bluuebunny/crossref_metadata_2025 huggingface dataset:
Specificity of
Bacillus thuringiensis
Delta-Endotoxin
Authors: Jaquet Fran�oise , H�tter Ralf , L�thy Peter
Published: January 2020

The insecticidal activity of the delta-endotoxins of 14
Bacillus thuringiensis
strains belonging to 12 subspecies was determined against
Pieris brassicae, Heliothis virescens
, and
Spodoptera littoralis.
Larvae of
P. brassicae
were highly susceptible to purified crystals of strains of
B. thuringiensis
subsp.
thuringiensis
and
B. thuringiensis
subsp.
morrisoni
, whereas
H. virescens
responded best to
B. thuringiensis
subsp.
kenyae
and
B. thuringiensis
subsp.
kurstaki.
The crystals of the
B. thuringiensis
subsp.
entomocidus
strain were the most potent against
S. littoralis.
It was shown that the solubility of the crystals within the gut of the three insect species is a first important step in the mode of action. Predissolution of the crystals especially enhanced the insecticidal activity against
H. virescens.
When in vitro-activated toxins were applied, the relative potency range varied greatly from one insect species to another. It can be concluded that at least three factors influence the potency of
B. thuringiensis
delta-endotoxins: the strain-related origin of the toxin, the degree of solubility of the crystals in the gut juice, and the intrinsic susceptibility of the insect to the toxin.
Detection of ochratoxin A in porcine kidneys by a monoclonal antibody-based radioimmunoassay
Authors: Rousseau D M , Candlish A G , Slegers G A , Van Peteghem C H , Stimson W H , Smith J E
Published: January 2020

By using an indirect enzyme-linked immunosorbent assay, eight monoclonal antibodies (MAbs) were selected. Mice were immunized with ochratoxin A that was conjugated to bovine serum albumin. The hybridoma cell line designated 10G2 was grown in tissue culture and as an ascites tumor. The MAb was characterized to be specific to ochratoxin A and of the immunoglobulin G (IgG) class. Subsequently, the ascites fluid of this hybridoma was used in a competitive solid-phase IgG radioimmunoassay on protein A-Sepharose CL-4B, with [14C]ochratoxin A as tracer. Porcine kidneys were extracted with 0.5% phosphoric acid in chloroform. A two-step cleanup was achieved on a Sep-Pak C18 cartridge and a Sep-Pak silica cartridge. Radioimmunoassay with MAbs coupled to protein A-Sepharose CL-4B allowed the detection of ochratoxin A in porcine kidneys at a concentration as low as 0.2 ng/g.
Preharvest aflatoxin contamination: effect of moisture and substrate variation in developing cottonseed and corn kernels
Authors: Lillehoj E B , Wall J H , Bowers E J
Published: January 2020

Variations in moisture and substrate in preharvest corn kernels and cottonseed were linked with the ability of Aspergillus parasiticus to infect the seed and produce aflatoxin. Osmotic pressures and moisture content (MC) levels of developing starch-rich corn kernels and lipid-rich cottonseed were determined. For in vivo studies, corn kernels and cottonseed were inoculated with A. parasiticus conidia and retained on plants through maturation. For in vitro studies, samples of corn kernels and cottonseed were collected at various stages, sterilized, inoculated, incubated for 2 weeks, and assayed for toxin. Aflatoxin levels were highest in corn kernels inoculated at 28 days postflowering (52% MC) in both the in vivo and in vitro tests. Toxin concentrations in cottonseed were greatest with inoculation at 35 days postflowering (70% MC) in seed retained on the plant, but toxin accumulation continued to increase with the maturity of the seed inoculated in cottonseed used in the in vitro trials. Moisture and substrate conditions in the midrange of seed development provided optimum conditions for fungal development and toxin production in seed retained on the plant.
Measurement of Surface Charge of Baculovirus Polyhedra
Authors: Small Deirdre A. , Moore Norman F.
Published: January 2020

The isoelectric points of three baculoviruses,
Trichoplusia ni
nuclear polyhedrosis virus (NPV),
T. ni
granulosis virus, and
Spodoptera littoralis
NPV were identified by cell electrophoresis. At neutral pH polyhedra were negatively charged.
T. ni
NPV polyhedra were reacted with a number of reagents which could potentially attach to or degrade their surface structure. This gave information on the components that contribute to the charge profile of
T. ni
NPV. This is discussed in relation to the use of polyhedra as biological control agents against insect pests.
Effects of chitin and its soluble derivatives on survival of Vibrio cholerae O1 at low temperature
Authors: Amako K , Shimodori S , Imoto T , Miake S , Umeda A
Published: January 2020

Chitin concentrations greater than 0.04% (wt/wt) protected cholera vibrios against killing at low temperature. This protective effect was detected with both the soluble form of chitin, glycol chitin, and the insoluble particulate form of chitin. Some amino acids or peptides also showed the same protective effect.
Purification and Characterization of Two Endoxylanases from
Clostridium acetobutylicum
ATCC 824
Authors: Lee Song F. , Forsberg Cecil W. , Rattray James B.
Published: January 2020

