bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of a Take-All Suppressive Strain of
Pseudomonas fluorescens
on Seminal Roots of Winter Wheat
Authors: Weller David M.
Published: January 2020

An antibiotic-resistant strain of
Pseudomonas fluorescens
, that suppresses take-all of wheat, was used to study the distribution of the bacteria on seminal roots of wheat after being introduced onto seeds. Cells of
P. fluorescens
were isolated from the entire length of the root, and density of the introduced bacteria declined with the distance from the base of the root. Maximum populations of 10
5
to 10
6
CFU and 10
3
to 10
5
CFU per cm of root were detected on sections of roots near the seed and root tip, respectively. The introduced bacteria competed well with indigenous bacteria, comprising at least 25% of the fluorescent pseudomonads detected by plate counts for 48 days after planting.
Modified agar medium for detecting environmental salmonellae by the most-probable-number method
Authors: Hussong D , Enkiri N K , Burge W D
Published: January 2020

Salmonellae in the environment remain a potential source of disease. Low numbers of salmonellae have been detected and enumerated from environmental samples by most-probable-number methods which require careful colony selection from a plated agar medium. A modified xylose lysine brilliant green medium was prepared to control the loss of selectivity caused by heating the brilliant green component. Added agar reduced colony spreading. The medium contained 47 g of xylose lysine agar base per liter; the agar content was adjusted to 2%, autoclaved, cooled to 50 degrees C, and then amended just before pouring to include H2S indicator and 7 ppm (7 ml of 1:1,000 brilliant green per liter) of unheated brilliant green dye. H2S-positive salmonellae were easily detected from sewage sludge compost to the exclusion of most other gram-negative bacteria. As a result, fewer non-salmonellae were picked for further most-probable-number analysis, greatly reducing the work load associated with the most-probable-number method. Direct plating was possible for enumerating salmonellae in laboratory composts containing ca. 10(3) or more salmonellae.
Simple method for isolation of 4-deoxynivalenol from rice inoculated with Fusarium graminearum
Authors: Ehrlich K C , Lillehoj E B
Published: January 2020

A new method for preparative isolation of 4-deoxynivalenol (DON) is presented. This method avoids the loss of material during purification on silica gel by column chromatography. DON and 3-acetyldeoxynivalenol in crude extracts of rice inoculated with Fusarium graminearum were converted to triacetyldeoxynivalenol; the acetylated product was easier to purify by silica gel chromatography than DON is. After hydrolysis and further purification on a charcoal-alumina column, the 71% pure DON was recovered in yields as high as 450 mg of DON per kg of rice. Subsequent separation on a Sephadex LH20 column yielded DON that was greater than 90% pure.
Anaerobic Biodegradation of Indole to Methane
Authors: Wang Yi-Tin , Suidan Makram T. , Pfeffer John T.
Published: January 2020

Methane gas was produced from a laboratory, granular activated carbon, anaerobic filter treating a synthetically prepared mixture of polycyclic
N
-aromatic compounds. The biodegradability of the individual polycyclic
N
-aromatic compound present in the mixture was investigated. Experimental results obtained from test bottles containing methanogenic enrichment cultures suggested that indole was degraded to methane and carbon dioxide under strict anaerobic conditions.
Disinfection of bacteria attached to granular activated carbon
Authors: LeChevallier M W , Hassenauer T S , Camper A K , McFeters G A
Published: January 2020

Heterotrophic plate count bacteria, coliform organisms, and pathogenic microorganisms attached to granular activated carbon particles were examined for their susceptibility to chlorine disinfection. When these bacteria were grown on carbon particles and then disinfected with 2.0 mg of chlorine per liter (1.4 to 1.6 mg of free chlorine residual per liter after 1 h) for 1 h, no significant decrease in viable counts was observed. Washed cells attached to the surface of granular activated carbon particles showed similar resistance to chlorine, but a progressive increase in sublethal injury was found. Observations made by scanning electron microscope indicated that granular activated carbon was colonized by bacteria which grow in cracks and crevices and are coated by an extracellular slime layer. These data suggest a possible mechanism by which treatment and disinfection barriers can be penetrated and pathogenic bacteria may enter drinking water supplies.
Isolation and characterization of a new Cytophaga species implicated in a work-related lung disease
Authors: Liebert C A , Hood M A , Deck F H , Bishop K , Flaherty D K
Published: January 2020

A yellow-pigmented, gram-negative, gliding bacterium isolated from an industrial water spray air humidification system was implicated as a causative agent in several occurrences of lung disease with hypersensitivity pneumonitis-like symptoms. The bacterium, designated WF-164, lacked microcysts or fruiting bodies and had a DNA base composition of 34.8 mol% of guanine plus cytosine. Gliding, flexing, nonflagellated cells measuring 0.3 by 3.5 to 8.9 micron were observed by using light and electron microscopy. Tests to determine utilization of selected carbohydrates revealed an amylolitic, chitinoclastic, noncellulytic bacterium. A number of additional biochemical and physiological tests were performed. DNA homology studies detected a 77.8% similarity to Cytophaga aquatilis (ATCC 29551). Comparisons of cellular fatty acid and carbohydrate contents of isolate WF-164 with a Flexibacter sp., several Cytophaga spp., and Flavobacterium reference strains revealed similar patterns to that of C. aquatilis. On the basis of these characteristics, isolate WF-164 was identified as a new Cytophaga sp.
Multilocus Electrophoretic Assessment of the Genetic Structure and Diversity of
Yersinia ruckeri
Authors: Schill William B. , Phelps Stevan R. , Pyle Stephen W.
Published: January 2020

