bluuebunny/crossref_metadata_2025 huggingface dataset:
Phenotypic study of bacteria associated with the caribbean sclerosponge, Ceratoporella nicholsoni
Authors: Santavy D L , Willenz P , Colwell R R
Published: January 2020

Heterotrophic bacteria associated with the Caribbean sclerosponge, Ceratoporella nicholsoni (Hickson), were found to occur extracellularly and were confined to the mesohyl regions of the sponge tissue. Physiological, metabolic, and morphological attributes of the culturable bacteria associated with the sponge were recorded by using numerical taxonomy methods for the analysis of 158 phenotypic attributes. Morphometric methods were used to determine the proportion of the total sponge-associated bacteria that were culturable by the methods employed, with the results ranging from 3 to 11% of the total bacteria inhabiting the sponge. Approximately 78% of the culturable bacteria clustered into four groups or phena, representing two previously undescribed Vibrio spp., an Aeromonas sp., and a coryneform- or actinomycete-like sp. Most of the bacteria were facultative anaerobes, fermenting sucrose and fucose but unusual in an inability to ferment glucose. This study was the first comprehensive study of heterotrophic bacteria associated with a sponge from the Caribbean basin, a region reputed to contain the most prolific sponge populations, with respect to biomass and diversity. The possible significance of these associations is discussed.
DNA Hybridization Probe for Use in Determining Restricted Nodulation among
Bradyrhizobium japonicum
Serocluster 123 Field Isolates
Authors: Sadowsky Michael J. , Cregan Perry B. , Keyser Harold H.
Published: January 2020

Several soybean plant introduction (PI) genotypes have recently been described which restrict nodulation of
Bradyrhizobium japonicum
serocluster 123 in an apparently serogroup-specific manner. While PI 371607 restricts nodulation of strains in serogroup 123 and some in serogroup 127, those in serogroup 129 are not restricted. When DNA regions within and around the
B. japonicum
I-110 common nodulation genes were used as probes to genomic DNA from the serogroup strains USDA 123, USDA 127, and USDA 129, several of the probes differentially hybridized to the nodulation-restricted and -unrestricted strains. One of the gene regions, cloned in plasmid pMJS12, was subsequently shown to hybridize to 4.6-kilobase
Eco
RI fragments from DNAs from nodulation-restricted strains and to larger fragments in nodulation-unrestricted strains. To determine if the different hybridization patterns could be used to predict nodulation restriction, we hybridized pMJS12 to
Eco
RI-digested genomic DNAs from uncharacterized serocluster 123 field isolates. Of the 36 strains examined, 15 were found to have single, major, 4.6-kilobase hybridizing
Eco
RI fragments. When tested for nodulation, 80% (12 of 15) of the strains were correctly predicted to be restricted for nodulation of the PI genotypes. In addition, hybridization patterns obtained with pMJS12 and nodulation phenotypes on PI 371607 indicated that there are at least three types of serogroup 127 strains. Our results suggest that the pMJS12 gene probe may be useful in selecting compatible host-strain combinations and in determining the suitability of field sites for the placement of soybean genotypes containing restrictive nodulation alleles.
Mineralization of
14
C-Ring-Labeled Synthetic Lignin Correlates with the Production of Lignin Peroxidase, not of Manganese Peroxidase or Laccase
Authors: Perez Juana , Jeffries Thomas W.
Published: January 2020

Recently, Mn(II) has been shown to induce manganese peroxidases (MnPs) and repress lignin peroxidases (LiPs) in defined liquid cultures of several white rot organisms. The present work shows that laccase is also regulated by Mn(II). We therefore used Mn(II) to regulate production of LiP, MnP, and laccase activities while determining the effects of Mn(II) on mineralization of ring-labeled synthetic lignin. At a low Mn(II) level,
Phanerochaete chrysosporium
and
Phlebia brevispora
produced relatively high titers of LiPs but only low titers of MnPs. At a high Mn(II) level, MnP titers increased 12- to 20-fold, but LiPs were not detected in crude broths.
P. brevispora
formed much less LiP than
P. chrysosporium
, but it also produced laccase activity that increased more than sevenfold at the high Mn(II) level. The rates of synthetic lignin mineralization by these organisms were similar and were almost seven times higher at low than at high Mn(II). Increased synthetic lignin mineralization therefore correlated with increased LiP, not with increased MnP or laccase activities.
Effect of methodology, dilution, and exposure time on the tuberculocidal activity of glutaraldehyde-based disinfectants
Authors: Cole E C , Rutala W A , Nessen L , Wannamaker N S , Weber D J
Published: January 2020

The Association of Official Analytical Chemists (AOAC) test for assessing the tuberculocidal activity of disinfectants has been shown to be variable. A modified AOAC test, which substituted Middlebrook 7H9 broth as the primary subculture medium and used neutralization by dilution, was compared with the standard AOAC method to assess the mycobactericidal activity of three glutaraldehyde-based disinfectants at 20 degrees C and various exposure times. These changes had a marked effect on results, with the modified AOAC test providing more positive penicylinders per 10 replicates in 12 of the 13 comparisons that provided positive results. These differences were observed with both Mycobacterium bovis (ATCC 35743) and a clinical isolate of Mycobacterium tuberculosis. The effects of various exposure times to and dilutions of the glutaraldehyde-based disinfectants were also examined. The minimum exposure time needed to inactivate reliably M. bovis or M. tuberculosis with 2% glutaraldehyde was 20 min at 20 degrees C. Diluting 2% glutaraldehyde caused a significant decline in mycobactericidal activity. Modification of the standard AOAC test to improve its sensitivity in detecting the failure of disinfectants to inactivate mycobacteria is indicated.
The bacteriophage kh receptor of Lactococcus lactis subsp. cremoris KH is the rhamnose of the extracellular wall polysaccharide
Authors: Valyasevi R , Sandine W E , Geller B L
Published: January 2020

