bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation and Characterization of Mutants of
Clostridium acetobutylicum
ATCC 824 Deficient in Acetoacetyl-Coenzyme A:Acetate/Butyrate:Coenzyme A-Transferase (EC 2.8.3.9) and in Other Solvent Pathway Enzymes
Authors: Clark Sandra W. , Bennett George N. , Rudolph Frederick B.
Published: January 2020

Mutants of
Clostridium acetobutylicum
ATCC 824 exhibiting resistance to 2-bromobutyrate or rifampin were isolated after nitrosoguanidine treatment. Mutants were screened for solvent production by using an automated alcohol test system. Isolates were analyzed for levels of butanol, ethanol, acetone, butyrate, acetate, and acetoin in stationary-phase batch cultures. The specific activities of NADH- and NADPH-dependent butanol dehydrogenase and butyraldehyde dehydrogenase as well as those of acetoacetyl-coenzyme A:acetate/butyrate:coenzyme A-transferase (butyrate-acetoacetate coenzyme A-transferase [EC 2.8.3.9]) (CoA-transferase), butyrate kinase, and phosphotransbutyrylase were measured at the onset of stationary phase. Rifampin-resistant strain D10 and 2-bromobutyrate mutant R were found to be deficient in only CoA-transferase, while several other mutants exhibited reduced butyraldehyde dehydrogenase and butanol dehydrogenase activities as well. The colony morphology of 2-bromobutyrate mutant R was similar to that of the parent on RCM medium; however, it had about 1/10 the level of CoA-transferase and increased levels of butanol dehydrogenase and butyraldehyde dehydrogenase. A nonsporulating, spontaneously derived degenerated strain exhibited reduced levels of butyraldehyde dehydrogenase, butanol, dehydrogenase, and CoA-transferase compared with those of the original strain. When
C. acetobutylicum
ATCC 824 was grown on medium containing low levels of 2-bromobutyrate, an altered colony morphology was observed. Not all strains resistant to 2-bromobutyrate (12 mM) were non-solvent-producing strains.
Effects of Organic Acid Anions on the Growth and Metabolism of
Syntrophomonas wolfei
in Pure Culture and in Defined Consortia
Authors: Beaty P. Shawn , McInerney Michael J.
Published: January 2020

The effects of organic acid anions on the growth of
Syntrophomonas wolfei
was determined by varying the initial concentration of the acid anion in the medium. The addition of 15 mM acetate decreased the growth rate of a butyrate-catabolizing coculture containing
Methanospirillum hungatei
from 0.0085 to 0.0029 per hour. Higher initial acetate concentrations decreased the butyrate degradation rate and the yield of cells of
S. wolfei
per butyrate degraded. Inhibition was not due to the counter ion or the effect of acetate on the methanogen. Initial acetate concentrations above 25 mM inhibited crotonate-using pure cultures and cocultures of
S. wolfei
. Benzoate and lactate inhibited the growth of
S. wolfei
on crotonate in pure culture and coculture. Lactate was an effective inhibitor of
S. wolfei
cultures at concentrations greater than 10 mM. High concentrations of acetate and lactate altered the electron flow in crotonate-catabolizing cocultures, resulting in the formation of less methane and more butyrate and caproate. The inclusion of the acetate-using methanogen,
Methanosarcina barkeri
, in a methanogenic butyrate-catabolizing coculture increased both the yield of
S. wolfei
cells per butyrate degraded and the efficacy of butyrate degradation. Butyrate degradation by acetate-inhibited cocultures occurred only after the addition of
Methanosarcina barkeri
. These results showed that the metabolism of
S. wolfei
was inhibited by high levels of organic acid anions. The activity of acetate-using methanogens is important for the syntrophic degradation of fatty acids when high levels of acetate are present.
More monensin-sensitive, ammonia-producing bacteria from the rumen
Authors: Chen G , Russell J B
Published: January 2020

Two monensin-sensitive bacteria which utilized carbohydrates poorly and grew rapidly on amino acids were isolated from the bovine rumen. The short rods (strain SR) fermented arginine, serine, lysine, glutamine, and threonine rapidly (greater than 158 nmol/mg of protein per h) and grew faster on casein digest containing short peptides than on free amino acids ().34 versus 0.29 h(-1)). Gelatin hydrolysate, an amino acid source containing an abundance of long peptides, was unable to support growth or ammonia production, but there was a large increase in ammonia production if strain SR was cocultured with peptidase-producing ruminal bacteria (Bacteroides ruminicola or Streptococcus bovis). Cocultures showed no synergism with short peptides. Strain SR washed out of continuous culture ().1 h(-1)) at pH 5.9. The irregularly shaped organisms (strain F) deaminated glutamine, histidine, glutamate, and serine rapidly (greater than 137 nmol/mg of protein per min) and grew faster on free amino acids than on short peptides ().43 versus 0.21 h(-1)). When strain F was provided with casein or gelatin hydrolysate and cocultured with peptidase-producing bacteria, there was a more than additive increase in ammonia production. Strain F grew in continuous culture (0.1 h(-1)) when the pH was as low as 5.3. The irregularly shaped cells and short rods were present at less than 10(9)/ml in vivo, but they ahd very high specific activities of ammonia production (greater than 310 nmol of ammonia/mg of protein per min) and could play an important role in ruminal amino acid fermentation.
Solubilization and renaturation of overexpressed aggregates of mutant tryptophan synthase alpha-subunits
Authors: Lim W K , Smith-Somerville H E , Hardman J K
Published: January 2020