Multilocus isoenzyme electrophoresis was used to screen 47 field isolates of
Yersinia ruckeri
for electrophoretic variation at 15 enzyme loci. Only four electrophoretic types were observed, thus indicating that the genetic structure of
Y. ruckeri
is clonal. Forty-two isolates were of one electrophoretic type, a reflection of the low amount of genetic diversity extant in this species. Although sorbitol fermentation has been considered to be indicative of a second biotype, no significant gene frequency differences were found between the group of 20 isolates that readily used sorbitol as the sole carbon source and the group of 27 that did not.
Role of stagnation and obstruction of water flow in isolation of Legionella pneumophila from hospital plumbing
Authors: Ciesielski C A , Blaser M J , Wang W L
Published: January 2020

The stagnation of water in two of four hospital hot-water storage tanks found to contain Legionella pneumophila was reduced by keeping the two tanks continually on-line for 1 year. L. pneumophila colony counts in these two tanks fell quickly to low levels, whereas the organisms persisted in the two tanks that were not in use. L. pneumophila continued to be isolated from 50 to 100% of the hospital showerheads which were sampled during this period. We also examined aerators and other hospital faucet fixtures which obstruct water flow. L. pneumophila was isolated from 22 of 30 faucet aerators and 2 of 16 vacuum breakers but not from 26 nonobstructed faucets or 6 backflow preventers. Over a 7-month period, after nine faucet aerators were sterilized, 10 of 60 surveillance cultures revealed L. pneumophila, despite the inability to isolate the organism from the potable-water tanks in use. These data suggest that prevention of stagnation in hot-water tanks may be effective in reducing L. pneumophila concentrations in potable-water systems serving high-risk populations. We have also shown that faucet aerators, by providing a surface for L. pneumophila to colonize, can become secondary reservoirs for the organism in hospital plumbing.
Production and Regeneration of
Lactobacillus casei
Protoplasts
Authors: Lee-Wickner Lyang-Ja , Chassy Bruce M.
Published: January 2020

Methods for the production and regeneration of
Lactobacillus casei
protoplasts are described. Protoplasts of
L. casei
strains were obtained by treatment with mutanolysin or with mutanolysin and lysozyme together in a protoplast formation buffer containing 0.02 M HEPES (
N
-2-hydroxyethylpiperazine-
N′
-2-ethanesulfonic acid) (pH 7.0), 1 mM MgCl
2
, 0.5% gelatin, and 0.3 M raffinose. Cells were regenerated on a complex medium supplemented with bovine serum albumin, MgCl
2
, CaCl
2
, gelatin, and raffinose. Lengthy digestion with lytic enzymes inhibited the capacity of protoplasts to regenerate. The optimum conditions of protoplast formation varied from strain to strain. Using predetermined optimal conditions it was possible to prepare protoplasts of several
L. casei
strains and regenerate them with 10 to 40% efficiency. The methods were applicable to other species of lactobacilli as well.
Aspartase-hyperproducing mutants of Escherichia coli B
Authors: Nishimura N , Kisumi M
Published: January 2020

When a wild-type strain of Escherichia coli B was cultured on a medium containing L-aspartic acid as the sole carbon source (Asp-C medium), aspartase formation was higher than that observed in minimal medium. Addition of glucose to Asp-C medium decreased aspartase formation. When also cultured in a medium containing L-aspartic acid as the sole nitrogen source (Asp-N medium), E. coli B showed a low level of aspartase formation and an elongated doubling time. To obtain aspartase-hyperproducing strains, we enriched cells growing faster than cells of the wild-type strain in Asp-N medium by continuous cultivation of mutagenized cells. After plate selection, the doubling times of these mutants were measured. Thereafter, fast-growing mutants were tested for aspartase formation. One of these mutants, strain EAPc7, had a higher level of aspartase formation than did the wild-type strain in medium containing L-aspartic acid as the carbon source, however; addition of glucose to this medium decreased aspartase formation. The other mutant, strain EAPc244, had a higher level of aspartase activity than did the wild-type strain in both media. Therefore, aspartase formation in mutant EAPc244 was released from catabolite repression. In strain EAPc244 the other catabolite-repressible enzymes, beta-galactosidase, tryptophanase, and the three tricarboxylic acid cycle enzymes, were also released from catabolite repression. Both mutants had sevenfold the aspartase formation of the wild-type strain in a medium which contained fumaric acid as the main carbon source and which has been used for industrial production of E. coli B aspartase. However, strain EAPc244 had 2.5-fold the fumarase activity of strain EAPc7.(ABSTRACT TRUNCATED AT 250 WORDS)
Changes in the lipid composition of Paecilomyces persicinus P-10 M1 during growth and cephalosporin C production
Authors: Papacharilaou E , Pisano M A
Published: January 2020

The lipid composition of the fungus Paecilomyces persicinus P-10 M1 was monitored daily for 6 days to detect any changes during growth and cephalosporin C production. Total lipid yields and cephalosporin C production were maximal after 72 h of incubation. Analysis of the total lipids revealed that the neutral lipid fraction was elevated at this time, whereas polar lipids were depressed. Phosphatidylethanolamine and phosphatidylcholine represented the major phospholipids detected. Phosphatidylethanolamine levels were descending when cephalosporin C was detected at its highest concentration. Increases in phosphatidylcholine levels paralleled those of cephalosporin C but reached a maximum at 48 h after the latter. Diphosphatidylglycerol, phosphatidic acid, and phosphatidylserine were also detected. Fatty acids present in the total lipid fraction ranged in carbon length from C12 to C24. The major acids were C16 (palmitic), C18:1 (oleic), and C18:2 (linoleic). All fatty acids exhibited minor variations in concentration during the 6-day period, and none displayed a direct correlation with cephalosporin C yields.
Production and characterization of monoclonal antibodies against aflatoxin M1
Authors: Woychik N A , Hinsdill R D , Chu F S
Published: January 2020