Two endoxylanases produced by
C. acetobutylicum
ATCC 824 were purified to homogeneity by column chromatography. Xylanase A, which has a molecular weight of 65,000, hydrolyzed larchwood xylan randomly, yielding xylohexaose, xylopentaose, xylotetraose, xylotriose, and xylobiose as end products. Xylanase B, which has a molecular weight of 29,000, also hydrolyzed xylan randomly, giving xylotriose and xylobiose as end products. Xylanase A hydrolyzed carboxymethyl cellulose with a higher specific activity than xylan. It also exhibited high activity on acid-swollen cellulose. Xylanase B showed practically no activity against either cellulose or carboxymethyl cellulose but was able to hydrolyze lichenan with a specific activity similar to that for xylan. Both xylanases had no aryl-β-xylosidase activity. The smallest oligosaccharides degraded by xylanases A and B were xylohexaose and xylotetraose, respectively. The two xylanases demonstrated similar

K
m

and
V
max
values but had different pH optima and isoelectric points. Ouchterlony immunodiffusion tests showed that xylanases A and B lacked antigenic similarity.
A Combined Immunofluorescence-DNA-Fluorescence Staining Technique for Enumeration of
Thiobacillus ferrooxidans
in a Population of Acidophilic Bacteria
Authors: Muyzer Gerard , de Bruyn Anke C. , Schmedding Diederik J. M. , Bos Piet , Westbroek Peter , Kuenen Gijs J.
Published: January 2020

An antiserum raised against whole cells of
Thiobacillus ferrooxidans
was allowed to react with a variety of acidophilic and nonacidophilic bacteria in an enzyme-linked immunosorbent assay and an indirect immunofluorescence assay. Both experiments demonstrated that the antiserum was specific at the species level. This preparation was used to evaluate the role of
T. ferrooxidans
in the microbial desulfurization process. Leaching experiments were performed, and the numbers of
T. ferrooxidans
cells and other bacteria were estimated by using a combined immunofluorescence-DNA-fluorescence staining technique that was adapted for this purpose. Nonsterile coal samples inoculated with
T. ferrooxidans
yielded high concentrations of soluble iron after 16 days. After this period, however,
T. ferrooxidans
cells could no longer be detected by the immunofluorescence assay, whereas the DNA-fluorescence staining procedure demonstrated a large number of microorganisms on the coal particles. These results indicate that
T. ferrooxidans
is removed by competition with different acidophilic microorganisms that were originally present on the coal.
Effect of Increased β-Glucosidase Activity on Virulence of
Erwinia amylovora
Authors: Kerppola Tom K. , Serwold-Davis Theresa , Gross Dennis C. , Kahn Michael L.
Published: January 2020

Plant tissues often contain β-glucosides that can be enzymatically hydrolyzed to produce toxic aglycones. It has been suggested that the low β-glucosidase activity found in
Erwinia amylovora
contributes to bacterial virulence by allowing the bacteria to infect plants that contain β-glucosides without inducing the formation of toxic aglycones. To test this suggestion, we created strains of
E. amylovora
which had high β-glucosidase activities and studied the ability of these strains to cause fire blight disease in pears (
Pyrus communis
). We isolated spontaneous mutants that were able to utilize β-glucosides as the sole carbon source and showed that one class had about 10 times as much β-glucosidase activity as the wild-type strain. In addition, we constructed several plasmids that carry the
Escherichia coli bgl
operon under the control of a transposon Tn
5
promoter that is expressed in
E. amylovora
. These plasmids were introduced in
E. amylovora
by transformation. Pathogenesis studies in immature Bartlett pear fruits, etiolated sprouts, and young shoots showed that a 100-fold increase in β-glucosidase activity does not interfere with normal development of fire blight disease in these model systems.
Comparative yields of T-2 toxin and related trichothecenes from five toxicologically important strains of Fusarium sporotrichioides
Authors: Marasas W F , Yagen B , Sydenham E , Combrinck S , Thiel P G
Published: January 2020

The range and comparative yields of T-2 toxin and related trichothecenes from five toxicologically important strains of Fusarium sporotrichioides, i.e., NRRL 3299, NRRL 3510, M-1-1, HPB 071178-13, and F-38, were determined. Lyophilized cultures of the five strains maintained in the International Toxic Fusarium Reference Collection were used to inoculate autoclaved corn kernels. Corn cultures were incubated at 15 degrees C for 21 days and analyzed for trichothecenes by thin-layer chromatography and capillary gas chromatography. All five strains produced T-2 toxin, HT-2 toxin, T-2 triol, and neosolaniol. Two strains also produced T-2 tetraol, and two others produced diacetoxyscirpenol. The highest producer of T-2 toxin (1,300 mg/kg), HT-2 toxin (200 mg/kg), T-2 triol (1.9 mg/kg), and neosolaniol (170 mg/kg) was NRRL 3510, which was originally isolated from millet associated with outbreaks of alimentary toxic aleukia in the USSR. The second highest producer of T-2 toxin (930 mg/kg) was NRRL 3299. The other three strains produced T-2 toxin at levels ranging from 130 to 660 mg/kg. Thus, the five strains differed considerably in the amounts of T-2 toxin and other trichothecenes produced under identical laboratory conditions. These strains are being maintained under optimal conditions for the preservation of Fusarium cultures and are available from the Fusarium Research Center, The Pennsylvania State University, University Park.
A new method to determine Giardia cyst viability: correlation of fluorescein diacetate and propidium iodide staining with animal infectivity
Authors: Schupp D G , Erlandsen S L
Published: January 2020

