bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation of
Phaffia rhodozyma
Mutants with Increased Astaxanthin Content
Authors: An Gil-Hwan , Schuman Donald B. , Johnson Eric A.
Published: January 2020

Plating of the astaxanthin-producing yeast
Phaffia rhodozyma
onto yeast-malt agar containing 50 μM antimycin A gave rise to colonies of unusual morphology, characterized by a nonpigmented lower smooth surface that developed highly pigmented vertical papillae after 1 to 2 months. Isolation and purification of the pigmented papillae, followed by testing for pigment production in shake flasks, demonstrated that several antimycin isolates were increased two- to fivefold in astaxanthin content compared with the parental natural isolate (UCD-FST 67-385). One of the antimycin strains (ant-1) and a nitrosoguanidine derivative of ant-1 (ant-1-4) produced considerably more astaxanthin than the parent (ant-1 had 800 to 900 μg/g; ant-1-4 had 900 to 1,300 μg/g; and 67-385 had 300 to 450 μg/g). The mutant strains were compared physiologically with the parent. The antimycin mutants grew slower on ammonia, glutamate, or glutamine as nitrogen sources compared with the natural isolate and also had lower cell yields on several carbon sources. Although isolated on antimycin plates, they were found to be more susceptible to antimycin A, apparently owing to the spatial separation of the papillae from the agar. They were also more susceptible than the parent to the respiratory inhibitor thenoyltrifluoroacetone and were slightly more susceptible to cyanide, but did not differ from the natural isolate in susceptibility to azide. The antimycin-derived strains were also killed faster than the parent by hydrogen peroxide. The carotenoid compositions of the parent and the antimycin-derived strains were similar to those previously determined in the type strain (UCD-FST 67-210) except that two carotenoids not previously found in the type strain were present in increased quantities in the antimycin mutants and phoenicoxanthin was a minor component. The chemical properties of the unknown carotenoids suggested that the strains isolated on antimycin agar tended to oxygenate and desaturate carotene precursors to a greater extent than the parent. The physiology of the antimycin isolates and the known specificity of antimycin for cytochrome
b
in the respiratory chain suggests that alteration of cytochrome
b
or cytochrome P-450 components involved in oxygenation and desaturation of carotenes in mitochondria are affected, which results in increased astaxanthin production. These astaxanthin-overproducing mutants and more highly pigmented derivative strains could be useful in providing a natural source of astaxanthin for the pen-reared-salmon industry or for other farmed animals that contain astaxanthin as their principal carotenoid.
Cloning of the Membrane-Bound Aldehyde Dehydrogenase Gene of
Acetobacter polyoxogenes
and Improvement of Acetic Acid Production by Use of the Cloned Gene
Authors: Fukaya Masahiro , Tayama Kenji , Tamaki Toshimi , Tagami Haruko , Okumura Hajime , Kawamura Yoshiya , Beppu Teruhiko
Published: January 2020

A genomic clone bank of
Acetobacter polyoxogenes
NBI1028 constructed in
Escherichia coli
by use of the expression vector pUC18 was screened with antibody raised against membrane-bound aldehyde dehydrogenase (ALDH; 75 kilodaltons [kDa]) from
A. polyoxogenes
NBI1028. A clone that synthesized a 41-kDa protein cross-reactive with anti-ALDH antibody was isolated. For cloning of the full-length ALDH structural gene, a cosmid gene bank was screened by Southern blot hybridization with the cloned DNA as a probe, and subcloning from the positive cosmid clone was performed with shuttle vector pMV24. Plasmid pAL25, containing the full-length ALDH structural gene, was isolated and expressed in both
E. coli
and
Acetobacter aceti
to produce a fused protein (78 kDa) with a short NH
2
-terminal β-galactosidase peptide. pAL25 conferred ALDH production on a mutant of
A. aceti
lacking the enzyme activity. Transformation of
A. aceti
subsp.
xylinum
NBI2099 with pAL25 caused 2- and 1.4-fold increases in the production rate and in the maximum concentration of acetic acid in submerged fermentation, respectively.
Polyphosphate-degrading enzymes in Acinetobacter spp. and activated sludge
Authors: van Groenestijn J W , Bentvelsen M M , Deinema M H , Zehnder A J
Published: January 2020

Polyphosphate-degrading enzymes were studied in Acinetobacter spp. and activated sludge. Polyphosphate: AMP phosphotransferase activity in Acinetobacter strain 210A decreased with increasing growth rates. The activity of this enzyme in cell extracts of Acinetobacter strain 210A was maximal at a pH of 8.5 and a temperature of 40 degrees C and was stimulated by (NH4)2SO4. The Km for AMP was 0.6 mM, and the Vmax was 60 nmol/min per mg of protein. Cell extracts of this strain also contained polyphosphatase, which was able to degrade native polyphosphate and synthetic magnesium polyphosphate and was strongly stimulated by 300 to 400 mM NH4Cl. A positive correlation was found between polyphosphate:AMP phosphotransferase activity, adenylate kinase activity, and phosphorus accumulation in six Acinetobacter strains. Significant activities of polyphosphate kinase were detected only in strain P, which contained no polyphosphate:AMP phosphotransferase. In samples of activated sludge from different plants, the activity of adenylate kinase correlated well with the ability of the sludge to remove phosphate biologically from wastewater.
Effect of Fluoride on Nitrification of a Concentrated Industrial Waste
Authors: Clarkson William W. , Collins Anthony G. , Sheehan Pamela L.
Published: January 2020

