bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of microbial growth on pentachlorophenol
Authors: Klecka G M , Maier W J
Published: January 2020

Batch and fed-batch experiments were conducted to examine the kinetics of pentachlorophenol utilization by an enrichment culture of pentachlorophenol-degrading bacteria. The Haldane modification of the Monod equation was found to describe the relationship between the specific growth rate and substrate concentration. Analysis of the kinetic parameters indicated that the maximum specific growth rate and yield coefficients are low, with values of 0.074 h-1 and 0.136 g/g, respectively. The Monod constant (Ks) was estimated to be 60 micrograms/liter, indicating a high affinity of the microorganisms for the substrate. However, high concentrations (KI = 1,375 micrograms/liter) were shown to be inhibitory for metabolism and growth. These kinetic parameters can be used to define the optimal conditions for the removal of pentachlorophenol in biological treatment systems.
Effects of Some Environmental Factors on Growth Characteristics of
Candida utilis
on Peat Hydrolysates
Authors: Chang Fu-Hsian
Published: January 2020

Samples of peat from Pine Island and Brookston bogs in Minnesota were hydrolyzed with various concentrations of HCl or H
2
SO
4
solutions, before or after debituminization (an extraction process used to remove waxy materials, bitumens, from peat), to produce peak hydrolysates as growth substrates for
Candida utilis.
Hydrolysates were neutralized with concentrated NaOH solution to pH 3.5, 4.5, 5.0, 5.5, 6.0, and 7.0. The precipitated humates were removed by filtration. The resulting peat hydrolysates were amended with reagent-grade K
2
HPO
4
, K
2
SO
4
, and MgSO
4
, 200, 100, and 50 mg per liter of peat hydrolysate, respectively. The debituminized peat produced more total nitrogen (TN) and reducing substances (RS) than the nondebituminized peat. Peat hydrolysates produced by HCl solutions contained slightly higher RS and TN than those produced by H
2
SO
4
solutions; however, the latter were better growth substrates than the former. The yield coefficients in both H
2
SO
4
and HCl hydrolysates initially decreased at 12 to 24 h and then increased gradually over the remaining incubation period (24 to 96 h). As TN and RS were increased, an increase in cell density, biomass, and productivity was observed. In contrast, a decrease in specific growth rate occurred as the RS and TN were increased. The generation time of
C. utilis
was affected by the concentrations of RS and TN. A peak substrate yield coefficient was found at pH 5.0 in HCl hydrolysates and at pH 6.0 to 6.5 in H
2
SO
4
hydrolysates. Good linear correlation coefficients were found between RS and biomass of
C. utilis.
The coefficients of correlation increased as the TN level in hydrolysates was increased.
Susceptibility of chemostat-grown Yersinia enterocolitica and Klebsiella pneumoniae to chlorine dioxide
Authors: Harakeh M S , Berg J D , Hoff J C , Matin A
Published: January 2020

The resistance of bacteria to antimicrobial agents could be influenced by growth environment. The susceptibility of two enteric bacteria, Yersinia enterocolitica and Klebsiella pneumoniae, to chlorine dioxide was investigated. These organisms were grown in a defined medium in a chemostat and the influence of growth rate, temperature, and cell density on the susceptibility was studied. All inactivation experiments were conducted with a dose of 0.25 mg of chlorine dioxide per liter in phosphate-buffered saline at pH 7.0 and 23 degrees C. The results indicated that populations grown under conditions that more closely approximate natural aquatic environments, e.g., low temperatures and growth at submaximal rates caused by nutrient limitation, were most resistant. The conclusion from this study is that antecedent growth conditions have a profound effect on the susceptibility of bacteria to disinfectants, and it is more appropriate to use the chemostat-grown bacteria as test organisms to evaluate the efficacy of a certain disinfectant.
Bacterial O-Methylation of Chloroguaiacols: Effect of Substrate Concentration, Cell Density, and Growth Conditions
Authors: Allard Ann-Sofie , Remberger Mikael , Neilson Alasdair H.
Published: January 2020

O-methylation of chloroguaiacols has been examined in a number of gram-positive and gram-negative bacteria to elucidate the effects of substrate concentration, growth conditions, and cell density. Substrate concentrations between 0.1 and 20.0 mg liter
−1
were used, and it was found that (i) yields of the O-methylated products were significantly higher at the lowest concentrations and (ii) rates of O-methylation were not linear functions of concentration. With 3,4,5-trichloroguaiacol, the nature of the metabolites also changed with concentration. During growth with a range of substrates, O-methylation of chloroguaiacols also took place. With vanillate, however, de-O-methylation occurred: the chlorocatechol formed from 4,5,6-trichloroguaiacol was successively O-methylated to 3,4,5-trichloroguaiacol and 3,4,5-trichloroveratrole, whereas that produced from 4,5-dichloroguaiacol was degraded without O-methylation. Effective O-methylation in nonproliferating suspensions occurred at cell densities as low as 10
5
cells ml
−1
, although both the yields and the rates were lower than in more dense cultures. By using disk assays, it was shown that, compared with their precursors, all of the O-methylated metabolites were virtually nontoxic to the strains examined. It is therefore proposed that O-methylation functions as a detoxification mechanism for cells exposed to chloroguaiacols and chlorophenols. In detail, significant differences were observed in the response of gram-positive and gram-negative cell strains to chloroguaiacols. It is concluded that bacterial O-methylation is to be expected in the natural environment subjected to discharge of chloroguaiacols.
Effect of Metal-Rich Sewage Sludge Application on the Bacterial Communities of Grasslands
Authors: Barkay Tamar , Tripp Susan C. , Olson Betty H.
Published: January 2020

