bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of Biphenyl and Polychlorinated Biphenyl Metabolism in Soil
Authors: Focht D. D. , Brunner W.
Published: January 2020

The metabolism of
14
C-labeled PCBs (polychlorinated biphenyls), which comprised the Aroclor 1242 mixture, was greatly enhanced by the addition of biphenyl (BP) to soil. After 49 days, only 25 to 35% of the original PCBs remained in the soil, and 48 to 49% was converted to
14
CO
2
(including soil carbonates) in treatments enriched with BP; by contrast, 92% of the PCBs remained and less than 2% was converted to
14
CO
2
in the unenriched control. Although the mineralization of PCBs in soils inoculated with
Acinetobacter
strain P6 was not greater than that in uninoculated BP-enriched soils, the initial and maximum mineralization rates and the disappearance of more highly chlorinated PCBs were greater with
Acinetobacter
strain P6. The mineralization of BP was consistent with kinetic models based upon linear-no growth and exponential growth; lower cell densities (<10
6
/g) of BP-oxidizing bacteria gave a better fit for exponential growth, whereas the highest cell density (10
9
/g) gave a better fit for linear-no growth. The numbers of BP-oxidizing bacteria declined exponentially upon depletion of the substrate. Since the mineralization of the chlorinated cometabolites was brought about by microorganisms (commensals) other than BP oxidizers,
14
CO
2
production could not be fit to either of the two growth models. However,
14
CO
2
production from the highest-density inoculum could be fit to a first-order (no-growth) sequential-reaction series. Although the population dynamics of the commensals could not be determined, the rate-limiting step in the cometabolic-commensal metabolism of PCBs to CO
2
had to be the initial oxidation, since the rate of
14
CO
2
production was directly related to the population density of BP oxidizers.
Biodegradation of
N
-Nitrosodimethylamine in Aqueous and Soil Systems
Authors: Kaplan David L. , Kaplan Arthur M.
Published: January 2020

N
-Nitrosodimethylamine (NDMA) was mineralized by microorganisms in aqueous and soil systems. Initial rates of mineralization (micrograms per milliliter per day) were calculated for a wide range of initial concentrations of NDMA (micrograms per milliliter to picograms per milliliter). Log-log plots of the data were fitted with both linear and nonlinear least-squares analyses; however, linear models provided better fits for the kinetic data in all cases. The slopes of the linear fits were not significantly different than 1.0 (
P
< 0.05); thus, first-order reaction kinetics were in effect over the range of concentrations tested, and saturation kinetics were not achieved. Rate constants (day
−1
) and total percent mineralized increased with decreasing initial concentrations of NDMA. Rates of mineralization were reduced in aqueous systems when supplemental carbon was available, whereas in soils, percentages of organic matter and supplemental carbon had little effect on rates of mineralization. Implications of these results for predictions of rates and threshold limits of mineralization activity in natural systems are discussed. A laboratory scale simulated trickling filter containing an activated charcoal bed provided a suitable environment for mineralization of NDMA at concentrations of 50 and 100 μg/ml on a continuous basis. NDMA was not toxic to natural populations of microorganisms at concentrations up to 10 mg/ml. Using high-pressure liquid chromatography coupled with radioactivity detection, we identified formaldehyde and methylamine as intermediates produced during the biodegradation of NDMA.
Passive Diffusion Technique for Concentration of Short-Chain Volatile Fatty Acids from Seawater
Authors: Molongoski John J. , Taylor Craig D.
Published: January 2020

A diffusion chamber is described which concentrates short-chain, volatile fatty acids from seawater while simultaneously separating them from interfering salts. The procedure relies on the passive diffusion of volatile compounds from acidified seawater samples and their subsequent absorption onto a base-impregnated filter. The method is simple, efficient, and adaptable to most commonly used methods of volatile acid analysis.
Aerobic Fermentation of D-Xylose to Ethanol by
Clavispora
sp
Authors: Nigam J. N. , Margaritis A. , Lachance M. A.
Published: January 2020

Eleven strains of an undescribed species of
Clavispora
fermented D-xylose directly to ethanol under aerobic conditions. Strain UWO(PS)83-877-1 was grown in a medium containing 2% D-xylose and 0.5% yeast extract, and the following results were obtained: ethanol yield coefficient (ethanol/D-xylose), 0.29 g g
−1
(57.4% of theoretical); cell yield coefficient (dry biomass/D-xylose), 0.25 g g
−1
; maximum ethanol concentration, 5.9 g liter
−1
; maximum volumetric ethanol productivity, 0.11 g liter
−1
h
−1
. With initial D-xylose concentrations of 40, 60, and 80 g liter
−1
, maximum ethanol concentrations of 8.8, 10.9, and 9.8 g liter
−1
were obtained, respectively (57.2, 57.1, and 48.3% of theoretical). Ethanol was found to inhibit the fermentation of D-xylose (

K
p

= 0.58 g liter
−1
) more than the fermentation of glucose (

K
p

= 6.5 g liter
−1
). The performance of this yeast compared favorably with that reported for some other D-xylose-fermenting yeasts.
Galactose transport in Streptococcus thermophilus
Authors: Hutkins R , Morris H A , McKay L L
Published: January 2020

