bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal inactivation of eight Salmonella serotypes on dry corn flour
Authors: VanCauwenberge J E , Bothast R J , Kwolek W F
Published: January 2020

Dry heat was used to inactivate Salmonella newington, Salmonella typhimurium, Salmonella anatum, Salmonella kentucky, Salmonella cubana, Salmonella seftenberg, Salmonella thompson, and Salmonella tennessee in corn flour at 10 and 15% moisture. The flour was spray inoculated at 10(5) Salmonella cells per g and then stored at 49 degrees C (120 degrees F); viable Salmonella cells were counted on Trypticase (BBL Microbiology Systems) soy agar plates every 30 min for the first 4 h and then at 4-h intervals for 20 additional h of storage. After 24 h, 99.9% of all Salmonella cells were killed. S. thompson and S. tennessee were more resistant to heat inactivation than the other serotypes. Naturally occurring contamination by Salmonella spp. in dry food products could be significantly reduced with this treatment.
Modified enrichment-serology procedure for detection of salmonellae in soy products
Authors: Surdy T E , Haas S O
Published: January 2020

A modified enrichment-serology (MES) procedure was used to reduce the time necessary for salmonella analysis. Naturally contaminated samples of soy products were preenriched in 1% proteose peptone for 6 h at 37 degrees C followed by inoculation into tetrathionate broth for 18 h at 37 degrees C. Two drops of the tetrathionate sample were inoculated into M broth. After incubation at 37 degrees C for 6 h, 0.85 ml of the mixture was formolized, and 0.1 ml of polyvalent H antiserum was added. After incubation in water bath at 50 degrees C for 1 h, the appearance of a typical floccular flagellar precipitate was observed in tubes positive for salmonellae. Over 3,000 samples were subjected to standard biochemical and serological procedures, and the results were compared with those of the MES method with a 96.7% correlation. Eleven of the samples (0.3%) were false-negative with the MES procedure, and 3% were false-negative with the U.S. Food and Drug Administration Bacteriological Analytical Manual procedure. The 3% negative samples by this latter procedure were subsequently found to be positive by the MES procedure. The MES procedure reduced the time required for salmonella analysis from 4 days to 32 h.
Dissolved Hydrocarbons and Related Microflora in a Fjordal Seaport: Sources, Sinks, Concentrations, and Kinetics
Authors: Button D. K. , Robertson Betsy R. , Craig Kathleen S.
Published: January 2020

The continuous addition of toluene as a solute of treated ballast water from oil tankers into a well-defined estuary facilitated the study of the dynamics of dissolved hydrocarbon metabolism in seawater. Most rates of toluene oxidation were in the range of 1 to 30 pg/liter per h at 0.5 μg of toluene per liter. Near the ballast water injection point, a layer of warm ballast water, rich in bacteria, that was trapped below the less-dense fresh surface water was located. Toluene residence times were approximately 2 weeks in this layer, 2 years elsewhere in Port Valdez, and 2 decades in the surface water of a more oceanic receiving estuary adjacent. Mixing was adequate for a steady-state treatment which showed that 98% of the toluene was flushed from Port Valdez before metabolism and gave a steady-state concentration of 0.18 μg/liter. Total bacterial biomass from direct counts and organism size data was usually near 0.1 mg/liter, but ranged up to 0.8 mg/liter in the bacteria-rich layer. The origin of bacteria in this layer was traced to growth in oil tanker ballast during shipments. The biomass of toluene oxidizers in water samples was estimated from the average affinity of pure-culture isolates for toluene (28 liters per g of cells per h) and observed toluene oxidation kinetics. Values ranged from nearly all of the total bacterial biomass within the bacteria-rich layer down to 0.2% at points far removed. Because the population of toluene oxidizers was large with respect to the amount of toluene consumed and because water from a nearby nonpolluted estuary was equally active in facilitating toluene metabolism, we searched for an additional hydrocarbon source. It was found that terpenes could be washed from spruce trees by simulated rainfall, which suggested that riparian conifers provide an additional and significant hydrocarbon source to seawater.
Effects of Salinity on Acetylene Reduction (Nitrogen Fixation) and Respiration in a Marine
Azotobacter
Authors: Dicker Howard J. , Smith David W.
Published: January 2020

An acetylene-reducing (nitrogen-fixing) bacterium, identified as
Azotobacter
sp., was isolated from a site in the Canary Creek Marsh, Del. Acetylene reduction activity of the isolate was maximal at 15 to 25‰ NaCl, with no activity observed at 0 or 60‰. Respiration studies showed similar results, with maximal activity occurring at a slightly lower salinity (10 to 20‰ NaCl). The salinities over which peak activity occurred fell within the normal range of in situ salinity (20 to 28‰ total salinity).
Immunological and biophysical alteration of hepatitis B virus antigens by sodium hypochlorite disinfection
Authors: Sehulster L M , Hollinger F B , Dreesman G R , Melnick J L
Published: January 2020

Sodium hypochlorite (NaOCl) was examined as an effective disinfectant in hepatitis laboratories. Concentrations of NaOCl containing 5,600 ppm (5,600 microgram/ml) of available chlorine were found to be effective in destroying the antigenicity of hepatitis B surface antigen (HBsAg) in virion-rich plasma after an exposure time of 1 min or more. In the treatment of protein-deficient solutions containing HBsAg, smaller concentrations of available chlorine (less than 500 pm) are equally effective. Neither 17-to 25-nm HBsAg particles nor 45-nm virion particles could be detected by electron microscopy after treatment. chemical interaction of protein and NaOCl was confirmed by isoelectrofocusing of 125I-labeled HBsAg. More than 90% of the labeled material was found at pH 3.0 or lower, indicating complete antigen oxidation. Labeled HBsAg was reduced in density from 1.21 g/cm3 in CsCl to approximately 1.07 g/cm3 after treatment with NaOCl. Both hepatitis B core antigen and deoxyribonucleic acid polymerase activity were significantly reduced after interaction with hypochlorite solutions. These results show that NaOCl destroys hepatitis B antigenicity and virus structures and therefore may be utilized as a disinfectant for the virus.
Glycine-containing selective medium for isolation of Legionellaceae from environmental specimens
Authors: Wadowsky R M , Yee R B
Published: January 2020