The viability of Giardia muris cysts was studied with the fluorogenic dyes fluorescein diacetate (FDA) and propidium iodide (PI). G. muris cysts were seen to fluoresce intensely green with FDA at an excitation wavelength of 450 to 490 nm. Cysts stained with PI fluoresced bright orange at an excitation wavelength of 450 to 490 nm and bright red at 545 to 546 nm. Examination of isolated G. muris cyst preparations stained with FDA-PI revealed that greater than 85% of the cysts stained green with FDA and less than 15% stained orange-red with PI. Using the mouse model for giardiasis, we inoculated FDA- or PI-stained cysts into neonatal mice. Feces were examined at days 3, 5, 8, and 11 postinoculation for the presence of cysts. Using 1,000 FDA-stained cysts as the inoculum, we detected cysts at days 5, 8, and 11 postinoculation in 19 of 19 mice, whereas a 50-fold greater dose of cysts produced infection in 27 of 27 mice at day 3 as well as at days 5, 8, and 11 postinoculation. Inoculation of mice with either 5,000 or 50,000 PI-stained G. muris cysts did not produce infection in any of the animals. Necropsy of mice infected with FDA-stained cysts showed trophozoites within the intestines. No trophozoites were detected within animals inoculated with PI-stained cysts. These results demonstrate that FDA-positive cysts are viable, as determined by infectivity, while PI-positive cysts are nonviable and incapable of producing G. muris infections in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)
Inactivation of human T-lymphotropic virus type III/lymphadenopathy-associated virus by formaldehyde-based reagents
Authors: Martin L S , Loskoski S L , McDougal J S
Published: January 2020

Neutral buffered Formalin, a fixative used in most pathology laboratories, was found to inactivate human T-lymphotropic virus type III/lymphadenopathy-associated virus. Preparations containing this virus with infectivity titers of greater than 10(5) were treated with 1% or greater neutral buffered Formalin; after treatment, virus was undetectable (titer, less than 10(1)). In addition, when infected phytohemagglutinin-stimulated lymphocytes were treated with paraformaldehyde, transmission of the virus to other such lymphocytes was eliminated.
Biodegradation of cresol isomers in anoxic aquifers
Authors: Smolenski W J , Suflita J M
Published: January 2020

The biodegradation of o-, m-, and p-cresol was examined in material obtained from a shallow anaerobic alluvial sand aquifer. The cresol isomers were preferentially metabolized, with p-cresol being the most easily degraded. m-Cresol was more persistent than the para-isomer, and o-cresol persisted for over 90 days. Biodegradation of cresol isomers was favored under sulfate-reducing conditions (SRC) compared with that under methanogenic conditions (MC). Slurries that were acclimated to p-cresol metabolism transformed this substrate at 18 and 330 nmol/h per g (dry weight) for MC and SRC, respectively. Inhibition of electron flow to sulfate reduction with 2.0 mM molybdate reduced p-cresol metabolism in incubations containing sulfate. When methanogenesis was blocked with 5 mM bromoethanesulfonic acid in incubations lacking sulfate, p-cresol catabolism was retarded. Under SRC 3.4 mol of sulfate was consumed per mol of p-cresol metabolized. The addition of sulfate to methanogenic incubations stimulated p-cresol degradation. Simultaneous adaptation studies in combination with spectrophotometric and chromatographic analysis of metabolites indicated that p-cresol was oxidized under SRC to p-hydroxybenzoate via the corresponding alcohol and aldehyde. This series of reactions was inhibited under sulfate-limited or aerobic conditions. Therefore, the primary catabolic event for p-cresol decomposition under SRC appears to involve the hydroxylation of the aryl methyl group.
Physicochemical stability and inactivation of human and simian rotaviruses
Authors: Meng Z D , Birch C , Heath R , Gust I
Published: January 2020

The effects of various physical and chemical treatments on the stability of a human serotype 1 rotavirus and simian agent 11 (SA11) were compared by using a fluorescence focus assay. The infectivity of both strains was retained after storage at room temperature for 14 days, 4 degree C for 22 days, and -20 degree C for 32 days; lyophilization; and treatment at pH 3 to 11. Both viruses were inactivated at pH 12, as was the human virus at pH 2, although this pH resulted in only partial inactivation of SA11. The human virus also appeared to be more sensitive than SA11 to the action of ether and chloroform. The infectivity of both viruses was lost after UV irradiation for 15 min and after treatment with 8% formaldehyde for 5 min, 70% (vol/vol) ethanol for 30 min, and 2% lysol, 2% phenol, and 1% H2O2 for 1 h each.
Use of membrane filters for measurement of mycobactericidal activity of alkaline glutaraldehyde solution
Authors: Collins F M
Published: January 2020

Bactericidal assays of 2% alkaline glutaraldehyde solution were carried out using Millipore membranes, and the rate of kill was compared with that of mycobacteria in suspension and on Penicylinder surfaces when using the methods recommended for the official tuberculocidal test. The rate of inactivation observed on the membrane filter surface was similar to that achieved using Penicylinders. The absence of visible colonies on the treated membranes provided a direct demonstration of sterility. The use of filter membranes in tuberculocidal tests provides a simple quantitative assay.
Nitrifying Bacteria in Wastewater Reservoirs
Authors: Abeliovich Aharon
Published: January 2020

