bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Immunologic Analysis of the Methanogenic Flora of Digestors Reveals a Considerable Diversity
Authors: Macario Alberto J. L. , de Macario Everly Conway
Published: January 2020

To determine which methanogens occur in digestors, we performed a quantitative immunologic analysis of a variety of samples. A comprehensive panel of calibrated polyclonal antibody probes of predefined specificity spectra was used. This allowed precise identification of bacteria by antigenic fingerprinting. A considerable diversity of methanogens was uncovered, much larger than previously reported, encompassing at least 14 strains of 11 species. Strategies were developed to measure the load of any given methanogen in a sample and to compare samples quantitatively. Two methanogens were found to predominate which were antigenically closely related with either
Methanobacterium formicicum
MF or
Methanobrevibacter arboriphilus
AZ. Fundamental data, probes, and methods are now available to monitor methanogenic subpopulations during digestor operation and thus learn about their respective roles and predictive significance.
Influence of amino acids on nitrogen fixation ability and growth of Azospirillum spp
Authors: Hartmann A , Fu H A , Burris R H
Published: January 2020

The utilization of amino acids for growth and their effects on nitrogen fixation differ greatly among the several strains of each species of Azospirillum spp. that were examined. A. brasiliense grew poorly or not at all on glutamate, aspartate, serine, or histidine as the sole nitrogen and carbon sources. Nitrogen fixation by most A. brasiliense strains was inhibited only slightly even by 10 mM concentrations of these amino acids. In contrast, A. lipoferum and A. amazonense grew very well on glutamate, aspartate, serine, or histidine as the sole nitrogen and carbon sources; nitrogen fixation, which was measured in the presence of malate or sucrose, was severely inhibited by these amino acids. It was concluded that growth on histidine as the sole source of nitrogen, carbon, and energy may be used for the taxonomic characterization of Azospirillum spp. and for the selective isolation of A. lipoferum. The different utilization of various amino acids by Azospirillum spp. may be important for their establishment in the rhizosphere and for their associative nitrogen fixation with plants. The physiological basis for the different utilization of glutamate by Azospirillum spp. was investigated further. A. brasiliense and A. lipoferum exhibited a high affinity for glutamate uptake (Km values for uptake were 8 and 40 microM, respectively); the Vmax was 6 times higher in A. lipoferum than in A. brasiliense. At high substrate concentrations (10 mM), the nonsaturable component of glutamate uptake was most active in A. lipoferum and A. amazonense.(ABSTRACT TRUNCATED AT 250 WORDS)
Effect of anaerobic digestion on oocysts of the protozoan Eimeria tenella
Authors: Lee M R , Shih J C
Published: January 2020

The effect of anaerobic digestion of poultry waste on oocysts of the protozoan Eimeria tenella, a common enteric pathogen that causes coccidiosis in poultry, was investigated in this study. Thermophilic (50 degrees C) and mesophilic (35 degrees C) anaerobic digestors, with poultry manure as the substrate, were inoculated with the oocysts. The oocysts were damaged during anaerobic digestion, as determined by morphological change and loss of their ability to sporulate. The recovered oocysts were tested for their infectivity in young chicks, as measured by body weight gain, mortality, and cecal lesions. Oocysts lost all their infectivity during thermophilic digestion, while oocysts subjected to mesophilic digestion remained moderately infective in comparison with untreated oocysts, which produced severe coccidiosis, high mortality, and low body weight gain in chicks. Oocysts were inactivated at 50 degrees C when they were suspended in digestor fluid or saline. Inactivation at 35 degrees C was significantly stronger in the digestor fluid than in the saline, which implied that factors other than temperature were involved in the lethal effect of anaerobic digestion on protozoan oocysts. In this study we demonstrated that the treatment of animal waste by anaerobic digestion, especially at a thermophilic temperature, has the benefits of pathogen control and protection of human and animal health in a farm environment.
Rapid latex agglutination test for detection of staphylococcal enterotoxins A to E that uses high-density latex particles
Authors: Fujikawa H , Igarashi H
Published: January 2020

A rapid reversed passive latex agglutination method that uses high-density latex particles for the detection of staphylococcal enterotoxins (SE) A to E was developed. It took 3 h for incubation, much less than the 16 h needed with a customary latex agglutination test for SE detection such as a commercial test kit (SET-RPLA; Denka Seiken Co. Ltd., Tokyo, Japan). The rapid test was shown to be highly specific and sensitive for SE detection (detection limit, about 0.5 ng of SE per ml), comparable to the SET-RPLA test. The rapid test was also efficient in SE detection in foods and culture supernatants of staphylococcal strains, similar to the SET-RPLA test. This showed that a rapid test with high-density latex particles is fully reliable for use.
Inhibition of Listeria monocytogenes by using bacteriocin PA-1 produced by Pediococcus acidilactici PAC 1.0
Authors: Pucci M J , Vedamuthu E R , Kunka B S , Vandenbergh P A
Published: January 2020

The bacteriocin produced by Pediococcus acidilactici PAC 1.0, previously designated PA-1 bacteriocin, was found to be inhibitory and bactericidal for Listeria monocytogenes. A dried powder prepared from PAC 1.0 culture supernatant fortified with 10% milk powder was found to contain bacteriocin activity. An MIC against L. monocytogenes and lytic effects in broth cultures were determined. Inhibition by PA-1 powder occurred over the pH range 5.5 to 7.0 and at both 4 and 32 degrees C. In addition, inhibition of L. monocytogenes was demonstrated in several food systems including dressed cottage cheese, half-and-half cream, and cheese sauce.
Effects of
Bradyrhizobium japonicum
and Soybean (
Glycine max
(L.) Merr.) Phosphorus Nutrition on Nodulation and Dinitrogen Fixation
Authors: Mullen Michael D. , Israel Daniel W. , Wollum A. G.
Published: January 2020