The potential for biological nitrification of an industrial waste containing 4,000 mg of ammonia N (NH
4
+
-N) and 10,000 mg of fluoride per liter was investigated. Ammonium sulfate and sodium fluoride were tested in various combinations of 100 to 2,000 mg of NH
4
+
-N per liter and 0 to 5,000 mg of F
−
per liter in suspended-growth stirred-tank reactors containing enriched cultures of nitrifying bacteria from a municipal sewage treatment plant. The stirred-tank reactors were fed once per day at a constant hydraulic retention period and cell retention time of 10 days. Temperature was 23°C, and pH was 7.0 to 7.5. Clarified secondary effluent was used to make up feeds and to provide minor nutrients. Steady-state data, confirmed by mass balances, were obtained after five to six retention periods. In the absence of fluoride, nitrification efficiency was near 100% for up to 500 mg of NH
4
+
-N per liter. The influence of fluoride was studied at a low ammonia concentration (100 mg/liter) and exerted no significant effect on nitrification at concentrations of up to 200 mg/liter. Maximum effect of fluoride was reached at 800 mg of F
−
per liter, and no greater inhibition was observed for up to 5,000 mg of F
−
per liter. At the highest concentrations studied, ion pairing of ammonium and fluoride may exert a significant effect on kinetic coefficients. Kinetic analyses showed maximum specific substrate removal rates (
q
max
) of NH
4
+
-N to be about 2.3 mg of N per mg of volatile suspended solids per day in the absence of fluoride and 0.85 mg of N per mg of volatile suspended solids per day in the presence of fluoride. The form of inhibition due to the presence of fluoride was shown to be not competitive, conforming to a mixed inhibition model.
Effect of visible light on progressive dormancy of Escherichia coli cells during the survival process in natural fresh water
Authors: Barcina I , González J M , Iriberri J , Egea L
Published: January 2020

Some effects of visible light on the survival of Escherichia coli in waters of the Butrón river were studied by comparing illuminated and nonilluminated systems. The following count methods were used: CFU on a selective medium (eosin-methylene blue agar), CFU on a medium of recuperation (Trypticase soy agar with yeast extract and glucose), number of metabolically active cells by reduction of 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to INT-formazan, and total number of E. coli cells as determined by the acridine orange direct-count method. In the illuminated systems, decreases in CFU of E. coli and in the number of metabolically active cells were observed. However, no decline of the total number of E. coli cells was observed. By count methods, different stages of progressive dormancy of E. coli cells were determined to exist in illuminated systems. Culturable and recoverable cells were defined as viable cells, and metabolically active cells and morphologically intact cells were defined as somnicells. Indirect activity measurements were also done by using [14C]glucose. In illuminated systems, a decrease of glucose uptake by E. coli cells was observed throughout the experiments. The assimilated fraction of [14C]glucose decreased faster than the respired fraction in illuminated systems. The percentage of respired [14C]glucose (14CO2 production) with respect to the total glucose uptake increased throughout the experiments, and the percentage of assimilated glucose decreased. Therefore, the visible light was also responsible for an additional inhibition of biosynthetic processes.
Expression in Bacillus subtilis of the 51- and 42-kilodalton mosquitocidal toxin genes of Bacillus sphaericus
Authors: Baumann L , Baumann P
Published: January 2020

A 3,080-base-pair KpnI-HindIII DNA fragment from Bacillus sphaericus 2362 coding for 51- and 42-kilodalton mosquitocidal proteins was cloned into Bacillus subtilis DB104 by using the vector pUB18. In B. subtilis these proteins were not detected during vegetative growth but were expressed during sporulation at levels comparable to those found in B. sphaericus.
Chemotaxis in
Methanospirillum hungatei
Authors: Migas John , Anderson Karen L. , Cruden D. L. , Markovetz A. J.
Published: January 2020

Methanospirillum hungatei
gave a positive chemotactic response to acetate.
Bacterial Population Development and Chemical Characteristics of Refuse Decomposition in a Simulated Sanitary Landfill
Authors: Barlaz M. A. , Schaefer D. M. , Ham R. K.
Published: January 2020

Population development of key groups of bacteria involved in municipal refuse conversion to methane was measured from the time of initial incubation through the onset of methane production. Hemicellulolytic bacteria, cellulolytic bacteria, hydrogen-producing acetogens, and acetate- and H
2
-plus-CO
2
-utilizing methanogens were enumerated by the most-probable-number technique with media containing oat spelt xylan, ball-milled cellulose, butyrate, acetate, and H
2
plus CO
2
, respectively. Refuse decomposition was monitored in multiple replicate laboratory-scale sanitary landfills. A laboratory-scale landfill was dismantled weekly for microbial and chemical analysis. Leachate was neutralized and recycled to ensure methanogenesis. The methane concentration of the sampled containers increased to 64% by day 69, at which time the maximum methane production rate, 929 liters of CH
4
per dry kg-year, was measured. Population increases of 2, 4, 5, 5, and 6 orders of magnitude were measured between fresh refuse and the methane production phase for the hemicellulolytic bacteria, cellulolytic bacteria, butyrate-catabolizing acetogens, and acetate- and H
2
-CO
2
-utilizing methanogens, respectively. The cellulolytic bacteria and acetogens increased more slowly than the methanogens and only after the onset of methane production. The initial decrease in the pH of the refuse ecosystem from 7.5 to 5.7 was attributed to the accumulation of acidic end products of sugar fermentation, to the low acid-consuming activity of the acetogenic and methanogenic bacteria, and to levels of oxygen and nitrate in the fresh refuse sufficient for oxidation of only 8% of the sugars to carbon dioxide and water. Cellulose and hemicellulose decomposition was most rapid after establishment of the methanogenic and acetogenic populations and a reduction in the initial accumulation of carboxylic acids. A total of 72% of these carbohydrates were degraded in the container sampled after 111 days. Initially acetate utilization, but ultimately polymer hydrolysis, limited the rate of refuse conversion to methane. Microbial and chemical composition data were combined to formulate an updated description of refuse decomposition in four phases: an aerobic phase, an anaerobic acid phase, an accelerated methane production phase, and a decelerated methane production phase.
Transformation of Metalaxyl by the Fungus
Syncephalastrum racemosum
Authors: Zheng Zhong , Liu Shu-Yen , Freyer Alan J. , Bollag Jean-Marc
Published: January 2020