By using an indirect enzyme-linked immunosorbent assay, four monoclonal antibodies were selected after fusion of mouse P3-NS1-Ag4-1 myeloma cells with spleen cells isolated from BALB/c mice that had been immunized with aflatoxin M1 (AFM1) conjugated to bovine serum albumin. Two of these antibodies were found to be specific for AFM1 and were designated AMW-1 and AMW-4. The specificities of AMW-1, which had higher affinity to AFM1, were determined by a competitive direct enzyme-linked immunosorbent assay with peroxidase-AFM1 as the marker. The relative cross-reactivity of each toxin (relative to AFM1) with AMW-1, as determined by the amount of aflatoxin necessary to cause 50% inhibition of enzyme activity, was 12, greater than 40, 12, and greater than 40 for B1, B2, G1, and G2, respectively.
Methylation and demethylation of mercury under controlled redox, pH and salinity conditions
Authors: Compeau G , Bartha R
Published: January 2020

In estuarine sediments, the microbially mediated processes of methylation, demethylation, and volatilization determine the state and overall toxicity of mercury pollutants. The effects of redox potential (Eh) and salinity on the above microbial processes were investigated in reactors constructed to allow for continuous monitoring and adjustment of the pH (6.8) and Eh of freshly collected estuarine sediments. For measurements of methylation and demethylation activity, sediment slurries adjusted to appropriate salinity were spiked with HgCl2 or CH3HgCl, respectively, and were incubated in the reactors. Methylmercury was measured by gas chromatography. Volatilized elemental mercury (Hg0) was trapped and determined by cold vapor atomic absorption spectrometry. Volatilization of Hg0 and CH3HgCH3 were found to be minimal. Methylation of Hg2+ was favored at Eh-220 mV as compared to +110 mV. At -220 mV, high salinity (2.5%) inhibited methylation, and low salinity (0.4%) favored it. At +110 mV, the salinity effect was less pronounced. Demethylation of CH3HgCl was favored at +110 mV regardless of the salinity level. Low redox potential under low salinity conditions inhibited demethylation, but high salinity reversed this inhibition. These findings are helpful for interpreting and predicting the behavior of mercury pollutants in estuarine sediments.
Role of Chemotaxis in the Ecology of Denitrifiers
Authors: Kennedy Michael J. , Lawless James G.
Published: January 2020

A modification of the Adler capillary assay was used to evaluate the chemotactic responses of several denitrifiers to nitrate and nitrite. Strong positive chemotaxis was observed to NO
3
−
and NO
2
−
by soil isolates of
Pseudomonas aeruginosa, Pseudomonas fluorescens
, and
Pseudomonas stutzeri
, with the peak response occurring at 10
−3
M for both attractants. In addition, a strong chemoattraction to serine (peak response at 10
−2
M), tryptone, and a soil extract, but not to NH
4
+
, was observed for all denitrifiers tested. Chemotaxis was not dependent on a previous growth on NO
3
−
, NO
2
−
, or a soil extract, and the chemoattraction to NO
3
−
occurred when the bacteria were grown aerobically or anaerobically. However, the best response to NO
3
−
was usually observed when the cells were grown aerobically with 10 mM NO
3
−
in the growth medium. Capillary tubes containing 10
−
3 M NO
3
−
submerged into soil-water mixtures elicited a significant chemotactic response to NO
3
−
by the indigenous soil microflora, the majority of which were
Pseudomonas
spp. A chemotactic strain of
P. fluorescens
also was shown to survive significantly better in aerobic and anaerobic soils than was a nonmotile strain of the same species. Both strains had equal growth rates in liquid cultures. Thus, chemotaxis may be one mechanism by which denitrifiers successfully compete for available NO
3
−
and NO
2
−
, and which may facilitate the survival of naturally occurring populations of some denitrifiers.
Autoradiographic method to screen for soil microorganisms which accumulate zinc
Authors: Zamani B , Knezek B D , Flegler S L , Beneke E S , Dazzo F B
Published: January 2020

An autoradiographic method was developed to screen for and isolate soil microorganisms which accumulate zinc (Zn). Diluted soil samples (Rubicon fine sand, Entic Haplorthods [pH 5.9]) were plated on soil extract-glucose agar containing radioactive 65Zn. After 7 days of incubation, individual colonies which accumulated sufficient 65Zn could be detected by autoradiography. These colonies were isolated and confirmed as Zn accumulators in pure culture by using the autoradiographic plate technique. Most Zn accumulators were filamentous fungi, identified as Penicillium janthinellum, Aspergillus fumigatus, and Paecilomyces sp. Isolates of Penicillium janthinellum were the most common Zn accumulators. The most abundant Zn-accumulating bacteria were Bacillus spp. The validity of the autoradiographic plate technique to differentiate soil microbes which accumulate Zn was examined independently by energy dispersive X-ray analysis in a scanning electron microscope. This method confirmed that fungal isolates which gave positive autoradiographic responses in the plate assay bioaccumulated more Zn in their biomass than fungal isolates from the same soil sample which gave negative autoradiographic responses. Thus, this technique can be applied to specifically screen for and isolate microbes from the environment which bioaccumulate Zn.
Preparation and characterization of monoclonal antibodies to the trichothecene mycotoxin T-2
Authors: Hunter K W , Brimfield A A , Miller M , Finkelman F D , Chu S F
Published: January 2020

