bluuebunny/crossref_metadata_2025 huggingface dataset:
Betaine Fermentation and Oxidation by Marine
Desulfuromonas
Strains
Authors: Heijthuijsen J. H. F. G. , Hansen T. A.
Published: January 2020

Two bacterial strains were dominant in anaerobic enrichment cultures with betaine (
N,N,N
-trimethylglycine) as a substrate and intertidal mud as an inoculum. One was a coccoid bacterium which was a trimethylamine (TMA)-fermenting methanogen similar to
Methanococcoides methylutens.
The other strain, a rod-shaped, gram-negative, motile bacterium, fermented betaine. On the basis of its ability to oxidize acetate and ethanol to CO
2
with sulfur as an electron acceptor, its inability to reduce sulfate and sulfite, its morphology, the presence of
c
-type cytochromes, and other characteristics, the isolated strain PM1 was identified as
Desulfuromonas acetoxidans.
Although only malate and fumarate were known as substrates for fermentative growth of this species, the type strain (DSM 684) also fermented betaine. Strain PM1 grew with a doubling time of 9.5 h at 30°C on betaine and produced approximately 1 mol of TMA per mol of betaine, 0.75 mol of acetate, and presumably CO
2
as fermentation products but only in the presence of selenite (100 nM). In this fermentation, betaine is probably reductively cleaved to TMA and acetate, and part of the acetate is then oxidized to CO
2
to provide the reducing equivalents for the initial cleavage reaction. In the presence of sulfur, betaine was converted to TMA and presumably CO
2
with the formation of sulfide; then, only traces of acetate were produced.
Description of an Estuarine Methylotrophic Methanogen Which Grows on Dimethyl Sulfide
Authors: Oremland Ronald S. , Kiene Ronald P. , Mathrani Indra , Whiticar Michael J. , Boone David R.
Published: January 2020

Characteristics of an obligately methylotrophic coccoid methanogen (strain GS-16) previously isolated from estuarine sediment are described. Growth was demonstrated on dimethyl sulfide (DMS) or trimethylamine (TMA), but not on methane thiol, methane thiol plus hydrogen, dimethyl disulfide, or methionine. DMS-grown cells were able to metabolize DMS and TMA simultaneously when inoculated into media containing substrate levels of these compounds. However, TMA-grown cells could not metabolize [
14
C]DMS to
14
CH
4
, although they could convert [
14
C]methanol to
14
CH
4
. These results suggest that metabolism of DMS proceeds along a somewhat different route than that of TMA and perhaps also that of methanol. The organism exhibited doubling times of 23 and 32 h for growth (25°C) in mineral media on TMA and DMS, respectively. Doubling times were more rapid (∼6 h) when the organisms were grown on TMA in complex broth. In mineral media, the fastest growth on DMS occurred between pH levels of 7.0 and 8.7, at 29°C, and with 0.2 to 0.4 M Na
+
and 0.04 M Mg
2+
. Somewhat different results occurred for growth on TMA in complex broth. Cells had a moles percent G+C value of 44.5% for their DNA. Growth on DMS, TMA, and methanol yielded stable carbon isotope fractionation factors of 1.044, 1.037, and 1.063, respectively. Fractionation factors for hydrogen were 1.203 (DMS) and 1.183 (TMA).
Nickel transport by the thermophilic acetogen Acetogenium kivui
Authors: Yang H C , Daniel S L , Hsu T D , Drake H L
Published: January 2020

Exogenous 63Ni was incorporated into carbon monoxide dehydrogenase when Acetogenium kivui ATCC 33488 was cultivated in the presence of 63NiCl2. The capacity for nickel (63NiCl2) transport was greatest with cells harvested from the mid- to late exponential phases of growth. Nickel transport was linear during the transport assay period and displayed saturation kinetics. The apparent Km and Vmax for nickel transport by H2-cultivated cells approximated 2.3 microM Ni and 670 pmol of Ni transported per min per mg (dry weight) of cells, respectively. The nickel transport system was not appreciably affected by the other divalent cations that were tested, and transported nickel was not readily exchangeable with exogenous nickel. Nickel transport was stimulated by glucose or H2 and was decreased by various metabolic inhibitors; however, nickel uptake by glucose- and H2-cultivated cells displayed differential sensitivities to ATPase inhibitors.
Competitive Inhibition of Ferrous Iron Oxidation by
Thiobacillus ferrooxidans
by Increasing Concentrations of Cells
Authors: Suzuki Isamu , Lizama Hector M. , Tackaberry Patrick D.
Published: January 2020

The oxidation of ferrous iron (Fe
2+
) to ferric iron (Fe
3+
) with dioxygen (O
2
) by various strains of
Thiobacillus ferrooxidans
was studied by measuring the rate of O
2
consumption at various Fe
2+
concentrations and cell concentrations. The apparent

K
m

values for Fe
2+
remained constant at different cell concentrations of laboratory strains ATCC 13661 and ATCC 19859 but increased with increasing cell concentrations of mine isolates SM-4 and SM-5. The latter results are explained by the competitive inhibition of the Fe
2+
-binding site of a cell by other cells in the reaction mixture. Possible mechanisms involving cell surface properties are discussed.
Colonial and Cellular Polymorphism in
Xenorhabdus luminescens
Authors: Hurlbert Ronald E. , Xu Jimin , Small Christopher L.
Published: January 2020

