bluuebunny/crossref_metadata_2025 huggingface dataset:
Conversion of zearalenone to zearalenone glycoside by Rhizopus sp
Authors: Kamimura H
Published: January 2020

The microbial conversion of zearalenone by various species of fungi was studied. Among them, Rhizopus sp. was the sole fungus which produced a new metabolite from zearalenone in addition to alpha- and beta-zearalenol. The structure of the new metabolite was determined to be zearalenone 4-beta-D-glucopyranoside on the basis of mass, infrared, and nuclear magnetic resonance spectroscopies. The results suggest that the mycelium of Rhizopus sp. catalyzes the glycosidation at the C-4 position of zearalenone.
Viable but nonculturable stage of Campylobacter jejuni and its role in survival in the natural aquatic environment
Authors: Rollins D M , Colwell R R
Published: January 2020

Conditions influencing the survival of Campylobacter jejuni in the natural aquatic environment have been determined. Release of Campylobacter spp. into natural waters by animal hosts is postulated to play a key role in the maintenance of viability and transmission of the organism in the environment. Laboratory flask microcosms containing filter-sterilized stream water were used to test C. jejuni for the ability to remain viable in simulated natural systems. The microcosms were compared with the biphasic and shaking broth procedures used routinely for growth of Campylobacter spp. in the research laboratory. The stream-water microcosms were analyzed to determine effects of temperature and aeration on the survival of a well-characterized C. jejuni strain isolated originally from a human campylobacteriosis patient. Morphological characteristics were evaluated by phase-contrast microscopy and scanning or transmission electron microscopy. Survival curves were quantified on the basis of plate counts, epifluorescent microscopy, optical density measurements, and direct viable counts associated with protein synthesis in the absence of DNA replication. A significant difference was observed between results of direct enumeration, i.e., direct viable counts or acridine orange direct counts, and those from spread plate cultures. In all cases, increasing temperature of cultivation resulted in decreased recoverability on laboratory media, due possibly to an increased metabolic rate, as analyzed by CO2 evolution in the presence of radiolabeled glutamate. Stream water held at low temperature (4 degrees C) sustained significant numbers of campylobacters for greater than 4 months. Microcosms, aerated with shaking, exhibited logarithmic decline in recoverable C. jejuni, while stationary systems underwent a more moderate rate of decrease to the nonculturable state.(ABSTRACT TRUNCATED AT 250 WORDS)
New Procedure for Extraction of Ammonium from Natural Waters for
15
N Isotopic Ratio Determinations
Authors: Selmer Johanne-Sophie , Sörensson Fred
Published: January 2020

A new method for extracting ammonium from natural waters for
15
N isotopic ratio determination is described. The method employs the conversion of the ammonium nitrogen into indophenol, which is then concentrated onto an octadecylsilane column. The method shows accuracy and precision comparable to those of other methods described in the literature. Some results from field experiments on the Swedish west coast are presented.
Differential Effects of Lithium Chloride on In Vitro Growth of
Clavibacter michiganense
subsp.
nebraskense
Depending upon Inoculum Source
Authors: Smidt Mary L. , Vidaver Anne K.
Published: January 2020

The bacterium
Clavibacter michiganense
subsp.
nebraskense
(
Corynebacterium michiganense
subsp.
nebraskense
) was grown in broth cultures and inoculated into corn plants. The plating efficiency of cells from broth cultures was essentially the same on nutrient broth-yeast extract and the semiselective medium for this bacterium, CNS. However, when cells were isolated from Goss bacterial wilt- and blight-infected corn, very few were recovered on CNS compared with the amount recovered on nutrient broth-yeast extract agar. When lithium chloride was omitted from the CNS, recoveries from infected corn were nearly the same as on nutrient broth-yeast extract agar. No other ingredient of CNS was inhibitory, nor did substitution of other salts for lithium chloride cause equal inhibition. The amount of inhibition was proportional to lithium chloride concentration. The inhibition by lithium chloride occurred with several strains of the bacterium isolated from one corn cultivar and with one of the strains recovered from three different cultivars of infected corn.
T-2 toxin production by Fusarium acuminatum isolated from oats and barley
Authors: Rabie C J , Sydenham E W , Thiel P G , Lübben A , Marasas W F
Published: January 2020

Oats grain from South Africa was frequently found to be infested by toxic strains of Fusarium acuminatum, as was one barley sample. All 11 toxic strains tested produced T-2 toxin (0.8 to 2,600 mg/kg), and 6 of 11 strains produced diacetoxyscirpenol (0.6 to 8.4 mg/kg). This is the first record of T-2 toxin-producing Fusarium isolates from Africa and of the production of large amounts of T-2 toxin at relatively high (25 degrees C) temperatures.
Time required for tumor induction by Agrobacterium tumefaciens
Authors: Sykes L C , Matthysse A G
Published: January 2020

Cellulose-minus mutants of Agrobacterium tumefaciens retain virulence but can be removed from wound sites by washing with water. Washing of Bryophyllum diagremontiana leaves inoculated with a cellulose-minus mutant was used to determine the minimum time the bacteria must be present for tumor induction. This time was 4 to 8 h.
Simplified Method for Dissolved DNA Determination in Aquatic Environments
Authors: DeFlaun Mary F. , Paul John H. , Davis Dean
Published: January 2020

