bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitation of aflatoxin B1 and aflatoxin B1 antibody by an enzyme-linked immunosorbent microassay
Authors: Pestka J J , Gaur P K , Chu F S
Published: January 2020

A specific microtest plate enzyme immunoassay has been developed for the rapid quantitation of aflatoxin B1 at levels as low as 25 pg per assay. Multiple-site injection of rabbits with an aflatoxin B1 carboxymethyloxime-bovine serum albumin conjugate was used for the production of hyperimmune sera. Dilutions of the purified antibody were air dried onto microplates previously treated with bovine serum albumin and glutaraldehyde and then incubated with an aflatoxin B1 carboxymethyloxime-horseradish peroxidase conjugate. The amount of enzyme bound to antibody was determined by monitoring the change in absorbance at 414 nm after the addition of a substrate solution consisting of hydrogen peroxide and 2,2'-azino-di-3-ethyl-benzthiazoline-6-sulfonate. Antibody titers determined in this manner closely correlated with those determined by radioimmunoassay. Competition assays as performed by incubation of different aflatoxin analogs with the peroxidase conjugate showed that aflatoxins B1 and B2 and aflatoxicol caused the most inhibition of conjugate binding to antibody. Aflatoxins G1 and G2 inhibited the conjugate binding to a lesser degree, whereas aflatoxins M1 and B2a had no effect of the assay.
Effects of Heavy Metal Pollution on Oak Leaf Microorganisms
Authors: Bewley Richard J. F.
Published: January 2020

During the growing season, comparisons were made of the leaf surface microflora of (i) two groups of mature oak trees, one in the vicinity of a smelting complex contaminated by heavy metals and the other at a relatively uncontaminated site, and (ii) two groups of oak saplings at the uncontaminated site, one of which was sprayed with zinc, lead, and cadmium to simulate the heavy metal pollution from the smelter without the complicating effects of other pollutants. Total viable counts of bacteria, yeasts, and filamentous fungi (isolated by leaf washing) were generally little affected by the spraying treatment, whereas polluted leaves of mature trees supported fewer bacteria compared with leaves of mature trees at the uncontaminated site. Numbers of pigmented yeasts were lower on polluted oaks and on metal-dosed saplings compared with their respective controls. Polluted leaves of mature trees supported both greater numbers of
Aureobasidium pullulans
and
Cladosporium
spp. and a greater percentage of metal-tolerant fungi compared with oak leaves at the uncontaminated site. There were no significant overall differences in the degree of mycelial growth between the two groups of saplings or the mature trees.
Effects of environmental variables and soil characteristics on virus survival in soil
Authors: Hurst C J , Gerba C P , Cech I
Published: January 2020

Because of the increasing emphasis placed upon land application as a means of wastewater disposal, it is important to evaluate the influences of different factors upon virus survival in soil. The objective of this study was to measure the effects of various environmental variables on virus persistence. Test samples of soil were placed in vials, and the soil was wetted with suspensions of virus in either distilled water, unchlorinated secondary sewage effluent, or mixtures of effluent and water. The viruses used were coxsackieviruses A9 and B3, echovirus 1, poliovirus 2, rotavirus SA11, and bacteriophages T2 and MS2. The rate of virus inactivation was evaluated statistically with regard to conditions under which the vials were incubated and to the soil characteristics. The factors that were found to influence virus survival were temperature, soil moisture content, presence of aerobic microorganisms, degree of virus adsorption to the soil, soil levels of resin-extractable phosphorus, exchangeable aluminium, and soil pH. Overall, temperature and virus adsorption to soil appeared to be the most important factors affecting virus survival.
Single radial immunodiffusion method for screening Staphylococcal isolates for enterotoxin
Authors: Meyer R F , Palmieri M J
Published: January 2020

A direct system for screening large numbers of staphylococcal isolates for enterotoxin production has been developed. The system employs polyvalent (serotypes A, B, C, D, and E) immunodiffusion assay slides in conjunction with a multiple-culturing system for toxin production. With the combined system, as many as 50 cultures can be screened simultaneously on a single assay slide having a sensitivity of about 0.3 microgram/ml. The system should be useful for detecting potential enterotoxin in foods containing a predominance of non-enterotoxigenic strains.
Moniliformin and butenolide: effect on mice of high-level, long-term oral intake
Authors: Burmeister H R , Grove M D , Kwolek W F
Published: January 2020

Mice survived 21 days without apparent illness while consuming a daily amount of either moniliformin or butenolide near or exceeding their oral 50% lethal dose.
Behavior of pathogenic bacteria in the oyster, Crassostrea commercialis, during depuration, re-laying, and storage
Authors: Son N T , Fleet G H
Published: January 2020

Oysters (Crassostrea commercials) harvested from major cultivation areas within the state of New South Wales, Australia, were commonly contaminated with low levels of the food-poisoning organisms Bacillus cereus, Clostridium perfringens, and Vibrio parahaemolyticus. Salmonella was found in oysters on only one occasion. These bacteria were cleansed from oysters during oyster purification by re-laying in a non-polluted waterway. Oysters were laboratory contaminated to levels in excess 1,000 cells per g with either B. cereus, C. perfringens, V. parahaemolyticus, Salmonella typhimurium, or S. senftenberg. These species were cleansed from such oysters during purification in a laboratory depuration unit that used ultraviolet light for sterilizing the depuration water. Escherichia coli was also cleansed from oysters under the same re-laying or depuration conditions so that its measurement alone could be used to indicate the cleansing of the above pathogenic species. The levels of these bacteria were also measured during the storage of oysters under conditions that occur during marketing. While B. cereus counts remained relatively stable during storage, the Salmonella spp. gradually decreased in numbers and C. perfringens rapidly died off. V. parahaemolyticus counts increased slightly during the first 4 days of storage, after which decreases occurred.
Effects of pH and Sugar on Acetoin Production from Citrate by
Leuconostoc lactis
Authors: Cogan Timothy M. , O'Dowd Mary , Mellerick Dervla
Published: January 2020

