bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of temperature and relative humidity on biological indicators used for ethylene oxide sterilization
Authors: Oxborrow G S , Placencia A M , Danielson J W
Published: January 2020

A study was made to determine the effects of temperature and moisture on the D-value of a common biological indicator. Relative humidity (RH) was varied between 10 and 70% in increments of 10%, and temperature was varied between 30 and 70 degrees C in increments of 10 degrees C. Temperature was found to have a pronounced effect on the D-value. At 60% RH, the D-value varied from 15.0 min at 30 degrees C to 1.1 min at 70 degrees C. When RH was plotted against the average D-value at the various temperatures, the temperature curves at or above 50 degrees C were more erratic and the RH had a significant effect. The study showed that temperature and RH must be controlled if biological indicators are to be properly calibrated for use in ethylene oxide sterilization.
Simple screening method for molds producing intracellular mycotoxins in pure cultures
Authors: Filtenborg O , Frisvad J C , Svendsen J A
Published: January 2020

A simple screening method for molds producing the intracellular mycotoxins brevianamide A, citreoviridin, cyclopiazonic acid, luteoskyrin, penitrem A, roquefortine C, sterigmatocystin, verruculogen, viomellein, and xanthomegnin was developed. After removing an agar plug from the mold culture, the mycelium on the plug is wetted with a drop of methanol-chloroform (1:2). By this treatment the intracellular mycotoxins are extracted within seconds and transferred directly to a thin-layer chromatography plate by immediately placing the plug on the plate while the mycelium is still wet. After removal of the plug, known thin-layer chromatographic procedures are carried out. The substrate (Czapek yeast autolysate agar) and growth conditions (25 degrees C for 7 days) used by Penicillium taxonomists proved suitable for the production of the mycotoxins investigated when 60 known toxigenic isolates and 865 cultures isolated from foods and feedstuffs were tested with this screening method.
Frequency distribution of coliforms in water distribution systems
Authors: Christian R R , Pipes W O
Published: January 2020

Nine small water distribution systems were sampled intensively to determine the patterns of dispersion of coliforms. The frequency distributions of confirmed coliform counts were compatible with either the negative-binomial or the lognormal distribution. They were not compatible with either the Poisson or Poisson-plus-added zeroes distribution. The implications of the use of the lognormal distributional model were further evaluated because of its previous use in water quality studies. The geometric means from 14 data sets ranged from 10(-6) to 0.2 coliforms per 100 ml, and the geometric standard deviations were between 10 and 100, with one exception. If the lognormal model is representative of the coliform distribution; the arithmetic mean sample count is a poor estimator of the true mean coliform density, and the probability of water in a distribution system containing small patches with large coliform densities without detection by routine monitoring is finite. These conclusions have direct bearing on the interpretation of microbiological quality standards for drinking water.
Microbial Transformations of Natural Antitumor Agents: Products of Rotenone and Dihydrorotenone Transformation by
Cunninghamella blakesleeana
Authors: Sariaslani F. Sima , Rosazza J. P.
Published: January 2020

Various species of
Absidia, Aspergillus, Cunninghamella, Trichothecium, Penicillium
, and
Phanerochaete
were found to transform rotenone to one or more metabolites. Two biotransformation products were isolated from a preparative-scale incubation of rotenone with
Cunninghamella blakesleeana
and identified as 1′,2′-dihydro-1′,2′-dihydroxyrotenone and 3′-hydroxyrotenone (amorphigenin). The catalytic reduction of the isopropylene side chain of rotenone resulted in the formation of 1′,2′-dihydrorotenone. The latter was transformed by
C. blakesleeana
to 2′-hydroxy-1′,2′-dihydrorotenone.
Effects of soil moisture and temperature on preharvest invasion of peanuts by the Aspergillus flavus group and subsequent aflatoxin development
Authors: Hill R A , Blankenship P D , Cole R J , Sanders T H
Published: January 2020

