bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduction of Ferric Iron in Anaerobic, Marine Sediment and Interaction with Reduction of Nitrate and Sulfate
Authors: Sørensen Jan
Published: January 2020

Studies were carried out to elucidate the nature and importance of Fe
3+
reduction in anaerobic slurries of marine surface sediment. A constant accumulation of Fe
2+
took place immediately after the endogenous NO
3
−
was depleted. Pasteurized controls showed no activity of Fe
3+
reduction. Additions of 0.2 mM NO
3
−
and NO
2
−
to the active slurries arrested the Fe
3+
reduction, and the process was resumed only after a depletion of the added compounds. Extended, initial aeration of the sediment did not affect the capacity for reduction of NO
3
−
and Fe
3+
, but the treatments with NO
3
−
increased the capacity for Fe
3+
reduction. Addition of 20 mM MoO
4
2−
completely inhibited the SO
4
2−
reduction, but did not affect the reduction of Fe
3+
. The process of Fe
3+
reduction was most likely associated with the activity of facultative anaerobic, NO
3
−
-reducing bacteria. In surface sediment, the bulk of the Fe
3+
reduction may be microbial, and the process may be important for mineralization in situ if the availability of NO
3
−
is low.
Actinomycetes and Fungi in Surface Waters and in Potable Water
Authors: Niemi R. Maarit , Knuth Sisko , Lundström Kenneth
Published: January 2020

In Finnish lakes and rivers used as water supplies, mesophilic fungi and actinomycetes were common, whereas thermophilic fungi and actinomycetes were present only in low concentrations. Fungi and actinomycetes were more abundant in eutrophic and mesotrophic lakes than in oligotrophic lakes. River water contained more thermophilic actinomycetes and fungi and mesophilic actinomycetes than did lake water. Runoff from soil seemed to be an important factor contributing to the incidence of these microbes in water. Chemical coagulation removed actinomycetes and fungi efficiently, but sand filtration allowed their passage. Disinfection could not prevent actinomycetes and fungi from reaching the distribution system. During infiltration in the production of recharged groundwater, mesophilic actinomycetes could even multiply appreciably.
Microbiological quality of dry-milk mixes and milk substitute infant formulas
Authors: Schwab A H , Swartzentruber A , Wentz B A , Read R B
Published: January 2020

The microbiological quality of dry-milk mixes and milk substitute infant formulas at the retail level was determined by a national survey of 1,574 analytical units. The geometric mean values for aerobic plate counts of milk-containing and milk substitute infant formulas were 25 and 52/g, respectively. The mean value for Staphylococcus aureus and for coliform organisms was less than 3/g. Each unit had an Escherichia coli most-probable-number value of less than 3/g.
Isolation of acholeplasmas and a mycoplasma from vegetables
Authors: Somerson N L , Kocka J P , Rose D , Del Giudice R A
Published: January 2020

The isolation of Mollicutes from food has not been reported. To isolate Mollicutes in the presence of high levels of unwanted bacteria, we first incubated fresh vegetables in liquid culture media containing lysozyme, ampicillin, and thallous acetate. Culture fluids were than separated from the vegetable samples, subjected to one freeze-thaw cycle, and passed through a filter of 0.4-micron porosity. Filtered samples were cultured in SP4 medium and in a conventional medium containing horse serum. With this procedure 21 acholeplasma isolations representing three species were obtained from endive, broccoli, and kale. Of 35 food samples tested, 11 were positive for acholeplasmas; acholeplasmas isolated from 6 of these samples were recovered only in SP4 medium. In seven single vegetable samples, two or more Acholeplasma spp. were isolated. A. laidlawii was isolated from all three vegetables and A. axanthum was found in broccoli and kale. Four isolates were serologically identified as A. oculi. Mycoplasma verecundum was the only Mycoplasma species recovered. Several isolates could not be typed serologically, as they reacted with antisera to both A. morum and A. hippikon. these isolates may include new Acholeplasma spp.
UV light-induced survival response in a highly radiation-resistant isolate of the Moraxella-Acinetobacter group
Authors: Keller L C , Thompson T L , Maxcy R B
Published: January 2020

A highly radiation-resistant member of the Moraxella-Acinetobacter group, isolate 4, obtained from meat, was studied to determine the effect of preexposure to UV radiation on subsequent UV light resistance. Cultures that were preexposed to UV light and incubated for a short time in plate count both exhibited increased survival of a UV light challenge dose. This response was inhibited in the presence of chloramphenicol. Frequencies of mutation to streptomycin, trimethoprim, and sulfanilamide resistance remained the same after the induction of this survival response and were not altered by treatment with mutagens, with the exception of mutation to streptomycin resistance after gamma-irradiation or nitrosoguanidine or methyl methane sulfonate treatment. The results indicated that isolate 4 has a UV light-inducible UV light resistance mechanism which is not associated with increased mutagenesis. The characteristics of the radiation resistance response in this organism are similar to those of certain other common food contaminants. Therefore, considered as part of the total microflora of meat, isolate 4 and the other radiation-resistant Moraxella-Acinetobacter isolates should not pose unique problems in a proposed radappertization process.
Lignocellulolytic Enzymes Produced by
Volvariella volvacea
, the Edible Straw Mushroom
Authors: Chang S. C. , Steinkraus K. H.
Published: January 2020

