proskauer, and citrate were evaluated and compared to the standard methods, agreement was 97% for indole, 90% for Voges-Proskauer, and 95% for Simmons' citrate.
Evaluation of a Commercial Air Filter for Removal of Virus from the Air
Authors: Roelants P. , Boon B. , Lhoest W.
Published: December 2020

The effectiveness of a commercial absolute air filter for removal of viruses from air was tested with an actinophage, under the usual conditions of a laminar airflow clean room. A new method of dry phage dispersion is described. The filter showed an average reduction of 99.996% of airborne actinophage.
Agar Diffusion Method for the Assay of Colicins
Authors: Richardson H. , Emslie-Smith A. H. , Senior B. W.
Published: December 2020

An agar diffusion method for the assay of colicins A, B, D, E
2
, E
3
, and K is described. The assays were performed in large, square pyrex dishes that contained an agar layer seeded with an indicator organism sensitive to the colicin. The samples were applied to the agar in steatite beads positioned in a randomized sequence. The plates were stored at 4 C for 24 hr to allow the colicins to diffuse into the agar. After incubation at 37 C, the activity of each colicin preparation was estimated by measuring the diameter of the zone of inhibition of the growth of the indicator strain around each bead. The results of each assay were subjected to a statistical analysis, which included an analysis of variance and calculation of the theoretical regression and the confidence interval of the assay. The size of the inhibition zones, the form of the regression, and the slope of the regression of the responses were affected by the type and concentration of the agar, the depth of the agar layer, the indicator organism, the indicator inoculum density, and the time allowed for prediffusion of the colicins. Optimal conditions for the assay of each colicin were determined. Using a four-point assay design, the relative colicin concentration of unknown preparations was estimated in terms of a standard preparation of the same colicin. The experimental error of these assays (95% confidence interval) was about ± 10%.
Simple Method to Remove Completely Ciliate Protozoa of Adult Ruminants
Authors: Akkada A. R. Abou , Bartley E. E. , Berube R. , Fina L. R. , Meyer R. M. , Henricks D. , Julius F.
Published: December 2020

Dioctyl sodium sulfosuccinate (Aerosol OT) has been used in a remarkably short period to obtain rumen ciliate-free cows. Two 30-g doses of Aerosol OT given on consecutive days appeared to effectively eliminate all types of rumen ciliate protozoa without harming the health of the host animal. Measurement of the rumen metabolic parameters of gas production, carbon dioxide to methane ratio,
p
H value, volatile fatty acids, ammonia, and in vitro cellulose digestion, along with total amylolytic streptococci counts of the rumen contents, showed that conditions in rumens of defaunated animals are normal 4 days after such treatment. It appears that such animals may be used in ruminal studies that require defaunated animals.
Evaluation of Laminar Flow Microbiological Safety Cabinets
Authors: Staat Robert H. , Beakley John W.
Published: December 2020

The microbiological control efficiency of two class 100 laminar down-flow hoods was determined by using aerosols of
Bacillus subtilis
var.
niger
spores. The first unit challenged utilized a slanted eyelid to partially enclose the front work opening. This hood showed nearly perfect control of ambient organisms in the work area. It also gave a 10
6
or greater drop in the number of organisms passing out of the exhaust system. However, when the interior work area of the hood was challenged, significant numbers of spores penetrated the air barrier and escaped into the ambient air. A redesigned laminar flow hood was built incorporating a vertical eyelid and a reduced opening to the work area. This hood showed the same excellent characteristics for controlling ambient contamination. Exhaust system leakage was also extremely low. Air barrier efficiency for the newer hood was increased with lower amounts of spore penetration into the ambient air.
Production of Bacteriophage T7
Authors: Sargeant K. , Yeo R. G. , Lethbridge J. H. , Shooter K. V.
Published: December 2020

Bacteriophage T7 was grown with
Escherichia coli
B as the host organism in 3- and 20-liter vessels. Under the best growth conditions devised, the yields of T7 in the culture lysates averaged 1.33 × 10
12
and 0.95 × 10
12
plaque-forming units per ml, respectively, compared with the best previously reported yields of 10
11
to 3 × 10
11
plaque-forming units per ml in 1-liter batches grown in the presence of air, or double this in similar batches grown in the presence of oxygen. The bacteriophage was purified by a simple method which gave average yields of 143 mg/liter and 131 mg/liter from the 3- and 20-liter batches, respectively. The efficiency of plating of the final material ranged from 18 to 42%. The purified bacteriophage is a convenient source of monodisperse deoxyribonucleic acid, the molecular weight of which is about 25 × 10
6
.
Diagnostic Criteria for Differentiation of Pseudomonads Pathogenic for Man
Authors: Gilardi Gerald L.
Published: December 2020

To determine the most useful diagnostic characters for the differentiation of pseudomonads pathogenic for man, including
Pseudomonas maltophilia
(
Alcaligenes bookeri
),
P. stutzeri
(
Bacillus denitrificans
),
P. pseudomallei
(
Malleomyces pseudomallei
), and apyocyanogenic strains of
P. aeruginosa
, a comparative examination was made of 58 strains of these bacilli for their morphological and biochemical characteristics. It was concluded that the criteria for differentiating these bacteria are type of flagellation, growth on S S Agar, fluorescein production, oxidation of carbohydrates in the medium of Hugh and Leifson, nitrogen gas production, gluconate oxidation, gelatinase activity, urease activity, lysine decarboxylase activity, arginine dihydrolase activity, oxidase reaction, sensitivity to polymyxin, requirement for methionine as a growth factor, and assimilation of organic compounds as the sole source of carbon and energy.
Routine Identification of Yeasts with the Aid of Molybdate-Agar Medium
Authors: Bump Charles M. , Kunz Lawrence J.
Published: December 2020

