bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficiency of bacterial protein synthesis during anaerobic degradation of cattle waste
Authors: Mackie R I , Bryant M P
Published: January 2020

The rate of [15N]ammonia (15NH3) uptake or incorporation into bacterial cells was studied, using stirred, 3-liter benchtop digestors fed on a semicontinuous basis with cattle waste. The fermentations were carried out at 40 and 60 degrees C and at four different loading rates (3, 6, 9, and 12 g of volatile solids per liter of reactor volume per day). The rate of NH3-N incorporation for the period 1 to 5 h after feeding at the four different loading rates was 0.49, 0.83, 1.05, and 1.08 mg/liter per h in the mesophilic digestor and 0.68, 1.07, 1.17, and 1.21 mg/liter per h in the thermophilic digestor. Values were lower 7 to 21 h after feeding in both digestors and were related to the rate of fermentation or CH4 production. In the mesophilic digestors, the rate of bacterial cell production ranged from 3.97 to 8.72 mg of dry cells per liter per h, 1 to 5 h after feeding at the different loading rates. Corresponding values for the thermophilic digestors ranged from 5.46 to 9.77 mg of dry cells per liter per h. Cell yield values ranged from 2.3 to 3.1 mg of dry cells per mol of CH4 produced in the mesophilic and thermophilic digestors at the two lower loading rates. The values were higher (2.8 to 3.4) in the mesophilic digestors at the two higher loading rates because of the accumulation of propionate and a consequent reduction in CH4 production. Low cell yields such as those measured in this study are characteristic of low-specific-growth rates under energy-limited conditions.
Construction of a Symbiotically Effective Strain of
Rhizobium leguminosarum
bv.
trifolii
with Increased Nodulation Competitiveness
Authors: Triplett Eric W.
Published: January 2020

Genes involved in nodulation competitiveness (
tfx
) were inserted by marker exchange into the genome of the effective strain
Rhizobium leguminosarum
bv.
trifolii
TA1. Isogenic strains of TA1 were constructed which differed only in their ability to produce trifolitoxin, an antirhizobial peptide. Trifolitoxin production by the ineffective strain
R. leguminosarum
bv.
trifolii
T24 limited nodulation of clover roots by trifolitoxin-sensitive strains of
R. leguminosarum
bv.
trifolii
. The trifolitoxin-producing exconjugant TA1::10-15 was very competitive for nodulation on clover roots when coinoculated with a trifolitoxin-sensitive reference strain. The nonproducing exconjugant TA1::12-10 was not competitive for nodule occupancy when coinoculated with the reference strain. Tetracycline sensitivity and Southern analysis confirmed the loss of vector DNA in the exconjugants. Trifolitoxin production by TA1::10-15 was stable in the absence of selection pressure. Transfer of
tfx
to TA1 did not affect nodule number or nitrogenase activity. These experiments represent the first stable genetic transfer of genes involved in nodulation competitiveness to a symbiotically effective
Rhizobium
strain.
Biodegradation of p-nitrophenol in an aqueous waste stream by immobilized bacteria
Authors: Heitkamp M A , Camel V , Reuter T J , Adams W J
Published: January 2020

Microbiological analyses of activated sludge reactors after repeated exposure to 100 mg of p-nitrophenol (PNP) per liter resulted in the isolation of three Pseudomonas species able to utilize PNP as a sole source of carbon and energy. Cell suspensions of the three Pseudomonas sp., designated PNP1, PNP2, and PNP3, mineralized 70, 60, and 45% of a 70-mg/liter dose of PNP in 24, 48, and 96 h, respectively. Mass-balance analyses of PNP residues for all three cultures showed that undegraded PNP was less than 1% (less than 50 micrograms); volatile metabolites, less than 1%; cell residues, 8.4 to 14.9%; and water-soluble metabolites, 1.2 to 6.7%. A mixed culture of all three PNP-degrading Pseudomonas sp. was immobilized by adsorption onto diatomaceous earth biocarrier in a 1.75-liter Plexiglas column. The column was aerated and exposed to a synthetic waste stream containing 629 to 2,513 mg of PNP per liter at flow rates of 2 to 15 ml/min. Chemical loading studies showed that the threshold concentration for acute toxicity of PNP to the immobilized bacteria was 2,100 to 2,500 mg/liter. Further studies at PNP concentrations of 1,200 to 1,800 mg/liter showed that greater than 99 and 91 to 99% removal of PNP was achieved by immobilized bacteria at flow rates of 10 and 12 ml/min, respectively. These values represent hydraulic retention times of 48 to 58 min and PNP removal rates of 0.99 to 1.1 mg/h per g of biocarrier at 25 degrees C under optimal conditions. This study shows the successful use of immobilized bacteria technology to remove high concentrations of PNP from aqueous waste streams.
Biotoxicity of mercury as influenced by mercury(II) speciation
Authors: Farrell R E , Germida J J , Huang P M
Published: January 2020