Four soil temperature and moisture treatment regimens were imposed on Florunner peanuts 94 days after planting in experimental plots in 1980. At harvest (145 days after planting), the incidence of the Aspergillus flavus group and the aflatoxin concentration were greatest in damaged kernels. Extensive colonization of sound mature kernels (SMK) by the A. flavus group occurred with the drought stress treatment (56% kernels colonized); colonization was less in the irrigated plot (7%) and the drought stress plot with cooled soil (11%) and was intermediate in the irrigated plot with heated soil (26%). Aflatoxin was virtually absent from SMK with the last three treatments, but it was found at an average concentration of 244 ppb (ng/g) in drought-stressed SMK. Colonization of SMK by the A. flavus group and aflatoxin production were greater with hot dry conditions. Neither elevated temperature alone nor drought stress alone caused aflatoxin contamination in SMK. When the ratio of SMK colonized by A. flavus compared with A. niger was greater than 19:1, there was aflatoxin contamination, but there was none if this ratio was less than 9:1. Irrigation caused a higher incidence of A. niger than drought did. This may have prevented the aflatoxin contamination of undamaged peanuts.
Tn
5
-Induced Mutations in the Enterobacterial Phytopathogen
Erwinia chrysanthemi
Authors: Chatterjee Arun K. , Thurn Kerry K. , Feese Dorothy A.
Published: January 2020

Escherichia coli
(2492/pJB4JI) matings with
Erwinia chrysanthemi
produced kanamycin resistant (Km
r
) transconjugants, a majority of which were gentamicin sensitive (Gm
s
). A small proportion (about 0.8%) of the Km
r
Gm
s
clones were either auxotrophic or failed to catabolize galacturonate (Gtu
−
). The R plasmid (pJB4JI) DNA was detected in the parent
E. coli
strain and in a Km
r
Gm
r
transconjugant, but not in Km
r
Gm
s
E. chrysanthemi
strains carrying Tn
5
-induced mutations. In Hfr crosses, Km
r
(Tn
5
) was found linked with most mutations. A majority (>95%) of prototrophic recombinants were Km
s
, except for Leu
+
and Arg
+
recombinants which were 30 to 50% Km
s
. Spontaneous revertants were obtained for all markers except
car, gtu, lys, thr
, and
trp.
Prototrophic revertants, with the exception of Met
+
, Leu
+
, or His
+
clones, were Km
s
. We conclude from both genetic and physical data that Tn
5
transposed from pJB4JI into different sites on the chromosome of
E. chrysanthemi.
In Vitro Survey of
Autographa californica
Nuclear Polyhedrosis Virus Interaction with Nontarget Vertebrate Host Cells
Authors: Volkman Loy E. , Goldsmith Phyllis A.
Published: January 2020

Thirty-five nontarget host cell lines, 23 of human and 12 of nonhuman vertebrate origin, were exposed to
Autographa californica
nuclear polyhedrosis virus preparations derived from four different sources: polyhedra, hemolymph, cell culture medium, and cultured cells. The virus and cells were incubated together at two different temperatures, 28 or 37°C, for four different lengths of time, 16, 40, 64, or 168 h, and the cells were assayed for the presence of virus by a peroxidase-antiperoxidase detection method. The estimated sensitivity of the assay as routinely conducted was 0.98 ng of alkali-liberated viral protein and 1.95 ng of budded viral protein per mm
2
. No evidence of frank replication was obtained in any of the 35 cell lines tested, although virus uptake appeared to be quite common. Virus uptake was confirmed in some cases by electron microscopy. The degree of virus uptake appeared to be dependent on cell type, time and temperature of incubation, and viral phenotype. Virus purified from polyhedra was generally taken up more readily than were the other forms tested.
Diagenesis of Metals Chemically Complexed to Bacteria: Laboratory Formation of Metal Phosphates, Sulfides, and Organic Condensates in Artificial Sediments
Authors: Beveridge T. J. , Meloche J. D. , Fyfe W. S. , Murray R. G. E.
Published: January 2020

Cells of
Bacillus subtilis
, when suspended in a 5mM metal solution, bind metals tenaciously to their cell walls. These metal-loaded cells, when mixed with a synthetic sediment and put under laboratory conditions to simulate low-temperature sediment diagenesis, nucleate the formation of a mixed assemblage of crystalline metal phosphates, metal sulfides, and polymeric, metal-complexed, organic residues. The sequential series of diagenetic events leading to the formation of authigenic mineral phases was followed by transmission electron microscopy and energy-dispersive X-ray analysis. The minerals quartz (SiO
2
) and calcite (CaCO
3
) were employed in the synthetic sediment. Crystalline magnetite (Fe
2
O
3
) and elemental sulfur were added as redox buffering agents to ensure anoxic conditions. Quartz and magnetite appeared unreactive throughout the experimental conditions. Elemental sulfur interacted with the metal-loaded cells, affected both the eventual chemistry and crystal habit of the metal phosphates, and formed a variety of crystalline metal sulfides. Calcite raised the pH of the fluid phase of the sediment, which influenced phosphate mineralization and inhibited metal sulfide genesis.
Clostridium botulinum
Type A Growth and Toxin Production in Media and Process Cheese Spread
Authors: Briozzo Jorge , de Lagarde Ethel Amato , Chirife Jorge , Parada José L.
Published: January 2020