A large number of yeasts, including a variety of species other than
Candida albicans
, were isolated from clinical specimens.
C. tropicalis
and
Torulopsis glabrata
were each found one-third as frequently as
C. albicans
. A schema is presented which made possible, by simple procedures, the identification of the great majority of the isolated yeasts. Preliminary isolation and differentiation was aided by the use of molybdate-agar medium. The use of the schema by diagnostic bacteriological laboratories is discussed.
Synergistic Antibacterial Activity of Ampicillin-Cloxacillin Mixtures Against
Proteus morganii
Authors: Bornside George H.
Published: December 2020

Synergistic antibacterial effects of mixtures of ampicillin and cloxacillin and induced penicillinases were investigated in 48 strains of
Proteus
. The serial tube dilution method was used to determine the minimal inhibitory concentration of ampicillin, cloxacillin, and 2:1 and 1:1 mixtures of ampicillin and cloxacillin. Production of penicillinases was determined by the cellulose acetate membrane method, with ampicillin, cloxacillin, mixtures of ampicillin and cloxacillin, penicillin G, and cephalothin as inducing agents and as substrates for penicillinase. Synergism occurred against
P. morganii
, but against no other species. The 1:1 ampicillin-cloxacillin combination was synergistic against 13 of 17
P. morganii
strains; the 2:1 combination was synergistic against only 9 strains. Penicillinases, demonstrated in all species except
P. mirabilis
, hydrolyzed penicillin G and cephalothin. Although only
P. vulgaris
hydrolyzed ampicillin, no species of
Proteus
hydrolyzed cloxacillin or the ampicillin-cloxacillin mixtures. Penicillinases were, however, induced by ampicillin, cloxacillin, and the mixtures. There was no relationship between production of penicillinase and synergism with mixtures of ampicillin and cloxacillin.
Thermal Energy Interchange During Anaerobic Methane Fermentation of Waste Organic Substrates
Authors: Pohland F. G.
Published: December 2020

An experimental calorimeter-type anaerobic fermentation system was developed to evaluate the extent of thermal energy interchange during anaerobic digestion of waste organic solids at 36 C. Results over a period of 184 days indicated that the energy released during conversion of the waste substrate was utilized primarily for the production of CH
4
and that any excess released as heat during normal digestion was not sufficient to overcome heat losses from the system. The more exothermic response observed during retarded digestion was attributed to the accumulation of volatile acids and associated reduction in gas yields. After combustion of the CH
4
produced during digestion, between 2,370 and 3,950 kcal per lb of volatile solids converted per day was available for heating the process and maintaining optimal temperature conditions.
Methods for Detecting Food-borne Enteroviruses
Authors: Herrmann John E. , Cliver Dean O.
Published: December 2020

A method previously reported for detecting virus in a model system composed of cottage cheese contaminated with coxsackievirus type A9 has been adapted to detecting selected strains of enteroviruses in a variety of foods. Bentonite is omitted and serum is added for extracting virus from low-protein foods. Samples of foods, usually 25 g, must contain at least 3 to 4 plaque-forming units for a 50% probability of detecting virus. Sensitivity in detecting echovirus type 6 was lower than that for the other viruses used. After extraction from potato salad, poliovirus type 2 was completely reactivated if it had been neutralized with coproantibody, but it was only partially reactivated if neutralized with hyperimmune rabbit serum.
Standardized, Automated Procedure for Measurement of Serum Hemolytic Complement Activity
Authors: Olitzky I.
Published: December 2020

In the interest of standardizing and automating complement fixation procedures, an AutoAnalyzer manifold was designed in which the reagents are mixed in proportions similar to that of the Laboratory Branch Complement Fixation test. By bypassing the fixation stage, the manifold proved useful for measuring serum hemolytic complement activity (C′). As many as 21 serum samples per hour can be screened by testing two appropriate dilutions. Normal adult C′ titers measured by the automated procedure ranged from 58 to 103 C′H
50
units per ml.
Effect of Inoculum Size on In Vitro Susceptibility Testing with Lincomycin
Authors: Shadomy Smith , Bruce Judith L. , Kannan Mickael M.
Published: December 2020

There is disagreement in the literature as to whether lincomycin is primarily a bacteriostatic or a bactericidal agent against gram-positive cocci and also regarding the levels of activity of this agent against susceptible microorganisms. These questions were examined in a study of the effect of inoculum size on the results of tube dilution susceptibility determinations with lincomycin against 49 clinical isolates of
Staphylococcus aureus
and 25 strains of streptococci and pneumococci. Lincomycin was both highly active and bactericidal when tested against 40 strains of
S. aureus
with inocula containing a maximum of 10
4
cells per ml [median minimal inhibitory concentration (MIC), 0.78 μg/ml; median minimal bactericidal concentration (MBC), 1.56 μg/ml]. With inocula of 10
5
cells per ml, lincomycin was primarily bacteriostatic (median MIC, 1.56 μg/ml; median MBC, 12.5 μg/ml). There were further decreases in inhibitory levels and significant losses of bactericidal activity when inocula containing more than 10
7
cells were tested (median MIC, 3.13 μg/ml; median MBC > 100 μg/ml). Similar measurements with streptococci and pneumococci revealed a lesser effect of inoculum size. The mean MBC value for α-hemolytic streptococci increased from 0.40 to 1.05 μg/ml with an increase in inocula from 10
4
to 10
6
cells per ml, but without a marked increase in MIC values. Similar results were obtained for β-hemolytic streptococci and pneumococci.
Carbenicillin: Activity In Vitro and Absorption and Excretion in Normal Young Men
Authors: Smith Charles B. , Finland Maxwell
Published: December 2020

