bluuebunny/crossref_metadata_2025 huggingface dataset:
Caffeine inhibition of aflatoxin production: mode of action
Authors: Buchanan R L , Hoover D G , Jones S B
Published: January 2020

Evaluation of caffeine and a number of related methylxanthines indicated that the ability of the compound to inhibit growth and aflatoxin production by Aspergillus parasiticus is highly specific and does not involve an inhibition of cyclic AMP phosphodiesterase. Supplementation of the culture medium with purine bases, nucleosides, and nucleotides suggested that the inhibition of fungal growth could be partially overcome by adenine or guanine but that the purines had little effect on the inhibition of aflatoxin production. Likewise, increasing the levels of trace minerals did not overcome the inhibition of toxin production. Electron microscopic evaluation of caffeine-treated and -untreated cultures indicated that the compound produced observable changes in the ultrastructure of the fungus.
Simple screening method for isolation of penicillin acylase-producing bacteria
Authors: Meevootisom V , Somsuk P , Prachaktam R , Flegel T W
Published: January 2020

A new screening method for bacteria capable of producing penicillin acylase is described. The method is based on the use of Serratia marcescens sensitive to 6-aminopenicillanic acid but comparatively resistant to benzylpenicillin. It is simple, quite specific, and requires no special equipment. It can also be used to screen for phenoxymethylpenicillin acylase activity. We also suggest an acidimetric method for rapid detection of cloned genes in genetic engineering studies of penicillin acylase.
Initial Phases of Starvation and Activity of Bacteria at Surfaces
Authors: Kjelleberg Staffan , Humphrey Beverley A. , Marshall Kevin C.
Published: January 2020

The activity of the hydrophilic
Vibrio
sp. strain DW1 and the hydrophobic
Pseudomonas
sp. strain S9, which both undergo starvation-induced responses, was examined at nutrient-enriched and nutrient-deficient interfaces. The initial period of response to a starvation regime (“dwarfing” phase) is a sequence of two processes: fragmentation and continuous size reduction of the fragmented cells. This dwarfing phase is also one of intense metabolic activity as supported by O
2
uptake measurements of the endogenous metabolism and the use of inhibitors of the proton flow, the electron transport chain, and membrane-bound ATPase. Hydrophilic bacteria become even smaller at nutrient-deficient surfaces than in the liquid phase upon starvation, and this is reflected in a higher endogenous metabolism exhibited by surface-associated cells compared with those in the liquid phase. On the other hand, hydrophobic bacteria dwarfing at surfaces did not exhibit a greater size reduction and exhibited an endogenous metabolism that was only slightly higher than that of cells in the liquid phase. Bacterial scavenging of surface-localized nutrients is related to the degree of irreversible binding of dwarf and starved bacteria, which in turn may be related to the degree of cell surface hydrophobicity.
Motility and Chemotaxis of
Rhizobium meliloti
in Soil
Authors: Soby Scott , Bergman Kostia
Published: January 2020

The spreading of
Rhizobium meliloti
strains in various autoclaved soils was measured by using simple modifications of established techniques. Behavioral mutants were used to demonstrate that efficient spreading requires active motility and chemotaxis. The rate of spreading was affected by physical or chemical differences among soils and by changes in water content.
Isolation and identification of pathogenic Naegleria australiensis (Amoebida, Vahlkampfiidae) from a spa in northern Italy
Authors: Scaglia M , Strosselli M , Grazioli V , Gatti S , Bernuzzi A M , de Jonckheere J F
Published: January 2020

Samples from therapeutic swimming pools and mud basins were cultured for free-living amoebae. Seven strains of pathogenic Naegleria species were isolated. Although some of the strains were as virulent as Naegleria fowleri, the etiological agent of primary amoebic meningoencephalitis, they were identified as Naegleria australiensis with the indirect fluorescent-antibody technique. The virulence of the isolates for mice corresponded with the cytopathic effect for Vero cells. The N. australiensis strains were isolated from swimming pools with water temperatures ranging from 32 to 35 degrees C and from mud with temperatures from 25 to 43 degrees C. The presence of pathogenic N. australiensis in the swimming pools did not correlate with bacterial indicators.
Siderophores Produced by Nitrogen-Fixing
Azotobacter vinelandii
OP in Iron-Limited Continuous Culture
Authors: Fekete Frank A. , Spence Jack T. , Emery Thomas
Published: January 2020

Azotobacter vinelandii
requires a high complement of iron and an efficient iron acquisition system to support nitrogen fixation. To circumvent problems inherent in batch culture trace metal studies, continuous cultures were used to measure the response of
A. vinelandii
to iron stress. Iron was found to be growth limiting for nitrogen-fixing
A. vinelandii
at a concentration as high as 12.5 μM; iron was growth sufficient at 25 μM. Iron-stressed
A. vinelandii
in continuous culture formed 2,3-hydroxybenzoic acid (DHB), 2-
N
,6-
N
-di-(2,3-dihydroxybenzoyl)-
l
-lysine (DHBL), and a chromophoric yellow-green fluorescent peptide (YGFP). At a fixed dilution rate of 0.1 h
−1
, steady-state growth occurred at growth-limiting iron concentrations. DHB and DHBL were quantitatively measured during iron-limited steady states and iron-sufficient states by Arnow colorimetric assays. YGFP was determined by absorbance measurements taken at 380 nm, and the concentration was calculated from the reported specific absorption coefficient. Biomass increased and DHBL, DHB, and YGFP concentrations decreased as the concentration of growth-limiting iron was increased in the culture vessel and medium reservoirs. DHBL was the major siderophore and YGFP was the minor siderophore species produced during iron-limited equilibrium growth. A low level of DHB and YGFP, but no DHBL, was formed under iron-sufficient conditions. These results provide further physiological evidence that DHB, YGFP, and especially DHBL may function as siderophores in nitrogen-fixing
A. vinelandii.
Classification of terverticillate penicillia based on profiles of mycotoxins and other secondary metabolites
Authors: Frisvad J C , Filtenborg O
Published: January 2020

