bluuebunny/crossref_metadata_2025 huggingface dataset:
Simple method to demonstrate radiation-inducible radiation resistance in microbial cells
Authors: Tan S T , Maxcy R B
Published: January 2020

A simple method for detection of radiation-inducible radiation resistance was developed by irradiating aliquots (0.01 ml) of cell suspension on agar plates. Part of each experimental plate was subjected to an induction treatment, and subsequent radiation resistance was compared with that of untreated cells on the same plate. The UV radiation resistance of a Micrococcus sp. was increased approximately 1.6 times by an induction treatment. This simple procedure of irradiating cells in a "fixed" position on agar avoided washing, centrifugation, and cell enumeration required in traditional methods.
Kinetic Concepts for Measuring Microbial Rate Constants: Effects of Nutrients on Rate Constants
Authors: Paris D. F. , Rogers J. E.
Published: January 2020

We investigated the effect of preincubation of environmental waters amended with inorganic nutrients (nitrogen, phosphorus, and traces of iron and magnesium) on the kinetics of the microbial transformation of phenol, propanil, propyl ester of (2,4-dichlorophenoxy)acetic acid, methyl parathion, Ronnel, and methoxychlor in pond and river waters. No effect on the second-order rate constants for these compounds was observed, although there was an increase in the bacterial populations and the pseudo-first-order rate constants. The use of nutrient-amended waters could be a useful tool for estimating second-order rate constants for an expanded number of compounds. This technique would provide a larger data base for predicting the behavior of xenobiotic compounds in the environment by using currently available mathematical models.
Solid Medium for Culturing Black Smoker Bacteria at Temperatures to 120°C
Authors: Deming Jody W. , Baross John A.
Published: January 2020

A solid, highly thermostable medium, based on the new gelling agent GELRITE, was devised to facilitate the culturing of extremely thermophilic microorganisms from submarine hydrothermal vents. The medium remained solid at temperatures to 120°C at vapor pressures and hydrostatic pressures to 265 atm. It proved useful to its maximum tested limits in isolating colonies of black smoker bacteria from hydrothermal fluids recently collected at the Juan de Fuca Ridge in the Pacific Ocean.
Nitrification Rates in the Baltic Sea: Comparison of Three Isotope Techniques
Authors: Enoksson Viveka
Published: January 2020

Simultaneous measurements of nitrification in the Baltic Sea were made at 10- to 30-m intervals in the months of June and November by three isotope techniques: [
15
N]nitrate dilution, N-serve sensitive [
14
C]bicarbonate incorporation, and [
15
N]ammonium oxidation to nitrite and nitrate. Nitrification rates of 1 to 280 nmol liter
−1
day
−1
were recorded, and each method showed that the highest rates of nitrification occurred below the halocline. Even in the presence of ammonium, dark incubations of mixed layer (above ca. 50 m) waters never yielded nitrification rates exceeding 45 nmol liter
−1
day
−1
. The rates measured by the ammonium oxidation method were two- to sevenfold greater than those obtained by
14
C incorporation or
15
N dilution. The merits of each technique are discussed, and it is suggested that the [
15
N]ammonium oxidation method should be used in conjunction with the [
14
C]bicarbonate incorporation method.
Pathogenicity of a fungus resembling Wangiella dermatitidis isolated from edible mushrooms
Authors: Kazanas N
Published: January 2020

A fungus resembling the human pathogen Wangiella dermatitidis (Kano) McGinnis, a dematiaceous hyphomycete, was recovered from imported desiccated "black fungus" mushrooms (Auricularia polytrichia (Mont.) Sacc.), a food item popular in Far Eastern cuisine. Except for its conidia, which are mostly reniform to allantoid rather than ovoid as is characteristic for W. dermatitidis, and the undecided mode of conidiogenesis, the isolate closely resembles W. dermatitidis in gross and microscopic morphology, thermotolerance, and general and neurotrophic infectivity patterns in mice injected intraperitoneally. The foodborne isolate was also infective for infant mice inoculated by oral intubation. The systematic position of the isolate is still under investigation. There has been no previous report of W. dermatitidis or of a fungus resembling it occurring in or on foods or of the infectivity of a fungus for a mammalian host by oral intubation.
Existence of a novel enzyme, pyrroloquinoline quinone-dependent polyvinyl alcohol dehydrogenase, in a bacterial symbiont, Pseudomonas sp. strain VM15C
Authors: Shimao M , Ninomiya K , Kuno O , Kato N , Sakazawa C
Published: January 2020

A novel enzyme, pyrroloquinoline quinone (PQQ)-dependent polyvinyl alcohol (PVA) dehydrogenase, was found in and partially purified from the membrane fraction of a PVA-degrading symbiont, Pseudomonas sp. strain VM15C. The enzyme required PQQ for PVA dehydrogenation with phenazine methosulfate, phenazine ethosulfate, and 2,6-dichlorophenolindophenol as electron acceptors and did not show PVA oxidase activity leading to H2O2 formation. The enzyme was active toward low-molecular-weight secondary alcohols rather than primary alcohols. A membrane-bound PVA oxidase was also present in cells of VM15C. Although the purified oxidase showed a substrate specificity similar to that of PQQ-dependent PVA dehydrogenase and about threefold-higher PVA-dehydrogenating activity with phenazine methosulfate or phenazine ethosulfate than PVA oxidase activity with H2O2 formation, it was shown that the enzyme does not contain PQQ as the coenzyme, and PQQ did not affect its activity. Incubation of the membrane fraction of cells with PVA caused a reduction in the cytochrome(s) of the fraction.
Interaction of albumin and phospholipid:cholesterol liposomes in growth of Mycoplasma spp
Authors: Cluss R G , Somerson N L
Published: January 2020