The effect of long-term application of heavy metal-laden sewage sludge on the total heterotrophic aerobic and the cadmium-resistant soil bacterial communities was studied. Gram-positive bacteria were completely absent from resistant communities. These findings suggest that this group is highly susceptible to Cd. Shannon's diversity indices estimated for total communities did not reveal negative effects on the communities that developed in the presence of sludge. However, Cd-resistant communities isolated from long-term sludge-amended soils were more diverse than the resistant communities from a control sample, suggesting that adaptation to Cd as a stressor had occurred in the presence of sludge constituents. This higher diversity was attributed to Cd resistance in pseudomonads and gram-negative fermenters. Resistance did not develop by dissemination of Cd resistance plasmids, because these were rarely detected in the genomes of resistant strains.
Anaerobic Degradation of Soluble Fractions of [
14
C-Lignin]Lignocellulose
Authors: Colberg P. J. , Young L. Y.
Published: January 2020

[
14
C-lignin]lignocellulose was solubilized by alkaline heat treatment and separated into different molecular size fractions for use as the sole source of carbon in anaerobic enrichment cultures. This study is aimed at determining the fate of low-molecular-weight, polyaromatic lignin derivatives during anaerobic degradation. Gel permeation chromatography was used to preparatively separate the original
14
C-lignin substrate into three component molecular size fractions, each of which was then fed to separate enrichment cultures. Biodegradability was assessed by monitoring total carbon dioxide and methane production, evolution of labeled gases, loss of
14
C-activity from solution, and changes in gel permeation chromatographic elution patterns. Results indicated that the smaller the size of the molecular weight fraction, the more extensive the degradation to gaseous end products. In addition, up to 30% of the entire soluble lignin-derived carbon was anaerobically mineralized to carbon dioxide and methane.
Phthalate metabolism in Pseudomonas fluorescens PHK: purification and properties of 4,5-dihydroxyphthalate decarboxylase
Authors: Pujar B G , Ribbons D W
Published: January 2020

Pseudomonas fluorescens PHK uses 4,5-dihydroxyphthalate as the sole carbon source for o-phthalate catabolism. This intermediate is the substrate for a decarboxylase of the pathway yielding protocatechuate. The decarboxylase was purified to homogeneity by an affinity chromatography procedure in which the reaction product, protocatechuate, was used as a ligand. We describe some properties of the enzyme, including its apparent molecular weight of 420,000 as determined by gel filtration and of 66,000 after sodium dodecyl sulfate-polyacrylamide disc gel electrophoresis, consistent with a hexameric functional protein. The apparent Km for the substrate 4,5-dihydroxyphthalate was 10.4 microM. The characteristics of this enzyme are compared with those described for the isofunctional enzyme from P. testosteroni.
Kinetic Studies of Bacterial Sulfate Reduction in Freshwater Sediments by High-Pressure Liquid Chromatography and Microdistillation
Authors: Hordijk Kees A. , Hagenaars Charles P. M. M. , Cappenberg Thomas E.
Published: January 2020

Indirect photometric chromatography and microdistillation enabled a simultaneous measurement of sulfate depletion and sulfide production in the top 3 cm of freshwater sediments to be made. The simultaneous measurement of sulfate depletion and sulfide production rates provided added insight into microbial sulfur metabolism. The lower sulfate reduction rates, as derived from the production of acid-volatile
35
S
2−
only, were explained by a conversion of this pool to an undistillable fraction under acidic conditions during incubation. A mathematical model was applied to calculate sulfate reduction from sulfate gradients at the sediment-water interface. To avoid disturbance of these gradients, the sample volume was reduced to 0.2 g (wet weight) of sediment. Sulfate diffusion coefficients in the model were determined (

D
s

= 0.3 × 10
−5
cm
2
s
−1
at 6°C). The results of the model were compared with those of radioactive sulfate turnover experiments by assessing the actual turnover rate constants (2 to 5 day
−1
) and pool sizes of sulfate at different sediment depths.
Characteristics and Adaptability of Some New Isolates of
Clostridium thermocellum
Authors: Bender Judith , Vatcharapijarn Y. , Jeffries T. W.
Published: January 2020

Six strains of
Clostridium thermocellum
isolated from various environments were characterized as to growth rate, production of reducing sugars, ethanol, and acetic acid from cellulose, base composition of DNA, and the abilities to adapt to ethanol and to grow at 45°C. Five of the six new isolates produced 7 to 15% more ethanol and two produced about 45% more reducing sugars than a standard reference strain. One strain (MC-6) adapted more readily to growth in 2% ethanol than the others.
Seasonal Bacterial Production in a Dimictic Lake as Measured by Increases in Cell Numbers and Thymidine Incorporation
Authors: Lovell Charles R. , Konopka Allan
Published: January 2020

