bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of microbial flora of the eye during wear of soft contact lenses
Authors: McBride M E
Published: January 2020

The microflora of the eye has been monitored in 21 patients during a 6-month period to study changes resulting from wear of soft contact lenses. A minimum of 20 cul-de-sac cultures were taken from each patient. Fifty-one percent of cultures taken prior to lens wear were positive for microbial growth, whereas, after lens wear, positive cultures ranged from 14.3% to 30.9" over the 6-month period. Staphylococcus epidermidis was the most frequently isolated organism, followed by Micrococcus spp., diphtheroids, and Bacillus spp. Nonfermentative, gram-negative rods and fungi were isolated spordically. Bacterial growth was sparse from all specimens, but individual differences were found. The microflora of the eye appears to resemble that of the skin, suggesting that the eye has no real flora of its own, but has a transient flora supplied from the skin, possibly the eyelid.
Deoxyribonucleic acid strand breaks during drying of Escherichia coli on a hydorohobic filter membrane
Authors: Asada S , Takano M , Shibasaki I
Published: January 2020

Cells of Escherichia coli mounted on a hydrophobic filter membrane were dried under various vapor pressures. A mutant defective in deoxyribonucleic acid repair (uvrA recA) was more sensitive to drying at a water activity of 0.53 or below than the parent strain but not at a water activity of 0.75 and above. Sucrose gradient studies showed that single- and double-strand breaks of deoxyribonucleic acid occurred at a water activity of 0.53 or below, but no breaks could be observed at a water activity of 0.75 or above. These results were observed in all cells rehydrated with 0.03 M tris (hydroxymethyl) aminomethane-hydrocholoride buffer solution at 0 or 37 degrees C, in the presence or absence of oxygen, with saturated water vapor or with a hypertonic solution followed by a gradual dilution. Freezable water was detected in the cells only at a water activity above 0.75 by differential scanning calorimetry. Removal of unfreezable water of cells in the drying, therfore, might induce deoxyribonucleic acid strand breaks.
Monensin and Dichloroacetamide Influences on Methane and Volatile Fatty Acid Production by Rumen Bacteria In Vitro
Authors: Slyter L. L.
Published: January 2020

The effect of monensin (0 or 33 μg/g of diet) upon rumen fermentation in the presence and absence of methanogenesis was determined in vitro by using mixed rumen organisms continuously cultured for 17 days. Methane was inhibited by dichloroacetamide (DCA; 32 mg/day) or by a pH of 5.1. Monensin effected a significant decrease in the ratio of acetic to propionic acid in the presence or absence of methanogenesis. In the absence of methanogenesis, the decrease in the ratio of acetic to propionic acid was entirely the result of increased propionic acid, whereas in the presence of methanogenesis the decrease in the ratio was the result of a combination of decreased acetic acid and increased propionic acid. There was a complementary interaction between monensin and DCA on volatile fatty acid production (expressed as millimoles of carbon per day). Addition of monensin to DCA-treated cultures resulted in the production of more acid; however, monensin and DCA had no beneficial effect on total carbon formed as acid and gases as compared with nonsupplemented control cultures. The monensin and DCA also resulted in greater digestion of neutral detergent fiber and less accumulation of formic acid and hydrogen as end products than did DCA alone.
l
-Lactic acid was produced in small but significantly greater amounts by the low-pH cultures, which also had less volatile fatty acid carbon formed from the fiber fraction of the forage supplied.
Phomopsin A production by Phomopsis leptostromiformis in liquid media
Authors: Lanigan G W , Payne A L , Smith L W , Wood P M , Petterson D S
Published: January 2020

Phomopsis leptostromiformis WA1515 produced 75 to 150 mg of phomopsin A per liter in stationary cultures in a Czapek-Dox medium supplemented with 5 to 10 g of yeast extract per liter. pH and temperature optima were approximately 6.0 and 25 degrees C, respectively. A commercial tryptic digest of casein was a satisfactory alternative to the yeast extract, but poor growth and very little phomopsin were obtained when the yeast was replaced by vitamin-free Casamino Acids or a mixture of 18 amino acids. Approximately 95% of the phomopsin A produced was found in the cutlure liquid. No phomopsin was detected in shaken cultures. No phomopsin B was found in any culture. Methods are described for recovery and estimation of phomopsin A from culture liquids.
Association of Actinomycete-Like Bacteria with Soil-Feeding Termites (Termitidae, Termitinae)
Authors: Bignell David E. , Oskarsson Hakon , Anderson Jonathan M.
Published: January 2020

Electron microscopy of the hindgut showed that actinomycete-like bacteria were the principal microbial associates of two African species of soil-feeding termites. Elongated cuticular spines provided attachment.
Territrems, tremorgenic mycotoxins of Aspergillus terreus
Authors: Ling K H , Yang C K , Peng F T
Published: January 2020

The tremorgenic mycotoxins isolated from Aspergillus terreus were given the trivial names territrem A and B instead of their previous designations of C1 and C2 respectively. High-resolution mass spectral data suggested the molecular formula of territrem A to be C28H30O9 and that of territrem B,C29H34O9. They were partially characterized by ultraviolet, infrared, proton magnetic resonance, and mass spectroscopy. The spectroscopic evidence indicated that their chemical structures were very similar. The procedures of purification were also revised for the complete separation of these two chemically related compounds.
Emulsifier of
Arthrobacter
RAG-1: Chemical and Physical Properties
Authors: Zuckerberg A. , Diver A. , Peeri Z. , Gutnick D. L. , Rosenberg E.
Published: January 2020

