bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial Distribution, Structure, Biomass, and Physiology of Microbial Assemblages across the Southern Ocean Frontal Zones during the Late Austral Winter
Authors: Hanson Roger B. , Lowery H. Kenneth
Published: January 2020

We examined the spatial distributions of picoplankton, nanoplankton, and microplankton biomass and physiological state relative to the hydrography of the Southern Ocean along 90° W longitude and across the Drake Passage in the late austral winter. The eastern South Pacific Ocean showed some large-scale biogeographical differences and size class variability. Microbial ATP biomass was greatest in euphotic surface waters. The horizontal distributions of microbial biomass and physiological state (adenylate energy charge ratio) coincided with internal currents (fronts) of the Antarctic Circumpolar Current. In the Drake Passage, the biological scales in the euphotic and aphotic zones were complex, and ATP, total adenylate, and adenylate energy charge ratio isopleths were compressed due to the extension of the sea ice from Antarctica and constriction of the Circumpolar Current through the narrow passage. The physiological state of microbial assemblages and biomass were much higher in the Drake Passage than in the eastern South Pacific Ocean. The temperature of Antarctic waters, not dissolved organic carbon, was the major variable controlling picoplankton growth. Estimates of picoplankton production based on ATP increments with time suggest that production under reduced predation pressure was 1 to 10 μg of carbon per liter per day. Our results demonstrate the influence of large-scale hydrographic processes on the distribution and structure of microplankton, nanoplankton, and picoplankton across the Southern Ocean.
Soil amoebas as biological markers to estimate the quality of swimming pool waters
Authors: N'Diaye A , Georges P , N'Go A , Festy B
Published: January 2020

The legal biological survey of swimming pool waters is based on both the level of bacteriological contamination and the amount of material of fecal origin. The great number of soil amoebas and the occasional epidemiological risk involved led us to consider using these organisms as possible biological markers to estimate the quality of pool water and the extent of disinfection. During a 1-year survey of 54 public swimming pools, 765 superficial pool and tap water samples were collected. One portion (50 ml) drawn from 1-liter samples was filtered and cultured for amoebas. In specimens considered contaminated we detected at least 20 amoebas per liter, whereas uncontaminated samples contained fewer than 20 amoebas per liter. By keeping the threshold value voluntarily low, we were able to compare tap water with pool water and to monitor the quality of various disinfection procedures (i.e., chlorine, bromine, and Cu-Ag). The data suggest that the filters were not always protective against a high concentration of amoebas. Furthermore, these disinfection procedures were not equally efficient according to estimates based on biological criteria. In addition, the quality of swimming pool water also depends on the quality of its source tap water. Thus, the numeration of soil amoebas can be used as an additional biological marker to estimate the quality of swimming pool water.
Biotransformation of tetrachloroethylene to trichloroethylene, dichloroethylene, vinyl chloride, and carbon dioxide under methanogenic conditions
Authors: Vogel T M , McCarty P L
Published: January 2020

Tetrachloroethylene (PCE) and trichloroethylene (TCE), common industrial solvents, are among the most frequent contaminants found in groundwater supplies. Due to the potential toxicity and carcinogenicity of chlorinated ethylenes, knowledge about their transformation potential is important in evaluating their environmental fate. The results of this study confirm that PCE can be transformed by reductive dehalogenation to TCE, dichloroethylene, and vinyl chloride (VC) under anaerobic conditions. In addition, [14C]PCE was at least partially mineralized to CO2. Mineralization of 24% of the PCE occurred in a continuous-flow fixed-film methanogenic column with a liquid detention time of 4 days. TCE was the major intermediate formed, but traces of dichloroethylene isomers and VC were also found. In other column studies under a different set of methanogenic conditions, nearly quantitative conversion of PCE to VC was found. These studies clearly demonstrate that TCE and VC are major intermediates in PCE biotransformation under anaerobic conditions and suggest that potential exists for the complete mineralization of PCE to CO2 in soil and aquifer systems and in biological treatment processes.
Large-scale preparation of ribulosebisphosphate carboxylase from a recombinant system in Escherichia coli characterized by extreme plasmid instability
Authors: Pierce J , Gutteridge S
Published: January 2020

An ampicillin-resistant, RecA- strain of Escherichia coli (HB101) harboring the multicopy pBR322 plasmid containing the structural gene for ribulosebisphosphate carboxylase from Rhodospirillum rubrum was used to prepare large quantities of the carboxylase protein. This recombinant system was characterized by extreme plasmid instability, which resulted in part from the 1.7-fold faster growth rate of plasmid-free cells and in part from very rapid rates of plasmid segregation. The plasmid-containing organisms produced and excreted a large amount of beta-lactamase activity, with the result that ampicillin selection could only be maintained for a very short period of time, after which the plasmid-containing (carboxylase-producing) cells were overgrown by plasmid-free cells. The instability was so severe that even isolated colonies prepared on ampicillin-containing plates were impure and contained plasmid-free cells. Nevertheless, large quantities of carboxylase protein could be obtained from this system by using a highly dilute inoculum which allows selection of ampicillin-resistant (carboxylase-producing) organisms for a sufficient period of time so that the period of growth under nonselective conditions was minimized, and cells harvested at high cell densities contained large amounts of the carboxylase protein. In the present instance, 300-liter fermentations were initiated with a 0.3-microliter inoculum of freshly grown cells. After 20 h of growth in rich medium containing ampicillin, the harvested cells contained 74 g of ribulosebisphosphate carboxylase protein (average of two separate cultures). These results are discussed in terms of the general nature of plasmid instability and protocols available to minimize the effects of such instability.
Test Medium for the Growth of
Nitrosomonas europaea
Authors: Sato Chikashi , Schnoor Jerald L. , McDonald Donald B. , Huey Jon
Published: January 2020