Although Streptococcus thermophilus accumulated [14C]lactose in the absence of an endogenous energy source, galactose-fermenting (Gal+) cells were unable to accumulate [14C]galactose unless an additional energy source was added to the test system. Both Gal+ and galactose-nonfermenting (Gal-) strains transported galactose when preincubated with sucrose. Accumulation was inhibited 50 or 95% when 10 mM sodium fluoride or 1.0 mM iodoacetic acid, respectively, was added to sucrose-treated cells, indicating that ATP was required for galactose transport activity. Proton-conducting ionophores also inhibited galactose uptake, although N,N'-dicyclohexyl carbodiimide had no effect. The results suggest that galactose transport in S. thermophilus occurs via an ATP-dependent galactose permease and that a proton motive force is involved. The galactose permease in S. thermophilus TS2b (Gal+) had a Km for galactose of 0.25 mM and a Vmax of 195 micromol of galactose accumulated per min per g (dry weight) of cells. Several structurally similar sugars inhibited galactose uptake, indicating that the galactose permease had high affinities for these sugars.
Germination of spores from Clostridium botulinum B-aphis and Ba410
Authors: Montville T J , Jones S B , Conway L K , Sapers G M
Published: January 2020

The germination of spores from Clostridium botulinum B-aphis and Ba410 was examined. In a complex medium, heat activation of spores from both strains doubled the germination rates and was required for germination in the presence of 2% NaCl. In a defined medium (CTB [D. B. Rowley and F. Feeherry, J. Bacteriol. 104:1151-1157, 1970]), the parent strain B-aphis germinated at a rate of 0.77% min-1 in the absence of NaCl and was not affected by 2% NaCl. A salt-tolerant derivative, strain Ba410, germinated at rates of 0.16% min-1 in CTB and 0.04% min-1 in CTB containing 2% NaCl. L-Alanine-triggered spores germinated faster than did L-cysteine-triggered spores from both strains. When both amino acids were present, B-aphis germinated rapidly in the absence of NaCl and had biphasic kinetics in the presence of NaCl. Strain Ba410 had biphasic kinetics in the absence of NaCl and germinated slowly with single-phase kinetics in the presence of NaCl. L-Alanine- and L-cysteine-triggered germinations were each inhibited by both D-alanine and D-cysteine, indicating a common germinant-binding site for both alanine and cysteine. Attempts to select for variants with amino acid-specific germinant-binding sites were unsuccessful. Differences in the germination kinetics of both strains could not be explained by ultrastructural differences. Transmission electron micrographs revealed striking similarities between the strains.
Identification of transformation products arising from bacterial oxidation of codeine by Streptomyces griseus
Authors: Kunz D A , Reddy G S , Vatvars A
Published: January 2020

14-Hydroxycodeine and norcodeine were rigorously identified as products arising from codeine oxidation by Streptomyces griseus ATCC 10137. Both products were routinely detected in extracted culture filtrates after growth of cells in the presence of codeine for 1 week. Under these conditions, about 4 mol% of the codeine starting material was consumed, with norcodeine and 14-hydroxycodeine representing the only identifiable transformation products (molar ratio, 4:1, respectively). Extraction of a series of culture filtrates and purification of the pooled metabolites by thin-layer and high-pressure liquid chromatography led to the isolation of both biological products, the structures of which were verified by high-resolution mass spectrometry and proton nuclear magnetic resonance spectroscopy. The identities of both biological products were further confirmed by comparison of their spectral properties with those of authentic standards. This is the first report providing structural evidence for the biological formation of 14-hydroxycodeine from codeine and of codeine oxidation by S. griseus.
Partial Chemical and Physical Characterization of Two Extracellular Polysaccharides Produced by Marine, Periphytic
Pseudomonas
sp. Strain NCMB 2021
Authors: Christensen Bj�rn E. , Kjosbakken Johs , Smidsr�d Olav
Published: January 2020

The marine bacterium
Pseudomonas
sp. strain NCMB 2021, which can attach to solid, and especially hydrophobic, surfaces, elaborates two different extracellular polysaccharides in batch cultures. One (polysaccharide A) was produced only during exponential growth and contained glucose, galactose, glucuronic acid, and galacturonic acid in a molar ratio of 1.00:0.81:0.42:0.32. It produced viscous solutions, formed gels at high concentrations, and precipitated with several multivalent cations. The other (polysaccharide B) was released at the end of the exponential phase and in the stationary phase. It contained equimolar amounts of
N
-acetylglucosamine, 2-keto-3-deoxyoctulosonic acid, an unidentified 6-deoxyhexose, and also O-acetyl groups. Despite its high molecular weight (10
5
to 10
6
as judged by gel filtration), the polysaccharide produced aqueous solutions with very low viscosities and was also soluble in 90% aqueous phenol, 80% methanol, and 80% ethanol.
Purification and Characterization of Liposan, a Bioemulsifier from
Candida lipolytica
Authors: Cirigliano Michael C. , Carman George M.
Published: January 2020

The inducible water-soluble bioemulsifier liposan (M. C. Cirigliano and G. M. Carman, Appl. Environ. Microbiol. 48:747-750, 1984) was purified from the yeast
Candida lipolytica.
The purification procedure included repeated solvent extractions of a concentrated culture filtrate and Affi-Gel concanavalin A affinity chromatography. The procedure yielded a preparation containing a major band (
M
r
= 27,600) which stained for protein and carbohydrate upon polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Liposan is composed of approximately 83% carbohydrate and 17% protein. Acid and enzymatic digestions of the emulsifier revealed that the carbohydrate portion is a heteropolysaccharide consisting of glucose, galactose, galactosamine, and galacturonic acid. Liposan effected and stabilized oil-in-water emulsions with a variety of commercial vegetable oils. Emulsification and stabilization properties of liposan were compared to those of a number of commercial emulsifiers and stabilizers.