Certain Escherichia coli tryptophan synthase mutant alpha-subunits encoded from mutagenized trpA-containing plasmids were overexpressed as insoluble aggregates which were seen as large, intracellular inclusion bodies. The insoluble aggregates were solubilized to various degrees by several neutral, chaotropic salts. The order of effectiveness of these salts (KSCN, NaI greater than NaNO3, LiBr greater than CaCl2) followed that for the Hofmeister series. Optimum conditions for the use of KSCN resulted in a maximum 70 to 75% solubilization of the aggregate forms for all mutant alpha-subunits examined. Removal of KSCN by dialysis resulted in the recovery of biological activity and of certain characteristic structural properties. Such salts may be a useful alternative for other recombinant protein aggregates which resist complete renaturation by commonly used treatments with guanidine or urea.
Enumeration of selected anaerobic bacterial groups in cecal and colonic contents of growing-finishing pigs
Authors: Butine T J , Leedle J A
Published: January 2020

Selected anaerobic bacterial groups in cecal and colonic contents of clinically healthy pigs fed a corn-soybean meal production diet were determined at sacrifice after 4, 8, and 11 weeks on feed, corresponding to intervals within the growing-finishing growth period. By using ruminal fluid-based media, the densities of the culturable anaerobic population; the cellulolytic, pectin-fermenting, pectin-hydrolyzing, xylan-fermenting; and the xylan-hydrolyzing, sulfate-reducing, and methanogenic bacterial populations were estimated. An analysis of variance was performed on these bacterial group variables to examine the effects of phase (weeks on feed), site (cecum or colon), or the interaction of phase with site. The population of total anaerobic bacteria was twice as dense in the colon as it was in the cecum (2 x 10(10) versus 1 x 10(10)/g [wet weight]; P = 0.001). The proportion of cellulolytic bacteria was lower at 4 weeks on feed than at 8 or 11 weeks (23 versus 32%; P = 0.026), while the proportion of pectin-fermenting bacteria depended on the interaction of phase with site (P = 0.021). The numbers of sulfate-reducing bacteria were significantly higher in the colon than in the cecum (6 x 10(7) versus 3 x 10(7); P = 0.014), as were methanogenic bacteria (19 x 10(7) versus 0.6 x 10(7); P = 0.0002). The remaining bacterial groups were stable with respect to phase and site. The results suggest that except for density differences, the microbial communities of the pig cecum and colon are similar in composition throughout the growing-finishing phase.
Effect of Growth Rate and Starvation-Survival on the Viability and Stability of a Psychrophilic Marine Bacterium
Authors: Moyer Craig L. , Morita Richard Y.
Published: January 2020

Cell populations of the marine bacterium ANT-300, from either batch or continuous culture with dilution rates ranging from
D
= 0.015 h
−1
to
D
= 0.200 h
−1
, were monitored for viability, direct counts, and optical density for 98 days under starvation conditions. Three stages of starvation survival were observed for each of the cell populations. Although direct counts remained at 2 × 10
7
to 3 × 10
7
cells ml
−1
throughout the starvation period, large fluctuations occurred in cell viability during stage 1 (0 to 14 days) of starvation survival. Stage 2 (14 to 70 days) involved an overall decrease in viability for each of the cell populations; the rate of viability loss was dependent upon the growth rate. Cell viability stabilized at approximately 0.3% of the direct count in stage 3 (70 to 98 days). Long-term starvation corresponded to the prolongation of stage 3 starvation survival. Cell volumes for each of the cell populations decreased with the length of the starvation period. However, the cell volume of starved cells was also dependent more on growth rate than on the length of the time starved. We hypothesize that the cell population with the slowest growth rate is most closely representative of cells found in the oligotrophic marine environment.
Extraction of Zinc from Industrial Waste by a
Penicillium
sp
Authors: Schinner Franz , Burgstaller Wolfgang
Published: January 2020

Zinc was extracted from a filter residue of a copper works (58.6% zinc) by a
Penicillium
sp. isolated from a metal-containing location. By isotachophoresis citric acid was identified as the leaching agent. Citrate was only formed when the leaching substrate was present. This production of citrate was different in several ways from that achieved by
Aspergillus niger
: glucose was utilized before fructose; the initial concentration of zinc was 50 to 500 times higher than usual in citrate fermentations with
A. niger
; citrate production stopped when 80 to 90% of the zinc was leached, although sufficient sugar for further synthesis was still present; and in synthetic media citrate production by
A. niger
needs an acidic environment (pH 2), while the formation of citric acid by
Penicillium
sp. occurred in a pH range of 7 to 4. Tests with different concentrations of waste material (0.5, 2.5, and 5%) showed that the highest yield of solubilized zinc occurred with a 2.5% substrate (93% zinc extracted after 13 days).
Production of Major Extracellular Enzymes during Lignocellulose Degradation by Two Streptomycetes in Agitated Submerged Culture
Authors: Adhi Tri P. , Korus Roger A. , Crawford Don L.
Published: January 2020

Streptomyces viridosporus
T7A and
S. badius
252 were grown in 1 to 2% (wt/vol) slurry cultures with mineral salts solution containing 0.6% yeast extract and 100/200 mesh ground and extracted corn lignocellulose at 37�C. Enzyme activities rapidly increased in the first 3 to 4 days and then declined and remained at a relatively constant level. Concentrations of endoglucanase and xylanase produced by
S. badius
were lower than those produced by
S. viridosporus
. However, the lignin-peroxidase peak concentration was threefold higher than with
S. viridosporus
and was obtained at 9 to 10 days of incubation. By polyacrylamide gel analysis, it was determined that peroxidases from both species consisted of four enzymes, with only one, the lignin peroxidase, having high activity. A culture pH of 8.5 was preferable for lignocellulose degradation by
S. badius
.
Environmental significance of the potential for mer(Tn21)-mediated reduction of Hg2+ to Hg0 in natural waters
Authors: Barkay T , Liebert C , Gillman M
Published: January 2020