Volvariella volvacea
, commonly known as the straw or paddy mushroom, had the following growth characteristics: minimum temperature, 25°C; optimal temperature, 37°C; maximal temperature, 40°C; pH optimum 6.0. Optimal pH for cellulase production was 5.5. The optimal initial pH for cellulase production and mycelial growth was found to be 6.0. The pH and temperature optima for cellulolytic activity were 5.0 and 50°C, respectively. Maximal cellulolytic activity was obtained within 5 days in shake-flask culture. The cellulases were found to be partly cell free and partly cell bound during growth on microcrystalline cellulose. The endoglucanase activity was primarily extracellular, and β-glucosidase activity was found exclusively extracellularly. Weak cellulase activity was detected when cells were grown on cellobiose and lactose.
V. volvacea
could not digest the lignin portion of newspaper in shake-flask cultivation. Phenol oxidase, an important enzyme in lignin biodegradation, also was lacking in the cell-free filtrate. However, the organism oxidized phenolic compounds when it was cultured on agar plates containing commercial lignin.
Modified micromethod of the Limulus amoebocyte lysate assay for endotoxin
Authors: Melvaer K L , Fystro D
Published: January 2020

A Limulus amoebocyte lysate microtechnique performed in petrolatum wells on a microscope slide is described. Injection of a dye solution in ethanol directly into the wells leads to an unambiguous interpretation of the results. Twelve samples can be tested on a single slide, and compact storing of the samples is possible.
Survival of Cowpea Rhizobia in Soil as Affected by Soil Temperature and Moisture
Authors: Boonkerd Nantakorn , Weaver R. W.
Published: January 2020

Successful inoculation of peanuts and cowpeas depends on the survival of rhizobia in soils which fluctuate between wide temperature and moisture extremes. Survival of two cowpea rhizobial strains (TAL309 and 3281) and two peanut rhizobial strains (T-1 and 201) was measured in two soils under three moisture conditions (air-dry, moist (−0.33 bar), and saturated soil) and at two temperatures (25 and 35°C) when soil was not sterilized and at 40°C when soil was sterilized. Populations of rhizobia were measured periodically for 45 days. The results in nonsterilized soil indicated that strain 201 survived relatively well under all environmental conditions. The 35°C temperature in conjunction with the air-dry or saturated soil was the most detrimental to survival. At this temperature, the numbers of strains T-1, TAL309, and 3281 decreased about 2 logs in dry soil and 2.5 logs in saturated soil during 45 days of incubation. In sterilized soil, the populations of all strains in moist soil increased during the first 2 weeks, but decreased rapidly when incubated under dry conditions. The populations did not decline under saturated soil conditions. From these results it appears that rhizobial strains to be used for inoculant production should be screened under simulated field conditions for enhanced survival before their selection for commercial inoculant production.
Adsorption of coliphages T1 and T7 to clay minerals
Authors: Schiffenbauer M , Stotzky G
Published: January 2020

Coliphages T1 and T7 of Escherichia coli were absorbed by kaolinite (K) and montmorillonite (M). Maximum adsorption of T7 (96%) to M was greater than that of T1 (84%), but the adsorption of both coliphages to K was the same (99%). Positively charged sites (i.e., anion exchange sites) on the clays appeared to be primarily responsible for the adsorption of T1 to K but only partially responsible for the adsorption of T1 to M; equilibrium adsorption isotherms of T1 to K and M did not show a correlation between adsorption and the cation exchange capacity of the clays, and the reduction in adsorption caused by sodium metaphosphate (a polyanion that interacts with positively charged sites on clay) was more pronounced with K than with M. The equilibrium adsorption isotherms of T7 to K and M suggested a correlation between adsorption and the cation exchange capacity of the clays. However, studies with sodium metaphosphate indicated that T7 also adsorbed to positively charged sites on the clays, especially on K. Adsorption of the coliphages to positively charged sites was greater with K than with M, probably because the ratio of positively charged sites to negatively charged sites was greater on K than on M.
Influence of environmental storage relative humidity on biological indicator resistance, viability, and moisture content
Authors: Reich R R , Morien L L
Published: January 2020

The effect of environmental storage relative humidity (RH) on the moisture content, viability, and moist heat and gaseous ethylene oxide (EO) resistance of biological indicators (BIs) was evaluated. No statistically significant difference was observed between the initial Bacillus stearothermophilus spore population and the spore population of BIs stored at 20 degrees C and 0, 20, 44, of 55% RH or under ambient, 4 degrees C, or -20 degrees C conditions after 12 months. A statistically significant decrease in moist heat resistance from initial starting levels was found for BIs stored at 20 degrees C and either 0 or 20% RH. There was a statistically significant decrease in the B. subtilis BI spore population, compared with initial levels, when the BIs were stored at 20 degrees C and 0% RH concomitant with a significant increase in their EO resistance. BI storage at 20 degrees C and 20 or 44% RH, or under ambient, 4 degrees C, or -20 degrees C conditions, had no significant effect on EO resistance. BIs stored at 20 degrees C and 66% RH demonstrated a significantly lower EO resistance compared with starting levels.
Expression of a proline-enriched protein in Escherichia coli
Authors: Kangas T T , Cooney C L , Gomez R F
Published: January 2020

The feasibility of expressing repeated synthetic codons in bacterial cells was demonstrated by showing that repeated codons for proline were expressed in Escherichia coli. Recombinant DNA technology was used to clone synthetic polydeoxyguanylate:polydeoxycytidylate into the PstI site of plasmid pBR322. Recombinant plasmid pGC139 was shown by means of HaeIII restriction digestion to contain approximately 41 cloned base pairs; the cloned sequence was expressed as a fusion to an ampicillinase protein. The resulting protein, enriched in proline, was expressed from plasmid pGC139 in E. coli maxicells. Extension of this technology could lead to improvement in the production of amino acids and to nutritional enrichment of single-cell protein.
Characteristics of Protease Production by
Cephalosporium
sp
Authors: Kimura Tetsu , Tsuchiya Katsumi
Published: January 2020