The relationship between acetoin production and citrate utilization in
Leuconostoc lactis
NCW1 was studied. In a complex medium the organism utilized citrate at neutral pH (initial pH, 6.3) and at acid pH (initial pH, 4.5) but produced nine times more acetoin at the latter pH. In resting cells the utilization of citrate was optimum at pH 5.3. Production of acetoin as a function of citrate utilization increased as the pH decreased, and at pH 4.3 all of the citrate utilized was recovered as acetoin. Glucose (10 mM) and lactose (10 mM) markedly stimulated citrate utilization but totally inhibited acetoin production in glucose- and lactose-grown cells. Addition of glucose to cells actively metabolizing citrate caused an immediate increase in citrate uptake and a reduction in the level of acetoin. The apparent
K

m

values of lactic dehydrogenase for pyruvate were 1.05, 0.25, and 0.15 mM at pH 7.5, 6.5, and 5.0, respectively. Several heterofermentation intermediates inhibited α-acetolactate synthetase and decarboxylase activities. The implications of these results in regulating acetoin formatin are discussed.
Surface-Active Lipids from
Nocardia erythropolis
Grown on Hydrocarbons
Authors: Macdonald Colin R. , Cooper David G. , Zajic James E.
Published: January 2020

Nocardia erythropolis
(ATCC 4277) was grown in a 28-liter fermentor on mineral salts medium and 4% hydrocarbon. Extraction of the neutral lipids with pentane removed approximately 90% of the surface activity of the culture medium. The residual surface activity of the culture medium was attributed to the polar lipid fraction which was not extracted with pentane. Analysis of the pentane extracts with thin-layer chromatography showed the presence of four major compounds. A fatty alcohol reached a maximum concentration in the early log phase of growth and then decreased to the end of the fermentation. A monoglyceride, an ester, and a fatty acid appeared during the log phase of growth and continued to increase until the end of the fermentation. The fatty acids isolated from the culture grown on hexadecane had a carbon skeleton with the same length as the substrate, with 70% of the component as the saturated acid and 30% as a monounsaturated homolog. When isolated from a kerosene culture, the fatty acids consisted of a number of homologs from C
18
to C
20
, including branched-chain and unsaturated acids, reflecting the distribution of the branched-chain isomers in the substrate.
Influence of Nutritional Conditions on Production of
l
-Glutamine by
Flavobacterium rigense
Authors: Nabe Koichi , Ujimaru Toshihiko , Yamada Shigeki , Chibata Ichiro
Published: January 2020

The nutritional conditions for the production of
l
-glutamine by
Flavobacterium rigense
strain 703 were investigated. The optimum concentration of ammonia for achieving the highest yield of
l
-glutamine (25 mg/ml of broth) was relatively broad, from 0.9 to 1.6%, whereas fumaric acid had a narrow optimum range, near 5.5%. High concentration of inorganic ions such as chloride or sulfate ion clearly inhibited cell growth. Therefore, ammonium salts other than (NH
4
)
2
-fumarate were unsuitable for the highest production. The optimum concentration of (NH
4
)
2
-fumarate was 7%. To reduce the concentration of fumaric acid in the medium, many substances were evaluated as substitutes. The fumaric acid concentration required for highest
l
-glutamine yield could not be replaced by any one of the compounds tested. However, part of fumaric acid could be replaced with succinic acid and cupric ion; 4% (NH
4
)
2
-fumarate plus 2.5% succinic acid or 5% (NH
4
)
2
-fumarate plus 1 mM cupric ion produced results similar to 7% (NH
4
)
2
-fumarate in the fermentation medium.
Distribution of ribonucleic acid coliphages in animals
Authors: Osawa S , Furuse K , Watanabe I
Published: January 2020

To determine the distribution pattern of ribonucleic acid (RNA) coliphages (classified by serological groups I through IV) in animal sources, we isolated RNA phages from (i) feces samples from domestic animals (cows, pigs, horses, and fowls), some other animals in a zoological garden, and humans, (ii) the gastrointestinal contents of cows and pigs, and (iii) sewage samples from treatment plants in slaughter houses. These samples were then analyzed serologically. The concentration of RNA phages in the first and second kinds of material was fairly low (10 to 10(3) plaque-forming units per original phage sample), whereas that in the third kind of material was fairly high (10(3) to 10(5) plaque-forming units per original phage sample). Concerning the group types of the RNA phages in the first and second kinds of material, human feces contained RNA phages of groups II and III almost equally, the gastrointestinal contents of pigs included those of groups I and II equally, and the feces or gastrointestinal contents of other mammals other than humans and pigs had those of group I exclusively. In the third type of material we found mostly group I phages with a minor fraction of group II phages. Thus, the prominent features of the distribution pattern of RNA phages are the predominance of groups III and II in humans and the predominance of group I in animals.
Inhibition of Babesia spp. by plastics
Authors: Timms P
Published: January 2020

