bluuebunny/crossref_metadata_2025 huggingface dataset:
Complementary Methods for the Differentiation of
Rhizobium meliloti
Isolates
Authors: Fuquay Janice I. , Bottomley Peter J. , Jenkins Michael B.
Published: January 2020

Because of the scarcity of literature on the successful use of serological methods for differentiation of
Rhizobium meliloti
isolates, the objectives of this study were to provide a rationale for selecting isolates to which antisera could be raised and to appraise the suitability of published methods of preparing
R. meliloti
antigens for the serological identification of field isolates. We used one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis to develop protein profiles of eight field isolates and one commercial inoculant strain of
R. meliloti
in order to choose candidates that were either identical or distinctly different from each other for the production of antisera. The serological methods of tube agglutination and gel immunodiffusion complemented the sodium dodecyl sulfate-polyacrylamide gel electrophoresis method of identification. On the basis of their agglutination titers and gel immunodiffusion analysis, the isolates were placed in five serogroups which were identical to the groupings based on protein profiles. Antigenic characteristics of gel immunodiffusion antigens were influenced by the composition of the growth medium, sonication of whole-cell antigens, and the addition of Formalin. We recommend that careful attention be given to the effects of varying antigen preparation procedures when analyzing
R. meliloti
so that experimental protocols do not complicate the results. The wide range of homologous-antiserum titers observed for the nine isolates indicates different inherent degrees of immunogenicity of
R. meliloti
which cannot be predicted before serum production. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis method is a useful tool for screening a collection of
R. meliloti
isolates to better ensure that strain-specific antisera representative of different types of organisms will be obtained.
Xylobolus frustulatus
Decay of Oak: Patterns of Selective Delignification and Subsequent Cellulose Removal
Authors: Otjen Lewis , Blanchette Robert A.
Published: January 2020

Xylobolus frustulatus
caused a distinct pocket rot in decorticated oak. Polymerization products appeared to accumulate in advance of delignified wood to form barriers to decay. Medullary ray parenchyma and earlywood vessels were not readily degraded and remained between pockets of decay. Chemical analyses indicated that 97% lignin, 96% xylose, and 69% mannose were removed from pockets of wood during incipient decay. Although 53% of the cellulose was removed from these areas, the remaining white tissues were composed of relatively pure cellulose. Hyphae became abundant as the released cellulose was subsequently removed. In the most advanced stages of decay, hyphae were absent from pockets, and only a sparse lining of crystals, found to contain a high concentration of calcium, remained.
Microscale method for rapid isolation of covalently closed circular plasmid DNA from group N streptococci
Authors: Orberg P K , Sandine W E
Published: January 2020

A method for rapid purification of plasmid DNA from lactic streptococci, utilizing microliter quantities of reagents, was developed by combination of a short lysozyme-mutanolysin cell wall digestion with a modification of the Escherichia coli plasmid isolation procedure of McMaster et al. (Anal. Biochem. 109:47-54, 1980). The preparations obtained were highly enriched for covalently closed circular DNA, and the method was applicable to plasmids of at least 40 megadaltons. Centrifugation in CsCl-ethidium bromide density gradients was not required.
Microbial Biomass and Utilization of Dissolved Organic Matter in the Okefenokee Swamp Ecosystem
Authors: Murray Robert E. , Hodson Robert E.
Published: January 2020

The Okefenokee Swamp exhibited levels of microbial biomass and aerobic glucose uptake comparable to those of other organically rich, detritus-based aquatic ecosystems. In contrast to other peat-accumulating systems, this acidic (pH 3.7), low-nutrient environment does not show diminished water column or surface sediment microbial biomass or heterotrophic activity. The total particular ATP varied between 0.03 and 6.6 μg liter
−1
(mean, 1.6 μg liter
−1
) in water and between 1 and 28 μg g (dry weight)
−1
(mean, 10.0 μg g [dry weight]
−1
in sediments. The turnover times for dissolved
d
-glucose were 1.26 to 701.25 h (mean, 110.25 h) in aerobic waters and 2.4 to 72 min (mean, 10.2 min) in aerobic surface sediments. Water column bacterial secondary production, measured as the incorporation of [
3
H]thymidine into cold-trichloroacetic acid-insoluble material, ranged from 0.06 to 1.67 nmol liter
−1
day
−1
(mean, 0.45 nmol liter
−1
day
−1
). The kinetics of
d
-glucose uptake by water column microflora are multiphasic and suggest the presence of a diverse microbial population capable of using labile substrates at nanomolar concentrations and at substantial rates. The presence of a large and active aerobic microbial community in the Okefenokee Swamp is indicative of an important role for microbes in swamp geochemistry and strongly suggests the existence of a detritus-based food web.
Significance of Algal Excretory Products for Growth of Epilimnetic Bacteria
Authors: Brock Thomas D. , Clyne Jenny
Published: January 2020

Light-stimulated uptake of
14
CO
2
and differential filtration through Nucleopore filters were used to estimate the significance of phytoplankton excretion as a source of bacterial carbon in water samples collected at different seasons of the year in Lake Mendota, Wis. On an annual basis, about 14% of the estimated bacterial production was accounted for by algal excretion, although at certain times of year the fraction of bacterial carbon derived from algal excretion was considerably higher. About 20% of the annual primary production was estimated to pass through the bacterial component.
Uptake of Metal Ions by
Rhizopus arrhizus
Biomass
Authors: Tobin J. M. , Cooper D. G. , Neufeld R. J.
Published: January 2020

