bluuebunny/crossref_metadata_2025 huggingface dataset:
Uptake of Glyphosate by an
Arthrobacter
sp
Authors: Pipke Rüdiger , Schulz Arno , Amrhein Nikolaus
Published: January 2020

The uptake of glyphosate (
N
-[phosphonomethyl]glycine) by an
Arthrobacter
sp. which can utilize this herbicide as its sole source of phosphorus was investigated. Orthophosphate suppressed the expression of the uptake system for glyphosate and also competed with glyphosate for uptake. The

K
m

for glyphosate uptake was 125 μM, and the

K
i

for orthophosphate was 24 μM. Organophosphonates as well as organophosphates inhibited glyphosate uptake, but only organophosphates and orthophosphate suppressed the uptake system. Glyphosate uptake was energy dependent, had a pH optimum of 6 to 7, and was differentially affected by divalent cations.
Synthesis of catalase in Staphylococcus aureus MF-31
Authors: Martin S E , Chaven S
Published: January 2020

During the growth of Staphylococcus aureus MF-31, initial catalase activity dropped to a reduced level at the onset of exponential phase before increasing. When S. aureus was grown at 25, 32, or 37 degrees C, catalase activity was found to decrease by 80 to 90% within 1 h of inoculation. Two catalase-negative mutants and wild-type S. aureus MF-31 cells were exposed to exogenous 20 mM H2O2 for 15 min. For wild-type S. aureus, there was no effect from H2O2 until min 15, at which time a 10% decrease in CFU was observed. Both mutants showed increased sensitivity to the H2O2, with 56 and 71% reductions in the CFU for mutants C3 and C4, respectively, after a 15-min exposure. Cells of mutant and wild-type S. aureus were subjected to sublethal heating at 52 degrees C for 20 min. The lack of catalase activity in the mutants resulted in large decreases in enumeration.
Cellulases and xylanase of an anaerobic rumen fungus grown on wheat straw, wheat straw holocellulose, cellulose, and xylan
Authors: Lowe S E , Theodorou M K , Trinci A P
Published: January 2020

The activities of cellulolytic and xylanolytic enzymes produced by an anaerobic fungus (R1) which resembled Neocallimastix sp. were investigated. Carboxymethylcellulase (CMCase), cellobiase, and filter paper (FPase) activities had pH optima of 6.0, 5.5, and 6.0, respectively. CMCase and cellobiase activities both had a temperature optimum of 50 degrees C, whereas FPase had an optimum of 45 degrees C. The pH and temperature optima for xylanase activity were pH 6.0 and 50 degrees C, respectively. Growth of the fungus on wheat straw, wheat straw holocellulose, or cellulose resulted in substantial colonization, with at least 43 to 58% losses in substrate dry matter and accumulation of comparable amounts of formate. This end product was correlated to apparent loss of substrate dry weight and could be used as an indicator of fungal growth. Milling of wheat straw did not enhance the rate or extent of substrate degradation. Growth of the R1 isolate on the above substrates or xylan also resulted in accumulation of high levels of xylanase activity and lower cellulase activities. Of the cellulases, CMCase was the most active and was associated with either low or trace amounts of cellobiase and FPase activities. During growth on xylan, reducing sugars, including arabinose and xylose, rapidly accumulated in the medium. Xylose and other reducing sugars, but not arabinose, were subsequently used for growth. Reducing sugars also accumulated, but not as rapidly, when the fungus was grown on wheat straw, wheat straw holocellulose, or cellulose. Xylanase activities detected during growth of R1 on media containing glucose, xylose, or cellobiose suggested that enzyme production was constitutive.(ABSTRACT TRUNCATED AT 250 WORDS)
Altered Electron Flow in Continuous Cultures of
Clostridium acetobutylicum
Induced by Viologen Dyes
Authors: Rao Govind , Mutharasan R.
Published: January 2020

The physiological response of
Clostridium acetobutylicum
to methyl and benzyl viologen was investigated. Viologen dyes at low concentrations (at levels of parts per million [micrograms per milliliter]) caused significant metabolic shifts. Altered electron flow appeared to direct carbon flow from acid to alcohol production accompanied by decreased hydrogen evolution. Reducing equivalents normally released as free hydrogen were directed toward formation of NADH which, in turn, resulted in increased alcohol production. In addition, it was shown that solvent production can take place at pH 6.3. Contrary to previous reports, butanol production appears to be independent of high levels of acetate-butyrate and glucose.
Citrate Metabolism by
Pediococcus halophilus
Authors: Kanbe Chiyuki , Uchida Kinji
Published: January 2020

Several strains of non-citrate-metabolizing
Pediococcus halophilus
have previously been isolated from soy sauce mash or moromi. The factors controlling the metabolism of citrate in soy pediococci were studied. All the soy pediococcal strains tested which failed to decompose citrate did not possess citrate lyase [citrate (
pro
-3
S
)-lyase; EC 4.1.3.6] activity. In
P. halophilus
, citrate lyase was an inducible enzyme, and the optimum pH for activity was 7.0. The metabolism of citrate in
P. halophilus
was different from that observed in lactic streptococci. The main products from citrate were acetate and formate, and this bacterium produced no acetoin or diacetyl. Formate production from citrate was greatly reduced in the presence of glucose.
P. halophilus
7117 (Cit
+
) was proved to contain citrate lyase, pyruvate formate-lyase (EC 2.3.1.54) phosphotransacetylase (phosphate acetyltransferase; EC 2.3.1.8), and acetate kinase (EC 2.7.2.1), i.e., all the enzymes necessary to convert citrate to acetate and formate.
Selective Process for Efficient Isolation of Soil
Bacillus
spp
Authors: Travers Russell S. , Martin Phyllis A. W. , Reichelderfer Charles F.
Published: January 2020

