bluuebunny/crossref_metadata_2025 huggingface dataset:
Intracellular accumulation of AMP as a cause for the decline in rate of ethanol production by Saccharomyces cerevisiae during batch fermentation
Authors: Dombek K M , Ingram L O
Published: January 2020

A general hypothesis is presented for the decline in the rate of ethanol production (per unit of cell protein) during batch fermentation. Inhibition of ethanol production is proposed to result from the intracellular accumulation of AMP during the transition from growth to the stationary phase. AMP acts as a competitive inhibitor of hexokinase with respect to ATP. When assayed in vitro in the presence of ATP and AMP concentrations equivalent to those within cells at different stages of fermentation, hexokinase activity declined in parallel with the in vivo decline in the rate of ethanol production. The coupling of glycolytic flux and fermentation to cell growth via degradation products of RNA may be of evolutionary advantage for Saccharomyces cerevisiae. Such a coupling would reduce the exposure of nongrowing cells to potentially harmful concentrations of waste products from metabolism and would conserve nutrients for future growth under more favorable conditions.
Metabolism of Pyridine Compounds by Phthalate-Degrading Bacteria
Authors: Taylor Barrie F. , Amador José A.
Published: January 2020

Bacteria were isolated from marine sediments that grew aerobically on
m
-phthalate,
p
-phthalate, or dipicolinate (2,6-pyridine dicarboxylate [2,6-PDCA]). Strain OP-1, which grew on
o
-phthalate and was previously obtained from a marine source, was also studied. Intact cells of each organism demonstrated Na
+
-dependent oxidation of their growth substrates. Strain PCC5M grew on dipicolinate but did not metabolize
m
-phthalate. The phthalate degraders, however, demonstrated Na
+
-dependent metabolism of the appropriate PDCA analogs. 2,6-PDCA was transformed by strain CC9M when this strain was grown on
m
-phthalate, 2,5-PDCA was metabolized by strain PP-1 grown on
p
-phthalate, and 2,3-PDCA (quinolinate) was oxidized by strain OP-1 grown on
o
-phthalate. Spectral changes accompanying the Na
+
-dependent transformations of the PDCA analogs suggest the formation of hydroxylated compounds. Metabolism probably occurred via phthalate hydroxylases; this is a previously unrecognized route for the environmental transformation of pyridine compounds. Hydroxylated products may feed into known pathways for the catabolism of pyridines or be photochemically degraded because of their absorbance in the solar actinic range (wavelengths > 300 nm). The results reinforce recent evidence for the broad potential of aromatic hydroxylase systems for the destruction of pollutants.
Pressure-Induced Alterations in the Protein Pattern of the Thermophilic Archaebacterium
Methanococcus thermolithotrophicus
Authors: Jaenicke R. , Bernhardt G. , Lüdemann H.-D. , Stetter K. O.
Published: January 2020

Elevated hydrostatic pressure has been shown to affect the growth rate of the thermophilic methanobacterium
Methanococcus thermolithotrophicus
without extending its temperature range of viability. Analysis of the cell inventory after ≈ 10 h of incubation at 65°C and 50 MPa (applying high-pressure liquid chromatography and two-dimensional gel electrophoresis) proved that pressure induces alterations in the protein pattern and the amino acid composition of the total cell hydrolysate. Gels showed that after pressurization a series of (basic) proteins with a molecular mass in the range of 38 and 70 kilodaltons occurs which is not detectable in cells grown at normal atmospheric pressure. The question of whether the observed alterations are caused by the perturbation of the balance of protein synthesis and turnover or by the pressure-induced synthesis of compounds analogous to heat shock proteins remains unanswered.
Product Inhibition of Butyrate Metabolism by Acetate and Hydrogen in a Thermophilic Coculture
Authors: Ahring Birgitte K. , Westermann Peter
Published: January 2020

Studies on product inhibition of a thermophilic butyrate-degrading bacterium in syntrophic association with
Methanobacterium thermoautotrophicum
showed that a gas phase containing more than 2 × 10
−2
atm (2.03 kPa) of hydrogen prevented growth and butyrate consumption, while a lower hydrogen partial pressure of 1 × 10
−3
to 2 × 10
−2
atm (0.1 to 2.03 kPa) gradually inhibited the butyrate consumption of the coculture. No inhibition of butyrate consumption was found on the addition of 0.75 × 10
−3
atm (76 Pa) of hydrogen to the gas phase. A slight inhibition of butyrate consumption by the coculture occurred at an acetate concentration of 16.4 mM. Inhibition gradually increased with increasing acetate concentration up to 81.4 mM, when complete inhibition of butyrate consumption occurred. When the culture contained an acetate-utilizing methanogen in addition to
M. thermoautotrophicum
, the inhibition of the triculture by acetate was gradually reversed as the acetate concentration was lowered by the aceticlastic methanogen. The results show that optimal growth conditions for the thermophilic butyrate-degrading bacterium depend on both hydrogen and acetate removal.
Bacterial oxidation of chemical carcinogens: formation of polycyclic aromatic acids from benz[a]anthracene
Authors: Mahaffey W R , Gibson D T , Cerniglia C E
Published: January 2020

A Beijerinckia strain designated strain B1 was shown to oxidize benz[a]anthracene after induction with biphenyl, m-xylene, and salicylate. Biotransformation experiments showed that after 14 h a maximum of 56% of the benz[a]anthracene was converted to an isomeric mixture of three o-hydroxypolyaromatic acids. Nuclear magnetic resonance and mass spectral analyses led to the identification of the major metabolite as 1-hydroxy-2-anthranoic acid. Two minor metabolites were also isolated and identified as 2-hydroxy-3-phenanthroic acid and 3-hydroxy-2-phenanthroic acid. Mineralization experiments with [12-14C]benz[a]anthracene led to the formation of 14CO2. These results show that the hydroxy acids can be further oxidized and that at least two rings of the benz[a]anthracene molecule can be degraded.
Influence of Calcium Ion on Ethanol Tolerance of
Saccharomyces bayanus
and Alcoholic Fermentation by Yeasts
Authors: Nabais Regina C. , Sá-Correia Isabel , Viegas Cristina A. , Novais Júlio M.
Published: January 2020