A mineral medium for studying the growth of
Nitrosomonas europaea
was developed and examined. The medium was defined in terms of chemical speciation by using chemical equilibrium computer models. The medium significantly increased the metabolic activity of the organisms compared with previously developed media, yielding a specific growth rate as high as 3.0 day
−1
(generation time, 5.5 h). The specific growth rate was enhanced by increasing the inoculum and was linearly correlated with the inoculum-to-total-culture volume ratio on a semilog scale. A reproducible growth rate for
N. europaea
was obtained with this medium under controlled experimental conditions.
General Biochemical Characterization of Thermostable Pullulanase and Glucoamylase from
Clostridium thermohydrosulfuricum
Authors: Hyun H. H. , Zeikus J. G.
Published: January 2020

Cell extracts of
Clostridium thermohydrosulfuricum
, an anaerobic bacterium which ferments starch into ethanol at 65°C, contained both pullulanase and glucoamylase activities. The general physiochemical and catalytic properties of these enzyme activities were compared. Pullulanase and glucoamylase activities were stable and optimally active at 85 and 75°C, respectively. The pH optima for activity and pH stability ranges were, respectively, 5.5 to 6 and 4.5 to 5.5 for pullulanase and 4 to 6 and 5 to 6 for glucoamylase. The apparent [S]

0.5
v

and
V
max
for pullulanase activity on pullulan were 0.33 mg/ml and 2.6 U/mg of protein. The apparent [S]

0.5
v

and
V
max
for glucoamylase activity on starch were of 0.41 mg/ml and 0.31 U/mg of protein. These enzymes were active and stable in the presence of air or 10% (vol/vol) ethanol. These enzyme activities allowed the organism to actively degrade raw starch into glucose in the absence of significant α-amylase activity.
Simultaneous and Enhanced Production of Thermostable Amylases and Ethanol from Starch by Cocultures of
Clostridium thermosulfurogenes
and
Clostridium thermohydrosulfuricum
Authors: Hyun H. H. , Zeikus J. G.
Published: January 2020

Clostridium thermohydrosulfuricum
and
Clostridium thermosulfurogenes
produced ethanol and amylases with different components as primary metabolites of starch fermentation. Starch fermentation parameters were compared in mono- and cocultures of these two thermoanaerobes to show that the fermentation was dramatically improved as a consequence of coordinate action of amylolytic enzymes and synergistic metabolic interactions between the two species. Under given monoculture fermentation conditions, neither species completely degraded starch during the time course of the study, whereas in coculture, starch was completely degraded. In monoculture starch fermentation,
C. thermohydrosulfuricum
produced lower levels of pullulanase and glucoamylase, whereas
C. thermosulfurogenes
produced lower levels of β-amylase and glucoamylase. In coculture fermentation, improvement of starch metabolism by each species was noted in terms of increased amounts and rates of increased starch consumption, amylase production, and ethanol formation. The single-step coculture fermentation completely degraded 2.5% starch in 30 h at 60°C and produced 9 U of β-amylase per ml, 1.3 U of pullulanase per ml, 0.3 U of glucoamylase per ml, and >120 mM ethanol with a yield of 1.7 mol/mol of glucose in starch. The potential industrial applications of the coculture fermentation and the physiological basis for the interspecies metabolic interactions are discussed.
Effect of an activated sludge wastewater treatment plant on ambient air densities of aerosols containing bacteria and viruses
Authors: Fannin K F , Vana S C , Jakubowski W
Published: January 2020

Bacteria- and virus-containing aerosols were studied during the late summer and fall seasons in a midwestern suburb of the United States before and during the start-up and operation of an unenclosed activated sludge wastewater treatment plant. The study showed that the air in this suburban area contained low-level densities of indicator microorganisms. After the plant began operating, the densities of total aerobic bacteria-containing particles, standard plate count bacteria, total coliforms, fecal coliforms, fecal streptococci, and coliphages increased significantly in the air within the perimeter of the plant. Before plant operations, bacteria were detected from five genera, Klebsiella, Enterobacter, Serratia, Salmonella, and Aeromonas. During plant operations, the number of genera identified increased to 11. In addition to those genera found before plant operations, Escherichia, Providencia, Citrobacter, Acinetobacter, Pasteurella, and Proteus, were also identified. Enteric viruses were detected in low densities from the air emissions of this plant. Only standard plate count bacteria remained at significantly higher than base-line densities beyond 250 m downwind from the center of the aeration tanks. Fecal streptococci and coliphages appeared to be more stable in aerosols than the other indicator microorganisms studied. In general, the densities of microorganism-containing aerosols were higher at night than during the day. The techniques used in this study may be employed to establish microorganism-containing aerosol exposure during epidemiological investigations.
Construction of Killer Wine Yeast Strain
Authors: Seki Tetsuji , Choi Eon-Ho , Ryu Dewey
Published: January 2020