Mycoplasma spp., sterol and fatty acid auxotrophs, are conventionally grown in complex media containing high concentrations of serum. Serum supplies the required lipids, but its presence complicates studies on the metabolism and antigenicity of mycoplasmas as well as the membrane dynamics of these organisms. In the present work, fetal bovine serum was replaced with dilipidated albumin and liposomes containing high concentrations of cholesterol. The liposomes were produced from phosphatidylcholine which contained other lipid species, including phosphatidylethanolamine, phosphatidylglycerol, and cholesterol. Other liposomes containing cholesterol and one phospholipid yielded significantly less growth of Mycoplasma gallisepticum, indicating that several phospholipids are required to achieve growth levels comparable to those obtained with complex medium. The sources and concentrations of cholesterol, albumin, phosphatidylcholine, and other phospholipids and the interactions among them were important affectors of mycoplasmal growth. Optimal lipid and albumin conditions established for M. gallisepticum were then used to propagate five diverse Mycoplasma spp. to growth levels which equalled or surpassed those obtained with medium containing 17% fetal bovine serum.
Purification and Characterization of Benzonitrilases from
Arthrobacter
sp. Strain J-1
Authors: Bandyopadhyay Amal Kumar , Nagasawa Toru , Asano Yasuhisa , Fujishiro Kinya , Tani Yoshiki , Yamada Hideaki
Published: January 2020

We found two kinds of benzonitrilases, designated benzonitrilases A and B, in a cell extract of
Arthrobacter
sp. strain J-1 grown on benzonitrile as a sole carbon and nitrogen source. Benzonitrilases A and B were purified approximately 409-fold and 38-fold, respectively. Purified benzonitrilase A appeared to be homogeneous according to the criteria of polyacrylamide gel electrophoresis. Both the enzymes hydrolyzed benzonitrile to benzoic acid and ammonia without forming benzamide as an intermediate. The molecular weights of benzonitrilases A and B were found to be 30,000 and 23,000, respectively. The subunit molecular weight of benzonitrilase A was the same as its molecular weight. The isoelectric points of benzonitrilases A and B were 4.95 and 4.80, respectively. The optimum temperature and pH, respectively, for benzonitrilase A were 40°C and 8.5, and those for benzonitrilase B were 30°C and 7.5. The
K

m

values for benzonitrilases A and B were 6.7 mM and 4.5 mM, respectively. Both the enzymes degraded
p
-tolunitrile, 4-cyanopyridine, and
p
-chlorobenzonitrile, but they did not attack aliphatic nitriles or amides. Both the enzymes were inhibited by thiol reagents.
Methods for isolating Campylobacter jejuni from low-turbidity water
Authors: Blaser M J , Cody H J
Published: January 2020

Membrane filtration methods were developed and evaluated for the quantitative recovery of Campylobacter jejuni from environmental waters of low turbidity. The best procedure studied involved passaging the test water through a filter (pore size, 0.45 micron) and plating it facedown on Campylobacter-selective agar. The filter was removed after overnight incubation, and the plate was streaked for isolation and then reincubated. This method, with or without prefiltration through 5.0- and 0.6-micron-pore-size membranes consistently resulted in the recovery of 30 C. jejuni CFU/250 ml of seeded natural waters. The other methods, plating the final filter face-up or preincubation of the filter in an enrichment medium, were not as sensitive. The technique described above could be useful in the routine monitoring of finished waters for C. jejuni or during investigations of suspected waterborne outbreaks for water of low turbidity.
Biodegradation of tert-butylphenyl diphenyl phosphate
Authors: Heitkamp M A , Freeman J P , Cerniglia C E
Published: January 2020

The biodegradation of tert-butylphenyl diphenyl phosphate (BPDP) was examined in microcosms containing sediment and water from five different ecosystems as part of our studies to elucidate the environmental fate of phosphate ester flame retardants. Biodegradation of [14C]BPDP was monitored in the environmental microcosms by measuring the evolution of 14CO2. Over 37% of BPDP was mineralized after 8 weeks in microcosms from an ecosystem which had chronic exposure to agricultural chemicals. In contrast, only 1.7% of BPDP was degraded to 14CO2 in samples collected from a noncontaminated site. The exposure concentration of BPDP affected the percentage which was degraded to 14CO2 in microcosms from the two most active ecosystems. Mineralization was highest at a concentration of 0.1 mg of BPDP and was inhibited with 10- and 100-fold higher concentrations of BPDP in these microcosms. Indigenous heterotrophic and BPDP-utilizing microbial populations and phosphoesterase enzyme activities were highest in sediments which had the highest biodegradation of BPDP. We observed adaptive increases in both microbial populations and phosphoesterase enzymes in some sediments acclimated to BPDP. Chemical analyses of the residues in the microcosms indicated undegraded BPDP and minor amounts of phenol, tert-butylphenol, diphenyl phosphate, and triphenyl phosphate as biodegradation products. These data suggest that the microbial degradation of BPDP results from at least three catabolic processes and is highest when low concentrations of BPDP are exposed to sediment microorganisms of eutrophic ecosystems which have high phosphotri- and diesterase activities and previous exposure to anthropogenic chemicals.
Characterization of β-Glucosidase Activity in Intertidal Marine Sediments
Authors: King Gary M.
Published: January 2020