We found that
Clostridium botulinum
type A grew well and produced toxin in media with a water activity (a
w
) of 0.972 or 0.965 and a pH of 5.7, but no growth or toxin production was observed at or below an a
w
of 0.949 during incubation at 30°C for 52 to 59 days. a
w
and pH values of media were adjusted to those of cheese spreads commercially produced. Solutes used to adjust a
w
included combinations of NaCl, cheese whey powder, emulsifying salt, sodium tripolyphosphate, and glycerol. In agreement with results obtained for media, toxin was produced in samples of cheese spread (a
w
, 0.970; pH, 5.7) at 30 to 70 days of incubation at 30°C.
Acetone, Isopropanol, and Butanol Production by
Clostridium beijerinckii
(syn.
Clostridium butylicum
) and
Clostridium aurantibutyricum
Authors: George H. A. , Johnson J. L. , Moore W. E. C. , Holdeman L. V. , Chen J. S.
Published: January 2020

Thirty-four strains representing 15 species of anaerobic bacteria were screened for acetone, isopropanol, and
n
-butanol (solvent) production. Under our culture conditions, several strains of
Clostridium beijerinckii
and
C. aurantibutyricum
produced at least 40 mM
n
-butanol (
C. acetobutylicum
strains produced up to 41 mM
n
-butanol under similar conditions). Both solvent-producing and non-solvent-producing strains of
C. beijerinckii
have high DNA homology with a reference strain of
C. beijerinckii.
Strains labeled “
Clostridium butylicum
” are phenotypically similar to
C. beijerinckii
and showed at least 78% DNA homology to a reference strain of
C. beijerinckii.
Therefore, these “
C. butylicum
” strains are members of
C. beijerinckii.
An earlier DNA homology study has shown that
C. beijerinckii, C. aurantibutyricum
, and
C. acetobutylicum
are distinct species.
Reduced Sulfur in Ashes and Slags from the Gasification of Coals: Availability for Chemical and Microbial Oxidation
Authors: Strayer Richard F. , Davis Edward C.
Published: January 2020

This study was initiated to determine if reduced sulfur contained in coal gasifier ash and slag was available for microbial and chemical oxidation because eventual large-quantity landfill disposal of these solid wastes is expected. Continuous application of distilled water to a column containing a high-sulfur-content (4% [wt/wt]) gasifier slag yielded leachates with high sulfate levels (1,300 mg of sulfate liter
−1
) and low pH values (4.2). At the end of the experiment, a three-tube most-probable-number analysis indicated that the waste contained 1.3 × 10
7
thiosulfate-oxidizing bacteria per g. Slag samples obtained aseptically from the column produced sulfate under both abiotic and biotic conditions when incubated in a mineral nutrient solution. Both microbial and chemical sulfate syntheses were greatly stimulated by the addition of thiosulfate to the slag-mineral nutrient solution. These results led to a test of microbial versus chemical sulfur oxidation in ashes and slags from five gasification processes. Sulfate production was measured in sterile (autoclaved) and nonsterile suspensions of the solid wastes in a mineral nutrient solution. These ashes and slags varied in sulfur content from 0.3 to 4.0% (wt/wt). Four of these wastes demonstrated both chemical (2.0 to 27 μg of sulfate g
−1
day
−1
) and microbial (3.1 to 114 μg of sulfate g
−1
day
−1
) sulfur oxidation. Obvious relationships between sulfur oxidation rate and either sulfur content or particle size distribution of the wastes were not immediately evident. We conclude that the sulfur contained in all but one waste is available for oxidation to sulfuric acid and that microorganisms play a partial role in this process.
Occurrence of Cyclopiazonic Acid in Peanuts
Authors: Lansden John A. , Davidson James I.
Published: January 2020