The extracellular emulsifier of
Arthrobacter
RAG-1 was deproteinized by hot phenol treatment and purified by fractional precipitation with (NH
4
)
2
SO
4
. The active fraction, precipitating between 30 and 35% saturation [EF-RAG(UET) WA], appeared to be homogeneous by immunodiffusion and sedimentation analysis. EF-RAG(UET) WA had an intrinsic viscosity of 750 cm
3
/g, a sedimentation constant of 6.06S, a diffusion constant of 5.25 × 10
−8
cm
2
s
−1
, and a partial molar volume of 0.712 cm
3
g
−1
. From these data a weight average molecular weight of 9.76 × 10
5
and a viscosity average molecular weight of 9.88 × 10
5
were calculated. EF-RAG(UET)WA contained 46.7% C, 7.01% H, and 6.06% N. Titration of the nonreducing polymer gave a single inflection point (pK′ = 3.05), corresponding to 1.5 μmol of carboxyl groups per mg. Direct estimation of O-ester and hexose content of the highly acidic polymer yielded 0.65 and 0.29 μmol/mg, respectively. Mild alkaline hydrolysis released fatty acids with an average molecular weight of about 231. Strong acid hydrolysis of EF-RAG(UET)WA yielded
d
-glucose (minor),
d
-galactosamine (major), and an unidentified amino uronic acid (major).
Metabolism of (+/-)-N-(n-propyl) amphetamine by Cunninghamella echinulata
Authors: Coutts R T , Foster B C , Jones G R , Myers G E
Published: January 2020

(+/-)-N-(n-propyl) amphetamine (I), a secondary amine, was readily metabolized by Cumminghamella echinulata. The products included known C- and N-oxygenated mammalian metabolites as well as N-acetylamphetamine and were identified by gas chromatography and mass spectrometry.
Occurrence of Vibrio parahaemolyticus in Dutch mussels
Authors: van den Broek M J , Mossel D A , Eggenkamp A E
Published: January 2020

A study was carried out on the occurrence of Vibrio parahaemolyticus in Dutch mussels originating from the East Schelde Estuary. In a totol of 79 10-g tissue samples, 3 (3.8%) were found to contain V. parahaemolyticus. In a second survey, 6 out of 23 bags of mussels (26%) contained one or more strains of V. parahaemolyticus in 5-g tissue samples. The many limitations of current methodology used in such surveys are stressed. Positive samples can be missed because viable cells may die during refrigerated transport. Surviving cells also may not be detected because they have been sublethally stressed. In addition, the unreliability of the identification criterion of no growth in 10% NaCl was demonstrated.
Heat resistance of Byssochlamys ascospores
Authors: Bayne H G , Michener H D
Published: January 2020

Ascospores from 25 strains of Byssochlamys were studied for their ability to resist heat treatment in a standard defined medium. Seven of these were able to survive heating at 90 degrees C for 25 min or longer, when initial numbers were frequently near 10(6)/ml. Ascospores from five resistant strains suspended in the medium at pH 5.0 were usually more resistant than those at pH 3.6. Rapid heat inactivation occurred for one strain at pH 6.6. Nonlogarithmic heat death rate was observed in all strains tested.
Poly-
β
-Hydroxybutyrate Accumulation as a Measure of Unbalanced Growth of the Estuarine Detrital Microbiota
Authors: Nickels Janet S. , King John D. , White David C.
Published: January 2020

The procaryotic endogenous storage material poly-
β
-hydroxybutyrate (PHB) can be induced to accumulate in the estuarine detrital microbiota under conditions which suggest unbalanced growth, such as limitation of a critical factor(s) in the presence of carbon and energy sources. Changes in PHB-to-lipid phosphate ratios detected in field samples can be mimicked in the laboratory with common estuarine stresses. Acute anoxia or low pH induces conditions of no growth with depression of both the synthesis and catabolism of PHB without change in the lipid phosphate. Balanced growth induced by nutrients increases the lipid phosphate, depresses PHB synthesis, and stimulates PHB catabolism, resulting in a low ratio of PHB to lipid phosphate. Unbalanced growth induced to a small extent by high salinity or much more readily by dark upland runoff water results in rapid accumulation of PHB and slowing of PHB catabolism with little change in lipid phospate. Unbalanced growth conditions result in high PHB-to-lipid phosphate ratios in the detrital microbiota.
Microbial Biomass and Activity Distribution in an Anoxic, Hypersaline Basin
Authors: LaRock Paul A. , Lauer Ray D. , Schwarz John R. , Watanabe Kathleen K. , Wiesenburg Denis A.
Published: January 2020

The Orca Basin is a hypersaline depression in the northern Gulf of Mexico with anoxic conditions observed in the lower 200 m of the water column. Measurements of adenosine 5′-triphosphate, heterotrophic potential, and uridine uptake made above and across the interface into the anoxic zone revealed the presence of an active microbial population approximately 100 m above the interface. Biomass and activity decreased at and just below the interface but increased near the bottom, consistent with similar observations made in the Cariaco Trench. The maximum adenosine 5′-triphosphate concentration above the interface of 5.9 ng/liter (2,173 m) is about eight times greater than the value found in oxygenated waters of corresponding depth in the absence of an anoxic zone. The maximum adenosine 5′-triphosphate concentration in the anoxic zone is approximately 15 times greater than that found in oxygenated water of similar depth, suggesting anoxia will support the development of a larger bacterial population. Our findings suggest that autotrophic bacteria may be the dominant physiological group in the region just above the interface.
Dialysis Continuous Process for Ammonium-Lactate Fermentation: Improved Mathematical Model and Use of Deproteinized Whey
Authors: Stieber R. W. , Gerhardt Philipp
Published: January 2020