Integration of physicochemical procedures for studying mercury(II) speciation with microbiological procedures for studying the effects of mercury on bacterial growth allows evaluation of ionic factors (e.g., pH and ligand species and concentration) which affect biotoxicity. A Pseudomonas fluorescens strain capable of methylating inorganic Hg(II) was isolated from sediment samples collected at Buffalo Pound Lake in Saskatchewan, Canada. The effect of pH and ligand species on the toxic response (i.e., 50% inhibitory concentration [IC50]) of the P. fluorescens isolated to mercury were determined and related to the aqueous speciation of Hg(II). It was determined that the toxicities of different mercury salts were influenced by the nature of the co-ion. At a given pH level, mercuric acetate and mercuric nitrate yielded essentially the same IC50s; mercuric chloride, on the other hand, always produced lower IC50s. For each Hg salt, toxicity was greatest at pH 6.0 and decreased significantly (P = 0.05) at pH 7.0. Increasing the pH to 8.0 had no effect on the toxicity of mercuric acetate or mercuric nitrate but significantly (P = 0.05) reduced the toxicity of mercuric chloride. The aqueous speciation of Hg(II) in the synthetic growth medium M-IIY (a minimal salts medium amended to contain 0.1% yeast extract and 0.1% glycerol) was calculated by using the computer program GEOCHEM-PC with a modified data base. Results of the speciation calculations indicated that complexes of Hg(II) with histidine [Hg(H-HIS)HIS+ and Hg(H-HIS)2(2+)], chloride (HgCl+, HgCl2(0), HgClOH0, and HgCl3-), phosphate (HgHPO4(0), ammonia (HgNH3(2+), glycine [Hg(GLY)+], alanine [Hg(ALA)+], and hydroxyl ion (HgOH+) were the Hg species primarily responsible for toxicity in the M-IIY medium. The toxicity of mercuric nitrate at pH 8.0 was unaffected by the addition of citrate, enhanced by the addition of chloride, and reduced by the addition of cysteine. In the chloride-amended system, HgCl+, HgCl2(0), and HgClOH0 were the species primarily responsible for observed increases in toxicity. In the cysteine-amended system, formation of Hg(CYS)2(2-) was responsible for detoxification effects that were observed. The formation of Hg-citrate complexes was insignificant and had no effect on Hg toxicity.
Lignocarbohydrate Solubilization from Straw by Actinomycetes
Authors: Ball A. S. , Godden B. , Helvenstein P. , Penninckx M. J. , McCarthy A. J.
Published: January 2020

Actinomycetes grown on wheat straw solubilized a lignocarbohydrate fraction which could be recovered by acid precipitation. Further characterization of this product (APPL) during growth of
Streptomyces
sp. strain EC1 revealed an increase in carboxylic acid and phenolic hydroxyl content, suggesting progressive modification. This was also observed in dioxane-extracted lignin fractions of degraded straw, and some similarity was further suggested by comparative infrared spectroscopy. However, the molecular weight profile of APPL was relatively constant during growth of
Streptomyces
sp. strain EC1 on straw, while analysis of the dioxane-extracted lignin fractions appeared to show fragmentation followed by repolymerization. Lignocarbohydrate solubilization could be monitored in all cultures by routine assay of APPL-associated protein, which accounted for up to 20% of the extracellular culture protein in some cases. Interestingly, this protein fraction was found to include active hydrolytic and oxidative enzymes involved in the degradation of lignocellulose, and specific enzyme activities were often increased in the acid-insoluble fractions of culture supernatants. This was particularly important for peroxidase and veratryl oxidase activities, which could be readily detected in the acid-precipitable lignocarbohydrate complex but were virtually undetectable in untreated culture supernatants.
Degradation of vinyl acetate by soil, sewage, sludge, and the newly isolated aerobic bacterium V2
Authors: Nieder M , Sunarko B , Meyer O
Published: January 2020

Vinyl acetate is subject to microbial degradation in the environment and by pure cultures. It was hydrolyzed by samples of soil, sludge, and sewage at rates of up to 6.38 and 1 mmol/h per g (dry weight) under aerobic and anaerobic conditions, respectively. Four yeasts and thirteen bacteria that feed aerobically on vinyl acetate were isolated. The pathway of vinyl acetate degradation was studied in bacterium V2. Vinyl acetate was degraded to acetate as follows: vinyl acetate + NAD(P)+----2 acetate + NAD(P)H + H+. The acetate was then converted to acetyl coenzyme A and oxidized through the tricarboxylic acid cycle and the glyoxylate bypass. The key enzyme of the pathway is vinyl acetate esterase, which hydrolyzed the ester to acetate and vinyl alcohol. The latter isomerized spontaneously to acetaldehyde and was then converted to acetate. The acetaldehyde was disproportionated into ethanol and acetate. The enzymes involved in the metabolism of vinyl acetate were studied in extracts. Vinyl acetate esterase (Km = 6.13 mM) was also active with indoxyl acetate (Km = 0.98 mM), providing the basis for a convenient spectrophotometric test. Substrates of aldehyde dehydrogenase were formaldehyde, acetaldehyde, propionaldehyde, and butyraldehyde. The enzyme was equally active with NAD+ or NADP+. Alcohol dehydrogenase was active with ethanol (Km = 0.24 mM), 1-propanol (Km = 0.34 mM), and 1-butanol (Km = 0.16 mM) and was linked to NAD+. The molecular sizes of aldehyde dehydrogenase and alcohol dehydrogenase were 145 and 215 kilodaltons, respectively.
Competitive Ability and Efficiency in Nodule Formation of Strains of
Bradyrhizobium japonicum
Authors: McDermoti Timothy R. , Graham Peter H.
Published: January 2020

In the American Midwest, superior N
2
-fixing inoculant strains of
Bradyrhizobium japonicum
consistently fail to produce the majority of nodules on the roots of field-grown soybean. Poor nodulation by inoculant strains is partly due to their inability to stay abreast of the expanding soybean root system in numbers sufficient for them to be competitive with indigenous bradyrhizobia. However, certain strains are noncompetitive even when numerical dominance is not a factor. In this study, we tested the hypothesis that the nodule occupancy achieved by strains is related to their nodule-forming efficiency. The nodulation characteristics and competitiveness of nine strains of
B. japonicum
were compared at both 20 and 30°C. The root tip marking technique was used, with the nodule-forming efficiency of each strain estimated from the average position of the uppermost nodule and the number of nodules formed above the root tip mark. The competitiveness of the nine strains relative to
B. japonicum
USDA 110 was determined by using immunofluorescence to identify nodule occupants. The strains differed significantly in competitiveness with USDA 110 and in nodulation characteristics, strains that were poor competitors usually proving to be inferior in both the average position of the uppermost root nodule and the number of nodules formed above the root tip mark. Thus, competitiveness was correlated with both the average position of the uppermost nodule (
r
= 0.5;
P
= 0.036) and the number of nodules formed above the root tip mark (
r
= 0.64;
P
= 0.005), while the position of the uppermost nodule was also correlated to the percentage of plants nodulated above the root tip mark (
r
= 0.81;
P
< 0.001) and the percentage of plants nodulated on the taproot (
r
= 0.67;
P
= 0.002).
Effects of molecular oxygen, oxidation-reduction potential, and antioxidants upon in vitro replication of Treponema pallidum subsp. pallidum
Authors: Cox D L , Riley B , Chang P , Sayahtaheri S , Tassell S , Hevelone J
Published: January 2020

