bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoadaptation and Protection against Active Forms of Oxygen in the Symbiotic Procaryote
Prochloron
sp. and Its Ascidian Host
Authors: Lesser Michael P. , Stochaj Wayne R.
Published: January 2020

Superoxide dismutase, ascorbate peroxidase, and catalase activities were studied in the symbiotic photosynthetic procaryote
Prochloron
sp. and its ascidian host
Lissoclinum patella.
The protein-specific activities of these antioxidant enzymes in the
Prochloron
sp. and
L. patella
collected at different depths from the Great Barrier Reef, Australia, were directly proportional to irradiance, whereas the pigment concentrations in the
Prochloron
sp. were inversely proportional to irradiance. The presence of a cyanide-sensitive superoxide dismutase, presumably a Cu-Zn metalloprotein, in the
Prochloron
sp. extends the possible phylogenetic distribution of this protein. The concentration of UV-absorbing mycosporine-like amino acids is inversely proportional to irradiance in both the host and symbiont, suggesting that these compounds may not provide sufficient protection against UV radiation in high-irradiance environments. The significant differences in the specific activities of these antioxidant enzymes, cellular photosynthetic pigment concentrations, and UV-absorbing compounds from high- and low-irradiance habitats constitute an adaptive response to different photic environments. These photoadaptive responses are essential to prevent inhibition of photosynthesis by high fluxes of visible and UV radiation.
Polymerase chain reaction for detection of invasive Shigella flexneri in food
Authors: Lampel K A , Jagow J A , Trucksess M , Hill W E
Published: January 2020

The polymerase chain reaction (PCR) was used to amplify a 760-base-pair (bp) fragment with the 220-kbp invasive plasmids of enteroinvasive Escherichia coli, Shigella flexneri, Shigella dysenteriae, Shigella boydii, and Shigella sonnei as templates. This PCR product was easily detected by agarose gel electrophoresis. A 210-bp AccI-PstI fragment lying within the amplified region was used as a probe in Southern hybridization blots and showed that the PCR-generated product was derived from the invasive plasmid. The application of PCR as a rapid method to detect enteroinvasive bacteria in foods was tested by inoculating lettuce with 10(4) S. flexneri cells per g in shigella broth base. Plasmid DNA was isolated from cultures of inoculated and uninoculated lettuce in broth after 0, 4, and 24 h of incubation. With the PCR, the 760-bp fragment was generated only from lettuce inoculated with S. flexneri, as shown by gel electrophoresis and confirmed both by Southern blotting and by nucleotide sequencing of the amplified region. Because the isolation of plasmid DNA, the performance of PCR, and gel electrophoresis all can be completed in 6 to 7 h, invasive enteric bacteria can be detected in less than 1 day.
Influence of antibiotics on intestinal tract survival and translocation of environmental Pseudomonas species
Authors: George S E , Kohan M J , Whitehouse D A , Creason J P , Claxton L D
Published: January 2020

The environmental release of microorganisms has prompted the investigation of potential health effects associated with their release. In this study, survival and translocation to the spleen and liver of several environmental Pseudomonas spp. were investigated in antibiotic-treated mice. Pseudomonas aeruginosa BC16 and P. maltophilia BC6, isolated from a commercial product for polychlorinated biphenyl degradation; P. aeruginosa AC869, a 3,5-dichlorobenzoate degrader; and P. cepacia AC1100, an organism that metabolizes 2,4,5-trichlorophenoxyacetic acid were examined for their survival capabilities in the intestines of mice dosed with clindamycin, kanamycin, rifampin, or spectinomycin. A mouse intestinal isolate, strain PAMG, was included in the study. Following antibiotic pretreatment (1 mg twice daily for 3 days), mice were dosed by gavage with 10(9) CFU of each Pseudomonas strain. At the end of the 5-day test period, strains AC869 and PAMG survived in kanamycin-, rifampin-, spectinomycin-, and clindamycin-treated animals. A statistically significant (P less than 0.05) increase in survival of strain PAMG was observed in clindamycin-, kanamycin-, and spectinomycin-treated mice for the test period. Treatment with clindamycin or rifampin increased (P less than 0.05) survival of strain BC6, an organism resistant to both antibiotics. However, strain BC6 was detected only in rifampin-treated mice at the end of the 5-day test period. Strain BC16, a clindamycin-resistant strain, was detected in clindamycin-treated mice and the untreated control animals. Rifampin had a negative effect (P less than 0.05) on strain AC869 and PAMG survival. Translocation to the spleen was observed in spectinomycin- and clindamycin-treated mice but was not detected in kanamycin- or rifampin-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)
KCl potentiation of the virucidal effectiveness of free chlorine at pH 9.0
Authors: Berg G , Sanjaghsaz H , Wangwongwatana S
Published: January 2020

In studies at 5 degrees C and pH 9.0, poliovirus 1 was inactivated about 15 times more rapidly by free chlorine (FC) in purified water in the presence of 1,262 mg of KCl per liter (approximately 0.0169 M) than in the absence of KCl. In the presence of 526 mg of KCl per liter, the virus was inactivated about seven times more rapidly by FC than in the absence of KCl. At a level of 21 mg/liter, KCl did not significantly potentiate the virucidal activity of FC in purified water. Although poliovirus 1 was inactivated almost three times more rapidly by FC in borate-buffered purified water than in purified water, the presence of the buffer did not alter the extent of potentiation by KCl. Most of FC exists as OCl- at pH 9.0. Tap water has been shown to markedly potentiate the polivirucidal effectiveness of FC at pH 9.0. For the same degree of virucidal potentiation of FC at this pH, a considerably greater quantity of KCl was required in purified water than the total salt content that appeared to be present in the tap water.
Effect of prior heat shock on heat resistance of Listeria monocytogenes in meat
Authors: Farber J M , Brown B E
Published: January 2020