Cells of
Bradyrhizobium japonicum
were grown in media containing either 1.0 mM or 0.5 μM phosphorus. In growth pouch experiments, infection of the primary root of soybean (
Glycine max
(L.) Merr.) by
B. japonicum
USDA 31, 110, and 142 was significantly delayed when P-limited cells were applied to the root. In a greenhouse experiment,
B. japonicum
USDA 31, 110, 122, and 142 grown with sufficient and limiting P were used to inoculate soybeans which were grown with either 5 μM or 1 mM P nutrient solution. P-limited cells of USDA 31 and 110 formed significantly fewer nodules than did P-sufficient cells, but P-limited cells of USDA 122 and 142 formed more nodules than P-sufficient cells. The increase in nodule number by P-limited cells of USDA 142 resulted in significant increases in both nodule mass and shoot total N. In plants grown with 1 mM P, inoculation with P-limited cells of USDA 110 resulted in lower total and specific nitrogenase activities than did inoculation with P-sufficient cells. Nodule numbers, shoot dry weights, and total N and P were all higher in plants grown with 1 mM P, and plants inoculated with USDA 31 grew poorly relative to plants receiving strains USDA 110, 122, and 142. Although the effects of soybean P nutrition were more obvious than those of
B. japonicum
P nutrition, we feel that it is important to develop an awareness of the behavior of the bacterial symbiont under conditions of nutrient limitation similar to those found in many soils.
Degradation of 2-Methylisoborneol by Aquatic Bacteria
Authors: Izaguirre George , Wolfe Roy L. , Means Edward G.
Published: January 2020

2-Methylisoborneol (MIB) is a musty- or muddy-smelling compound which occurs in some natural waters and which is difficult to remove by conventional water treatment methods. Bacterial degradation of MIB was examined in batch culture experiments. Cultures able to metabolize MIB were enriched in a mineral salts medium supplemented with milligram-per-liter levels of the compound and were inoculated with water and sediment samples from reservoirs where MIB is seasonally produced. Bacteria from degrading cultures were isolated on R2A agar and identified as predominantly
Pseudomonas
spp. Degradation occurred only in cultures consisting of three or more different bacteria. MIB supported growth as the sole added carbon source at 1 to 6.7 mg/liter. MIB was also degraded at microgram-per-liter levels in sterile filtered lake water inoculated with washed bacteria and in synthetic medium supplemented with various sugars or acetate. Complete degradation of MIB took from 5 days to more than 2 weeks. Enrichment with isoborneol, a structural analog of MIB, failed as a preenrichment for MIB degraders. Isoborneol at 20 to 40 mg/liter readily supported bacterial growth, whereas MIB at 12 to 20 mg/liter took months to degrade. The relative recalcitrance of MIB compared with isoborneol may be a result of the additional methyl group in MIB.
Influence of readily metabolizable carbon on pentachlorophenol metabolism by a pentachlorophenol-degrading Flavobacterium sp
Authors: Topp E , Crawford R L , Hanson R S
Published: January 2020

The influence of high concentrations of pentachlorophenol (PCP) and readily metabolizable carbon on the activity and viability of a PCP-degrading Flavobacterium sp. was examined in a mineral salts medium. Lags preceding PCP removal by glutamate-grown Flavobacterium cells were greatly attenuated by the addition of glutamate, aspartate, succinate, acetate, glucose, or cellobiose. The effect of these supplementary carbon sources on the apparent lag was not mediated entirely through the stimulation of growth since PCP metabolism accompanied the onset of growth. The specific activity of PCP-degrading cells in the absence of supplementary carbon was 1.51 x 10(-13) +/- 0.08 x 10(-13) g of PCP per cell per h and in the presence of supplementary carbon was 0.92 x 10(-13) +/- 0.09 x 10(-13) g of PCP per cell per h. Glutamate in combination with glucose or cellobiose partially repressed PCP metabolism. PCP removal by PCP-induced, glutamate-grown cells suspended in the presence of 4 g of sodium glutamate per liter was sensitive to shock loads of PCP, with a Ki of about 86.8 micrograms/ml. Subsequent removal rates, however, were more resistant to PCP. Optimal stimulation of PCP removal by sodium glutamate required 3.0 g/liter, about the same concentration as that which saturated growth in the absence of PCP. PCP removal rates decayed within minutes following the transfer of PCP-induced, glutamate-grown cells to media containing PCP without supplementary carbon, and increasing PCP concentrations accelerated the decay.(ABSTRACT TRUNCATED AT 250 WORDS)
Fruiting at High Temperature and Its Genetic Control in the Basidiomycete
Flammulina velutipes
Authors: Fultz Sara A.
Published: January 2020

Of 10 geographic strains of
Flammulina velutipes
, 4 were found capable of fruiting at 22°C (Fr
H
) rather than at the typical 15°C (Fr
L
). Crosses made between Fr
H
and Fr
L
monokaryons were never observed to fruit at 22°C. However, some hybrids did fruit at the intermediate temperature of 18°C when grown on appropriate substrates, indicating incomplete dominance of the low-temperature requirement. Analysis of progeny of five Fr
H
× Fr
L
crosses indicated that a minimum of two genes appears to control the requirement for fruiting at ≤15°C. The genes are not closely linked to either incompatibility locus.
Outermost-cell-surface changes in an encapsulated strain of Staphylococcus aureus after preservation by freeze-drying
Authors: Ohtomo T , Yamada T , Yoshida K
Published: January 2020