Five commercially available plastic containers were compared with glass for toxicity toward Babesia rodhaini and Babesia bigemina. Comparisons were made by using infectivity tests in mice (B. rodhaini) and cattle (B. bigemina). Low-density polypropylene and polystyrene containers were not toxic, but two of the three polyvinyl chloride containers tested significantly reduced the viability of both species of Babesia. Plasticizer present in various amounts on the surface of the toxic containers was most likely the inhibitory material.
Yeasts from Marine and Estuarine Waters with Different Levels of Pollution in the State of Rio de Janeiro, Brazil
Authors: Hagler Allen N. , Mendonça-Hagler Leda C.
Published: January 2020

Yeast counts were made at 24 marine and estuarine sites in the vicinity of Rio de Janeiro, Brazil. Mean salinities of estuarine sites ranged from 14.2 to 27.4‰, and mean temperatures ranged from 25 to 28°C. Total coliform counts varied from 80% above 100,000 colony-forming units (CFU)/100 ml at heavily polluted sites to 100% below 100 CFU/100 ml at unpolluted sites. Total yeast counts above 100 CFU/100 ml were typical of heavily and moderately polluted water but atypical of lightly polluted and unpolluted water. Mean total yeast counts were 2,880 CFU/100 ml for heavily polluted sites, 202 CFU/100 ml for moderately polluted sites, and 3 CFU/100 ml for lightly polluted and unpolluted sites. Total yeast counts had a positive response to increased pollution levels, and
Candida krusei
and phenotypically similar yeasts as a group were prevalent in polluted estuarine water but rare in unpolluted seawater. The 549 strains of yeasts and yeast-like organisms isolated were grouped into 67 species, of which the 21 most prevalent made up 86% of the total yeast population. The prevalent genera in the polluted estuary were
Candida, Rhodotorula, Torulopsis, Hanseniaspora, Debaryomyces
, and
Trichosporon
.
Microbial Cells as Biosorbents for Heavy Metals: Accumulation of Uranium by
Saccharomyces cerevisiae
and
Pseudomonas aeruginosa
Authors: Strandberg Gerald W. , Shumate Starling E. , Parrott John R.
Published: January 2020

Uranium accumulated extracellularly on the surfaces of
Saccharomyces cerevisiae
cells. The rate and extent of accumulation were subject to environmental parameters, such as pH, temperature, and interference by certain anions and cations. Uranium accumulation by
Pseudomonas aeruginosa
occurred intracellularly and was extremely rapid (<10 s), and no response to environmental parameters could be detected. Metabolism was not required for metal uptake by either organism. Cell-bound uranium reached a concentration of 10 to 15% of the dry cell weight, but only 32% of the
S. cerevisiae
cells and 44% of the
P. aeruginosa
cells within a given population possessed visible uranium deposits when examined by electron microscopy. Rates of uranium uptake by
S. cerevisiae
were increased by chemical pretreatment of the cells. Uranium could be removed chemically from
S. cerevisiae
cells, and the cells could then be reused as a biosorbent.
In Vitro Nitrogen Fixation by Two Actinomycete Strains Isolated from
Casuarina
Nodules
Authors: Gauthier D. , Diem H. G. , Dommergues Y.
Published: January 2020

Acetylene reduction activity was demonstrated in pure cultures of two actinomycete strains isolated from nodules of
Casuarina equisetifolia.
This activity was comparable to that of free-living
Rhizobium
strains, but appeared to be less sensitive to pO
2
and more sensitive to the presence of combined nitrogen.
Differential plating medium for quantitative detection of histamine-producing bacteria
Authors: Niven C F , Jeffrey M B , Corlett D A
Published: January 2020

A histidine-containing agar medium has been devised for quantitative detection of histamine-producing bacteria that are alleged to be associated with scombroid fish poisoning outbreaks. The responsible bacteria produce a marked pH change in the agar, with attendant color change of pH indicator adjacent to the colonies, thus facilitating their recognition. Proteus morganii and Klebsiella pneumoniae were the two most common histidine-decarboxylating species isolated from scombroid fish and mahi mahi.
Swine refusal factors elaborated by Fusarium strains and identified as trichothecenes
Authors: Vesonder R F , Ellis J J , Rohwedder W K
Published: January 2020

Fusarium poae (Peck) Wollenw. NRRL 3287, F. nivale (Fr.) Ces. NRRL 3289, and F. moniliforme Sheldon NRRL 3197, each grown on cracked corn (13 days at 28 degrees C), produced refusal factors in pig bioassays. Substantial quantities of trichothecenes were detected in the refused corn: T-2 toxin (30 micrograms/g) was detected in corn fermented with the F. poae strain; the level of vomitoxin (1 microgram/g) in corn cultured with F. nivale did not account for the 48% refusal response in the pigs tested. The F. moniliforme concomitantly produced T-2 toxin (33 micrograms/g) and vomitoxin (1.5 micrograms/g). This strain's taxonomic position was reexamined, and it is shown to be a cultural variant of the species F. tricinctum (Cda.) Sacc.
Bacteroides species: maintenance of laboratory strains
Authors: Baldwin W W , Tseng M , Landay M E
Published: January 2020

A medium composed of blood agar base (40 g/liter), yeast extract (5 g/liter), and cysteine hydrochloride (0.05 g/liter), completely filling screw-cap tubes (13 by 100 mm), can keep Bacteroides species alive for at least 10 months without refrigeration.
Bacteria associated with false-positive most-probable-number coliform test results for shellfish and estuaries
Authors: Hussong D , Damaré J M , Weiner R M , Colwell R R
Published: January 2020