Images
Inhibition Experiments on Anaerobic Methane Oxidation
Authors: Alperin Marc J. , Reeburgh William S.
Published: January 2020

Anaerobic methane oxidation is a general process important in controlling fluxes of methane from anoxic marine sediments. The responsible organism has not been isolated, and little is known about the electron acceptors and substrates involved in the process. Laboratory evidence indicates that sulfate reducers and methanogens are able to oxidize small quantities of methane. Field evidence suggests anaerobic methane oxidation may be linked to sulfate reduction. Experiments with specific inhibitors for sulfate reduction (molybdate), methanogenesis (2-bromoethanesulfonic acid), and acetate utilization (fluoroacetate) were performed on marine sediments from the zone of methane oxidation to determine whether sulfate-reducing bacteria or methanogenic bacteria are responsible for methane oxidation. The inhibition experiment results suggest that methane oxidation in anoxic marine sediments is not directly mediated by sulfate-reducing bacteria or methanogenic bacteria. Our results are consistent with two possibilities: anaerobic methane oxidation may be mediated by an unknown organism or a consortium involving an unknown methane oxidizer and sulfate-reducing bacteria.
Reasons for possible failure of inoculation to enhance biodegradation
Authors: Goldstein R M , Mallory L M , Alexander M
Published: January 2020

Pseudomonas strains capable of mineralizing 2,4-dichlorophenol (DCP) and p-nitrophenol (PNP) in culture media were isolated from soil. One DCP-metabolizing strain mineralized 1.0 and 10 micrograms of DCP but not 2.0 to 300 ng/ml in culture. When added to lake water containing 10 micrograms of DCP per ml, the bacterium did not mineralize the compound, and only after 6 days did it cause the degradation of 1.0 microgram of DCP per ml. The organism did not grow or metabolize DCP when inoculated into sterile lake water, but it multiplied in sterile lake water amended with glucose or with DCP and supplemental nutrients. Its population density declined and DCP was not mineralized when the pseudomonad was added to nonsterile sewage, but the bacterium grew in sterile DCP-amended sewage, although not causing appreciable mineralization of the test compound. Addition of the bacterium to nonsterile soil did not result in the mineralization of 10 micrograms of DCP per g, although mineralization was evident if the inoculum was added to sterile soil. A second DCP-utilizing pseudomonad failed to mineralize DCP when added to the surface of sterile soil, although activity was evident if the inoculum was mixed with the soil. A pseudomonad able to mineralize 5.0 micrograms of PNP per ml in culture did not mineralize the compound in sterile or nonsterile lake water. The bacterium destroyed PNP in sterile sewage and enhanced PNP mineralization in nonsterile sewage. When added to the surface of sterile soil, the bacterium mineralized little of the PNP present at 5.0 micrograms/g, but it was active if mixed well with the sterile soil.(ABSTRACT TRUNCATED AT 250 WORDS)
Carbon isotopic fractionation in heterotrophic microbial metabolism
Authors: Blair N , Leu A , Mu�oz E , Olsen J , Kwong E , Des Marais D
Published: January 2020

Differences in the natural-abundance carbon stable isotopic compositions between products from aerobic cultures of Escherichia coli K-12 were measured. Respired CO2 was 3.4% depleted in 13C relative to the glucose used as the carbon source, whereas the acetate was 12.3% enriched in 13C. The acetate 13C enrichment was solely in the carboxyl group. Even though the total cellular carbon was only 0.6% depleted in 13C, intracellular components exhibited a significant isotopic heterogeneity. The protein and lipid fractions were -1.1 and -2.7%, respectively. Aspartic and glutamic acids were -1.6 and +2.7%, respectively, yet citrate was isotopically identical to the glucose. Probable sites of carbon isotopic fractionation include the enzyme, phosphotransacetylase, and the Krebs cycle.
Development of methods to measure virus inactivation in fresh waters
Authors: Ward R L , Winston P E
Published: January 2020

This study concerns the identification and correction of deficiencies in methods used to measure inactivation rates of enteric viruses seeded into environmental waters. It was found that viable microorganisms in an environmental water sample increased greatly after addition of small amounts of nutrients normally present in the unpurified seed virus preparation. This burst of microbial growth was not observed after seeding the water with purified virus. The use of radioactively labeled poliovirus revealed that high percentages of virus particles, sometimes greater than 99%, were lost through adherence to containers, especially in less turbid waters. This effect was partially overcome by the use of polypropylene containers and by the absence of movement during incubation. Adherence to containers clearly demonstrated the need for labeled viruses to monitor losses in this type of study. Loss of viral infectivity in samples found to occur during freezing was avoided by addition of broth. Finally, microbial contamination of the cell cultures during infectivity assays was overcome by the use of gentamicin and increased concentrations of penicillin, streptomycin, and amphotericin B.
Effects of metals on Legionella pneumophila growth in drinking water plumbing systems
Authors: States S J , Conley L F , Ceraso M , Stephenson T E , Wolford R S , Wadowsky R M , McNamara A M , Yee R B
Published: January 2020

An investigation of the chemical environment and growth of Legionella pneumophila in plumbing systems was conducted to gain a better understanding of its ecology in this habitat. Water samples were collected from hospital and institutional hot-water tanks known to have supported L. pneumophila and were analyzed for 23 chemical parameters. The chemical environment of these tanks was found to vary extensively, with the concentrations of certain metals reaching relatively high levels due to corrosion. The effect of various chemical conditions on L. pneumophila growth was then examined by observing its multiplication in the chemically analyzed hot-water tank samples after sterilization and reinoculation with L. pneumophila. L. pneumophila and associated microbiota used in these experiments were obtained from a hot-water tank. These stains were maintained in tap water and had never been passaged on agar. The results of the growth studies indicate that although elevated concentrations of a number of metals are toxic, lower levels of certain metals such as iron, zinc, and potassium enhance growth of naturally occurring L. pneumophila. Parallel observations on accompanying non-Legionellaceae bacteria failed to show the same relationship. These findings suggest that metal plumbing components and associated corrosion products are important factors in the survival and growth of L. pneumophila in plumbing systems and may also be important in related habitats such as cooling towers and air-conditioning systems.
Method for detecting viruses in aerosols
Authors: Wallis C , Melnick J L , Rao V C , Sox T E
Published: January 2020