A double-stranded RNA plasmid which confers the superkiller phenotype was transferred into a wine yeast (Montrachet strain 522) and its leucine-requiring derivative (strain 694) by cytoduction, using the protoplast fusion technique. The killer wine yeast constructed completely suppressed the growth of killer-sensitive strains of
Saccharomyces cerevisiae
in yeast extract-peptone-glucose medium at pH 4.5, whereas the killer effect was somewhat decreased at pH 3.5. The wine yeast harboring the killer factor also inhibited the growth of killer-sensitive cells satisfactorily when it was grown in grape juice.
Metabolism and Solubilization of Cellulose by
Clostridium cellulolyticum
H10
Authors: Giallo Jacqueline , Gaudin Christian , Belaich Jean-Pierre
Published: January 2020

When
Clostridium cellulolyticum
was grown with cellulose MN300 as the substrate, the rates of growth and metabolite production were found to be lower than those observed with soluble sugars as the substrate. At low cellulose concentrations, the growth yields were equal to those obtained with cellobiose. The main fermentation products from cellulose and soluble sugars were the same. Up to 15 mM of consumed hexose, a change in the metabolic pathway favoring lactate production similar to that observed with soluble sugars was found to occur concomitantly with a decrease in molar growth yield. With cellulose concentrations above 5 g/liter, accumulation of soluble sugars occurred once growth had ceased. Glucose accounted for 30% of these sugars. A kinetic analysis of cellulose solubilization revealed that cellulolysis by
C. cellulolyticum
involved three stages whatever cellulose concentration was used. Analysis of these kinetics showed three consecutive enzymatic activity levels having the same
K

m

(0.8 g of cellulose per liter, i.e., 5 mM hexose equivalent) but decreasing values of
V
max
. The hypothesis is suggested that each step corresponds to differences in cellulose structure.
Adhesion of Streptococcus sanguis CH3 to polymers with different surface free energies
Authors: van Pelt A W , Weerkamp A H , Uyen M H , Busscher H J , de Jong H P , Arends J
Published: January 2020

The adhesion of the oral bacterium Streptococcus sanguis CH3 to various polymeric surfaces with surface free energies (gamma s) ranging from 22 to 141 erg cm-2 was investigated. Suspensions containing nine different bacterial concentrations (2.5 X 10(7) to 2.5 X 10(9) cells per ml) were used. After adhesion for 1 h at 21 degrees C and a standardized rinsing procedure, the number of attached bacteria per square centimeter (nb) was determined by scanning electron microscopy. The highest number of bacteria was consistently found on polytetrafluorethylene (gamma s = 22 erg cm-2), and the lowest number was found on glass (gamma s = 141 erg cm-2) at all bacterial concentrations tested. The overall negative correlation between nb and gamma s was weak. However, the slope of the line showing this decrease, calculated from an assumed linear relationship between nb and gamma s, appeared to depend strongly on the bacterial concentration and increased with increasing numbers of bacteria in the suspension. Analysis of the data for each separate polymer showed that the numbers of attached cells on polyvinyl chloride and polypropylene were higher but that those on polycarbonate were lower than would be expected on basis of a linear relationship between nb and gamma s. Desorption experiments were performed by first allowing the bacteria to attach to substrata for 1 h, after which the substrata and attached bacteria were removed to bacterial suspensions containing 10-fold lower bacterial concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
Salmonella infections in a marsupial, the quokka (Setonix brachyurus), in relation to seasonal changes in condition and environmental stress
Authors: Hart R P , Bradshaw S D , Iveson J B
Published: January 2020

An unusual abundance of Salmonella infections was studied in an island population of a wild marsupial, the quokka (Setonix brachyurus), which experiences starvation in summer associated with significant mortality. The frequency of infections was found to vary seasonally over most parts of the island, with high infection rates (70 to 100%) in summer and low infection rates (0 to 30%) in winter. In some samples, there was an average of as many as two isolations per animal, and up to five isolations were made from a single animal. By the end of summer, virtually all animals excreted Salmonella spp., with a median rate of excretion of approximately 3,000 Salmonella organisms per g of feces. The seasonal changes occurred over intervals of only weeks. The infections are believed to be associated with disruption of the digestive physiology of the animals caused by the poor quality of feed available in summer. This conclusion was supported by a quantitative study of the infections and by a field manipulation experiment which delayed the initiation of the infections as long as a food supplement was available. The proliferation of Salmonella spp. is discussed in terms of the ecology of the quokka and of the use of Salmonella spp. as indicators of environmental stress acting on the animals.
Mobilization of Thiobacillus ferrooxidans plasmids among Escherichia coli strains
Authors: Rawlings D E , Woods D R
Published: January 2020

Nonconjugative Thiobacillus ferrooxidans plasmids were mobilized at high frequencies among Escherichia coli strains by the IncP plasmid RP4 and at low frequencies by the IncN plasmid R46, but not by the IncW plasmid pSa. The mobilization region of a nonconjugative T. ferrooxidans plasmid was located on a 5.3-kilobase T. ferrooxidans DNA fragment.
Properties of Lactate Dehydrogenase in a Psychrophilic Marine Bacterium
Authors: Mitchell P. , Yen H. C. , Mathemeier P. F.
Published: January 2020