Aerobic and facultatively anaerobic bacteria isolated from false-positive, presumptive, total coliform, most-probable-number tests of Chesapeake Bay oyster, water, and sediment samples were characterized and then classified by numerical taxonomy. A total of 538 bacterial strains clustered into 17 phena, the predominant groups of which were Enterobacteriaceae (including Escherichia coli), Aeromonas spp., and Bacillus spp. Bacillus spp. were recovered most frequently from sediment samples. Gas-producing strains which were not members of the Enterobacteriaceae were not isolated during this study. However, disproportionately large numbers of atypical and anaerogenic lactose-fermenting strains were encountered. We concluded that no single, specific bacterial group can be identified as being responsible for the false-positive reaction in the presumptive coliform test. Instead, the false-positive reaction is a result of complex interactions among various genera, representing predominantly bacteria other than coliforms.
Cadmium-binding component in Escherichia coli during accommodation to low levels of this ion
Authors: Khazaeli M B , Mitra R S
Published: January 2020

An inducible cadmium-binding protein was isolated from Escherichia coli cells accommodated to 3 X 10(-6) M Cd2+ but not from normal or unaccommodated cells. Sephadex G-100, metal chelate affinity chromatography, and disc gel electrophoresis were used in the purification procedure. The molecular weight of the Cd2+-binding protein was estimated to be about 39,000 by Sephadex G-100 chromatography, making it different from the conventional, much smaller metallothionein.
One-year survey of enteroviruses, adenoviruses, and reoviruses isolated from effluent at an activated-sludge purification plant
Authors: Irving L G , Smith F A
Published: January 2020

Samples of raw sewage, primary effluent, and secondary effluent from a large activated-sludge purification plant near Melbourne (Victoria, Australia) were collected every second week for 1 year. Viruses were detected in all secondary effluent samples and in six of seven samples obtained after final chlorination. Adenoviruses (85% reduction) and reoviruses (28% reduction) were removed less efficiently by this treatment process than were enteroviruses (93% reduction). In addition, 57 of 171 samples of effluent tested were positive for either adenoviruses or reoviruses, or both, when enteroviruses were not isolated. This clearly shows that the use of enteroviruses as sole indicators of viruses in water may miss up to one-third of instances of viral contamination. Enteroviruses and adenoviruses were isolated most frequently in HeLa-R cell cultures, whereas reoviruses were most often isolated in primary monkey kidney cells.
Ecological distribution of Legionella pneumophila
Authors: Fliermans C B , Cherry W B , Orrison L H , Smith S J , Tison D L , Pope D H
Published: January 2020

Bacteria were concentrated 500-fold from 20-liter water samples collected from 67 different lakes and rivers in the United States. The data suggest that Legionella pneumophila is part of the natural aquatic environment and that the bacterium is capable of surviving extreme ranges of environmental conditions. The data further demonstrate the effectiveness of the direct fluorescent-antibody technique for detecting L. pneumophila in natural aquatic systems. Smears of the concentrated samples were screened microscopically for serogroups of L. pneumophila by the direct fluorescent-antibody technique. Virtually all of the 793 samples were found to be positive by this method. The 318 samples containing the largest numbers of positive bacteria which were morphologically consistent with L. pneumophila were injected into guinea pigs for attempted isolations. Isolates were obtained from habitats with a wide range of physical, chemical, and biological parameters. Samples collected monthly from a thermally altered lake and injected into guinea pigs demonstrated a seasonality of infection, with the highest frequency of infection occurring during the summer months.
Nodulation of
Acacia
Species by Fast- and Slow-Growing Tropical Strains of
Rhizobium
Authors: Dreyfus B. L. , Dommergues Y. R.
Published: January 2020

Thirteen
Acacia
species were classified into three groups according to effective nodulation response patterns with fast- and slow-growing tropical strains of
Rhizobium.
The first group nodulated effectively with slow-growing, cowpea-type
Rhizobium
strains; the second, with fast-growing
Rhizobium
strains; and the third, with both fast- and slow-growing
Rhizobium
strains. The
Rhizobium
requirements of the
Acacia
species of the second group were similar to those of
Leucaena leucocephala.
Plant Yield and Nitrogen Content of a Digitgrass in Response to
Azospirillum
Inoculation
Authors: Schank S. C. , Weier K. L. , MacRae I. C.
Published: January 2020

Two Australian soils, a vertisol (pH 6.8, 0.299% N) and a sandy yellow podzol (pH 6.2, 0.042% N), were used with digitgrass,
Digitaria
sp. X46-2 (PI 421785), in a growth room experiment. Comparisons were made between plants inoculated with live and autoclaved bacterial suspensions of Australian and Brazilian isolates of
Azospirillum brasilense
. Seedlings were inoculated on days 10 and 35. Acetylene-reducing activity was measured five times during the experiment. Dry matter yields of the digitgrass on the podzol (low N) inoculated with live bacteria were 23% higher than those of the controls. On the vertisol (high N), yield increases from inoculation with live bacteria were 8.5%. The higher-yielding plants had significantly lower percent nitrogen, but when total nitrogen of the tops was calculated, the inoculated plants had a higher total N than did the controls (
P
=0.04). Acetylene-reducing activity was variable in the experiment, ranging from 0.5 to 11.9 μmol of C
2
H
4
core
−1
day
−1
. Live bacterial treatment induced a proliferation of roots, possible earlier maturity, higher percent dry matter, and a higher total N in the tops.
Heparinase production by Flavobacterium heparinum
Authors: Galliher P M , Cooney C L , Langer R , Linhardt R J
Published: January 2020