Glycine, at a final concentration of 0.3%, has been shown to be an excellent selective agent for the isolation of Legionellaceae. Stock cultures of Legionella pneumophila were not inhibited on buffered charcoal-yeast extract agar containing the amino acid. Among the other Legionellaceae tested, only one of two strains of L. dumoffii and two of six strains of L. micdadei were appreciably inhibited. This medium permitted the isolation of L. pneumophila from environmental specimens with marked inhibition of many non-Legionellaceae bacteria. The selectivity of the medium was subsequently improved by the incorporation of vancomycin (5 microgram/ml) and polymyxin B (100 U/ml). This selective medium, glycine-vancomycin-polymyxin B agar, should facilitate the recovery of Legionellaceae from environmental sources.
Production of
l
-Phenylalanine from
trans
-Cinnamic Acid with
Rhodotorula glutinis
Containing
l
-Phenylalanine Ammonia-Lyase Activity
Authors: Yamada Shigeki , Nabe Koichi , Izuo Nobuhiko , Nakamichi Katsuhiko , Chibata Ichiro
Published: January 2020

An enzymatic method using
l
-phenylalanine ammonia-lyase (EC 4.3.1.5) for the rapid conversion of
trans
-cinnamic acid to
l
-phenylalanine has been investigated. With
Rhodotorula glutinis
, enzyme activity as high as 0.3 U/ml of culture broth was obtained. The enzyme activity was kept stable for a relatively long time during cultivation by the addition of
l
-isoleucine. Optimization of the parameters of the conversion reaction resulted in accumulation of 18 mg of
l
-phenylalanine per ml of reaction mixture. The conversion yield from
trans
-cinnamic acid was about 70%. The method may provide a rapid and practical way to produce
l
-phenylalanine useful as an essential amino acid.
Long-Term Effects of Crude Oil on Uptake and Respiration of Glucose and Glutamate in Arctic and Subarctic Marine Sediments
Authors: Griffiths Robert P. , Caldwell Bruce A. , Broich William A. , Morita Richard Y.
Published: January 2020

The effects of crude oil on uptake and respiration (mineralization) of glucose and glutamate in marine sediments were investigated. After the sediments were treated with crude oil, they were replaced at or near the collection site by scuba divers. These sediments remained in situ until they were retrieved for analysis. Glucose and glutamate uptake rates were found to decrease, and the percent respired was found to increase in Arctic and subarctic marine sediments that had been exposed to fresh crude oil. These same changes were also observed when “weathered” crude oil was used and when untreated sediments were overlaid with oiled sediments. When the kinetics of glutamate uptake were determined, both the maximum potential uptake rate and the turnover time were significantly affected. A comparison between the proportion of glucose taken into the cells and that respired as CO
2
indicated that crude oil affected biosynthetic mechanisms. A study of sediments that had been exposed to crude oil for at least 5 months showed that glutamate transport into the cells was affected more extensively than biosynthetic mechanisms. In the initial months of exposure, bacterial concentrations and total adenylate concentrations were found to decrease in the presence of crude oil. Our data suggest that secondary productivity in the marine environment could be adversely affected by the presence of crude oil in marine sediments.
Simultaneous Rates of Ribonucleic Acid and Deoxyribonucleic Acid Syntheses for Estimating Growth and Cell Division of Aquatic Microbial Communities
Authors: Karl David M.
Published: January 2020

A method for measuring rates of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) syntheses using a single radioactive precursor has been devised and tested using bacterial cultures and natural assemblages of marine and freshwater microorganisms. The procedure is based upon the uptake and incorporation of exogenous [
3
H]adenine into cellular adenosine triphosphate and deoxyadenosine triphosphate pools which serve as the immediate precursors for the adenine incorporated into RNA and DNA, respectively. It is proposed that the DNA/RNA rate ratio is correlated with the specific growth rate of microorganisms and can be used as an index for estimating and comparing the productivities of microbial assemblages in nature. This technique can also be used to detect discontinuous growth and cell division processes which frequently occur in surface plankton populations. The DNA/RNA rate ratios measured in a variety of aquatic ecosystems ranged from 3.3 to 31.8% without significant correlation to total microbial biomass.
Mechanism of poliovirus inactivation by bromine chloride
Authors: Keswick B H , Fujioka R S , Loh P C
Published: January 2020

The mechanism of poliovirus inactivation by BrCl was determined by exposing poliovirus to various concentrations of BrCl and correlating the loss of virus infectivity with structural changes of the virus. Concentrations of 0.3 to 5 mg of BrCl per liter resulted in 95% to total inactivation of poliovirus. However, the inactivated virus retained structural integrity, as determined by buoyant density measurements of poliovirus labeled with radioactivity. However, at concentrations of 10 to 20 mg of BrCl per liter, total inactivation of poliovirus was associated with the degradation of the structural integrity of the virus. Since infectious ribonucleic acid at similar concentrations could be recovered from untreated poliovirus and poliovirus treated with 0.3 mg of BrCl per liter, it was concluded that BrCl as HOBr or bromamines inactivates poliovirus by reacting with the protein coat of the virus. Moreover, this inactivating reaction does not result in the degradation of the structure of the virion, nor does it affect the biological activity of the internal ribonucleic acid of the virus.
Cellulase and Xylanase Release from
Bacteroides succinogenes
and Its Importance in the Rumen Environment
Authors: Forsberg Cecil W. , Beveridge Terrance J. , Hellstrom Anita
Published: January 2020