Samples of segregation 3 farmer stock peanuts from the 1980 southeastern United States growing season were analyzed for the presence of cyclopiazonic acid and aflatoxins. Cyclopiazonic acid appeared in 21 of 27 loose-shell kernel fractions at a range of 32 to 6,525 μg/kg and in 4 of 21 sound mature kernel fractions at a range of 32 to 130 μg/kg. Aflatoxins were detected in 26 of 27 loose-shell kernel fractions and in 20 of 21 sound mature kernel fractions. Cyclopiazonic acid used at 105 and 210 μg/kg to spike peanut samples was recovered at an average rate of 93.3%, with ranges of 89 to 119 and 166 to 221 μg/kg, respectively. The minimum detection limit on oxalic acid-impregnated silica gel plates was 26 ng.
Levels of Water-Soluble Vitamins in Methanogenic and Non-Methanogenic Bacteria
Authors: Leigh John A.
Published: January 2020

The levels of seven water-soluble vitamins in
Methanobacterium thermoautotrophicum, Methanococcus voltae, Escherichia coli, Bacillus subtilis, Pseudomonas fluorescens
, and
Bacteroides thetaiotaomicron
were compared by using a vitamin-requiring
Leuconostoc
strain. Both methanogens contained levels of folic acid and pantothenic acid which were approximately two orders of magnitude lower than levels in the nonmethanogens.
Methanobacterium thermoautotrophicum
contained levels of thiamine, biotin, nicotinic acid, and pyridoxine which were approximately one order of magnitude lower than levels in the nonmethanogens. The thiamine level in
Methanococcus voltae
was approximately one order of magnitude lower than levels in the nonmethanogens. Only the levels of riboflavin (and nicotinic acid and pyridoxine in
Methanococcus voltae
) were approximately equal in the methanogens and nonmethanogens. Folic acid may have been present in extracts of methanogens merely as a precursor, by-product, or hydrolysis product of methanopterin.
Metabolism of glucose and cellobiose by cellulolytic mesophilic Clostridium sp. strain H10
Authors: Giallo J , Gaudin C , Belaich J P , Petitdemange E , Caillet-Mangin F
Published: January 2020

The metabolism of strain H10, a cellulolytic mesophilic Clostridium sp., was studied on glucose and cellobiose as energy and carbon sources. The main products of fermentation of both sugars were acetate, lactate, and ethanol. At low sugar levels, molar growth yields were better for cellobiose than for glucose. In both cases, an inhibition of growth was observed between 1 and 2 g/liter and a total inhibition after the latter concentration. Inhibition was not the result of low pH due to acid formation; growth under static pH conditions was limited in the same way. On the other hand, acetate and lactate had no inhibitory effect when added at concentrations equal to the final titers. Concomitant with the inhibition of growth was a change in metabolic pathways for sugar concentrations between 1 and 2 g/liter, i.e., the production of lactate was higher. After complete inhibition of growth, an accumulation of carbohydrates which were neither glucose nor cellobiose was observed.
Microbiological Analysis of Rock Cod (
Sebastes
spp.) Stored Under Elevated Carbon Dioxide Atmospheres
Authors: Mokhele Khotso , Johnson Andrew R. , Barrett Ericka , Ogrydziak David M.
Published: January 2020

The numbers and types of microorganisms on fresh rock cod fillets and fillets stored in air or in a modified atmosphere (MA; 80% CO
2
, 20% air) at 4°C were compared. Samples were analyzed after 0, 7, 14, and 21 days of storage. The isolation plates were incubated aerobically, anaerobically, or under MA at 4, 20, or 35°C. After 7 days of storage in air, the fillets were obviously spoiled and had a 3- to 4-log cycle increase in microbial counts. Plate counts increased more slowly on MA-stored fillets. After 21 days, the counts on the latter had increased only 2 log cycles, and the fillets did not seem spoiled. The microbial flora changed greatly during MA storage. Only
Lactobacillus
spp. (70%) and an
Aeromonas
sp.-like isolate (30%) were found on plates incubated aerobically at 4 and 20°C, and only
Lactobacillus
spp. was found on plates incubated aerobically and anaerobically at 35 and at 20°C under MA. Isolation plates incubated at 20°C in air gave the highest counts in the shortest incubation time and the greatest diversity of bacterial types recovered. No
Vibrio parahaemolyticus, Staphylococcus aureus
, or
Clostridium botulinum
type E were isolated from the fresh or MA-stored fillets.
Competition Among
Rhizobium leguminosarum
Strains for Nodulation of Lentils (
Lens esculenta
)
Authors: May Sheila N. , Bohlool B. Ben
Published: January 2020

