bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct Quantitative Gas Chromatographic Separation of C
2
-C
6
Fatty Acids, Methanol, and Ethyl Alcohol in Aqueous Microbial Fermentation Media
Authors: Rogosa M. , Love L. L.
Published: December 2020

A method is described for the direct quantitative gas chromatographic separation of C
2
-C
6
lower fatty acid homologues, methanol, and ethyl alcohol in aqueous microbial fermentation media. A hydrogen flame detector and a single-phase solid column packing, comprising beads of a polyaromatic resin (polystyrene cross-linked with divinyl benzene), were employed. Direct injections of 1 to 10 μliters of aqueous culture supernatant fluids were made. Quantitative recoveries of C
2
-C
6
acids added to culture supernatant fluids were obtained.
Heat Inactivation of Enterotoxin A from
Staphylococcus aureus
in Veronal Buffer
Authors: Hilker J. S. , Heilman W. R. , Tan P. L. , Denny C. B. , Bohrer C. W.
Published: December 2020

Serological tests were used to determine the slope of the thermal inactivation curve of crude enterotoxin A in Veronal buffer (
p
H 7.2), and the resulting
z
value was 27.8 C. (50 F). Serological assays also showed that the heat inactivation at each time-temperature depended on the original concentration of enterotoxin A. The usefulness of the Oudin tube serological test for determining end points of inactivation of naturally produced enterotoxin A (not concentrated) is discussed. We concluded that this test cannot be used to determine end points of heat inactivation for enterotoxin A in the minute quantities naturally produced in foods.
Effects of Culture Conditions on Production of
trans
-Cinnamic Acid from Alkylbenzenes by Soil Microorganisms
Authors: Douros John D. , Frankenfeld John W.
Published: December 2020

The production of
trans
-cinnamic acid from various alkylbenzenes by soil microorganisms was studied intensively by use of a co-oxidation technique. The microorganisms were grown on
n
-paraffins, and they did not use aromatic compounds as a carbon source when the preferred substrate was present in the medium. The effects of cell population, co-oxidation time, and type and mode of addition of the alkylbenzenes on the yield of
trans
-cinnamic acid were investigated. Yields (5 g/liter) of a product consisting of
trans
-cinnamic acid (88 to 100%) and 5-phenylvaleric acid (0 to 12%) were obtained when the proper conditions were chosen. Of a variety of microorganisms studied, a soil isolate closely related to
Cellulomonas galba
was found to be best for the production of
trans
-cinnamic acid.
Factors Influencing the Survival and Revival of Heat-treated
Escherichia coli
Authors: Russell A. D. , Harries Diann
Published: December 2020

Maximal revival of heat-damaged
Escherichia coli
occurred in nutrient media containing 0.8 to 1.0% (w/v) of Difco yeast extract. Vitamins did not appear to be involved in the recovery process. The situation with amino acids was less clear-cut, and, although certain of these may be essential for revival, proof for this is as yet inconclusive. Replica plating, in which colonies (from cells which had survived a heating process) on a rich medium were replicated onto minimal agar, revealed that no auxotrophic mutants had been formed as a result of heat treatment. Bacteria which were heated in 1% (w/v) yeast extract were killed more slowly than those heated in water.
Preservation of Influenza Virus Infectivity by Lyophilization
Authors: Beardmore W. B. , Clark T. D. , Jones K. V.
Published: December 2020

A method of lyophilizing influenza virus in allantoic fluid with retention of high-titer of egg infectivity is described. Five strains of virus were lyophilized, and all were much more stable than fluid virus preparations, retaining 2 to 3 logs of infectivity after storage at 37 C for 60 to 95 days. Statistical analysis of an accelerated storage test by extrapolation of viral degradation indicates that the lyophilized viruses are stable indefinitely at or below room temperature.
Survival of Aerobic and Anaerobic Bacteria in Chicken Meat During Freeze-Dehydration, Rehydration, and Storage
Authors: Chipley J. R. , May K. N.
Published: December 2020

Total and anaerobic counts were ascertained on boneless, cooked, cubed, frozen chicken meat. We determined survival of aerobes and anaerobes in the natural flora after the meat was freeze-dehydrated and rehydrated at room temperature for 30 min and at 50, 85, and 100 C for 10 min. Total and anaerobic counts of bacteria in the rehydrated meat were established during storage of samples at 4, 22, and 37 C—until a spoilage odor was detected. Samples were also inoculated with
Clostridium sporogenes
and were dried and rehydrated at 100 C and stored at 37 C. Approximately 21% of the aerobes and 37% of the anaerobes survived drying and rehydration at room temperature. Many genera of aerobes, anaerobes, and facultative anaerobes survived drying and rehydration at 50 C; only sporeformers survived rehydration at 85 or 100 C. Low-temperature (4 C) storage of rehydrated meat produced ample shelf life (over 20 days), whereas storage at the higher temperature resulted in a shelf life of less than 30 hr. Approximately 81% of the
C. sporogenes
cells survived rehydration at 100 C and grew to over 10
7
cells within 40 hr. Our study presents additional data for adequate microbiological control in processing of freeze-dehydrated meat. Also, it points out the natural selection for sporeformers at high temperature of rehydration, stressing the need for consumer education in product handling for safety purposes.
Comparison of Titrations on the Chorioallantoic Membrane of Chick Embryos with the Rabbit Scarification Technique for the Potency Assay of Smallpox Vaccines
Authors: Fuller Vernon J. , Kolb Robert W.
Published: December 2020