During growth of
Bacteroides succinogenes
in a liquid medium with cellulose as the source of carbohydrate, greater than 80% of the carboxymethylcellulase (endo-β-1,4-glucanase), xylanase, and aryl-β-xylosidase and 50% of the aryl-β-glucosidase released from cells into the culture fluid. Less than 25% of the cellobiase activity was detected in the culture fluid. Approximately 50% of each of the released enzymes measured was associated with sedimentable subcellular membrane vesicles. The vesicles appeared to be released from the outer membrane of intact cells by bleb formation, primarily in pockets between the cells and the cellulose, although a few unattached cells with blebs were seen. Many vesicles were seen adhering to cellulose, and they were also seen free in the culture fluid. These data suggest that
B. succinogenes
releases hydrolytic enzymes in nonsedimentable and particulate forms during growth by a mechanism which has until now received little attention. Cellulose incubated in a porous nylon bag in the rumen was colonized by bacteria resembling
B. succinogenes
, and subcellular vesicles were seen penetrating channels and fractures in the cellulose. On this basis, it is suggested that
B. succinogenes
cells in the rumen contribute to an extracellular population of subcellular vesicles that possess cellulolytic and hemicellulolytic activities which probably enhance polymer digestion and provide a source of sugars for microbes lacking polymer-degrading activity, thereby contributing to a stable heterogeneous microbial population.
Transduction of Lactose Metabolism by
Streptococcus cremoris
C3 Temperate Phage
Authors: Snook René J. , McKay Larry L. , Ahlstrand Gilbert G.
Published: January 2020

Temperate phage was induced from
Streptococcus cremoris
C3 and morphologically characterized by high-resolution electron micrographic techniques. Interspecies genetic transfer of lactose-fermenting ability by the temperate phage was demonstrated, using two lactose-negative (Lac
−
)
S. lactis
strains as recipients. Plasmid transfer was confirmed by agarose gel electrophoresis. Transductant plasmid profiles were of three types—those containing no visible plasmid deoxyribonucleic acid, those possessing a 23-megadalton (Mdal) plasmid, and those containing a 23-Mdal plasmid and a 30-Mdal plasmid. A Lac
+
transductant could serve as a donor of the
lac
determinants during solid-surface matings. These results add to previously published reports of inter- and intraspecies genetic transfer in dairy starter cultures.
Positively charged filters for virus recovery from wastewater treatment plant effluents
Authors: Chang L T , Farrah S R , Bitton G
Published: January 2020

Positively charged Zeta Plus filters were used to concentrate enteroviruses from 19 liters of effluent from activated sludge units. Neither the addition of salts nor the acidification of the effluent was required for adsorption of viruses to the filters. Viruses adsorbed to the filters were eluted by treating the filters with a solution of 4 M urea buffered at pH 9 with 0.05 M lysine. Eluted viruses were concentrated into final volumes of 1 to 2 ml by using a two-step concentration procedure that employed inorganic and organic flocculation. Approximately 50% of the viruses added to effluents could be recovered in the final sample. The procedure was used to monitor effluents from activated sludge units at two wastewater treatment plants for the presence of enteroviruses.
Phosphorus-Limited Growth of a Green Alga and a Blue-Green Alga
Authors: Lang Douglas S. , Brown Edward J.
Published: January 2020

The phosphorus-limited growth kinetics of the chlorophyte
Scenedesmus quadricauda
and the cyanophyte
Synechococcus
Nägeli were studied by using batch and continuous culturing techniques. The steady-state phosphate transport capability and the phosphorus storage capacity is higher in
S.
Nägeli than in
S. quadricauda. Synechococcus
Nägeli can also deplete phosphate to much lower levels than can
S. quadricauda.
These results, along with their morphological characteristics, were used to construct partial physiological profiles for each organism. The profiles indicate that this unicellular cyanophyte (cyanobacterium) is better suited for growth in phosphorus-limited oligotrophic niches than is this chlorophyte (green alga).
Catabolism of Phloroglucinol by the Rumen Anaerobe
Coprococcus
Authors: Patel T. R. , Jure K. G. , Jones G. A.
Published: January 2020

A rumen isolate,
Coprococcus
, sp. Pe
1
5, was found to carry phloroglucinol reductase, which catalyzed the initial step in the breakdown of phloroglucinol. The organism uses phloroglucinol as the sole source of carbon and energy when grown in the absence of oxygen. Induced levels of enzyme were detected in cells grown either on phloroglucinol or on other carbon sources in the presence of limiting quantities of phloroglucinol. Although the organism is a strict anaerobe, the enzyme from anaerobically grown cells was insensitive to air. The partially purified enzyme required reduced nicotinamide adenine dinucleotide phosphate as an electron donor and was specific for phloroglucinol. However, partial enzyme activity (14 to 17%) was also detected in the presence of 2-methyl-1,4-naphthoquinone but not in the presence of several other phenolic compounds. The enzyme exhibited a higher affinity for phloroglucinol than for reduced nicotinamide adenine dinucleotide phosphate, with

K
m

values of 3.0 × 10
−5
M and 29.0 × 10
−5
M, respectively. The optimum pH for maximal enzyme activity was 7.4, and the molecular weight of the native protein was about 130,000, as determined by the Sephadex gel filtration technique.
Salivary syndrome in horses: identification of slaframine in red clover hay
Authors: Hagler W M , Behlow R F
Published: January 2020