Deep wastewater reservoirs are used throughout Israel to store domestic wastewater effluents for summer irrigation. These effluents contain high concentrations of ammonia (≤5 mM) that are frequently toxic to photosynthetic microorganisms and that lead to development of anoxic conditions. Population dynamics of nitrifying bacteria and rates of nitrification were studied in two wastewater reservoirs that differed in organic load and degree of oxygenation and in the laboratory under controlled conditions, both by serial dilutions in mineral medium and microscopically with fluorescein isothiocyanate-conjugated antibodies prepared against local isolates. The difference in counts by the two methods was within 1 order of magnitude. In the laboratory, an O
2
concentration of 0.2 mg liter
−1
was close to optimal with respect to growth of NH
3
oxidizers on domestic wastewater, while O
2
concentrations of 0.05 mg liter
−1
supported significant rates of nitrification. It was found that even hypertrophic anaerobic environments such as the anaerobic hypolimnion of the wastewater reservoir or the anaerobic settling ponds are capable of sustaining a viable, although not actively nitrifying, population of
Nitrosomonas
spp. and
Nitrobacter
spp., in contrast to their rapid decline when maintained anaerobically in mineral medium in the laboratory. Nitrification rates of NH
3
in effluents during storage in the reservoirs were slower by 1 to 2 orders of magnitude compared with corresponding rates in water samples brought to the laboratory. The factors causing this inhibition were not identified.
Comparison of methods for rotavirus detection in water and results of a survey of Jerusalem wastewater
Authors: Guttman-Bass N , Tchorsh Y , Marva E
Published: January 2020

Methods for the detection of viable rotaviruses and rotavirus antigen in water were developed and compared. The methods included laboratory-developed enzyme-linked immunosorbent assays (ELISAs) with chromogenic and luminescent substrates, commercial Rotazyme and Enzygnost ELISAs, and an indirect immunofluorescent assay. Of the methods tested, the immunofluorescent assay and the Enzygnost ELISA were the most sensitive for the simian rotavirus SA-11. All of the methods were positive for human rotavirus from clinical specimens. Seeded SA-11 rotavirus was concentrated from water by absorption to and elution from Zeta Plus filters followed by organic flocculation. Interference with the assays by components of the wastewater concentrates was minimal for the ELISAs, although the undiluted organic flocs were cytotoxic for the immunofluorescent assay. A survey of Jerusalem wastewater was carried out over the course of 1 year, and samples were assayed for rotaviruses and enteroviruses. Although enteroviruses were found in almost all of the samples, all samples were negative for rotaviruses. The concentration of rotaviruses in the wastewater was thus below the detection limit of the method used.
Effects of Cinnabar on Pyrite Oxidation by
Thiobacillus ferrooxidans
and Cinnabar Mobilization by a Mercury-Resistant Strain
Authors: Baldi Franco , Olson Gregory J.
Published: January 2020

The effect of cinnabar on pyrite oxidation by mercury-sensitive and mercury-resistant strains of
Thiobacillus ferrooxidans
was investigated by using percolation columns. Mercury-resistant strains oxidized pyrite in pyrite-cinnabar mixtures (1 and 10%, wt/wt), whereas a mercury-sensitive strain did not. Elemental mercury was produced by the mercury-resistant strains growing in the pyrite-cinnabar mixtures in percolation columns and in flasks containing cinnabar only. Manometric experiments showed that cinnabar had little effect on oxygen uptake of mercury-sensitive or mercury-resistant cells growing on ferrous sulfate, pyrite, or pyrite-ferrous sulfate mixtures. In addition, shake flask leaching experiments showed that cinnabar had little effect on pyrite oxidation at 1% (wt/wt) but inhibited growth of mercury-sensitive and mercury-resistant strains at 10%. Mercury-resistant strains were unable to grow on cinnabar as an energy source.
Survival of selected bacterial species in sterilized activated carbon filters and biological activated carbon filters
Authors: Rollinger Y , Dott W
Published: January 2020

The survival of selected hygienically relevant bacterial species in activated carbon (AC) filters on a bench scale was investigated. The results revealed that after inoculation of the test strains the previously sterilized AC absorbed all bacteria (10(6) to 10(7)). After a period of 6 to 13 days without countable bacteria in the effluent, the numbers of Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas putida increased up to 10(4) to 10(5) CFU/ml of effluent and 10(6) to 10(7) CFU/g of AC. When Klebsiella pneumoniae and Streptococcus faecalis were used, no growth in filters could be observed. The numbers of E. coli, P. aeruginosa, and P. putida, however, decreased immediately and showed no regrowth in nonsterile AC from a filter which had been continuously connected to running tap water for 2 months. Under these conditions an autochthonous microflora developed on the carbon surface which could be demonstrated by scanning electron microscopy and culturing methods (heterotrophic plate count). These bacteria reduced E. coli, P. aeruginosa, and P. putida densities in the effluent by a factor of more than 10(5) within 1 to 5 days. The hypothesis that antagonistic substances of the autochthonous microflora were responsible for the elimination of the artificial contamination could not be confirmed because less than 1% of the isolates of the autochthonous microflora were able to produce such substances as indicated by in vitro tests. Competition for limiting nutrients was thought to be the reason for the observed effects.
Soil Solution Phosphorus Status and Mycorrhizal Dependency in
Leucaena leucocephala
Authors: Habte Mitiku , Manjunath Aswathanarayan
Published: January 2020

A phosphorus sorption isotherm was used to establish concentrations of P in a soil solution ranging from 0.002 to 0.807 μg/ml. The influence of P concentration on the symbiotic interaction between the tropical tree legume
Leucaena leucocephala
and the vesicular-arbuscular mycorrhizal (VAM) fungus
Glomus fasciculatum
was evaluated in pot experiments. The level of mycorrhizal infection in
Leucaena
roots increased as the concentration of P was raised from 0.002 to 0.153 μg/ml. Higher levels of P depressed mycorrhizal infection, but the level of infection never declined below 50%. Periodic monitoring of P contents of
Leucaena
subleaflets indicated that significant mycorrhizal activity was detected as early as 17 days after planting, with the activity peaking 12 to 16 days thereafter. The highest level of mycorrhizal activity was associated with a soil solution P level of 0.021 μg/ml. Even though the mycorrhizal inoculation effect diminished as the concentration of P in the soil solution was increased, mycorrhizal inoculation significantly increased P uptake and dry-matter yield of
Leucaena
at all levels of soil solution P examined. The concentration of P required by nonmycorrhizal
L. leucocephala
for maximum yield was 27 to 38 times higher than that required by mycorrhizal
L. leucocephala.
The results illustrate the very high dependence of
L. leucocephala
on VAM fungi and the significance of optimizing soil solution phosphorus for enhancing the benefits of the VAM symbiosis.
Restriction Fragment Length Polymorphisms in the Mushrooms
Agaricus brunnescens
and
Agaricus bitorquis
Authors: Castle Alan J. , Horgen Paul A. , Anderson James B.
Published: January 2020

