bluuebunny/crossref_metadata_2025 huggingface dataset:
Antimicrobial activity of tertiary amine covalently bonded to a polystyrene fiber
Authors: Endo Y , Tani T , Kodama M
Published: January 2020

Tertiary amine was covalently bonded to a polystyrene fiber and examined for antibacterial activity. The tertiary amine covalently bonded to a polystyrene fiber (TAF) showed a high antimicrobial activity against Escherichia coli. TAF exhibited a stronger antibacterial activity against gram-negative bacteria (E. coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhimurium, and Serratia marcescens) than against gram-positive bacteria (Staphylococcus aureus and Streptococcus faecalis) or Candida albicans. This activity against E. coli was accentuated by 0.1% deoxycholate or 10 mg of actinomycin D per ml, to which E. coli is normally not susceptible. This implies that TAF causes an increase of the bacterial outer membrane permeability. On the other hand, the antimicrobial activity was inhibited by adding Mg2+ or by lowering the pH. This suggest an electrostatic interaction between the bacterial cell wall and TAF. Scanning electron microscopy showed that E. coli cells were initially attached to TAF, with many projections on the cell surface, but then were apparently lysed after contact for 4 h. Taken together, these results imply that bacteria initially interact with TAF by an electrostatic force between the anionic bacterial outer membrane and the cationic tertiary amine residues of TAF and that longer contact with TAF damages the bacterial outer membrane structure and increases its permeability.
Evaluation of
Pseudomonas fluorescens
for Suppression of Sheath Rot Disease and for Enhancement of Grain Yields in Rice (
Oryza sativa
L.)
Authors: Sakthivel N. , Gnanamanickam S. S.
Published: January 2020

Pseudomonas fluorescens
strains antagonistic to
Sarocladium oryzae
, the sheath rot (Sh-R) pathogen of rice (
Oryza sativa
L.), were evaluated in greenhouse and field tests for suppression of Sh-R severity and enhancement of grain yields of rice. Imprints of rice seedlings and a direct-observation technique of staining roots with fluorochromes confirmed the association of
P. fluorescens
with roots and the ability of the strain to move along shoot tips. In greenhouse tests,
P. fluorescens
-treated rice plants (cv. IR 20) showed a 54% reduction in the length of Sh-R lesions. In three field tests, treatment with
P. fluorescens
reduced the severity of Sh-R by 20 to 42% in five rice cultivars. Bacterization of rice cultivars with
P. fluorescens
enhanced plant height, number of tillers, and grain yields from 3 to 160%.
Algal and Bacterial Activities in Acidic (pH 3) Strip Mine Lakes
Authors: Gyure Ruth A. , Konopka Allan , Brooks Austin , Doemel William
Published: January 2020

Reservoir 29 and Lake B are extremely acid lakes (epilimnion pHs of 2.7 and 3.2, respectively), because they receive acidic discharges from coal refuse piles. They differ in that the pH of profundal sediments in Reservoir 29 increased from 2.7 to 3.8 during the period of thermal stratification, whereas permanently anoxic sediments in Lake B had a pH of 6.2. The pH rise in Reservoir 29 sediments was correlated with a temporal increase in H
2
S concentration in the anaerobic hypolimnion from 0 to >1 mM. The chlorophyll
a
levels in the epilimnion of Reservoir 29 were low, and the rate of primary production was typical of an oligotrophic system. However, there was a dense 10-cm layer of algal biomass at the bottom of the metalimnion. Production by this layer was low owing to light limitation and possibly H
2
S toxicity. The specific photosynthetic rates of epilimnetic algae were low, which suggests that nutrient availability is more important than pH in limiting production. The highest photosynthetic rates were obtained in water samples incubated at pH 2.7 to 4. Heterotrophic bacterial activity (measured by [
14
C]glucose metabolism) was greatest at the sediment/water interface. Bacterial production (assayed by thymidine incorporation) was as high in Reservoir 29 as in a nonacid mesotrophic Indiana lake.
Influence of Phosphate on the Growth and Nodulation Characteristics of
Rhizobium trifolii
Authors: Leung Kamtin , Bottomley Peter J.
Published: January 2020

The growth and nodulating characteristics of
Rhizobium trifolii
6 and 36 differed under different external phosphate conditions. Under growth conditions designed to deplete the internal phosphate content of the rhizobia, strain 6 maintained a generation time of 5 h during the exponential phase over two cycles of growth in phosphate-depleted medium. In contrast, the generation time of strain 36 was extended from 3.5 to 9.8 h over two cycles of phosphate-depleted growth, although the organism eventually achieved the same cell density and cellular phosphate content as that of strain 6 at stationary phase. Phosphate-depleted strain 6 required 0.51 ± 0.08 μM phosphate to commence proliferation, whereas phosphate-depleted strain 36 required 0.89 ± 0.04 μM phosphate under the same conditions. Phosphate-depleted strain 6 maintained viability when exposed to external phosphate concentrations subcritical for growth to occur, whereas phosphate-depleted strain 36 lost viability within 48 h when exposed to medium containing phosphate at concentrations subcritical for growth. Phosphate-depleted strain 36 was inferior to phosphate-depleted strain 6 at nodulating subterranean clover (
Trifolium subterraneum
L. cv. Mt. Barker) by taking 2 to 4 days longer to develop nodules in phosphatedepleted plant grown medium at pH 5.5. Nodulation by phosphate-depleted strain 36 was accelerated either by including phosphate in the plant growth medium at pH 5.5 or by raising the solution pH of phosphate-depleted plant growth medium to pH 6.5. External phosphate and pH effects were not observed on the nodulating capabilities of phosphate-depleted strain 6 or on luxury phosphate-grown cells of either strain. Phosphatedepleted strains 6 and 36 proliferated to a similar extent on the rhizoplanes even under stringently low external P
i
concentrations. The phosphatase activities of both phosphate-depleted strains were significantly (
P
= 0.05) higher at pH 6.5 than at pH 5.5, and the activity of strain 6 was significantly higher (
P
= 0.05) than that of strain 36 at pH 5.5 and 5.0.
Osmotic significance of glycerol accumulation in exponentially growing yeasts
Authors: Reed R H , Chudek J A , Foster R , Gadd G M
Published: January 2020