The effects of drying time during freeze-drying on the outermost cell surface of an encapsulated strain of Staphylococcus aureus S-7 (Smith, diffuse) were investigated, with special attention paid to capsule and slime production. To quantify capsule and slime production, capsule antigen production and cellular characteristics such as growth type in serum-soft agar, cell volume index, and clumping factor reaction were examined. After freeze-drying the colonial morphology of strain S-7 was altered from a diffuse to a compact type in serum-soft agar. In accordance with these changes, the titer of the clumping factor reaction increased while the cell volume index, capsule and slime production, and capsule antigen production were markedly decreased in parallel with the period of freeze-drying. The ability of the strain to adhere to collagen, fibrinogen, and soybean lectin was also compared before and after freeze-drying. Fibrinogen levels slightly increased when 10% skim milk and 2% honey were used as cryoprotective agents and showed a remarkable increase when 0.05 M phosphate buffer was used as a control. Also, the ability of strain S-7 to adhere to soybean lectin declined, whereas no changes were observed for collagen under any conditions. Strain S-7 was phage nontypable before freeze-drying but the number of typable cells increased after freeze-drying; phage-typable cells reacted to phage 52 alone after 5 h of freeze-drying, but additional cells also proved to be phage typable to phage 42E after 10 h. Electron micrographs indicated that strain S-7, an encapsulated strain, was converted to an unencapsulated state after freeze-drying.(ABSTRACT TRUNCATED AT 250 WORDS)
Inactivation of biofilm bacteria
Authors: LeChevallier M W , Cawthon C D , Lee R G
Published: January 2020

The current project was developed to examine inactivation of biofilm bacteria and to characterize the interaction of biocides with pipe surfaces. Unattached bacteria were quite susceptible to the variety of disinfectants tested. Viable bacterial counts were reduced 99% by exposure to 0.08 mg of hypochlorous acid (pH 7.0) per liter (1 to 2 degrees C) for 1 min. For monochloramine, 94 mg/liter was required to kill 99% of the bacteria within 1 min. These results were consistent with those found by other investigators. Biofilm bacteria grown on the surfaces of granular activated carbon particles, metal coupons, or glass microscope slides were 150 to more than 3,000 times more resistant to hypochlorous acid (free chlorine, pH 7.0) than were unattached cells. In contrast, resistance of biofilm bacteria to monochloramine disinfection ranged from 2- to 100-fold more than that of unattached cells. The results suggested that, relative to inactivation of unattached bacteria, monochloramine was better able to penetrate and kill biofilm bacteria than free chlorine. For free chlorine, the data indicated that transport of the disinfectant into the biofilm was a major rate-limiting factor. Because of this phenomenon, increasing the level of free chlorine did not increase disinfection efficiency. Experiments where equal weights of disinfectants were used suggested that the greater penetrating power of monochloramine compensated for its limited disinfection activity. These studies showed that monochloramine was as effective as free chlorine for inactivation of biofilm bacteria. The research provides important insights into strategies for control of biofilm bacteria.
Effect of Fermentation Conditions on Growth of
Streptococcus cremoris
AM2 and
Leuconostoc lactis
CNRZ 1091 in Pure and Mixed Cultures
Authors: Boquien Clair-Yves , Corrieu Georges , Desmazeaud Michel J.
Published: January 2020

Two strains of mesophilic lactic acid bacteria,
Streptococcus cremoris
AM2 and
Leuconostoc lactis
CNRZ 1091, were grown in pure and mixed cultures in the presence or absence of citrate (15 mM) and at controlled (pH 6.5) or uncontrolled pH. Microbial cell densities at the end of growth, maximum growth rates, the pH decrease of the medium resulting from growth, and the corresponding acidification rates were determined to establish comparisons. The control of pH in pure cultures had no effect on
L. lactis
CNRZ 1091 populations. The final populations of
S. cremoris
AM2, however, were at least five times higher than when the pH was not controlled (4 × 10
8
vs. 2 × 10
9
CFU · ml
−1
). The pH had no effect on the growth rate of either strain. That of
S. cremoris
AM2 (0.8 h
−1
) was about twice that of
L. lactis
CNRZ 1091. When the pH fell below 5, the growth of both strains decreased or stopped altogether. Citrate had no effect on
S. cremoris
AM2, while final populations of
L. lactis
CNRZ 1091 were two to three times higher (3 × 10
8
CFU · ml
−1
); it had no effect on the maximum growth rates of the two strains. Citrate attenuated the pH decrease of the medium and reduced the maximum acidification rate of the culture by 50%, due to the growth of
S. cremoris
AM2. Acidification due to
L. lactis
CNRZ 1091, however, was very slight. Regardless of the conditions of pH and citrate, the total bacterial population in mixed culture was lower (by 39%) than that of the sum of each pure culture. Mixed culture improved the maximum growth rate of
L. lactis
CNRZ 1091 (0.6 h
−1
) by 50%, while that of
S. cremoris
AM2 was unaffected. The acidification rate of the growth medium in mixed culture, affected by the presence of citrate, resulted from the development and activity of
S. cremoris
AM2.
Antibacterial activity of soluble pyridinium-type polymers
Authors: Kawabata N , Nishiguchi M
Published: January 2020

Cross-linked poly(N-benzyl-4-vinylpyridinium halide) (designated insoluble BVP) was previously reported to capture bacterial cells alive by contact with them. The corresponding linear polymer poly(N-benzyl-4-vinylpyridinium salt) (designated soluble BVP) was found to exhibit antibacterial activity. This soluble pyridinium-type polymer showed strong antibacterial activity against gram-positive bacteria, whereas it was less active against gram-negative bacteria. The antibacterial activity of this cationic, polymeric disinfectant was considerably greater than that of the corresponding monomeric compound and was approximately equal to that of conventional disinfectants such as benzalkonium chloride and chlorohexidine.
Rapid hydrophobic grid membrane filter-enzyme-labeled antibody procedure for identification and enumeration of Escherichia coli O157 in foods
Authors: Todd E C , Szabo R A , Peterkin P , Sharpe A N , Parrington L , Bundle D , Gidney M A , Perry M B
Published: January 2020