Two
Agaricus
species,
A. brunnescens
(a commercial mushroom) and
A. bitorquis
(a wild, edible species), were examined for restriction fragment length polymorphisms.
Eco
RI-digested nuclear DNA from isolates of both species were cloned in plasmid vector pUC18. Ten random recombinant clones were used in Southern DNA-DNA hybridizations to probe
Eco
RI-digested DNA from 11
A. brunnescens
isolates (7 commercial, 2 wild type, and 2 homokaryotic) and 7
A. bitorquis
isolates. Most cloned fragments were polymorphic in both species. There were fewer different genotypes than expected, however, in the sample of commercial
A. brunnescens
strains. DNA from homokaryotic strains showed fewer bands in most hybridizations than DNA from heterokaryotic strains. All
A. bitorquis
isolates could be distinguished from each other as well as from every
A. brunnescens
strain. Putative homokaryons were detected by the loss of polymorphic bands among protoplast regenerates from one commercial strain and two strains collected in the wild.
Kinetics of Homoacetic Fermentation of Lactate by
Clostridium formicoaceticum
Authors: Yang Shang-Tian , Tang I-Ching , Okos Martin R.
Published: January 2020

Clostridium formicoaceticum
homofermentatively converted lactate to acetate at mesophilic temperatures (30 to 42°C) and at pHs between 6.6 and 9.6. The production of acetate was found to be growth associated. Approximately 0.96 g of acetic acid and 0.066 g of cells were formed from each gram of lactic acid consumed at 37°C. The concentration of the substrate (lactate) had little or no effect on the growth rate; however, the fermentation was inhibited by acetic acid. The bacterium grew at an optimal pH of 7.6 and an optimal temperature of 37°C. Small amounts of bicarbonate were stimulatory to bacterial growth. Bacterial growth was enhanced, however, by the use of higher concentrations of bicarbonate in the media, only because higher buffer capacities were obtained and proper medium pH could be maintained for growth. Based on its ability to convert lactate to acetate, this homoacetic bacterium may be important in the anaerobic methanogenic process when lactate is a major intermediary metabolite.
Separation of organic dust from microorganism suspensions by partitioning in aqueous polymer two-phase systems
Authors: Ström G , Palmgren U , Blomquist G
Published: January 2020

Conidia of Penicillium brevi-compactum and Aspergillus fumigatus, sporangiospores of Rhizopus rhizopodiformis, spores of Streptomyces griseus, and bacterial cells of Bacillus subtilis were partitioned in two-phase systems consisting of dextran, polyethylene glycol, substituted positively charged sulfonylpolyethylene glycol, and water. At a pH of 2.8 in the system, the microorganisms showed 60 to 90% affinity for the upper, polyethylene glycol-rich phase, except for cells of B. subtilis, which were entirely located in the lower, dextran-rich phase. This partition behavior was used to separate microorganisms in aqueous suspensions of peat, wood fuel chip, and straw samples from organic dust impurities prior to total count by acridine orange staining and epifluorescence microscopy. Only one extraction of the interphase and lower phase was needed to separate approximately 98% of the conidia of Penicillium chrysogenum from a suspension containing peat dust.
Technique for Estimating Low Numbers of a Bacterial Strain(s) in Soil
Authors: Makkar N. S. , Casida L. E.
Published: January 2020

A technique is described for obtaining most probable number estimates of the number of cells of a bacterial strain(s) when it is present in low numbers in the soil. The technique is based on the bacteriophage response that is elicited when a known number of bacteriophage for the bacterium of interest is incubated with soil dilutions in a nutrient broth. The technique was evaluated for use with gram-negative bacteria.
Comparison of the hydrophobic-grid membrane filter procedure and standard methods for coliform analysis of water
Authors: McDaniels A E , Bordner R H , Menkedick J R , Weber C I
Published: January 2020

The hydrophobic-grid membrane filter (HGMF) has been proposed as an alternate method to the standard membrane filter (MF) procedure for the detection and enumeration of coliforms from water. Eight samples of nonchlorinated wastewater effluents were analyzed by the HGMF, standard MF, and tube fermentation most-probable-number methods for fecal coliforms, and eight samples each of polluted surface and dosed drinking waters were analyzed by the same methods for total coliforms. The drinking waters were dosed with coliforms and other heterotrophs concentrated from nonchlorinated domestic wastewater and treated with chlorine to reduce the numbers of organisms and simulate stress caused by chlorination. Statistical analyses determined that recoveries of fecal coliforms were significantly higher by the filtration methods for the nonchlorinated domestic wastewaters but not for the other waters. The results also indicated that recoveries of fecal and total coliforms did not differ significantly when either MFs or HGMFs were used. Total coliform results obtained with HGMFs having greater than 100 positive grid cells were significantly more precise than estimates obtained by the standard MF method only for polluted surface waters.
Degradation of 1,4-dichlorobenzene by a Pseudomonas sp
Authors: Spain J C , Nishino S F
Published: January 2020

