bluuebunny/crossref_metadata_2025 huggingface dataset:
Phenanthrene-degrading phenotype of Alcaligenes faecalis AFK2
Authors: Kiyohara H , Nagao K , Kouno K , Yano K
Published: January 2020

A phenanthrene-degrading bacterium that assimilated a wide range of organic compounds was isolated from a soil sample and identified as Alcaligenes faecalis strain AFK2. The strain degraded phenanthrene through protocatechuate, but did not utilize naphthalene. The phenanthrene-degrading phenotype (Phn+) of AFK2 disappeared after 20 successive subcultures in a mineral salts medium containing o-phthalate or after subculture in nutrient broth containing mitomycin C. The results suggested that the Phn+ phenotype of this strain might be encoded by extrachromosomal genes.
Isolation of
Clostridium thermocellum
Auxotrophs
Authors: Méndez Beatriz S. , Gómez Reinaldo F.
Published: January 2020

Spontaneous and UV irradiation-induced auxotrophic mutants of
Clostridium thermocellum
, an anaerobic cellulolytic thermophile, were isolated after penicillin enrichment in a chemically defined medium.
Moniliformin production and toxicity of different Fusarium species from Southern Africa
Authors: Rabie C J , Marasas W F , Thiel P G , Lübben A , Vleggaar R
Published: January 2020

Four new moniliformin-producing species of Fusarium were found, viz., F. acuminatum, F. concolor, F. equiseti, and F. semitectum. Isolates of F. acuminatum and F. concolor produced large amounts of moniliformin (3.4 and 9.5 g/kg, respectively), whereas isolates of the other three species yielded less than 30 mg/kg. The production of moniliformin by isolates of F. oxysporum and F. avenaceum from southern Africa is described. All 14 toxic isolates of F. oxysporum produced moniliformin. Most isolates of F. fusarioides and all six isolates of Fusarium moniliforme va. subglutinans tested produced moniliformin, as did 28 of 36 toxic isolates of F. moniliforme. A number of F. moniliforme isolates produced greater than 10 g/kg, and one isolate yielded 33.7 g/kg in corn after incubation for 5 weeks at 25 degrees C. Moniliformin production in the field in corn ears was shown by inoculating plants with known moniliformin-producing isolates of three Fusarium species. Yields of up to 645 mg/kg were recorded. Isolates of F. acuminatum, F. equiseti, F. fusarioides, and F. moniliforme were found that were highly toxic to ducklings but which did not produce moniliformin.
Isolation and Characterization of Ultramicrobacteria from a Gulf Coast Estuary
Authors: MacDonell M. T. , Hood Mary A.
Published: January 2020

Viable bacteria were recovered from estuarine waters passed through a 0.2-μm polycarbonate membrane filter. The recovery method included the use of a dilute nutrient broth for primary enrichment followed by conditioning of the organism to a dilute nutrient solid medium. These bacteria were gram-negative rods and coccobacilli having an NaCl requirement and, upon initial culturing, low nutritional requirements. In response to increased nutrient preparations, these microorganisms underwent an increase in size and growth rate, giving rise to visible colonies. Phenotypic characterization suggests that species of
Vibrio, Aeromonas, Pseudomonas
, and
Alcaligenes
were among the isolates. The abundance and the nutritional requirements of these ultramicrobacteria imply that they represent a class of microorganisms which have successfully adjusted to poor nutrient conditions.
Survival of Vibrio cholerae and Escherichia coli in estuarine waters and sediments
Authors: Hood M A , Ness G E
Published: January 2020

In in vitro estuarine water and sediment chambers, the survival of Vibrio cholerae and Escherichia coli was determined by plate counting and direct counting techniques. V. cholerae strains included environmental, clinical, and serotype O1 and non-O1 isolates, whereas E. coli strains included ATCC 25922 and a freshly cultured human isolate. Recovery of V. cholerae varied significantly with incubation temperature. Growth and extended periods of survival occurred in sterile sediments, sterile waters, and nonsterile waters, but not in nonsterile sediments. In contrast to V. cholerae, viable cells of E. coli decreased rapidly in both sterile and nonsterile estuarine waters. Direct counts revealed that E. coli cells were intact in the estuarine water, but attempts to resuscitate them were unsuccessful. The data suggest that V. cholerae survives better in estuarine waters than E. coli. The results may explain the recent observations that V. cholerae levels do not correlate well with fecal coliform concentrations in estuarine waters. Furthermore, the results add increasing evidence to support the theory that V. cholerae is an autochthonous bacterium in estuaries.
Ozone inactivation of cell-associated viruses
Authors: Emerson M A , Sproul O J , Buck C E
Published: January 2020

The inactivation of HEp-2 cell-associated poliovirus (Sabin 1) and coxsackievirus A9 was investigated in three experimental systems, using ozone as a disinfectant. The cell-associated viral samples were adjusted to a turbidity of 5 nephelometric turbidity units. The cell-associated poliovirus and coxsackievirus samples demonstrated survival in a continuous-flow ozonation system at applied ozone dosages of 4.06 and 4.68 mg/liter, respectively, for 30 s. Unassociated viral controls were inactivated by the application of 0.081 mg of ozone per liter for 10 s. Ultrasonic treatment of cell-associated enteric viruses did not increase inactivation of the cell-associated viruses. The batch reactor with a declining ozone residual did not effect total inactivation of either cell-associated enteric virus. These cell-associated viruses were completely inactivated after exposure to ozone in a batch reactor using continuous ozonation. Inactivation of cell-associated poliovirus required a 2-min contact period with an applied ozone dosage of 6.82 mg/liter and a residual ozone concentration of 4.70 mg/liter, whereas the coxsackievirus was completely inactivated after a 5-min exposure to an applied ozone dosage of 4.81 mg/liter with an ozone residual of 2.18 mg/liter. These data indicate that viruses associated with cells or cell fragments are protected from inactivation by ozone concentrations that readily inactivate purified virus. The cell-associated viral samples used in this research contained particles that were 10 to 15 microns in size. Use of a filtration system before ozonation would remove these particles, thereby facilitating inactivation of any remaining viruses associated with cellular fragments.
Survival of Escherichia coli in lake bottom sediment
Authors: LaLiberte P , Grimes D J
Published: January 2020