An O-antigen-specific monoclonal antibody, labeled by horseradish peroxidase-protein A, was used in a hydrophobic grid membrane filter-enzyme-labeled antibody method for rapid detection of Escherichia coli O157 in foods. The method yielded presumptive identification within 24 h and recovered, on average, 95% of E. coli O157:H7 artificially inoculated into comminuted beef, veal, pork, chicken giblets, and chicken carcass washings. In food samples from two outbreaks involving E. coli O157:H7, the organism was isolated at levels of up to 10(3)/g. The lower limit of sensitivity was 10 E. coli O157 per g of meat. Specific typing for E. coli O157:H7 can be achieved through staining with labeled H7 antiserum or tube agglutination.
Expression of Nodulation Genes in
Rhizobium leguminosarum
biovar
trifolii
Is Affected by Low pH and by Ca and Al Ions
Authors: Richardson Alan E. , Simpson Richard J. , Djordjevic Michael A. , Rolfe Barry G.
Published: January 2020

Early stages in the infection of leguminous plants by
Rhizobium
spp. are restricted at low pH and are further influenced by the presence of Ca and Al ions. In the experiments reported here, transcriptional and translational fusions of the
Escherichia coli lacZ
gene to
Rhizobium leguminosarum
biovar
trifolii
nodulation (
nod
) genes were used to investigate the effects of pH and of Ca and Al ions on
nod
gene expression. The regulatory
nodD
gene in
R. leguminosarum
biovar
trifolii
was constitutively expressed at a range of pH levels between 4.8 and 6.5, and expression was not affected by the addition of 22.5 μM Al or 1,250 μM Ca. Induction of expression of
nodA, nodF,
and region II nodulation genes in the presence of 5 × 10
−7
M 7,4′-dihydroxyflavone was restricted at a pH of <5.7 and was extremely poor at pH 4.8. Induction of
nodA
expression was further restricted by 22.5 μM Al over a range of pH levels but was increased in the presence of Ca. The addition of Ca, however, only slightly alleviated the Al-mediated inhibition of
nodA
induction. Induction of expression of
nodA
was equally sensitive to low pH in three strains of
R. leguminosarum
biovar
trifolii
(ANU845, ANU815, and ANU1184), which exhibited contrasting growth abilities in solution culture at a pH of <5.0. Aluminum, however, differentially affected the induction of
nodA
in these three strains, with the most Al-tolerant strain for growth being the most Al-sensitive strain for
nod
gene induction. Poor induction of expression of nodulation genes in
R. leguminosarum
biovar
trifolii
was considered to be an important factor contributing to the acid-sensitive step of legume root infection.
Dissimilar plasmids isolated from Pseudomonas diminuta MG and a Flavobacterium sp. (ATCC 27551) contain identical opd genes
Authors: Harper L L , McDaniel C S , Miller C E , Wild J R
Published: January 2020

The opd (organophosphate-degrading) gene derived from a 43-kilobase-pair plasmid (pSM55) of a Flavobacterium sp. (ATCC 27551) has a sequence identical to that of the plasmid-borne gene of Pseudomonas diminuta. Hybridization studies with DNA fragments obtained by restriction endonuclease digestion of plasmid DNAs demonstrated that the identical opd sequences were encoded on dissimilar plasmids from the two sources.
Formation, regeneration, and transfection of Lactobacillus plantarum protoplasts
Authors: Cosby W M , Casas I A , Dobrogosz W J
Published: January 2020

Protoplasts of L. plantarum were produced by mutanolysin-lysozyme digestion at 50 degrees C and regenerated at a frequency of 1.6 to 3.8%. The addition of Tween 80 to the growth medium increased the length of time required for protoplast formation. When transfected with bacteriophage B2 DNA, transfection efficiencies ranged from 25 to 230 PFU/microgram of DNA and from 2.2 X 10(-5) to 4.7 X 10(-4) PFU per recovered protoplast. Total transfectant yield was 3.7 X 10(2) to 3.4 X 10(3) per treatment. Transformations with plasmid DNA were unsuccessful.
Penetrability of White Rot-Degraded Pine Wood by the Lignin Peroxidase of
Phanerochaete chrysosporium
Authors: Srebotnik Ewald , Messner Kurt , Foisner Roland
Published: January 2020

The penetration of enzymes into wood cell walls during white rot decay is an open question. A postembedding immunoelectron microscopic technique was the method of choice to answer that question. Infiltration of pine wood specimens with a concentrated culture filtrate greatly improved the labeling density and, thereby, reproducibility. Characterization of the concentrated culture filtrate by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting (immunoblotting) revealed three closely spaced proteins of molecular weights about 42,000 showing immunoreactivity against anti-lignin peroxidase serum. It was shown by immunogold labeling that lignin peroxidase of
Phanerochaete chrysosporium
is located on the surface of the wood cell wall or within areas of heavy attack. It did not diffuse into undecayed parts of the cell wall. The reasons for preventing lignin peroxidase from penetrating wood cell walls during white rot decay are discussed.
Stability of
Bradyrhizobium japonicum
Inoculants after Introduction into Soil
Authors: Brunel Brigitte , Cleyet-Marel Jean-Claude , Normand Philippe , Bardin Rene
Published: January 2020