A Pseudomonas species able to degrade p-dichlorobenzene as the sole source of carbon and energy was isolated by selective enrichment from activated sludge. The organism also grew well on chlorobenzene and benzene. Washed cells released chloride in stoichiometric amounts from o-, m-, and p-dichlorobenzene, 2,5-dichlorophenol, 4-chlorophenol, 3-chlorocatechol, 4-chlorocatechol, and 3,6-dichlorocatechol. Initial steps in the pathway for p-dichlorobenzene degradation were determined by isolation of metabolites, simultaneous adaptation studies, and assay of enzymes in cell extracts. Results indicate that p-dichlorobenzene was initially converted by a dioxygenase to 3,6-dichloro-cis-1,2-dihydroxycyclohexa-3,5-diene, which was converted to 3,6-dichlorocatechol by an NAD+-dependent dehydrogenase. Ring cleavage of 3,6-dichlorocatechol was by a 1,2-oxygenase to form 2,5-dichloro-cis, cis-muconate. Enzymes for degradation of haloaromatic compounds were induced in cells grown on chlorobenzene or p-dichlorobenzene, but not in cells grown on benzene, succinate, or yeast extract. Enzymes of the ortho pathway induced in cells grown on benzene did not attack chlorobenzenes or chlorocatechols.
Growth inhibition of putrefactive anaerobe 3679 caused by stringent-type response induced by protonophoric activity of sorbic acid
Authors: Ronning I E , Frank H A
Published: January 2020

The inhibitory effects of potassium sorbate on the bioenergetics, phenylalanine uptake, protein synthesis, and certain aspects of cell regulation were examined in putrefactive anaerobe 3679. Undissociated sorbic acid appeared to act as a protonophore by lowering the intracellular pH and dissipating the proton motive force of the membrane. Sorbate inhibited the uptake of phenylalanine, decreased the rate of protein synthesis, and altered patterns of phosphorylated nucleotide accumulation, resulting in increased intracellular concentrations of GTP, ppGpp, and an unidentified compound (possibly pppGpp). The addition of a noninhibitory amount of tetracycline released the inhibition of growth by sorbate. Based on these results, we concluded that the inhibition of putrefactive anaerobe 3679 by sorbate resulted from a stringent-type regulatory response induced by the protonophoric activity of sorbic acid.
Microbially Mediated Leaching of Low-Sulfur Coal in Experimental Coal Columns
Authors: Radway JoAnn C. , Tuttle Jon H. , Fendinger Nicholas J. , Means Jay C.
Published: January 2020

The leaching of a low-sulfur bituminous coal was investigated with experimental coal columns subjected to simulated rainfall events. Leachates from the columns became dominated by iron-oxidizing bacteria as evidenced by specific enrichment cultures and measurements of CO
2
assimilation. Heterotrophic microorganisms were also present in the coal leachates, but their numbers and activity decreased with decreasing pH. This pattern could be reversed by increasing the pH of the coal with lime. Organosulfur-utilizing bacteria made up a substantial portion of the heterotrophic community. Measurements of microbial activity in coal cores indicated that although much of the microbial community remained associated with coal particles, the relative abundance of heterotrophs and autotrophs in leachate seemed to reflect that in coal cores. When bacterial growth was delayed by autoclaving coal samples, acid production and leaching of iron and sulfur were also delayed. Rapid leaching of materials from coal thus appears to be strongly dependent on the presence of the natural bacterial microflora.
Multiyear study of sludge application to farmland: prevalence of bacterial enteric pathogens and antibody status of farm families
Authors: Ottolenghi A C , Hamparian V V
Published: January 2020

We describe our experience with the isolation of salmonellae from sewage sludge from four treatment plants in different geographic areas of Ohio. Over 3 years, we isolated salmonellae 50 times from 311 sludge samples. Most isolations were made after enrichment in Selenite broth (BBL Microbiology Systems, Cockeysville, Md.). The largest proportion of isolations came from the plant serving the population of Columbus, a large metropolitan area. A significantly greater number of isolations from this plant were made during the first quarter of the year. Twenty-one different serotypes were isolated, along with five untypable strains. The most frequently isolated serotype was Salmonella infantis. Five of the strains were multiply resistant to antibiotics. We also describe the prevalence of antibodies to salmonellae in members of the families residing on the farms in the study. It was found that antibodies to group C salmonellae predominated.
Restriction enzyme analysis of lactose and bacteriocin plasmids from Streptococcus lactis subsp. diacetylactis WM4 and cloning of BclI fragments coding for bacteriocin production
Authors: Harmon K S , McKay L L
Published: January 2020

The 131.1-kilobase (kb) bacteriocin production (Bac) plasmid pNP2 and the 63.6-kb lactose metabolism (Lac) plasmid pCS26, from Streptococcus lactis subsp. diacetylactis WM4, as well as pWN8, a 116.7-kb recombinant plasmid from a Lac+ transconjugant, were analyzed with restriction enzymes to determine the origin of pWN8. Plasmid pWN8 conferred a Lac+ Bac- phenotype, contained DNA derived from pCS26 and pNP2, and, like pNP2, exhibited self-transmissibility (Tra+). In cloning attempts, Bac+ transformant S. lactis KSH1 was isolated. The recombinant plasmid, pKSH1, contained three BclI fragments from pNP2. Bac- transformants which individually contained each of the three fragments were also identified. Comparison of restriction maps of pKSH1 and pNP2 revealed an 18.4-kb region common to both plasmids, involving two of the three BclI fragments. S. lactis KSH1 also exhibited greater inhibitory activity against the indicator strain S. diacetylactis 18-16 than did a strain containing the 131.1-kb Bac plasmid.
H
2
-CO
2
Recirculation and pH Control for Growth of Methanogens in Mass Culture
Authors: Boone David R. , Mathrani Indra M. , Mah Robert A.
Published: January 2020

