bluuebunny/crossref_metadata_2025 huggingface dataset:
Variation in Heterotrophic and Autotrophic Nitrifier Populations in Relation to Nitrification in Organic Soils
Authors: Tate Robert L.
Published: January 2020

The occurrence of heterotrophic and autotrophic nitrifiers in Pahokee muck and the role of these organisms in the ecosystem were assessed by surveying their population densities under different field conditions and by observing the relationship of these populations with aerobic bacteria and soil moisture. Heterotrophic nitrifier populations varied from 2.0 × 10
5
to 3.8 × 10
6
bacteria per cm
3
of muck in surface fallow (bare) Pahokee muck during the annual cycle. This population decreased 40-fold between the surface and the 60- to 70-cm depths of soil. Similar variations were noted with autotrophic nitrifier populations. Significant correlations were found between heterotrophic nitrifiers and both soil moisture and aerobic bacteria. These relationships did not exist for the autotrophic nitrifiers. In soil that had been heated to kill the autotrophic nitrifiers, while preserving a population of the heterotrophs, and then amended with sodium acetate or ammonium sulfate or both, no nitrate or nitrite accumulated, although significant increases in heterotrophic nitrifiers were detected. In unheated control soil, nitrate plus nitrite-N increased from 14.3 to 181 μg/g of wet soil, and 48 μg of nitrite-N per g was produced. These data suggest that the autotrophic nitrifiers were the sole population responsible for nitrification in Pahokee muck.
Comparison of nine brands of membrane filter and the most-probable-number methods for total coliform enumeration in sewage-contaminated drinking water
Authors: Tobin R S , Lomax P , Kushner D J
Published: January 2020

Nine different brands of membrane filter were compared in the membrane filtration (MF) method, and those with the highest yields were compared against the most-probable-number (MPN) multiple-tube method for total coliform enumeration in simulated sewage-contaminated tap water. The water was chlorinated for 30 min to subject the organisms to stresses similar to those encountered during treatment and distribution of drinking water. Significant differences were observed among membranes in four of the six experiments, with two- to four-times-higher recoveries between the membranes at each extreme of recovery. When results from the membranes with the highest total coliform recovery rate were compared with the MPN results, the MF results were found significantly higher in one experiment and equivalent to the MPN results in the other five experiments. A comparison was made of the species enumerated by these methods; in general the two methods enumerated a similar spectrum of organisms, with some indication that the MF method was subject to greater interference by Aeromonas.
Rapid radiometric method for detection of Salmonella in foods
Authors: Stewart B J , Eyles M J , Murrell W G
Published: January 2020

A radiometric method for the detection of Salmonella in foods has been developed which is based on Salmonella poly H agglutinating serum preventing Salmonella from producing 14CO2 from [14C]dulcitol. The method will detect the presence or absence of Salmonella in a product within 30 h compared to 4 to 5 days by routine culture methods. The method has been evaluated against a routine culture method using 58 samples of food. The overall agreement was 91%. Five samples negative for Salmonella by the routine method were positive by the radiometric method. These may have been false positives. However, the routine method may have failed to detect Salmonella due to the presence of large numbers of lactose-fermenting bacteria which hindered isolation of Salmonella colonies on the selective agar plates.
Purification of the envelope glycoproteins of western equine encephalitis virus by glass wool column chromatography
Authors: Yamamoto K , Simizu B
Published: January 2020

Glass wool column chromatography was used for separation of the two glycoproteins of western equine encephalitis virus. Cross-contamination of each protein separated was confirmed to be negligible by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
Lipase Induction in
Mucor hiemalis
Authors: Akhtar M. Waheed , Mirza A. Q. , Chughtai M. I. D.
Published: January 2020

The influence on lipase induction in
Mucor hiemalis
of different types of triglycerides containing mainly oleic acid (olive oil), erucic acid (mustard oil), or saturated fatty acids of 8 to 16 carbons (coconut oil) was studied. The fungus was grown in shake flasks in a fermentation medium containing peptone, minerals, and glucose or one of the oils as the carbon source. Maximum lipase was produced when the initial pH of the fermentation medium was kept at 4.0. Addition of Ca
2+
to the medium did not increase lipase production. The optimum pH for activity of both the mycelial and extracellular lipases was found to be 7.0. The fungus produced a significant amount of lipase in the presence of glucose, but the lipase activity increased markedly when olive oil was added to the medium at the beginning of the fermentation. Addition of olive oil at a later stage did not induce as much enzyme. Studies with washed mycelia showed that a greater amount of lipase was released when olive oil was present than when glucose was present. Among the various types of triglycerides used as the carbon source, olive oil was found to be most effective in inducing the lipase. Olive oil and mustard oil fatty acids inhibited the lipase more than those of coconut oil. The lipase induced by a particular type of triglyceride did not seem to be specific for the same triglyceride, nor was it inhibited specifically by it. Irrespective of the triglyceride used in the fermentation medium, the lipase produced was most active against coconut oil triglyceride, and this specificity, as shown by lipase activities in an
n
-heptane system, was not found to be due to a better emulsification of this oil. The lipase of
M. hiemalis
can be considered to be both constitutive and inducible.
Comparison of In Situ and In Vitro Rates of Methane Release in Freshwater Sediments
Authors: Kelly C. A. , Chynoweth D. P.
Published: January 2020