Two mouse immunoglobulin G1 monoclonal antibodies that bind to the trichothecene mycotoxin T-2 were prepared. These antibodies, designated 12C12 and 15H6, had affinities for T-2 of 3.5 X 10(6) and 5.8 X 10(7) liters/mol, respectively. A competitive inhibition enzyme immunoassay that employed these antibodies had a sensitivity for T-2 of 50 ng per assay. Both antibodies bound to the metabolite HT-2 but not to the related trichothecenes monoacetoxyscirpenol, diacetoxyscirpenol, deoxynivalenol, and deoxyverrucarol. Evidence is presented that T-2-protein conjugates inhibit protein synthesis in lymphoid cells and that this apparent immunotoxicity may be due to the release of T-2 from the protein carrier.
Influence of
Serratia marcescens
Pigmentation on Cell Concentrations in Aerosols Produced by Bursting Bubbles
Authors: Syzdek Lawrence D.
Published: January 2020

For eight strains of
Serratia marcescens
, increased cell concentrations were found in aerosols produced from bursting bubbles, with concentrations ranging from a maximum of ca. 80 times the bulk concentration for pigmented strains 4180, 933, and 274 to a minimum approximately equal to the bulk concentration for nonpigmented strain 8100. The increased cell concentration in the aerosol was suppressed when pigmented strains were grown at 37°C, a temperature at which the pigment prodigiosin is not synthesized, resulting in lower concentrations similar to those of nonpigmented strains. Strains that produce higher concentrations of prodigiosin after 1, 2, 4, and 8 days of growth show increasing concentrations in bubble-produced drops; duplicate cultures grown at 37°C did not show any increases. In four concurrent experiments, cells starved for 24 h showed greater concentrations than nonstarved cells for chromogenic strain NIMA, whereas for nonchromogenic strain WF, starved cells showed greater concentrations in three cases and a decreased concentration in the fourth. Bacterial concentrations in aerosol drops from bursting bubbles appear to be predominantly influenced by the surface condition of the bacterial cell.
Occurrence of Yersinia enterocolitica in wild-living birds and Japanese serows
Authors: Kato Y , Ito K , Kubokura Y , Maruyama T , Kaneko K , Ogawa M
Published: January 2020

Yersinia spp. were isolated from 34 of 500 birds representing nine species. The highest isolation rate, 5 of 21 (23.8%), was found in blue magpies (Cyanopia cyanus), followed by pheasants (Phasianus colchicus tohkaidi), 5 of 33 (15.2%); gray starlings (Sturnus cineraceus), 6 of 57 (10.5%); tree sparrows (Passer montanus), 1 of 14 (7.1%); bulbuls (Hypsipetes amaurotis), 4 of 57 (7.0%); crows (Corvus levailantii or Corvus corone), 7 of 117 (6.0%); eastern turtledoves (Streptopelia orientalis), 4 of 118 (3.4%); Chinese bamboo pheasants (Bumbusicola thoracica thoracica), 1 of 36 (2.8%); and domestic pigeons (Columba livia domestica), 1 of 47 (2.1%). The isolates were identified as Yersinia enterocolitica O:3, O:4, O:4,32, O:5A, O:6,30, O:7,8, and O:14, Yersinia frederiksenii, Yersinia intermedia, and Yersinia kristensenii. Yersinia spp. were isolated from 35 of 157 wild-living Japanese serows (Capricornis cripus). The isolates were identified as Y. enterocolitica O:4, O:4,32, O:5A, O:7, O:7,8, O:9, O:14, O:18, and O:34, Y. frederiksenii, Y. intermedia, and Y. kristensenii.
Solid-State Fermentation with
Trichoderma reesei
for Cellulase Production
Authors: Chahal D. S.
Published: January 2020

Cellulase yields of 250 to 430 IU/g of cellulose were recorded in a new approach to solid-state fermentation of wheat straw with
Trichoderma reesei
QMY-1. This is an increase of ca. 72% compared with the yields (160 to 250 IU/g of cellulose) in liquid-state fermentation reported in the literature. High cellulase activity (16 to 17 IU/ml) per unit volume of enzyme broth and high yields of cellulases were attributed to the growth of
T. reesei
on a hemicellulose fraction during its first phase and then on a cellulose fraction of wheat straw during its later phase for cellulase production, as well as to the close contact of hyphae with the substrate in solid-state fermentation. The cellulase system obtained by the solid-state fermentation of wheat straw contained cellulases (17.2 IU/ml), β-glucosidase (21.2 IU/ml), and xylanases (540 IU/ml). This cellulase system was capable of hydrolyzing 78 to 90% of delignified wheat straw (10% concentration) in 96 h, without the addition of complementary enzymes, β-glucosidase, and xylanases.
Sulfide Alleviation of the Acetylene Inhibition of Nitrous Oxide Reduction in Soil
Authors: Evans David G. , Beauchamp Eric , Trevors Jack T.
Published: January 2020

The alleviation of the acetylene blockage of nitrous oxide reduction by sulfide was studied in anaerobically incubated Brookston soil to better characterize the process. Removal of nitrate-derived nitrous oxide from soil amended with acetylene and sulfide occurred earlier in the presence of glucose than it did in its absence. This was attributed to the influence of glucose on nitrous oxide production rather than reduction during the early stages of the soil incubation. Glucose was found to have no effect on reduction of injected nitrous oxide in the presence of acetylene- and sulfide-amended soil, whereas carbon dioxide significantly stimulated reduction. It is suggested that the microorganism(s) involved may use carbon dioxide as a cellular carbon source. The sulfide added to the soil probably did not act solely as an electron donor, as the number of electrons required to reduce the added nitrous oxide in our systems was greater than the amount supplied by the sulfide. The soil pH at which the alleviation occurred was 6.7 and was not affected by the sulfide treatment.
Autoradiographic Studies of [
methyl
-
3
H]Thymidine Incorporation in a Cyanobacterium (
Microcystis wesenbergii
)-Bacterium Association and in Selected Algae and Bacteria
Authors: Bern Lars
Published: January 2020

