bluuebunny/crossref_metadata_2025 huggingface dataset:
Subtherapeutic levels of antibiotics in poultry feeds and their effects on weight gain, feed efficiency, and bacterial cholyltaurine hydrolase activity
Authors: Feighner S D , Dashkevicz M P
Published: January 2020

A radiochemical method was developed to estimate cholyltaurine hydrolase potentials and rates of cholyltaurine hydrolysis in chicken intestinal homogenates. This method was used to monitor the effects of antibiotic feed additives on cholyltaurine hydrolase activity. Avoparcin, bacitracin methylenedisalisylic acid, efrotomycin, lincomycin, penicillin G procaine, and virginiamycin improved rate of weight gain and feed conversion of chicks and decreased cholyltaurine hydrolase activity in ileal homogenates relative to those of nonmedicated control birds. The results provided the first evidence that feeding selected antibiotics at subtherapeutic levels can affect bile acid-transforming enzymes in small-intestinal homogenates. The inverse relationship between growth performance and cholyltaurine hydrolase activity raises the possibility that specific inhibitors of this enzyme may promote weight gain and feed conversion in livestock and thereby reduce or eliminate the need for antibiotic feed additives.
Enzyme-Linked Immunosorbent Assay for Specific Identification and Enumeration of
Azospirillum brasilense
Cd. in Cereal Roots
Authors: Levanony Hanna , Bashan Yoav , Kahana Zvi E.
Published: January 2020

The enzyme-linked immunosorbent assay is suggested as a reliable, sensitive, and highly specific method for the identification and enumeration of
Azospirillum brasilense
Cd. As few as 10
5
CFU/ml can be practically identified by this method. At higher bacterial numbers, sensitivity increased linearly up to 5 × 10
8
CFU/ml, yielding useful standard curves. No cross-reaction was found either with different closely related
Azospirillum
strains or with other rhizosphere bacteria. The method allows for a specific identification of
A. brasilense
Cd. both in pure cultures and in mixtures with other bacterial species, even when the colony morphology is variable. The method was successfully applied to assess the degree of root colonization on various cereals by
A. brasilense
Cd.
Flowthrough Reactor Flasks for Study of Microbial Metabolism in Sediments
Authors: Smith Richard L. , Klug Michael J.
Published: January 2020

Flowthrough reactor flasks are described that allow continuous low-level nutrient input to mixed anoxic sediments without dilution of the sediment. The flasks were tested by simulating sulfate inputs into sediments collected from a freshwater eutrophic lake. After an initial 2-day adaptation within the reactor system, rates of methane production and sulfate consumption were constant for the duration of a 12-day incubation. A sulfate input rate of 0.15 mmol liter of sediment
−1
day
−1
resulted in an equivalent rate of sulfate removal, which was unaffected by inputs of acetate (1.0 mmol liter of sediment
−1
day
−1
). The rate of methane production in control reactors, 0.18 mmol liter of sediment
−1
day
−1
, was doubled by the addition of acetate, whereas sulfate consumption was only stimulated by additions of high concentrations of sulfate plus acetate (1.5 and 1.0 mmol liter of sediment
−1
day
−1
, respectively). The reactor system appears to be effective in maintaining the balance between sulfate reduction and methane production in freshwater sediments and is potentially useful for study of the response of sediment populations to varying inputs of naturally occurring substrates, selected inhibitors, or xenobiotic compounds.
Transposon Mutagenesis of
Azospirillum brasilense
and
Azospirillum lipoferum
: Physical Analysis of Tn
5
and Tn
5
-Mob Insertion Mutants
Authors: Vanstockem Mark , Michiels Kris , Vanderleyden Jos , Van Gool August P.
Published: January 2020

Tn
5
-induced insertion mutants were generated in
Azospirillum brasilense
Sp7 and
A. lipoferum
SpBr17 by mating with
Escherichia coli
strains carrying suicide plasmid vectors. The sources of Tn
5
were the suicide plasmids pGS9 and pSUP2021. Kanamycin-resistant
Azospirillum
colonies appeared from crosses with
E. coli
at maximum frequencies of 10
−7
per recipient cell. Transposon Tn
5
also conferred streptomycin resistance on
Azospirillum
colonies as was observed earlier for
Rhizobium
sp. Eight Tn
5
-induced Km
r
Sm
r
A. brasilense
Sp7 mutants with reduced nitrogen-fixing capacity were isolated. The potential use of Tn
5
-Mob for labeling and mobilization of
Azospirillum
-indigenous plasmids was demonstrated by isolating Tn
5
-Mob insertions in the megaplasmids of
A. brasilense
Sp7.
Kinetics of Butyrate, Acetate, and Hydrogen Metabolism in a Thermophilic, Anaerobic, Butyrate-Degrading Triculture
Authors: Ahring Birgitte K. , Westermann Peter
Published: January 2020

Kinetics of butyrate, acetate, and hydrogen metabolism were determined with butyrate-limited, chemostat-grown tricultures of a thermophilic butyrate-utilizing bacterium together with
Methanobacterium thermoautotrophicum
and the TAM organism, a thermophilic acetate-utilizing methanogenic rod. Kinetic parameters were determined from progress curves fitted to the integrated form of the Michaelis-Menten equation. The apparent half-saturation constants,

K
m

, for butyrate, acetate, and dissolved hydrogen were 76 μM, 0.4 mM, and 8.5 μM, respectively. Butyrate and hydrogen were metabolized to a concentration of less than 1 μM, whereas acetate uptake usually ceased at a concentration of 25 to 75 μM, indicating a threshold level for acetate uptake. No significant differences in