Strains of available terverticillate penicillium species and varieties were analyzed for profiles of known mycotoxins and other secondary metabolites produced on Czapek yeast autolysate agar (intracellular metabolites) and yeast extract-sucrose agar (extracellular metabolites) by using simple thin-layer chromatography screening techniques. These strains (2,473 in all) could be classified into 29 groups based on profiles of secondary metabolites. Most of these profiles of secondary metabolites were distinct, containing several biosynthetically different mycotoxins and unknown metabolites characterized by distinct colors and retardation factors on thin-layer chromatography plates. Some species (P. italicum and P. atramentosum) only produced one or two metabolites by the simple screening methods. The 29 groups based on profiles of secondary metabolites were known species or subgroups thereof. These species and subgroups were independently identifiable by using morphological and physiological criteria. The species accepted, the number of isolates in each species investigated, and the mycotoxins they produced were: P. atramentosum, 4; P. aurantiogriseum, 510 (group I: penicillic acid and S-toxin and group II: penicillic acid, penitrem A [low frequency], terrestric acid [low frequency], viomellein, and xanthomegnin); P. brevicompactum, 81 (brevianamid A and mycophenolic acid); P. camembertii group I, 38, and group II, 114 (cyclopiazonic acid); P. chrysogenum, 87 (penicillin, roquefortine C, and PR-toxin); P. claviforme, 4 (patulin and roquefortine C); P. clavigerum, 4 (penitrem A); P. concentricum group I, 10 (griseofulvin and roquefortine C), and group II, 3 (patulin and roquefortine C); P. crustosum, 123 (penitrem A, roquefortine C, and terrestric acid); P. echinulatum, 13; P. expansum, 91 (citrinin, patulin, and roquefortine C); P. granulatum, 6 (patulin, penitrem A, and roquefortine C [traces]); P. griseofulvum, 21 (cyclopiazonic acid, griseofulvin, patulin, and roquefortine C); P. hirsutum, 100 (group I: terrestric acid; group II: citrinin, penicillic acid , roquefortine C, and terrestric acid; and group III: roquefortine C and terrestric acid), P. hirsutum group IV, 2 (chaetoglobosin C); P. isariiforme, 1; P. italicum, 41; P. mali, 104; P. roquefortii, 78 (group I: mycophenolic acid, PR-toxin, and roquefortine C and group II: mycophenolic acid, patulin, penicillic acid [low frequency], and roquefortine C); P. viridicatum group I, 634 (brevianamid A [low frequency], penicillic acid, viomellein, and xanthomegnin), P. viridicatum group II and III, 494 (citrinin and ochratoxin A), P. viridicatum group IV, 12 (griseofulvin and viridicatumtoxin). It is proposed that profiles of secondary metabolites be strongly emphasized in any future revision of the penicillia.
Analysis of Poly-β-Hydroxybutyrate in
Rhizobium japonicum
Bacteroids by Ion-Exclusion High-Pressure Liquid Chromatography and UV Detection
Authors: Karr Dale B. , Waters James K. , Emerich David W.
Published: January 2020

Ion-exclusion high-pressure liquid chromatography (HPLC) was used to measure poly-β-hydroxybutyrate (PHB) in
Rhizobium japonicum
bacteroids. The products in the acid digest of PHB-containing material were fractionated by HPLC on Aminex HPX-87H ion-exclusion resin for organic acid analysis. Crotonic acid formed from PHB during acid digestion was detected by its intense absorbance at 210 nm. The Aminex-HPLC method provides a rapid and simple chromatographic technique for routine analysis of organic acids. Results of PHB analysis by Aminex-HPLC were confirmed by gas chromatography and spectrophotometric analysis.
Chemotaxonomy of Gibberella zeae with special reference to production of trichothecenes and zearalenone
Authors: Ichinoe M , Kurata H , Sugiura Y , Ueno Y
Published: January 2020

By adopting a single-spore isolation technique, 113 isolates of Gibberella zeae, the perfect stage of Fusarium graminearum, were isolated from rice stubbles in barley and wheat fields and tested for production of trichothecenes and zearalenone on rice grains. Of the isolates, 93% produced the trichothecenes, and they could be subdivided into two chemotaxonomic groups: nivalenol and fusarenon-X producers and deoxynivalenol and 3-acetyldeoxynivalenol producers. No cross production of these two types of trichothecenes was observed in these isolates. Zearalenone was detected in 68% of the isolates, but no clear relationship could be observed regarding its position with respect to the two chemotaxonomic groups.
Toxicity of the Alternaria metabolites alternariol, alternariol methyl ether, altenuene, and tenuazonic acid in the chicken embryo assay
Authors: Griffin G F , Chu F S
Published: January 2020

The effects in the chicken embryo assay of four Alternaria metabolites (alternariol [AOH], alternariol methyl ether [AME], altenuene [ALT], and tenuazonic acid [TA]) were investigated. Administered to 7-day-old chicken embryos by yolk sac injection, AOH, AME, and ALT caused no mortality or teratogenic effect at doses up to 1,000, 500, and 1,000 micrograms per egg, respectively. TA exhibited a calculated 50% lethal dose of 548 micrograms per egg, with no teratogenic effect observed at either lethal or sublethal doses.
Sucker-like structures on the pathogenic amoeba Naegleria fowleri
Authors: John D T , Cole T B , Marciano-Cabral F M
Published: January 2020

