bluuebunny/crossref_metadata_2025 huggingface dataset:
Denitrification and Assimilatory Nitrate Reduction in
Aquaspirillum magnetotacticum
Authors: Bazylinski Dennis A. , Blakemore R. P.
Published: January 2020

Aquaspirillum magnetotacticum
MS-1 grew microaerobically but not anaerobically with NO
3
−
or NH
4
+
as the sole nitrogen source. Nevertheless, cell yields varied directly with NO
3
−
concentration under microaerobic conditions. Products of NO
3
−
reduction included NH
4
+
, N
2
O, NO, and N
2
. NO
2
−
and NH
2
OH, each toxic to cells at 0.2 mM, were not detected as products of cells growing on NO
3
−
. NO
3
−
reduction to NH
4
+
was completely repressed by the addition of 2 mM NH
4
+
to the growth medium, whereas NO
3
−
reduction to N
2
O or to N
2
was not. C
2
H
2
completely inhibited N
2
O reduction to N
2
by growing cells. These results indicate that
A. magnetotacticum
is a microaerophilic denitrifier that is versatile in its nitrogen metabolism, concomitantly reducing NO
3
−
by assimilatory and dissimilatory means. This bacterium appears to be the first described denitrifier with an absolute requirement for O
2
. The process of NO
3
−
reduction appears well adapted for avoiding accumulation of several nitrogenous intermediates that are toxic to cells.
Influence of carbohydrates on growth and sporulation of Clostridium perfringens in a defined medium with or without guanosine
Authors: Sacks L E
Published: January 2020

Clostridium perfringens strains NCTC 8238, NCTC 8798, NCTC 8679, 8-6, FD-1, and PS52 formed high levels of heat-resistant spores in a defined medium (D) with various sugars as energy sources. Strain PS49 formed high levels of heat-resistant spores when grown with dextrin and methylxanthines. The experiments showed the possibility of carrying out experiments on the sporulation of certain C. perfringens strains in a completely defined medium, without using the ill-defined polysaccharide dextrin. The addition of guanosine and sucrose to D medium generally suppressed sporulation in most strains and made it possible to prepare overnight cultures consisting mainly of vegetative cells. These cultures could be used to inoculate D medium directly, eliminating both the need to wash cells and the lag which normally occurs when cells have been grown in a different medium. Except for strains PS52 and NCTC 8238, guanosine generally increased growth rates and reduced sporulation for all strains when grown on simple sugars. Methylxanthines decreased growth rates and increased sporulation of NCTC 8679 and PS49 when present in D medium with dextrin. In the absence of guanosine, strains NCTC 8798 and 8-6 grew much slower on glucose than on disaccharides. Strain PS52 grew on lactose only after a prolonged lag. For strains requiring dextrin for good sporulation, a commercial dextrin (Difco Laboratories) was found to be readily filter sterilized, making it possible to prepare large amounts of media for use in the production of spores (or enterotoxin).
Metabolism of Halophenols by 2,4,5-trichlorophenoxyacetic acid-degrading Pseudomonas cepacia
Authors: Karns J S , Kilbane J J , Duttagupta S , Chakrabarty A M
Published: January 2020

Resting cells of 2,4,5-trichlorophenoxyacetic acid-grown Pseudomonas cepacia AC1100 were able to completely and rapidly dechlorinate several chlorine-substituted phenols, including 2,4,5-trichlorophenol, 2,3,4,6-tetrachlorophenol, and pentachlorophenol. Several other trichlorophenols were only partially dechlorinated. The evidence suggests that 2,4,5-trichlorophenol is an intermediate in the degradation of 2,4,5-trichlorophenoxyacetic acid by strain AC1100. Moreover, although strain AC1100 was isolated by selection for growth on a chlorinated aromatic compound, brominated and fluorinated analogs were efficiently dehalogenated by strain AC1100 resting cells, whereas an iodinated analog was poorly dehalogenated.
Production of Soy Sauce Koji Mold Spore Inoculum in Plastic Bags
Authors: Lotong N. , Suwanarit P.
Published: January 2020

An innovation is described for producing soy sauce koji mold spore inoculum by using inexpensive autoclavable plastic bags and reuseable plastic enclosures to make culture vessels. After growth, the spore mass could be dried and packaged in the same bag after removing the enclosure. Broken rice was used as the substrate for mold cultivation. Viable spore counts of 10
9
spores per g were obtained under optimal conditions. After drying at 50°C for 6 h, the moisture content of the spore mass decreased from 35.22 to 6.32% with no significant effect on spore viability. The dry spores could be stored in the refrigerator or at room temperature for at least 3 months.
Evaluation of filters for recovery of Campylobacter jejuni from water
Authors: Mathewson J J , Keswick B H , DuPont H L
Published: January 2020

Campylobacter jejuni has been incriminated in several large waterborne outbreaks, but it has rarely been isolated from water itself. Better methodology is needed for the isolation of C. jejuni from water. We evaluated three types of 0.45-micron microporous filters and three different pore sizes of positively charged depth filters for their ability to recover C. jejuni from seeded, sterile tap and surface water. The microporous filters tested were Millipore HA, Gelman GN6, and Zetapor. Three pore sizes of Zeta Plus depth filters (05S, 30S, and 50S) were evaluated by using an adsorption-elution technique. The overall percent recovery in both tap and surface water by microporous filters was: Zetapor, 66%; Millipore HA, 33%; and Gelman GN6, 33%. Adsorption-elution with Zeta Plus 50S allowed 89% recovery of C. jejuni. These data suggest that both the positively charged Zetapor microporous filter and the Zeta Plus 50S depth filter are effective filters for the recovery of C. jejuni from water.
Initiation of Activation of a Preemergent Herbicide by a Novel Alkylsulfatase of
Pseudomonas putida
FLA
Authors: Lillis Veronica , Dodgson Kenneth S. , White Graham F. , Payne William J.
Published: January 2020