The role of mer(Tn21) in the adaptation of aquatic microbial communities to Hg2+ was investigated. Elemental mercury was the sole product of Hg2+ volatilization by freshwater and saline water microbial communities. Bacterial activity was responsible for biotransformation because most microeucaryotes did not survive the exposure conditions, and removal of larger microbes (greater than 1 micromole) from adapted communities did not significantly (P greater than 0.01) reduce Hg2+ volatilization rates. DNA sequences homologous to mer(Tn21) were found in 50% of Hg2+-resistant bacterial strains representing two freshwater communities, but in only 12% of strains representing two saline communities (the difference was highly significant; P less than 0.001). Thus, mer(Tn21) played a significant role in Hg2+ resistance among strains isolated from fresh waters, in which microbial activity had a limited role in Hg2+ volatilization. In saline water environments in which microbially mediated volatilization was the major mechanism of Hg2+ loss, other bacterial genes coded for this biotransformation.
Viability of Giardia cysts suspended in lake, river, and tap water
Authors: deRegnier D P , Cole L , Schupp D G , Erlandsen S L
Published: January 2020

Numerous waterborne outbreaks of giardiasis have occurred since 1965, yet little or no information has been reported on the viability of Giardia cysts in different aquatic environments. We have studied the viability of Giardia muris cysts suspended in lake, river, and tap water, while also monitoring water temperature, dissolved oxygen, pH, and other water quality parameters. Fecal pellets containing G. muris cysts were placed in glass vials covered with filter paper and exposed to (i) lake water at 15 ft (ca. 4.6 m) and 30 ft (ca. 9.2 m), (ii) river water, (iii) tap water, and (iv) distilled water stored under laboratory conditions. At 3, 7, 14, 28, 56, and 84 days, two vials from each environment were removed, and cyst viability was determined by (i) fluorogenic dye exclusion, (ii) production of giardiasis in an animal, and (iii) cyst morphology by Nomarski microscopy. In the fall, the cysts suspended at 30 ft in lake water remained viable for up to 56 days whereas cysts stored at 15 ft were nonviable after day 28. The G. muris cysts exposed to river water remained viable up to 28 days as determined by the production of giardiasis in mice. G. muris cysts suspended in tap water showed no signs of viability after 14 days, while cysts serving as controls (exposed to refrigerated distilled water) remained viable for up to 56 days. In the winter, Giardia cysts suspended in either lake or river water were viable for 56 to 84 days whereas cysts exposed to tap water were nonviable by day 14.(ABSTRACT TRUNCATED AT 250 WORDS)
Temperature Compensation in
Methanosarcina barkeri
by Modulation of Hydrogen and Acetate Affinity
Authors: Westermann Peter , Ahring Birgitte K. , Mah Robert A.
Published: January 2020

The affinity of
Methanosarcina barkeri
227 for acetate and hydrogen at different incubation temperatures was investigated. Increasing the temperature from 20 to 37�C resulted in a 4.5-fold increase in

K
m

for acetate and a 4.8-fold increase for hydrogen. The corresponding increase in
V
max
for acetate was 8.3-fold (5.4-fold for hydrogen). This response implied a decrease in the temperature coefficient (Q
10
) and hence a decrease in the temperature dependency as a function of decreasing substrate concentration.
Characteristics and restriction analysis of the 4-chlorobiphenyl catabolic plasmid, pSS50
Authors: Hooper S W , Dockendorff T C , Sayler G S
Published: January 2020

The plasmid pSS50 is a 53-kilobase self-transmissible plasmid of broad host range that has been isolated from several Alcaligenes and Acinetobacter species. This plasmid has previously been shown to mediate the mineralization of 4-chlorobiphenyl to carbon dioxide and water. Physical characterization of this plasmid by restriction analysis indicates that most hexanucleotide cleavage sites are clustered in a 5-kilobase region, leaving large regions without restriction sites. The paucity of restriction sites is not due to DNA methylation.
Growth rate control of adherent bacterial populations
Authors: Gilbert P , Allison D G , Evans D J , Handley P S , Brown M R
Published: January 2020

We report a novel in vitro method which, through application of appropriate nutrient limitations, enables growth rate control of adherent bacterial populations. Exponentially growing cells are collected by pressure filtration onto cellulose acetate membranes. Following inversion into the bases of modified fermentors, membranes and bacteria are perfused with fresh medium. Newly formed and loosely attached cells are eluted with spent medium. Steady-state conditions (dependent upon the medium flow rate) at which the adherent bacterial biomass is constant and proportional to the limiting nutrient concentrations are rapidly achieved, and within limits, the growth rate is proportional to the medium flow rate. Scanning electron microscopic studies showed that such populations consist of individual cells embedded within an extracellular polymer matrix.
Variation in Deoxynivalenol, 15-Acetyldeoxynivalenol, 3-Acetyldeoxynivalenol, and Zearalenone Production by
Fusarium graminearum
Isolates
Authors: Mirocha C. J. , Abbas H. K. , Windels C. E. , Xie W.
Published: January 2020

Of 88 isolates of
Fusarium graminearum
collected from soil or cereals in the United States, 49 produced 15-acetyldeoxynivalenol (15-ADON) as the major isomer; one produced 3-acetyldeoxynivalenol (3-ADON). A total of 26 isolates collected from cereals or soil in Australia, New Zealand, Norway, China, and Poland were used for comparison. Of these, 15 produced 3-ADON as the major isomer and 2 produced 15-ADON.
Effects of nisin on growth of bacteria attached to meat
Authors: Chung K T , Dickson J S , Crouse J D
Published: January 2020