Using scanning electron microscopy, we observed sucker-like structures on amoebae of 13 human isolates of Naegleria fowleri. The number of suckers per amoeba seemed to vary according to the virulence of the strain. We propose the term amoebastome to describe this unique sucker-like structure of N. fowleri.
Fate of Bacillus sphaericus 1593 and 2362 spores used as larvicides in the aquatic environment
Authors: Davidson E W , Urbina M , Payne J , Mulla M S , Darwazeh H , Dulmage H T , Correa J A
Published: January 2020

Dry powders produced from insecticidal Bacillus sphaericus strains 1593 and 2362 were applied against Culex tarsalis and Anopheles franciscanus mosquito larvae in small-plot field trials. Good control of C. tarsalis, but not of A. franciscanus, was produced at 0.1 and 0.2 lb/acre [ca. 0.122 and 0.244 kg/ha]. B. sphaericus spores settled rapidly from upper water layers and accumulated in bottom muds. Control of third/fourth-instar C. tarsalis larvae was maintained through day 4 after testing and was related to the presence of at least 100 spores per ml in the upper water layer 2 days earlier. B. sphaericus was shown to recycle in dead larvae both in the laboratory and in the field, producing an increase of 100- to 1,000-fold in spore numbers. There was no evidence of recycling in treated water nor of significant spore persistence upon reflooding of ponds after a very hot, dry period.
In vitro formation of 3'-hydroxy T-2 and 3'-hydroxy HT-2 toxins from T-2 toxin by liver homogenates from mice and monkeys
Authors: Yoshizawa T , Sakamoto T , Okamoto K
Published: January 2020

In vitro metabolism of T-2 toxin was studied in homogenates of mouse and monkey livers. In addition to several hydrolyzed products, including HT-2 toxin, neosolaniol, 4-deacetylneosolaniol, 15-deacetylneosolaniol, and T-2 tetraol, two metabolic products were isolated from the incubation mixture. Their structures were confirmed as 3'-hydroxy T-2 toxin and 3'-hydroxy HT-2 toxin on the basis of mass and nuclear magnetic resonance spectroscopy. The formation of these hydroxylated metabolites was found in the microsomes in the presence of NADPH, and the hydroxylation reaction was enhanced by treating mice with phenobarbital. The results suggest that a cytochrome P-450 is catalyzing the hydroxylation at the C-3' position of T-2 and HT-2 toxins. An in vitro metabolic pathway of T-2 toxin in the hepatic homogenates containing the NADPH-generating system is proposed.
Hydrophobicity as an Adhesion Mechanism of Benthic Cyanobacteria
Authors: Fattom Ali , Shilo Moshe
Published: January 2020

The capacity of benthic cyanobacteria to adhere to solid substrates was examined in terms of their cell surface properties. By using a biphasic water-hydrocarbon test system, it was demonstrated that benthic cyanobacteria from divergent habitats were all hydrophobic, whereas all the planktonic cyanobacteria tested were hydrophilic. Divalent cations were found more efficient than monovalent cations in effecting the expression of hydrophobicity. Mechanical shearing of the cell surface, as well as chemical removal of the cell wall, demonstrated that the hydrophobicity was confined to the outer surface layers. The hydrophobic sites were distributed along the whole length of the cyanobacterial filament. Hydrophilic hormogonia of benthic cyanobacteria became hydrophobic within 48 h when grown in the light; chloramphenicol, 3(3,4-dichlorophenyl)1,1 dimethylurea, or incubation in the dark prevented this transition. Hydrophobicity of
Phormidium
filaments was masked in late stationary phase; this effect was removed by gentle washing.
Simultaneous occurrence of deoxynivalenol, zearalenone, and aflatoxin in 1982 scabby wheat from the midwestern United States
Authors: Hagler W M , Tyczkowska K , Hamilton P B
Published: January 2020

Thirty-three samples of wheat of the 1982 crop year from Kansas and Nebraska were analyzed for deoxynivalenol, T-2 toxin, zearalenone, and aflatoxin. Deoxynivalenol was identified in 31 of 33 samples, zearalenone was identified in 3 of 33 samples, and aflatoxin B1 was identified in 23 of 31 samples. One 1982 wheat sample from Illinois and one from Texas were also contaminated with deoxynivalenol at 1,200 and 600 ng/g, respectively. None of the samples contained detectable T-2 toxin. The mean concentration of deoxynivalenol was 1,782 +/- 262 ng/g, and the concentrations of aflatoxin B1 ranged from 0.8 to 17.0 ng/g, with a mean of 3.37 +/- 0.7. Zearalenone concentrations of the three positive samples were 35, 90, and 115 ng/g. However, density segregation of two other samples which tested negative yielded light fractions, comprising less than 2% of the samples, contaminated at 230 and 254 ng of zearalenone per g; calculated zearalenone concentrations for these two samples were below the limit of detection of the method. The high frequency of aflatoxin B1 and deoxynivalenol in wheat from the 1982 crop is unprecedented, as is the simultaneous contamination of some samples with deoxynivalenol, zearalenone, and aflatoxin B1.
Production of a Biosurfactant from
Torulopsis bombicola
Authors: Cooper D. G. , Paddock D. A.
Published: January 2020

Two types of carbon sources—carbohydrate and vegetable oil—are necessary to obtain large yields of biosurfactant from
Torulopsis bombicola
ATCC 22214. Most of the surfactant is produced in the late exponential phase of growth. It is possible to grow the yeast on a single carbon source and then add the other type of substrate, after the exponential growth phase, and cause a burst of surfactant production. This product is a mixture of glycolipids. The maximum yield is 70 g liter
−1
, or 35% of the weight of the substrate used. An economic comparison demonstrated that this biosurfactant could be produced significantly more cheaply than any of the previously reported microbial surfactants.
Self-transmissible plasmid in Zymomonas mobilis carrying antibiotic resistance
Authors: Walia S K , Carey V C , All B P , Ingram L O
Published: January 2020