We were able to isolate
Bacillus thuringiensis
from environmental samples with a background of 10
9
bacteria per g of soil. Our selection process differed significantly from classical selection methods which permit only the desired organism to grow. In our process, germination of
B. thuringiensis
spores was selectively inhibited by sodium acetate, while most of the undesired sporeformers germinated. Next, all of the nonsporulated microbes were eliminated by heat treatment at 80�C for 3 min. The surviving spores were then plated on a rich agar medium and allowed to grow until they sporulated. Of random colonies picked from agar, 20 to 96% were crystal-forming
Bacillus
species.
B. thuringiensis
and
B. sphaericus
were routinely selected by this method.
Changes in antimicrobial resistance in fecal bacteria associated with pig transit and holding times at slaughter plants
Authors: Molitoris E , Fagerberg D J , Quarles C L , Krichevsky M I
Published: January 2020

Fecal coliforms, fecal streptococci, and antimicrobial resistance (AMR) associated with various pig transit and holding times were investigated at slaughter plants. Changes in the relative abundance of two biotypes of Streptococcus faecium were associated with transit and holding of pigs, although approximately 20% of the isolates were unidentified. The greatest variety of coliforms was isolated from porcine feces after short transit (2 h) or holding (3 h) times and was qualitatively similar to those from pigs on farms. Isolates from pigs with longer average transit or holding times were almost all Escherichia coli (four biotypes). Streptococcal resistance to most antimicrobial agents was significantly greater (P less than 0.05) in isolates from live pigs at slaughter plants than in those from pigs at farms and was apparent after a short transit time (2 h). Streptococci from pigs held an average of 15 h were less resistant to most antimicrobial agents than those from pigs held 3 or 43 h. When compared with short transit times, moderate transit times (6 h) were associated with significantly decreased (P less than 0.05) coliform resistance and decreased resistance transfer but a greater diversity of AMR patterns. Holding pigs overnight (14 h) was associated with lowered coliform resistance to several antimicrobial agents, compared with the resistance of isolates from pigs held 3 or 39 h. A substantial increase (18 to 48%) in the ability to transfer streptomycin resistance was demonstrated in coliforms from pigs held 39 h, when compared with those from pigs held 3 h.(ABSTRACT TRUNCATED AT 250 WORDS)
Effect of NaCl, pH, temperature, and atmosphere on growth of Salmonella typhimurium in glucose-mineral salts medium
Authors: Thayer D W , Muller W S , Buchanan R L , Phillips J G
Published: January 2020

The interactions of pH (5.0, 6.0, and 7.0), temperature (19, 28, and 37 degrees C), and atmosphere (aerobic versus anaerobic) with NaCl (0, 1, 2, 3, 4, and 5%) on the growth of Salmonella typhimurium ATCC 14028 in defined glucose-mineral salts culture medium were evaluated. Response surface methodology was used to develop equations describing the response of S. typhimurium to environmental changes. The response to an increasing concentration of NaCl at any temperature tested was nonlinear. The maximum growth was predicted to occur at an NaCl concentration of 0.5%, a temperature of 19 degrees C, and an initial pH of 7.0 under aerobic growth conditions. The relative amounts of aerobic growth at 19 degrees C, pH 7.0, and NaCl concentrations of 0, 0.5, 1, 2, 3, 4, and 5% were predicted to be 99.2, 100.0, 98.8, 90.2, 73.5, 48.6, and 15.6%, respectively. Anaerobic growth conditions repressed the amount of growth relative to that under aerobic conditions, and the effects of NaCl and pH were additive at low salt concentrations; however, at higher salt levels anaerobiosis provided protection against the effects of NaCl.
Bacterial colonization and endotoxin content of a new renal dialysis water system composed of acrylonitrile butadiene styrene
Authors: du Moulin G C , Coleman E C , Hedley-Whyte J
Published: January 2020

We measured endotoxin and bacterial levels in tap water, in water purified by reverse osmosis, and in dialysate samples over a 4-month period in a new 10-bed renal dialysis unit. Water treated by reverse osmosis is conducted to the 10 stations through 111 m of piping composed of acrylonitrile butadiene styrene (ABS). All determinations were made prior to the opening of the unit and after the system was purged for 35 h with all bedside station taps open. Formaldehyde disinfection of the piping system was attempted with a recommended protocol after 11 weeks by feeding 2.5 liters of 37% formaldehyde (0.85%, vol/vol) into the delivery system. Prior to water purging, 24 ng of endotoxin per ml was detected. This level decreased to 2.0 ng of endotoxin after the purging. Levels of endotoxin remained below 1.0 ng of endotoxin per ml throughout the duration of the study. In contrast, the level of viable microorganisms recovered from the treated water was approximately 3.5 X 10(4) CFU/100 ml. Even after disinfection of the system, there was no significant decrease in culturable bacteria from the water even though endotoxin levels were lower. Species isolated from the renal dialysis system were predominately pseudomonads, whereas species isolated from the tap water were Bacillus and Flavobacterium species. ABS provides a surface suitable for long-term colonization and growth of bacteria. Currently recommended decontamination protocols are ineffective in removing potentially pathogenic bacteria from ABS pipes and thus constitute an increased risk to patients undergoing dialysis.
Application of Most-Probable-Number Statistics to Direct Enumeration of Microorganisms
Authors: Roser D. J. , Bavor H. J. , McKersie S. A.
Published: January 2020