The potency of the U.S. Reference Smallpox Vaccine, Lot 2, the International Reference Preparation of Smallpox Vaccine, and commercial smallpox vaccines was determined by the chorioallantoic membrane (CAM) and rabbit scarification (RS) potency assay methods. The mean titer of the U.S. Reference (based on 107 ampoules) was 10
8.1
pock-forming units (PFU) per ml and that of the International Reference (based on 3 ampoules) was 10
7.8
PFU/ml. A statistical analysis of the CAM data for the U.S. Reference resulted in the establishment of a table of limits of acceptance for smallpox vaccines. Of the commercial smallpox vaccines tested by the CAM and RS methods, 89% demonstrated potencies comparable to the U.S. Reference. Our results show that the CAM test method has application in the control testing of smallpox vaccines produced by U.S. licensed manufacturers provided it is used within the limits discussed.
Effect of Low-Frequency Ultrasound and Elevated Temperatures on Isolation of Bacteria from Raw Milk
Authors: Huhtanen C. N.
Published: December 2020

Treatment of milk with low-frequency ultrasound significantly increased the total bacterial counts and the counts of enterococci, coliforms, and staphylococci. Warming diluted milk for about 12 min at 30 or 40 C increased the counts of some organisms, but the heat produced by ultrasonic treatment did not account entirely for its effect. The ultrasonic effect was related to the energy output of the generator and to the energy absorbed by the treated materials.
Effects of Hyperoxia upon Microorganisms
Authors: Brown Olen R. , Huggett David O.
Published: December 2020

A membrane culture technique was developed for directly exposing microorganisms to test atmospheres. Inhibition and killing were calculated from comparisons with air-grown cultures. Direct colony counts were used with low inocula. With mass inocula, plate colony counts and optical-density measurements were made on resuspended filter populations. Bacteria, including
Escherichia coli
, were more sensitive to oxygen than previously reported. With inocula of a few hundred cells per membrane, five of seven species failed to produce colonies while exposed to oxygen at one atmosphere. Upon reincubation in air, the survival of five species ranged from near 0 to 12% of the cells.
Aerobacter aerogenes
was neither inhibited nor killed. With this technique, bacteria are in direct contact with the test atmosphere and cells which survive are detected but do not obscure the response of other cells in the population.
Assimilation of Alkanes and Alkenes by Fungi
Authors: Markovetz A. J. , Cazin J. , Allen J. E.
Published: December 2020

A group of filamentous fungi were assayed for their ability to utilize a series of
n
-alkanes and 1-alkenes as the sole source of carbon. Although strains of
Cunninghamella
exhibited profuse growth on most of the hydrocarbons tested, the majority of fungi tested were able to produce definite growth on one or more of the compounds. The hydrocarbons with a 14-carbon chain length appeared to be more consistently utilized than any other. Strains of
Aspergillus
appeared to differ in their capacity to utilize individual members of the hydrocarbon series. Thin-layer chromatographic analyses of ether extracts from
C. blakesleeana
grown on
n
-tetradecane and 1-tetradecene were similar and revealed the presence of a monocarboxylic acid, a primary alcohol, and a secondary alcohol.
Microbiological Evaluation of a Large-Volume Air Incinerator
Authors: Barbeito Manuel S. , Taylor Larry A. , Seiders Reginald W.
Published: December 2020

Two semiportable metal air incinerators, each with a capacity of 1,000 to 2,200 standard ft
3
of air per min, were constructed to sterilize infectious aerosols created for investigative work in a microbiological laboratory. Each unit has about the same air-handling capacity as a conventional air incinerator with a brick stack but costs only about one-third as much. The units are unique in that the burner housing and combustion chamber are air-tight and utilize a portion of the contaminated air stream to support combustion of fuel oil. Operation is continuous. Aerosols of liquid and dry suspensions of
Bacillus subtilis
var.
niger
spores and dry vegetative cells of
Serratia marcescens
were disseminated into the two incinerators to determine the conditions required for sterilization of contaminated air. With the latter organisms (concentration 2.03 × 10
7
cells/ft
3
of air), a temperature of 525 F (274 C), measured at the firebox in front of the heat exchanger, was sufficient for sterilization. To sterilize 1.74 × 10
7
and 1.74 × 10
9
wet spores of
B. subtilis
per ft
3
, the required temperature ranged from 525 to 675 F (274 to 357 C) and 625 to 700 F (329 to 371 C), respectively. Air-sterilization temperature varied with each incinerator. This was because of innate differences of fabrication, different spore concentrations, and use of one or two burners With dry
B. subtilis
spores (1.86 × 10
8
/ft
3
), a temperature of 700 F was required for sterilization. With dry spores, no difference was noted in the sterilization temperature for the two incinerators.
Glycerol Ester Hydrolase Activity of Lactic Acid Bacteria
Authors: Oterholm Anders , Ordal Z. John , Witter Lloyd D.
Published: December 2020

Seventeen strains of lactic acid bacteria were assayed for their glycerol ester hydrolase activity by using an improved agar-well technique, and eight strains by determining the activity in cell-free extracts using a
p
H-stat procedure. All cultures tested showed activity and hydrolyzed tributyrin more actively than they did tricaproin. The cell extract studies demonstrated that the cells contained intracellular esterases and lipases. The culture supernatant fluid was without activity. The lipase and the esterase differed in their relative activity to each other in the different extracts and in the ease by which they could be freed from the cellular debris. It is suggested that the lipase of these organisms is an endoenzyme and the esterase an ectoenzyme.
Replication and Plaque Assay of Influenza Virus in an Established Line of Canine Kidney Cells
Authors: Gaush Charles R. , Smith Thomas F.
Published: December 2020