The fungus
Syncephalastrum racemosum
(Cohn) Schroeter was found to transform the fungicide metalaxyl [
N
-(2,6-dimethylphenyl)-
N
-(methoxyacetyl)-alanine methyl ester] in pure culture. After 21 days of incubation in a basal medium amended with 5 μg of metalaxyl per ml, more than 80% of the compound was transformed by the fungus. The transformation rates decreased as the concentrations of metalaxyl increased from 5 to 100 μg/ml. No transformation was observed when the concentration of metalaxyl was higher than 200 μg/ml. Two isomeric metabolites and a mixture of two other isomeric metabolites were isolated from the organic extract of the growth medium and identified as
N
-(2-methyl-6-hydroxymethylphenyl)-
N
- and
N
-(2-hydroxymethyl-6-methylphenyl)-
N
-(methoxyacetyl)-alanine methyl ester and
N
-(3-hydroxy- and
N
-(5-hydroxy-2,6-dimethyl-phenyl)-
N
-(methoxyacetyl)-alanine methyl ester according to their mass-spectral and nuclear magnetic resonance-spectral characteristics. Benzylic hydroxylation of the methyl side chains and/or aromatic hydroxylation appeared to be the major reactions involved in the metabolism of metalaxyl.
Genetic transformation system for the aflatoxin-producing fungus Aspergillus flavus
Authors: Woloshuk C P , Seip E R , Payne G A , Adkins C R
Published: January 2020

A heterologous transformation system was developed for Aspergillus flavus with efficiencies greater than 20 stable transformants per micrograms of DNA. Protoplasts of uracil-requiring strains of the fungus were transformed with plasmid and cosmid vectors containing the pyr-4 gene of Neurospora crassa. Transformants were selected for their ability to grow and sporulate on medium lacking uracil. Vector DNA appeared to integrate randomly into the genome of A. flavus with a tendency for multiple, tandem insertion. Transformants with single or multiple insertions were stable after five consecutive transfers on medium containing uracil. Uracil-requiring recipient strains were obtained either by UV-irradiating conidia and selecting colonies resistant to 5-fluoroorotic acid or by transferring the mutated pyr locus to strains by parasexual recombination. This is the first report of a transformation system for an aflatoxin-producing fungus. The transformation system and the availability of aflatoxin-negative mutants provide a new approach to studying the biosynthesis and regulation of aflatoxin.
Occurrence and diurnal population fluctuations of the ruminal protozoan Microcetus lappus
Authors: Towne G , Nagaraja T G
Published: January 2020

A series of experiments with bison and cattle were conducted to obtain information on the relatively uncommon ruminal protozoan Microcetus lappus. Although M. lappus is a holotrich, diurnal changes in concentrations indicate that it follows a cycle unlike most other holotrichs, decreasing shortly after feed is offered and then gradually increasing over time. Concentrations of M. lappus varied widely among animals, exceeding 50% of the total protozoan population in some cattle. In bison, Microcetus concentrations averaged 2% of the protozoan population. Dietary protein and energy levels apparently did not influence Microcetus numbers. The highest concentrations of M. lappus were found in the reticulum, whereas the lowest numbers occurred in the mid-dorsal sac.
Isolation of Vibrio cholerae from aquatic birds in Colorado and Utah
Authors: Ogg J E , Ryder R A , Smith H L
Published: January 2020

Vibrio cholerae was isolated from cloacal swabs and freshly voided feces collected from 20 species of aquatic birds in Colorado and Utah during 1986 and 1987. About 17% (198 of 1,131) fecal specimens collected from July 1986 through August 1987 contained the organism. Both O1 and non-O1 V. cholerae strains were isolated from the fecal specimens. Isolates from eight birds (representing five species) agglutinated in O group 1 antiserum. Supernatants of broth cultures from three isolates which typed as V. cholerae O1 serotype Ogawa gave reactions typical of cholera toxin when tested on Y-1 mouse adrenal cell cultures. Several serovars of non-O1 V. cholerae were isolated from the fecal specimens; serovar 22 was the most prevalent type. All non-O1 isolates were cytotoxic to Y-1 mouse adrenal cells. Only non-O1 V. cholerae was detected in water samples collected from the habitat of the birds. The results of this study suggest that aquatic birds serve as carriers and disseminate V. cholerae over a wide area.
Worldwide Abundance and Distribution of
Bacillus thuringiensis
Isolates
Authors: Martin Phyllis A. W. , Travers Russell S.
Published: January 2020