K
m

values for butyrate degradation were found between chemostat- and batch-grown tricultures, although the maximum growth rate was somewhat higher in the batch cultures in which the medium was supplemented with yeast extract. Acetate utilization was found to be the rate-limiting reaction for complete degradation of butyrate to methane and carbon dioxide in continuous culture. Increasing the dilution rate resulted in a gradual accumulation of acetate. The results explain the low concentrations of butyrate and hydrogen normally found during anaerobic digestion and the observation that acetate is the first volatile fatty acid to accumulate upon a decrease in retention time or increase in organic loading of a digestor.
Ethanol Perturbs Glycosylation and Inhibits Hypersecretion in
Trichoderma reesei
Authors: Merivuori Hannele , Montenecourt Bland S. , Sands Jeffrey A.
Published: January 2020

The effects of ethanol and phenylethanol on the growth of and glycoprotein secretion by
Trichoderma reesei
were studied. Low levels (1.5%, vol/vol) of ethanol perturbed the glycosylation process, as shown by alterations in the isoelectric profile of the secreted proteins and a reduction in the rate of incorporation of mannose into oligosaccharides. In addition to these effects on posttranslational modification, ethanol drastically lowered the protein secretion level of a hypersecretory strain.
Growth of
Azotobacter vinelandii
on Soil Nutrients
Authors: Wu Fang Jy , Moreno Joaquin , Vela G. R.
Published: January 2020

Azotobacter vinelandii
cells grew well in a medium made from soil and distilled water which contained little or no carbohydrate. They utilized
p
-hydroxybenzoic acid and other phenolic acids, soil nitrogen, and water-soluble mineral substances. Seventeen soils which supported excellent growth of
A. vinelandii
contained 11 to 18 different phenolic acids each, including
p
-hydroxybenzoic,
m
-hydroxybenzoic, vanillic,
p
-coumeric, syringic,
cis
- and
trans
-ferrulic, and other unidentified aromatic acids. Three white, chalky “caliche” soils which were taken from areas where no plants grew failed to support the growth of
A. vinelandii
, and these contained no, two, and three phenolic acids, respectively.
A. vinelandii
did not fix nitrogen when growing in dialysates of soils which contained numerous phenolic acids. Growth was ample and rapid in most of the soils tested, but cell morphology was different from that usually seen in chemically defined, nitrogen-free media which contain glucose.
One-Step Microbial Conversion of a Racemic Mixture of Pantoyl Lactone to Optically Active
d
-(—)-Pantoyl Lactone
Authors: Shimizu Sakayu , Hattori Shizuo , Hata Hiroyuki , Yamada Hideaki
Published: January 2020

Washed cells of
Rhodococcus erythropolis
IFO 12540 were found to convert only the
l
-(+)-isomer of pantoyl lactone to the
d
-(—)-isomer in a racemic mixture of pantoyl lactone. Under suitable reaction conditions, the amount of
d
-(—)-pantoyl lactone synthesized was 18.2 mg/ml (94.4% enantiomer excess; molar yield, 90.5%). This conversion was suggested to proceed through the following successive reactions: first, the enzymatic oxidation of
l
-(+)-pantoyl lactone to ketopantoyl lactone; second, the rapid and spontaneous hydrolysis of the ketopantoyl lactone to ketopantoic acid; and then, the enzymatic reduction of the ketopantoic acid to
d
-(—)-pantoic acid. After the reaction
d
-(—)-pantoic acid could be lactonized by means of acid treatment. During the conversion, the
d
-(—)-isomer, which was initially present in the reaction mixture, did not undergo any modification.
Effect of Oxygen on Lactose Metabolism in Lactic Streptococci
Authors: Smart John B. , Thomas Terence D.
Published: January 2020

Three strains of
Streptococcus lactis
, two of
Streptococcus cremoris
, and one of
Streptococcus thermophilus
metabolized oxygen in the presence of added carbohydrate primarily via a closely coupled NADH oxidase/NADH peroxidase system. No buildup of the toxic intermediate H
2
O
2
was detected with the three
S. lactis
strains. All six strains contained significant superoxide dismutase activity and are clearly aerotolerant. Lactose- or glucose-driven oxygen consumption was biphasic, with a rapid initial rate followed by a slower secondary rate which correlated with factors affecting the in vivo activation of lactate dehydrogenase. The rate of oxygen consumption was rapid under conditions that led to a reduction in lactate dehydrogenase activity (low intracellular fructose 1,6-bisphosphate concentration). These conditions could be achieved with nongrowing cells by adding lactose at a constant but limiting rate. When the rate of lactose fermentation was limited to 5% of its maximum, nongrowing cells of
S. lactis
strains ML3 and ML8 carried out an essentially homoacetic fermentation under aerobic conditions. These same cells carried out the expected homolactic fermentation when presented with excess lactose under anaerobic conditions. Homoacetic fermentation leads to the generation of more energy, by substrate-level phosphorylation via acetate kinase, than the homolactic fermentation. However, it was not observed in growing cells and was restricted to slow fermentation rates with nongrowing cells.
Intergeneric protoplast fusion between Fusobacterium varium and Enterococcus faecium for enhancing dehydrodivanillin degradation
Authors: Chen W , Ohmiya K , Shimizu S
Published: January 2020

Intergeneric protoplast fusion between Fusobacterium varium (Pcs Glu+) and Enterococcus faecium (Pcr Glu-) was performed under strictly anaerobic conditions to improve dehydrodivanillin (DDV) degradation. The fusion frequency obtained from the selective medium (Pc+ Glu-) was about 0.9 X 10(-5) to 1.3 X 10(-5). The seven fusants isolated were all gram-negative anaerobes with rod shapes like that of F. varium and with main phenotypical properties of cocci like those of E. faecium such as esculin and starch hydrolysis, milk clotting, and lactate production. Five fusants showed enhanced DDV degradation activities that were 2 to 4 times higher than those of parental strains. Genetic relatedness between a fusant (FE7) and the parents was estimated by DNA-DNA Southern blot hybridization with 32P-labeled chromosomal DNA fragments of F. varium and E. faecium as respective probes. The fusant FE7 presented a very high cross-hybridization with both probes, indicating a high DNA homology between the fusant and both parental strains. Almost all the fusants obtained here have stably kept the properties described above for about 2 years. These results suggest that intergeneric gene transfer takes place through protoplast fusion and that the fusants that were obtained are stable recombinants.
Conjugal Transfer of Plasmid-Encoded Determinants for Bacteriocin Production and Immunity in
Lactobacillus acidophilus
88
Authors: Muriana Peter M. , Klaenhammer Todd R.
Published: January 2020