The present investigation showed by means of autoradiography that the cyanobacterium
Microcystis wesenbergii
did not incorporate [
3
H]thymidine at nanomolar concentrations, whereas its associated heterotrophic bacteria appearing in the gelatinous cover of the cyanobacterium became labeled. Several other tested cyaobacteria and algae did not incorporate [
3
H]thymidine.
Sterigmatocystin in dairy cattle feed contaminated with Aspergillus versicolor
Authors: Vesonder R F , Horn B W
Published: January 2020

Sterigmatocystin (7.75 micrograms/g of feed) and a high-propagule-density of Aspergillus versicolor were detected in feed associated with acute clinical symptoms of bloody diarrhea and death in dairy cattle. Nine isolates of A. versicolor from the feed produced 13 to 89 micrograms of sterigmatocystin per g on cracked corn and lower amounts in liquid culture. This is the first report of sterigmatocystin in dairy cattle feed in the United States.
Bacterial reduction of fensulfothion and its hydrolysis product 4-methylsulfinyl phenol
Authors: Mac Rae I C , Cameron A J
Published: January 2020

Oxygen-limited cultures of Klebsiella pneumoniae reduced 4-methylsulfinyl phenol to 4-methylthiophenol. A study of the effect of 4-methylthiophenol on the growth of K. pneumoniae revealed that the specific growth rate was retarded by 40% in the presence of 200 micrograms of the phenol per ml. A soil bacterium, Hafnia sp., was isolated that could reduce the organophosphorus insecticide fensulfothion to fensulfothion sulfide.
Response of Bacteria Isolated from a Pristine Prairie Stream to Concentration and Source of Soluble Organic Carbon
Authors: McArthur J. Vaun , Marzolf G. Richard , Urban James E.
Published: January 2020

Responses of native aquatic bacteria to source and concentration of dissolved organic carbon was observed by using gradient plates. Dissolved organic carbon of prairie (grasses) or gallery forest (bur oak) origin was used as the carbon source in these observations. Bacteria isolated from sediments in the grassland reaches of a prairie stream showed growth only on grass leachates. Bacteria isolated from the gallery forest reaches of the same stream were able to grow on plates made from either source of leachate. The differing quality, quantity, and rate of supply of these dissolved organic carbon sources should select for variation in the bacterial assemblages.
Hybridization and Polyploidization of
Saccharomyces cerevisiae
Strains by Transformation-Associated Cell Fusion
Authors: Takagi Atsuko , Harashima Satoshi , Oshima Yasuji
Published: January 2020

Hybrid or polyploid clones of
Saccharomyces cerevisiae
produced by protoplast fusion were easily isolated by selecting transformants with the plasmid phenotype because the transformation was directly associated with cell fusion. When haploid cells were used as the original strain, the transformants were mostly diploids with a significant fraction of polyploids (triploids or tetraploids). Repeated transformation after curing the plasmid gave rise to clones with higher ploidy, but the frequency of cell fusion was severely reduced as ploidy increased.
Change in Microbial Numbers during Thermophilic Composting of Sewage Sludge with Reference to CO
2
Evolution Rate
Authors: Nakasaki Kiyohiko , Sasaki Masayuki , Shoda Makoto , Kubota Hiroshi
Published: January 2020

Dewatered sewage sludge was composted in a laboratory-scale autothermal reactor in which a constant temperature of 60°C was kept as long as possible by regulating the air feed rate. The change in CO
2
evolution rate was measured continuously from the start up through the cessation of compositing. The succession of mesophilic bacteria, thermophilic bacteria, and thermophilic actinomycetes was also observed during the composting. Specific CO
2
evolution rates of thermophilic bacteria and actinomycetes in the constant-temperature region of 60°C were assessed quantitatively. It was found that the CO
2
evolution rate was attributed to thermophilic bacteria at the initial stage of 60°C and to thermophilic actinomycetes at the later stage of 60°C.
Characteristics of Mesophilic Bacteria Isolated during Thermophilic Composting of Sewage Sludge
Authors: Nakasaki Kiyohiko , Sasaki Masayuki , Shoda Makoto , Kubota Hiroshi
Published: January 2020

The degree of inactivation by UV irradiation was different between vegetative cells and spores of bacteria isolated from sewage sludge composting at 60°C. By using this property, a method to estimate the spore ratio of a mixture of vegetative cells and spores was presented. This UV irradiation method was applied to the estimation of the spore ratio of sewage sludge compost samples collected at several stages of composting. The spore ratio of mesophilic bacteria in the samples obtained at the thermophilic stage of 60°C was 40% at most. The vegetative form of mesophilic bacteria showed a thermotolerance property at 60°C by forming colonies but showed no respiratory activity at that temperature.
Root Hair Deformations Associated with Fractionated Extracts from
Rhizobium trifolii
Authors: Ervin Sean E. , Hubbell David H.
Published: January 2020