A receptor for bacteriophages of lactic acid bacteria, including Lactococcus lactis subsp. cremoris KH, was found on the cell wall and not on the cell membrane, as determined by a phage-binding assay of sodium dodecyl sulfate- and mutanolysin-treated cell walls. The cell wall carbohydrates of L. lactis subsp. cremoris KH were analyzed by gas chromatography and mass spectrometry and found to contain rhamnose, galactose, glucose and N-acetylglucosamine. Similar analysis of mutants that were reduced in the ability to bind phages kh, 643, c2, ml3, and 1 indicated that galactose was essential for binding all phages. In addition, rhamnose was required for binding phages kh and ml3. Inhibition studies of phage binding by using two different lectins with a specificity for galactose indicated that phage kh may not bind directly to galactose. Rather, galactose may be an essential structural component located in the vicinity of the receptor. Incubation of any of the five phages with rhamnose or of phage kh with purified cell walls inactivated the phages. Inactivation required divalent cations and was irreversible. Inactivation of phages was stereospecific for rhamnose, as neither L-(+)- nor D-(-)-fucose (the stereoisomers of rhamnose) inhibited the phage. Furthermore, phage infection of a culture was completely inhibited by the addition of rhamnose to the medium. Therefore, the receptor for phage kh appears to be a rhamnose component of the extracellular wall polysaccharide.
Expression and regulation of a Bacteroides fragilis sucrose utilization system cloned in Escherichia coli
Authors: Scholle R R , Steffen H E , Goodman H J , Woods D R
Published: January 2020

A Bacteroides fragilis strain isolated from human feces was the source of chromosomal DNA in the construction of plasmid pBS100. The cloned 6-kilobase insert of plasmid pBS100 conferred a sucrose positivity phenotype on transformed cells of Escherichia coli JA221. E. coli JA221(pBS100) cells were able to utilize sucrose as the sole source of carbon because of the presence of sucrase enzyme and sucrose uptake activities. Sucrase activity was inducible in B. fragilis but constitutive in E. coli JA221(pBS100) cells. In sucrose-minimal medium, both B. fragilis and E. coli JA221(pBS100) produced intracellular and extracellular sucrase activities throughout the growth cycle. Osmotic shock experiments performed on E. coli JA221(pBS100) indicated that up to 55% of the sucrase activity was localized in the periplasmic space, 30% was in the cytoplasm, and the remaining 15% was in the cell-free extracellular supernatant fluid. B. fragilis and E. coli JA221(pBS100) actively transported sucrose. Sucrose uptake was induced by sucrose in B. fragilis, whereas the uptake activity in E. coli JA221(pBS100) was constitutive. E. coli JA221(pBS100) appeared to transport sucrose by a phosphotransferase-independent system. B. fragilis transported sucrose only under strictly anaerobic conditions. No uptake activity was detected under aerobic conditions with or without addition of catalase.
Genome analysis of Bradyrhizobium japonicum serocluster 123 field isolates by using field inversion gel electrophoresis
Authors: Sobral B W , Sadowsky M J , Atherly A G
Published: January 2020

The genomes of 11 Bradyrhizobium japonicum serocluster 123 field isolates were analyzed by using field inversion gel electrophoresis. Genomic fingerprints produced by digestion of intact genomic DNA in agarose plugs with the rare-cutting restriction enzymes AseI, DraI, SpeI, and XbaI showed that the isolates were genetically diverse. Few (30 to 50%) isolates exhibited the same fingerprint as the USDA serogroup strain with which they are antigenically related. Southern hybridization with a nifHD gene probe to the blotted field inversion electrophoresis gels provided further evidence of the relatedness between members of serogroups 123 and 127.
Several Uses for Isobutyric Acid-Ammonium Hydroxide Solvent in Endotoxin Analysis
Authors: Caroff Martine G. L. , Karibian Doris
Published: January 2020

Many steps in the analysis of rough and semirough endotoxins were found to be facilitated by the use of isobutyric acid-ammonium hydroxide solvent.
Amplification of the rbcL gene from dissolved and particulate DNA from aquatic environments
Authors: Paul J H , Cazares L , Thurmond J
Published: January 2020

The carboxylation of ribulose biphosphate by the enzyme ribulosebisphosphate carboxylase/oxygenase is the mechanism for CO2 fixation and primary production in nearly all ecosystems on this planet. Although certain algal isolates and higher plants contain conserved nucleotide sequences in the large subunit of the gene (rbcL) for this enzyme, such genes from natural microbial assemblages have not been heretofore examined. Using oligonucleotide primers designed for conserved regions of the rbcL gene of a Synechococcus sp. (Anacystis nidulans), we have amplified rbcL from DNA preparations from planktonic samples from a Florida reservoir and from algal isolates by the polymerase chain reaction. We have also detected rbcL by gene amplification in the extracellular DNA fraction of this reservoir, indicating that phytoplankton can be a source of dissolved DNA. These results suggest that gene amplification can be applied for the detection of conserved genes encoding enzymes involved in important ecological functions in aquatic environments.
DNA Probe for
Lactobacillus delbrueckii
Authors: Delley Michèle , Mollet Beat , Hottinger Herbert
Published: January 2020

From a genomic DNA library of
Lactobacillus delbrueckii
subsp.
bulgaricus,
a clone was isolated which complements a leucine auxotrophy of an
Escherichia coli
strain (GE891). Subsequent analysis of the clone indicated that it could serve as a specific DNA probe. Dot-blot hybridizations with over 40 different
Lactobacillus
strains showed that this clone specifically recognizes
L. delbrueckii
subsp.
delbrueckii, bulgaricus,
and
lactis.
The sensitivity of the method was tested by using an α-
32
P-labeled DNA probe.
Improved assay for surface hydrophobic avidity of Candida albicans cells
Authors: Hazen K C , LeMelle W G
Published: January 2020