Thirty-one cultures of
Rhizobium leguminosarum
were screened for effectiveness (C
2
H
2
reduction) on lentils (
Lens esculenta
). Fluorescent antibodies prepared against three of the most effective strains (Hawaii 5-0, Nitragin 92A3, and Nitragin 128A12) exhibited a high degree of strain specificity; the antibodies reacted strongly with their homologous rhizobia in culture and with bacteroids in nodules. They did not cross-react with one another, and only weakly with 5 of the 47 other
R. leguminosarum
cultures tested. In competition studies in the growth chamber, whenever strain Nitragin 92A3 was included in the inoculum mixture, it consistently (but not always significantly,
P
= 0.05) occupied the majority of nodules on all four cultivars used. However, some degree of strain X cultivar interaction was apparent: Hawaii 5-0 was of equal competitiveness (
P
= 0.05) with Nitragin 92A3 on three of the varieties (Commercial, Tekoa, and Benewah), but inferior (
P
= 0.01) on the Chilean variety; Nitragin 92A3 completely dominated (
P
= 0.01) Nitragin 128A12 on all cultivars; and Hawaii 5-0 was of equal competitiveness (
P
= 0.05) to Nitragin 128A12 on the Chilean variety and more competitive (
P
= 0.01) on the commercial variety and less so on the other two varieties. In field experiments, Hawaii 5-0 proved of equal competitiveness (
P
= 0.01) with Nitragin 92A3 in one soil (an Inceptisol) and superior (
P
≤ 0.05) to it in another (an Oxisol). Incidence of double-strain occupancy of nodules varied from 0 to 36% in vermiculite, depending on the strains in the mixture and the host variety, and from 0 to 38% in the field, depending on the strains in the mixture and the soil type. The results suggest a close relationship between the competitiveness of a strain and its occurrence in doubly infected nodules.
Butanol Production by a Butanol-Tolerant Strain of
Clostridium acetobutylicum
in Extruded Corn Broth
Authors: Lin Yun-Long , Blaschek Hans P.
Published: January 2020

By employing serial enrichment, a derivative of
Clostridium acetobutylicum
ATCC 824 was obtained which grew at concentrations of butanol that prevented growth of the wild-type strain. The parent strain demonstrated a negative growth rate at 15 g of butanol/liter, whereas the SA-1 mutant was still able to grow at a rate which was 66% of the uninhibited control. SA-1 produced consistently higher concentrations of butanol (from 5 to 14%) and lower concentrations of acetone (12.5 to 40%) than the wild-type strain in 4 to 20% extruded corn broth (ECB). Although the highest concentration of butanol was produced by SA-1 and the wild-type strain in 14% ECB, the best solvent ratio with respect to optimizing butanol and decreasing acetone occurred between 4 and 8% ECB for SA-1. SA-1 demonstrated higher conversion efficiency to butanol than the wild-type strain at every concentration of ECB tested. Characterization of the wild-type and SA-1 strain in 6% ECB demonstrated the superiority of the latter in terms of growth rate, time of onset of butanol production, carbohydrate utilization, pH resistance, and final butanol concentration in the fermentation broth.
Effects of Iron Starvation on the Physiology of the Cyanobacterium
Agmenellum quadruplicatum
Authors: Hardie L. P. , Balkwill D. L. , Stevens S. E.
Published: January 2020

The effects of iron starvation on the growth and physiology of the unicellular cyanobacterium
Agmenellum quadruplicatum
were studied. Uptake of iron from the medium did not occur at a constant rate. The majority of the iron was removed at two different times, when the cells were initially inoculated into the medium and after the cultures had become quite dense and had stopped growing. Iron became limiting for growth 16 h after transfer to an iron-deficient medium, but cultures retained full viability for at least 212 h. Once iron became limiting,
c
-phycocyanin and chlorophyll
a
were degraded concurrently. This was followed by an accumulation of intracellular glucose in place of the
c
-phycocyanin. Nitrate and nitrite reductase activities were elevated through 50 h, after which they decreased steadily. The photosynthetic unit size also increased through 50 h and then decreased. Once iron was restored to the culture medium, growth resumed. The intracellular pigment levels increased rapidly as the glucose level diminished.
Susceptibilities of Algae and
Legionella pneumophila
to Cooling Tower Biocides
Authors: Soracco Reginald J. , Gill Helen K. , Fliermans Carl B. , Pope Daniel H.
Published: January 2020