Rhizopus arrhizus
biomass was found to absorb a variety of different metal cations and anions but did not absorb alkali metal ions. The amount of uptake of the cations was directly related to ionic radii of La
3+
, Mn
2+
, Cu
2+
, Zn
2+
, Cd
2+
, Ba
2+
, Hg
2+
, Pb
2+
, UO
2
2+
, and Ag
+
. The uptake of all the cations is consistent with absorption of the metals by sites in the biomass containing phosphate, carboxylate, and other functional groups. The uptake of the molybdate and vanadate anions was strongly pH dependent, and it is proposed that the uptake mechanism involves electrostatic attraction to positively charged functional groups.
Microbial Degradation of Alkyl Carbazoles in Norman Wells Crude Oil
Authors: Fedorak Phillip M. , Westlake Donald W. S.
Published: January 2020

Norman Wells crude oil was fractionated by sequential alumina and silicic acid column chromatography methods. The resulting nitrogen-rich fraction was analyzed by gas chromatography-mass spectrometry and showed 26 alkyl (C
1
to C
5
) carbazoles to be the predominant compounds. An oil-degrading mixed bacterial culture was enriched on carbazole to enhance its ability to degrade nitrogen heterocycles. This culture was used to inoculate a series of flasks of mineral medium and Norman Wells crude oil. Residual oil was recovered from these cultures after incubation at 25°C for various times. The nitrogen-rich fraction was analyzed by capillary gas chromatography, using a nitrogen-specific detector. Most of the C
1
-, C
2
-, and C
3
- carbazoles and one of the C
4
-isomers were degraded within 8 days. No further degradation occurred when incubation was extended to 28 days. The general order of susceptibility of the isomers to biodegradation was C
1
> C
2
> C
3
> C
4
. The carbazole-enriched culture was still able to degrade
n
-alkanes, isoprenoids, aromatic hydrocarbons, and sulfur heterocycles in the crude soil.
Quantitative Method for Colorimetric Determination of Formate in Fermentation Media
Authors: Sleat Robert , Mah Robert A.
Published: January 2020

The effects of fermentation products and media supplements on a colorimetric assay for formate were evaluated. Formate was detected at concentrations as low as 0.5 mM in fermentation media.
Characterization of the cellulolytic activity of a Bacillus isolate
Authors: Robson L M , Chambliss G H
Published: January 2020

A group I Bacillus strain, DLG, was isolated and characterized as being most closely related to Bacillus subtilis. When grown on any of a variety of sugars, the culture supernatant of this isolate was found to possess cellulolytic activity, as demonstrated by degradation of trinitrophenyl-carboxymethyl cellulose. Growth in medium containing cellobiose or glucose resulted in the greatest production of cellulolytic activity. The cellulolytic activity was not produced until the stationary phase of growth, and the addition of glucose or cellobiose to a culture in this phase had no apparent effect on enzyme production. Fractionation of the culture supernatant showed that the molecular weight of the enzymatic activity was less than 100,000. Maximum cellulolytic activity in assays was observed at pH 4.8 and at 58C, although maximum thermal stability of the activity. Kinetic experiments suggested that more than one enzyme was acting upon trinitrophenyl-carboxymethyl cellulose. Exocellular protein produced by this Bacillus isolate showed roughly one-fifth the cellulolytic activity displayed by Trichoderma reesei C30 on noncrystalline, cellulosic substrates. In contrast to T. reesei cellulase, the Bacillus enzymatic activity showed no ability to degrade crystalline forms of cellulose, nor was cellobiase activity detectable.
Rapid enumeration of Staphylococcus aureus in foods by direct demonstration of enterotoxigenic colonies on membrane filters by enzyme immunoassay
Authors: Peterkin P I , Sharpe A N
Published: January 2020

Based on enzyme-linked immunosorbent assay, a convenient method has been devised for the direct demonstration of enterotoxin B production by Staphylococcus aureus colonies grown for 24 h on membrane filters. The problem of false-positive reactions due to binding of immunoglobulin G to protein A was turned to advantage by conjugating horseradish peroxidase directly to protein A, which then mediated the labeling of the antitoxin. The test requires 3 h to complete and yields a purple stain at the site of enterotoxin B-producing colonies, thus allowing direct enumeration of confirmed S. aureus in foods within 27 h. The method should be applicable to other enterotoxins of S. aureus.
Dependence of Betaine Stimulation of Vitamin B
12
Overproduction on Protein Synthesis
Authors: Fa You-Hua , Kusel J. Peter , Demain Arnold L.
Published: January 2020

The betaine-stimulated differential synthesis of vitamin B
12
, i.e., the increase in B
12
per increase in dry cell weight, by
Pseudomonas denitrificans
was inhibited by rifampin and chloramphenicol but not by benzylpenicillin and carbenicillin at concentrations of antibiotic that inhibit growth. The level of the first enzyme of corrin (and porphyrin) biosynthesis, δ-aminolevulinic acid synthetase, was decreased to a much greater degree by rifampin and chloramphenicol than by the penicillins. These data support the concept that betaine stimulation of B
12
synthesis is a result of its stimulation of synthesis of δ-aminolevulinic acid synthetase, a labile and presumably rate-limiting enzyme of corrin formation requiring continuous induction. In further support of this hypothesis, it was found that chloramphenicol immediately interfered with both vitamin B
12
and δ-aminolevulinic acid synthetase formation, no matter when it was added to the system.
Interaction of
Rhizobium
sp. with Toxin-Producing Fungus in Culture Medium and in a Tropical Soil
Authors: Habte Mitiku , Barrion Melinda
Published: January 2020