Nisin had an inhibitory effect on gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, and Streptococcus lactis) but did not have an inhibitory effect on gram-negative bacteria (Serratia marcescens, Salmonella typhimurium, and Pseudomonas aeruginosa) attached to meat. Nisin delayed bacterial growth on meats which were artificially inoculated with L. monocytogenes or Staphylococcus aureus for at least 1 day at room temperature. If the incubation temperature was 5 degrees C, growth of L. monocytogenes was delayed for more than 2 weeks, and growth of Staphylococcus aureus did not occur. We also found that the extractable activity of nisin decreased rapidly when the meats were incubated at ambient temperatures and that this decrease was inversely related to the observed inhibitory effect. These findings disclosed that nisin delays the growth of some gram-positive bacteria attached to meat. However, nisin alone may not be sufficient to prevent meat spoilage because of the presence of gram-negative and other nisin-resistant gram-positive bacteria.
Hyperproduction of Poly-β-Hydroxybutyrate during Exponential Growth of
Azotobacter vinelandii
UWD
Authors: Page William J. , Knosp Olga
Published: January 2020

The transformation of
Azotobacter vinelandii
UW with
A. vinelandii
113 DNA resulted in the formation of rifampin-resistant colonies, 13% of which also inherited a previously unrecognized mutation in the respiratory NADH oxidase. These transformants produced colonies with a white-sectored phenotype after prolonged incubation. Cells from these sectors were separated and purified by streaking and were named UWD. The dense white phenotype was due to the production of a large amount of poly-β-hydroxybutyrate during the exponential growth of strain UWD. The polymer accounted for 65 or 75% of the cell dry weight after 24 h of incubation of cultures containing glucose and either ammonium acetate or N
2
, respectively, as the nitrogen source. Under the same conditions, strain UW cells contained 22 to 25% poly-β-hydroxybutyrate, but O
2
-limited growth was required for these optimal production values. Polymer production was not dependent on O
2
limitation in strain UWD, but the efficiency of conversion of glucose to poly-β-hydroxybutyrate was enhanced in O
2
-limited cultures. Conversion efficiencies were >0.25 and 0.33 mg of poly-β-hydroxybutyrate per mg of glucose consumed under vigorous- and low-aeration conditions, respectively, compared with an efficiency of 0.05 achieved by strain UW. Strain UWD, therefore, appeared to from poly-β-hydroxybutyrate under novel conditions, which may be useful in designing new methods for the industrial production of biodegradable plastics.
Effect of Surface-Active
Pseudomonas
spp. on Leaf Wettability
Authors: Bunster Lillian , Fokkema Nyckle J. , Schippers Bob
Published: January 2020

Different strains of
Pseudomonas putida
and
P. fluorescens
isolated from the rhizosphere and phyllosphere were tested for surface activity in droplet cultures on polystyrene. Droplets of 6 of the 12 wild types tested spread over the surface during incubation, and these strains were considered surface active; strains not showing this reaction were considered non-surface active. Similar reactions were observed on pieces of wheat leaves. Supernatants from centrifuged broth cultures behaved like droplets of suspensions in broth; exposure to 100°C destroyed the activity. Average contact angles of the supernatants of surface-active and non-surface-active strains on polystyrene were 24° and 72°, respectively. The minimal surface tension of supernatants of the surface-active strains was about 46 mN/m, whereas that of the non-surface-active strains was 64 mN/m (estimations from Zisman plots). After 6 days of incubation, wheat flag leaves sprayed with a dilute suspension of a surface-active strain of
P. putida
(WCS 358RR) showed a significant increase in leaf wettability, which was determined by contact angle measurements. Increasing the initial concentration of bacteria and the amount of nutrients in the inoculum sprayed on leaves reduced the contact angles from 138° on leaves treated with antibiotics (control) to 43° on leaves treated with surface-active bacteria. A closely related strain with no surface activity on polystyrene did not affect leaf wettability, although it was present in densities similar to those of the surface-active strain. Nutrients alone could occasionally also increase leaf wettability, apparently by stimulating naturally occurring surface-active bacteria. When estimating densities of
Pseudomonas
spp. underneath droplets with low contact angles, it appeared that populations on leaves treated with a surface-active strain could vary from about 10
4
to 10
6
CFU cm
−2
, suggesting that the surface effect may be prolonged after a decline of the population. The possible ecological implications are discussed.
Biodegradation of Asphalt Cement-20 by Aerobic Bacteria
Authors: Pendrys John P.
Published: January 2020

Seven gram-negative, aerobic bacteria were isolated from a mixed culture enriched for asphalt-degrading bacteria. The predominant genera of these isolates were
Pseudomonas, Acinetobacter, Alcaligenes, Flavimonas
, and
Flavobacterium
. The mixed culture preferentially degraded the saturate and naphthene aromatic fractions of asphalt cement-20. A residue remained on the surface which was resistant to biodegradation and protected the underlying asphalt from biodegradation. The most potent asphalt-degrading bacterium,
Acinetobacter calcoaceticus
NAV2, excretes an emulsifier which is capable of emulsifying the saturate and naphthene aromatic fractions of asphalt cement-20. This emulsifier is not denatured by phenol.
Protection of rainbow trout against vibriosis and furunculosis by the use of attenuated strains of Vibrio anguillarum
Authors: Norqvist A , Hagström A , Wolf-Watz H
Published: January 2020

