bluuebunny/crossref_metadata_2025 huggingface dataset:
Pectolytic enzymes in Rhizobium
Authors: Hubbell D H , Morales V M , Umali-Garcia M
Published: January 2020

A sensitive pectin agar plate assay was used to demonstrate low levels of pectolytic enzymes in infective and noninfective strains of Rhizobium. The possible relation of this characteristic to legume infection is discussed.
Structural factors influencing the biodegradation of imides
Authors: Ennis D M , Kramer A , Jameson C W , Mazzocchi P H , Bailey W J
Published: January 2020

Comparative studies on the biodegradability of amides and imides are presented. Low-molecular-weight imides of varying chain lengths (4, 6, 7, 8, 18, and 20 carbons) were biodegrable. N-alkyl substitution of amides and imides resulted in non-biodegrable derivatives when the amide portion was greater than two carbons in length. N-alkyl-substituted derivatives of acetamide or diacetamide, however, were biodegrable. Several soil isolates, including Aspergillus niger and species of Flavobacterium and Alcaligenes, were capable of growth with imides as sole N or C sources.
Isolation of Yersinia enterocolitica from raw milk
Authors: Schiemann D A , Toma S
Published: January 2020

Four enrichment procedures were used for examining 131 raw milk samples for the presence of Yersinia enterocolitica. Forty-two isolations were obtained from 19 pooled- (31.1 percent positive) and 10 individual-producer samples (14.3 percent positive). Enrichment by Butterfields phosphate buffer incubated at 4 degrees C for 14 days and then inoculation of modified Rappaport broth incubated at 23 degrees C for 5 days produced the greatest number of isolations. The majority of isolates were biotype 1, and many were atypical from clinical isolates in being rhamnose positive (47.6 percent), citrate positive (16.7 percent), and lactose positive (26.2 percent). Thirteen isolates were serotypable, belonging to seven different O serotypes, with O:5 occurring most frequently.
Distribution of autotrophic nitrifying bacteria in a polluted river (the Passaic)
Authors: Matulewich V A , Finstein M S
Published: January 2020

The abundance of nitrifying bacteria, determined by most-probable-number procedures, within habitats of the Passaic River was as follows: rooted aquatic plants greater than algae approximately equal to rocks greater than sediments greater than greater than water. On the average, NH4+ oxidizers were 540-fold more abundant in the topmost 1 cm of sediment than in the water, and NO2- oxidizers were 250-fold more abundant. The population densities in this surface sediment at two nearby stations, one with a predominantly mineral stream bed and the other an organic ooze, did not differ significantly. Large numbers of nitrifiers were present to a depth of about 5 cm in a mineral sediment core.
Physiological Response of
Neurospora
Conidia to Freezing in the Dehydrated, Hydrated, or Germinated State
Authors: Leef James L. , Mazur Peter
Published: January 2020

This study concerned the response to freezing of
Neurospora crassa
conidia in four different states: air-dry, hydrated in water, hydrated in Vogel medium lacking only sucrose, or hydrated in complete Vogel medium. All hydrated conidia were incubated in one of the above media for various times before freezing and were then washed and frozen in distilled water. Viability was estimated by three techniques, and the agreement among them was good. Hydration of air-dry conidia was found to be very rapid and, once hydrated, the conidia were much more sensitive to rapid freezing than they were before hydration. Rapidly cooled conidia survived freezing to a much higher extent when the warming rate was rapid than when it was slow; slowly cooled conidia showed little or no dependence on the warming rate. This sensitivity to rapid cooling and slow warming was attributed to the effects of intracellular ice. The sensitivity to freezing could be reversed by dehydrating the conidia in vacuo before freezing; thus, it was concluded that the presence or absence of water is the determining factor in the initial sensitivity due to freezing. In water, the sensitivity remained constant from 2 min to 15 days after hydration. Although conidia hydrated in growth medium lacking sucrose remained metabolically inactive, their sensitivity to rapid freezing decreased as a function of time in the medium before freezing. The reason for this decreased sensitivity is not understood. Conidia hydrated in complete growth medium (i.e., containing sucrose) became metabolically active and, after the initial sensitivity associated with hydration, became increasingly more sensitive to freezing as a function of their time in the medium. Drying itself was deleterious to metabolically active conidia, and those that survived dehydration did not exhibit a large absolute increase in resistance to subsequent freezing. The increase in sensitivity to freezing and to drying seems associated with the presence of metabolic activity; however, the precise cause of the sensitization remains obscure.
Identification of enterotoxigenic staphylococci from sheep and sheep cheese
Authors: H�jek V
Published: January 2020

The total of 127 Staphylococcus aureus strains obtained from sheep and sheep cheese were examined for their biochemical activities, biotypes, phage patterns, and ability to produce enterotoxins. Of the 83 staphylococcal strains isolated from animals 77 (93%) were classified as the C biotype. Of this group of sheep-adapted strains, 61 (79%) were sensitive to phage 78, and 46 (60%) produced enterotoxin C exclusively. The three isolated belonging to the A biotype produced enterotoxin D, and two of the three unclassifiable strains produced enterotoxin A. Of the 44 staphylococcal strains isolated from sheep cheese, there were 37 (84%) identified as the C biotype. From this series, 31 (84%) strains were lysed with phage 78, 6 (16%) strains produced enterotoxin C, and 1 strain produced enterotoxin A. One of the six strains determined as the A biotype produced enterotoxin D. C biotype strains, especially of ovine origin, are an exception among animal staphylococci, because a large number of them are enterotoixgenic. The C antigenic type is the most usual of the known enterotoxins in staphylococci of animal provenance.
Formation of glycosidases in batch and continuous culture of Bacteroides fragilis
Authors: Berg J O , Nord C E , Wadstr�m T
Published: January 2020