Natural-abundance 13C-nuclear magnetic resonance spectroscopy has shown glycerol to be the major osmotically significant low-molecular-weight solute in exponentially growing, salt-stressed cells of the yeasts Saccharomyces cerevisiae, Zygosaccharomyces rouxii, and Debaromyces hansenii. Measurement of the intracellular nonosmotic volume (i.e., the fraction of the cell that is osmotically unresponsive) by using the Boyle-van't Hoff relationship (for nonturgid cells, the osmotic volume is directly proportional to the reciprocal of the external osmotic pressure) showed that the nonosmotic volume represented up to 53% of the total cell volume; the highest values were recorded in media with maximum added NaCl. Determinations of intracellular glycerol levels with respect to cell osmotic volumes showed that increases in intracellular glycerol may counterbalance up to 95% of the external osmotic pressure due to added NaCl. The lack of other organic osmotica in 13C-nuclear magnetic resonance spectra indicates that inorganic ions may constitute the remaining component of intracellular osmotic pressure.
Occurrence and Growth of Killer Yeasts during Wine Fermentation
Authors: Heard G. M. , Fleet G. H.
Published: January 2020

Sixteen wine fermentations were examined for the presence of killer yeasts. Killer property and sensitivity to killer action were found in isolates of
Saccharomyces cerevisiae
but not in isolates of
Kloeckera, Candida, Hansenula
, and
Torulaspora
spp. Several killer and killer-sensitive strains of
S. cerevisiae
were differentiated by colony morphology, and this property was used to monitor their growth kinetics in mixed cultures in grape juice. Killer-sensitive strains died off within 24 to 48 h during mixed-strain fermentation. Killer action was demonstrated at pH 3.0 and pH 3.5 and over the range of 15 to 25°C but depended on the proportion of killer to killer-sensitive cells at the commencement of fermentation. The dominance of killer strains in mixed-strain fermentations was reflected in the production of ethanol, acetic acid, and glycerol.
Sporotrichum thermophile
Growth, Cellulose Degradation, and Cellulase Activity
Authors: Bhat K. M. , Maheshwari Ramesh
Published: January 2020

The activity of components of the extracellular cellulase system of the thermophilic fungus
Sporotrichum thermophile
showed appreciable differences between strains; β-glucosidase (EC 3.2.1.21) was the most variable component. Although its endoglucanase (EC 3.2.1.4) and exoglucanase (EC 3.2.1.91) activities were markedly lower,
S. thermophile
degraded cellulose faster than
Trichoderma reesei
. The production of β-glucosidase lagged behind that of endoglucanase and exoglucanase. The latter activities were produced during active growth. When growth was inhibited by cycloheximide treatment, the hydrolysis of cellulose was lower than in the control in spite of the presence of both endoglucanase and exoglucanase activities in the culture medium. Degradation of cellulose was a growth-associated process, with cellulase preparations hydrolyzing cellulose only to a limited extent. The growth rate and cell density of
S. thermophile
were similar in media containing cellulose or glucose. A distinctive feature of fungal development in media incorporating cellulose or lactose (inducers of cellulase activity) was the rapid differentiation of reproductive units and autolysis of hyphal cells to liberate propagules which were capable of renewing growth immediately.
Factors affecting the production of pyrroloquinoline quinone by the methylotrophic bacterium W3A1
Authors: McIntire W S , Weyler W
Published: January 2020

Two variants of the methylotrophic bacterium W3A1, designated W3A1-S (slimy) and W3A1-NS (nonslimy), were compared with respect to their ability to grow in batch culture on the C1 substrates methylamine, methanol, and trimethylamine. Substrate utilization, cell density, pH, cellular and soluble polysaccharide production, and concentrations of the enzymes methylamine dehydrogenase, trimethylamine dehydrogenase, and methanol dehydrogenase produced were measured as a function of growth. The ability of the two bacterial variants to excrete the redox cofactor pyrroloquinoline quinone into the growth medium was also investigated. The two variants were similar with respect to all properties measured, except that W3A1-S produced significantly more capsular polysaccharides than variant W3A1-NS. Pyrroloquinoline quinone was excreted when either variant was grown on any of the C1 substrates investigated but was maximally produced when the methylamine concentration was 0.45% (wt/vol). This cofactor is excreted only as bacterial growth enters the stationary phase, a time when the levels of trimethylamine dehydrogenase and the quinoproteins methanol dehydrogenase and methylamine dehydrogenase begin to decline. It is not known whether the pyrroloquinoline quinone found in the medium is made de novo for excretion, derived from the quinoprotein pool, or both. Pyrroloquinoline quinone excretion has been observed with other methylotrophs, but this is the first instance where the excretion was observed with substrates other than methanol.
Inactivation of human and simian rotaviruses by ozone
Authors: Vaughn J M , Chen Y S , Lindburg K , Morales D
Published: January 2020