The effect of prior heat shock on the thermal resistance of Listeria monocytogenes in meat was investigated. A sausage mix inoculated with approximately 10(7) L. monocytogenes per g was initially subjected to a heat shock temperature of 48 degrees C before being heated at a final test temperature of 62 or 64 degrees C. Although cells heat shocked at 48 degrees C for 30 or 60 min did not show a significant increase in thermotolerance as compared with control cells (non-heat shocked), bacteria heat shocked for 120 min did, showing an average 2.4-fold increase in the D64 degrees C value. Heat-shocked cells shifted to 4 degrees C appeared to maintain their thermotolerance for at least 24 h after heat shock.
Layered structure of bacterial aggregates produced in an upflow anaerobic sludge bed and filter reactor
Authors: MacLeod F A , Guiot S R , Costerton J W
Published: January 2020

The ultrastructure of bacterial granules that were maintained in an upflow anaerobic sludge bed and filter reactor was examined. The reactor was fed a sucrose medium, and it was operated at 35 degrees C. Scanning and transmission electron microscopy revealed that the granular aggregates were three-layered structures. The exterior layer of the granule contained a very heterogeneous population that included rods, cocci, and filaments of various sizes. The middle layer consisted of a slightly less heterogeneous population than the exterior layer. A more ordered arrangement, made up predominantly of bacterial rods, was evident in this second layer. The third layer formed the internal core of the granules. It consisted of large numbers of Methanothrix-like cells. Large cavities, indicative of vigorous gas production, were evident in the third layer. On the basis of these ultrastructural results, a model that presents a possible explanation of granule development is offered.
Ferrous Iron and Sulfur Oxidation and Ferric Iron Reduction Activities of
Thiobacillus ferrooxidans
Are Affected by Growth on Ferrous Iron, Sulfur, or a Sulfide Ore
Authors: Suzuki Isamu , Takeuchi Travis L. , Yuthasastrakosol Trin D. , Oh Jae Key
Published: January 2020

Eight strains of
Thiobacillus ferrooxidans
(laboratory strains Tf-1 [= ATCC 13661] and Tf-2 [= ATCC 19859] and mine isolates SM-1, SM-2, SM-3, SM-4, SM-5, and SM-8) and three strains of
Thiobacillus thiooxidans
(laboratory strain Tt [= ATCC 8085] and mine isolates SM-6 and SM-7) were grown on ferrous iron (Fe
2+
), elemental sulfur (S
0
), or sulfide ore (Fe, Cu, and Zn). The cells were studied for their aerobic Fe
2+
- and S
0
-oxidizing activities (O
2
consumption) and anaerobic S
0
-oxidizing activity with ferric iron (Fe
3+
) (Fe
2+
formation). Fe
2+
-grown
T. ferrooxidans
cells oxidized S
0
aerobically at a rate of 2 to 4% of the Fe
2+
oxidation rate. The rate of anaerobic S
0
oxidation with Fe
3+
was equal to the aerobic oxidation rate in SM-1, SM-3, SM-4, and SM-5, but was only one-half or less that in Tf-1, Tf-2, SM-2, and SM-8. Transition from growth on Fe
2+
to that on S
0
produced cells with relatively undiminished Fe
2+
oxidation activities and increased S
0
oxidation (both aerobic and anaerobic) activities in Tf-2, SM-4, and SM-5, whereas it produced cells with dramatically reduced Fe
2+
oxidation and anaerobic S
0
oxidation activities in Tf-1, SM-1, SM-2, SM-3, and SM-8. Growth on ore 1 of metal-leaching Fe
2+
-grown strains and on ore 2 of all Fe
2+
-grown strains resulted in very high yields of cells with high Fe
2+
and S
0
oxidation (both aerobic and anaerobic) activities with similar ratios of various activities. Sulfur-grown Tf-2, SM-1, SM-4, SM-6, SM-7, and SM-8 cultures leached metals from ore 3, and Tf-2 and SM-4 cells recovered showed activity ratios similar to those of other ore-grown cells. It is concluded that all the
T. ferrooxidans
strains studied have the ability to produce cells with Fe
2+
and S
0
oxidation and Fe
3+
reduction activities, but their levels are influenced by growth substrates and strain differences.
Latex and vinyl nonsterile examination gloves: status report on laboratory evaluation of defects by physical and biological methods
Authors: Kotilainen H R , Avato J L , Gantz N M
Published: January 2020

We have reported previously (H. R. Kotilainen, J. P. Brinker, J. L. Avato, and N. M. Gantz, Arch. Intern. Med. 149:2749-2753, 1989) that the quality of nonsterile examination gloves available for clinical use may be extremely variable. In view of the concern over human immunodeficiency virus and hepatitis B virus transmission to health care workers, the continuing variability of gloves available for use, and the need for a simple and safe test, we have evaluated 2,500 vinyl (five brands) and 2,000 latex (four brands) gloves by the 300-ml and the newly proposed 1,000-ml water tests and for permeability to herpes simplex virus type 1 and poliovirus type 1, respectively. While all 300-ml watertight gloves were unlikely to leak herpes simplex virus type 1 (1.3% vinyl; 0.5% latex), poliovirus was recovered much more frequently (8.9% vinyl, 6.1% latex). In all gloves that passed the 1,000-ml test, herpes simplex virus type 1 was not recovered. Poliovirus was recovered infrequently (1.4% vinyl, 1.5% latex). Preliminary analyses suggest that the 1,000-ml water test has significantly increased sensitivity over the 300-ml water test in the detection of small holes in both vinyl and latex gloves that may allow the passage of viral particles. Gloves that pass a 1,000-ml water challenge are unlikely to allow the passage of a small virus such as poliovirus. Given that human immunodeficiency virus, hepatitis B virus and herpes simplex virus type 1 are larger particles than poliovirus, gloves that pass the 1,000-ml water test theoretically could provide better protection.
Biodegradation of Trichloroethylene in Continuous-Recycle Expanded-Bed Bioreactors
Authors: Phelps T. J. , Niedzielski J. J. , Schram R. M. , Herbes S. E. , White D. C.
Published: January 2020