The cryptic plasmid pRUT41 from Zymomonas mobilis was examined for its biological properties. This plasmid was found to be conjugally transferred from Z. mobilis CP4 to Escherichia coli BM21 and to carry genes for antibiotic resistance (gentamicin, kanamycin, and streptomycin). Covalently closed circular plasmid DNA was isolated from eight transconjugants of E. coli BM21. These plasmids were identical in mobility on agarose gels and exhibited the same restriction patterns as the native pRUT41 plasmid isolated from Z. mobilis. The plasmid location of the antibiotic resistance genes was further confirmed by transforming E. coli BM21 with isolated pRUT41 plasmid from strain CP4 and with plasmids from the transconjugants of BM21. Resistance to streptomycin, kanamycin, and gentamicin was tightly linked and transferred together in all cases.
Improved method for detection of glycosidases in bacterial colonies
Authors: Paoni N F , Arroyo R L
Published: January 2020

An assay has been developed to detect bacterial glycosidases in colonies grown on the surface of agar plates. Advantages of this technique over previously described methods include elimination of the need for replica plating, better visualization of chromagenic reaction products, and a simple permeabilization step to enable better penetration by chromagenic substrates.
Inclusion bodies in Plesiomonas shigelloides
Authors: Pastian M R , Bromel M C
Published: January 2020

Inclusion bodies were discovered in seven environmental isolates of Plesiomonas shigelloides and the P. shigelloides control (ATCC 14029). Differential staining indicated that the inclusion bodies may be composed of polyphosphates, and developmental stages of the bodies may occur. The inclusion bodies may be useful for rapid presumptive identification of this organism.
Quantitation of pH- and salt-tolerant subpopulations from Clostridium botulinum
Authors: Montville T J
Published: January 2020

Plating efficiencies of Clostridium botulinum 62A spores on media with variable pH (7.0 to 5.5) and salt (0, 1, 2, and 3%) levels revealed that only a very small subpopulation could give rise to colonies. The relative size of this subpopulation decreased by orders of magnitude with decreasing pH and increasing salt concentrations. Strong interactions of pH with salt were noted. For example, on a medium containing 2% salt at pH 5.5, colonies could be formed from only 1 in 100,000 spores. Proper monitoring of medium anaerobiosis was critical in obtaining reproducible results.
Metabolic and ultrastructural response to glucose of two eurytrophic bacteria isolated from seawater at different enriching concentrations
Authors: Baxter M , Sieburth J M
Published: January 2020

Two marine bacteria, an Acinetobacter sp. (strain GO1) and a vibrio sp. (strain G1), were isolated by extinction dilution and maintained in natural seawater supplemented with nitrogen, phosphorus, and glucose at 0.01 and 10 mg of glucose carbon per liter above ambient monosaccharide concentrations, respectively. After 3 days in unsupplemented natural seawater, growth in batch culture with glucose supplements was determined by changes in cell numbers and glucose concentration. The exponential growth of the Acinetobacter strain with added glucose was indistinguishable from that in natural seawater alone, whereas that of the Vibrio strain was more rapid in the presence of glucose supplements, suggesting that the Acinetobacter strain preferred the natural organic matter in seawater as a carbon source. The ultrastructure for both isolates was unaffected by glucose supplements during exponential growth, but there were marked changes in stationary-phase cells. The Vibrio strain formed polyphosphate at 10 mg of glucose carbon per liter, whereas poly-beta-hydroxybutyrate formation occurred at 100 mg and became excessive at 1,000 mg, disrupting the cells. In contrast, the Acinetobacter strain elongated at 100 and 1,000 mg of glucose carbon per liter but failed to show poly-beta-hydroxybutyrate formation. The diversity of responses shown here would not have been detected with a single concentration of substrate, often used in the literature to characterize both pure and natural populations of marine bacteria.
Adhesion of a Mycobacterium sp. to cellulose diacetate membranes used in reverse osmosis
Authors: Ridgway H F , Rigby M G , Argo D G
Published: January 2020

The kinetics of adhesion of a Mycobacterium sp. to cellulose diacetate reverse-osmosis membranes is described. This Mycobacterium sp. (strain BT2-4) was previously implicated in the initial stages of reverse-osmosis membrane biofouling at a wastewater reclamation facility. Adhesion of BT2-4 cells to the cellulose diacetate membrane surfaces occurred within 1 to 2 h at 30 degrees C and exhibited saturation-type kinetics which conformed closely to the Langmuir adsorption isotherm (Pearson r correlation coefficient = 0.977), a mathematical expression describing the partitioning of substances between a solution and solid-liquid interface. This suggests that the cellulose diacetate membrane surfaces may possess a finite number of available binding sites to which the mycobacteria can adhere. Treatment of the attached mycobacteria with different enzymes suggested that cell surface polypeptides, alpha-1, 4- or alpha-1,6-linked glucan polymers, and carboxyl ester bond-containing substances (possibly peptidoglycolipids) may be involved in mycobacterial adhesion. The possible implication of these findings for reverse-osmosis membrane biofouling are discussed.
Microbial Transformation of Esters of Chlorinated Carboxylic Acids
Authors: Paris D. F. , Wolfe N. L. , Steen W. C.
Published: January 2020