Separate terms for substrate limitation and product inhibition were incorporated into an equation describing the rate of cell growth for the steady-state fermentation of lactose to lactic acid with neutralization to a constant pH by ammonia. The equation was incorporated into a generalized mathematical model of a dialysis continuous process for the fermentation, developed previously, in which the substrate is fed into the fermentor and the fermentor contents are dialyzed through a membrane against water. The improved model was used to simulate the fermentation on a digital computer, and the results agreed with previous experimental tests using whole whey as the substrate. Further simulations were then made to guide experimental tests using deproteinized whey as the substrate. Dried cheese-whey ultrafiltrate was rehydrated with tap water to contain 242 mg of lactose per ml, supplemented with 8 mg of yeast extract per ml, charged into a 5-liter fermentor without sterilization, adjusted in pH (5.5) and temperature (44°C), and inoculated with an adapted culture of
Lactobacillus bulgaricus.
The fermentor and dialysate circuits were connected, and a series of steady-state conditions was managed nonaseptically for 71 days. The fermentation of deproteinized whey relative to whole whey, with both highly concentrated, resulted in similar extents of product accumulation but at a lesser rate.
Comparison of Substrate Affinities Among Several Rumen Bacteria: a Possible Determinant of Rumen Bacterial Competition
Authors: Russell James B. , Baldwin R. L.
Published: January 2020

Five rumen bacteria,
Selenomonas ruminantium, Bacteroides ruminicola, Megasphaera elsdenii, Streptococcus bovis
, and
Butyrivibrio fibrisolvens
were grown in continuous culture. Estimates of substrate affinities were derived from Lineweaver-Burk plots of dilution rate versus substrate concentration. Each bacterium was grown on at least four of the six substrates: glucose, maltose, sucrose, cellobiose, xylose, and lactate. Wide variations in substrate affinities were seen among the substrates utilized by a species and among species for the same substrate. These wide differences indicate that substrate affinity may be a significant determinant of bacterial competition in the rumen where soluble substrate concentrations are often low. Growth of these bacteria in continuous culture did not always follow typical Michaelis-Menten kinetics. Inflated theoretical maximum growth rates and non-linear Lineweaver-Burk plots were sometimes seen. Maintenance energy expenditures and limitation of growth rate by factors other than substrate concentration (i.e., protein synthesis) are discussed as possible determinants of these deviations.
Conditions for induction of bacteriophage from lysogenic Bacillus megaterium with aflatoxin B1
Authors: Whittaker B L , Chipley J R
Published: January 2020

The present study was conducted to determine whether or not aflatoxin B1 was an effective inducing agent for lysogenic bacteria and to characterize some of the parameters involved in induction. A lysogenic strain of Bacillus megaterium (NRRL-B-3695) and an indicator strain of this species (NRRL-B-3694) were used. Cultures of the lysogenic strain were incubated for various periods of time in the presence of aflatoxin B1. Plaque-forming units as well as colony-forming units were then determined. Results of the present study indicated that bacteriophage lysogenizing B. megaterium could be induced with aflatoxin B1. The optimum concentration for induction was 25 micrograms of toxin per ml of early-log-phase culture. Evidence suggested that: (i) higher concentrations of aflatoxin B1 formed hydrophobic complexes which would not efficiently induce B. megaterium; (ii) the toxic effect of aflatoxin B1 severely limited the number of cells which could be induced prior to killing action of the toxin; and (iii) concentrations less than 25 micrograms of aflatoxin B1 per ml were not efficient inducers of bacteriophage production nor did they demonstrate the toxic effect observed at higher concentrations.
Ochratoxin A-induced iron deficiency anemia
Authors: Huff W E , Chang C F , Warren M F , Hamilton P B
Published: January 2020

Ochratoxin A at 8 micrograms per g of diet, but not at lower doses, fed to chickens from 1 day to 3 weeks of age resulted in significantly (P less than 0.05) decreased packed blood cell volume and hemoglobin concentration without altering the number of circulating erythrocytes. Serum iron and percentage of transferrin saturation were lowered at 4 and 8 micrograms/g. Therefore, anemia was characteristic of severe ochratoxicosis of young chickens, and the anemia was categorized as a hypochromic-microcytic anemia of the iron deficiency type. These data indicate that ochratoxin A by itself does not cause hemorrhagic anemia syndrome of chickens and that an anemia caused by a nutritional deficiency can be elicited by a mycotoxin.
Salmonella species isolated from animal feed in Iraq
Authors: Al-Hindawi N , Taha R R
Published: January 2020

Of 700 animal feed samples, 32 (4.5%) harbored Salmonella. The highest percentage of contamination was found in sheep feed and local protein. A total of 17 Salmonella serotypes were identified. The most frequent serotypes were Salmonella meleagridis. S. bornum, S. montevideo, and S. drypool. S. bornum was isolated for the first time in Iraq and from both local feed and its ingredients. The common somatic group found was that of Salmonella group C; then came groups E, G, B, and D. Three serotypes (S. enteritidis, S. california, and S. muenchen) seemed to form a link of infection among feed, food, patients, and carriers.
Conversion of Biovolume Measurements of Soil Organisms, Grown Under Various Moisture Tensions, to Biomass and Their Nutrient Content
Authors: van Veen Johannes A. , Paul Eldor A.
Published: January 2020