Bradyrhizobium japonicum
USDA 125-Sp, USDA 138, and USDA 138-Sm had been used as inoculants for soybean (
Glycine max
(L.) Merr.) in soils previously free of
B. japonicum.
At 8 to 13 years after their release, these strains were reisolated from soil samples. A total of 115 isolates were obtained through nodules, and seven colonies were obtained directly by a serological method. The stability of the inoculants was confirmed by comparing the reisolated cultures with their respective parental strains which had been preserved by being lyophilized or stored on a yeast extract-mannitol agar slant at 4°C. Comparisons were made on morphological and serological characters, carbon compound utilization (8 tested), intrinsic antibiotic resistance (9 tested), and enzymatic activity (19 tested). Mucous and nonmucous isolates of serogroup 125 were analyzed for symbiotic effectiveness and restriction fragment hybridization with a DNA probe. Our data suggest that the
B. japonicum
inoculants have survived for up to 13 years in the soils without significant mutation except for two reisolates with a slightly increased kanamycin resistance level.
Activation thermodynamics of virus adsorption to solids
Authors: Preston D R , Farrah S R
Published: January 2020

The kinetics of bacteriophage MS2, T2, and f2 adsorption to powdered nitrocellulose and disrupted Seitz S1 filters at pH 7 were determined as a function of temperature. Data from these studies were combined with data produced in a previous study on MS2 adsorption to clay by Stagg et al. (Appl. Environ. Microbiol. 33:385-391, 1977). These workers studied the adsorption of MS2 to bentonite clay as a function of temperature. Data from both this previous study and the current one were used to calculate the thermodynamic parameters of virus adsorption. The results show that adsorption of bacteriophages to the solids tested is a physical process (energy of activation, less than 40 kcal [168 J]/mol) rather than a chemical process (energy of activation, greater than 40 kcal/mol). The free energy of activation showed a high negative correlation (r = -0.904, r2 = 0.817) with the percentage of virus adsorption to the solids tested. The energy of activation was highly negatively correlated with the percentage of virus adsorption to nitrocellulose and clay (r = -0.913, r2 = 0.834) but poorly correlated with the percentage of virus adsorption to disrupted Seitz S1 filters (r = -0.348, r2 = 0.121). In general, under conditions in which the percentage of virus adsorption was low, the energy of activation, the free energy of activation, and the entropy of activation were high. Increasing the percentage of virus adsorbed by changing the adsorbing conditions or changing the adsorbing solid decreased the energy of activation, the free energy of activation, and the entropy of activation.
Molecular cloning of 3-phenylcatechol dioxygenase involved in the catabolic pathway of chlorinated biphenyl from Pseudomonas putida and its expression in Escherichia coli
Authors: Khan A , Tewari R , Walia S
Published: January 2020

Genes encoding 3-phenylcatechol dioxygenases were cloned from the chlorobiphenyl-degrading Pseudomonas putida strain OU83, using broad-host-range cosmid vector pCP13. Restriction enzyme analysis of DNA from 2,3-dioxygenase-positive chimeric cosmids showed DNA inserts ranging in size from 6.0 to 30 kilobases. The origin of the DNA insert in hybrid clones was established by using 32P-labeled hybrid clones (pOH101 and pOH810). A 2.3-kilobase HindIII fragment was common to two clones. The 2,3-dioxygenase from the parent P. putida strain, OU83, and the recombinant clones (pOH101 and pOH8101) showed similar characteristics as determined by isoelectric focusing and polyacrylamide gel electrophoresis. The 2,3-dioxygenase from the Escherichia coli recombinant cosmid showed a pI of 5.0, a Km of 14 microM, and broad substrate activity with catechol, 4-chlorocatechol, 4-methylcatechol, and 2,3-dihydroxybiphenyl.
Growth-supporting activity for Legionella pneumophila in tap water cultures and implication of hartmannellid amoebae as growth factors
Authors: Wadowsky R M , Butler L J , Cook M K , Verma S M , Paul M A , Fields B S , Keleti G , Sykora J L , Yee R B
Published: January 2020

Photosynthetic cyanobacteria, heterotrophic bacteria, free-living amoebae, and ciliated protozoa may support growth of Legionella pneumophila. Studies were done with two tap water cultures (WS1 and WS2) containing L. pneumophila and associated microbiota to characterize growth-supporting activity and assess the relative importance of the microbiota in supporting multiplication of L. pneumophila. The water cultures were incubated in the dark at 35 degrees C. The growth-supporting factor(s) was separated from each culture by filtration through 1-micron-pore-size membrane filters. The retentate was then suspended in sterile tap water. Multiplication of L. pneumophila occurred when both the retentate suspension and the filtrate from either culture were inoculated into sterile tap water. L. pneumophila did not multiply in tap water inoculated with only the filtrate, even though filtration did not reduce the concentration of L. pneumophila or heterotrophic bacteria in either culture. Growth-supporting activity of the retentate suspension from WS1 was inactivated at 60 degrees C but unaffected at 0, 25, and 45 degrees C after 30-min incubations. Filtration experiments indicated that the growth-supporting factor(s) in WS1 was 2 to 5 micron in diameter. Ciliated protozoa were not detected in either culture. Hartmannellid amoebae were conclusively demonstrated in WS2 but not in WS1. L. pneumophila multiplied in tap water inoculated with the amoebae (10(3)/ml) and the 1-micron filtrate of WS2. No multiplication occurred in tap water inoculated with the filtrate only. Growth-supporting activity for L. pneumophila may be present in plumbing systems; hartmannellid amoebae appear to be important determinants of multiplication of L. pneumophila in some tap water cultures.
Influence of Ethylene Produced by Soil Microorganisms on Etiolated Pea Seedlings
Authors: Arshad Muhammad , Frankenberger W. T.
Published: January 2020