A simple method with poliovirus as the model was developed for recovering human enteric viruses from aerosols. Filterite filters (pore size, 0.45 micron; Filterite Corp., Timonium, Md.) moistened with glycine buffer (pH 3.5) were used for adsorbing the aerosolized virus. No virus passed the filter, even with air flow rates of 100 liters/min. Virus recovery from the filter was achieved by rapid elution with 800 ml of glycine buffer, pH 10. The virus in the primary eluate was reconcentrated by adjusting the pH to 3.5, adding AlCl3 to 0.0005 M, collecting the virus on a 0.25-micron-pore Filerite disk (diameter, 25 mm) and and eluting with 6 ml of buffer, pH 10. With this method, virus could be detected regularly in aerosols produced by flushing when 3 X 10(8) PFU of poliovirus were present in the toilet bowl. Poliovirus-containing fecal material from two of four infants who had recently received oral polio vaccine also yielded virus in the aerosols when feces containing 2.4 X 10(7) to 4.5 X 10(7) PFU of virus had been added to the toilet bowl. Persons infected with a variety of natural enteric viruses are known to excrete this amount of virus in their daily stools.
Effect of phosphate and copper on the fermentation of hydroheptin
Authors: Tunac J B , McDaniel L E
Published: January 2020

The organism Streptomyces chartreusis IMRU 3962 produced a mixture of the antibiotics hydroheptin and chartreusin in fermentation broth. The addition of increasing levels of phosphate resulted in a corresponding increase in the production of both antibiotics, with maximum yields of 400 to 450 micrograms of chartreusin per ml and 80 to 100 micrograms of hydroheptin per ml at 0.45 to 0.55 M phosphate. Chartreusin was invariably produced at a higher ratio; however, a reversal in ratio to favor hydroheptin was attained when 0.03% copper sulfate was added to the medium, particularly at a 0.2 M KH2PO4 level, with antibiotic yields of 125 micrograms of hydroheptin per ml and 40 micrograms of chartreusin per ml.
Stability of the larvicidal activity of Bacillus thuringiensis subsp. israelensis: amino acid modification and denaturants
Authors: Pfannenstiel M A , Couche G A , Muthukumar G , Nickerson K W
Published: January 2020

The Bacillus thuringiensis subsp. israelensis mosquito larvicidal toxin is not a sulfhydryl-activated toxin. The protein disulfide bonds were cleaved and blocked without loss of toxicity. In contrast, modification of the lysine side chains eliminated toxicity. Additionally, the toxin was resistant to high concentrations of salt (8 M NaBr), organic solvents (40% methanol), denaturants (4 M urea), and neutral detergents (10% Triton X-100). However, it was inactivated by both positively and negatively charged detergents and by guanidine hydrochloride.
Phenotype character of the methylglyoxal resistance gene in Saccharomyces cerevisiae: expression in Escherichia coli and application to breeding wild-type yeast strains
Authors: Murata K , Fukuda Y , Shimosaka M , Watanabe K , Saikusa T , Kimura A
Published: January 2020

The gene responsible for the methylglyoxal resistance of Saccharomyces cerevisiae was cloned, and its phenotypic characteristics were investigated. S. cerevisiae cells with the gene could accumulate large amounts of glutathione in the medium and should remarkably high resistance to various toxic compounds such as methylglyoxal, tetramethylthiuram disulfide, iodoacetamide, and heavy-metal ions. The gene was also expressed in Escherichia coli cells, and the resistance of E. coli cells to toxic compounds also increased as observed for S. cerevisiae cells. The phenotypic characteristics of the gene were applicable to the selection of the transformants of wild-type yeast strains having no genetic markers.
Effect of Oxygen Tension, Mn(II) Concentration, and Temperature on the Microbially Catalyzed Mn(II) Oxidation Rate in a Marine Fjord
Authors: Tebo Bradley M. , Emerson Steven
Published: January 2020

We present evidence that the oxidation of Mn(II) in a zone above the O
2
/H
2
S interface in the water column of Saanich Inlet, British Columbia, Canada, is microbially catalyzed. We measured the uptake of
54
Mn(II) in water samples under in situ conditions of pH and temperature and in the presence and absence of oxygen. Experiments in the absence of oxygen provided a measure of the exchange of the tracer between the dissolved and solid pools of Mn(II); we interpret the difference between experiments in the presence and absence of oxygen to be a measure of Mn(II) oxidation. Using this method we examined the effect of oxygen tension, Mn(II) concentration, and temperature on the initial in situ Mn(II) oxidation rate (
V
0
). Mn(II) oxidation was almost twice as fast under conditions of 67% air saturation (
V
0
=5.5 nM h
−1
) as with the in situ concentration of 15 μM (5% air saturation;
V
0
=3.1 nM h
−1
). Additions of ca. 18 μM Mn(II) completely inhibited all Mn(II) oxidation at three different depths in the oxidizing zone, and there was a temperature optimum for Mn(II) oxidation of around 20°C. These results are consistent with biologically mediated Mn(II) oxidation and indicate that the rate is limited by both oxygen and the concentration of microbial binding sites in this environment.
Immunoperoxidase method with human immune serum globulin for broad-spectrum detection of cultivable human enteric viruses: application to enumeration of cultivable viruses in environmental samples
Authors: Payment P , Trudel M
Published: January 2020