An outbreak of salivary syndrome in horses in North Carolina was investigated. Rhizoctonia leguminicola was the predominant fungus isolated from toxic red clover hay. The fungus was less prevalent in the hay after 10 months of storage, and the hay had also decreased in biological activity after 10 months. Toxic hay caused extreme salivation, piloerection, respiratory distress, and increased frequency of defecation when fed to guinea pigs, and purified extracts of toxic hay and pure slaframine elicited these same responses when injected intraperitoneally into guinea pigs. The freshly acquired hay, based on the biological (slobber-producing) activity in hay and in purified extracts, contained the equivalent to 50 to 100 ppm (50 to 100 microgram/g) of slaframine, but this level had decreased after 10 months by about 10-fold to about 7 ppm. Slaframine and seven synthetic derivates of slaframine were used in presumptive gas-liquid chromatographic identification of this mycotoxin. Slaframine (1-acetoxy-6-amino-octahydroindolizine) was identified in purified extracts of toxic hay by gas-liquid chromatography-mass spectrometry after preparative thin-layer chromatography. This was the first direct identification of slaframine in toxic red clove hay.
Prolonged survival of Serratia marcescens in chlorhexidine
Authors: Marrie T J , Costerton J W
Published: January 2020

During an outbreak of Serratia marcescens infections at our hospital, we discovered widespread contamination of the 2% chlorhexidine hand-washing solution by S. marcescens. Examination by electron microscopy of the sides of bottles in which this solution was stored revealed that microorganisms were embedded in a fibrous matrix. Bacteria, free in the liquid, were morphologically abnormal, showing cell wall disruption or cytoplasmic changes. Furthermore, bacteria adherent to the walls of the storage jugs and embedded in this fibrous matrix also had morphologically abnormal cytoplasm. Despite these changes, viable S. marcescens organisms were recovered from the fluid during a storage period of 27 months. The concentration of chlorhexidine required to inhibit these strains of Serratia was 1,024 microgram/ml; however, the organism could survive in concentrations of up to 20,000 micrograms/ml. Additional studies are needed to define the mechanism(s) that allows such bacteria to contaminate and survive in disinfectants.
Entrance and Growth of Lactic Acid Bacteria in Gas-Exchanged, Brined Cucumbers
Authors: Daeschel M. A. , Fleming H. P.
Published: January 2020

Entrance of lactic acid bacteria into the interior of brined cucumbers was found to be greatly influenced by gas composition of the cucumbers before brining. Exchange of the internal gas of fresh cucumbers with O
2
resulted in absorption of bacteria into the subsequently brined fruit within a few hours. Bacteria were absorbed into nonexchanged cucumbers to a lesser extent. Little bacterial absorption occurred in N
2
-exchanged cucumbers. Stomata of the cucumber skin appeared to be a likely port for bacterial entry. When
Pediococcus cerevisiae
or
Lactobacillus plantarum
cells were added to the brine of O
2
-exchanged cucumbers, the respective cell types colonized in large numbers within intercellular spaces and vascular elements of mesocarp tissue during fermentation of the cucumbers. Implications of these observations, particularly with regard to bloater formation in brined cucumbers, are discussed.
Isolation of a Strain of
Clostridium thermoaceticum
Capable of Growth and Acetic Acid Production at pH 4.5
Authors: Schwartz Robert D. , Keller Frederick A.
Published: January 2020

Using a series of pH controlled batch fermentations operated in a fed-batch mode and adaptation and selection techniques where pH and acetic acid provided the selective pressures, we isolated a culture of
Clostridium thermoaceticum
that can grow and produce acetic acid at pH 4.5. At pH 4.5 the fastest mass doubling time was 36 h, and the highest acetic acid concentration reached was 4.5 g/liter. Generally, as the pH was decreased from 6.0 and the initial acetic acid concentration increased, the mass doubling time increased, and the final acetic acid concentration decreased. These observations can be explained in terms of inhibition by the free acetic acid concentration at a given pH, relative to the total acetic acid concentration (free acid plus acetate ion). We have thus reached one of the criteria determined by us to be required for an economically viable fermentation acetic acid process, i.e., pH 4.5. A second requirement for a mass doubling time of about 7 h (0.1/h dilution rate) can probably be reached by selection in continuous culture. The final requirement for an acetic acid concentration of 50 g/liter will be the most difficult to achieve in view of the organism's sensitivity to low concentrations of free acetic acid.
Isolation of a bile salt sulfatase-producing Clostridium strain from rat intestinal microflora
Authors: Huijghebaert S M , Mertens J A , Eyssen H J
Published: January 2020

Bile acid sulfates, formed in human and rat livers, are desulfated by the intestinal microflora. In our study we first isolated from conventional rat feces an unnamed bacterium, termed strain S1, which desulfated the 5 beta-bile salt 3 alpha-sulfates in vitro and in vivo after association with gnotobiotic rats. Strain S1 also possessed 12 alpha-hydroxysteroid dehydrogenase and bile salt-deconjugating activities. The strain was a strict anaerobic, CO2-requiring, gram-negative, sporeforming rod and was designated as belonging to the genus Clostridium. Growth was scarce in culture media, unless in the presence of 0.1% taurine, a sulfur-containing amino acid. Addition of this substance raised the number of bacteria in thioglycolate and peptone yeast media from 10(4) per ml to 10(6) to 10(7) per ml and increased the colony diameter on agar medium from 0.2 mm to 0.5 to 0.9 mm. Sulfatase activity was specific for the 5 beta-bile salt sulfates, leaving the 5 alpha-bile salt sulfates unchanged. In addition, the sulfatase activity was cell bound, and its production was dependent on the composition of the culture medium, although no minimal sulfur medium was required for sulfatase activity.
Feasibility of
55
Fe Autoradiography as Performed on N
2
-Fixing
Anabaena
spp. Populations and Associated Bacteria
Authors: Paerl Hans W.
Published: January 2020