The activation of the preemergent herbicide 2-(2,4-dichlorophenoxy)ethyl sulfate (Crag herbicide) is initiated by soil microorganisms that are presumed to act by removing the ester sulfate group via some type of sulfatase enzyme. An enrichment technique with the herbicide as the sole source of sulfur led to the isolation of several pure cultures that could produce 2-(2,4-dichlorophenoxy)ethanol from the herbicide. One of these, a strain of
Pseudomonas putida
, was particularly active. Polyacrylamide gel zymograms of extracts of cells grown on nutrient broth showed the presence of three secondary and three primary alkylsulfatases. One of the latter enzymes was active toward Crag herbicide as well as sodium dodecyl sulfate. Maximum activity was obtained in the late-stationary phase of growth, and enzyme yields were not affected by either the presence or the absence of the herbicide in the growth medium. The enzyme was purified 2,670-fold to homogeneity by a combination of streptomycin sulfate treatment, heat treatment, and column chromatography on DEAE-cellulose, Sephacryl 200-S, and butyl agarose. The pure enzyme was tetrameric (molecular weight, 295,000) and most active at pH 6.0. Saturation kinetics with inhibition by excess substrate were observed for Crag herbicide and octyl sulfate. 2-Butox-yethyl sulfate was a relatively poor substrate, and dodecyltriethoxy sulfate was not hydrolyzed at all. Enzymatic hydrolysis of each substrate in the presence of H
2
18
O led to incorporation of
18
O exclusively into SO
4
2−
ions in all three cases. The Crag herbicide sulfatase therefore acts by cleaving the O-S bond of the C-O-S ester linkage, in contrast with other alkylsulfatases acting on long-chain alkyl sulfates.
Chemically Defined Medium for Cultivation of Several Epiphytic and Phytopathogenic Spiroplasmas
Authors: Lee I.-M. , Davis R. E.
Published: January 2020

A chemically defined medium, LD82, was formulated for in vitro cultivation of spiroplasmas. Medium LD82 supported good growth for four epiphytic and insect-pathogenic spiroplasmas,
Spiroplasma floricola
23-6
T
,
Spiroplasma
sp. strain SR3,
Spiroplasma
sp. strain brevi, and
Spiroplasma
sp. strain AS576, and of the phytopathogenic spiroplasmas
Spiroplasma citri
Maroc R8A2
T
and PC1. Titers of all six strains grown in defined medium LD82 reached 2.0 × 10
9
to 6.0 × 10
9
CFU/ml of culture. All spiroplasma strains tested formed colonies readily on agar medium LD82. None of the spiroplasmas formed typical fried-egg colonies. All formed diffuse colonies, but the forms of colonies differed somewhat among the spiroplasma strains. In preliminary studies of nutritional requirements, phospholipids slightly enhanced the growth of the epiphytic and insect-pathogenic strains in medium LD82 and were found essential for good growth of
S. citri.
Direct skin test in highly sensitized guinea pigs for rapid and sensitive determination of staphylococcal enterotoxin B
Authors: Scheuber P H , Mossmann H , Beck G , Hammer D K
Published: January 2020

The direct skin test in highly sensitized guinea pigs was developed as a rapid and extremely sensitive assay for detection of staphylococcal enterotoxin B (SEB) in foods. This report details the experimental conditions required to elicit optimal sensitization of guinea pigs to SEB. An intense and persistent immunoglobulin E (IgE) anti-SEB response was established in strain 13 guinea pigs pretreated with cyclophosphamide followed by four sensitizing doses of 10 micrograms of SEB 1 month apart. The conditions, however, optimal for eliciting IgE responses led to a sustained failure to produce antibody of the IgG1 subclass. With the use of highly sensitized guinea pigs, one can achieve a sensitivity ranging from 0.1 to 1.0 pg of purified SEB by the direct skin test for at least 7 months after the last challenge. For analysis of SEB in food extracts, the entire assay can be accomplished within 20 min with a sensitivity of 10 to 100 pg SEB per ml of prepared food samples, and the recovery of enterotoxin from spiked food products ranged between 75 and 89% of the amount added.
Quantitative immunofluorescence studies of the serology of Bacillus anthracis spores
Authors: Phillips A P , Martin K L
Published: January 2020

A fluorescein-conjugated antibody against formalin-inactivated spores of Bacillus anthracis Vollum reacted only weakly with a variety of Bacillus species in microfluorometric immunofluorescence assays. A conjugated antibody against spores of B. anthracis Sterne showed little affinity for spores of several B. anthracis isolates including B. anthracis Vollum, indicating that more than one anthrax spore serotype exists.
Antibiotic resistance of fecal coliforms after long-term withdrawal of therapeutic and subtherapeutic antibiotic use in a swine herd
Authors: Langlois B E , Cromwell G L , Stahly T S , Dawson K A , Hays V W
Published: January 2020

Tetracycline resistance of fecal coliforms isolated from swine decreased from 82 to 42%, a decrease of less than 50%, after the use of all forms of antimicrobial agents were discontinued in the herd for 126 months.
Protease activities of rumen protozoa
Authors: Forsberg C W , Lovelock L K , Krumholz L , Buchanan-Smith J G
Published: January 2020