Direct microscopic measurements of biomass in soil require conversion factors for calculation of the mass of microorganisms from the measured volumes. These factors were determined for two bacteria, five fungi, and a yeast isolated from soil. Moisture stress conditions occurring in nature were simulated by growth in two media using shake cultures, on agar plates, and on membranes held at 34, 330, and 1,390 kPa of suction. The observed conversion factors, i.e., the ratio between dry weight and wet volume, generally increased with increasing moisture stress. The ratios for fungi ranged from 0.11 to 0.41 g/cm
3
with an average of 0.33 g/cm
3
. Correction of earlier data assuming 80% water and a wet-weight specific gravity of 1.1 would require a conversion factor of 1.44. The dry-weight specific gravity of bacteria and yeasts ranged from 0.38 to 1.4 g/cm
3
with an average of 0.8 g/cm
3
. These high values can only occur at 10% ash if no more than 50% of the cell is water, and a specific conversion factor to correct past data for bacterial biomass has not yet been suggested. The high conversion factors for bacteria and yeast could not be explained by shrinkage of cells due to heat fixing, but shrinkage during preparation could not be completely discounted. Moisture stress affected the C, N, and P content of the various organisms, with the ash contents increasing with increasing moisture stress. Although further work is necessary to obtain accurate conversion factors between biovolume and biomass, especially for bacteria, this study clearly indicates that existing data on the specific gravity and the water and nutrient content of microorganisms grown in shake cultures cannot be applied when quantifying the soil microbial biomass.
Method for Measuring Rates of NH
4
+
Turnover in Anoxic Marine Sediments, Using a
15
N-NH
4
+
Dilution Technique
Authors: Blackburn T. Henry
Published: January 2020

A method is described for the determination of the net and total rates of NH
4
+
production and NH
4
+
incorporation at different depths in an anoxic marine sediment.
15
N-NH
4
+
was added to the sediment NH
4
+
pool, and the
15
N content was assayed after 0, 2, and 5 days of incubation. The pool size changed during incubation; this change in pool size is incorporated into a model which predicts the dynamics of
15
N-NH
4
+
dilution. A simple microdiffusion of NH
3
was followed by an emission spectrometry analysis of
15
N content. This procedure avoided all problems of cross-contamination. The model was tested and rates were measured in four sediment cores, at seven different depths. The high correlation coefficients (mean, 0.96 for the 0- to 2-, 2- to 4-, 4- to 6-, and 6- to 8-cm sediment fractions) indicated that the model was correct and that the measured rates were valid. The immediate distribution of
15
N-NH
4
+
between interstitial and exchangeable NH
4
+
pools indicated that it was the combined pool that was turning over. In the 0- to 2-cm fraction at 17�C the net rate of NH
4
+
production was 274 (standard deviation, 31) nmol cm
−3
day
−1
, and the mean total rate of NH
4
+
production was 309 (standard deviation, 39) nmol cm
−3
day
−1
; both rates decreased to <1% of these values in the 12- to 14-cm fractions.
Partial reactivation of chlorine-treated echovirus
Authors: Young D C , Sharp D G
Published: January 2020

After treatment of a dispersed suspension of echovirus with HOCl, much of the lost plaque titer was restored if the treated virus was induced to aggregate by adjustment of the suspending medium to pH 4.5. This did not appear to be a repair of individual virions but rather a special kind of multiplicity-related increase in plaquing efficiency which occurred when the host cell received several of the damaged virions in a clump.
Determination of lipopolysaccharide by a bioluminescence technique
Authors: Ulitzur S , Yagen B , Rottem S
Published: January 2020

The determination of the lipid A content of bacterial lipopolysaccharide by using a dim mutant of the luminous bacterium Beneckea harveyi is described. The luminous bacteria emitted light upon the addition of an acid hydrolysate of lipopolysaccharide which contained myristic acid, thus making it possible to detect as little as 1 ng of lipopolysaccharide. By converting the 3-OH-myristic acid to myristic acid, it was possible to further increase the detection sensitivity and to establish a basis for a specific and highly sensitive bioassay for the detection of lipopolysaccharide.
New markers for Eubacterium lentum
Authors: Bokkenheuser V D , Winter J , Finegold S M , Sutter V L , Ritchie A E , Moore W E , Holdeman L V
Published: January 2020

Of 37 strains of Eubacterium lentum and phenotypically similar organisms, 26 (70%) synthesized a corticoid 21-dehydroxylase and/or a 3 alpha-hydroxysteroid dehydrogenase. It appeared that the corticoid 3 alpha-hydroxysteroid dehydrogenase was identical to the bile acid 3 alpha-hydroxysteroid dehydrogenase. Steroid-metabolizing enzymes were found both in E. lentum and in phenotypically similar organisms. E. lentum is characterized by nitrate reduction and enhanced growth in the presence of arginine. Many phenotypically similar organisms possess either one or the other of the two markers. In contrast, using the steroid-metabolizing enzymes as markers, a "steroid-active" and a "steroid-inactive" group were established with minimal overlapping of metabolic characteristics. Synthesis of the steroid enzymes was positively correlated with production of gas from H2O2 and formation of H2S. A simple method for the detection of corticoid 21-dehydroxylase and 3 alpha-hydroxysteroid dehydrogenase, one or both of which were present in 92% of the steroid-active group, is described.
Plant Growth Substances Produced by
Azospirillum brasilense
and Their Effect on the Growth of Pearl Millet (
Pennisetum americanum
L.)
Authors: Tien T. M. , Gaskins M. H. , Hubbell D. H.
Published: January 2020