A simple method that distinguishes among hydrophobic avidity levels of highly hydrophobic isolates of the pathogenic fungus Candida albicans is described. This method involves mixing polystyrene microspheres at different concentrations with a constant concentration of yeast cells and plotting the data in accordance with the Langmuir isotherm equation. A 10-fold difference between the C. albicans isolates with the lowest and highest avidity (KH) values was found. This method may also demonstrate that surface hydrophobic sites with different avidities are present within a yeast cell population.
Chlorinated biphenyl mineralization by individual populations and consortia of freshwater bacteria
Authors: Pettigrew C A , Breen A , Corcoran C , Sayler G S
Published: January 2020

Comparative studies were performed to investigate the contribution of microbial consortia, individual microbial populations, and specific plasmids to chlorinated biphenyl biodegradation among microbial communities from a polychlorinated biphenyl-contaminated freshwater environment. A bacterial consortium, designated LPS10, was shown to mineralize 4-chlorobiphenyl (4CB) and dehalogenate 4,4'-dichlorobiphenyl. The LPS10 consortium involved three isolates: Pseudomonas testosteroni (LPS10A), which mediated the breakdown of 4CB and 4,4'-dichlorobiphenyl to 4-chlorobenzoic acid; an isolate tentatively identified as an Arthrobacter sp. (LPS10B), which mediated 4-chlorobenzoic acid degradation; and Pseudomonas putida bv. A (LPS10C), whose role in the consortium has not been determined. None of these isolates contained detectable plasmids or sequences homologous to the 4CB-degradative plasmid pSS50. A freshwater isolate, designated LBS1C1, was found to harbor a 41-megadalton plasmid that was related to the 35-megadalton plasmid pSS50, and this isolate was shown to mineralize 4CB. In chemostat enrichments with biphenyl and 4CB as primary carbon sources, the LPS10 consortium was found to outcomplete bacterial populations harboring plasmids homologous to pSS50. These results demonstrate that an understanding of the biodegradative capacity of individual bacterial populations as well as interacting populations of bacteria must be considered in order to gain a better understanding of polychlorinated biphenyl biodegradation in the environment.
Agrobacterium tumefaciens
Is a Diazotrophic Bacterium
Authors: Kanvinde Lalita , Sastry G. R. K.
Published: January 2020

This is the first report that
Agrobacterium tumefaciens
can fix nitrogen in a free-living condition as shown by its abilities to grow on nitrogen-free medium, reduce acetylene to ethylene, and incorporate
15
N supplied as
15
N
2
. As with most other well-characterized diazotrophic bacteria, the presence of NH
4
+
in the medium and aerobic conditions repress nitrogen fixation by
A. tumefaciens.
The system requires molybdenum. No evidence for nodulation was found with pea, peanut, or soybean plants. Further understanding of the nitrogen-fixing ability of this bacterium, which has always been considered a pathogen, should cast new light on the evolution of a pathogenic versus symbiotic relationship.
Effects of cyclohexane, an industrial solvent, on the yeast Saccharomyces cerevisiae and on isolated yeast mitochondria
Authors: Uribe S , Rangel P , Espínola G , Aguirre G
Published: January 2020

Little information on the effects of cyclohexane at the cellular or subcellular level is available. In Saccharomyces cerevisiae, cyclohexane inhibited respiration and diverse energy-dependent processes. In mitochondria isolated from S. cerevisiae, oxygen uptake and ATP synthesis were inhibited, although ATPase activity was not affected. Cyclohexane effects were similar to those reported for beta-pinene and limonene, suggesting that the cyclohexane ring in these monoterpenes may be a determinant for their biological activities.
Monoclonal antibodies against the ruminal bacterium Selenomonas ruminantium
Authors: Brooker J D , Stokes B
Published: January 2020

Monoclonal antibodies were raised against whole cells of two different strains of Selenomonas ruminantium and tested for specificity and sensitivity in immunofluorescence and enzyme-linked immunosorbent assay procedures. Species-specific and strain-specific antibodies were identified, and reactive antigens were demonstrated in solubilized cell wall extracts of S. ruminantium. A monoclonal antibody-based solid-phase immunoassay was established to quantify S. ruminantium in cultures or samples from the rumen, and this had a sensitivity of 0.01 to 0.02% from 10(7) cells. For at least one strain, the extent of antibody reaction varied depending upon the stage of bacterial growth. Antigen characterization by immunoblotting shows that monoclonal antibodies raised against two different strains of S. ruminantium reacted with the same antigen on each strain. For one strain, an additional antigen reacted with both monoclonal antibodies. In the appropriate assay, these monoclonal antibodies may have advantages over gene probes, both in speed and sensitivity, for bacterial quantification studies.
Application of the theory of adaptive polymorphism to the ecology and epidemiology of pathogenic yeasts
Authors: Hunter P R , Fraser C A
Published: January 2020

The theory of adaptive polymorphism predicts that species occupying broad ecological niches will be phenotypically and genotypically more varied than those occupying narrow niches. It is suggested that this theory has direct relevance to the epidemiology of microbial pathogens in that environmental pathogens inhabit a broader niche and should be expected to exhibit greater variation than pathogens that are obligate commensals. This proved to be the case when one obligate commensal, the pathogenic yeast Candida albicans, was compared with other Candida spp. and an environmental pathogen, Cryptococcus neoformans. Further evidence of this relationship is derived from the literature. This observation adds further support to the theory of adaptive polymorphism, although the mechanisms of maintenance of polymorphism is asexually reproducing populations must be different from those in sexually reproducing populations. This observation may give important clues to the epidemiology of those infections for which it is not already known.
Oxidation of benzaldehydes to benzoic acid derivatives by three Desulfovibrio strains
Authors: Zellner G , Kneifel H , Winter J
Published: January 2020