Intact, metabolically active rumen protozoa prepared by gravity sedimentation and washing in a mineral solution at 10 to 15 degrees C had comparatively low proteolytic activity on azocasein and low endogenous proteolytic activity. Protozoa washed in 0.1 M potassium phosphate buffer (pH 6.8) at 4 degrees C and stored on ice autolysed when they were warmed to 39 degrees C. They also exhibited low proteolytic activity on azocasein, but they had a high endogenous proteolytic activity with a pH optimum of 5.8. The endogenous proteolytic activity was inhibited by cysteine proteinase inhibitors, for example, iodoacetate (63.1%) and the aspartic proteinase inhibitor, pepstatin (43.9%). Inhibitors specific for serine proteinases and metalloproteinases were without effect. The serine and cysteine proteinase inhibitors of microbial origin, including antipain, chymostatin, and leupeptin, caused up to 67% inhibition of endogenous proteolysis. Hydrolysis of casein by protozoa autolysates was also inhibited by cysteine proteinase inhibitors. Some of the inhibitors decreased endogenous deamination, in particular, phosphoramidon, which had little inhibitory effect on proteolysis. Protozoal and bacterial preparations exhibited low hydrolytic activities on synthetic proteinase and carboxypeptidase substrates, although the protozoa had 10 to 78 times greater hydrolytic activity (per milligram of protein) than bacteria on the synthetic aminopeptidase substrates L-leucine-p-nitroanilide, L-leucine-beta-naphthylamide, and L-leucinamide. The aminopeptidase activity was partially inhibited by bestatin. It was concluded that cysteine proteinases and, to a lesser extent, aspartic proteinases are primarily responsible for proteolysis in autolysates of rumen protozoa. The protozoal autolysates had high aminopeptidase activity; low deaminase activity was observed on endogenous amino acids.
Stereoselective metabolism of anthracene and phenanthrene by the fungus Cunninghamella elegans
Authors: Cerniglia C E , Yang S K
Published: January 2020

The fungus Cunninghamella elegans oxidized anthracene and phenanthrene to form predominately trans-dihydrodiols. The metabolites were isolated by reversed-phase high-pressure liquid chromatography for structural and conformational analyses. Comparison of the circular dichroism spectrum of the fungal trans-1,2-dihydroxy-1,2-dihydroanthracene to that formed by rat liver microsomes indicated that the major enantiomer of the trans-1,2-dihydroxy-1,2-dihydroanthracene formed by C. elegans had an S,S absolute stereochemistry, which is opposite to the predominately 1R,2R dihydrodiol formed by rat liver microsomes. C. elegans oxidized phenanthrene primarily in the 1,2-positions to form trans-1,2-dihydroxy-1,2-dihydrophenanthrene. In addition, a minor amount of trans-3,4-dihydroxy-3,4-dihydrophenanthrene was detected. Metabolism at the K-region (9,10-positions) of phenanthrene was not detected. Comparison of the circular dichroism spectra of the phenanthrene trans-1,2- and trans-3,4-dihydrodiols formed by C. elegans to those formed by mammalian enzymes indicated that each of the dihydrodiols formed by C. elegans had an S,S absolute configuration. The results indicate that there are differences in both the regio- and stereoselective metabolism of anthracene and phenanthrene between the fungus C. elegans and rat liver microsomes.
In vitro ruminal fermentation of organic acids common in forage
Authors: Russell J B , Van Soest P J
Published: January 2020

Mixed rumen bacteria from cows fed either timothy hay or a 60% concentrate were incubated with 7.5 mM citrate, trans-aconitate, malate, malonate, quinate, and shikimate. Citrate, trans-aconitate, and malate were fermented at faster rates than malonate, quinate, and shikimate. Acetate was the primary fermentation product for all six acids. Quinate and shikimate fermentations gave rist to butyrate, whereas malate and malonate produced significant amounts of propionic acid. High-pressure liquid chromatography of fermentation products from trans-aconitate incubations revealed a compound that was subsequently identified as tricarballylate. As much as 40% of the trans-aconitate acid was converted to tricarballylate, and tricarballylate was fermented slowly. The slow rate of tricarballylate metabolism by mixed rumen bacteria and its potential as a magnesium chelator suggest that tricarballylate formation could be an important factor in the hypomagnesemia that leads to grass tetany.
Deterministic Three-Half-Order Kinetic Model for Microbial Degradation of Added Carbon Substrates in Soil
Authors: Brunner Walter , Focht Dennis D.
Published: January 2020

The kinetics of mineralization of carbonaceous substrates has been explained by a deterministic model which is applicable to either growth or nongrowth conditions in soil. The mixed-order nature of the model does not require a priori decisions about reaction order, discontinuity period of lag or stationary phase, or correction for endogenous mineralization rates. The integrated equation is simpler than the integrated form of the Monod equation because of the following: (i) only two, rather than four, interdependent constants have to be determined by nonlinear regression analysis, (ii) substrate or product formation can be expressed explicitly as a function of time, (iii) biomass concentration does not have to be known, and (iv) the required initial estimate for the nonlinear regression analysis can be easily obtained from a linearized form rather than from an interval estimate of a differential equation.
14
CO
2
evolution data from soil have been fitted to the model equation. All data except those from irradiated soil gave better fits by residual sum of squares (RSS) by assuming growth in soil was linear (RSS = 0.71) as opposed to exponential (RSS = 2.87). The underlying reasons for growth (exponential versus linear), no growth, and relative degradation rates of substrates are consistent with the basic mechanisms from which the model is derived.
Microbial uptake of radiolabeled substrates: estimates of growth rates from time course measurements
Authors: Li W K
Published: January 2020

The uptake of [3H]glucose and a mixture of 3H-labeled amino acids was measured, in time course fashion, in planktonic microbial assemblages of the eastern tropical Pacific Ocean. The average generation times of those portions of the assemblages able to utilize these substrates were estimated from a simple exponential growth model. Other workers have independently used this model in its integrated or differential form. A mathematical verification and an experimental demonstration of the equivalence of the two approaches are presented. A study was made of the size distribution of heterotrophic activity, using time course measurements. It was found that the size distribution and the effect of sample filtration before radiolabeling were dependent on time of incubation. In principle, it was possible to ascribe these time dependences to differences in the specific growth rate and initial standing stock of the microbial assemblages.
Cellulase biosynthesis in a catabolite repression-resistant mutant of Thermomonospora curvata
Authors: Fennington G , Neubauer D , Stutzenberger F
Published: January 2020