Nine strains of bacteroides fragilis were cultivated in stirred fermentors and tested for their ability to produce glycosidases. B. fragilis subsp. vulgatus B70 was used for optimizing the production of glycosidases. The highest bacterial yield was obtained in proteose peptone-yeast extract medium. The optimum pH for maximal bacterial yield was 7.0, and the optimum temperature for growth was 37 degrees C. The formation of glycosidases was optimal between pH 6.5 and 7.5, and the optimum temperature for synthesis of glycosidases was between 33 and 37 degrees C. Culture under controlled conditions in fermentors gave more reproducible production of glycosidases than static cultures in bottles. The strain was also grown in continuous culture at a dilution rate of 0.1 liter/h at pH 7.0 and 37 degrees C with a yield of 2.0 mg of dry weight per ml in the complex medium. The formation of glycosidases remained constant during the entire continuous process.
Denitrification and Ammonia Formation in Anaerobic Coastal Sediments
Authors: Koike Isao , Hattori Akihiko
Published: January 2020

Simultaneous determinations of nitrogen gas production, ammonia, and particulate organic nitrogen formation in the coastal sediments of Mangoku-Ura, Simoda Bay, and Tokyo Bay were made by using the
15
N-label tracer method. The rate of nitrogen gas production in the sediment surface layer was about 10
−2
μg atom of N per g per h, irrespective of the location of the sediments examined. [
15
N]ammonia and -particulate organic nitrogen accounted for 20 to 70% of the three products, and after several hours of incubation, the major fraction of nondenitrified
15
N in Mangoku-Ura and Simoda Bay sediments was recovered as ammonia. In Tokyo Bay sediments, particulate organic nitrogen was produced at a greater rate than was ammonia. The reduction rate data suggest that the pathway of nitrate reduction to ammonia is important in coastal sediments.
Effects of Polychlorinated Biphenyls on Growth and Respiration of Heterotrophic Marine Bacteria
Authors: Blakemore Richard P. , Carey Anne E.
Published: January 2020

A number of marine bacterial isolates from both near-shore and open-ocean environments were tested for growth inhibition with exposure to low concentrations (1 to 100 μg/liter) of Aroclor 1254, a commercial mixture of polychlorinated biphenyls (PCBs). Of over 17 bacterial cultures tested, growth of only two open-ocean isolates, one a pseudomonad and the other a tetrad-forming coccus, was consistently inhibited by Aroclor at concentrations as low as 10 μg/liter (10 ppb). Growth inhibition was dose dependent over a concentration range of 10 to 100 μg/liter. The effects upon division rates and final cell yields of each bacterial isolate were greatest when PCBs were added to cultures with low cell densities or with lower specific growth rates. The pseudomonad also had reduced carotenoid levels and an altered filamentous morphology with Aroclor present at a concentration of 10 μg/liter, or more. The effects noted were reversible for at least 18 h after initial exposure. Concentrations of Aroclor in excess of those needed to stop growth had no detectable effect upon the respiration rate of cells of either culture. This suggests that the reduced division rates observed were not due to inability of PCB-treated cells to transport or catabolize the carbohydrate or amino acid substrates tested.
Hydrocarbon Biodegradation in Hypersaline Environments
Authors: Ward David M. , Brock T. D.
Published: January 2020

When mineral oil, hexadecane, and glutamate were added to natural samples of varying salinity (3.3 to 28.4%) from salt evaporation ponds and Great Salt Lake, Utah, rates of metabolism of these compounds decreased as salinity increased. Rate limitations did not appear to relate to low oxygen levels or to the availability of organic nutrients. Some oxidation of
l
-[
U
-
14
C]glutamic acid occurred even at extreme salinities, whereas oxidation of [1-
14
C]hexadecane was too low to be detected. Gas chromatographic examination of hexane-soluble components of tar samples from natural seeps at Rozel Point in Great Salt Lake demonstrated no evidence of biological oxidation of isoprenoid alkanes subject to degradation in normal environments. Some hexane-soluble components of the same tar were altered by incubation in a low-salinity enrichment culture inoculated with garden soil. Attempts to enrich for microorganisms in saline waters able to use mineral oil as a sole source of carbon and energy were successful below, but not above, about 20% salinity. This study strongly suggests a general reduction of metabolic rate at extreme salinities and raises doubt about the biodegradation of hydrocarbons in hypersaline environments.
Comparison between adsorption of poliovirus and rotavirus by aluminum hydroxide and activated sludge flocs
Authors: Farrah S R , Goyal S M , Gerba C P , Conklin R H , Smith E M
Published: January 2020

Adsorption of poliovirus and rotavirus by aluminum hydroxide and activated sludge flocs was studied. Both aluminum hydroxide and activated sludge flocs adsorbed greater amounts of poliovirus than rotavirus. Aluminum hydroxide flocs reduced the titer of poliovirus in tap water by 3 log10, but they only reduced the titer of a simian rotovirus (SA-11) in tap water by 1 log10 or less and did not noticeably reduce the number of human rotavirus particles present in a dilute stool suspension. Activated sludge flocs reduced the titer of added poliovirus by 0.7 to 1.8 log10 and reduced the titer of SA-11 by 0.5 log10 or less. These studies indicate that a basic difference in the adsorptive behavior of enteroviruses and rotaviruses exists and that water and wastewater treatment processes that are highly effective in removal of enteroviruses may not be as effective in removing other viral groups such as rotaviruses.
Resistance of pathogenic Naegleria to some common physical and chemical agents
Authors: Chang S L
Published: January 2020