Carbenicillin is a new semisynthetic penicillin which differs from other penicillins in showing moderate antibacterial activity against
Pseudomonas
. Its activity in vitro is enhanced at low
p
H. Serum binding is of low order and does not appreciably alter activity. Strains of
Pseudomonas
exposed to subinhibitory concentrations of carbenicillin rapidly develop resistance by a mechanism that does not depend upon destruction of the drug. In normal subjects, high levels of anti-
Pseudomonas
activity are readily obtained in the urine after intramuscular injection. Levels of carbenicillin adequate to inhibit many strains of
Pseudomonas
can be achieved in serum only with an intravenous administration of a large dose. Carbenicillin appears to exhibit the same low degree of toxicity as do other penicillins.
Thermal Injury and Recovery of
Streptococcus faecalis
Authors: Clark Carol W. , Witter Lloyd D. , Ordal Z. John
Published: December 2020

Exposure of
Streptococcus faecalis
R57 to sublethal heating produced a temporary change in the salt tolerance and growth of the organism. After sublethal heat treatment at 60 C for 15 min, greater than 99.0% of the viable population was unable to reproduce on media containing 6% NaCl. In addition, the heated cells displayed a sensitivity to incubation temperature,
p
H, and 0.01% methylene blue. When the injured cells were placed in a synthetic medium, recovery occurred at a much slower rate than in a complex medium. However, both media supported comparable growth of the uninjured organism. Various media used for the enrichment of streptococci also provided a suitable environment for the recovery of the injured cells. Generally, as more selective agents were present in the medium, the rates of recovery decreased. Metabolic inhibitor studies with chloramphenicol, penicillin, and actinomycin D substantiated the fact that the process involved was recovery and not growth, and that this recovery was linked to ribonucleic acid synthesis.
Response of the
Mimeae
to some Physical and Chemical Agents
Authors: Snodgrass Charlotte J. , Koburger J. A.
Published: December 2020

Isolates of
Mima polymorpha
and
Herellea vaginicola
obtained from retail food products were investigated for their ability to hydrolyze proteins, starch, and lipids as well as for their ability to initiate growth under varying conditions of
p
H, sodium chloride concentration, and temperature. None of the isolates hydrolyzed starch and a few hydrolyzed proteins, whereas most were actively lipolytic. Members of each genus grew over the range 6 to 42 C; in general,
H. vaginicola
was more tolerant to high concentrations of sodium chloride and to acid conditions than was
M. polymorpha
.
Resistance of Spores of
Bacillus subtilis
var.
niger
on Kapton and Teflon Film to High Temperature and Dry Heat
Authors: Bruch Mary K. , Smith Frederick W.
Published: December 2020

To determine parameters that would assure sterility of a sealed seam of film for application in “split-seam entry,” spores of
Bacillus subtilis
var.
niger
were sprayed onto pieces of Kapton and Teflon film. Short-time, high-temperature (200 to 270 C) exposures were made with film pieces between aluminum blocks in a hot-air oven, and the
D
and
z
values were determined after subculture of surviving spores. The use of Kapton film allowed the study of high temperatures, since it is not heat sealable and could be used to make thin packages for heat treatment. Spores on Teflon were dry-heat treated in a package designed to simulate an actual seam to be sealed. The
z
values of 29.1 C (52.4 F) for spores on Kapton and 139 C (250.4 F) for spores on Teflon were calculated.
Screening of Feed Components for Salmonella with Polyvalent H. Agglutination
Authors: Barkate John A.
Published: December 2020

The application of polyvalent H serology for screening certain feed components for
Salmonella
was evaluated. In a comparative study of 1,894 suspicious or known positive samples,
Salmonella
organisms were detected in 1,141 samples with the conventional method and in 1,134 samples with the polyvalent H method. A statistical analysis of the results obtained by both methods indicated that the polyvalent H method is as reliable as the conventional method. Salmonellae can be detected by this method within 60 hr, whereas conventional methods require at least 4 days. The speed and reliability of the polyvalent H method are desirable for routine quality assurance.
Antimicrobial Evaluation of 1-Methyl-3-Nitro-1-Nitrosoguanidine
Authors: Hunt D. E. , Pittillo R. F.
Published: December 2020

1-Methyl-3-nitro-1-nitrosoguanidine was shown to have in vitro antimicrobial activity against fungi and gram-positive and gram-negative bacteria; it was also shown to have in vivo activity in mice experimentally infected with
Staphylococcus aureus
or
Escherichia coli
comparable to that observed with penicillin or streptomycin sulfate.
Bacteriology of Manganese Nodules
Authors: Ehrlich H. L.
Published: December 2020