A catabolite repression-resistant mutant of the thermophilic actinomycete Thermomonospora curvata was obtained by treatment with ethyl methanesulfonate and UV light. Cellulase biosynthesis was undiminished by glucose, 2-deoxyglucose, or alpha-methyl glucoside, which are potent repressors in the wild type. Intracellular cyclic AMP levels were higher in the mutant in both the absence and the presence of repressors.
Pragmatic criteria to distinguish psychrophiles and psychrotrophs in ecological systems
Authors: Gow J A , Mills F H
Published: January 2020

Optimal incubation times and temperatures were determined for populations of psychrophilic and psychrotrophic bacteria from a seasonally cold ocean. The application of conventional pragmatic criteria did not differentiate the two populations, although they could be distinguished by growth at two temperatures.
Bacterial Symbionts in the Sugar Beet Root Maggot,
Tetanops myopaeformis
(von Röder)
Authors: Iverson Kathy L. , Bromel Mary C. , Anderson Albin W. , Freeman Thomas P.
Published: January 2020

Aerobic heterotrophic and facultative anaerobic bacteria were isolated from all developmental stages of the sugar beet root maggot,
Tetanops myopaeformis
(von Röder). Two distinct bacterial symbiotic relationships were observed.
Serratia liquefaciens
and
Serratia marcescens
were found to be associated with all developmental stages. Bacterial symbiont transmission occurred from one generation to the next. Symbionts were transferred from the male reproductive system to the female reproductive system, where both an internal infiltration of the egg chorion and an external smearing of the eggs occurred during oviposition.
Pseudomonas maltophilia
was found in association with the larval gut and the inner surface of the puparium. Electron microscopy of the inner puparial surface revealed symbionts within the chitinous wall. In vitro symbiont chitinase production was found, using both nephelometric (turbidimetric) and
N
-acetylglucosamine assays. A relationship appeared to exist between adult fly emergence and enzymatic chitin degradation of the puparium by the bacterial symbionts.
Bacterial interference with coliform colony sheen production on membrane filters
Authors: Burlingame G A , McElhaney J , Bennett M , Pipes W O
Published: January 2020

The membrane filter (MF) method for detection and enumeration of coliform bacteria in drinking water requires that the coliforms both grow and produce a green metallic sheen when the filter is incubated on modified Endo medium at 35 degrees C for 22 h. Large numbers of noncoliform bacteria, which are enumerated by the standard plate count (SPC) technique, can interfere with the detection of coliforms on MF. This paper presents quantitative evidence from laboratory experiments on the interference of specific SPC bacteria on coliform colony sheen production on MF. Pseudomonas aeruginosa and Aeromonas hydrophila caused significant reductions in Escherichia coli sheen colony counts when present at 3,000 and 220 per filter, respectively. The Flavobacterium sp. and Bacillus sp. selected for this study from SPC did not interfere with coliform colony sheen production. Excessive crowding of E. coli and Enterobacter cloacae colonies on MF also caused a reduction in the number of colonies that produced sheen. Even when there was no crowding (14 colonies per filter), only a fraction of the E. cloacae colonies produced sheen colonies on modified Endo medium.
Conjugative 40-megadalton plasmid in Streptococcus lactis subsp. diacetylactis DRC3 is associated with resistance to nisin and bacteriophage
Authors: McKay L L , Baldwin K A
Published: January 2020

Streptococcus lactis subsp. diacetylactis DRC3 was examined for plasmid DNA and found to contain a previously unreported plasmid of 40 X 10(6) daltons. This plasmid, designated pNP40, was conjugally transferred to a plasmid-cured derivative of S. lactis C2. Transconjugants containing pNP40 acquired resistance to nisin produced by strains of S. lactis and to commercially available nisin when assay plates were incubated at 21, 32, and 37 degrees C. In addition, c2 phage growth was completely restricted in transconjugants containing pNP40 at 21 and 32 degrees C, but not at 37 degrees C. This result suggests that pNP40 may be coding for a temperature-sensitive enzyme that restricts phage growth at 21 and 32 degrees C, but not at 37 degrees C. Eight consecutive transfers of a transconjugant containing pNP40 in Elliker broth at 37 degrees C resulted in 100% loss of resistance to c2 phage when colonies were tested at 32 degrees C. These phage-sensitive isolates had lost pNP40 and had also become sensitive to nisin. This result suggests that pNP40 may also be thermosensitive in its replication. The finding of a phage resistance determinant located on a conjugative plasmid should prove useful in constructing phage-resistant variants for dairy fermentation processes.
Assessment of the potential of insecticides, emulsifiers, and solvent mixtures to enhance viral infection in cultured mammalian cells
Authors: Brookman D H , Chopra C , Ecobichon D J , Kang C Y , Ritter L , Thorsen J
Published: January 2020

Various insecticides, solvents, emulsifiers, and mixtures thereof were tested to determine whether these compounds are capable of enhancing the sensitivity of cultured mammalian cells to infection with vesicular stomatitis virus. None of 42 compounds tested significantly enhanced the viral infection.
Adsorption of Escherichia coli onto insolubilized lauryl pyridinium iodide and its bacteriostatic action
Authors: Nakagawa Y , Tawaratani T , Kourai H , Horie T , Shibasaki I
Published: January 2020