Desulfovibrio vulgaris Marburg, "Desulfovibrio simplex" XVI, and Desulfovibrio sp. strain MP47 used benzaldehydes such as vanillin, 3,4,5-trimethoxybenzaldehyde, protocatechualdehyde, syringaldehyde, p-anisaldehyde, p-hydroxybenzaldehyde, and 2-methoxybenzaldehyde as electron donors for sulfate reduction and carbon dioxide and/or components of yeast extract as carbon sources for cell synthesis. The aldehydes were oxidized to their corresponding benzoic acids. The three sulfate reducers oxidized up to 7 mM vanillin and up to 4 mM p-anisaldehyde. Higher concentrations of vanillin or p-anisaldehyde were toxic. In addition, pyridoxal hydrochloride and o-vanillin served as electron donors for sulfate reduction. Salicylaldehyde, pyridine-2-aldehyde, pyridine-4-aldehyde, and 4-hydroxy-3-methoxybenzylalcohol were not oxidized. No molecular hydrogen was detected in the gas phase. The oxidized aldehydes were not further degraded.
Enumeration of enterotoxigenic Bacteroides fragilis in municipal sewage
Authors: Shoop D S , Myers L L , LeFever J B
Published: January 2020

Of 237 isolates of Bacteroides fragilis from sewage influent at the Bozeman, Mont., wastewater treatment plant, 22 (9.3%) were enterotoxigenic, as indicated by the ability to elicit fluid accumulation in the lamb ileal loop test. It appears that enterotoxigenic B. fragilis is endemic in the human population at a moderately high level.
Alternate gram staining technique using a fluorescent lectin
Authors: Sizemore R K , Caldwell J J , Kendrick A S
Published: January 2020

Fluorescence-labeled wheat germ agglutinin binds specifically to N-acetylglucosamine in the outer peptidoglycan layer of gram-positive bacteria. The peptidoglycan layer of gram-negative bacteria is covered by a membrane and is not labeled by the lectin. By exploiting this phenomenon, an alternative Gram staining technique has been developed.
Widespread occurrence of specific restriction endonucleases in Salmonella infantis, Salmonella thompson, and Salmonella blockley isolated from humans in Japan
Authors: Miyahara M , Kudoh Y , Mise K
Published: January 2020

Specific restriction endonucleases were detected in three serotypes of Salmonella spp. isolated from humans in Japan from 1970 to 1987: an isoschizomer of AvaII endonuclease at a frequency of 0.91 in Salmonella infantis, an isoschizomer of KpnI at a frequency of 0.34 in Salmonella thompson, and an isoschizomer of StyI at a frequency of 0.30 in Salmonella blockley. Of interest is that restriction endonuclease-producing S. thompson was detected at high frequencies in the 1970s but at low frequencies in the 1980s.
Spore Yield and Microcycle Conidiation of
Colletotrichum gloeosporioides
in Liquid Culture
Authors: Cascino J. J. , Harris R. F. , Smith C. S. , Andrews J. H.
Published: January 2020

The effect of V8 juice concentration (5 to 40%, vol/vol), spore inoculum density (10
5
and 10
7
spores per ml), and liquid batch or fed-batch culture condition on mycelium and spore production by
Colletotrichum gloeosporioides
was evaluated. The amount of mycelium produced, the time required for initiation of sporulation following attainment of maximum mycelium, and the time for attainment of maximum spore concentration increased with increasing V8 juice concentration in batch culture. Cultures containing V8 juice at >10% achieved a similar spore density (apparent spore-carrying capacity) of about 0.8 mg of spores per ml (1 × 10
7
to 2 × 10
7
spores per ml) independent of inoculum density and V8 juice concentration. The relative spore yield decreased from a high of 64% of the total biomass for the low-inoculum 5% V8 culture, through 13% for the analogous 40% V8 culture, to a low of 2% for the high-inoculum 27% V8 culture. Fed-batch cultures were used to establish conditions of high spore density and low substrate availability but high substrate flux. The rate of addition of V8 juice was adjusted to approximate the rate of substrate utilization by the (increasing) biomass. The final spore concentration was about four times higher (3.0 mg of spores per ml) than the apparent spore-carrying capacity in batch culture. This high spore yield was obtained at the expense of greatly reduced mycelium, resulting in a high relative spore yield (62% of the total biomass). Microcycle conidiation occurred in the fed-batch but not batch systems. These data indicate that substrate-limited, fed-batch culture can be used to increase the amount and efficiency of spore production by
C. gloeosporioides
by maintaining microcycle conidiation conditions favoring allocation of nutrients to spore rather than mycelium production.
Mutant Strain of
Bradyrhizobium japonicum
with Increased Symbiotic N
2
Fixation Rates and Altered Mo Metabolism Properties
Authors: Maier Robert J. , Graham Lennox
Published: January 2020