Rates of primary and bacterial production in Little Crooked Lake were calculated from the rates of incorporation of H
14
CO
3
−
and [
methyl
-
3
H]thymidine, respectively. Growth rates of bacteria in diluted natural samples were determined for epilimnetic and metalimnetic bacterial populations during the summers of 1982 and 1983. Exponential growth was observed in these diluted samples, with increases in cell numbers of 30 to 250%. No lag was observed in bacterial growth in 14 of 16 experiments. Correlation of bacterial growth rates to corresponding rates of thymidine incorporation by natural samples produced a conversion factor of 2.2 × 10
18
cells produced per mole of thymidine incorporated. The mass of the average bacterial cell in the lake was 1.40 × 10
−14
± 0.05 × 10
−14
g of C cell
−1
. Doubling times of natural bacteria calculated from thymidine incorporation rates and in situ cell numbers ranged from 0.35 to 12.00 days (median, 1.50 days). Bacterial production amounted to 66.7 g of C m
−2
from April through September, accounting for 29.4% of total (primary plus bacterial) production during this period. The vertical and seasonal distribution of bacterial production in Little Crooked Lake was strongly influenced by the distribution of primary production. From April through September 1983, the depth of maximum bacterial production rates in the water column was related to the depth of high rates of primary production. On a seasonal basis, primary production increased steadily from May through September, and bacterial production increased from May through August and then decreased in September.
Kinetics of Denitrifying Growth by Fast-Growing Cowpea Rhizobia
Authors: El Hassan G. A. , Zablotowicz R. M. , Focht D. D.
Published: January 2020

Two fast-growing strains of cowpea rhizobia (A26 and A28) were found to grow anaerobically at the expense of NO
3
−
, NO
2
−
, and N
2
O as terminal electron acceptors. The two major differences between aerobic and denitrifying growth were lower yield coefficients (
Y
) and higher saturation constants (
K

s

) with nitrogenous oxides as electron acceptors. When grown aerobically, A26 and A28 adhered to Monod kinetics, respectively, as follows:
K

s

, 3.4 and 3.8 μM;
Y
, 16.0 and 14.0 g · cells eq
−1
; μ
max
, 0.41 and 0.33 h
−1
. Yield coefficients for denitrifying growth ranged from 40 to 70% of those for aerobic growth. Only A26 adhered to Monod kinetics with respect to growth on all three nitrogenous oxides. The apparent
K

s

values were 41, 270, and 460 μM for nitrous oxide, nitrate, and nitrite, respectively; the
K

s

for A28 grown on nitrate was 250 μM. The results are kinetically and thermodynamically consistent in explaining why O
2
is the preferred electron acceptor. Although no definitive conclusions could be drawn regarding preferential utilization of nitrogenous oxides, nitrite was inhibitory to both strains and effected slower growth. However, growth rates were identical (μ
max
, 0.41 h
−1
) when A26 was grown with either O
2
or NO
3
−
as an electron acceptor and were only slightly reduced when A28 was grown with NO
3
−
(0.25 h
−1
) as opposed to O
2
(0.33 h
−1
).
Bacterial Alginate Produced by a Mutant of
Azotobacter vinelandii
Authors: Chen Wen-Pin , Chen Jan-Yuan , Chang Shao-Chiang , Su Chia-Ling
Published: January 2020

The optimum conditions in shaken flasks for production of bacterial alginate by mutant C-14 of
Azotobacter vinelandii
NCIB 9068 and a comparison of the properties of bacterial and algal alginates were investigated. The largest amount of bacterial alginate was obtained in about 110 h by a culture grown on optimum medium at 34°C and 170-rpm shaking speed. The viscosity of the culture broth was 18,400 cps and the alginate concentration reached 6.22 g/liter. The viscosity of the purified bacterial alginate was as high as 11,200 cps at a low concentration (0.6%). A greater than fivefold concentration of algal alginate was required to reach the same viscosity at a low shear rate. A solution of bacterial alginate was more pseudoplastic than that of algal alginate was. No significant differences were observed in other properties of bacterial and algal alginates such as gel formation with calcium ion, thermostability, and effect of temperature, pH, and sodium chloride on viscosity.
Differential Adhesion and Infection of Nematodes by the Endoparasitic Fungus
Meria coniospora
(
Deuteromycetes
)
Authors: Jansson Hans-Börje , Jeyaprakash A. , Zuckerman Bert M.
Published: January 2020

The conidia of the endoparasitic fungus
Meria coniospora
(
Deuteromycetes
) had different patterns of adhesion to the cuticles of the several nematode species tested; adhesion in some species was only to the head and tail regions, on others over the entire cuticle, whereas on others there was a complete lack of adhesion. After adhesion, the fungus usually infected the nematode. However, adhesion to third-stage larvae of five animal parasitic nematodes, all of which carry the cast cuticle from the previous molt, did not result in infection.
M. coniospora
infected animal parasitic nematodes when this protective sheath was removed. Seven preparations of sialic acid (
N
-acetylneuraminic acid) gave three types of response in adhesion-infection of nematodes: (i) a significant reduction in conidial adhesions; (ii) no interference with adhesion, but a 10-day delay in infection; and (iii) a delay in infection by 2 to 3 days. The current results support previous findings indicating involvement of sialic acids localized on nematode cuticles in recognition of prey by
M. coniospora.
Fermentation of cellodextrins by cellulolytic and noncellulolytic rumen bacteria
Authors: Russell J B
Published: January 2020

Water-soluble cellodextrins were prepared from microcrystalline cellulose by using fuming hydrochloric acid and acetone precipitation. This cellodextrin preparation contained only trace amounts of glucose and cellobiose and was primarily composed of cellotetraose and cellopentaose. When various species of cellulolytic and noncellulolytic bacteria were cultured with cellodextrins, their growth rates and maximal optical densities were in most cases similar to those observed with cellobiose. Time course samplings and analyses of cellodextrins by high-pressure liquid chromatography indicated that longer-chain cellodextrins were hydrolyzed extracellularly to cellobiose and cellotriose. Cellodextrin utilization by noncellulolytic rumen bacteria and extracellular hydrolysis of cellodextrins increase the possibility that cross-feeding occurs in the rumen and help to explain the high numbers of noncellulolytic bacteria in ruminants fed fibrous diets.
Studies on transfection and transformation of protoplasts of Bacillus larvae, Bacillus subtilis, and Bacillus popilliae
Authors: Bakhiet N , Stahly D P
Published: January 2020