Anaerobic lake sediment incubated in vitro was investigated for its ability to mimic natural in situ sediment activities, using rate of methane production for the comparison. Two lakes with different rates and seasonal patterns of methanogenic activity were compared. There was good agreement (at the 97.5% confidence level) between rates of in situ methane release and initial (lasting an average of 120 h) rates of production measured in vitro in surface (0- to 3-cm) sediment. Evidence from this study, and others, indicated that it is the in situ surface sediment methane production which is primarily responsible for maintaining in situ methane release, and thus the above agreement was what was expected if surface in situ activity was maintained in vitro. When deeper sediment was investigated, however, the sum of in vitro rates from 0 to 20 cm (measured in 1.5- to 3-cm intervals) was much higher than in situ release rates and would have resulted in an impossibly high volume of gas. The extra gas could not have been stored within the sediments. We conclude that the in situ methanogenic activity of the 0- to 3-cm anaerobic surface sediments could be preserved during removal and laboratory incubation. However, similar treatment of deeper sediment appeared to stimulate methanogenic activity.
Some Effects of Douglas Fir Terpenes on Certain Microorganisms
Authors: Andrews R. E. , Parks L. W. , Spence K. D.
Published: January 2020

The Douglas fir terpene α-pinene was shown to inhibit the growth of a variety of bacteria and a yeast. Other terpenes of the Douglas fir, including limonene, camphene, and isobornyl acetate, were also inhibitory to
Bacillus thuringiensis
. All terpenes were inhibitory at concentrations normally present in the fir needle diet of Douglas fir tussock moth larvae. The presence of such terpenes in the diet of these insects was found to strongly influence the infectivity of
B. thuringiensis
spores for the Douglas fir tussock moth larvae. The terpene α-pinene destroyed the cellular integrity and modified mitochondrial activity in certain microorganisms.
Variation in Microbial Activity in Histosols and Its Relationship to Soil Moisture
Authors: Tate Robert L. , Terry Richard E.
Published: January 2020

Microbial biomass, dehydrogenase activity, carbon metabolism, and aerobic bacterial populations were examined in cropped and fallow Pahokee muck (a lithic medisaprist) of the Florida Everglades. Dehydrogenase activity was two- to sevenfold greater in soil cropped to St. Augustinegrass (
Stenotaphrum secundatum
(Walt) Kuntz) compared with uncropped soil, whereas biomass ranged from equivalence in the two soils to a threefold stimulation in the cropped soil. Biomass in soil cropped to sugarcane (
Saccharum
spp. L) approximated that from the grass field, whereas dehydrogenase activities of the cane soil were nearly equivalent to those of the fallow soil. Microbial biomass, dehydrogenase activity, aerobic bacterial populations, and salicylate oxidation rates all correlated with soil moisture levels. These data indicate that within the moisture ranges detected in the surface soils, increased moisture stimulated microbial activity, whereas within the soil profile where moisture ranges reached saturation, increased moisture inhibited aerobic activities and stimulated anaerobic processes.
Cage Culture Turbidostat: a Device for Rapid Determination of Algal Growth Rate
Authors: Skipnes Olav , Eide Ingvar , Jensen Arne
Published: January 2020

The present cage culture turbidostat consists of a growth chamber and a control unit. The microorganisms (photoautotrophic algae) are kept in the growth chamber by porous membranes (pore size 1 to 3 μm) which retain the algae but allow efficient exchange of the growth medium. Flow rate and composition of the medium can therefore be varied independently of algal population density. A reciprocating pumping mode of the medium is introduced to obtain more gentle clearance of membranes than that provided by rotation or stirring in other membrane fermentors. Pulsed light and a light-emitting diode/light-sensitive transistor couple are used to monitor the turbidity of the culture, independent of external light needed for growth. The control unit keeps the turbidity constant by frequent activation of the dilution pump. Theoretical analysis of growth in the turbidostat shows that integrated activation time of the dilution pump is proportional to the growth rate of the organism. Theoretical analysis was also used to determine minimum flow-rate and nutrient concentration of medium to cover the requirement of the algae. Experiments with three different marine diatoms were carried out, and they demonstrated that the growth rate could be determined every hour and that the cultures could be kept at constant turbidity over 10 to 14 days at least.
Estimation of Escherichia coli in raw ground beef
Authors: Stiles M E , Ng L K
Published: January 2020

This study was undertaken to establish and evaluate more rapid methods of estimating Escherichia coli in ground beef than the standard most probable number (MPN) technique. Direct inoculation of and modifications to EC medium gave unreliable estimates of the presumptive E. coli count. Solid media incubated at an elevated temperature were compared to the MPN technique. Anderson and Baird-Parker's tryptone bile agar (TBA) method and prepoured plates of Endo, Levine eosin methylene blue (EMB), and violet red bile (VRBA) agars incubated at 44 degree C gave equivalent counts to the standard MPN method. Anderson and Baird-Parker TBA was the most selective solid medium for E. coli estimation, but all selective media incubated at elevated temperature reduced apparent E. coli counts by as much as 50%. Indole-producing and lactose-fermenting Enterobacteriaceae, capable of growth at elevated temperature, were tested for their growth on TBA, EMB, and VRBA at elevated temperature. TBA was selective for E. coli biotype I compared to other Enterobacteriaceae that predominate in meats. VRBA and EMB incubated at elevated temperature were not as selective as TBA, but differences in colonies could be observed between typical E. coli colonies and other Enterobacteriaceae on these media. Therefore, VRBA incubated at elevated temperature is proposed as a quality assurance screening test for presumptive E. coli in ground meat. Resuscitation techniques and prepoured plates with VRBA increased recovery levels of presumptive E. coli, but, under the conditions of this study, not to levels that represented a significant practical difference.
Recovery of Indigenous Viruses from Wastewater Sludges, Using a Bentonite Concentration Procedure
Authors: Turk Christopher A. , Moore Barbara E. , Sagik Bernard P. , Sorber Charles A.
Published: January 2020