Experiments were conducted to determine the influence of a toxin-producing fungus on a rhizobial population in yeast-mannitol medium and in a tropical soil. The fungus, which was isolated from a highly weathered soil (Tropeptic Eutrustox), was identified as a
Metarhizum
sp. The density of rhizobial populations established in yeast-mannitol medium in the absence of the fungus was 10
5
times higher than that established in its presence. However, the fungus did not exert similar antagonistic influence on the rhizobial population incubated with it in the sterilized test soil. Rhizobial growth activity in yeast-mannitol medium was also insensitive to the presence of the fungus when the medium was amended with 1% (wt/vol) kaolinite or montmorillonite. The results suggest that clay minerals may be responsible for protecting rhizobia against toxin-producing fungi in soil.
Effect of radiation and freezing on [3H]DNA of Yersinia enterocolitica
Authors: Grecz N , El-Zawahry Y A
Published: January 2020

Freezing of the enteropathogenic bacterium Yersinia enterocolitica to -18 and -75 degrees C caused 7 and 42% cell death, respectively, and 0.329 and 0.588 single-strand breaks per 10(8) daltons of DNA, respectively, while radiation to one D10 dose (10% cell survival) combined with freezing to 2 to 0, -18, and -75 degrees C induced 0.05, 0.75, and 5.04 single-strand breaks, respectively. The increase in the effectiveness of radiation with respect to the yield of single-strand breaks at -18 and -75 degrees C is contrary to expectation and seems to be due to arrest of repair of single-strand breaks by these low temperatures.
Relationship Between Substrate Concentration and Fermentation Product Ratios in
Clostridium thermocellum
Cultures
Authors: Brener David , Johnson Byron F.
Published: January 2020

Growth of
Clostridium thermocellum
in batch cultures was studied over a broad range of cellobiose concentrations. Cultures displayed important differences in their substrate metabolism as determined by the end product yields. Bacterial growth was severely limited when the initial cellobiose concentration was 0.2 (wt/vol), was maximal at substrate concentrations between 0.5 and 2.0%, and did not occur at 5.0% cellobiose. Ethanol accumulated maximally (38.3 μmol/10
9
cells) in cultures with an initial cellobiose concentration of 0.8%, whereas cultures in 2.0% cellobiose accumulated only 17.3 μmol, and substrate-limited cultures (0.2% cellobiose) accumulated little, if any, ethanol beyond that initially detected (8.3 μmol/10
9
cells). In a medium with 0.8% cellobiose, ethanol was produced at a constant rate of approximately 1.1 μmol/10
9
cells per h from late-logarithmic phase (16 h) of growth well into stationary phase (44 h). When ethanol was added exogenously at levels more than twice the maximum produced by the cultures themselves (0.5% [vol/vol]), neither the extent of growth (maximum Klett units, 150) nor the amounts of ethanol produced (∼0.17%) by the culture was affected. The ratio of ethanol to acetate was highest (2.8) when cells were grown in 0.8% cellobiose and lowest (1.2) when cells were grown in 0.2% cellobiose.
Removal of Cadmium by Microorganisms in a Two-Stage Chemostat
Authors: Houba C. , Remacle J.
Published: January 2020

A two-stage chemostat was used to study removal of cadmium by microorganisms in continuous culture. The medium was contaminated with 0.8 mg of Cd per liter. At 20°C, most of the microbial biomass formed aggregates which settled in the second stage of the chemostat. Effluent was free of bacteria. Up to 80% of the metal contained in the inlet flux was removed by the biomass, with 20% remaining in solution. At 10°C and with a shorter retention time, flocculation was poorer and metal removal by settling biomass did not exceed 35%.
Fine Structure of Succinate-Swollen
Rhizobium trifolii
0403
Authors: Urban James E. , Bechtel Donald B.
Published: January 2020

Transmission electron micrographs of glutaraldehyde- OsO
4
-fixed
Rhizobium trifolii
0403 before and after cells were treated with 16.6 mM succinate showed that treated cells increased in mass by increasing cytoplasmic volume. The morphology of succinate-treated cells was identical to that of bacteroids, and the appearances of the envelope and periplasmic space were similar. The primary difference was in inclusion number and type.
Charge-shift electrophoretic behavior of T-2 toxin in agarose gels
Authors: Gyongyossy-Issa M I , Christie E J , Khachatourians G G
Published: January 2020

We report the use of charge-shift electrophoresis to define the behavior of the trichothecene mycotoxin T-2 in aqueous solutions. We found that T-2 behaves in a hydrophobic manner and that this technique can be adapted for the separation of small hydrophobic molecules such as T-2 and cholesterol.
Direct Counting of Bacteria Preserved with Lugol Iodine Solution
Authors: Pomroy A. J.
Published: January 2020

Lugol iodine solution was compared with glutaraldehyde as a preservative for marine bacteria. Direct counts with the fluorochrome 4′,6-diamidino-2-phenylindole show no significant difference between the preservatives, but the use of Lugol solution has several advantages over glutaraldehyde, especially in the handling and storage of samples. Bacteria were counted in water samples that were preserved with Lugol iodine solution and stored at room temperature for 4 years. Microprotozoa were also counted in samples preserved with Lugol iodine solution by using the fluorochrome fluorescein isothiocyanate.
Virus transport and survival after land application of sewage sludge
Authors: Bitton G , Pancorbo O C , Farrah S R
Published: January 2020

The survival and transport patterns of poliovirus 1 and echovirus 1 were studied in undisturbed soil cores which were treated with digested sludge and exposed to natural weather conditions prevailing in north central Florida. It was shown that, under those experimental conditions, enteroviruses are relatively rapidly inactivated in the soil. A more rapid virus decline was observed during the warm and dry fall season than during the warm and wet summer season. The monitoring of soil core leachates has shown that both viruses were effectively retained by the sludge-treated soil.
Comparison of methods for recovery of Escherichia coli and Staphylococcus aureus from seeded laundry fabrics
Authors: Cody H J , Smith P F , Blaser M J , LaForce F M , Wang W L
Published: January 2020