We found the insect control agent
Bacillus thuringiensis
to be a ubiquitous soil microorganism. Using acetate selection to screen soil samples, we isolated
B. thuringiensis
in 785 of 1,115 soil samples. These samples were obtained in the United States and 29 other countries. A total of 48% of the
B. thuringiensis
isolates (8,916 isolates) fit the biochemical description of known varieties, while 52% represented undescribed
B. thuringiensis
types. Over 60% (1,052 isolates) of the isolates tested for toxicity were toxic to insects in the orders Lepidoptera or Diptera. Soil samples were collected from various habitats, including those habitats with different numbers of insects. The current presence of insects did not predict the presence of
B. thuringiensis
in a particular soil sample.
B. thuringiensis
was most abundant in samples from Asia.
Effect of Growth Conditions and Trehalose Content on Cryotolerance of Bakers' Yeast in Frozen Doughs
Authors: Gélinas Pierre , Fiset Gisèle , LeDuy Anh , Goulet Jacques
Published: January 2020

The cryotolerance in frozen doughs and in water suspensions of bakers' yeast (
Saccharomyces cerevisiae
) previously grown under various industrial conditions was evaluated on a laboratory scale. Fed-batch cultures were very superior to batch cultures, and strong aeration enhanced cryoresistance in both cases for freezing rates of 1 to 56°C min
−1
. Loss of cell viability in frozen dough or water was related to the duration of the dissolved-oxygen deficit during fed-batch growth. Strongly aerobic fed-batch cultures grown at a reduced average specific rate (μ = 0.088 h
−1
compared with 0.117 h
−1
) also showed greater trehalose synthesis and improved frozen-dough stability. Insufficient aeration (dissolved-oxygen deficit) and lower growth temperature (20°C instead of 30°C) decreased both fed-batch-grown yeast cryoresistance and trehalose content. Although trehalose had a cryoprotective effect in
S. cerevisiae
, its effect was neutralized by even a momentary lack of excess dissolved oxygen in the fed-batch growth medium.
Increase in colonic methanogens and total anaerobes in aging rats
Authors: Maczulak A E , Wolin M J , Miller T L
Published: January 2020

Methanogens are present in the colons of our local Wistar rat colony. We studied the changes in concentrations of their fecal methanogenic and nonmethanogenic bacteria with age as a model of the development of these communities in humans. We found that the predominant methanogen in the rats is a Methanobrevibacter species. The log of the concentration of total anaerobes increased from 9.8/g (dry weight) at 3.0 weeks of age (shortly after weaning) to 10.7/g (dry weight) at 96 weeks (shortly before the end of the life span). In contrast, the log concentration of methanogens increased from 5.5 to 9/g (dry weight) during the same time period. Therefore, methanogens increased as a percentage of the total anaerobes from 0.005% at 3.0 weeks to 2.0% at 96 weeks. About 12 doublings of the methanogenic population and 3.3 doublings of the nonmethanogenic population took place from weaning until death. The slow increase in the ratio of methanogens to total anaerobes with age followed the same pattern in cecal contents as found in feces. There were no relationships between animal weights or fecal outputs and the increase in total anaerobe and methanogen concentrations in feces. A possible explanation for the slow increase in the Methanobrevibacter species in Wistar rats with age is a gradual shifting of the use of electrons from the reduction of CO2 to acetate by acetogens to the reduction of CO2 to CH4. The results provide the first evidence for an age-related change in the nonmethanogenic bacteria of the colon and supporting microbiological evidence for physiological studies that have shown age-related increases in colonic methane production in humans.
Reinvestigation of
Brevibacterium
sp. Strain KY-4313 as a Source of Canthaxanthin
Authors: Nelis H. J. , De Leenheer A. P.
Published: January 2020

The hydrocarbon-utilizing
Brevibacterium
sp. strain KY-4313 was reevaluated for its potential to produce canthaxanthin, a carotenoid pigment of strong commercial interest. Three approaches were used to optimize the canthaxanthin yield from this organism, i.e., the preparation of mutants, the addition of supposedly carotenogenic chemicals to the growth medium, and growth promotion. Following treatment of the parent strain with
N
-nitrosomethylurea, a presumed mutant was isolated which showed a 32% increase in cellular canthaxanthin content. No effective carotenogenic chemicals were found in connection with hydrocarbon fermentations, in which mainly growth promotion through periodic medium renewal proved conducive to enhanced pigment production. Carotenogenesis could be stimulated in brain heart infusion broth by adding alcohols or retinol. Improved growth in this medium was generally not associated with higher canthaxanthin yields. Both superior growth and pigment levels were obtained in a newly designed medium based on fumaric acid-molasses. The maximum yields of canthaxanthin in shake flasks were (in milligrams per liter) 4.2 (brain heart infusion broth plus propanol-zinc sulfate), 3.6 (hydrocarbon medium), and 9.3 (fumaric acid-molasses), which represent a significant improvement over the originally reported optimal result (1 mg/liter). The corresponding yields of echinenone, the direct precursor of canthaxanthin, were 1.2, 1.6, and 2.3 mg/liter, respectively. Two-liter hydrocarbon batch fermentations involving medium renewal maximally produced 7.2 mg of canthaxanthin and 3.7 mg of echinenone per liter.
Cloning and characterization of the trpC gene from an aflatoxigenic strain of Aspergillus parasiticus
Authors: Horng J S , Linz J E , Pestka J J
Published: January 2020