Glycoside derivatives of 4-methylumbelliferone (MUF) were used to characterize the polysaccharidase enzyme systems present in sediments from an intertidal mud flat. The formation of highly fluorescent MUF on hydrolysis of the various glycosides was determined at low substrate concentrations (<1 μM) and with short incubation periods (>5 min). The hydrolysis of MUF-β-
d
-glucose in sediments from depth intervals of 0 to 2 cm was insensitive to the presence of oxygen, dissolved sulfide, and iron; magnesium and calcium were stimulatory, however. A pronounced temperature optimum was observed at 40°C, a salinity optimum at 30‰, and a pH optimum at 8.5. Rates of hydrolysis were completely inhibited by the addition of mercuric chloride and sodium azide, but only partially inhibited by toluene and the specific β-glucosidase inhibitor δ-1,5-gluconolactone. The response to δ-1,5-gluconolactone suggested that about 50% of the observed hydrolysis of MUF-β-
d
-glucoside was due to exo- and endoglucanases. A wide variety of hydrolytic activities was observed, with at least some nonspecificity occurring in the case of MUF-β-
d
-fucoside. Depth profiles indicated maximal activity in surface sediments with a rapid decline below 2 cm. MUF-glycosides provided a convenlent tool for initial analyses of the dynamics and controls of polymer hydrolysis in marine sediments.
Inactivation of human and simian rotaviruses by chlorine
Authors: Vaughn J M , Chen Y S , Thomas M Z
Published: January 2020

The inactivation of simian rotavirus SA-11 and human rotavirus type 2 (Wa) by chlorine was compared at 4 degrees C by using single-particle virus stocks. Both virus types were usually more readily inactivated at pH 6.0 than at pH 8.0 when low chlorine concentrations (0.05 to 0.2 mg/liter) were used. A complete (5 log) reduction of both was obtained within 20 s at all pH levels when chlorine concentrations were increased to 0.3 mg/liter. Slight differences in the chlorine sensitivities of SA-11 and human rotavirus type 2 were noted but were not considered to be significant.
Effects of cysteine on growth, protease production, and catalase activity of Pseudomonas fluorescens
Authors: Himelbloom B H , Hassan H M
Published: January 2020

Cysteine inhibits growth of and protease production by Pseudomonas fluorescens NC3. Catalase activity in P. fluorescens NC3 was increased by cysteine. The addition of exogenous hydrogen peroxide did not increase catalase activity, thus suggesting a role for the endogenous generation of hydrogen peroxide via the autoxidation of cysteine.
Sensitivity of Moore sewer swabs for isolating Salmonella typhi
Authors: Sears S D , Ferreccio C , Levine M M
Published: January 2020

Moore swabs (sewer swabs) have been used successfully to culture pathogenic organisms from wastewater. Sensitivity seems to depend on the size of the waterway sampled as well as the number of organisms present. In Santiago, Chile, we placed 24 swabs into the sewers draining the homes of 10 known chronic carriers of typhoid. Swabs were positive for Salmonella typhi in 5 of the 10 households (50%) and 6 of the 24 swabs placed (25%).
Isolation of an antigenically unique methanogen from human feces
Authors: Misawa H , Hoshi T , Kitame F , Homma M , Nakamura K
Published: January 2020

A methanogenic bacterium with the morphological and physiological properties of the genus Methanobrevibacter was isolated from the feces of a Japanese man who excreted methane in his breath. Indirect immunofluorescence staining revealed that the isolate had an antigenicity unrelated to that of any known members of the genus Methanobrevibacter.
Fungal Metabolism of
n
-Alkylbenzenes
Authors: Fedorak Phillip M. , Westlake Donald W. S.
Published: January 2020

Isolates of
Paecilomyces, Verticillium, Beauveria
, and
Penicillium
species were tested for ability to metabolize a variety of
n
-alkylbenzenes. Minimum side chain lengths were required for metabolism of these substrates. These were C
4
for the
Paecilomyces
sp., C
8
for the
Verticillium
sp., and C
9
for the other two isolates. Growth on dodecylbenzene yielded benzoic and phenylacetic acids as transient intermediates, and these acids supported growth of the isolates.
Isolation of Campylobacter jejuni from retail mushrooms
Authors: Doyle M P , Schoeni J L
Published: January 2020

Campylobacter jejuni was isolated from 3 (1.5%) of 200 retail, polyvinyl chloride film-wrapped, fresh mushrooms. These results indicate that fresh mushrooms may indeed be a source of C. jejuni and support previously reported epidemiological data (Seattle-King County Department of Public Health, Surveillance of the Flow of Salmonella and Campylobacter in a Community, 1984) which revealed an an elevated relative risk of developing campylobacter enteritis in individuals who consume mushrooms.
Modulation of Affinity of a Marine Pseudomonad for Toluene and Benzene by Hydrocarbon Exposure
Authors: Law A. T. , Button D. K.
Published: January 2020