A cell-free extract from
Arthrobacter
37, isolated from a manganese nodule from the Atlantic Ocean, exhibited enzymatic activity which accelerated manganese accretion to synthetic Mn-Fe oxide as well as to crushed manganese nodule. The reaction required oxygen and was inhibited by HgCl
2
and
p
-chloromercuribenzoate but not by Atebrine dihydrochloride. The rate of enzymatic action depended on the concentration of cell-free extract used. The enzymatic activity had a temperature optimum around 17.5 C and was destroyed by heating at 100 C. The amount of heat required for inactivation depended on the amount of nucleic acid in the preparation. In the cell-free extract, unlike the whole-cell preparation, peptone could not substitute for NaHCO
3
in the reaction mixture. An enzyme-containing protein fraction and a nucleic acid fraction could be separated from cell extract by gel filtration, when prepared in 3% NaCl but not in seawater. The nucleic acid fraction was not required for enzymatic activity.
New Turbidimetric Device for Measuring Cell Concentrations in Thick Microbial Suspensions
Authors: Fujita Teruyuki , Nunomura Kazuko
Published: December 2020

A photoelectric turbidimeter is described for use in measuring cell concentrations in thick suspensions. Its sample cuvette provides a path length continuously adjustable between 0.01 and 20.00 mm. By reducing the path length, it is possible to measure the optical density in thick cell suspensions without dilution. Moreover, the method described is rapid and simple, and only small amounts (less than 1 ml) of cell suspensions are required. The method is applicable to cell concentrations ranging up to 10
9
/ml for yeast.
Transglycosyl-Amylase of
Candida tropicalis
Authors: Nakamura Lawrence K. , Smiley Karl L.
Published: December 2020

Transglucosyl-amylase was purified 96-fold and partially characterized. The
K
m
value with dextrin as substrate was 9.1 mg/ml. Glycerol, an acceptor of
d
-glucose, appeared to inhibit dextrin hydrolysis noncompetitively. The energy of activation of the enzyme was 7,920 cal/mole. Indirect determinations showed that synthesis of
d
-glucosyl glycerol was significantly affected by the nature of the amylaceous substrate. Glucosyl-glycerol synthesis did not increase as incubation temperature was raised from 50 to 60 C. Direct determinations by gas-liquid chromatography indicated that the synthesis of glucosyl glycerol, as a function of the concentration of either enzyme, substrate, or glycerol, traced a curvilinear path approaching 15 mg/ml as the maximum. When enzyme, substrate, and glycerol at high concentrations were varied in all possible combinations, however, conditions for producing as much as 47.5 mg/ml of glucosyl glycerol were established.
Interaction of Staphylococcal Penicillinase and 6-[D(—)-α-Guanidino-Phenylacetamido]-Penicillanic Acid
Authors: Thiele Elizabeth H. , Robinson Harry J.
Published: December 2020

6[
d
(—)-α-Guanidinophenylacetamido]-penicillanic acid was shown to be significantly hydrolyzed by only one of six preparations of staphylococcal penicillinase. This penicillin analogue is a stronger penicillinase inactivator than are nafcillin and methicillin, which were not significantly hydrolyzed by the enzyme.
Improvement of a Continuous-Culture Apparatus for Long-Term Use
Authors: Taub Frieda B. , Dollar Alexander M.
Published: December 2020

A glass and plastic apparatus was designed to meet requirements for continuous culture of cells. Some of the improvements incorporated into this apparatus include an all-glass growth vessel with a self-cleaning bottom, special compression fittings to connect tubing to glass tubing, a removable yield reservoir, and a nonwetting gas exhaust assembly. All portions of the system can be autoclaved for sterilization, and medium bottles and pump lines are replaced aseptically.

Images

Fig. 1
Synergism Between Hyperoxia and Antibiotics for
Pseudomonas aeruginosa
Authors: Brown Olen R. , Silverberg Robert G. , Huggett David O.
Published: December 2020

Three strains of
Pseudomonas aeruginosa
were directly exposed on the surface of membrane filters to hyperoxic atmospheres. One of the three strains was found to be sensitive to oxygen. Colonies failed to appear during 18 hr of incubation in pure oxygen at 1 atm, but about 40% of the bacteria recovered to produce colonies upon reincubation in air. Similar killing was produced by 10 hr of oxygen exposure. No inhibition or killing was observed with two other strains. Streptomycin (1μg/ml) and kanamycin (5μg/ml) were more effective in killing the oxygen-sensitive strain in the presence of 60 to 70% oxygen than in air, but polymyxin B (5μg/ml) did not show a synergistic effect under such conditions.
Microbiological Safety Evaluation of an Industrial Refuse Incinerator
Authors: Barbeito Manuel S. , Gremillion Gardner G.
Published: December 2020

An industrial refuse incinerator was tested to determine minimal operating temperatures required to prevent release of viable microorganisms into the atmosphere. A liquid suspension of
Bacillus subtilis
var.
niger
spores was disseminated into the firebox as an aerosol, and dry spores mixed with animal bedding were dumped into the firebox. The minimal requirement for wet spores was 575 F (302 C) for the firebox air temperature and 385 F (196 C) for the firebrick refractory lining. When dry spores were used, these temperatures were 700 and 385 F (371 and 196 C), respectively.
Production of
Clostridium pasteurianum
in a Defined Medium
Authors: Sargeant K. , Ford J. W. S. , Longyear V. M. C.
Published: December 2020