We modified a fermentor (10-liter liquid volume) for the growth of anaerobic, H
2
-CO
2
-catabolizing bacteria. Gas in the fermentor (ca. 10% CO
2
, 50% H
2
, 40% CH
4
) was recirculated by a diaphragm pump. During growth, the gas composition was maintained by the addition of a mixture of 80% H
2
and 20% CO
2
, and this addition was controlled by a pH auxostat. During gas addition, gas was discharged from the recirculating gas stream and was collected by the displacement of an acidified salt solution.
Phomenoic acid and phomenolactone, antifungal substances from Phoma lingam (Tode) Desm.: kinetics of their biosynthesis, with an optimization of the isolation procedures
Authors: Topgi R S , Devys M , Bousquet J F , Kollmann A , Barbier M
Published: January 2020

Phomenoic acid and phomenolactone, previously isolated from the fungus Phoma lingam (Tode) Desm., have shown moderate antifungal and antibacterial properties in vitro. To rationalize the production of phomenoic acid, a kinetic study of its biosynthesis in the mycelium was performed. Phomenoic acid and phomenolactone appear in the mycelium after a prolonged incubation, a phenomenon which may be of particular interest for the production of these substances or in the study of the mechanism of their biosynthesis. The isolation procedure was optimized for phomenoic acid. Through a series of SiO2 column chromatographies, high-pressure liquid chromatography, and transformation of the mixture of phomenoic acid and phomenolactone into methyl phomenoate (BF3), the final yield of phomenoic acid reached 160 mg/liter of culture medium. An alternative method for the isolation of both phomenoic acid and phomenolactone is also reported in detail.
Regulation of aflatoxin biosynthesis: assessment of the role of cellular energy status as a regulator of the induction of aflatoxin production
Authors: Buchanan R L , Jones S B , Gerasimowicz W V , Zaika L L , Stahl H G , Ocker L A
Published: January 2020

Possible relationships among cellular energy status and the induction and initiation of aflatoxin synthesis were studied by using replacement culture techniques in conjunction with aflatoxin-supporting and-nonsupporting media. Transcription and translation processes associated with the induction of aflatoxin synthesis occurred 3 to 6 and 6 to 10 h, respectively, after mycelia were transferred to glucose-containing media. From adenylate energy charge determinations and in situ 31P nuclear magnetic resonance analyses, a relationship between overall energy status and the induction or initiation of aflatoxin synthesis could not be identified; however, electron microscopic evaluations indicated that aflatoxin synthesis occurred in association with a glucose-mediated inactivation of mitochondria. The results suggest that aflatoxin synthesis is not regulated by the overall energy status of the fungal cell but may be controlled by the energy status of specific subcellular compartments.
Cytotoxic and cytolytic activity of nonadecafluoro-n-decanoic acid on Acholeplasma laidlawii
Authors: Liss A , Pfeil J C , Levitt D
Published: January 2020

We studied the interactions between the perfluorinated fatty acid nonadecafluoro-n-decanoic acid (NDFDA) and the cell wall-less procaryote Acholeplasma laidlawii, which were cultured in an identical medium base but with different serum supplements. When grown in mycoplasma media supplemented with PPLO serum fraction (Difco Laboratories, Detroit, Mich.), A. laidlawii was rapidly killed by low concentrations of toxicant (less than 1.0 mM). At higher concentrations (greater than 10 mM), NDFDA treatment appeared to lyse cells. A. laidlawii cells grown in horse serum-supplemented mycoplasma media were both killed and lysed at the same NDFDA concentration (greater than 10 mM). These data suggest that this perfluorinated fatty acid can be cytotoxic and cytolytic to mycoplasmas. Changes in active concentrations occurred in parallel with changes in growth medium serum supplementation, which is known to alter mycoplasma membrane composition. We propose that NDFDA interacts with the membranes of A. laidlawii cells, resulting in cell death or cell lysis or both.
Comparative survival of antibiotic-resistant and -sensitive fecal indicator bacteria in estuarine water
Authors: Pettibone G W , Sullivan S A , Shiaris M P
Published: January 2020

The survival of antibiotic-resistant and -sensitive strains of Escherichia coli, Enterococcus faecalis, Enterococcus faecium, Streptococcus equinus, and two environmental isolates, AP17 and AQ62, was examined in estuarine water. Each strain was rendered resistant to a combination of two antibiotics by serial passage in increasing concentrations of antibiotics. Cultures were incubated in filter-sterilized estuarine water for up to 7 days. Recovery was assessed by examining colony-forming ability on media with and without antibiotics. None of the antibiotic-resistant forms survived longer than its antibiotic-sensitive counterpart in estuarine water. Three of the resistant strains died off more rapidly than the antibiotic-sensitive wild type. Survival of the test bacteria in estuarine water was as follows: sensitive and resistant AQ62, resistant Escherichia coli less than sensitive Escherichia coli less than resistant AP17 less than resistant Enterococcus faecium less than sensitive AP17, sensitive and resistant S. equinus less than sensitive and resistant Enterococcus faecalis, sensitive Enterococcus faecium. The results supported the suggestion that fecal entercocci may serve as better indicators of fecal pollution than Escherichia coli in marine ecosystems. Moreover, the results indicated that the use of antibiotic-resistant mutants to follow the fate of bacteria in the environment is inappropriate without adequate studies to ensure that resistant and wild-type strains react similarly to environmental stressors.
Improved membrane filtration media for enumeration of total coliforms and Escherichia coli from sewage and surface waters
Authors: Freier T A , Hartman P A
Published: January 2020