Mutant strains of
Bradyrhizobium japonicum
that required higher levels of molybdate than the wild-type strain for growth on NO
3
-containing medium were obtained after transposon Tn
5
mutagenesis of the wild-type strain. The mutant strains expressed more than fivefold-greater nitrate reductase activities in the range of 0.1 to 1.0 mM added molybdate compared with activities expressed upon incubation in non-Mo-supplemented medium, whereas the nitrate reductase activity of the wild-type strain (JH) was not markedly influenced by Mo supplementation. In free-living culture, mutant strains JH310 and JH359 expressed substantial nitrogenase activity, even in medium treated to remove molybdate, and nitrogenase activity was influenced little by Mo supplementation, whereas the wild-type strain required 100 nM added Mo for highest nitrogenase activity. Double-reciprocal plots of Mo uptake rates versus Mo concentration showed that both bacteroids and free-living cells of mutant strain JH359 had about the same affinity for Mo as did the parent strain. Bacteroids of both the mutants and the wild type also exhibited similar Mo accumulation rates over a 9-min period under very-low-Mo (4 nM) conditions. Nitrogenase activities for strain JH359 and for the wild-type strain in free-living culture were both strongly inhibited by tungsten; thus, the nitrogenase activities of both strains are probably the result of a “conventional” Mo-containing nitrogenase. Soybeans inoculated with strain JH359 and grown under either Mo-supplemented or Mo-deficient conditions had greater specific acetylene reduction rates and significantly greater plant fresh weight than those inoculated with the wild-type strain. Under Mo-deficient conditions, the acetylene reduction rates and plant fresh weights were up to 35 and 58% greater, respectively, for mutant-nodulated plants compared with wild-type-strain-nodulated plants.
Comparative biodegradation of alkyl halide insecticides by the white rot fungus, Phanerochaete chrysosporium (BKM-F-1767)
Authors: Kennedy D W , Aust S D , Bumpus J A
Published: January 2020

The ability of Phanerochaete chrysosporium to degrade six alkyl halide insecticides (aldrin, dieldrin, heptachlor, chlordane, lindane, and mirex) in liquid and soil-corncob matrices was compared by using 14C-labeled compounds. Of these, only [14C]lindane and [14C]chlordane underwent extensive biodegradation, as evidenced by the fact that 9.4 to 23.4% of these compounds were degraded to 14CO2 in 30 days in liquid cultures and 60 days in soil-corncob cultures inoculated with P. chrysosporium. Although [14C]aldrin, [14C]dieldrin, [14C]heptachlor, and [14D]mirex were poorly mineralized, substantial bioconversion occurred, as determined by substrate disappearance and metabolite formation. Nonbiological disappearance was observed only with chlordane and heptachlor.
Dechlorination of Four Commercial Polychlorinated Biphenyl Mixtures (Aroclors) by Anaerobic Microorganisms from Sediments
Authors: Quensen John F. , Boyd Stephen A. , Tiedje James M.
Published: January 2020

The rate, extent, and pattern of dechlorination of four Aroclors by inocula prepared from two polychlorinated biphenyl (PCB)-contaminated sediments were compared. The four mixtures used, Aroclors 1242, 1248, 1254, and 1260, average approximately three, four, five, and six chlorines, respectively, per biphenyl molecule. All four Aroclors were dechlorinated with the loss of
meta
plus
para
chlorines ranging from 15 to 85%. Microorganisms from an Aroclor 1242-contaminated site in the upper Hudson River dechlorinated Aroclor 1242 to a greater extent than did microorganisms from Aroclor 1260-contaminated sediments from Silver Lake, Mass. The Silver Lake inoculum dechlorinated Aroclor 1260 more rapidly than the Hudson River inoculum did and showed a preferential removal of
meta
chlorines. For each inoculum the rate and extent of dechlorination tended to decrease as the degree of chlorination of the Aroclor increased, especially for Aroclor 1260. The maximal observed dechlorination rates were 0.3, 0.3, and 0.2 μg-atoms of Cl removed per g of sediment per week for Aroclors 1242, 1248, and 1254, respectively. The maximal observed dechlorination rates for Hudson River and Silver Lake organisms for Aroclor 1260 were 0.04 and 0.21 μg-atoms of Cl removed per g of sediment per week, respectively. The dechlorination patterns obtained suggested that the Hudson River microorganisms were more capable than the Silver Lake organisms of removing the last
para
chlorine. These results suggest that there are different PCB-dechlorinating microorganisms at different sites, with characteristic specificities for PCB dechlorination.
Stereoselective Reduction of Ethyl 4-Chloro-3-Oxobutanoate by a Microbial Aldehyde Reductase in an Organic Solvent-Water Diphasic System
Authors: Shimizu Sakayu , Kataoka Michihiko , Katoh Masaaki , Morikawa Tadashi , Miyoshi Teruzo , Yamada Hideaki
Published: January 2020

Enzyme-catalyzed asymmetric reduction of ethyl 4-chloro-3-oxobutanoate in an organic solvent-water diphasic system was studied. NADPH-dependent aldehyde reductase isolated from
Sporobolomyces salmonicolor
AKU4429 and glucose dehydrogenase were used as catalysts for reduction of ethyl 4-chloro-3-oxobutanoate and recycling of NADPH, respectively, in this system. In an aqueous system, the substrate was unstable. Inhibition of the reaction and inactivation of the enzymes by the substrate and the product were also observed. An
n
-butyl acetate-water diphasic system very efficiently overcame these limitations. In a 1,600-ml−1,600-ml scale diphasic reaction, ethyl (
R
)-4-chloro-3-hydroxybutanoate (0.80 mol; 86% enantiomeric excess) was produced from the corresponding oxoester in a molar yield of 95.4% with an NADPH turnover of 5,500 mol/mol.
Enhanced Nodulation and Nitrogen Fixation by a Revertant of a Nodulation-Defective
Bradyrhizobium japonicum
Tryptophan Auxotroph
Authors: Hunter William J. , Kuykendall L. David
Published: January 2020