Lactate dehydrogenase (EC 1.1.1.27) from
Vibrio marinus
MP-1 was purified 15-fold and ammonium activated. The optimum pH for pyruvate reduction was 7.4. Maximum lactate dehydrogenase activity occurred at 10 to 15°C, and none occurred at 40°C. The crude-extract enzyme was stable between 15 and 20°C and lost 50% of its activity after 60 min at 45°C. The partially purified enzyme was stable between 8 and 15°C and lost 50% of its activity after 60 min at 30°C. The thermal stability of lactate dehydrogenase was increased by mercaptoethanol, with 50% remaining activity at 42°C.
Characterization of Bacteria by Particle Beam Mass Spectrometry
Authors: Sinha Mahadeva P. , Platz Robert M. , Friedlander Sheldon K. , Vilker Vincent L.
Published: January 2020

A technique is described for detecting and characterizing bacteria on a single-particle basis by mass spectrometry. The method involves generation of a particle beam of single whole cells which are rapidly volatilized and ionized in vacuum in the ion source of a quadrupole mass spectrometer. The particle beam can be generated, with minimal sample handling, from a naturally occurring aerosol or from a solution of bacteria that can be dispersed as an aerosol. The mass spectrum is generated by successively measuring the average intensities of different mass peaks. The average intensity is obtained by measuring the ion intensity distribution at the particular mass (
m/e
) for ion pulses from more than 1,000 bacteria particles.
Bacillus cereus, Bacillus subtilis
, and
Pseudomonas putida
samples were analyzed to test the capability of the instrument for differentiating among species of bacteria. Significant ion-intensity information was produced over the
m/e
range of 50 to 300, an improvement over previous pyrolysis-mass spectrometry results. The complex mass spectra contained a few unique peaks which could be used for the differentiation of the bacteria. A statistical analysis of the variations in peak intensities among the three bacteria provided a quantitative measure of the reproducibility of the instrument and its ability to differentiate among bacteria. The technique could lead to a new rapid method for the analysis of microorganisms and could be used for the detection of airborne pathogens on a continuous, real-time basis.
Effect of Sym Plasmid Curing on Symbiotic Effectiveness in
Rhizobium fredii
Authors: Mathis James N. , Barbour W. Mark , Elkan Gerald H.
Published: January 2020

A mutant, USDA 206C, of
Rhizobium fredii
USDA 206 was obtained by passage on acridine plates. This mutant was cured of its 197-megadalton Sym plasmid but retained its symbiotic effectiveness. Multiple plasmid and chromosomally borne
nif
gene copies have previously been shown in
R. fredii
USDA 206.
Hin
dIII and
Eco
RI restriction enzyme digests of plasmid and total DNA showed that at least two
nif
gene copies are probably missing in USDA 206C. To compare the symbiotic effectiveness of USDA 206 and USDA 206C, plant tests were carried out. Statistically significant differences were obtained for nodule number, nodule mass, nitrogenase activity per plant, nitrogenase specific activity, and total plant dry weight. There was an apparent correlation between loss of Sym plasmidborne
nif
gene copies and reduction of overall symbiotic effectiveness. Delayed nodulation by strain USDA 206C relative to strain USDA 206 also indicated an association with the loss of plasmidborne nodulation functions and the reduced symbiotic effectiveness of strain USDA 206C.
Enhancement of Pyrroloquinoline Quinone Production and Polyvinyl Alcohol Degradation in Mixed Continuous Cultures of
Pseudomonas putida
VM15A and
Pseudomonas
sp. Strain VM15C with Mixed Carbon Sources
Authors: Shimao Masayuki , Fujita Itsuki , Kato Nobuo , Sakazawa Chikahiro
Published: January 2020

In a mixed continuous culture of
Pseudomonas putida
VM15A and
Pseudomonas
sp. strain VM15C with polyvinyl alcohol (PVA) as the sole source of carbon, growth of the PVA-degrading bacterium VM15C and, hence, PVA degradation were limited by the growth factor, pyrroloquinoline quinone, produced by VM15A. Feeding of a carbon source for VM15A, ethanol, with PVA enhanced pyrroloquinoline quinone production and caused increases in the VM15C population and PVA degradation in a mixed continuous culture. There was an optimum range for PVA degradation of the ethanol concentration, although pyrroloquinoline quinone concentrations in continuous mixed cultures increased with increasing ethanol concentration.
Biosynthetic relationship among aflatoxins B1, B2, M1, and M2
Authors: Dutton M F , Ehrlich K , Bennett J W
Published: January 2020

Aflatoxins are a family of toxic, acetate-derived decaketides that arise biosynthetically through polyhydroxyanthraquinone intermediates. Most studies have assumed that aflatoxin B1 is the biosynthetic precursor of the other aflatoxins. We used a strain of Aspergillus flavus which accumulates aflatoxin B2 to investigate the later stages of aflatoxin biosynthesis. This strain produced aflatoxins B2 and M2 but no detectable aflatoxin B1 when grown over 12 days in a low-salt, defined growth medium containing asparagine. Addition of dichlorvos to this growth medium inhibited aflatoxin production with concomitant accumulation of versiconal hemiacetal acetate. When mycelial pellets were grown for 24, 48, and 72 h in growth medium and then transferred to a replacement medium, only aflatoxin B2 and M2 were recovered after 96 h of incubation. Addition of sterigmatocystin to the replacement medium led to the recovery of higher levels of aflatoxins B2 and M2 than were detected in control cultures, as well as to the formation of aflatoxins B1 and M1 and O-methylsterigmatocystin. These results support the hypothesis that aflatoxins B1 and B2 can arise independently via a branched pathway.
Mechanism of the Heat Sensitization of
Bacillus subtilis
Spores by Ethidium Bromide
Authors: Hanlin J. H. , Slepecky R. A.
Published: January 2020