The inactivation of simian rotavirus SA-11 and human rotavirus type 2 (Wa) by ozone was compared at 4 degrees C by using single-particle virus stocks. Although the human strain was clearly more sensitive, both virus types were rapidly inactivated by ozone concentrations of 0.25 mg/liter or greater at all pH levels tested. Comparison of the virucidal activity of ozone with that of chlorine in identical experiments indicated little significant difference in rotavirus-inactivating efficiencies when the disinfectants were used at concentrations of 0.25 mg/liter or greater.
13
C Nuclear Magnetic Resonance Studies of Propionate Catabolism in Methanogenic Cocultures
Authors: Robbins J. E.
Published: January 2020

Propionate catabolism was monitored in anaerobic cocultures of propionate-degrading and methanogenic bacteria. Metabolism was monitored by use of
13
C-enriched propionate and succinate. The intermediates identified indicated that the methylmalonyl coenzyme A pathway was used in these cultures. The data also indicated that a transcarboxylation reaction between succinate and propionyl coenzyme A occurred, yielding propionate and methylmalonyl coenzyme A.
A selective medium for enumeration and recovery of Pseudomonas cepacia biotypes from soil
Authors: Hagedorn C , Gould W D , Bardinelli T R , Gustavson D R
Published: January 2020

TB-T medium provides a high degree of selectivity for and detection of Pseudomonas cepacia biotypes upon initial plating from soil. TB-T medium consists of a basal medium with glucose as the sole carbon source and asparagine as the sole nitrogen source. The selectivity of TB-T medium is based on the combination of trypan blue (TB) and tetracycline (T) (pH 5.5). On TB-T medium, 216 of 300 isolates (72%) from five different soil types were identified as P. cepacia. The remaining 28% were facultative organisms that could be separated readily from P. cepacia by anaerobic glucose fermentation and by their inability to grow at 41 degrees C. Molds were controlled on low soil dilutions by adding crystal violet, nystatin, or both. Elimination of either ingredient or elevation of the pH to 7.5 resulted in a pronounced loss of selectivity. The efficiency of recovery varied considerably among P. cepacia strains but was high enough for some strains (76 to 86%) to permit quantitative studies. TB-T medium combines a defined formulation with high selectivity and allows recovery of P. cepacia biotypes from low soil dilutions (10(1) to 10(3)).
Drag reduction by Acinetobacter calcoaceticus BD4
Authors: Sar N , Rosenberg E
Published: January 2020

The encapsulated bacterium Acinetobacter calcoaceticus BD4 at a density of 3.6 X 10(9) cells per ml reduced the friction of turbulent water in a narrow pipe by 55%. This drag reduction was due to the tightly bound polysaccharide capsules (0.4 mg per ml) of culture. Capsule-deficient mutants of BD4 failed to reduce drag. The cell-bound polysaccharide demonstrated a threefold-higher drag-reducing activity than the polymer which was free in solution.
Control of Interspecies Electron Flow during Anaerobic Digestion: Role of Floc Formation in Syntrophic Methanogenesis
Authors: Thiele Jurgen H. , Chartrain M. , Zeikus J. Gregory
Published: January 2020

The flora of an anaerobic whey-processing chemostat was separated by anaerobic sedimentation techniques into a free-living bacterial fraction and a bacterial floc fraction. The floc fraction constituted a major part (i.e., 57% total protein) of the total microbial population in the digestor, and it accounted for 87% of the total CO
2
-dependent methanogenic activity and 76% of the total ethanol-consuming acetogenic activity. Lactose was degraded by both cellular fractions, but in the free flora fraction it was associated with higher intermediary levels of H
2
, ethanol, butyrate, and propionate production. Electron microscopic analysis of flocs showed bacterial diversity and juxtapositioning of tentative
Desulfovibrio
and
Methanobacterium
species without significant microcolony formation. Ethanol, an intermediary product of lactose-hydrolyzing bacteria, was converted to acetate and methane within the flocs by interspecies electron transfer. Ethanol-dependent methane formation was compartmentalized and closely coupled kinetically within the flocs but without significant formation of H
2
gas. Physical disruption of flocs into fragments of 10- to 20-μm diameter initially increased the H
2
partial pressure but did not change the carbon transformation kinetic patterns of ethanol metabolism or demonstrate a significant role for H
2
in CO
2
reduction to methane. The data demonstrate that floc formation in a whey-processing anaerobic digestor functions in juxtapositioning cells for interspecies electron transfer during syntrophic ethanol conversion into acetate and methane but by a mechanism which was independent of the available dissolved H
2
gas pool in the ecosystem.
Measurement of live bacteria by Nomarski interference microscopy and stereologic methods as tested with macroscopic rod-shaped models
Authors: Baldwin W W , Bankston P W
Published: January 2020

A new method is proposed to measure bacterial cells under growth conditions. Bacterial cells, suspended in their growth medium, were attached to a cover slip with poly-L-lysine. The cover slip was inverted and placed on a glass microscope slide. To prevent dehydration of the medium, the edges of the cover slip were sealed to the microscope slide with clear fingernail polish. The bacteria on the slide were then quickly photographed with a Leitz light microscope, using Nomarski optics. The photographic negatives were then projected at a standard distance through a lens system, and the projected images of the whole cells were outlined by hand onto graph paper. The profile images so transcribed onto the graph paper were in effect transverse sections of each of the cells. Using stereologic grid and point counting techniques, the area of the cell transverse section as well as the perimeter or circumference of the transverse section were estimated. Formulae were developed so that both the volume and surface area of the whole cell could be ascertained from these area and circumference measurements. Since the efficacy of any measurements of surface area and volume of microscopic rod-shaped bacterial cells could be questioned, macroscopic rod-shaped models were used to test the theory and formulae and to compare this method with other commonly used cell-sizing techniques. This technique could be used in any study of bacterial cell size or changes in cell size (e.g., osmotic shifts).
Poliovirus retention in soil columns after application of chemical- and polyelectrolyte-conditioned dewatered sludges
Authors: Pancorbo O C , Bitton G , Farrah S R , Gifford G E , Overman A R
Published: January 2020