In greenhouse studies, the symbiotic properties of a prototrophic revertant (TA11 NOD
+
) of a nodulation defective tryptophan auxotroph of
Bradyrhizobium japonicum
were compared with those of the normally nodulating wild-type strain,
B. japonicum
I-110 ARS. Strain I-110 ARS was the parent of auxotrophic mutant TA11. Plants inoculated with TA11 NOD
+
contained significantly more nitrogen per plant than did plants inoculated with wild-type bacteria (275.9 ± 35 versus 184 ± 18 mg). Also, plants that received the revertant were larger, averaging 8.4 ± 0.9 g (dry weight) versus 6.4 ± 0.6 g for those that received the wild-type bacterial strain. Additionally, plants that received the NOD
+
strain had 56% more nodules and 41% more nodule mass than did control plants. With both inocula, average nodule size and amount of nitrogen fixed per gram of nodule were about the same. These data indicated that the improvement in nitrogen fixation observed with the TA11 NOD
+
resulted from an increase in the overall nodule number. The physiological basis for this increase in nodulation is not known, but enhanced tryptophan catabolism does not appear to be involved.
Regulation of Sugar Transport Systems in
Fusarium oxysporum
var.
lini
Authors: Brandão Rogélio L. , Loureiro-Dias Maria C.
Published: January 2020

Fusarium oxysporum
var.
lini
(ATCC 10960) formed a facilitated diffusion system for glucose (

K
s

, about 10 mM) when grown under repressed conditions. Under conditions of derepression, the same system was present together with a high-affinity (

K
s

, about 40 μM) active system. The maximum velocity of the latter was about 5% of that of the facilitated diffusion system. The high-affinity system was under the control of glucose repression and glucose inactivation. When lactose was the only carbon source in the medium, a facilitated diffusion system for lactose was found (

K
s

, about 30 mM).
Effect of cellulose fine structure on kinetics of its digestion by mixed ruminal microorganisms in vitro
Authors: Weimer P J , Lopez-Guisa J M , French A D
Published: January 2020

The digestion kinetics of a variety of pure celluloses were examined by using an in vitro assay employing mixed ruminal microflora and a modified detergent extraction procedure to recover residual cellulose. Digestion of all of the celluloses was described by a discontinuous first-order rate equation to yield digestion rate constants and discrete lag times. These kinetic parameters were compared with the relative crystallinity indices and estimated accessible surface areas of the celluloses. For type I celluloses having similar crystallinities and simple nonaggregating particle morphologies, the fermentation rate constants displayed a strong positive correlation (r2 = 0.978) with gross specific surface area; lag time exhibited a weaker, negative correlation (r2 = 0.930) with gross specific surface area. Crystallinity was shown to have a relatively minor effect on the digestion rate and lag time. Swelling of microcrystalline cellulose with 72 to 77% phosphoric acid yielded substrates which were fermented slightly more rapidly than the original material. However, treatment with higher concentrations of phosphoric acid resulted in a more slowly fermented substrate, despite a decrease in crystallinity and an increase in pore volume. This reduced fermentation rate was apparently due to the partial conversion of the cellulose from the type I to the type II allomorph, since mercerized (type II) cellulose was also fermented more slowly, and only after a much longer lag period. The results are consistent with earlier evidence for the cell-associated nature of cellulolytic enzymes of ruminal bacteria and suggest that ruminal microflora do not rapidly adapt to utilization of celluloses with altered unit cell structures.
Description of a Novel Symbiotic Bacterium from the Brittle Star,
Amphipholis squamata
Authors: Lesser Michael P. , Blakemore Richard P.
Published: January 2020

A gram-negative, marine, facultatively anaerobic bacterial isolate designated strain AS-1 was isolated from the subcuticular space of the brittle star,
Amphipholis squamata.
Its sensitivity to O/129 and novobiocin, overall morphology, and biochemical characteristics and the moles percent guanine-plus-cytosine composition of its DNA (42.9 to 44.4) suggest that this isolate should be placed in the genus
Vibrio.
Strain AS-1 was not isolated from ambient seawater and is distinct from described
Vibrio
species. This symbiotic bacterium may assist its host as one of several mechanisms of nutrient acquisition during the brooding of developing embryos.
Gene escape model: transfer of heavy metal resistance genes from Escherichia coli to Alcaligenes eutrophus on agar plates and in soil samples
Authors: Top E , Mergeay M , Springael D , Verstraete W
Published: January 2020

Conjugal transfer from Escherichia coli to Alcaligenes eutrophus of the A. eutrophus genes coding for plasmid-borne resistance to cadmium, cobalt, and zinc (czc genes) was investigated on agar plates and in soil samples. This czc fragment is not expressed in the donor strain, E. coli, but it is expressed in the recipient strain, A. eutrophus. Hence, expression of heavy metal resistance by cells plated on a medium containing heavy metals represents escape of the czc genes. The two plasmids into which this DNA fragment has been cloned previously and which were used in these experiments are the nonconjugative, mobilizable plasmid pDN705 and the nonconjugative, nonmobilizable plasmid pMOL149. In plate matings at 28 to 30 degrees C, the direct mobilization of pDN705 occurred at a frequency of 2.4 x 10(-2) per recipient, and the mobilization of the same plasmid by means of the IncP1 conjugative plasmids RP4 or pULB113 (present either in a third cell [triparental cross] or in the recipient strain itself [retromobilization]) occurred at average frequencies of 8 x 10(-4) and 2 x 10(-5) per recipient, respectively. The czc genes cloned into the Tra- Mob- plasmid pMOL149 were transferred at a frequency of 10(-7) to 10(-8) and only by means of plasmid pULB113. The direct mobilization of pDN705 was further investigated in sandy, sandy-loam, and clay soils. In sterile soils, transfer frequencies at 20 degrees C were highest in the sandy-loam soil (10(-5) per recipient) and were enhanced in all soils by the addition of easily metabolizable nutrients.(ABSTRACT TRUNCATED AT 250 WORDS)
Toxicity of 1,1,1-Trichloroethane and Trichloroethene on a Mixed Culture of Methane-Oxidizing Bacteria
Authors: Broholm Kim , Jensen Bjørn K. , Christensen Thomas H. , Olsen Lajla
Published: January 2020

