bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors Involved in Hydrolysis of Microcrystalline Cellulose by
Acetivibrio cellulolyticus
Authors: MacKenzie C. Roger , Patel Girishchandra B. , Bilous Doris
Published: January 2020

Acetivibrio cellulolyticus
cellulase obtained by the water elution of residual cellulose from the growth medium was compared with the cellulase activity present in culture supernatants. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis indicated that water elution released most of the protein bands which adhered to undigested cellulose from the culture medium. The enzyme in the culture supernatant and that eluted from residual cellulose had specific activities for Avicel hydrolysis that were 20- to 40-fold greater than that of
Trichoderma reesei
cellulase. However, Ca
2+
and a reducing agent such as dithiothreitol were required for maximum Avicel hydrolysis rates by these
A. cellulolyticus
enzyme preparations. The effect of these agents on
p
-nitrophenyl lactopyranoside hydrolysis suggested that they were required by an exoglucanase component. Supernatant enzyme preparations contained large amounts of carbohydrate which was separated from most of the cellulase protein by phenyl-Sepharose chromatography. Removal of this carbohydrate, which interfered with protein fractionations, allowed for an activity stain analysis of the supernatant enzyme.
Mitochondrial DNA in Candida pintolopesii, a yeast indigenous to the surface of the secreting epithelium of the murine stomach
Authors: McCarthy D M , Jenq W , Savage D C
Published: January 2020

Candida pintolopesii 108-1 is an indigenous yeast which colonizes the surface of the secreting gastric mucosa of mice. We have been exploring the aerobic respiratory capacities of this organism in reference to its capacity to colonize the stomach surface, an environment that could contain little oxygen for microbial growth. In this paper, we report mitochondrial DNA and membranes in cells of a strain of this yeast isolated from the gastric epithelium of a mouse and compare the findings with those made by other investigators in studies of Saccharomyces cerevisiae. Putative mitochondrial DNA was isolated from crude lysates of C. pintolopesii and S. cerevisiae as fluorescing bands in CsCl gradients containing 4',6-diamidino-2-phenylindole. The DNA from C. pintolopesii hybridized with a 32P-labeled DNA probe for the 21S rRNA gene encoded by mitochondrial DNA in S. cerevisiae. Postvital cell staining with 4',6-diamidino-2-phenylindole and rhodamine 123 revealed mitochondrial DNA and membranes, respectively, in the cytoplasm of intact C. pintolopesii cells. The staining patterns were generally similar to those reported for S. cerevisiae. Finally, structures similar to those reported to be mitochondria in electron micrographs of S. cerevisiae were seen in preparations of C. pintolopesii cells examined by transmission electron microscopy. These data confirm findings from studies of its respiratory capacity published earlier that a strain of C. pintolopesii isolated directly from its native habitat has functional mitochondria.
Thermal inactivation and injury of Bacillus stearothermophilus spores
Authors: Feeherry F E , Munsey D T , Rowley D B
Published: January 2020

Aqueous spore suspensions of Bacillus stearothermophilus ATCC 12980 were heated at different temperatures for various time intervals in a resistometer, spread plated on antibiotic assay medium supplemented with 0.1% soluble starch without (AAMS) or with (AAMS-S) 0.9% NaCl, and incubated at 55 degrees C unless otherwise indicated. Uninjured spores formed colonies on AAMS and AAMS-S; injured spores formed colonies only on AAMS. Values of D, the decimal reduction time (time required at a given temperature for destruction of 90% of the cells), when survivors were recovered on AAMS were 62.04, 18.00, 8.00, 3.33, and 1.05 min at 112.8, 115.6, 118.3, 121.1, and 123.9 degrees C, respectively. Recovery on AAMS-S resulted in reduced decimal reduction time. The computed z value (the temperature change which will alter the D value by a factor of 10) for spores recovered on AAMS was 8.3 degrees C; for spores recovered on AAMS-S, it was 7.6 degrees C. The rates of inactivation and injury were similar. Injury (judged by salt sensitivity) was a linear function of the heating temperature. At a heating temperature of less than or equal to 118.3 degrees C, spore injury was indicated by the curvilinear portion of the survival curve (judged by salt sensitivity), showing that injury occurred early in the thermal treatment as well as during logarithmic inactivation (reduced decimal reduction time). Heat-injured spores showed an increased sensitivity not only to 0.9% NaCl but also to other postprocessing environmental factors such as incubation temperatures, a pH of 6.6 for the medium, and anaerobiosis during incubation.
Susceptibility of Campylobacter jejuni and Yersinia enterocolitica to UV radiation
Authors: Butler R C , Lund V , Carlson D A
Published: January 2020

Two enteric pathogens, Campylobacter jejuni and Yersinia enterocolitica serogroup O:3, together with Escherichia coli, were investigated for susceptibility to UV radiation at 254 nm. The UV dose required for a 3-log reduction (99.9% inactivation) of C. jejuni, Y. enterocolitica, and E. coli was 1.8, 2.7, and 5.0 mWs/cm2, respectively. Using E. coli as the basis for comparison, it appears that C. jejuni and Y. enterocolitica serogroup O:3 are more sensitive to UV than many of the pathogens associated with waterborne disease outbreaks and can be easily inactivated in most commercially available UV reactors. No association was found between the sensitivity of Y. enterocolitica to UV and the presence of a 40- to 50-megadalton virulence plasmid.
Inhibition of Methanogenesis from Acetate in Granular Sludge by Long-Chain Fatty Acids
Authors: Koster Iman W. , Cramer Albertus
Published: January 2020