The addition of Ca
2+
(as CaCl
2
) in optimal concentrations (0.75 to 2.0 mM) to a fermentation medium with a trace contaminating concentration of Ca
2+
(0.025 mM) led to the rapid production of higher concentrations of ethanol by
Saccharomyces cerevisiae, Saccharomyces bayanus
, and
Kluyveromyces marxianus
. The positive effect of calcium supplementation (0.75 mM) on alcoholic fermentation by
S. bayanus
was explained by the increase in its ethanol tolerance. The ethanol inhibition of growth and fermentation followed the equation μ

xi

= μ

oi

[1 - (
X/X

mi

)]

ni

, where μ

oi

and μ

xi

are, respectively, the specific growth (
i
=
g
) and fermentation (i =
f
) rates in the absence or presence of a concentration (
X
) of added ethanol, and
X

mi

is the maximal concentration of ethanol which allows growth or fermentation. The toxic power is given by
n

i

. In Ca
2+
- supplemented medium (0.75 mM),
n

g

= 0.42 for growth and
n

f

= 0.43 for fermentation compared with 0.52 and 0.55, respectively, in unsupplemented medium; for both media,
X

mg

= 10% (vol/vol) and
X

mf

= 13% (vol/vol). For lethal concentrations of ethanol, the specific death rates were minimal for cells that were grown and incubated with ethanol in medium with an optimal concentration of Ca
2+
, maximal for cells grown and incubated with ethanol in unsupplemented medium, and intermediate for cells grown in unsupplemented medium and incubated with ethanol in calcium-supplemented medium. The effect of Ca
2+
on the acidification curve of energized cells in the presence of ethanol was found to be closely associated with its protective effect on growth, fermentation, and viability.
Model suicide vector for containment of genetically engineered microorganisms
Authors: Bej A K , Perlin M H , Atlas R M
Published: January 2020

A model suicide vector (pBAP19h), designed for the potential containment of genetically engineered microorganisms, was made by constructing a plasmid with the hok gene, which codes for a lethal polypeptide, under the control of the lac promoter. The vector plasmid also codes for carbenicillin resistance. In the absence of carbenicillin, induction of the hok gene in vitro caused elimination of all detectable cells containing the suicide vector; pBAP19h-free cells of the culture survived and grew exponentially. In the presence of carbenicillin, however, the number of cells containing pBAP19h initially declined after induction of hok but then multiplied exponentially. The surviving cells still had a fully functional hok gene and had apparently developed resistance to the action of the Hok polypeptide. Thus, high selective pressure against the loss of the suicide vector led to a failure of the system. Soil microcosm experiments confirmed the ability of a suicide vector to restrict the growth of a genetically engineered microorganism in the absence of selective pressure against the loss of the plasmid, with 90 to 99% elimination of hok-bearing cells within 24 h of hok induction. However, some pBAP19h-bearing cells survived in the soil microcosms after hok induction. The surviving cells contained an active hok gene but were not capable of normal growth even after elimination of the hok gene; it appears that a mutation that made them Hok resistant also reduced their capacity for membrane functions needed for energy generation and exponential cell growth. Thus, the model suicide vector was shown to be functional in soil as well as in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)
Constitutive Expression of Enniatin Synthetase during Fermentative Growth of
Fusarium scirpi
Authors: Billich Andreas , Zocher Rainer
Published: January 2020

The production of enniatins by
Fusarium scirpi
during fermentative growth in submerged cultures was measured. The fungus produced the antibiotic during mycelial growth, but not during the stationary phase of cultivation. By contrast, enniatin synthetase, the enzyme responsible for enniatin synthesis, was present during growth, during the stationary phase, and even in spores. Similarly, the enniatin synthetase mRNA was present at every stage of the cultivation of the fungus. Therefore, this multifunctional peptide synthetase is a constitutive enzyme, the expression of which is not regulated by any specific mechanism. The findings stand in contrast to the common assumption that production of secondary metabolites underlies regulatory control, leading to separation of the trophophase and the idiophase.
Heat shock affects permeability and resistance of Bacillus stearothermophilus spores
Authors: Beaman T C , Pankratz H S , Gerhardt P
Published: January 2020

Heat shock of dormant spores of Bacillus stearothermophilus ATCC 7953 at 100 or 80 degrees C for short times, the so-called activation or breaking of dormancy, was investigated by separating the resulting spores by buoyant density centrifugation into a band at 1.240 g/ml that was distinct from another band at 1.340 g/ml, the same density as the original spores. The proportion of spores at 1.240 g/ml became larger when the original dormant spores were heated for a longer period of time, but integument-stripped dormant spores were quickly and completely converted to spores with a band at 1.240 g/ml. The spores with bands at both 1.240 and 1.340 g/ml were germinable faster than the original dormant spores and thus were considered to be activated. The spores with a band at 1.240 g/ml, which were considered to be fully activated, were apparently permeabilized, with a resulting complete depletion of dipicolinic acid, partial depletion of minerals, susceptibility to lysozyme action, permeation of the gradient medium, changed structural appearance in electron micrographs of thin-sectioned spores, and partly decreased heat resistance (D100 = 453 min) compared with the original dormant spores (D100 = 760 min). However, the fully activated spores with a band at 1.240 g/ml, although devoid of dipicolinic acid, still were much more resistant than germinated spores or vegetative cells (D100 = 0.1 min). The spores with a band at 1.340 g/ml, which were considered to be partly activated, showed no evidence of permeabilization and were much more heat resistant (D100 = 1,960 min) than the original dormant spores.(ABSTRACT TRUNCATED AT 250 WORDS)
Cloning of the
Thermomonospora fusca
Endoglucanase E2 Gene in
Streptomyces lividans:
Affinity Purification and Functional Domains of the Cloned Gene Product
Authors: Ghangas Gurdev S. , Wilson David B.
Published: January 2020