Trace (microgram liter
−1
) quantities of either toluene or benzene injected into an amino-acid-limited continuous culture of
Pseudomonas
sp. strain T2 were utilized immediately with affinities of 2.6 and 6.8 liters g of cells
−1
h
−1
, respectively, and yielded large amounts of organic products, carbon dioxide, and cells. The immediate utilization of hydrocarbons by hydrocarbon-deprived organisms helps to establish the nutritional value of nonpolar substrates in the environment. The observation of small Michaelis constants for toluene transport led to tests of metabolic competition between hydrocarbons; however, competitive inhibition of toluene metabolism was not found for benzene, naphthalene, xylene, dodecane, or amino acids. Benzene and terpenes were inhibitory at milligram liter
−1
concentrations. Toluene was metabolized by a strongly inducible system when compared with benzene. The capacity of toluene to effect larger affinity values increased with exposure time and concentration. The kinetics of induction suggested saturation phenomena, resulting in an induction constant,
K
ind
, of 96 μg of toluene liter
−1
. Maximal induction of amino-acid-grown cells required about 80 h, with the affinity reaching 317 liters g of cells
−1
h
−1
.
Identification of
Bradyrhizobium japonicum
Nodule Isolates from Wisconsin Soybean Farms
Authors: Kamicker Barbara J. , Brill Winston J.
Published: January 2020

One-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis was a more discriminating method than serotyping for identifying strains of
Bradyrhizobium japonicum.
Analysis of 543 nodule isolates from southeastern Wisconsin soybean farms revealed that none of the isolates were formed by any of the inoculant strains supplied by either of two inoculant companies. Twenty-nine indigenous strains and six inoculant strains were identified. Strain 61A76, the most competitive indigenous strain, formed 21% of the nodules. Indigenous strains 3030, 3058, 0336, and 3052 formed 15, 11, 9, and 9% of the nodules, respectively. These predominant strains were not associated with a particular soybean cultivar, soil type, or farm location.
Biotransformation of Unsaturated Long-Chain Fatty Acids by
Eubacterium lentum
Authors: Verhulst A. , Parmentier G. , Janssen G. , Asselberghs S. , Eyssen H.
Published: January 2020

Eubacterium lentum
(33 strains) isomerized the 12-
cis
double bond of C
18
fatty acids with
cis
double bonds at C-9 and C-12 into an 11-
trans
double bond before reduction of the 9-
cis
double bond. The 14-
cis
double bond of homo-γ-linolenic acid was isomerized by 29 strains into a 13-
trans
double bond. The same strains isomerized the 14-
cis
double bond of arachidonic acid into a 13-
trans
double bond and then isomerized the 8-
cis
double bond into a 7-
trans
double bond; the 13-
cis
double bond of 10-
cis
, 13-
cis
-nonadecadienoic acid was isomerized into a 12-
trans
double bond. None of these isomerization products was further reduced. Studies with resting cells showed optimal isomerization velocity at a linoleic acid concentration of 37.5 μM; higher concentrations were inhibitory. The pH optimum for isomerization was 7.5 to 8.5. The isomerase was inhibited by the sulfhydryl reagents iodoacetamide, bromoacetate, and
N
-ethylmaleimide and by the chelators EDTA and 1,10-phenanthroline.
Nutrient Limitation and Adaptation of Microbial Populations to Chemical Transformations
Authors: Lewis David L. , Kollig Heinz P. , Hodson Robert E.
Published: January 2020

Using field-collected periphyton and bacterial isolates, we determined adaptation lag periods for microbial transformation of
p
-cresol. Lag periods were longer for periphyton samples collected from field sites that were low in dissolved inorganic nitrogen and phosphorus. Moreover, lag periods decreased in samples amended with N or P. Our data suggest that adaptation lag periods for microbial transformation of low concentrations of chemicals may correlate with limiting nutrient concentrations, and this correlation may provide a basis for predictive mathematical modeling of lag periods.
Influence of Cyanobacterial Hyperscum on Heterotrophic Activity of Planktonic Bacteria in a Hypertrophic Lake
Authors: Robarts Richard D. , Zohary Tamar
Published: January 2020

The response of the planktonic heterotrophic bacterial community to the buildup and breakdown of a semipermanent, crusted, floating cyanobacterial mat, or hyperscum, that covered 1 to 2 ha was studied in a hypertrophic lake (Hartbeespoort Dam, South Africa). The initial response of bacteria in the main basin to the release of dissolved organic carbon (DOC) from the hyperscum 1 km away was an increase in activity per cell from 35 × 10
−12
to 153 × 10
−12
μg of C cell
−1
h
−1
for total cell counts, while activity per cell for metabolically active cells increased from 19 × 10
−11
to 85 × 10
−11
μg of C cell
−1
h
−1
. No major population growth occurred at this stage. Later, with the continuous supply of DOC from the hyperscum, total bacterial numbers increased from 6.6 × 10
6
to 20 × 10
6
cells ml
−1
, while the activity per cell declined. Metabolically active bacteria followed the same trend. Shorter-term DOC increases caused only increases in bacterial activity per cell. The data from Hartbeespoort Dam demonstrate an interesting and little-documented mechanism by which aquatic bacteria respond to increased DOC concentration and which may be universal for aquatic systems.
Protoplast transformation in coryneform bacteria and introduction of an alpha-amylase gene from Bacillus amyloliquefaciens into Brevibacterium lactofermentum
Authors: Smith M D , Flickinger J L , Lineberger D W , Schmidt B
Published: January 2020