The effects of various concentrations of dithiothreitol, molecular oxygen, and several antioxidants upon the in vitro replication of Treponema pallidum were studied. The optimal dithiothreitol concentration was between 0.65 and 1.62 mM, and the optimum oxygen concentration was 3.0% +/- 0.5% in both the presence and absence of additional antioxidants. It was discovered that the reduced sulfhydryl concentration and the oxidation-reduction potential of the medium were stabilized after 5 days. The water-soluble antioxidants cobalt chloride, cocarboxylase, mannitol, and histidine were individually tested for their ability to increase treponemal growth in vitro. The optimum concentrations for these antioxidants were 21 nM, 4.3 nM, 0.55 mM, and 0.23 mM, respectively. When combined at these concentrations, the mixture of antioxidants stimulated the in vitro replication of T. pallidum. The number of treponemes in cultures with the antioxidants averaged a 59-fold increase, compared with a 43-fold increase in cultures lacking the antioxidants. It was further demonstrated that histidine and mannitol were the most critical components of this mixture. Catalase and superoxide dismutase were investigated for their ability to promote the growth and maintain viability of T. pallidum in tissue culture. The optimum concentrations for these enzymes were 10,000 U/liter and 25,000 U/liter, respectively. When these enzymes and the above antioxidants were combined and added to a chemically reduced modified Eagle medium, the treponemes increased an average of 70-fold, compared with an average of 35-fold in cultures lacking them. Furthermore, this medium, T. pallidum culture medium, supported the replication of T. pallidum at oxygen concentrations from 5 to 7% with little loss in yield or viability. The lipid-soluble antioxidants vitamin A and vitamin E acetate were also shown to enhance the in vitro growth of T. pallidum in this medium.
Effects of Physicochemical Factors on the Adhesion to Cellulose Avicel of the Ruminal Bacteria
Ruminococcus flavefaciens
and
Fibrobacter succinogenes
subsp.
succinogenes
Authors: Roger Valérie , Fonty Gérard , Komisarczuk-Bony Sylvie , Gouet Philippe
Published: January 2020

Ruminococcus flavefaciens
adhered instantly to cellulose, while
Fibrobacter succinogenes
had the highest percentage of adherent cells after about 25 min of contact between bacteria and cellulose. Adhesion of
R. flavefaciens
was unaffected by high concentrations of sugars (5%), temperature, pH, oxygen, metabolic inhibitors, and lack of Na
+
. In contrast, the attachment was affected by the removal of divalent cations (Mg
2+
and Ca
2+
), the presence of cellulose derivatives (methylcellulose and hydroxyethylcellulose), and cystine. Adhesion of
F. succinogenes
was sensitive to low and high temperatures, high concentrations of glucose and cellobiose (5%), hydroxyethylcellulose (0.1%), redox potential, pH, lack of monovalent cations, and the presence of an inhibitor of membrane ATPases or lasalocid and monensin. Cells of
F. succinogenes
heated at 100°C no longer were adherent. On the other hand, adhesion was insensitive to the lack of divalent cations (Mg
2+
and Ca
2+
), the presence of 2,4-dinitrophenol, tetrachlorosalicylanilide, or inhibitors of the electron transfer chains. Adhesion of
F. succinogenes
seems to be related to the metabolic functions of the cell. External proteins and/or cellulases themselves might play a part in the attachment process. Several mechanisms are probably involved in the adhesion of
R. flavefaciens
, the main one being the interaction between the large glycocalyx and the divalent cations Ca
2+
and Mg
2+
. Hydrophobic bonds and enzymes may also be involved.
In Situ Depletion of Pentachlorophenol from Contaminated Soil by
Phanerochaete
spp
Authors: Lamar Richard T. , Dietrich Diane M.
Published: January 2020

The ability of two white rot fungi to deplete pentachlorophenol (PCP) from soil, which was contaminated with a commercial wood preservative, was examined in a field study. Inoculation of soil containing 250 to 400 μg of PCP g
−1
with either
Phanerochaete chrysosporium
or
P. sordida
resulted in an overall decrease of 88 to 91% of PCP in the soil in 6.5 weeks. This decrease was achieved under suboptimal temperatures for the growth and activity of these fungi, and without the addition of inorganic nutrients. Since the soil had a very low organic matter content, peat was included as a source of organic carbon for fungal growth and activity. A small percentage (8 to 13%) of the decrease in the amount of PCP was a result of fungal methylation to pentachloroanisole. Gas chromatographic analysis of sample extracts did not reveal the presence of extractable transformation products other than pentachloroanisole. Thus, when losses of PCP via mineralization and volatilization were negligible, as they were in laboratory-scale studies (R. T. Lamar, J. A. Glaser, and T. K. Kirk, Soil Biol. Biochem. 22:433-440, 1990), most of the PCP was converted to nonextractable soil-bound products. The nature, stability, and toxicity of soil-bound transformation products, under a variety of conditions, must be elucidated before use of these fungi in soil remediation efforts can be considered a viable treatment method.
Incidence and characterization of Listeria monocytogenes in foods available in Taiwan
Authors: Wong H C , Chao W L , Lee S J
Published: January 2020