Heparinase production by Flavobacterium heparinum in complex protein digest medium, with heparin employed as the inducer, has been studied and improved. The maximum productivity of heparinase has been increased 156-fold over that achieved by previously published methods to 375 U/liter per h in the complex medium. Rapid deactivation of heparinase activity, both specific and total, was observed at the onset of the stationary phase. Nutritional studies on growth and heparinase production showed an obligate requirement for L-histidine and no vitamin requirement. L-Methionine partially relieved the L-histidine requirement. A defined medium containing glucose, ammonium sulfate, basal salts, L-methionine, and L-histidine was developed for growth and heparinase production. The growth rate in this medium was 0.21 h-1, which is 40%, higher than that in complex medium. The maximum volumetric productivity of heparinase in the defined medium was increased to 1,475 U/liter per h, providing a 640-fold increase over that achieved by previously published methods. No rapid deactivation was observed. An examination of alternate inducers for heparinase showed that heparin degradation products, hyaluronic acid, heparin monosulfate, N-acetyl-D-glucosamine, and maltose, induce heparinase in complex medium. An Azure A assay was modified and fully developed to measure the heparin concentration during fermentation and the heparinase specific activity of crude extracts of F. heparinum obtained from sonication, thus negating the need for further purification to measure activity."
Denitrification and Nitrogen Fixation in Alaskan Continental Shelf Sediments
Authors: Haines John R. , Atlas Ronald M. , Griffiths Robert P. , Morita Richard Y.
Published: January 2020

Rates of nitrogen fixation and denitrification were measured in Alaskan continental shelf sediments. In some regions, rates of nitrogen fixation and denitrification appeared to be equal; in other areas, rates were significantly different. Potential rates of denitrification were found to be limited primarily by the available nitrate substrate. Major regional differences in rates of denitrification were not statistically significant, but significant differences were found for nitrogen fixation rates in different regions of the Alaskan continental shelf. Estimated net losses of nitrogen from Bering Sea sediments were calculated as 1.8 × 10
12
g of N/yr. Experimental exposure of continental shelf sediments to petroleum hydrocarbons reduced rates of nitrogen fixation and denitrification in some cases but not others. Long-term exposure was necessary before a reduction in nitrogen fixation rates was observed; unamended rates of denitrification but not potential denitrification rates (NO
3
−
added) were depressed after exposure to hydrocarbons.
Survival of enteroviruses and coliform bacteria in a sludge lagoon
Authors: Farrah S R , Bitton G , Hoffmann E M , Lanni O , Pancorbo O C , Lutrick M C , Bertrand J E
Published: January 2020

Enteroviruses associate with aerobically and anaerobically digested sludge were determined before the addition of the sludge to a sludge lagoon. The fate of sludge-associated viruses was followed during detention of sludge in the lagoon and after application of sludge to land for disposal. While digested sludge was being added to the lagoon, enteroviruses were readily detected in grab samples of sludge from the lagoon. Sludge-associated viruses dropped to low or undetectable levels after disposal of sludge on land and during periods when addition of digested sludge to the lagoon was suspended. Changes in the levels of fecal coliforms in the lagooned sludge paralleled changes in the numbers of enteroviruses. Enteroviruses were not detected in water from deep wells located on the sludge disposal site or near the lagoon. During the initial part of the study, poliovirus serotypes accounted for greater than 90% of the viruses identified. Later, poliovirus serotypes comprised less than 40% of the virus isolates, and echoviruses and Coxsackieviruses were the most common enteroviruses identified.
Effect of Chlorine on
Giardia lamblia
Cyst Viability
Authors: Jarroll Edward L. , Bingham Alan K. , Meyer Ernest A.
Published: January 2020

The effect of chlorine concentration on
Giardia lamblia
cyst viability was tested under a variety of conditions. The ability of
Giardia
cysts to undergo excystation was used as the criterion of viability. The experimental variables employed included temperature (25, 15, and 5°C), pH (6, 7, and 8), chlorine-cyst contact time (10, 30, and 60 min), and chlorine concentration (1 to 8 mg/liter). In the pH range studied, cyst survival generally was observed to increase as buffer pH increased. Water temperature coupled with chlorination proved to be important in cyst survival. Results of these experiments at the three temperatures studied can be summarized as follows: at 25°C, exposure to 1.5 mg/liter for 10 min killed all cysts at pH 6, 7, and 8. At 15°C, 2.5 mg of chlorine per liter for 10 min killed all cysts at pH 6, but at pH 7 and 8 small numbers of cysts remained viable after 30 min but not after 60 min. At 5°C, 1 mg of chlorine per liter for 60 min failed to kill all the cysts at any pH tested. At this temperature, 2 mg of chlorine per liter killed all cysts after 60 min at pH 6 and 7, but not at pH 8. A chlorine concentration of 4 mg/liter killed all the cysts at all three pH values after 60 min, but not after 30 min. A chlorine concentration of 8 mg/liter killed all
Giardia
cysts at pH 6 and 7 after contact for 10 min, and at pH 8 after 30 min. This study points up the role of temperature, pH, and chlorine demand in the halogen treatment of drinking water to destroy cysts. It also raises an epidemiological problem, namely: low water temperatures, where killing of
Giardia
requires relatively high chlorine concentrations and long contact times, are (i) to be expected in many areas where epidemic waterborne giardiasis has been reported and (ii) particularly conducive to the long-term survival of
Giardia
cysts.
Morphological Survey of Microbial Mats Near Deep-Sea Thermal Vents
Authors: Jannasch Holger W. , Wirsen Carl O.
Published: January 2020