Nine algal strains and nine
Legionella pneumophila
strains were tested in laboratory culture for their susceptibility to inhibition by a variety of commercially available microbiocides. The responses ranged from ineffective to effective at 1/100 the manufacturers' recommended pulse doses. Tests were also performed to determine whether the action of the microbiocide was bacteriostatic or bacteriocidal.
Soil Fungicides for Controlling Chytridiaceous Mycoparasites of
Gigaspora margarita
and
Glomus fasciculatum
Authors: Sylvia David M. , Schenck N. C.
Published: January 2020

The percentage of azygospores of
Gigaspora margarita
with zoosporangia of chytridiaceous fungi (CF) was reduced significantly after agitating them in fenaminosulf before incubation in soil. Fenaminosulf did not affect zoosporangia development on chlamydospores of
Glomus fasciculatum.
Metalaxyl and ethazol were not effective against CF on spores of either mycorrhizal fungus. Azygospores of
G. margarita
were treated with fenaminosulf and used as the inoculum for pot cultures. After 19 weeks, the percentage of azygospores containing CF was reduced significantly by this treatment, whereas root colonization and sporulation by the mycorrhizal fungus were unaffected. Pot cultures of
G. margarita
, either drenched with fenaminosulf or not, did not differ in the percentage of azygospores containing CF. However, root colonization and sporulation by the mycorrhizal fungus was temporarily delayed when pots were drenched with fenaminosulf.
Method for Measuring Changes in Surface Tension on Agar
Authors: Weisberg David S. , Dworkin Martin
Published: January 2020

The surface tension of agar surfaces was determined by measuring the contact angles formed by drops of various hydrophobic liquids on the surface and then calculating the composite surface free energy function by solving a series of simultaneous equations derived from these data. This method was used to measure the change in the surface tension of agar produced by the addition of various concentrations of albumin. The resulting curve was typical of the effect of increasing concentrations of surfactants on surface tension. The method was compared with other methods of determining surface tension of solids, and it was concluded that the technique used here provided the most reliable results.
Hypochlorite injury of Clostridium botulinum spores alters germination responses
Authors: Foegeding P M , Busta F F
Published: January 2020

Clostridium botulinum spores were sublethally damaged by exposure to 12 or 28 micrograms of available chlorine per ml for 2 min at 25 degrees C and pH 7.0. The damaging dose was 2.7 x 10(-6) to 3.1 x 10(-6) micrograms of available chlorine per spore. Damage was manifested by a consistent 1.6 to 2.4 log difference between the most probable number enumeration of spores (modified peptone colloid medium) and the colony count (modified peptone yeast extract glucose agar); this did not occur with control spores. Damaged spores could be enumerated by the colony count procedure. Germination responses were measured in several defined and nondefined media. Hypochlorite treatment altered the rate and extent of germination in some of the media. Calcium lactate (9 mM) permitted L-alanine (4.5 mM) germination of hypochlorite-treated spores in a medium containing 12 or 55 mM sodium bicarbonate, 0.8 mM sodium thiosulfate, and 100 mM Tris-hydrochloride (pH 7.0) buffer. Tryptose inhibited L-alanine germination of the spores. Treatments with hypochlorite and with hydrogen peroxide (7%, 25 degrees C, 2 min) caused similar enumeration and germination responses, indicating that the effect was due to a general oxidation phenomenon.
Sporulation of
Clostridium acetobutylicum
P262 in a Defined Medium
Authors: Long Susan , Jones David T. , Woods David R.
Published: January 2020

A defined minimal sporulation medium for
Clostridium acetobutylicum
P262, which produces high levels of solvents, is described. The overall sporulation sequence was similar to that of other endospore-forming bacteria. However, we observed a presporulation stage, during which swollen phase-bright cells which contained large amounts of granulose formed. During sporulation, the initiation of spore coat formation occurred before the onset of cortex formation. Other
Clostridium
strains tested showed marked variations in ability to grow and sporulate in various minimal media.
Transductional construction of a threonine-hyperproducing strain of Serratia marcescens: lack of feedback controls of three aspartokinases and two homoserine dehydrogenases
Authors: Komatsubara S , Kisumi M , Chibata I
Published: January 2020