The goal of this study was to investigate the likelihood of developing useful transformation systems for coryneform bacteria. Two species of coryneform bacteria, Brevibacterium lactofermentum and Corynebacterium lilium, were transformed with chimeras constructed from pUB110 and a cryptic coryneform plasmid (pGX1901). C. lilium protoplasts were also efficiently transfected with phage CS1 DNA. High transformation and transfection frequencies were obtained after only 2 min of lysozyme treatment of lysozyme-sensitive mutants. A series of experiments was also conducted to determine whether DNA from other species of important industrial microbes from the genus Bacillus could be expressed in coryneform bacteria. Evidence of restriction of Bacillus subtilis DNA by B. lactofermentum was observed but could be overcome. A Bacillus amyloliquefaciens alpha-amylase gene (amyEBamP) was subcloned onto a plasmid able to replicate in B. lactofermentum. B. lactofermentum transformants for this plasmid expressed amylase activity and produced material cross-reactive to amylase antibody.
Excystation and culturing of human and animal Giardia spp. by using gerbils and TYI-S-33 medium
Authors: Wallis P M , Wallis H M
Published: January 2020

Mongolian gerbils were used as an animal model to excyst and host Giardia spp. isolated from meadow voles, dogs, beavers, and humans. Both cysts and trophozoites were used to establish infections. Gerbils were infected with Giardia duodenalis from beaver, dog, and human sources, and the trophozoites were extracted and cultured in Diamond TYI-S-33 medium. The use of gentamicin and ampicillin in the medium, coupled with treatment of gerbils with gentamicin before they were sacrificed, permitted the elimination of trophozoite purification techniques before culturing. An extract of whole bovine calf blood, CLEX, was substituted for fetal bovine serum in TYI-S-33 medium and was found to be both adequate and less expensive.
Role for Emulsan in Growth of
Acinetobacter calcoaceticus
RAG-1 on Crude Oil
Authors: Pines O. , Gutnick D.
Published: January 2020

When
Acinetobacter calcoaceticus
RAG-1 was grown together with an emulsan-deficient mutant on crude oil, only the emulsan-producing RAG-1 was found to grow, regardless of whether the medium was supplemented with emulsan. The results suggested that the cell-associated form of the bioemulsifier is the biologically active species required for growth on crude oil. A revertant of an emulsan-deficient strain was isolated which simultaneously regained the ability to produce both cell-associated and cell-free emulsan as well as the ability to grow on crude oil.
Comparison of Acridine Orange, Acriflavine, and Bisbenzimide Stains for Enumeration of Bacteria in Clear and Humic Waters
Authors: Bergström Irina , Heinänen Anne , Salonen Kalevi
Published: January 2020

In highly humic water, acridine orange precipitated with dissolved humic matter, resulting in such bright background fluorescence that no bacteria could be seen. With bisbenzimide staining, a similar precipitate was nonfluorescent but obscured many cells. An acriflavine staining method proved useful and reproducible both in clear and in humic waters. Fading of fluorescence was not a problem, and stained samples could be stored after preparation. The fluorescence of cells stained with acriflavine was weaker than that with acridine orange, making counting extremely small cells slightly more difficult with the former stain.
Recovery, growth, and production of heat-stable enterotoxin by Escherichia coli after copper-induced injury
Authors: Singh A , McFeters G A
Published: January 2020

Exposure of enterotoxigenic Escherichia coli strains to a sublethal concentration (0.75 mg/liter) of copper for 3 days at 4 degrees C induced sensitivity to deoxycholate (0.1%). When placed in a complex (brain heart infusion) or a defined amino acid salt medium, the copper-injured cells recovered their tolerance to deoxycholate in 3 and 6 h, respectively, and commenced active growth. Growth and heat-stable enterotoxin production of uninjured and copper-injured cells were studied in brain heart infusion medium. A slightly altered growth curve and an initial slow rate of toxin production were observed in injured cells when compared with those corresponding uninjured controls. However, maximum heat-stable enterotoxin levels in injured cultures were comparable to those produced by uninjured cells, suggesting that the enterotoxigenic potential of copper-injured cells was fully retained.
Evolved aniline catabolism in Acinetobacter calcoaceticus during continuous culture of river water
Authors: Wyndham R C
Published: January 2020

Adaptation of Acinetobacter calcoaceticus from river water to aniline depends on the dynamics of parent and mutant populations. The parent, Acinetobacter strain DON26 phenotype Ani0, was common in river water and assimilated aniline effectively at micromolar concentrations, but was inhibited at higher concentrations of aniline. The Ani0 phenotype was also characterized by a broad specificity for oxidation of chloroanilines by aniline-induced cells. The mutant Ani+ phenotype was represented by DON2, isolated from a population of less than 100 cells ml-1 in a mixed river water culture, and by DON261, isolated during continuous culture of DON26. Ani+ strains assimilated aniline at a greater maximum specific rate than the parent and were able to grow at concentrations of aniline greater than 16 mM. These strains cooxidized phenol after growth at high aniline concentrations, but showed reduced activity toward chloroanilines. These changes plus kinetic data, oxygen uptake data, and the results of auxanography indicate that the mutant has an increased activity and altered specificity of the initial enzyme in the aniline catabolic pathway. The parent strain, DON26, was at a selective advantage relative to the mutant at low concentrations of aniline, but was replaced by the mutant when aniline concentrations increased. Adaptation of the mixed river water community to aniline involved selection of both phenotypes. Reversion of the Ani+ to Ani0 phenotype occurred at a frequency of 10(-2) in the absence of aniline selection. Plasmid content was not altered during either acquisition or loss of the Ani+ phenotype. Adaptive changes in Acinetobacter spp. populations illustrate important differences in the catabolic activities of natural and pollutant selected strains.(ABSTRACT TRUNCATED AT 250 WORDS)
Comparative study of selective media for enumeration of Pseudomonas aeruginosa from water by membrane filtration
Authors: de Vicente A , Borrego J J , Arrabal F , Romero P
Published: January 2020