Protoplasts of Bacillus larvae NRRL b-3555 and Bacillus subtilis RM125 (restrictionless, modificationless mutant) were transfected with DNA from the B. larvae bacteriophage PBL1c in the presence of polyethylene glycol. B. subtilis 168 and Bacillus popilliae NRRL B-2309M protoplasts could not be transfected with PBL1c DNA. Protoplasts of B larvae NRRL B-3555 were transformed with plasmids pC194 and pHV33 in the presence of polyethylene glycol. The frequency of transformation was much higher when the plasmids were isolated from B. larvae NRRL B-3555 transformants than when they were isolated from B. subtilis 168. These results indicate that the restriction-modification systems found in B. larvae NRRL B-3555 and B. subtilis 168 may be different. Conditions for protoplast formation and cell wall regeneration were developed for B. popilliae NRRL B-2309S. However, no transformation occurred with plasmids pC194 and pHV33 (isolated from B. subtilis 168).
Cellulase and Other Polymer-Hydrolyzing Activities of
Trichomitopsis termopsidis
, a Symbiotic Protozoan from Termites
Authors: Odelson David A. , Breznak John A.
Published: January 2020

Crude extracts of the anaerobic, cellulolytic protozoan
Trichomitopsis termopsidis
possessed endo-β-1,4-glucanase and cellobiase activities, as evidenced by hydrolytic action on carboxymethyl cellulose and cellobiose, respectively. Cell extracts also hydrolyzed microcrystalline cellulose. Hydrolysis of microcrystalline cellulose displayed optima at pH 5 and at 30°C, and glucose was the sole product liberated. Cellulolytic activities of
T. termopsidis
appeared to be entirely cell associated. Hydrolytic activity was also detected against Douglas fir wood powder, xylan, starch, and protein, but not chitin. The importance of these enzymes in the nutrition of
T. termopsidis
is discussed in terms of the natural habitat of this protozoan (the hindgut of wood-eating termites).
Differences in Xylan Degradation by Various Noncellulolytic Thermophilic Anaerobes and
Clostridium thermocellum
Authors: Wiegel Jürgen , Mothershed Cheryle P. , Puls Jürgen
Published: January 2020

Hemicellulose fractions with a predetermined distribution of xylose, xylooligomers, and xylan fractions were obtained through steam explosion of wood by the steam explosion-extraction process of BFA-Hamburg, Hamburg, Federal Republic of Germany. A differential utilization of various molecular-weight fractions by several thermophilic anaerobic bacteria was determined during their growth on the hemicellulose preparations.
Clostridium thermocellum
(60°C) first utilized the high-molecular-weight fractions (polymerization degree of 15 to 40 xylose units). Xylose and xylooligomers of
n
= 2 to 5 accumulated while
C. thermocellum
was not growing, as evident from the fermentation products formed. Whereas the xylan was hydrolyzed and the small oligoxylans were utilized after more than 100 h of incubation, xylose was not significantly utilized. In contrast to this,
C. thermohydrosulfuricum
(70°C) and
Thermoanaerobium brockii
(70°C) utilized xylose first and then xylooligomers of
n
= 2 to 5, but xylooligomers of
n
greater than 6 were only slowly utilized.
Thermoanaerobacter ethanolicus
(70°C),
Thermobacteroides acetoethylicus
(70°C), and
C. thermosaccharolyticum
(60°C) utilized xylose preferentially. Xylooligomers of
n
= 2 to 5 and
n
= 6 and greater were apparently concomitantly utilized without significant differences. In contrast to
C. thermocellum
, the non-cellulolytic organisms grew during xylan hydrolysis, producing ethanol, lactate, acetate, CO
2
, and H
2
.
Isolation and characterization of Pediococcus halophilus from salted anchovies (Engraulis anchoita)
Authors: Villar M , de Ruiz Holgado A P , Sanchez J J , Trucco R E , Oliver G
Published: January 2020

The presence of bacteria in salted anchovies during and at the end of the curing process was investigated. Attempts to isolate bacteria under aerobic or anaerobic conditions led to the isolation of only bacteria of the genus Pediococcus which were identified as Pediococcus halophilus. The isolates correspond to a rather heterogeneous group in which some of the members differ in some biochemical tests from the types described in the literature.
Degradation of halogenated aliphatic compounds by Xanthobacter autotrophicus GJ10
Authors: Janssen D B , Scheper A , Dijkhuizen L , Witholt B
Published: January 2020

A bacterium that is able to utilize a number of halogenated short-chain hydrocarbons and halogenated carboxylic acids as sole carbon source for growth was identified as a strain of Xanthobacter autotrophicus. The organism constitutively produces two different dehalogenases. One enzyme is specific for halogenated alkanes, whereas the other, which is more heat stable and has a higher pH optimum, is specific for halogenated carboxylic acids. Haloalkanes were hydrolyzed in cell extracts to produce alcohols and halide ions, and a route for the metabolism of 1,2-dichlorethane is proposed. Both dehalogenases show a broad substrate specificity, allowing the degradation of bromine- and chlorine-substituted organic compounds. The results show that X. autotrophicus may play a role in the degradation of organochlorine compounds and that hydrolytic dehalogenases may be involved in the microbial metabolism of short-chain halogenated hydrocarbons in microorganisms.
General Method for the Identification of Plasmid Species in Fast-Growing Soil Microorganisms
Authors: Plazinski Jacek , Cen Ying H. , Rolfe Barry G.
Published: January 2020