A method was developed for the determination of dissolved DNA in aquatic environments. The method is based upon the concentration of dissolved DNA by ethanol precipitation of 0.2-μm-pore-size filtered water. The DNA in concentrated extracts was quantified by the fluorescence of Hoechst 33258-DNA complexes. Fluorescence not attributable to DNA was corrected for by DNase I digestion of the extracts and averaged 25% of the total fluorescence for all samples. The effectiveness of the procedure for concentrating dissolved DNA was demonstrated by the efficient (>90%) recovery of internal standards. Concentrations of dissolved DNA from a variety of marine and freshwater environments ranged from 0.2 to 44 μg/liter, with the highest values being obtained for estuarine and river environments. The method is simple, specific for DNA, and more sensitive than previously described methods for the determination of extracellular DNA.
Substrate utilization by Campylobacter jejuni and Campylobacter coli
Authors: Westfall H N , Rollins D M , Weiss E
Published: January 2020

An attempt was made to elucidate in Campylobacter spp. some of the physiologic characteristics that are reflected in the kinetics of CO2 formation from four 14C-labeled substrates. Campylobacter jejuni and C. coli were grown in a biphasic medium, and highly motile spiral cells were harvested at 12 h. Of the media evaluated for use in the metabolic tests, minimal essential medium without glutamine, diluted with an equal volume of potassium sodium phosphate buffer (pH 7.2), provided the greatest stability and least competition with the substrates to be tested. The cells were incubated with 0.02 M glutamate, glutamine, alpha-ketoglutarate, or formate, or with concentrations of these substrates ranging from 0.0032 to 0.125 M. All four substrates were metabolized very rapidly by both species. A feature of many of these reactions, particularly obvious with alpha-ketoglutarate, was an immediate burst of CO2 production followed by CO2 evolution at a more moderate rate. These diphasic kinetics of substrate utilization were not seen in comparable experiments with Escherichia coli grown and tested under identical conditions. With C. jejuni, CO2 production from formate proceeded rapidly for the entire period of incubation. The rate of metabolism of glutamate, glutamine, and alpha-ketoglutarate by both species was greatly enhanced by increased substrate concentration. The approach to the study of the metabolism of campylobacters here described may be useful in detecting subtle changes in the physiology of cells as they are maintained past their logarithmic growth phase.
Purification and Biochemical Analysis of the Cytoplasmic Membrane from the Desiccation-Tolerant Cyanobacterium
Nostoc commune
UTEX 584
Authors: Olie Jaap J. , Potts Malcolm
Published: January 2020

The cytoplasmic membrane of the heterocystous cyanobacterium
Nostoc commune
UTEX 584 was isolated free of thylakoids and phycobiliprotein-membrane complexes by flotation centrifugation. Purified membranes had a buoyant density of 1.07 g cm
−3
and were bright orange. Twelve major proteins were detected in the membrane, and of these, the most abundant had molecular masses of 83, 71, 68, 51, and 46 kilodaltons. The ester-linked fatty acids of the methanol fraction contained 16:0, 18:0, 18:1ω9c, 20:0, and 20:3ω3 with no traces of hydroxy fatty acids. Compound 20:3ω3 represented 56.8% of the total fatty acid methyl esters, a feature which distinguishes the cell membrane of
N. commune
UTEX 584 from those of all other cyanobacteria which have been characterized to date. Fatty acid 18:3 was not detected. Carotenoids were analyzed by highperformance liquid chromatography. The cytoplasmic membrane contained β-carotene and echinenone as the dominant carotenoids and lacked chlorophyll
a
and pheophytin
a.
Whole cells contained β-carotene and echinenone, and lesser amounts of zeaxanthin and (3
R
)-cryptoxanthin.
Bacterial Physiological Diversity in the Rhizosphere of Range Plants in Response to Retorted Shale Stress
Authors: Metzger W. C. , Klein D. A. , Redente E. F.
Published: January 2020

Bacterial populations were isolated from the soil-root interface and root-free regions of
Agropyron smithii
Rydb. and
Atriplex canescens
(Pursh) Nutt. grown in soil, retorted shale, or soil over shale. Bacteria isolated from retorted shale exhibited a wider range of tolerance to alkalinity and salinity and decreased growth on amino acid substrates compared with bacteria from soil and soil-over-shale environments. Exoenzyme production was only slightly affected by growth medium treatment. Viable bacterial populations were higher in the rhizosphere and rhizoplane of plants grown in retorted shale than in plants grown in soil or soil over shale. In addition, a greater number of physiological groups of rhizosphere bacteria was observed in retorted shale compared with soil alone. Two patterns of community similarity were observed in comparisons of bacteria from soil over shale with those from soil and retorted-shale environments. Root-associated populations from soil over shale had a higher proportion of physiological groups in common with those from the soil control than with those from the retorted-shale treatment. However, in non-rhizosphere populations, bacterial groups from soil over shale more closely resembled the physiological groups from retorted shale.
Acetylene Metabolism and Stimulation of Denitrification in an Agricultural Soil
Authors: Topp Edward , Germon Jean-Claude
Published: January 2020

The effects of C
2
H
2
metabolism on N
2
O production were examined in soil slurries. Enrichment of C
2
H
2
consumption activity occurred only in aerobic incubations. Rapid disappearance of subsequent C
2
H
2
additions, stimulation of CO
2
production, and most-probable-number enumerations of C
2
H
2
utilizers indicated enrichment of the population responsible. During C
2
H
2
consumption in slurries incubated statically under air, maximal rates of N
2
O evolution were 19 times higher than those in anaerobic incubations. After 20 days of enrichment with C
2
H
2
, the production of N
2
O by slurries supplemented with C
2
H
2
and nitrate was 10 times higher than that in the unenriched controls. A
Nocardia
- or
Arthrobacter
-like bacterium was isolated that grew on C
2
H
2
but did not denitrify. The behavior of soil inoculated with this bacterium became similar to that of C
2
H
2
-enriched soil incubated aerobically. Ethanol, acetate, and acetaldehyde were identified in enrichment experiments, and denitrification in soil slurries was stimulated by addition of the supernatant from a pure culture grown on mineral medium with C
2
H
2
. These results indicate that denitrification can be stimulated by the actions of an aerobic, nondenitrifying C
2
H
2
-metabolizing population. Utilization of intermediate metabolites by denitrifiers and enhanced O
2
consumption are two possible mechanisms for this stimulation.
Thirteen Virulent and Temperate Bacteriophages of
Lactobacillus bulgaricus
and
Lactobacillus lactis
Belong to a Single DNA Homology Group
Authors: Mata Mireille , Trautwetter Annie , Luthaud Gisèle , Ritzenthaler Paul
Published: January 2020