The transport of poliovirus type 1 (strain LSc) was studied in Red Bay sandy loam columns that were treated with chemical- or polyelectrolyte-conditioned dewatered sludges and then leached with natural rainwater under saturated flow conditions. Poliovirus was concentrated in the alum and ferric chloride sludges that were produced following the flocculation of virus-seeded raw sewage. Virtually complete inactivation of the virus was observed following the flocculation of raw sewage or the stabilization of alum and ferric chloride sludges with lime at pH 11.5. Poliovirus was also concentrated in polyelectrolyte-conditioned dewatered sludge that was produced from virus-seeded, anaerobically digested sludge. Despite the saturated flow conditions for a sustained period, no viruses were detected in the leachates of the soil columns that were treated with these chemical and chemically treated sludges. Since the viruses were mostly associated with the solids in these sludge samples, it is believed that they were immobilized along with the sludge solids in the top portion of the soil columns.
Acetic Acid Production by an Electrodialysis Fermentation Method with a Computerized Control System
Authors: Nomura Yoshiyuki , Iwahara Masayoshi , Hongo Motoyoshi
Published: January 2020

In acetic acid fermentation by
Acetobacter aceti
, the acetic acid produced inhibits the production of acetic acid by this microorganism. To alleviate this inhibitory effect, we developed an electrodialysis fermentation method such that acetic acid is continuously removed from the broth. The fermentation unit has a computerized system for the control of the pH and the concentration of ethanol in the fermentation broth. The electrodialysis fermentation system resulted in improved cell growth and higher productivity over an extended period; the productivity exceeded that from non-pH-controlled fermentation. During electrodialysis fermentation in our system, 97.6 g of acetic acid was produced from 86.0 g of ethanol; the amount of acetic acid was about 2.4 times greater than that produced by non-pH-controlled fermentation (40.1 g of acetic acid produced from 33.8 g of ethanol). Maximum productivity of electrodialysis fermentation in our system was 2.13 g/h, a rate which was 1.35 times higher than that of non-pH-controlled fermentation (1.58 g/h).
Biodegradation of alpha- and beta-hexachlorocyclohexane in a soil slurry under different redox conditions
Authors: Bachmann A , Walet P , Wijnen P , de Bruin W , Huntjens J L , Roelofsen W , Zehnder A J
Published: January 2020

Aerobic conditions proved to be best for the microbiol conversion of alpha-hexachlorocyclohexane (alpha-HCH) in a soil slurry. The dry soil contained 400 mg of alpha-HCH per kg. This xenobiotic compound was mineralized within about 18 days at an initial rate of 23 mg/kg of soil per day by the mixed native microbial population of the soil. The only intermediate that was detected during breakdown was pentachlorocyclohexene, which was detected at very small concentrations. Alpha-HCH was also bioconverted under methanogenic conditions. However, a rather long acclimation period (about 30 days) was necessary before degradation started, at a rate of 13 mg/kg of soil per day. Mass balance calculations showed that about 85% of the initial alpha-HCH that was present was converted to monochlorobenzene, 3,5-dichlorophenol, and a trichlorophenol isomer, possibly 2,4,5-trichlorophenol. Under both denitrifying and sulfate-reducing conditions, no significant bioconversion of alpha-HCH was observed. The beta isomer of HCH was recalcitrant at all of the four redox conditions studied. We propose that the specific spatial chloride arrangement of the beta isomer is responsible for its stability. The results reported here with complex soil slurry systems showed that alpha-HCH is, in contrast to the existing data in the literature, best degraded biologically in the presence of oxygen.
A suspension method to determine reuse life of chemical disinfectants during clinical use
Authors: Robison R A , Bodily H L , Robinson D F , Christensen R P
Published: January 2020

In-use testing of disinfectants is necessary to ensure efficacy over time. The current official procedure for testing disinfectants, the Association of Official Analytical Chemists (AOAC) use-dilution method, cannot be adapted to repeated sampling techniques of use-life testing. It is therefore necessary to use an alternative method when evaluating the activity of a disinfectant under actual use. The Clinical Research Associates (CRA) suspension method was developed to fill this need. It consists of adding 0.5 ml of a standard culture to 5.0 ml of test disinfectant and sampling the mixture after 10 min for surviving bacteria. When this test was compared with the AOAC use-dilution method under a simulated use situation, the two methods were generally equivalent in identifying disinfectant inactivation. In addition, the CRA method was less time consuming, easier to perform, and less variable than the AOAC method. Use of the CRA method in a clinical study demonstrated the need for reuse claims to be based on clinical use studies rather than on laboratory testing only.
Development of a Mutant Strain of
Bacillus polymyxa
Showing Enhanced Production of 2,3-Butanediol
Authors: Mallonee D. H. , Speckman R. A.
Published: January 2020