Resistance of pathogenic Naegleria to drying, low and high temperature, and two halogens was studied. Dying made trophozoites nonviable instantaneously and cysts nonviable in less than 5 min. Trophozoites degenerated in hours at temperatures below 10 degrees C and in minutes when frozen; cysts survived according to the equation th - t0/theta 1,440/1.122T (t0 is survival at 0 degrees C; Tis temperature between 0 and 10 degrees C), but 1.5 h at --10 degrees C to 1 h at --30 degrees C. At 51, 55, 58, 63, and 65 degrees C, trophozoites survived about 30, 10, 5, 1 and less than 0.5 min, respectively, cysts survived three to four times longer at 51 degrees C and six to seven times longer at 55 to 65 degrees C. Cyst destruction rates by heat indicated first-order kinetics with 25,400 cal/1 degree C for energy of activation. Cyst destruction rates by free chlorine and I2 also conformed to first-order kinetics. Concentration-contact time curves yielded concentration coefficient values of 1.05 for free chlorine and 1.4 for I2 and point to superchlorination as an effective means of destroying the cysts if free residuals are used as a guide and allowance is provided for low temperature and/or high pH waters.
Colonial variation, capsule formation, and bacteriophage resistance in Bacteroides thetaiotaomicron
Authors: Burt S , Meldrum S , Woods D R , Jones D T
Published: January 2020

A Bacteroides thetaiotaomicron strain segregated two unstable colonial variants at high frequency. There is a correlation between colony morphology, encapsulation, Giemsa staining, and bacteriophage resistance.
Adaptational change in proline and water content of Staphylococcus aureus after alteration of environmental salt concentration
Authors: Koujima I , Hayashi H , Tomochika K , Okabe A , Kanemasa Y
Published: January 2020

Adaptation of Staphylococcus aureus to a change in salinity was studied by estimating the intracellular content of water and proline after alteration of the salt concentration of the culture medium. The intracellular water content of S. aureus cultured in normal broth was 1.70 g/g (dry weight). After transfer to 1.8 M NaCl-containing broth, the water content decreased to 0.80 g/g (dry weight) within 1 min. After changing the salt concentration of the medium, intracellular free proline (assumed to be one of the osmoregulators in S. aureus) increased gradually from 0 to 1,400 mumol/g (dry weight) during 30 min of incubation at 37 degrees C. The water content rose to 0.88 g/g (dry weight) in 30 min. Proline was not taken up at 0 to 4 degrees C, suggesting that the process was one of active transport. The salt tolerance of S. aureus, therefore, appears to occur initially by dehydration of the cell after transfer from a medium of low salinity to one of high salinity and then by accumulation of proline, which carries water into the cell with it.
Recovery of sublethally heat-injured Salmonella typhimurium on supplemented plating media
Authors: D'Aoust J Y
Published: January 2020

The efficacy of 32 additives to Levine eosin-methylene blue-salts agar medium (EMBS) for the recovery of sublethally heat-injured Salmonella typhimurium was evaluated. In order of decreasing effectiveness, lactate, mannitol, and alpha-glycerophosphate mediated 90% or more recovery of injured cells; similar levels of recovery were obtained on EMBS supplemented with 1% (wt/vol) tryptic soy broth, protease peptone, or plate count agar. Other additives showed little or no capacity for repair or strongly inhibited heated and nonheated cell suspensions. Conditions of growth and storage before heat treatment were also found to markedly affect susceptibility to heat injury.
Distribution of the genus Leptospira in soil and water
Authors: Henry R A , Johnson R C
Published: January 2020

The distribution of the aerobic spirochetes Leptospira in surface waters, soil, and aquatic animals was investigated. Isolates from water and soil exhibited physiological characteristics common to members of the "biflexa complex," none were capable of infecting experimental animals, and leptospires could not be isolated from the eight genera of aquatic animals examined. The isolation frequencies from surface waters were: stream, 100%; lake, 65%; spring, 28%; bog lake, 5%; and marsh, 0%. With the exception of the stream, more isolations were obtained from the soil adjacent to the water than from the water. Leptospires were most frequently associated with soils of high moisture and organic matter content.
Changes in photosynthetic rate and pigment content of blue-green algae in Lake Mendota
Authors: Konopka A , Brock T D
Published: January 2020

Blue-green algal blooms were present in Lake Mendota (Dane County, Wis.) from June to November 1976. Concentrations of total algal biomass and of particular algal species were monitored and compared with the pigment contents (chlorophyll a and phycocyanin) and photosynthetic rate of the algal populations. The specific photosynthetic rate (micrograms of C fixed per microgram of chlorophyll a per hour) was a good measure of the physiological state of the algae because this quantity increased just before each population increase and decreased before algal densities diminished. Since the quantity of light in the epilimnion which was available for photosynthesis by algal cells decreased in summer when the high algal densities attenuated incoming radiation, we investigated the possibility that the organisms would utilize lower light intensities more efficiently by increasing their pigment contents. Although some evidence of enhanced utilization of low light levels was found in the period from July to October, this result was not due to increasing chlorophyll and phycocyanin contents. There was a decrease in the phycocyanin content of the algae during this period, perhaps related to the availability of inorganic nitrogen.
Relation between radiation resistance and salt sensitivity of spores of five strains of Clostridium botulinum types A, B, and E
Authors: Kiss I , Rhee C O , Grecz N , Roberts T A , Farkas J
Published: January 2020