A method for the growth of
Clostridium pasteurianum
in a 140-liter (total capacity) stainless-steel vessel is described. By preventing the
p
H value from falling below 5.6, the growth of cultures was prolonged. Larger amounts of the carbon source (sucrose) and the nitrogen source (ammonium ion) were supplied and consumed, and cell yields of up to 5.56 g (dry weight) per liter were obtained. The highest cell yield previously reported was 1.7 g (dry weight) per liter obtained under nitrogen-fixing conditions in 500-ml cultures. The ferredoxin content of the cells was comparable with that obtained by earlier workers.
Penicillin-resistant Variants of Pneumococci
Authors: Gunnison Janet B. , Fraher Margaret A. , Pelcher Elisabeth A. , Jawetz Ernest
Published: December 2020

All of the 74 strains of pneumococci isolated from human infections from 1963 to 1964 proved to be uniformly and highly susceptible to penicillin. Of these strains, 15 were identified by capsule-swelling reactions and were submitted to serial transfer in the presence of increasing concentrations of penicillin. Highly penicillin-resistant mutants were selected from 14 of the 15 strains, whereas one strain was moderately resistant. Of these mutants, 11 could still react with specific antiserum, and all of the mutants could be identified by fermentation reactions and optochin inhibition. The in vitro development of penicillin resistance in these mutants did not result in a change in cell-wall composition sufficient to diminish bile solubility. The possibility of encountering rising penicillin resistance among pneumococci, as well as the possibility that such mutants may react atypically, should be kept in mind.
Association of Mucoid Encapsulated
Moraxella duplex
var.
nonliquefaciens
with Chronic Bronchitis
Authors: Bottone Edward , Allerhand Jona
Published: December 2020

The recovery of two strains of highly mucoid encapsulated
Moraxella duplex
var.
nonliquefaciens
from the sputum of two patients suffering from chronic bronchitis is described. The biochemical, morphological, and pathogenic characteristics of this microorganism are discussed.
Production of Alkaline Phosphatase from
Escherichia coli
in Continuous Culture
Authors: Sayer P. D.
Published: December 2020

A 2-liter continuous culture for the production of
Escherichia coli
rich in alkaline phosphatase is described. The maximal output is greater than 250 mg of enzyme per day. The enzyme yield per unit of bacterial dry weight is only one-fifth of that obtained in earlier investigations. However, because of the increased bacterial density, the output per unit volume of culture is more than four times as great.
Mutagens for Regeneration of an Antibiotic-producing Strain of
Aspergillus versicolor
Authors: Dhar A. K. , Bose S. K.
Published: December 2020

The individual colonies of a partially degenerated culture of
Aspergillus versicolor
vary widely in their ability to produce an antibiotic active against
Trichophyton rubrum
. Mutagenic treatment with nitrous acid or ultraviolet light gave potent colonies. Nitrous acid gave better results in terms of stability and yield. This treatment may therefore prove useful in the regeneration of partially degenerated cultures.
Role of Curing Agents in the Preservation of Shelf-stable Canned Meat Products
Authors: Duncan Charles L. , Foster E. M.
Published: December 2020

Experiments were conducted to gain a better understanding of the mechanism by which sodium chloride, sodium nitrate, and sodium nitrite supplement the action of heat in preserving canned cured meat products. Heated spores of putrefactive anaerobe 3679h were less tolerant of all three curing agents in the outgrowth medium than were unheated spores. When the curing agents were added to the heating menstruum, but not to the outgrowth medium, sodium chloride and sodium nitrate tended to protect the spores against heat injury, but sodium nitrite did not. When the spores were both heated and cultured in the presence of the curing agents: (i) nitrate and salt increased the apparent heat resistance at low concentrations (0.5 to 1%) but decreased it at concentrations of 2 to 4%; (ii) nitrite was markedly inhibitory, especially at
p
H 6.0. At the normal
p
H of canned luncheon meats (approximately 6.0), nitrite appears to be the chief preservative agent against spoilage by putrefactive anaerobes.
Effect of Sodium Nitrite, Sodium Chloride, and Sodium Nitrate on Germination and Outgrowth of Anaerobic Spores
Authors: Duncan Charles L. , Foster E. M.
Published: December 2020

The effects of meat-curing agents on germination and outgrowth of putrefactive anaerobe 3679h (PA 3679h) spores were studied in microcultures. Nitrite concentrations up to 0.06% at
p
H 6.0 or between 0.8 and 1% at
p
H 7.0 allowed emergence and elongation of vegetative cells but blocked cell division. The newly emerged cells then lysed. With more than 0.06% nitrite at
p
H 6.0 or more than 0.8 to 1% at
p
H 7.0, the spores lost refractility and swelled, but vegetative cells did not emerge. Even as much as 4% nitrite failed to prevent germination (complete loss of refractility) and swelling of the spores. Sodium chloride concentrations above 6% prevented complete germination (i.e., the spores retained a refractile core). In the presence of 3 to 6% sodium chloride, most of the spores germinated and produced vegetative cells, but cell division was often blocked. Sodium nitrate had no apparent effect on germination and outgrowth at concentrations up to 2%.