Experimental bioreactors operated as recirculated closed systems were inoculated with bacterial cultures that utilized methane, propane, and tryptone-yeast extract as aerobic carbon and energy sources and degraded trichloroethylene (TCE). Up to 95% removal of TCE was observed after 5 days of incubation. Uninoculated bioreactors inhibited with 0.5% Formalin and 0.2% sodium azide retained greater than 95% of their TCE after 20 days. Each bioreactor consisted of an expanded-bed column through which the liquid phase was recirculated and a gas recharge column which allowed direct headspace sampling. Pulses of TCE (20 mg/liter) were added to bioreactors, and gas chromatography was used to monitor TCE, propane, methane, and carbon dioxide. Pulsed feeding of methane and propane with air resulted in 1 mol of TCE degraded per 55 mol of substrate utilized. Perturbation studies revealed that pH shifts from 7.2 to 7.5 decreased TCE degradation by 85%. The bioreactors recovered to baseline activities within 1 day after the pH returned to neutrality.
Pyrolytic Methylation-Gas Chromatography of Whole Bacterial Cells for Rapid Profiling of Cellular Fatty Acids
Authors: Dworzanski Jacek P. , Berwald Luc , Meuzelaar Henk L. C.
Published: January 2020

A novel, on-line derivatization technique has been developed which enables generation of fatty acid methyl ester (FAME) profiles from microorganisms by gas chromatography-mass spectrometry without the need for laborious and time-consuming sample preparation. Microgram amounts of bacterial cells are directly applied to a thin ferromagnetic filament and covered with a single drop of methanolic solution of tetramethylammonium hydroxide. After air drying, the filament is inserted into a special gas chromatograph inlet equipped with a high-frequency coil, thus enabling rapid inductive heating of the ferromagnetic filament. This so-called Curie-point heating technique is shown to produce patterns of bacterial FAMEs which are qualitatively and quantitatively nearly identical to those obtained from extracts of methylated lipids prepared by conventional sample pretreatment methods. Relatively minor differences involve the loss of hydroxy-substituted fatty acids by the pyrolytic approach as well as strongly enhanced signals of FAMEs derived from mycolic acids. This type of pyrolysis enables on-line derivatization and thermal extraction of volatile derivatives for analysis, whereas the residual components remain on a disposable probe (ferromagnetic wire) of a pyrolytic device. The reduced sample size (micrograms instead of milligrams) and the lack of sample preparation requirements open up the possibility of rapid microbiological identification of single colonies (thus overcoming the need for time-consuming subculturing) as well as analysis of FAME profiles directly from complex environmental samples.
Monoclonal antibody specific for Listeria monocytogenes, Listeria innocua, and Listeria welshimeri
Authors: Siragusa G R , Johnson M G
Published: January 2020

Eight hundred fifty-nine murine hybridomas were produced from eight fusions, and 27 were characterized for secretion of antibodies reactive to Listeria monocytogenes. One monoclonal antibody (MAb), P5C9, reacted with all test strains of L. monocytogenes (31 of 31), L. innocua (3 of 3), and L. welshimeri (1 of 1) but not with any strains of the other four Listeria species or with any of 22 gram-positive or 11 gram-negative species of bacteria when tested in microtiter and dot blot enzyme immunoassays. Of the other 26 antibodies, 20 reacted with either L. monocytogenes Scott A or V7 and with some or all of the other six Listeria species but also cross-reacted with some or all of the non-Listeria bacteria tested. MAb P5C9 is of the immunoglobulin G1 murine subclass. In Western blot (immunoblot) analyses, this MAb reacted with a single antigen with a molecular weight of 18,500, and it is shared in common with all three reactive species, L. monocytogenes, L. innocua, and L. welshimeri. This antigen was extracted with detergent and appeared to be cell bound.
Bacteriophage typing of Listeria species
Authors: Loessner M J , Busse M
Published: January 2020

A bacteriophage typing scheme for differentiating Listeria isolates from dairy products and various other foodstuffs was developed. Sixteen selected phages isolated from both environmental sources and lysogenic strains were used for typing and, according to their lytic spectra, divided into four groups. Thus far, 41 distinct patterns of lysis were seen when this set was used in typing 57 defined reference strains, representing all five confirmed species and 16 serotypes in addition to 454 Listeria isolates of primarily foodborne origin. Overall, typability was 84.5%; i.e., a strain was lysed by at least one phage at 100x routine test dilution. Strains belonging to serovar 3 were mostly resistant to lysis by the phages employed. The results were highly reproducible, as determined in retyping trials several weeks later. Some phages isolated from environmental sources showed a wider lytic spectrum than did those isolated from lysogenic strains. In accordance with this, the phages were found in different clusters within a computer-generated linkage map. Species specificity and serovar specificity of the lytic reaction were not found. None of the phages was able to lyse strains of Listeria grayi, Listeria murrayi or Jonesia denitrificans. This phage typing system may provide important information for a means of recognizing and eliminating sources of contamination by Listeria spp. within dairy plant equipment.
Particle agglutination assays to identify fibronectin and collagen cell surface receptors and lectins in Aeromonas and Vibrio species
Authors: Ascencio F , Aleljung P , Wadström T
Published: January 2020