A novel method for rapid determination of total microbial cell numbers was investigated. The method involves the application of most-probable-number estimation statistics to direct microscopic counting of microbial cells by using a particle sizing graticule. Its accuracy and reliability were tested with computer simulations of bacterial cell distributions encountered in ecological studies. Good estimates of cell numbers were obtained when the cell density varied from 3 to 6,000 cells per field, i.e., over 3 orders of magnitude. Low levels of contagion did not markedly influence cell estimates, although high levels, corresponding to discrete scattered microcolonies, did. However, these could be recognized visually. Estimates of cell numbers in Breed smears confirmed its speed and good correlation with the standard quadrat counting technique under real experimental conditions.
Proteolysis in the gut of mosquito larvae results in further activation of the Bacillus sphaericus toxin
Authors: Broadwell A H , Baumann P
Published: January 2020

Gut proteases from the larvae of the mosquito Culex pipiens convert the 43-kilodalton (kDa) toxin from Bacillus sphaericus 2362 to a 40-kDa peptide. The 50% lethal concentration of this peptide for tissue culture-grown cells of Culex quinquefasciatus was 1.0 microgram/ml (as determined by the intracellular ATP assay), 54-fold less than that of the 43-kDa peptide. Gut proteases from Anopheles gambiae and Aedes aegypti, as well as bovine pancreatic trypsin, also converted the 43-kDa protein to a 40-kDa peptide which was indistinguishable from the peptide formed by the proteases from C. pipiens with respect to its toxicity to tissue culture-grown cells of C. quinquefasciatus. Evidence for the in vivo conversion of the 43-kDa protein to the 40-kDa peptide was also obtained from experiments in which larvae of C. pipiens, Anopheles gambiae, and Aedes aegypti were fed crystals from B. sphaericus 2362. By using the exclusion of trypan blue as an indication of cell viability, it was shown that chitobiose, chitotriose, N-acetylmuramic acid, and N-acetylneuraminic acid decreased the toxicity of the 40-kDa peptide (from 100 to 50% mortality at about 10 mM concentrations of these sugars). Muramic acid, N-acetylgalactosamine, and N-acetylglucosamine were less effective, while several sugars had no effect, suggesting that the 40-kDa toxin binds to specific receptors on the cell membrane. The 40-kDa protein was less toxic to tissue culture-grown cells of Anopheles gambiae and Aedes dorsalis, and the same sugars which reduced the toxicity for cells of C. quinquefasciatus were also effective in reduction of toxicity for these cell lines.(ABSTRACT TRUNCATED AT 250 WORDS)
Characterization of Agrobacterium tumefaciens strains isolated from grapevine tumors in China
Authors: Ma D Q , Yanofsky M F , Gordon M P , Nester E W
Published: January 2020

Thirteen strains of Agrobacterium tumefaciens isolated from grapevine tumors in northern China were surveyed. These strains varied in their host range properties, although all were tumorigenic on grapevines. Twelve of these strains belonged to Agrobacterium sp. biotype 3, and 11 strains resulted in the synthesis of the opine octopine in tumor tissue. Interestingly, one strain resulted in accumulation of arginine, a previously unrecognized opine, in tumor tissue. Although DNA in most of these strains showed homology to the previously characterized transferred DNA and vir loci, some virulent strains showed little or no homology to these loci. Thus, some of these strains represent widely divergent examples of Agrobacterium sp. The DNA in most strains exhibited little or no homology to a wide-host-range virA locus but did show strong homology to a limited-host-range virA locus. This finding further supports the idea that Agrobacterium strains associated with grapevines may have a specific virA locus.
Incidence of Vibrio cholerae from estuaries of the United States West Coast
Authors: Kaysner C A , Abeyta C , Wekell M M , DePaola A , Stott R F , Leitch J M
Published: January 2020

The incidence of Vibrio cholerae in shellfish, sediment, and waters of California, Oregon, and Washington was determined during the summer of 1984. Samples from 24 distinct estuaries were analyzed qualitatively. V. cholerae non-O1 was found in 23 estuaries and in 44.6% of the 529 samples examined. V. cholerae O1 Inaba was isolated from water samples in Morro Bay, Calif. Vibrio mimicus was found in 2.3% of the samples. Cholera enterotoxin was not found in cell-free filtrates of the 100 isolates tested in the Y-1 mouse adrenal cell assay, but heat-labile cytotoxic activity was observed with 3% of the isolates.
Regulation of β-1,4-Endoglucanase Synthesis in
Thermomonospora fusca
Authors: Lin Ershen , Wilson David B.
Published: January 2020

In
Thermomonospora fusca
YX, endocellulase synthesis varies over a 100-fold range depending on the carbon source used. This study shows that the variation is caused by two regulatory mechanisms: an induction mechanism that increases the rate of endocellulase synthesis about 20-fold and a growth rate-dependent repression mechanism that changes the rate of synthesis over a 6-fold range in both induced and noninduced cells. In
T. fusca
, endocellulase synthesis can be induced by cellulose, cellobiose, or cellodextrin. Cellulase is involved in inducer generation from cellulose. Growth rate-dependent repression can be reversed by limiting cultures for carbon, nitrogen, or, to a lesser extent, phosphorus. Further evidence for two separate regulatory mechanisms is provided by the isolation of mutants (CC-1 and CC-2) whose endocellulases are synthesized constitutively but are still sensitive to growth rate-dependent repression. These conclusions about total endocellulase synthesis were extended to the individual endocellulases by showing that three
T. fusca
endocellulases are coordinately regulated.
Reduction of Selenate to Selenide by Sulfate-Respiring Bacteria: Experiments with Cell Suspensions and Estuarine Sediments
Authors: Zehr Jonathan P. , Oremland Ronald S.
Published: January 2020