A variety of foods were examined for the incidence of Listeria monocytogenes, and the bacterial isolates were further characterized. L. monocytogenes was selected on LiCl-phenylethanol-moxalactam agar after enrichments and identified by several biochemical, mobility, and CAMP tests. L. monocytogenes was isolated from 58.8% of pork samples, 50% of chicken carcasses, 38% of turkey parts, 34% of frozen semiready foods, 24% of beef steaks, 12.2% of vegetables, 10.5% of seafoods, and 4.4% of frozen dim sum but was not found in the Chinese pickles and fermented milks. Isolates from seafoods, turkey parts, and beef samples had higher hemolytic activity than those from other samples. The isolates were highly susceptible to ampicillin, cephalothin, chloramphenicol, erythromycin, gentamicin, kanamycin, neomycin, novobiocin, penicillin, and streptomycin. About 14.5% of the isolates were resistant to methicillin, and 14.5% were resistant to tetracycline. The majority of the isolates from turkey parts and beef steaks were serotype 1, and those from chicken and pork samples were serotype 4 and others. Hemolytic activity, methicillin susceptibility, and serotype distribution of the isolates from domestic and imported food samples were significantly different. The results suggest the presence of food- or geography-specific L. monocytogenes strains.
Enhancing the Viability of
Lactobacillus plantarum
Inoculum by Immobilizing the Cells in Calcium-Alginate Beads Incorporating Cryoprotectants
Authors: Kearney Louise , Upton Mary , Mc Loughlin Aiden
Published: January 2020

Many literature reports have cited the importance of the rehydration conditions of lyophilized cultures in determining viability. The rate of rehydration and the volume of fluid used have been identified as two important factors. One possible means of controlling these is by immobilizing the cells before lyophilization within a gel matrix in which the subsequent rehydration rate and fluid volume would be controlled by the properties of the gel. In this study
Lactobacillus plantarum
was immobilized and lyophilized in Ca-alginate beads in which 1 M glycerol or 0.75 M adonitol with skim milk were incorporated as a cryoprotectant. The properties of these Ca-alginate beads were examined before and after lyophilization and rehydration. The beads incorporating glycerol were smaller and stronger than those with adonitol. After lyophilization, size decreased and strength increased but to a greater extent in the beads with glycerol, indicating that the microenvironment within the two bead types was probably different. The protective effect of the bead microenvironment on immobilized
L. plantarum
was also examined. Lyophilization and rehydration within the alginate beads with either polyol yielded higher survival rates than that attained with free cell cultures during rehydration in optimal or suboptimal conditions. During rehydration under suboptimal conditions, the immobilized cell survival was greatest when 0.75 M adonitol was the incorporated cryoprotectant.
Production of S-(+)-ibuprofen from a nitrile compound by Acinetobacter sp. strain AK226
Authors: Yamamoto K , Ueno Y , Otsubo K , Kawakami K , Komatsu K
Published: January 2020

S-(+)-2-(4'-Isobutylphenyl)propionic acid [S-(+)-ibuprofen] was produced from racemic 2-(4'-isobutylphenyl)propionitrile (Ibu-CN) by an isolated bacterial strain, Acinetobacter sp. strain AK226. Ammonium acetate, acetonitrile, or n-butyronitrile as a carbon source in the culture medium was effective for bacterial growth and induction of this activity. The optimum pH of the reaction was around 8.0. S-(+)-Ibuprofen formed from Ibu-CN by resting cells was present in a 95% enantiomeric excess. Acinetobacter sp. strain AK226 appeared to possess a nitrilase for Ibu-CN because 2-(4'-isobutylphenyl)propionamide was not detected in the reaction mixture and 2-(4'-isobutylphenyl)propionamide was not hydrolyzed to S-(+)-ibuprofen. Since S-(+)-ibuprofen was preferentially produced while the R enantiomer of Ibu-CN was left almost intact over the time course of the reaction, the putative nitrilase appeared to be highly specific for the S enantiomer of Ibu-CN.
Digestion of Barley, Maize, and Wheat by Selected Species of Ruminal Bacteria
Authors: McAllister Tim A. , Cheng K.-J. , Rode Lyle M. , Forsberg Cecil W.
Published: January 2020

Differences in the digestion of barley, maize, and wheat by three major ruminal starch-digesting bacterial species,
Streptococcus bovis
26,
Ruminobacter amylophilus
50, and
Butyrivibrio fibrisolvens
A38, were characterized. The rate of starch digestion in all cereal species was greater for
S. bovis
26 than for
R. amylophilus
50 or
B. fibrisolvens
A38. Starch digestion by
S. bovis
26 was greater in wheat than in barley or maize, whereas starch digestion by
R. amylophilus
50 was greater in barley than in maize or wheat.
B. fibrisolvens
A38 digested the starch in barley and maize to a similar extent but was virtually unable to digest the starch in wheat. The higher ammonia concentration in cultures of
B. fibrisolvens
A38 when grown on wheat than when grown on barley or maize suggests that
B. fibrisolvens
A38 utilized wheat protein rather than starch. Scanning electron microscopy revealed that
B. fibrisolvens
A38 initially colonized cell wall material, while
S. bovis
26 randomly colonized the endosperm and
R. amylophilus
50 preferentially colonized starch granules. There was subsequent colonization but only superficial digestion of wheat starch granules by
B. fibrisolvens
A38. Variation in the association between starch and protein within the endosperm of cereal grains contributes to the differential effectiveness with which amylolytic species can utilize cereal starch.
Application of direct plaque assay for detection and enumeration of bacteriophages of Bacteroides fragilis from contaminated-water samples
Authors: Cornax R , Moriñigo M A , Paez I G , Muñoz M A , Borrego J J
Published: January 2020