To assess the effect of laundry procedures on fabric-associated bacteria, a standard method of enumeration is needed. We evaluated six methods for enumeration of Escherichia coli and Staphylococcus aureus seeded (10(2) and 10(5) CFU/100 cm2 of fabric area) onto sterilized hospital sheets and terry . Two methods involved maceration of seeded swatches in broth followed by passage of the broth through a 0.45-micron-pore-size, 47-mm-diameter filter membrane. Three methods involved agitation of seeded swatches in broth with a paint shaker and membrane filtration of the broth to recover eluted bacterial cells, and the final method involved direct enumeration of cells on fabrics by overlaying seeded swatches with agar containing triphenyltetrazolium chloride as an indicator. The most convenient recovery method employed a 90-s agitation followed by serial dilution of broths and membrane filtration. This method provided 44/57% (low seed/high seed) recovery of E. coli from sheets and 133/31% from terry and 34/74% recovery of S. aureus from sheets and 58/57% from terry . Although maceration provided similar recovery of E. coli and S. aureus, it is a less-practical method. The direct enumeration method was ineffective for enumerating gram-positive bacteria. We conclude that either the agitation or maceration method used enumerated the seeded bacteria to within 1 log10 of their expected number and can be used to assess the bactericidal effectiveness of various steps in the laundering process.
Phage Resistance in a Phage-Insensitive Strain of
Streptococcus lactis
: Temperature-Dependent Phage Development and Host-Controlled Phage Replication
Authors: Sanders Mary E. , Klaenhammer Todd R.
Published: January 2020

Streptococcus lactis
ME2 is a dairy starter strain that is insensitive to a variety of phage, including φ18. The efficiency of plating of φ18 on ME2 and N1 could be increased from <1 × 10
−9
to 5.0 × 10
−2
and from 7.6 × 10
−7
to 2.1 × 10
−2
, respectively, when the host strains were subcultured at 40°C before plating the phage and the phage assay plates were incubated at 40°C. Host-dependent replication was demonstrated in N1 at 30°C and in N1 and ME2 at 40°C, suggesting the operation of a temperature-sensitive restriction and modification system in ME2 and N1. The increased sensitivity of ME2 and N1 to φ18 at 40°C was also demonstrated by lysis of broth cultures and increased plaque size. ME2 grown at 40°C showed an increased ability to adsorb φ18, indicating a second target for temperature-dependent phage sensitivity in ME2. Challenge of N1 with a φ18 preparation that had been previously modified for growth on N1 indicated that at 40°C phage development was characterized by a shorter latent period and larger burst size than at 30°C. The evidence presented suggests that the high degree of phage insensitivity expressed by ME2 consists of a variety of temperature-sensitive mechanisms, including (i) the prevention of phage adsorption, (ii) host-controlled restriction of phage, and (iii) suppression of phage development. At 30°C these factors appear to act cooperatively to prevent the successful emergence of lytic phage active against
S. lactis
ME2.
Anaerobic Biodegradation of the Lignin and Polysaccharide Components of Lignocellulose and Synthetic Lignin by Sediment Microflora
Authors: Benner Ronald , Maccubbin A. E. , Hodson Robert E.
Published: January 2020

Specifically radiolabeled [
14
C-lignin]lignocelluloses and [
14
C-polysaccharide]lignocelluloses were prepared from a variety of marine and freshwater wetland plants including a grass, a sedge, a rush, and a hardwood. These [
14
C]lignocellulose preparations and synthetic [
14
C]lignin were incubated anaerobically with anoxic sediments collected from a salt marsh, a freshwater marsh, and a mangrove swamp. During long-term incubations lasting up to 300 days, the lignin and polysaccharide components of the lignocelluloses were slowly degraded anaerobically to
14
CO
2
and
14
CH
4
. Lignocelluloses derived from herbaceous plants were degraded more rapidly than lignocellulose derived from the hardwood. After 294 days, 16.9% of the lignin component and 30.0% of the polysaccharide component of lignocellulose derived from the grass used (
Spartina alterniflora
) were degraded to gaseous end products. In contrast, after 246 days, only 1.5% of the lignin component and 4.1% of the polysaccharide component of lignocellulose derived from the hardwood used (
Rhizophora mangle
) were degraded to gaseous end products. Synthetic [
14
C]lignin was degraded anaerobically faster than the lignin component of the hardwood lignocellulose; after 276 days, 3.7% of the synthetic lignin was degraded to gaseous end products. Contrary to previous reports, these results demonstrate that lignin and lignified plant tissues are biodegradable in the absence of oxygen. Although lignocelluloses are recalcitrant to anaerobic biodegradation, rates of degradation measured in aquatic sediments are significant and have important implications for the biospheric cycling of carbon from these abundant biopolymers.
Alcoholic Fermentation of
d
-Xylose by Yeasts
Authors: Toivola Ansa , Yarrow David , van den Bosch Eduard , van Dijken Johannes P. , Scheffers W. Alexander
Published: January 2020

Type strains of 200 species of yeasts able to ferment glucose and grow on xylose were screened for fermentation of
d
-xylose. In most of the strains tested, ethanol production was negligible. Nineteen were found to produce between 0.1 and 1.0 g of ethanol per liter. Strains of the following species produce more than 1 g of ethanol per liter in the fermentation test with 2% xylose:
Brettanomyces naardenensis, Candida shehatae, Candida tenuis, Pachysolen tannophilus, Pichia segobiensis
, and
Pichia stipitis.
Subsequent screening of these yeasts for their capacity to ferment
d
-cellobiose revealed that only
Candida tenuis
CBS 4435 was a good fermenter of both xylose and cellobiose under the test conditions used.
Association of metal tolerance with multiple antibiotic resistance of bacteria isolated from drinking water
Authors: Calomiris J J , Armstrong J L , Seidler R J
Published: January 2020