55
Fe emits low-energy X rays and Auger electrons by electron capture decay. Auger electrons are useful for autoradiographic examination of
55
Fe incorporation among microbial communities. Attainable resolution, in terms of silver grain deposition, is excellent and comparable to
3
H. Two known Fe-demanding processes, photosynthetic CO
2
fixation and N
2
fixation, were examined by autoradiography of
Anabaena
populations. During photosynthetically active (illuminated) N
2
-fixing periods, biological incorporation of
55
FeCl
3
by vegetative cells and heterocysts was evident. When N
2
fixation was suppressed by NH
4
+
additions, heterocysts revealed no incorporation of
55
Fe. Conversely, when N
2
-fixing
Anabaena
filaments were placed in darkness,
55
Fe incorporation decreased in vegetative cells, whereas heterocysts showed sustained rates of
55
Fe incorporation. Bacteria actively incorporated
55
Fe under both light and dark conditions. The chelated (by Na
2
-ethylenediaminetetraacetate) form of
55
FeCl
3
was more readily incorporated than the nonchelated form. Furthermore, abiotic adsorption of
55
Fe to filters and nonliving particles proved lower when chelated
55
Fe was used in experiments.
55
Fe autoradiography is useful for observing the fate and cellular distribution of various forms of Fe among aquatic microbial communities.
Localized Tetrazolium Reduction in Relation to N
2
Fixation, CO
2
Fixation, and H
2
Uptake in Aquatic Filamentous Cyanobacteria
Authors: Paerl Hans W. , Bland Patricia T.
Published: January 2020

The aquatic filamentous cyanobacteria
Anabaena oscillarioides
and
Trichodesmium
sp. reveal specific cellular regions of tetrazolium salt reduction. The effects of localized reduction of five tetrazolium salts on N
2
fixation (acetylene reduction),
14
CO
2
fixation, and
3
H
2
utilization were examined. During short-term (within 30 min) exposures in
A. oscillarioides
, salt reduction in heterocysts occurred simultaneously with inhibition of acetylene reduction. Conversely, when salts failed to either penetrate or be reduced in heterocysts, no inhibition of acetylene reduction occurred. When salts were rapidly reduced in vegetative cells,
14
CO
2
fixation and
3
H
2
utilization rates decreased, whereas salts exclusively reduced in heterocysts were not linked to blockage of these processes. In the nonheterocystous genus
Trichodesmium
, the deposition of reduced 2,3,5-triphenyl-2-tetrazolium chloride (TTC) in the internal cores of trichomes occurs simultaneously with a lowering of acetylene reduction rates. Since TTC deposition in heterocysts of
A. oscillarioides
occurs contemporaneously with inhibition of acetylene reduction, we conclude that the cellular reduction of this salt is of use in locating potential N
2
-fixing sites in cyanobacteria. The possible applications and problems associated with interpreting localized reduction of tetrazolium salts in cyanobacteria are presented.
Teflon chemostat for studies of trace metal metabolism in Streptococcus mutans and other bacteria
Authors: Strachan R C , Aranha H , Lodge J S , Arceneaux J E , Byers B R
Published: January 2020

A teflon chemostat constructed for studies of microbial trace metal metabolism is described. The utility of this continuous culture system was demonstrated with Streptococcus mutans, in which iron and manganese stimulated growth in ranges of 0.18 to 0.45 and 18 to 54 microM, respectively. This device should facilitate studies of the effect of trace metals on a variety of physiological functions.
Two Naturally Occurring Nuclear Polyhedrosis Virus Variants of
Neodiprion sertifer
Geoffr. (Hymenoptera; Diprionidae)
Authors: Brown David A.
Published: January 2020

Two isolates of
Neodiprion sertifer
(Geoffr.) nuclear polyhedrosis virus from Britain and North America were compared using three biochemical techniques. Alkaline protease assays of polyhedra revealed the presence of endogenous enzyme activity in the British isolate but not in the North American isolate. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of virus particle structural polypeptides revealed only minor differences, with the exception that the North American virus was contaminated with polyhedral protein. The restriction endonucleases
Sal
I,
Hind
III, and
Hpa
II were used as a definitive method of distinguishing the two variants, with all endonucleases achieving this to a greater or lesser extent. The possible significance of all of these observations is discussed in terms of their possible influence on the registration and field application of this virus.
Growth of
Eubacterium limosum
with Carbon Monoxide as the Energy Source
Authors: Genthner B. R. Sharak , Bryant M. P.
Published: January 2020

Eubacterium limosum
grew with CO as the sole source of energy and formed acetate and CO
2
as the major products. The generation time on CO was 7 h. Uninhibited growth occurred in cultures containing 50% CO or less, but growth occurred at all concentrations tested (i.e., up to 75% CO). The pH optimum for growth was 7.0 to 7.2, whereas growth was poor at a pH below 6.7. CO
2
stimulated growth on CO. CO was preferentially utilized when both CO and H
2
were present.
Regulation of beta-D-galactosidase synthesis in Candida pseudotropicalis
Authors: Pedrique M , Castillo F J
Published: January 2020