Lactobacillus acidophilus
88 produced a bacteriocin, designated lactacin F, that demonstrated inhibitory activity toward
L. acidophilus
6032,
L. lactis
970,
L. helveticus
87,
L. bulgaricus
1489,
L. leichmanii
4797,
L. fermentum
1750, and
Streptococcus faecalis
19433. Production of lactacin F was pH dependent and could be maximized in MRS broth cultures maintained at pH 7.0. Lactacin F was heat stable and sensitive to ficin, proteinase K, trypsin, and
Bacillus subtilis
protease.
L. acidophilus
88 harbored plasmids of 4 and 27 megadaltons. Variants of
L. acidophilus
88 which were deficient in lactacin F production (Laf
+
) and lactacin F immunity (Laf

t

) retained the two resident plasmids. A Laf
−
Laf
s
derivative,
L. acidophilus
89, was used as a recipient in agar surface mating experiments with
L. acidophilus
88 (Laf
+
Laf

t

). Two types of Laf
+
Laf

t

transconjugants were recovered. One type (T-E) had acquired two plasmids of 68 (pPM68) and 52 (pPM52) megadaltons that were not detected in either the conjugal donor or the other type of Laf
+
Laf

t

transconjugants (T-89). Laf
+
and Laf

t

were unstable in the plasmid-bearing transconjugant. Plasmid analysis of Laf
−
Laf
s
variants revealed that pPM52 and pPM68 were cured with loss of Laf
+
and Laf

t

. Bacteriocin production and immunity phenotypes were genetically stable in Laf
+
Laf

t

transconjugants not harboring pPM52 and pPM68, suggesting chromosomal integration of the transferred determinants. The data demonstrated intragenic conjugation in
L. acidophilus
and provided direct evidence for involvement of transient plasmid determinants in Laf
+
and Laf

t

.

Images
Analysis of Yeast Flora Associated with Grape Sour Rot and of the Chemical Disease Markers
Authors: Guerzoni Elisabetta , Marchetti Rosa
Published: January 2020

The frequency and the density of the species associated with grape sour rot in different cultivars were determined. The most frequent species in the rotten grapes,
Candida krusei, Kloeckera apiculata
, and
Metschnikowia pulcherrima
, and a less frequent species,
Issatchenkia occidentalis
, when inoculated with
Saccharomycopsis crataegensis
were able to induce in vitro the symptoms of the disease. The gas chromatographic determination of the volatile compounds in the headspace was used to evaluate the metabolic role of the different species associated with the disease. These analyses made it possible to presume that, whereas some species, such as
Candida krusei
and
Hanseniaspora uvarum
, can be considered responsible for these modifications and in particular for the ethyl acetate production, others, such as
Saccharomycopsis crataegensis
, can promote the development of the former species.
Purification and Some Properties of a Membrane-Bound Aminopeptidase A from
Streptococcus cremoris
Authors: Exterkate Fred A. , de Veer Gerrie J. C. M.
Published: January 2020

A membrane-bound
l
-α-glutamyl (aspartyl)-peptide hydrolase (aminopeptidase A) (EC 3.4.11.7) from
Streptococcus cremoris
HP has been purified to homogeneity. The free γ-carboxyl group rather than the amino group of the N-terminal
l
-α-glutamyl (aspartyl) residue appeared to be essential for catalysis. No endopeptidase activity could be established with this enzyme. The native enzyme is a polymeric, most probably trimeric, metalloenzyme (relative molecular weight, approximately 130,000) which shows on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels apparent high relative molecular weight values due to (lipid?) material dissociable with butanol. The subunit (relative molecular weight, approximately 43,000) is catalytically inactive. The enzyme is inactivated completely by dithiothreitol, chelating agents, and the bivalent metal ions Cu
2+
and Hg
2+
. Of the sulfhydryl-blocking reagents tested, only
p
-hydroxymercuribenzoate appeared to inhibit the enzyme. Activity lost by treatment with a chelating agent could be restored by Co
2+
and Zn
2+
. The importance of the occurrence of an aminopeptidase A in
S. cremoris
with respect to growth in milk is discussed.
Influence of Soil and Nonsoil Environments on Nodulation by
Rhizobium trifolii
Authors: Demezas David H. , Bottomley Peter J.
Published: January 2020

Indigenous serotypes 1-01 and 2-02 of
Rhizobium trifolii
occupied similar percentages (18 to 23%) of root nodules on soil-grown subclover (
Trifolium subterraneum
L.) and were virtually absent (4.5%) from nodules of soil-grown white clover (
Trifolium repens
L.). In contrast (with the exception of one dilution [10
−4
]), serotype 1-01 occupied a substantial portion of nodules (16 to 40%) on white clover seedlings grown on mineral salts agar and exposed to samples of the same soil in the form of a 10-fold dilution series (10
−1
to 10
−5
). Under the latter conditions, occupancy of subclover nodules by 1-01 and of nodules of both plant species by 2-02 was consistent with the results obtained with soil-grown plants.
Survival of pathogenic bacteria in various freshwater sediments
Authors: Burton G A , Gunnison D , Lanza G R
Published: January 2020