Thirteen virulent phages and two temperate phages of two closely related bacterial species (
Lactobacillus lactis
and
L. bulgaricus
) were compared for their protein composition, their antigenic properties, their restriction endonuclease patterns, and their DNA homology. The immunoblotting studies and the DNA-DNA hybridizations showed that the phages could be differentiated into two groups. One group contained 2 temperate phages of
L. bulgaricus
and 11 virulent phages of
L. lactis.
Inside each group, at least two common proteins of identical sizes could be detected for each phage. These proteins were able to cross-react in immunoblotting experiments with an antiserum raised against one phage of the same group. Temperate phage DNAs showed partial homology with DNAs from some virulent phages. These homologies seem to be located on the region coding for the structural proteins since recombinant plasmids coding for one of the major phage proteins of one phage were able to hybridize with the DNAs from phages of the same group. These results suggest that temperate and virulent phages may be related to one another.
Behavior of Vibrio cholerae in hot foods
Authors: Makukutu C A , Guthrie R K
Published: January 2020

Four food types held hot at 45 to 60 degrees C were deliberately contaminated with O1 and non-O1 Vibrio cholerae strains. These organisms were assayed for survival and recovery from the foods within 1 h of the time the food was kept hot. The results showed no growth of V. cholerae non-O1 on thiosulfate-citrate bile-sucrose agar plates after 24 h of incubation at 37 degrees C for food held hot at 50 to 60 degrees C. Growth was low for V. cholerae O1 and was not achieved in some instances in which foods were held at either 55 or 60 degrees C after 40 or 60 min of from the time the food was kept hot. Both organisms, however, were recovered equally from all food types held at all temperatures after 48 h of incubation. When incubated for an additional 24 h, the organisms grew to unusually small-sized colonies, measuring 0.1 to 0.3 mm in diameter, on the same agar plates that were negative for growth after an initial 24 h of incubation. It was concluded that V. cholerae survived the period of time held at hot temperatures. Although the organisms were not recovered from some foods when held at some of the temperatures and times after 24 h of incubation, they remained viable. An incubation period of 48 h at 37 degrees C was found to be appropriate for the recovery of V. cholerae from hot foods.
Utilization of ornithine and arginine as specific precursors of clavulanic acid
Authors: Romero J , Liras P , Martín J F
Published: January 2020

Ornithine and arginine (5 to 20 mM), but not glutamic acid or proline, exerted a concentration-dependent stimulatory effect on the biosynthesis of clavulanic acid in both resting-cell cultures and long-term fermentations of Streptomyces clavuligerus. Ornithine strongly inhibited cephamycin biosynthesis in the same strain. [1-14C]-, [5-14C]-, or [U-14 C] ornithine was efficiently incorporated into clavulanic acid, whereas the incorporation of uniformly labeled glutamic acid was very poor. [U-14C] citrulline were not incorporated at all. Mutant nca-1, a strain that is blocked in clavulanic acid biosynthesis, did not incorporate arginine into clavulanic acid. S. clavuligerus showed arginase activity, converting arginine into ornithine, but not amidinotransferase activity. Both arginase activity and clavulanic acid formation were enhanced simultaneously by supplementing the production medium with 10 mM arginine.
Radiation resistance of lactobacilli isolated from radurized meat relative to growth and environment
Authors: Hastings J W , Holzapfel W H , Niemand J G
Published: January 2020

Of 113 lactobacilli isolated from radurized (5 kGy) minced meat, 7 Lactobacillus sake strains, 1 L. curvatus strain, and 1 L. farciminis strain were used for radiation resistance studies in a semisynthetic substrate (i.e., modified MRS broth). Five reference Lactobacillus spp., one Staphylococcus aureus strain, and one Salmonella typhimurium strain were used for comparative purposes. All L. sake isolates exhibited the phenomenon of being more resistant to gamma-irradiation in the exponential (log) phase than in the stationary phase of their growth cycles by a factor of 28%. Four references strains also exhibited this phenomenon, with L. sake (DSM 20017) showing a 68% increase in resistance in the log phase over the stationary phase. This phenomenon was not common to all bacteria tested and is not common to all strains with high radiation resistance. Four L. sake isolates and three reference strains were used in radiation sensitivity testing in a natural food system (i.e., meat). The bacteria were irradiated in minced meat and packaged under four different conditions (air, vacuum, CO2, and N2). Organisms exhibited the highest death rate (lowest D10 values [doses required to reduce the logarithm of the bacterial population by 1] ) under CO2 packaging conditions, but resistance to irradiation was increased under N2. The D10 values of the isolates were generally greater than those of the reference strains. The D10 values were also higher (approximately two times) in meat than in semisynthetic growth medium.
Selection of Yeasts for Breadmaking by the Frozen-Dough Method
Authors: Oda Yuji , Uno Kazuo , Ohta Shigenori
Published: January 2020