Using a horizontal gel electrophoresis method, we demonstrated reproducibly the presence of indigenous plasmids in different
Rhizobium, Agrobacterium
, and
Pseudomonas
strains. The method yields a large amount of plasmid DNA and is sensitive in detecting megaplasmids with molecular weights higher than 5 × 10
8
. In two
Rhizobium meliloti
strains, a megaplasmid other than the low-mobility plasmid already known was detected.
IncH plasmids in Escherichia coli strains isolated from broiler chicken carcasses
Authors: Chaslus-Dancla E , Lafont J P
Published: January 2020

Plasmids conferring tellurite resistance were transferred at low temperature (27 degrees C) from Escherichia coli strains isolated from chicken carcasses at the time of slaughter and after storage. They belonged to group IncH, as evidenced by their large molecular weight and incompatibility with plasmid pIP233. E. coli strains contaminating chickens meat can thus represent a source of IncH plasmids in the food chain of humans.
Influence of adsorption time, rocking, and soluble proteins on the plaque assay of monodispersed poliovirus
Authors: Richards G P , Weinheimer D A
Published: January 2020

Factors that could affect adsorption of monodispersed poliovirus to cell culture monolayers were evaluated. These included varying the virus adsorption period under static and nonstatic (rocked) conditions and altering the rocking rate. The effects of several soluble proteins on plaque formation, enumeration, and size were also evaluated. Rocking involved the mechanical spread of viruses over cell culture monolayers for 1 to 4 h. Rocked cultures exhibited significantly higher (P less than 0.05) plaque counts than corresponding static cultures. Optimal plaque counts were obtained after a 2-h adsorption period with rocking; increasing the period to 4 h did not significantly increase PFU. Optimal counts were not obtained until greater than or equal to 4 h with static adsorption. Plaque counts were not affected by increasing the rocking rate above one oscillation per minute, but a slower rocking rate resulted in a significant decrease in plaques. Adsorption of poliovirus in the presence of 3% solutions of beef and meat extracts, acid-precipitated oyster protein, two brands of skim milk, and 3 and 10% fetal bovine serum was compared with adsorption in protein-free controls. Significant reductions (P less than 0.05) in plaque counts occurred with one brand of skim milk, whereas 3% beef extract yielded highly significant reductions (P less than 0.01) in plaque counts and appreciable decreases in plaque sizes. Salinities of protein-containing virus inocula were high for beef and meat extracts but somewhat below physiological levels for the remaining inocula. Beef extract-associated reductions in PFU were eliminated after the extracts were dialyzed. Plaque reductions were associated with dialyzable components of the beef extract but not with the inoculum salinity.
Fluorometric determination of the DNA concentration in municipal drinking water
Authors: McCoy W F , Olson B H
Published: January 2020

DNA concentrations in municipal drinking water samples were measured by fluorometry, using Hoechst 33258 fluorochrome. The concentration, extraction, and detection methods used were adapted from existing techniques. The method is reproducible, fast, accurate, and simple. The amounts of DNA per cell for five different bacterial isolates obtained from drinking water samples were determined by measuring DNA concentration and total cell concentration (acridine orange epifluorescence direct cell counting) in stationary pure cultures. The relationship between DNA concentration and epifluorescence total direct cell concentration in 11 different drinking water samples was linear and positive; the amounts of DNA per cell in these samples did not differ significantly from the amounts in pure culture isolates. We found significant linear correlations between DNA concentration and colony-forming unit concentration, as well as between epifluorescence direct cell counts and colony-forming unit concentration. DNA concentration measurements of municipal drinking water samples appear to monitor changes in bacteriological quality at least as well as total heterotrophic plate counting and epifluorescence direct cell counting.
Transfer of plasmids pBR322 and pBR325 in wastewater from laboratory strains of Escherichia coli to bacteria indigenous to the waste disposal system
Authors: Gealt M A , Chai M D , Alpert K B , Boyer J C
Published: January 2020

Laboratory strains of Escherichia coli containing plasmid pBR325 (or pBR322) were coincubated with a mobilizer strain of E. coli (containing the conjugative plasmid R100-1) and a recipient strain of bacteria. Bacterial strains isolated from raw wastewater or a plasmid-free E. coli laboratory strain served as recipients. Transfer of the pBR plasmid into the recipient strain occurred during a 25-h coincubation in either L broth or sterilized wastewater; transfer frequencies were several orders of magnitude lower in wastewater. After the coincubation, recipients exhibited both plasmid-encoded phenotypic characteristics and an altered plasmid profile, as shown by agarose gel electrophoresis of purified plasmid DNA.
Application of flow cytometry to detection and characterization of Legionella spp
Authors: Tyndall R L , Hand R E , Mann R C , Evans C , Jernigan R
Published: January 2020

Flow cytometry, using fluorescein-bound specific antibodies and propidium iodide, was shown to be effective in detecting Legionella spp. in cooling tower waters. The procedure was quicker and less labor intensive than fluorescent microscopy. The use of these procedures also identified qualitative differences, perhaps related to infectivity, in Legionella populations.
Simplified Procedure for Recovery of Lignin Acidolysis Products for Determining the Lignin-Degrading Abilities of Microorganisms
Authors: Pometto Anthony L. , Crawford Don L.
Published: January 2020