Images

Fig. 1

Fig. 2

Fig. 3
Protease Production by Species of
Entomophthora
Authors: Jönsson Arne G.
Published: December 2020

Ten insect-pathogenic species of
Entomophthora
showed wide variation in their ability to produce alkaline protease in surface culture.
E. coronata
, the most active producer, was selected for studies in submerged culture together with
E. virulenta
. All media tested appeared suitable for mycelial growth of these two organisms, but a liver medium was superior for the production of protease. The effect of the constituents of the liver medium upon yield was investigated. The lag between growth and the production of protease was 24 to 40 hr, and only very small amounts of protease were obtained from sonically treated mycelium. The
p
H values during growth rose from ranges of 4.5 to 7.5 in the initial medium to 7.2 to 7.9, and did not affect the final yields. The optimal temperature for the production of protease by
E. coronata
was 24 to 32 C, and good growth was observed at temperatures as low as 16 C. The process with
E. coronata
was scaled up to fermentors without a decrease in yield; 5 enzyme units/liter were obtained after approximately 33 hr. This corresponds to a maximal productivity of 0.45 enzyme unit per liter per hr during the protease-producing phase. The process was insensitive to changes in aeration rate. The liver in the medium was replaced by various agricultural by-products, meat scrap, rapeseed oil meal, cottonseed nutrients, milk powder, and meat hydrolysate, with approximately the same or higher yields of protease.
Duration of Prophylactic Effect of Statolon Against Mengovirus in Mice
Authors: Schmidt Jerome P. , Pindak Frank F.
Published: December 2020

Intraperitoneal injection of statolon into mice is known to exert a protective effect against a subsequent infection with a variety of viruses owing to stimulation of production of interferon. To study the duration of such protection, groups of mice were treated with 350 μg of statolon at 69, 55, 41, 27, 13, 6, or 1 day prior to a challenge with mengovirus. Other groups were treated with 760 μg at 1 to 6 days before challenge. Ten days after inoculation with the virus, LD
50
determinations were made for each group. Mice which received statolon 1 to 5 days before infection were significantly more resistant to the virus than nontreated controls; no protection could be demonstrated in the other groups.
Continuous-Dilution Method for the Mass Culture of Synchronized Cells
Authors: Hare T. A. , Schmidt R. R.
Published: December 2020

A new mass-culturing technique for synchronized cells is described. Continuous dilution with fresh culture medium provides the cells with nearly constant environmental conditions (continuous resupply of nutrients, constant adjustment of
p
H, maintenance of a nearly constant cell mass-to-culture volume ratio, etc.) at high cell densities, thereby resulting in the yield of ample cellular material for most biochemical studies during the cell cycle. The new mass-culturing system, when utilized to culture synchronous
Chlorella pyrenoidosa
, yielded approximately three times as much cellular material as a previous nondilution method, in the same time period and in less than one-tenth the culture volume. Although the newly developed mass-culture method was tested with a unicellular green alga, the basic method should be readily adaptable to synchronous cultures of other microorganisms and to cells in tissue culture.
Secondary and Apparent Primary Antibody Responses After Group A Streptococcal Vaccination of 21 Children
Authors: Massell Benedict F. , Michael J. Gabriel , Amezcua Jacqueline , Siner Myron
Published: December 2020

A partially purified M protein, extracted from a mouse-virulent strain of type 3, group A streptococcus, was administered subcutaneously in gradually increasing amounts at weekly intervals to 21 children in a Family Program. Seven children with type 3 bactericidal antibody in prevaccination sera showed a secondary response. Of 14 children with no detectable type 3 bactericidal antibody prior to vaccination, 13 developed definite type 3 antibody during or soon after vaccination. This response appeared to be of the primary variety in at least some of the 13 children because (i) the total incidence of antibody response (20 of 21) was greater than can be accounted for by the documented incidence of clinical and subclinical type 3 infections among children of our Family Program during a period of 14 years, (ii) the response in the 13 children with no detectable antibody prior to vaccination was more delayed than in those showing a definite secondary response, and (iii) on the average, the amount of vaccine needed for a response in these 13 children was 15 to 28 times greater than that required for the secondary response. Local skin reactions were variable among the vaccinated children. Systemic reactions were infrequent and not severe. The giving of multiple injections of partially purified M protein did not seem to cause cutaneous hypersensitivity.
Aerococcus viridans
in the Hospital Environment
Authors: Kerbaugh Mildred A. , Evans James B.
Published: December 2020

Aerococcus viridans
has been described as an airborne organism prevalent in occupied rooms. It has also been described as an organism having many characteristics that might cause it to be confused with streptococci or staphylococci, and this may account for the fact that the presence of
A. viridans
has not been reported in the hospital environment or in clinical specimens. Swab specimens were taken from 47 objects in 11 different areas in a local hospital, cultured overnight in Trypticase Soy Broth, and streaked on blood-agar and on a selective serum agar containing potassium tellurite and crystal violet. Of 85 α-hemolytic cultures isolated, 11 proved to be typical
A. viridans
based on diagnostic tests that also were applied to a collection of gram-positive cocci, including authentic strains of
A. viridans
. These organisms are gram-positive cocci with a strong tendency toward tetrad formation in broth cultures. They are predominantly aerobic, have a very weak catalase activity, and lack porphyrin respiratory enzymes. Three similar cultures also were obtained from routine clinical specimens.
A Simple Procedure for Detecting the Presence of Cyclopropane Fatty Acids in Bacterial Lipids
Authors: Brian Buford L. , Gardner Earl W.
Published: December 2020

Four gram-negative bacterial species, including
Escherichia coli
strain B,
Serratia marcescens, Pseudomonas fluorescens
, and
Vibrio cholerae
(
comma
) strain NIH 41, were investigated for fatty acid content by gas-liquid chromatography involving a preparatory technique which facilitated detection of cyclopropane fatty acids. Methyl esters of fatty acids were subjected to mild catalytic hydrogenation to eliminate unsaturates. Hydrogenation was followed by bromination which removed cyclopropane acids from chromatographic profile patterns. Lactobacillic acid (
cis
-11,12-methyleneoctanoate) and
cis
-9,10-methylenehexadecanoate, previously reported in lipids of
E. coli
and
S. marcescens
, were found in small amounts in
P. fluorescens
but were not detected in
V. cholerae
.
Incidence of
Clostridium botulinum
Type E in Salmon and Other Marine Fish in the Pacific Northwest
Authors: Craig James M. , Hayes Sidney , Pilcher K. S.
Published: December 2020