The fish pathogen Vibrio anguillarum causes a lethal infection in rainbow trout (Salmo gairdneri). Three different avirulent mutants, constructed by transposon insertion mutagenesis (VAN20 and VAN70) or as antibiotic-resistant mutants (VAN1000), were isolated by screening 200 individual isolated mutants for avirulence. When used as live vaccines, all three avirulent mutants were able to induce protective immunity against the homologous as well as a heterologous strain of V. anguillarum. When VAN1000 was used, protective immunity could be recorded 1 week after bath vaccination with 10(7) bacteria per ml of water for 30 min. A single-dose immunization was effective for at least 12 weeks. Western immunoblotting showed that strains of V. anguillarum have antigenic determinants in common with Aeromonas strains. Therefore, we tested and confirmed that VAN1000 also was able to induce protective immunity against challenge with Aeromonas salmonicida.
Detection of Lignin Peroxidase and Xylanase by Immunocytochemical Labeling in Wood Decayed by Basidiomycetes
Authors: Blanchette R. A. , Abad A. R. , Farrell R. L. , Leathers T. D.
Published: January 2020

The white rot fungi used in this study caused two different forms of degradation.
Phanerochaete chrysosporium
, strain BKM-F-1767, and
Phellinus pini
caused a preferential removal of lignin from birch wood, whereas
Trametes
(
Coriolus
)
versicolor
caused a nonselective attack of all cell wall components. Use of polyclonal antisera to H8 lignin peroxidase and monoclonal antisera to H2 lignin peroxidase followed by immunogold labeling with protein A-gold or protein G-gold, respectively, showed lignin peroxidase extra-and intracellularly to fungal hyphae and within the delignified cell walls after 12 weeks of laboratory decay. Lignin peroxidase was localized at sites within the cell wall where electron-dense areas of the lignified cell wall layers remained. In wood decayed by
Trametes versicolor
, lignin peroxidase was located primarily along the surface of eroded cell walls. No lignin peroxidase was evident in brown-rotted wood, but slight labeling occurred within hyphal cells. Use of polyclonal antisera to xylanase followed by immunogold labeling showed intense labeling on fungal hyphae and surrounding slime layers and within the woody cell wall, where evidence of degradation was apparent. Colloidal-gold-labeled xylanase was prevalent in wood decayed by all fungi used in this study. Areas of the wood with early stages of cell wall decay had the greatest concentration of gold particles, while little labeling occurred in cells in advanced stages of decay by brown or white rot fungi.
Characterization of Anaerobic Dechlorinating Consortia Derived from Aquatic Sediments
Authors: Genthner Barbara R. Sharak , Price W. Allen , Pritchard P. H.
Published: January 2020

Four methanogenic consortia which degraded 2-chlorophenol, 3-chlorophenol, 2-chlorobenzoate, and 3-chlorobenzoate, respectively, and one nitrate-reducing consortium which degraded 3-chlorobenzoate were characterized. Degradative activity in these consortia was maintained by laboratory transfer for over 2 years. In the methanogenic consortia, the aromatic ring was dechlorinated before mineralization to methane and carbon dioxide. After dechlorination, the chlorophenol consortia converted phenol to benzoate before mineralization. All methanogenic consortia degraded both phenol and benzoate. The 3-chlorophenol and 3-chlorobenzoate consortia also degraded 2-chlorophenol. No other cross-acclimation to monochlorophenols or monochlorobenzoates was detected in the methanogenic consortia. The consortium which required nitrate for the degradation of 3-chlorobenzoate degraded benzoate and 4-chlorobenzoate anaerobically in the presence of KNO
3
, but not in its absence. This consortium also degraded benzoate, but not 3-chlorobenzoate, aerobically.
Genetically Engineered
Erwinia carotovora
in Aquatic Microcosms: Survival and Effects on Functional Groups of Indigenous Bacteria
Authors: Scanferlato Vjera S. , Orvos David R. , Cairns John , Lacy George H.
Published: January 2020

The survival of genetically engineered
Erwinia carotovora
L-864, with a kanamycin resistance gene inserted in its chromosome, was monitored in the water and sediment of aquatic microcosms. The density of genetically engineered and wild-type
E. carotovora
strains declined at the same rate, falling in 32 days below the level of detection by viable counts. We examined the impact of the addition of genetically engineered and wild-type strains on indigenous bacteria belonging to specific functional groups important in nutrient cycling. For up to 16 days, the densities of total and proteolytic bacteria were significantly higher (
P
< 0.05) in microcosms inoculated with genetically engineered or wild-type
E. carotovora
, but by 32 days after inoculation, they had decreased to densities similar to those in control microcosms. Inoculation of genetically engineered or wild-type
E. carotovora
had no apparent effect on the density of amylolytic and pectolytic bacteria in water and sediment. Genetically engineered and wild-type
E. carotovora
did not have significantly different effects on the densities of specific functional groups of indigenous bacteria (
P
> 0.05).
Principal-Component Analysis of the Characteristics Desirable in Baker's Yeasts
Authors: Oda Yuji , Ouchi Kozo
Published: January 2020

Twenty-seven properties considered to be required for good bakery products were examined in 56 industrial and 2 laboratory yeast strains. The data obtained were applied to principal-component analysis, one of the multivariate statistical analyses. The first and second principal components together were extracted, and these accounted for 77.7% of the variance. The first principal component was interpreted as the glycolytic activity of yeast in dough, and the second one was interpreted as the balance of leavening abilities in sweet and flour doughs from the factor loadings. The scattergram on the two principal components was effective in grouping the 58 yeast strains used.
New method to study bacterial adhesion to meat
Authors: Piette J P , Idziak E S
Published: January 2020