The NaCl tolerance of different strains of Clostridium botulinum varies over a wide range, and the patterns of NaCl inhibition differ distinctly and characteristically from strain to strain. The more radiation-resistant strains, such as 33A, 62A, and 7272A, are more resistant to NaCl, whereas the more radiation-sensitive strains, such as 51B and 1304E, are more sensitive to NaCl. This rule appears to hold irrespective of whether the spores were unirradiated controls or whether they were radiation damaged prior to exposure to NaCl in the recovery media. The data seem to indicate that radiation doses in the shoulder portion of the radiation survival curves did not noticeably sensitive the spores to NaCl, whereas radiation doses in the exponential-decline portion of the survival curve invariably produced a distinct sensitization. Thus, strains 33A and 62A were not sensitized to NaCl by 0.3 to 0.4 Mrad, i.e., in the shoulder portion of the survival curve. Radiation-sensitive strain 51B, which shows no distinct shoulder in its survival curve, was sensitized to NaCl by 0.1 Mrad, the lowest radiation dose employed in this study. These observations seem to suggest a possible relationship between deoxyribonucleic acid repair capacity and salt tolerance.
Gentamicin-Based Medium for the Isolation of Group D Streptococci and Application of the Medium to Water Analysis
Authors: Donnelly L. Scott , Hartman Paul A.
Published: January 2020

Gentamicin-thallous-carbonate (GTC) medium contained (per liter): 40.0 g of Trypticase soy agar, 5.0 g of KH
2
PO
4
, 2.0 g of NaHCO
2
, 1.0 g of glucose, 1.0 g of esculin, 0.5 g of thallous acetate (TA), 0.5 g of ferric citrate, 0.75 ml of Tween 80, and 2.5 mg of gentamicin sulfate. The NaHCO
3
(20 ml of a 10% solution that had been heated to boiling) was added after sterilization of the basal medium. The spread plate technique was used to compare GTC agar with Pfizer selective enterococcus, TA, and KF agars by using sewage as well as bovine and swine fecal samples. Significantly greater numbers of group D streptococci were recovered on GTC agar than on Pfizer selective enterococcus or KF agars, within and over all samples. Higher counts also were obtained on GTC than on TA agar, but the differences were not statistically significant. The percentage of false positives was about the same for all four media. Samples of riverwater also were plated on GTC, TA, and KF agars, and significantly higher recoveries were obtained with GTC agar. GTC agar was superior to the other media examined primarily because of increased recoveries of
Streptococcus bovis
and
S. equinus
; other advantages of GTC agar were large colony size and short (24-h) incubation period. The percentage of false positives from riverwater was 13% for GTC agar and 0% for TA and KF agars; therefore, confirmation would be necessary when GTC agar is used with some types of environmental samples.
Characteristics of the constituent substrains of Bacillus popilliae growing in batch and continuous cultures
Authors: Sharpe E S , Bulla L A
Published: January 2020

Continuous culture of Bacillus popilliae was achieved for the first time in a small chemostat. Initially, variable cell yields during steady-state chemostat growth led to a re-examination of growth rates in batch cultures. B. popilliae NRRL B-2309 and a wild strain were both found to be natural mixtures of three substrains characterized by different growth rates and colony morphologies and varying stability. Selected subcultures grown continuously provided data for three different cell production curves. Cell yields were two to three times greater per unit of medium in continuous than in batch culture, and about 1% of slow-growing chemostat cells formed typical spores.
Isolation and cultivation of spirochetes and other spiral-shaped bacteria associated with the cecal mucosa of rats and mice
Authors: Lee A , Phillips M
Published: January 2020

A method for the culture of spiral-shaped bacteria associated with the intestinal mucosa of rodents is described. The appearance in culture of a spiral organism from rat ceca and a spirochete from mouse ceca is illustrated; these organisms are morphologically similar to the major inhabitants of the cecal mucosa in each animal species.
Improved Enrichment and Isolation Procedures for Obtaining Pure Cultures of
Beggiatoa
Authors: Burton Sheril D. , Lee John D.
Published: January 2020

Scoring agar surfaces with alginate swabs before placing washed filaments of
Beggiatoa
on the agar has greatly increased the rate at which single filaments move from contaminated areas. Numerous morphological types of pure cultures have been grown in organic media supplemented with either catalase or reducing agents. Aerated sewage was used as the enrichment source.
Incidence of airborne Aspergillus flavus spores in cornfields of five states
Authors: Bothast R J , Beuchat L R , Emswiller B S , Johnson M G , Pierson M D
Published: January 2020

Airborne Aspergillus flavus spores were rarely detected throughout the 1975 growing season by the agar plate method at cornfield sites in Georgia, Illinois, Maryland, South Carolina, and Virginia.
Growth of Prototheca isolates on n-hexadecane and mixed-hydrocarbon substrate
Authors: Walker J D , Pore R S
Published: January 2020

Prototheca zopfii, an achlorphyllous alga, was capable of using hydrocarbons as sole carbon and energy source. The ability of P. zopfii to use hydrocarbons did not correlate with source of isolation. Seventy-five percent of the P. zopfii cultures recovered from sewage, plants, or animals utilized hydrocarbons. Other Prototheca species and P. zopfii that did not utilize hydrocarbons were isolated simultaneously from several sources with isolates that did use hydrocarbons. Species type rather than source of isolation was the predominant factor that determined hydrocarbon utilization.
Use of fecal streptococci as indicators of pollution in soil
Authors: Kibbey H J , Hagedorn C , McCoy E L
Published: January 2020