The survival of Escherichia coli in bottom sediment (Lake Onalaska, navigation pool no. 7, Mississippi River) was studied by using in situ dialysis culture of sterile (autoclaved) and unsterile sediment samples. Bags made from dialysis tubing were filled with either course sand sediment (28.8% fine) or organic, silty clay sediment (77.2% fine) and placed at the sediment-water interface. Bags representing sterile controls, unsterile uninoculated controls, autoclaved inoculated sediment, and unsterile inoculated sediment were studied during a 5-day period for each sediment type. Daily most-probable-number determinations indicated that E. coli populations in unsterile inoculated sediment fluctuated between 5.3 X 10(2) and 2.2 X 10(3) bacteria per g of silty clay and between 3.0 X 10(3) and 1.4 X 10(4) bacteria per g of sand. Autoclaved silty clay sediment inoculated with 1.0 X 10(6) bacteria per g increased to 2.2 X 10(8) bacteria per g in 3 days. During the same period, autoclaved sand sediment inoculated with 1.2 X 10(5) cells per g increased to 5.4 X 10(7) bacteria per g. By day 5, populations in both cultures had decreased by 1 log. The ability of E. coli to survive for several days in aquatic sediment in situ suggests that fecal coliforms in water may not always indicate recent fecal contamination of that water but rather resuspension of viable sediment-bound bacteria.
Phytate hydrolysis by germfree and conventional rats
Authors: Wise A , Gilburt D J
Published: January 2020

Phytic acid is naturally occurring compound that reduces intestinal absorption of many metals. Early work suggests that some dietary phytate may be hydrolyzed in the large intestines by bacteria, but more recently nutritionists have suggested that a mucosal enzyme is responsible. This paper reports a study intended to resolve this controversy. The hydrolysis of dietary phytic acid was measured in germfree and conventional rats fed either of two diets that differed in their calcium content. Negligible phytate hydrolysis occurred in the germfree rats, whereas 22 and 56% of the phytic acid was hydrolyzed by conventional rats fed high- and low-calcium diets, respectively. We concluded that bacteria were responsible for the hydrolysis of phytate in these diets and that any activity of endogenous enzyme was negligible.
Relative Efficacy of Different Alfalfa Cultivar-
Rhizobium meliloti
Strain Combinations for Symbiotic Nitrogen Fixation
Authors: Miller R. W. , Sirois J. C.
Published: January 2020

Five
Rhizobium meliloti
isolates known to have different capabilities for expression of nitrogenase activity under symbiotic conditions were used to inoculate four representative
Medicago sativa
cultivars under aseptic conditions. Nitrogenase activities and respiratory activity were measured for whole plants and excised nodules. Dry weights and nodule numbers were also recorded after 4 weeks of growth in plastic pouches on a nitrogen-free nutrient medium. Hydrogen evolution and acetylene reduction rates were used to calculate the fraction of reducing power allocated to dinitrogen reduction. Although the efficiency of the system defined in this way was poorly correlated with plant yield, a very high linear correlation was obtained between yield and the algebraic product of nitrogenase activity and efficiency. High correlation (
r
> 0.78) was obtained between respiration and nitrogenase activity for whole plants as well as for excised nodules. Nodular respiration accounted for between 10 and 20% of the total plant dark respiration. The four test cultivars exhibited significantly different symbiotic responses to the inocula, although trends in potential for expression of the nitrogenase system by the five
R. meliloti
strains were evident. There was significant interaction between the host plant and symbiont in determining nitrogenase activity and yield. This screening method allows quantitative discrimination between effective and ineffective host-inoculum combinations.
Production and Vertical Flux of Attached Bacteria in the Hudson River Plume of the New York Bight as Studied with Floating Sediment Traps
Authors: Ducklow Hugh W. , Kirchman David L. , Rowe Gilbert T.
Published: January 2020

We investigated the growth and vertical flux of attached bacteria with floating sediment traps in the Hudson River Plume of the New York Bight during the spring diatom blooms. Traps were floated at the base of the mixed layer (ca. 10 m) for 1-day periods. After recovery, we measured bacterial abundance and rates of [
methyl
-
3
H]thymidine incorporation in the trap samples. The vertical flux of attached bacteria was estimated with a model formulated to distinguish between bacterial accumulation in traps due to in situ growth and that due to vertical flux. Attached bacterial flux ranged from 0.6 × 10
11
to 2.0 × 10
11
cells m
−2
day
−1
, and attached bacterial settling rates of 0.1 to 1.0 m day
−1
were observed during periods of vertical particulate organic carbon flux ranging from 254 to 1,267 mg of C m
−2
day
−1
. In situ growth of bacteria in sediment traps was unimportant as a source of bacterial increase when compared with vertical flux during our study. The vertical flux of attached bacteria removed 3 to 67% of the total daily bacterial production from the water column. Particulate organic carbon is not significantly mineralized by attached bacteria during its descent to the sea floor in the plume area during this period, when water temperature and grazing rates are at their annual minima.
Sequential utilization of mixed monosaccharides by yeasts
Authors: Hsiao H Y , Chiang L C , Ueng P P , Tsao G T
Published: January 2020