Insoluble lauryl pyridinium iodide [C12(50)] was synthesized as an antimicrobial agent. Escherichia coli cells were not killed by C12(50) but only adsorbed onto it. Though cells on C12(50) could not grow in nutrient agar, they possessed the ability to develop once they were liberated from C12(50). The adsorption of cells onto C12(50) was inhibited by iodide anions released from C12(50) itself. The ability of C12(50) to adsorb was decreased by the adsorbed cells, but C12(50) could be reactivated by washing with alkaline solutions. It was, therefore, suggested that this adsorption was mainly due to the electrostatic interaction between cells and C12(50). The adsorption of cells onto C12(50) was confirmed by scanning electron microscopy.
Isolation, chemical structure, acute toxicity, and some physicochemical properties of territrem C from Aspergillus terreus
Authors: Ling K H , Liou H H , Yang C M , Yang C K
Published: January 2020

Territrem C, a new tremorgenic mycotoxin (C28H32O9; molecular weight, 512.20) was isolated from the chloroform extract of rice cultures of Aspergillus terreus 23-1, which also produces territrems A and B. Isolation, acute toxicity, and some physicochemical properties of territrem C are discussed in this paper. The spectral and chemical evidence indicated that the structural difference between territrem C and territrem B (C29H34O9) was in their phenyl moieties: a 4-hydroxy-3,5-dimethoxy phenyl group in territrem C and a 3,4,5-trimethoxy phenyl group in territrem B. It was also demonstrated that territrem B was obtained by methylation of territrem C with dimethyl sulfate.
Sensitivity of heat-stressed yeasts to essential oils of plants
Authors: Conner D E , Beuchat L R
Published: January 2020

Eight strains of yeasts (Candida lipolytica, Debaryomyces hansenii, Hansenula anomala, Kloeckera apiculata, Lodderomyces elongisporus, Rhodotorula rubra, Saccharomyces cerevisiae, and Torulopsis glabrata) were examined for changes in sensitivity to eight essential oils of plants (allspice, cinnamon, clove, garlic, onion, oregano, savory, and thyme) after being sublethally heat stressed. With the exception of garlic oil for all test yeasts, onion oil for S. cerevisiae, and oregano oil for R. rubra, the essential oils at concentrations of up to 200 ppm in recovery media did not interfere with colony formation by unheated cells. However, some oils, at concentrations as low as 25 ppm in recovery media, reduced populations of sublethally heat-stressed cells compared to populations recovered in media containing no test oils. This demonstrates that the yeasts were either metabolically or structurally damaged as a result of being exposed to elevated temperatures and that essential oils prohibited repair of injury. The size (diameter) of colonies produced on oil-supplemented recovery agar by heat-stressed cells was reduced compared to that observed on unsupplemented agar. Pigment production by heated R. rubra was inhibited by oils of oregano, savory, and thyme, but enhanced by garlic and onion oils. The influence of essential oils on survival of yeasts in thermally processed foods and in the enumeration of stressed cells in these foods should not be minimized.
In Vivo Cloning of
lac
Genes in
Streptococcus lactis
ML3
Authors: Anderson Douglas G. , McKay Larry L.
Published: January 2020

The isolation and characterization of a
Streptococcus lactis
ML3 strain which possessed a recombinant lactose plasmid is described. The recombination events generating this plasmid occurred in vivo in a recombination-deficient strain and appeared to be mediated by transposition events. Restriction mapping revealed that the recombinant plasmid, pDA0307, contained a region of the lactose plasmid, pSK08, linked to another resident plasmid, pSK07. Copy number determinations indicated that the
lac
genes were present at approximately 20 copies per cell in pDA0307, whereas the
lac
genes are normally present at approximately 10 copies per cell in pSK08. The strain containing pDA0307 displayed a 21 to 54% increase in the expression of the Lac enzyme phospho-β-
d
-galactosidase. However, the strain containing pDA0307 both grew and produced lactic acid in milk at rates identical to that of a strain containing pSK08. This result suggests that
lac
gene dosage of plasmid-linked
lac
genes was not limiting the rate at which these derivatives of
S. lactis
ML3 fermented milk.
Aerobic Microbial Degradation of Glucoisosaccharinic Acid
Authors: Strand S. E. , Dykes J. , Chiang V.
Published: January 2020

α-Glucoisosaccharinic acid (GISA), a major by-product of kraft paper manufacture, was synthesized from lactose and used as the carbon source for microbial media. Ten strains of aerobic bacteria capable of growth on GISA were isolated from kraft pulp mill environments. The highest growth yields were obtained with
Ancylobacter
spp. at pH 7.2 to 9.5. GISA was completely degraded by cultures of an
Ancylobacter
isolate.
Ancylobacter
cell suspensions consumed oxygen and produced carbon dioxide in response to GISA addition. A total of 22 laboratory strains of bacteria were tested, and none was capable of growth on GISA. GISA-degrading isolates were not found in forest soils.
Cystine antagonism of the antibacterial action of lactoperoxidase-thiocyanate-hydrogen peroxide on Streptococcus agalactiae
Authors: Mickelson M N , Anderson A J
Published: January 2020

Cystine reduction in Streptococcus agalactiae, resulting in sulfhydryl formation, may account for antagonism of the antibacterial effect of lactoperoxidase-thiocyanate-hydrogen peroxide when cystine is present in excess of the amount needed for maximum growth. Accumulation of cystine by S. agalactiae and its reduction to form sulfhydryl compounds were demonstrated. The reduction of cystine appeared to occur by a couple reaction between glutathione reductase and glutathione-disulfide transhydrogenase activity, both of which were found in the supernatant fraction from cell homogenates. NADPH-specific glutathione reductase activity was found in the pellet and supernatant fractions from cell homogenates. Two sulfhydryls were formed for each mole of NADPH used during cystine reduction. The information presented offers a plausible explanation of how cystine, when present in excess of growth needs, may be reduced to generate sulfhydryl compounds which neutralize the antibacterial effect of lactoperoxidase-thiocyanate-hydrogen peroxide on S. agalactiae.
Rutin-induced beta-glucosidase activity in Streptococcus faecium VGH-1 and Streptococcus sp. strain FRP-17 isolated from human feces: formation of the mutagen, quercetin, from rutin
Authors: MacDonald I A , Bussard R G , Hutchison D M , Holdeman L V
Published: January 2020