The survival, recovery, and identification of Streptococcus isolates from soil was investigated by (i) examination of survival in soil under different moisture and temperature conditions, (ii) evaluation of media combinations for recovering fecal streptococci from soil, and (iii) partial identification of isolates from diverse habitats. Cool, moist conditions prolonged the survival of Streptococcus faecalis in soil for at least 12 weeks, whereas freezing was lethal, with the populations being reduced up to 95% when several freeze-thaw treatments occurred. Media evaluations indicated that both the efficiency of recovery and enumeration of the fecal streptococci from soil can be influenced by the combination of media used. Taxonomic data revealed a need to develop procedures to differentiate between isolates of fecal origin and plant-derived streptococci that possess many of the cultural reactions of S. faecalis. It was found that recent fecal isolates exhibited a much greater incidence of multiple antibiotic resistance than soil or vegetation isolates, and this characteristic, coupled with the use of enterococci as indicators of fecal contamination in soil systems, is discussed.
Reduction of Lactic Acid, Nonprotein Nitrogen, and Ash in Lactic Acid Whey by
Candida ingens
Culture
Authors: Ruiz Leonard P. , Gurnsey Joan C. , Short John L.
Published: January 2020

A simple, efficient procedure for removing lactic acid and for reducing nonprotein nitrogen and ash in lactic acid whey has been developed. The procedure consists of culturing
Candida ingens
on the whey. This organism could assimilate >98% of the lactic acid and approximately 40% of the nonprotein nitrogen. Ash reduction of up to 45% resulted from precipitation of calcium apatite due to the increase in pH from 4.4 to approximately 8.0 which occurred during growth of
C. ingens.
Improved fluxes during laboratory-scale ultrafiltration were obtained for the treated lactic acid whey.
C. ingens
treatment of lactic acid whey appears to facilitate processing of this material to a more useful product.
Bacteria isolated from the duodenum, ileum, and cecum of young chicks
Authors: Salanitro J P , Blake I G , Muirehead P A , Maglio M , Goodman J R
Published: January 2020

Facultatively anaerobic and strictly anaerobic bacteria colonizing the intestinal tracts of 14-day-old chicks fed a corn-based diet were enumerated, isolated, and identified. Colony counts from anaerobic roll tubes (rumen fluid medium) or aerobic plates (brain heart infusion agar) recovered from homogenates of the duodenum, upper and lower ileum, and cecum varied appreciably among samples from individual birds. Anaerobic and aerobic counts from the duodenum and ileum were similar. Anaerobic counts were highest from the cecum (0.7 X 10(11) to 1.6 X 10(11)/g of dry tissue) and exceeded aerobic plate counts by a factor of at least 10(2). Facultatively anaerobic groups (Streptococcus, Staphylococcus, Lactobacillus, and Escherichia coli) comprised the predominant flora of the duodenum and ileum, although large numbers of anaerobes (9 to 39% of the small intestine isolates), represented by species of Eubacterium, Propionibacterium, Clostridium, Gemmiger, and Fusobacterium, were also recovered. Strict anaerobes (anaerobic gram-positive cocci, Eubacterium, Clostridium Gemmiger, Fusobacterium, and Bacteriodes) made up nearly the entire microbial population of the cecum. Scanning electron microscopy of the intestinal epithelia of chicks revealed populations of microbes on the duodenal, ileal, and cecal mucosal surfaces.
PR toxin production in different Penicillium roqueforti strains
Authors: Wei R D , Liu G X
Published: January 2020

Different Penicillium roqueforti strains from the American Type Culture Collection were tested for the production of PR toxin. All four strains were able to produce the toxin on semisynthetic medium at 24 degrees C after certain periods of incubation. The yields were correlated with the pH of the medium. Timing of the harvest influenced both the yield and purification of the toxin.
Osmotically induced increase in thermal resistance of heat-sensitive, dipicolinic acid-less spores of Bacillus cereus Ht-8
Authors: Bhothipaksa K , Busta F F
Published: January 2020

Thermal resistance in heat-sensitive, dipicolinic acid (DPA)-less spores of Bacillus cereus Ht-8 heated in sucrose solutions increased at and above a concentration of 2 M sucrose. The decimal reduction times at 75 degrees C for spores heated in 0.0, 1.8, 2.2, and 2.6 M sucrose were 2.0, 2.8, 4.5, and 12 min, respectively. Maltose, fructose, and glucose increased heat resistance above that observed in water but did not elevate resistance to the level observed with sucrose at the same osmolality. Cation-induced loss of thermal resistance in chemically sensitized spores was reversed in the presence of sucrose. Spores germinated in brain heart infusion were resistant when heated in sucrose. In the presence of sucrose, spores exhibited an increase in optical density at 700 nm. Electron micrographs of the DPA-less spores suspended in 2.2 M sucrose revealed a shrinkage of outer coats and exosporium membranes. The results suggested that the osmotic property of sugars increased thermal resistance in DPA-less spores. The osmotic pressure exerted by sugars may be similar to the pressure that usually exists within the cortex of normal spores containing DPA and may cause the dehydration of the protoplast and the consequent thermal resistance. The role of dehydration and the nonessential nature of DPA for thermal resistance in spores were confirmed.
Plating procedure for the enumeration of coliforms from dairy products
Authors: Ray B , Speck M L
Published: January 2020