Four yeasts (Saccharomyces cerevisiae, Schizosaccharomyces pombe, Candida utilus, and Rhodotorula toruloides) were tested for their ability to grow and consume D-glucose, D-xylose, D-xylulose, and D-xylitol. Sequential utilization of substrates was observed when D-glucose as mixed with D-xylulose as the carbon source. Catabolite inhibition was tentatively concluded to be responsible for this regulatory mechanism. D-Glucose was also found to inhibit the utilization of D-xylose and D-xylitol in C. utilus and R. toruloides. D-Xylose, D-xylitol, and D-xylulose were consumed simultaneously by R. toruloides and C. utilus.
Dissimilatory Reduction of NO
2
−
to NH
4
+
and N
2
O by a Soil
Citrobacter
sp
Authors: Smith M. Scott
Published: January 2020

Dissimilatory reduction of NO
2
−
to N
2
O and NH
4
+
by a soil
Citrobacter
sp. was studied in an attempt to elucidate the physiological and ecological significance of N
2
O production by this mechanism. In batch cultures with defined media, NO
2
−
reduction to NH
4
+
was favored by high glucose and low NO
3
−
concentrations. Nitrous oxide production was greatest at high glucose and intermediate NO
3
−
concentrations. With succinate as the energy source, little or no NO
2
−
was reduced to NH
4
+
but N
2
O was produced. Resting cell suspensions reduced NO
2
−
simultaneously to N
2
O and free extracellular NH
4
+
. Chloramphenicol prevented the induction of N
2
O-producing activity. The

K
m

for NO
2
−
reduction to N
2
O was estimated to be 0.9 mM NO
2
−
, yet the apparent

K
m

for overall NO
2
−
reduction was considerably lower, no greater than 0.04 mM NO
2
−
. Activities for N
2
O and NH
4
+
production increased markedly after depletion of NO
3
−
from the media. Amendment with NO
3
−
inhibited N
2
O and NH
4
+
production by molybdate-grown cells but not by tungstate-grown cells. Sulfite inhibited production of NH
4
+
but not of N
2
O. In a related experiment, three
Escherichia coli
mutants lacking NADH-dependent nitrite reductase produced N
2
O at rates equal to the wild type. These observations suggest that N
2
O is produced enzymatically but not by the same enzyme system responsible for dissimilatory reduction of NO
2
−
to NH
4
+
.
Uptake of Cyclic AMP by Natural Populations of Marine Bacteria
Authors: Ammerman James W. , Azam Farooq
Published: January 2020

The major objective of this study was to describe the mechanism(s) of cyclic AMP uptake by natural populations of marine bacteria. A second objective was to determine whether this uptake could contribute to the intracellular regulatory pool of cyclic AMP. Using high-specific-activity
32
P-labeled cyclic AMP, we found several high-affinity uptake systems. The highest-affinity system had a half-saturation constant of <10 pM. This system was extremely specific for cyclic nucleotides, particularly cyclic AMP. It appeared to meet the criteria for active transport. Uptake of cyclic AMP over a wide concentration range (up to 2 μM) showed multiphasic kinetics, with half-saturation constants of 1 nM and greater. These lower-affinity systems were much less specific for cyclic nucleotides. Although much of the labeled cyclic AMP taken up by the high-affinity systems was metabolized, some remained as intact cyclic AMP within the cells during 1 h of incubation. This suggests that at least some of the bacteria use cyclic AMP dissolved in seawater to augment their intracellular pools.
Enzyme immunoassay for detection of Salmonellae in foods
Authors: Minnich S A , Hartman P A , Heimsch R C
Published: January 2020

An enzyme immunoassay was developed to detect Salmonella in foods. Indirect test protocols were developed for use with microtitration plates or Gilford microcuvettes. Samples from enrichment cultures were mixed with H-specific immunoglobulin G and allowed to react; unbound antibody was removed by three 5-min centrifugation washes; goat anti-rabbit antibody conjugated to alkaline phosphatase was added and allowed to react; and unbound conjugate was removed by centrifugation washing as before. Salmonella-positive samples were indicated by the production of a chromogenic reaction product after the addition of alkaline phosphatase substrate. The color could be read visually or quantified by absorbance. Ninety-eight food samples were examined to compare the enzyme immunoassay with enrichment serology, immunofluorescence, and the Food and Drug Administration pure culture technique. The enzyme immunoassay was sensitive and specific, and it possessed advantages over methods currently in use. Furthermore, when the enzyme immunoassay was used to screen preenrichment media, the results indicated that it might be decidedly more sensitive than the conventional pure culture technique.
Changes in cell wall carbohydrate composition of Paecilomyces persicinus P-10 M1 during growth and cephalosporin C production
Authors: Malowitz R , Pisano M A
Published: January 2020

The carbohydrate composition of the cell walls of Paecilomyces persicinus P-10 M1 was monitored daily for 6 days to detect any changes during growth and cephalosporin C production. Walls were isolated after mechanical breakage, sonication, and exposure to detergent. Major quantitative changes in cell wall carbohydrate composition accompanied a decrease in both cell weight and antibiotic production. Glucosamine content remained relatively constant in the 24- to 96-h cell walls and increased markedly in the 120- and 144-h preparations. The non-nitrogenous carbohydrate cell wall component, however, decreased significantly in the 48- and 120-h cell walls. Gas-liquid chromatographic analysis of the non-nitrogenous carbohydrate cell well fraction revealed the presence of glucose, the major component, mannose, galactose, and minute quantities of arabinose. Except for glucose, which was found to decrease moderately in the 120- and 144-h cell walls, the neutral sugars did not vary significantly with time.
Use of Hoechst Dyes 33258 and 33342 for Enumeration of Attached and Planktonic Bacteria
Authors: Paul John H.
Published: January 2020