A distilled water elution-bentonite concentration technique was developed and used to monitor indigenous viruses present in liquid sludges undergoing land application at six field sites.
Antagonism Between Osmophilic Lactic Acid Bacteria and Yeasts in Brine Fermentation of Soy Sauce
Authors: Noda Fumio , Hayashi Kazuya , Mizunuma Takeji
Published: January 2020

Brine fermentation by osmophilic lactic acid bacteria and yeasts for long periods of time is essential to produce a good quality of shoyu (Japanese fermented soy sauce). It is well known that lactic acid fermentation by osmophilic lactic acid bacteria results in the depression of alcoholic fermentation by osmophilic yeasts, but the nature of the interaction between osmophilic lactic acid bacteria and yeasts in brine fermentation of shoyu has not been revealed. The inhibitory effect of osmophilic lactic acid bacteria on the growth of osmophilic yeasts was investigated. It was recognized that osmophilic shoyu yeasts such as
Saccharomyces rouxii
and
Torulopsis versatilis
were inhibited by a metabolite produced by osmophilic lactic acid bacteria (belonging to
Pediococcus halophilus
) in brine fermentation of shoyu. The primary inhibitor was considered to be acetic acid, although lactic acid was slightly inhibitory.
Mutagenicity of islandicin and chrysophanol in the Salmonella/microsome system
Authors: Liberman D F , Schaefer F L , Fink R C , Ramgopal M , Ghosh A C , Mulcahy R
Published: January 2020

Chrysophanol and islandicin, two anthraquinones which are structurally related to emodin, were found to be frame-shift mutagens for Salmonella typhimurium strain TA 1537 after metabolic activation.
Heat resistance of the chemical resistance forms of Clostridium botulinum 62A spores over the water activity range 0 to 0.9
Authors: Alderton G , Chen J K , Ito K A
Published: January 2020

Having available the separate chemical resistance forms of Clostridium botulinum 62A spores from an investigation of the effect of spore form on wet heat resistance and also a method for measuring heat resistance at known water activities over the whole water activity (aw) range, we measured the heat resistance of these preparations at four different temperatures at each aw interval of 0.1 from aw 0 to aw 0.9. The required temperature dependence of resistance was calculated for each aw increment. The spore forms showed a low resistance at aw values of 0 and 0.7 of 0.9, with a rise in resistance in the range aw 0.1 to 0.5. The temperature dependence values behaved similarly.
Effects of Alkaline Phosphatase Activity on Nucleotide Measurements in Aquatic Microbial Communities
Authors: Karl D. M. , Craven D. B.
Published: January 2020

Alkaline phosphatase (APase) activity was detected in aquatic microbial assemblages from the subtropics to Antarctica. The occurrence of APase in environmental nucleotide extracts was shown to significantly affect the measured concentrations of cellular nucleotides (adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, guanosine triphosphate, uridine triphosphate, and cytidine triphosphate), adenylate energy charge, and guanosine triphosphate/adenosine triphosphate ratios, when conventional methods of nucleotide extraction were employed. Under the reaction conditions specified in this report, the initial rate of hydrolysis of adenosine triphosphate was directly proportional to the activity of APase in the sample extracts and consequently can be used as a sensitive measure of APase activity. A method was devised for obtaining reliable nucleotide measurements in naturally occurring microbial populations containing elevated levels of APase activity. The metabolic significance of APase activity in microbial cells is discussed, and it is concluded that the occurrence and regulation of APase in nature is dependent upon microscale inorganic phosphate limitation of the autochthonous microbial communities.
Collagenase Production by Nematode-Trapping Fungi
Authors: Schenck Susan , Chase Theodore , Rosenzweig W. D. , Pramer David
Published: January 2020

A number of species of nematode-trapping fungi, which capture and digest nematodes having keratin and collagen in their cuticles, were tested for the ability to produce extracellular collagenase and keratinase. Collagenase, which is active on ichthyocol, earthworm collagen, and procollagen from chicken embryo fibroblasts, was found in the growth medium of all tested species; keratinase was not found. The enzyme from
Arthrobotrys amerospora
was concentrated by precipitation with (NH
4
)
2
SO
4
and further purified by adsorption on collagen at 0°C. The collagenase was active over a pH range of 2.5 to 10.0. It was not inactivated by dialysis against ethylenediaminetetraacetic acid for 48 h or by the sulfhydryl group inhibitors
N
-ethylmaleimide and
p
-chloromercuribenzoate. The production of collagenase may aid the fungus to penetrate the cuticle of its prey.
Sequence of Events in the Digestion of Fresh Legume Leaves by Rumen Bacteria
Authors: Cheng K.-J. , Fay J. P. , Howarth R. E. , Costerton J. W.
Published: January 2020