There is indirect evidence that soil microorganisms producing ethylene (C
2
H
4
) can influence plant growth and development, but unequivocal proof is lacking in the literature. A laboratory study was conducted to demonstrate the validity of this speculation. Four experiments were carried out to observe the characteristic “triple” response of etiolated pea seedlings to C
2
H
4
microbially derived from
l
-methionine as a substrate in the presence or absence of Ag(I), a potent inhibitor of C
2
H
4
action. In two experiments, the combination of
l
-methionine and
Acremonium falciforme
(as an inoculum) was used, while in another study the indigenous soil microflora was responsible for C
2
H
4
production. A standardized experiment was conducted with C
2
H
4
gas to compare the contribution of the microflora to plant growth. In all cases, etiolated pea seedlings exhibited the classical triple response, which includes reduction in elongation, swelling of the hypocotyl, and a change in the direction of growth (horizontal). The presence of Ag(I) afforded protection to the pea seedlings against the microbially derived C
2
H
4
. This study demonstrates that microbially produced C
2
H
4
in soil can influence plant growth.
Analysis of Indole-3-Acetic Acid and Related Indoles in Culture Medium from
Azospirillum lipoferum
and
Azospirillum brasilense
Authors: Crozier Alan , Arruda Paulo , Jasmim Janie M. , Monteiro Ana Maria , Sandberg Göran
Published: January 2020

Analysis of neutral and acidic ethyl acetate extracts from culture medium of
Azospirillum brasilense
703Ebc by high-performance liquid chromatography (HPLC) and combined gas chromatography-mass spectrometry demonstrated the presence of indole-3-acetic acid (IAA), indole-3-ethanol, indole-3-methanol, and indole-3-lactic acid. IAA in media of 20 strains of
A. brasilense
and
Azospirillum lipoferum
was analyzed quantitatively by both the colorimetric Salkowski assay and HPLC-based isotopic dilution procedures. There was little correlation between the estimates obtained with the two procedures. For instance, the Salkowski assay suggested that the culture medium from
A. brasilense
703Ebc contained 26.1 μg of IAA ml
−1
, whereas HPLC revealed the presence of only 0.5 μg of IAA ml
−1
. Equivalent estimates with
A. brasilense
204Ed were 10.5 and 0.01 μg of IAA ml
−1
, respectively. The data demonstrate that the Salkowski assay is not a reliable method for measuring the IAA content of
Azospirillum
culture medium and that estimates in excess of 10 μg of IAA ml
−1
should be viewed with particular caution. Metabolism of [2′-
14
C]IAA by
A. brasilense
703Ebc yielded radiolabeled indole-3-methanol, whereas roots of maize (
Zea mays
L.) seedlings gave rise to [
14
C]oxindole-3-acetic acid and an array of polar metabolites. Metabolism of [2′-
14
C]IAA by maize roots inoculated with
A. brasilense
703Ebc produced a metabolic profile characteristic of maize rather than
Azospirillum
species.
Cultivation of cottontail rabbit epidermal (Sf1Ep) cells on microcarrier beads and their use for suspension cultivation of Treponema pallidum subsp. pallidum
Authors: Riley B S , Cox D L
Published: January 2020

In vitro propagation of Treponema pallidum can be achieved by cocultivation with Sf1Ep cells. This study had two objectives: (i) to achieve suspension cultivation of Sf1Ep cells and (ii) to develop procedures for achieving the replication of T. pallidum in those cell cultures. Seven suspension cultures of Sf1Ep cells yielded an average of 7.2 x 10(8) T. pallidum (36-fold increase) after 12 days.
Improved Assay for Rhodanese in
Thiobacillus
spp
Authors: Singleton David R. , Smith David W.
Published: January 2020

Rhodanese (thiosulfate:cyanide sulfurtransferase; EC 2.8.1.1) catalyzes the conversion of thiosulfate and cyanide to thiocyanate and sulfite. Conventional rhodanese assays colorimetrically measure the formation of one or the other of the products. These assays suffer from the fact that there is significant nonbiological formation of these products in addition to the enzymatically catalyzed reaction. In the present report, we describe a modified procedure for assaying rhodanese in which a separate boiled control was prepared for each assay trial. The boiled control corrected for the nonbiological contributions to product formation.
Isolation and Characterization of a Mutant of
Arthrobacter
sp. Strain GLP-1 Which Utilizes the Herbicide Glyphosate as Its Sole Source of Phosphorus and Nitrogen
Authors: Pipke Rüdiger , Amrhein Nikolaus
Published: January 2020

Arthrobacter
sp. strain GLP-1, grown on glucose as a carbon source, utilizes the herbicide glyphosate [
N
-(phosphonomethyl)glycine] as its sole source of phosphorus as well as its sole source of nitrogen. The mutant strain GLP-1/Nit-1 utilizes glyphosate as its sole source of nitrogen as well. In strain GLP-1, P
i
was a potent competitive inhibitor of glyphosate uptake (

K
i

, 24 μM), while the affinity of P
i
for the uptake system of strain GLP-1/Nit-1 was reduced by 2 orders of magnitude (

K
i

, 2.3 mM). It is concluded that the inability of strain GLP-1 to utilize glyphosate as a source of nitrogen is due to the stringent control of glyphosate uptake by excess phosphate released during the degradation of the herbicide.
Simplified X-ray film method for detection of bacterial volatilization of mercury chloride by Escherichia coli
Authors: Nakamura K , Nakahara H
Published: January 2020

A simplified X-ray film method for detecting bacterial production of Hgo by Escherichia coli was developed. There was excellent agreement of results between this X-ray film method and radioactive mercury volatilization assays. Although not quantitative, the X-ray film method has the advantages of being rapid, simple to perform, and inexpensive.
Test of the validity of the Poisson assumption for analysis of most-probable-number results
Authors: Haas C N , Heller B
Published: January 2020