The DNA-specific fluorochromes Hoechst 33258 and 33342 were used to enumerate aquatic bacteria by epifluorescent direct counts. Cultures of estuarine bacteria gave identical counts when stained with Hoechst 33258 or acridine orange, whereas natural populations of aquatic bacteria gave 92 to 98.5% of the acridine orange counts. The technique had distinct advantages over acridine orange when enumerating bacteria on surfaces which bind acridine orange, such as polystyrene.
Simple method for quantitation of viable mycoplasmas
Authors: Albers A C , Fletcher R D
Published: January 2020

A rapid, simple, and inexpensive method for quantitation of viable mycoplasmas is described. Serial dilutions were made in sterile microtiter plates with standard microtiter equipment. The results were multiplied by a factor of 2.38 to obtain colony-forming units comparable to those obtained with the laborious glass pipette-tube dilution method.
Tetrazolium Reduction-Malachite Green Method for Assessing the Viability of Filamentous Bacteria in Activated Sludge
Authors: Bitton Gabriel , Koopman Ben
Published: January 2020

A method was developed to assess the activity of filamentous bacteria in activated sludge. It involves the incubation of activated sludge with 2(
p
-iodophenyl)-3-(
p
-nitrophenyl)-5-phenyl tetrazolium chloride followed by staining with malachite green. Both cells and 2(
p
-iodophenyl)-3-(
p
-nitrophenyl)-5-phenyl tetrazolium chloride-formazan crystals can be observed in prepared specimens by using bright-field microscopy. This procedure allowed us to distinguish between inactive and actively metabolizing filaments after chlorine application to control the bulking of activated sludge.
Sorption of Cadmium by Microorganisms in Competition with Other Soil Constituents
Authors: Kurek Ewa , Czaban Janusz , Bollag Jean-Marc
Published: January 2020

The fate of cadmium in soil is influenced to a great extent by microbial activity. Microorganisms were compared with abiotic soil components for their ability to sorb Cd from a liquid medium. When the same amount (on a dry weight basis) of bacterial cells (
Serratia marcescens
and
Paracoccus
sp.), clay (montmorillonite), or sand was separately incubated in 0.05 M phosphate buffer, pH 7.2, containing 10 ppm of Cd (10 μg/ml), bacterial cells removed the largest quantity of Cd. Dead cells sorbed much more Cd from the medium than live cells. A comparative study of Cd removal from the medium by seven soil bacteria and four fungi did not indicate appreciable differences. With increasing microbial biomass, the relative efficiency of 0.1 M NaOH as an extractant of sorbed Cd increased, whereas the extraction efficiency of 0.005 M DTPA (diethylenetriaminepentaacetic acid) decreased. It appeared that NaOH and DTPA extracted different chemical forms of Cd. This assumption was supported by vastly different correlation coefficients in the relative amount of Cd extracted by the two solvents.
Production of 2-Keto-
l
-Gulonic Acid from
d
-Glucose by Two-Stage Fermentation
Authors: Sonoyama Takayasu , Tani Hiroyoshi , Matsuda Katsuhiro , Kageyama Bunji , Tanimoto Masahiro , Kobayashi Kobei , Yagi Shigeo , Kyotani Hisashi , Mitsushima Kenji
Published: January 2020

A practical method for the production of calcium 2-keto-
l
-gulonate (an intermediate in the Reichstein synthesis of
l
-ascorbic acid) from
d
-glucose has been established by using a two-stage fermentation system.
d
-Glucose was first converted to calcium 2,5-diketo-
d
-gluconate by a mutant strain of
Erwinia
sp. in a medium containing
d
-glucose, corn steep liquor, (NH
4
)
2
HPO
4
, and CaCO
3
. After a 26-h cultivation, 328.6 mg of calcium 2,5-diketo-
d
-gluconate per ml was obtained, with a 94.5% yield from
d
-glucose. This broth was used directly for the next conversion without removal of cells by treatment with sodium dodecyl sulfate. The stereospecific reduction of calcium 2,5-diketo-
d
-gluconate to calcium 2-keto-
l
-gulonate was performed with a mutant strain of
Corynebacterium
sp. When the cell growth reached a maximum (about 16 h) in a medium containing
d
-glucose, corn steep liquor, NaNO
3
, KH
2
PO
4
, and trace elements, NaNO
3
was added to the culture, and then the calcium 2,5-diketo-
d
-gluconate broth was fed over a period of about 50 h. Since the mutant strain requires a hydrogen donor for reduction, the calcium 2,5-diketo-
d
-gluconate broth was mixed with
d
-glucose before being fed. The results of four two-stage fermentations in 10-m
3
conventional fermentors showed that an average of 106.3 mg of calcium 2-keto-
l
-gulonate per ml was obtained, with a 84.6% yield from
d
-glucose, the starting material of calcium 2,5-diketo-
d
-gluconate production. Calcium 2-keto-
l
-gulonate was stable in the broth. Neither 2-keto-
d
-gluconic acid nor 5-keto-
d
-gluconic acid was detected in the final broth.
Agar-Like Polysaccharide Produced by a
Pseudomonas
Species: Production and Basic Properties
Authors: Kang Kenneth S. , Veeder George T. , Mirrasoul Peter J. , Kaneko Tatsuo , Cottrell Ian W.
Published: January 2020