Four human-associated bacteria, Pseudomonas aeruginosa, Salmonella newport, Escherichia coli, and Klebsiella pneumoniae, were tested for survival in five freshwater sediments. Bacterial survival in continuous-flow chambers was monitored over 14-day periods on sediments ranging from organically rich high-clay fractions to organically poor sandy fractions. Bacterial die-off ranged from 1 to 5 orders of magnitude in sediments. E. coli survived as long as or longer than S. newport. P. aeruginosa and K. pneumoniae tended to survive longer than E. coli. Survival of E. coli and S. newport was greater in sediments containing at least 25% clay. Good reproducibility allowed the development of linear models to describe die-off rates.
Production of 1,3-Propanediol from Glycerol by
Clostridium acetobutylicum
and Other
Clostridium
Species
Authors: Forsberg Cecil W.
Published: January 2020

Glycerol was fermented with the production of 1,3-propanediol as the major fermentation product by four strains of
Clostridium acetobutylicum
, six of
C. butylicum
, two of
C. beijerinckii
, one of
C. kainantoi
, and three of
C. butyricum
. 1,3-Propanediol was identified by its retention times in gas chromatography and high-pressure liquid chromatography and by its mass spectrum. During growth of
C. butylicum
B593 in a chemostat culture at pH 6.5, 61% of the glycerol fermented was converted to 1,3-propanediol. When the pH was decreased to 4.9, growth and 1,3-propanediol production were substantially reduced.
Population Heterogeneity of
Agrobacterium tumefaciens
in Galls of
Populus
L. from a Single Nursery
Authors: Nesme Xavier , Michel Marie-France , Digat Bernard
Published: January 2020

This study focused on the natural crown gall infections occurring in a
Leuce
poplar nursery. Soil effects on crown gall frequency were detected, indicating that contamination was due to a resident
Agrobacterium tumefaciens
population, which was present before seedling plantation. The crown gall frequency on poplar progenies varied from 3 to 67%, indicating the feasibility of improvement in crown gall resistance. Of 129 tumor isolates, 128 were pathogenic. These isolates were of biotype 1 or 2. Biochemical, serological, and antibiotic resistance typing results concurred, indicating the presence of four biotype 1 and two biotype 2 resident subpopulations. No significant change was noticed in the relative proportions of subpopulations from one year to another. Pathogenic subpopulations both in vitro and in planta were susceptible to Kerr K84 (P. B. New and A. Kerr, J. Appl. Bacteriol. 90:172-179, 1972). In addition, no serological cross-reactions were found to occur between K84 and the pathogenic subpopulations.
Identification of Cryptosporidium oocysts in river water
Authors: Ongerth J E , Stibbs H H
Published: January 2020

Water samples were collected from four rivers in Washington State and two rivers in California and examined for the presence of Cryptosporidium oocysts. Oocyst-sized particles were concentrated from 20-liter samples of water by membrane filtration, centrifugation, and differential sedimentation. The particle concentrate was then deposited on a 25-mm-diameter membrane filter for oocyst identification by indirect immunofluorescence assay. The identification procedure had a limit of detection of about five oocysts per liter. Cryptosporidium oocysts were found in each of 11 river water samples examined. Concentrations ranged from 2 to 112 oocysts per liter. The finding of Cryptosporidium oocysts in all samples examined from six western rivers is noteworthy in light of recent reports indicating that Cryptosporidium sp. is a significant agent of human and animal disease. This finding suggests that waterborne oocysts of this parasite are more important than was previously recognized. More detailed studies are needed to define geographical and temporal distribution, to assess the viability of waterborne oocysts, and to determine the importance of water as a means of transmission.
Butanol-Ethanol Dehydrogenase and Butanol-Ethanol-Isopropanol Dehydrogenase: Different Alcohol Dehydrogenases in Two Strains of
Clostridium beijerinckii (Clostridium butylicum)
Authors: Hiu Stephen F. , Zhu Chang-Xi , Yan Run-Tao , Chen Jiann-Shin
Published: January 2020

Alcohol-producing strains of
Clostridium beijerinckii (Clostridium butylicum)
produce, besides acetone, either
n
-butanol and ethanol or
n
-butanol, ethanol, and isopropanol as their characteristic products. Alcohol dehydrogenase has been isolated from a strain (NRRL B593) of
C. beijerinckii
producing isopropanol and from a strain (NRRL B592) not producing isopropanol. Butanol-ethanol dehydrogenase activities were present in both strains, but isopropanol dehydrogenase activity was present only in the isopropanol-producing strain. The butanol-ethanol dehydrogenase of strain NRRL B592 had
M
r
66,000 and a
K
m
of 6 μM for butyraldehyde. In contrast, the butanol-ethanol-isopropanol dehydrogenase of strain NRRL B593 had a
M
r
100,000 and
K
m
s
of 9.5 and 1.0 mM for butyraldehyde and acetone, respectively. In a purification by four different types of separatory methods (DEAE-cellulose, hydroxyapatite, Sephacryl S-300, and Matrex Gel Red A), butanol-ethanol-isopropanol dehydrogenase activities of strain NRRL B593 were purified up to 200-fold (10 to 30% yield), and these activities were not separated. Gel electrophoresis followed by activity stain also revealed distinct mobilities for the butanol-ethanol dehydrogenase of strain NRRL B592 and the butanol-ethanol-isopropanol dehydrogenase of strain NRRL B593. In cell extracts from both strains, a higher alcohol dehydrogenase activity was measured with NADP(H) than with NAD(H). The 150- to 200-fold-purified alcohol dehydrogenase from strain NRRL B593 did not show any NAD(H)-linked activities. The
K
m
for NADPH was 31 μM (with butyraldehyde as cosubstrate) and 18 μM (with acetone as cosubstrate) for the alcohol dehydrogenase of strain NRRL B593. This study showed that the alcohol dehydrogenases from two strains of
C. beijerinckii
differed significantly.
Isolation of Different
Agrobacterium
Biovars from a Natural Oak Savanna and Tallgrass Prairie
Authors: Bouzar Hacène , Moore Larry W.
Published: January 2020