Washed cell suspensions of
Desulfovibrio desulfuricans
subsp.
aestuarii
were capable of reducing nanomolar levels of selenate to selenide as well as sulfate to sulfide. Reduction of these species was inhibited by 1 mM selenate or tungstate. The addition of 1 mM sulfate decreased the reduction of selenate and enhanced the reduction of sulfate. Increasing concentrations of sulfate inhibited rates of selenate reduction but enhanced sulfate reduction rates. Cell suspensions kept in 1 mM selenate were incapable of reducing either selenate or sulfate when the selenate/sulfate ratio was ≥0.02, indicating that irreversible inhibition occurs at high selenate concentrations. Anoxic estuarine sediments having an active flora of sulfate-respiring bacteria were capable of a small amount of selenate reduction when ambient sulfate concentrations were low (<4 mM). These results indicate that sulfate is an inhibitor of the reduction of trace quantities of selenate. Therefore, direct reduction of traces of selenate to selenide by sulfate-respiring bacteria in natural environments is constrained by the ambient concentration of sulfate ions. The significance of this observation with regard to the role sediments play in sequestering selenium is discussed.
Trichothecene mycotoxins in aerosolized conidia of Stachybotrys atra
Authors: Sorenson W G , Frazer D G , Jarvis B B , Simpson J , Robinson V A
Published: January 2020

Stachybotrys atra is the etiologic agent of stachybotryotoxicosis, and this fungus and its trichothecene mycotoxins were recently implicated in an outbreak of unexplained illness in homes. S. atra was grown on sterile rice, autoclaved, dried, and then aerosolized by acoustic vibration. The distribution of particles (mass and number) was monitored on an aerodynamic particle sizer interfaced with a computer. Dust was collected on preweighed glass-fiber filters and extracted with 90% aqueous methanol. Extracts were tested for the ability to inhibit protein synthesis in rat alveolar macrophages, the ability to inhibit the proliferation of mouse thymocytes, and the presence of specific trichothecene mycotoxins. Virtually all of the particles were less than 15 micron in aerodynamic diameter, and the mass median diameter was 5 micron. Thus, most of the particles were respirable. Microscopic analysis of the generated dust revealed that ca. 85% of the dust particles were conidia of S. atra, another 6% were hyphal fragments, and the remainder of the particles were unidentifiable. Thus, greater than 90% of the particles were of fungal origin. The extracts strongly inhibited protein synthesis and thymocyte proliferation. Purified satratoxin H was also highly toxic in the same systems. Each of the individual filters contained satratoxin H (average, 9.5 ng/mg of dust). Satratoxin G and trichoverrols A and B were found in lesser amounts in some, but not all, of the filters. The limit of analysis is ca. 50 ng. These results establish that the conidia of S. atra contain trichothecene mycotoxins. In view of the potent toxicity of the trichothecenes, the inhalation of aerosols containing high concentrations of these conidia could be a potential hazard to health.
Construction of
Streptococcus lactis
subsp.
lactis
Strains with a Single Plasmid Associated with Mucoid Phenotype
Authors: von Wright Atte , Tynkkynen Soile
Published: January 2020

Lactose-fermenting mucoid (Lac
+
Muc
+
) variants of plasmid-free
Streptococcus lactis
subsp.
lactis
MG1614 were obtained by protoplast transformation with total plasmid DNA from Muc
+
S. lactis
subsp.
cremoris
ARH87. By using plasmid DNA from these variants for further transformations followed by novobiocininduced plasmid curing, Lac
−
Muc
+
MG1614 strains containing only a single 30-megadalton plasmid could be constructed. This plasmid, designated pVS5, appeared to be associated with the Muc
+
phenotype.
Methods for Isolation of Auxotrophic Mutants of
Methanobacterium ivanovii
and Initial Characterization of Acetate Auxotrophs
Authors: Jain Mahendra K. , Zeikus J. Gregory
Published: January 2020

To develop a biochemical genetic approach to understanding cell carbon synthesis or metabolic pathways in methanogens,
Methanobacterium ivanovii
was selected as a model organism for genetic manipulation studies. The organism displayed a colony size of 3 to 6 mm in less than 2 weeks and had a plating efficiency of about 90%, which made it suitable for replica plating. Mutagenesis and selection techniques were developed for selection of acetate auxotrophs. Chemical mutagenesis with ethyl methanesulfonate, followed by enrichment with bacitracin as a selective agent, resulted in stable acetate auxotrophs.
M. ivanovii
was very sensitive to UV, but UV-induced acetate auxotrophs were unstable and reverted within two to four transfers. The acetate auxotrophs were analyzed in relation to wild type for carbon monoxide dehydrogenase enzyme activity.
Sulfate Reduction in Peat from a New Jersey Pinelands Cedar Swamp
Authors: Spratt Henry G. , Morgan Mark D. , Good Ralph E.
Published: January 2020