Bacterial isolates from the drinking water system of an Oregon coastal community were examined to assess the association of metal tolerance with multiple antibiotic resistance. Positive correlations between tolerance to high levels of Cu2+, Pb2+, and Zn2+ and multiple antibiotic resistance were noted among bacteria from distribution waters but not among bacteria from raw waters. Tolerances to higher levels of Al3+ and Sn2+ were demonstrated more often by raw water isolates which were not typically multiple antibiotic resistant. A similar incidence of tolerance to Cd2+ was demonstrated by isolates of both water types and was not associated with multiple antibiotic resistance. These results suggest that simultaneous selection phenomena occurred in distribution water for bacteria which exhibited unique patterns of tolerance to Cu2+, Pb2+, and Zn2+ and antibiotic resistance.
Seasonal variations of Vibrio cholerae (non-O1) isolated from California coastal waters
Authors: Kenyon J E , Piexoto D R , Austin B , Gillies D C
Published: January 2020

This report compares recovery of non-O1 Vibrio cholerae strains from seven California coastal sites during the winter and summer of 1983. A total of 41 identified and 27 presumptive nn-O1 V. cholerae strains were recovered from six of seven coastal sites in the summer. A 5-to 56-fold increase in the numbers of organisms isolated from different sites occurred in the summer months, when water temperatures were 1.9 to 5.1 degrees C higher. At the three sites where the highest levels of non-O1 V. cholerae were found, pollution, as measured by the total number of coliforms, exceeded the legal limit (less than 1,000 coliforms per 100 ml.).
Inhibition of Alcoholic Fermentation of Grape Must by Fatty Acids Produced by Yeasts and Their Elimination by Yeast Ghosts
Authors: Lafon-Lafourcade S. , Geneix C. , Ribéreau-Gayon P.
Published: January 2020

In a complete nutritive medium rich in sugar, such as grape must, the inhibition of alcoholic fermentation is caused by substances produced by the yeast which, acting synergistically with ethanol, are toxic to the yeasts themselves. Among these are decanoic and octanoic acids and their corresponding ethyl esters. Their adsorption by yeast ghosts permits the prevention and treatment of fermentation stoppages.
Comparison of antigenicity of toxins produced by Clostridium botulinum type C and D strains
Authors: Ochanda J O , Syuto B , Oguma K , Iida H , Kubo S
Published: January 2020

C1 neurotoxin of Clostridium botulinum strains C-Stockholm (C-ST), C beta-Yoichi, C-468, CD6F, and C-CB19 and type D toxin of strains D-1873 and D-CB16 were purified by gel filtration, ion exchange, and affinity chromatographies. The purified toxins had di-chain structure made of heavy and light chains. The toxins of C beta-Yoichi, C-468, CD6F, and C-CB19 reacted with anti-C-ST heavy chain and anti-C-ST light chain in immunodiffusion tests and enzyme-linked immunosorbent assay, whereas D-CB16 toxin reacted with anti-D-1873 heavy chain and anti-D-1873 light chain. However, C-6813 toxin reacted with anti-D-1873 heavy chain and anti-C-ST light chain but not with anti-C-ST heavy chain or anti-D-1873 light chain immunoglobulin G. These results indicate common antigens in the heavy chains of C-6813 and D-1873 toxins and in the light chains of C-6813 and C-ST toxins. Further, they provide evidence for heterogeneity within type C1 toxin subunits.
Selective Inhibition by 2-Bromoethanesulfonate of Methanogenesis from Acetate in a Thermophilic Anaerobic Digestor
Authors: Zinder S. H. , Anguish T. , Cardwell S. C.
Published: January 2020

The effects of 2-bromoethanesulfonate, an inhibitor of methanogenesis, on metabolism in sludge from a thermophilic (58°C) anaerobic digestor were studied. It was found from short-term experiments that 1 μmol of 2-bromoethanesulfonate per ml completely inhibited methanogenesis from
14
CH
3
COO
−
, whereas 50 μmol/ml was required for complete inhibition of
14
CO
2
reduction. When 1 μmol of 2-bromoethanesulfonate per ml was added to actively metabolizing sludge which was then incubated for 24 h. it caused a 60% reduction in methanogenesis and a corresponding increase in acetate accumulation; at 50 μmol/ml it caused complete inhibition of methanogenesis and accumulation of acetate. H
2
, and ethanol.
Isolation of
Streptococcus lactis
Bacteriophages and Their Interaction with the Host Cell
Authors: Parada José L. , La Vía María I. , Solari Alberto J.
Published: January 2020

Phages may cause lysis of lactic acid bacteria used in cheese production. Three virulent bacteriophages specific for
Streptococcus lactis
subsp.
lactis
C2 were isolated and purified from cheese whey. They showed distinct plaque sizes, and although they had similar morphology by electron microscope examination, their dimensions were slightly different. The phage heads were elongated and hexagonal in shape, and the flexible tails appeared periodically cross-striated. They were DNA phages based on the acridine orange test. On infection, phage was adsorbed on the bacterial surface by the free end of the tail. After 80 min of incubation at 25°C, the phage heads appeared empty, slightly collapsed, and possessed a visible hollow tube through which the genetic material had been injected.
Bacterial oxidation of the polycyclic aromatic hydrocarbons acenaphthene and acenaphthylene
Authors: Schocken M J , Gibson D T
Published: January 2020