Eleven yeast strains suitable for frozen dough were selected from over 300
Saccharomyces
strains. All of these were identified as
Saccharomyces cerevisiae
from morphological, cultural, and physiological characteristics. The selected yeast cells accumulated a higher amount of trehalose than did commercial bakers' yeast cells.
Rapid Microbial Mineralization of Toluene and 1,3-Dimethylbenzene in the Absence of Molecular Oxygen
Authors: Zeyer J. , Kuhn E. P. , Schwarzenbach R. P.
Published: January 2020

Up to 0.4 mM 1,3-dimethylbenzene (
m
-xylene) was rapidly mineralized in a laboratory aquifer column operated in the absence of molecular oxygen with nitrate as an electron acceptor. Under continuous flow conditions, the degradation rate constant (pseudo-first order) was >0.45 h
−1
. Based on a carbon mass balance with [ring-
14
C]
m
-xylene and a calculation of the electron balance,
m
-xylene was shown to be quantitatively (80%) oxidized to CO
2
with a concomitant reduction of nitrate. The mineralization of
m
-xylene in the column also took place after reducing the redox potential, E′, of the inflowing medium with sulfide to <−0.11 V. Microorganisms adapted to growth on
m
-xylene were also able to degrade toluene under denitrifying conditions. These results suggest that aromatic hydrocarbons present in anoxic environments such as lake sediments, sludge digestors, and groundwater infiltration zones from landfills and polluted rivers are not necessarily persistent but may be mineralized in the absence of molecular oxygen.
Quantitative method for measurement of aerotolerance of bacteria and its application to oral indigenous anaerobes
Authors: Kikuchi H E , Suzuki T
Published: January 2020

An index which expressed the aerobic to anaerobic potential was made for bacteria with intermediate tolerance for oxygen. One method used for this analysis was measurement of the relative bacterial growth ratio. The other method was based on the pattern of the absorbancy versus depth plot. The index was applied to oral indigenous anaerobes.
Metabolism of Reduced Methylated Sulfur Compounds in Anaerobic Sediments and by a Pure Culture of an Estuarine Methanogen
Authors: Kiene Ronald P. , Oremland Ronald S. , Catena Anthony , Miller Laurence G. , Capone Douglas G.
Published: January 2020

Addition of dimethylsulfide (DMS), dimethyldisulfide (DMDS), or methane thiol (MSH) to a diversity of anoxic aquatic sediments (e.g., fresh water, estuarine, alkaline/hypersaline) stimulated methane production. The yield of methane recovered from DMS was often 52 to 63%, although high concentrations of DMS (as well as MSH and DMDS) inhibited methanogenesis in some types of sediments. Production of methane from these reduced methylated sulfur compounds was blocked by 2-bromoethanesulfonic acid. Sulfate did not influence the metabolism of millimolar levels of DMS, DMDS, or MSH added to sediments. However, when DMS was added at ∼2-μM levels as [
14
C]DMS, metabolism by sediments resulted in a
14
CH
4
/
14
CO
2
ratio of only 0.06. Addition of molybdate increased the ratio to 1.8, while 2-bromoethanesulfonic acid decreased it to 0, but did not block
14
CO
2
production. These results indicate the methanogens and sulfate reducers compete for DMS when it is present at low concentrations; however, at high concentrations, DMS is a “noncompetitive” substrate for methanogens. Metabolism of DMS by sediments resulted in the appearance of MSH as a transient intermediate. A pure culture of an obligately methylotrophic estuarine methanogen was isolated which was capable of growth on DMS. Metabolism of DMS by the culture also resulted in the transient appearance of MSH, but the organism could grow on neither MSH nor DMDS. The culture metabolized [
14
C]-DMS to yield a
14
CH
4
/
14
CO
2
ratio of ∼2.8. Reduced methylated sulfur compounds represent a new class of substrates for methanogens and may be potential precursors of methane in a variety of aquatic habitats.
DNA-damaging activity of patulin in Escherichia coli
Authors: Lee K S , Röschenthaler R J
Published: January 2020

At a concentration of 10 micrograms/ml, patulin caused single-strand DNA breaks in living cells of Escherichia coli. At 50 micrograms/ml, double-strand breaks were observed also. Single-strand breaks were repaired in the presence of 10 micrograms of patulin per ml within 90 min when the cells were incubated at 37 degrees C in M9-salts solution without a carbon source. The same concentration also induced temperature-sensitive lambda prophage and a prophage of Bacillus megaterium. When an in vitro system with permeabilized Escherichia coli cells was used, patulin at 10 micrograms/ml induced DNA repair synthesis and inhibited DNA replication. The in vivo occurrence of DNA strand breaks and DNA repair correlated with the in vitro induction of repair synthesis. In vitro the RNA synthesis was less affected, and overall protein synthesis was not inhibited at 10 micrograms/ml. Only at higher concentrations (250 to 500 micrograms/ml) was inhibition of in vitro protein synthesis observed. Thus, patulin must be regarded as a mycotoxin with selective DNA-damaging activity.
Relationship of formate to growth and methanogenesis by Methanococcus thermolithotrophicus
Authors: Belay N , Sparling R , Daniels L
Published: January 2020