The detection and enumeration of most cultivable human enteric viruses from water is possible if samples are first inoculated onto a suitable cell line such as MA-104 or BGM. Virus growth is then detected by an indirect immunoperoxidase method with human immune serum globulin as the source of antibody to most enteric viruses. The number of positive cell cultures in the immunoperoxidase assay is used to calculate the virus titer (as a most probable number) in the sample assayed.
Comparison of enrichment broths for isolation of Campylobacter jejuni
Authors: Heisick J
Published: January 2020

Growth of Campylobacter jejuni was compared in enrichment broths of Doyle and Roman (Appl. Environ. Microbiol. 43:1343-1353, 1982) and Park et al. (C. E. Park, Z. K. Stankiewicz, J. Lovett, and J. Hunt, Can. J. Microbiol. 27:841-842, 1981), as modified by Lovett et al. (J. Lovett, D. W. Francis, and J. M. Hunt, Appl. Environ. Microbiol. 46:459-462, 1983). Inoculated foods used were cream-pudding types, which may be cross-contaminated by improper handling, improper storage of meats prepared simultaneously, or the use of raw milk as an ingredient. Both broths adequately supported growth.
Isolation of Gregatin A from
Phialophora gregata
by Preparative High-Pressure Liquid Chromatography
Authors: Taylor Scott L. , Peterson Robert E. , Gray Lynn E.
Published: January 2020

A method was developed for the production and purification of gregatin A from
Phialophora gregata
NRRL 13198 cultured on rice at 20°C for 28 days. Liquid extraction followed by high-pressure liquid chromatography afforded 247.0 mg of crystalline gregatin A per kg of rice.
Diffusion through a Double-Sided Plate: Development of a Method to Study Alga-Bacterium Interactions
Authors: Colwell Frederick S. , Speidel Harold K.
Published: January 2020

Bacteria and algae isolated from a wastewater oxidation pond were inoculated onto opposing surfaces of double-layer agar plates (Lutri plates) to determine the usefulness of such plates for studying microbial interactions. The altered growth characteristics of various algae depending on the species of bacteria on the adjacent medium surface indicated that there was diffusion of extracellular products through the agar, suggesting that this simple assay can be used for screening potential interactions of actively growing organisms.
Spore heat resistance and specific mineralization
Authors: Bender G R , Marquis R E
Published: January 2020

Spores of Bacillus megaterium ATCC 19213, Bacillus subtilis niger and Bacillus stearothermophilus ATCC 7953 were converted to fully demineralized, but viable, H forms by controlled acid titration. H forms were more heat sensitive than were native forms, but z values were greater for killing of H spores than those for native spores. Therefore, the differences in heat sensitivity between native and H forms decreased with increasing killing temperature. The increase in heat sensitivity associated with demineralization did not appear to be due to damage to cortex lytic enzymes of the germination system because it could not be moderated by decoating heated H spores and plating them on medium with added lysozyme. H spores could be remineralized by means of back titration with appropriate base solutions. The remineralized spores, except for the Na form, were then more heat resistant than were H spores. Ca and Mn were more effective in restoring resistance than were Mg and K. Generally, the remineralized forms (except for the Na form) had z values greater than those of the native forms but still less than those of the H forms. At lower killing temperatures, the reinstatement of resistance could be related to the extent of remineralization. However, at higher killing temperatures, only a fraction of the mineral was effective in restoring resistance, and higher levels of remineralization did not result in greater resistance. Mineralization is clearly an important factor in spore heat resistance, but the relationship between resistance and mineralization is complex and dependent on killing temperature.
Examination of Thermophilic Methane-Producing Digesters by Analysis of Bacterial Lipids
Authors: Henson J. Michael , Smith Paul H. , White David C.
Published: January 2020

Thermophilic methane-producing digesters were examined by the analysis of lipids to determine the microbial biomass, community structure, and nutritional status of the microbes within the digesters. The digesters received a daily feedstock of cattle feed and Bermuda grass, with some digesters receiving additional supplements of propionate, butyrate, or nitrate. Microbial biomass, measured as total extractable lipid phosphate, was decreased in slurries from digesters receiving continuous addition of the fermentation intermediates propionate or butyrate as compared with slurries from control digesters receiving the feedstock alone. In slurries from digesters that received continuous addition of nitrate, the microbial biomass was higher than in the slurries from control digesters. The control digesters had ca. 2.5 × 10
11
bacteria per g (dry weight) as determined from total extractable lipid phosphate. Shifts in microbial community structure were observed by analysis of ester-linked phospholipid fatty acids. Statistical analysis of the patterns of phospholipid fatty acids indicated that the digesters receiving different supplements could be distinguished from the control digester and from each other. Poly-β-hydroxybutyric acid, an indicator of metabolic stress, was detected in slurries from all the digesters. Slurries from the nitrate-amended digester had the highest concentration of poly-β-hydroxybutyric acid, whereas slurries from the propionate-amended digester had the lowest concentration. These chemical analyses offer a quantitative means to correlate shifts in microbial biomass, community structure, and nutritional status in complex fermentation systems to the production of a specific end product.
Use of immunofluorescence and phase-contrast microscopy for detection and identification of Giardia cysts in water samples
Authors: Sauch J F
Published: January 2020