A plaque assay system has been developed for types A and B influenza viruses in an established line of canine kidney cells (MDCK-USD). In addition to a homogeneous susceptible cell, consistent plaque production depends on the use of highly purified agar (Agarose). This quantitative system was used to determine the rate of adsorption, synthesis, and thermal inactivation of influenza viruses, as well as to determine a dose response curve. Plaque assays on the MDCK-USD line and the parent MDCK line showed that the latter was more sensitive to A/Swine and A
2
/Japan 305 viruses. Titration of standard virus pools in embryonated eggs and MDCK-USD indicated that the cell culture system was as sensitive as the in ovo assay.
Rapid and Sensitive Detection of Bacteria by Gas Chromatography
Authors: Mitruka B. M. , Alexander M.
Published: December 2020

A gas chromatograph fitted with electron capture and flame ionization detectors was employed for the rapid detection of bacteria by analysis for their metabolic products. The presence of
Proteus vulgaris, Streptococcus faecalis, S. liquefaciens, Escherichia coli
B,
Bacillus cereus
, and
B. popilliae
was detected in 2 to 4 hr in media inoculated with less than 10
4
cells per ml, whereas a 7- to 12-hr growth period was required for the detection of products formed in cultures of
Serratia marcescens, Aerobacter aerogenes, E. coli
K-12,
Staphylococcus aureus
, and
Salmonella typhimurium
. Metabolites elaborated by the equivalent of less than a single cell of
B. cereus, S. faecalis, P. vulgaris
, or
E. coli
B were sensed by the electron capture detector. The flame ionization detector was generally not as sensitive. Volatile metabolites were identified, and their concentrations were determined.
Gas Exchange of Algae
Authors: Ammann Elizabeth C. B. , Fraser-Smith Antony
Published: December 2020

A single culture of
Chlorella pyrenoidosa
(700 ml) was grown continuously under uniform environmental conditions for a period of 11 months. During this time, the culture remained uncontaminated and its oxygen production, carbon dioxide consumption, and photosynthetic quotient (PQ = CO
2
/O
2
) were monitored on a 24-hr basis. The gas exchange characteristics of the alga were found to be extremely reliable; the average oxygen production was 1.21 ± 0.03 ml per min, the carbon dioxide consumption was 1.09 ± 0.03 ml per min, and the PQ was 0.90 ± 0.01 when changes in both lamp intensity and instrument accuracy were taken into consideration. Such long-term dependability in the production of oxygen, consumption of carbon dioxide, and maintenance of a uniform PQ warrants the use of
C. pyrenoidosa
in a regenerative life support system for space travel.
Bacteriology of Manganese Nodules
Authors: Trimble R. B. , Ehrlich H. L.
Published: December 2020

MnO
2
reduction by aerobic growing cultures of
Bacillus
29 and coccus 32, isolated from ferromanganese nodules, was assessed for 7 days. A 1-day lag was observed before the onset of MnO
2
reduction by either culture. Addition of HgCl
2
to a final concentration of about 10
-3
M caused a rapid cessation of MnO
2
reduction by the growing cultures. Neither culture reduced MnO
2
when grown under continued anaerobiosis from the start of an experiment. However, if conditions were made anaerobic after MnO
2
reduction was initiated, reduction continued at a rate only slightly lower than that under aerobic conditions. Resting-cell cultures reduced MnO
2
equally well aerobically and anaerobically, provided that ferricyanide was present to serve as electron carrier. These findings showed that oxygen is needed for culture adaptation to MnO
2
reduction, and that oxygen does not interfere with microbial MnO
2
reduction itself. Both cultures caused sharp drops in the
p
H of the medium during MnO
2
reduction: with coccus 32, during the entire incubation time; with
Bacillus
29, for the first 3 days. The
E
h
of the medium fluctuated with either culture and never fell below 469 mv with
Bacillus
29 and below 394 mv with coccus 32. The rates of glucose consumption and Mn
2+
release by
Bacillus
29 and coccus 32 were fairly constant, but the rates of lactate and pyruvate production were not. Although acid production undoubtedly helped in the reduction of pyrolusite (MnO
2
) by the bacteria, it did not appear to be important in the reduction of manganese oxide in ferromanganese nodules, as shown by the results with a nodule enrichment.
Influence of Spore Moisture Content on the Dry-Heat Resistance of
Bacillus subtilis
var.
niger
Authors: Angelotti Robert , Maryanski James H. , Butler Thomas F. , Peeler James T. , Campbell Jeptha E.
Published: December 2020

The dry-heat resistance of
Bacillus subtilis
var.
niger
spores located in or on various materials was determined as
D
and
z
values in the range of 105 through 160 C. The systems tested included spores located on steel and paper strips, spores located between stainless-steel washers mated together under 150 inch-lb and 12 inch-lb of torque, and spores encapsulated in methylmethacrylate and epoxy plastics.
D
values for a given temperature varied with the test system. High
D
values were observed for the systems in which spores were encapsulated or under heavy torque, whereas lower
D
values were observed for the steel and paper strip systems and the lightly torqued system. Similar
z
values were obtained for the plastic and steel strip systems (
z
D
= 21 C), but an unusually low
z
for spores on paper (
z
D
= 12.9 C) and an unusually high
z
for spores on steel washers mated at 150 inch-lb of torque (
z
D
= 32 C) were observed. The effect of spore moisture content on the
D
value of spores encapsulated in water-impermeable plastic was determined, and maximal resistance was observed for spores with a water activity (
a
w
) of 0.2 to 0.4. Significantly decreased
D
values were observed for spores with moisture contents below
a
w
0.2 or above
a
w
0.4. The data indicate that the important factors to be considered when measuring the dry heat resistance of spores are (i) the initial moisture content of the spore, (ii) the rate of spore desiccation during heating, (iii) the water retention capacity of the material in or on which spores are located, and (iv) the relative humidity of the system at the test temperature.
Metabolism of Tryptophans by
Pseudomonas aureofaciens
Authors: Elander Richard P. , Mabe James A. , Hamill Robert H. , Gorman Marvin
Published: December 2020