Methanococcus thermolithotrophicus is a methanogenic archaebacterium that can use either H2 or formate as its source of electrons for reduction of CO2 to methane. Growth and suspended-whole-cell experiments show that H2 plus CO2 methanogenesis was constitutive, while formate methanogenesis required adaptation time; selenium was necessary for formate utilization. Cells grown on formate had 20 to 100 times higher methanogenesis rates on formate than cells grown on H2-CO2 and transferred into formate medium. Enzyme assays with crude extracts and with F420 or methyl viologen as the electron acceptor revealed that hydrogenase was constitutive, while formate dehydrogenase was regulated. Cells grown on formate had 10 to 70 times higher formate dehydrogenase activity than cells grown on H2-CO2 with Se present in the medium; when no Se was added to H2-CO2 cultures, even lower activities were observed. Adaptation to and growth on formate were pH dependent, with an optimal pH for both about one pH unit above that optimal for H2-CO2 (pH 5.8 to 6.5). When cells were grown on H2-CO2 in the presence of formate, formate (greater than or equal to 50 mM) inhibited both growth and methanogenesis at pH 5.8 to 6.2, but not at pH greater than 6.6. Both acetate and propionate produced similar inhibition. Formate inhibition was also observed in Methanospirillum hungatei.
Distribution of Hydrogen-Metabolizing Bacteria in Alfalfa Field Soil
Authors: Cunningham Scott D. , Kapulnik Yoram , Phillips Donald A.
Published: January 2020

H
2
evolved by alfalfa root nodules during the process of N
2
fixation may be an important factor influencing the distribution of soil bacteria. To test this hypothesis under field conditions, over 700 bacterial isolates were obtained from fallow soil or from the 3-mm layer of soil surrounding alfalfa (
Medicago sativa
L.) root nodules, alfalfa roots, or bindweed (
Convolvulus arvensis
L.) roots. Bacteria were isolated under either aerobic or microaerophilic conditions and were tested for their capacity to metabolize H
2
. Isolates showing net H
2
uptake and
3
H
2
incorporation activity under laboratory conditions were assigned a Hup
+
phenotype, whereas organisms with significant H
2
output capacity were designated as a Hout
+
phenotype. Under aerobic isolation conditions two Hup
+
isolates were obtained, whereas under microaerophilic conditions five Hup
+
and two Hout
+
isolates were found. The nine isolates differed on the basis of 24 standard bacteriological characteristics or fatty acid composition. Five of the nine organisms were isolated from soil around root nodules, whereas the other four were found distributed among the other three soil environments. On the basis of the microaerophilic isolations, 4.8% of the total procaryotic isolates from soil around root nodules were capable of oxidizing H
2
, and 1.2% could produce H
2
. Two of the Hup
+
isolates were identified as
Rhizobium meliloti
by root nodulation tests, but the fact that none of the isolates reduced C
2
H
2
under the assay conditions suggested that the H
2
metabolism traits were associated with various hydrogenase systems rather than with nitrogenase activity. Results from this study support the concept that H
2
evolution by alfalfa root nodules has a significant effect on the surrounding microenvironment and influences the number and diversity of bacteria occupying that region.
Heterotrophic Nitrification in an Acid Forest Soil and by an Acid-Tolerant Fungus
Authors: Stroo Hans F. , Klein Theodore M. , Alexander Martin
Published: January 2020

Nitrate was formed from ammonium at pH 3.2 to 6.1 in suspensions of a naturally acid forest soil; the maximum rates of formation occurred at ca. pH 4 to 5. Nitrate was also formed from soil nitrogen in suspensions incubated at 50°C. Autotrophic nitrifying bacteria could not be isolated from this soil. Enrichment cultures produced nitrate in a medium with β-alanine if much soil was added to the medium, and nitrite but not nitrate was formed in the presence of small amounts of soil. Nitrification by these enrichments was abolished by eucaryotic but not procaryotic inhibitors. A strain of
Absidia cylindrospora
isolated from this soil was found to produce nitrate and nitrite in a medium with β-alanine at pH values ranging from 4.0 to 4.8. Nitrate production by
A. cylindrospora
required the presence of sterile soil. Free and bound hydroxylamine, hydroxamic acids, and primary aliphatic nitro compounds did not accumulate during the conversion of β-alanine to nitrite by the fungus. The organism also formed nitrite from ammonium in a medium containing acetate. We suggest that nitrification in this soil is a heterotrophic process catalyzed by acid-tolerant fungi and not by autotrophs or heterotrophs in nonacid microsites.
Color mutants of Aspergillus flavus and Aspergillus parasiticus in a study of preharvest invasion of peanuts
Authors: Cole R J , Hill R A , Blankenship P D , Sanders T H
Published: January 2020

A comparison of the invasion of flowers, aerial pegs, and kernels by wild-type and mutant strains of Aspergillus flavus or A. parasiticus along with aflatoxin analyses of kernels from different drought treatments have supported the hypothesis that preharvest contamination with aflatoxin originates mainly from the soil. Evidence in support of soil invasion as opposed to aerial invasion was the following. A greater percentage of invasion of kernels rather than flower or aerial pegs by either wild-type A. flavus or mutants. Significant invasion by an A. parasiticus color mutant occurred only in peanuts from soil supplemented with the mutant, whereas adjacent plants in close proximity but in untreated soil were only invaded by wild-type A. flavus or A. parasiticus. Aflatoxin data from drought-stressed, visibly undamaged peanut kernels showed that samples from soil not supplemented with a mutant strain contained a preponderance of aflatoxin B's (from wild-type A. flavus) whereas adjacent samples from mutant-supplemented soil contained a preponderance of B's plus G's (from wild-type and mutant A. parasiticus). Preliminary data from two air samplings showed an absence of propagules of A. flavus or A. parasiticus in air around the experimental facility.
Stimulation of Bacterial DNA Synthesis by Algal Exudates in Attached Algal-Bacterial Consortia
Authors: Murray Robert E. , Cooksey Keith E. , Priscu John C.
Published: January 2020