The effect of four saturated long-chain fatty acids (caprylic, capric, lauric, and myristic) and one unsaturated long-chain fatty acid (oleic) on the microbial formation of methane from acetate was investigated in batch anaerobic toxicity assays. The tests were carried out with granular sludge from an upflow anaerobic sludge bed reactor. In this sludge,
Methanothrix
spp. are the predominant acetoclastic methanogens. Lauric acid appeared to be the most versatile inhibitor: inhibition started at 1.6 mM, and at 4.3 mM the maximum specific acetoclastic methanogenic activity had been reduced to 50%. Caprylic acid appeared to be only slightly inhibitory. Oleic acid was almost as inhibitory as lauric acid. Although adsorption of the inhibitor on the cell wall might play an important role in the mechanism of inhibition, the inhibition was found to be correlated with concentration rather than with the amount per unit of biomass. In practical situations, as in anaerobic waste treatment processes, synergism can be expected to enhance the inhibition of methanogenesis. In the present research a background concentration of lauric acid below its MIC strongly enhanced the toxicity of capric acid and (to an even greater extent) myristic acid.
Reconstitution of emulsifying activity of Acinetobacter calcoaceticus BD4 emulsan by using pure polysaccharide and protein
Authors: Kaplan N , Zosim Z , Rosenberg E
Published: January 2020

Acinetobacter calcoaceticus BD4 and BD413 produce extracellular emulsifying agents when grown on 2% ethanol medium. For emulsifying activity, both polysaccharide and protein fractions were required, as demonstrated by selective digestion of the polysaccharide with a specific bacteriophage-borne polysaccharide depolymerase, deproteinization of the extracellular emulsifying complex with hot phenol, and reconstitution of emulsifier activity with pure polysaccharide and a polysaccharide-free protein fraction. Chemical modification of the carboxyl groups in the polysaccharide resulted in a loss of activity. The protein required for reconstitution of emulsifying activity was purified sevenfold. The BD4 emulsan apparently derives its amphipathic properties from the association of an anionic hydrophilic polysaccharide with proteins.
Comparative assessment of chlorine, heat, ozone, and UV light for killing Legionella pneumophila within a model plumbing system
Authors: Muraca P , Stout J E , Yu V L
Published: January 2020

Nosocomial Legionnaires disease can be acquired by exposure to the organism from the hospital water distribution system. As a result, many hospitals have instituted eradication procedures, including hypercholorination and thermal eradication. We compared the efficacy of ozonation, UV light, hyperchlorination, and heat eradication using a model plumbing system constructed of copper piping, brass spigots, Plexiglas reservoir, electric hot water tank, and a pump. Legionella pneumophila was added to the system at 10(7) CFU/ml. Each method was tested under three conditions; (i) nonturbid water at 25 degrees C, (ii) turbid water at 25 degrees C, and (iii) nonturbid water at 43 degrees C. UV light and heat killed L. pneumophila most rapidly and required minimal maintenance. Both UV light and heat (60 degrees C) produced a 5 log kill in less than 1 h. In contrast, both chlorine and ozone required 5 h of exposure to produce a 5 log decrease. Neither turbidity nor the higher temperature of 43 degrees C impaired the efficacy of any of the disinfectant methods. Surprisingly, higher temperature enhanced the disinfecting efficacy of chlorine. However, higher temperature accelerated the decomposition of the chlorine residual such that an additional 120% volume of chlorine was required. All four methods proved efficacious in eradicating L. pneumophila from a model plumbing system.
Characterization of a Copper Resistance Plasmid Conserved in Copper-Resistant Strains of
Pseudomonas syringae
pv.
tomato
Authors: Cooksey Donald A.
Published: January 2020

A 35-kilobase plasmid was conserved among 12 copper-resistant strains of
Pseudomonas syringae
pv.
tomato.
Restriction patterns of this plasmid from each strain were identical, and a cloned copper resistance gene from 1 strain hybridized to the same location on the 35-kilobase plasmid of all 12 strains.
Preparation of scirpentriol and triacetoxyscirpenol in good yield from cultures of Fusarium sambucinum NRRL 13495
Authors: Richardson K E , Hamilton P B
Published: January 2020

Crude extracts of filtrates of cultures of Fusarium sambucinum NRRL 13495 were acetylated or hydrolyzed. After chromatography on cartridge columns of silica gel and recrystallization three times from mixtures of ethyl acetate and hexane, 3,4,15-triacetoxyscirpenol (435 +/- 10 mg/liter of filtrate; mean +/- standard error [n = 3]) and the parent alcohol scirpentriol were isolated (261 +/- 29 mg/liter of filtrate; mean +/- standard error [n = 3]) in 68 and 53% yield for a 130- and 14-fold improvement, respectively, over prior reports.
Preparation of 4,15-diacetoxyscirpenol from cultures of Fusarium sambucinum NRRL 13495
Authors: Richardson K E , Hamilton P B
Published: January 2020

Filtrates of Fusarium sambucinum NRRL 13495 grown in a stagnant culture for 9 days contained up to 458 +/- 60 (mean +/- standard error; n = 3) mg of 4,15-diacetoxyscirpenol per liter depending on culture conditions. Extraction with ethyl acetate, chromatography on a column of silica gel, and crystallization from mixtures of ethyl acetate and hexane provided pure material in 96% yield.
Lysis of
Bacillus subtilis
Cells by Glycerol and Sucrose Esters of Fatty Acids
Authors: Tsuchido Tetsuaki , Ahn Yung-Hoon , Takano Mitsuo
Published: January 2020