Components from culture fluid and whole cells of
Rhizobium trifolii
were examined for effects on root hair morphology of white clover seedlings (
Trifolium repens
var. Ladino). Cell-free culture fluid, exopolysaccharides, supernatant fluid from the precipitation of the exopolysaccharides, capsular polysaccharides, lipopolysaccharides, and a protein fraction from culture fluids were assayed for morphogenetic effects on the root hairs of axenically grown clover seedlings. Crude fractions were chromatographed on Bio Gel A-5m (Bio-Rad Laboratories), and fractions collected were similarly assayed. Hexose, uronic acid, and protein concentrations were determined for all fractions assayed. Gel chromatography indicated the materials with deforming ability to be of high molecular weight (>10,000). For all fractions except exopolysaccharide, deforming ability was associated with a protein component. This suggested that two components were associated with deformation; both contained polysaccharides and one contained protein. Crude fractions differed in their ability to cause deformations and indicated the following relative ability (in decreasing order) to deform root hairs: cell-free culture fluid, capsular polysaccharides, protein from culture fluids, exopolysaccharide, and cell envelope. Lipopolysaccharides had no effect.
Factors Affecting the Germination of Akinetes of
Nodularia spumigena
(
Cyanobacteriaceae
)
Authors: Huber Ann L.
Published: January 2020

Nutritional and physical factors which influence the germination of akinetes of
Nodularia spumigena
(Cyanobacteriaceae) were examined. Low concentrations of phosphorus (<0.9 μM) were required for germination. Nitrate had no effect, but ammonia, at concentrations of >45 μM, inhibited germination. Salinities of >20‰ were inhibitory to germination. Optimum temperatures were 22°C or greater. Germination did not take place in the dark, but only very low light intensities (0.5 microeinstein m
−2
s
−1
) were necessary to initiate germination. Red light (620 to 665 nm) was required. More than 24 h of continuous exposure to light was necessary for any significant germination to occur. The conditions for germination corresponded with conditions in the Peel-Harvey Estuary, Western Australia, 2 to 3 weeks before large summer
Nodularia
blooms.
Localization of Polyvinyl Alcohol Oxidase Produced by a Bacterial Symbiont,
Pseudomonas
sp. Strain VM15C
Authors: Shimao Masayuki , Nishimura Yuji , Kato Nobuo , Sakazawa Chikahiro
Published: January 2020

An axenic culture of a polyvinyl alcohol (PVA)-degrading symbiont,
Pseudomonas
sp. strain VM15C, was established on PVA with a crude preparation of the growth factor (factor A) produced by the symbiotic partner
Pseudomonas putida
VM15A. An increase of factor A in the culture medium enhanced the cell-associated PVA oxidase activity as well as the growth rate, but decreased production of extracellular PVA oxidase. PVA oxidase in cells grown on PVA was present in the periplasmic space at a higher ratio than in cells grown on peptone. PVA degradation occurred rapidly with washed cells. PVA was also degraded by immobilized cells entrapped in agar gels.
Adsorption of viruses to charge-modified silica
Authors: Zerda K S , Gerba C P , Hou K C , Goyal S M
Published: January 2020

The purpose of this study was to provide a clearer understanding of virus adsorption, focusing specifically on the role of electrostatic interactions between virus particles and adsorbent surfaces. The adsorption of poliovirus 1, reovirus types 1 and 3, and coliphages MS-2 and T2 to colloidal silica synthetically modified to carry either positive or negative surface charge was evaluated. Adsorption experiments were performed by combining virus and silica in 0.1-ionic-strength buffers of pH 4.0, 6.4, and 8.5. Samples agitated for specified adsorption periods were centrifuged to pellet adsorbent particles plus adsorbed virus, and the supernatants were assayed for unadsorbed virus. All viruses adsorbed exclusively to negatively charged silica at pH values below their isoelectric points, i.e., under conditions favoring a positive surface charge on the virions. Conversely, all viruses adsorbed exclusively to positively charged silica at pH values above their isoelectric points, i.e., where virus surface charge is negative. Viruses in near-isoelectric state adsorbed to all types of silica, albeit to a lesser degree.
Fermentation by a new daunomycin-producing organism, Streptomyces insignis ATCC 31913
Authors: Tunac J B , Graham B D , Dobson W E , Lenzini M D
Published: January 2020

A new organism belonging to the grey series of streptomycetes is described which produces 55 to 75 micrograms of daunomycin per ml in a sparged fermentor. This organism is not taxonomically related to other known daunomycin producers. Its proposed name in Streptomyces insignis ATCC 31913.
Production and Characterization of Polymeric Lignin Degradation Intermediates from Two Different
Streptomyces
spp
Authors: Borgmeyer Jeffry R. , Crawford Don L.
Published: January 2020

Previous investigations have identified a quantitatively major intermediate of lignin degradation by
Streptomyces viridosporus
. The intermediate, a modified lignin polymer, acid-precipitable polymeric lignin (APPL), is released as a water-soluble catabolite and has been recovered in amounts equivalent to 30% of the lignin originally present in a corn stover lignocellulose substrate after degradation by this actinomycete. In the present work, APPLs were collected at various time intervals from cultures of two highly ligninolytic
Streptomyces
sp. strains,
S. viridosporus
T7A and
S. badius
252, growing on corn stover lignocellulose. APPL production was measured over time, and the chemistry of APPLs produced by each organism after different time intervals was compared. Chemical characterizations included assays for lignin, carbohydrate, and ash contents, molecular weight distributions by gel permeation chromatography, and chemical degradation analyses by permanganate oxidation, acidolysis, and alkaline ester hydrolysis. Differences between the organisms were observed in the cultural conditions required for APPL production and in the time courses of APPL accumulation.
S. viridosporus
produced APPL in solid-state fermentation over a 6- to 8-week incubation period, whereas
S. badius
produced as much or more APPL, but only in liquid culture and over a 7- to 8-day incubation period. The chemistry of the APPLs produced also differed.
S. viridosporus
APPL was more lignin-like than that of
S. badius
and was slowly modified further over time, although no change in molecular weight distribution over time was observed. In contrast,
S. badius
APPL was less lignin-like and increased substantially in average molecular weight over time. Results indicated that differing mechanisms of lignin metabolism may exist in these two
Streptomyces
sp. strains.
S. viridosporus
APPL probably originates from the heart of the lignin and is released largely as the result of β-ether cleavage and other oxidative reactions.
S. badius
APPL probably originates in the same manner; however, after release as a water-soluble catabolite, lower-molecular-weight intermediates of lignin degradation are repolymerized with APPL in a reaction catalyzed by an extracellular phenol oxidase. The chemical analyses and the presence of extracellular phenol oxidase in
S. badius
, but not in
S. viridosporus
, support this conclusion.
Comparison of the airborne survival of calf rotavirus and poliovirus type 1 (Sabin) aerosolized as a mixture
Authors: Ijaz M K , Sattar S A , Johnson-Lussenburg C M , Springthorpe V S
Published: January 2020