Two groups of compounds were selected for microbial transformation studies. In the first group were carboxylic acid esters having a fixed aromatic moiety and an increasing length of the alkyl component. Ethyl esters of chlorine-substituted carboxylic acids were in the second group. Microorganisms from environmental waters and a pure culture of
Pseudomonas putida
U were used. The bacterial populations were monitored by plate counts, and disappearance of the parent compound was followed by gas-liquid chromatography as a function of time. The products of microbial hydrolysis were the respective carboxylic acids. Octanol-water partition coefficients (
K
ow
) for the compounds were measured. These values spanned three orders of magnitude, whereas microbial transformation rate constants (
k

b

) varied only 50-fold. The microbial rate constants of the carboxylic acid esters with a fixed aromatic moiety increased with an increasing length of alkyl substituents. The regression coefficient for the linear relationships between log
k

b

and log
K
ow
was high for group 1 compounds, indicating that these parameters correlated well. The regression coefficient for the linear relationships for group 2 compounds, however, was low, indicating that these parameters correlated poorly.
Viable fungi in corn dust
Authors: Hill R A , Wilson D M , Burg W R , Shotwell O L
Published: January 2020

Numbers of viable fungal propagules in corn dusts in southern Georgia were estimated during various farm and grain elevator operations in 1979, 1980, and 1982. A six-stage Andersen sampler for viable microbial particles was used to sample the dusts with various agar media. The most abundant fungi in corn dusts were species of yeasts: Aspergillus, Penicillium, Cladosporium, Alternaria. Helminthosporium, and Fusarium. However, the relative abundance of these fungi differed between years. There was a greater incidence of the Aspergillus flavus group in the hot, dry year of 1980 compared with the cooler, wetter years of 1979 and 1982. Fungi in the corn dusts sampled numbered between 10(4) and 10(9) viable propagules per m3 of air. By contrast, outdoor air often contained fewer than 10(4) viable fungal propagules per m3. Most A. flavus propagules were deposited at stages three and four of the Andersen sampler, with correspond to the trachea, primary bronchi, and secondary bronchi in the human respiratory system. In an assessment of the air spores by exposing sterile petri dishes, more large-spored fungi, like Alternaria tenuis, and fewer small-spored fungi, such as A. flavus, were detected when compared with colony counts from petri dishes exposed to air in the Anderson sampler.
Mineral Soils as Carriers for
Rhizobium
Inoculants
Authors: Chao W.-L. , Alexander Martin
Published: January 2020

Mineral soil-based inoculants of
Rhizobium meliloti
and
Rhizobium phaseoli
survived better at 4°C than at higher temperatures, but ca. 15% of the cells were viable at 37°C after 27 days. Soil-based inoculants of
R. meliloti, R. phaseoli, Rhizobium japonicum
, and a cowpea
Rhizobium
sp. applied to seeds of their host legumes also survived better at low temperatures, but the percent survival of such inoculants was higher than peat-based inoculants at 35°C. Survival of
R. phaseoli, R. japonicum
, and cowpea rhizobia was not markedly improved when the cells were suspended in sugar solutions before drying them in soil. Nodulation was abundant on
Phaseolus vulgaris
derived from seeds that had been coated with a soil-based inoculant and stored for 165 days at 25°C. The increase in yield and nitrogen content of
Phaseolus angularis
grown in the greenhouse was the same with soil-and peat-based inoculants. We suggest that certain mineral soils can be useful and readily available carriers for legume inoculants containing desiccation-resistant
Rhizobium
strains.
Effects of Nitrapyrin [2-Chloro-6-(Trichloromethyl) Pyridine] on the Obligate Methanotroph
Methylosinus trichosporium
OB3b
Authors: Topp Edward , Knowles Roger
Published: January 2020

Nitrapyrin inhibited growth, CH
4
oxidation, and NH
4
+
oxidation, but not the oxidation of CH
3
OH, HCHO, or HCOONa, by
Methylosinus trichosporium
OB3b, suggesting that nitrapyrin acts against the methane monooxygenase enzyme system. The inhibition of CH
4
oxidation could be reversed by repeated washing of nitrapyrin-inhibited cells, indicating that its effect is bacteriostatic. The addition of Cu
2+
did not release the inhibition. Methane oxidation was also inhibited by 6-chloro-2-picoline. These data suggest that the mode of action of nitrapyrin on
M. trichosporium
is different from that on chemoautotrophic NH
4
+
oxidizers or methanogens.
Conidium Germination Rate in Wild and Domesticated Yellow-Green Aspergilli
Authors: Wicklow D. T.
Published: January 2020

Conidia of domesticated yellow-green aspergilli from strains of
Aspergillus oryzae
(Ahlburg) Cohn and
Aspergillus sojae
Sakaguchi and Yamada ex Murakami, used in the preparation of koji inoculum, germinate approximately 3 h sooner than conidia produced by related wild species,
Aspergillus flavus
Link ex Fr. and
Aspergillus parasiticus
Speare. There was no consistent relationship between average conidium size and estimated 50% germination time. Germination trials were conducted on Czapek agar at 28°C. A hypothesis is offered that, in the propagation of koji inoculum, selection has favored those individuals capable of rapid conidium germination and germ tube extension, attributes that enable them to gain the available substrate during intraspecific competition.
Penicillin acylase from the hybrid strains Escherichia coli 5K(pHM12): enzyme formation and hydrolysis of beta-lactam antibiotics with whole cells
Authors: Schömer U , Segner A , Wagner F
Published: January 2020