Thermomonospora fusca
YX grown in the presence of cellulose produces a number of β-1-4-endoglucanases, some of which bind to microcrystalline cellulose. By using a multicopy plasmid, pIJ702, a gene coding for one of these enzymes (E2) was cloned into
Streptomyces lividans
and then mobilized into both
Escherichia coli
and
Streptomyces albus.
The gene was localized to a 1.6-kilobase
Pvu
II-
Cla
I segment of the originally cloned 3.0-kilobase
Sst
I fragment of
Thermomonospora
DNA. The culture supernatants of
Streptomyces
transformants contain a major endoglucanase that cross-reacts with antibody against
Thermomonospora
cellulase E2 and has the same molecular weight (43,000) as
T. fusca
E2. This protein binds quickly and tightly to Avicel, from which it can be eluted with guanidine hydrochloride but not with water. It also binds to filter paper but at a slower rate than to Avicel. Several large proteolytic degradation products of this enzyme generated in vivo lose the ability to bind to Avicel and have higher activity on carboxymethyl cellulose than the native enzyme. Other smaller products bind to Avicel but lack activity. A weak cellobiose-binding site not observed in the native enzyme was present in one of the degradation products. In
E. coli
, the cloned gene produced a cellulase that also binds tightly to Avicel but appeared to be slightly larger than
T. fusca
E2. The activity of intact E2 from all organisms can be inactivated by Hg
2+
ions. Dithiothreitol protected against Hg
2+
inactivation and reactivated both unbound and Avicel-bound Hg
2+
-inhibited E2, but at different rates.
Mineralization of Diethylthiophosphoric Acid by an Enriched Consortium from Cattle Dip
Authors: Shelton Daniel R.
Published: January 2020

Enrichment cultures were initiated from cattle dip solution with diethylthiophosphoric acid (DETP) as the carbon and energy source. An enriched consortium consisting of at least six distinct bacterial species was subsequently obtained. The consortium mineralized DETP to sulfate and phosphate while utilizing ethyl moieties as a carbon and energy source. These data demonstrate that DETP can be metabolized under environmentally realistic conditions.
Metabolism of volatile chlorinated aliphatic hydrocarbons by Pseudomonas fluorescens
Authors: Vandenbergh P A , Kunka B S
Published: January 2020

A Pseudomonas fluorescens strain designated PFL12 was isolated from soil and water that were contaminated with various chloroaliphatic hydrocarbons. The isolate was able to metabolize 1,2-dichloroethane, 1,1,2-trichloroethane, 1,2-dichloropropane, 2,2-dichloropropane, and trichloroethylene.
Selenate reduction by bacteria from a selenium-rich environment
Authors: Maiers D T , Wichlacz P L , Thompson D L , Bruhn D F
Published: January 2020

Samples collected from Kesterson Reservoir were screened for bacterial presence and selenate reduction capability. Selenate concentrations of 100 mg/liter were not toxic to indigenous bacteria. Of the 44 samples collected, 20 possessed microbial populations capable of reducing selenate. Reduction was observed in 4% of the water samples, 92% of the sediment samples, and 100% of the soil samples. Microbial reduction of 100 mg of selenate per liter was complete within 1 week of incubation. Up to 75 mg of selenate per liter was reduced beyond selenite to an insoluble red precipitate. Data collected indicate that indigenous bacteria have a significant role in the biogeochemical cycling of selenium.
BamHI restriction endonuclease analysis of Yersinia ruckeri plasmids and their relatedness to the genus Yersinia 42- to 47-megadalton plasmid
Authors: Guilvout I , Quilici M L , Rabot S , Lesel R , Mazigh D
Published: January 2020

The plasmid profile and BamHI restriction pattern of 17 sorbitol-negative and 1 sorbitol-positive French Yersinia ruckeri strain of the American type strain were studied. The 17 sorbitol-negative strains and the American strain harbored a 62-megadalton (MDa) plasmid with an identical BamHI restriction pattern. Southern hybridization indicated that this 62-MDa plasmid is common among these various strains. The sorbitol-positive strain had four plasmid bands (70, 62, 32, and 25 MDa), and there was no comigration of the DNA fragments of these cleaved plasmids with the fragments of the 62-MDa plasmid. Hybridization of these restricted plasmids with the common 62-MDa plasmid showed a weak DNA homology. The Y. ruckeri plasmid (62 MDa) had a different molecular weight than the virulence plasmid (42 to 47 MDa) of the genus Yersinia, and they had different BamHI restriction patterns. Furthermore, no sequence of the Y. ruckeri plasmid DNA was recognized after Southern hybridization when the 47-MDa plasmid of Y. enterocolitica was used as a probe.
Procedure for isolating the endophyte from tall fescue and screening isolates for ergot alkaloids
Authors: Bacon C W
Published: January 2020