A mixture of a cell culture-adapted strain (C-486) of calf rotavirus and poliovirus type 1 (Sabin) was prepared in tryptose phosphate broth containing 0.1% uranine (physical tracer) and antifoam at a final concentration of 0.001%. By using a six-jet Collison nebulizer, the mixture was aerosolized into a 300-liter stainless-steel rotating (4 rpm) drum. The temperature of the air inside the drum was kept at 20 +/- 1 degrees C, and the virus aerosols were held at the following three levels of relative humidity (RH): low (30 +/- 5%), medium (50 +/- 5%), and high (80 +/- 5%). An all-glass impinger, containing 10.0 ml of tryptose phosphate broth with antifoam, was used to collect samples of air from the drum. Both viruses were propagated and quantitated in MA-104 cells. The calf rotavirus was found to survive well at mid-range RH, where 60% of the infectious virus could be detected even after 24 h of virus aerosolization. At the low RH, the half-life of the infectious rotavirus was ca. 14 h. On the other hand, no infectious poliovirus could be recovered from the drum air at the low and medium RH. At the high RH, more than 50% of the infectious rotavirus became undetectable within 90 min of aerosolization. In contrast to this, the half-life of the poliovirus at the high RH was about 10 h. These data, based on the aerosolization of virus mixtures, therefore suggest that there is a pronounced difference in the way RH influences the airborne survival of these two types of viruses held under identical experimental conditions.
Persistence of Denitrifying Enzyme Activity in Dried Soils
Authors: Smith M. Scott , Parsons Laura L.
Published: January 2020

The effects of air drying soil on denitrifying enzyme activity, denitrifier numbers, and rates of N gas loss from soil cores were measured. Only 29 and 16% of the initial denitrifying enzyme activity in fresh, near field capacity samples of Maury and Donerail soils, respectively, were lost after 7 days of air drying. The denitrifying activity of bacteria added to soil and activity recently formed in situ were not stable during drying. When dried and moist soil cores were irrigated, evolution of N gas began, and it maximized sooner in the dried cores. This suggests that the persistence of denitrifying enzymes permits accelerated denitrification when dried soils are remoistened. Enzyme activity increased significantly in these waterlogged cores, but fluctuations in enzyme activity were small compared with fluctuations in actual denitrification rate, and enzyme activities were always greater than denitrification rates. Apparent numbers of isolatable denitrifiers (most-probable-number counts) decreased more than enzyme activity as the soils were dried, but after the soils were rewetted, the extent of apparent growth was not consistently related to the magnitude of N loss. We hypothesize that activation-inactivation of existing enzymes by soil O
2
is of greater significance in transient denitrification events than is growth of denitrifiers or synthesis of new enzymes.
Optimum conditions for ursodeoxycholic acid production from lithocholic acid by Fusarium equiseti M41
Authors: Kulprecha S , Ueda T , Nihira T , Yoshida T , Taguchi H
Published: January 2020

Ursodeoxycholic acid dissolves cholesterol gallstones in humans. In the present study optimum conditions for ursodeoxycholic acid production by Fusarium equiseti M41 were studied. Resting mycelia of F. equiseti M41 showed maximum conversion at 28 degrees C, pH 8.0, and dissolved oxygen tension of higher than 60% saturation. Monovalent cations, such as Na+, K+, and Rb+, stimulated the conversion rate more than twofold. In the presence of 0.5 M KCl, the initial uptake rate and equilibrium concentration of lithocholic acid (substrate) were enhanced by 5.7- and 1.7-fold, respectively. We confirmed that enzyme activity catalyzing 7 beta-hydroxylation of lithocholic acid was induced by substrate lithocholic acid. The activity in the mycelium was controlled by dissolved oxygen tension during cultivation: with a dissolved oxygen tension of 15% and over, the activity peak appeared at 25 h of cultivation, whereas the peak was delayed to 34 and 50 h with 5 and 0% dissolved oxygen tension, respectively. After reaching the maximum, the 7 beta-hydroxylation activity in the mycelium declined rapidly at pH 7.0, but the decline was retarded by increasing the pH to 8.0. Several combinations of operations, such as pH shift (from pH 7 to 8), addition of 0.5 M KCl, and dissolved oxygen control, were applied to the production of ursodeoxycholic acid in a jar fermentor, and a much larger amount of ursodeoxycholic acid (1.2 g/liter) was produced within 96 h of cultivation.
Aromatic and Volatile Acid Intermediates Observed during Anaerobic Metabolism of Lignin-Derived Oligomers
Authors: Colberg P. J. , Young L. Y.
Published: January 2020