2,3-Butanediol is a feedstock chemical of potential industrial importance. It can serve as a monomer for many polymers of consumer interest that are currently supplied by the fossil fuel industry.
Bacillus polymyxa
can grow on inexpensive waste products of the food-processing industry and produce this glycol. This paper describes a mutant strain of
B. polymyxa
which displays constitutive production of catabolic α-acetolactate synthase, an enzyme in the 2,3-butanediol pathway which is normally produced only in the late log or stationary phase of growth. The mutant was obtained by treating the wild type with nitrosoguanidine and subjecting it to a penicillin counterselection procedure. One of the selected mutant strains produced four times as much of the glycol as the wild type and utilized approximately 25% of the energy source, compared with essentially complete utilization of the energy source by the wild type. Studies are under way to optimize the production of the glycol by the mutant.
Aquatic nitrogen transformations at low oxygen concentrations
Authors: Downes M T
Published: January 2020

Nitrite and nitrous oxide made up 40% of the hypolimnetic dissolved inorganic nitrogen in mesotrophic Lake Rotoiti, New Zealand, prior to hypolimnetic anoxia. Up to 120 mg of N m-3 as nitrite and 20 mg of N m-3 as nitrous oxide accumulated, whereas dissolved-oxygen concentrations remained between 1.0 and 0.2 g m-3 and were totally consumed when the hypolimnion became completely anoxic. Assays of water column nitrification potentials, together with measurements of the relative rates of nitrate and nitrite reduction, suggested that at low dissolved-oxygen concentrations both nitrite and nitrous oxide were produced mainly by ammonium-oxidizing bacteria, with nitrous oxide being a product of nitrifier denitrification.
High Survivability of Cheese Whey-Grown
Rhizobium meliloti
Cells upon Exposure to Physical Stress
Authors: Bissonnette N. , Lalande R.
Published: January 2020

Whey, a by-product of the dairy industry, has been found to protect the rhizobia cells during freezing and thawing. Cells of rhizobia grown on whey sustained freezing better at −18°C than did cells grown on mannitol or sucrose. Suspensions of cells grown on whey or mannitol that were suspended in whey performed equally well at −18 and −80°C, with 94 and 100% survival, respectively. Whey-grown rhizobia in pellets withstood desiccation better than did their mannitol-grown equivalents. Rhizobia that were grown on whey and then inoculated onto commercial peat showed a survival rate of 100% after 23 weeks at −4°C. Whey-grown cells in peat performed better at various temperatures during storage, even when they were exposed to desiccation, than did mannitol-grown cells in peat. Whey, therefore, offers interesting possibilities as a
Rhizobium
protectant for the inoculum industry.
Enzyme immunoassay for the macrocyclic trichothecene roridin A: production, properties, and use of rabbit antibodies
Authors: M�rtlbauer E , Gareis M , Terplan G
Published: January 2020

Antisera against roridin A were prepared by using a roridin A-hemisuccinate derivative coupled to human serum albumin as the immunogen. Antibodies could be detected in the sera of the immunized rabbits as early as 4 weeks after the initial exposure. After one booster injection at week 14, high antibody titers were measured over a period of 21 weeks. The specificity and sensitivity of the antibodies were tested by using roridin A-hemisuccinate coupled to horseradish peroxidase as an enzyme-linked toxin in a competitive assay with a double-antibody solid phase. The assay was most specific for the tested macrocyclic trichothecenes, and the relative cross-reactivities with roridin A, roridin J, verrucarin A, satratoxin H, and satratoxin G were 1, 0.41, 0.15, 0.15, and 0.07, respectively. When 16 nonmacrocyclic trichothecenes were tested, only diacetylverrucarol (0.0015) and verrucarol (0.0005) showed minor cross-reactivity. The sensitivity of the enzyme immunoassay for the detection of roridin A was in the range of 5 to 50 ng/ml (0.16 to 1.6 ng per assay).
Transformation of Clostridium perfringens L forms with shuttle plasmid DNA
Authors: Mahony D E , Mader J A , Dubel J R
Published: January 2020

L-form (L-phase) cultures of Clostridium perfringens were tested for their transformability with plasmid DNA. Three L-form strains were transformable, but one, strain L-13, was superior to the others. This strain was easily and reproducibly transformed with previously described shuttle vectors which were derived from either C. perfringens or Escherichia coli. Strain L-13 was transformable by a variety of methods, and a new micromethod worked well under both aerobic and anaerobic conditions. The maximal number of transformants was attained after strain L-13 was exposed for 4 h to the transforming DNA and polyethylene glycol. Viable counts determined in tubes of semisolid brain heart infusion medium containing 10% sucrose, with or without 2 micrograms of tetracycline per ml, showed a transformation rate of 3.9 X 10(-5) (transformants per viable cells).
Microbial Conversion of α-Ionone, α-Methylionone, and α-Isomethylionone
Authors: Yamazaki Yoshinari , Hayashi Yumiko , Arita Masatoshi , Hieda Tadaharu , Mikami Yoichi
Published: January 2020

α-Ionone, α-methylionone, and α-isomethylionone were converted by
Aspergillus niger
JTS 191. The individual bioconversion products from α-ionone were isolated and identified by spectrometry and organic synthesis. The major products were
cis
-3-hydroxy-α-ionone,
trans
-3-hydroxy-α-ionone, and 3-oxo-α-ionone. 2,3-Dehydro-α-ionone, 3,4-dehydro-β-ionone, and 1-(6,6-dimethyl-2-methylene-3-cyclohexenyl)-buten-3-one were also identified. Analogous bioconversion products from α-methylionone and α-isomethylionone were also identified. From results of gas-liquid chromatographic analysis during the fermentation, we propose a metabolic pathway for α-ionones and elucidation of stereochemical features of the bioconversion.
Nitrogen inhibition of mycotoxin production by Alternaria alternata
Authors: Orvehed M , Häggblom P , Söderhäll K
Published: January 2020