Twenty-nine strains of
Pseudomonas
, classified as
P. fluorescens
biotype D or E or as
P. multivorans
, were examined for the production of pyrrolnitrin, an antifungal agent synthesized in
P. aureofaciens
. Eight strains were shown to produce pyrrolnitrin in shake-flask fermentation. Four cultures were from the multivorans taxon, and the remaining four were members of the fluorescens group. The antifungal agent produced in these strains was isolated and shown to be pyrrolnitrin by comparison with an authentic sample. The strains differed markedly with respect to the amount of pyrrolnitrin produced and in their utilization of exogenous tryptophan. Secondary metabolites, not related to pyrrolnitrin, were also examined and compared with those synthesized in
P. aureofaciens
. Marked differences were noted in both phenazine pigments and phenolic metabolites. The results of the study suggest that the production of pyrrolnitrin may be widespread in selected taxonomic groups of
Pseudomonas
.
Effect of Salt Concentration in the Recovery Medium on Heat-injured
Streptococcus faecalis
Authors: Beuchat L. R. , Lechowich R. V.
Published: December 2020

Properties relating to the recovery of three heat-injured strains of
Streptococcus faecalis
were studied. All strains were cultured in all purpose plus Tween broth (APT) at 30 C for 24 hr before being subjected to heat in fresh APT broth. APT recovery medium containing various added amounts of NaCl, KCl, MgCl
2
, or KCl and MgCl
2
was used to assess the effect of salts on the recovery of thermally injured
S. faecalis
. It was evident that, upon exposure to heat,
S. faecalis
cells became sensitive to increased salt concentrations. Analyses to determine the ribonucleic acid (RNA) content of heated cells showed a reduction of cellular RNA, but the per cent reduction was not directly proportional to the per cent reduction of the viable cells.
Investigation of Reported Aflatoxin Production by Fungi Outside the
Aspergillus flavus
Group
Authors: Wilson Benjamin J. , Campbell T. Colin , Hayes A. Wallace , Hanlin Richard T.
Published: December 2020

A screening study of 121 fungus isolates, representing 29 species, for aflatoxin synthesis demonstrated this property only in
Aspergillus flavus
and
A. parasiticus
. Eight of the organisms found negative were isolates reported by other investigators to produce aflatoxin. Since similar negative reports have come from several other workers, it is concluded that only the
A. flavus
group of
Aspergillus
can presently be certified as sources of these toxins. Reasons for possible false-positive findings are discussed along with precautionary measures and differential analytical procedures useful in aflatoxin screening studies.
Antiviral Agent from λ-infected
Escherichia coli
K-12
Authors: Centifanto Ysolina M.
Published: December 2020

Phagicin, which is an antiviral agent active against deoxyribonucleic acid (DNA) viruses such as vaccinia and herpes simplex, has been identified as a phage internal protein. It was found in infected
Escherichia coli
lysates, but could also be obtained by disruption of the purified infective particles after incubation with LiCl at 46 C for 15 min or by sonic treatment. After centrifugation at high speed, the antiviral activity was found in the DNA phase and could be separated by chromatography on Sephadex gels with 0.2 M phosphate buffer (
p
H 7.5) as the eluent. Phagicin present in lysates after removal of infective particles was nondialyzable and was bound to nucleic acids. It could be released during precipitation of nucleic acids by streptomycin sulfate, and in this form it could be easily dialyzed. The antiviral activity of phagicin was specific for herpes simplex and vaccinia viruses.
Stability of Suspensions of Influenza Virus Dried to Different Contents of Residual Moisture by Sublimation In Vacuo
Authors: Greiff Donald , Rightsel Wilton A.
Published: December 2020

After freezing, suspensions of influenza virus were dried by sublimation of water in vacuo to contents of residual moisture of 3.2, 2.1, 1.7, 1, or 0.4%. The stability of the several suspensions was determined by an accelerated storage test. Based on the times predicted for the dried preparations stored at different temperatures to lose 1 log of infectivity titer, the order of stability in relation to residual moistures was as follows: 1.7% > 2.1% > 1% > 3.2% > 0.4%.
A Disposable Anaerobic System Designed for Field and Laboratory Use
Authors: Brewer John H. , Allgeier Daniel L.
Published: December 2020

A disposable anaerobic system which is characterized by its light weight and its compactness is described. The system consists of a multilayer plastic bag with a unique sealing device. A collapsible impregnated cardboard container is fitted with a catalyst and holders for a disposable hydrogen generator and an anaerobic indicator. The catalyst is active at room temperature and requires no heat activation. This system, which lends itself readily to compact storage, quick assembly, and ease of operation, is disposable after use.
Growth and Metabolism of Live Vaccine Strain of
Pasteurella tularensis
Authors: Scharer Jeno M. , Klein Frederick , Lincoln Ralph E.
Published: December 2020