In the present study, mPA-D and mPA-E agar, modifications of mPA-C agar that reduce background fecal streptococci that interfere with the differentiation and enumeration of the Pseudomonas aeruginosa colonies grown in other mPA media, are proposed for use in analyzing natural water samples. In addition, the efficiencies of several culture media for the recovery of P. aeruginosa in water after membrane filtration and multiple-tube techniques are compared. The degree of selectivity, precision, efficiency, and sensitivity achieved with the proposed media exceeded that achieved by current methods. Furthermore, they yielded equal rates of accuracy and specificity. Incubation at 36 degrees C resulted in an improved recovery of stressed P. aeruginosa. In conclusion, we propose the use of mPA-D and mPA-E agar, both incubated at 36 degrees C for 24 to 48 h, for analyzing river water and seawater, respectively.
Virulence of Vibrio vulnificus strains from marine environments
Authors: Tison D L , Kelly M T
Published: January 2020

Vibrio vulnificus strains isolated from geographically diverse marine sources were compared with clinical isolates for phenotype and in vitro and in vivo production of virulence factors. There were no differences between environmental and clinical strains on the basis of biochemical characteristics or antimicrobial susceptibility patterns. Cytolysin and cytotoxin titers produced by environmental strains were generally comparable to those of clinical strains. Of 29 environmental isolates tested, 25 were pathogenic for mice. These data show that environmental V. vulnificus strains are phenotypically indistinguishable from clinical isolates and that approximately 90% of the environmental strains tested produced in vitro virulence factors and in vivo pathogenicity for mice comparable to those produced by clinical V. vulnificus isolates.
Comparison of membrane filter, multiple-fermentation-tube, and presence-absence techniques for detecting total coliforms in small community water systems
Authors: Jacobs N J , Zeigler W L , Reed F C , Stukel T A , Rice E W
Published: January 2020

Methods for detecting total coliform bacteria in drinking water were compared using 1,483 different drinking water samples from 15 small community water systems in Vermont and New Hampshire. The methods included the membrane filter (MF) technique, a 10-tube fermentation tube (FT) technique, and the presence-absence (P-A) test. Each technique was evaluated using a 100-ml drinking water sample. Of the 1,483 samples tested, 336 (23%) contained coliforms as indicated by either one, two, or all three techniques. The FT detected 82%, the P-A detected 88%, and the MF detected 64% of these positives. All techniques simultaneously detected 55% of the positives. Evaluation of the confirmation efficiency of the P-A technique showed 94% of the presumptive positives confirming as coliforms. Thirteen different species of coliforms were identified from the 37 tests in which the P-A was positive but the MF and FT were negative. The P-A test was simple to inoculate and interpret and was considerably more sensitive than the MF and slightly more sensitive than the FT in detecting coliforms in this type of drinking water supply.
Purification and Properties of β-
N
-Acetylhexosaminidase from
Mucor fragilis
Grown in Bovine Blood
Authors: Yamamoto Kenji , Tsuji Yasunobu , Matsushita Sawako , Kumagai Hidehiko , Tochikura Tatsurokuro
Published: January 2020

Mucor fragilis
grown on bovine blood powder as the sole carbon source abundantly produced β-
N
-acetylhexosaminidase. The enzyme activity was several times higher than that of a culture obtained with glucose medium. The enzyme had two different molecular weight forms. The high-molecular-weight form had somewhat higher β-
N
-acetylgalactosaminidase activity than the lower-molecular-weight enzyme which had β-
N
-acetylgalactosaminidase activity equivalent to about 40% of its β-
N
-acetylglucosaminidase activity. Bovine blood seemed to induce both enzymes, but
N
-acetylamino sugars specifically induced the low-molecular-weight form.
N
-Acetylgalactosamine had an especially marked effect on activity. The low-molecular-weight form of enzyme was purified from the culture filtrate by fractionation with ammonium sulfate and various column chromatographies. The purified enzyme was found to be homogeneous by polyacrylamide gel electrophoresis. The optimum pH was 4.0 to 5.0 for β-
N
-acetylglucosaminidase activity and 5.5 to 6.5 for β-
N
-acetylgalactosaminidase activity. The enzyme hydrolyzed natural substrates such as di-
N
-acetylchitobiose, tri-
N
-acetylchitotriose, and a glycopeptide obtained by modification of fetuin.
Improvement of an
l
-Leucine-Producing Mutant of
Brevibacterium lactofermentum
2256 by Genetically Desensitizing It to α-Acetohydroxy Acid Synthetase
Authors: Tsuchida Takayasu , Momose Haruo
Published: January 2020

Genetic improvement of
l
-leucine productivity in strain 218, an
ile
−
2-thiazolealanine-resistant mutant of
Brevibacterium lactofermentum
2256, was attempted. In strain 218, which produced 28 mg of
l
-leucine per ml from 13% glucose, α-isopropylmalate synthetase was genetically desensitized and derepressed to the effect of
l
-leucine, whereas α-acetohydroxy acid synthetase remained unaltered, although it could be derepressed phenotypically by limiting the isoleucine concentration in the culture. From strain 218 we isolated 103 mutants resistant to β-hydroxyleucine (4 mg/ml). Among these, three were found to produce mere
l
-leucine than the parent. The α-acetohydroxy acid synthetase of all three mutant strains was found to be genetically desensitized to all of the branched-chain amino acids
l
-isoleucine,
l
-valine, and
l
-leucine. The repression mechanism in α-acetohydroxy acid synthetase formation was the same as in the parent strain. The improved strains typically produced 34 mg of
l
-leucine per ml, the highest productivity ever reported.
Production and Characteristics of Avicel-Disintegrating Endoglucanase from a Protease-Negative
Humicola grisea
var.
thermoidea
Mutant
Authors: Hayashida Shinsaku , Mo Kaiguo
Published: January 2020