A test of the validity of the Poisson assumption for sample replicates in dilution series of finite length is proposed and its properties are examined by using Monte Carlo simulation. The test is based on an examination of the number of intervals between complete sterility and complete infection in a series. The test is applied to a data set of routine influent coliform samples at the Chicago water supply intake. By this test, the data set is rejected as being drawn from a Poisson replication. Tables for direct application to a 3-dilution, 5-tube decimal series are presented, and their application is illustrated.
Comparison of seven plating media for enumeration of Listeria spp
Authors: Loessner M J , Bell R H , Jay J M , Shelef L A
Published: January 2020

The suitability of seven media for the enumeration of Listeria spp. was evaluated at 30 degrees C for 48 h. The media tested were (i) the original McBride Listeria agar formulation (with glycine); (ii) modified McBride agar containing glycine anhydride; (iii) LiCl-phenylethanol-moxalactam (LPM) agar; (iv) acriflavine-ceftazidime agar; (v) Rodriguez isolation agar (RISA); (vi) modified Vogel-Johnson (MVJ) agar; (vii) cyclohexanedione-nalidixic acid-phenylethanol agar; and tryptose agar as control. A total of 66 organisms were used including 11 Listeria monocytogenes strains and 5 other Listeria spp. For L. monocytogenes strains only, all media performed highly similarly. Of the other Listeria spp., only two grew on MVJ agar and three each grew on LPM and RISA. Only LPM agar inhibited the 50 non-listeriae, including five yeasts, while MVJ agar inhibited all but one yeast. The McBride Listeria agar formulation that contained glycine anhydride was less selective than the original. When pure cultures of 10 bacteria (including one L. monocytogenes strain) were combined and plated on four media, L. monocytogenes colonies were easiest to enumerate on MVJ agar, followed by LPM and RISA. These media ranked in the same order when plated with homogenates of various foods to which was added L. monocytogenes Scott A, but LPM agar was the best overall since Scott A was inhibited by MVJ. Upon microscopic examination of listerial colonies from the plating media, atypical cell morphology was noted with cells being about twofold in size on LPM, MVJ, and acriflavine-ceftazidime agars. Overall, LPM agar was the most suitable of the media tested even though it was inhibitory to Listeria grayi and Listeria murrayi.
Identification and Characterization of a Bacteroid-Specific Dehydrogenase Complex in
Rhizobium leguminosarum
PRE
Authors: Lankhorst René M. Klein , Katinakis Panagiotis , van Kammen Albert , van den Bos Rommert C.
Published: January 2020

In membranes of
Rhizobium leguminosarum
bacteroids isolated from nitrogen-fixing pea root nodules, two different protein complexes with NADH dehydrogenase activity were detected. One of these complexes, with a molecular mass of 110 kilodaltons, was also found in membranes of free-living rhizobia, but the other, with a molecular mass of 550 kilodaltons, appeared to be present only in bacteroids. The bacteroid-specific complex, referred to as DH1, probably consists of at least four different subunits. Using antibodies raised against the separate polypeptides, we found that a 35,000-molecular-weight polypeptide (35K polypeptide) in the DH1 complex is bacteroid specific, while the other proposed subunits were also detectable in cytoplasmic membranes of free-living bacteria. Dehydrogenase complex DH1 is also present in bacteroids of a
R. leguminosarum nifA
mutant, indicating that the synthesis of the dehydrogenase is not dependent on the gene product of this
nif
-regulatory gene. A possible involvement of the bacteroid-specific DH1 complex in electron transport to nitrogenase is discussed.
Transfection of Lactobacillus bulgaricus protoplasts by bacteriophage DNA
Authors: Boizet B , Flickinger J L , Chassy B M
Published: January 2020

A protoplast transfection system has been developed for Lactobacillus bulgaricus. The procedure involves a polyethylene glycol-mediated fusion of bacteriophage DNA encapsulated in liposomes into mutanolysin-treated cells. With L. bulgaricus B004 and DNA isolated from the phage phi c5004, transfection reached a maximum when at least 95% of the cells were osmotically fragile. The incorporation of phage DNA into liposomes was essential; no transfectants were detected in the absence of liposomes. The largest number of transfectants was observed after longer periods (20 min) of fusion of mutanolysin-treated cells and liposomes with polyethylene glycol. The maximum efficiency of 5 x 10(7) PFU/microgram of DNA was reached after a 24-h incubation in growth media prior to plating transfected cells in an agar overlay to detect the appearance of plaques. A minimum of 4 h of incubation in growth medium after fusion was required to detect the production and release of virions. The possibility that the high frequencies observed were due to bursting of transfected cells and subsequent infection of additional cells was found not to be a factor. The number of transfectants observed was directly proportional to the quantity of DNA added. These results define conditions appropriate for the introduction of DNA into L. bulgaricus.
Degradation and O-methylation of chlorinated phenolic compounds by Rhodococcus and Mycobacterium strains
Authors: Häggblom M M , Nohynek L J , Salkinoja-Salonen M S
Published: January 2020

Three polychlorophenol-degrading Rhodococcus and Mycobacterium strains were isolated independently from soil contaminated with chlorophenol wood preservative and from sludge of a wastewater treatment facility of a kraft pulp bleaching plant. Rhodococcus sp. strain CG-1 and Mycobacterium sp. strain CG-2, isolated from tetrachloroguaiacol enrichment, and Rhodococcus sp. strain CP-2, isolated from pentachlorophenol enrichment, mineralized pentachlorophenol and degraded several other polychlorinated phenols, guaiacols (2-methoxyphenols), and syringols (2,6-dimethoxyphenols) at micromolar concentrations and were sensitive to the toxic effects of pentachlorophenol. All three strains initiated degradation of the chlorophenols by para-hydroxylation, producing chlorinated para-hydroquinones, which were then further degraded. Parallel to degradation, strains CG-1, CG-2, and CP-2 also O-methylated nearly all chlorinated phenols, guaiacols, syringols, and hydroquinones. O-methylation of chlorophenols was a slow reaction compared with degradation. The preferred substrates of the O-methylating enzyme(s) were those with the hydroxyl group flanked by two chlorine substituents. O-methylation was constitutively expressed, whereas degradation of chlorinated phenolic compounds was inducible.
Production of Succinic Acid from Citric Acid and Related Acids by
Lactobacillus
Strains
Authors: Kaneuchi Choji , Seki Masako , Komagata Kazuo
Published: January 2020