A highly polymorphic
Xenorhabdus luminescens
strain was isolated. The primary form of
X. luminescens
was luminescent and nonswarming and produced a yellow pigment and antimicrobial substances. The primary form generated a secondary form that had a distinct orange pigmentation, was weakly luminescent, and did not produce antimicrobial substances. Both the primary and secondary forms generated a set of colony variants at frequencies that exceeded normal rates for spontaneous mutation. The variant forms include nonswarming and swarming forms that formed large colonies and a small-colony (SC) form. The primary and secondary forms generated their SC forms at frequencies of between 1 and 14% and 1 and 2%, respectively. The SC forms were distinct from their parental primary and secondary forms in colony and cellular morphology and in protein composition. The cellular morphology and protein patterns of the nonswarming and swarming colony variants were all very similar. The DNA fingerprints of all forms were similar. Each SC-form colony reverted at high frequency to the form from which it was derived. The proportion of parental-type cells in the SC-form colonies varied with age, with young colonies containing as few as 0.0002% parental-type cells. The primary-to-secondary switch was stable, but all the other colony forms were able to switch at high frequencies to the alternative colony phenotypes.
Characterization of the microbial community colonizing the anal and vulvar pores of helminths from the hindgut of zebras
Authors: Mackie R I , Krecek R C , Els H J , van Niekerk J P , Kirschner L M , Baecker A A
Published: January 2020

Scanning and transmission electron microscopy were used to examine the adherence and in situ morphology of the microbial community colonizing the anal and vulvar pores of the subfamily Cyathostominae (Nematoda: Strongylidae) from the colon of Burchell's zebra (Equus burchelli antiquorum). Two different morphological types of asporogenous rod were prominent in the microbial community. One was a thin, septate, filamentous organism (0.4 to 0.5 micron by 2 to 3 microns) with blunt ends, which was more prominent at the site of attachment. The other was a larger (1.8 to 2.4 microns by 5 to 10 microns) multicellular rod with round ends in the form of a trichome. Spiral- and vibrio-shaped bacteria were also present in the thin sections. The septate filaments were shown to contain a cell spacer similar to those described in Methanospirillum hungatei. Attachment to the cuticle was by means of an amorphous electron-dense material with fibrillar appearance and not by specialized holdfast segments. Ten isolates were obtained from a habitat-simulating medium on which a homogenate from the posterior region was plated. Antibodies were raised to whole cells of five rod-shaped isolates in rabbits and fluorescein isothiocyanate labeled. Positive bright-yellow fluorescence was obtained with one of the clostridial isolates. The results are discussed with reference to other bacteria with similar morphology, the nature of this unique interrelationship between the microbial community and its parasitic host inside the equine hindgut, and the possibility of biological control of parasitic helminths.
Solutions to Problems in Enumerating Sediment Bacteria by Direct Counts
Authors: Schallenberg Marc , Kalff Jacob , Rasmussen Joseph B.
Published: January 2020

We examined the effect of different sediment types on the staining effectiveness of the fluorochrome DAPI (4′-6-diamidino-2-phenylindole dihydrochloride) over a wide range of concentrations and on the masking effect of sediment particles on DAPI-stained bacteria. Sediment type greatly affects the staining efficiency of DAPI, and most published studies seem to have underestimated bacterial abundances by using suboptimal concentrations of the fluorochrome. A DAPI concentration of 5 μg ml
−1
is required to effectively stain the bacteria in most sediments that can be sampled with a gravity corer. When the sediments are diluted 687 times (a dilution factor similar to those most often used in the literature), sediment particle masking of stained bacteria is highly variable for different sediment types. By using a measure of turbidity (
A
750
) to indicate masking and the quartz-corrected water content as a measure of the initial (in situ) dilution of each sediment type, it becomes possible to show a linear relationship between masking and the integrated (initial × experimental) dilution of various sediments. This relationship allows the development of a correction procedure for masking which makes accurate and unbiased counts possible. Data so obtained show a strong relationship between bacteria (cells per milliliter of fresh sediment) and sediment organic matter (grams [dry weight] per milliliter of fresh sediment), one that is not discernable without the correction. The proposed method of staining and correction for sediment masking provides the basis for a standardized interpretation of sediment bacterial counts.
Microbial Transformation of the Tetrazolinone Herbicide F5231
Authors: Schocken Mark J. , Creekmore R. William , Theodoridis George , Nystrom Gerald J. , Robinson Robert A.
Published: January 2020

Microbial transformation of the tetrazolinone herbicide F5231 was accomplished with the filamentous fungus
Absidia pseudocylindrospora
Hesseltine et Ellis (ATCC 24169). The fungus converted the herbicide to six metabolites which were identified spectrally by mass, infrared, and nuclear magnetic resonance spectroscopy.
Use of the Most-Probable-Number Technique To Detect
Polymyxa betae
(Plasmodiophoromycetes) in Soil
Authors: Ciafardini Gino , Marotta Bruna
Published: January 2020

The fungus
Polymyxa betae
is an obligate parasite of the roots of many plants of the family
Chenopodiaceae
. In the sugar beet, it acts as a vector of beet necrotic yellow vein virus, the agent of a serious disease known as rhizomania. With indirect methods of analysis, such as bioassay, one can establish only the presence or absence, but not the quantity, of
P. betae
in soil. A new method based on the technique of the most probable number (MPN) of infective units of
P. betae
present in the soil was developed on the basis of the biological characteristics of this microorganism. Compared with traditional bioassay methods, the MPN method is suitable for determining the contamination level of
P. betae
in a soil, and it appears promising for the routine analysis of many soil samples, whether they were affected by rhizomania or presumed noninfested. The instrumentation designed especially for the recovery of viable
P. betae
from soil with the MPN technique is made from commercially available materials, results in a saving of space during sample incubation, and permits this method to be used for any laboratory analysis.
Separation of Protein Crystals from Spores of
Bacillus thuringiensis
by Ludox Gradient Centrifugation
Authors: Zhu Yu Sheng , Brookes Allan , Carlson Ken , Filner Philip
Published: January 2020