We investigated protease formation by
Cephalosporium
sp. strain KM388, which produced trypsin inhibitor in the same cultures, in medium containing polypeptone, meat extract, and glucose (natural medium) and in medium containing NaNO
3
, glucose, and yeast extract (semisynthetic medium). In natural medium, protease was secreted into the culture broth after cessation of growth caused by consumption of the polypeptone, the growth-limiting substrate. Enzyme formation in the stationary growth phase was due to de novo and so-called preferential synthesis, because cycloheximide immediately inhibited enzyme formation. In semisynthetic medium, protease was produced in parallel with mycelial growth, but production was repressed by the addition of polypeptone to the medium; protease production began after the added polypeptone was consumed. On the other hand, if glucose was eliminated from natural medium, the lag period of initiation of enzyme production was reduced until the late exponential phase. The addition of phosphate up to a concentration of 1.0% to natural medium also shortened the lag period and damped the pH change of the broth during cultivation.
Methods for Studying Aquatic Bacteriophage Ecology
Authors: Primrose Sandy B. , Seeley Nigel D. , Logan Kelvin B. , Nicolson John W.
Published: January 2020

Methods are described for enumerating the different kinds of bacteriophage present in virus concentrates prepared from 120 liters of water. Although developed specifically for use with coliphages, they should be applicable to viruses infecting other hosts. These methods involve mixed indicators, equilibrium buoyant-density centrifugation, use of enzymes or inhibitors or both, and specific hybridization probes, either alone or in combination. With these methods, it was possible to specifically enumerate filamentous and isometric male-specific (F-specific) phages, the different classes of P-group plasmid-specific phages, φX174-like phages, and λ-like phages. Some applications of these methods, including measurement of virus inactivation in the environment and the extent of fecal pollution, are discussed.
Clostridium acetobutylicum
Protoplast Formation and Regeneration
Authors: Allcock Errol R. , Reid Sharon J. , Jones David T. , Woods David R.
Published: January 2020

Techniques and media for the production and regeneration of stable
Clostridium acetobutylicum
protoplasts are described.
Evaluation of cell lines and immunofluorescence and plaque assay procedures for quantifying reoviruses in sewage
Authors: Ridinger D N , Spendlove R S , Barnett B B , George D B , Roth J C
Published: January 2020

Twelve continuous cell lines were tested to determine their sensitivity to reovirus types 1, 2, and 3 isolated from sewage. Madin-Darby bovine kidney (MDBK), rhesus monkey kidney (LLC-MK2), and human embryonic intestinal (intestinal 407) cells were most sensitive, respectively. In a similar study, MDBK cells were more sensitive than LLC-MK2 and Buffalo green monkey kidney (BGM) cells to sewage-isolated, protamine-precipitated reoviruses which had not been serotyped and had no previous cell contact. Sewage-isolated, protamine-precipitated reoviruses were also used in conjunction with MDBK cells in a comparative evaluation of immunofluorescent cell count and plaque assay procedures. The immunofluorescence assay is more sensitive and more rapid than the plaque assay. Reoviruses in excess of 10(4)/liter of raw sewage were detected by the immunofluorescent cell count assay.
Effect of Sodium Chloride on Bakers' Yeast Growing in Gelatin
Authors: Wei Chia-Jenn , Tanner Robert D. , Malaney George W.
Published: January 2020

In recent years, industrial fermentation researchers have shifted their attention from liquid to solid and semisolid culture conditions. We converted liquid cultures to the semisolid mode by adding high levels of gelatin. Previous studies on liquid cultures have revealed the inhibitory activity of mineral salts, such as NaCl, on the fermentation of sugars by yeasts. We made a kinetic study of the effects of 1 to 5% (wt/vol) NaCl on the alcoholic fermentations of glucose by
Saccharomyces cerevisiae
in a growth medium containing 16% gelatin. Our results showed that the effect of high salt content on semisolid culture is essentially the same as the effect on liquid culture; i.e., as the salt content increased, the following occurred: (i) the growth of yeasts decreased, (ii) the lag period of the yeast biomass curve lengthened, (iii) the sugar intake was lowered, (iv) the yield of ethanol was reduced, and (v) the production of glycerol was increased. We observed a new relationship correlating the area of kinetic hysteresis with ethanol production rate, acetaldehyde concentration, and the initial NaCl concentration.
Legume-
Rhizobium
Interactions: Cowpea Root Exudate Elicits Faster Nodulation Response by
Rhizobium
Species
Authors: Bhagwat Arvind A. , Thomas Joseph
Published: January 2020

Preinfection events in legume-
Rhizobium
symbiosis were analyzed by studying the different nodulation behaviors of two rhizobial strains in cowpeas
(Vigna sinensis).
Log-phase cultures of
Rhizobium
sp. strain 1001, an isolate from the plant nodule, initiated host responses leading to infection within 2 h after inoculation, whereas log-phase cultures of
Rhizobium
sp. strain 32H1 took at least 7 h to trigger a discernible response. The delay observed with strain 32H1 could be eliminated by incubating the rhizobial suspension, before inoculation, for 4.5 h either in the cowpea rhizosphere/rhizoplane condition or in the root exudate of cowpea plants, grown without NH
4
+
in the rooting medium. The delay could not be eliminated by incubating the rhizobial suspension in the rooting medium of plants grown in the presence of 5 mM NH
4
+
, indicating that there is a regulatory role of combined nitrogen in triggering preinfection events by the legume. The substance(s) in the root exudate which elicited the faster nodulation response by
Rhizobium
sp. strain 32H1 could be separated into a high-molecular-weight fraction by Sephadex G-100 gel filtration. The data support the notion that legume roots release substances that favor the development of rhizobial features essential for infection and nodulation.
Respiration of Tritiated Substrates in Heterotrophic Activity Assays
Authors: Kuparinen Jorma , Tamminen Timo
Published: January 2020