A fecal isolate, Streptococcus sp. strain FRP-17, and strain VGH-1 of Streptococcus faecium were shown to contain beta-glucosidases which converted rutin (quercetin-3-O-beta-D-glucose-alpha-L-rhamnose) to quercetin and were active against o-nitrophenyl-beta-D-glucose. The activity against rutin could be measured by increased mutagenicity in the Ames assay or visualized on thin-layer chromatography plates. In both organisms, the beta-glucosidase activities were inducible by the addition of rutin to the growth media. Several closely related strains of Streptococcus spp. lacked any beta-glucosidase activity. In cell preparations of the active organisms, activities with rutin and o-nitrophenyl-beta-D-glucose were optimal at pH 6.8 and could be enhanced by increasing the ionic strength of the assay system. At low ionic strengths, both quercetin and a new product (intermediate between the polarities of rutin and quercetin) were formed by the incubation of rutin with cell preparations of either active organism. This product disappeared with increased ionic strength, suggesting that it may be a reaction intermediate, quercetin-3-O-beta-D-glucose. These results suggest that the beta-glucosidase active against rutin and that active against o-nitrophenyl-beta-D-glucose are the same.
Legionella sainthelensi: a new species of Legionella isolated from water near Mt. St. Helens
Authors: Campbell J , Bibb W F , Lambert M A , Eng S , Steigerwalt A G , Allard J , Moss C W , Brenner D J
Published: January 2020

Six strains of a new species, Legionella sainthelensi, were isolated from freshwater in areas affected by the volcanic eruptions of Mt. St. Helens in the state of Washington. Strains of L. sainthelensi are culturally and biochemically similar to other legionellae. They grow on buffered charcoal yeast agar but not on media that lack cysteine. They are gram-negative, nonsporeforming, motile rods that are positive in reactions for catalase, oxidase, gelatin liquefaction, and beta-lactamase. They are negative in reactions for urease, hydrolysis of hippurate, reduction of nitrates, fermentation of glucose, and blue-white autofluorescence. Their cell wall fatty acid composition is qualitatively similar to those of other legionellae, with 50 to 62% branched-chain fatty acids. They contain the isobranched-chain 14- and 16-carbon acids and anteisobranched-chain 15- and 17-carbon acids and relatively large amounts of straight-chain 16-carbon acid. All strains of L. sainthelensi contain approximately equal amounts of ubiquinones Q9, Q10, Q11, and Q12, a pattern similar to those of Legionella bozemanii, Legionella dumoffi, and Legionella longbeachae. Serological cross-reactions were observed between L. sainthelensi, both serogroups of L. longbeachae, and Legionella oakridgensis. Three strains of L. sainthelensi were greater than 90% related by DNA hybridization. The type strain of L. sainthelensi, Mt. St. Helens 4, was 36% related to the type strain of L. longbeachae and 3 to 14% related to the other nine described Legionella species.
Ecology of pathogenic yeasts in Amazonian soil
Authors: Mok W Y , Luizão R C , do Socorro Barreto da Silva M , Teixeira M F , Muniz E G
Published: January 2020

In an investigation of Amazonian soil as a natural reservoir for pathogenic fungi, 1,949 soil samples collected from diverse geographical and ecological settings of the Brazilian Amazon Basin were analyzed for the presence of non-keratinophilic fungi by the indirect mouse inoculation procedure and for the presence of keratinophilic fungi by the hair bait technique. All soil samples were acidic with low pH values. From 12% of the soil samples, 241 yeast and yeastlike isolates pertaining to six genera and 82 species were recovered, of which 63% were Torulopsis and 26% were Candida species. Nine fungi with known pathogenic potentials were encountered among 43% (104) of the isolates: T. glabrata, C. guilliermondii, C. albicans, C. pseudotropicalis, C. stellatoidea, C. tropicalis, Rhodotorula rubra, and Wangiella dermatitidis. The yeast flora was marked by species diversity, low frequency of each species, random geographical distribution, and an apparent lack of species clustering. The composition and distribution of the yeast flora in soil differed from those of the yeast flora harbored by bats, suggesting that the Amazonian external environment and internal bat organs act as independent natural habitats for yeasts.
Stimulation of aflatoxin B1 and T-2 toxin production by sorbic acid
Authors: Gareis M , Bauer J , von Montgelas A , Gedek B
Published: January 2020

Aspergillus flavus grown on yeast extract-sucrose medium produced higher amounts of aflatoxin B1 in the presence of 0.025% sorbic acid than without this chemical with a maximum at 17 days of incubation. Addition of 0.05 to 0.0125% sorbic acid stimulated T-2 toxin production of Fusarium acuminatum cultures grown on maize meal. The highest amounts of the mycotoxin were detected in 14-day-old cultures containing 0.025% sorbic acid. It is assumed that certain amounts of sorbic acid near the minimal inhibitory concentration reduce the activity of the tricarboxylic acid cycle; this may lead to an accumulation of acetyl coenzyme A, which is an essential intermediate in the biosynthesis of aflatoxin B1 and T-2 toxin.
GELRITE as a Gelling Agent in Media for the Growth of Thermophilic Microorganisms
Authors: Lin Chi Chung , Casida L. E.
Published: January 2020