To construct a threonine-hyperproducing strain of Serratia marcescens Sr41, the six regulatory mutations for three aspartokinases and two homoserine dehydrogenases were combined in a single strain by three transductional crosses. The constructed strain, T-1026, carried the lysC1 mutation leading to lack of feedback inhibition and repression of aspartokinase III, the thrA1(1) mutation desensitizing aspartokinase I to feedback inhibition, the thrA2(1) mutation releasing feedback inhibition of homoserine dehydrogenase I, the two hnr mutations derepressing aspartokinase I and homoserine dehydrogenase I, and the etr-1 mutation derepressing aspartokinase II and homoserine dehydrogenase II. The strain produced ca. 40 mg of threonine per ml of medium containing sucrose and urea. Furthermore, the productivity of strain T-1026 was compared with those of strains devoid of more than one of the six regulatory mutations.
Reductive Dehalogenations of Halobenzoates by Anaerobic Lake Sediment Microorganisms
Authors: Horowitz Amikam , Suflita Joseph M. , Tiedje James M.
Published: January 2020

Methane-producing freshwater lake sediment was found to dehalogenate chloro-, bromo-, and iodobenzoates by a reductive reaction in which the halogen was replaced by a hydrogen atom. The identity of the dehalogenated products was confirmed by mass spectrometry, nuclear magnetic resonance, or cochromatography. Removal of the halogens to produce benzoate was necessary before mineralization to CH
4
+ CO
2
could occur. The dehalogenation occurred after a lag period which lasted from 1 week to more than 6 months, depending on the chemical. Dehalogenation was not observed in the absence of CH
4
production, and it was inhibited by the addition of 20% O
2
. Once sediment was acclimated to halobenzoate dehalogenation, new additions of the halobenzoate were degraded without lag. Acclimation was observed regardless of whether the parent substrates were eventually mineralized to CH
4
+ CO
2
. Sediment acclimated to bromo- and chlorobenzoate degradation generally metabolized bromo- and chlorobenzoates, but sediment acclimated to iodobenzoate degradation only metabolized iodobenzoate. Prior acclimation of sediment to benzoate decomposition did not alter the pattern of dehalogenation, and sediment acclimated to dehalogenation was not concurrently acclimated to benzoate degradation. The presence of this apparent specificity, the lag period, and subsequent acclimation, together with our findings of the absence of dehalogenation in sterile sediments and by sediments previously incubated at ≥39°C, suggests that this reaction was biologically catalyzed. Apparently, a pathway for the reductive dehalogenation of aryl halides is present in anaerobic microorganisms of this methanogenic sediment.
Kinetics of Microbial Dehalogenation of Haloaromatic Substrates in Methanogenic Environments
Authors: Suflita Joseph M. , Robinson Joseph A. , Tiedje James M.
Published: January 2020

The kinetic parameters associated with the microbial dehalogenation of 3-chlorobenzoate, 3,5-dichlorobenzoate, and 4-amino-3,5-dichlorobenzoate were measured in anoxic sediment slurries and in an enriched methanogenic culture grown on 3-chlorobenzoate. The initial dehalogenation of the substrates exhibited Michaelis-Menten kinetics. The apparent

K
m

values for the above substrates ranged from 30 to 67 μM. The pattern of degradation, however, was unusual. The enrichment culture accumulated partially dehalogenated intermediates to 72 and 98% of that possible when incubated with either 3,5-dichloro- or 4-amino-3,5-dichlorobenzoate, respectively, but did not accumulate significant amounts of benzoate when 3-chlorobenzoate was the sole carbon and energy source. The accumulated intermediates were rapidly metabolized only after the parent substrate concentrations were nearly depleted (<5 μM). A sequential Michaelis-Menten model was developed to account for the observed pattern of biodegradation. Using this model, we found that relative differences in the

K
m

and

V
max

parameters for substrate and intermediate dehalogenations alone were insufficient to explain the transitory accumulation of intermediates. However, by inserting a competitive inhibition term, with the primary substrate as the inhibitor, the observed pattern of degradation was simulated. Apparently, the dichlorinated substrates competitively inhibit the dehalogenation of the monochlorinated substrates. Similar kinetic patterns were noted for sediments, although the rates were slower than in the enrichment culture.
Entrainment of Viruses from Septic Tank Leach Fields Through a Shallow, Sandy Soil Aquifer
Authors: Vaughn James M. , Landry Edward F. , Thomas McHarrell Z.
Published: January 2020

A study was conducted which focused on movement of naturally occurring human enteroviruses from a subsurface wastewater disposal system through a shallow aquifer. The potential for significant entrainment of virus particles was evidenced by their recovery at down-gradient distances of 67.05 m and from aquifer depths of 18 m. A significant negative correlation was observed between virus occurrence and the distance from the “septage” (leaching pool) source. Virus occurrence could not be statistically correlated with either total or fecal coliforms, indicating the limitations of current microbial water quality indicators for predicting the virological quality of groundwater.
Radioassay for Hydrogenase Activity in Viable Cells and Documentation of Aerobic Hydrogen-Consuming Bacteria Living in Extreme Environments
Authors: Schink Bernhard , Lupton F. S. , Zeikus J. G.
Published: January 2020