A "repair-detection" procedure consisting of pour plating of food samples with Trypticase soy agar, followed by 1-h repair incubation at room temperature and subsequent overlay with violet red bile agar, was found to be an effective method for the detection of injuried and uninjuried coliforms from dairy products. This method was relatively less effective for the detection of coliforms in many semipreserved foods as compared with dairy products, but more effective than the most-probable-number method.
Threonine production by regulatory mutants of Serratia marcescens
Authors: Komatsubara S , Kisumi M , Murata K , Chibata I
Published: January 2020

beta-Hydroxynorvaline (alpha-amino-beta-hydroxyvaleric acid)-resistant mutants of Serratia marcescens deficient in both threonine dehydrogenase and threonine deaminase were isolated and characterized. One of the mutants, strain HNr21, lacked feedback inhibition of threonine-sensitive aspartokinase and homoserine dehydrogenase, was repressed for the two enzymes, and produced 11 mg of threonine per ml of medium containing a limiting amount of isoleucine. The other mutant, strain HNr59, was constitutively derepressed for aspartokinase and homoserine dehydrogenase. Its kinase was sensitive to feedback inhibition, but its dehydrogenase was insensitive to feedback inhibition. This strain produced 5 mg of threonine per ml of medium containing either a limiting or an excess amount of isoleucine. Diaminopimelate auxotrophs derived from strain HNr59 produced more threonine (13 mg/ml) than the parent strain. However, similar auxotrophs derived from strain HNr21 produced the same amount of threonine as that produced by the parent strain.
Simultaneous determinations of nitrification and nitrate reduction in coastal sediments by a 15N dilution technique
Authors: Koike I , Hattori A
Published: January 2020

Nitrification, the oxidation of ammonia to nitrite and nitrate, and nitrate reduction by bacteria in coastal sediments of Mangoku-Ura and Odawa Bay were simultaneously determined by a 15N dilution technique. In muddy sediments of Mangoku-Ura, nitrate reduction proceeded at a rate of 10(-2) to 10 X 10(-2) microgram-atoms of N/g per h. Nitrification was far less intensive. Denitrification, or N2 production from nitrate, accounted for about 30% of the nitrate reduction. A simultaneous occurrence of nitrification and nitrate reduction with a similar rate of 10(-2) microgram-atoms of N/g per h was demonstrated in sandy sediment collected from a Zostera bed of Odawa Bay.
Causes of variation in botulinal inhibition in perishable canned cured meat
Authors: Tompkin R B , Christiansen L N , Shaparis A B
Published: January 2020

Final internal processing temperatures within the range of 63 to 74 degrees C did not alter the degree of botulinal inhibition in inoculated perishable canned comminuted cured pork abused at 27 degrees C. Adding hemoglobin to the formulation reduced residual nitrite after processing and decreased botulinal inhibition. Different meats yielded different rates of botulinal outgrowth when substituted for fresh pork ham. Pork or beef heart meat showed no inhibition of the Clostridium botulinum inoculum even with a 156-microgram/g amount of sodium nitrite added to the product. This effect appears to be one of stimulating outgrowth, since residual nitrite depletion was not measurably altered.
Control of nonspecific staining in the fluorescent antibody technique for the detection of salmonellae in foods
Authors: Swaminathan B , Ayres J C , Williams J E
Published: January 2020

A fluorescent antibody conjugate, prepared from the IgG (immunoglobulin G) fraction of Salmonella polyvalent flagellar antiserum, gave better specific staining intensities and significantly lower nonspecific staining than did conjugates prepared from globulin fractions of ammonium sulfate-fractionated Salmonella polyvalent antisera. IgG was purified by affinity chromatography against protein A, a normal cell wall component of Staphylococcus aureus. Affinity chromatography yielded high-purity IgG in a one-step purification procedure. The conjugate prepared from affinity-purified IgG was compared with commercially available fluorescent antibody conjugates for the detection of salmoneallae in retail samplings of meats and poultry and gave better correlations with the cultural method than did the commercial conjugates.
Anaerobic utilization of phosphite and hypophosphite by Bacillus sp
Authors: Foster T L , Winans L , Helms S J
Published: January 2020

A Bacillus sp. capable of utilizing phosphite and hypophosphite under anaerobic conditions was isolated from Cape Canerval soil samples. The organism was isolated on a glucose-mineral salts medium with phosphate deleted. Anaerobic cultivation of this isolate resulted in decreases in the hypophosphite or phosphite concentration, increases in turbidity, cell count, and dry-cell weight, and decreases in pH and glucose concentration. The optimum hypophosphite concentration for this isolate was 60 microgram/ml, whereas the optimum phosphate concentration was greater than 1,000 microgram/ml, suggesting that higher concentrations of hypophosphite may be toxic to this isolate. Hypophosphite or phosphite utilization was accompanied by little or no detectable accumulation of phosphate in the medium, and 32P-labeled hypophosphite was incorporated into the cell as organic phosphate. When phosphate was present in the medium, the isolate failed to metabolize phosphite. In the presence of phosphite and hypophosphite, the isolate first utilized phosphite and then hypophosphite.
Rapid sampling culture chamber
Authors: Carey A E , Schroeder B W
Published: January 2020

An all-glass chamber for culturing anaerobic and aerobic bacteria in liquid medium is described. The system permits both rapid sampling and turbidimetric measurements under controlled atmospheric conditions.
Thermophilic methanogenesis in a hot-spring algal-bacterial mat (71 to 30 degrees C)
Authors: Ward D M
Published: January 2020