Alternaria alternata produces the polyketides alternariol (AOH) and alternariol monomethyl ether (AME) during the stationary growth phase. Addition of 12 mM NaNO3 to the cultures before initiation of polyketide production reduced the AOH and AME content to 5 to 10% of that of controls. Glutamate and urea also reduced AOH and AME accumulation, whereas increasing the ionic strength did not affect the polyketide content. Adding NaNO3 after polyketide production had started did not inhibit further AOH accumulation, although over 90% of the added NO3- disappeared from the medium within 24 h. Activity of an AME-synthesizing enzyme, alternariol-O-methyltransferase (AOH-MT), appeared in control mycelia during the early stationary growth phase. No AOH-MT activity appeared in mycelia blocked in polyketide synthesis by addition of NaNO3. Later addition of NaNO3 reduced the AOH-MT specific activity to 50% of that of the control, whereas the total of activity per mycelium was the same. The AOH-MT activity in vitro was not affected by 100 mM NaNO3. The results suggest that nitrogen in some way inhibited the formation of active enzymes in the polyketide-synthesizing pathway in A. alternata when it was added before these enzymes were formed.
Colonization of gastrointestinal tracts of chicks by Campylobacter jejuni
Authors: Beery J T , Hugdahl M B , Doyle M P
Published: January 2020

Bacterial enumeration and histologic examination of organs and tissues of 8-day-old chicks 7 days after peroral inoculation with Campylobacter jejuni revealed that the organism colonized primarily the lower gastrointestinal tract. The principal sites of localization were the ceca, large intestine, and cloaca, where densely packed cells of C. jejuni were observed in mucus within crypts. Examination of C. jejuni-colonized crypts by transmission electron microscopy revealed that the campylobacters freely pervaded the lumina of crypts without attachment to crypt microvilli. Understanding the mechanism of colonization may lead to approaches that will reduce the incidence of C. jejuni carriage by poultry.
Stability of enterocytes and certain enzymatic activities in suspensions of cells from the villous tip to the crypt of Lieberkühn of the mouse small intestine
Authors: Whitt D D , Savage D C
Published: January 2020

A series of studies in this laboratory have focused on how an indigenous microbiota influences the activities of alkaline phosphatase, phosphodiesterase I, and thymidine kinase in the enterocytes of the upper small intestine of mice. To draw conclusions about the role of the microflora in determining levels of enzymatic activity, we found it necessary to develop a procedure by which cell suspensions could be obtained containing enterocytes isolated sequentially from the villous tip to the crypt of Lieberkühn. The procedure was modified from the one developed for rats by Weiser (J. Biol. Chem. 248:2536-2541, 1973), involved a minimum number of interfering factors (e.g., proteolytic enzymes and mechanical agitation), and worked reproducibly for mice. During development of the procedure, some variables affecting the assays of the enzymes known to be present in enterocytes were also explored. Rods to which were tied everted segments of gut were incubated in a series of tubes containing a solution of EDTA the concentration of which was changed from 1.5 to 5.0 mM, thus giving a greater yield of enterocytes at every step. The cells incubating in the chelating solution were most stable when 0.23 M sucrose was included in the EDTA solutions. Success in assaying enzymatic activities in the cell suspensions depended on (i) how the cells were isolated, (ii) the assay procedure for thymidine kinase, and (iii) whether cellular suspensions or extracts were assayed.
Survival of rifampin-resistant mutants of Pseudomonas fluorescens and Pseudomonas putida in soil systems
Authors: Compeau G , Al-Achi B J , Platsouka E , Levy S B
Published: January 2020

The fate of spontaneous chromosomal rifampin-resistant (Rifr) mutants of Pseudomonas putida and Pseudomonas fluorescens in sterile and live organic soil from which they were isolated was studied. In sterile native-soil assays, a Rifr mutant of P. putida showed no decrease in competitive fitness when compared with the wild-type parent. However, mutants of P. fluorescens were of two general categories. Group 1 showed no difference from the wild type in terms of growth rate, competitive fitness, and membrane protein composition. Group 2 showed a slower growth rate in both minimal and enriched media and an altered membrane protein profile. These mutants also demonstrated decreased competitive fitness compared with the wild-type strain. In live soil, the Rifr P. putida strain persisted throughout the 38-day test period with a decay rate of 0.7 log10 CFU/g of soil per 10 days. A group 1 Rifr P. fluorescens mutant maintained its inoculated titer for 7 to 10 days and then decayed at a rate of 0.2 to 0.4 log10 CFU/g of soil per 10 days. A group 2 Rifr P. fluorescens mutant remained at its titer for 1 to 5 days before decaying at a two- to threefold-faster rate. These findings indicate that rifampin resistance may not be an innocuous mutation in some pseudomonads and that marked strains should be compared with wild-type parents before being used as monitors of parental strain survival. Colonization of sterile soil with either the wild-type or mutant strain precluded normal colonization of the second added strain.(ABSTRACT TRUNCATED AT 250 WORDS)
Comparisons of ruminal fermentation characteristics and microbial populations in bison and cattle
Authors: Towne G , Nagaraja T G , Cochran R C , Harmon D L , Owensby C E , Kaufman D W
Published: January 2020