A method is described for the purification of
Bacillus thuringiensis
protein crystals by Ludox gradient centrifugation. This method is simple, inexpensive, fast, and efficient compared with other techniques. It has been successfully used to purify and characterize the protein crystals from several
B. thuringiensis
strains.
Biodegradation of Natural and Synthetic Humic Acids by the White Rot Fungus
Phanerochaete chrysosporium
Authors: Blondeau Roland
Published: January 2020

Biodegradation of natural and synthetic (melanoidin) humic acids by
Phanerochaete chrysosporium
BKM-F 1767 was demonstrated by decolorization in batch culture, reduction in molecular weight, and
14
CO
2
production from labeled melanoidin. This biodegradation occurred during secondary metabolism of the fungus in nitrogen-limited cultures; experimental results suggest that all or a part of the lignin-degrading system of BKM-F 1767 plays a part in biodegradation.
Use of a novel air separation system in a fed-batch fermentative culture of Escherichia coli
Authors: Fass R , Clem T R , Shiloach J
Published: January 2020

A novel air separation system based on permeable membrane gas separation technology was used to cultivate Escherichia coli. The system fulfilled the dissolved oxygen requirements of a culture of E. coli grown on a glucose synthetic medium at a high and constant growth rate of 0.55 h-1. A biomass yield of 45 g (dry weight) per liter was achieved, and no by-product inhibition by acetate or CO2 was observed.
Use of Robotics To Dispense Culture Media
Authors: Brewer D. , Schwartzentruber K. , Taylor A.
Published: January 2020

Liquid and agar-containing media can be aseptically dispensed by a laboratory robot. Five errors occurred during the filling of 700 tubes with medium; four of these were due to imperfections of the screw-threaded caps of the culture tubes. The mean volume dispensed was 14.8 ml (standard deviation, 0.5;
n
= 50) when the system was set to deliver 15 ml.

Images
Growth of
Neocallimastix
sp. Strain R1 on Italian Ryegrass Hay: Removal of Neutral Sugars from Plant Cell Walls
Authors: Theodorou Michael K. , Longland Annette C. , Dhanoa Mewa S. , Lowe Susan E. , Trinci Anthony P. J.
Published: January 2020

The anaerobic fungus
Neocallimastix
sp. strain R1 was grown for up to 5 days on a medium containing autoclaved Italian ryegrass hay as the carbon source. Culture supernatants and digested cell walls were harvested at 12-h intervals. Supernatants were analyzed for the fermentation products formate and acetate, and residual cell walls were analyzed for dry-matter and neutral-sugar losses. Fungal growth was accompanied by the digestion of plant cell walls and the accumulation of fermentation products in culture media. Dry-matter losses were accounted for by removal of four major neutral sugars (arabinose, galactose, glucose, and xylose) from the plant cell walls. First-order reaction kinetics could be used to describe the loss of each sugar. All cell wall sugars, including arabinose and galactose, which are not fermented by
Neocallimastix
sp. strain R1 were removed simultaneously. Although the rates of removal of individual sugars were similar, there were significant differences in their extents of removal: the extent of removal of arabinose exceeded that of the other three sugars, and xylose was the least digestible. This study provides the first account of simultaneous (nonpreferential) removal of neutral sugars from plant cell walls by an anaerobic fungus. Although in vitro techniques were used, these results indicate a potentially significant role for the anaerobic fungi as fiber digesters in the rumen.
Characterization of Bacteria That Suppress
Rhizoctonia
Damping-Off in Bark Compost Media by Analysis of Fatty Acid Biomarkers
Authors: Tunlid A. , Hoitink H. A. J. , Low C. , White D. C.
Published: January 2020

Examination of cucumber roots (
Cucumis sativus
L.) grown in bark compost media and of the surrounding edaphic substrate showed profiles of polar lipid fatty acids commonly found in bacteria. The composition of fatty acids in these profiles differed significantly between roots grown in a medium naturally suppressive to
Rhizoctonia
damping-off and roots from a conducive medium. Cucumber roots from the suppressive medium had higher proportions of
cis
-vaccenic acid (18:1 ω 7
c
) and the iso-branched monoenoic fatty acid i17:1 ω 8 but lower proportions of several iso- and anteiso-branched fatty acids compared with roots from the conducive medium. The concentrations of the bacterial fatty acids were significantly lower in the surrounding media. However, the suppressive and conducive growth substrates had differences in the composition of the bacterial fatty acids similar to those found between the cucumber roots proper. These results suggest major differences in bacterial community composition between suppressive and conducive systems. Fatty acid analyses were also utilized to examine the effects on bacterial community composition of root colonization by
Flavobacterium balustinum
299, a biocontrol agent. The concentration of the most prominent fatty acid in this bacterium, i17:1 ω 8, was increased on roots produced from inoculated seeds in a medium rendered suppressive by the treatment. This change was concomitant with a significant increase in the concentration of 18:1 ω 7
c
, not present in the lipids of the antagonist, indicating a shift in the microflora from a conducive to a suppressive bacterial community.
Differential depuration of poliovirus, Escherichia coli, and a coliphage by the common mussel, Mytilus edulis
Authors: Power U F , Collins J K
Published: January 2020