A simplified procedure for the identification and measurement of single-ring aromatic products of lignin acidolysis is described. The procedure employed a 6-h hydrolysis of spruce milled wood lignin in acidic dioxane at 87°C, followed by a series of organic extractions to recover acidolysis products which were quantified by gas chromatography of trimethylsilyl derivatives. Complex gel permeation chromatography procedures utilized by other workers were avoided in the modified procedure, but equivalent results were obtained. The simplified procedure was utilized to hydrolyze sound and actinomycete-decayed spruce milled wood lignins and was shown to be useful as a technique for the rapid screening of microorganisms for their ability to alter lignin.
Filamentous sulfur bacteria of activated sludge: characterization of Thiothrix, Beggiatoa, and Eikelboom type 021N strains
Authors: Williams T M , Unz R F
Published: January 2020

Seventeen strains of filamentous sulfur bacteria were isolated in axenic culture from activated sludge mixed liquor samples and sulfide-gradient enrichment cultures. Isolation procedures involved plating a concentrated inoculum of washed filaments onto media containing sulfide or thiosulfate. The isolates were identified as Thiothrix spp., Beggiatoa spp., and an organism of uncertain taxonomic status, designated type 021N. All bacteria were gram negative, reduced nitrate, and formed long, multicellular trichomes with internal reserves of sulfur, volutin, and sudanophilic material. Thiothrix spp. formed rosettes and gonidia, and four of six strains were ensheathed. Type 021N organisms utilized glucose, lacked a sheath, and differed from Thiothrix spp. in several aspects of cellular and cultural morphology. Beggiatoa spp. lacked catalase and oxidase, and filaments were motile. Biochemical and physiological characterization of the isolates revealed important distinguishing features between the three groups of bacteria. Strain differences were most evident among the Thiothrix cultures. A comparison of the filamentous sulfur bacteria with freshwater strains of Leucothrix was made also.
Mechanism of action of aflatoxin B1 in Bacillus megaterium
Authors: Tiwari R P , Dham C K , Bhalla T C , Saini S S , Vadehra D V
Published: January 2020

Bacillus megaterium cells from various growth phases were equally susceptible to the lethal effects of aflatoxin B1. Known surfactants (EDTA and Tween-80) accentuated the effects of aflatoxin B1. Viability and inulin uptake in aflatoxin B1-exposed cells decreased considerably. The effect was concentration dependent. A straight-line relationship observed in the death curve indicated a single target for aflatoxin B1 action in B. megaterium. Leakage of intracellular constituents in B. megaterium was also concentration dependent, and this can be related to the extent of cell membrane damage.
Effect of Colloidal Materials on Cellulase Production by
Trichoderma reesei
Rut-C30
Authors: Duff Sheldon J. B. , Cooper David G. , Fuller O. Maynard
Published: January 2020

The addition of positively charged colloidal materials to the growth medium markedly increased the concentration of cellulase enzymes produced by
Trichoderma reesei
Rut-C30. Filter paper activities of up to 4 and 13 IU/ml have been achieved by the addition of colloidal materials, using 3% lactose and 3% cellulose, respectively, as a substrate. The particles exert their effect by binding soluble sugars and slowing their uptake by the organism.
Adaptation to High-Intensity, Low-Wavelength Light among Surface Blooms of the Cyanobacterium
Microcystis aeruginosa
Authors: Paerl Hans W. , Bland Patricia T. , Bowles N. Dean , Haibach Mark E.
Published: January 2020

Natural populations of the nuisance bloom cyanobacterium
Microcystis aeruginosa
obtained from the eutrophic Neuse River, N.C., revealed optimal chlorophyll
a
-normalized photosynthetic rates and resistance to photoinhibition at surface photosynthetically active radiation (PAR) intensities. At saturating PAR levels these populations exhibited higher photosynthetic rates in quartz than in Pyrex vessels. Eucaryotic algal populations obtained from the same river failed to counteract photoinhibition. At saturating PAR levels, such populations generally yielded lower photosynthetic rates in quartz containers than they did in Pyrex containers. Cultivation of natural
Microcystis
populations under laboratory conditions led to physiologically distinct populations which had photoinhibitory characteristics similar to those of other cultured cyanobacterial and eucaryotic algae. Our findings indicate that (i) photosynthetic production among natural surface populations is best characterized and quantified in quartz rather than Pyrex incubation vessels; (ii) extrapolation of natural photoinhibitory trends from laboratory populations is highly subjective to culture and PAR histories and may yield contradictory results; and (iii) buoyant surface-dwelling populations, rather than exhibiting senescence, are poised at optimizing PAR utilization, thereby maintaining numerical dominance in eutrophic waters when physico-chemical conditions favor bloom formation.
Evaluation of nongermicidal handwashing protocols for removal of transient microbial flora
Authors: Vesley D , Lillquist D R , Le C T
Published: January 2020

A method has been described which can compare the efficacy of different nongermicidal handwashing protocols for removal of transient microbial flora without the necessity of establishing or relying on a previously determined baseline for an individual subject. The wash effluent is collected, and colony counts for the effluent reflect the number removed by the wash protocol. A second standard wash in a handwashing machine is performed, and the test criterion is the percent removed in the test wash based on the sum of total CFU recovered from the two washes. The method was used to compare an 8-s cycle for a newly developed handwashing machine with a conventional 15-s Ivory soap wash. When machine pressure was adequate (42 lb/in2), there was no statistically significant difference in the percent removal of transient flora by the two methods (48.8% from the machine versus 45.1% from the Ivory soap wash). At 32 lb/in2, the Ivory soap wash recovered 60.3%, whereas the machine recovered 45.1%.
Molecular cloning of Bacillus sphaericus penicillin V amidase gene and its expression in Escherichia coli and Bacillus subtilis
Authors: Olsson A , Hagström T , Nilsson B , Uhlén M , Gatenbeck S
Published: January 2020