Mutational experiments were performed to decrease the protease productivity of
Humicola grisea
var.
thermoidea
YH-78 using UV light and
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine. A protease-negative mutant, no. 140, exhibited higher endoglucanase activity than the parent strain in mold bran culture at 50°C for 4 days. The culture extract rapidly disintegrated filter paper but produced a small amount of reducing sugar. About 30% of total endoglucanase activity in the extract was adsorbed onto Avicel. The electrophoretically homogeneous preparation of Avicel-adsorbable endoglucanase (molecular weight, 128,000) showed intensive filter-paper-disintegrating activity but did not release reducing sugar. The preparation also exhibited a highly synergistic effect with the cellulase preparation from
Trichoderma reesei
in the hydrolysis of microcrystalline cellulose. This endoglucanase was observed via scanning electron microscopy to disintegrate Avicel fibrils layer by layer from the surface, yielding thin sections with exposed chain ends. A mutant, no. 191, producing higher protease activity and an Avicel-unadsorbable, Avicel-nondisintegrating endoglucanase was isolated. The purified enzyme (molecular weight, 63,000) showed no disintegrating activity on filter paper and Avicel and a less synergistic effect with the
T. reesei
cellulase in hydrolyzing microcrystalline cellulose than did the former enzyme. Endoglucanase was therefore divided into two types, Avicel disintegrating and Avicel nondisintegrating.
Recovery and diversity of heterotrophic bacteria from chlorinated drinking waters
Authors: Maki J S , LaCroix S J , Hopkins B S , Staley J T
Published: January 2020

Heterotrophic bacteria were enumerated from the Seattle drinking water catchment basins and distribution system. The highest bacterial recoveries were obtained by using a very dilute medium containing 0.01% peptone as the primary carbon source. Other factors favoring high recovery were the use of incubation temperatures close to that of the habitat and an extended incubation (28 days or longer provided the highest counts). Total bacterial counts were determined by using acridine orange staining. With one exception, all acridine orange counts in chlorinated samples were lower than those in prechlorinated reservoir water, indicating that chlorination often reduces the number of acridine orange-detectable bacteria. Source waters had higher diversity index values than did samples examined following chlorination and storage in reservoirs. Shannon index values based upon colony morphology were in excess of 4.0 for prechlorinated source waters, whereas the values for final chlorinated tap waters were lower than 2.9. It is not known whether the reduction in diversity was due solely to chlorination or in part to other factors in the water treatment and distribution system. Based upon the results of this investigation, we provide a list of recommendations for changes in the procedures used for the enumeration of heterotrophic bacteria from drinking waters.
Schinus molle: a new source of natural fungitoxicant
Authors: Dikshit A , Naqvi A A , Husain A
Published: January 2020

The oil of Schinus molle exhibited the maximum fungitoxic activity during the screening of some essential oils against some common storage and animal pathogenic fungi. It showed absolute toxicity against animal pathogens and mild activity against storage fungi. The effective concentrations of the oil varied from 200 to 900 ppm. The toxicity of the oil persisted up to 80 degrees C and 90 days of storage but declined when autoclaved. It withstood heavy inoculum density. The oil exhibited a narrow range of activity and was found to be more effective than Multifungin, an antifungal drug. The oil was characterized by its various physicochemical properties. It was found to comprise 50 constituents. It appeared that some changes in the oil constituents during storage affected its fungitoxic potency.
Alginate Beads as Synthetic Inoculant Carriers for Slow Release of Bacteria That Affect Plant Growth
Authors: Bashan Yoav
Published: January 2020

Uniform synthetic beads were developed as carriers for the bacterial inoculation of plants. The beads are made of sodium alginate and skim milk and contain a large reservoir of bacterial culture which releases the bacteria at a slow and constant rate. The beads are biodegradable and produce no environmental pollution. The strength of the beads, the rate of bacterial release, and the time of their survival in the soil can be controlled by several hardening treatments. The final product, lyophilized beads, is simple to use and is applied to the seeds concomitantly with sowing. The released bacteria are available for root colonization immediately at seed germination. Dry beads containing bacteria can be stored at ambient temperature over a long period without loss of bacterial content; storage requires a limited space, and the quality control of a number of bacteria in the bead is simple. The level of plant inoculation with beads was similar to that with previously used peat inoculants, but the former method yielded more consistent results, as the frequency of inoculated plants was much higher. The former method provides a different approach for inoculation of plants with beneficial rhizosphere bacteria.
Degradation of pig gastric and colonic mucins by bacteria isolated from the pig colon
Authors: Stanley R A , Ram S P , Wilkinson R K , Roberton A M
Published: January 2020