A method was developed in which indirect immunofluorescence and phase-contrast microscopy are used for rapid detection and identification of Giardia cysts in raw and finished water supplies. When anti-Giardia cyst antiserum and fluorescein conjugate were applied to known Giardia cysts on membrane filters, the cysts fluoresced bright green when they were illuminated by UV light. This procedure permitted individual cysts to be quickly located even in samples heavily contaminated with other microorganisms and debris. The identity of presumptive Giardia cysts located in this way could then be confirmed by observing characteristic internal morphological features with phase-contrast microscopy. With this method, Giardia cysts were detected and their identities were confirmed in samples taken from raw and finished surface water supplies during several recent outbreaks.
Anaerobic degradation of veratrylglycerol-beta-guaiacyl ether and guaiacoxyacetic acid by mixed rumen bacteria
Authors: Chen W , Supanwong K , Ohmiya K , Shimizu S , Kawakami H
Published: January 2020

Veratrylglycerol-beta-guaiacyl ether (0.2 g/liter), a lignin model compound, was found to be degraded by mixed rumen bacteria in a yeast extract medium under strictly anaerobic conditions to the extent of 19% within 24 h. Guaiacoxyacetic acid, 2-(o-methoxyphenoxy)ethanol, vanillic acid, and vanillin were detected as degradation products of veratrylglycerol-beta-guaiacyl ether by thin-layer chromatography, gas chromatography, and gas chromatography-mass spectrometry. Guaiacoxyacetic acid (0.25 g/liter), when added into the medium as a substrate, was entirely degraded within 36 h, resulting in the formation of phenoxyacetic acid, guaiacol, and phenol. These results suggest that the beta-arylether bond, an important intermonomer linkage in lignin, can be cleaved completely by these rumen anaerobes.
Evaluation of methods for concentrating hepatitis A virus from drinking water
Authors: Sobsey M D , Oglesbee S E , Wait D A
Published: January 2020

By using recently developed cultivation and assay systems, currently available methods for concentrating enteric viruses from drinking water by adsorption to and subsequent elution from microporous filters followed by organic flocculation were evaluated for their ability to recover hepatitis A virus (HAV). Cell culture-adapted HAV (strain HM-175) in seeded tapwater was efficiently adsorbed by both electronegative (Filterite) and electropositive (Virosorb 1MDS) filters at pH and ionic conditions previously used for other enteric viruses. Adsorbed HAV was efficiently eluted from these filters by beef extract eluents at pH 9.5. Eluted HAV was further concentrated efficiently by acid precipitation (organic flocculation) of eluents containing beef extract made from powdered, but not paste, sources. By using optimum adsorption conditions for each type of filter, HAV was concentrated greater than 100-fold from samples of seeded tapwater, with about 50% recovery of the initial infectious virus added to the samples. The ability to recover and quantify HAV in contaminated drinking water with currently available methods should prove useful in further studies to determine the role of drinking water in HAV transmission.
Isolation and Screening of Yeasts That Ferment
d
-Xylose Directly to Ethanol
Authors: Nigam J. N. , Ireland R. S. , Margaritis A. , Lachance M. A.
Published: January 2020

Natural habitats of yeasts were examined for the presence of strains able to produce ethanol from
d
-xylose. Black knots, insect frass, and tree exudates were screened by enrichment in liquid
d
-xylose-yeast extract medium. These and each
d
-xylose-assimilating yeast in a collection from cactus fruits and
Drosophila
spp. were tested for alcohol production from this sugar. Among the 412 isolates examined, 36 produced more than 1 g of ethanol liter
−1
from 20 g of
d
-xylose liter
−1
, all under aerated conditions. Closer examination of the strains indicated that their time courses of
d
-xylose fermentation followed different patterns. Some strains produced more biomass than ethanol, and among these, ethanol may or may not be assimilated rapidly after depletion of
d
-xylose. Others produced more ethanol than biomass, but all catabolized ethanol after carbohydrate exhaustion. Ethanol production appeared best at low pH values and under mild aeration. Possible correlations between the nutritional profiles of the yeasts and their ability to produce ethanol from
d
-xylose were explored by multivariate analysis.
d
-Xylose appeared slightly better utilized by yeasts which rate poorly in terms of fermentation. The fermentation of
d
-glucose had no bearing on
d
-xylose fermentation. No specific nutritional trait could discriminate well between better
d
-xylose fermentors and other yeasts.
Nitrous Oxide Emission Associated with Autotrophic Ammonium Oxidation in Acid Coniferous Forest Soil
Authors: Martikainen Pertti J.
Published: January 2020

Aerobic N
2
O production was studied in nitrifying humus from urea-fertilized pine forest soil. Acetylene and nitrapyrin inhibited both NH
4
+
oxidation and N
2
O production, indicating that N
2
O production was closely associated with autotrophic NH
4
+
oxidation. N
2
O production was enhanced by low soil pH; it was negligible above pH 4.7. When soil pH decreased from 4.7 to 4.1, the relative amount of N
2
O-N produced from NH
4
+
-N oxidized increased exponentially to 20%. There was also some evidence that N
2
O formation was stimulated by salts (potassium sulfate and sodium phosphates). The maximum rate of N
2
O-N production was 0.17 μg of N
2
O-N per g of soil per h. When humus was treated with NO
2
−
, N
2
O evolved immediately, indicating chemical formation, but no N
2
O was formed on the addition of NO
3
−
. The amount of N
2
O-N evolved was 0.6 to 4.6% of NO
2
−
-N added. A high concentration of NO
2
−
and low soil pH enhanced chemical production of N
2
O. There was no accumulation of NO
2
−
during nitrification. The calculations indicated that chemical formation of N
2
O was not the main source of N
2
O during NH
4
+
oxidation. After the addition of inhibitors of NH
4
+
oxidation the soils contained NO
3
−
, but no N
2
O was produced. The results suggest that enhanced autotrophic NH
4
+
oxidation is a potential source of N
2
O in fertilized acid forest soil.
Biochemical characteristics of Edwardsiella ictaluri
Authors: Waltman W D , Shotts E B , Hsu T C
Published: January 2020