The lytic action of glycerol and sucrose esters of fatty acids with different carbon chain lengths on the exponentially growing cells of
Bacillus subtilis
168 was investigated. Of each series of esters, glycerol dodecanoate and sucrose hexadecanoate were the most active. Lysis at 1 h after the addition of 0.1 mM glycerol dodecanoate or 20 μg of sucrose hexadecanoate per ml was 81 or 79%, respectively, as evaluated by the reduction in optical density. During this treatment a great loss of viability occurred that preceded lysis. The results that were obtained suggest that autolysis is induced by these esters. The esters caused morphological changes in the cells, but a seeming adaptation of the cells to esters was seen.
Seasonal occurrence of Campylobacter spp. in surface waters and their correlation with standard indicator bacteria
Authors: Carter A M , Pacha R E , Clark G W , Williams E A
Published: January 2020

Campylobacter jejuni, Campylobacter coli, and a Campylobacter-like organism were isolated from a number of natural water sources in central Washington, including ponds, lakes, and small mountain streams at elevations ranging from 1,460 to 5,400 feet (ca. 445 to 1,646 m) above sea level. At the two sites where extensive sampling was done, the bacteria were recovered throughout the year. Generally, the recovery rates were highest in the fall and winter months and lowest during the spring and summer months. Campylobacter density did not show significant correlation with microbiological (plate counts of fecal and total coliforms, fecal streptococci, and heterotrophic bacteria) or physical (water temperature, pH, and conductivity) parameters.
Properties of the Glucose Transport System in Some Deep-Sea Bacteria
Authors: DeLong Edward F. , Yayanos A. Aristides
Published: January 2020

Many deep-sea bacteria are specifically adapted to flourish under the high hydrostatic pressures which exist in their natural environment. For better understanding of the physiology and biochemistry of these microorganisms, properties of the glucose transport systems in two barophilic isolates (PE-36, CNPT-3) and one psychrophilic marine bacterium (
Vibrio marinus
MP1) were studied. These bacteria use a phosphoenol-pyruvate:sugar phosphotransferase system (PTS) for glucose transport, similar to that found in many members of the
Vibrionaceae
and
Enterobacteriaceae
. The system was highly specific for glucose and its nonmetabolizable analog, methyl alpha-glucoside (a-MG), and exhibited little affinity for other sugars tested. The temperature optimum for glucose phosphorylation in vitro was approximately 20�C. Membrane-bound PTS components of deep-sea bacteria were capable of enzymatically cross-reacting with the soluble PTS enzymes of
Salmonella typhimurium
, indicating functional similarities between the PTS systems of these organisms. In CNPT-3 and
V. marinus
, increased pressure had an inhibitory effect on a-MG uptake, to the greatest extent in
V. marinus
. Relative to atmospheric pressure, increased pressure stimulated sugar uptake in the barophilic isolate PE-36 considerably. Increased hydrostatic pressure inhibited in vitro phosphoenolpyruvate-dependent a-MG phosphorylation catalyzed by crude extracts of
V. marinus
and PE-36 but enhanced this activity in crude extracts of the barophile CNPT-3. Both of the pressure-adapted barophilic bacteria were capable of a-MG uptake at higher pressures than was the nonbarophilic psychrophile,
V. marinus
.
Inactivation of clostridial ferredoxin and pyruvate-ferredoxin oxidoreductase by sodium nitrite
Authors: Carpenter C E , Reddy D S , Cornforth D P
Published: January 2020

Clostridial ferredoxin and pyruvate-ferredoxin oxidoreductase activity was investigated after in vitro or in vivo treatment with sodium nitrite. In vitro treatment of commercially available Clostridium pasteurianum ferredoxin with sodium nitrite inhibited ferredoxin activity. Inhibition of ferredoxin activity increased with increasing levels of sodium nitrite. Ferredoxin was isolated from normal C. pasteurianum and Clostridium botulinum cultures and from cultures incubated with 1,000 micrograms of sodium nitrite per ml for 45 min. The activity of in vivo nitrite-treated ferredoxin was decreased compared with that of control ferredoxin. Pyruvate-ferredoxin oxidoreductase isolated from C. botulinum cultures incubated with 1,000 micrograms of sodium nitrite per ml showed less activity than did control oxidoreductase. It is concluded that the antibotulinal activity of nitrite is due at least in part to inactivation of ferredoxin and pyruvate-ferredoxin oxidoreductase.
Degradation of n-haloalkanes and alpha, omega-dihaloalkanes by wild-type and mutants of Acinetobacter sp. strain GJ70
Authors: Janssen D B , Jager D , Witholt B
Published: January 2020

A 1,6-dichlorohexane-degrading strain of Acinetobacter sp. was isolated from activated sludge. The organism could grow with and quantitatively release halide from 1,6-dichlorohexane, 1,9-dichlorononane, 1-chloropentane, 1-chlorobutane, 1-bromopentane, ethylbromide, and 1-iodopropane. Crude extracts contained an inducible novel dehalogenase that liberated halide from the above compounds and also from 1,3-dichloropropane, 1,2-dibromoethane, and 2-bromoethanol. The latter two compounds were toxic suicide substrates for the organism at concentrations of 10 and 5 microM, respectively. Mutants resistant to 1,2-dibromoethane (3 mM) lacked dehalogenase activity and did not utilize haloalkanes for growth. Mutants resistant to both 1,2-dibromoethane (3 mM) and 2-bromoethanol (30 mM) could no longer oxidize or utilize alcohols and were capable of hydrolytic dehalogenation of 1,2-dibromoethane to ethylene glycol.
Susceptibility of Torulopsis glabrata in the presence of six antifungal agents determined by comparison of growth at several pHs
Authors: Darbord J C , Vincent F , Boutron L , Goury V , Guyomard S
Published: January 2020