The elimination of sewage effluent-associated poliovirus, Escherichia coli, and a 22-nm icosahedral coliphage by the common mussel, Mytilus edulis, was studied. Both laboratory-and commercial-scale recirculating, UV depuration systems were used in this study. In the laboratory system, the logarithms of the poliovirus, E. coli, and coliphage levels were reduced by 1.86, 2.9, and 2.16, respectively, within 52 h of depuration. The relative patterns and rates of elimination of the three organisms suggest that they are eliminated from mussels by different mechanisms during depuration under suitable conditions. Poliovirus was not included in experiments undertaken in the commercial-scale depuration system. The differences in the relative rates and patterns of elimination were maintained for E. coli and coliphage in this system, with the logarithm of the E. coli levels being reduced by 3.18 and the logarithm of the coliphage levels being reduced by 0.87. The results from both depuration systems suggest that E. coli is an inappropriate indicator of the efficiency of virus elimination during depuration. The coliphage used appears to be a more representative indicator. Depuration under stressful conditions appeared to have a negligible affect on poliovirus and coliphage elimination rates from mussels. However, the rate and pattern of E. coli elimination were dramatically affected by these conditions. Therefore, monitoring E. coli counts might prove useful in ensuring that mussels are functioning well during depuration.
Expression by Soil Bacteria of Nodulation Genes from
Rhizobium leguminosarum
biovar
trifolii
Authors: Jarvis B. D. W. , Ward L. J. H. , Slade E. A.
Published: January 2020

Gram-negative, rod-shaped bacteria from the soil of white clover-ryegrass pastures were screened for their ability to nodulate white clover (
Trifolium repens
) cultivar Grasslands Huia and for DNA homology with genomic DNA from
Rhizobium leguminosarum
biovar
trifolii
ICMP2668 (NZP582). Of these strains, 3.2% were able to hybridize with strain ICMP2668 and nodulate white clover and approximately 19% hybridized but were unable to nodulate. Strains which nodulated but did not hybridize with strain ICMP2668 were not detected. DNA from
R. leguminosarum
biovar
trifolii
(strain PN165) cured of its symbiotic (Sym) plasmid and a specific
nod
probe were used to show that the relationship observed was usually due to chromosomal homology. Plasmid pPN1, a cointegrate of the broad-host-range plasmid R68.45 and a symbiotic plasmid pRtr514a, was transferred by conjugation to representative strains of nonnodulating, gram-negative, rod-shaped soil bacteria. Transconjugants which formed nodules were obtained from 6 of 18 (33%) strains whose DNA hybridized with that of PN165 and 1 of 9 (11%) strains containing DNA which did not hybridize with that of PN165. The presence and location of R68.45 and
nod
genes was confirmed in transconjugants from three of the strains which formed nodules. Similarly, a pLAFR1 cosmid containing
nod
genes from a derivative of
R. leguminosarum
biovar
trifolii
NZP514 formed nodules when transferred to soil bacteria.
Production of enterotoxin A by supposedly nonenterotoxigenic Staphylococcus aureus strains
Authors: Gomez-Lucía E , Goyache J , Orden J A , Blanco J L , Ruiz-Santa-Quiteria J A , Domínguez L , Suárez G
Published: January 2020

The production of staphylococcal enterotoxins A (SEA) and B (SEB) was studied by inoculating six well-defined staphylococcal collection strains into cow's, goat's, or sheep's milk (individually or as a 50% mixture of cow's + goat's or cow's + sheep's), into brain heart infusion, and into a medium generally used to enhance the synthesis of enterotoxins (3+3 medium). Four of the strains used are considered to be SEB producers, another is considered an SEA producer, and the remaining strain is nonenterotoxigenic but produces large quantities of staphylococcal protein A. Staphylococcal protein A masked the results in most cases. Only one strain secreted exclusively SEB, while the other three SEB producers synthesized SEA in different amounts. We conclude that enterotoxin production depends on the natural substrate and may differ from the results obtained when the strain is grown on cellophane over agar to determine its toxigenicity.
Selection by Anion-Exchange Chromatography of Exopolysaccharide Mutants of the Cyanobacterium
Synechocystis
Strain PCC 6803
Authors: Panoff Jean-Michel , Joset Françoise
Published: January 2020

The degree of retention of whole cells of
Synechocystis
strain PCC 6803 on DEAE-cellulose columns was shown to depend on their content of exopolysaccharides, which are at least in part responsible for the external negative charge of the cells. This feature was used for the isolation of mutants modified in the apparent viscosity caused by these macromolecular constituents. When a wild-type suspension was loaded onto a DE52 column, the cells eluting in the two extreme fractions of a 0 to 5 M NaCl step gradient represented 10
−9
to 10
−7
of the total eluted population. The accuracy of the procedure was established through the analysis of four clones: Suc(0)32 and Suc(0)65 (0 M) and Suc(5)64A and Suc(5)61 (5 M). The decreased viscosity of the exopolymers of the two 0 M clones, which appeared identical, could be related to the production of molecules less charged in uronic acids and more readily liberated from the cells. The two 5 M clones exhibited a lower sedimentation velocity, correlating with either a 60% increase in uronic acid and a doubling of the specific viscosity of the exopolysaccharides [clone Suc(5)64A] or a doubling of the per-cell production of polymers otherwise identical to those from wild-type cells [clone Suc(5)61].
Anaerobic Degradation of Chloroaromatic Compounds in Aquatic Sediments under a Variety of Enrichment Conditions
Authors: Genthner Barbara R. Sharak , Price W. Allen , Pritchard P. H.
Published: January 2020