The growth and metabolism of the live vaccine strain of
Pasteurella tularensis
in different media were investigated. Maximal growth was observed in a medium containing a sulfuric acid digest of casein as amino acid source. Amino acid metabolism produced considerable ammonia, and the rate of ammonia evolution was directly proportional to the growth rate. The most likely route for amino acid breakdown is nonspecific oxidative deamination.
Taxonomy by Carbon Replication
Authors: Dietz Alma , Mathews John
Published: December 2020

Carbon repligraphic comparison of eight cultures described as
Streptomyces hygroscopicus
showed four distinct types. Five of the cultures could be considered
S. hygroscopicus
by spore type (a relatively nonsegmented spore structure with an extremely wrinkled surface); three of the cultures had spore types that differed from one another and from the
hygroscopicus
holotype. Differentiation was confirmed by Ektacolor pattern.
Microbiological Quality of Protein Feed Supplements Produced by Rendering Plants
Authors: Loken K. I. , Culbert Kathleen H. , Solee R. E. , Pomeroy B. S.
Published: December 2020

Samples of protein feed supplements produced by rendering plants were examined for salmonellae, total aerobic bacterial counts, coliform counts, and enterococci. Isolations of salmonellae were more frequent from products with high counts; however, 6% of the samples with total counts of less than 1,000 per gram and 14% of the samples with coliform counts of less than 1 per gram contained salmonellae. Serotypes of
Escherichia coli
which have been associated with disease in domestic animals and poultry were also isolated from products. Although the distribution of serotypes of salmonellae isolated from environmental swabs and flies was similar to that isolated from products, the isolation of several serotypes from flies which had not been isolated in plants suggested that flies may be a potential source of contamination.
Radiation Treatment of Foods
Authors: Idziak Edmund S. , Incze Kalman
Published: December 2020

Radurization processing of fresh eviscerated poultry has been microbiologically studied. The recommended dose of 0.5 Mrads extended the shelf life at 5 C by approximately 14 days. This treatment also effected a 10 and 11 log reduction in the number of viable
Salmonella
species and
Staphylococcus aureus
strains, respectively. Recycling these organisms at sublethal doses of irradiation resulted in strains possessing increased irradiation resistance. Shifts in the microbial ecology after irradiation and storage resulted, in some instances, in the isolation of organisms tentatively identified as
Moraxella
sp. and
Herellea vaginicola
.
Production of Mevalonic Acid by Fermentation
Authors: Tamura Gakuzo , Ando Kunio , Kodama Kenjiro , Arima Kei
Published: December 2020

The purpose of this investigation was to select microorganisms that produce substantial quantities of mevalonic acid and to develop an economic fermentation process. To screen for mevalonic acid-producing microorganisms, it was necessary to improve the method for the quantitative determination of this acid. The biological assay was modified by shortening the incubation time and simplifying the procedure. The principle of the assay is based on the essential mevalonic acid requirement of the organism
Lactobacillus heterohiochii
for growth. Screening was carried out by selecting high mevalonic acid-producing organisms from various type cultures.
Endomycopsis fibuliger
was chosen for medium development studies, and 939 μg of mevalonic acid per ml was produced in the culture filtrate after modifications of medium and fermentation conditions.
Production of Nucleic Acid-related Substances by Fermentative Processes
Authors: Furuya Akira , Abe Shigeo , Kinoshita Shukuo
Published: December 2020

The accumulation of 5′-inosinic acid (IMP) by a mutant, KY 13102, induced from
Brevibacterium ammoniagenes
ATCC 6872 by ultraviolet light irradiation, was examined. Although growth was stimulated by adenine or adenosine, the microorganism showed fair growth in the medium containing amino acids but no adenine. Among six kinds of natural nutrients tested, meat extract and Casamino Acids were suitable for the accumulation of IMP. Manganese ion strongly affected growth, the accumulation of IMP and hypoxanthine, and cell morphology. Among amino acids tested, L-methionine, L-proline, and L-valine stimulated IMP accumulation. In the medium containing 1.0 g of L-proline per liter, 12.8 mg of IMP per ml was accumulated. The mechanism of IMP accumulation by the mutant is discussed.
Effect of Diurnal Temperature Cycles on the Production of Aflatoxin
Authors: Schroeder Harry W. , Hein Hugo
Published: December 2020

Exposures to short periods of high temperature (40 to 50 C) in each 24-hr diurnal temperature cycle (average temperature ca. 25 C) reduced growth of
Aspergillus parasiticus
and production and accumulation of the aflatoxins when compared with cultures held continuously at 25 C. In contrast, diurnal cycles with an average temperature of ca. 25 C but with minima as low as 10 C did not appreciably affect either growth or toxin production. The ratio of production of aflatoxin B to aflatoxin G increased as the maximal temperature was raised but remained essentially unchanged with decreasing minimal temperatures.
Thermal Resistance of Salmonellae Isolated from Dry Milk
Authors: Read R. B. , Bradshaw J. G. , Dickerson R. W. , Peeler J. T.
Published: December 2020