Microbial sulfate reduction rates in acidic peat from a New Jersey Pine Barrens cedar swamp in 1986 were similar to sulfate reduction rates in freshwater lake sediments. The rates ranged from a low of 1.0 nmol cm
−3
day
−1
in February at 7.5- to 10.0-cm depth to 173.4 nmol cm
−3
day
−1
in July at 5.0- to 7.5-cm depth. The presence of living
Sphagnum
moss at the surface generally resulted in reduced rates of sulfate reduction. Pore water sulfate concentrations and water table height also apparently affected the sulfate reduction rate. Concentrations of sulfate in pore water were nearly always higher than those in surface water and groundwater, ranging from 26 to 522 μM. The elevated pore water sulfate levels did not result from the evapotranspiratory concentration of infiltrating stream water or groundwater, but probably resulted from oxidation of reduced sulfur compounds, hydrolysis of ester sulfates present in the peat, or both. The total sulfur content of peat that had no living moss at the surface was 164.64 ± 1.5 and 195.8 ± 21.7 μmol g (dry weight)
−1
for peat collected from 2.5 to 5.0 and 7.5 to 10.0 cm, respectively. Organosulfur compounds accounted for 84 to 88% of the total sulfur that was present in the peat. C-bonded sulfur accounted for 91 to 94% of the organic sulfur, with ester sulfate being only a minor constituent. Reduced inorganic sulfur species in peat from 2.5 to 7.5 cm were dominated by H
2
S-FeS (68%), while pyritic sulfide was the predominant inorganic sulfur species in the peat from depths of 7.5 to 10.0 cm (75%).
Detailed Characterization and Comparison of Four Lactic Streptococcal Bacteriophages Based on Morphology, Restriction Mapping, DNA Homology, and Structural Protein Analysis
Authors: Coveney John A. , Fitzgerald Gerald F. , Daly Charles
Published: January 2020

Bacteriophages uc1001 and uc1002, which are lytic for
Streptococcus cremoris
UC501 and UC502, respectively, were characterized in detail. Comparisons were made with a previously characterized phage, P008, which is lytic for
Streptococcus lactis
subsp.
diacetylactis
F7/2, and uc3001, which is a lytic phage for
S. cremoris
UC503. Phages uc1001 and uc1002 had small isometric heads (diameters, 52 and 50 nm, respectively) and noncontractile tails (lengths, 152 and 136 nm, respectively), and uc1002 also had a collar. Both had 30.1 ± 0.6 kilobase pairs (kbp) of DNA with cross-complementary cohesive ends. Restriction endonuclease maps made with seven endonucleases showed no common fragments. Despite this there was a very high level of homology between uc1001 and uc1002, and results of cross-hybridization experiments showed that the organization of both phage genomes was similar. Heteroduplex analysis confirmed this and quantified the level of homology at 83%. The regions of nonhomology comprised 2.1−, 1.1−, and 1.0-kbp deletion loops and 13 smaller loops and bubbles. The sodium dodecyl sulfate-polyacrylamide gel electrophoretic structural protein profiles were related, with a major band of about 40,000 molecular weight and minor bands of 35,000 and 34,000 molecular weight in common. There were also differences, however, in that uc1001 had a second major band of 68,000 molecular weight and two extra minor bands. Except for the restriction maps, which were strain specific, phages uc1001, uc1002, and P008 were closely related by all the criteria listed above. Their DNAs also showed a very significant bias against the cleavage sites of 9 of 11 restriction endonucleases. Phage uc3001 was unrelated to uc1001, uc1002, or P008 in that it had a prolate head (53 by 39 nm) and a shorter tail (105 nm), contained approximately 22 kbp of DNA, had unrelated cohesive ends, showed no DNA homology with the isometric-headed phages, and displayed a very different structural protein profile.
Inactivation of Giardia muris cysts by free chlorine
Authors: Leahy J G , Rubin A J , Sproul O J
Published: January 2020

The chlorine resistance of cysts of the flagellate protozoan Giardia muris was examined. This organism, which is pathogenic to mice, is being considered as a model for the inactivation of the human pathogen Giardia lamblia. Excystation was used as the criterion for cyst viability. Experiments were performed at pH 5, 7, and 9 at 25 degrees C and pH 7 at 5 degrees C. Survival curves were "stepladder"-shaped, but concentration-time data generally conformed to Watson's Law. Chlorine was most effective at neutral pH and was only slightly less so in acidic solutions. Comparison of inactivation data based on equivalent hypochlorous acid concentrations, which corrects for chlorine ionization, showed that the cysts have a pH-dependent resistance to inactivation. Concentration-time (C X t') products for free chlorine obtained at 25 degrees C ranged from a low of 50 mg min/liter at pH 5 to a high of 218 mg min/liter at pH 9 and were as high as 1,000 mg min/liter at 5 degrees C. It appears that G. muris cysts are somewhat more resistant to inactivation than G. lamblia cysts and rank among the microorganisms that are most resistant to inactivation by free chlorine.
Protocol for sampling environmental sites for legionellae
Authors: Barbaree J M , Gorman G W , Martin W T , Fields B S , Morrill W E
Published: January 2020

A protocol for sampling environmental sites was developed and used to identify possible sources of Legionella species in support of epidemiologic investigations at two hospitals. In hospital A, legionellae were isolated from 43 of 106 (40%) different sites. Three separate Legionella pneumophila serotypes and a previously unrecognized species were present in different combinations in the positive samples. Two of five cooling towers contained the same L. pneumophila serogroup 1 monoclonal type (1,2,4,5) as was isolated from patients. The same monoclonal type was also isolated from make-up water for the two cooling towers, a hot water tank, water separators in four main air compressor systems for respiratory therapy, and cold and hot water faucets. In hospital B, 13 of 37 (38%) sample sites contained legionellae, all of which were L. pneumophila serogroup 1. The monoclonal type matching isolates from patients (1,2,4,5) was found at the highest concentration in a hot water tank, but it was also present at four other sample sites. Since legionellae not related to disease may be found in many of the sites sampled, an epidemiologic association with the probable source should be established before intervention methods, such as disinfection, are undertaken.
Expression of a
Thermomonospora fusca
Cellulase Gene in
Streptomyces lividans
and
Bacillus subtilis
Authors: Ghangas Gurdev S. , Wilson David B.
Published: January 2020