When fresh whole leaves of six different species of forage legumes were suspended in an artificial rumen medium and inoculated with rumen bacteria, bacterial adhesion and proliferation were noted at the stomata, and penetration of the stomate by these bacteria was documented by electron microscopy. The invading bacteria adhered to surfaces within the intercellular space of the leaf and produced very extensive exopolysaccharide-enclosed microcolonies. After some of the legume leaf cell walls were disorganized and ruptured by bacterial digestion, these cells (notably, parenchyma and epidermal cells) were invaded by bacteria, with subsequent formation of intracellular microcolonies. However, other cells were neither ruptured nor colonized (notably, stomata guard cells and vascular tissue). At all stages of the digestion of intact legume leaves, the rumen bacteria grew in microcolonies composed of cells of single or mixed morphological types, and a particular ecological niche was often completely and consistently occupied by a very large microcolony of cells of single or mixed morphological types.
Adherence as a method of differentiating virulent and avirulent strains of Vibrio parahaemolyticus
Authors: Hackney C R , Kleeman E G , Ray B , Speck M L
Published: January 2020

Usually only Kanagawa-positive strains of Vibrio parahaemolyticus are considered virulent; yet, a significant portion of V. parahaemolyticus food poisonings appear to be caused by Kanagawa-negative strains. Therefore, additional and more accurate measurements of a strain's food-poisoning potential are needed. Adherence of V. parahaemolyticus to human fetal intestinal (HFI) cells in vitro seems to offer this information. All strains of V. parahaemolyticus adhered to the HFI cells, but the degree of adherence was related to a number of factors. These included the age of the culture, the strain's Kanagawa reaction and source, the length of time the bacteria were exposed to the HFI cells, and the composition of the growth medium. Cells harvested during the late log phase of growth adhered more intensely than those harvested from the late stationary phase. Virulent strains, i.e., those involved in food poisoning, were observed to have a high adherence ability regardless of their Kanagawa reaction, whereas Kanagawa-negative strains isolated from seafood exhibited weak adherence intensities. Kanagawa-positive strains isolated from seafood adhered strongly to the HFI cells. The difference between the virulent and avirulent strains was quantitative in nature, and the greatest differences in adherence intensities were observed after short (10 to 15 min) exposure times. The presence of ferric iron in the growth medium was found to increase the adherence intensities of the virulent strains.
Effects of Grazing by Estuarine Gammaridean Amphipods on the Microbiota of Allochthonous Detritus
Authors: Morrison Susan J. , White David C.
Published: January 2020

Estuarine gammaridean amphipods grazing at natural population density on detrital microbiota affected the microbial community composition, biomass, and metabolic activity without affecting the physical structure of the leaves. Total microbial biomass estimated by adenosine triphosphate and lipid phosphate or observed by scanning electron microscopy was greater on grazed than on ungrazed detritus. The rates of oxygen consumption, poly-β-hydroxybutyrate synthesis, total lipid biosynthesis, and release of
14
CO
2
from radioactively prelabeled microbiota were higher on grazed than on ungrazed leaves, indicating stimulation of the metabolic activity of grazed detrital microbes. This was true with rates based either on the dry leaf weight or microbial biomass. Alkaline phosphatase activity was lower in the grazed system, consistent with enhanced inorganic phosphate cycling. The loss of
14
C from both total lipid and poly-β-hydroxybutyrate of microorganisms prelabeled with
14
C was greater from grazed than ungrazed microbes. There was a faster decrease in the
14
C-glycolipid than in the
14
C-neutral lipid or
14
C-phospholipid fractions. Analysis of specific phospholipids showed losses of the metabolically stable [
14
C]glycerolphosphorylcholine derived from phosphatidylcholine and much more rapid metabolism of the bacterial lipid phosphatidylglycerol measured as [
14
C]glycerolphosphorylglycerol with amphipod grazing. The biochemical data supported scanning electron microscopy observations of a shift as the grazing proceeded from a bacterial/fungal community to one dominated by bacteria.
Effect of monensin on fermentation characteristics of the artificial rumen
Authors: Wallace R J , Cheng K J , Czerkawski J W
Published: January 2020

Addition of monensin (Rumensin, Eli Lilly and Co.) to an artificial rumen immediately depressed the digestion of roughage and of roughage/concentrate (50:50) feeds. Methane and propionate production were affected only with the roughage/concentrate feed.
Measurement of Mercury Methylation in Lake Water and Sediment Samples
Authors: Furutani Akira , Rudd John W. M.
Published: January 2020

Biological mercury methylation was assayed by a new radiochemical technique in the water column and sediments of a mercury-contaminated lake. In 24 weeks during 1979, there were three episodes of methylating activity in surface floc and in water, each lasting 3 to 5 weeks. Periods of methylation in the water column coincided with surface sediment methylation and appeared to be related to overall microbial activity. Mercury was actively methylated in the presence of bound sulfide.
Mercury methylation by fish intestinal contents
Authors: Rudd J W , Furutani A , Turner M A
Published: January 2020

A new radiochemical method has been applied to the examination of mercury methylation in fish intestinal contents. Intestinal contents of six freshwater fish species were found capable of converting 203Hg2+ to CH3203Hg+. This activity was observed in fish from five of six lakes tested whether or not there was mercury pollution. Bacterial activity in the intestinal contents is most likely responsible for this methylation. Methylating activity of piscivors increased with decreasing quantity of intestinal contents. Generally, pike and walleye intestinal contents methylated a larger fraction of 203Hg2+ than those of whitefish and suckers. These data contradict the previous general conclusion that there is no mercury methylation in fish.
Combined membrane filtration-electrochemical microbial detection method
Authors: Wilkins J R , Grana D C , Fox S S
Published: January 2020