We describe a method using an automated system whereby fungistatic activities can be determined in several conditions. The process was adapted to Torulopsis glabrata, and it showed that benzalkonium chloride, chlorhexidine gluconate, and thimerosal preserve fungistatic activities in acidic medium, whereas acidification reduces the activity of povidone iodine and poloxamer.
Influence of the
Bradyrhizobium japonicum
Hydrogenase on the Growth of
Glycine
and
Vigna
Species
Authors: Drevon J. J. , Kalia V. C. , Heckmann M. O. , Salsac L.
Published: January 2020

The effect of the
Bradyrhizobium japonicum
hydrogenase on nitrogen fixation was evaluated by comparing the growth of
Vigna
and
Glycine
species inoculated with a Hup mutant and its Hup
+
revertant. In all experiments, the growth of plants inoculated with the strain without hydrogenase was at least equal to the growth of the strain with hydrogenase. For
Glycine usuriensis
and
Glycine max cv
. Hodgson in liquid culture, the growth was higher with the Hup
−
strain. It is possible that reduced rates of nitrogen fixation in the presence of hydrogenase are due to O
2
depletion caused by the hydrogen oxidizing, since the oxygen pressure in the air appears to be a limiting factor of symbiotic nitrogen fixation in the soybean.
Effects of several mycotoxins on specific growth rate of Butyrivibrio fibrisolvens and toxin degradation in vitro
Authors: Westlake K , Mackie R I , Dutton M F
Published: January 2020

Four strains of Butyrivibrio fibrisolvens did not degrade aflatoxin B1. Acetyl T-2 toxin, T-2 toxin, HT-2 toxin, deoxynivalenol, diacetoxyscirpenol, verrucarin A, zearalenone, and ochratoxin A did not affect the specific growth rate of B. fibrisolvens CE51 significantly, but all were degraded to greater or lesser extents. Breakdown products were produced as a result of deacetylation reactions.
Characterization of virucidal agents in activated sludge
Authors: Knowlton D R , Ward R L
Published: January 2020

A comprehensive study was carried out to determine the properties of agents responsible for loss of virus infectivity in mixed-liquor suspended solids (MLSS) of activated sludge. Initial experiments revealed that model enteric viruses (poliovirus-1 and rotavirus SA-11) were irreversibly inactivated in MLSS and released their RNA genomes. Enteric viruses belonging to other genera (echovirus-12, coxsackievirus A13, reovirus-3) were also shown to lose infectivity in MLSS. Although the virucidal activity decreased at reduced temperatures, MLSS still retained significant activity at 4 degrees C. The virucidal agents in MLSS were stable for months at 4 degrees C, but their activity decreased approximately 50% during 4 days of aeration at 26 degrees C. Primary effluent, the nutrient source for activated sludge, also contained virucidal activity. After centrifugation of MLSS, almost all virucidal activity was found in the particulate fraction because of inhibitory substances retained in the supernatant fraction. Decreasing or increasing the solids concentration of the particulate fraction did not increase the virucidal activity of the fraction. The effects of heat and antibiotics on the virucidal activity of MLSS, coupled with the finding that the activity can be produced in autoclaved primary effluent seeded with MLSS, strongly support the conclusion that microorganisms are responsible for this activity. Attempts to characterize the virucidal microbial components of MLSS indicated that treatments that resulted in the inactivation or removal of microorganisms also caused a loss of virucidal activity. Thus, it appears that the virucidal components of microorganisms are either short-lived or active only while bound to the organisms themselves.
Microplate Assay for
Colletotrichum
Spore Production
Authors: Slade S. J. , Harris R. F. , Smith C. S. , Andrews J. H. , Nordheim E. V.
Published: January 2020

A simple microplate method was devised to assay spore production by
Colletotrichum gloeosporioides
by growing the fungus on 1 ml of solid media in the wells of tissue culture plates. Growth and sporulation on microplates were compared at days 4 and 8 with growth and sporulation in 100-ml liquid batch cultures that involved 11 common media. Spore production per unit volume of medium was the same for solid and liquid forms of the media. Qualitative assessment of mycelial growth measured on microplates agreed with that of growth measured in liquid cultures. The microplate assay indicated that V8 juice was the best medium and that an organic content of about 6 mg/ml was optimal for high sporulation and low mycelium production. The assay provides a convenient, rapid, and inexpensive means of screening media for the production of fungal conidia in large numbers, to be used, for example, in biological control programs.
Isolation and Some Properties of a β-
d
-Xylosidase from
Clostridium acetobutylicum
ATCC 824
Authors: Lee Song F. , Forsberg Cecil W.
Published: January 2020

A β-
d
-xylosidase from
C. acetobutylicum
ATCC 824 was purified by column chromatography on CM-Sepharose, hydroxylapatite, Phenyl Sepharose, and Sephadex G-200. The enzyme had an apparent molecular weight of 224,000 as estimated by gel filtration. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the enzyme consisted of two subunits of 85,000 and one subunit of 63,000 daltons. It exhibited optimal activity at pH 6.0 to 6.5 and 45°C. the enzyme had an isoelectric point of 5.85. It hydrolyzed
p
-nitrophenylxyloside readily with a

K
m

of 3.7 mM. The enzyme hydrolyzed xylo-oligosaccharides with chain lengths of 2 to 6 units by cleaving a single xylose from the chain end. It showed little or no activity against xylan, carboxymethyl cellulose, and other
p
-nitrophenylglycosides.
Mobilization of plasmid pHSV106 from Escherichia coli HB101 in a laboratory-scale waste treatment facility
Authors: Mancini P , Fertels S , Nave D , Gealt M A
Published: January 2020