GELRITE, a new gelling agent with good thermal stability and clarity, was evaluated in media for culturing selected thermophilic microorganisms. It was also evaluated for performing counts of thermophilic bacteria from soil samples. In most cases, GELRITE was shown to be superior to agar for these applications.
Host specificity of filamentous, segmented microorganisms adherent to the small bowel epithelium in mice and rats
Authors: Tannock G W , Miller J R , Savage D C
Published: January 2020

Germfree rats and mice were given by gavage samples of ileal homogenates prepared from conventional rats and mice. Filamentous, segmented procaryotes adhered to the small bowel epithelium in the ex-germfree mice only when the homogenate was made from mouse bowel and in the ex-germfree rats only when the inoculum came from rats. Thus, the filamentous microorganisms are host animal specific.
Effect of oil and dispersant on growth and chlorophyll a content of the marine microalga Tetraselmis suecica
Authors: Fabregas J , Herrero C , Veiga M
Published: January 2020

Low hydrocarbon concentrations stimulated the growth of Tetraselmis suecica, whereas higher concentrations (200 ppm) inhibited growth. The content of chlorophyll a in this microalga was affected in a similar way. Crude oil had the most marked effects. Dispersant SEAKLIN-101-NT and mixtures of oil and SEAKLIN-101-NT did not show selective toxicity for the microalga, although inhibitory effects could be observed at high concentrations.
Lipid Composition of a Psychrophilic Marine
Vibrio
sp. During Starvation-Induced Morphogenesis
Authors: Oliver James D. , Stringer William F.
Published: January 2020

Qualitative and quantitative changes with time in phospholipids and fatty acids were examined after suspension of cells of a psychrophilic marine bacterium in nutrient-free artificial seawater at 5°C. Viability was maintained throughout the 21-day examination period, with plate counts and acridine orange direct counts indicating a slight increase in cell number. Gravimetric data, however, showed a significant decrease in bacterial biomass during the 3-week study. Levels of ATP per cell also decreased significantly (59%) during the starvation period. Since starvation (resulting in dormancy) is probably the typical physiological state of marine bacteria, estimation of bacterial density in marine waters by using ATP data obtained from log-phase cells is probably inaccurate. Total lipid phosphate decreased (65%) during the starvation period, with phosphatidylethanolamine showing the greatest loss. A large increase (57%) in the neutral lipid fraction was also detected, especially during the first week of starvation. A selective increase in palmitoleate at the expense of myristate was detected in the membrane lipids. The effects of these changes on membrane fluidity and the possible consequences for these cells in the marine environment are discussed.
Electrolyte Effects on Attachment of an Estuarine Bacterium
Authors: Gordon Andrew S. , Millero Frank J.
Published: January 2020

The effect of electrolyte concentration on attachment of
Vibrio alginolyticus
to hydroxyapatite was determined. Bacterial affinity for attachment to the surface and surface capacity were derived from linearization of bacterial adsorption isotherms. At low concentrations (<0.1 M) the affinity of the bacteria for the surface increased with increasing ionic strength, in agreement with the D.L.V.O. theory of colloid interaction. At higher concentrations, bacterial affinity for the surface decreased with increasing concentration of cations and was not related to ionic strength changes in the medium. These results demonstrate a change in the mechanism by which salts affect bacterial attachment at salt concentrations above 0.1 M. The results are consistent with the relationship between the proportion of attached bacteria and salinity observed in previously published field studies. The results may also resolve differences between various attachment studies carried out in different ionic strength media, utilizing different bacteria, surfaces, and experimental methods.
Cytoplasmic proteins of Streptococcus mutans (serotype c) and their interaction with fluoride
Authors: Yotis W W , Zeb M , Kubak B , Wu-Yuan C , Yotis E , McNulty J
Published: January 2020

The protein profile of the cytoplasmic proteins of Streptococcus mutans GS-5 was determined by two-dimensional gel electrophoresis. Use of this recently developed, high-resolution analytical tool showed in excess of 140 cytoplasmic proteins. The profile consisted of mostly acidic components with pI values between 3.70 and 5.30 and relative molecular weights mainly in the 13,000 to 90,000 range. With sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the proteins were resolved into 40 to 45 components. The binding of fluoride by the proteins reached a maximum value in 15 min, and it was linear with exogenous F- doses of up to 60 to 80 ppm per mg of protein (60 to 80 micrograms/g). The proteins bound 22 to 138 times more F- from assay mixtures containing 1 mM CaCl2 than from assay mixtures containing such ions as HgCl2, ZnCl2, CuCl2, MgCl2, MnCl2, or SnCl2. When NaF, SnF2, NH4F, CsF, (CH3)4NF, and Na2PO3F were used as sources of F- (adjusted to 10 ppm of F- in all cases), the proteins bound 2.1, 1.8, 1.6, 1.4, and 0.3 ppm of F- per mg of protein, respectively. Initial fractionation of the plasma proteins by preparative column isoelectric focusing indicated that proteins with pI values of 4.1 to 4.5 as well as those with pI values of 5.0 to 5.3 bound twice as much F- as did the proteins outside these pI values.
Production and characterization of antibody against aflatoxin Q1
Authors: Fan T S , Zhang G S , Chu F S
Published: January 2020

Antibodies against aflatoxin Q1 (AFQ1) were obtained from rabbits after immunization of either AFQ1-hemisuccinate or AFQ2a conjugated to bovine serum albumin. Both radioimmunoassay and enzyme-linked immunosorbent assaY (ELISA) were used for the determination of antibody titers and specificities. Antibodies obtained from rabbits after immunization with AFQ1-hemisuccinate-bovine serum albumin had the highest affinity to aflatoxin B1, whereas antibodies obtained from rabbits after immunization with AFQ2a-bovine serum albumin bound most effectively with AFQ2a. AFQ2a antibody was selected for the subsequent direct and indirect ELISA for the detection of AFQ1 in biological fluids. When AFQ2a-peroxidase and AFQ2a antibody were used, direct ELISA was able to detect as low as 2 ppb (ng/ml) of AFQ1 spiked in the urine samples that had been subjected to a Sep-Pak cleanup treatment. In indirect ELISA in which the antigen (AFQ2a-bovine serum albumin) was coated to the solid phase followed by reaction with rabbit antibody and goat anti-rabbit immunoglobulin G-peroxidase conjugate, 50-fold less antibody was used without sacrificing sensitivity. Recoveries of AFQ1 added to urine samples (2 to 40 ppb) were 46.3 to 73% and 65.8 to 85.8% for direct and indirect ELISA, respectively.
Ferric chloride flocculation for nonflocculating beef extract preparations
Authors: Payment P , Fortin S , Trudel M
Published: January 2020