Salmonella anatum, S. binza, S. cubana, S. meleagridis, S. newbrunswick
, and
S. tennessee
isolated from dry milk, and
S. senftenberg
775W were studied for heat resistance to determine whether these organisms would survive pasteurization as recommended by the 1965 Pasteurized Milk Ordinance of the U.S. Public Health Service. Thermal inactivation determinations were made on washed cells of the test microorganisms suspended in sterile whole milk. Excluding
S. senftenberg, D
values ranged from 3.6 to 5.7 sec at 62.8 C, from 1.1 to 1.8 sec at 65.6 C, and from 0.28 to 0.52 sec at 68.3 C. Corresponding values for
S. senftenberg
were 34.0, 10.0, 1.2, and 0.55 sec for respective exposure temperatures of 65.5, 68.3, 71.7, and 73.9 C. The present milk pasteurization processes as recommended by the Public Health Service will inactivate all seven strains of salmonellae studied, provided that the initial concentration does not exceed a calculated 3 × 10
12
salmonellae per ml of milk.
Dry Heat or Gaseous Chemical Resistance of
Bacillus subtilis
var.
niger
Spores Included Within Water-soluble Crystals
Authors: Mullican Charles L. , Hoffman Robert K.
Published: December 2020

Inclusion of spores of
Bacillus subtilis
var.
niger
in water-soluble crystals increased the resistance of the spores to dry heat and to a gaseous mixture of methyl bromide and ethylene oxide. Resistance of spores in glycine crystals to dry heat at 125 C was increased 5 to 24 times compared to unprotected spores. There appeared to be a positive correlation between the size of the crystal and the degree of resistance. The resistance to dry heat of spores included in sodium chloride crystals was about six times greater than unprotected spores. A gaseous mixture of methyl bromide (964 mg/liter) and ethylene oxide (642 mg/liter) at 37% relative humidity was ineffective in sterilizing spores enclosed within these water-soluble crystals, as was ethylene oxide alone. However, if the relative humidity was sufficiently high to dissolve the crystals during exposure to the vapor, viable-spore counts were drastically reduced or were negative. The surfaces of crystals grossly contaminated with dry spores were sterilized by exposure to gaseous ethylene oxide. Sterilization of heat-labile or moisture-labile materials with a critical requirement for sterility, as in planetary probes or drugs, may be complicated by the presence of spores in naturally occurring water-soluble crystals. This phenomenon is similar to the protection afforded spores entrapped in solid plastics.
Novel Multi-Slit Large-Volume Air Sampler
Authors: Buchanan L. M. , Decker H. M. , Frisque D. E. , Phillips C. R. , Dahlgren C. M.
Published: December 2020

Scientific investigators who are interested in the various facets of airborne transmission of disease in research laboratories and hospitals need a simple, continuous, high-volume sampling device that will recover a high percentage of viable microorganisms from the atmosphere. Such a device must sample a large quantity of air. It should effect direct transfer of the air into an all-purpose liquid medium in order to collect bacteria, viruses, rickettsia, and fungi, and it should be easy to use. A simple multi-slit impinger sampler that fulfills these requirements has been developed. It operates at an air-sampling rate of 500 liters/min, has a high collection efficiency, functions at a low pressure drop, and, in contrast to some earlier instruments, does not depend upon electrostatic precipitation at high voltages. When compared to the all-glass impinger, the multi-slit impinger sampler collected microbial aerosols of
Serratia marcescens
at 82% efficiency, and aerosols of
Bacillus subtilis
var.
niger
at 78% efficiency.
Hemagglutination and Hemolysis by
Authors: Barrett James T. , Howe Michael L.
Published: December 2020

Twenty-two species of lichens from 10 different genera possessed a hemagglutinin for one or more of human, sheep, horse, cow, rabbit, guinea pig, and chicken erythrocytes. Hemolysins were also detected occasionally, but these were only active at low dilutions. In those species tested, the hemolytic principle was dialyzable; the hemagglutinating agent was not. Preliminary studies have indicated that the lichen hemagglutinins are nonspecific.
Sensitivity of Herpes Simplex Virus, Vaccinia Virus, and Adenoviruses to Deoxyribonucleic Acid Inhibitors and Thiosemicarbazones in a Plaque Suppression Test
Authors: Herrmann Ernest C.
Published: December 2020

Herpes simplex and vaccinia viruses and adenovirus types 1, 2, 5, and 7 were tested by plaque suppression methods for sensitivity to halogenated deoxyuridines (5-iodo-, 5-bromo-, 5-chloro-, and 5-fluoro-), cytosine arabinoside, isatin-β-thiosemicarbazone, and
N
-methylisatin-β-thiosemicarbazone. After incubation for 12 days in HeLa cell cultures, vaccinia virus plaques were still readily suppressed by deoxyribonucleic acid (DNA) inhibitors and thiosemicarbazones. Herpes simplex virus plaques were likewise suppressed by at least three DNA inhibitors. Adenovirus plaques were not suppressed by DNA inhibitors or thiosemicarbazones. 5-Fluoro-2′-deoxyuridine could not be shown to have any antiviral activity, but it did produce a substantial lethal action on the cells.
Microbial Contamination on Disposable Hypodermic Syringes Prior to Sterilization by Ionizing Radiation
Authors: Cook A. M. , Berry R. J.
Published: December 2020