A procedure was developed to isolate and determine ergot alkaloid production by Acremonium coenophialum, the endophytic fungus of tall fescue. The procedure established that macerated leaf sheath or pith from inflorescence stem placed either in a liquid medium or on a corn meal-malt extract agar medium produced isolated mycelium and characteristic conidia within a 3- to 3.5-week period. Once isolated, each fungus was placed in another liquid medium, M104T, where competent strains produced total ergot alkaloids ranging from 38 to 797 mg/liter. Several isolates were negative for ergot alkaloid synthesis. The production of ergot alkaloids by individual isolates was unstable; isolates rapidly degenerated in their ability to produce ergot alkaloids during subculture. However, the procedure as presented allows the assessment of an isolate for ergot alkaloid synthesis during its initial isolation.
Identification of
Erwinia amylovora,
the Fireblight Pathogen, by Colony Hybridization with DNA from Plasmid pEA29
Authors: Falkenstein Hildegard , Bellemann Peter , Walter Sabine , Zeller Wolfgang , Geider Klaus
Published: January 2020

All strains of
Erwinia amylovora
characterized carry a medium-size plasmid of 29 kilobases (pEA29). We mapped this plasmid with various restriction enzymes, cloned the whole DNA into an
Escherichia coli
plasmid, and subcloned restriction fragments. These DNA species were used for identification of
E. amylovora
after handling of strains in the laboratory and also in field isolates. About 70 strains of
E. amylovora
and 24 strains from nine other species, mainly found in plant habitats, were checked in a colony hybridization test. Virulent and avirulent
E. amylovora
strains reacted positively, whereas the other species were negative. Apart from the hybridization assay, the positive strains were additionally tested for ooze production on rich agar with 5% sucrose and on immature-pear slices. Unspecific background hybridization of non-
E. amylovora
strains found for hybridization with the whole
E. amylovora
plasmid was almost eliminated when a 5-kilobase
Sal
I fragment from pEA29 was used as a probe and when the washes after the hybridization procedure were done with high stringency. Under these conditions,
E. amylovora
could be readily identified from field isolates.
Role of chemical concentration and second carbon sources in acclimation of microbial communities for biodegradation
Authors: Wiggins B A , Alexander M
Published: January 2020

A study was conducted to determine the role of concentration of the test chemical, of a second organic compound, and of mutation in the acclimation period before the mineralization of organic compounds in sewage. The acclimation period for the mineralization in sewage of 2 micrograms of 4-nitrophenol (PNP) per liter increased from 6 to 12 days in the presence of 10 mg of 2,4-dinitrophenol per liter. The extension of the acclimation period was equivalent to the time required for mineralization of 2,4-dinitrophenol. In contrast, the time for acclimation for the degradation of 2 micrograms of PNP per liter was reduced when 10 or 100 mg of phenol per liter was added. Lower phenol levels increased the acclimation period to 8 days. The length of the acclimation period for PNP mineralization decreased as the initial concentration of PNP increased from 2 micrograms to 100 mg/liter. The acclimation period for phenol mineralization was lengthened as the phenol concentration increased from 100 to 1,400 mg/liter. The length of the acclimation period for PNP and phenol biodegradation was reproducible, but it varied among replicates for the biodegradation of other nitro-substituted compounds added to sewage or lake water, suggesting that a mutation was responsible for acclimation to these other compounds. The acclimation period may thus reflect the time required for the destruction of toxins, and it also may be affected by the concentration of the test compound or the presence of other substrates.
Genetic diversity and relationships among isolates of Rhizobium leguminosarum biovar phaseoli
Authors: Pinero D , Martinez E , Selander R K
Published: January 2020

Fifty-one isolates of Rhizobium leguminosarum biovar phaseoli from various geographic and ecological sources, largely in Mexico, were characterized by the electrophoretic mobilities of 15 metabolic enzymes, and 46 distinctive multilocus genotypes (electrophoretic types [ETs]) were distinguished on the basis of allele profiles at the enzyme loci. Mean genetic diversity per enzyme locus among the 46 ETs was 0.691, the highest value yet recorded for any species of bacterium. The occurrence of strong nonrandom associations of alleles over loci suggested a basically clonal population structure, reflecting infrequent recombination of chromosomal genes. Multilocus genotypic diversity was unusually high, with the most strongly differentiated pairs of ETs having distinctive alleles at all 15 loci and major clusters of ETs diverging at genetic distances as large as 0.89. This great diversity in the chromosomal genome raises the possibility that R. leguminosarum biovar phaseoli is a polyphyletic assemblage of strains. As other workers have suggested, the inclusion of all strains capable of nodulating beans in a single biovar or species is genetically unrealistic and taxonomically misleading. A biologically meaningful classification of Rhizobium spp. should be based on assessment of variation in the chromosomal genome rather than on phenotypic characters, especially those mediated for the most part or wholly by plasmid-borne genes, such as host relationships.
Nutritional versatility and growth kinetics of an Aeromonas hydrophila strain isolated from drinking water
Authors: van der Kooij D , Hijnen W A
Published: January 2020

The nutritional versatility and growth kinetics of Aeromonas hydrophila were studied to determine the nature and the growth-promoting properties of organic compounds which may serve as substrates for the growth of this organism in drinking water during treatment and distribution. As an initial screening, a total of 69 different organic compounds were tested at a concentration of 2.5 g/liter as growth substrates for 10 A. hydrophila strains. Of these strains, strain M800 attained the highest maximum colony counts in various types of drinking water and river water and was therefore used in further measurements of growth at low substrate concentrations. A mixture of 21 amino acids and a mixture of 10 long-chain fatty acids, when added to drinking water, promoted growth of strain M800 at individual compound concentrations as low as 0.1 microgram of C per liter. Mixtures of 18 carbohydrates and 18 carboxylic acids clearly enhanced growth of the organism at individual compound concentrations above 1 microgram of C per liter. Growth measurements with 63 individual substrates at a concentration of 10 micrograms of C per liter gave growth rates of greater than or equal to 0.1/h with two amino acids, nine carbohydrates, and six long-chain fatty acids. Ks values were determined for arginine (less than or equal to 0.3 micrograms of C per liter), glucose (15.9 micrograms of C per liter), acetate (11.1 micrograms of C per liter), and oleate (2.1 micrograms of C per liter). The data obtained indicate that biomass components, such as amino acids and long-chain fatty acids, can promote multiplication of aeromonads in drinking water distribution systems at concentrations as low as a few micrograms per liter.
Microbial transformation of the pyrethroid insecticides: permethrin, deltamethrin, fastac, fenvalerate, and fluvalinate
Authors: Maloney S E , Maule A , Smith A R
Published: January 2020