Pretreatment with ethidium bromide (5 μg/ml) followed by a water wash had no effect on unheated
Bacillus subtilis
spores, but the viability of these spores after heating was much lower than that of similarly heated spores exposed to water alone. The fate of water- or ethidium bromide-treated spores, unheated or heated, was followed by allowing them to germinate and outgrow in a minimal or a complex liquid medium. Spores exposed to ethidium bromide and then heated (85°C, 10 min) exhibited a developmental block during germination and outgrowth. Many of them were blocked at the stage when the bacterium emerged from the germinated spore. When 0.35 μg of ethidium bromide per ml was added to heated spores in the germination-growth medium, the outgrowth of heated spores was inhibited to the same extent as were pretreated spores. Ethidium bromide acted in the first hour of germination of heated spores since addition after this time was ineffective in inhibiting recovery events. Repair of heat-damaged spore DNA was detected during the first 2 h of germination. The addition of ethidium bromide (final concentration, 0.35 μg/ml) inhibited DNA repair during early outgrowth. Increased sensitivity of spores to heat after pretreatment with sublethal concentrations of ethidium bromide was due to the inhibition of the repair of heat-damaged DNA.
Role of a Ferric Ion-Reducing System in Sulfur Oxidation of
Thiobacillus ferrooxidans
Authors: Sugio Tsuyoshi , Domatsu Chitoshi , Munakata Osamu , Tano Tatsuo , Imai Kazutami
Published: January 2020

The properties of a ferric ion-reducing system which catalyzes the reduction of ferric ion with elemental sulfur was investigated with a pure strain of
Thiobacillus ferrooxidans
. In anaerobic conditions, washed intact cells of the strain reduced 6 mol of Fe
3+
with 1 mol of elemental sulfur to give 6 mol of Fe
2+
, 1 mol of sulfate, and a small amount of sulfite. In aerobic conditions, the 6 mol of Fe
2+
produced was immediately reoxidized by the iron oxidase of the cell, with a consumption of 1.5 mol of oxygen. As a result, Fe
2+
production was never observed under aerobic conditions. However, in the presence of 5 mM cyanide, which completely inhibits the iron oxidase of the cell, an amount of Fe
2+
production comparable to that formed under anaerobic conditions was observed under aerobic conditions. The ferric ion-reducing system had a pH optimum between 2.0 and 3.8, and the activity was completely destroyed by 10 min of incubation at 60°C. A short treatment of the strain with 0.5% phenol completely destroyed the ferric ion-reducing system of the cell. However, this treatment did not affect the iron oxidase of the cell. Since a concomitant complete loss of the activity of sulfur oxidation by molecular oxygen was observed in 0.5% phenol-treated cells, it was concluded that the ferric ion-reducing system plays an important role in the sulfur oxidation activity of this strain, and a new sulfur-oxidizing route is proposed for
T. ferrooxidans
.
Rate of Bacterial Mortality in Aquatic Environments
Authors: Servais Pierre , Billen Gilles , Rego Jose Vives
Published: January 2020

A method is proposed which provides a minimum estimate of the rate of bacterial mortality in growing natural populations of planktonic bacteria. This estimate is given by the rate of decrease of radioactivity from the DNA of a [
3
H]thymidine-labeled natural assemblage of bacteria after all added thymidine has been exhausted from the medium. Results obtained from river water, estuarine water, and seawater show overall bacterial mortality rates in the range 0.010 to 0.030 h
−1
, in good agreement with the range of growth rates measured in the same environments. Use of selective filtration through Nuclepore filters (pore size, 2 μm) allowed us to determine the contribution of microzooplankton grazing to overall bacterial mortality. Grazing rates estimated by this method ranged from 0 to 0.02 h
−1
.
Laboratory infection of chicken eggs with Campylobacter jejuni by using temperature or pressure differentials
Authors: Clark A G , Bueschkens D H
Published: January 2020

Fertile chicken eggs were infected in our laboratory with Campylobacter jejuni suspensions by using temperature or pressure differential methods of inoculation. After 2 days of incubation, over 90% of the eggs carried C. jejuni when iron was present in the inoculum. This percentage declined rapidly until by day 8, less than 10% of the eggs were detectably infected. However, up to 11% of hatched, healthy chicks carried C. jejuni in their intestinal tracts. The isolated organisms were of the same serotype as the initial inoculum. C. jejuni was recovered without difficulty when the intestinal tracts of chicks were enriched, but recovery from early dead-in-shell or infertile eggs was poor. This poor recovery and the rapid decline of C. jejuni after 2 days of egg incubation suggest that the vibrio is sensitive to some part of the incubating egg or to the temperature of prolonged incubation. It was impossible to predict which eggs would yield infected chicks on the basis of the number of organisms taken up by each egg, and no correlation existed between the number of organisms taken up and the efficiency of the hatch, i.e., the hatch ratio. If iron was omitted from the inoculum broth, the egg infection rate at day 2 was lower.
Methanogenesis in an Upflow Anaerobic Sludge Blanket Reactor at pH 6 on an Acetate-Propionate Mixture
Authors: ten Brummeler Erik , Pol Look W. Hulshoff , Dolfing Jan , Lettinga Gatze , Zehnder Alexander J. B.
Published: January 2020