A new method was developed for the study of bacterial adhesion to meat surfaces. Thin slices of meat (40 microns thick) were inserted into a specially designed observation chamber. The meat slices were then exposed to a bacterial suspension (ca. 10(6) CFU.ml-1) to initiate adhesion (20 min of contact time) and subsequently rinsed to eliminate nonadherent bacteria. Because of the special chamber design, the disruptive force exerted on the bacteria during rinsing (shear stress) was uniform over the whole surface of the meat slices, was constant, and could be varied from 0 to 0.08 N.m-2. After being rinsed, the meat slices were stained with basic fuschin and observed under light microscopy to determine the number and distribution of adherent bacteria. This new method was used to study the adhesion of Acinetobacter strain LD2, a Lactobacillus sp., and Pseudomonas fluorescens to slices of beef fat and tendon. At 25 degrees C, most (greater than or equal to 99.9%) of the cells of the Lactobacillus sp. deposited on the meat were washed off the surface during rinsing (0.05 N.m-2), whereas a large number (ca. 10(5) CFU.cm-2) of Acinetobacter strain LD2 and P. fluorescens cells remained adherent. The extent of adhesion was similar on fat and tendon, and adherent bacteria were distributed evenly over the whole surface of the slices. This preliminary study indicates that the combined use of thin slices of meat and of the observation chamber provides us with the means to more accurately study bacterial adhesion to meat surfaces.
Resistance against Industrial Bacteriophages Conferred on Lactococci by Plasmid pAJ1106 and Related Plasmids
Authors: Jarvis Audrey W. , Heap Howard A. , Limsowtin Gaetan K. Y.
Published: January 2020

Plasmid pAJ1106 and its deletion derivative, plasmid pAJ2074, conferred lactose-fermenting ability (Lac) and bacteriophage resistance (Hsp) at 30°C to Lac
−
proteinase (Prt)-negative
Lactococcus lactis
subsp.
lactis
and
L. lactis
subsp.
lactis
var.
diacetylactis
recipient strains. An additional plasmid, pAJ331, isolated from the original source strain of pAJ1106, retained Hsp and conjugative ability without Lac. pAJ331 was conjugally transferred to two
L. lactis
subsp.
lactis
and one
L. lactis
subsp.
cremoris
starter strains. The transconjugants from such crosses acquired resistance to the phages which propagated on the parent recipient strains. Of 10 transconjugant strains carrying pAJ1106 or one of the related plasmids, 8 remained insensitive to phages through five activity test cycles in which cultures were exposed to a large number of industrial phages at incubation temperatures used in lactic casein manufacture. Three of ten strains remained phage insensitive through five cycles of a cheesemaking activity test in which cultures were exposed to approximately 80 different phages through cheesemaking temperatures. Three phages which propagated on transconjugant strains during cheesemaking activity tests were studied in detail. Two were similar (prolate) in morphology and by DNA homology to phages which were shown to be sensitive to the plasmid-encoded phage resistance mechanism. The third phage was a long-tailed, small isometric phage of a type rarely found in New Zealand cheese wheys. The phage resistance mechanism was partially inactivated in most strains at 37°C.
β-Glucose-1-Phosphate, a Possible Mediator for Polysaccharide Formation in Maltose-Assimilating
Lactococcus lactis
Authors: Sjöberg Annelie , Hahn-Hägerdal Bärbel
Published: January 2020

Homolactic fermentation of glucose and heterolactic fermentation of maltose with
Lactococcus lactis
65.1 were confirmed. When moles of glucose were compared, the uptake rates of the two carbon sources were similar. The intracellular concentration of fructose-1,6-diphosphate (FDP) in maltose-assimilating cells was half of that in glucose-assimilating cells. Similarly, formation of FDP and lactate from maltose by extracts of maltose-grown cells was half of that formed from glucose by extracts of glucose-grown cells, indicating a difference in the utilization of the two carbon sources for energy metabolism. Concentrations of adenine nucleotides were similar in both types of cells. Glucose-1-phosphate was found in extracts of maltose-grown cells given maltose and, in addition, an inducible and low β-specific phosphoglucomutase activity was observed. β-Glucose-1-phosphate was not metabolized by cell extracts to either FDP or lactate, suggesting an alternative metabolic route. The amount of [
14
C]maltose incorporated into the cell material of maltose-grown cells was four times greater than that of [
14
C]glucose incorporated into the cell material of glucose-grown cells. The intracellular concentration of UTP was lower in maltose-assimilating cells than in glucose-assimilating cells. Cells grown on maltose were more spherical and less fragile than cells grown on glucose.
Experimental Tests of Nutrient Limitation in Freshwater Picoplankton
Authors: Wehr John D.
Published: January 2020

On the basis of correlative studies, picoplankton in Calder Lake, New York, are apparently unaffected by seasonal fluxes in nutrient (N and P) levels. In this small eutrophic lake, picoplankton (<2.0- to 0.2-μm size) and nanoplankton (<20 to >2 μm) predominate. Microplankton (>20 μm) are typically least important. Experiments were conducted in situ to test whether N, P or N/P ratios affect the predominance of these smaller organisms. Manipulations were run in 4-liter microcosms during June, July, and August 1988, corresponding to periods of increasing stratification and nutrient depletion. Following nutrient additions, phytoplankton were harvested and fractionated into three size classes. Microplankton and nanoplankton were significantly stimulated by both N (2.5 to 50 μM) and P (1 to 20 μM) additions. The severity of nutrient limitation was greatest during July. Picoplankton responded less strongly to N additions and were never P limited. These field data support laboratory studies which indicate that bacterium-sized phytoplankton use nutrients more efficiently and are superior competitors within mixed communities.
Changes in Cytoplasmic Carbon and Nitrogen Pools in a Soil Bacterium and a Fungus in Response to Salt Stress
Authors: Schimel Joshua P. , Scott Warren J. , Killham Kenneth
Published: January 2020