The influence of trichloroethene (TCE; 0 to 65 mg/liter) and 1,1,1-trichloroethane (1,1,1-TCA; 0 to 103 mg/liter) on methane consumption of a mixed culture of methane-oxidizing bacteria was studied in laboratory batch experiments. Increasing concentrations of TCE or 1,1,1-TCA resulted in decreasing methane consumption. Methane consumption was totally inhibited at a concentration of 13 mg of TCE per liter, while methane consumption was still observed at the upper studied concentration of 103 mg of 1,1,1-TCA per liter. The inhibition of methane consumption by TCE depended on the initial concentration of methane. A model accounting for competitive inhibition between methane and TCE or 1,1,1-TCA was used to simulate methane consumption at various concentrations of TCE or 1,1,1-TCA. The simulations indicated that competitive inhibition may be the mechanism causing the inhibitory effect of TCE on methane consumption, while this does not seem to be the case for 1,1,1-TCA.
Plasmid-associated bacteriocin production by a strain of Carnobacterium piscicola from meat
Authors: Ahn C , Stiles M E
Published: January 2020

Carnobacterium piscicola LV17 isolated from vacuum-packed meat produces bacteriocin(s) that is active against closely related lactic acid bacteria, Enterococcus spp., and a strain of Listeria monocytogenes but not against gram-negative bacteria. The bacteriocin has a bactericidal mode of action, is heat resistant, and is stable over a wide range of pH but is inactivated by proteolytic enzymes. Sensitive and resistant cells were shown to adsorb the bacteriocin, but cell death depended on contact of the bacteriocin with the cell membrane. Bacteriocin production is detected early in the growth cycle of the organism in APT broth, but it is not produced in APT broth adjusted to pH 5.5. Bacteriocin production and resistance to the bacteriocin produced are associated with two plasmids of 40 and 49 megadaltons. The possibility that two bacteriocins are produced is indicated because the inhibitory substances of the mutant strains containing either the 40- or 49-megadalton plasmids have different antimicrobial spectra.
Regulation and localization of amylolytic enzymes in Clostridium acetobutylicum ATCC 824
Authors: Annous B A , Blaschek H P
Published: January 2020

Amylolytic activity was primarily cell associated when Clostridium acetobutylicum was grown on glucose or maltose and primarily extracellular when grown on dextrin or starch. Total amylolytic activity decreased with increasing glucose concentration. When this microorganism was grown in P2 medium containing starch, the intracellular amylolytic activity was 90% membrane bound and 10% cytoplasmic in nature. The addition of 1% glucose to 2% starch-based P2 medium at different stages of growth indicated that this carbohydrate repressed the synthesis of C. acetobutylicum amylolytic enzymes at the level of transcription.
Heterologous gene expression in Lactococcus lactis subsp. lactis: synthesis, secretion, and processing of the Bacillus subtilis neutral protease
Authors: van de Guchte M , Kodde J , van der Vossen J M , Kok J , Venema G
Published: January 2020

The Bacillus subtilis nprE gene lacking its own promoter sequence was inserted in the lactococcal expression vector pMG36e. Upon introduction of the recombinant plasmid into Lactococcus lactis subsp. lactis strain MG1363, neutral protease activity could be visualized by the appearance of large clearing zones around colonies grown on milk agar plates. By measuring the activities of the neutral protease and the intracellular enzyme lactate dehydrogenase in culture supernatants and cell fractions, it was demonstrated that the neutral protease was actively secreted into the growth medium. This was corroborated by using the Western blot (immunoblot) technique, which showed the presence of the mature form of the neutral protease in the culture supernatant. On the basis of these results, it is concluded that the B. subtilis neutral protease gene was expressed in L. lactis and that the gene product was secreted into the growth medium and was apparently correctly processed to produced a biologically active protein. The secretion of this particular enzyme may be helpful in achieving accelerated cheese ripening.
Effects of Organic Substrates on Dechlorination of Aroclor 1242 in Anaerobic Sediments
Authors: Nies Loring , Vogel Timothy M.
Published: January 2020

The effects of different organic substrates on the abilities of anaerobic sediment enrichments to reductively dechlorinate polychlorinated biphenyls (PCBs) were studied. Sediments collected from a site previously contaminated with PCBs were dosed with additional PCBs (Aroclor 1242; approximately 300 ppm [300 μg/g], sediment dry weight) and incubated anaerobically with acetate, acetone, methanol, or glucose. The pattern of dechlorination was similar for each substrate-fed batch; however, the extents and rates of dechlorination were different. Significant dechlorination over time was observed, with the relative rates and extents of dechlorination being greatest for methanol-, glucose-, and acetone-fed batches and least for acetate-fed batches. Dechlorination occurred primarily on the
meta
- and
para
- positions of the highly chlorinated congeners, resulting in the accumulation of less-chlorinated, primarily
ortho
-substituted products. No significant dechlorination was observed in incubation batches receiving no additional organic substrate, even though identical inorganic nutrients were added to all incubation batches. In addition, dechlorination was not observed in autoclaved controls that received substrate and nutrients.
Formation and Action of Lignin-Modifying Enzymes in Cultures of
Phlebia radiata
Supplemented with Veratric Acid
Authors: Lundell Taina , Leonowicz Andrzej , Rogalski Jerzy , Hatakka Annele
Published: January 2020