A new species of
Pseudomonas
was isolated that produced copious amounts of an exocellular heteropolysaccharide (PS-60) after incubation for 3 days at 30°C in media containing 3% glucose as a carbon source. The polysaccharide was composed of approximately 46% glucose and 30% rhamnose and, in addition, contained 21% uronic acid and 3%
O
-acetyl. Upon deacetylation by a mild alkaline treatment, PS-60 produced a brittle, firm, and optically clear gel. This gelling property was thermoreversible. The PS-60 gel exhibited excellent heat stability that withstood autoclaving (i.e., 121°C for 15 min) for several cycles. The gel strength, melting point, and setting point of the polysaccharide were controlled primarily by the concentration of cations. PS-60 was not affected by a variety of enzymes. The results of tests involving various culture media and biochemical test media indicate that PS-60 is an excellent alternative gelling agent to agar.
Salmonella spp. in the working environment of sewage treatment plants in Oslo, Norway
Authors: Langeland G
Published: January 2020

The presence of Salmonella spp. was investigated at three sewage treatment plants in Oslo, Norway. Salmonella bacteria were isolated from floor surfaces and areas with hand contact in the treatment plant, from floor surfaces and areas with hand contact in the treatment plant, from floor surfaces in the changing rooms, and in one case from floor surfaces in an eating room. The sewage sludge contained from 140 to 140,000 Salmonella spp. per 100 g dry weight. Raw and treated sewage contained an average of 130 and 3 of these bacteria per 100 ml, respectively. There was poor correlation between the pattern of serotypes isolated from the sewage works and the patterns of those which were registered among the population of Oslo during the investigation. Neither enteropathogenic bacteria nor parasite eggs were found in fecal samples from employees at the plant. The health significance of the presence of Salmonella spp. in the environment of sewage workers is discussed.
Purification of Poly-β-Hydroxybutyrate by Density Gradient Centrifugation in Sodium Bromide
Authors: Nickerson Kenneth W.
Published: January 2020

Fractionation of fully sporulated cultures of
Bacillus thuringiensis
by density gradient centrifugation in NaBr produced two bands which were identified as poly-β-hydroxybutyrate. This technique generated high yields of membrane-bound and unbound granules of exceptional purity and degree of polymerization.
Microbial Production of 2,3-Butylene Glycol from Cheese Whey
Authors: Speckman R. A. , Collins E. B.
Published: January 2020

Six microorganisms that produced acetoin or diacetyl or both from glucose were tested for the production of 2,3-butylene glycol from lactose.
Bacillus polymyxa
and
Streptococcus faecalis
gave positive results and were tested in unmodified wheys. Cottage cheese whey was unsatisfactory, but
B. polymyxa
produced large amounts of the glycol in sweet whey, about 60 mmol of glycol per 100 mmol of lactose utilized. Aeration and an increased ratio of surface area to volume of whey enhanced the production of glycol. 2,3-Butylene was separated from the spent whey and from acetoin and diacetyl with a Sephadex G-10 column.
Survival of Salmonella adelaide and fecal coliforms in coarse sands of the swan costal plain, Western Australia
Authors: Parker W F , Mee B J
Published: January 2020

The survival of Salmonella adelaide and fecal coliforms in two coarse sands influenced by two sources of septic tank effluent was studied. The experiments were conducted in conditions that reflected the soil environment beneath functioning septic tank systems. Significant differences in survival were found with different effluent sources. In one experiment the survival of S. adelaide was similar to that of fecal coliforms; in the other it was not. The nonuniform, multiphasic nature of survival curves was variability observed in these experiments suggests that the application of such survival data for establishing management criteria for septic tank systems--by, for example, the use of soil moisture characteristic curves to give estimates of movement in the soil--is inappropriate.
Enterotoxin production in milk at 22 and 4 degrees C by Escherichia coli and Yersinia enterocolitica
Authors: Olsvik O , Kapperud G
Published: January 2020

Enterotoxigenic Escherichia coli (five strains) and Yersinia enterocolitica (five strains) were cultivated in sterile milk at 22 and 4 degrees C. The bacteria grew well at both temperatures. Three strains of E. coli produced heat-labile enterotoxin in the milk at 22 degrees C as demonstrated by enzyme-linked immunosorbent assay. Heat-stable enterotoxins were not detected in milk by the infant mouse test.
Microbiological examination of sebeel water
Authors: Hammad Z H , Dirar H A
Published: January 2020

Water samples from clay storage jugs ("zeers") located in homes and at public watering stands ("sebeels") at streets, mosques, and schools were examined. Coliforms, fecal coliforms, and fecal streptococci were detected in 100, 69, 88, and 91.56% of the samples, respectively. The general microbiology of the water and some factors affecting microbial load were studied. The predominant bacterial genera of sebeel water were found to be Staphylococcus. Aerococcus, Micrococcus, Streptococcus, Bacillus, Listeria, Lactobacillus, and Arthrobacter. A simple modification of zeer construction was suggested to help improve sanitation.
Prophage Curing in
Lactobacillus casei
by Isolation of a Thermoinducible Mutant
Authors: Shimizu-Kadota Mariko , Sakurai Toshizo
Published: January 2020

To eliminate the occurrence of virulent phage in industrial fermentation, attempts were made to obtain prophage-cured derivatives from
Lactobacillus casei
lysogenic strain S-1. A thermoinducible mutant lysogen was isolated from mutagenized strain S-1, since S-1 cannot be induced under laboratory conditions. The mutation responsible for thermoinducibility was located on the prophage. Prophage-cured strains were selected after heat induction of the mutant. These cured strains did not produce the virulent phage and should be valuable for industrial fermentation.
Field evaluation of the microbial insecticide Bacillus thuringiensis serotype H-14 against floodwater mosquitoes
Authors: Mulla M S , Federici B A , Darwazeh H A , Ede L
Published: January 2020