The trpC gene in the tryptophan biosynthetic pathway was isolated from an aflatoxigenic Aspergillus parasiticus by complementation of an Escherichia coli trpC mutant lacking phosphoribosylanthranilate isomerase (PRAI) activity. The cloned gene complemented an E. coli trpC mutant deficient in indoleglycerolphosphate synthase (IGPS) activity as well as an Aspergillus nidulans mutant strain that was defective in all three enzymatic activities of the trpC gene (glutamine amidotransferase, IGPS, and PRAI), thus indicating the presence of a complete and functional trpC gene. The location and organization of the A. parasiticus trpC gene on the cloned DNA fragment were determined by deletion mapping and by hybridization to heterologous DNA probes that were prepared from cloned trpC genes of A. nidulans and Aspergillus niger. These experiments suggested that the A. parasiticus trpC gene encoded a trifunctional polypeptide with a functional domain structure organized identically to those of analogous genes from other filamentous fungi. The A. parasiticus trpC gene was expressed constitutively regardless of the nutritional status of the culture medium. This gene should be useful as a selectable marker in developing a DNA-mediated transformation system to analyze the aflatoxin biosynthetic pathway of A. parasiticus.
Characterization of a Lactobacillus strain producing white crystals on cheddar cheese
Authors: Rengpipat S , Johnson E A
Published: January 2020

From an enrichment culture of white-crystal deposits from aged Cheddar cheese, an atypical Lactobacillus strain was characterized. The new isolate is facultatively heterofermentative, has a G + C content of 40 mol%, and produces D and L isomers of lactic acid. The strain had a limited ability to ferment carbohydrates. It utilized fructose, galactose, glucose, lactose, maltose, mannose, and ribose but was negative for esculin, gluconate, citrate, and several other carbon sources. The isolate also had low DNA-DNA homologies with strains of Lactobacillus casei and Lactobacillus plantarum. Cheese prepared with milk containing the isolate developed white crystals during curing. Formation of copious D-lactate from unknown substrates during curing probably caused the white-crystal deposits. The strain has been deposited in the American Type Culture Collection (ATCC 49178).
Bioluminescence of the insect pathogen Xenorhabdus luminescens
Authors: Schmidt T M , Kopecky K , Nealson K H
Published: January 2020

Luminescence of batch cultures of Xenorhabdus luminescens was maximal when cultures approached stationary phase; the onset of in vivo luminescence coincided with a burst of synthesis of bacterial luciferase, the enzyme responsible for luminescence. Expression of luciferase was aldehyde limited at all stages of growth, although more so during the preinduction phase. Luciferase was purified from cultures of X. luminescens Hm to a specific activity of 4.6 x 10(13) guanta/s per mg of protein and found to be similar to other bacterial luciferases. The Xenorhabdus luciferase consisted of two subunits with approximate molecular masses of 39 and 42 kilodaltons. A third protein with a molecular mass of 24 kilodaltons copurified with luciferase, and in its presence, either NADH or NADPH was effective in stimulating luminescence, indicating that this protein is an NAD(P)H oxidoreductase. Luciferases from two other luminous bacteria, Vibrio harveyii (B392) and Vibrio cholerae (L85), were partially purified, and their subunits were separated in 5 M urea and tested for complementation with the subunits prepared from X. luminescens Hb. Positive complementation was seen with luciferase subunits among all three species. The slow decay kinetics of the Xenorhabdus luciferase were attributed to the alpha subunit.
Production of deoxynivalenol by Fusarium isolates from samples of wheat associated with a human mycotoxicosis outbreak and from sorghum cultivars
Authors: Ramakrishna Y , Bhat R V , Ravindranath V
Published: January 2020

Fusarium isolates from specific diseased sorghum plants and rain-soaked wheat and wheat flour associated with human mycotoxicosis in India have been screened for their toxigenic potential. Of the 322 isolates screened, 11 isolates were found to produce deoxynivalenol in concentrations ranging from 0.01 to 186 micrograms g-1. The occurrence of deoxynivalenol-producing fusaria in a nontemperate region and deoxynivalenol production in low concentrations by Fusarium moniliforme are reported for the first time.
Identification of Mycelium-Associated Cellulase from
Streptomyces reticuli
Authors: Wachinger Gisela , Bronnenmeier Karin , Staudenbauer Walter L. , Schrempf Hildgund
Published: January 2020

Among 180
Streptomyces
strains tested, 25 were capable of hydrolyzing microcrystalline cellulose (Avicel) at 30°C.
Streptomyces reticuli
was selected for further studies because of its ability to grow at between 30 and 50°C on Avicel. Enzymatic activities degrading Avicel, carboxymethyl cellulose, and cellobiose were found both in the culture supernatant and in association with the mycelium and crystalline substrate. The bound enzymes were efficiently solubilized by repeated washes with buffer of low ionic strength (50 mM Tris hydrochloride [pH 7.5]) and further purified by fast protein liquid chromatography. A high-molecular-weight Avicelase of >300 kilodaltons could be separated from carboxymethyl cellulase (CMCase) and β-glucosidase activities (molecular mass, 40 to 50 kilodaltons) by gel filtration on Superose 12. The CMCase fraction was resolved by Mono Q anion-exchange chromatography into two enzymes designated CMCase 1 and CMCase 2. The β-glucosidase activity was found to copurify with CMCase 2. The purified cellulase components showed optimal activity at around pH 7.0 and temperatures of between 45 and 50°C. Avicelase (but not CMCase) activity was stimulated significantly by the addition of CaCl
2
.
Sodium-dependent transport of branched-chain amino acids by a monensin-sensitive ruminal peptostreptococcus
Authors: Chen G J , Russell J B
Published: January 2020