The respiration percentage of
3
H-labeled glucose by heterotrophic microorganisms in water samples was determined by a method based on equimolar addition of [
3
H]- and [
14
C]glucose to samples. The respiration percentage of [
3
H]glucose exceeded that of [
14
C]glucose by 10% over the assayed range of respiration rates. Respiration percentages diminished with decreasing temperature, the relation between respiration of [
3
H]- and [
14
C]glucose remaining the same. The significance of tritiated water respiration with regard to experimental design is emphasized.
Membrane filter technique for the isolation of Yersinia enterocolitica
Authors: Bartley T D , Quan T J , Collins M T , Morrison S M
Published: January 2020

A membrane filter procedure was developed for the isolation of Yersinia enterocolitica from aquatic environments. Primary differentiation was based on the fermentation of sorbitol, the absence of lysine decarboxylase and arginine decarboxylase-dihydrolase activities, and the production of urease. Sodium deoxycholate was incorporated as an inhibitor of background organisms. The presumptive identification of Y. enterocolitica was accomplished in 50 h, and the rate of identity confirmation of typical colonies was 88%. The mean recovery rate of 15 strains from phosphate buffer suspensions was 91%, and quantitative recovery was demonstrated for low populations of the organism in both laboratory-prepared and naturally occurring mixed cultures. The technique was used to isolate 33 strains of Y. enterocolitica from 15 of 27 river water samples and from prechlorinated sewage effluent. Nine (27%) of the isolates were rhamnose positive, and only five (15%) were serotypable. Two isolates were identified as serotype O:4 (or O:4,32), two were O:17, and the fifth was O:40.
Bostrycin and 4-deoxybostrycin: two nonspecific phytotoxins produced by Alternaria eichhorniae
Authors: Charudattan R , Rao K V
Published: January 2020

Two crystalline red pigments with phytotoxic activity were isolated from culture filtrates of Alternaria eichhorniae, a pathogen of the water hyacinth Eichhornia crassipes. The pigments were present in the ratio of 4:1 and were identified as bostrycin and 4-deoxybostrycin, respectively. This is the first isolation of 4-deoxybostrycin from a natural source. Bostrycin, 4-deoxybostrycin, and their isopropylidene derivatives induced necrosis on tested plant leaves comparable to the A. eichhorniae-induced necrosis on water hyacinth. The lowest phytotoxic concentrations of crystalline bostrycin and 4-deoxybostrycin on water hyacinth leaves were about 7 and 30 microgram/ml, respectively. Both substances were inhibitory to Bacillus subtilis but were inactive against the fungus Geotrichum candidum.
Induction of cytopathogenicity in mammalian cell lines challenged with culturable enteric viruses and its enhancement by 5-iododeoxyuridine
Authors: Benton W H , Ward R L
Published: January 2020

Cultures of 17 established cell lines were tested against 105 enteric virus types for capacity to support viral replication as indicated by cytopathogenic effect production. Enhancement of susceptibility by treatment of the cells with 5-iododeoxyuridine was evaluated in parallel with untreated cells. Cytopathogenic effect was produced in two or more cell lines by every virus tested except six strains of group A coxsackie virus. No cell line was found to be susceptible to these six virus types. In general, treatment with 5-iododeoxyuridine provided a more rapid onset of cytopathogenic effect in susceptible cells and in some instances resulted in refractory cells becoming permissive to viral replication. The use of 5-iododeoxyuridine allowed two human embryonic lines (HEL-299 and L-132), in combination, to be susceptible to all but the six group A coxsackie virus strains.
Enzyme-linked immunosorbent assays for detection and quantitation of the entomocidal parasporal crystalline protein of Bacillus thuringiensis subspp. kurstaki and israelensis
Authors: Wie S I , Andrews R E , Hammock B D , Faust R M , Bulla L A
Published: January 2020

An enzyme-linked immunosorbent assay was used to detect and quantitate the parasporal crystal toxins of Bacillus thuringiensis subspp. kurstaki and israelensis. The assay method described is extremely sensitive, accurate, and highly specific. With this technique, crystalline insecticidal proteins from several subspecies of B. thuringiensis were compared. The dipteran crystal toxin produced by B. thuringiensis subsp. israelensis was shown to share few epitopes with the lepidopteran toxin from B. thuringiensis subspp. kurstaki, tolworthi, berliner, and alesti.
Effects of Clostridium botulinum toxins on infant and adult mice
Authors: Wisdom C , Midura T F
Published: January 2020

Toxic supernatants of many Clostridium botulinum type B isolates from various sources, especially those of isolates obtained from cases of infant botulism, appeared to more toxic in infant mice than in adult mice. The significance of this finding in diagnostic situations is discussed.
Integrated process for ammonia inactivation of aflatoxin-contaminated corn and ethanol fermentation
Authors: Bothast R J , Nofsinger G W , Lagoda A A , Black L T
Published: January 2020