Algal-bacterial mats which grow in the effluent channels of alkaline hot springs provided an environment suitable for studying natural thermophilic methane producing bacteria. Methane was rapidly produced in cores taken from the meat and appeared to be an end product of decomposition of the algal-bacterial organic matter. Formaldehyde prevented production of methane. Initial methanogenic rate was lower and methanogenesis became exponential when samples were permitted to cool before laboratory incubation. Methanogenesis occurred and methanogenic bacteria were present over a range of 68 to 30 degrees C, with optimum methanogenesis near 45 degrees C. The temperature distribution of methanogenesis in the mat is discussed relative to published results on standing crop, primary production, and decomposition in the thermal gradient. The depth distribution of methanogenesis was similar to that of freshwater sediments, with a zone of intense methanogenesis near the mat surface. Methanogenesis in deeper mat layers was very low or undetectable despite large numbers of viable methanogenic bacteria and could not be stimulated by addition of anoxic source water, sulfide, or a macronutrient solution.
Lignocellulose decomposition by selected streptomyces strains
Authors: Crawford D L
Published: January 2020

From 30 actinomycete cultures isolated by enrichment technique on agar media containing newsprint as a primary carbon and energy source, three Streptomyces strains were selected for characterization of their lignocellulose-decomposing abilities. All three streptomycetes were capable of oxidizing specifically 14C-labeled lignocelluloses to 14CO2. These Streptomyces were shown to attack primarily the cellulosic (glucan) components, of which between 25 to 40% evolved as 14CO2 during 1,025 h of incubation depending upon the culture used. Lignin labeled lignocelluloses were also attacked, but to a lesser degree, with up to about 3.5% being oxidized to 14CO2 depending upon the culture used. Additionally, it was shown that purified 14C-labeled milled-wood lignin was attacked, with recoveries of up to 17.7% of the label was 14CO2. This is the first conclusive evidence to show that streptomycetes can decompose lignin.
Transduction in Bacillus thuringiensis
Authors: Thorne C B
Published: January 2020

Bacteriophage CP-51, originally reported as a generalized transducing phage for Bacillus cereus and B. anthracis, has been shown to carry out generalized transduction in several strains of B. thuringiensis. A newly isolated phage, CP-54, which has a broader host range than CP-51, also mediates generalized transduction in B. thuringiensis. CP-51 and CP-54 are similar in size and morphology and are related serologically, but they are not identical. CP-54 is more cold labile than CP-51, and, as with CP-51, its stability both at 0 and 15 degrees C is enhanced by the presence of 0.02 M Mg2+. Some examples of cotransduction of linked markers in B. thuringiensis are presented, demonstrating the feasibility of chromosomal mapping in this organism. The rare occurrence of cross-transduction among strains of B. thuringiensis is probably a reflection of nonhomology rather than restriction, since phage itself did not appear to be restricted when grown on a particular host and assayed with other hosts as indicator.
Detection of mutagens produced by fungi with the Salmonella typhimurium assay
Authors: Bjeldanes L F , Chang G W , Thomson S V
Published: January 2020

Forty-one fungal isolates (one isolate per species) representing common plant pathogens and food crop contaminants were grown on sterile, polished rice and assayed for mutagenic activity in the Salmonella typhimurium-microsome system. Initially, single doses of aqueous and chloroform extracts of the moldy rice were assayed against the TA100 tester strain by incorporating extracts into the growth medium and by applying small quantities on disks placed on the agar surface. Suspected activity was examined further by analysis of several doses in the plate incorporation assay. Extracts of two aflatoxin-producing isolates (Aspergillus flavus and A. parasiticus) showed pronounced mutagenic activity, as did extracts of five other isolates (A. heterothallicus, A. nidulans, A. terricola, Alternaria tenuis, and Fusarium moniliforme) which did not contain detectable aflatoxins. Seven additional isolates (Botrytis cineria, Ceratocystis fimbriata, Cladosporium herbarum, Fusarium solani f. sp. pisi, Penicillium oxalicum, Thermomyces lanuginosus, and Verticilium albo-atrum) revealed activity which was possibly mutagenic; i.e., mutagenic responses were not observed in both the disk and incorporation assays, and clear dose-related activity was not observed in the incorporation assay. Extracts of the remaining fungi were not mutagenic in the bacterial assay.
Simple method for the isolation of astaxanthin from the basidiomycetous yeast Phaffia rhodozyma
Authors: Johnson E A , Villa T G , Lewis M J , Phaff H J
Published: January 2020

A method is described for the quantitative and, possibly, large-scale extraction of astaxanthin from the yeast Phaffia rhodozyma. The method utilizes extracellular enzymes produced by the bacterium Bacillus circulans WL-12, which partially digests the yeast cell wall and renders the carotenoid pigments extractable by acetone or ethanol. Complete recovery of astaxanthin from heat-killed P. rhodozyma cells was obtained after growing B. circulans WL-12 on these yeast cells for 26 h and then extracting the yeast-bacterium mixture with acetone. A bacteria-free lytic system, which gave quantitative extraction of astaxanthin from P. rhodozyma, was obtained by concentrating the culture broth from the growth of B. circulans WL-12 on P. rhodozyma cells. Hydrolytic enzyme activities detected in this concentrate included beta-(1 leads to 3)-glucanase, beta-(1 leads to 6)-glucanase, alpha-(1 leads to 3)-glucanase, xylanase, and chitinase. The lytic system was found to work most efficiently at pH 6.5 and with low concentrations of yeast.
Studies on an acetate-fermenting strain of Methanosarcina
Authors: Mah R A , Smith M R , Baresi L
Published: January 2020