A total of 119 isolates of Edwardsiella ictaluri collected over the last 7 years from several states were biochemically characterized. Although not very reactive biochemically, this bacterium shows a high degree of homogeneity. Differences were found only in the production of gas from formate or from glucose at 37 degrees C and in the production of hydrogen sulfide as detected by lead acetate paper. Analysis of E. ictaluri by year of geographic area indicated that some differences existed, but no clear-cut biotypic variations were found. All isolates studied were capable of degrading chondroitin sulfate, a major component of cartilage, which may be an important virulence factor in the formation of the hole-in-the-head lesion characteristic of infected fish.
Intermediate-Scale, Semicontinuous Solid-Phase Fermentation Process for Production of Fuel Ethanol from Sweet Sorghum
Authors: Gibbons William R. , Westby Carl A. , Dobbs Thomas L.
Published: January 2020

A novel, semicontinuous solid-phase fermentation system was used to produce fuel ethanol from sweet sorghum. The process was at an intermediate scale. In the process, dried and shredded sweet sorghum was rehydrated to 70% moisture, acidified to pH 2.0 to 3.0, and either pasteurized (12 h at 70 to 80°C) or not pasteurized before spray inoculation with a broth culture of
Saccharomyces cerevisiae.
Fermented pulp exited the semicontinuous fermentor after a retention time of 72 h and contained approximately 6% (vol/vol) ethanol. Ethanol yields from dry sweet sorghum were 176 to 179 liters/10
3
kg (85% of theoretical). Production costs for a greatly scaled-up (×1,400) conceptual version of this system were projected by calculation to average $0.47/liter for 95% ethanol. The calculated energy balance (energy output/energy input ratio) was estimated to be 1.05 when pasteurization was included and 1.31 when pasteurization was omitted. In calculating the energy balances, the output energy of the protein feed byproduct and the input energy for growing the sweet sorghum were not considered. A design for the scaled-up plant (farm scale) is provided.
Survival of
Azotobacter
spp. in Dry Soils
Authors: Moreno J. , Gonzalez-Lopez J. , Vela G. R.
Published: January 2020

Dry soils stored in glass containers in the laboratory and protected from contamination for periods of 22 to 24 years yielded numerous colonies of
Azotobacter chroococcum
and other members of the family
Azotobacteraceae
. These results were compared with those reported in 1974, and the findings are uniformly consistent in terms of surviving populations. The data prove that these bacteria remain viable after prolonged periods of dormancy in much the same way as do the endospores of gram-positive bacteria.
Microbial Ecophysiology of Whey Biomethanation: Intermediary Metabolism of Lactose Degradation in Continuous Culture
Authors: Chartrain M. , Zeikus J. G.
Published: January 2020

The intermediary carbon and electron flow routes for lactose degradation during whey biomethanation were studied in continuous culture. The chemostat was operated under lactose-limited conditions with a 100-h retention time. The carbon balance observed for lactose degradation was 4.65 mmol of CH
4
, 4.36 mmol of CO
2
and 1.15 mmol of cellular carbon per mmol of lactose consumed, with other intermediary metabolites (i.e., acetate, lactate, etc.) accounting for less than 2% of the lactose consumed. The carbon and electron recoveries for this biomethanation were 87 and 90%, respectively.
14
C tracer studies demonstrated that lactose biomethanation occurred in three distinct but simultaneous phases. Lactose was metabolized primarily into lactate, ethanol, acetate, formate, and carbon dioxide. During this hydrolytic phase, 82% of the lactose was transformed into lactate. These metabolites were transformed into acetate and H
2
-CO
2
in a second, acetogenic, phase. Finally, the direct methane precursors were transformed during the methanogenic phase, with acetate accounting for 81% of the methane formed. A general scheme is proposed for the exact carbon and electron flow route during lactose biomethanation, which predicts the prevalent microbial populations in this ecosystem.
Microbial Ecophysiology of Whey Biomethanation: Characterization of Bacterial Trophic Populations and Prevalent Species in Continuous Culture
Authors: Chartrain M. , Zeikus J. G.
Published: January 2020

The organization and species composition of bacterial trophic groups associated with lactose biomethanation were investigated in a whey-processing chemostat by enumeration, isolation, and general characterization studies. The bacteria were spatially organized as free-living forms and as self-immobilized forms appearing in flocs. Three dominant bacterial trophic group populations were present (in most probable number per milliliter) whose species numbers varied with the substrate consumed: hydrolytic, 10
10
; acetogenic, 10
7
to 10
10
; and methanogenic, 10
6
to 10
9
. The three prevalent species utilizing lactose were identified as
Leuconostoc mesenteroides, Klebsiella oxytoca
, and
Clostridium butyricum. Clostridium propionicum
and
Desulfovibrio vulgaris
were the dominant lactate-consuming, hydrogen-producing acetogenic bacteria, while
D. vulgaris
was the only significant ethanol-degrading species.
Methanosarcina barkeri
and
Methanothrix soehngenii
were identified as the dominant acetate-utilizing methanogens, and
Methanobacterium formicicum
was the prevalent hydrogen-utilizing methanogen. A microbial food chain is proposed for lactose biomethanation that comprises multiple species in three different groups, with the major hydrogen-producing acetogen being a sulfate-reducing species,
D. vulgaris
, which functioned in the absence of significant levels of environmental sulfate.
Rapid physical mapping by transposon Tn5 mutagenesis to localize the cloned yeast ILV2 gene
Authors: Van Dyk T K , Falco S C , LaRossa R A
Published: January 2020