A recently isolated ruminal peptostreptococcus which produced large amounts of branched-chain volatile fatty acids grew rapidly with leucine as an energy source in the presence but not the absence of Na. Leucine transport could be driven by an artificial membrane potential (delta psi) only when Na was available, and a chemical gradient of Na+ (delta uNa+) also drove uptake. Because Na+ was taken up with leucine and a Z delta pH could not serve as a driving force (with or without Na), it appeared that leucine was transported in symport with Na+. The leucine carrier could use Li as well as Na and had a single binding site for Na+. The Km for Na was 5.2 mM, and the Km and Vmax for leucine were 77 microM and 328 nmol/mg of protein per min, respectively. Since valine and isoleucine competitively inhibited (Kis of 90 and 49 microM, respectively) leucine transport, it appeared that the peptostreptococcus used a common carrier for branched-chain amino acids. Valine or isoleucine was taken up rapidly, but little ammonia was produced if they were provided individually. The lack of ammonia could be explained by an accumulation of reducing equivalents. The ionophore, monensin, inhibited growth, but leucine was taken up and deaminated at a slow rate. Monensin caused a loss of K, an increase in Na, a slight increase in delta psi, and a decrease in intracellular pH. The inhibition of growth was consistent with a large decrease in ATP.(ABSTRACT TRUNCATED AT 250 WORDS)
Differential Expression of Xylanases and Endoglucanases in the Hybrid Derived from Intergeneric Protoplast Fusion between a
Cellulomonas
sp. and
Bacillus subtilis
Authors: Gokhale D. V. , Deobagkar D. N.
Published: January 2020

A stable hybrid obtained by protoplast fusion between a
Cellulomonas
sp. and
Bacillus subtilis
exhibits an altered pattern of enzyme induction with different cellulosic substrates. Unlike in the
Cellulomonas
sp., xylanase was induced in the hybrid organism specifically by xylan, and endoglucanase was induced by carboxymethyl cellulose. The amount and specific activity of xylanase produced by the hybrid were more than those produced by the
Cellulomonas
sp. β-Glucosidase which is cell bound or intracellular in the
Cellulomonas
sp. was secreted by the hybrid organism, and relative amounts of extracellular β-glucosidase were high. Furthermore, this extracellular β-glucosidase activity was dependent on the nature of the cellulosic substrate. Endoglucanases synthesized in the hybrid differed in their electrophoretic mobilities as compared with the parental enzymes.
Electron Spin Resonance Analysis of the Effect of Butanol on the Membrane Fluidity of Intact Cells of
Clostridium acetobutylicum
Authors: Baer Shirley H. , Bryant Dennis L. , Blaschek Hans P.
Published: January 2020

Analysis of electron spin resonance spectra of 5-doxyl stearic acid in aqueous suspensions of
Clostridium acetobutylicum
ATCC 824 and the butanol-tolerant SA-2 derivative during a small-scale fermentation at three different butanol challenge levels indicated that the SA-2 strain is able to respond to the physical fluidizing effect of high (1.5%) butanol challenge by reducing its membrane fluidity at 12 and 30 h. The wild-type 824 strain was unable to so respond when challenged at the 1.5% level.
Characterization of the acclimation period before anaerobic dehalogenation of halobenzoates
Authors: Linkfield T G , Suflita J M , Tiedje J M
Published: January 2020

The acclimation periods prior to detectable dehalogenation of halogenated benzoates in anaerobic lake sediments ranged from 3 weeks to 6 months. These acclimation periods were reproducible over time and among sampling sites and were characteristic of the chemical tested. The lengthy acclimation period appears to represent an induction phase in which little or no aryl dehalogenation is observed, followed by an exponential increase in activity typical of an enrichment response. Continuous growth from the time of the first exposure to the chemical is inconsistent with the extremely low per-cell activities estimated for the early days of the acclimation period and the fact that the dehalogenation yields no carbon to support microbial growth. The finding of a characteristic acclimation time for each chemical argues against nutritional deficiency, inhibition, or predation as an explanation for this phase of metabolism, while the reproducibility of the findings with time and space and among replicates argues against genetic changes as the explanation. The acclimation times did correlate with the eventual dehalogenation rates. This may reflect the general energy limitations in the anaerobic communities and suggests that those chemicals with faster dehalogenation rates provide more energy for the induction and growth phases of the active population.
Inhibition of Listeria monocytogenes growth by the lactoperoxidase-thiocyanate-H2O2 antimicrobial system
Authors: Siragusa G R , Johnson M G
Published: January 2020

The lactoperoxidase-thiocyanate-H2O2 system (LP system), consisting of lactoperoxidase (0.37 U/ml), KSCN (0.3 mM), and H2O2 (0.3 mM), delayed but did not prevent growth of L. monocytogenes Scott A at 5, 10, 20, and 30 degrees C in broth and at 20 degrees C in milk. The net lag periods determined spectrophotometrically varied inversely with temperature and were shorter at 5 and 10 degrees C for cultures from shaken versus from statically grown inocula. Lag periods for cultures from shaken and statically grown inocula, respectively, were 73 and 98 h at 5 degrees C, 22 and 32 h at 10 degrees C, both 8.9 h at 20 degrees C, and both 2.8 h at 30 degrees C. After the lag periods, the maximum specific growth rates were similar for each of the three treatments (complete LP system, H2O2 alone, or control broth) at 5, 10, and 20 degrees C and were 0.06 to 0.08, 0.09 to 0.1, and 0.32 to 0.36/h, respectively. At 20 degrees C in sterile reconstituted skim milk, the LP system restricted growth of Scott A, with log CFU counts per ml at 0, 36, and 68 h being 5.7, 6.4 and 7.9 (versus 5.7, 9.8, and 11.2 for controls). Possible explanations for the decreased lag times observed for cultures from aerobically grown inocula are discussed.
Presence of the fish pathogen Vibrio salmonicida in fish farm sediments
Authors: Enger O , Husevåg B , Goksøyr J
Published: January 2020