A Beijerinckia sp. and a mutant strain, Beijerinckia sp. strain B8/36, were shown to cooxidize the polycyclic aromatic hydrocarbons acenaphthene and acenaphthylene. Both organisms oxidized acenaphthene to the same spectrum of metabolites, which included 1-acenaphthenol, 1-acenaphthenone, 1,2-acenaphthenediol, acenaphthenequinone, and a compound that was tentatively identified as 1,2-dihydroxyacenaphthylene. In contrast, acenaphthylene was oxidized to acenaphthenequinone and the compound tentatively identified as 1,2-dihydroxyacenaphthylene by the wild-type strain of Beijerinckia. Both of these products were also formed when the organism was incubated with synthetic cis-1,2-acenaphthenediol. A metabolite identified as cis-1,2-acenaphthenediol was formed from acenaphthylene by the mutant Beijerinckia sp. strain B8/36. Cell extracts prepared from the wild-type Beijerinckia strain contain a constitutive pyridine nucleotide-dependent dehydrogenase which can oxidize 1-acenaphthenol and 9-fluorenol. The results indicate that although acenaphthene and acenaphthylene are both oxidized to acenaphthenequinone, the pathways leading to the formation of this end product are different.
Mixed-Culture Fermentor for Simulating Methanogenic Digestors
Authors: Boone David R.
Published: January 2020

Propionate degradation in an anaerobic digestor degrading animal waste (10-day retention time, 5.75 g liter
−1
day
−1
volatile solids loading rate, 40°C) was 0.304 mM h
−1
, measured with [2-
14
C]propionate; this value indicated that CH
4
produced from propionate accounted for 14.8% of the CH
4
produced in the digestor (34.5%, including acetate produced from propionate). The mean propionate concentration was 0.67 mM, giving a propionate turnover rate of 0.46 h
−1
. A continuous-, mixed-culture fermentor was developed to mimic the digestor. When degradation rates of methanogenic precursors (H
2
, CO
2
, and acetate) equalled those measured in the digestor, propionate degradation was inhibited. When the H
2
turnover rate was lowered by decreasing addition of H
2
-generating substrates or by allowing a portion of the H
2
degradation to occur in an isolated compartment, propionate degradation in the fermentor resumed. The possibility is discussed that in digestors, much of the H
2
is produced and degraded within microenvironments associated with particles. Thus, the gross turnover rate of H
2
measured in digestors is an average, and specific microenvironments within the digestor may have different rates of turnover.
Light and Electron Microscopic Examinations of Methane-Producing Biofilms from Anaerobic Fixed-Bed Reactors
Authors: Robinson Ralph W. , Akin Debra E. , Nordstedt Roger A. , Thomas Michael V. , Aldrich Henry C.
Published: January 2020

Ultrastructural examinations were performed on biofilms from eight anaerobic fixed-bed reactors filled with various packing materials and operated on fresh swine waste. By using light, UV, scanning, and transmission electron microscopy, the distribution of a diverse microbial population composed of bacteria and a few yeasts was determined. This is the first time that the ultrastructure of in situ anaerobic digestor biofilms has been reported. A large number of methanogenic bacteria were identified by their fluorescence under 420 nm of radiation. Of these, two morphologically distinct types were most prevalent in the films.
Methanothrix
spp. was present in high numbers at the film surface, whereas
Methanosarcina
spp. were commonly embedded in the lower regions of the film. Inhabitants of the film were surrounded by an exopolysaccharide matrix that was very dense toward the base. An extensive network of channels was observed throughout the matrix that may facilitate gas and nutrient exchange to the lower regions of the film.
Role of DNase in recovery of plasmid DNA from Clostridium perfringens
Authors: Blaschek H P , Klacik M A
Published: January 2020

Recovery of plasmid DNA from Clostridium perfringens 10543A and 3626B cleared lysates was significantly improved by the addition of 0.2% (vol/vol) diethylpyrocarbonate (DEP) before protoplast disruption in the cleared lysate protocol. Three previously undetected, large-molecular-mass plasmids (45.2, 51.9, and 68.2 megadaltons) were isolated from modified DEP-treated cleared lysates of C. perfringens 3626B. Two plasmids (9.4 and 30 megadaltons) were recovered from C. perfringens 10543A modified DEP-treated cleared lysates which previously required dye-buoyant density gradient centrifugation for visualization on agarose gels. Unsuccessful attempts to isolate plasmid DNA from Brij 58 cleared lysates of extracellular DNase-negative mutants of C. perfringens suggested the deleterious DNase activity was not extracellular. Cellular localization studies indicated that the cell wall-compartmentalized cell fraction contained 72.2% of the total DNase activity, whereas the extracellular and intracellular fractions demonstrated much less (26.8 and 1.0%, respectively). Cleared lysates prepared with DEP demonstrated much less DNase activity than cleared lysates prepared without DEP. The variable and irreproducible recovery of plasmid DNA from C. perfringens cleared lysates was attributed to cell wall-compartmentalized DNase.
Interaction of
Pseudomonas solanacearum
with Suspension-Cultured Tobacco Cells and Tobacco Leaf Cell Walls In Vitro
Authors: Duvick Jonathan P. , Sequeira Luis
Published: January 2020