Populations of agrobacteria in excess of 10
5
CFU/g were recovered from 12 soil and root samples obtained from the Allison Savanna, Minn., a natural oak savanna and tallgrass prairie which has never been disturbed agriculturally. Of 126 strains picked randomly from selective media, 54 were identified as
Agrobacterium
spp. Biovar 2 strains predominated (35 of 54), but these strains were distributed into three phenotypically distinct subgroups. Of the remaining
Agrobacterium
strains, four were biovar 1-2, one was biovar 1, and none were biovar 3. The last 14
Agrobacterium
strains formed a homogeneous group which differed biochemically from the hitherto reported biovars. Opine utilization (coded for by genes on the tumor-inducing plasmid in pathogenic
Agrobacterium
spp.) by these agrobacteria was limited to two biovar 2 strains. In contrast, 10 nonfluorescent gram-negative strains utilized either nopaline or octopine as the sole carbon and nitrogen source. There may be a need to reexamine the source and role of opines in the terrestrial environment because (i) all of these opine utilizers were isolated from an environment free of crown gall, the only known terrestrial source of opines, and (ii) 83% of the opine utilizers were not
Agrobacterium
spp.
Oxygen regulation of nitrate uptake in denitrifying Pseudomonas aeruginosa
Authors: Hernandez D , Rowe J J
Published: January 2020

Oxygen had an immediate and reversible inhibitory effect on nitrate respiration by denitrifying cultures of Pseudomonas aeruginosa. Inhibition of nitrate utilization by oxygen appeared to be at the level of nitrate uptake, since nitrate reduction to nitrite in cell extracts was not affected by oxygen. The degree of oxygen inhibition was dependent on the concentration of oxygen, and increasing nitrate concentrations could not overcome the inhibition. The inhibitory effect of oxygen was maximal at approximately 0.2% oxygen saturation. The inhibition appeared to be specific for nitrate uptake. Nitrite uptake was not affected by these low levels of aeration, and nitrite reduction was only partially inhibited in the presence of oxygen. The regulation of nitrate respiration at the level of transport by oxygen may represent a major mechanism by which the entire denitrification pathway is regulated in P. aeruginosa.
Explanations for the acclimation period preceding the mineralization of organic chemicals in aquatic environments
Authors: Wiggins B A , Jones S H , Alexander M
Published: January 2020

A study was conducted of possible reasons for acclimation of microbial communities to the mineralization of organic compounds in lake water and sewage. The acclimation period for the mineralization of 2 ng of p-nitrophenol (PNP) or 2,4-dichlorophenoxyacetic acid per ml of sewage was eliminated when the sewage was incubated for 9 or 16 days, respectively, with no added substrate. The acclimation period for the mineralization of 2 ng but not 200 ng or 2 micrograms of PNP per ml was eliminated when the compound was added to lake water that had been first incubated in the laboratory. Mineralization of PNP by Flavobacterium sp. was detected within 7 h at concentrations of 20 ng/ml to 2 micrograms/ml but only after 25 h at 2 ng/ml. PNP-utilizing organisms began to multiply logarithmically after 1 day in lake water amended with 2 micrograms of PNP per ml, but substrate disappearance was only detected at 8 days, at which time the numbers were approaching 10(5) cells per ml. The addition of inorganic nutrients reduced the length of the acclimation period from 6 to 3 days in sewage and from 6 days to 1 day in lake water. The prior degradation of natural organic materials in the sewage and lake water had no effect on the acclimation period for the mineralization of PNP, and naturally occurring inhibitors that might delay the mineralization were not present. The length of the acclimation phase for the mineralization of 2 ng of PNP per ml was shortened when the protozoa in sewage were suppressed by eucaryotic inhibitors, but it was unaffected or increased if the inhibitors were added to lake water.(ABSTRACT TRUNCATED AT 250 WORDS)
Properties of
Desulfovibrio carbinolicus
sp. nov. and Other Sulfate-Reducing Bacteria Isolated from an Anaerobic-Purification Plant
Authors: Nanninga Henk J. , Gottschal Jan C.
Published: January 2020

Several sulfate-reducing microorganisms were isolated from an anaerobic-purification plant. Four strains were classified as
Desulfovibrio desulfuricans, Desulfovibrio sapovorans, Desulfobulbus propionicus
, and
Desulfovibrio
sp. The
D. sapovorans
strain contained poly-β-hydroxybutyrate granules and seemed to form extracellular vesicles. A fifth isolate,
Desulfovibrio
sp. strain EDK82, was a gram-negative, non-spore-forming, nonmotile, curved organism. It was able to oxidize several substrates, including methanol. Sulfate, sulfite, thiosulfate, and sulfur were utilized as electron acceptors. Pyruvate, fumarate, malate, and glycerol could be fermented. Because strain EDK82 could not be ascribed to any of the existing species, a new species,
Desulfovibrio carbinolicus
, is proposed. The doubling times of the isolates were determined on several substrates. Molecular hydrogen, lactate, propionate, and ethanol yielded the shortest doubling times (3.0 to 6.3 h). Due to the presence of support material in an anaerobic filter system, these species were able to convert sulfate to sulfide very effectively at a hydraulic retention time as short as 0.5 h.
Reductive dechlorination of 2,4-dichlorobenzoate to 4-chlorobenzoate and hydrolytic dehalogenation of 4-chloro-, 4-bromo-, and 4-iodobenzoate by Alcaligenes denitrificans NTB-1
Authors: van den Tweel W J , Kok J B , de Bont J A
Published: January 2020