A cellulase gene from
Thermomonospora fusca
coding for endocellulase E
5
was introduced into
Streptomyces lividans
by using shuttle plasmids that can replicate in either
S. lividans
or
Escherichia coli.
Plasmid DNA isolated from
E. coli
was used to transform
S. lividans
, selecting for thiostrepton resistance. The transformants expressed and excreted the endocellulase, but the ability to produce the endocellulase was unstable. This instability was shown to result from deletion of the endocellulase gene from the plasmid. Plasmid DNA prepared from a culture in which plasmid modification had occurred was used to transform
E. coli
, selecting for Amp
+
cells, and all of the transformants were cellulase positive, showing that pBR322 and
T. fusca
DNA were deleted together. When a plasmid was constructed containing only
T. fusca
DNA in plasmid pIJ702, the transformants were more stable, and the level of endocellulase activity produced in the culture supernatant after growth on 0.2% glucose was close to the level produced by
T. fusca
cultures grown on 0.2% cellulose. About 50% of the total protein in the culture supernatant of the
S. lividans
transformant was endocellulase E
5
. The enzyme produced by the
S. lividans
transformant was identical to pure
T. fusca
E
5
in its electrophoretic mobility and was completely inhibited by antiserum to E
5
. Shuttle plasmids containing the E
5
gene that could replicate in
Bacillus subtilis
and
E. coli
were also constructed and used to transform
B. subtilis.
Again there was extensive deletion of the plasmid DNA during transformation and growth in
B. subtilis.
There was no evidence of E
5
activity, even in those
B. subtilis
transformants that retained the E
5
gene.
Variation in Quantitative Requirements for Na
+
for Transport of Metabolizable Compounds by the Marine Bacteria
Alteromonas haloplanktis
214 and
Vibrio fischeri
Authors: Droniuk Randal , Wong P. T. S. , Wisse Gesine , MacLeod Robert A.
Published: January 2020

The rates of uptake by
Alteromonas haloplanktis
of 19 metabolizable compounds and by
V. fischeri
of 16 of 17 metabolizable compounds were negligible in the absence of added alkali-metal cations but rapid in the presence of Na
+
. Only
d
-glucose uptake by
V. fischeri
occurred at a reasonable rate in the absence of alkali-metal cations, although the rate was further increased by added Na
+
, K
+
, or Li
+
. Quantitative requirements for Na
+
for the uptake of 11 metabolites by
A. haloplanktis
and of 6 metabolites by
V. fischeri
and the characteristics of the Na
+
response at constant osmotic pressure varied with each metabolite and were different from the Na
+
effects on the energy sources used. Li
+
stimulated transport of some metabolites in the presence of suboptimal Na
+
concentrations and for a few replaced Na
+
for transport but functioned less effectively. K
+
had a small capacity to stimulate lysine transport. The rate of transport of most of the compounds increased to a maximum at 50 to 300 mM Na
+
, depending on the metabolite, and then decreased as the Na
+
concentration was further increased. For a few metabolites, the rate of transport continued to increase in a biphasic manner as the Na
+
concentration was increased to 500 mM. Concentrations of choline chloride equimolar to inhibitory concentrations of NaCl were either not inhibitory or appreciably less inhibitory than those of NaCl. All metabolites examined accumulated inside the cells against a gradient of unchanged metabolite in the presence of Na
+
, even though some were very rapidly metabolized. The transport of
l
-alanine, succinate, and
d
-galactose into
A. haloplanktis
and of
l
-alanine and succinate into
V. fischeri
was inhibited essentially completely by the uncoupler 3,5,3′,4′-tetrachlorosalicylanilide. Glucose uptake by
V. fischeri
was inhibited partially by 3,5,3′,4′-tetrachlorosalicylanilide and also by arsenate and iodoacetate.
Induction and Characterization of Artificial Diploids from the Haploid Yeast
Torulaspora delbrueckii
Authors: Sasaki Takashi , Ohshima Yoshinobu
Published: January 2020

The yeast
Torulaspora delbrueckii
, which propagates as a haploid, was made into a diploid by treatment with dimethyl sulfoxide (DMSO) on the regeneration of protoplasts. The diploid state was stably inherited; the cell volume was three times that of the parent strain and the cellular DNA content was two times that of the parental strain. No essential difference was found between diploids induced by DMSO and those formed through intraspecific protoplast fusion. The diploid strains sporulated fairly well, with their cells converting directly into asci. Random spore analysis revealed that diploids induced through protoplast fusion gave rise to auxotrophic segregants (haploids) with the parental genetic marker or to segregants formed by recombination, while diploids induced by DMSO from a doubly auxotrophic parent gave rise to no recombinant, indicating that it was chromosomally homoallelic in nature. The magnesium level in the protoplast regeneration medium was found to be an important factor for inducing diploid formation. At 0.2 mM magnesium diploids appeared even in the absence of DMSO, while at 2 mM magnesium diploids never appeared unless DMSO was added to the regeneration medium. Evidence is provided that the diploids induced by DMSO or a low magnesium level are due to direct diploidization but not protoplast fusion. UV light irradiation of intact cells (without protoplasts), 10% of which survived, also produced diploids among this surviving population. From these results we conclude that the perturbation of protoplast regeneration or of cell division by the treatments mentioned above somehow induced direct diploidization of
T. delbrueckii.
Transfer of chromosomal genes and plasmids in Bacillus thuringiensis
Authors: Aronson A I , Beckman W
Published: January 2020