The mobilization of plasmid pHSV106 from Escherichia coli HB101, in a laboratory model waste treatment facility, by both laboratory and indigenous wastewater strains of E. coli was monitored by transfer of antibiotic resistance characteristics and by detection of pHSV106 DNA sequences in recipient cells. The mobilization was demonstrated to occur under several different treatment conditions, such as different media composition, microbial concentrations, and waste flow rates. The herpes simplex virus thymidine kinase gene was used as a hybridization marker to confirm the occurrence of the transfer. The use of the HB101 (recA mutant) host cell implies that recA functions are unnecessary for the gene transfer.
An evaluation of the sporicidal activity of ozone
Authors: Rickloff J R
Published: January 2020

This study was undertaken to determine the feasibility of sterilizing surfaces with ozone-saturated water by the methods of the Association of Official Analytical Chemists (AOAC). Initially, it was determined that there was no apparent difference in ozone resistance between spores of Bacillus subtilis and Clostridium sporogenes when they are suspended in water. Both species were inactivated by a 10-min exposure at ambient temperature. Resistance was increased when the spores were dried on AOAC carriers. Viable organisms were recovered after an exposure of 40 min at ambient temperature. An increase in the reactor water temperature to 60 degrees C did not improve the effectiveness of the ozone in sterilizing AOAC carriers. Dried spores of C. sporogenes were more resistant than B. subtilis spores because of a greater accumulation of organic matter on the carriers. No significant sporicidal activity was demonstrated after 40 min for spores of either species when they were inoculated on silk suture loops. The data suggest that organic loading and poor ozone penetrability are key factors in effecting the ability of ozone to sterilize surfaces rapidly.
Detection of Cryptosporidium in water by using polypropylene cartridge filters
Authors: Musial C E , Arrowood M J , Sterling C R , Gerba C P
Published: January 2020

Members of the genus Cryptosporidium are protozoan parasites that cause gastroenteritis in humans and animals and appear to be spread largely by the fecal-oral route. A method was developed for the concentration and detection of Cryptosporidium oocysts in water to assess their occurrence in the environment and potential for waterborne disease transmission. This method was developed by using spun polypropylene cartridge filters. Optimal conditions for concentration, filter elution, filter porosity, and detection were determined. Fluoresceinated monoclonal antibodies were used for oocyst detection. Experiments also were conducted to study the effect of flow rate, low oocyst numbers, and the addition of detergents on recovery and retention of oocysts. The method that was developed was sensitive enough to detect oocysts at levels of less than 1 per liter. Using this method, we isolated Cryptosporidium oocysts from secondarily treated sewage.
Influence of immobilization on the stability of pTG201 recombinant plasmid in some strains of Escherichia coli
Authors: Nasri M , Sayadi S , Barbotin J N , Dhulster P , Thomas D
Published: January 2020

The stability of pTG201 plasmid was examined by continuous culture in three genetically different Escherichia coli hosts. Two types of experiment were carried out, one with free cells and one with immobilized cells. When cells were cultivated in free continuous culture in the absence of antibiotic selection, the plasmid was maintained with various degrees of stability in the three host organisms. By contrast, in continuous culture with immobilized cells, plasmid pTG201 was stably maintained in the three strains. We showed that the increase in pTG201 stability in immobilized cells is due neither to plasmid transfer between immobilized cells nor to an increase of the plasmid copy number of immobilized cells. We also showed that plasmid-free cells, when coimmobilized and grown in competition with plasmid-containing cells, cannot overrun the culture.
Membrane H
+
Conductance of
Clostridium thermoaceticum
and
Clostridium acetobutylicum
: Evidence for Electrogenic Na
+
/H
+
Antiport in
Clostridium thermoaceticum
Authors: Terracciano Joseph S. , Schreurs Wilhelmus J. A. , Kashket Eva R.
Published: January 2020

H
+
conductance in de-energized cells of
Clostridium thermoaceticum
and
Clostridium acetobutylicum
was determined from the rate of realkalinization of the medium after an acid pulse. In both organisms, cell membrane proton permeability was increased by fermentation end products and ionophores. In
C. thermoaceticum,
H
+
conductance was increased by Na
+
ions compared with K
+
as counterions. In these cells, addition of Na
+
, but not K
+
, elicited efflux of H
+
; H
+
efflux was stimulated by SCN
−
and decreased by various ionophores. We concluded that
C. thermoaceticum
possesses an electrogenic Na
+
/H
+
antiporter. In contrast,
C. acetobutylicum
cells did not have an electrogenic Na
+
/H
+
antiporter.
Isolation of Cellulolytic Anaerobic Extreme Thermophiles from New Zealand Thermal Sites
Authors: Sissons Christopher H. , Sharrock Keith R. , Daniel Roy M. , Morgan Hugh W.
Published: January 2020

Avicel enrichment cultures from 47 thermal-pool sites in the New Zealand Rotorua-Taupo region were screened for growth and carboxymethyl cellulase activity at 75°C. Eight anaerobic cellulolytic cultures were obtained. The effect of temperature on carboxymethyl cellulase activity was measured, and bacteria were isolated from the five best cultures. Bacteria from two sources designated TP8 and TP10 grew at 75°C, accumulated reducing sugar in the growth medium and gave free cellulases with avicelase activity. Bacteria from sources designated Tok4, Tok8, and Wai21 grew at 75°C, accumulated no free sugars in the medium, and gave free carboxymethyl cellulases with virtually no avicelase activity. All were obligate anaerobic nonsporeforming rods which stained gram negative, grew on pentoses as well as hexoses, and gave ethanol and acetate as major fermentation end products. The isolated strain which produced the most active and stable cellulases (trivially designated TP8.T) had lower rates of free endocellulase accumulation at 75°C than did
Clostridium thermocellum
at 60°C, but its cellulase activity against avicel and filter paper in culture supernatants was comparable. Tested at 85°C, TP8.T carboxymethyl cellulases included components which were very stable, whereas
C. thermocellum
carboxymethyl cellulases were all rapidly inactivated. The TP8.T avicelase activity was relatively unaffected by Triton X-100, EDTA, and dithiothreitol. Evidence was obtained for the existence of unisolated, cellulolytic extreme thermophiles producing cellulases which were more stable and active than those from TP8.T.
Distribution of Iron-Oxidizing Bacteria in the Nordic Uranium Tailings Deposit, Elliot Lake, Ontario, Canada
Authors: Silver M.
Published: January 2020