Pure cultures of Bacillus cereus, Pseudomonas fluorescens, and Achromobacter sp. were shown to transform five pyrethroid insecticides in the presence of Tween 80. One of the major products, 3-phenoxybenzoic acid, was further transformed to 4-hydroxy-3-phenoxybenzoic acid. Permethrin was the most rapidly transformed of the pyrethroids, with a half-life of less than 5 days.
Purification and Characterization of Thermostable Pullulanase from
Bacillus stearothermophilus
and Molecular Cloning and Expression of the Gene in
Bacillus subtilis
Authors: Kuriki Takashi , Park Jong-Hyun , Okada Shigetaka , Imanaka Tadayuki
Published: January 2020

A thermostable pullulanase (α-dextrin 6-glucanohydrolase [EC 3.2.1.41]) from a newly isolated
Bacillus stearothermophilus
strain (TRS128) was purified and characterized. The enzyme hydrolyzed (1→6)-α-
d
-glucosidic linkages of pullulan to produce maltotriose, and the optimum temperature was 65°C. About 90% of the enzyme activity was retained after treatment at 65°C for 60 min. By using pTB522 as a vector plasmid, the pullulanase gene was cloned and expressed in
Bacillus subtilis.
Biodegradation of pentachlorophenol by the white rot fungus Phanerochaete chrysosporium
Authors: Mileski G J , Bumpus J A , Jurek M A , Aust S D
Published: January 2020

Extensive biodegradation of pentachlorophenol (PCP) by the white rot fungus Phanerochaete chrysosporium was demonstrated by the disappearance and mineralization of [14C]PCP in nutrient nitrogen-limited culture. Mass balance analyses demonstrated the formation of water-soluble metabolites of [14C]PCP during degradation. Involvement of the lignin-degrading system of this fungus was suggested by the fact the time of onset, time course, and eventual decline in the rate of PCP mineralization were similar to those observed for [14C]lignin degradation. Also, a purified ligninase was shown to be able to catalyze the initial oxidation of PCP. Although biodegradation of PCP was decreased in nutrient nitrogen-sufficient (i.e., nonligninolytic) cultures of P. chrysosporium, substantial biodegradation of PCP did occur, suggesting that in addition to the lignin-degrading system, another degradation system may also be responsible for some of the PCP degradation observed. Toxicity studies showed that PCP concentrations above 4 mg/liter (15 microM) prevented growth when fungal cultures were initiated by inoculation with spores. The lethal effects of PCP could, however, be circumvented by allowing the fungus to establish a mycelial mat before adding PCP. With this procedure, the fungus was able to grow and mineralize [14C]PCP at concentrations as high as 500 mg/liter (1.9 mM).
Role of Cations in Accumulation and Release of Phosphate by
Acinetobacter
Strain 210A
Authors: van Groenestijn Johan W. , Vlekke Gerard J. F. M. , Anink Désirée M. E. , Deinema Maria H. , Zehnder Alexander J. B.
Published: January 2020

Cells of the strictly aerobic
Acinetobacter
strain 210A, containing aerobically large amounts of polyphosphate (100 mg of phosphorus per g [dry weight] of biomass), released in the absence of oxygen 1.49 mmol of P
i
, 0.77 meq of Mg
2+
, 0.48 meq of K
+
, 0.02 meq of Ca
2+
, and 0.14 meq of NH
4
+
per g (dry weight) of biomass. The drop in pH during this anaerobic phase was caused by the release of 1.8 protons per PO
4
3−
molecule. Cells of
Acinetobacter
strain 132, which do not accumulate polyphosphate aerobically, released only 0.33 mmol of P
i
and 0.13 meq of Mg
2+
per g (dry weight) of biomass but released K
+
in amounts comparable to those released by strain 210A. Stationary-phase cultures of
Acinetobacter
strain 210A, in which polyphosphate could not be detected by Neisser staining, aerobically took up phosphate simultaneously with Mg
2+
, the most important counterion in polyphosphate. In the absence of dissolved phosphate in the medium, no Mg
2+
was taken up. Cells containing polyphosphate granules were able to grow in a Mg-free medium, whereas cells without these granules were not. Mg
2+
was not essential as a counterion because it could be replaced by Ca
2+
. The presence of small amounts of K
+
was essential for polyphosphate formation in cells of strain 210A. During continuous cultivation under K
+
limitation, cells of
Acinetobacter
strain 210A contained only 14 mg of phosphorus per g (dry weight) of biomass, whereas this element was accumulated in amounts of 59 mg/g under substrate limitation and 41 mg/g under Mg
2+
limitation. For phosphate uptake in activated sludge, the presence of K
+
seemed to be crucial.
Plasmid Incidence in Bacteria from Deep Subsurface Sediments
Authors: Fredrickson J. K. , Hicks R. J. , Li S. W. , Brockman F. J.
Published: January 2020