The addition of 2.5 mM ferric chloride to 0.5% beef extract solution at pH 3.5 was found to be highly efficient in the recovery of seeded poliovirus type 1 (Sabin) or indigenous viruses from environmental samples. This method was extremely useful to reconcentrate viruses from beef extract solutions that did not flocculate at pH 3.5.
Mixotrophic Growth of a
Thiobacillus ferrooxidans
Strain
Authors: Barros M. E. C. , Rawlings D. E. , Woods D. R.
Published: January 2020

Mixotrophic growth of a
Thiobacillus ferrooxidans
strain is described. DNA moles percent guanine plus cytosine and homology determinations confirmed that the mixotrophically grown
T. ferrooxidans
cultures were not contaminated with heterotrophic
Acidiphilium
strains.
Rhizobium japonicum
Serogroup and Hydrogenase Phenotype Distribution in 12 States
Authors: Keyser Harold H. , Weber Deane F. , Uratsu Sandra L.
Published: January 2020

A survey was conducted in 1980 on 972 isolates of
Rhizobium japonicum
obtained from 65 soybean field locations in 12 states. Isolates were examined for the hydrogenase (Hup) phenotype and somatic serogroup identity. Only 20% of the isolates were Hup
+
, with a majority of Hup
−
isolates occurring in 10 of the 12 states. The most predominant serogroup was 31 (21.5%), followed by 123 (13.6%). Although most serogroups contained a majority of Hup
−
isolates, marked differences occurred. None of the isolates in serogroup 135 were Hup
+
, but 93% of the isolates in serogroup 122 were Hup
+
. The serogroups with relatively high frequencies of Hup
+
isolates (122 and 110) constitute only a small part (<5% each) of the
R. japonicum
field population in the 12 states.
Heterotrophic nitrification among denitrifiers
Authors: Castignetti D , Hollocher T C
Published: January 2020

Twelve denitrifying bacteria representing six genera were tested for an ability to nitrify pyruvic oxime heterotrophically. Six of these bacteria exhibited appreciable nitrification activity, yielding as much as 5.8 mM nitrite and little or no nitrate when grown in a mineral salts medium containing 7 mM pyruvic oxime and 0.05% yeast extract. Of the six active bacteria, four (Pseudomonas denitrificans, Pseudomonas aeruginosa, and two strains of Pseudomonas fluorescens) could grow on yeast extract but not pyruvic oxime, one (Pseudomonas aureofaciens) could grow slowly on pyruvic oxime, and one (Alcaligenes faecalis) could apparently grow on pyruvic oxime in the presence of yeast extract but not in its absence. Eight of the twelve bacteria in the resting state could oxidize hydroxylamine to nitrite, and P. aureofaciens was remarkably active in this regard. In general, those denitrifiers active in the nitrification of pyruvic oxime or hydroxylamine or both are abundant in soils. A possible advantage of having nitrification and denitrification capabilities in the same organism is discussed.
Method for detecting production of zearalenone, zearalenol, T-2 toxin, and deoxynivalenol by Fusarium isolates
Authors: Richardson K E , Hagler W M , Hamilton P B
Published: January 2020

Three methods for detecting toxigenic fusaria in culture were compared by using known producers of zearalenone, zearalenol, T-2 toxin, and deoxynivalenol. Moist, autoclaved rice cultures of known toxigenic isolates grown in 20-ml tubes yielded oily extracts containing compounds which interfered with qualitative and quantitative analysis for the mycotoxins. Vermiculite moistened with nutrient broth in 20-ml tubes yielded a much cleaner extract. Growing the fungi on a liquid medium required a shorter incubation period, but yields of T-2 toxin and deoxynivalenol were low and variable, and the method required greater space in the incubator. Screening of the extracts by thin-layer chromatography with colorimetric spray reagents to detect the presence of these toxins permitted reduction in the number of extracts quantified by the more lengthy gas-liquid chromatographic method. Culturing in nutrient broth on vermiculite in tubes coupled to a qualitative screen before quantitation proved to be a convenient, inexpensive, and relatively rapid method that enabled reliable screening of a large number of Fusarium isolates for toxin production as compared with prior methods.
Leakage of glutathione from bacterial cells caused by inhibition of gamma-glutamyltranspeptidase
Authors: Nakayama R , Kumagai H , Tochikura T
Published: January 2020

Glutathione leaked from cells of Proteus mirabilis grown in medium containing an inhibitor of gamma-glutamyltranspeptidase. In medium containing 100 mM L-serine and borate, up to 300 microM glutathione accumulated. L-Serine in the medium was consumed during the logarithmic phase of growth, gamma-glutamyltranspeptidase activity was restored, and glutathione decreased in the medium. In the presence of 2 mM 6-diazo-5-oxo-L-norleucine, cells increased normally, gamma-glutamyltranspeptidase was inhibited completely, and the maximum concentration of glutathione which accumulated in the medium was 20 microM. The glutathione content of cells rose before leakage began. Glutathione leaked from intact cells of other bacteria, although to a lesser extent than was seen with P. mirabilis.