Transformation of veratric (3,4-dimethoxybenzoic) acid by the white rot fungus
Phlebia radiata
was studied to elucidate the role of ligninolytic, reductive, and demeth(ox)ylating enzymes. Under both air and a 100% O
2
atmosphere, with nitrogen limitation and glucose as a carbon source, reducing activity resulted in the accumulation of veratryl alcohol in the medium. When the fungus was cultivated under air, veratric acid caused a rapid increase in laccase (benzenediol:oxygen oxidoreductase; EC 1.10.3.2) production, which indicated that veratric acid was first demethylated, thus providing phenolic compounds for laccase. After a rapid decline in laccase activity, elevated lignin peroxidase (ligninase) activity and manganese-dependent peroxidase production were detected simultaneously with extracellular release of methanol. This indicated apparent demethoxylation. When the fungus was cultivated under a continuous 100% O
2
flow and in the presence of veratric acid, laccase production was markedly repressed, whereas production of lignin peroxidase and degradation of veratryl compounds were clearly enhanced. In all cultures, the increases in lignin peroxidase titers were directly related to veratryl alcohol accumulation. Evolution of
14
CO
2
from 3-O
14
CH
3
-and 4-O
14
CH
3
-labeled veratric acids showed that the position of the methoxyl substituent in the aromatic ring only slightly affected demeth(ox)ylation activity. In both cases, more than 60% of the total
14
C was converted to
14
CO
2
under air in 4 weeks, and oxygen flux increased the degradation rate of the
14
C-labeled veratric acids just as it did with unlabeled cultures.
Acetoin Fermentation by Citrate-Positive
Lactococcus lactis
subsp.
lactis
3022 Grown Aerobically in the Presence of Hemin or Cu
2+
Authors: Kaneko Tsutomu , Takahashi Masahiro , Suzuki Hideki
Published: January 2020

Citr
+
Lactococcus lactis
subsp.
lactis
3022 produced more biomass and converted most of the glucose substrate to diacetyl and acetoin when grown aerobically with hemin and Cu
2+
. The activity of diacetyl synthase was greatly stimulated by the addition of hemin or Cu
2+
, and the activity of NAD-dependent diacetyl reductase was very high. Hemin did not affect the activities of NADH oxidase and lactate dehydrogenase. These results indicated that the pyruvate formed via glycolysis would be rapidly converted to diacetyl and that the diacetyl would then be converted to acetoin by the NAD-dependent diacetyl reductase to reoxidize NADH when the cells were grown aerobically with hemin or Cu
2+
. On the other hand, the
Y
Glu
value for the hemincontaining culture was lower than for the culture without hemin, because acetate production was repressed when an excess of glucose was present. However, in the presence of lipoic acid, an essential cofactor of the dihydrolipoamide acetyltransferase part of the pyruvate dehydrogenase complex, hemin or Cu
2+
enhanced acetate production and then repressed diacetyl and acetoin production. The activity of diacetyl synthase was lowered by the addition of lipoic acid. These results indicate that hemin or Cu
2+
stimulates acetyl coenzyme A (acetyl-CoA) formation from pyruvate and that lipoic acid inhibits the condensation of acetyl-CoA with hydroxyethylthiamine PP
i
. In addition, it appears that acetyl-CoA not used for diacetyl synthesis is converted to acetate.
Modification of Water-Soluble Coal-Derived Products by Dibenzothiophene-Degrading Microorganisms
Authors: Stoner D. L. , Wey J. E. , Barrett K. B. , Jolley J. G. , Wright R. B. , Dugan P. R.
Published: January 2020

To study mechanisms by which microorganisms oxidize thiophenic sulfur in coal, we tested bacterial cultures for the ability to degrade dibenzothiophene (DBT), DBT-5-oxide, and DBT-sulfone and to modify water-soluble coal products derived from Illinois no. 6 and Ugljevik coals. In yeast extract medium, the majority of selected isolates degraded DBT and accumulated DBT-5-oxide in culture fluids; all but one of the cultures degraded DBT-5-oxide, and none of them degraded DBT-sulfone. Elemental analysis data indicated that the microbial cultures were able to decrease the amount of sulfur in soluble coal products derived from Illinois no. 6 and Ugljevik coals. However, these data suggested that microbially mediated sulfur removal from soluble Ugljevik coal occurred by nonspecific mechanisms. That is, extensive degradation of the carbon structure was concurrent with the loss of sulfur. This conclusion was supported by X-ray photoelectron spectroscopic data which indicated that the reduced sulfur forms in the soluble Ugljevik coal product was not oxidized by microbial treatment.
Formation of Stable Bdelloplasts as a Starvation-Survival Strategy of Marine Bdellovibrios
Authors: Sánchez-Amat A. , Torrella F.
Published: January 2020

Several wild-type isolates of marine bdellovibrios formed stable bdelloplasts when they infected gram-negative bacterial prey under certain culture conditions. Synchronous predator-prey cultures and low nutrient concentrations increased the yield of stable bdelloplasts. The bdellovibrio cells retained in the stable bdelloplasts showed a high survival capacity in nutrient-depleted saline solution (10% viable
Bdellovibrio
cells after 3 months at 25°C), whereas
Bdellovibrio
attack-phase cells kept under the same starvation conditions lost viability more quickly (1% viable cells after 48 h). The addition of yeast extract to a stable bdelloplast suspension induced lysis of the bdelloplasts and release of motile infecting attack-phase
Bdellovibrio
cells. Other substances, such as free amino acids, protein hydrolysates, NH
4
+
, carbohydrates, and organic amines, did not induce such a release. Stable bdelloplasts were highly hydrophobic and had a lower endogenous respiration rate than attack-phase cells. In general, stable bdelloplasts were almost as sensitive to temperature changes, desiccation, sonication, tannic acid, and Triton X-100 treatment as attack-phase cells. Electron microscopy of stable bdelloplasts did not reveal any extra cell wall layer, either in the bdelloplast envelope or in the retained
Bdellovibrio
cells, unlike the bdellocysts of the soil bacterium
Bdellovibrio
sp. strain W. We propose that formation of stable bdelloplasts is a survival strategy of marine bdellovibrios which occurs in response to nutrient- and prey-poor seawater habitats.