An acetate-fermenting strain of Methanosarcina was isolated from an acetate enrichment culture inoculated with anaerobic sludge from a waste treatment digestor. In pure culture, this organism fermented acetate in the absence of added hydrogen at rates comparable in magnitude to those found in digestor systems. This rate was significantly higher than previously obtained for pure cultures of this genus. Mineral components of yeast extract were highly stimulatory for cultures growing on methanol. Comparable stimulation was not observed for cultures growing on acetate. Labeling studies indicated that acetate was converted to methane and CO2 as predicted by previous studies on mixed cultures. Total oxidation or reduction of acetate was not the mechanism of conversion of acetate to methane by the pure culture. The ability of this strain to form colonies or to produce methane from acetate was apparently influenced by the choice of substrate and conditions used for growing the inoculum.
Restriction endonuclease analysis to distinguish two closely related nuclear polyhedrosis viruses: Autographa californica MNPV and Trichoplusia ni MNPV
Authors: Miller L K , Dawes K P
Published: January 2020

Restriction endonuclease fragment patterns of the deoxyribonucleic acid genomes of Autographa californica nuclear polyhedrosis virus (multiply embedded type) and Trichoplusia ni nuclear polyhedrosis virus (multiply embedded type) demonstrate that the two viruses are distinct but closely related variants.
Antiviral effect of commercial juices and beverages
Authors: Konowalchuk J , Speirs J I
Published: January 2020

Nineteen commercial juices or beverages were tested for inactivation of poliovirus type 1. Grape and apple juices and tea were particularly antiviral. Although antiviral in aqueous solution, ascorbic acid was ineffective after addition to juices.
Isolation of an enteropathogenic, Kanagawa-positive strain of Vibrio parahaemolyticus from seafood implicated in acute gastroenteritis
Authors: Spite G T , Brown D F , Twedt R M
Published: January 2020

A strain of Vibrio parahaemolyticus, serotype O4/K4, that was Kanagawa positive and reactive in the rabbit ileal loop test, was isolated in low numbers from raw oysters implicated in a case of acute gastroenteritis. To our knowledge, this is the first report of the isolation of a Kanagawa-positive strain from suspect food in the United States.
Long-range air transmission of bacteria
Authors: Bovallius A , Bucht B , Roffey R , Anäs P
Published: January 2020

Bacterial spores from a sandstorm area north of the Black Sea were transmitted to Sweden by air, giving increased concentrations of viable bacterial spores at two air sampling stations in Sweden.
Comparison of selective media for coagulase-positive enterotoxigenic Staphylococcus aureus
Authors: Niskanen A , Aalto M
Published: January 2020

Different culture media were used to detect enterotoxigenic Staphylococcus aureus strains from peptone salt solution and inoculated minced meat. When recovery, reactions, and counting mistakes were considered, it was concluded that Baird-Parker agar was the best medium.
Improved methods for detecting enteric viruses in oysters
Authors: Sobsey M D , Carrick R J , Jensen H R
Published: January 2020

New and improved methods for concentrating enteroviruses, reoviruses, and adenoviruses from oysters have been developed and evaluated. Viruses are efficiently adsorbed to homogenized oyster meat by adjusting the homogenate to pH 5.0 and a conductivity of less than or equal to 2,000 mg of NaCl per liter. After low-speed centrifugation, the virus-free supernatant is discarded and the viruses are eluted from the sedimented oyster solids with pH 7.5 glycine-NaCl having a conductivity of 8,000 mg of NaCl per liter. The oyster solids are removed by low-speed centrifugation and filtration, and the viruses in the filtered supernatant are concentrated to a small volume by either ultrafiltration or acid precipitation at pH 4.5. The concentrate is treated with antibiotics and inoculated into cell cultures for virus isolation and quantitation. When these methods were tested with oysters experimentally contaminated with polioviruses, reoviruses, and adenoviruses, recovery efficiencies averaged about 46%. With the exception of virus assay and quantitation, these methods are simple and inexpensive enough to be done in typical shellfish microbiology laboratories.
Nitrogen Fixation (Acetylene Reduction) by Epiphytes of Freshwater Macrophytes
Authors: Finke Linda R. , Seeley H. W.
Published: January 2020

The involvement of epiphytic microorganisms in nitrogen fixation was investigated in a shallow freshwater pond near Ithaca, N.Y. The acetylene reduction technique was used to follow diel and seasonal cycles of nitrogen fixation by epiphytes of
Myriophyllum spicatum
. Acetylene-reducing activity was maximal between noon and 6 p.m., but substantial levels of activity relative to daytime rates continued through the night. Experiments with the seasonal course of activity showed a gradual decline during the autumn months and no activity in January or February. Activity commenced in May, with an abrupt increase to levels between 0.45 and 0.95 nmol of ethylene formed per mg (dry weight) of plant per h. Through most of the summer months, mean rates of acetylene reduction remained between 0.15 and 0.60 nmol/mg (dry weight) per h. It was calculated from diel and seasonal cycles that, in the pond areas studied, epiphytes were capable of adding from 7.5 to 12.5 μg of N per mg of plant per year to the pond. This amount is significant relative to the total amount of nitrogen incorporated into the plant. Blue-green algae (cyanobacteria), particularly
Gloeotrichia
, appeared to bear prime responsibility for nitrogen fixation, but photosynthetic bacteria of the genus
Rhodopseudomonas
were isolated from
M. spicatum
and shown to support high rates of acetylene reduction.