A rapid particle agglutination assay (PAA) utilizing latex beads coated with connective tissue and serum proteins was evaluated for its ability to identify fibronectin, collagen (types I and IV), fibrinogen, and transferrin cell surface receptors on Vibrio and Aeromonas strains isolated from diseased fish, human infections, and the environment. Similar tests were performed to screen for cell surface lectins. Vibrio as well as Aeromonas strains were found to bind connective tissue proteins (collagen types I, II, and IV and fibronectin), serum proteins (i.e., fibrinogen), and glycoproteins (bovine submaxillary mucin, hog gastric mucin, orosomucoid, and fetuin) immobilized on the latex particles. The specificity of the agglutination reaction was studied by particle agglutination inhibition assays performed by preincubating bacterial suspensions in solutions containing either gelatin (for the various connective tissue protein PAA reagents) or sialic acid-rich glycoproteins (for the various glycoprotein PAA reagents). Expression of cell surface receptors for connective tissue proteins was found to depend on culture methods.
Stability of antibiotics under growth conditions for thermophilic anaerobes
Authors: Peteranderl R , Shotts E B , Wiegel J
Published: January 2020

It was shown that the inhibitory effect of kanamycin and streptomycin in a growing culture of Clostridium thermohydrosulfuricum JW 102 is of limited duration. To screen a large number of antibiotics, their stability during incubation under the growth conditions of thermophilic clostridia was determined at 72 and 50 degrees C by using a 0.2% yeast extract-amended prereduced mineral medium with a pH of 7.3 or 5.0. Half-lives were determined in a modified MIC test with Escherichia coli, Staphylococcus aureus, and Bacillus megaterium as indicator strains. All compounds tested were similar at the two temperatures or more stable at 50 than at 72 degrees C. The half-life (t1/2) at pH 7.3 and 72 degrees C ranged from 3.3 h (k = 7.26 day-1, where k [degradation constant] = 1/t1/2) for ampicillin to no detectable loss of activity for kanamycin, neomycin, and other antibiotics. Apparently some compounds (e.g., lasalocid and neomycin) became more potent during incubation (k greater than 0). A change to pH 5.0 caused some compounds to become more labile (e.g., kanamycin) and others (e.g., streptomycin) to become more stable than at pH 7.3.
Characterization of Amylolytic Enzyme Activities Associated with the Hyperthermophilic Archaebacterium
Pyrococcus furiosus
Authors: Brown Stephen H. , Costantino Henry R. , Kelly Robert M.
Published: January 2020

The hyperthermophilic archaebacterium
Pyrococcus furiosus
produces several amylolytic enzymes in response to the presence of complex carbohydrates in the growth medium. These enzyme activities, α-glucosidase, pullulanase, and α-amylase, were detected in both cell extracts and culture supernatants. All activities were characterized by temperature optima of at least 100°C as well as a high degree of thermostability. The existence of this collection of activities in
P. furiosus
suggests that polysaccharide availability in its growth environment is a significant aspect of the niche from which it was isolated.
Dynamics of Aeromonas hydrophila, Aeromonas sobria, and Aeromonas caviae in a sewage treatment pond
Authors: Monfort P , Baleux B
Published: January 2020

The spatiotemporal dynamics of Aeromonas spp. and fecal coliforms in the sewage treatment ponds of an urban wastewater center were studied after 20 months of sampling from five stations in these ponds. Isolation and identification of 247 Aeromonas strains were undertaken over four seasons at the inflow and outflow of this pond system. The hemolytic activity of these strains was determined. The Aeromonas spp. and the fecal coliform distributions showed seasonal cycles, the amplitude of which increased at distances further from the wastewater source, so that in the last pond there was an inversion of the Aeromonas spp. cycle in comparison with that of fecal coliforms. The main patterns in these cycles occurred simultaneously at all stations, indicating control of these bacterial populations by seasonal factors (temperature, solar radiation, phytoplankton), the effects of which were different on each bacterial group. The analysis of the Aeromonas spp. population structure showed that, regardless of the season, Aeromonas caviae was the dominant species at the pond system inflow. However at the outflow the Aeromonas spp. population was dominated by A. caviae in winter, whereas Aeromonas sobria was the dominant species in the treated effluent from spring to fall. Among the Aeromonas hydrophila and A. sobria strains, 100% produced hemolysin; whereas among the A. caviae strains, 96% were nonhemolytic.
Listeria species in a California coast estuarine environment
Authors: Colburn K G , Kaysner C A , Abeyta C , Wekell M M
Published: January 2020

Listeria species and L. monocytogenes were found in 81 and 62%, respectively, of fresh or low-salinity waters (37 samples) in tributaries draining into Humboldt-Arcata Bay, Calif., during a winter (January-February) sampling period. The incidence of Listeria species and L. monocytogenes in sediment (46 samples) from the same sites where water was sampled was 30.4 and 17.4%, respectively. One of three bay water samples contained Listeria species (including L. monocytogenes), while of 35 samples of oysters examined, only 1 was found positive for Listeria species (L. innocua). A given species or L. monocytogenes serogroup appeared to predominate in fresh water when domesticated animals (cows, horses) were nearby, whereas greater variety with no species predominance was observed in areas with no direct animal influence.
Viable endospores of Thermoactinomyces vulgaris in lake sediments as indicators of agricultural history
Authors: Nilsson M , Renberg I
Published: January 2020