Ruminal microbial populations, fermentation characteristics, digestibility, and liquid flow rates in two ruminally cannulated bison and two ruminally cannulated Hereford steers fed a prairie hay diet were compared. No significant differences in anaerobic bacterial counts, volatile fatty acid concentrations, or ruminal pHs were evident between bison and cattle. Also, no significant differences in neutral detergent fiber digestibility, indigestible fiber retention time, or intake were detected between bison and cattle, although cattle had higher levels (P less than 0.08) of ruminal dry matter and indigestible fiber than bison. Bison had a smaller (P = .02) ruminoreticular volume, faster liquid dilution rates, and faster liquid turnover times than cattle. The average ruminal ammonia nitrogen concentration was higher (P = 0.02) in bison (1.17 mg/dl) than in cattle (0.79 mg/dl). Total ciliate protozoal counts and cell volume were greater (P = 0.07) in bison (32.8 x 10(4)/g and 407.1 x 10(-4) ml/g, respectively) than in cattle (15.7 x 10(4)/g and 162.2 x 10(-4) ml/g, respectively). Bison harbored higher (P less than 0.02) numbers of Dasytricha spp., Eudiplodinium maggii, Eudiplodinium bursa, and Epidinium spp. than cattle and possessed a type B protozoan population. The cattle possessed a mixed type A-type B population that was characterized by Ophryoscolex spp. and Polyplastron spp. in association with low concentrations of Epidinium spp. and Eudiplodinium maggii.
Pyrene degradation by a Mycobacterium sp.: identification of ring oxidation and ring fission products
Authors: Heitkamp M A , Freeman J P , Miller D W , Cerniglia C E
Published: January 2020

The degradation of pyrene, a polycyclic aromatic hydrocarbon containing four aromatic rings, by pure cultures of a Mycobacterium sp. was studied. Over 60% of [14C]pyrene was mineralized to CO2 after 96 h of incubation at 24 degrees C. High-pressure liquid chromatography analyses showed the presence of one major and at least six other metabolites that accounted for 95% of the total organic-extractable 14C-labeled residues. Analyses by UV, infrared, mass, and nuclear magnetic resonance spectrometry and gas chromatography identified both pyrene cis- and trans-4,5-dihydrodiols and pyrenol as initial microbial ring-oxidation products of pyrene. The major metabolite, 4-phenanthroic acid, and 4-hydroxyperinaphthenone and cinnamic and phthalic acids were identified as ring fission products. 18O2 studies showed that the formation of cis- and trans-4,5-dihydrodiols were catalyzed by dioxygenase and monooxygenase enzymes, respectively. This is the first report of the chemical pathway for the microbial catabolism of pyrene.
Is free halogen necessary for disinfection?
Authors: Williams D E , Elder E D , Worley S D
Published: January 2020

The principle of Le Chatelier was used in demonstrating that 3-chloro-4,4-dimethyl-2-oxazolidinone (compound 1) itself kills Staphylococcus aureus rather than the very small amount of free chlorine in hydrolysis equilibrium with compound 1. On the other hand, when the N-bromo analog of compound 1 (compound 1B) was used as the disinfectant, the mixture of combined compound 1B and free bromine formed in the hydrolysis equilibrium provided disinfection. When the hydrolysis equilibrium for 1B was suppressed to the level at which a negligible amount of free bromine remained in solution, combined compound 1B was much more efficacious than combined compound 1 at killing S. aureus.
Stabilities of lyophilized Staphylococcus aureus typing bacteriophages
Authors: Zierdt C H
Published: January 2020

Staphylococcus aureus bacteriophages (25 phages) were lyophilized in aliquots 12 to 18 years ago and stored in vacuo at -20 degrees C. Eight viruses each lost one log titer, while seventeen retained the original titers. The use of lyophilized phages provided more reproducible phage typing and reduced by 75% the complexity and cost. This important test is thus made feasible for more laboratories.
Molecular cloning of the penicillin G acylase gene from Arthrobacter viscosus
Authors: Ohashi H , Katsuta Y , Hashizume T , Abe S N , Kajiura H , Hattori H , Kamei T , Yano M
Published: January 2020

Penicillin G acylase was purified from the cultured filtrate of Arthrobacter viscosus 8895GU and was found to consist of two distinct subunits with apparent molecular weights of 24,000 (alpha) and 60,000 (beta). The partial N-terminal amino acid sequences of the alpha and beta subunits were determined with a protein gas phase sequencer, and a 29-base oligonucleotide corresponding to the partial amino acid sequence of the alpha subunit was synthesized. An Escherichia coli transformant having the penicillin G acylase gene was isolated from an A. viscosus gene library by hybridization with the 29-base probe. The resulting positive clone was further screened by the Serratia marcescens overlay technique. E. coli carrying a plasmid designated pHYM-1 was found to produce penicillin G acylase in the cells. This plasmid had an 8.0-kilobase pair DNA fragment inserted in the EcoRI site of pACYC184.
Fermentation of Insoluble Cellulose by Continuous Cultures of
Ruminococcus albus
Authors: Pavlostathis Spyros G. , Miller Terry L. , Wolin Meyer J.
Published: January 2020

The hydrolysis and fermentation of insoluble cellulose (Avicel) by continuous cultures of
Ruminococcus albus
7 was studied. An anaerobic continuous culture apparatus was designed which permitted gas collection, continuous feeding, and wasting at different retention times. The operation of the apparatus was controlled by a personal computer. Cellulose destruction ranged from ca. 30 to 70% for hydraulic retention times of 0.5 to 2.0 days. Carbon recovery in products was 92 to 97%, and the oxidation-reduction ratios ranged from 0.91 to 1.15. The total product yield (biomass not included) per gram of cellulose (expressed as glucose) was 0.83 g g
−1
, and the ethanol yield was 0.41 g g
−1
. The product yield was constant, indicating that product formation was growth linked.
Cloning and expression of a Bacteroides succinogenes mixed-linkage beta-glucanase (1,3-1,4-beta-D-glucan 4-glucanohydrolase) gene in Escherichia coli
Authors: Irvin J E , Teather R M
Published: January 2020