Anaerobic degradation of monochlorophenols and monochlorobenzoates in a variety of aquatic sediments was compared under four enrichment conditions. A broader range of compounds was degraded in enrichments inoculated with sediment exposed to industrial effluents. Degradation of chloroaromatic compounds was observed most often in methanogenic enrichments and in enrichments amended with 1 mM bromoethane sulfonic acid. Degradation was observed least often in enrichments with added nitrate or sulfate. The presence of 10 mM bromoethane sulfonic acid prevented or inhibited degradation of most compounds tested. Primary enrichments in which KNO
3
was periodically replenished to maintain enrichment characteristics degraded chlorobenzoates, but not chlorophenols. In contrast, primary enrichments in which Na
2
SO
4
was periodically replenished failed to degrade any chloroaromatic compounds. Upon transfer to fresh medium, none of the sulfate enrichments required the presence of Na
2
SO
4
for degradation, while only two nitrate enrichments required the presence of KNO
3
for degradation. As a class of compounds, chlorophenols were degraded more readily than chlorobenzoates. However, as individual compounds 3-chlorobenzoate, 2-chlorophenol, and 3-chlorophenol degradation was observed most often and with an equal frequency. Within the chlorophenol class, the relative order of degradability was
ortho
>
meta
>
para
, while that of chlorobenzoates was
meta
>
ortho
>
para
, In laboratory transfers, 2-chlorobenzoate, 3-chlorobenzoate, and 2-chlorophenol degradation was most easily maintained, while degradation of
para
-chlorinated compounds was very difficult to maintain.
Regulation of Trichodiene Synthase in
Fusarium sporotrichioides
and
Gibberella pulicaris
(
Fusarium sambucinum
)
Authors: Hohn Thomas M. , Beremand Marian N.
Published: January 2020

The regulation of trichodiene synthase (TS) and its relationship to trichothecene biosynthesis was investigated in
Fusarium sporotrichioides
NRRL 3299 and
Gibberella pulicaris
R-6380. Cultures were analyzed for the presence of TS activity, trichothecenes, and immunodetectable TS polypeptide over a time period of 144 h. Enzyme activity increased from barely detectable to maximum levels over a period of 3 h for
F. sporotrichioides
, while in
G. pulicaris
, a steady increase was observed over 144 h. Increases in TS activity of 50-fold for
F. sporotrichioides
and 10-fold for
G. pulicaris
R-6380 preceded by several hours the detection of trichothecenes. Immunoblot analysis employing polyclonal serum specific for the enzyme from
F. sporotrichioides
showed that increases in the levels of TS polypeptide corresponded to the observed changes in enzyme activity for both organisms. These data indicate that the regulation of TS activity is accomplished through increases in its cellular concentration and that TS may serve as a useful indicator of trichothecene biosynthetic activity.
Effect of disinfection of drinking water with ozone or chlorine dioxide on survival of Cryptosporidium parvum oocysts
Authors: Peeters J E , Mazás E A , Masschelein W J , Villacorta Martiez de Maturana I , Debacker E
Published: January 2020

Demineralized water was seeded with controlled numbers of oocysts of Cryptosporidium parvum purified from fresh calf feces and subjected to different treatments with ozone or chlorine dioxide. The disinfectants were neutralized by sodium thiosulfate, and neonatal mice were inoculated intragastrically and sacrificed 7 days later for enumeration of oocyst production. Preliminary trials indicated that a minimum infection level of 1,000 oocysts (0.1-ml inoculum) per mouse was necessary to induce 100% infection. Treatment of water containing 10(4) oocysts per ml with 1.11 mg of ozone per liter (concentration at time zero [C0]) for 6 min totally eliminated the infectivity of the oocysts for neonatal mice. A level of 2.27 mg of ozone per liter (C0) was necessary to inactivate water containing 5 x 10(5) oocysts per ml within 8 min. Also, 0.4 mg of chlorine dioxide per liter (C0) significantly reduced infectivity within 15 min of contact, although some oocysts remained viable.
Antibacterial Activity of Sirodesmin PL Phytotoxin: Application to the Selection of Phytotoxin-Deficient Mutants
Authors: Boudart Georges
Published: January 2020

Sirodesmin PL, a phytotoxin and mycotoxin produced by
Leptosphaeria maculans
, the causal agent of stem-canker disease of crucifers, exhibited antibacterial activity against gram-positive bacteria and particularly
Bacillus subtilis.
The importance of the disulfide bridge of the molecule in antibacterial activity was demonstrated. A simple and reliable bioassay based on the antibacterial activity of the toxin was performed for screening sirodesmin PL-deficient mutants when grown on solid culture medium. A mutant was selected and found to produce 3,700-fold less toxin than did the wild-type strain. A sensitive procedure for quantification of the toxin by high-pressure liquid chromatography was developed. Levels of product as low as 100 ng could be detected by this procedure.
Hybridization of DNA probes with whole-community genome for detection of genes that encode microbial responses to pollutants: mer genes and Hg2+ resistance
Authors: Barkay T , Liebert C , Gillman M
Published: January 2020

Nucleic acids extracted from microbial biomass without prior culturing were hybridized with probes representing four mer operons to detect genes encoding adaptation to Hg2+ in whole-community genomes. A 29-fold enrichment in sequences similar to the mer genes of transposon Tn501 occurred during adaptation in a freshwater community. In an estuarine community, all four mer genes were only slightly enriched (by three- to fivefold), suggesting that additional, yet uncharacterized, mer genes encoded adaptation to Hg2+.
Thermostable, Raw-Starch-Digesting Amylase from
Bacillus stearothermophilus
Authors: Kim Jaeyoung , Nanmori Takashi , Shinke Ryu
Published: January 2020