Bacteria were isolated from deep terrestrial subsurface sediments underlying the coastal plain of South Carolina. A total of 163 isolates from deep sediments, surface soil, and return drill muds were examined for plasmid DNA content and resistance to the antibiotics penicillin, ampicillin, carbenicillin, streptomycin, kanamycin, and tetracycline. MICs of Cu
2+
, Cr
3+
, and Hg
2+
for each isolate were also determined. The overall frequency of plasmid occurrence in the subsurface bacteria was 33%. Resistance was most frequent to penicillin (70% of all isolates), ampicillin (49%), and carbenicillin (32%) and was concluded to be related to the concentrations of the individual antibiotics in the disks used for assaying resistance and to the production of low levels of β-lactamase. The frequencies of resistance to penicillin and ampicillin were significantly greater for isolates bearing plasmids than for plasmidless isolates; however, resistance was not transferable to penicillin-sensitive
Escherichia coli
. Hybridization of subsurface bacterial plasmids and chromosomal DNA with a whole-TOL-plasmid (pWWO) probe revealed some homology of subsurface bacterial plasmid and chromosomal DNAs, indicating a potential for those bacteria to harbor catabolic genes on plasmids or chromosomes. The incidences of antibiotic resistance and MICs of metals for subsurface bacteria were significantly different from those for drill mud bacteria, ruling out the possibility that bacteria from sediments were derived from drill muds.
Carbon dioxide fixation and mixotrophic metabolism by strain DCB-1, a dehalogenating anaerobic bacterium
Authors: Stevens T O , Tiedje J M
Published: January 2020

Fixation by strain DCB-1 of CO2 carbon into cell material and organic acids occurred during growth on pyruvate both with and without thiosulfate. By using sodium [14C]bicarbonate and sodium [2-14C]pyruvate, the isotopic composition of products and cells was investigated. Up to 70% of cell carbon was derived from CO2. CO2 carbon was also incorporated into succinate, formate, and acetate. Both carbons of acetate underwent exchange reactions with CO2, although the carboxyl-group exchange was twice as fast. Because strain DCB-1 uses CO2 as its major but not sole carbon source while deriving energy from pyruvate metabolism, we describe its metabolism as mixotrophic. Other mixotrophic conditions also supported growth. Lactate or butyrate, which could not support growth in mineral medium, could replace pyruvate as the oxidizable substrate only when acetate was added to the medium.
Production and characterization of a monoclonal antibody cross-reactive with most group A trichothecenes
Authors: Fan T S , Schubring S L , Wei R D , Chu F S
Published: January 2020

A monoclonal antibody cross-reactive with most group A trichothecenes was produced by fusion of P3/NS-1/1-AG4-1 myeloma cells with spleen cells isolated from a BALB/c mouse that had been immunized with 3-acetyl-neosolaniol-hemisuccinate conjugated to bovine serum albumin. One stable clone, H159B1D5, which produced monoclonal antibody that bound with both T-2 toxin and diacetoxyscirpenol (DAS) was obtained after subcloning. Enzyme-linked immunosorbent assay (ELISA) revealed that the antibody belongs to the immunoglobulin G1 (kappa chain) isotype and had binding constants of 2.81 x 10(9), 1.05 x 10(9), and 1.57 x 10(8) liters per mole for T-2 tetraol tetraacetate, T-2 toxin, and DAS, respectively. The relative cross-reactivities of the antibody with T-2 tetraol tetraacetate, T-2 toxin, and DAS were 200, 100, and 20, respectively, with tritiated T-2 toxin as the marker ligand. The relative cross-reactivities for the above toxins were 667, 100, and 73, respectively, with tritiated DAS as the marker ligand. No cross-reaction with HT-2 and deoxynivalenol triacetate was observed in either system. By using this monoclonal antibody, an indirect ELISA for analysis of T-2 toxin was also developed. The linear portion of the standard curve for analysis of T-2 toxin in each analysis by radioimmunoassay and ELISA was in the range of 0.1 to 2 ng and 0.05 to 1.0 ng, respectively.
Floc Formation by
Azospirillum lipoferum
Grown on Poly-β-Hydroxybutyrate
Authors: Bleakley Bruce H. , Gaskins Murray H. , Hubbell David H. , Zam Stephan G.
Published: January 2020

Azospirillum lipoferum
RG6xx was grown under conditions similar to those resulting in encystment of
Azotobacter
spp.
A. lipoferum
produced cells of uniform shape when grown on nitrogen-free β-hydroxybutyrate agar. Cells accumulated poly-β-hydroxybutyrate and often grew as chains or filaments that eventually lost motility and formed capsules. Within 1 week, vegetative
A. lipoferum
inocula were converted into microflocs arising from filaments or chains. Cells within microflocs were pleomorphic, contained much poly-β-hydroxybutyrate, and were encapsulated. Some cells had a cystlike morphology. Up to 57% of the dry weight of encapsulated flocs was poly-β-hydroxybutyrate, whereas vegetative cells grown in broth with combined nitrogen had only 3% of their dry weight as poly-β-hydroxybutyrate. Neither encapsulated cells in flocs nor nonencapsulated vegetative cells were significantly desiccation resistant. Under starvation conditions (9 days) only 25% of encapsulated cells remained viable, whereas vegetative cells multiplied severalfold. In short-term germination experiments with encapsulated flocs, nitrate, ammonium, and soil extract promoted formation of motile vegetative cells. Most cells in treatments lacking combined nitrogen eventually depleted their visible poly-β-hydroxybutyrate reserves without germinating. The remaining cells retained the reserve polymer and underwent size reduction.
Effect of phenolic monomers on the growth and beta-glucosidase activity of Bacteroides ruminicola and on the carboxymethylcellulase, beta-glucosidase, and xylanase activities of Bacteroides succinogenes
Authors: Martin S A , Akin D E
Published: January 2020

trans-p-Coumaric acid inhibited the growth of Bacteroides ruminicola on both cellobiose and glucose, while trans-ferulic acid and vanillin retarded growth. The phenolic monomers varied in their potential to inhibit the Bacteroides succinogenes beta-glucosidase, carboxymethylcellulase, and xylanase, with p-coumaric acid being the most inhibitory. The B. ruminicola beta-glucosidase was inhibited less than 10% by all three compounds.
Characterization of an extracellular lignin peroxidase of the lignocellulolytic actinomycete Streptomyces viridosporus
Authors: Ramachandra M , Crawford D L , Hertel G
Published: January 2020