A large number of syringes were taken from the production lines of three independent manufacturers; the numbers and types of microorganisms contaminating these randomly sampled syringes were assessed in the laboratories maintained by each of these manufacturers for routine sterility testing, according to a standard protocol devised by the Research Committee of the UK Panel on Gamma and Electron Irradiation, which coordinated the investigation and analyzed the results. Items produced by a manufacturer were assessed for microbiological contamination both in their own laboratories and in the laboratories of the other manufacturers. The level of “false-positive” results was determined independently for each laboratory by the testing of “known sterile” items which had been subjected to the radiation-sterilization process. Both the percentage of syringes initially sterile and the average number of organisms per contaminated syringe differed among the three manufacturers. When corrected for interlaboratory differences, the number of syringes initially sterile ranged from 16 to 48%, and the mean number of organisms per contaminated syringe was 20 to 70. Of 964 syringes tested by all three laboratories, only one contained over 1,000 aerobic organisms (1,133). The most common organisms found were coagulase-negative, gram-positive cocci. Two manufacturers assessed contamination by anaerobic organisms; of 610 syringes, 1 contained 4,275 organisms and 3 more had 100 to 1,000 organisms, but 488 (80%) were uncontaminated by anaerobes. The results are discussed in the context of the choice of radiation dose necessary for the sterilization of medical products manufactured under controlled hygienic conditions.
Bioproduction and Purification of Rubratoxin
Authors: Hayes A. Wallace , Wilson Benjamin J.
Published: December 2020

Methods were developed for bioproduction and extraction of rubratoxin B from liquid cultures of
Penicillium rubrum
P-13 (NRRL A-11785). A maximum of 874.7 mg of toxin per liter of medium was attained in 21 days using stationary cultures of Mosseray's simplified Raulin solution enriched with 2.5% malt extract. Malt extract was required for rubratoxin production. Rubratoxin was not produced in either shake flasks or in fermentors with restricted aeration. Crystalline toxin was obtained by liquid-liquid extraction of concentrated culture medium with ethyl ether. Adhering colored impurities were removed by column chromatography and by recrystallization from acetone.
Susceptibility of Coagulase-negative Staphylococci to Lysostaphin and Other Antibiotics
Authors: Zygmunt Walter A. , Browder Henry P. , Tavormina Peter A.
Published: December 2020

In general, coagulase-negative staphylococci were found to be relatively less susceptible to the lytic action of lysostaphin than coagulase-positive staphylococci. To achieve, arbitrarily, a lysis greater than 75%, it was necessary to use an increased concentration of enzyme or a longer incubation period than that usually required with coagulase-positive strains. For the most part, the cultures studied were sensitive to oxacillin, cloxacillin, dicloxacillin, nafcillin, ancillin, cephalothin, cephaloridine, fusidic acid, lincomycin, novobiocin, and neomycin [median minimal inhibitory concentrations (MIC) of 1.56 μg/ml or less]. Some degree of resistance (median MIC values of 12.5 μg/ml or greater) to benzylpenicillin, ampicillin, methicillin, tetracycline, chloretetracycline, erythromycin, ristocetin, and lysostaphin was found. Ten methicillin-resistant, coagulase-negative staphylococal strains were found to be cross-resistant to all nine of the penicillins tested, but much less resistant to the two cephalosporin analogues. In several instances, some of these strains seemed to be more sensitive to benzylpenicillin and to certain of the semisynthetic penicillins than to methicillin. Of the 18 antibiotics tested with the viable plate count method, the methicillin-resistant strains were found to be the most sensitive to lincomycin and novobiocin.
Identification of Stimulants for
Lactobacillus bulgaricus
in Tomato Juice
Authors: Cogan T. M. , Gilliland S. E. , Speck M. L.
Published: December 2020

Acid production in milk by
Lactobacillus bulgaricus
was stimulated by tomato juice or its serum. Preliminary purification of the stimulants involved adsorption and elution on a cation-exchange resin. Unidimensional paper chromatography in two solvent systems was employed in further isolation and purification. Identification of the stimulatory components was based on ultraviolet spectral analysis and thin-layer chromatography. The stimulants were identified as adenine and adenosine.
Characterization of an Inhibitor for
Lactobacillus bulgaricus
in Tomato Juice
Authors: Cogan T. M. , Gilliland S. E. , Speck M. L.
Published: December 2020

Tomato juice (serum) added to milk in high concentration caused inhibition of acid production by
Lactobacillus bulgaricus
. The inhibitor was partially purified by adsorption on charcoal. Further isolation and purification involved paper chromatography in two different solvent systems. Ultraviolet-absorption spectra and thin-layer chromatography were used in characterization studies. The inhibitor was found to be a xylose- and adenine-containing nucleotide.
Fungi Isolated from Tobacco Leaves and Brown-Spot Lesions Before and After Flue-Curing
Authors: Welty R. E. , Lucas G. B. , Fletcher J. T. , Yang H.
Published: December 2020

Discs of tissue excised from ripe nonflue-cured and flue-cured tobacco leaves, harvested on six dates and cultured on three selective media, yielded 21 and 24 genera of fungi, respectively. Of 5,094 fungi isolated from 3,240 pieces of nonfluecured leaf tissue, 89.5% comprised five genera,
Alternaria, Cladosporium, Epicoccum, Trichoderma
, and
Nigrospora
. Of 2,494 fungi isolated from 3,240 pieces of flue-cured leaf tissue, 70.9% were
Alternaria, Cladosporium Epicoccum, Aspergillus
, and
Nigrospora
. Flue-cured and nonflue-cured brown-spot lesions harvested at two locations yielded 12 and 14 genera of fungi, respectively.
Alternaria, Penicillium, Phoma
, and
Stemphyllium
comprised 91.5% of the 2,245 fungi isolated from noncured and 87.1% of the 1,118 fungi isolated from the cured lesions. The number and kinds of fungi obtained from diseased and healthy tissue were reduced but not eliminated by flue-curing.
Continuous Oxidative Assimilation of Acetic Acid and Endogenous Protein Synthesis Applicable to Treatment of Nitrogen-Deficient Waste Waters
Authors: Gaudy A. F. , Goel K. C. , Gaudy Elizabeth T.
Published: December 2020