A process is described for converting aflatoxin-contaminated corn to ethanol via combining ammonia inactivation with the liquefaction step of the ethanol fermentation process. Better ethanol yields were obtained when ammonia was added during liquefaction than when no ammonia was added. Aflatoxin B1 levels were reduced 80 to 85% by the process.
Restriction endonuclease analysis of the lactose plasmid in Streptococcus lactis ML3 and two recombinant lactose plasmids
Authors: Walsh P M , McKay L L
Published: January 2020

We investigated the molecular relationship between the 60-megadalton (Mdal) recombinant lactose plasmids in ML 3 x LM2301 lactose-positive (Lac+) transconjugants and the genetic material of Streptococcus lactis ML3. Lactose metabolism is linked to the 33-Mdal plasmid pSK08 in ML3, and the recipient LM2301 is cured of plasmid DNA. The plasmids were analyzed with a series of restriction enzymes. We found that the 60-Mdal plasmids of Lac+ transconjugants contained pSK08 DNA, but were not simply dimers of pSK08. The 60-Mdal plasmids contained a segment of DNA not apparent in pSK08. The restriction patterns of the 60-Mdal plasmid in a Lac+ nonclumping transconjugant and that in a Lac+ clumping transconjugant were different. This suggested that there was a molecular differences between these two recombinant plasmids. We conclude that the segment of DNA in the 60-Mdal plasmids that was not present in pSK08 was the proposed transfer factor responsible for cell aggregation and high-frequency conjugation.
Strain-Specific Synthesis of Mycophenolic Acid by
Penicillium roqueforti
in Blue-Veined Cheese
Authors: Engel Günter , von Milczewski Karl Ernst , Prokopek Dieter , Teuber Michael
Published: January 2020

Twenty of 80 strains of
Penicillium roqueforti
were able to produce up to 600 mg of mycophenolic acid (MPA) liter
−1
in 2% yeast extract-5% sucrose broth. Sixty-two of these strains had been isolated from the main blue-veined cheese varieties of western Europe or from starter cultures. Of these 62 dairy strains, only 7 had MPA-producing potential in vitro. These seven strains had all been isolated during the period 1975 to 1981 from the blue cheese of one individual factory. In cheese from the market, MPA (up to 5 mg kg
−1
) was only found in samples of this same factory. With MPA-producing and -nonproducing strains for the experimental manufacture of blue cheese, MPA synthesis in cheese was only detected with strains which form MPA in yeast extract-sucrose broth. The maximum MPA level at 4 mg kg
−1
was similar to that in commercial cheese. Toxicity of MPA was tested with two established human cell lines (Detroit 98 and Girardi Heart) and one established pig kidney cell line (AmII).
Effect of Sulfide on Nitrogen Fixation in a Stream Sediment-Water System
Authors: Tam Tat-Yee , Mayfield Colin I. , Inniss William E. , Knowles Roger
Published: January 2020

Nitrogen fixation (C
2
H
2
reduction) in a sediment-water system was studied under anaerobic incubation conditions. Sodium sulfide at low concentrations stimulated activity, with a twofold increase in C
2
H
4
production occurring in the presence of 8 μmol of S
2−
per ml of stream water. Sodium sulfide at concentrations of 16 μmol of S
2−
per ml or greater inhibited nitrogen fixation, with 64 μmol of S
2−
per ml being completely inhibitory. Sulfide at levels of 16 μmol/ml or above inhibited CO
2
production, and the degree of inhibition increased with increasing concentration of sulfide. Titanium (III) citrate (used to modify Eh levels) stimulated both nitrogen fixation and CO
2
production, but could not duplicate, at any concentration tested, the twofold increase in nitrogen fixation caused by 8 μmol of S
2−
per ml. Sulfide additions caused pH changes in the sediment, and when the sediment was adjusted and maintained at pH 7.0 all concentrations of sulfide inhibited nitrogen fixation activity. From considerations of the redox equilibria of H
2
, H
2
S, and other sulfur species at various pH values, it appeared that H
2
S was the toxic entity and that HS
−
was less toxic. The observed stimulation of activity was apparently due to a pH change coupled with the concurrent production of HS
−
from H
2
S.
Influence of salinity and organic nutrient concentration on survival and growth of Vibrio cholerae in aquatic microcosms
Authors: Singleton F L , Attwell R W , Jangi M S , Colwell R R
Published: January 2020

Laboratory microcosms were employed to evaluate the influence of selected environmental parameters, organic nutrient concentration, and salinity on the growth and survival of a toxigenic strain of Vibrio cholerae LA4808. Over the range conditions tested, this strain of V. cholerae showed maximum response as determined by increased plate counts and direct microscopic counts in microcosms prepared with a chemically defined sea salts solution at a salinity of 25%, but with lower or higher salinity levels, the maximum population size declined. When added organic concentrations of less than 1,000 micrograms/liter were present, a marked salinity effect on the growth of V. cholerae was detected. However, at or above an organic nutrient concentration of 1,000 micrograms/liter, the need for an optimum salinity level was spared. From the results of this study, it is concluded that V. cholerae can grow under conditions of organic nutrient concentration and salinity typical of estuaries. Results obtained support the hypothesis that V. cholerae is an autochthonous member of the estuarine microbial community.
Estimations of Uronic Acids as Quantitative Measures of Extracellular and Cell Wall Polysaccharide Polymers from Environmental Samples
Authors: Fazio Steven A. , Uhlinger David J. , Parker Jeffrey H. , White David C.
Published: January 2020