A low frequency of chromosomal gene transfer from Bacillus thuringiensis to Bacillus cereus was detected by cell mating, with a tryptophan marker being the most frequently transferred gene among four that were tested. The process was resistant to DNase and was not mediated by cell filtrates. Among several B. thuringiensis subspecies tested, transfer was best with a derivative of B. thuringiensis subsp. kurstaki HD1, which lost several plasmids. All of the B. cereus recombinants contained at least one plasmid from the donor B. thuringiensis; frequently, it was a plasmid that encoded a protoxin gene. In matings with B. thuringiensis subsp. kurstaki HD1, a 29-megadalton plasmid that contained a ca. 2.5-kilobase region of homology with the chromosome was always transferred. No detectable transfer of chromosomal genes was found in B. thuringiensis subsp. kurstaki HD1 strains lacking this plasmid, suggesting that there may be chromosome mobilization.
Ultrastructure of
Thiothrix
spp. and “Type 021N” Bacteria
Authors: Williams Terry M. , Unz Richard F. , Doman J. Thomas
Published: January 2020

The ultrastructural features of two groups of filamentous sulfur bacteria,
Thiothrix
spp. and an unnamed organism designated “type 021N,” were examined by transmission electron microscopy. Negative staining of whole cells and filaments with uranyl acetate revealed the presence of tufts of fimbriae located at the ends of individual gonidia of
Thiothrix
sp. strain A1 and “type 021N” strain N7. Holdfast material present at the center of mature rosettes was observed in thin sections stained with ruthenium red. A clearly defined sheath enveloped the trichomes of two of three
Thiothrix
strains but was absent from “type 021N” filaments. The outer cell wall appeared more complex in “type 021N” strains than in
Thiothrix
isolates. Bulbs or clusters of irregularly shaped cells, often present in filaments of “type 021N” bacteria, appeared to result from crosswalls which formed at angles oblique to the filament axis. The multicellular nature of these sulfur bacteria was apparent in that only the cytoplasmic membrane and peptidoglycan layer of the cell wall were involved in the septation process. Sulfur inclusions which developed in the presence of sodium thiosulfate were enclosed by a single-layered envelope and located within invaginations of the cytoplasmic membrane.
Widespread occurrence of bacterial thiol methyltransferases and the biogenic emission of methylated sulfur gases
Authors: Drotar A , Burton G A , Tavernier J E , Fall R
Published: January 2020

A majority of heterotrophic bacteria isolated from soil, water, sediment, vegetation, and marine algae cultures methylated sulfide, producing methanethiol. This was demonstrated with intact cells by measuring the emission of methanethiol with a sulfur-selective chemiluminescence detector, and in cell extracts by detection of sulfide-dependent thiol methyltransferase activity. Extracts of two Pseudomonas isolates were fractionated by gel-filtration and ion-exchange chromatography, and with sulfide as the substrate a single peak of thiol methyltransferase activity was seen in each case. Extracts of several bacterial strains also contained thiol methyltransferase activity with organic thiols as substrates. Thus, S-adenosylmethionine-dependent thiol methyltransferase activities are widespread in bacteria and may contribute to biogenic emissions of methylated sulfur gases and to the production of methyl thioethers.
In vivo formation of gene fusions in Pseudomonas putida and construction of versatile broad-host-range vectors for direct subcloning of Mu d1 and Mu d2 fusions
Authors: Simon V , Schumann W
Published: January 2020

The Mu d1 and Mu d2 prophages were integrated into the conjugative broad-host-range plasmid R751. The two plasmids were then transferred into Pseudomonas putida, and derivatives carrying intact Mu prophages were recovered. After induction of Mu at 42 degrees C, both operon and gene fusions were observed on 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal) plates. Broad-host-range vectors were constructed which allow direct cloning of both operon or gene fusions and their analysis in Escherichia coli and P. putida. By using one of these vectors, two operon fusions were isolated from the P. putida chromosome and comparatively analyzed in E. coli and P. putida.
Steroid sulfatase activity in a Peptococcus niger strain from the human intestinal microflora
Authors: Van Eldere J R , De Pauw G , Eyssen H J
Published: January 2020

A strictly anaerobic gram-positive coccus, identified as Peptococcus niger, that developed sulfatase activity towards steroid-3-sulfate esters was isolated from human fecal material. This strain desulfated the arylsulfate esters estrone-3-sulfate (100%) and beta-estradiol-3-sulfate (50%); only trace amounts of desulfated estriol-3-sulfate were found. In addition, alkylsulfatase activity was found towards the 3 alpha-sulfates of 5 alpha-androstane-17-one and 5 beta-androstane-17-one and towards the 3 beta-sulfates of 5 alpha-androstane-17-one, delta 5-androstene-17-one, 5 alpha-pregnane-20-one, and delta 5-pregnene-20-one, all of which were 100% desulfated. No sulfatase activity was found towards the 17-sulfate esters of beta-estradiol or delta 4-androstene-3-one-17 alpha-ol. The nonsteroid arylsulfate esters paranitrophenyl sulfate, paranitrocatechol sulfate, and phenolphthalein disulfate were desulfated 70, 40, and 40%, respectively. In addition to its sulfatase activity, this strain also developed C-17 oxidoreductase activity towards the estrogens and androsta(e)nes and C-3 oxidoreductase activity towards androsta(e)nes and pregna(e)nes.
Production of Thermostable α-Amylase, Pullulanase, and α-Glucosidase in Continuous Culture by a New
Clostridium
Isolate
Authors: Antranikian G. , Herzberg C. , Gottschalk G.
Published: January 2020

The production of α-amylase, pullulanase, and α-glucosidase and the formation of fermentation products by the newly isolated thermophilic
Clostridium
sp. strain EM1 were investigated in continuous culture with a defined medium and an incubation temperature of 60°C. Enzyme production and excretion were greatly influenced by the dilution rate and the pH of the medium. The optimal values for the formation of starch-hydrolyzing enzymes were a pH of 5.9 and a dilution rate of 0.075 to 0.10 per h. Increase of the dilution rate from 0.1 to 0.3 per h caused a drastic drop in enzyme production. The ethanol concentration and optical density of the culture, however, remained almost constant. Growth limitation in the chemostat with 1% (wt/vol) starch was found optimal for enzyme production. Under these conditions 2,800 U of pullulanase per liter and 1,450 U of α-amylase per liter were produced; the amounts excreted were 70 and 55%, respectively.
Free-Living Dinitrogen-Fixing Bacteria Isolated from Petroleum Refinery Oily Sludge
Authors: Laguerre Gisele , Bossand Bernard , Bardin Rene
Published: January 2020