A pseudorandom genomic library of Bacteroides succinogenes DNA, cloned into pUC8 in Escherichia coli, was screened for beta-glucanase activity on 0.1% lichenan plates. Six high-activity clones, containing identical 5.2-kilobase inserts of B. succinogenes DNA, were obtained. The clones exhibited activity solely on beta-glucan substrates containing beta-(1----3)(1----4) linkages, thus manifesting a specific fibrolytic enzyme previously unrecognized in B. succinogenes. A subclone (pJI10) of the original insert (1.35 kilobases in size) expressed full beta-glucanase activity under control of its own promoter. The expression of beta-glucanase in pJI10 appeared subject to catabolite regulation by glucose. Detailed analysis of enzyme activity in the parental and deleted derivatives, subcloned into pUC18 and pUC19, suggested that the apparent glucose repression was an artifact arising as a consequence of interactions with the lac transcriptional unit in the plasmid vector.
Thiolase from
Clostridium acetobutylicum
ATCC 824 and Its Role in the Synthesis of Acids and Solvents
Authors: Wiesenborn Dennis P. , Rudolph Frederick B. , Papoutsakis Eleftherios T.
Published: January 2020

Thiolase (acetyl-coenzyme A [CoA] acetyltransferase, E.C. 2.3.1.19) from
Clostridium acetobutylicum
ATCC 824 has been purified 70-fold to homogeneity. Unlike the thiolase in
Clostridium pasteurianum,
this thiolase has high relative activity throughout the physiological range of internal pH of 5.5 to 7.0, indicating that change in internal pH during acid production is not an important factor in the regulation of this thiolase. In the condensation direction, the thiolase is inhibited by micromolar levels of CoA, and this may be an important factor in modulating the net condensation of acetyl-CoA to acetoacetyl-CoA. Other cofactors and metabolites that were tested and shown to be inhibitors are ATP and butyryl-CoA. The native enzyme consists of four 44,000-molecular-weight subunits. The kinetic binding mechanism is ping-pong. The

K
m

value for acetyl-CoA is 0.27 mM at 30°C and pH 7.4. The

K
m

values for sulfhydryl-CoA and acetoacetyl-CoA are, respectively, 0.0048 and 0.032 mM at 30°C and pH 8.0. The active site apparently contains a sulfhydryl group, but unlike other thiolases, this thiolase is relatively stable in the presence of 5,5′-dithiobis(2-nitrobenzoic acid). Studies of thiolase specific activity under various types of continuous fermentations show that regulation of this enzyme at both the genetic and enzyme levels is important.
Acetate production from hydrogen and [13C]carbon dioxide by the microflora of human feces
Authors: Lajoie S F , Bank S , Miller T L , Wolin M J
Published: January 2020

Fecal suspensions from humans were incubated with 13CO2 and H2. The suspensions were from subjects who harbored 10(8) and 10(10) methanogens per g (dry weight) of feces, respectively, and from a subject who did not harbor methanogens. Quantitative nuclear magnetic resonance spectroscopy showed that acetate labeled in both the methyl and carboxyl groups was formed by suspensions from the subject without methanogens and the subject with the lower concentrations of methanogens. The amounts of labeled acetate formed were in agreement with the amounts expected based on measurements of H2 utilization. No labeled acetate was formed by suspensions from the subject with the higher concentrations of methanogens, and essentially all of the H2 used was accounted for by CH4 production. Suspensions from the subject with lower concentrations of methanogens produced both methane and acetate from H2 and CO2. The results indicate that reduction of CO2 to acetate may be a major pathway for microbial production of acetate in the human colon except when very high concentrations of methanogens (ca. 10(10) per g [dry weight] of feces) are present. Double-labeled acetate was also formed from H2 and 13CO2 by fecal suspensions from nonmethanogenic and moderately methanogenic rats.
Ruminal ciliated protozoa in bison
Authors: Towne G , Nagaraja T G , Kemp K K
Published: January 2020

Ruminal contents from 79 slaughtered bison and 2 ruminally cannulated bison were collected to obtain information on total numbers and species distribution of ciliated protozoa. The bison originated from numerous herds throughout the Great Plains and were grouped into three dietary categories: (i) only forage; (ii) forage with moderate levels of supplementation; and (iii) feedlot concentrate-silage diet. Total ciliate counts were highest in bison receiving grain supplementation (210.1 x 10(4)/g) and lowest in bison consuming only forage (27.1 x 10(4)/g). All protozoan species found in bison have been reported in domestic livestock, although Ophryoscolex sp., a relatively common protozoan in cattle, was detected at low concentrations in only eight bison. The uncommon holotrich Microcetus lappus was present in five bison in concentrations reaching 8.4% of the total ciliate population. Charonina ventriculi, another infrequently observed species, was present in 18 bison, with the highest concentrations in forage-fed animals. Thirty bison possessed a type B protozoan population, characterized by Epidinium sp., Eudiplodinium maggii, and Eudiplodinium bovis. Thirty-eight bison possessed a mixed A-B population, characterized by Polyplastron sp. coexisting with low numbers of Eudiplodinium maggii or Epidinium sp. or both. Thirteen bison possessed populations lacking any remnant type B ciliate species. At least 29 of the bison possessing Polyplastron sp. were known to have been in contact with cattle, whereas all bison isolated from cattle had type B populations. The reduction of type B populations in bison becomes increasingly likely as bison production expands into areas inhabited by domestic livestock.