The extracellular polysaccharide polymers can bind microbes to surfaces and can cause physical modification of the microenvironment. Since uronic acids appear to be the components of these extracellular films that are most concentrated in a location outside the cell membrane, a quantitative assay for uronic acids was developed. Polymers containing uronic acids are resistant to quantitative hydrolysis, and the uronic acids, once released, form lactones irreproducibly and are difficult to separate from the neutral sugars. These problems were obviated by the methylation of the uronic acids and their subsequent reduction with sodium borodeuteride to the corresponding alcohol while they were in the polymer and could not form lactones. This caused the polymers to lose the ability to adhere to their substrates, so they could be quantitatively recovered. The hydrolysis of the dideuterated sugars was reproducible and could be performed under conditions that were mild enough that other cellular and extracellular polymers were not affected. The resulting neutral sugars were readily derivatized and then were separated and assayed by glass capillary gas-liquid chromatography. The dideuterated portion of each pentose, hexose, or heptose, identified by combined capillary gas-liquid chromatography and mass spectrometry, accurately provided the proportion of each uronic acid in each carbohydrate of the polymer. Examples of the applications of this methodology include the composition of extracellular polymers in marine bacteria, invertebrate feeding tubes and fecal structures, and the microfouling films formed on titanium and aluminum surfaces exposed to seawater.
Comparison of methods for measurement of bacterial growth rates in mixed batch cultures
Authors: Christian R R , Hanson R B , Newell S Y
Published: January 2020

Eight methods of assessing growth rate constants of bacteria were compared in batch cultures of 3-micrometers-filtered estuarine water from the Skidaway River in Ga. Mixed assemblages of bacteria were grown under four nutrient regimes of added yeast extract ranging from 0 to 100 mg/liter. Linear and exponential growth rate constants were computed from changes in cell densities, biovolumes, and ATP concentrations. Exponential growth rate constants were obtained from the frequency of dividing cells and RNA synthesis as measured by [3H]adenine uptake. Rate constants obtained during lag, exponential, and stationary growth phases depended largely on the method used. Constants calculated from changes in cell densities, frequency of dividing cells, and adenine uptake correlated most closely with each other, whereas constants calculated from changes in ATP concentrations and biovolumes correlated best with each other. Estimates of in situ bacterial productivity and growth vary depending on the method used and the assumptions made regarding the growth state of bacteria.
Effect of Interfaces on Small, Starved Marine Bacteria
Authors: Kjelleberg Staffan , Humphrey Beverley A. , Marshall Kevin C.
Published: January 2020

The copiotrophic marine
Vibrio
sp. strain DW1, shown previously in batch culture to increase in numbers at the onset of starvation and then to form viable small cells with low endogenous respiration, appears to have a survival advantage at interfaces.
Vibrio
sp. strain DW1 behaved differently at interfaces compared with the aqueous phase under starvation conditions: (i) small cells were observed at an air-water interface without nutrients, (ii) nutrients added to the air-water interface quickly produced larger cells at the surface, (iii) motility persisted many hours longer at the solid-water interface of a dialysis membrane in a microchamber at the onset of starvation, and (iv) regrowth and division at the solid-liquid interface occurred quickly and at nutrient concentrations too low to permit growth in the aqueous phase. It was concluded that, if small starved cells from copiotrophic bacteria can reach an interface, additional survival mechanisms become available to them: (i) interfaces constitute areas of favorable nutrient conditions, and (ii) interfaces lacking a sufficient amount of nutrient, nevertheless, trigger cells to become smaller, thus increasing their surface/volume ratio and the packing density.
Anaerobic bacterial populations on normal and diseased human biopsy tissue obtained at colonoscopy
Authors: Edmiston C E , Avant G R , Wilson F A
Published: January 2020

Human epithelium was cultured to characterize differences in microbial populations between regions of normal colon and between polyps, inflammatory bowel disease, and cancer and their respective adjacent normal mucosa. Twenty-one patients (12 polyps, 5 inflammatory bowel disease, 4 cancer) underwent colonoscopy with anaerobic culture of mucosal biopsies from normal and diseased ascending, transverse, descending, and sigmoid colon. No differences for total number of organisms and recovery of species between ascending colon and other normal regions were seen except for sigmoid colon. Significant differences between polyps and adjacent normal tissue were seen for total number of organisms and recovery of genera and species. No significant differences in total number of organisms and recovery of genera were seen between cancer and inflammatory bowel disease and their respective adjacent normal tissue. The recovery of genera from polyps and normal tissue was Bacteroides greater than Fusobacterium greater than Clostridium greater than Eubacterium greater than Peptostreptococcus. These data suggest that (i) the total number of anaerobic organisms and species remained relatively constant, except for lower numbers in normal distal colon which were probably a result of the preparation for colonoscopy; (ii) polyp formation favored increased microbial colonization; and (iii) the increased number of organisms generally reflected those genera and species seen on adjacent normal mucosa.
Pock Formation of
Streptomycetes endus
with Production of Phage Taillike Particles
Authors: Ogata Seiya , Suenaga Hikaru , Hayashida Shinsaku
Published: January 2020

Plate (or slope) cultures of endomycin-producing
Streptomyces endus
(KCC S-0213) showed spontaneously developing pocks which increased in number during subculturing. Neither spore formation nor typical aerial hyphae formation was observed in the pocks, whereas formation of substrate hyphase was not inhibited. Almost all of the hyphae were broken or lysed in the pocks, and many phage tail tiplike particles were observed in the pocks. No self-replication activity was associated with the particles. The particles often formed a hexagonal crystal or a large crystal mass. The production of these particles did not occur in the liquid culture or in young or normal plate cultures having no pocks. These results were similar to those obtained from the plaque-making phenomenon, except for active phage production, in thiostrepton-producing
Streptomyces azureus
(ATCC 14921), which has been described previously.
Effects of Acid on Plant Litter Decomposition in an Arctic Lake
Authors: McKinley Vicky L. , Vestal J. Robie
Published: January 2020