Alcaligenes denitrificans NTB-1, previously isolated on 4-chlorobenzoate, also utilized 4-bromo-, 4-iodo-, and 2,4-dichlorobenzoate but not 4-fluorobenzoate as a sole carbon and energy source. During growth, stoichiometric amounts of halide were released. Experiments with whole cells and cell extracts revealed that 4-bromo- and 4-iodobenzoate were metabolized like 4-chlorobenzoate, involving an initial hydrolytic dehalogenation yielding 4-hydroxybenzoate, which in turn was hydroxylated to 3,4-dihydroxybenzoate. The initial step in the metabolism of 2,4-dichlorobenzoate was catalyzed by a novel type of reaction for aerobic organisms, involving inducible reductive dechlorination to 4-chlorobenzoate. Under conditions of low and controlled oxygen concentrations, A. denitrificans NTB-1 converted all 4-halobenzoates and 2,4-dichlorobenzoate almost quantitatively to 4-hydroxybenzoate.
Fate of
Bacillus thuringiensis
subsp.
israelensis
under Simulated Field Conditions
Authors: Ohana Bella , Margalit Joel , Barak Ze'Ev
Published: January 2020

The fate of
Bacillus thuringiensis
subsp.
israelensis
in a natural aquatic habitat was studied in a model system by using laboratory-simulated field waters and a mutant of the bacterium resistant to three antibiotics. Contact with mud of a sporal culture of the mutant resulted in an immediate disappearance of the larvicidal activity but had no influence on viability. The cessation of toxicity was caused by bacterial adsorption on soil particles, since 99.8% of the bacteria was found in the mud fraction within 45 min, with concurrent disappearance from the supernatant. When the mud was stirred, the bacteria could be redetected. The viability count of the mud suspension remained practically constant for at least 22 days, indicating that the spores were still fully viable but were incapable of germinating and multiplying in the mud under our experimental conditions. Approximately 8% of the colony forming ability of the bacteria could be separated from the mud by vigorous mixing followed by immediate filtration. The filtrated spores retained their toxicity, killing 90% of the larval populations even after 22 days incubation in the soil. The inactivation of the toxic activity of
B. thuringiensis
subsp.
israelensis
in the mud was therefore a reversible process and was probably due to masking of the bacteria, thus making the bacteria and their toxin inaccessible to the larvae. In the simulated field waters without mud, we observed only a very slow inhibition of the larvicidal activity. In contrast to the activity in the mud suspension, this activity could not be restored.
Bacterial O-methylation of halogen-substituted phenols
Authors: Allard A S , Remberger M , Neilson A H
Published: January 2020

Two strains of bacteria capable of carrying out the O-methylation of phenolic compounds, one from the gram-positive genus Rhodococcus and one from the gram-negative genus Acinetobacter, were used to examine the O-methylation of phenols carrying fluoro-, chloro-, and bromo-substituents. Zero-order rates of O-methylation were calculated from data for the chloro- and bromophenols; there was no simple relationship between the rates of reaction and the structure of the substrates, and significant differences were observed in the responses of the two test organisms. For the gram-negative strain, the pattern of substitution was as important as the number of substituents. Hexachlorophene was resistant to O-methylation by both strains, and tetrabromobisphenol-A was O-methylated only by the gram-positive strain. It is suggested that in the natural environment, bacterial O-methylation of phenols carrying electron-attracting substituents might be a significant alternative to biodegradation.
Photosynthetic action spectra and adaptation to spectral light distribution in a benthic cyanobacterial mat
Authors: Jorgensen B B , Cohen Y , Des Marais D J
Published: January 2020

We studied adaptation to spectral light distribution in undisturbed benthic communities of cyanobacterial mats growing in hypersaline ponds at Guerrero Negro, Baja California, Mexico. Microscale measurements of oxygen photosynthesis and action spectra were performed with microelectrodes; spectral radiance was measured with fiber-optic microprobes. The spatial resolution of all measurements was 0.1 mm, and the spectral resolution was 10 to 15 nm. Light attenuation spectra showed absorption predominantly by chlorophyll a (Chl a) (430 and 670 nm), phycocyanin (620 nm), and carotenoids (440 to 500 nm). Blue light (450 nm) was attenuated 10-fold more strongly than red light (600 nm). The action spectra of the surface film of diatoms accordingly showed activity over the whole spectrum, with maxima for Chl a and carotenoids. The underlying dense Microcoleus population showed almost exclusively activity dependent upon light harvesting by phycobilins at 550 to 660 nm. Maximum activity was at 580 and 650 nm, indicating absorption by phycoerythrin and phycocyanin as well as by allophycocyanin. Very little Chl a-dependent activity could be detected in the cyanobacterial action spectrum, even with additional 600-nm light to excite photosystem II. The depth distribution of photosynthesis showed detectable activity down to a depth of 0.8 to 2.5 mm, where the downwelling radiant flux at 600 nm was reduced to 0.2 to 0.6% of the surface flux.
A new selective medium for isolating Pseudomonas spp. from water
Authors: Krueger C L , Sheikh W
Published: January 2020

A new medium, pseudomonas selective isolation agar, was developed to isolate Pseudomonas spp. from water. It consists of 350 micrograms of nitrofurantoin per ml and 2 micrograms of crystal violet per ml in a nutrient agar base. It is more selective for Pseudomonas spp. than are available commercial media. Its ingredients are inexpensive and readily available, and it is easy to prepare.
Conjugal transfer of plasmid DNA between streptococci immobilized in calcium alginate gel beads
Authors: Steenson L R , Klaenhammer T R
Published: January 2020