Regulation of lactose (beta-D-galactosidase) synthesis in the lactose-utilizing yeast Candida pseudotropicalis was studied. The enzyme was inducible by lactose and galactose. When grown on these sugars the enzyme level of the yeast was 20 times or higher than when grown on glycerol. The Km and optimal pH were similar for the lactase induced either by lactose or galactose. The hydrolysis of o-nitrophenyl-beta-D-galactopyranoside by the lactase was inhibited by galactose and several analogs and galactosides, but not by glucose. Lactose uptake activity observed in lactose-grown cells was very reduced in cells grown on glucose or galactose. Glucose repressed the induction of lactase, but not the metabolic system for galactose utilization. In continuous culture on lactose medium at dilution rates below 0.2 h-1 the specific lactase activity was higher than in batch cultures and decreased with increases in dilution rate. Lactase was induced by pulses of lactose and galactose in cells growing on glucose, but only at low dilution rates were the steady-state concentration of glucose was very low.
Effects of Polyenes, Detergents, and Other Potential Membrane Perturbants on an Osmotolerant Yeast,
Saccharomyces rouxii
Authors: Arnold Wilfred N. , Johnson Brenda P.
Published: January 2020

The osmotolerance of
Saccharomyces rouxii
48-28 was confirmed with both NaCl- and KCl-fortified growth media, with more tolerance being exhibited for the potassium salt. Washed and buffered cells from unfortified medium were challenged with a variety of compounds (and also with physical treatments) that potentially would elicit membrane perturbations. The efficacy of these brief treatments was judged primarily by monitoring subsequent viability. Change in the degree of expression of β-fructofuranosidase (EC 3.2.1.26), which is cryptic in young cells of
S. rouxii
, was a second criterion. There was a linear correlation between cell death and enzyme expression for treatments with polyenes, detergents, some organic solvents which did not denature the enzyme, and various freeze-thaw regimens in graded amounts of glycerol. The species is relatively insensitive to polyene antimycotics, the order of decreasing effect being filipin, nystatin, and amphotericin B.
S. rouxii
was found to be less sensitive to osmotic shock than is
Saccharomyces cerevisiae
, but in neither species is β-fructofuranosidase released to the medium. The sensitivity of
S. rouxii
to ionic detergents, but not to nonionic detergents, was rationalized as being due to cell wall discrimination against larger micelles for the nonionic examples. This was confirmed by showing that protoplasts were sensitive to both classes. In cultures older than 5 days the normal agreement between colony-forming units and methylene blue exclusion (another test of viability) no longer held. Delayed fermentation of sucrose by
S. rouxii
, which is a diagnostic feature of the species, is explained by death of some cells, expression of their β-fructofuranosidase, and utilization of the monosaccharides by the surviving cells.
Effect of temperature on spore germination and vegetative cell growth of Clostridium botulinum
Authors: Grecz N , Arvay L H
Published: January 2020

Spore germination and vegetative growth of Clostridium botulinum type E strain VH at 2 to 50 degrees C were studied. At all of these temperatures, germination began immediately after the addition of the spores to the germination medium. Microscopic observations during germination revealed three types of spores: phase bright (ungerminated), phase variable (partially germinated), and phase dark (fully germinated). At all temperatures except 50 degrees C, there was a pronounced lag between the initial appearance of phase-variable spores and their eventual conversion to phase-dark spores. The number of partially germinated spores increased steadily, reaching 40 to 60% by 18 to 21 h of incubation. During this time, phase-dark, fully germinated spores developed slowly and did not exceed 28% in any of the samples. At 18 to 26 h of incubation, the rate of full germination increased abruptly four-fold. There was extensive and relatively rapid germination at 2 degrees C, the lowest temperature tested, yielding about 60% phase-variable spores by 18 h, which became phase-dark by 26 h of incubation. The optimum temperature for partial and full germination was consistently 9 degrees C. Germination at 50 degrees C was exceptionally rapid and was completed within 1 to 2 h, although 40% remained phase bright. Vegetative cells showed detectable growth at 6 to 41 degrees C, with a distinct optimum at 32.5 degrees C. No growth occurred at 50 degrees C, and only marginal growth was observed at 6 to 14 degrees C. The psychrophilic nature of the germination process coupled with the cold tolerance of vegetative growth appears to give C. botulinum type E an advantage in cold climates as well as in cold-stored foods.
Purification and Properties of a Malolactic Enzyme from a Strain of
Leuconostoc mesenteroides
Isolated from Grapes
Authors: Lonvaud-Funel A. , de Saad A. M. Strasser
Published: January 2020

An enzymatic complex able to transform
l
-malate to
l
-lactate was obtained from a
Leuconostoc mesenteroides
strain isolated from grapes. The molecular weight was about 235,000, the isoelectric point was at pH 4.35, and the optimal pH for activity was 5.75. The malolactic activity followed a sequential pattern concerning the involved substrates. At pH values substantially different from the optimum, a positive cooperativity between malate molecules was observed. Oxamate, fructose-1, 6-diphosphate, and
l
-lactate acted as noncompetitive inhibitors, whereas succinate, citrate, and tartrate isomers produced a competitive inhibition.
Effect of UV light disinfection on antibiotic-resistant coliforms in wastewater effluents
Authors: Meckes M C
Published: January 2020

Total coliforms and total coliforms resistant to streptomycin, tetracycline, or chloramphenicol were isolated from filtered activated sludge effluents before and after UV light irradiation. Although the UV irradiation effectively disinfected the wastewater effluent, the percentage of the total surviving coliform population resistant to tetracycline or chloramphenicol was significantly higher than the percentage of the total coliform population resistant to those antibiotics before UV irradiation. This finding was attributed to the mechanism of R-factor-mediated resistance to tetracycline. No significant difference was noted for the percentage of the surviving total coliform population resistant to streptomycin before or after UV irradiation. Multiple drug resistance patterns of 300 total coliform isolates revealed that 82% were resistant to two or more antibiotics. Furthermore, 46% of these isolates were capable of transferring antibiotic resistance to a sensitive strain of Escherichia coli.
Evaluation of coliphage detection as a rapid indicator of water quality
Authors: Wentsel R S , O'Neill P E , Kitchens J F
Published: January 2020