The effects of acid on the microbial decomposition of the dominant aquatic macrophyte (
Carex
sp.) in Toolik Lake, Alaska were studied in microcosms during the ice-free season of 1980. Toolik Lake is slightly buffered, deep, and very oligotrophic. Microbial activities, as determined by
14
C-acetate incorporation into extractable lipids, associated with
Carex
litter were significantly (
P
< 0.01) reduced within 2 days at pHs of 3.0 and 4.0, but not 5.0, 5.5, or 6.0, as compared with ambient controls (pH 7.4). ATP levels were significantly reduced at pH 3.0, but not at the other pHs tested. After 18 days, microbial activity significantly correlated with weight loss (
P
< 0.05), nitrogen content (
P
< 0.01), and C/N ratios (
P
< 0.01) of the litter, but did not correlate with ATP levels. Scanning electron microscopy of the litter surface revealed that the fungi present at ambient pH did not become dominant at pHs below 5.5, diatoms were absent below pH 4.0, and bacterial numbers and extracellular slime were greatly reduced at pH 4.0 and below. Mineralization of
Carex
14
C-lignin-labeled or
14
C-cellulose-labeled lignocellulose was reduced at pH 2.0, but not at pH 4.0, 5.0, or 6.0, compared with controls (pH 7). We concluded that if the pH of the water from this slightly buffered lake was sufficiently reduced, rates of litter decomposition would be significantly reduced.
Production of ochratoxin A in barley by Aspergillus ochraceus and Penicillium viridicatum: effect of fungal growth, time, temperature, and inoculum size
Authors: Häggblom P
Published: January 2020

Moistened barley was inoculated with 1.4 x 10(3) and 1.4 x 10(5) spores, respectively, from ochratoxin A-producing strains of Aspergillus ochraceus and Penicillium varidicatum. To estimate fungal tissue in the barley, the amount of glucosamine was followed for 28 days at 10 and 25 degrees C. Ochratoxin A was also followed during the same period and under the same conditions. The data show that ochratoxin A could be detected 4 to 6 days after inoculation at 25 degrees C, and the maximal accumulation of ochratoxin A was observed 28 days after inoculation. After 28 days at 25 degrees C, the quantities of ochratoxin A were between 7 and 46 micrograms/g of grain. At 10 degrees C only P. viridicatum produced ochratoxin A. The results indicated that production of ochratoxin A is not associated with rapid increase of glucosamine in the barley.
Contamination of red-meat carcasses by Campylobacter fetus subsp. jejuni
Authors: Gill C O , Harris L M
Published: January 2020

Campylobacter fetus subsp. jejuni was commonly present in the feces of unweaned calves (2 to 3 weeks old) and from two of four groups of sheep. One new season lamb (12 to 16 weeks old) carried the organism, but the bacteria were not isolated from cattle. With unweaned calves, the fractions of animals infected and carcasses contaminated were similar. Contamination of carcasses usually involved low densities of C. fetus subsp. jejuni (ca. 1 to 10/cm2), which were isolated from flank but not rump areas. The organism was recovered less frequently from chilled carcasses and deboned veal. Small numbers of C. fetus subsp. jejuni could be recovered from equipment during the processing of unweaned calves but not after routine cleaning.
Attached and Free-Floating Bacteria in a Diverse Selection of Water Bodies
Authors: Bell Colin R. , Albright Lawrence J.
Published: January 2020

The contribution of attached and free-floating bacteria to the bacterial numbers and heterotrophic uptake in 44 diverse aquatic environments was studied. A factor analysis reduced the variability of the raw data base to three major factors explaining 53.6% of total variance. These factors were (i) salinity, (ii) heterotrophic uptake, and (iii) particulate load. A cluster analysis categorized the 44 habitats into five distinct environmental types based on these three factors. There was no significant pattern in the distribution of attached versus free-floating bacteria when assessed by epifluorescent microscopy. However the contribution of attached bacteria to the uptake of an amino acids mix was reduced in marine waters. Heavy particulate loads resulted in an increased percentage uptake of amino acids and glucose from the attached bacteria. Uptake response was found to be substrate specific especially in oliogotrophic freshwater. Amino acid uptake was more associated with the attached fraction, whereas glucose uptake was mediated more by the free-floating fraction.
Metabolism of ochratoxin A by primary cultures of rat hepatocytes
Authors: Hansen C E , Dueland S , Drevon C A , St�rmer F C
Published: January 2020

Association of ochratoxin A with cultured rat hepatocytes occurs at 4 degrees C, and the saturation level in the medium is 0.3 mM ochratoxin A, with maximal binding after 60 min. At 37 degrees C the level of cell-associated ochratoxin A increased up to 6 h and remained at 2 nmol of toxin per mg of cell protein for 30 h. With increasing concentrations of ochratoxin A, increasing amounts of the toxin accumulated in the cells; saturation occurred at a concentration of 0.3 mM. Ochratoxin A was metabolized by hepatocytes at 37 degrees. (4R)-4-Hydroxyochratoxin A appeared in the medium at a maximal level (about 30 nmol/mg of cell protein) at an ochratoxin A concentration of 0.25 mM after 48 h of incubation. Small amounts of (4S)-4-hydroxyochratoxin A were detected only after incubation for 22 h or longer.
Sophorolipids from Torulopsis bombicola: possible relation to alkane uptake
Authors: Ito S , Inoue S
Published: January 2020