Previously we reported production of an extracellular lignin-inducible peroxidase by Streptomyces viridosporus (M. Ramachandra, D.L. Crawford, and A.L. Pometto III, Appl. Environ. Microbiol. 53:2754-2760, 1987). This peroxidase was shown to oxidize 3,4-dihydroxyphenylalanine, 2,4-dichlorophenol, homoprotocatechuic acid, caffeic acid, and N,N,N',N'-tetramethylphenylenediamine and was found in higher than normal levels in strains enhanced for lignocellulose degradation. In the present study, we used a pure extracellular enzyme preparation with high peroxidase isoform P3 activity to oxidize lignin substructure model compounds of both the 1,2-diaryl propane and arylglycerol-beta-aryl ether types and containing C alpha-carbonyl and C alpha-hydroxyl groups. The reactions were monitored by gas chromatography-mass spectrometry and high-pressure liquid chromatography techniques. In the presence, but not the absence, of hydrogen peroxide, the enzyme preparation catalyzed C alpha-C beta bond cleavage in the side chains of the diaryl ethers 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)propane-1,3-diol (I) and 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)propan-1-one (II) and the diaryl ethane 1-(4-methoxyphenyl)-2-(phenyl)ethan-1-one (III). Rapid hydrogen peroxide consumption was observed when the enzyme preparation was added to either milled corn lignin or lignocellulose. Additional characterizations showed that this enzyme is a heme protein (Soret band, 408 nm) and a major component of the ligninolytic system of S. viridosporus T7A. This is the first report of a lignin peroxidase in a bacterium. We have designated this new lignin peroxidase as ALiP-P3.
Degradation of Kraft Indulin Lignin by
Streptomyces viridosporus
and
Streptomyces badius
Authors: Giroux Hélène , Vidal Pierre , Bouchard Jean , Lamy François
Published: January 2020

Crawford and collaborators have studied extensively the solubilization of lignocellulose by two
Streptomyces
species,
S. badius
and
S. viridosporus.
Using a condensed industrial lignin essentially devoid of carbohydrates, Indulin AT, as the sole source of carbon, similar results were obtained: (i) the growths of the bacteria were optimum at pH 7.5 to 8.5; (ii) yeast extract was a better source of nitrogen than NH
4
Cl; (iii) the products of the depolymerization of Indulin were soluble, acid-precipitable polymers. When
d
-glucose was added as a secondary carbon source, it was used preferentially and the production of acid-precipitable polymers began only after the complete depletion of the sugar. On the assumption that the degradation of Indulin was catalyzed by enzymes, proteins found in the culture media and soluble and insoluble intracellular proteins were incubated with Indulin at pH 7.0 at 37°C. Proteins in all fractions from
S. badius
had ligninolytic activities which, with the exception of those in the intracellular soluble fraction, were increased in the presence of H
2
O
2
. In
S. viridosporus
, both extra- and intracellular soluble activities were found which were not increased by H
2
O
2
. The extracellular activity of
S. viridosporus
was not affected by heat, resisted partially an exposure to pH 1.0, and was completely destroyed by proteolysis.
Laccase-mediated detoxification of phenolic compounds
Authors: Bollag J M , Shuttleworth K L , Anderson D H
Published: January 2020

The ability of a polyphenoloxidase, the laccase of the fungus Rhizoctonia praticola, to detoxify phenolic pollutants was examined. The growth of the fungus could be inhibited by phenolic compounds, and the effective concentration was dependent on the substituents of the phenol. A toxic amount of a phenolic compound was added to a fungal growth medium in the presence or absence of a naturally occurring phenol, and half of the replicates also received laccase. The medium was then inoculated with R. praticola, and the levels of phenols in the medium were monitored by high-performance liquid chromatography analysis. The addition of the laccase reversed the inhibitory effect of 2,6-xylenol, 4-chloro-2-methylphenol, and p-cresol. Other compounds, e.g., o-cresol and 2,4-dichlorophenol, were detoxified only when laccase was used in conjunction with a natural phenol such as syringic acid. The toxicity of p-chlorophenol and 2,4,5-trichlorophenol could not be overcome by any additions. The ability of the laccase to alter the toxicity of the phenols appeared to be related to the capacity of the enzyme to decrease the levels of the parent compound by transformation or cross-coupling with another phenol.
Characterization of Jarosite Formed upon Bacterial Oxidation of Ferrous Sulfate in a Packed-Bed Reactor
Authors: Grishin Sergei I. , Bigham Jerry M. , Tuovinen Olli H.
Published: January 2020

A packed-bed bioreactor with activated-carbon particles as a carrier matrix material inoculated with
Thiobacillus ferrooxidans
was operated at a pH of 1.35 to 1.5 to convert ferrous sulfate to ferric sulfate. Despite the low operating pH, trace amounts of precipitates were produced in both the reactor and the oxidized effluent. X-ray diffraction and chemical analyses indicated that the precipitates were well-ordered potassium jarosite. The chemical analyses also revealed a relative deficiency of Fe and an excess of S in the reactor sample compared with the theoretical composition of potassium jarosite.
Protozoan Grazing, Bacterial Activity, and Mineralization in Two-Stage Continuous Cultures
Authors: Bloem Jaap , Starink Mathieu , Bär-Gilissen Marie-José B. , Cappenberg Thomas E.
Published: January 2020