Azospirillum brasilense,
a nitrogen-fixing bacterium found in the rhizosphere of various grass species, was investigated to establish the effect on plant growth of growth substances produced by the bacteria. Thin-layer chromatography, high-pressure liquid chromatography, and bioassay were used to separate and identify plant growth substances produced by the bacteria in liquid culture. Indole acetic acid and indole lactic acid were produced by
A. brasilense
from tryptophan. Indole acetic acid production increased with increasing tryptophan concentration from 1 to 100 μg/ml. Indole acetic acid concentration also increased with the age of the culture until bacteria reached the stationary phase. Shaking favored the production of indole acetic acid, especially in a medium containing nitrogen. A small but biologically significant amount of gibberellin was detected in the culture medium. Also at least three cytokinin-like substances, equivalent to about 0.001 μg of kinetin per ml, were present. The morphology of pearl millet roots changed when plants in solution culture were inoculated. The number of lateral roots was increased, and all lateral roots were densely covered with root hairs. Experiments with pure plant hormones showed that gibberellin causes increased production of lateral roots. Cytokinin stimulated root hair formation, but reduced lateral root production and elongation of the main root. Combinations of indole acetic acid, gibberellin, and kinetin produced changes in root morphology of pearl millet similar to those produced by inoculation with
A. brasilense.
Frequency of Dividing Cells, a New Approach to the Determination of Bacterial Growth Rates in Aquatic Environments
Authors: Hagström  , Larsson U. , Hörstedt P. , Normark S.
Published: January 2020

Frequency of dividing cells is suggested to be an indirect measure of the mean growth rate of an aquatic bacterial community. Seasonal changes in frequency of dividing cells were found which covariated with the bacterial uptake of
14
C-labeled phytoplankton exudates. Batch and continuous culture growth experiments, using brackish water bacteria in pure and mixed enrichment cultures, were performed to establish a relationship between frequency of dividing cells and growth rate. An improved technique for bacterial direct counts, using fluorescent staining and epifluorescence microscopy, is presented. Based on a 6-month survey in a coastal area of the Baltic Sea, the bacterial production in the photic zone is estimated. Compared to the total primary production in the area, the bacterial population during this period utilized approximately 25% of the amount of carbon originally fixed by the primary producers.
Nitrogen-Fixing (Acetylene Redution) Activity and Population of Aerobic Heterotrophic Nitrogen-Fixing Bacteria Associated with Wetland Rice
Authors: Watanabe Iwao , Barraquio Wilfredo L. , De Guzman Marcelino R. , Cabrera Delfin A.
Published: January 2020

Nitrogen-fixing activity associated with different wetland rice varieties was measured at various growth stages by an in situ acetylene reduction method after the activities of blue-green algae (cyanobacteria) in the flood water and on the lower portion of the rice stem were eliminated. Nitrogen-fixing activities associated with rice varieties differed with plant growth stages. The activities increased with plant age, and the maximum was about at heading stage. The nitrogen fixed during the whole cropping period was estimated at 5.9 kg of N per ha for variety IR26 (7 days) and 4.8 kg of N per ha for variety IR36 (95 days). The population of aerobic heterotrophic N
2
-fixing bacteria associated with rice roots and stems was determined by the most-probable-number method, using semisolid glucose-yeast extract and semisolid malate-yeast extract media. The addition of yeast extract to the glucose medium increased the number and activity of aerobic heterotrophic N
2
-fixing bacteria. The glucose-yeast extract medium gave higher counts of aerobic N
2
-fixing bacteria associated with rice roots than did the malate-yeast extract medium, on which
Spirillum
-like bacteria were usually observed. The lower portion of the rice stem was also inhabited by N
2
-fixing bacteria and was an active site of N
2
fixation.
Identification of the naturally occurring isomer of zearalenol produced by Fusarium roseum 'Gibbosum' in rice culture
Authors: Hagler W M , Mirocha C J , Pathre S V , Behrens J C
Published: January 2020

One diastereomer of trans-zearalenol [2,4-dihydroxy-6-(6,10-dihydroxy-trans-1-undecenyl)-benzoic acid-mu-lactone] was isolated from cultures of Fusarium roseum 'Gibbosum.' This strongly estrogenic metabolite was identified by analysis of its mass spectrum and its behavior in thin-layer, high-pressure liquid and gas-liquid chromatographic systems. The concentration of zearalenol in cultures was 563 mu g/g, or 7% of the 8,000-mu g/g zearalenone content, while the two diastereomers of 8'-hydroxyzearalenone each occurred at 3% of the zearalenone level. Of the two possible diastereomers of zearalenol, the one occurring in cultures was identical to the low-melting-point (171 degrees C) isomer (alpha) obtained by synthesis. In the rat uterus bioassay, the alpha zearalenol isomer was three times more estrogenic than zearalenone while the beta isomer was equal in activity in zearalenone. The two diastereomers of zearalenol can be distinguished from each other by the intensity of the m/e+ 302 fragment of the mass spectrum of the pure underivatized compound.
Population Densities of
Rhizobium japonicum
Strain 123 Estimated Directly in Soil and Rhizospheres
Authors: Reyes V. G. , Schmidt E. L.
Published: January 2020

Rhizobium japonicum
serotype 123 was enumerated in soil and rhizospheres by fluorescent antibody techniques. Counting efficiency was estimated to be about 30%. Indigenous populations of strain 123 ranged from a few hundred to a few thousand per gram of field soil before planting. Rhizosphere effects from field-grown soybean plants were modest, reaching a maximum of about 2 × 10
4
cells of strain 123 per g of inner rhizosphere soil in young (16-day-old) plants. Comparably slight rhizosphere stimulation was observed with field corn. High populations of strain 123 (2 × 10
6
to 3 × 10
6
cells per g) were found only in the disintegrating taproot rhizospheres of mature soybeans at harvest, and these populations declined rapidly after harvest. Pot experiments with the same soil provided data similar to those derived from the field experiments. Populations of strain 123 reached a maximum of about 10
5
cells per g of soybean rhizosphere soil, but most values were lower and were only slightly higher than values in wheat rhizosphere soil. Nitrogen treatments had little effect on strain 123 densities in legume and nonlegume rhizospheres or on the nodulation success of strain 123. No evidence was obtained for the widely accepted theory of specific stimulation, which has been proposed to account for the initiation of the
Rhizobium
-legume symbiosis.
Measuring Radioactive Methane with the Liquid Scintillation Counter
Authors: Zehnder Alexander J. B. , Huser Beat , Brock Thomas D.
Published: January 2020