A rapid method for Tn5 mutagenesis of cloned genes on multicopy plasmids was used to map a yeast ILV2 mutant allele encoding a sulfometuron methyl-resistant acetolactate synthase. Twenty-one of 40 independent Tn5 insertions were within the 5.6-kilobase-pair cloned segment. Of these, seven adjacent transposition events inactivated the sulfometuron methyl resistance determinant, localizing the ILV2 gene to a minimum 1.4-kilobase-pair region.
Occurrence of free and conjugated 12,13-epoxytrichothecenes and zearalenone in banana fruits infected with Fusarium moniliforme
Authors: Chakrabarti D K , Ghosal S
Published: January 2020

Three recognized 12,13-epoxytrichothecene mycotoxins, trichothecolone, diacetoxyscirpenol, and T-2 toxin, and a hyperestrogenic factor, zearalenone, together with the fatty acid esters of trichothecolone, scirpenetriol, T-2 tetraol, and zearalenone, were isolated from the flask culture extractives of Fusarium moniliforme Sheldon (IMI 225232) as well as from the fruit of banana (Musa sapientum L.) infected with the same fungus in the field and in storage. The total concentrations of these toxins in the naturally infected fruits were quite high (0.8 to 1.0 mg/g of fruit). F. moniliforme infections of banana fruits, being of wide occurrence in the world, could cause serious health problems in humans when the infected fruits are ingested for a prolonged period of time.
Some Effects of Diflubenzuron on Growth and Sporogenesis in
Streptomyces
spp
Authors: Smucker Richard A. , Simon Susanne L.
Published: January 2020

Diflubenzuron, an insect growth regulator that blocks chitin deposition in insect cuticles, was tested for its effects on morphogenesis of
Streptomyces
spp. Use of diflubenzuron resulted in reduced dominance of spore hairs, reduced the width of the outer wall, and prevented formation of the inner spore wall in
S. bambergiensis
. In
S. coelicolor
, diflubenzuron altered the structure of the fibrillar pattern of spore envelopes. Exposure to diflubenzuron resulted in small increases in exported protein and in a ca. 20% increase in chitinase in both
Streptomyces
spp.
Enzymatic Aryl-O-Methyl-
14
C Labeling of Model Lignin Monomers
Authors: Frazer Anne Cornish , Bossert Ingeborg , Young L. Y.
Published: January 2020

Aryl-
O
-methyl ethers are abundant in aerobic and anaerobic environments. In particular, lignin is composed of units of this type. Lignin monomers specifically radiolabeled in methoxy, side chain, and ring carbons have been synthesized by chemical procedures and are important in studies of lignin synthesis and degradation, humus formation, and microbial O-demethylation. In this paper attention is drawn to an enzymatic procedure for preparing O-methyl-
14
C-labeled aromatic lignin monomers which has not previously been exploited in microbial ecology and physiology studies and which has several advantages compared with chemical synthesis procedures.
O
-[
methyl
-
14
C]vanillic and
O
-[
methyl
-
14
C]ferulic acids were prepared with
S
-[
methyl
-
14
C]adenosyl-
l
-methionine as the methyl donor, using commercially obtained porcine liver catechol-
O
-methyltransferase (EC 2.1.1.6). The specific activity of the methylated products was the same as that of the methyl donor, a maximum of about 58 μCi/μmol, and the yields were 42% (vanillate) and 35% (ferulate). Thus lignin monomers are readily prepared as O-methylated products of the catechol-
O
-methyltransferase reaction and, with this enzyme method of preparation, would be more widely available than labeled compounds which require chemical synthesis.
Anaerobic C
1
Metabolism of the O-Methyl-
14
C-Labeled Substituent of Vanillate
Authors: Frazer Anne Cornish , Young L. Y.
Published: January 2020

The O-methyl substituents of aromatic compounds constitute a C
1
growth substrate for a number of taxonomically diverse anaerobic acetogens. In this study, strain TH-001, an O-demethylating obligate anaerobe, was chosen to represent this physiological group, and the carbon flow when cells were grown on O-methyl substituents as a C
1
substrate was determined by
14
C radiotracer techniques.
O
-[
methyl
-
14
C]vanillate (4-hydroxy-3-methoxy-benzoate) was used as the labeled C
1
substrate. The data showed that for every O-methyl carbon converted to [
14
C]acetate, two were oxidized to
14
CO
2
. Quantitation of the carbon recovered in the two products, acetate and CO
2
, indicated that acetate was formed in part by the fixation of unlabeled CO
2
. The specific activity of
14
C in acetate was 70% of that in the O-methyl substrate, suggesting that only one carbon of acetate was derived from the O-methyl group. Thus, it is postulated that the carboxyl carbon of the product acetate is derived from CO
2
and the methyl carbon is derived from the O-methyl substituent of vanillate. The metabolism of
O
-[
methyl
-
14
C]vanillate by strain TH-001 can be described as follows: 3
14
CH
3
OC
7
H
5
O
3
+ CO
2
+ 4H
2
O →
14
CH
3
COOH + 2
14
CO
2
+ 10H
+
+ 10e
-
+ 3HOC
7
H
5
O
3
.