Salmon, sole, cod, oysters, clams, and crabs from ocean waters along the coast of Oregon and Washington were examined for the presence of
Clostridium botulinum
type E. The organism was detected by identification of the type E toxin in enrichment cultures of the viscera of individual fish. Of 369 salmon specimens, 48 yielded cultures containing toxin lethal to mice, and almost half of the toxic cultures were shown to contain botulinal toxin, chiefly type E. Eighteen of 113 sole and cod specimens, 4 of 22 Dungeness crab specimens, 5 of 16 oyster specimens, and 27 of 115 clam specimens gave rise to cultures containing botulinal toxin which was usually type E, although types A and B were occasionally encountered.
Effect of Dextrose in Medium for the Preparation of
Mycoplasma gallisepticum
Plate Antigens
Authors: Adler H. E. , Damassa A. J.
Published: December 2020

Antigens for
Mycoplasma gallisepticum
were prepared from organisms propagated in media with and without dextrose supplementation. The antigens made from organisms produced in medium enriched with dextrose were less sensitive than the others in slide agglutination tests.
Growth and Survival of Fuel Isolates in Hydrocarbon-Fuel Emulsions
Authors: Cooney J. J. , Edmonds Paul , Brenner Q. M.
Published: December 2020

Two fuel utilizers, a strain of
Pseudomonas aeruginosa
and a
Hormodendrum
sp., and two fuel isolates which did not use fuel,
Staphylococcus
and
Bacillus
spp., were tested for ability to survive and grow in systems containing emulsified or nonemulsified forms of JP-4 jet fuel. Neither emulsion (Alamac no. 1 or Alamac no. 2) supported microbial growth without a water phase. Growth of
P. aeruginosa
in liquid systems containing either emulsion was not significantly different from growth in liquid systems with nonemulsified fuel. The
Hormodendrum
sp. grew well in a liquid medium containing nonemulsified JP-4, but when either of the emulsions served as carbon source no growth was observed. However, good growth was noted on spread plates with either emulsion. Viable cells of
Bacillus
sp. did not increase over a 4-day period, and
Staphylococcus
sp. did not survive in liquid systems containing JP-4 or emulsions.
A New Plating Medium for the Isolation of Enteric Pathogens
Authors: King Sylvia , Metzger William I.
Published: December 2020

A new agar plating medium for the isolation of enteric pathogens is described. This medium contains greater quantities of peptone to offset the inhibitory effects of bile salts. Additional carbohydrates and larger quantities of those previously used have also been incorporated into the medium to differentiate pathogens from some of the slow lactose fermenters. The use of an indicator system never used before in a differential plating medium opens new possibilities for improvement over traditional and newer selective media. Known strains from the various genera of
Enterobacteriaceae
have been tested for colonial differentiation as well as for possible inhibitory effects. The results show the medium to be highly selective for the shigellae as well as for other enteric pathogens.
Biological Characterization of Prasinomycin, a Phosphorus-containing Antibiotic
Authors: Meyers Edward , Miraglia Gennaro J. , Smith Dorothy A. , Basch Harold I. , Pansy Felix E. , Trejo William H. , Donovick Richard
Published: December 2020

Prasinomycin, a new antibiotic from the green spore streptomycete,
Streptomyces prasinus
, primarily inhibits the growth of gram-positive microorganisms. Like penicillin, it is effective only against growing cells. Though primarily bacteriostatic at levels about the minimal inhibitory concentration, it is bactericidal at higher levels. Neither synergism nor antagonism could be demonstrated for prasinomycin with a variety of other antibiotics. It is highly active upon subcutaneous administration to mice infected with
Staphylococcus aureus, Streptococcus pyogenes
C203, or
Diplococcus pneumoniae
. Prasinomycin has a unique prophylactic action whereby one dose protects mice against experimental infections for as long as 2 months. It is more effective against
S. aureus
infections in mice when administered subcutaneously 20 hr prior to infection than when given in divided doses 1 hr before and 4 hr after infection.
Heat Sterilization of Water in a Large Open Vessel
Authors: Yale Charles E. , Linsley James G. , Anderson Lawrence C.
Published: December 2020

A safe, convenient, and economical method of preparing and dispensing a large volume of sterile water in a movable container is described. A caster-mounted, rectangular, 100-gal, stainless-steel water tank was fabricated. An audible, solid-state water-level alarm was developed for use with a detachable sensing probe that could be autoclaved. A filter system was constructed to allow the tank to be autoclaved as an open vessel. Thermocouples were mounted within the tank of water to study the time-temperature relationships of the water during the sterilization cycle. In a downward displacement autoclave with a hot jacket, 75 min were required for the water temperature to rise from 140 to 240 F (60 to 116 C). A total of 3 hr for heating and holding includes an adequate safety factor to insure the sterility of the water immediately after autoclaving. The long-term sterility of the water and the safety of the system were verified by using the water to maintain a germ-free animal colony.
Lipase Activity of
Mucor pusillus
Authors: Somkuti G. A. , Babel F. J.
Published: December 2020