Although a gas proportional counter is the most convenient method of measuring the radioactivity of fixed gases such as methane, it cannot be used when high nonradioactive concentrations of methane are present in the gas phase, due to quenching. If only methane and carbon dioxide are present in radioactive form in the gas phase, a liquid scintillation method for measuring these substances can be used. The procedure is described in detail, and the solubility of methane in liquid scintillation cocktails is determined.
Cytochrome Involvement in Mn(II) Oxidation by Two Marine Bacteria
Authors: Arcuri Edward J. , Ehrlich Henry L.
Published: January 2020

Two marine, Mn(II)-oxidizing bacterial cultures, BIII 45 and BIII 82, were examined spectrophotometrically at ambient temperature for their cytochrome complements. Membrane preparations from an ethylenediaminetetracetate-lysozyme treatment of 48-h cultures of both strains contained type
b, c
, and
o
cytochromes. No evidence for a type
a
cytochrome was noted. “Periplasmic” fractions of both strains also contained small amounts of cytochrome, including cytochrome
o
, but “intracellular” fractions did not. Type
c
cytochrome in membrane preparations of culture BIII 45 was consistently reduced by Mn(II) when the membranes were suspended in the periplasmic fraction of the culture. In the case of culture BIII 82, type
c
cytochrome in membrane preparations was consistently reduced by Mn(II) when the membranes were suspended in either periplasmic or intracellular fractions of the strain. Although, based on previous inhibitor studies, type
b
cytochrome was also expected to be reduced by Mn(II), no spectrophotometric evidence for its reduction was found, probably because not enough of it was reduced under the steady-state conditions of the experiments.
Comparison of Limulus assay, standard plate count, and total coliform count for microbiological assessment of renovated wastewater
Authors: Jorgensen J H , Lee J C , Alexander G A , Wolf H W
Published: January 2020

The Limulus endotoxin assay was compared to the standard plate count and total coliform count for assessment of the bacteriological quality of reclaimed wastewater. A total of 48 water samples from an advanced waste treatment plant in Dallas, Tex. were examined by the three techniques. Limulus assays were technically simpler to perform and provided results much sooner than conventional culture methods. However, the endotoxin values did not correlate extremely well with determinations of viable bacterial numbers. This lack of correlation may have been due to alterations in the normal ratio of viable gram-negative cells to endotoxin caused by water reclamation procedures.
Effect of Bacteria and Amoebae on Rhizosphere Phosphatase Activity
Authors: Gould W. Douglas , Coleman David C. , Rubink Amy J.
Published: January 2020

The contributions of various components of soil microflora and microfauna to rhizosphere phosphatase activity were determined with hydroponic cultures. Three treatments were employed: (i) plants alone (
Bouteloua gracilis
(H.B.K.) Lag. ex Steud.) (ii) plants plus bacteria (
Pseudomonas
sp.), and (iii) plants plus bacteria plus amoebae (
Acanthamoeba
sp.). No alkaline phosphatase was detected, but an appreciable amount of acid phosphatase activity (120 to 500 nmol of
p
-nitrophenylphosphate hydrolyzed per h per plant) was found in the root culture solutions. The presence of bacteria or bacteria and amoebae increased the amount of acid phosphatase in solution, and properties of additional activity were identical to properties of plant acid phosphatase. The presence of bacteria or bacteria and amoebae increased both solution and root phosphatase activities at most initial phosphate concentrations.
Bile Salt 3α- and 12α-Hydroxysteroid Dehydrogenases from
Eubacterium lentum
and Related Organisms
Authors: Macdonald Ian A. , Jellett Joanne F. , Mahony David E. , Holdeman Lillian V.
Published: January 2020

Thirty-two strains of
Eubacterium lentum
and phenotypically similar anaerobic gram-positive bacilli were screened for intracellular bile salt 3α- and 12α-hydroxysteroid dehydrogenase (HSDHase) activities. These organisms were categorized into four groups: (A) those containing 12α-HSDHase only (10 strains), (B) those containing 3α- and 12α-HSDHase (13 strains), (C) those containing 3α-HSDHase only (2 strains), and (D) those devoid of any measurable HSDHase activity (7 strains). Of the respective four groups, 9/10, 13/13, 0/2, and 0/7 were like the neotype strain of
E. lentum
(ATCC 25559) in that they produced H
2
S in a triple sugar iron agar butt, reduced nitrate to nitrite, and weakly decomposed hydrogen peroxide. The other strains were variable for nitrate reduction and activity on hydrogen peroxide, but all the organisms in the first three categories (with one exception) were H
2
S producers (triple sugar iron agar butt) and all (with one exception) were designated
E. lentum
, whereas the organisms of category B were non-H
2
S producers (triple sugar iron agar butt). Five of these seven were not stimulated by arginine and are designated “phenotypically similar organisms.” Thin-layer chromatography of extracted spent bacterial medium of four representative strains from each group grown in the presence of cholate revealed the presence of (A) 12-oxo product, (B) 12-oxo and 3-oxo products, (C) 3-oxo product, and (D) the absence of any of these products. The 12α-HSDHase of category B organisms was unstable unless 10
−3
M dithioerythritol was added to the buffer. With the exception of 3 out of 32 strains, there was a positive correlation between the production of measurable amounts of 12α-HSDHase and H
2
S production. Growth curves and the effect of arginine on growth and the production of 3α- and 12α-HSDHase were examined in representative strains of categories A, B, and C. Both enzymes were shown to bind onto a nicotinamide adenine dinucleotide-Sepharose column and could be eluted by high-ionic-strength buffer, resulting in approximately 25-fold and 18-fold purification, respectively. Molecular weight estimations by Sephadex G-200 gave values of 205,000 and 125,000 for the 3α- and 12α-HSDHase, respectively. Purified 12α-HSDHase was investigated with respect to pH requirement, substrate specificity, and enzyme kinetics.
Resolution of
Penicillium roqueforti
Toxin and Eremofortins A, B, and C by High-Performance Liquid Chromatography
Authors: Moreau S. , Masset A. , Biguet J.
Published: January 2020