The electrochemical method was used successfully to detect Escherichia coli cells retained on membrane filters. Preliminary results suggest that the combined technique could be used to predict the microbial loading of water samples.
Effect of aeration and carbon dioxide on cell morphology of Candida utilis
Authors: Straskrabová V , Páca J , Králícková E
Published: January 2020

The effect of CO2 availability on cell size, shape, and aggregation in continuous cultures of Candida utilis was studied in minimal medium with glucose or ethanol as the sole carbon and energy source. Enrichment with CO2 was achieved (i) by using the substrate with more C atoms, (ii) by using pure oxygen and thus decreasing aeration intensity at the same dissolved-oxygen concentration, or (iii) by adding CO2 to the aeration gas. The cells were always of yeast shape, and no filaments were formed. In cultures with a biomass concentration above 6 g (dry weight) per liter, no cell aggregates were observed. In cultures with a lower biomass, the daughter cells failed to separate from the parent cells and formed aggregates with thickened walls. The average cell number per aggregate was found to be higher, and the average protoplast volume lower, under conditions of probable CO2 limitation. Simultaneously, the ratio of total dry weight to wet weight of protoplasts was considerably higher, indicating an increased share of wall or extracellular material. The possible effect of the observed morphological changes for maintaining a suitable concentration gradient of CO2 around the cell is discussed.
Antibiotic Resistances of Yogurt Starter Cultures
Streptococcus thermophilus
and
Lactobacillus bulgaricus
Authors: Sozzi Tommaso , Smiley Martin B.
Published: January 2020

Twenty-nine strains of
Lactobacillus bulgaricus
and 15 strains of
Streptococcus thermophilus
were tested for resistance to 35 antimicrobial agents by using commercially available sensitivity disks. Approximately 35% of the isolates had uncharacteristic resistance patterns.
Improved medium for selective isolation and enumeration of Bifidobacterium
Authors: Tanaka R , Mutai M
Published: January 2020

Petuely's selective medium for Bifidobacterium was improved by addition of riboflavin, nucleic acid bases, pyruvic acid, and nalidixic acid. The modified medium, when examined under strictly anaerobic conditions for efficient isolation of Bifidobacterium from human fecal samples, exhibited selective and high viable counts that were close to those found on the usual nonselective medium.
Capture of latex beads, bacteria, endotoxin, and viruses by charge-modified filters
Authors: Hou K , Gerba C P , Goyal S M , Zerda K S
Published: January 2020

This report demonstrates how electropositive filters can be used to enhance the removal of microorganisms and other negatively charged particles from water. It was shown that electropositive depth filters were capable of adsorbing viruses and endotoxins many times smaller than the average pore size of the filter. Electronegative filters of similar porosity or electropositive filters that had been treated to destroy the positive charge were almost ineffective under similar conditions for the removal of viruses and small latex spheres. The results of this study indicate that electropositive filters are highly effective in the removal of a wide range of contaminants over a wide range of pH values and ionic conditions.
Simple method for concentration of bacteria from large volumes of tap water
Authors: Goyal S M , Gerba C P
Published: January 2020

Membrane adsorption-elution techniques have made it possible to concentrate and detect small numbers of viruses in large volumes of water and wastewater, but no such methods are available for quantitative recovery of bacteria. A number of waterborne disease outbreaks of "unknown etiology" in the United States are suspected to have been caused by pathogens present in numbers too small to be detected by currently available methodology. The present study reports on the use of positively charged depth filters for the concentration and detection of bacteria in large volumes of tap water. In this method, dechlorinated tap water was passed, under positive pressure, through positively charged filter media (Zetaplus, 05S). More than 90% of seeded bacteria adsorbed to these filters at ambient pH levels. Adsorbed bacteria were eluted by passing a small volume of Trypticase soy broth in the direction opposite of the influent flow. By this method, Escherichia coli and Salmonella serovar B organisms in 20 liters of tap water were concentrated in a final volume of 50 ml, with an average recovery efficiency of greater than or equal to 30%.
Evidence for Cometabolism in Sewage
Authors: Jacobson Stuart N. , O'Mara Nancy L. , Alexander Martin
Published: January 2020

A procedure was developed to demonstrate cometabolism in models of natural ecosystems. The procedure involves showing the formation of metabolic products in high yield and the lack of incorporation of substrate carbon into cellular constituents. Samples of four
14
C-labeled herbicides (trifluralin, profluralin, fluchloralin, and nitrofen) were incubated with sewage aerobically and under discontinuous anaerobiosis for 88 days, and fresh sewage was added at intervals. Products were formed from each of the herbicides in nonsterile, but not in sterile, sewage. The yield of recovered products reached 87% for profluralin and more than 90% for fluchloralin and trifluralin, and the number of products ranged from 6 for nitrofen to 12 for fluchloralin. Concentrating the sewage microflora 40-fold greatly enhanced the rate of conversion. None of the radioactivity from the herbicide entered the nucleoside pool of the sewage microflora. The lack of incorporation of substrate carbon into cells and the almost stoichiometric conversion of the substrate to organic products indicate that members of the microbial community were cometabolizing the test compounds.
Thermal injury of Yersinia enterocolitica
Authors: Restaino L , Jeter W S , Hill W M
Published: January 2020