A rapid coliphage analysis technique for enumerating coliphages in natural waters has been evaluated by water quality laboratories located throughout the United States. Correlations were established between coliphages and coliforms in natural water systems. These correlations were highly significant. This relationship can thus be used to determine the number of fecal or total coliforms present in natural water samples based on an enumeration of coliphages. With this method, coliphages in natural water systems (containing greater than or equal to six coliphages per 100 ml) can be enumerated within 6 h.
Differences Among Cowpea Rhizobia in Tolerance to High Temperature and Desiccation in Soil
Authors: Osa-Afiana L. O. , Alexander Martin
Published: January 2020

Strains of cowpea rhizobia grew in mannitol-amended, nonsterile soil at 29 to 35°C but not at 40°C. Little decline in numbers of these bacteria occurred in dry, nonsterile soil incubated at 42°C for 7 days. Strains of cowpea rhizobia differed widely in their tolerances to drying at 30°C in nonsterile and sterile soil, and from less than 1 to 50% of the bacteria were still viable after 11 days. No relation was evident between tolerance to desiccation and the degree of aridity of the site from which the bacteria were isolated or their growth rates in culture, but strains not producing extracellular polysaccharide were often more tolerant than those producing extracellular polysaccharide. It is suggested that desiccation-tolerant rhizobia be used for the production of legume inoculants.
Distribution of Methanogenic and Sulfate-Reducing Bacteria in Near-Shore Marine Sediments
Authors: Hines Mark E. , Buck John D.
Published: January 2020

The distribution of methanogenic and sulfate-reducing bacteria was examined in sediments from three sites off the coast of eastern Connecticut and five sites in Long Island Sound. Both bacterial groups were detected at all sites. Three distributional patterns were observed: (i) four sites exhibited methanogenic and sulfate-reducing populations which were restricted to the upper 10 to 20 cm, with a predominance of sulfate reducers; (ii) three sites in western Long Island Sound exhibited a methanogenic population most abundant in sediments deeper than those occupied by sulfate reducers; (iii) at one site that was influenced by fresh groundwater, methanogens and sulfate reducers were numerous within the same depths; however, the number of sulfate reducers varied vertically and temporally with sulfate concentrations. It was concluded that the distributions of abundant methanogenic and sulfate-reducing bacteria were mutually exclusive. Methanogenic enrichments yielded all genera of methanogens except
Methanosarcina
, with the methanobacteria predominating.
Rapid Screen for Bacteria Degrading Water-Insoluble, Solid Hydrocarbons on Agar Plates
Authors: Kiyohara Hohzoh , Nagao Kazutaka , Yana Keiji
Published: January 2020

A rapid procedure was devised for detecting on solid media bacteria able to degrade water-insoluble, solid hydrocarbons such as the polycyclic aromatic hydrocarbons phenanthrene, anthracene, and biphenyl. After
Alcaligenes faecalis
AFK2 was inoculated on a plate containing mineral salts agar, an ethereal solution of phenanthrene (about 10%, wt/vol) was sprayed on the surface of the plate, and the plate was incubated at 30°C for 2 to 3 days. Colonies showing degradation were surrounded with clear zones on the opaque plate. A similar clear zone also was formed around colonies which had been grown on a succinate-mineral salts agar or nutrient agar, followed by spraying of the ethereal solution of phenanthrene and further incubating for 1 day. Other phenanthrene-assimilating bacteria, including
Beijerinckia
Bwt and
Pseudomonas
SPM64, also formed clear zones on phenanthrene-covered agar plates. This method was applicable to detection of bacteria able to assimilate anthracene, naphthalene, and biphenyl.
Methanogenesis in Big Soda Lake, Nevada: an Alkaline, Moderately Hypersaline Desert Lake
Authors: Oremland Ronald S. , Marsh Lorraine , DesMarais David J.
Published: January 2020

Incubated sediment slurries from Big Soda Lake, Nevada, produced significant levels of CH
4
, and production was inhibited by 2-bromoethanesulfonic acid and by autoclaving. Methane production was stimulated by methanol, trimethylamine, and, to a lesser extent, methionine. Surprisingly, hydrogen, acetate, and formate amendments provided only slight or no stimulation of methanogenesis. Methane production by sediment slurries had a pH optimum of 9.7. A methanol-grown enrichment culture containing a small, epifluorescent coccus as the predominant organism was recovered from sediments. The enrichment grew best when FeS or autoclaved sediment particles were included in the media, had a pH optimum of 9.7, and produced
14
CH
4
from
14
CH
3
OH. The methane formed by methanolgrown enrichment cultures was depleted in
13
C by 72 to 77‰ relative to the methanol.
Use of Epifluorescence Microscopy in Studies of the Germination and Recovery of Thermoactinomycetes
Authors: Attwell R. W. , Colwell R. R.
Published: January 2020