The direct double-agar-layer plaque assay for the detection and enumeration of specific bacteriophages of Bacteroides fragilis from contaminated-water samples was performed. Several factors that affect the methods, such as conditions of the bacterial culture, composition of the assay medium, addition of divalent cations, and decontamination techniques applied to the sample, were evaluated. The results obtained show that the direct assay technique proved to be more efficient than the most-probable-number technique. A higher recovery of bacteriophages was obtained from 17 of 24 samples with the direct assay. The two methods only showed similar results from samples with a low degree of pollution.
Remobilization of toxic heavy metals adsorbed to bacterial wall-clay composites
Authors: Flemming C A , Ferris F G , Beveridge T J , Bailey G W
Published: January 2020

Significant quantities of Ag(I), Cu(II), and Cr(III) were bound to isolated Bacillus subtilis 168 walls, Escherichia coli K-12 envelopes, kaolinite and smectite clays, and the corresponding organic material-clay aggregates (1:1, wt/wt). These sorbed metals were leached with HNO3, Ca(NO3)2, EDTA, fulvic acid, and lysozyme at several concentrations over 48 h at room temperature. The remobilization of the sorbed metals depended on the physical properties of the organic and clay surfaces and on the character and concentration of the leaching agents. In general, the order of remobilization of metals was Cr much less than Ag less than Cu. Cr was very stable in the wall, clay, and composite systems; pH 3.0, 500 microM EDTA, 120-ppm [mg liter-1] fulvic acid, and 160-ppm Ca remobilized less than 32% (wt/wt) of sorbed Cr. Ag (45 to 87%) and Cu (up to 100%) were readily removed by these agents. Although each leaching agent was effective at mobilizing certain metals, elevated Ca or acidic pH produced the greatest overall mobility. The organic chelators were less effective. Lysozyme digestion of Bacillus walls remobilized Cu from walls and Cu-wall-kaolinite composites, but Ag, Cr, and smectite partially inhibited enzyme activity, and the metals remained insoluble. The extent of metal remobilization was not always dependent on increasing concentrations of leaching agents; for example, Ag mobility decreased with some clays and some composites treated with high fulvic acid, EDTA, and lysozyme concentrations. Sometimes the organic material-clay composites reacted in a manner distinctly different from that of their individual counterparts; e.g., 25% less Cu was remobilized from wall- and envelope-smectite composites than from walls, envelopes, or smectite individually in 500 microM EDTA. Alternatively, treatment with 160-ppm Ca removed 1.5 to 10 times more Ag from envelope-kaolinite composites than from the individual components. The particle size of the deposited metal may account for some of the stability changes; those metals that formed large, compact aggregates (Cr and Ag) as seen by transmission electron microscopy were less likely to be remobilized. In summary, it is apparent that remobilization of toxic heavy metals in sediments, soils, and the vadose zone is a complicated issue. Predictions based on single inorganic or organic component systems are too simplistic.
Production of fumonisins by Fusarium moniliforme and Fusarium proliferatum isolates associated with equine leukoencephalomalacia and a pulmonary edema syndrome in swine
Authors: Ross P F , Nelson P E , Richard J L , Osweiler G D , Rice L G , Plattner R D , Wilson T M
Published: January 2020

Fumonisin B1 (FB1) and FB2 were isolated from corn cultures of both Fusarium moniliforme and Fusarium proliferatum. Respective concentrations in culture materials of FB1 and FB2 ranged from 960 to 2,350 and 120 to 320 micrograms/g for F. moniliforme and from 1,670 to 2,790 and 150 to 320 micrograms/g for F. proliferatum. Thin-layer chromatography, gas chromatography-mass spectroscopy, high-performance liquid chromatography, and liquid secondary ion mass spectroscopy were used for detection. Fumonisins from F. proliferatum have not previously been reported.
Cell Surface Characteristics of Bacteriophage-Resistant
Lactococcus lactis
subsp.
cremoris
SK110 and Its Bacteriophage-Sensitive Variant SK112
Authors: Sijtsma Lolke , Jansen Natali , Hazeleger Wilma C. , Wouters Jan T. M. , Hellingwerf Klaas J.
Published: January 2020

Several cell surface characteristics of bacteriophage-resistant
Lactococcus lactis
subsp.
cremoris
SK110 were compared with those of its phage-sensitive derivative SK112. After centrifugation, SK110 cells resisted suspension more strongly than SK112 cells. SK112 was more negatively charged and had a more hydrophobic cell surface than SK110. Furthermore, SK112 was agglutinated in the presence of concanavalin A, whereas SK110 was not. The opposite was observed upon incubation of cells of either strain with a lectin from
Ricinus communis.
A mild alkali treatment decreased the differences in the cell surface characteristics of the two strains remarkably.
Chlorophenol degradation coupled to sulfate reduction
Authors: Häggblom M M , Young L Y
Published: January 2020