Procedures were developed to evaluate thermal injury to three strains of Yersinia enterocolitica (serotypes 0:3, 0:8, and 0:17). Serotype 0:17 (atypical strain) was more sensitive to bile salts no. 3 (BS) and to sublethal heat treatment than the typical strains, 0:3 and 0:8. When the 0:3, 0:8, and 0:17 serotypes were thermally stressed in 0.1 M PO4 buffer, pH 7.0, at 47 degrees C for 70, 60, and 12 min, respectively, greater than 99% of the total viable cell population was injured. Injury was determined by the ability of cells to form colonies on brain heart infusion (BHI) agar, but not on Trypticase soy agar (TSA) plus 0.6% BS for serotypes 0:3 and 0:8 and TSA plus 0.16% BS for 0:17. Heat injury of serotype 0:17 cells for 15 min in 0.1 M PO4 buffer caused an approximate 1,000-fold reduction in cell numbers on selective media as compared with cells heated in pork infusion (PI), BHI broth, and 10% nonfat dry milk (NFDM). The extended lag and resuscitation period in BHI broth was 2.5 times greater for 0:17 cells injured in 0.1 M PO4 than for cells injured in BHI or PI. The rate and extent of repair of Y. enterocolitica 0:17 cells in three recovery media were directly related to the heating menstruum used for injury. The use of metabolic inhibitors demonstrated that ribonucleic acid synthesis was required for repair, whereas deoxyribonucleic, cell wall, and protein synthesis were not necessary for recovery of 0:17 cells injured in 0.1 M PO4 buffer, BHI, or PI. Inhibition of respiration by 2,4-dinitrophenol slowed repair only for 0:17 cells injured in 0.1 M PO4 buffer, not for cells injured in PI or BHI.
Prophage-Cured Derivatives of
Streptococcus lactis
and
Streptococcus cremoris
Authors: Gasson Michael J. , Davies F. Lyndon
Published: January 2020

Prophage curing was achieved in
Streptococcus lactis
and
Streptococcus cremoris
, and the cured derivatives were shown to be indicators for their temperate bacteriophages. Relysogenization of these cured derivatives completed the first formal demonstration of the lysogenic state in lactic streptococci.
Comparison of Two Alcohol Dehydrogenases in the Fungus
Rhizopus javanicus
Authors: Yoneya Takefumi , Sato Yasushi
Published: January 2020

Two alcohol dehydrogenases with different catalytic properties were separated from
Rhizopus javanicus
, and some of their immunological and molecular properties were compared.
Analysis, Production, and Isolation of an Extracellular Laccase from
Polyporus anceps
Authors: Petroski Richard J. , Peczynska-Czoch Wanda , Rosazza John P.
Published: January 2020

Methods are described for the analysis, production, and isolation of laccase produced by a strain of
Polyporus anceps
. A simple quantitative colorimetric assay based on the oxidation of syringaldazine to syringaldazine quinone is described. Using a defined medium supplemented with the amino acids cysteine and histidine and with elevated phosphate, consistently high titers of laccase were obtained. The enzyme was isolated directly from fermentation medium by binding to diethylaminoethyl cellulose, and, once bound to the ion exchanger, it could be stored for 6 months at -70°C with minimal loss of activity. The enzyme was quantitatively recovered from the resin by elution with 0.2 M phosphate buffer (pH 5.0).
Effective ileal loop dose of Kanagawa-positive Vibrio parahaemolyticus
Authors: Twedt R M , Peeler J T , Spaulding P L
Published: January 2020

Groups of 16 rabbits per strain were injected with broth culture dilutions of three Kanagawa-positive Vibrio parahaemolyticus strains. The effective dose required to produce ileal loop dilatation in 50% of rabbits for pure cultures of strains 10136-76 and 553-72 from patients stools and NY 477 from incriminated food was 1.1 x 10(6), 2.6 x 10(5), and 7.7 x 10(6) organisms, respectively. When each of these cultures was admixed with greater than or equal to 10(9) Vibrio alginolyticus cells, the 50% effective dose was 1.2 x 10(6), 1.1 x 10(7), and 1.3 x 10(8) cells, respectively. Although concomitant injection of large numbers of competitive nonvirulent cells did not affect the 50% effective dose for strain 10136-76, that for the remaining two was increased 20- to 40-fold. The initiation of ileal loop response as estimated from sigmoidal plots of proportion of positive loops versus cell concentrations was given by as few as 10(2) cells of strain 553-72. Strains NY 477 and 10136-76 required approximately 10(5) cells. Half of the maximal response from these plots corresponded well with the 50% effective dose for the strains. These results suggest that pathogenicity of Kanagawa-positive V. parahaemolyticus strains may involve the participation of some virulence mechanisms in addition to the Kanagawa hemolysin.
Effect of fermentation conditions on toxin production by Clostridium botulinum type B
Authors: Siegel L S , Metzger J F
Published: January 2020

To obtain high yields of toxin for the preparation of purified neurotoxoids, we examined the time of appearance and the quantity of toxin produced by the Bean strain of Clostridium botulinum type B under various conditions by using a fermentor system. The medium employed consisted of 2.0% casein hydrolylsate and 1.5% yeast extract plus an appropriate concentration of glucose. The maximum toxin concentration (4 x 10(5) to 5 x 10(5) mouse median lethal doses per ml) was attained within 48 h under the following fermentation conditions: an initial glucose concentration of 0.5 or 1.0%, a temperature of 35 degrees C, a nitrogen overlay at a rate of 5 liters/min, and an agitation rate of 50 rpm.
Effect of phenolic antioxidants on the mutagenicity of aflatoxin B1
Authors: Shelef L A , Chin B
Published: January 2020