Bacteria of the genus Thermoactinomyces form endospores with an extreme longevity in natural habitats. We isolated Thermoactinomyces sacchari from 9,000-year-old varved (annually laminated) sediment; thus, T. sacchari is probably one of the oldest known living organisms. More importantly, we tested and verified the hypothesis that there is a relationship between concentrations of dormant, viable endospores of T. vulgaris in lake sediments and the extent of agriculture in the catchments of the lakes. In surface sediments, low concentrations were recorded in forest lakes and the concentrations increased with increasing areas of cultivated land around the lakes. In varved sediment cores from three lakes, we found a temporal relationship between records of T. vulgaris endospores and the pollen of plants indicating agriculture. Endospores were very rare in sediments deposited before agriculture, ca. 1100 A.D. From then to between 1300 and 1700 A.D., a period with restricted cultivation, low but more regular rates of accumulation of endospores were recorded. High endospore accumulation rates were found with the subsequent agricultural expansion. This investigation confirms suggestions that this bacterium could be used as a paleoindicator for agricultural activity and be complementary to pollen analyses. Viable bacteria in continuous records of lake sediments are also potential material for evolutionary studies.
Molecular analysis of deep-subsurface bacteria
Authors: Jiménez L
Published: January 2020

Bacterial isolates from deep-sediment samples from three sites at the Savannah River site, near Aiken, S.C., were studied to determine their microbial community composition and DNA structure by using total DNA hybridization and moles percent G + C. Standard phenotypic identification underestimated the bacterial diversity at the three sites, since isolates with the same phenotype had different DNA structures in terms of moles percent G + C and DNA homology. The G + C content of deep-subsurface bacteria ranged from 20 to 77 mol%. More than 60% of the isolates tested had G + C values similar to those of Pseudomonas spp., and 12% had values similar to those of Acinetobacter spp. No isolates from deeper formations showed the same DNA composition as isolates from upper formations. Total-DNA hybridization and DNA base composition analysis provided a better resolution than phenotypic tests for the understanding of the diversity and structure of deep-subsurface bacterial communities. On the basis of the moles percent G + C values, deep-subsurface isolates tested seemed to belong to the families Pseudomonadaceae and Neisseriaceae, which might reflect a long period of adaptation to the environmental conditions of the deep subsurface.
Protein phosphorylation in response to stress in Clostridium acetobutylicum
Authors: Balodimos I A , Rapaport E , Kashket E R
Published: January 2020

The possible involvement of protein phosphorylation in the clostridial stress response was investigated by radioactively labeling growing cells of Clostridium acetobutylicum with 32Pi or cell extracts with [gamma-32P]ATP. Several phosphoproteins were identified; these were not affected by the growth stage of the culture. Although the extent of protein phosphorylation was increased by heat stress, the phosphoproteins did not correspond to known stress proteins seen in one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Purified clostridial DnaK, a stress protein, acted as a kinase catalyzing the phosphorylation of a 50-kilodalton protein. The phosphorylation of this protein was enhanced in extracts prepared from heat-stressed cells. Diadenosine-5',5"'-P1,P4-tetraphosphate had no influence on protein phosphorylation.
X-Prolyl-Dipeptidyl Aminopeptidase of
Lactobacillus delbrueckii
subsp.
bulgaricus
: Characterization of the Enzyme and Isolation of Deficient Mutants
Authors: Atlan Danièle , Laloi Patrick , Portalier Raymond
Published: January 2020

Lactobacillus delbrueckii
subsp.
bulgaricus
CNRZ 397 is able to hydrolyze X-proline-
para
-nitroanilides and X-proline-β-naphthylamides (X for alanyl- or glycyl-). A single metal-independent cytoplasmic enzyme with a molecular weight estimated to be 82,000 is responsible for these activities and was named X-prolyl-dipeptidyl aminopeptidase (X-Pro-DPAP). Isolation and analysis of mutants totally deficient for X-Pro-DPAP activity showed that a total lack of this enzyme induces (i) a decrease in the growth rate; (ii) an increase in cell wall proteinase activity; (iii) the loss of three cell wall proteins with respective molecular masses of 16, 40, and 52 kilodaltons; and (iv) enhancement of a cell wall protein with a molecular mass of 150 kilodaltons. The involvement of X-Pro-DPAP in casein catabolism is discussed.
Taxonomic differentiation of 101 lactococcal bacteriophages and characterization of bacteriophages with unusually large genomes
Authors: Prevots F , Mata M , Ritzenthaler P
Published: January 2020

Sixty-three virulent bacteriophages of Lactococcus lactis were differentiated by DNA-DNA hybridization. The results, including those of a previous classification of 38 phages of the same bacterial species (P. Relano, M. Mata, M. Bonneau, and P. Ritzenthaler, J. Gen. Microbiol. 133:3053-3063, 1987) show that 48% of the phages analyzed belong to a unique DNA homology group (group III). Phages of this most abundant group had small isometric heads. Group I comprised 29% of the phages analyzed and was characterized by a small phage genome (19 to 22 kilobases) and a particular morphology with a prolate head. Like group III, this group contained representative phages of other classifications. Group II (21%) included virulent and temperate phages with small isometric heads. Two large isometric-headed phages, phi 109 and phi 111, were not related to the three DNA homology groups I, II, and III. The genome of phi 111 was unusually large (134 kilobases) and revealed partial DNA homology with another large isometric phage, 1289, described by Jarvis (type e) (A. W. Jarvis, Appl. Environ. Microbiol. 47:343-349, 1984). The protein compositions of phi 111 and 1289 were similar (three common major proteins of 21, 28, and 32 kilodaltons).
New Field Isolates of
Rhizobium leguminosarum
Biovar Viciae That Nodulate the Primitive Pea Cultivar Afghanistan in Addition to Modern Cultivars
Authors: Ma S.-W. , Iyer V. N.
Published: January 2020