Four experimental formulations of the microbial insecticide Bacillus thuringiensis var. israelensis (serotype H-14) were evaluated in the field against larvae of the floodwater mosquitoes Aedes nigromaculis and Psorophora columbiae with ground and aerial application methods. The formulations included ABG-6108D (Abbott Laboratories, North Chicago, Ill.), a wettable powder containing about 400 IU/mg, Sandoz 402-WDC (Sadoz, Inc., Homestead, Fla.), a flowable concentrate containing 600 IU/mg, and two wettable powder formulations of Bactimos (Biochem Products, Montchanin, Del.), one with 3,000 IU/mg and the other with 6,000 IU/mg. Trials against both species indicated they were similar in susceptibility to B. thuringiensis var. israelensis (serotype H-14), and that by using ground application methods, populations of second and third instars could be reduced by 83 to 100% with ABG-6108 and Sandoz 402-WDC at 0.56 to 1.12 kg/ha and with Bactimos (6,000 IU/mg) at 0.44 kg/ha. When applied aerially, approximately two to three times the ground rates had to be used to obtain similar population reductions. Fourth instars were difficult to control, requiring approximately 1.5 to 2 times the rates required for the earlier instars to obtain 80 to 100% reductions. However, these rates were not sufficient to obtain adequate control if larvae were late fourth instars.
Decontamination of laboratory microbiological waste by steam sterilization
Authors: Rutala W A , Stiegel M M , Sarubbi F A
Published: January 2020

A steam sterilizer (autoclave) was tested to determine the operating parameters that affected sterilization of microbiological waste. Tests involved standardized loads (5, 10 ad 15 lb [ca. 2.27, 4.54, and 6.80 kg, respectively]) contaminated petri plates in autoclave bags placed in polypropylene or stainless steel containers. Thermal and biological data were obtained by using a digital potentiometer and a biological indicator containing spores of Bacillus stearothermophilus, respectively. The transfer of heat was more efficient when smaller loads of microbiological waste were tested and stainless steel rather than polypropylene containers were used. A single bag with the sides rolled down to expose the top layer of petri plates allowed heat to pass better than did a single bag with the top constricted by a twist-tie. The presence of water in the autoclave bag did not significantly improve heat-up time in stainless steel or polypropylene containers. The results of biological tests substantiated the temperature data. When 10 or 15 lb of microbiological waste was exposed to various test conditions, the only condition that ensured the destruction of B. stearothermophilus involved the use of a stainless steel container (with or without water) for 90 min. Autoclaving for 45 min resulted in the destruction of bacteria included in 10 lb (136 +/- 3 plates) or 15 lb (205 +/- 6 plates) of microbiological waste when stainless steel containers with or without water or polypropylene containers with water used, whereas 60 min was required to kill all bacteria if polypropylene containers without water were used.
Sensitivity of aflatoxin b1 to ionizing radiation
Authors: Van Dyck P J , Tobback P , Feyes M , van de Voorde H
Published: January 2020

Aflatoxin B1 in a 5-micrograms/ml water solution was sensitive to ionizing radiation. Inactivation was assayed by the Ames microsome mutagenicity test and confirmed by thin-layer chromatography. Destruction of aflatoxin B1 had already begun at 2.5 kilograms (kGy; 1 kGy = 0.1 Mrad), but a dose exceeding 10 kGy was necessary for total destruction.
Fluorogenic assays for immediate confirmation of Escherichia coli
Authors: Feng P C , Hartman P A
Published: January 2020

Rapid assays for Escherichia coli were developed by using the compound 4-methylumbelliferone glucuronide (MUG), which is hydrolyzed by glucuronidase to yield a fluorogenic product. The production of glucuronidase was limited to strains of E. coli and some Salmonella and Shigella strains in the family Enterobacteriaceae. For immediate confirmation of the presence of E. coli in most-probable-number tubes, MUG was incorporated into lauryl tryptose broth at a final concentration of 100 micrograms/ml. Results of both the presumptive test (gas production) and the confirmed test (fluorescence) for E. coli were obtained from a variety of food, water, and milk samples after incubation for only 24 h at 35 degrees C. Approximately 90% of the tubes showing both gas production and fluorescence contained fecal coliforms (they were positive in EC broth incubated at 45 degrees C). Few false-positive reactions were observed. The lauryl tryptose broth-MUG-most-probable-number assay was superior to violet red bile agar for the detection of heat- and chlorine-injured E. coli cells. Anaerogenic strains produced positive reactions, and small numbers of E. coli could be detected in the presence of large numbers of competing bacteria. The fluorogenic assay was sensitive and rapid; the presence of one viable cell was detected within 20 h. E. coli colonies could be distinguished from other coliforms on membrane filters and plates of violet red bile agar if MUG was incorporated into the culture media. A rapid confirmatory test for E. coli that is amenable to automation was developed by using microtitration plates filled with a nonselective medium containing MUG. Pure or mixed cultures containing E. coli produced fluorescence within 4 h (most strains) to 24 h (a few weakly positive strains).
Identity and Behavior of Xylem-Residing Bacteria in Rough Lemon Roots of Florida Citrus Trees
Authors: Gardner John M. , Feldman Albert W. , Zablotowicz Robert M.
Published: January 2020