An endospore-forming thermophilic bacterium, which produced amylase and was identified as
Bacillus stearothermophilus,
was isolated from soil. The amylase had an optimum temperature of 70°C and strongly degraded wheat starch granules (93%) and potato starch granules (80%) at 60°C.
Transformation of Bacillus cereus vegetative cells by electroporation
Authors: Belliveau B H , Trevors J T
Published: January 2020

Transformation of untreated vegetative cells of Bacillus cereus 569 with plasmid pC194 (1.8 megadaltons) by high-voltage electroporation resulted in a maximum of 2 x 10(-5) transformants per viable cell. Transformation of a 130-megadalton plasmid occurred at a comparable frequency. The method was simple, rapid, and yielded transformant colonies in 14 to 24 h. Transformation was obtained with unpurified total plasmid DNA.
Partial purification and characterization of an NAD-dependent 3 beta-hydroxysteroid dehydrogenase from Clostridium innocuum
Authors: Edenharder R , Pfützner M
Published: January 2020

In nine strains of Clostridium innocuum, 3 beta-hydroxysteroid-dehydrogenating activities were detected. 3 beta, 7 alpha, 12 alpha-Trihydroxy- and 3 beta-hydroxy-12-keto-5 beta-cholanoic acids were identified as reduction products of the respective 3-keto bile acids by gas-liquid chromatography and gas-liquid chromatography-mass spectrometry. One strain was shown to contain a NAD-dependent 3 beta-hydroxysteroid dehydrogenase. Enzyme production was constitutive in the absence of added bile acids. The specific enzyme activity was significantly reduced by growth medium supplementation with 3-keto bile acids, with trisubstituted acids being more effective than disubstituted ones. A pH optimum of 10.0 to 10.2 was found after partial purification by DEAE-cellulose chromatography. A molecular weight of about 56,000 was established. 3 beta-hydroxysteroid dehydrogenase activity was also found in the membrane fraction after solubilization with Triton X-100, suggesting that the enzyme was originally membrane bound. The enzyme reduced a 3-keto group in unconjugated and conjugated bile acids, lower Km values being demonstrated with disubstituted than with trisubstituted bile acids. Keto functions at C-7 and C-12 further reduced the Km value. The enzyme was found to be partially heat labile (86% inactivation at 50 degrees C for 10 min).
Analysis of pectate lyases produced by soft rot bacteria associated with spoilage of vegetables
Authors: Liao C H
Published: January 2020

Isoelectric focusing (IEF) profiles of pectate lyases (PLs) produced by five different groups of soft rot bacteria were analyzed by using the combined techniques of thin-layer polyacrylamide gel IEF and agarose-pectate overlay activity staining. Four strains of soft rot Erwinia spp. produced three or more PL isozymes. All of eight Pseudomonas viridiflava strains examined produced one single PL with a pI of 9.7. All 10 of Pseudomonas fluorescens strains produced two PLs; the major one had a pI of 10.0 and the minor one had a pI of 6.7. A single PL with a pI of greater than or equal to 10.0 was detected in one strain each of Xanthomonas campestris and Cytophaga johnsonae. PLs of six representative strains were purified from culture supernatants by ammonium sulfate precipitation and anion-exchange chromatography. All purified PL samples macerated potato slices, but to different degrees. The Mrs of alkaline PLs produced by P. viridiflava, P. fluorescens, X. campestris, and C. johnsonae were estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be 42,000, 41,000, 41,500, and 35,000, respectively. IEF profiles of PLs were distinct among the bacterial species. Profiles of non-Erwinia spoilage bacteria were considerably simpler than those of Erwinia spp. The PL with an alkaline pI appeared to be the principal or the sole enzymatic factor involved in tissue maceration caused by most strains of soft rot bacteria.
Growth characteristics on cellobiose of three different anaerobic fungi isolated from the ovine rumen
Authors: Phillips M W , Gordon G L
Published: January 2020

Three morphologically different anaerobic fungi, a Neocallimastix sp. strain (LM-1), a Piromonas sp. strain (SM-1), and a Sphaeromonas sp. strain (NM-1), were isolated from the rumens of sheep. Growth studies were conducted with each isolate in batch cultures by using an anaerobic semidefined medium that lacked ruminal fluid and contained 0.5% cellobiose. Cultures were incubated for periods of up to 10 days, and fungal growth was assessed at regular intervals by dry weight measurements. Samples of fungal biomass were also analyzed for cell-associated protein and, after acid hydrolysis, for chitin as hexosamine. The isolates produced similar yields of dry weight and contained similar amounts of protein. However, strain LM-1 grew at a higher rate and contained less than half the level of chitin compared with the other two isolates. There were high positive correlations between chitin and protein for all three fungi, but comparisons of these parameters with dry weights were affected by the presence of variable amounts of storage carbohydrate. The amount of storage carbohydrate reached maximum levels in strain LM-1 during mid-growth phase and then quickly declined thereafter. When dry weight yields for strain LM-1 were adjusted for changes in storage carbohydrate, high positive correlations were obtained between dry weight and protein or chitin. The storage carbohydrate was probably an alpha-1,4-glucan with alpha-1,6 branches.
Degradation and utilization of cellulose and straw by three different anaerobic fungi from the ovine rumen
Authors: Gordon G L , Phillips M W
Published: January 2020