The effects of water potential on the cellular compositions of a soil bacterium and a fungus were examined by growing the organisms in media with various KCl concentrations. In media containing up to 1 M KCl, C/N ratios in
Aspergillus flavus
increased significantly, while those for a
Pseudomonas
sp. did not. For both organisms, the proportions of cellular C and N in cytoplasm increased by a factor of 10 as salinity increased from 0 to 1 M KCl. Such compositional changes have implications for microbial biomass dynamics in soils of varying water potential and for biomass measurement by chloroform fumigation.
Evaluation of three newly developed direct plating media to enumerate Listeria monocytogenes in foods
Authors: Cassiday P K , Brackett R E , Beuchat L R
Published: January 2020

LiCl-phenylethanol-moxalactam Agar (LPMA), ARS Modified McBride Agar, and Modified Vogel Johnson Agar were compared with previously tested plating media in the enumeration of Listeria monocytogenes from pasteurized whole milk, chocolate ice cream mix, Brie cheese, and raw cabbage. LPMA was most suitable for analyzing Brie cheese and cabbage. Gum base-nalidixic acid-tryptone-soya medium (previously tested) was most suitable for analyzing milk and chocolate ice cream mix.
Production of vanillic acid from vanillin by resting cells of Serratia marcescens
Authors: Perestelo F , Dalcón M A , de la Fuente G
Published: January 2020

Resting-cell suspensions of Serratia marcescens were able to convert, quantitatively, 0.3% vanillin to vanillic acid. The vanillic acid-producing activity reached a maximum after 28 h of incubation with 0.01% vanillin as an inducer.
Influence of soil variables on in situ plasmid transfer from Escherichia coli to Rhizobium fredii
Authors: Richaume A , Angle J S , Sadowsky M J
Published: January 2020

A model system was established to determine whether intergeneric plasmid transfer occurs in soil and how various soil variables affect the rate of plasmid transfer. The donor bacterium, Escherichia coli HB101 carrying plasmid pBLK1-2 (pRK2073::Tn5), and the recipient bacterium, Rhizobium fredii USDA 201, were inoculated into a sterile Adelphia fine-sandy-loam soil. Transconjugants were enumerated by direct plating on antibiotic-amended HM [N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid; 2-(N-morpholino) ethanesulfonic acid] salts medium. Randomly chosen transconjugants were verified by serological typing and Southern hybridization with a Tn5 gene probe. The maximum transfer frequency was observed after 5 days of incubation (1.8 x 10(-4) per recipient). The influences of clay (0 to 50% addition), organic matter (0 to 15% addition), soil pH (4.3 to 7.25), soil moisture (2 to 40%), and soil incubation temperature (5 to 40 degrees C) on plasmid transfer were examined. Maximum transfer frequencies were noted at a clay addition of 15%, an organic matter addition of 5%, a soil pH of 7.25, a soil moisture content of 8%, and a soil incubation temperature of 28 degrees C. These results indicate that intergeneric plasmid transfer may occur in soil and that soil variables may significantly affect the rate of transfer.
Genetic Analysis of Haploids from Industrial Strains of Baker's Yeast
Authors: Oda Yuji , Ouchi Kozo
Published: January 2020

Strains of baker's yeast conventionally used by the baking industry in Japan were tested for the ability to sporulate and produce viable haploid spores. Three isolates which possessed the properties of baker's yeasts were obtained from single spores. Each strain was a haploid, and one of these strains, YOY34, was characterized. YOY34 fermented maltose and sucrose, but did not utilize galactose, unlike its parental strain. Genetic analysis showed that YOY34 carried two
MAL
genes, one functional and one cryptic; two
SUC
genes; and one defective
gal
gene. The genotype of YOY34 was identified as
MAT
α
MAL1 MAL3g SUC2 SUC4 gall.
The
MAL1
gene from this haploid was constitutively expressed, was dominant over other wild-type
MAL
tester genes, and gave a weak sucrose fermentation. YOY34 was suitable for both bakery products, like conventional baker's yeasts, and for genetic analysis, like laboratory strains.
15
N
2
Fixation by Bacteria Associated with Maize Roots at a Low Partial O
2
Pressure
Authors: Alexander David B. , Zuberer David A.
Published: January 2020

Nitrogen fixation by bacteria associated with roots of intact maize plants was measured by exposing the roots to
15
N
2
at a partial O
2
pressure (pO
2
) of 2 or 10 kPa. The plants were grown in a mixture of Weswood soil and sand and then transferred to plastic cylinders containing an N-free plant nutrient solution. The solution was sparged continuously with a mixture of air and N
2
at a pO
2
of 2 or 10 kPa. Acetylene reduction was measured after the roots were exposed to the low pO
2
overnight. The air-N
2
atmosphere in the cylinders was then replaced with an O
2
-He atmosphere at the same pO
2
, and the roots were exposed to 20 kPa of
15
N
2
for 20 to 22 h. Incorporation of
15
N into the roots was 200 times greater at 2 kPa of O
2
than at 10 kPa of O
2
. Adding
l
-malate (1 g of C liter
−1
) to the nutrient solution increased root-associated nitrogenase activity, producing a strong
15
N label which could be traced into the shoots. Fixed
15
N was detected in the shoots within 5 days after the plants were returned to unfertilized soil. In a similar experiment with undisturbed plants grown in fritted clay, movement of fixed
15
N into the shoots was evident within 4 days after the roots were exposed to
15
N
2
at 2 kPa of O
2
. Inoculation with
Azospirillum lipoferum
yielded no significant differences in shoot dry weight, total nitrogen content, percent nitrogen, or
15
N enrichment of plant tissues. Inoculated plants did exhibit greater root dry weight than uninoculated plants, however.
Insertion and amplification of foreign genes in the Lactococcus lactis subsp. lactis chromosome
Authors: Chopin M C , Chopin A , Rouault A , Galleron N
Published: January 2020