Dinitrogen-fixing activity (acetylene reduction and
15
N
2
fixation) was found in an oily sludge originating from a petroleum refinery. Two representative dinitrogen-fixing bacterial strains were isolated from this oily waste. Their nitrogenase activity was effective when they were cultivated on sterilized sludge or simple carbon substrates (organic acid salts, sugars). Using the classical methods, these strains could not be unambiguously related to other diazotrophic taxa. The landfarming process is widely used for oily sludge disposal; this study shows that oily sludges are more than a simple carbon input into the soil but that they must also be considered as real sources of dinitrogen-fixing and probably degradative microorganisms.
Purification and Properties of an Extracellular Protease Produced by the Entomopathogenic Fungus
Beauveria bassiana
Authors: Bidochka Michael J. , Khachatourians George G.
Published: January 2020

Beauveria bassiana
GK2016 grown in a medium with gelatin as the sole carbon and nitrogen source produced an extracellular protease. The protease production was highest when the fungus was grown on a semiliquid medium and was purified about 18-fold, with a recovery of 21%. The protease molecular weight was estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be about 35,000. It had an optimum activity at pH 8.5 and 37°C and was rapidly inactivated at 50°C. Its enzymatic activity was that of an endopeptidase which hydrolyzed elastin, casein, and gelatin but was much less active on bovine serum albumin and collagen. No trypsinlike activity was detected on
N
-α-benzoyl-
dl
-arginine-
p
-nitroanilide. It was, however, inhibited by phenylmethylsulfonyl fluoride, indicating that a serine residue is present in the active site. The protease was unaffected by metal-chelating agents, sulfhydryl reagents, trypsin inhibitor, and chymotrypsin inhibitor.
Bacterial detoxification of diisopropyl fluorophosphate
Authors: Attaway H , Nelson J O , Baya A M , Voll M J , White W E , Grimes D J , Colwell R R
Published: January 2020

The ability of 18 gram-negative bacterial isolates to detoxify diisopropyl fluorophosphate, a structural analog of the agents soman and sarin, was investigated. Detoxification by both frozen cell sonicates and acetone powders was assayed by two methods, i.e., the hydrolytic release of fluoride, measured by a fluoride-specific ion electrode, and the disappearance of acetylcholinesterase inhibition in vitro. Frozen cell sonicates for all strains exhibited some activity (F- ion release). In general, acetone powder preparations produced higher activity than frozen cell sonicates did, and the highest activities were exhibited by strains with known parathion hydrolase activity. Two ranges in activity were observed, low level, ranging from 0.1 to 7.0 mumol/min per g of protein, and high level, detected only in parathion hydrolase-producing strains, from 47 to greater than 300 mumol/min per g of protein. Results indicate that parathion hydrolase was nonspecific in phosphoesterase activity. Also, it was an effective detoxicant at low concentrations and near-neutral pH.
Identification of
Lotus
Rhizobia by Direct DNA Hybridization of Crushed Root Nodules
Authors: Cooper J. E. , Bjourson A. J. , Thompson J. K.
Published: January 2020

Hybridization of crushed
Lotus pedunculatus
root nodules with
32
P-labeled total genomic DNA probes was used to identify
Rhizobium loti
and
Bradyrhizobium
sp. (
Lotus
rhizobia). Probes always hybridized with homologous target DNA and frequently with DNAs of other strains from the same genus. Intergeneric hybridization did not occur. Results were comparable to those from colony hybridization.
Seasonal and Spatial Distribution of Extracellular Enzymatic Activities and Microbial Incorporation of Dissolved Organic Substrates in Marine Sediments
Authors: Meyer-Reil Lutz-Arend
Published: January 2020

Seasonal and spatial distributions of extracellular enzymatic activities and microbial incorporations of dissolved organic substrates were followed in sediments of the brackish water Kiel Bight (Baltic Sea, Federal Republic of Germany). Enzymatic hydrolysis of polymeric organic compounds was determined by means of fluorogenic substrates (4-methylumbelliferyl-β-
d
-glucoside,
l
-leucine-4-methylcoumarinyl-7-amide hydrochloride); incorporation of dissolved organic substrates into microbial biomass was measured by using tritiated substances (acetate, leucine, and thymidine). Based on a recently developed core injection technique, substrates were injected in microliter portions into undisturbed sediment cores. Enzymatic and incorporation activities underwent strong seasonal variations related to the enrichment of organic material in the sediment surface following sedimentation events. The input of the phytoplankton bloom during autumn caused stimulation of both enzymatic hydrolysis of polymeric organic compounds and microbial incorporation of dissolved organic substrates. Following input by spring phytoplankton bloom, mainly incorporation activities were stimulated. In late spring the development of the benthic fauna obviously greatly influenced microbial activities. During summer individual periods of high microbial activities were observed which might be traced back to short-term sedimentation events. The high microbial incorporation of leucine and thymidine during winter demonstrated that the nutrient supply rather than temperature is the dominating factor determining microbial production. Stimulation of microbial activities arose from the sediment surface and spread out relatively quickly into deeper horizons. Generally, the sediments were characterized by distinct patterns of interrelationships between the individual parameters of microbial activities measured.