We studied chlorophenol degradation under sulfate-reducing conditions with an estuarine sediment inoculum. These cultures degraded 0.1 mM 2-, 3-, and 4-chlorophenol and 2,4-dichlorophenol within 120 to 220 days, but after refeeding with chlorophenols degradation took place in 40 days or less. Further refeeding greatly enhanced the rate of degradation. Sulfate consumption by the cultures corresponded to the stoichiometric values expected for complete oxidation of the chlorophenol to CO2. Formation of sulfide from sulfate was confirmed with a radiotracer technique. No methane was formed, verifying that sulfate reduction was the electron sink. Addition of molybdate, a specific inhibitor of sulfate reduction, inhibited chlorophenol degradation completely. These results indicate that the chlorophenols were mineralized under sulfidogenic conditions and that substrate oxidation was coupled to sulfate reduction. In acclimated cultures the three monochlorophenol isomers and 2,4-dichlorophenol were degraded at rates of 8 to 37 mumol liter-1 day-1. The relative rates of degradation were 4-chlorophenol greater than 3-chlorophenol greater than 2-chlorophenol, 2,4-dichlorophenol. Sulfidogenic cultures initiated with biomass from an anaerobic bioreactor used in treatment of pulp-bleaching effluents dechlorinated 2,4-dichlorophenol to 4-chlorophenol, which persisted, whereas 2,6-dichlorophenol was sequentially dechlorinated first to 2-chlorophenol and then to phenol.
Double-Antibody Sandwich Enzyme-Linked Immunosorbent Assay for Cellobiohydrolase I
Authors: Riske Frank J. , Eveleigh Douglas E. , Macmillan James D.
Published: January 2020

A double-antibody sandwich enzyme-linked immunosorbent assay was developed for quantifying cellobiohydrolase I (CBH I) in crude preparations of the cellulase complex from
Trichoderma reesei.
The other enzymes (endoglucanase and β-glucosidase) in this complex and other ingredients in culture broth did not interfere with this assay. The antibody configuration that resulted in the highest specificity for the assay of CBH I employed a monoclonal antibody to coat wells in polystyrene plates and peroxidase-labeled polyclonal antibody to detect cellobiohydrolase bound to the immobilized monoclonal antibody. Previously, procedures have not been available for the direct assay of CBH I activity in the presence of the other enzymes in the complex, and current indirect procedures are cumbersome and inaccurate. The direct procedure described here is highly specific for CBH I and useful for quantifying this enzyme in the range of 0.1 to 0.8 μg/ml.
Isolation and Identification of the Coal-Solubilizing Agent Produced by
Trametes versicolor
Authors: Cohen Martin S. , Feldman Kathleen A. , Brown Cynthia S. , Gray Edward T.
Published: January 2020

Low-ranked coals were dissolved by using cell extracts derived from liquid cultures of
Trametes versicolor
. The coal-solubilizing agent (CSA) was separated from the broth components by a multistep isolation procedure including reverse-phase high-pressure liquid chromatography, size exclusion chromatography, ethanol fractionation, and recrystallization. Staircase voltammetry was used to show that two CSA moieties can coordinate to aqueous copper(II) ion. A molecular weight determination (using amperometry) gave an apparent molecular weight of 1.3
4
× 10
2
g/mol ± 8%. Nuclear magnetic resonance indicated that all protons on CSA are exchangeable in D
2
O and that there is only one type of carbon in CSA. The infrared spectrum of recrystallized CSA is identical to that of ammonium oxalate, and X-ray studies confirmed the crystal structure and composition of CSA to be that of ammonium oxalate monohydrate. The equivalent weight of the coal in solution, when the coal was dissolved by ammonium oxalate, is 7,940 g of coal per mol of iron present in the coal.
Single-Strain versus Multistrain Inoculation: Effect of Soil Mineral N Availability on Rhizobial Strain Effectiveness and Competition for Nodulation on Chick-Pea, Soybean, and Dry Bean
Authors: Somasegaran Padma , Bohlool B. Ben
Published: January 2020

The nitrogen-fixing effectiveness of multistrain inoculants was found to be determined by both the effectiveness of the component strains and the percentage of the nodules occupied by them. Multistrain formulations were always either as good as the most effective single-strain inoculant or intermediate between the most and the least effective. The percentage of nodules occupied and the amount of nitrogen fixed by the component strains of a multistrain inoculant showed highly significant linear correlation. The availability of soil N had a significant influence on the nitrogen fixation potential of each strain. The mineral N status of the soil was clearly a significant factor in affecting the competition pattern of
Rhizobium loti
(chick-pea) and
Bradyrhizobium japonicum
strains. Differences between the effectiveness of strains were masked under conditions of soil N availability. However, when soil N was immobilized with sugarcane bagasse, the differences became significant. In the chick-pea system,
R. loti
TAL 1148 (Nit 27A8) was the most effective but not the most competitive of the three strains used. In the soybean and dry bean systems,
B. japonicum
TAL 102 (USDA 110) and
R. leguminosarum
bv. phaseoli TAL 182, respectively, were consistently the most effective and, more often than not, the most competitive of the strains used for each species.
Susceptibility to Heavy Metals and Characterization of Heterotrophic Bacteria Isolated from Two Hydrothermal Vent Polychaete Annelids,
Alvinella pompejana
and
Alvinella caudata
Authors: Jeanthon Christian , Prieur Daniel
Published: January 2020

Specimens of alvinellid polychaetes and their tubes were collected in the Parigo hydrothermal vent field on the East Pacific Rise (13°N) in October and November 1987. Heterotrophic bacterial strains were isolated on metal-amended media from the tube and dorsal integument of one specimen of
Alvinella pompejana
, from the dorsal integument of another from the whole integument of a specimen of
Alvinella caudata
, and from undetermined alvinellid tubes. The strains were characterized and tested for susceptibility to five heavy metals by using a microdilution method for MIC determinations. All strains were gram-negative rods. Most of them were characterized by the ability to degrade Tween 80 and gelatin and to produce hydrogen sulfide from cysteine. Numerous strains, from all sample origins, displayed resistance to cadmium, zinc, arsenate, and silver and tolerated high amounts of copper. Metal resistance was exhibited by 92.3% of the total isolates. The occurrence of multiply resistant bacteria may demonstrate an adaptation of alvinellid-associated microflora to the general enrichment of metals in the hydrothermal vent environment.
Transformation of Aspergillus parasiticus with a homologous gene (pyrG) involved in pyrimidine biosynthesis
Authors: Skory C D , Horng J S , Pestka J J , Linz J E
Published: January 2020