Iron-oxidizing bacteria are present within the top 2 m (but not always at the surface) and near the water table-capillary fringe of the vegetated Nordic uranium deposit, Elliot Lake, Ontario, Canada. They are distributed uniformly in the top 0.5 m of unvegetated tailings. The locations of these bacteria correlate with zones of pyrite oxidation as delineated in previous studies by the formation of soluble iron and sulfate. Heterotrophic bacteria are also present in the tailings, with greatest concentrations at the surface and near the water table-capillary fringe. Sulfate-reducing bacteria were detected in the soil and peat at the base of the tailings. The results of this study suggest that the establishment of vegetation directly upon the tailings surface does not arrest bacterial pyrite oxidation.
Cell Wall-Associated Proteases of
Streptococcus cremoris
Wg2
Authors: Hugenholtz Jeroen , van Sinderen Douwe , Kok Jan , Konings Wil N.
Published: January 2020

Two components of the proteolytic system, proteins A and B (J. Hugenholtz, F. Exterkate, and W. N. Konings, Appl. Environ. Microbiol. 48:1105-1110, 1984), have been studied in
Streptococcus cremoris
Wg2 by immunological methods. The components could not be separated by standard chromatography techniques because both proteins had almost identical molecular weights (about 140,000) and isoelectric points (pH 4.5). Specific antibodies were raised against proteins A and B by excision of the different immunoprecipitates from crossed immunoelectrophoresis gels. With these antibodies, protein A or B was removed from solutions containing both proteins. The purified proteins A and B possessed proteolytic activity and were inhibited by the serine protease inhibitor phenylmethylsulfonyl fluoride. Each of these proteins accounted for approximately 50% of the total proteolytic activity isolated from
S. cremoris
Wg2. The specific antibodies against the proteases were also used for immuno-gold labeling studies. The proteases were clearly seen to be located at the outside of the cell wall. The proteases had the same location when the genetic information coding for the proteases was cloned in
Streptococcus lactis
and
Bacillus subtilis
.
Change in Size of
Chromatium minus
Cells in Relation to Growth Rate, Sulfur Content, and Photosynthetic Activity: A Comparison of Pure Cultures and Field Populations
Authors: Montesinos Emilio
Published: January 2020

The size frequency distribution of planktonic cells of purple sulfur phototrophic bacteria was measured at several depths in a bacterial layer of Lake Cisó (Spain). The bacterioplankton was dominated by
Chromatium minus
(87 to 94% of the total biomass). The largest cells of
C. minus
were found in the top part of the bacterial layer. In addition, the in situ and potential specific photosynthetic activity (CO
2
fixation and acetate uptake) and specific pigment content were measured in relation to several key environmental parameters that determine the activity of cells. Potential growth rates were estimated from production rates and biomass. A maximal specific growth rate of 0.074 h
−1
was found for the top part of the bacterial layer. Photosynthesis versus light and versus sulfide curves among field samples indicated that light was the main limiting factor controlling the activity of
C. minus
in Lake Cisó. The specific bacteriochlorophyll
a
content was very high in all samples (0.27 to 0.36 μg μg of C
−1
). Results of laboratory experiments performed with pure cultures indicated that the average cell volume changes from 5.9 to 20.0 μm
3
and that differences in growth rate, breakdown, or synthesis of sulfur and glycogen and degradation of the photosynthetic apparatus are the main factors accounting for the observed changes in cell volume across the bacterial layer.
Prevalence of Borrelia burgdorferi and Babesia microti in mice on islands inhabited by white-tailed deer
Authors: Anderson J F , Johnson R C , Magnarelli L A , Hyde F W , Myers J E
Published: January 2020

Borrelia burgdorferi and Babesia microti were isolated from 35 of 51 white-footed mice (Peromyscus leucopus) and meadow voles (Microtus pennsylvanicus) captured on two Narragansett Bay, R.I., islands inhabited by deer, the principal host for the adult stages of the vector tick, Ixodes dammini. Immature ticks parasitized mice from both islands. From 105 mice captured on four other islands not inhabited by deer neither pathogen was isolated, nor were I. dammini found.
Influence of 5-Methyltryptophan-Resistant
Bradyrhizobium japonicum
on Soybean Root Nodule Indole-3-Acetic Acid Content
Authors: Hunter William J.
Published: January 2020

Bradyrhizobium japonicum
mutants resistant to 5-methyltryptophan were isolated. Some of these mutants were found to accumulate indole-3-acetic acid (IAA) and tryptophan in culture. In greenhouse studies, nodules from control plants inoculated with wild-type bradyrhizobia contained 0.04, 0.10, and 0.58 μg of free, ester-linked, and peptidyl IAA g (fresh weight) of nodules
−1
, respectively. Nodules from plants inoculated with 5-methyltryptophan-resistant bradyrhizobia contained 0.94, 1.30, and 10.6 μg of free, ester-linked, and peptidyl IAA g (fresh weight) of nodules
−1
, respectively. This manyfold increase in nodule IAA content indicates that the
Bradyrhizobium
inoculum can have a considerable influence on the endogenous IAA level of the nodule. Further, these data imply that much of the IAA that accumulated in the high-IAA-containing nodules was of bacterial rather than plant origin. These high-IAA-producing 5-methyltryptophan-resistant bacteria were poor symbiotic nitrogen fixers. Plants inoculated with these bacteria had a lower nodule mass and fixed less nitrogen per gram of nodule than did plants inoculated with wild-type bacteria.
Generation of Tn5 insertions in streptococcal conjugative transposon Tn916
Authors: Yamamoto M , Jones J M , Senghas E , Gawron-Burke C , Clewell D B
Published: January 2020