Attachment of radiolabeled
Pseudomonas solanacearum
cells to suspension-cultured tobacco cells and tobacco leaf cell walls was measured in vitro by a filtration technique that allowed separation of attached and unattached bacteria. An avirulent strain (B1) attached more rapidly to suspension-cultured cells than did the virulent parent strain (K60), and B1 attachment was less sensitive to inhibition by high ionic strength than was K60. Attachment of B1 bacteria to suspension-cultured cells and to leaf cell walls was comparable (50 to 70%), but only a small proportion (10 to 20%) of K60 bacteria attached to leaf cell walls under optimal conditions. With high bacterial populations (10
8
bacteria per ml), attachment of K60 to suspension-cultured cells was greatly reduced. Attachment of both strains was completely inhibited by pretreating bacterial cells with heat (41°C) or azide and was partially inhibited by EDTA and kanamycin. The mechanism of attachment is not known, but ionic forces may be involved.
Effect of carbon monoxide on fermentation of fiber, starch, and amino acids by mixed rumen microorganisms in vitro
Authors: Russell J B , Jeraci J L
Published: January 2020

When 1 atm (101.3 kPa) of carbon monoxide was added to mixed rumen bacterial incubations containing timothy hay, methane production was inhibited by 88% without an increase in hydrogen. The molar ratio of propionate to acetate increased from 0.83 to 1.53, extracellular ammonia declined from 5.2 to 2.4 mM, and hemicellulose and cellulose digestions were inhibited by 40 and 27%, respectively. Even low levels of carbon monoxide (less than 0.1 atm [10.13 kPa]) significantly changed the products of fermentation. With starch, methane production was once again inhibited, but the magnitude of starch fermentation was unaffected. Decrease in acetate was accompanied by an equal molar increase in lactate. Ammonia production from the amino acid source, Trypticase, declined 20% as carbon monoxide was increased to 1.0 atm, and 93% of this decrease was explained by a selective inhibition of branched-chain amino acid fermentation.
Ferrous Iron Oxidation by
Thiobacillus ferrooxidans
: Inhibition with Benzoic Acid, Sorbic Acid, and Sodium Lauryl Sulfate
Authors: Onysko Steven J. , Kleinmann Robert L. P. , Erickson Patricia M.
Published: January 2020

Benzoic acid, sorbic acid, and sodium lauryl sulfate at low concentrations (5 to 10 mg/liter) each effectively inhibited bacterial oxidation of ferrous iron in batch cultures of
Thiobacillus ferrooxidans.
The rate of chemical oxidation of ferrous iron in low-pH, sterile batch reactors was not substantially affected at the tested concentrations (5 to 50 mg/liter) of any of the compounds.
Peat Hydrolysate Medium Optimization for Pullulan Production
Authors: Boa Jacques M. , LeDuy Anh
Published: January 2020

Peat hydrolysate, a diluted acid-autoclaved extract of peat, was used as a substrate for the production of the extracellular polysaccharide pullulan by three strains of
Aureobasidium pullulans
, 140B, 142, and 2552. It was found that the addition of (NH
4
)
2
SO
4
and K
2
HPO
4
as sources of nitrogen and phosphate, respectively, is not necessary for the polysaccharide production. The economically optimized culture medium for large-scale production of pullulan contains peat hydrolysate, 0.05% NaCl, 0.02% MgSO
4
, and 0.01% antifoam FG-10. The initial pH of peat hydrolysate medium is adjusted to its optimum value of 6.0 with Ca(OH)
2
. The total ingredient cost for the production of each kilogram of pullulan with optimized medium is only 1/10 of that with the nonoptimized medium. In this study, a zero cost for peat hydrolysate was assumed, since it is an effluent of the peat and peat processing industries.
Stabilization of a histidine-producing strain of Serratia marcescens
Authors: Sugiura M , Kisumi M
Published: January 2020

A decrease in histidine productivity was observed during subculture of a histidine-producing strain of Serratia marcescens. The decrease was accompanied by an increase in the number of wild-type revertants. Adenine accelerated the growth of producing strain HT-2892 to nearly equal that of revertants, and histidine production was stable because the depletion of ATP in strain HT-2892 was restored by adenine. To increase the intracellular ATP content, mutants resistant to 6-methylpurine, an antagonist of adenine, were isolated from strain HT-2892. 6-Methylpurine-resistant mutant MPr90 grew more rapidly than the parent producing strain and produced L-histidine stably, even when it was subjected to subculture in medium without adenine. ATP depletion was restored in strain MPr90, probably owing to the derepression of adenylosuccinate synthetase in AMP biosynthesis.
Growth Kinetics of
Thiobacillus ferrooxidans
Isolated from Arsenic Mine Drainage
Authors: Braddock Joan Forshaug , Luong Huan V. , Brown Edward J.
Published: January 2020

Thiobacillus ferrooxidans
is found in many Alaskan and Canadian drainages contaminated by metals dissolved from placer and lode gold mines. We have examined the iron-limited growth and iron oxidation kinetics of a
T. ferrooxidans
isolate, AK1, by using batch and continuous cultures. Strain AK1 is an arsenic-tolerant isolate obtained from placer gold mine drainage containing large amounts of dissolved arsenic. The steady-state growth kinetics are described with equations modified for threshold ferrous iron concentrations. The maximal specific growth rate (μ
max
) for isolate AK1 at 22.5°C was 0.070 h
−1
, and the ferrous iron concentration at which the half-maximal growth rate occurred (
K

μ

) was 0.78 mM. Cell yields varied inversely with growth rate. The iron oxidation kinetics of this organism were dependent on biomass. We found no evidence of ferric inhibition of ferrous iron oxidation for ferrous iron concentrations between 9.0 and 23.3 mM. A supplement to the ferrous medium of 2.67 mM sodium arsenite did not result in an increased steady-state biomass, nor did it appear to affect the steady-state growth kinetics observed in continuous cultures.
Effects of Cadmium on Aquatic Hyphomycetes
Authors: Abel T. H. , Bärlocher F.
Published: January 2020