Torulopsis bombicola produces extracellular sophorolipids when it is grown on water-insoluble alkanes. Sophorolipids and related model compounds, which were not themselves used for growth, were found to stimulate markedly the growth of T. bombicola on alkanes. This stimulatory effect was restricted to growth on C10 to C20 alkanes, whereas no significantly influence was observed for growth on fatty alcohols, fatty acids, glucose, or glycerol. The nonionic methyl ester of the glycolipid supported the greatest cell yield. However, a number of synthetic nonionic surfactants were unable to replace the glycolipid. When organisms were grown on hexadecane, stimulation of growth by sophorolipids was observed almost exclusively with strains of Torulopsis yeasts. In contrast, the growth of other typical alkane-utilizing yeasts, such as candida and Pichia strains, was inhibited or not affected. It appears that sophorolipids are involved in alkane dissimilation by T. bombicola through an undetermined mechanism.
Development of high heat resistance of Arizona neotype by preincubation at 35 degrees C in media containing NaCl
Authors: Ng H
Published: January 2020

When cells of Arizona neotype were preincubated at 35 degrees C in a medium containing NaCl (1 to 10%), they were found to be much more heat resistant upon being tested at 57 degrees C in a Trypticase (BBL Microbiology Systems) soy-yeast extract broth medium containing 10% NaCl than cells that had not been preincubated. Although no growth takes place during preincubation in the presence of 10% NaCl, some metabolic activity is necessary, since the presence of 2,4-dinitrophenol during incubation reduced the amount of gain in heat resistance. Incubation in the presence of N2, instead of air, abolished the effect. Chloramphenicol and rifampin, however, had no effect. Preincubated cells were just as heat resistant when separated by centrifugation and suspended in a fresh medium as when suspended in the incubated supernatant liquid. Conversely, the incubated supernatant liquid did not confer increased heat resistance upon unincubated cells. The increase in heat resistance, therefore, is probably a result of the salt osmotically plasmolyzing the cells by removing intracellular water, thus rendering the cellular contents more stable to heat. It is not known, however, why metabolic activity is necessary.
Recovery of Campylobacter jejuni and Campylobacter coli from inoculated foods by selective enrichment
Authors: Doyle M P , Roman D J
Published: January 2020

A direct enrichment procedure was developed to selectively recover small numbers of Campylobacter jejuni, C. coli, and nalidixic acid-resistant thermophilic Campylobacter from foods. The procedure includes an enrichment medium composed of brucella broth, 7% lysed horse blood, 0.3% sodium succinate, 0.01% cysteine hydrochloride, vancomycin (15 micrograms/ml), trimethoprim (5 micrograms/ml), polymyxin B (20 IU/ml), and cycloheximide (50 micrograms/ml) that is inoculated with 10 or 25 g of food and incubated with agitation under microaerophilic conditions at 42 degrees C for 16 to 18 h. After incubation, the medium is plated directly onto Campy-BAP agar plates (M. J. Blaser et al., Ann. Intern. Med. 91:179-185, 1979), and resulting colonies that resemble Campylobacter are identified by conventional tests. The foods evaluated included raw milk, hamburger, and chicken skin which had aerobic plate counts of 10(5) to 10(9) bacteria/g. The procedure was effective in recovering as few as 0.1 cell of Campylobacter per g of food. Of the 50 isolates of Campylobacter evaluated, all were recovered from raw milk and hamburger at a level of 1 to 4 cells/g, and 41 and 40 isolaes were recovered from the hamburger and milk, respectively, at 0.1 to 0.4 cell/g. The enrichment was least effective for recovering campylobacters from chicken skin, as 7 and 26 of 50 isolates were not recovered at 1 to 4 and 0.1 to 0.4 cell/g, respectively. This new procedure is more rapid, direct, and effective than other enrichment or direct plating procedures for recovering small numbers of campylobacters from foods.
Comparison of methods for recovering indigenous viruses from raw wastewater sludge
Authors: Brashear D A , Ward R L
Published: January 2020

Five general methods for recovering indigenous viruses from raw wastewater sludge were compared. Each method included elution, concentration, and disinfection steps. The elution method, found to consistently yield the greatest viral recovery, was a two-phase technique that involved blending sludge with Freon. Other methods, including two being tested as American Society for Testing Materials tentative standard methods, were less effective. Viral recoveries were generally greater (sometimes much greater) if samples were concentrated by high-speed centrifugation rather than by organic flocculation with 3% beef extract. Three cell lines were used to measure viral recoveries by the plaque assay. The efficiency of recovery was greatest on BGM cells, followed by RD and MA-104 cells.
Growth of Sessile
Sphaerotilus natans
in a Tubular Recycle System
Authors: McCoy William F. , Costerton J. William
Published: January 2020

The growth of sessile
Sphaerotilus natans
was measured in a continuous-flow recycle system. Four methods were used to confirm that the growth of the biofilm was a linear function that increased with time. Of the methods used, one monitored in situ biofouling (increased fluid frictional resistance), two indicated biomass (ATP and DNA per square centimeter), and one allowed the direct observation of replaceable test surfaces by scanning electron microscopy. The filamentous growth of
S. natans
caused an increase in the fluid frictional resistance. The increase in biofouling was directly proportional to the increase in biomass.