Mucin degradation was studied with one Clostridium (RS42) and two Bacteroides (RS2 and RS13) strains isolated from the pig colon mucosa. Mucins from pig colon and stomach were prepared in their subunit forms for use as growth substrates, and the loss of the individual sugars from the mucins was measured after bacterial growth. Colonic mucin was more resistant to degradation than gastric mucin. The strains differed in their competence in degrading the mucins. Carbohydrate plus sulfate removal from gastric mucin varied from 63 to 76% for RS2, 37 to 46% for RS13, and 37 to 53% for RS42. All three strains removed more fucose (67 to 87%) and less sulfate (22 to 63%) than the average carbohydrate plus sulfate loss. Under the same conditions of growth, a mixed pig fecal culture removed 78% of sulfate and 96% of each sugar. Of the two major glycoprotein types present in the subunit pig gastric mucin preparation (R. A. Stanley, S. P. Lee, and A. M. Roberton, Biochim. Biophys. Acta 760:262-269, 1983), the less highly sulfated mucin was more susceptible to RS42 degradation. The degradation of gastric mucin by RS2 was not affected by glucose or high sulfate concentrations in the growth medium. The results show that the three strains of colon bacteria are capable of significant hydrolysis of mucin carbohydrate and that the extent of degradation seen with pure cultures is determined in part by the subunit glycoprotein type(s) present in the mucin.
Methodology for Estimating Numbers of Free-Living and Attached Bacteria in Estuarine Water
Authors: Clarke K. Robert , Joint Ian R.
Published: January 2020

A fundamental problem in estuarine microbiology studies is the accurate determination of the density in the water column of both free-living bacteria and those attached to suspended particulate matter. When a water sample is filtered and the filter is viewed by epifluorescence microscopy, counts can be made of the numbers of bacteria which are seen on the filter background (free-living) and those which appear to lie on sediment particles (both free-living and attached). With only the additional knowledge of the proportion of the filter area covered by particles (a quantity that is straightforwardly determined by stereological point counting), results from geometric probability were used to determine the expected number of bacteria which are hidden by particles and hence to provide an estimation scheme for the true densities of free-living and attached bacteria. Variance equations based on a Taylor series are given, and a partial check of the method is attempted with controlled mixtures of bacteria and sediment. An alternative procedure is also proposed, in which the natural attached/free-living ratio is altered by an intervention experiment, allowing an estimation which is less model dependent but more labor intensive. Both methods are applied to a series of samples from the Tamar estuary, United Kingdom, taken in April 1985. A notable conclusion is that there are always more free-living than attached bacteria in the water column throughout the estuary.
Phosphotransferase Activity in
Clostridium acetobutylicum
from Acidogenic and Solventogenic Phases of Growth
Authors: Hutkins Robert W. , Kashket Eva R.
Published: January 2020

Clostridium acetobutylicum
cells, when energized with fructose, transported and phosphorylated the glucose analog 2-deoxyglucose by a phosphoenolpyruvate-dependent phosphotransferase (PT) system. Butanol up to 2% did not inhibit PT activity, although its chaotropic effect on the cell membrane caused cellular phosphoenolpyruvate and the 2-deoxyglucose-6-phosphate to leak out. Cells harvested from the solventogenic phase of batch growth had a significantly lower PT activity than did cells from the acidogenic phase.
Selective-enrichment procedure for isolation of Listeria monocytogenes from fecal and biologic specimens
Authors: Doyle M P , Schoeni J L
Published: January 2020

A selective-enrichment procedure (SEP) was developed to isolate Listeria monocytogenes from fecal and biologic specimens. This procedure was compared with direct plating with McBride listeria agar and 2-, 4-, and 8-week cold-enrichment procedures in recovering L. monocytogenes from mouse fecal, liver, and brain specimens. Although the SEP occasionally did not isolate the organism from specimens proved positive by the other procedures, the SEP isolated L. monocytogenes from about two and five times as many specimens as the cold-enrichment and direct-plating procedures, respectively.
Cytopathology of pathogenic and nonpathogenic Naegleria species for cultured rat neuroblastoma cells
Authors: Marciano-Cabral F M , Fulford D E
Published: January 2020

The cytopathology for rat neuroblastoma cells (B-103) and the pathogenicity for B6C3F1 mice of four species of Naegleria have been compared. Both live amoebae and cell-free extracts of N. australiensis, N. fowleri, N. gruberi, and N. lovaniensis added to 51Cr-labeled B-103 cells caused release of radiolabel. All four species of Naegleria exhibited surface extensions termed food cups. Only N. fowleri and N. australiensis were pathogenic for mice. Electron microscopic observations of cultures of either N. australiensis or N. lovaniensis with B-103 cells established that the cytopathology involved lysis of the B-103 target cells.
Catabolism of Amino Acids by
Megasphaera elsdenii
LC1
Authors: Wallace R. John
Published: January 2020

The amino acids in an acid hydrolysate of casein were catabolized more extensively by
Megasphaera elsdenii
than those in an enzymic hydrolysate. Threonine and serine were most actively degraded, but no resultant increase in growth yield occurred. Branched-chain volatile fatty acid production, which increased as the dilution rate of a glucose-limited chemostat decreased, seemed to be associated with maintenance rather than with growth.
Analysis of
Rhizobium meliloti
Sym Mutants Obtained by Heat Treatment
Authors: Toro Nicolas , Olivares José
Published: January 2020

Deletions in the pSym megaplasmid of
Rhizobium meliloti
were produced at a high frequency, and their lengths varied according to incubation temperature. Morphological differentiation into large and small colonies occurred after heat treatment. Small colonies elicited pseudonodules on alfalfa roots.