A collection of 13 field isolates of
Rhizobium leguminosarum
bv. viciae that have the ability to nodulate the roots of current North American cultivars of peas as well as a “primitive” cultivar, Afghanistan, was examined. These isolates originated in diverse geographical regions of the world, which indicates that this phenotype is not restricted to isolates from any one region. When subclones of the nodulation region from one plasmid were used to examine
Eco
RI-fragment-length polymorphisms in this collection of strains as well as in a collection comprising strains that do not nodulate the primitive cultivar, polymorphism was found in both collections. With one exception, RisφA6, all strains that nodulated cv. Afghanistan pea contained a region called
nodX
as an extension to the
nodA BCIJ
operon that has been observed in all
R. leguminosarum
bv. viciae strains, including those that do not nodulate cv. Afghanistan pea. RisφA6 was also the only strain in which nodulating ability could not be associated with a conjugative plasmid.
Rapid Quantification of Planktonic Ciliates: Comparison of Improved Live Counting with Other Methods
Authors: Sime-Ngando Telesphore , Hartmann Hans Julian , Groliere Claude Alain
Published: January 2020

The following efficient and quantitatively valid method to filter concentrate and count live planktonic ciliates was developed and compared with other treatments: unconcentrated (raw) samples and centrifuged samples were counted live, and the effects of five different fixatives (HgCl
2
, Lugol's iodine, formaldehyde, glutaraldehyde, and Champy-DaFano) on the counts were monitored. Samples originated from a eutrophic mountain lake (Lake Aydat, near Clermont-Ferrand, France). Overall, live filtered counts were similar to counts of raw samples, but they were significantly higher (2 to 2.3 fold,
P
< 0.05) by analysis of variance than counts from centrifuged samples. Nevertheless, some taxa, i.e.,
Halteria
and
Loxodes
spp., were sensitive to filtration. The live filtered counts were also comparable to counts of raw HgCl
2
-fixed and settled samples. HgCl
2
and Lugol fixation consistently gave the highest total counts, while significantly lower counts were always obtained with Champy-DaFano-fixed samples. Losses due to fixation were insignificant for raw samples but were substantial and statistically significant in concentrated samples (15% after filtration and 71% after centrifugation, compared with counts from the corresponding live samples). Live counting of passively filter-concentrated ciliates has many advantages over other methods. It is two to four times quicker and more efficient. Ciliates are recognized with certainty, more species are identified, and enumeration of dead organisms (e.g., tintinnid loricas) is avoided. It should be recommended as a quantitatively valid alternative to classical methods for assessing planktonic ciliate populations.
Cloning of alpha- and beta-galactosidase genes from an extreme thermophile, Thermus strain T2, and their expression in Thermus thermophilus HB27
Authors: Koyama Y , Okamoto S , Furukawa K
Published: January 2020

The genes encoding thermostable alpha- and beta-galactosidases from an extremely thermophilic bacterium, Thermus strain T2, were cloned in Escherichia coli. The alpha-galactosidase gene was located just downstream from the beta-galactosidase gene. The genes were introduced into Thermus thermophilus HB27 with the aid of Thermus cryptic plasmid pTT8, and beta-galactosidases were expressed constitutively.
Nucleotide sequence and distribution of the pTR2030 resistance determinant (hsp) which aborts bacteriophage infection in lactococci
Authors: Hill C , Miller L A , Klaenhammer T R
Published: January 2020

The lactococcal plasmid pTR2030 encodes resistance to bacteriophage attack via two mechanisms, an abortive-infection mechanism, designated Hsp, and a restriction and modification system. We present the complete sequence of the hsp structural gene. The gene is 1,887 base pairs in length and encodes a protein with a predicted molecular mass of 73.8 kilodaltons. The upstream region was cloned in a promoter-screening vector and shown to direct the constitutive expression of the cat-86 gene. An internal probe was used to determine the distribution of the hsp sequence in industrially significant lactococcal strains and to evaluate its relatedness to another lactococcal plasmid implicated in an abortive-infection-type mechanism, pNP40. No homology was detected, suggesting that this gene is not widely distributed in lactococci. Therefore, there are at least two independent abortive-infection genotypes in lactococci.
Production and epitope analysis of monoclonal antibodies against a Rhizobium leguminosarum biovar trifolii strain
Authors: Wright S F
Published: January 2020

Heat-treated cells of Rhizobium leguminosarum biovar trifolii strain 162X95 were used to produce monoclonal antibodies (MAbs). The fusion produced three cross-reactive MAbs and eight MAbs specific for the immunizing strain and a group of five other R. trifolii strains from the same geographic region where 162X95 was isolated (California). Seven MAbs were analyzed by competitive enzyme-linked immunosorbent assay to determine the number of different epitopes detectable on strain 162X95. The results indicated that six MAbs reacted with the same or overlapping epitopes, and the seventh MAb gave inconclusive results.
Plate Assay for Simultaneous Detection of Alginate Lyases and Determination of Substrate Specificity
Authors: Gacesa Peter , Wusteman Frederick S.
Published: January 2020