A method for the quantitative analysis of
Penicillium roqueforti
toxin using a high-performance liquid chromatography system is proposed.
Microbial Activity in Organic Soils as Affected by Soil Depth and Crop
Authors: Tate Robert L.
Published: January 2020

The microbial activity of Pahokee muck, a lithic medisaprist, and the effect of various environmental factors, such as position in the profile and type of plant cover, were examined. Catabolic activity for [7-
14
C]salicylic acid, [1,4-
14
C]succinate, and [1,2-
14
C]acetate remained reasonably constant in surface (0 to 10 cm) soil samples from a fallow (bare) field from late in the wet season (May to September) through January. Late in January, the microbial activity toward all three compounds decreased approximately 50%. The microbial activity of the soil decreased with increasing depth of soil. Salicylate catabolism was the most sensitive to increasing moisture deep in the soil profile. At the end of the wet season, a 90% decrease in activity between the surface and the 60- to 70-cm depth occurred. Catabolism of acetate and succinate decreased approximately 75% in the same samples. Little effect of crop was observed. Variation in the microbial activity, as measured by the catabolism of labeled acetate, salicylate, or succinate, was not significant between a sugarcane (
Saccharum officinarum L.
) field and a fallow field. The activity with acetate was insignificantly different in a St. Augustine grass [
Stenotaphrum secundatum
(Walt) Kuntz] field, whereas the catabolism of the remaining substrates was elevated in the grass field. These results indicate that the total carbon evolved from the different levels of the soil profile by the microbial community oxidizing the soil organic matter decreased as the depth of the soil column increased. However, correction of the amount of carbon yielded at each level for the bulk density of that level reveals that the microbial contribution to the soil subsidence is approximately equivalent throughout the soil profile above the water table.
Mutagenic activity of Fusarium moniliforme isolates in the Salmonella typhimurium assay
Authors: Bjeldanes L F , Thomson S V
Published: January 2020

A total of 33 isolates of Fusarium moniliforme from several food or feed crops were grown on sterile cracked corn, and chloroform-isopropanol extracts were assayed for mutagenic activity in the Salmonella typhimurium-microsome system by using tester strain TA98 or TA100 or both. Extracts of 21 (64%) of the isolates assayed against TA100 were mutagenic. Activities of seven of these extracts were increased markedly with incorporation of the liver homogenate (S-9) into the assay. Seven (33%) of the isolates assayed against TA98 were weakly active, with the liver homogenate having little effect on reversion rates.
Effect of Ultraviolet-B (280 to 320 nm) Radiation on Blue-Green Algae (Cyanobacteria), Possible Biological Indicators of Stratospheric Ozone Depletion
Authors: Newton J. W. , Tyler D. D. , Slodki M. E.
Published: January 2020

The effect of ultraviolet-B (280 to 320 nm) irradiation on physiological activities of
Anabaena flos-aquae
and the water fern
Azolla caroliniana
has been studied under conditions where lethal effects of irradiation are absent. Nitrogenase activity, measured as acetylene reduction, specifically declined during irradiation with low levels of ultraviolet-B, whereas other physiological activities were unaffected. These findings indicate that measurement of acetylene reduction by cyanobacteria may serve as a specific, sensitive biochemical assay to assess environmental ultraviolet-B effects due to depletion of stratospheric ozone.
New prodigiosin-like pigment from Alteromonas rubra
Authors: Gerber N N , Gauthier M J
Published: January 2020

The red prodigiosin-like pigment from Alteromonas rubra was shown to be a mixture of prodigiosin (pigment 1) and a new cyclic isomer (pigment 2). The new structure was elucidated by mass and nuclear magnetic resonance spectra. Careful examinations of the prodigiosins produced by Serratia marcescens, Vibrio psychoerythrus, and an unidentified red bacterium (LL-100-6) failed to disclose any of the new pigment, pigment 2.
Nutritional Studies on Xanthan Production by
Xanthomonas campestris
NRRL B1459
Authors: Souw Peter , Demain Arnold L.
Published: January 2020

The nutritional requirements of
Xanthomonas campestris
NRRL B1459 for optimal xanthan production were studied in a chemically defined medium. Of the carbon sources tested, a 4% sucrose or glucose medium yielded the highest xanthan titers. The further addition of certain organic acids, such as succinate, pyruvate, and α-ketoglutarate, stimulated xanthan production; excess concentrations of these organic acids inhibited xanthan formation. Certain amino acids (e.g., glutamate) and nitrate salts were superior to ammonium salts for xanthan production. Concentrations of these nitrogen sources higher than the optimal levels inhibited xanthan production while stimulating growth. Xanthan production was also sensitive to high concentrations of inorganic phosphate. High xanthan potencies, up to 30 g/kg of broth, were achieved in these shake-flask studies, in which completely defined media were used.
Production of Lactase by
Candida pseudotropicalis
Grown in Whey
Authors: de Bales Sonia A. , Castillo Francisco J.
Published: January 2020