The plasmid pE194 is unable to replicate in Lactococcus lactis subsp. lactis (formerly Streptococcus lactis). When linked to resident bacteriophage sequences, pE194 was able to integrate into the L. lactis subsp. lactis chromosome either by Campbell-like recombination or by double crossing over with deletion. Integration occurred into the DNA of the prophage and prevented its multiplication. When a selective pressure was applied to an integrant in which pE194 was flanked by two direct repeats of prophage fragment, amplification of pE194 and the prophage fragment was observed. The pE194 copy number was assessed at six to nine, and amplification was stable upon growth under nonselective conditions.
Catechol Formation and Melanization by Na
+
-Dependent
Azotobacter chroococcum
: a Protective Mechanism for Aeroadaptation?
Authors: Shivprasad Shailaja , Page William J.
Published: January 2020

Aeroadaptive microaerophilic
Azotobacter chroococcum
184 produced a cell-associated black pigment when grown at high aeration rates under nitrogen-fixing conditions. This pigment was shown to be a catechol melanin. Polyphenol oxidase activity was detected in cell extracts of cells grown for 72 h. Melanin formation was optimal in the later stages of growth, and there was no correlation between nitrogenase activity and melanization. Nitrogenase activity in strain 184 was optimal at 10% O
2
, and melanin formation was suppressed by O
2
limitation. In the presence of charcoal, an adsorbent of toxic oxygen intermediates, and benzoic acid, a scavenger of hydroxyl radicals, melanization was inhibited. However, in the presence of copper, the intensity of pigment color increased and melanization was accelerated. Copper also eliminated catalase and peroxidase activities of the organism but still permitted aerobic growth. In the presence of low levels of iron, melanization was accelerated under high aeration rates, and under low rates of aeration, melanization was observed only at higher levels of iron. Hydroxamate-siderophore production was detectable in the presence of soluble iron under high rates of aeration but was repressed by the same levels of iron under low aeration rates. Unlike melanization and hydroxamate formation, catechol formation was observed under both low and high rates of aeration under nitrogen-fixing conditions. Catechol formation and melanization were repressed by 14 mM NH
4
+
, at which level nitrogenase activity was also repressed. Copper reversed the repressive effect of NH
4
+
. A role for catechol formation and melanization in aeroadaptation is proposed.
Molybdenum Involvement in Aerobic Degradation of 2-Furoic Acid by
Pseudomonas putida
Fu1
Authors: Koenig Kerstin , Andreesen Jan Remmer
Published: January 2020

An organism identified as
Pseudomonas putida
was isolated from an enrichment culture with 2-furoic acid as its sole source of carbon and energy. The organism contained a 2-furoyl-coenzyme A (CoA) synthetase to form 2-furoyl-CoA and a 2-furoyl-CoA dehydrogenase to form 5-hydroxy-2-furoyl-CoA as the first two enzymes involved in the degradation. Tungstate, the specific antagonist of molybdate, decreased growth rate and consumption of 2-furoic acid but had no influence on growth with succinate. Correspondingly, the 2-furoyl-CoA dehydrogenase activity decreased when the organism was grown on 2-furoic acid in the presence of increasing amounts of tungstate. The addition of molybdate reversed the negative effect on 2-furoyl-CoA dehydrogenase activity, which points to the involvement of a molybdoenzyme in this reaction. Both enzymes studied were inducible. No plasmid was detected in this organism.
Lactobacilli and bile salt hydrolase in the murine intestinal tract
Authors: Tannock G W , Dashkevicz M P , Feighner S D
Published: January 2020

Mice that have a complex intestinal microflora but that do not harbor lactobacilli were used to determine the contribution of lactobacilli to the total bile salt hydrolase activity in the murine intestinal tract. Bile salt hydrolase activity in the ileal contents of these mice was reduced 86% in the absence of lactobacilli and by greater than 98% in the absence of lactobacilli and enterococci compared with samples from conventional mice. Bile salt hydrolase activities were lower in ileal and cecal contents from lactobacillus-free mice colonized with enterococci than in samples from lactobacillus-free mice colonized with lactobacilli. Bile salt hydrolase activity in the duodena, jejuna, ilea, and ceca of reconstituted lactobacillus-free mice colonized by lactobacilli was similar to that in samples from the intestinal tracts of conventional mice. We conclude from these studies that lactobacilli are the main contributors to total bile salt hydrolase activity in the murine intestinal tract.
Lyme disease and migrating birds in the Saint Croix River Valley
Authors: Weisbrod A R , Johnson R C
Published: January 2020

During a study of migrating land birds in 1987, we examined over 9,200 individual birds representing 99 species from the Saint Croix River Valley, a Lyme disease-endemic area of east central Minnesota and northwestern Wisconsin. We found that 250 deer tick (Ixodes dammini) larvae and nymphs infested 58 birds from 15 migrant species; 56 ticks (22.4%) were positive for the Lyme disease spirochete Borrelia burgdorferi. Five ground-foraging migrant bird species favoring mesic habitats, veery (Catharus fuscescens), ovenbird (Seiurus aurocapillus), northern waterthrush (S. novaboracensis), common yellowthroat (Geothlypis trichas), and swamp sparrow (Melospiza georgiana), accounted for nearly three-quarters of parasitized individuals. Nearly half of the spirochete-positive ticks were removed from migrating birds taken in a riparian floodplain forest. Recaptured migrants with infected ticks indicate that they transmit B. burgdorferi to hexapod larvae. We suggest that birds may be both an important local reservoir in the upper Mississippi Valley and long-distance dispersal agents for B. burgdorferi-infected ticks to other regions of the continent.