A microscopic survey is presented of the most commonly observed and morphologically conspicuous microorganisms found attached to natural surfaces or to artificial materials deposited in the immediate vicinity of thermal submarine vents at the Galapagos Rift ocean spreading zone at a depth of 2,550 meters. Of special interest were the following findings: (i) all surfaces intermittently exposed to H
2
S-containing hydrothermal fluid were covered by layers, ca. 5 to 10 μm thick, of procaryotic, gram-negative cells interspaced with amorphous metal (Mn-Fe) deposits; (ii) although some of the cells were encased by dense metal deposits, there was little apparent correlation between metal deposition and the occurrence of microbial mats, (iii) highly differentiated forms appeared to be analogues of certain cyanobacteria, (iv) isolates from massive mats of a prosthecate bacterium could be identified as
Hyphomicrobium
spp., (v) intracellular membrane systems similar to those found in methylotrophic and nitrifying bacteria were observed in approximately 20% of the cells composing the mats, (vi) thiosulfate enrichments made from mat material resulted in isolations of different types of sulfur-oxidizing bacteria including the obligately chemolithotrophic genus
Thiomicrospira.
Nitrogen Fixation by the Photosynthetic Sulfur Bacterium
Chlorobium phaeobacteroides
from Lake Kinneret
Authors: Bergstein T. , Henis Y. , Cavari B. Z.
Published: January 2020

N
2
fixation by
Chlorobium phaeobacteroides
from Lake Kinneret was dependent on ammonia concentration and light intensity. In the thermocline of Lake Kinneret, N
2
fixation and photosynthesis were low. It was concluded that the bacteria do not contribute significantly to the organic nitrogen load of the lake.
Second-Order Model to Predict Microbial Degradation of Organic Compounds in Natural Waters
Authors: Paris Doris F. , Steen William C. , Baughman George L. , Barnett John T.
Published: January 2020

The reliability of second-order rate constants for assessing microbial degradation kinetics in natural waters was examined by using three compounds that undergo hydrolytic degradation. The butoxyethyl ester of 2,4-dichlorophenoxyacetic acid was studied in water samples from 31 sites, malathion was examined in water from 14 sites, and chlorpropham was studied in samples from 11 sites. The coefficient of variation for rate constants for each compound was less than 65% over all sites. Additional studies indicated that the rate conformed to second-order kinetics; that is, the rate was proportional to both bacterial and xenobiotic concentrations.
Coliform species recovered from untreated surface water and drinking water by the membrane filter, standard, and modified most-probable-number techniques
Authors: Evans T M , LeChevallier M W , Waarvick C E , Seidler R J
Published: January 2020

The species of total coliform bacteria isolated from drinking water and untreated surface water by the membrane filter (MF), the standard most-probable-number (S-MPN), and modified most-probable-number (M-MPN) techniques were compared. Each coliform detection technique selected for a different profile of coliform species from both types of water samples. The MF technique indicated that Citrobacter freundii was the most common coliform species in water samples. However, the fermentation tube techniques displayed selectivity towards the isolation of Escherichia coli and Klebsiella. The M-MPN technique selected for more C. freundii and Enterobacter spp. from untreated surface water samples and for more Enterobacter and Klebsiella spp. from drinking water samples than did the S-MPN technique. The lack of agreement between the number of coliforms detected in a water sample by the S-MPN, M-MPN, and MF techniques was a result of the selection for different coliform species by the various techniques.
Chitinase-overproducing mutant of Serratia marcescens
Authors: Reid J D , Ogrydziak D M
Published: January 2020

Genetic modification of Serratia marcescens QMB1466 was undertaken to isolated mutants which produce increased levels of chitinolytic activity. After mutagenesis with ultraviolet light, ethyl methane sulfonate or N-methyl-N'-nitro-N-nitrosoguanidine, 19,940 colonies were screened for production of enlarged zones of clearing (indicative of chitinase activity) on chitin-containing agar plates. Forty-four chitinase high producers were tested further in shake flask cultures. Mutant IMR-1E1 was isolated which, depending on medium composition, produced two to three times more than the wild type of the other components of the chitinolytic enzyme system--a factor involved in the hydrolysis of crystalline chitin and chitobiase. After induction by chitin, endochitinase and chitobiase activity appeared at similar times for both IMR-1E1 and QMB1466, suggesting possible coordinate control of these enzymes. The results are consistent with IMR-1E1 containing a regulatory mutation which increased production of the components of the chitinolytic enzyme system and/or with IMR-1E1 containing a tandem duplication of the chitinase genes. The high rate of reversion of IMR-1E1 to decreased levels of chitinase production suggests that the overproduction of chitinase by IMR-1E1 is due to a tandem gene duplication.
Gentamicin-thallous-carbonate medium for isolation of fecal streptococci from foods
Authors: Thian T S , Hartman P A
Published: January 2020

Gentamicin-thallous-carbonate (GTC) agar was formulated by Donnelly and Hartman (Appl. Environ. Microbiol. 35:576-581, 1978) to select for fecal streptococci in sewage and water samples. The present study was conducted to determine the usefulness of GTC agar for the enumeration of fecal streptococci in foods. Comparisons were made with KF streptococcal (KF), Pfizer selective enterococcus (PSE), and thallous acetate (TA) agars. Samples of ground beef pork sausage, frozen broccoli, frozen fish, and ice cream were examined. Presumptive streptococcal counts obtained on GTC agar were significantly higher than those obtained on KF and PSE agars and were comparable to those obtained on TA agar. GTC was more sensitive than KF or PSE agars primarily because of the recovery of greater numbers of Streptococcus bovis and Streptococcus equinus strains. Percentages of confirmed fecal streptococci obtained on GTC, KF, PSE, and TA agars were 70, 95, 80, and 74, respectively. Differences between these percentages were not statistically significant, but they indicated that selectivity of GTC agar could be improved. Advantages of using GTC agar to isolate fecal streptococci from foods include a short incubation time (16 to 18 h) and large, distinct colonies that facilitate rapid enumeration and subsequent confirmation.
Mycophenolic Acid Production by
Penicillium brevicompactum
on Solid Media
Authors: Bartman C. D. , Doerfler D. L. , Bird B. A. , Remaley A. T. , Peace J. N. , Campbell I. M.
Published: January 2020