The Bacillus sphaericus gene coding for penicillin V amidase, which catalyzes the hydrolysis of penicillin V to yield 6-aminopenicillanic acid and phenoxyacetic acid, has been isolated by molecular cloning in Escherichia coli. The gene is contained within a 2.2-kilobase HindIII-PstI fragment and is expressed when transferred into E. coli and Bacillus subtilis. The expression in B. subtilis carrying the recombinant plasmid is approximately two times higher than in the original B. sphaericus strain. A comparison of the purified enzyme from B. sphaericus and the expressed gene product in E. coli minicells suggests that the native enzyme consists of four identical subunits, each with a molecular weight of 35,000.
Impact of Nitrogen and Phosphorus on [
14
C]Lignocellulose Decomposition by Stream Wood Microflora
Authors: Aumen Nicholas G. , Bottomley Peter J. , Gregory Stan V.
Published: January 2020

Nutritional and physical factors affecting the decomposition of [
14
C]lignocellulose prepared from Douglas fir (
Pseudotsuga menziesii
) were examined by incubating the labeled substrate with homogenized surface wood scrapings obtained from a Douglas fir log in a Pacific Northwest stream. Incubations were conducted in distilled water, in stream water collected from four different sources, or in a defined mineral salts solution with or without supplemental N (KNO
3
). Decomposition rates of [
14
C]lignocellulose, as measured by
14
CO
2
evolution, were greater in each of the four filter-sterilized sources of stream water than in distilled water alone. Decomposition experiments conducted in stream water media with the addition of defined mineral salts demonstrated that [
14
C]cellulose decomposition was stimulated 50% by the addition of either KNO
3
or KH
2
PO
4
/K
2
HPO
4
and further enhanced (167%) by a combination of both. In contrast, [
14
C]lignin decomposition was stimulated (65%) only by the addition of both N and P. Decomposition of [
14
C]lignocellulose was greatest when supplemental KNO
3
was supplied in concentrations of at least 10.0 mg of N liter
−1
but not increased further by higher concentrations. The decomposition of [
14
C]lignocellulose increased as the incubation temperature was raised and NO
3
−1
-N supplementation further increased these rates between three-and sevenfold over the range of temperatures examined (5 to 22°C). Accumulation of NH
4
+
(2 to 4 mg of N liter
−1
) was always observed in culture filtrates of incubations which had been supplemented with KNO
3
, the quantity being independent of NO
3
−
concentrations ≥ 10 mg of N liter
−1
. The role of supplemental NO
3
−
in the decomposition of [
14
C]lignocellulose is discussed in relation to wood decomposition and the low concentrations of N found in stream ecosystems of the Pacific Northwest.
Direct immunoassay for detection of salmonellae in foods and feeds
Authors: Anderson J M , Hartman P A
Published: January 2020

A direct enzyme immunoassay (EIA) with polyclonal antibodies was developed for detecting salmonellae in foods and feeds. Salmonella cells were attached firmly to the wells of polystyrene microtitration plates with a capture-antibody technique. Spicer-Edwards anti-H immunoglobulin G was bound to protein A-beta-D-galactosidase to serve as the signal; 4-methylumbelliferyl-beta-D-galactoside was used as the substrate. The sensitivity threshold was 10(7) cells per ml. Direct EIA, indirect EIA, and pure-culture techniques were compared by using 48 samples of naturally contaminated foods and feeds. The direct EIA was more sensitive than the indirect EIA or pure-culture technique. Food samples were analyzed within 3 working days, and 32 samples were tested simultaneously in a single 96-well microtitration plate. False-positive or false-negative results did not pose a problem. This direct EIA is sensitive, rapid, and amenable to automation.
Comparison of Methane Production Rate and Coenzyme F
420
Content of Methanogenic Consortia in Anaerobic Granular Sludge
Authors: Dolfing Jan , Mulder Jan-Willem
Published: January 2020

The coenzyme F
420
content of granular sludge grown on various substrates and substrate combinations was measured, and the potential of the sludge to form methane (maximum specific methane production rate) from hydrogen, formate, acetate, propionate, and ethanol was determined. The F
420
content varied between 55 nmol g of volatile suspended solids (VSS)
−1
for sludge grown on acetate and 796 nmol g of VSS
−1
for sludge grown on propionate. The best correlation was found between the F
420
content and the potential activity for methane formation from formate; almost no correlation, however, was found with acetate as the test substrate. The ratio between the potential methanogenic activities (
q
ch
4
) of sludges grown on various substrates and their F
420
content was in general highest for formate (48.2 μmol of CH
4
μmol of F
420
−1
min
−1
) and lowest for propionate (6.9 μmol of CH
4
μmol of F
420
−1
min
−1
) as test substrates. However, acetate-grown granular sludge with acetate as test substrate showed the highest ratio, namely, 229 μmol of CH
4
μmol of F
420
−1
min
−1
. The data presented indicate that the F
420
content of methanogenic consortia can be misleading for the assessment of their potential acetoclastic methanogenic activity.
Type 1 Fimbria-Mediated Adhesion of Enteric Bacteria to Grass Roots
Authors: Haahtela Kielo , Tarkka Eveliina , Korhonen Timo K.
Published: January 2020