The persistence of the fish pathogen Vibrio salmonicida in fish farm sediments was studied by use of fluorescent-antibody techniques. The specificities of the monoclonal antibodies and polyclonal rabbit serum used in the study were tested against a number of Vibrio strains, including 4 isolates from intestinal tracts of healthy fish and 98 isolates from sediments. V. salmonicida was detected in sediment samples from diseased farms several months after an outbreak of the disease. The bacterium was also detected in a sediment sample from a disease-free fish farm. No V. salmonicida could be detected in sediments not influenced by fish farming. The number of positive samples was generally higher with application of rabbit serum as opposed to use of monoclonal antibodies, indicating that the rabbit serum may cross-react with other bacteria.
Membrane fatty acid and virulence changes in the viable but nonculturable state of Vibrio vulnificus
Authors: Linder K , Oliver J D
Published: January 2020

The nonculturable state of Vibrio vulnificus and, for comparison, that of Escherichia coli were studied in artificial-seawater microcosms at 5 degrees C. Total cell counts were monitored by acridine orange epifluorescence, metabolic activity by direct viable counts, and culturability by plate counts on selective and nonselective media. Whereas total counts remained constant, plate counts of V. vulnificus suggested nonculturability by day 24. In contrast, direct viable counts indicated significant cell viability throughout 32 days of incubation. As an indication of the metabolic changes that occurred as cells entered the state of nonrecoverability, membrane fatty acid analyses were performed. At the point of nonculturability of V. vulnificus, the major fatty acid species (C16 and C16:1) had decreased 57% from the T0 level, concomitant with the appearance of several short-chain acids. Although the bacteria were still recoverable, a similar trend was observed with E. coli. Electron microscopy of nonculturable V. vulnificus showed that the cells were rounded and reduced in size and contained fewer ribosomes. Mouse infectivity studies conducted with these cells suggested loss of virulence.
Intratracheal exposure of rats to Aspergillus fumigatus spores isolated from sawmills in Sweden
Authors: Land C J , Sostarić B , Fuchs R , Lundström H , Hult K
Published: January 2020

Five strains of Aspergillus fumigatus (A, B, D, H, and K) isolated from sawmills were used to expose groups of three rats by intratracheal intubation. The dose was 10(9) spores per rat. At 48 h after administration, two rats from the D group and all rats from the K group died with symptoms of strong dyspnea and tachypnea. At 72 h postadministration and after, some animals showed mild to moderate dyspnea and tachypnea. Autopsies of all animals were performed, including a histopathological examination of the lungs. At 72 h after administration, two distinct morphological groups were identified histopathologically. Severe necrotizing pneumonia characterized by the presence of abundant fungal hyphae was seen in animals that died spontaneously within 48 h postadministration and rats with bronchopneumonia and was characterized by the presence of numerous fungal spores. There was an obvious difference in pathogenicity among the strains of A. fumigatus. Strains D and K were more pathogenic, and only the rats exposed to these strains showed the presence of fungal hyphae in the lungs. The mycotoxin gliotoxin that is produced by A. fumigatus and has antiphagocytic activity was not detected in the spores from any of the A. fumigatus strains.
Rate Equations and Kinetic Parameters of the Reactions Involved in Pyrite Oxidation by
Thiobacillus ferrooxidans
Authors: Lizama Hector M. , Suzuki Isamu
Published: January 2020

Rate equations and kinetic parameters were obtained for various reactions involved in the bacterial oxidation of pyrite. The rate constants were 3.5 μM Fe
2+
per min per FeS
2
percent pulp density for the spontaneous pyrite dissolution, 10 μM Fe
2+
per min per mM Fe
3+
for the indirect leaching with Fe
3+
, 90 μM O
2
per min per mg of wet cells per ml for the
Thiobacillus ferrooxidans
oxidation of washed pyrite, and 250 μM O
2
per min per mg of wet cells per ml for the
T. ferrooxidans
oxidation of unwashed pyrite. The

K
m

values for pyrite concentration were similar and were 1.9, 2.5, and 2.75% pulp density for indirect leaching, washed pyrite oxidation by
T. ferrooxidans
, and unwashed pyrite oxidation by
T. ferrooxidans
, respectively. The last reaction was competitively inhibited by increasing concentrations of cells, with a

K
i

value of 0.13 mg of wet cells per ml.
T. ferrooxidans
cells also increased the rate of Fe
2+
production from Fe
3+
plus pyrite.
Nuclear Magnetic Resonance Studies of Poly(3-Hydroxybutyrate) and Polyphosphate Metabolism in
Alcaligenes eutrophus
Authors: Doi Yoshiharu , Kawaguchi Yasushi , Nakamura Yoshiyuki , Kunioka Masao
Published: January 2020