Three different ruminal fungi, a Neocallimastix sp. (strain LM-1), a Piromonas sp. (strain SM-1), and a Sphaeromonas sp. (strain NM-1), were grown anaerobically in liquid media which contained a suspension of either 1% (wt/vol) purified cellulose or finely milled wheat straw as the source of fermentable carbon. Fungal biomass was estimated by using cell wall chitin or cellular protein in cellulose cultures and chitin in straw cultures. Both strains LM-1 and SM-1 degraded cellulose with a concomitant increase in fungal biomass. Maximum growth of both fungi occurred after incubation for 4 days, and the final yield of protein was the same for both fungi. Cellulose degradation continued after growth ceased. Strain NM-1 failed to grow in the cellulose medium. All three anaerobic fungi grew in the straw-containing medium, and loss of dry weight from the cultures indicated degradation of straw to various degrees (LM-1 greater than SM-1 greater than NM-1). The total fiber component and the cellulose component of the straw were degraded in similar proportions, but the lignin component remained undegraded by any of the fungi. Maximum growth yield on straw occurred after 4 days for strain LM-1 and after 5 days for strains SM-1 and NM-1. The calculated yield of cellular protein for strain LM-1 was twice that of both strains SM-1 and NM-1. The cellular protein yield of strain SM-1 was the same in both cellulose and straw cultures. In contrast to cellulose, straw degradation ceased after the end of the growth phase.(ABSTRACT TRUNCATED AT 250 WORDS)
Influence of
Bradyrhizobium japonicum
Location and Movement on Nodulation and Nitrogen Fixation in Soybeans
Authors: Wadisirisuk P. , Danso S. K. A. , Hardarson G. , Bowen G. D.
Published: January 2020

The influence of seed and soil inoculation on bradyrhizobial migration, nodulation, and N
2
fixation was examined by using two
Bradyrhizobium japonicum
strains of contrasting effectiveness in N
2
fixation. Seed-inoculated strains formed fewer nodules on soybeans (mostly restricted to the tap and crown roots within 0 to 5 cm from the stem base) than did bradyrhizobia distributed throughout the soil or inoculated at specific depths. Nodulation was greater below the depths at which bradyrhizobial cells were located rather than above, even though watering was done from below to minimize passive bradyrhizobial migration with percolating water. The most profuse nodulation occurred within approximately 5 cm below the point of placement and was generally negligible below 10 cm. These and other results suggest that bradyrhizobial migration from the initial point of placement was very limited. Nevertheless, the more competitive strain, effective strain THA 7, migrated into soil to a greater extent than the ineffective strain THA 1 did. Nitrogen fixation resulting from the dual-strain inoculations differed depending on the method of inoculation. For example, the amount of N
2
fixed when both strains were slurried together onto the seed was about half that obtained from mixing the effective strain into the soil with the ineffective strain on the seed. The results indicate the importance of rhizobial distribution or movement into soil for nodulation, nodule distribution, strain competitiveness, and N
2
fixation in soil-grown legumes.
Diffusion of the Interspecies Electron Carriers H
2
and Formate in Methanogenic Ecosystems and Its Implications in the Measurement of
K

m

for H
2
or Formate Uptake
Authors: Boone David R. , Johnson Richard L. , Liu Yitai
Published: January 2020

We calculated the potential H
2
and formate diffusion between microbes and found that at H
2
concentrations commonly found in nature, H
2
could not diffuse rapidly enough to dispersed methanogenic cells to account for the rate of methane synthesis but formate could. Our calculations were based on individual organisms dispersed in the medium, as supported by microscopic observations of butyrate-degrading cocultures. We isolated an axenic culture of
Syntrophomonas wolfei
and cultivated it on butyrate in syntrophic coculture with
Methanobacterium formicicum
; during growth the H
2
concentration was 63 nM (10.6 Pa).
S. wolfei
contained formate dehydrogenase activity (as does
M. formicicum
), which would allow interspecies formate transfer in that coculture. Thus, interspecies formate transfer may be the predominant mechanism of syntrophy. Our diffusion calculations also indicated that H
2
concentration at the cell surface of H
2
-consuming organisms was low but increased to approximately the bulk-fluid concentration at a distance of about 10 μm from the surface. Thus, routine estimation of kinetic parameters would greatly overestimate the
K

m

for H
2
or formate.
Determination of Biomass by Ultrasonic Measurements
Authors: Zips A. , Faust U.
Published: January 2020

The quantitative determination of biomass in a suspension by means of ultrasound velocity is a simple and on-line-applicable method. Such an ultrasonic sensor offers the advantage of being long-term stable, reliable, and sterilizable. In this paper we present sound velocity measurements made with different microorganisms. The experimental results which we have obtained with an impulse-echo method will be compared with theoretical predictions and discussed with respect to previous findings (Y. Ishimori, I. Karube, and S. Suzuki, Appl. Environ. Microbiol. 42:632-637, 1981).
Selective Recovery of 16S rRNA Sequences from Natural Microbial Communities in the Form of cDNA
Authors: Weller Roland , Ward David M.
Published: January 2020

Cloning of cDNA obtained from 16S rRNA (16S rcDNA) selectively retrieves species-specific sequence information useful for analyzing the composition and structure of natural microbial communities. With this technique we obtained recombinant 16S rcDNA libraries from
Escherichia coli
and from a model hot-spring cyanobacterial-mat community. The recombinant plasmids contained exclusively 16S rRNA-derived inserts. This selective approach is independent of biasing culture techniques and eliminates the laborious screening required to locate 16S rRNA gene-bearing recombinants in genomic DNA libraries obtained from natural communities.
Antibacterial activity of Lactobacillus sake isolated from meat
Authors: Schillinger U , L�cke F K
Published: January 2020