When grown on Czapek-Dox agar,
Penicillium brevicompactum
produced mycophenolic acid after a vegetative mycelium had been formed and as aerial hyphae were developing. Nutrients were still plenteous in the agar when the synthesis began. If aerial hyphal development was prevented by placing a dialysis membrane over the growing fungus, no mycophenolic acid was produced. When the dialysis membrane was peeled back and, as a consequence, production of aerial hyphae began, mycophenolic acid biosynthesis was observed. We concluded that mycophenolic acid was produced only by
P. brevicompactum
colonies that possessed an aerial mycelium.
Fate of Immediate Methane Precursors in Low-Sulfate, Hot-Spring Algal-Bacterial Mats
Authors: Sandbeck Kenneth A. , Ward David M.
Published: January 2020

The fates of acetate and carbon dioxide were examined in several experiments designed to indicate their relative contributions to methane production at various temperatures in two low-sulfate, hot-spring algal-bacterial mats. [2-
14
C]acetate was predominantly incorporated into cell material, although some
14
CH
4
and
14
CO
2
was produced. Acetate incorporation was reduced by dark incubation in short-term experiments and severely depressed by a 2-day preincubation in darkness. Autoradiograms showed that acetate was incorporated by long filaments resembling phototrophic microorganisms of the mat communities. [
3
H]acetate was not converted to C
3
H
4
in samples from Octopus Spring collected at the optimum temperature for methanogenesis. NaH
14
CO
3
was readily converted to
14
CH
4
at temperatures at which methanogenesis was active in both mats. Comparisons of the specific activities of methane and carbon dioxide suggested that of the methane produced, 80 ± 6% in Octopus Spring and 71 ± 21% in Wiegert Channel were derived from carbon dioxide. Addition of acetate to 1 mM did not reduce the relative importance of carbon dioxide as a methane precursor in samples from Octopus Spring. Experiments with pure cultures of
Methanobacterium thermoautotrophicum
suggested that the measured ratio of specific activities might underestimate the true contribution of carbon dioxide in methanogenesis.
Inhibitory Effect of Nitrapyrin on Three Genera of Ammonia-Oxidizing Nitrifiers
Authors: Belser L. W. , Schmidt E. L.
Published: January 2020

Five strains of
Nitrosomonas
and one each of
Nitrosospira
and
Nitrosolobus
were examined for sensitivity to the nitrification inhibitor nitrapyrin. Considerable variation in sensitivity was observed, with some strains about five times more resistant than others. Sensitivity to nitrapyrin varied more with strain than with genus.
Substrate specificity and stereospecificity of nicotinamide adenine dinucleotide-linked alcohol dehydrogenases from methanol-grown yeasts
Authors: Hou C T , Patel R , Laskin A I , Barnabe N , Marczak I
Published: January 2020

Nicotine adenine dinucleotide-linked primary alcohol dehydrogenase and a newly discovered secondary alcohol dehydrogenase coexist in most strains of methanol-grown yeasts. Alcohol dehydrogenases from methanol-grown yeasts oxidize (--)-2-butanol preferentially over its (+) enantiomorph. This is substantially different from alcohol dehydrogenases from bakers' yeast and horse liver.
Problems Associated with the Use of Azide as an Inhibitor of Microbial Activity in Soil
Authors: Rozycki Michael , Bartha Richard
Published: January 2020

Problems associated with the use of sodium or potassium azide as an inhibitor of microbial activity in soil include erroneous CO
2
evolution readings, shifts in inhibitor concentration, rise in soil pH, and explosion hazard.
Isolation of Candida albicans from freshwater and sewage
Authors: Cook W L , Schlitzer R L
Published: January 2020

The isolation and identification of Candida albicans from polluted aquatic environments were facilitated by the inclusion of a selective medium and a differential screening medium to detect the reduction of 2,3,5-triphenyltetrazolium chloride. C. albicans occurred commonly in low numbers in sewage influents, rivers, and streams.
Biphasic resin system for growing concentrated cultures of microorganisms and its application to the cultivation of Neisseria gonorrhoeae
Authors: Giard R L , Vedros N A
Published: January 2020

A technique is described in which a polyester casting resin is used instead of agar for the growth of Neisseria gonorrhoeae in a biphasic system. In complex medium, higher concentrations and stability of T1 colony type were obtained with resin than with either agar or broth alone after 24 h of incubation. In defined medium, the growth of gonococci and colony type stability were similar in single-phase and resin systems and superior to the growth and stability occurring in the biphasic agar system.
Syntrophomonas wolfei
gen. nov. sp. nov., an Anaerobic, Syntrophic, Fatty Acid-Oxidizing Bacterium
Authors: McInerney M. J. , Bryant M. P. , Hespell R. B. , Costerton J. W.
Published: January 2020