An aseptic vacuum extraction technique was used to obtain xylem fluid from the roots of rough lemon (
Citrus jambhiri
Lush.) rootstock of Florida citrus trees. Bacteria were consistently isolated from vascular fluid of both healthy and young tree decline-affected trees. Thirteen genera of bacteria were found, the most frequently occurring genera being
Pseudomonas
(40%),
Enterobacter
(18%),
Bacillus, Corynebacterium
, and other gram-positive bacteria (16%), and
Serratia
(6%). Xylem bacterial counts fluctuated seasonally. Bacterial populations ranged from 0.1 to 22 per mm
3
of root tissue (about 10
2
to 2 × 10
4
bacteria per g of xylem) when bacterial counts were made on vascular fluid, but these numbers were 10- to 1,000-fold greater when aseptically homogenized xylem tissue was examined similarly. Some of the resident bacteria (4%) are potentially phytopathogenic. It is proposed that xylem bacteria have an important role in the physiology of citrus.
Mutagenicity of anthraquinone and hydroxylated anthraquinones in the Ames/Salmonella microsome system
Authors: Liberman D F , Fink R C , Schaefer F L , Mulcahy R J , Stark A A
Published: January 2020

The mutagenicity of anthracene, anthraquinone, and four structurally similar compounds of each was evaluated in the Ames/Salmonella microsome assay. Anthraquinone was shown to be mutagenic for strains TA1537, TA1538, and TA98 in the absence of rat liver homogenate. The four anthraquinone derivatives tested were mutagenic for TA1537 exclusively. None of the anthracenes exhibited mutagenic activity.
Sampling Design and Enumeration Statistics for Bacteria Extracted from Marine Sediments
Authors: Montagna Paul A.
Published: January 2020

The spatial and temporal distributions of marine bacteria were studied at both a muddy and a sandy subtidal site in North Inlet, S.C. The sampling design was hierarchical, since subsampling (by a dilution series) of the sediments was necessary to count bacterial cells using acridine orange epifluoresence microscopy. The cell count data fit a log-normal distribution. The abundance of bacteria was 10
11
g
−1
(dry weight) of mud and 10
9
g
−1
(dry weight) of sand. Variance component analyses demonstrated that variation due to the subsampling procedures was always statistically significant. Thus the common practice of counting 20 fields from one filter preparation is inadequate for estimating the true bacterial population variance in marine sediments. It is recommended that replication of the subsampling level be performed. Standardization of data (by dry weight of sediment) decreased sampling variance at the mud site but not at the sand site, implying that bacteria are more homogeneously distributed in sand than in mud.
Kinetic Analysis of Competition Between Sulfate Reducers and Methanogens for Hydrogen in Sediments
Authors: Lovley Derek R. , Dwyer Daryl F. , Klug Michael J.
Published: January 2020

The competition between sulfate-reducing and methanogenic bacteria for hydrogen was investigated in eutrophic lake sediments that contained low in situ sulfate concentrations and in sulfate-amended sediments. Sulfate reduction and methane production coexisted in situ in lake surface sediments (0 to 2 cm), but methane production was the dominant terminal process. Addition of 10 to 20 mM sulfate to sediments resulted in a decrease in the hydrogen partial pressure and a concomitant inhibition of methane production over time. Molybdate inhibition of sulfate reduction in sulfate-amended sediments was followed by an increase in the hydrogen partial pressure and the methane production rate to values comparable to those in sediments not amended with sulfate. The sulfate reducer population had a half-saturation constant for hydrogen uptake of 141 pascals versus 597 pascals for the methanogen population. Thus, when sulfate was not limiting, the lower half-saturation constant of sulfate reducers enabled them to inhibit methane production by lowering the hydrogen partial pressure below levels that methanogens could effectively utilize. However, methanogens coexisted with sulfate reducers in the presence of sulfate, and the outcome of competition at any time was a function of the rate of hydrogen production, the relative population sizes, and sulfate availability.
Isolation and characterization of Edwardsiella tarda from fall chinook salmon (Oncorhynchus tshawytscha)
Authors: Amandi A , Hiu S F , Rohovec J S , Fryer J L
Published: January 2020

A new bacterial pathogen of chinook salmon (oncorhynchus tshawytscha) was isolated from fish in Oregon's Rogue River. The bacteria are biochemically and serologically related to strains of Edwardsiella tarda. Initially isolated from chinook salmon, the bacteria were also pathogenic for steelhead and rainbow trout (Salmo gairdneri), and channel catfish (Ictalurus punctatus). The 50% lethal doses for chinook salmon, steelhead trout, and channel catfish injected intraperitoneally and maintained in 18 degrees C water were 4.1 x 10(6), 5.6 x 10(6), and 4.0 x 10(5) respectively. When chinook salmon and rainbow trout were injected intraperitoneally and held in 12 degrees C water, the mean lethal doses were 6.4 x 10(7) and 1.7 x 10(6), respectively. The invasiveness of the organism was low in steelhead trout exposed to the bacteria by the waterborne route. The optimum growth temperature of the bacteria in brain heart infusion broth was approximately 35 degrees C. The guanine plus cytosine content of DNA obtained from E. tarda isolated from salmon was 59 mol%.
Comparative Aspects of Sulfur Mineralization in Sediments of a Eutrophic Lake Basin
Authors: King Gary M. , Klug M. J.
Published: January 2020

The net mineralization of organic sulfur compounds in surface sediments of Wintergreen Lake was estimated from a mass-balance budget of sulfur inputs and sediment sulfur concentrations. The net mineralization of organic sulfur inputs is <50% complete, which is consistent with the dominance of organic sulfur (>80% of total sulfur) in sediment. Although sediment sulfur is predominantly organic, sulfate reduction is the most significant process in terms of the quantities of sulfur transformed in surface sediments. Rates of sulfate reduction in these sediments average 7 mmol/m
2
per day. On an annual basis, this rate is 19-fold greater than net rates of organic sulfur mineralization and 65-fold greater than sulfate ester hydrolysis.
Microcystis aeruginosa toxin: cell culture toxicity, hemolysis, and mutagenicity assays
Authors: Grabow W O , Du Randt W C , Prozesky O W , Scott W E
Published: January 2020