A total of 221 strains of Lactobacillus isolated from meat and meat products were screened for antagonistic activities under conditions that eliminated the effects of organic acids and hydrogen peroxide. Nineteen strains of Lactobacillus sake, three strains of Lactobacillus plantarum, and one strain of Lactobacillus curvatus were shown to inhibit the growth of some other lactobacilli in an agar spot test; and cell-free supernatants from 6 of the 19 strains of L. sake exhibited inhibitory activity against indicator organisms. Comparison of the antimicrobial spectra of the supernatants suggested that the inhibitory compounds were not identical. One of the six strains, L. sake Lb 706, was chosen for further study. The compound excreted by L. sake Lb 706 was active against various lactic acid bacteria and Listeria monocytogenes. Its proteinaceous nature, narrow inhibitory spectrum, and bactericidal mode of action indicated that this substance is a bacteriocin, which we designated sakacin A. Curing experiments with two bacteriocin-producing strains of L. sake resulted in mutants that lacked both bacteriocin activity and immunity to the bacteriocin. Plasmid profile analysis of L. sake Lb 706 and two bacteriocin-negative variants of this strain indicated that a plasmid of about 18 megadaltons may be involved in the formation of bacteriocin and immunity to this antibacterial compound. In mixed culture, the bacteriocin-sensitive organisms were killed after the bacteriocin-producing strain reached maximal cell density, whereas there was no decrease in cell number in the presence of the bacteriocin-negative variant.
Identification of Vibrio anguillarum in fish by using partial 16S rRNA sequences and a specific 16S rRNA oligonucleotide probe
Authors: Rehnstam A S , Norqvist A , Wolf-Watz H , Hagstr�m A
Published: January 2020

16S rRNA from seven different Vibrio anguillarum strains was partially sequenced and compared. From this sequence information we could design a 25-base-long oligonucleotide and use it as a specific probe for identification of V. anguillarum. This was determined by RNA-DNA colony hybridization and slot-blot hybridization. Strong, specific hybridization to the probe was observed for all V. anguillarum strains tested. Furthermore, no cross-hybridization could be seen against five other bacterial species. The detection limit was 5 x 10(3) bacteria per ml. It was even possible to detect V. anguillarum, by slot-blot hybridization, directly in a homogenized kidney from a fish that had died of vibriosis. The partial sequence information revealed small but significant differences between strains of the same species. These sequence differences are sufficiently significant to allow serotyping on the RNA level. Comparing strains of different serotypes revealed a 10-base and an 11-base difference in V. anguillarum serotypes O8 and O9, respectively, in a 122-base partial sequence.
Nodulation of
Glycine max
by Six
Bradyrhizobium japonicum
Strains with Different Competitive Abilities
Authors: Smith Geoffrey B. , Wollum A. G.
Published: January 2020

The root nodule locations of six
Bradyrhizobium japonicum
strains were examined to determine if there were any differences which might explain their varying competitiveness for nodule occupancy on
Glycine max.
When five strains were added to soybeans in plastic growth pouches in equal proportions with a reference strain (U.S. Department of Agriculture, strain 110), North Carolina strain 1028 and strain 110 were the most competitive for nodule occupancy, followed by U.S. Department of Agriculture strains 122, 76, and 31 and Brazil strain 587. Among all strains, nodule double occupancy was 17% at a high inoculum level (10
7
CFU pouch
−1
) and 2% at a low inoculum level (10
4
CFU pouch
−1
). The less competitive strains increased their nodule representation by an increase in the doubly occupied nodules at the high inoculum level. Among all strains, the number of taproot and lateral root nodules was inversely related at both the high and low inoculum levels (
r
= −0.62 and −0.69, respectively;
P
= 0.0001). This inverse relationship appeared to be a result of the plant host control of bacterial infection. Among each of the six strains, greater than 95% of the taproot nodules formed at the high inoculum density were located on 25% of the taproot length, the nodules centering on the position of the root tip at the time of inoculation. No differences among the six strains were observed in nodule initiation rates as measured by taproot nodule position. Taproot nodules were formed in the symbiosis before lateral root nodules. One of the poorly competitive strains (strain 76) occupied three times as many taproot nodules as lateral root nodules when competing with strain 110 (nodules were harvested from 4-week-old plants). Among these six wild-type strains of
B. japonicum,
competitive ability evidently is not related to nodule initiation rates.
Polycyclic aromatic hydrocarbon degradation by a Mycobacterium sp. in microcosms containing sediment and water from a pristine ecosystem
Authors: Heitkamp M A , Cerniglia C E
Published: January 2020

Microcosm studies were conducted to evaluate the survival and performance of a recently discovered polycyclic aromatic hydrocarbon (PAH)-degrading Mycobacterium sp. when this organism was added to sediment and water from a pristine ecosystem. Microcosms inoculated with the Mycobacterium sp. showed enhanced mineralization, singly and as components in a mixture, of 2-methylnaphthalene, phenanthrene, pyrene, and benzo[alpha]pyrene. Studies utilizing pyrene as the sole added PAH showed that the Mycobacterium sp. survived in microcosms for 6 weeks both with and without preexposure to PAH and mineralized multiple doses of pyrene. Pyrene mineralization rates for sterilized microcosms inoculated with the Mycobacterium sp. showed that competition with indigenous microorganisms did not adversely affect survival of or pyrene degradation by the Mycobacterium sp. Pyrene mineralization by the Mycobacterium sp. was not enhanced by inorganic nutrient enrichment and was hindered by organic nutrient enrichment, which appeared to result from overgrowth of indigenous bacteria. This study demonstrates the versatility of the PAH-degrading Mycobacterium sp. and expands its potential applications to include the degradation of two-, three-, four-, and five-ringed PAHs in sediments.