An anaerobic, nonphototrophic bacterium that β-oxidizes saturated fatty acids (butyrate through octanoate) to acetate or acetate and propionate using protons as the electron acceptor (H
2
as electron sink product) was isolated in coculture with either a non-fatty acid-degrading, H
2
-utilizing
Desulfovibrio
sp. or methanogens. Three strains of the bacterium were characterized and are described as a new genus and species,
Syntrophomonas wolfei. S. wolfei
is a gram-negative, slightly helical rod with round ends that possesses between two to eight flagella laterally inserted along the concave side of the cell. It has a multilayered cell wall of the gram-negative type. The presence of muramic acid, inhibition of growth by penicillin, and increased sensitivity of the cells to lysis after treatment with lysozyme indicate that peptidoglycan is present in the cell wall. Cells of
S. wolfei
contain poly-β-hydroxybutyrate. Isoheptanoate was degraded to acetate, isovalerate, and H
2
. Carbohydrates, proteinaceous materials, alcohols, or other tested organic compounds do not support growth. Common electron acceptors are not utilized with butyrate as the electron donor. Growth and degradation of fatty acids occur only in syntrophic association with H
2
-using bacteria. The most rapid generation time obtained by cocultures of
S. wolfei
with
Desulfovibrio
and
Methanospirillum hungatei
is 54 and 84 h, respectively. The addition of Casamino Acids but neither Trypticase nor yeast extract stimulated growth and resulted in a slight decrease in the generation time of
S. wolfei
cocultured with
M. hungatei.
The addition of H
2
to the medium stopped growth and butyrate degradation by
S. wolfei.
Loss of plasmids during enrichment for Escherichia coli
Authors: Hill W E , Carlisle C L
Published: January 2020

Enrichment with sodium lauryl sulfate and incubation at 44.5 degrees C resulted in a loss of plasmids and decreased efficiency in the recovery of pathogenic. Escherichia coli strains from foods.
Effect of temperature on growth and activity of Aeromonas spp. and mixed bacterial populations in the Anacostia River
Authors: Cavari B Z , Allen D A , Colwell R R
Published: January 2020

During the winter months, total bacterial counts in the water column and in the sediment in the Anacostia River were two- to eightfold higher than at other times of the year, whereas Aeromonas spp. decreased in number of several orders of magnitude. This significant decrease in number in the Anacostia River during the cold months of the year can be explained by the low metabolic activity of Aeromonas at low temperatures.
Chemically Defined Minimal Medium for Growth of the Anaerobic Cellulolytic Thermophile
Clostridium thermocellum
Authors: Johnson Eric A. , Madia Ashwin , Demain Arnold L.
Published: January 2020

A minimal chemically defined medium has been developed for
Clostridium thermocellum
. The growth factors required are biotin, pyridoxamine, vitamin B
12
, and
p
-aminobenzoic acid.
Acinetobacter spp.: distinct morphology on eosin methylene blue agar as an aid to identification in drinking water
Authors: Spino D F , Geldreich E E
Published: January 2020

Acinetobacter calcoaceticus, frequently found in drinking waters and implicated in nosocomial infections, was presumptively identified by its tiny, blue colonial appearance on Levine eosin methylene blue agar. All of the 33 isolates from drinking water showing this distinctive colonial appearance were identified as A. calcoaceticus.
Utilization of Xylan by Two Species of Human Colonic
Bacteroides
Authors: Salyers Abigail A. , Gherardini Frank , O'Brien Mildred
Published: January 2020

During growth of two strains of human colonic
Bacteroides
on xylan, several oligomers, the smallest of which was xylobiose, were released into the medium.
T1 bacteriophage as an indicator for decontamination of laminar-flow biological safety cabinets
Authors: Jones K E , Wetzler T F , Kenny G E
Published: January 2020

Type 1 coliphage dried onto a glass surface was used as an indicator to monitor decontamination of biological safety cabinets. When desiccated virus was treated with formaldehyde vapor (5,000 or 10,000 ppm) adjusted to 70 to 90% relative humidity immediately before testing, viral inactivation was slow for the first 50 min but then accelerated, being complete in the next 10 min. However, when virus was incubated in an atmosphere containing 70% humidity for 1 h before formaldehyde was added, inactivation was complete within 3 min, indicating that careful attention must be paid to relative humidity in decontamination of safety cabinets.
Identification, distribution, and toxigenicity of obligate anaerobes in polluted waters
Authors: Daily O P , Joseph S W , Gillmore J D , Colwell R R , Seidler R J
Published: January 2020

A seasonal occurrence of obligately anaerobic bacteria, predominantly of the genera Bacteroides and Clostridium, in a polluted water site has been observed. The number of anaerobes varied from 1.8 X 10(3) cells/ml in the warmer months to 10 cells/ml in winter. Several isolates were toxigenic, indicating a potential human health hazard.
Microbial profiles of country-cured hams aged in stockinettes, barrier bags, and paraffin wax
Authors: Draughon F A , Melton C C , Maxedon D
Published: January 2020

No significant differences were found in surface microflora of county-cured hams covered with stockinettes, barrier bags, or a coating of paraffin wax during aging, except for a reduction in mold growth on waxed hams. The incidence of Clostridium spp. was lost in all treatments. Micrococcus spp. and Streptococcus spp. were the most common contaminants, but caused no apparent spoilage problem in any treatment.
Enzyme Thermistor Analysis of Penicillin in Standard Solutions and in Fermentation Broth
Authors: Mattiasson Bo , Danielsson Bengt , Winquist Fredrik , Nilsson Hans , Mosbach Klaus
Published: January 2020

Immobilized penicillinase was applied in an enzyme thermistor for calorimetric analysis of samples containing penicillin G. Standard solutions as well as extracts from fermentation broth were analyzed. The enzyme was applied bound either to porous glass or, when dealing with crude preparations, to the inner surface of nylon tubing. In the fermentation system studied, high concentrations of penicillin were present, thus allowing dilution to reduce the influence of the composition of the medium on the analysis. The useful linear concentration range was from 0.1 to 100 mM. The coefficient of correlation between analytical results obtained with the present method and those from conventional assays was 0.997.