Algal-bacterial consortia attached to polystyrene surfaces were prepared in the laboratory by using the marine diatom
Amphora coffeaeformis
and the marine bacterium
Vibrio proteolytica
(the approved name of this bacterium is
Vibrio proteolyticus
[W. E. C. Moore, E. P. Cato, and L. V. H. Moore, Int. J. Syst. Bacteriol. 35:382-407, 1985]). The organisms were attached to the surfaces at cell densities of approximately 5 × 10
4
cells cm
-2
(diatoms) and 5 × 10
6
cells cm
-2
(bacteria). The algal-bacterial consortia consistently exhibited higher rates of [
3
H]thymidine incorporation than did biofilms composed solely of bacteria. The rates of [
3
H]thymidine incorporation by the algal-bacterial consortia were fourfold greater than the rates of incorporation by monobacterial biofilms 16 h after biofilm formation and were 16-fold greater 70 h after biofilm formation. Extracellular material released from the attached
Amphora
cells supported rates of bacterial activity (0.8 × 10
-21
to 17.9 × 10
-21
mol of [
3
H]thymidine incorporated cell
-1
h
-1
) and growth (doubling time, 29.5 to 1.4 days) comparable to values reported for a wide variety of marine and freshwater ecosystems. In the presence of sessile diatom populations, DNA synthesis by attached
V. proteolytica
cells was light dependent and increased with increasing algal abundance. The metabolic activity of diatoms thus appears to be the rate-limiting process in biofilm development on illuminated surfaces under conditions of low bulk-water dissolved organic carbon.
Multiple antibiotics produced by Pseudomonas fluorescens HV37a and their differential regulation by glucose
Authors: James D W , Gutterson N I
Published: January 2020

Pseudomonas fluorescens HV37a inhibited growth of the fungus Pythium ultimum on potato dextrose agar (PDA). An antibiotic activity produced under these conditions was fractionated and partially characterized. Extracts prepared from the PDA on which HV37a was grown revealed a single peak of antibiotic activity on thin-layer chromatograms. Similar extracts were prepared from mutants of HV37a. Their analysis indicated that the antibiotic observed in thin-layer chromatograms was responsible for fungal inhibition observed on PDA. The production of the PDA antibiotic required the presence of glucose, whereas two other antibiotic activities were produced only on potato agar without added glucose. Two mutants (denoted AfuIa and AfuIb) previously characterized as deficient in fungal inhibition on PDA showed altered regulation of the production of all three antibiotics in response to glucose. These mutants were also deficient in glucose dehydrogenase. Mutants isolated as deficient in glucose dehydrogenase were also deficient in fungal inhibition and were grouped into two classes on the basis of complementation analysis with an AfuI cosmid. Glucose regulation of antibiotic biosynthesis therefore involves at least two components and requires glucose dehydrogenase.
Bacterial communities degrading amino- and hydroxynaphthalene-2-sulfonates
Authors: Nörtemann B , Baumgarten J , Rast H G , Knackmuss H J
Published: January 2020

A 6-aminonaphthalene-2-sulfonic acid (6A2NS)-degrading mixed bacterial community was isolated from a sample of river Elbe water. The complete degradation of this xenobiotic compound may be described by a mutualistic interaction of two Pseudomonas strains isolated from this culture. One strain, BN6, could also grow on 6A2NS in monoculture, however, with accumulation of black polymers. This organism effected the initial conversion of 6A2NS into 5-aminosalicylate (5AS) through regioselective attack of the naphthalene skeleton in the 1,2-position. 5AS was totally degraded by another member of the community, strain BN9. After prolonged adaptation of strain BN6 to growth on 6A2NS, this organism readily converted all naphthalene-2-sulfonates with OH- or NH2-substituents in the 5-, 6-, 7-, or 8-position. The corresponding hydroxy- or aminosalicylates were excreted in stoichiometric amounts, with the exception that the metabolite from 5A2NS oxidation was not identical with 6AS.
Further Verification of the Isotope Dilution Approach for Estimating the Degree of Participation of [
3
H]thymidine in DNA Synthesis in Studies of Aquatic Bacterial Production
Authors: Bell Russell T.
Published: January 2020

The optimal concentration of [
3
H]thymidine (i.e., the maximal degree of participation in DNA synthesis) as determined by adding increasing amounts of labeled thymidine at the same specific activity was similar to the concentration of thymidine inhibiting the de novo pathway as determined by isotope dilution plots. These experiments provide further verification of the isotope dilution approach for determining the degree of participation of [
3
H]thymidine in DNA synthesis.
Magnesium limitation and its role in apparent toxicity of ethanol during yeast fermentation
Authors: Dombek K M , Ingram L O
Published: January 2020

The rate of ethanol production per milligram of cell protein begins to decline in the early stage of batch fermentation before high concentrations of ethanol have accumulated. In yeast extract-peptone medium (20% glucose), this initial decline appears to be related to growth and to result in part from a nutrient deficiency. The addition of yeast extract, peptone, and ashed preparations of these restored the ability of glucose-reconstituted medium (in which cells had been previously grown) to support vigorous growth. Magnesium was identified as the active component. Supplementing fermentations with 0.5 mM magnesium prolonged exponential growth, resulting in increased yeast cell mass. The addition of magnesium also reduced the decline in fermentative activity (micromoles of CO2 evolved per hour per milligram of protein) during the completion of batch fermentations. These two effects reduced the time required for the conversion of 20% glucose into ethanol by 1/3 with no measurable loss in ethanol yield (98% of theoretical maximum yield). It is possible that some of the reported beneficial effects of complex nutrients (soy flour and yeast extract) for ethanol production also result from the correction of a simple inorganic ion deficiency, such as magnesium.
Properties of Cytophaga johnsonae strains causing spoilage of fresh produce at food markets
Authors: Liao C H , Wells J M
Published: January 2020