High-rate anaerobic digestion can be applied in upflow anaerobic sludge blanket reactors for the treatment of various wastewaters. In upflow anaerobic sludge blanket reactors, sludge retention time is increased by a natural immobilization mechanism (viz. the formation of a granular type of sludge). When this sludge is cultivated on acid-containing wastewater, the granules mainly consist of an acetoclastic methanogen resembling
Methanothrix soehngenii.
This organism grows either in rods or in long filaments. Attempts to cultivate a stable sludge consisting predominantly of
Methanosarcina
sp. on an acetate-propionate mixture as substrate by lowering the pH from 7.5 during the start-up to approximately 6 failed. After 140 days of continuous operation of the reactor a filamentous organism resembling
Methanothrix soehngenii
prevailed in the sludge. The specific methanogenic activity of this sludge on acetate-propionate was optimal at pH 6.6 to 6.8 and 7.0 to 7.2, respectively.
Separation and Purification of Bacteria from Soil
Authors: Bakken Lars R.
Published: January 2020

Bacteria were released and separated from soil by a simple blending-centrifugation procedure. The percent yield of bacterial cells (microscopic counts) in the supernatants varied over a wide range depending on the soil type. The superantants contained large amounts of noncellular organic material and clay particles. Further purification of the bacterial cells was obtained by centrifugation in density gradients, whereby the clay particles and part of the organic materials sedimented. A large proportion of the bacteria also sedimented through the density gradient, showing that they had a buoyant density above 1.2 g/ml. Attachment to clay minerals and humic material may account for this apparently high buoyant density. The percent yield of cells was negatively correlated with the clay content of the soils, whereas the purity was positively correlated with it. The cell size distribution and the relative frequency of colony-forming cells were similar in the soil homogenate, the supernatants after blending-centrifugation, and the purified bacterial fraction. In purified bacterial fraction from a clay loam, the microscopically measured biomass could account for 20 to 25% of the total C and 30 to 40% of the total N as cellular C and N. The amount of cellular C and N may be higher, however, owing to an underestimation of the cell diameter during fluorescence. A part of the contamination could be ascribed to extracellular structures as well as partly decayed cells, which were not revealed by fluorescence microscopy.
Bacterial Biovolume and Biomass Estimations
Authors: Bratbak Gunnar
Published: January 2020

The biomass of bacterial populations in aquatic ecosystems is often estimated by measuring bacterial biovolume and converting this into biomass in terms of carbon. A reliable conversion factor relating the measured bacterial biovolume to bacterial carbon content is essential for this approach. Based on direct measurements of bacterial cell carbon content, cell number, and biovolume, I have derived an average conversion factor of 5.6 × 10
−13
g of C μm
−3
. This conversion factor is 3.4 to 6.6 times higher than most theoretically derived factors currently in use. Both bacterial biomass and bacterial production in aquatic ecosystems may thus have been seriously underestimated.
Growth of Legionella pneumophila in continuous culture
Authors: Berg J D , Hoff J C , Roberts P V , Matin A
Published: January 2020

A method was developed to grow Legionella pneumophila in continuous culture. A chemostat was used to simulate nutrient-limited, submaximal growth in the natural environmental and to provide a precisely controlled growth regimen. Cultures grew under forced aeration under conditions yielding up to 38% saturation of dissolved oxygen; supplemental CO2 (5%) at the same gas flow rates as ambient air had no effect on culture growth. Pleomorphism was observed during growth under all conditions. Pigment was produced only at D less than 0.03 h-1. Catalase was produced at higher growth rates but not at higher temperatures. The pathogenicity was unaffected by altering either the growth rate or the growth temperature.
TDP-1, a toxic component causing tibial dyschondroplasia in broiler chickens, and trichothecenes from Fusarium roseum 'Graminearum'
Authors: Lee Y W , Mirocha C J , Shroeder D J , Walser M M
Published: January 2020

Fusarium roseum 'Graminearum' was isolated from overwintered oats in Alaska and was tested for its ability to cause tibial dyschondroplasia (TDP) in broiler chickens. The water-soluble fraction was tested and found to cause TDP. In addition, diacetoxyscirpenol and 7-hydroxydiacetoxyscirpenol were identified in the acetonitrile fraction of the extracts and caused mild mouth lesions in chickens. Six major water-soluble components were purified by thin-layer chromatography and tested for toxicity to chick embryos. One of the six components, called TDP-1, was found to be lethal to chick embryos. There was a 100% incidence of TDP in chickens fed a diet containing 75 ppm (wt/wt) of pure TDP-1, thus establishing the cause and effect relationship between TDP and TDP-1. Analyses by thin-layer chromatography and mass spectrometry revealed that TDP-1 is polar and ninhydrin positive, exhibits fluorescence with UV irradiation, and is a nitrogen-containing component with an empirical formula of C15H20N2O4.
Modification of in vitro metabolism of T-2 toxin by esterase inhibitors
Authors: Wei R D , Chu F S
Published: January 2020

In vitro metabolism of T-2 toxin with S-9 fraction obtained from livers of phenobarbital-treated pigs and rats in the presence of different esterase inhibitors, including NaF, p-hydroxymercuribenzoate, phenylmethylsulfonyl fluoride, eserine sulfate, diisopropylfluorophosphate, and diethyl p-nitrophenyl phosphate, was studied. The metabolism was completely shifted to the hydroxylation at the C-3' position in the T-2 toxin molecule when esterase inhibitors were present. Diethyl p-nitrophenyl phosphate was found to be the most potent among six esterase inhibitors tested. In the presence of 10(-4) M diethyl p-nitrophenyl phosphate, 3'-hydroxy-T-2 toxin was the only metabolite detected. Similar results were obtained when other T-2-related metabolites were tested. The yield of conversion of T-2 toxin, acetyl T-2 toxin, HT-2 toxin and T-2 triol to their respective 3'-hydroxyl derivatives were 82, 73, 72, and 75%, respectively.
Enrichment medium for isolation of Campylobacter jejuni-Campylobacter coli
Authors: Rogol M , Shpak B , Rothman D , Sechter I
Published: January 2020