Spore germination and growth of thermoactinomycetes were observed by epifluorescence microscopy. Each of the principal stages in germination was recognized and found to correspond to changes in phase-contrast appearance commonly monitored during endospore germination. The effects of novobiocin and nalidixic acid on germination of
Thermoactinomyces vulgaris
and
T. thalpophilus
were studied by using epifluorescence microscopy. Outgrowth but not initiation was inhibited by 100 μg of nalidixic acid per ml and 50 μg of novobiocin per ml. When each of the compounds, at various concentrations, was incorporated into a medium for thermoactinomycete recovery, the antibiotics were found to inhibit colony development. Samples of water and sediment incubated in a growth medium containing novobiocin and selective for thermoactinomycete species were examined by epifluorescence microscopy for total numbers of outgrown spores. Direct viable counts of outgrown spores indicated that the standard plate count enumerated less than 10% of the viable population of thermoactinomycetes.
Biosynthesis of radiolabeled verruculogen by Penicillium simplicissimum
Authors: Day J B , Mantle P G
Published: January 2020

In surface culture of Penicillium simplicissimum, verruculogen was shown to be biosynthesized from the intact carbon skeletons of tryptophan and proline, isoprenoid derivatives of mevalonic acid, and a methyl group donated by methionine. Selected radiolabeled precursors (1 mCi) pulse-fed at the optimum stage of fermentation yielded verruculogen (specific activity, 5.89 X 10(2) microCi mmol-1) labeled in the prolyl and isoprenyl regions of the molecule and suitable for metabolic studies.
Production and Loss of Nitric Oxide from Denitrification in Anaerobic Brookston Clay
Authors: McKenney D. J. , Shuttleworth K. F. , Vriesacker J. R. , Findlay W. I.
Published: January 2020

Nitric oxide, nitrous oxide, and nitrite ion production was measured in a Brookston clay column undergoing anaerobic denitrification. A flow system method was used whereby argon carrier gas continuously stripped soil gases from the column, allowing steady-state rates to be obtained. Over several days the temporal change in rates of these gases and NO
2
−
followed a pattern of increase and decay which may be expected of a reaction proceeding by several consecutive steps. The method permits observation of the relatively large net production rate of NO, which is normally not observed in static systems based on head space analysis of gaseous denitrification products. In the first several hours after the onset of anoxic conditions, the net rate of NO production,
f
NO
, increased sharply to a maximum (∼1 × 10
−10
mol of N/g of soil per min), paralleling the rapid increase in NO
2
−
level, and then followed a more gradual decline extending over approximately 45 h. A similar but less pronounced pattern was observed for N
2
O, with net rates of production being considerably less than for NO. The ratio [NO-N]/[N
2
O-N] decreased with time from ∼2.5 at 6 h to ∼2.0 at 45 h. Estimated rates of N
2
production appeared to be initially high, decreased rapidly within a few hours, and then gradually increased with time after the establishment of anaerobic conditions.
Response of Campylobacter jejuni to sodium chloride
Authors: Doyle M P , Roman D J
Published: January 2020

Studies were done to provide more comprehensive information on the response of Campylobacter jejuni and nalidixic acid-resistant, thermophilic Campylobacter (NARTC) to sodium chloride at 4, 25, and 42 degrees C. Three strains of C. jejuni were studies, and all could grow at 42 degrees C in the presence of 1.5% NaCl, but not 2.0% NaCl. At the same temperature, NARTC could grow in 2.0% NaCl and was substantially more tolerant to 2.5 and 4.5% NaCl than was C. jejuni. Both C. jejuni and NARTC grew poorly in the absence of added NaCl and grew best in the presence of 0.5% NaCl at 42 degrees C. At 25 degrees C, NaCl concentrations of 1.0 to 2.5% were protective to NARTC, but the same concentrations of salt generally enhanced the rate of death of C. jejuni. At 4 degrees C, both C. jejuni and NARTC were sensitive to 1.0% or more NaCl; however, the rate of death at this temperature was substantially less than that which occurred at 25 degrees C. A 3 log10 decrease of cells occurred in 4.5% NaCl after 1.2 to 2.1 days at 25 degrees C, and a similar reduction in cells took approximately 2 weeks at the same salt concentration and 4 degrees C. Although C. jejuni grows best in the presence of 0.5% NaCl, the presence of NaCl at concentrations as low as 1.0% may retard growth or increase rate of death; hence, it is advisable that growth media used for recovering or enumerating this organism contain 0.5% NaCl, but not 1.0% or more NaCl.
Transformation of 25-Hydroxycholesterol by
Rhizoctonia muneratii
Authors: Wozny Mary Ellen E. , Smith Tyrone R. , Angus Ralph L. , Kaiser Emil T.
Published: January 2020

Rhizoctonia muneratii
ATCC 13247 was capable of catalyzing the conversion of 25-hydroxycholesterol to the 3-oxo-4-ene. Hydroxylation at the 6α and 6β positions with the concomitant 3-oxo-4-ene transformation was also observed. The addition of Triton X-100 to the growth medium immediately before steroid addition selectively prevented the appearance of the respective 6α-hydroxylated products. The observed conversions were indicative of the utility of microbial transformations in preparing hydroxylated steroids which can be useful for further synthetic modification or for study as pharmacological agents.
Biodegradation of [
14
C]Tri-
p
-Cresyl Phosphate in a Laboratory Activated-Sludge System
Authors: Ku Yuoh , Alvarez George H.
Published: January 2020

Biodegradation of [
14
C]tri-
p
-cresyl phosphate was studied in a laboratory model sewage treatment system to develop information on the nature of its transformation products. In 24-h experiments, 70 to 80% of tri-
p
-cresyl phosphate added at the 1-μg/ml level was degraded. The remaining parent compound was associated with the sludge solids. The major metabolite extracted with ethyl ether from the aqueous phase was identified as
p
-hydroxybenzoic acid by gas chromatography-mass spectrometry. Two unstable ether-extractable metabolites were not identified. The half-life of [
14
C]tri-
p
-cresyl phosphate was estimated to be 7.5 h.