The Ames assay employing Salmonella typhimurium TA100 and TA98 was used to investigate potential interactions between aflatoxin B1 (AFB1) and the phenolic antioxidants butylated hydroxytoluene, butylated hydroxyanisole, and propyl gallate. AFB1 doses were within the linear response range, and the antioxidants were used at levels of 0 to 50 micrograms per plate. All three antioxidants were nonmutagenic in either bacterial tester strain, with or without the hepatic S-9 enzyme preparation; toxic effects were observed at doses higher than 20 micrograms per plate. Butylated hydroxytoluene and butylated hydroxyanisole substantially increased AFB1-induced mutagenesis in the two tester strains with microsomal activation. The addition of 5 to 20 micrograms of butylated hydroxytoluene or hydroxyanisole to 5 to 20 ng of AFB1 per plate caused more than a twofold increase in the number of His+ revertants. Addition of propyl gallate resulted in only a moderate increase in the number of revertants. Whereas several anticarcinogenic and antimutagenic effects by phenolic antioxidants have been reported, particularly in studies with polycyclic aromatic hydrocarbons, the enhancement of mutagenic potency of AFB1 by these compounds suggests a specificity with respect to the chemical nature of AFB1.
Incorporation of
32
P and Growth of Pseudomonad UP-2 on
n
-Tetracosane
Authors: Zilber I. Kirschner , Rosenberg E. , Gutnick D.
Published: January 2020

Cultures of the marine pseudomonad UP-2 growing on
n
-tetracosane contained both free cells and cells bound to the solid hydrocarbon. After separation by filtration through a Whatman no. 1 filter, the numbers of free and bound cells were estimated from the amount of
32
P incorporated into each fraction and the determined value of
32
P incorporation per viable cell in the filtrate (free cells). During the early exponential growth phase, over 80% of the cells were bound to large pieces of
n
-tetracosane; as the culture approached the stationary phase, the number of bound cells remained constant, whereas free cells continued to accumulate. Pulse-labeling experiments indicated that cells grew both on the surface of the solid and in the aqueous medium. During the growth cycle, a portion of the
n
-tetracosane which was initially nonfilterable was recovered in the filtrate in a form which was largely cell associated. This cell-associated
n
-tetracosane was preferentially utilized and could completely account for the observed growth of free cells.
Transformation Assay for Identification of Psychrotrophic Achromobacters
Authors: Juni Elliot , Heym Gloria A.
Published: January 2020

The finding that many psychrotrophic, gram-negative, nonmotile, oxidase-positive coccobacilli (achromobacters) are competent for genetic transformation made possible the development of a transformation assay that permits recognition of genetically related strains. It has been demonstrated that 109 independently isolated achromobacters are genetically related since deoxyribonucleic acid samples from all of these organisms were able to transform a single competent auxotrophic strain to prototrophy. Genetically interacting bacteria included strains that lacked one or more of the characteristics typical for most achromobacters. An oxidase-negative mutant of one of these strains reacted positively in the transformation assay, unlike other oxidase-negative bacteria. Achromobacters were derived from fish, poultry, irradiated foods, seawater, and other sources. One strain previously classified as
Micrococcus cryophilus
has been shown to be related to the achromobacters. Two achromobacters had an optimum growth temperature of 35°C and behaved as typical mesophiles. The moraxellae and
Acinetobacter
were shown to be unrelated to the achromobacters by using the transformation assay. The ready demonstration of genetic relatedness provides a new basis for taxonomic grouping of the psychrotrophic achromobacters.
Chlorine resistance of poliovirus isolants recovered from drinking water
Authors: Shaffer P T , Metcalf T G , Sproul O J
Published: January 2020

Poliovirus 1 isolants were recovered from finished drinking water produced by a modern, well-operated water treatment plant. These waters contained free chlorine residuals in excess of 1 mg/liter. The chlorine inactivation of purified high-titer preparations of two such isolants was compared with the inactivation behavior of two stock strains of poliovirus 1, LSc and Mahoney. The surviving fraction of virus derived from the two natural isolants was shown to be orders of magnitude greater than that of the standard strains. These results raise the question whether indirect drinking water standards based on free chlorine residuals are adequate public health measures, or whether direct standards based on virus determinations might be necessary.
Progression of Epiphytic Microflora in Wheat and Alfalfa Silages as Observed by Scanning Electron Microscopy
Authors: Moon Nancy J. , Henk W. G.
Published: January 2020

Wheat and alfalfa silages were examined by scanning electron microscopy and standard methods of microbial enumeration. Epiphytic microflora were present at levels of 10
6
to 10
8
/g in the fresh-cut plants. This flora was initially observed microscopically primarily on the surfaces. After 4 days of fermentation, lactic acid bacteria were observed on the surface in high concentrations near open stomata and throughout the interior mesophyll air sac spaces. At 4 days, populations on interior surfaces were restricted to the exterior surfaces of the air sacs. After 8 days the mesophyllic cells showed marked deterioration, and bacteria were observed on their inner surfaces. At 32 days, the end of the fermentation, vascular bundles and epidermal cells remained intact whereas stomata and mesophyllic cells were collapsed and often contained microorganisms. It is concluded that the interior of the leaves offers substantial nutritional and environmental advantages to epiphytic flora and is an important if not major deterioration site in fermented products. Since little deterioration of exterior surfaces was observed, these sites may play a minor role in supplying nutrients for microbial growth.
Relative potencies of four reference endotoxin standards as measured by the Limulus amoebocyte lysate and USP rabbit pyrogen tests
Authors: Weary M E , Donohue G , Pearson F C , Story K
Published: January 2020