A method has been developed for the introduction of Tn5 into Escherichia coli plasmid chimeras containing Streptococcus faecalis DNA. Tn5 could be introduced via a lambda::Tn5 delivery vehicle. The system proved to be particularly efficient and facilitated insertions at numerous sites on DNA containing the 16-kilobase conjugative transposon Tn916. It was possible to introduce some of the resulting Tn916::Tn5 derivatives back into S. faecalis by using a recently developed protoplast transformation procedure. A presumed zygotic induction resulted in insertion of the Tn916 derivatives at multiple sites in the S. faecalis chromosome.
Coagglutination and enzyme capture tests for detection of Escherichia coli beta-galactosidase, beta-glucuronidase, and glutamate decarboxylase
Authors: Kaspar C W , Hartman P A , Benson A K
Published: January 2020

Polyclonal antibodies to Escherichia coli beta-galactosidase, beta-glucuronidase, and glutamate decarboxylase were used in coagglutination tests for identification of these three enzymes in cell lysates. Enzyme capture assays were also developed for the detection of E. coli beta-galactosidase and beta-glucuronidase. The enzymes were released by using a gentle lysis procedure that did not interfere with antibody-enzyme interactions. All three enzymes were detected in 93% (51 of 55) of the E. coli strains tested by coagglutination; two of the three enzymes were identified in the remaining 7%. Of 42 non-E. coli tested by coagglutination, only four nonspecifically agglutinated either two or three of the anti-enzyme conjugates. Thirty-two (76%) non-E. coli isolates were negative by coagglutination for all three enzymes. The enzyme capture assay detected the presence of beta-galactosidase in seven of eight and beta-glucuronidase in all eight strains of E. coli tested. Some strains of beta-galactosidase-positive Citrobacter freundii and Enterobacter cloacae were also positive by the enzyme capture assay, indicating that the antibodies were not entirely specific for E. coli beta-galactosidase; however, five other gas-positive non-E. coli isolates were negative by the enzyme capture assay. The coagglutination tests and enzyme capture assays were rapid and sensitive methods for the detection of E. coli beta-galactosidase, beta-glucuronidase, and glutamate decarboxylase.
Bradyrhizobium japonicum
-Environment Interactions: Nodulation and Interstrain Competition in Soils along an Elevational Transect
Authors: George Thomas , Bohlool B. Ben , Singleton Paul W.
Published: January 2020

The effects of temperature and soil type on interstrain competition of
Bradyrhizobium japonicum
and on nodulation and nitrogen accumulation in five soybean varieties belonging to four maturity groups were investigated at three sites devoid of soybean rhizobia along an elevational transect in Hawaii. Competition patterns of the three
B. japonicum
strains were unaffected by soil type or soil temperature. Strain USDA 110 was the best competitor, occupying on the average 81 and 64% of the nodules in the field and greenhouse experiments, respectively. Strain USDA 138 was the least successful in the field (4%), although it formed 34% of the nodules in the greenhouse. Nodule occupancy by
B. japonicum
strains was found to be related to soybean maturity group. Strain USDA 110 formed 61, 71, 88, 88, and 98% of the nodules in the field on Clay (00), Clark (IV), D68-0099 (VI), N77-4262 (VI), and Hardee (VIII), respectively. Strain USDA 136b formed few nodules on Hardee, an
Rj2
soybean variety incompatible with that strain, in both experiments. Nodule number and weight at the 1,050-m site were reduced to 41 and 27%, respectively, of those at the 320-m site because of the decrease in temperature. Nodule number increased with increasing maturity group number at each site; however, there was not a corresponding increase in nodule weight. Nitrogen accumulation decreased from 246 mg of N per plant at the lowest elevation site to 26 mg of N per plant at the highest elevation. While soil type and temperature had no effect on strain competition, temperature had a profound influence on nodule parameters and plant growth.
Stimulation by Hyphopichia burtonii and Bacillus amyloliquefaciens of aflatoxin production by Aspergillus flavus in irradiated maize and rice grains
Authors: Cuero R G , Smith J E , Lacey J
Published: January 2020

Aspergillus flavus was grown on maize and rice extract agars and on irradiated viable cracked maize and rice grains, either in pure culture or in dual culture with wild strains of either Hyphopichia burtonii or Bacillus amyloliquefaciens. Aflatoxin production by A. flavus and its growth and interactions with the other microorganisms were studied at three water activities (aw) (0.98, 0.95, and 0.90) and two temperatures (25 and 16 degrees C). Both H. burtonii and B. amyloliquefaciens markedly stimulated growth and aflatoxin production by A. flavus on cracked maize, especially at 25 degrees C and 0.95 and 0.98 aw. No aflatoxin was detected in pure cultures of A. flavus on cracked rice after 12 days of incubation at 25 degrees C, but some was produced by mixed cultures at 16 degrees C and 0.98 aw. The morphological interactions among A. flavus, H. burtonii, and B. amyloliquefaciens were also examined on maize and rice extract agars under similar controlled conditions.
Effect of Bacteriophage on Colonization of Sugarbeet Roots by Fluorescent
Pseudomonas
spp
Authors: Stephens Peter M. , O'Sullivan Marian , O'Gara Fergal
Published: January 2020