A rapid and simple technique was developed for conjugation between group N and group D streptococci by using cells entrapped within calcium alginate gel beads. With this method, the frequencies of transfer of lactose metabolism from Streptococcus lactis ME2 to S. lactis LM2302 were comparable to those achieved with agar surface matings. Conjugal transfer of the chloramphenicol and erythromycin resistance plasmid pVA797::Tn917 from S. faecalis V1229 to S. faecalis V1102 in alginate beads occurred at frequencies comparable to those achieved with filter matings. The results demonstrated efficient conjugal transfer of plasmid DNA among alginate-immobilized streptococcal cells and suggested that this method could be used as an alternative to conventional solid-surface and filter matings with these organisms.
Microbiological evaluation of wet and dry floor sanitization systems in hospital patient rooms
Authors: Vesley D , Klapes N A , Benzow K , Le C T
Published: January 2020

A new system for sanitizing floors in hospital patient rooms has been developed. The method consists of dry dusting with a cotton-blend, chemically treated (10% by dry mop weight) dust mop. This method was compared with a conventional cleaning protocol consisting of an initial predusting with the same nongermicidal chemical (3% by dry mop weight) followed by wet mopping with a fresh solution of a quaternary ammonium disinfectant-detergent. Each of six rooms was sampled by using RODAC plates (Becton Dickinson Labware, Oxnard, Calif.) on 10 consecutive days for each of the two methods. The study was initially performed during the summer and then repeated during the winter. Results imply that there is no significant difference between the new dry method (81.9% CFU reduction) and the conventional method (83.1% CFU reduction). Furthermore, the initial dry dusting step in the conventional method accounted for virtually all of the reduction by that method. Thus, wet mopping with a germicidal chemical produced no additional significant reduction of natural microbial populations on environmental surfaces beyond that achieved by dry dusting with dust-suppressant chemicals.
Effect of phenolic acids and phenolics from plant cell walls on rumenlike fermentation in consecutive batch culture
Authors: Theodorou M K , Gascoyne D J , Akin D E , Hartley R D
Published: January 2020

Information on the interaction between mixed populations in the rumen and plant phenolics is required to fully elucidate the limitations of phenolic compounds on forage digestibility. The objective of this study was to examine the degradation of Italian ryegrass (Lolium multiflorum L.) hay incubated with mixed ruminal populations in consecutive batch culture (CBC) with or without phenolic acids or phenolic compounds extracted from plant cell walls. Each CBC consisted of a series of 10 cultures (3 replicates per culture) inoculated (10%, vol/vol) in sequence at 48-h intervals with microbial suspension from the previous set of cultures. All cultures were grown on a semidefined medium containing Italian ryegrass hay, and each CBC was initiated with an inoculum from the rumen. Rumenlike fermentation characteristics were maintained in control CBCs by repeated inoculum transfer. Treatment CBCs were transferred as described above, but cultures 5, 6, and 7 were incubated in the presence of trans-p-coumaric, cis-p-coumaric, or trans-ferulic acid or phenolics extracted from the cell walls of maize stem or barley straw. Mean apparent dry matter disappearance in control CBC cultures was 495 mg per g of hay, whereas the presence of phenolics reduced the initial dry matter disappearance by 6.3 to 25.6%. trans-p-Coumaric acid and, to a lesser extent, the phenolics from cell walls of maize stem were the most inhibitory compounds for dry matter disappearance and for the production of volatile fatty acids; trans-p-coumaric acid altered the molar ratio of acetate/propionate/butyrate. The CBC further showed variations in the ability of the rumen microbial population to adapt to phenolic compounds.
Evidence for novel mechanisms of polychlorinated biphenyl metabolism in Alcaligenes eutrophus H850
Authors: Bedard D L , Haberl M L , May R J , Brennan M J
Published: January 2020

Previous studies indicated that Alcaligenes eutrophus H850 attacks a different spectrum of polychlorinated biphenyl (PCB) congeners than do most PCB-degrading bacteria and that novel mechanisms of PCB degradation might be involved. To delineate this, we have investigated the differences in congener selectivity and metabolite production between H850 and Corynebacterium sp. strain MB1, an organism that apparently degrades PCBs via a 2,3-dioxygenase. H850 exhibited a superior ability to degrade congeners via attack on 2-, 2,4-, 2,5-, or 2,4,5-chlorophenyl rings in PCBs but an inferior ability to degrade congeners via attack on a 4-chlorophenyl ring. Reactivity preferences were also reflected in the products formed from unsymmetrical PCBs; thus MB1 attacked the 2,3-chlorophenyl ring of 2,3,2',5'-tetrachlorobiphenyl to yield 2,5-dichlorobenzoic acid, while H850 attacked the 2,5-chlorophenyl ring to yield 2,3-dichlorobenzoic acid and a novel metabolite, 2',3'-dichloroacetophenone. Furthermore, H850 oxidized 2,4,5,2',4',5'-hexachlorobiphenyl, a congener with no adjacent unsubstituted carbons, to 2',4',5'-trichloroacetophenone. The atypical congener selectivity pattern and novel metabolites produced suggest that A. eutrophus H850 may degrade certain PCB congeners by a new route beginning with attack by some enzyme other than the usual 2,3-dioxygenase.
Occurrence of Staphylococcus aureus and Pseudomonas aeruginosa in Israeli coastal water
Authors: Yoshpe-Purer Y , Golderman S
Published: January 2020