Two kinds of experiments, sporulation and growth experiments, were carried out to demonstrate the effect of cadmium on aquatic hyphomycetes. Oak (
Quercus petraea
L.) leaves were exposed in a hard-water stream (Lüssel, Swiss Jura) and a soft-water stream (Ibach, Black Forest) for 2 months. In the laboratory, fungal sporulation on the leaves in stream water enriched with cadmium (as CdCl
2
) was studied. A measurable effect was found when the cadmium concentration exceeded 0.1 ppm (0.1 mg/liter). Concentrations higher than 100 ppm inhibited conidium production completely. This toxic effect of cadmium was species dependent and much higher in soft water (water with low concentrations of calcium and magnesium) than in hard water. Growth experiments with
Alatospora acuminata
Ingold,
Clavariopsis aquatica
De Wildeman,
Flagellospora curvula
Ingold,
Heliscus lugdunensis
Saccardo and Therry, and
Tetracladium marchalianum
De Wildeman showed the same pattern of cadmium sensitivity as that seen in the sporulation experiments. Mycelial growth was less sensitive to cadmium than was fungal sporulation. High concentrations of competing cations (e.g., calcium and zinc) or potential ligands could reduce cadmium toxicity. Calcium content seems to be the most important factor responsible for the different sensitivity of aquatic hyphomycetes in hard and soft water.
Plasmid transformation of Streptococcus lactis protoplasts: optimization and use in molecular cloning
Authors: Kondo J K , McKay L L
Published: January 2020

The parameters affecting polyethylene glycol-induced plasmid transformation of Streptococcus lactis LM0230 protoplasts were examined to increase the transformation frequency. In contrast to spreading protoplasts over the surface of an agar medium, their incorporation into soft agar overlays enhanced regeneration of protoplasts and eliminated variability in transformation frequencies. Polyethylene glycol with a molecular weight of 3,350 at a final concentration of 22.5% yielded optimal transformation. A 20-min polyethylene glycol treatment of protoplasts in the presence of DNA was necessary for maximal transformation. The number of transformants recovered increased as the protoplast and DNA concentration increased over a range of 3.0 X 10(6) to 3.0 X 10(8) protoplasts and 0.25 to 4.0 micrograms of DNA per assay, respectively. With these parameters, transformation was increased to 5 X 10(3) to 4 X 10(4) transformants per microgram of DNA. Linear and recombinant plasmid DNA transformed, but at frequencies 10- to 100-fold lower than that of covalently closed circular DNA. Transformation of recombinant DNA molecules enabled the cloning of restriction endonuclease fragments coding for lactose metabolism into S. lactis LM0230 with the Streptococcus sanguis cloning vector, pGB301. These results demonstrated that the transformation frequency is sufficient to clone plasmid-coded genes which should prove useful for strain improvement of dairy starter cultures.
Fermentation of Cellodextrins by Different Yeast Strains
Authors: Gondé Pierre , Blondin Bruno , Leclerc Marc , Ratomahenina Robert , Arnaud Alain , Galzy Pierre
Published: January 2020

The fermentation of cellodextrins by eight yeast species capable of fermenting cellobiose was monitored. Only two of these species,
Torulopsis molischiana
and
T. wickerhamii
, were able to ferment β-glucosides with a degree of polymerization between one and six. These two species showed exocellular β-glucosidase activity. Four other species were able to ferment cellotriose, and the last two species only fermented cellobiose. These latter six species produced a β-glucosidase capable of attacking cellodextrins, but this enzyme was endocellular.
Microelectrode Studies of Interstitial Water Chemistry and Photosynthetic Activity in a Hot Spring Microbial Mat
Authors: Revsbech Niels P. , Ward David M.
Published: January 2020

Microelectrodes were used to measure oxygen, pH, and oxygenic photosynthetic activity in a hot spring microbial mat (Octopus Spring, Yellowstone National Park), where the cyanobacterium
Synechococcus lividus
and the filamentous bacterium
Chloroflexus aurantiacus
are the only known phototrophs. The data showed very high biological activities in the topmost layers of the microbial mat, resulting in extreme values for oxygen and pH. At a 1-mm depth at a 55°C site, oxygen and pH reached 900 μM and 9.4, respectively, just after solar noon, whereas anoxic conditions with a pH of 7.2 were measured before sunrise. Although diurnal changes between these extremes occurred over hours during a diurnal cycle, microbial activity was great enough to give the same response in 1 to 2 min after artificial shading. Oxygenic photosynthesis was confined to a 0.5- to 1.1-mm layer at sites with temperatures at or above about 50°C, with maximum activities in the 55 to 60°C region. The data suggest that
S. lividus
is the dominant primary producer of the mat.
Evidence for the role of copper in the injury process of coliform bacteria in drinking water
Authors: Domek M J , LeChevallier M W , Cameron S C , McFeters G A
Published: January 2020

Low levels of copper in chlorine-free distribution water caused injury of coliform populations. Monitoring of 44 drinking water samples indicated that 64% of the coliform population was injured. Physical and chemical parameters were measured, including three heavy metals (Cu, Cd, and Pb). Copper concentrations were important, ranging from 0.007 to 0.54 mg/liter. Statistical analyses of these factors were used to develop a model to predict coliform injury. The model predicted almost 90% injury with a copper concentration near the mean observed value (0.158 mg/liter) in distribution waters. Laboratory studies with copper concentrations of 0.025 and 0.050 mg/liter in an inorganic carbon buffer under controlled conditions of temperature and pH caused over 90% injury within 6 and 2 days, respectively. Studies of the metabolism of injured Escherichia coli cells indicated that the respiratory chain is at least one site of damage in injured cells.