Two strains of gliding, orange-pigmented bacteria, isolated from fresh bell pepper and watermelon, respectively, showing soft-rot lesions, were identified as Cytophaga johnsonae. They differed from seven type strains of C. johnsonae deposited at the American Type Culture Collection (ATCC) in some properties, such as the ability to utilize glucose, xylose, trehalose, rhamnose, and sucrose. Spherical bodies resembling microcysts of Sporocytophaga sp. in addition to short rods and long filaments were observed in two strains (ATCC 29583 and 29588) throughout the growth cycle and also in aged cultures of other strains. All strains examined were shown to degrade five natural or synthetic polymers (pectin, chitin, starch, protein, and carboxymethyl cellulose). Only six strains (including ATCC 17061, 29587, 29589, and 19366) were able to infect and macerate artificially wounded potato tubers and fruits of pepper, squash, and tomato. The pathogenic strains secreted more pectate lyase in broth medium than the nonpathogenic strains. C. johnsonae, generally known as a soil saprophyte, might occasionally act as an opportunistic pathogen, causing decay of fresh produce in storage or in transit.
Action of citrinin on bacterial chromosomal and plasmid DNA in vivo and in vitro
Authors: Martin W , Lorkowski G , Creppy E E , Dirheimer G , Röschenthaler R
Published: January 2020

Citrinin, a mycotoxin of Penicillium citrinum and other species of the genera Penicillium and Aspergillus, caused the following effects at different concentrations in Escherichia coli. In vivo at 100 micrograms/ml single-strand breaks were caused in the chromosomal DNA. In the presence of 100 micrograms/ml, UV (254 nm)-induced DNA damage was repaired in the bacterial cells without need for a complete growth medium. At 300 micrograms/ml lambda ts prophage was induced in a lysogenic E. coli strain. In an E. coli strain carrying a F' lac plasmid, 4.7% of the cells displayed the Lac- phenotype after treatment with 200 micrograms of citrinin per ml, suggesting elimination of the F' factor. In vitro, DNA repair synthesis was observed at 5 micrograms of citrinin per ml in permeabilized cells, and replicative DNA synthesis was inhibited at 200 micrograms/ml. In these systems synthesis of stable RNAs was slightly diminished at 300 micrograms/ml, and protein synthesis was not affected at concentrations up to 450 micrograms/ml. Lambda and ColE1 plasmid DNA were cleaved in vitro when small amounts of copper ions were present. This DNA-attacking activity was prevented by NADPH, catalase, and superoxide dismutase and by higher concentrations of hydroxyl radical scavengers, suggesting the involvement of free radicals in the mechanism of action of citrinin on DNA.
Degradation of 1,4-dichlorobenzene by Alcaligenes sp. strain A175
Authors: Schraa G , Boone M L , Jetten M S , van Neerven A R , Colberg P J , Zehnder A J
Published: January 2020

An organism, identified as an Alcaligenes sp., was isolated from an enrichment culture in which 1,4-dichlorobenzene served as the sole carbon and energy source. During growth with 1,4-dichlorobenzene in pure culture, stoichiometric amounts of chloride were released. Growth experiments and oxygen uptake rates with other chlorinated aromatic compounds revealed a high degree of specificity of the initial dioxygenase. cis-1,2-Dihydroxycyclohexa-3,5-diene oxidoreductase and 1,2-pyrocatechase, but not 2,3-pyrocatechase, were found in cell extracts, while 3,6-dichlorocatechol and (2,5-dichloro)muconic acid could be detected as intermediates during degradation of 1,4-dichlorobenzene. It is proposed that dioxygenases are involved in the initial steps of 1,4-dichlorobenzene degradation, while ring opening proceeds via ortho cleavage.
Location of plasmid-mediated citrate utilization determinant in R27 and incidence in other H incompatibility group plasmids
Authors: Taylor D E , Brose E C
Published: January 2020

Citrate utilization (Cit+) is encoded by a specific subgroup of incompatibility HI plasmids, viz., IncHI1 plasmids. Only one IncHI1 plasmid, pRG1271, which originated in a Mexican typhoid outbreak in 1972, did not specify Cit+. All other Cit+ plasmids hybridized to a Cit+ probe, a 2-kilobase BglII fragment derived from the Cit+ transposon Tn3411. The position of the Cit+ determinant was mapped to a 13.5-kilobase ApaI fragment within the prototype IncHI1 plasmid R27. No other functions have been mapped within this region. Citrate utilization mediated by IncHI1 was observed only after a prolonged lag period of approximately 150 h, and certain Escherichia coli strains, e.g., E. coli K-12 J53-1, were not able to utilize citrate specified by the H plasmids. Most E. coli strains harboring the multicopy Cit+ plasmid pOH2, a derivative of pBR322, required only 18 to 24 h to express the Cit+ phenotype, but E. coli J53-1 (pOH2) required at least 72 h for expression.
Symbiotic Characteristics and
Rhizobium
Requirements of a
Leucaena leucocephala
×
Leucaena diversifolia
Hybrid and Its Parental Genotypes
Authors: Somasegaran P. , Martin R. B.
Published: January 2020

In 56-day-old plants,
Leucaena leucocephala
and its hybrid with
L. diversifolia
showed 100% more total N than did
L. diversifolia.
Significant (
P
< 0.01) host-inoculation interaction in total N was 14.4% of the total phenotypic variation. The most effective and competitive
Rhizobium
sp. for the leucaenas was TAL 1145. Three-strain mixed inoculation was inferior to TAL 1145 alone.
Effects of Genotype, Spawn Run Time, and Substrate Formulation on Biological Efficiency of Shiitake
Authors: Royse D. J. , Bahler C. C.
Published: January 2020