The lack of efficient transformation methods for aflatoxigenic Aspergillus parasiticus has been a major constraint for the study of aflatoxin biosynthesis at the genetic level. A transformation system with efficiencies of 30 to 50 stable transformants per microgram of DNA was developed for A. parasiticus by using the homologous pyrG gene. The pyrG gene from A. parasiticus was isolated by in situ plaque hybridization of a lambda genomic DNA library. Uridine auxotrophs of A. parasiticus ATCC 36537, a mutant blocked in aflatoxin biosynthesis, were isolated by selection on 5-fluoroorotic acid following nitrosoguanidine mutagenesis. Isolates with mutations in the pyrG gene resulting in elimination of orotidine monophosphate (OMP) decarboxylase activity were detected by assaying cell extracts for their ability to convert [14C]OMP to [14C]UMP. Transformation of A. parasiticus pyrG protoplasts with the homologous pyrG gene restored the fungal cells to prototrophy. Enzymatic analysis of cell extracts of transformant clones demonstrated that these extracts had the ability to convert [14C]OMP to [14C]UMP. Southern analysis of DNA purified from transformant clones indicated that both pUC19 vector sequences and pyrG sequences were integrated into the genome. The development of this pyrG transformation system should allow cloning of the aflatoxin-biosynthetic genes, which will be useful in studying the regulation of aflatoxin biosynthesis and may ultimately provide a means for controlling aflatoxin production in the field.
Survival of bacteria during aerosolization
Authors: Marthi B , Fieland V P , Walter M , Seidler R J
Published: January 2020

One form of commercial application of microorganisms, including genetically engineered microorganisms is as an aerosol. To study the effect of aerosol-induced stress on bacterial survival, nonrecombinant spontaneous antibiotic-resistant mutants of four organisms, Enterobacter cloacae, Erwinia herbicola, Klebsiella planticola, and Pseudomonas syringae, were sprayed in separate experiments in a greenhouse. Samples were collected over a distance of 15 m from the spray site for enumeration. Spores of Bacillus subtilis were used as tracers to estimate the effects of dilution on changes in population over distance. Viable counts of P. syringae, Enterobacter cloacae, and K. planticola decreased significantly over a distance of 15 m. Erwinia herbicola showed no significant decline in counts over the same distance. The degree of survival of P. syringae during aerosolization was dependent on ambient environmental conditions (i.e., temperature, relative humidity), droplet size of the aerosol, and prior preparative conditions. Survival was greatest at high relative humidities (70 to 80%) and low temperatures (12 degrees C). Survival was reduced when small droplet sizes were used. The process of washing the cells prior to aerosolization also caused a reduction in their survival. Results from these experiments will be useful in developing sound methodologies to optimize enumeration and for predicting the downwind dispersal of airborne microorganisms, including genetically engineered microorganisms.
Effect of aerosolization on subsequent bacterial survival
Authors: Walter M V , Marthi B , Fieland V P , Ganio L M
Published: January 2020

To determine whether aerosolization could impair bacterial survival, Pseudomonas syringae and Erwinia herbicola were aerosolized in a greenhouse, the aerosol was sampled at various distances from the site of release by using all-glass impingers, and bacterial survival was followed in the impingers for 6 h. Bacterial survival subsequent to aerosolization of P. syringae and E. herbicola was not impaired 1 m from the site of release. P. syringae aerosolized at 3 to 15 m from the site of release at a temperature of 12 degrees C and a relative humidity of 80% survived 35- to 65-fold better than P. syringae released at 27 degrees C and a relative humidity of 40%. No difference was observed in the survival of P. syringae and E. herbicola following aerosolization at the same temperature and relative humidity. Bacteria sprayed directly onto bean and oat plants established stable populations at comparable numbers on both plants over an 8-day period following inoculation. Bacteria that inoculated adjacent plants by drifting downwind up to 5 m were detectable at an initial population of 10(2) CFU/g on oats and 10(5) CFU/g on beans 2 h after the spray. However, bacterial populations on both plants were undetectable within 48 h.
Immobilization of Chloroperoxidase on Aminopropyl-Glass
Authors: Kadima Tenshuk A. , Pickard Michael A.
Published: January 2020

Chloroperoxidase (CPO) purified from
Caldariomyces fumago
CMI 89362 was covalently bound to aminopropyl-glass by using a modification of an established method. Acid-washed glass was derivatized by using aminopropyltriethoxysilane, and the enzyme was ionically bound at low ionic strength. Further treatment with glutaraldehyde covalently linked the enzyme to the glass beads in an active form. No elution of bound activity from glass beads could be detected with a variety of washings. The loading of enzyme protein to the glass beads was highest, 100 mg of CPO per g of glass, at high reaction ratios of CPO to glass, but the specific activity of the immobilized enzyme was highest, 36% of theoretical, at low enzyme-to-carrier ratios. No differences in the properties of the soluble and immobilized enzymes could be detected by a number of criteria: their pH-activity and pH-stability profiles were similar, as were their thermal stabilities. After five uses, the immobilized enzyme retained full activity between pH 6.0 and 6.7.
Detection of Listeria monocytogenes in foods by immunomagnetic separation
Authors: Skjerve E , Rørvik L M , Olsvik O
Published: January 2020

Immunomagnetic separation with immunomagnetic beads was used to isolate strains of Listeria monocytogenes both from pure cultures and from heterogeneous suspensions. The monoclonal antibodies used recognized all six strains of serotype 4 but only one of three strains of serotype 1. Coating procedure, incubation time, and number of immunomagnetic beads influenced the sensitivity of the isolation method. Less than 1 x 10(2) bacteria per ml in pure cultures and less than 2 x 10(2) bacteria per ml in enriched foods could be detected. The method represents a new approach to extraction and isolation of pathogenic bacteria directly from foods, after resuscitation, or from enrichment broths.
Effect of aflatoxins on rat peritoneal macrophages
Authors: Cusumano V , Costa G B , Seminara S
Published: January 2020