The metabolic pathways of poly(3-hydroxybutyrate) (PHB) and polyphosphate in the microorganism
Alcaligenes eutrophus
H16 were studied by
1
H,
13
C, and
31
P nuclear magnetic resonance (NMR) spectroscopy and by conventional analytical techniques.
A. eutrophus
cells accumulated two storage polymers of PHB and polyphosphate in the presence of carbon and phosphate sources under aerobic conditions after exhaustion of nitrogen sources. The solid-state cross-polarization/magic-angle spinning
13
C NMR spectroscopy was used to study the biosynthetic pathways of PHB and other cellular biomass components from
13
C-labeled acetate. The solid-state
13
C NMR analysis of lyophilized intact cells grown on [1-
13
C]acetate indicated that the carbonyl carbon of acetate was selectively incorporated both into the carbonyl and methine carbons of PHB and into the carbonyl carbons of proteins. The
31
P NMR analysis of
A. eutrophus
cells in suspension showed that the synthesis of intracellular polyphosphate was closely related to the synthesis of PHB. The roles of PHB and polyphosphate in the cells were studied under conditions of carbon, phosphorus, and nitrogen source starvation. Under both aerobic and anaerobic conditions PHB was degraded, whereas little polyphosphate was degraded. The rate of PHB degradation under anaerobic conditions was faster than that under aerobic conditions. Under anaerobic conditions, acetate and 3-hydroxybutyrate were produced as the major extracellular metabolites. The implications of this observation are discussed in connection with the regulation of PHB and polyphosphate metabolism in
A. eutrophus.
Physicochemical interaction of Escherichia coli cell envelopes and Bacillus subtilis cell walls with two clays and ability of the composite to immobilize heavy metals from solution
Authors: Walker S G , Flemming C A , Ferris F G , Beveridge T J , Bailey G W
Published: January 2020

Isolated Escherichia coli K-12 cell envelopes or Bacillus subtilis 168 cell walls were reacted with smectite or kaolinite clay in distilled deionized water (pH 6.0); unbound envelopes or walls were separated by sucrose density gradient centrifugation, and the extent of adsorption was calculated. At saturation, both clays adsorbed approximately 1.0 mg (dry weight) of envelopes or walls per mg (dry weight) of clay. Clays showed a preference for edge-on orientation with both walls and envelopes, which was indicative of an aluminum polynuclear bridging mechanism between the wall or envelope surface and the clay edge. The addition of heavy metals increased the incidence of planar surface orientations, which suggested that multivalent metal cation bridging was coming into play and was of increasing importance. The metal-binding capacity of isolated envelopes, walls, clays, and envelope-clay or wall-clay mixtures was determined by atomic absorption spectroscopy after exposure to aqueous 5.0 mM Ag+, Cu2+, Cd2+, Ni2+, Pb2+, Zn2+, and Cr3+ nitrate salt solutions at pHs determined by the buffering capacity of wall, envelope, clay, or composite system. The order of metal uptake was walls greater than envelopes greater than smectite clay greater than kaolinite clay for the individual components, and walls plus smectite greater than walls plus kaolinite greater than envelopes plus smectite greater than envelopes plus kaolinite for the mixtures. On a dry-weight basis, the envelope-clay and wall-clay mixtures bound 20 to 90% less metal than equal amounts of the individual components did.(ABSTRACT TRUNCATED AT 250 WORDS)
Relationships among Cell Size, Membrane Permeability, and Preservative Resistance in Yeast Species
Authors: Warth Alan D.
Published: January 2020

The rate of uptake of propanoic acid and the cell dimensions were measured for 23 yeasts differing in their resistance to weak-acid-type preservatives. Relationships between reciprocal uptake rate, reciprocal permeability, cell volume, cell area, volume/area, and the MICs of benzoic acid and propanoic acid for the yeasts were tested by correlation analysis on pairs of parameters. The MIC of methylparaben, which is not a weak-acid-type preservative, was included. The most significant relationships found were between both reciprocal uptake rate and reciprocal permeability and the MICs of propanoic and benzoic acids Cell volume, area, and volume/area were each individually correlated with propanoic and benzoic acid MICs, but less strongly. In multiple regression analyses, inclusion of terms for volume, area, or volume/area did not markedly increase the significance. The MIC of methylparaben was unrelated to the uptake and permeability parameters, but did show a correlation with cell volume/area.
Schizosaccharomyces pombe
was anomalous in having very low permeability. Exclusion of these outlying data revealed particularly strong relationships (
P
< 0.001) between both reciprocal uptake rate and reciprocal permeability and the benzoic acid MIC. MICs for
Zygosaccharomyces bailii
isolates were substantially higher than for the other species, and therefore
Z. baillii
isolates had a large influence on the regressions. However, the relationships observed remained significant even after removal of the
Z. bailii
data. In showing a correlation between the rate at which propanoic acid enters yeast cells and the ability of the cells to tolerate this and other weak-acid-type preservatives, but not methylparaben, the results suggest that the resistance mechanism, in which preservative is continuously removed from the cell, is a common and major determinant of the preservative tolerance of yeast species.
Yeast Lipid Estimation by Enzymatic and Nuclear Magnetic Resonance Methods
Authors: Moreton R. S.
Published: January 2020

Low-resolution nuclear magnetic resonance and enzymatic glycerol estimation were compared with a solvent extraction method for estimating the intracellular lipid content of lipid-accumulating yeasts. Both methods correlated well with the solvent extraction procedure and were more convenient with large numbers of samples.
Enzyme activities and antibiotic susceptibility of colonial variants of Bacillus subtilis and Bacillus licheniformis
Authors: Carlisle G E , Falkinham J O
Published: January 2020

A nonmucoid colonial variant of a mucoid Bacillus subtilis strain produced less amylase activity and a transparent colonial variant of a B. licheniformis strain produced less protease activity compared with their parents. Antibiotic susceptibility patterns of the colonial variants differed, and increased resistance to beta-lactam antibiotics was correlated with increased production of extracellular beta-lactamase.