Two strains of
Mucor pusillus
were examined for their ability to synthesize lipase in a complex medium used in the production of milk-clotting protease. Lipase activity of both strains reached maximal after 6 days of incubation under submerged conditions at 35 C. Lipase secreted into the medium hydrolyzed butterfat and vegetable lipids, as well as selected synthetic triglycerides. About 50% of lipase activity was destroyed after a 45-min heat treatment at 58 C.
Choline and Inositol Distribution in Algae and Fungi
Authors: Ikawa Miyoshi , Borowski Paul T. , Chakravarti Ashima
Published: December 2020

Inositol and choline were present in varying amounts among the species of
Rhodophyta, Phaeophyta, Chlorophyta
, and
Euglenophyta
examined. However, in the two members of the order
Fucales
(division
Phaeophyta
) examined, no detectable amounts of choline were found. In contrast, the species of
Cyanophyta
examined contained no detectable amounts of either choline or inositol. All species of the fungal classes
Phycomyceteae, Ascomyceteae
, and
Basidiomyceteae
collected contained both inositol and choline in varying amounts. The red, brown, and blue-green algae usually contained much less inositol and choline than do plant and animals sources, but the fungi and the algae
Chlorella
and
Euglena
contained amounts comparable to those present in plant sources.
Specific Identification of Fraction I-Positive
Pasteurella pestis
Colonies on Antiserum-Agar Plates
Authors: Albizo Johnnie M. , Surgalla Michael J.
Published: December 2020

A method is described for the use of antiplague serum in Blood Agar Base plating media to detect fraction I-positive
Pasteurella pestis
. The antiserum was produced conveniently and in large volume in rabbits by use of Cutter plague vaccine combined with Freund's complete adjuvant.
P. pestis
colonies were specifically identified within 48 hr after plating by the presence of a precipitin ring surrounding each colony. The basis of the test was shown to be a precipitin reaction between fraction I antigen released from
P. pestis
colonies after chloroform vapor treatment and fraction I antibody present in the antiserum-agar medium.
An Improved Diluent for Rubella Hemagglutination and Hemagglutination-Inhibition Tests
Authors: Auletta Angela E. , Gitnick Gary L. , Whitmire Carrie E. , Sever John L.
Published: December 2020

Rubella hemagglutinating (HA) antigen was prepared in BHK-21 tissue as 5% cell suspensions and from unconcentrated and 20× concentrated infected supernatant fluids. In some instances, unconcentrated fluids were treated with Tween 80 and ether; cell suspensions were treated with ether alone. Preparations were tested for HA activity in dextrose-gelatin-Veronal (DGV) buffer solutions; 0.85% NaCl; Sorenson's phosphate-buffered saline,
p
H 7.2; and a diluent of 0.9% NaCl, 0.1% CaCl
2
(anhydrous), and 0.1% MgSO
4
·7H
2
O. HA titers were consistently two- to fourfold higher in the saline with added Ca
++
and Mg
++
than in DGV. Hemagglutination-inhibition titers of paired human sera were the same in either diluent. It is suggested that the interaction between rubella HA antigen and the red cells of young (less than 1-day-old) chicks may be at least partially ion dependent and that titers are enhanced by increased quantities of divalent cations.
Correlation of Taxonomic Criteria for a Collection of Marine Bacteria
Authors: Johnson Roy M. , Katarski Mary E. , Weisrock William P.
Published: December 2020

Numerical taxonomy was done on 208 strains of marine bacteria. The collection was segregated into eight groups, seven of which contained
Vibrio
spp. Nucleic acid base ratio studies on a typical
Vibrio
sp. from each group and other genera were done. The phenotypically different
Vibrio
sp. had a narrow range of base ratios. The other genera had base ratios more similar to the base ratios reported for their genus than to each other as marine bacteria. The taxonomic groups are compared with generic classification and the strains' sources of isolations.
Lysis of Viable Rumen Bacteria in Bovine Rumen Fluid
Authors: Jarvis B. D. W.
Published: December 2020

Streptococcus bovis
and
Butyrivibrio
sp. were labeled with thymidine-methyl-
3
H, washed, and resuspended in rumen fluid or rumen fluid fractions obtained from Holstein and Jersey cows fed alfalfa hay once daily. Factors affecting the lytic activity found in untreated rumen fluid were examined. Day to day variation and differences before and after feeding were observed for the same cow. There were also differences between cows on the same day. For a given rumen fluid, the rate of release of label was roughly proportional to the number of labeled cells present over a 100-fold range in concentration. Removal of protozoa largely abolished the lytic action of fresh rumen fluid for
S. bovis
, but some soluble lytic activity remained. Mixed rumen protozoa added to media containing labeled
S. bovis
caused label to appear in solution. In a sample of rumen fluid containing 4.3 × 10
4
protozoa/ml 5.2% of the
S. bovis
population were destroyed by protozoa per hr. The mean rate of destruction for 12 runs on whole rumen fluid was 8.7% per hr with a standard deviation of 6.05. Parallel experiments with
Butyrivibrio
indicated that soluble lytic factors were more important for this organism. They could be destroyed by autoclaving and were generated when viable rumen bacteria were resuspended in autoclaved rumen fluid. The lysis of
S. bovis
and
Butyrivibrio
, at equal cell densities, by mixed rumen protozoa was compared in 30% rumen fluid media, and
Butyrivibrio
appeared to be more readily lysed than
S. bovis
.