Phagocytosis, intracellular killing of Candida albicans, and superoxide production by rat peritoneal macrophages exposed to aflatoxins B1, B2, G1, G2, B2a, and M1 at several times and concentrations were analyzed to evaluate the intensity of a depressive effect for each mycotoxin. All aflatoxins used at very low concentrations had a depressive effect on the functions of macrophages. The biggest impairment of phagocytosis, intracellular killing, and spontaneous superoxide production was observed in macrophages exposed to aflatoxins B1 and M1.
Purification of acetoacetate decarboxylase from Clostridium acetobutylicum ATCC 824 and cloning of the acetoacetate decarboxylase gene in Escherichia coli
Authors: Petersen D J , Bennett G N
Published: January 2020

In Clostridium acetobutylicum ATCC 824, acetoacetate decarboxylase (EC 4.1.1.4) is essential for solvent production, catalyzing the decarboxylation of acetoacetate to acetone. We report here the purification of the enzyme from C. acetobutylicum ATCC 824 and the cloning and expression of the gene encoding the acetoacetate decarboxylase enzyme in Escherichia coli. A bacteriophage lambda EMBL3 library of C. acetobutylicum DNA was screened by plaque hybridization, using oligodeoxynucleotide probes derived from the N-terminal amino acid sequence obtained from the purified protein. Phage DNA from positive plaques was analyzed by Southern hybridization. Restriction mapping and subsequent subcloning of DNA fragments hybridizing to the probes localized the gene within an approximately 2.1 kb EcoRI/Bg/II fragment. A polypeptide with a molecular weight of approximately 28,000 corresponding to that of the purified acetoacetate decarboxylase was observed in both Western blots (immunoblots) and maxicell analysis of whole-cell extracts of E. coli harboring the clostridial gene. Although the expression of the gene is tightly regulated in C. acetobutylicum, it was well expressed in E. coli, although from a promoter sequence of clostridial origin.
Identification of Different
Agrobacterium
Strains Isolated from the Same Forest Nursery
Authors: Michel Marie-France , Brasileiro Ana Cristina Miranda , Depierreux Christiane , Otten Leon , Delmotte Francis , Jouanin Lise
Published: January 2020

Several
Agrobacterium
strains isolated from the same forest nursery from 1982 to 1988 were compared by serological, biochemical, and DNA-DNA hybridization methods. Similarities among strains belonging to biovar 2 were observed by indirect immunofluorescence, whereas biovar 1 strains showed serological heterogeneity. Electrophoretic analysis of bacterial envelope-associated proteins showed that few bands appeared in the strains belonging to biovar 1, whereas many proteins appeared in the case of biovar 2 strains. Chromosomal DNA was analyzed with six random C58 chromosomal fragments. None of the six probes hybridized to the DNA of the two biovar 2 strains. One of the probes gave the same hybridization pattern with all biovar 1 strains, whereas the other probes yielded different patterns. The
vir
regions were closely related in the different pathogenic strains. The T-DNA and replication regions were less conserved and showed some variations among the strains.
Identification and catabolic activity of well-derived gasoline-degrading bacteria from a contaminated aquifer
Authors: Ridgway H F , Safarik J , Phipps D , Carl P , Clark D
Published: January 2020

Approximately 300 gasoline-degrading bacteria were isolated from well water and core material from a shallow coastal aquifer contaminated with unleaded gasoline. Identification of 244 isolates revealed four genera: Pseudomonas, Alcaligenes, Nocardia, and Micrococcus, with pseudomonads making up 86.9% of bacteria identified. A total of 297 isolates was sorted into 111 catabolic groups on the basis of aerobic growth responses on 15 gasoline hydrocarbons. Each test hydrocarbon was degraded by at least one isolate. Toluene, p-xylene, ethylbenzene, and 1,2,4-trimethylbenzene were most frequently utilized as growth substrates, whereas cyclic and branched alkanes were least utilized. Most isolates were able to grow on 2 or 3 different hydrocarbons, and nearly 75% utilized toluene as a sole source of carbon and energy. Isolates were remarkably specific for hydrocarbon usage, often catabolizing only one of several closely related compounds. A subset of 220 isolates was sorted into 51 groups by polyacrylamide gel electrophoresis. Pseudomonas aeruginosa was partitioned into 16 protein-banding groups (i.e., subspecies) whose catabolic activities were largely restricted to substituted aromatics. Different members of subspecies groups defined by protein-banding pattern analysis often exhibited different growth responses on the same hydrocarbon, implying marked strain diversity. The catabolic activities of well-derived, gasoline-degrading bacteria associated with this contaminated aquifer are consonant with in situ adaptation at the site.
Characterization and Reclassification of Yeasts Used for Biological Control of Postharvest Diseases of Fruits and Vegetables
Authors: McLaughlin R. J. , Wilson C. L. , Chalutz E. , Kurtzman C. P. , Fett W. F. , Osman S. F.
Published: January 2020

In previous studies workers have shown that three yeast strains (strains US-7, 82, and 101) have biological control activity against various postharvest fungal pathogens of fruits and vegetables, including
Penicillium
rots of apples and citrus and
Botrytis
rot of apples. In these reports the researchers have described these strains as
Debaryomyces hansenii
(anamorph,
Candida famata
) or
Candida
sp. strains. In this study we performed additional physiological, DNA reassociation, and mannan characterization tests that clearly established a new taxonomic classification for these strains,
Candida guilliermondii.
We also propose amendment of the physiological test profile in the taxonomic description of
C. guilliermondii.