Penicillin acylase formation by the hybrid strain Escherichia coli 5K(pHM12) was studied under different culture conditions and reached 200 to 250 mumol of 6-aminopenicillanic acid per min per g of bacteria (wet weight) for penicillin G. The Km of whole-cell acylase was determined with 9 to 11 mM for penicillin G at a pH optimum of 7.8 at 45 degrees C. A competitive product inhibition for phenylacetic acid of Ki = 130 mM was found. 6-Aminopenicillanic acid acts as a noncompetitive inhibitor, with a Ki of 131. The temperature optimum of the reaction lies at 54 degrees C. Penicillin G inhibits the reaction at Ki(S) = 1,565 to 1,570 mM. Whole-cell acylase reacts on a wide spectrum of penicillins and cephalosporins, but those substrates with a delta-aminoadipyl rest are not hydrolized. beta-Lactamase activity of less than 1% relative to the acylase activity was found at reaction temperatures between 28 and 45 degrees C. After a comparison of different methods for the estimation of beta-lactamase activity, we found that high-pressure liquid chromatography is to be preferred. During batch fermentation of E. coli 5K(pHM12), problems of plasmid stability in the host strain arose which were overcome by the addition of 4 mg of tetracycline per liter to the medium as a selective marker.
Enteric virus and indicator bacteria levels in a water treatment system modified to reduce trihalomethane production
Authors: Stetler R E , Ward R L , Waltrip S C
Published: January 2020

A drinking-water treatment plant with high concentrations of trihalomethanes in its finished water and large numbers of viruses in its source water was located. This plant was used to study the effect of an alteration in the point of chlorination from the first to last step of water treatment on the biological and chemical qualities of its finished water. This alteration caused some reduction in trihalomethane production, but trihalomethane concentrations still exceeded the prescribed limit of 100 micrograms/liter. No viruses or bacterial indicators were ever isolated from the finished water of the modified plant. Total virus removal by the treatment steps before chlorination (coagulation, sedimentation, and sand filtration) averaged ca. 90%, whereas removal of bacterial indicators by these processes averaged between 88 and 98%. Recoveries of viruses and bacterial indicators in the source water were generally negatively correlated.
Determinants of the microbiological characteristics of South Australian swimming pools
Authors: Esterman A , Roder D M , Cameron A S , Robinson B S , Walters R P , Lake J A , Christy P E
Published: January 2020

A survey of 100 swimming pools has been conducted to assess the effectiveness of disinfection practices against various microorganisms and to check compliance with recommended chlorine levels and pH. Microbiological quality was assessed from densities of total coliforms, Escherichia coli, and Pseudomonas aeruginosa, total colony counts, and the presence or absence of amoebae, including the pathogen Naegleria fowleri. Although a free chlorine residual of 1.0 mg/liter and a pH range of 7.0 to 7.6 are recommended by local health authorities, 41 pools had a lower free chlorine residual and 37 had a pH outside this range. Multiple logistic regression analysis was used to test the association of field measurements with the microbiological data. The analysis demonstrated a strong positive association of free chlorine with bacteriological quality and the absence of Naegleria spp. No other field measurement was predictive in this regard, although the absence of all amoebae was associated with a relatively low water temperature and pH. Using a mathematical model derived from this analysis, it was estimated that 99% of pools would have acceptable bacteriological quality and 94% would be free of Naegleria spp. at a free chlorine residual of 1.0 mg/liter. However, at the mean water temperature (23 degrees C) and pH (7.5) seen in this study, other amoebae would still be detectable in 500-ml samples taken from 40% of pools at this chlorine level.
Competition for Sulfate and Ethanol Among
Desulfobacter, Desulfobulbus
, and
Desulfovibrio
Species Isolated from Intertidal Sediments
Authors: Laanbroek Hendrikus J. , Geerligs Harm J. , Sijtsma Lolke , Veldkamp Hans
Published: January 2020

Competition for sulfate and ethanol among
Desulfobacter, Desulfobulbus
, and
Desulfovibrio
species isolated from estuarine sediments was studied in energy-limited chemostats.
Desulfovibrio baculatus
was the most successful competitor for limiting amounts of sulfate and ethanol, followed by
Desulfobulbus propionicus.
The success of
Desulfovibrio baculatus
was dependent on the availability of sufficient iron. Of the three species studied,
Desulfobacter postgatei
was the least successful competitor for limiting amounts of sulfate. Although stimulating the growth of
Desulfobacter postgatei
, addition of Ca-saturated illite particles to culture media did not affect the outcome of competition for sulfate. Thus, under sulfate limitation acetate accumulated. This phenomenon was briefly discussed in relation to the flow of electrons during anaerobic mineralization in marine and estuarine sulfate-limited sediments.
Virus movement in soil during saturated and unsaturated flow
Authors: Lance J C , Gerba C P
Published: January 2020

Virus movement in soil during saturated and unsaturated flow was compared by adding poliovirus to sewage water and applying the water at different rates to a 250-cm-long soil column equipped with ceramic samplers at different depths. Movement of viruses during unsaturated flow of sewage through soil columns was much less than during saturated flow. Viruses did not move below the 40-cm level when sewage water was applied at less than the maximum infiltration rate; virus penetration in columns flooded with sewage was at least 160 cm. Therefore, virus movement in soils irrigated with sewage should be less than in flooded groundwater recharge basins or in saturated soil columns. Management of land treatment systems to provide unsaturated flow through the soil should minimize the depth of virus penetration. Differences in virus movement during saturated and unsaturated flow must be considered in the development of any model used to simulate virus movement in soils.
Differentiation of lactic streptococcal phages into phage species by DNA-DNA homology
Authors: Jarvis A W
Published: January 2020

Twenty-five lactic streptococcal bacteriophages were differentiated by DNA homology into four species. Complete correlation was found between DNA homology groups and morphological characteristics of the phages except that two phage types, which differed in only the presence or absence of a collar, were one species by DNA homology. These findings were supported by serological data and differences in DNA molecular weights of the proposed species. The complete lack of homology between these phage species indicates that they are unlikely to have a recent common phage ancestor and that one morphological type of phage has not been derived by mutation from a phage of another morphological type.
Transient Responses of Glucose-Limited Cultures of
Cytophaga johnsonae
to Nutrient Excess and Starvation
Authors: Höfle Manfred G.
Published: January 2020