A plate assay to detect the presence of alginate lyases (EC 4.2.2.3) has been developed. The simultaneous use of specific alginate block structures of defined composition allows the substrate specificity of the enzymes to be determined. Clearing zones in the alginate-containing media are visualized with either cetyl pyridinium chloride or ruthenium red.
Chromium reduction in Pseudomonas putida
Authors: Ishibashi Y , Cervantes C , Silver S
Published: January 2020

Reduction of hexavalent chromium (chromate) to less-toxic trivalent chromium was studied by using cell suspensions and cell-free supernatant fluids from Pseudomonas putida PRS2000. Chromate reductase activity was associated with soluble protein and not with the membrane fraction. The crude enzyme activity was heat labile and showed a Km of 40 microM CrO4(2-). Neither sulfate nor nitrate affected chromate reduction either in vitro or with intact cells.
Plasmid-associated sensitivity of Bacillus thuringiensis to UV light
Authors: Benoit T G , Wilson G R , Bull D L , Aronson A I
Published: January 2020

Spores and vegetative cells of Bacillus thuringiensis were more sensitive to UV light than were spores or cells of plasmid-cured B. thuringiensis strains or of the closely related Bacillus cereus. Introduction of B. thuringiensis plasmids into B. cereus by cell mating increased the UV sensitivity of the cells and spores. Protoxins encoded by one or more B. thuringiensis plasmids were not involved in spore sensitivity, since a B. thuringiensis strain conditional for protoxin accumulation was equally sensitive at the permissive and nonpermissive temperatures. In addition, introduction of either a cloned protoxin gene, the cloning vector, or another plasmid not containing a protoxin gene into a plasmid-cured strain of B. thuringiensis all increased the UV sensitivity of the spores. Although the variety of small, acid-soluble proteins was the same in the spores of all strains examined, the quantity of dipicolinic acid was about twice as high in the plasmid-containing strains, and this may account for the differences in UV sensitivity of the spores. The cells of some strains harboring only B. thuringiensis plasmids were much more sensitive than cells of any of the other strains, and the differences were much greater than observed with spores.
Substrate-velocity relationships for the Trichoderma viride cellulase-catalyzed hydrolysis of cellulose
Authors: Liaw E T , Penner M H
Published: January 2020

The influence of substrate and enzyme concentrations on the rate of saccharification of two defined insoluble cellulose substrates, Avicel (FMC Corp., Philadelphia, Pa.) and Solka-Floc (James River Co., Berlin, N.H.), by the cellulase enzyme system of Trichoderma viride was evaluated. In the assays, enzyme concentrations ranging from 0.004 to 0.016 IU/ml and substrate concentrations up to 10% (wt/vol) were used. Analysis by initial velocity methods found the maximum velocity of saccharification to be nearly equivalent for the two substrates and the Km for the two substrates to be of a similar magnitude, i.e., 0.20% (wt/vol) for Solka-Floc and 0.63% (wt/vol) for Avicel. Studies in which relatively high substrate concentrations (greater than 15 times the Km) were used demonstrated that the enzyme exhibited very different apparent substrate inhibition properties for the two substrates. The rate of saccharification of Avicel at relatively high substrate concentrations was up to 35% lower than the maximum rate which was observed at lower substrate concentrations. The Avicel concentration corresponding to the maximum rate of saccharification was dependent on the enzyme concentration. In contrast to the results with Avicel, the enzyme did not exhibit substrate inhibition with the Solka-Floc substrate. Potential differences in the degree of substrate inhibition with different substrates, as reported here, are particularly relevant to the experimental design of comparative studies.
Spectral Irradiance and Distribution of Pigments in a Highly Layered Marine Microbial Mat
Authors: Pierson Beverly K. , Sands Vicki M. , Frederick Judith L.
Published: January 2020

The spectral irradiance from 400 to 1,100 nm was measured with depth in the intertidal sand mats at Great Sippewissett Salt Marsh, Mass. These mats contained at least four distinct layers, composed of cyanobacteria, purple sulfur bacteria containing bacteriochlorophyll
a
(Bchl
a
), purple sulfur bacteria containing Bchl
b
, and green sulfur bacteria. Spectral irradiance was measured directly by layering sections of mat on a cosine receptor. Irradiance was also approximated by using a calibrated fiber-optic tip. With the tip, irradiance measurements could be obtained at depth intervals less than 250 μm. The irradiance spectra were correlated qualitatively and quantitatively with the distribution of the diverse chlorophyll pigments in this mat and were compared with spectra recorded in plain sand lacking pigmented phototrophs. We found that the shorter wavelengths (400 to 550 nm) were strongly attenuated in the top 2 mm of the mat. The longer wavelengths (red and near infrared) penetrated to much greater depths, where they were attenuated by Bchl
a, b
, and
c
-containing anoxygenic phototrophic bacteria. The specific attenuation bands in the irradiance spectra correlated with the specific in vivo absorption bands of the Bchl-protein complexes in the bacteria. We concluded that the pigments in the phototrophs had a profound affect on the light environment within the mat. It seems likely that the diverse Bchl-protein complexes found in the anoxygenic phototrophs evolved in dense mat environments as a result of competition for light.
Use of nuclear DNA restriction fragment length polymorphisms to analyze the diversity of the Aspergillus flavus group: A. flavus, A. parasiticus, and A. nomius
Authors: Moody S F , Tyler B M
Published: January 2020