A broth enrichment medium for the improvement of isolation of Campylobacter jejuni-Campylobacter coli from stool samples and other specimens is presented. Of 1,228 samples examined in parallel, positive results were obtained from 81 by direct inoculation of selective media and from 112 after enrichment. Thus, an increase of 27.7% in the isolation rate was obtained by using the enrichment medium. The same medium without antibiotics allows the preservation of isolates of C. jejuni-C. coli for at least 2 months at 4 degrees C.
Response of the microflora in outdoor experimental streams to pentachlorophenol: compartmental contributions
Authors: Pignatello J J , Johnson L K , Martinson M M , Carlson R E , Crawford R L
Published: January 2020

Outdoor artificial streams were treated continuously with pentachlorophenol (PCP) for 88 days during the summer of 1983. The contributions of different stream compartments (microbial habitats) to microbial degradation of PCP were determined in a stream treated with 144 micrograms of PCP per liter. The 488-m long stream was composed of mud-bottomed pools alternating with gravel riffles. PCP loss in the stream attributable to microbial degradation after an adaptation period was in the range of 55 to 74%. Contributions to PCP loss were determined for rock surface (epilithic), macrophyte surface (epiphytic), sedimentary, and water column communities by measuring rates of PCP disappearance in stream water, containing ambient concentrations of PCP, in contact with representative compartmental samples. The specific capability, in units of micrograms of PCP per hour per square meter of stream cross-sectional area (macrophytes at maximum plant density, water column at mean depth, upper 10-cm layer of gravel), followed the order rock surface much greater than macrophytes greater than sediment approximately equal to water column. The compartmental contribution to total stream losses in units of grams per hour followed the same order, although the differences were smaller. The rate of PCP disappearance in the water column above sediment cores followed the order oxygen-rich greater than oxygen-poor approximately equal to anaerobic greater than sorption-only conditions. The large difference in specific capability between the rock surface and sediment compartments could be attributed to oxygen deficiency (because of chemical and biological oxygen demand) in the sediments. Free-floating and particle-attached organisms in the water column were important to PCP biodegradation.
Pressate from Peat Dewatering as a Substrate for Bacterial Growth
Authors: Mulligan Catherine N. , Cooper David G.
Published: January 2020

This study considered the possibility of using water expressed during the drying of fuel-grade peat as a substrate for microbial growth. Highly humified peat pressed for 2.5 min at 1.96 MPa produced water with a chemical oxygen demand of 690 mg/liter. Several biological compounds could be produced by using the organic matter in expressed peat water as a substrate. These included polymers such as chitosan, contained in the cell wall of
Rhizopus arrhizus
, and two extracellular polysaccharides, xanthan gum and pullulan, produced by
Xanthomonas campestris
and
Aureobasidium pullulans
, respectively. A very effective surfactant was produced by
Bacillus subtilis
grown in the expressed water. Small additions of nutrients to the peat pressate were necessary to obtain substantial yields of products. The addition of peptone, yeast extract, and glucose improved production of the various compounds. Biological treatment improved the quality of the expressed water to the extent that in an industrial process it could be returned to the environment.
Nutritionally limited pectinolytic bacteria from the human intestine
Authors: Jensen N S , Canale-Parola E
Published: January 2020

A selective procedure was used to isolate pectinolytic intestinal bacteria from human subjects. The three isolates with the greatest pectinolytic activity utilized pectin and a few related compounds as fermentable substrates for growth but did not utilize any other compound tested. Thus, their substrate utilization pattern was markedly different from that of previously described intestinal pectinolytic isolates. The three isolates are representatives of a nutritionally defined group of bacteria for which the term pectinophilic is proposed.
Effect of Gramicidin on Methanogenesis by Various Methanogenic Bacteria
Authors: Jarrell Ken F. , Hamilton Elizabeth A.
Published: January 2020

Methanogenesis by
Methanobacterium thermoautotrophicum
strains was extremely sensitive to gramicidin, total inhibition being observed at 0.2 μg/ml. In contrast, methane synthesis by
Methanococcus voltae, Methanogenium marisnigri, Methanosarcina mazei
, and
Methanospirillum hungatei
were resistant to the highest concentrations of gramicidin tested (40 μg/ml), although spheroplasts of
Methanospirillum hungatei
were extremely sensitive. Other species tested showed intermediate sensitivity to gramicidin, methanogenesis inhibition occurring at 4 to 20 μg/ml.
Development of a minimal medium for Clostridium perfringens by using an anaerobic chemostat
Authors: Goldner S B , Solberg M , Post L S
Published: January 2020