The colonization potential of two fluorescent
Pseudomonas
strains (M11/4, B2/6) that exhibit antifungal activity in vitro was studied on the roots of sugarbeet plants in a clay loam soil. The cell density of the introduced bacteria declined on the root system over a 16-day test period in nonsterile soil. Strain B2/6 declined at a significantly faster rate compared with M11/4. This loss in viability and difference in colonization ability between M11/4 and B2/6 was not observed in sterile soil. Nutrient deprivation induced by indigenous microorganisms was excluded as a key factor involved in the decline of the introduced bacteria on the basis that strains M11/4 and B2/6 retained viability when subjected to nutrient starvation conditions over a 16-day period. Experiments designed to test whether antagonism by indigenous microorganisms was responsible for the decline in the introduced fluorescent
Pseudomonas
sp. population revealed the presence of large numbers of bacteriophage in the soil capable of lysing strain B2/6. Reconstitution experiments carried out with sugarbeet seedlings inoculated independently with strains M11/4 and B2/6 and grown in sterile soil to which a soil phage filtrate had been added showed a significant decrease in the viability of strain B2/6 relative to M11/4. Phage antagonistic toward strain B2/6 were detected in 43% of soils taken from the major sugarbeet growing regions of Ireland.
Nitrous Oxide Reduction in Nodules: Denitrification or N
2
Fixation?
Authors: Coyne M. S. , Focht D. D.
Published: January 2020

Detached cowpea nodules that contained a nitrous oxide reductase-positive (Nor
+
) rhizobium strain (8A55) and a nitrous oxide reductase-negative (Nor
−
) rhizobium strain (32H1) were incubated with 1%
15
N
2
O (95 atom%
15
N) in the following three atmospheres: (i) aerobic with C
2
H
2
(10%), (ii) aerobic without C
2
H
2
, and (iii) anaerobic (argon atmosphere) without C
2
H
2
. The greatest production of
15
N
2
occurred anaerobically with 8A55, yet very little was formed with 32H1. Although acetylene reduction activity was slightly higher with 32H1, about 10 times more
15
N
2
was produced aerobically by 8A55 than by 32H1 in the absence of acetylene. The major reductive pathway of N
2
O reduction by denitrifying rhizobium strain 8A55 is by nitrous oxide reductase rather than nitrogenase.
Attachment as a factor in the protection of Enterobacter cloacae from chlorination
Authors: Herson D S , McGonigle B , Payer M A , Baker K H
Published: January 2020

Enterobacter cloacae attached to drinking water distribution particles was subjected to chlorination. Attachment resulted in the protection of these organisms from disinfection. This effect was found to be dependent upon both the level of chlorine in the system and attachment time. The results obtained in this study indicate that attached organisms may play an important role in coliform outbreaks.
Induction of siderophore activity in Anabaena spp. and its moderation of copper toxicity
Authors: Clarke S E , Stuart J , Sanders-Loehr J
Published: January 2020

Growth of Anabaena sp. strain 7120 (in the absence of chelators or added iron) was inhibited by the addition of 2.1 to 6.5 microM copper and was abolished by copper concentration of 10 microM or higher. When the copper was chelated to schizokinen (the siderophore produced by this organism in response to iron starvation), the toxic effects were eliminated. Analysis of culture filtrates showed that the cupric schizokinen remains in the medium, thereby lowering the amount of copper taken up by the cells. Although this organism actively transports ferric schizokinen, it apparently does not recognize the cupric complex. Thus, Anabaena sp. is protected from copper toxicity under conditions in which siderophore is being produced. For cells grown in low iron, the accumulation of extracellular schizokinen was observed to parallel cell growth and continue well into stationary phase. The actual iron status of the organism was monitored by using iron uptake velocity as an assay. Cultures grown on 0.1 microM added iron were found to be severely iron limited upon reaching stationary phase, thus explaining the continued production of schizokinen. These data show that the siderophore system in Anabaena spp. has developed primarily as a response to iron starvation and that additional functions such as alleviation of copper toxicity or allelopathic inhibition of other algal species are merely secondary benefits.
Isolation and Characterization of Thermophilic Bacterial Strains with Inulinase Activity
Authors: Allais Jean-Jacques , Hoyos-Lopez Gladys , Kammoun Sadok , Baratti Jacques C.
Published: January 2020

Nine bacterial strains growing on inulin as the sole carbon and energy source were isolated from soil samples by enrichment culture on a mineral medium. Four of the strains were thermophilic and belong to the genus
Bacillus.
The thermophilic strains synthesized a β-fructosidase that was active on both inulin and sucrose. The presence of inulin in the culture medium is necessary for enzyme synthesis. Most of the activity on inulin was recovered in the culture medium, and the enzyme was synthesized during cell growth.
Comparison of media and methods for detecting and enumerating Listeria monocytogenes in refrigerated cabbage
Authors: Hao D Y , Beuchat L R , Brackett R E
Published: January 2020

Direct plating, selective enrichment, and cold enrichment followed by secondary selective enrichment procedures were compared for detecting and enumerating Listeria monocytogenes in chopped cabbage stored at 5 degrees C for up to 64 days. Addition of Fe3+ to solid media enhanced detection of the organism. Cold enrichment (5 degrees C) in nutrient broth and brain heart infusion broth followed by secondary enrichment (48 h, 30 degrees C) in Trypticase soy-yeast extract-antibiotic broth and thiocyanate-nalidixic acid broth and plating on selective agar media (Doyle and Schoeni selective enrichment agar [minus acriflavin hydrochloride, supplemented with 5 micrograms of Fe3+/ml] and McBride Listeria agar) resulted in the detection of highest populations.