Cells from glucose-limited chemostat cultures of
Cytophaga johnsonae
were subjected to a sudden relaxation of substrate limitation by injecting the cells into fresh batch cultures. Starvation experiments were carried out by injecting glucose-limited cells into batch cultures lacking glucose. Transient responses of biomass, glucose uptake and mineralization, ATP content, and viability on different agar media were monitored during these nutrient-shift experiments. Cells reacted differently depending on growth rate and time spent in the chemostat. Fast-growing cells showed an immediate adaptation to the new growth conditions, despite some initial overshoot reactions in ATP and uptake potential. In contrast, slowly growing cells and long-term-adapted cells showed extensive transient growth responses. Glucose uptake and mineralization potentials changed considerably during the transient growth phase before reaching new levels. During the starvation experiments, all cell types displayed a fast decrease in ATP, but the responses of the substrate uptake and mineralization potentials were strongly dependent upon the previous growth rate. Both potentials decreased rapidly in cells with high growth rates. On the other hand, cells with low growth rates maintained 80% of their uptake and mineralization potentials after 8 h of starvation. Thus, slowly growing cells are much better adapted for starvation than are fast-growing cells.
Inorganic phosphate accumulation and cadmium detoxification in Klebsiella aerogenes NCTC 418 growing in continuous culture
Authors: Aiking H , Stijnman A , van Garderen C , van Heerikhuizen H , van 't Riet J
Published: January 2020

Klebsiella aerogenes NCTC 418, growing in the presence of cadmium under glucose-, sulfate-, or phosphate-limited conditions in continuous culture, exhibits two different cadmium detoxifying mechanisms. In addition to sulfide formation, increased accumulation of Pi is demonstrated as a novel mechanism. Intracellular cadmium is always quantitatively counterbalanced by a concerted increase in both inorganic sulfide and Pi contents of the cells. This led to the conclusion that production of sulfide and accumulation of Pi are detoxification mechanisms present in K. aerogenes but that their relative importance is crucially dependent on the strain and the growth conditions employed.
Microbial metabolism of haloaromatics: isolation and properties of a chlorobenzene-degrading bacterium
Authors: Reineke W , Knackmuss H J
Published: January 2020

A chlorobenzene-degrading bacterium was isolated by continuous enrichment from a mixture of soil and sewage samples. This organism, strain WR1306, was grown in a chemostat on a mineral medium with chlorobenzene being supplied through the vapor phase with a critical Dc value at a dilution rate of 0.55 h-1. Maximum growth rates in batch culture were accomplished at substrate concentrations of less than or equal to 0.5 mM in the culture medium. During growth on chlorobenzene, stoichiometric amounts of chloride were released. Respiration data and enzyme activities in cell extracts as well as the isolation of 3-chlorocatechol from the culture fluid are consistent with the degradation of chlorobenzene via 3-chloro-cis-1,2-dihydroxycyclohexa-3,5-diene, 3-chlorocatechol, 2-chloro-cis,cis-muconate, trans-4-carboxymethylenebut-2-en-4-olide, maleylacetate, and 3-oxoadipate.
Microbial Aerosols: Estimated Contribution of Combine Harvesting to an Airshed
Authors: Lighthart Bruce
Published: January 2020

From plate counts of the airborne microorganisms in the downwind dust plume of operating grass-seed combines, the mean source concentrations were calculated to be 6.4 × 10
8
and 4.7 × 10
8
/m
3
, respectively, potentially accounting for at least 41.9% of the bacteria and 35.1% of the fungi in the airshed in the Willamette Valley, Oregon.
Use of bacteriophage P1 as a vector for Tn5 insertion mutagenesis
Authors: Quinto M , Bender R A
Published: January 2020

Infection of a strain lysogenic for bacteriophage P1 CM with P1::Tn5 followed by simultaneous selection for the chloroamphenicol resistance associated with the resident prophage and the kanamycin resistance associated with Tn5 results in a large number of independent Tn5 insertion mutations. This superinfection-selection protocol is a fast, easy, and safe way to isolate null mutations in enteric bacteria without generating unwanted cryptic mutations elsewhere in the genome.
Proliferation of Legionella pneumophila as an intracellular parasite of the ciliated protozoan Tetrahymena pyriformis
Authors: Fields B S , Shotts E B , Feeley J C , Gorman G W , Martin W T
Published: January 2020

In a series of experiments, we have determined that Legionella pneumophila will proliferate as an intracellular parasite of the ciliated holotrich Tetrahymena pyriformis in sterile tap water at 35 degrees C. After 7 days of incubation, serpentine chains of approximately 10(3) L. pneumophila cells were observed throughout the cytoplasm of the protozoan infected initially with 1 to 30 L. pneumophila cells. The overall L. pneumophila population increased from ca. 1.0 X 10(2) to ca. 5.0 X 10(4) cells per ml in the coculture within this time frame. The interactions between the protozoan and the bacterium appear to depend upon their concentrations as well as temperature of incubation. L. pneumophila did not multiply in sterile tap water alone, in suspensions of lysed T. pyriformis, or in cell-free filtrates of a T. pyriformis culture. In addition to establishing an ecological model, we found that addition of T. pyriformis to environmental specimens served as an enrichment method that improved isolation of legionella from the specimens.
Effect of Ionic Composition of Suspending Solution on Virus Adsorption by a Soil Column
Authors: Lance J. C. , Gerba C. P.
Published: January 2020