A number of
Lactobacillus
strains produced succinic acid in de Man-Rogosa-Sharpe broth to various extents. Among 86 fresh isolates from fermented cane molasses in Thailand, 30 strains (35%) produced succinic acid; namely, 23 of 39
Lactobacillus reuteri
strains, 6 of 18
L. cellobiosus
strains, and 1 of 6 unidentified strains. All of 10
L. casei
subsp.
casei
strains, 5
L. casei
subsp.
rhamnosus
strains, 6
L. mali
strains, and 2
L. buchneri
strains did not produce succinic acid. Among 58 known strains including 48 type strains of different
Lactobacillus
species, the strains of
L. acidophilus, L. crispatus, L. jensenii
, and
L. parvus
produced succinic acid to the same extent as the most active fresh isolates, and those of
L. alimentarius, L. collinoides, L. farciminis, L. fructivorans
(1 of 2 strains tested),
L. malefermentans
, and
L. reuteri
were also positive, to lesser extents. Diammonium citrate in de Man-Rogosa-Sharpe broth was determined as a precursor of the succinic acid produced. Production rates were about 70% on a molar basis with two fresh strains tested. Succinic acid was also produced from fumaric and malic acids but not from
dl
-isocitric, α-ketoglutaric, and pyruvic acids. The present study is considered to provide the first evidence on the production of succinic acid, an important flavoring substance in dairy products and fermented beverages, from citrate by lactobacilli.
Useful Host-Vector Systems in
Bacillus stearothermophilus
Authors: Zhang Min , Nakai Hiroaki , Imanaka Tadayuki
Published: January 2020

We isolated a highly transformable thermophile,
Bacillus stearothermophilus
SIC1, which exhibited the following features. The growth temperature ranged from 45 to 65°C in L broth. The maximum cell concentration in 2L broth (2% tryptone, 1% yeast extract, 0.5% NaCl, pH 7.2) was determined as an optical density at 660 nm of 7.8, and the generation time was 11 min at 60°C. Strain SIC1 was a prototroph and was transformed by the protoplast procedure not only with
repB
plasmids (high-copy-number plasmids such as pTB913 and pUB110) but also with
repA
plasmids (low-copy-number plasmids such as pTB53). Transformation efficiencies with
repB
and
repA
plasmids were about 2 × 10
6
to 5 × 10
6
and 5 × 10
4
transformants per μg of DNA, respectively. The transformant carrying plasmid pTB913Y/K could grow at 63°C in the presence of kanamycin. The regeneration frequency of protoplasts was 60%, and only 1 day was needed for regeneration at 55°C.
Underestimation of DNA Synthesis by [
3
H]Thymidine Incorporation in Marine Bacteria
Authors: Jeffrey Wade H. , Paul John H.
Published: January 2020

A direct comparison of [
3
H]thymidine incorporation with DNA synthesis was made by using an exponentially growing estuarine bacterial isolate and the naturally occurring bacterial populations in a eutrophic subtropical estuary and in oligotrophic offshore waters. Simultaneous measurements of [
3
H]thymidine incorporation into DNA, fluorometrically determined DNA content, and direct counts were made over time. DNA synthesis estimated from thymidine incorporation values was compared with fluorometrically determined changes in DNA content. Even after isotope dilution, nonspecific macromolecular labeling, and efficiency of DNA recovery were accounted for, [
3
H]thymidine incorporation consistently underestimated DNA synthesized by six- to eightfold. These results indicate that although the relationship of [
3
H]thymidine incorporation to DNA synthesis appears consistent, there are significant sources of thymine bases incorporated into DNA which cannot be accounted for by standard [
3
H]thymidine incorporation and isotope dilution assays.
Disk Inoculum-Solid Medium Method To Test Carbon and Nitrogen Assimilation by Yeast Isolates
Authors: Moore Kerry J. , Johnson Michael G. , McClary Shane P.
Published: January 2020

Carbon and nitrogen assimilation for 50 yeasts isolated from White Riesling fermentation were tested by using a disk inoculum-solid medium method. This method was quicker and gave results comparable to the conventional liquid medium methods. Yeast characteristics (growth response, pigment production, morphology) could also be compared with this method.
Intergeneric and intrageneric conjugal transfer of plasmid-encoded antibiotic resistance determinants in Leuconostoc spp
Authors: Pucci M J , Monteschio M E , Kemker C L
Published: January 2020

Transfer of the broad-host-range resistance plasmids pIP501 and pAM beta 1 from Streptococcus faecalis to Leuconostoc dextranicum and Leuconostoc cremoris occurred between cells that were immobilized on nitrocellulose filters in the presence of DNase. Transfer of pIP501 to Leuconostoc spp. also occurred when Streptococcus sanguis and Streptococcus lactis were used as donors. In addition, transfer of pIP501 and pAM beta 1 was observed from L. cremoris and L. dextranicum transconjugants to S. sanguis and S. faecalis. Expression of the pAM beta 1 erythromycin and pIP501 erythromycin and chloramphenicol resistance determinants was essentially equivalent in donors and transconjugants. Frequencies of transfer generally ranged from 10(-4) to 10(-7) transconjugants per input donor cell. Intrageneric transfer of pIP501 and pAM beta 1 occurred between L. cremoris and L. dextranicum strains in the same approximate range. These data further extend the host range of pIP501 and pAM beta 1 and demonstrate another example of gene transfer in the genus Leuconostoc.