Substrate formulations of sawdust, wheat bran, and millet were inoculated with spawns from one hybrid and two parental genotypes of
Lentinula edodes.
Biological efficiency (BE) and size data on mushrooms harvested from two substrate formulations with spawn run times of 60, 90, and 120 days were analyzed. A significant genotype-spawn run time-substrate formulation interaction was observed for BE. The longer spawn runs resulted in greater BE than the shorter spawn runs. This study points to the need for more work to determine the underlying variability within genotypes.
Methane Production from Formate by Syntrophic Association of
Methanobacterium bryantii
and
Desulfovibrio vulgaris
JJ
Authors: Guyot Jean-Pierre , Brauman Alain
Published: January 2020

Coculture of a sulfate-reducing bacterium, when grown in the absence of added sulfate, with
Methanobacterium bryantii
, which uses only H
2
and CO
2
for methanogenesis, degraded formate to CH
4
. A pure culture of
Desulfovibrio vulgaris
JJ was able to produce small amounts of H
2
. Such a syntrophic relationship might provide an additional way to avoid formate accumulation in anaerobic environments.
Inhibition of Clostridium botulinum 62A by fumarates and maleates and relationship of activity to some physicochemical constants
Authors: Dymicky M , Bencivengo M , Buchanan R L , Smith J L
Published: January 2020

A series of n-monoalkyl maleates and n-mono-, di-, and methyl n-alkyl fumarates were prepared, 18 esters of each, with R = CH3 to C18H37. Their activity against Clostridium botulinum was determined in culture medium. The n-monoalkyl maleates and fumarates possessed significant activity, particularly those esterified with higher C13 to C18 alcohols. Somewhat lower activity was exhibited by methyl n-alkyl fumarates, while symmetrical esters, di-n-alkyl fumarates, were almost inactive. An attempt was made to correlate the activity of n-monoalkyl maleates and fumarates with chain length, solubility in water, apparent dissociation constant (pKa'), and infrared and UV absorption frequencies. The active esters may have potential as preservatives in foods.
Microbiological Degradation of Malodorous Substances of Swine Waste under Aerobic Conditions
Authors: Bourque Denis , Bisaillon Jean-Guy , Beaudet R�jean , Sylvestre M. , Ishaque Muhammad , Morin Andr�
Published: January 2020

Phenol,
p
-cresol, and volatile fatty acids (VFA; acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids) were used as odor indicators of swine waste. Aeration of the waste allowed the indigenous microorganisms to grow and degrade these malodorous substances. The time required for degradation of these substances varied according to the waste used, and it was not necessarily related to their concentrations. Using a minimal medium which contained one of the malodorous compounds as sole carbon source, we have selected from swine waste microorganisms that can grow in the medium. The majority of these microorganisms were able to degrade the same substrate when inoculated in sterilized swine waste but with an efficiency varying from one strain to the other. None of these strains was able to degrade all malodorous substances studied. Within 6 days of incubation these selected strains degraded the following:
Acinetobacter calcoaceticus
, phenol and all VFA;
Alcaligenes faecalis
,
p
-cresol and all VFA;
Corynebacterium glutamicum
and
Micrococcus
sp., phenol,
p
-cresol, and acetic and propionic acids;
Arthrobacter flavescens
, all VFA. On a laboratory scale, the massive inoculation of swine waste with
C. glutamicum
or
Micrococcus
sp. accelerated degradation of the malodorous substances. However, this effect was not observed with all of the various swine wastes tested. These results suggest that an efficient deodorization process of various swine wastes could be developed at the farm level based on the aerobic indigenous microflora of each waste.
Averufanin is an aflatoxin B1 precursor between averantin and averufin in the biosynthetic pathway
Authors: McCormick S P , Bhatnagar D , Lee L S
Published: January 2020

Wild-type Aspergillus parasiticus produces, in addition to the colorless aflatoxins, a number of pigmented secondary metabolites. Examination of these pigments demonstrated that a major component was an anthraquinone, averufanin. Radiolabeling studies with [14C]averufanin showed that 23% of the label was incorporated into aflatoxin B1 by the wild type and that 31% of the label was incorporated into O-methylsterigmatocystin by a non-aflatoxin-producing isolate. In similar studies with blocked mutants of A. parasiticus the 14C label from averufanin was accumulated in averufin (72%) and versicolorin A (54%) but not averantin. The results demonstrate that averufanin is a biosynthetic precursor of aflatoxin B1 between averantin and averufin.
Cricket Paralysis Virus, a Potential Control Agent for the Olive Fruit Fly,
Dacus oleae
Gmel
Authors: Manousis Thanasis , Moore Norman F.
Published: January 2020

Representatives of several families of insect viruses were tested for growth and pathogenicity in the olive fruit fly,
Dacus oleae
Gmel. The viruses included nuclear polyhedrosis viruses, an iridovirus, two picornaviruses, and
Trichoplusia ni
small RNA virus (a member of the
Nudaurelia
β family), in addition to two naturally occurring viruses of the olive fruit fly. Two viruses, one of the two picornaviruses (cricket paralysis virus [CrPV] and the iridovirus (type 21 from
Heliothis armigera
), were found to replicate in adult flies. Flies which were fed on a solution containing CrPV for 1 day demonstrated a high mortality with 50% dying within 5 days and nearly 80% dying within 12 days of being fed. The virus was transmissible from infected to noninfected flies by fecal contamination. The CrPV which replicated in the infected flies was demonstrated to be the same as input virus by infection of
Drosophila melanogaster
cells and examination of the expressed viral proteins, immunoprecipitation of the virus purified from flies, and electrophoretic analysis of the structural proteins.