Crude toxin was prepared by lyophilization and extraction of toxic Microcystis aeruginosa from four natural sources and a unicellular laboratory culture. The responses of cultures of liver (Mahlavu and PCL/PRF/5), lung (MRC-5), cervix (HeLa), ovary (CHO-K1), and kidney (BGM, MA-104, and Vero) cell lines to these preparations did not differ significantly from one another, indicating that toxicity was not specific for liver cells. The results of a trypan blue staining test showed that the toxin disrupted cell membrane permeability within a few minutes. Human, mouse, rat, sheep, and Muscovy duck erythrocytes were also lysed within a few minutes. Hemolysis was temperature dependent, and the reaction seemed to follow first-order kinetics. Escherichia coli, Streptococcus faecalis, and Tetrahymena pyriformis were not significantly affected by the toxin. The toxin yielded negative results in Ames/Salmonella mutagenicity assays. Microtiter cell culture, trypan blue, and hemolysis assays for Microcystis toxin are described. The effect of the toxin on mammalian cell cultures was characterized by extensive disintegration of cells and was distinguishable from the effects of E. coli enterotoxin, toxic chemicals, and pesticides. A possible reason for the acute lethal effect of Microcystis toxin, based on cytolytic activity, is discussed.
Solvent Production and Morphological Changes in
Clostridium acetobutylicum
Authors: Jones D. T. , van der Westhuizen A. , Long S. , Allcock E. R. , Reid S. J. , Woods D. R.
Published: January 2020

The morphological and cytological changes which occurred in
Clostridium acetobutylicum
P262 during the production of acetone, butanol, and ethanol in an industrial fermentation medium were identified and correlated with the growth and physiological changes. The swollen, cigar-shaped clostridial forms were involved in the conversion of acids to neutral solvents, and there was a correlation between the number of clostridial forms and the production of solvents. Sporulation mutants which were unable to form clostridial stages (
cls
mutants) did not produce solvents. Oligosporogenous mutants which showed reduced clostridial stage formation produced intermediate levels of solvents. Sporulation mutants blocked after the clostridial stage, which were unable to form mature spores (
spo
mutants), produced normal levels of solvents.
Fermentation of Cellulose to Methane and Carbon Dioxide by a Rumen Anaerobic Fungus in a Triculture with
Methanobrevibacter
sp. Strain RA1 and
Methanosarcina barkeri
Authors: Mountfort Douglas O. , Asher Rodney A. , Bauchop Thomas
Published: January 2020

The fermentation of cellulose by a rumen anaerobic fungus in the presence of
Methanobrevibacter
sp. strain RA1 and
Methanosarcina barkeri
strain 227 resulted in the formation of 2 mol each of methane and carbon dioxide per mol of hexose fermented. Coculture of the fungus with either
Methanobrevibacter
sp. or
M. barkeri
produced 0.6 and 1.3 mol of methane per mol of hexose, respectively. Acetate, formate, ethanol, hydrogen, and lactate, which are major end products of cellulose fermentation by the fungus alone, were either absent or present in very low quantities at the end of the triculture fermentation (≤0.08 mol per mol of hexose fermented). During the time course of cellulose fermentation by the triculture, hydrogen was not detected (<1 × 10
−5
atm; <0.001 kPa) and only acetate exhibited transitory accumulation; the maximum was equivalent to 1.4 mol per mol of hexose at 6 days which was higher than the total acetate yield of 0.73 in the fungus monoculture. The effect of methanogens is interpreted as a shift in the flow of electrons away from the formation of electron sink products lactate and ethanol to methane via hydrogen, favoring an increase in acetate, which is in turn converted to methane and carbon dioxide by
M. barkeri
. The maximum rate of cellulose degradation in the triculture (3 mg/ml per day) was faster than previously reported for bacterial cocultures and within 16 days degradation was complete. The triculture was used successfully also in the production of methane from cellulose in the plant fibrous materials, sisal (fiber from leaves of
Agave sisalona
L.) and barley straw leaf.
Accumulation of Amino Acids in
Rhizobium
sp. Strain WR1001 in Response to Sodium Chloride Salinity
Authors: Hua Sui-Sheng T. , Tsai Victor Y. , Lichens Georgia M. , Noma Amy T.
Published: January 2020

Rhizobium
sp. strain WR1001, isolated from the Sonoran Desert by Eskew and Ting, was found to be able to grow in defined medium containing NaCl up to 500 mM, a concentration approaching that of sea water. Therefore, it is a valuable strain for studying the biochemical basis of salt tolerance. Intracellular free glutamate was found to increase rapidly in response to osmotic stress by NaCl. It accounted for 88% of the amino acid pool when the bacterium was grown in 500 mM NaCl. The role of glutamate dehydrogenase in glutamate biosynthesis was examined in several
Rhizobium
strains. Both NADH- and NADPH-dependent glutamate dehydrogenase activities in various
Rhizobium
strains were observed. The range of activity differed considerably depending on the particular strain. KCl (500 mM) did not stimulate glutamate dehydrogenase activity, as reported in a number of bacterial strains by Measures. The low activity of glutamate dehydrogenase in
Rhizobium
sp. strain WR1001 apparently cannot fulfill a biosynthetic function of glutamate formation in response to medium NaCl concentrations.