Anaerobic enrichment cultures acclimated for 2 years to use a
14
C-labeled, lignin-derived substrate with a molecular weight of 600 as a sole source of carbon were characterized by capillary and packed column gas chromatography. After acclimation, several of the active methanogenic consortia were inhibited with 2-bromoethanesulfonic acid, which suppressed methane formation and enhanced accumulation of a series of metabolic intermediates. Volatile fatty acids levels in 2-bromoethanesulfonic acid-amended cultures were 10 times greater than those in the uninhibited, methane-forming consortia with acetate as the predominant component. Furthermore, in the 2-bromoethanesulfonic acid-amended consortia, almost half of the original substrate carbon was metabolized to 10 monoaromatic compounds, with the most appreciable quantities accumulated as cinnamic, benzoic, caffeic, vanillic, and ferulic acids. 2-Bromoethanesulfonic acid seemed to effectively block CH
4
formation in the anaerobic food chain, resulting in the observed buildup of volatile fatty acids and monoaromatic intermediates. Neither fatty acids nor aromatic compounds were detected in the oligolignol substrate before its metabolism, suggesting that these anaerobic consortia have the ability to mediate the cleavage of the β-aryl-ether bond, the most common intermonomeric linkage in lignin, with the subsequent release of the observed constituent aromatic monomers.
Virion conformational forms and the complex inactivation kinetics of echovirus by chlorine in water
Authors: Young D C , Sharp D G
Published: January 2020

Aberrant inactivation kinetics were observed when monodispersed echovirus type 1 (Farouk) was inactivated with chlorine. An initial 1- to 2-log10-unit decrease in titer was followed by lag period, during which the titer stayed the same or increased, and this was followed by a final decline in titer. First-order kinetics were obtained with poliovirus type 1 under the same conditions. Isoelectric focusing studies of echovirus before chlorine treatment showed that the virus distributed into two pH-dependent and interconvertible isoelectric forms. After chlorine treatment all remaining virus infectivity was associated with a third pH-independent isoelectric form. The complex inactivation kinetics appeared to be due to shifts between these conformational forms during inactivation in certain ionic environments. Under certain conditions the conformational shifts resulted in substantial resistance of monodispersed echovirus to chlorine.
Solid-State Fermentation: an Alternative to Improve the Nutritive Value of Coffee Pulp
Authors: Peñaloza Walter , Molina Mario R. , Brenes Roberto Gomez , Bressani Ricardo
Published: January 2020

Coffee pulp was subjected to a solid-state fermentation process, using
Aspergillus niger
. The initial moisture content of the pulp, as well as the fermentation time and temperature, had a significant effect on the increase in total amino acid content of the material. The increase in total amino acids showed a significant correlation with the dry matter recovered (
r
= −0.98) and the increase in pH during the process (
r
= 0.98). With a moisture content of 80%, a pH of 3.5, a temperature of 35°C, and an aeration of 8 liters/min per kg as fermentation conditions, it was found that the maximum concentration of total amino acids was attained after 43 h. The fermented product had a higher total amino acid content and a lower cell wall constituent value (primarily cellulose and hemicellulose) than the original pulp. A growing chicken's ration containing 10% of the fermented product had a feed efficiency (2.14) similar to that of the standard ration (2.19) and was significantly better than that of the diet containing 10% of the original pulp (2.53). The difference observed in feed intake and weight gain between the standard diet and that with 10% of the fermented product is considered to be due to palatability factors which should be studied further.
Influence of Easily Degradable Naturally Occurring Carbon Substrates on Biodegradation of Monosubstituted Phenols by Aquatic Bacteria
Authors: Shimp Robert J. , Pfaender Frederic K.
Published: January 2020

The influence of readily degradable, naturally occurring carbon substrates on the biodegradation of several monosubstitued phenols (
m
-cresol,
m
-aminophenol,
p
-chlorophenol) was examined. The natural substrate classes used were amino acids, carbohydrates, and fatty acids. Samples of the microbial community from Lake Michie, a mesotrophic reservoir, were adapted to different levels of representatives from each natural substrate class in chemostats. After an extended adaptation period, the ability of the microbial community to degrade the monosubstituted phenols was determined by using a radiolabeled substrate uptake and mineralization method. Several microbiological characteristics of the communities were also measured. Adaptation to increasing concentrations of amino acids, carbohydrates, or fatty acids enhanced the ability of the microbial community to degrade all three phenols. The stimulation was largest for
m
-cresol and
m
-aminophenol. The mechanism responsible for the enhancement of monosubstituted phenol metabolism was not clearly identified, but the observation that adaptation to amino acids also increased the biodegradation of glucose and, to a lesser extent, naphthalene suggests a general stimulation of microbial metabolism. This study demonstrates that prior exposure to labile, natural substrates can significantly enhance the ability of aquatic microbial communities to respond to xenobiotics.
Microcalorimetric Approach to Determine Relationships between Energy Supply and Metabolism in River Epilithon
Authors: Lock Maurice A. , Ford Timothy E.
Published: January 2020

In a study to determine the relative importance of various apparent molecular weight fractions to the metabolism (heat output) of attached microorganisms in rivers, a marked lack of response to gross changes in the external organic matter supply was noted over the course of several hours. Such a response by a mixed autotrophic-heterotrophic community could be attributed to the autotrophs being the sole organic energy source for the heterotrophs. However, substantial metabolic activities were noted in attached microbial communities grown in darkness (algae free), thus indicating that riverborne organic matter was a major energy source. This paradox was attributed to a proposed lag in the availability of dissolved and colloidal organic matter to the heterotrophic microorganisms.