The effect of various electrolytes on the adsorption of poliovirus was measured in 250-cm-long soil columns with ceramic samplers at different depths. Viruses suspended in deionized water moved much farther through the soil than those suspended in tap water, whereas movement in sewage water was intermediate. The salt content of the tap water and sewage water promoted virus adsorption, but evidently the organic compounds in sewage retarded adsorption. When viruses were suspended in chloride solutions of K
+
, Na
+
, Ca
+
, and Mg
2+
, virus adsorption increased as the cation concentration and valence increased. The depth of virus penetration was related to the ionic strength of the solutions. Virus penetration data for NO
3
−
, SO
4
2−
, and H
2
PO
4
−
salts of K
+
, Na
+
, and Ca
2+
indicated that other anions were more effective than Cl
−
in promoting virus adsorption. Also, NH
4
+
was more effective than other cations in limiting the penetration depth of viruses. It seems that ions composed of radicals are more effective than ions composed of single atoms in promoting virus adsorption. Al
3+
was the most effective ion in limiting virus penetration, probably owing to flocculation of the viruses. Adding AlCl
3
concentrations to secondary sewage effluent to provide an Al
3+
concentration of 0.1 mM reduced the virus penetration depth to 40 cm. These studies show that the ionic composition of the suspending solutions must be considered in predicting virus penetration depths, and it may be practical to add low concentrations of a flocculating agent such as AlCl
3
to sewage water to limit virus movement through very porous soils.
Identification of
Frankia
Strains by Two-Dimensional Polyacrylamide Gel Electrophoresis
Authors: Benson David R. , Buchholz S. E. , Hanna D. G.
Published: January 2020

Fifteen
Frankia
strains from five different plant species were analyzed by two-dimensional polyacryl-amide gel electrophoresis to determine their relatedness by comparing the polypeptide patterns obtained. Three major subgroups (A, C, and D) were found in the
Alnus-Comptonia-Myrica
cross-inoculation group. An isolate from
Purshia tridentata
had a unique protein pattern and represents a distinct group of frankiae. Members of group A were isolated from root nodules of
Alnus incana
subsp.
rugosa
and
Alnus viridis
subsp.
crispa.
Group C organisms were from
A. incana
subsp.
rugosa
and
Comptonia peregrina
nodules, and group D organisms were from
A. incana
subsp.
rugosa, A. viridis
subsp.
cripsa
, and
Myrica pensylvanica
root nodules. Isolates from each gel group were obtained at several widely separated geographical locations. The results indicate that two-dimensional polyacrylamide gel electrophoresis is useful for identifying
Frankia
isolates.
Substrate Utilization by an Oxalate-Consuming
Spirillum
Species in Relation to Its Growth in Ozonated Water
Authors: van der Kooij D. , Hijnen W. A. M.
Published: January 2020

The nutritional versatility of a vibrio-shaped, oxalate-utilizing isolate, strain NOX, obtained from tap water supplied with low concentrations of formate, glyoxylate, and oxalate, was determined by growth experiments with low-molecular-weight carbon compounds at high (grams per liter) and very low (micrograms per liter) concentrations. The organism, which was identified as a
Spirillum
species, appeared to be specialized in the utilization of a number of carboxylic acids. Yields of 2.9 × 10
6
CFU/μg of oxalate C and 1.2 × 10
7
CFU/μg of acetate C were obtained from growth experiments in tap water supplied with various low amounts of either oxalate or acetate. A substrate saturation constant of 0.64 μM oxalate was calculated for strain NOX from the relationship between growth rate and concentration of added oxalate. Maximum colony counts of strain NOX grown in ozonated water (dosages of 2.0 to 3.2 mg of O
3
per liter) were 15 to 20 times larger than the maximum colony counts of strain NOX grown in water before ozonation. Based on the nutritional requirements of strain NOX, it was concluded that carboxylic acids were produced by ozonation. Oxalate concentrations were calculated from the maximum colony counts of strain NOX grown in samples of ozonated water in which a non-oxalate-utilizing strain of
Pseudomonas fluorescens
had already reached maximum growth. The oxalate concentrations obtained by this procedure ranged from 130 to 220 μg of C/liter.
Partial Purification and Characterization of a Thermostable Actinomycete β-Amylase
Authors: Obi S. K. C. , Odibo F. J. C.
Published: January 2020

A thermostable amylase, possibly a β-amylase from
Thermoactinomyces
sp. no. 2 isolated from soil, is reported. The enzyme was purified 36-fold by acetone precipitation, ion-exchange chromatography, and Sephadex G-200 gel filtration, and the molecular weight was estimated at 31,600. The enzyme was characterized by demonstration of optimum activity at 60°C and pH 7 and by retention of 70% activity at 70°C (30 min). It was stimulated by Mn
2+
and Fe
2+
but strongly inhibited by Hg
2+
. Maltose was the only detectable product of hydrolysis of starches and was quantitatively highest in plantain starch hydrolysate.
Degradation of Lignin by
Cyathus
Species
Authors: Abbott Thomas P. , Wicklow Donald T.
Published: January 2020

The ability of 12
Cyathus
species to degrade
14
C-labeled lignin in kenaf was studied. The sum of
14
C released into solution plus
14
C released into the gas phase over a 32-day fermentation period was used to determine average daily rates of lignin biodegradation.
Cyathus pallidus. C. africanus
, and
C. berkeleyanus
delignified kenaf most rapidly.
C. canna
showed the greatest preference for lignin degradation over other plant components, and its rate of lignin degradation was only slightly lower than the three most active species. The apparent ability of fungi to metabolize low-molecular-weight lignin breakdown products correlated well with their overall delignification rates.
C. stercoreus
metabolized degradation products of lignin from wheat straw better than those from kenaf lignin, based on the amount of low-molecular-weight products left in solution.