A previous study indicated that the oxidative assimilation capacity of a heterogeneous microbial population for acetic acid did not return to the initial value after a period of endogenous respiration in the presence of ammonium sulfate. In view of this finding it was not possible to recommend fully the use of a continuous oxidative assimilation process for the treatment of nitrogen-deficient waste waters of noncarbohydrate nature. To put the process to a severe test, a laboratory-scale pilot plant study was done. Acetate (1,000 mg/liter) was fed continuously to a completely mixed, aerated reactor vessel, from which the mixed liquor was channeled to a settling basin. The settling basin supernatant fluid was continuously discharged, and a portion of the settled biological sludge was subjected to endogenous respiration in the presence of ammonium sulfate and was recycled to the aeration vessel. Experiments were conducted at three levels of ammonia nitrogen in the endogenous phase. Approximately 90% removal of the carbon source (expressed as chemical oxygen demand, COD) was attained with a low level of supplemental nitrogen (COD/N = 70:1) and a fairly low reactor detention time (4 hr). Based upon these and previous results, it has been concluded that the process shows promise for application to the treatment of a wide variety of nitrogen-deficient industrial wastes.
Isolation of Shigellae
Authors: Taylor Welton I. , Schelhart Dorothy
Published: December 2020

The efficiencies of three enrichment broths and four plating media for isolation of enteric pathogens were compared from 1,117 stool specimens. Direct streaking proved to be inferior to enrichment, detecting only 50% of the salmonellae and 61% of the shigellae. By contrast, Selenite Broth (SF) found 90% of the total salmonellae isolates and 82% of the shigellae isolates. Gram-Negative Broth (GN) found 82% and 85%, respectively, but Tetrathionate found only 60% and 39%. Thus, SF and GN were comparable for both salmonellae and shigellae and significantly better than Tetrathionate Broth for both. The plating media compared were MacConkey (MAC), deoxycholate citrate (DC), xylose lysine deoxycholate (XLD), and xylose lysine Brilliant Green (XLBG) Agars. Of the total salmonellae isolated, XLD produced 94%; XLBG, 71%; MAC, 55%; and DC, only 35%. Of shigellae, XLD found 89%; MAC, 75%; XLBG, 63%; and DC, but 27%. The efficacy of XLD is observed to be almost threefold that of DC. The most successful combination of media for the detection of fecal pathogens was GN or SF enrichment broths streaked to XLD plates. These analyses resulted in the isolation of 118 strains of salmonellae and 33 of shigellae.
Cellular Fatty Acid Composition and Identification of Rumen Bacteria
Authors: Ifkovits R. W. , Ragheb H. S.
Published: December 2020

The fatty acid compositions of 21 pure cultures of rumen bacteria, representing 12 genera and 14 species, were compared as methyl esters. Each organism possessed a consistent and reproducible fatty acid profile. Overlapping similarities and differences in composition did not allow differentiation between families or genera. Although species differentiation was possible, fatty acid composition appeared to be only an aid in the identification of bacteria.
Fermentation of Philippine Vegetable Blends
Authors: Orillo C. A. , Sison E. C. , Luis M. , Pederson C. S.
Published: December 2020

Seven blends of Philipphine vegetables, two of which contained soybeans and one mongo bean sprouts, were prepared for fermentation and study of microbiological and chemical changes. The fermentations were typical lactic acid bacterial fermentations, initiated by
Leuconostoc mesenteroides
and continued by
Lactobacillus brevis, Pediococcus cerevisiae
, and
L. plantarum
. The combination of high acidity and low
p
H resembled other vegetable fermentations, such as sauerkraut. The procedure offers a method of preserving surplus vegetables, and, in addition, a method for incorporating and preserving the high-protein-containing soybeans.
Procedure for Evaluating the Effects of 2,450- Megahertz Microwaves upon
Streptococcus faecalis
and
Saccharomyces cerevisiae
Authors: Lechowich R. V. , Beuchat L. R. , Fox K. I. , Webster F. H.
Published: December 2020

Modifications of a commercial 2,450-megahertz microwave oven were made so that 6 ml of microbial suspension could be exposed to the microwave field for various periods of time. The microorganisms were contained in the central tube of a modified Liebig condenser positioned in the approximate geometric center of the oven cavity. Kerosene at -25 C was circulated through the jacket of the condenser during microwave exposure permitting microwaves to reach the microbial suspension. Flow rates of the kerosene were varied to permit the temperature of the suspension to range from 25 to 55 C during microwave exposure. Conductive heating experiments using similar temperatures were also conducted. A thermocouple-relay system was employed to measure the suspension temperature immediately after the magnetron shutoff. Continuous application of microwaves to suspensions of 10
8
to 10
9
Streptococcus faecalis or Saccharomyces cerevisiae
per ml appeared to produce no lethal effects other than those produced by heat. Respiration rates of microwave-exposed
Scerevisiae
were directly related to decreases in viable count produced by increased microwave exposure times.
Mode of Action of the Antibacterial Compound Dequalinium Acetate
Authors: Hugo W. B. , Frier M.
Published: December 2020

Dequalinium acetate is taken up rapidly by bacterial cells. Unlike the membrane-active drugs exemplified by cetrimide or chlorhexidine, its capacity for damaging the plasma membrane is low. The drug appears to penetrate quite rapidly into the cytoplasm where its effect seems to be exerted. A review of the evidence obtained in this study suggests that nucleic acid-containing components of the cell may be the prime target of this compound.