Lactase (β-
d
-galactosidase) was produced by
Candida pseudotropicalis
grown in deproteinized whey. Maximum enzyme production in 2% whey was obtained by supplementation with 0.15% yeast extract, 0.1% (NH
4
)
2
SO
4
, and 0.05% KH
2
PO
4
(wt/vol). Highest enzyme values (4.35 U/mg of cells and 68 U/ml) were obtained with 10 to 12% whey, while enzyme yield was maximal in 2% whey (0.87 U/mg of whey). Optimal initial pH for cultivation was 3.5. The best conditions for extraction included 2% (wt/vol) chloroform, 10 h of treatment, pH 6.6 and higher, and 30 to 37°C. Optimum pH and temperature for enzyme activity were 6.2 and 47°C. The enzyme had a
K

m

for
O
-nitrophenyl-β-
d
-galactopyranoside of 3.06 × 10
−3
M and the initial
V

max

was estimated as 6.63 × 10
−8
M per min. It hydrolized 50 and 100% of the lactose in whey and milk within 4 and 5 h, respectively, at 37°C. The lyophilized enzyme retained 95% of activity for 3 months when stored at −20°C.
Effect of Concentration of Organic Chemicals on Their Biodegradation by Natural Microbial Communities
Authors: Boethling Robert S. , Alexander Martin
Published: January 2020

The effect of concentration on the biodegradation of synthetic organic chemicals by natural microbial communities was investigated by adding individual
14
C-labeled organic compounds to stream water at various initial concentrations and measuring the formation of
14
CO
2
. The rate of degradation of
p
-chlorobenzoate and chloroacetate at initial concentrations of 47 pg/ml to 47 μg/ml fell markedly with lower initial concentrations, although half or more of the compound was converted to CO
2
in 8 days or less. On the other hand, little mineralization of 2,4-dichlorophenoxyacetate and 1-naphthyl-
N
-methylcarbamate, or the naphthol formed from the latter, occurred when these compounds were present at initial concentrations of 2 to 3 ng/ml or less, although 60% or more of the chemical initially present at higher concentrations was converted to CO
2
in 6 days. It is concluded that laboratory tests of biodegradation involving chemical concentrations greater than those in nature may not correctly assess the rate of biodegradation in natural ecosystems and that low substrate concentration may be important in limiting biodegradation in natural waters.
Seasonal and Geographic Distribution of Luminous Bacteria in the Eastern Mediterranean Sea and the Gulf of Elat
Authors: Yetinson T. , Shilo M.
Published: January 2020

Luminous bacteria in the Mediterranean Sea and the Gulf of Aqaba-Elat have different distribution patterns. In the Mediterranean Sea,
Beneckea harveyi
is present all year round, with different subtypes alternating in summer and winter;
Photobacterium fischeri
was only present during the winter. In the Gulf of Elat,
P. leiognathi
is present throughout the water column in similar densities during the entire year. This constancy in distribution is presumably due to the near-constancy in water temperature. In summer,
Photobacterium leiognathi
is replaced by
B. harveyi
in coastal surface waters. In the hypersaline Bardawil lagoon, only
B. harveyi
types are present.
P. fischeri
, a major component of the Mediterranean Sea winter communities, is absent from the lagoon. Luminous
Beneckea
strains show a great diversity in properties, e.g. temperature range for growth, sensitivity to infection by phages, sensitivity to attack by
Bdellovibrio
strains, and differences in tolerance to high-salinity shock. Therefore, subdivision of the taxonomic cluster of
B. harveyi
into subtypes is indicated. The composition of the luminous bacteria communities may serve as indicators of different marine water bodies. The symbiotic luminous bacteria of the light organ of the common Gulf of Elat fish,
Photoblepharon palbebratus steinitzi
, is different from any of the types described.
Microbial oxidation of gaseous hydrocarbons: epoxidation of C2 to C4 n-alkenes by methylotrophic bacteria
Authors: Hou C T , Patel R , Laskin A I , Barnabe N
Published: January 2020

Over 20 new cultures of methane-utilizing microbes, including obligate (types I and III) and facultative methylotrophic bacteria were isolated. In addition to their ability to oxidize methane to methanol, resting cell-suspensions of three distinct types of methane-grown bacteria (Methylosinus trichosporium OB3b [type II, obligate]; Methylococcus capsulatus CRL M1 NRRL B-11219 [type I, obligate]; and Methylobacterium organophilum CRL-26 NRRL B-11222 [facultative]) oxidize C2 to C4 n-alkenes to their corresponding 1,2-epoxides. The product 1,2-epoxides are not further metabolized and accumulate extracellularly. Methanol-grown cells do not have either the epoxidation or the hydroxylation activities. Among the substrate gaseous alkenes, propylene is oxidized at the highest rate. Methane inhibits the epoxidation of propylene. The stoichiometry of the consumption of propylene and oxygen and the production of propylene oxide is 1:1:1. The optimal conditions for in vivo epoxidation are described. Results from inhibition studies indicate that the same monooxygenase system catalyzes both the hydroxylation and the epoxidation reactions. Both the hydroxylation and epoxidation activities are located in the cell-free particulate fraction precipitated between 10,000 and 40,000 x g centrifugation.