A minimal medium was developed for the cultivation of Clostridium perfringens in an anaerobic chemostat. Cultures of C. perfringens ATCC 3624 and NCTC 10240 were grown at 46 and 43 degrees C, respectively, in a glucose-limited, chemically defined medium at pH 7.2. The concentrations of amino acids, minerals, nucleotides, and vitamins, initially present in excess, were varied independently. The minimum concentration of each nutrient which would support 3 X 10(8) CFU/ml with a generation time of less than 40 min was determined and used to develop a reformulated defined medium. Atomic absorption spectroscopy and amino acid analyses of the reformulated medium indicated additional adjustments in nutrient content which led to the development of a minimal medium for each strain. The nutritional profile for each strain was similar. A decrease in the concentration of arginine, histidine, and tyrosine for strain 3624 and of arginine, histidine, and isoleucine for strain 10240 resulted in an increase in the optical density of each culture.
Rates of Drying and Survival of
Rhizobium meliloti
Strains During Storage at Different Relative Humidities
Authors: Mary Patrice , Ochin Daniel , Tailliez Roger
Published: January 2020

An investigation was made of the survival of six strains of
Rhizobium meliloti
filtered on membrane filters and held in atmospheres of controlled relative humidities (RH) of from 0 to 100% at 30�C in the presence of air. The rate of water loss in the desiccator was determined by the humidity-controlling solution used. Drying was accelerated by a mild evacuation of the desiccator during the drying step. Survival rates of
R. meliloti
strains were much higher after slow drying to 0% RH than immediately after rapid drying. Fast drying (drying period less than 3.4 h) was shown to adversely affect the tolerance to storage at all RH values tested (no survival after 2 to 5 days of storage). When survival during storage was measurable (after slow drying), the optimum RH values for storage were 43% for strains A145 and Wu498, 22 to 43% for strains RCR2011, Wu499, and Ar16, and 83% for strain RCR2004. The most favorable drying periods were 8, 9.2, 14.2, and 50.1 h for the subsequent storage of strain RCR2011 at RH values of 0, 22, 43, and 83%, respectively. The damaging effects of rapid drying on the tolerance of strain RCR2011 to storage at different RH values could be prevented either by rehydration and subsequent slow redrying or incomplete rapid drying followed by slow drying. It is suggested that
R. meliloti
strains are susceptible to desiccation stresses. However, the quantitative differences among strains appear to be large enough to permit selection with regard to tolerance to desiccation and storage in dried states.
Electrochemical classification of gram-negative and gram-positive bacteria
Authors: Matsunaga T , Nakajima T
Published: January 2020

Intestinal bacteria were classified as gram-positive or gram-negative by an electrode system with a basal plane pyrolytic graphite electrode and a porous nitrocellulose membrane filter to trap bacteria. When the potential of the graphite electrode was run in the range of 0 to 1.0 V versus the saturated calomel electrode (SCE), gram-positive bacteria gave peak currents at 0.65 to 0.69 V versus the SCE. The peak potentials of gram-negative bacteria were 0.70 to 0.74 V versus the SCE. Gram-negative bacteria and gram-positive bacteria were also classified based on the ratio of the second peak current to the first peak current when the potential cycle was repeated twice. The numbers of cells on the membrane filter were determined from the peak currents. It was found that the peak currents result from the electrochemical oxidation of coenzyme A in the cells of Escherichia coli and Lactobacillus acidophilus.
Activation and injury of Clostridium perfringens spores by alcohols
Authors: Craven S E , Blankenship L C
Published: January 2020

The activation properties of Clostridium perfringens NCTC 8679 spores were demonstrated by increases in CFU after heating in water or aqueous alcohols. The temperature range for maximum activation, which was 70 to 80 degrees C in water, was lowered by the addition of alcohols. The response at a given temperature was dependent on the time of exposure and the alcohol concentration. The monohydric alcohols and some, but not all, of the polyhydric alcohols could activate spores at 37 degrees C. The concentration of a monohydric alcohol that produced optimal spore activation was inversely related to its lipophilic character. Spore injury, which was manifested as a dependence on lysozyme for germination and colony formation, occurred under some conditions of alcohol treatment that exceeded those for optimal spore activation. Treatment with aqueous solutions of monohydric alcohols effectively activated C. perfringens spores and suggests a hydrophobic site for spore activation.
Comparative Amperometric Study of Uptake Hydrogenase and Hydrogen Photoproduction Activities between Heterocystous Cyanobacterium
Anabaena cylindrica
B629 and Nonheterocystous Cyanobacterium
Oscillatoria
sp. Strain Miami BG7
Authors: Kumazawa S. , Mitsui A.
Published: January 2020

Heterocystous filamentous cyanobacterium
Anabaena cylindrica
B629 and nonheterocystous filamentous cyanobacterium
Oscillatoria
sp. strain Miami BG7 were cultured in media with N
2
as the sole nitrogen source; and activities of oxygen-dependent hydrogen uptake, photohydrogen production, photooxygen evolution, and respiration were compared amperometrically under the same or similar experimental conditions for both strains. Distinct differences in these activities were observed in both strains. The rates of hydrogen photoproduction and hydrogen accumulation were significantly higher in
Oscillatoria
sp. strain BG7 than in
A. cylindrica
B629 at every light intensity tested. The major reason for the difference was attributable to the fact that the heterocystous cyanobacterium had a high rate of oxygen-dependent hydrogen consumption activity and the nonheterocystous cyanobacterium did not. The activity of oxygen photoevolution and respiration also contributed to the difference.
Oscillatoria
sp. strain BG7 had lower O
2
evolution and higher respiration than did
A. cylindrica
B629. Thus, the effect of O
2
on hydrogen photoproduction was minimized in
Oscillatoria
sp. strain BG7.