Recombinant DNA clones carrying high-copy or low-copy sequences from Aspergillus nidulans and Neurospora crassa were used to identify restriction fragment length polymorphisms (RFLPs) diagnostic for members of the A. flavus group: A. flavus, A. parasiticus, and A. nomius. These fungi were resolved into three distinct categories when they were grouped according to RFLP patterns. Subgroups within these categories were also evident. This limited RFLP analysis of nuclear DNA of members of the A. flavus group did not identify any RFLPs that differentiate these isolates on the basis of toxin production, but limited correlation with geographic location was observed.
Characterization of Root Surface and Endorhizosphere Pseudomonads in Relation to Their Colonization of Roots
Authors: van Peer Ron , Punte Helma L. M. , de Weger Letty A. , Schippers Bob
Published: January 2020

An extensive colonization of the endorhizosphere by fluorescent pseudomonads was observed in tomato plants grown on artificial substrates. These studies reveal that a significantly higher percentage of pseudomonads obtained from the endorhizosphere (30%) reduced plant growth than those obtained from the root surface (4%). Lipopolysaccharide patterns, cell envelope protein patterns, and other biochemical characteristics indicated that
Pseudomonas
isolates obtained from the endorhizosphere are distinct from
Pseudomonas
isolates obtained from the root surface. Isolates from the endorhizosphere especially were able to recolonize the endorhizosphere of both sterile and nonsterile tomato roots. The ability of the endorhizosphere isolates to colonize the endorhizosphere significantly correlated with their agglutination by tomato root agglutinin but did not correlate with chemotaxis to seed exudates of tomato. No correlation between colonization of the endorhizosphere and agglutination by root agglutinin could be demonstrated for the root surface isolates. We propose that agglutination of specific
Pseudomonas
strains by root agglutinin is of importance in the initial phase of adherence of bacteria to the root surface.
Toxicity to Spodoptera exigua and Trichoplusia ni of individual P1 protoxins and sporulated cultures of Bacillus thuringiensis subsp. kurstaki HD-1 and NRD-12
Authors: Moar W J , Masson L , Brousseau R , Trumble J T
Published: January 2020

The toxicities to neonate Spodoptera exigua and Trichoplusia ni of lyophilized powders obtained from sporulated liquid cultures (referred to as sporulated cultures) and Escherichia coli-expressed P1 [cryIA(a) cryIA(b) cryIA(c)] protoxins from three-gene strains of NRD-12 and HD-1 of Bacillus thuringiensis subsp. kurstaki were determined by using diet incorporation bioassays. Although sporulated cultures from both strains were more toxic to T. ni than S. exigua, there were no differences in toxicity between NRD-12 and HD-1. Toxicities of the three individual P1 protoxins against S. exigua varied by at least fivefold, with the cryIA(b) protein being the most toxic. These same protoxins varied in toxicity against T. ni by at least 16-fold, with the cryIA(c) protein being the most toxic. However, when tested against either S. exigua or T. ni, there were no differences in toxicity between an NRD-12 P1 protoxin and the corresponding HD-1 P1 protoxin. Comparing the toxicities of individual protoxins with that of sporulated cultures demonstrates that no individual protoxin was as toxic to S. exigua as the sporulated cultures. However, this same comparison against T. ni shows that both the cryIA(b) and cryIA(c) proteins are at least as toxic as the sporulated cultures. Results from this study suggest that NRD-12 is not more toxic to S. exigua than HD-1, that different protein types have variable host activity, and that other B. thuringiensis components are not required for T. ni toxicity but that other components such as spores might be required for S. exigua toxicity.
Transport of β-Galactosides in
Lactobacillus plantarum
NC2
Authors: Jeffrey Scott R. , Dobrogosz Walter J.
Published: January 2020

The ability of
Lactobacillus plantarum
NC2 to transport thiomethyl-β-
d
-galactoside in the presence or absence of various inhibitors was investigated to determine the mechanism of β-galactoside transport in this bacterium. A novel system employing
l
-arabinose as an energy-generating compound is described, and evidence that this transport is energized by an ATP-driven proton motive force is presented.
Influence of solute, pH, and incubation temperature on recovery of heat-stressed Wallemia sebi conidia
Authors: Beuchat L R , Pitt J I
Published: January 2020

The influences of glucose, sorbitol, and NaCl in a basal enumeration medium at water activities (aw) from 0.82 to 0.97 on colony formation by sublethally heat-stressed Wallemia sebi conidia were determined. Over this aw range, glucose and sorbitol had similar effects on recovery, whereas at an aw of 0.82 to 0.92, NaCl had a detrimental effect. Colony diameters were generally largest on media containing sorbitol and smallest on media containing NaCl. Maximum colony size and viable population of heat-stressed conidia were observed on media at an aw of ca. 0.92. When the recovery incubation temperature was 20 degrees C, the number of uninjured conidia detected at an aw of 0.82 was reduced compared with the number detected at 25 degrees C, while at 30 degrees C, the number recovered at an aw of 0.97 was reduced. The effect on heat-stressed conidia was magnified. This suggests that W. sebi conidia may be more tolerant of aw values higher than the optimum 0.92 when the incubation temperature is decreased from the near optimum of 25 degrees C and less tolerant of aw values greater than 0.92 when the incubation temperature is higher than 25 degrees C. The sensitivity of heat-stressed conidia increased as the pH of the recovery medium was decreased from 6.55 to 3.71. W. sebi conidia dispersed in wheat flour at aw values of 0.43 and 0.71 and stored for up to 65 days at both 1 and 25 degrees C neither lost viability nor underwent sublethal desiccation or temperature injury.(ABSTRACT TRUNCATED AT 250 WORDS)