Two media were developed that allowed both a total coliform count and an Escherichia coli count to be determined on the same medium after 24 h of incubation at 35 degrees C. The new media were tested along with two standard media on 10 surface water and 7 sewage samples. The experimental media yielded equivalent or higher counts relative to the standard media and recovered more specifically the desired indicator groups as determined by colony identification.
Rapid plasmid analysis for identification of Edwardsiella ictaluri from infected channel catfish (Ictalurus punctatus)
Authors: Lobb C J , Rhoades M
Published: January 2020

Eighteen different strains of Edwardsiella ictaluri isolated from infected channel catfish (Ictalurus punctatus) were screened to determine whether plasmid DNA was present. Two plasmids of 5,700 and 4,900 base pairs were identified. Restriction enzyme analysis showed that each of the strains harbored these same two plasmids. Restriction maps of the separated plasmids indicated that these plasmids were not closely related to each other. A rapid screening technique was developed that would allow the presence of these plasmids from either broth cultures or single colonies of E. ictaluri to be determined within 2 to 3 h by agarose gel electrophoresis. These results suggest that plasmid fingerprinting of E. ictaluri should become a useful tool in the presumptive identification of this bacterium from infected channel catfish.
Ethanol production during batch fermentation with Saccharomyces cerevisiae: changes in glycolytic enzymes and internal pH
Authors: Dombek K M , Ingram L O
Published: January 2020

During batch fermentation, the rate of ethanol production per milligram of cell protein is maximal for a brief period early in this process and declines progressively as ethanol accumulates in the surrounding broth. Our studies demonstrate that the removal of this accumulated ethanol does not immediately restore fermentative activity, and they provide evidence that the decline in metabolic rate is due to physiological changes (including possible ethanol damage) rather than to the presence of ethanol. Several potential causes for the decline in fermentative activity have been investigated. Viability remained at or above 90%, internal pH remained near neutrality, and the specific activities of the glycolytic and alcohologenic enzymes (measured in vitro) remained high throughout batch fermentation. None of these factors appears to be causally related to the fall in fermentative activity during batch fermentation.
Factors contributing to the reduced invasiveness of chlorine-injured Yersinia enterocolitica
Authors: LeChevallier M W , Schiemann D A , McFeters G A
Published: January 2020

The invasion of epithelial cells in vitro and in vivo by chlorine-injured Yersinia enterocolitica was assessed by direct microscopic observations. These experiments showed that injury by chlorine inhibited invasiveness of virulent Y. enterocolitica. Two requirements appeared to be necessary for invasiveness: the organism must be viable and metabolically active, and the organism must have certain surface components to initiate engulfment. Inhibition of RNA synthesis by rifampin and protein synthesis by chloramphenicol, tetracycline, and spectinomycin inhibited the invasiveness but not the attachment of Y. enterocolitica to epithelial cells. Membrane preparations from untreated and antimicrobial-agent-treated Y. enterocolitica blocked the invasiveness of virulent Y. enterocolitica, whereas membranes from chlorinated cells were unable to block invasiveness. Chlorine did not change the hydrophobicity or surface charge of injured Y. enterocolitica. The results indicate that invasion was more than simple association of the bacterium with the epithelial cell and involved a specific trigger to stimulate engulfment.
Efficient plasmid transformation of the beta-lactam producer Streptomyces clavuligerus
Authors: Garcia-Dominguez M , Martin J F , Mahro B , Demain A L , Liras P
Published: January 2020

The conditions for optimal formation and regeneration of protoplasts of Streptomyces clavuligerus were established. The optimal temperature for regeneration of protoplasts and for transformation was 26 degrees C in three different regeneration media. The best efficiency of transformation was obtained with 40% polyethylene glycol 1000. The efficiencies of regeneration and transformation increased greatly when protoplasts were obtained from cultures in the early stationary phase of growth. The number of transformants per assay increased linearly with rising concentrations of protoplasts. However, the number of transformants per protoplast decreased at concentrations of protoplasts above 1.5 X 10(9). The total number of transformants rose linearly at increasing plasmid DNA concentrations, but the number of the transformants per microgram of DNA became constant at concentrations above 1 microgram of DNA. Transformation frequencies as high as 5 X 10(5) transformants per microgram of DNA were obtained when plasmid pIJ702 was isolated from S. clavuligerus but not when isolated from Streptomyces lividans.
A Differential Medium for the Enumeration of Homofermentative and Heterofermentative Lactic Acid Bacteria
Authors: McDonald L. C. , McFeeters R. F. , Daeschel M. A. , Fleming H. P.
Published: January 2020

A medium was developed for the differential enumeration of homofermentative and heterofermentative lactic acid bacteria. Essential components of the medium included fructose (14 mM), KH
2
PO
4
(18 mM), bromcresol green (as a pH indicator), and other nutrients to support growth. In agar medium, homofermentative colonies were blue to green, while heterofermentative colonies remained white. A total of 21
Lactobacillus, Pediococcus, Leuconostoc,
and
Streptococcus
species were correctly classified with the medium.