In two-stage continuous cultures, at bacterial concentrations, biovolumes, and growth rates similar to values found in Lake Vechten, ingestion rates of heterotrophic nanoflagellates (HNAN) increased from 2.3 bacteria HNAN
−1
· h
−1
at a growth rate of 0.15 day
−1
to 9.2 bacteria · HNAN
−1
· h
−1
at a growth rate of 0.65 day
−1
. On a yeast extract medium with a C/N/P ratio of 100:15:1.2 (Redfield ratio), a mixed bacterial population showed a yield of 18% (C/C) and a specific carbon content of 211 fg of C · μm
−3
. The HNAN carbon content and yield were estimated at 127 fg of C · μm
−3
and 47% (C/C). Although P was not growth limiting, HNAN accelerated the mineralization of PO
4
-P from dissolved organic matter by 600%. The major mechanism of P remineralization appeared to be direct consumption of bacteria by HNAN. N mineralization was performed mainly (70%) by bacteria but was increased 30% by HNAN. HNAN did not enhance the decomposition of the relatively mineral-rich dissolved organic matter. An accelerated decomposition of organic carbon by protozoa may be restricted to mineral-poor substrates and may be explained mainly by protozoan nutrient regeneration. Growth and grazing in the cultures were compared with methods for in situ estimates. Thymidine incorporation by actively growing bacteria yielded an empirical conversion factor of 1.1 × 10
18
bacteria per mol of thymidine incorporated into DNA. However, nongrowing bacteria also showed considerable incorporation. Protozoan grazing was found to be accurately measured by uptake of fluorescently labeled bacteria, whereas artificial fluorescent microspheres were not ingested, and selective prokaryotic inhibitors blocked not only bacterial growth but also protozoan grazing.
Prevalence of nontuberculous mycobacteria in water supplies of hemodialysis centers
Authors: Carson L A , Bland L A , Cusick L B , Favero M S , Bolan G A , Reingold A L , Good R C
Published: January 2020

Infection of hemodialysis patients with nontuberculous mycobacteria (NTM) has been associated with water used in reprocessing hemodialyzers. This study was conducted to determine the prevalence of NTM and other bacteria in water samples collected over a 13-week period from 115 randomly selected dialysis centers in the United States. Total viable counts were determined by membrane filter assays; increased recovery of NTM was obtained by dosing a portion of each water sample with 1% formaldehyde (HCHO) before filtering. NTM were widely distributed and occurred with a high frequency in water supplies in dialysis centers. NTM were detected in water from 95 centers (83%), and 50% of all samples examined contained NTM. The results of this study support recommendations to use 4% HCHO or a chemical germicidal equivalent for disinfecting dialyzers that are to be reused.
Induction of petite yeast mutants by membrane-active agents
Authors: Jiménez J , Longo E , Benítez T
Published: January 2020

Ethanol proved to be a strong mutagenic agent of Saccharomyces mitochondrial DNA. Other active membrane solvents, such as tert-butanol, isopropanol, and sodium dodecyl sulfate, also turned out to be powerful petite mutation [rho-] inducers. Mutants defective in ergosterol synthesis (erg mutants) showed an extremely high frequency of spontaneous petite cells, suggesting that mitochondrial membrane alterations that were caused either by changes in its composition, as in the erg mutants, or by the effects of organic solvents resulted in an increase in the proportion of petite mutants. Wine yeast strains were generally more tolerant to the mutagenic effects of alcohols on mitochondrial DNA and more sensitive to the effect of sodium dodecyl sulfate than laboratory strains. However, resistance to petite mutation formation in laboratory strains was increased by mitochondrial transfer from alcohol-tolerant wine yeasts. Hence, the stability of the [rho+] mitochondrial DNA in either the presence or absence of solvents depends in part on the nature of the mitochondrial DNA itself. The low frequency of petite mutants found in wine yeast-laboratory yeast hybrids and the fact that the high frequency of petite mutants of a particular wine spore segregated meiotically indicated that many nuclear genes also play an important role in the mitochondrial genome in both the presence and absence of membrane solvents.
Nucleotide sequences of Saccharomycopsis fibuligera genes for extracellular beta-glucosidases as expressed in Saccharomyces cerevisiae
Authors: Machida M , Ohtsuki I , Fukui S , Yamashita I
Published: January 2020

We isolated two genes for extracellular beta-glucosidase, BGL1 and BGL2, from the genomic library of the yeast Saccharomycopsis fibuligera. Gene products (BGLI and BGLII) were purified from the culture fluids of Saccharomyces cerevisiae transformed with BGL1 and BGL2, respectively. Molecular weights of BGLI and BGLII were estimated to be 220,000 and 200,000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The two beta-glucosidases showed the same enzymatic characteristics, such as thermo-denaturation kinetics and dependencies on pH and temperature, but quite different substrate specificities: BGLI hydrolyzed cellobiose efficiently, but BGLII did not. This result is consistent with the observation that the S. cerevisiae transformant carrying BGL1 fermented cellobiose to ethanol but the transformant carrying BGL2 did not. Southern blot analysis revealed that the two beta-glucosidase genes were derived from Saccharomycopsis fibuligera and that the nucleotide sequences of the two genes are closely related. The complete nucleotide sequences of the two genes were determined. BGL1 and BGL2 encode 876- and 880-amino-acid proteins which were shown to be highly similar to each other. The putative precursors begin with hydrophobic segments that presumably act as signal sequences for secretion. Amino acid analysis of the purified proteins confirmed that BGL1 and BGL2 encode BGLI and BGLII, respectively.