Type 1 fimbriae of
Klebsiella pneumoniae
and
Enterobacter agglomerans
mediated bacterial adhesion to the roots of bluegrass,
Poa pratensis.
Purified, radiolabeled fimbriae bound to grass roots in vitro; binding was inhibited by α-methyl-
d
-mannoside or Fab fragments to the fimbriae. Anti-type 1 fimbriae Fab fragments and α-methyl-
d
-mannoside also inhibited adhesion of type 1-fimbriated bacteria to
P. pratensis
roots. It is proposed that associative nitrogen fixation by
Klebsiella
and
Enterobacter
strains also involves type 1 fimbriae, in addition to the type 3 fimbriae of
Klebsiella
spp. (T. K. Korhonen, E. Tarkka, H. Ranta, and K. Haahtela, J. Bacteriol. 155:860-865, 1983).
In Vitro Adhesion of N
2
-Fixing Enteric Bacteria to Roots of Grasses and Cereals
Authors: Haahtela Kielo , Korhonen Timo K.
Published: January 2020

Nitrogen-fixing
Klebsiella
and
Enterobacter
strains isolated from several plants were assayed for fimbriae and for adhesion to plant roots in vitro. All eight
Klebsiella
strains formed type 3 fimbriae, and five strains also formed type 1 fimbriae; all 21
Enterobacter
strains had type 1 fimbriae. Three strains of
Klebsiella
carrying either type 1, type 3, or no fimbriae were used as model organisms in developing an in vitro adhesion test. Adhesion was assayed with bacterial cells labeled with [
3
H]leucine. Fifteen N
2
-fixing strains and the three model strains were compared for adhesion to the roots of seven grasses and five cereals. Type 3-fimbriated
Klebsiella
strains adhered better than the other strains, and type 3 fimbriae appeared to be major adhesins for the
Klebsiella
strains. Although variations between plants were observed, no host specificity for bacterial adhesion was found.
Characterization of aquatic bacteria and cloning of genes specifying partial degradation of 2,4-dichlorophenoxyacetic acid
Authors: Amy P S , Schulke J W , Frazier L M , Seidler R J
Published: January 2020

Water samples from rivers, streams, ponds, and activated sewage were tested for the presence of bacteria which utilize 2,4-dichlorophenoxyacetic acid (2,4-D) as a sole source of carbon. Seventy percent of the attempted enrichments yielded pure cultures of 2,4-D-metabolizing bacteria. All but 1 of the 30 isolates were gram-negative rods, all but 2 were motile, and all were nonfermentative and oxidase and catalase positive. Nine isolates had DNA guanine-plus-cytosine values of 61.1 to 65 mol%. One isolate had a 67 mol% guanine-plus-cytosine value. The results suggest that these 2,4-D-metabolizing bacteria belong to the genus Alcaligenes. Fourteen of 23 isolates contained one or more detectable plasmids of about 20, 60, or 100 megadaltons. HindIII restriction fragment patterns showed these plasmids to be different from each other with one exception. Very similar restriction fragment patterns were revealed with a plasmid isolated from an Alcaligenes eutrophus strain obtained from Australia (pJMP397) and in an Alcaligenes sp. isolated in Oregon (pEML159). These two plasmids were about 56 megadaltons, had the same guanine-plus-cytosine value, were transmissable, and coded for 2,4-D metabolism and resistance to HgCl2. Hybridization of these two plasmids was demonstrated by using nick-translated 32P-labeled pJMP397. The vector pBR325 was used to clone HindIII fragments from pEML159. One cloned fragment of 14.8 megaldaltons expressed in Escherichia coli the ability to release 14CO2 from 2,4-D labeled in the acetate portion.
Identification of various T-2 toxin metabolites in chicken excreta and tissues
Authors: Visconti A , Mirocha C J
Published: January 2020

Gas chromatography-mass spectrometry was used to identify various T-2 toxin metabolites in chicken excreta and organs 18 h after intraperitoneal injection of the toxin. No trichothecenes were detected in the heart and kidneys, and only trace amounts were detected in the lungs. Most of the T-2 metabolites were found in the excreta, although considerable amounts were also found in the liver. In addition to the previously identified T-2 metabolites in chicken excreta (HT-2 toxin, 15 acetoxy T-2 tetraol, and T-2 tetraol), we found 3'-hydroxy HT-2 toxin (the major metabolite in excreta and organs), 3'-hydroxy T-2 toxin, 4-acetoxy T-2 tetraol, and trace amounts of 8-acetoxy T-2 tetraol, 3-acetoxy-3'hydroxy HT-2 toxin, and T-2 triol. Unmetabolized T-2 toxin and an unidentified isomer of T-2 tetraol monoacetate were also detected in the excreta. Most of the metabolites in the chicken are similar to those encountered in cultures of fungal species producing T-2 toxin. A comparison with T-2 toxin metabolism in the cow is also reported.
Glycosidases of the rumen anaerobic fungus Neocallimastix frontalis grown on cellulosic substrates
Authors: Pearce P D , Bauchop T
Published: January 2020

The rumen anaerobic fungus Neocallimastix frontalis was grown on cellulosic substrates, and the cellular distribution and types of glycosidases produced by the organism were studied. Fungal cultures were fractionated into extracellular, insoluble (membrane), and intracellular fractions and assayed for glycosidase activity by using Avicel, carboxymethylcellulose, xylan, starch, polygalacturonic acid, and the p-nitrophenyl derivatives of galactose, glucose, and xylose as substrates. Enzymic activity was highest in the extracellular fraction; however, the membrane fraction also displayed appreciable activity. The intracellular fraction was inactive towards all substrates. Polygalacturonic acid was the only substrate not hydrolyzed by the active fractions, indicating that pectinase was absent. The results show that N. frontalis, a common rumen anaerobic fungus, produces enzymes for degrading cellulose and hemicellulose, key components of plant fiber.