The occurrence of Pseudomonas aeruginosa and coagulase-positive Staphylococcus aureus in seawater from beaches of central Israel was investigated from June 1983 until June 1985. P. aeruginosa was monitored in 652 samples of seawater from 34 beaches, and S. aureus was monitored in 628 samples. P. aeruginosa was found in 44.8% of samples (6.5% with 1 bacterium per 100 ml of water), and S. aureus was recovered from 60.7% of samples (5.3% with 1 organism per 100 ml), compared with 91.6% of samples with total coliforms (TC) and 82.2% with fecal coliforms (FC). The correlation between the presence of P. aeruginosa to that of TC and FC was 99.1 and 98.3%, respectively, while S. aureus was found in 4.3 and 8% of samples where TC and FC, respectively, were absent. Monitoring of S. aureus as a supplementary indicator in populated beaches is recommended because it will add valuable information on the sanitary quality of the seawater.
Microbial Ecophysiology of Whey Biomethanation: Comparison of Carbon Transformation Parameters, Species Composition, and Starter Culture Performance in Continuous Culture
Authors: Chartrain M. , Bhatnagar L. , Zeikus J. G.
Published: January 2020

Changes in lactose concentration and feed rate altered bacterial growth and population levels in a whey-processing chemostat. The bacterial population and methane production levels increased in relation to increased lactose concentrations comparable to those in raw whey (6%) and converted over 96% of the substrate to methane, carbon dioxide, and cells. Sequential increases in the chemostat dilution rate demonstrated excellent biomethanation performance at retention times as low as 25 h. Retention times shorter than 25 h caused prevalent bacterial populations and methane production to decrease, and intermediary carbon metabolites accumulated in the following order: acetate, butyrate, propionate, lactate, ethanol, and lactose. Bacterial species dominated in the chemostat as a function of their enhanced substrate uptake and growth kinetic properties. The substrate uptake kinetic properties displayed by the mixed chemostat population were equivalent to those of individual species measured in pure culture, whereas the growth kinetic properties of species in mixed culture were better than those measured in pure culture. A designed starter culture consisting of
Leuconostoc mesenteroides, Desulfovibrio vulgaris, Methanosarcina barkeri,
and
Methanobacterium formicicum
displayed biomethanation performance, which was similar to that of a diverse adapted mixed-culture inoculum, in a continuous contact digestor system to which 10 g of dry whey per liter was added. Preserved starter cultures were developed and used as inocula for the start-up of a continuous anaerobic digestion process that was effective for biomethanation of raw whey at a retention time of 100 h.
Distribution of Protozoa in Subsurface Sediments of a Pristine Groundwater Study Site in Oklahoma
Authors: Sinclair James L. , Ghiorse William C.
Published: January 2020

Sediment core samples were obtained at a groundwater study site in Oklahoma in January and June 1985. Most-probable-number estimates showed that protozoan numbers declined steeply with depth in subsoil. Flagellates and amoebae dominated the protozoan population, which declined to a most probable number of 28 · g (dry weight)
−1
in a clay loam layer at the bottom of the unsaturated zone. Samples from a texturally variable interface zone between 3 and 4 m down also were variable in their content of protozoa. Four contiguous clay loam samples in a single core from this zone contained variable numbers of amoebae ranging from 0.2 to 44 · g (dry weight)
−1
. However, a sandy clay loam layer at the bottom of the core contained a mixture of flagellates and amoebae with a combined population density of 67 · g (dry weight)
−1
. A slow-growing filose amoeba was isolated from interface zone samples and was tentatively classified in a new family in the order Aconchulinida. Protozoa were not detected in the saturated zone except in a very permeable gravelly, loamy sand layer at a depth of approximately 7.5 m. Low numbers (4 to 6 · g [dry weight]
−1
) of surface-type flagellates and amoebae, as well as the filose amoeba seen in the interface zone, were observed in this layer. Acid-treated and untreated samples contained equivalent numbers of protozoa, showing that the majority of protozoa in the layer at 7.5 m and the interface zone samples were encysted. Increased numbers of bacteria also were found in the layer at 7.5 m, indicating that it was biologically more active than other saturated-zone layers. Cyanobacteria grew in illuminated samples from this layer, suggesting that it may be connected hydrologically to a nearby river.
Susceptibility of Halobacteria to Heavy Metals
Authors: Nieto J. J. , Ventosa A. , Ruiz-Berraquero F.
Published: January 2020

Sixty-eight halobacteria, including both culture collection strains and fresh isolates from widely differing geographical areas, were tested for susceptibility to arsenate, cadmium, chromium, cobalt, copper, lead, mercury, nickel, silver, and zinc ions by an agar dilution technique. The culture collection strains showed different susceptibilities, clustering into five groups.
Halobacterium mediterranei
and
Halobacterium volcanii
were the most metal tolerant, whereas
Haloarcula californiae
and
Haloarcula sinaiiensis
had the highest susceptibilities of the culture collection strains. Different patterns of metal susceptibility were found for all the halobacteria tested, and there was a uniform susceptibility to mercury and silver. All strains tested were multiply metal tolerant.
Degradation of chlorinated phenols by a pentachlorophenol-degrading bacterium
Authors: Steiert J G , Pignatello J J , Crawford R L
Published: January 2020

A pentachlorophenol (PCP)-degrading Flavobacterium sp. was tested for its ability to dechlorinate other chlorinated phenols by using resting cells that had been grown in the presence or absence of PCP. Phenols with chlorine atoms at positions 2 and 6 of the phenol ring were dechlorinated completely by PCP-induced cells. Other chlorinated phenols were not significantly mineralized. When PCP was added to a culture growing on L-glutamate, there was a lag period before the start of PCP degradation. When similar cells were treated with chloramphenicol prior to the addition of PCP, they did not degrade added PCP, even after prolonged incubations. Thus, the enzymes necessary for PCP degradation appeared to be inducible. Suspensions of cells grown in the presence of 2,4,6-trichlorophenol or 2,3,5,6-tetrachlorophenol did not show a lag period for mineralization of PCP, 2,4,6-trichlorophenol, or 2,3,5,6-tetrachlorophenol, indicating that one enzyme system probably was induced for the biodegradation of all three compounds. Nondegradable chlorophenols were toxic toward the Flavobacterium sp., probably acting as uncouplers of oxidative phosphorylation.