Four commonly used reference endotoxin standards, Escherichia coli O113:H10:K0, E. coli O55:B5, Salmonella abortusequi, and Shigella dysenteriae were compared by the USP rabbit pyrogen and the Limulus amoebocyte lysate tests. By the rabbit pyrogen test, S. abortus equi was identified as the most potent endotoxin, followed closely by E. coli O113:H10:K0 and E. coli O55:B5.
Influence of inoculum size of Aspergillus parasiticus spores on aflatoxin production
Authors: Sharma A , Behere A G , Padwal-Desai S R , Nadkarni G B
Published: January 2020

The influence of the inoculum size on growth and aflatoxin production was examined in Aspergillus parasiticus (NRRL 3145) by using a synthetic medium. The reduction in the number of spores by 4 to 5 log cycles either by serial dilution or by gamma irradiation caused a two fold increase in the toxin production. The decrease in the inoculum size induced a lag in growth of the culture, though the final yield of the mycelium over the 28-day experimental period was the same. The maximal accumulation of aflatoxin was observed on day 14 of incubation. A transition from the biphasic to monophasic pattern in aflatoxin production could be correlated with the size of the inoculum. The enhanced toxin production from dilute inocula was similar to that obtained with the surviving fraction of the spores after gamma irradiation (0 to 150 krads).
Effects of pH shifts, bile salts, and glucose on sporulation of Clostridium perfringens NCTC 8798
Authors: Hickey C S , Johnson M G
Published: January 2020

The sporulation of Clostridium perfringens NCTC 8798 was studied after exposing vegetative cells to: pH values of 1.5 to 8.0 in fluid thioglycolate broth (for 2h) and then transferring them to Duncan-Strong (DS) sporulation medium; sodium cholate or sodium deoxycholate (0.3 to 6.5 mM) in DS medium; or Rhia-Solberg medium with 0.4% (wt/wt) starch, glucose, or both added at 0 to 55 mM. At pH 1.5, no culturable heat-resistant spores were formed. For cells exposed to pH 3.0, 4.0, 5.0, or 6.0, increases in heat-resistant spores were not seen until after a lag of 12 to 13 h, whereas the lag was only 2 to 3 h for cells exposed to pH 7.0 or 8.0. Maximal spore crops were produced after only 6 to 8 h for cells exposed to pH 7 or 8, but 16 to 18 h was required for production of maximal spore crops by cells exposed to the lower-pH media. The addition of sodium cholate (3.5 to 6.5 mM) to DS medium only slightly reduced the culturable heat-resistant spore count from 1.9 X 10(7) to 3 X 10(6)/ml. The addition of 1.8 mM or more sodium deoxycholate reduced the culturable heat-resistant spore count to less than 10/ ml. When either starch or glucose alone was added to Rhia-Solberg medium there was no production of culturable heat-resistant spores, but a combination of 0.4% (wt/wt) starch and 4.4 mM glucose yielded 6 X 10(5) spores/ml. The spore production remained at this level for glucose concentrations of 6 to 22 mM, but then declined to about 3 X 10(3) spores per ml at higher concentrations.
Failure of the most-probable-number technique to detect coliforms in drinking water and raw water supplies
Authors: Evans T M , Waarvick C E , Seidler R J , LeChevallier M W
Published: January 2020

A procedure was developed to detect false-negative reactions (interference) in the standard most-probable-number (S-MPN) technique for coliform enumeration of untreated surface water and potable water supplies. This modified MPN (M-MPN) procedure allowed a quantitative assessment of the interference with coliform detection in untreated surface water and potable water supplies. Coliform interference was found to occur in the presumptive, confirmed, and completed tests of the S-MPN technique. When coliforms were present, interference with their detection occurred in over 80% of the samples. The inferior nature of the S-MPN was revealed by the 100% increase in the incidence of completed coliform-positive drinking water samples obtained with the M-MPN technique. The M-MPN procedure was also superior to the standard membrane filter technique. Eight different species of coliforms were recovered from false-negative tests, including Citrobacter, Enterobacter, Klebsiella, and Escherichia coli (in decreasing order of occurrence). The use of standard MPN techniques for monitoring potable water supplies may lead to a false security that the drinking water supply is potable, i.e., free from indicator bacteria.
Formation of Short-Chain Fatty Acids from H
2
and CO
2
by a Mixed Culture of Bacteria
Authors: Goldberg I. , Cooney C. L.
Published: January 2020

The biological utilization of CO
2
and H
2
for the formation of short-chain fatty acids was studied by using a mixed culture of bacteria. Optimization of a medium was carried out in continuous culture to identify limiting factors which controlled growth and production of organic acids. The optimal pH for growth and acid production was 7.0 at 37°C; the maximal cell concentration obtained was 5.9 g of cells per liter (dry weight), and the maximal amount of volatile acids formed was 4.7 g/liter, with acetic acid as the predominant acid. With the optimized medium, it was found that the rate of transfer of hydrogen or carbon dioxide, or both, from gas to liquid was the limiting factor which controlled growth and production of acids.
Formaldehyde degradation by catalytic oxidation
Authors: Shirey W N , Hall T A , Hanel E , Sansone E B
Published: January 2020

Formaldehyde used for the disinfection of a laminar-flow biological safety cabinet was oxidatively degraded by using a catalyst. This technique reduced the formaldehyde concentration in the cabinet from about 5,000 to about 45 mg/m3 in 8 h. This technique should prove useful in other applications.