An isotopic tracer assay based on the hydrogenase-dependent formation of tritiated water from tritium gas was developed for in life analysis of microbial hydrogen transformation. This method allowed detection of bacterial hydrogen metabolism in pure cultures or in natural samples obtained from aquatic ecosystems. A differentiation between chemical-biological and aerobic-anaerobic hydrogen metabolism was established by variation of the experimental incubation temperature or by addition of selective inhibitors. Hydrogenase activity was shown to be proportional to the consumption or production of hydrogen by cultures of
Desulfovibrio vulgaris, Clostridium pasteurianum
, and
Methanosarcina barkeri.
This method was applied, in connection with measurements of free hydrogen and most-probable-number enumerations, in aerobic natural source waters to establish the activity and document the ecology of hydrogen-consuming bacteria in extreme acid, thermal, or saline environments. The utility of the assay is based in part on the ability to quantify bacterial hydrogen transformation at natural hydrogen partial pressures, without the use of artificial electron acceptors.
Fermentation of Peptides by
Bacteroides ruminicola
B
1
4
Authors: Russell James B.
Published: January 2020

The maximum growth rate of
Bacteroides ruminicola
B
1
4 was significantly improved when either Trypticase or acetate and C
4
-C
5
fatty acids were added to defined medium containing macrominerals, microminerals, vitamins, hemin, cysteine hydrochloride, and glucose. The organism was unable to grow with peptides as the sole energy source, but growth yields from glucose were significantly improved when Trypticase was added to batch cultures containing basal medium, acetate, and C
4
-C
5
volatile fatty acids. During periods of rapid growth, very little peptide was deaminated to ammonia, but after growth ceased there was a linear increase in ammonia. Fifteen grams of Trypticase per liter resulted in maximum ammonia production. In glucose-limited chemostats, ammonia production from peptides was inversely proportional to the dilution rate, and 87% of the variation in ammonia production could be explained by retention time in the culture vessel. Chemostats receiving Trypticase had higher theoretical maximum growth yields and lower maintenance energy expenditures than similar cultures not receiving peptide. Cells from the Trypticase cultures contained more carbohydrate, and this difference was most evident at rapid dilution rates. When corrections were made for cell composition and the amount of peptides that were fermented, it appeared that peptide carbon skeletons could be used for maintenance energy.
B. ruminicola
B
1
4 was unable to grow on peptides alone because it was unable to utilize peptides at a fast enough rate to meet its maintenance requirement.
Whole-cell bioconversion of vanillin to vanillic acid by Streptomyces viridosporus
Authors: Pometto A L , Crawford D L
Published: January 2020

A two-step batch fermentation-bioconversion of vanillin (4-hydroxy-3-methoxybenzaldehyde) to vanillic acid (4-hydroxy-3-methoxybenzoic acid) was developed, utilizing whole cells of Streptomyces viridosporus T7A. In the first step, cells were grown in a yeast extract-vanillin medium under conditions where cells produced an aromatic aldehyde oxidase. In the second step, vanillin was incubated with the active cells and was quantitatively oxidized to vanillic acid which accumulated in the growth medium. Vanillic acid was readily recovered from the spent medium by a combination of acid precipitation and ether extraction at greater than or equal to 96% molar yield and upon recrystallization from glacial acetic acid was obtained in greater than or equal to 99% purity.
Volatile Fatty Acid Production by the Hindgut Microbiota of Xylophagous Termites
Authors: Odelson David A. , Breznak John A.
Published: January 2020

Acetate dominated the extracellular pool of volatile fatty acids (VFAs) in the hindgut fluid of
Reticulitermes flavipes, Zootermopsis angusticollis
, and
Incisitermes schwarzi
, where it occurred at concentrations of 57.9 to 80.6 mM and accounted for 94 to 98 mol% of all VFAs. Small amounts of C
3
to C
5
VFAs were also observed. Acetate was also the major VFA in hindgut homogenates of
Schedorhinotermes lamanianus, Prorhinotermes simplex, Coptotermes formosanus
, and
Nasutitermes corniger.
Estimates of in situ acetogenesis by the hindgut microbiota of
R. flavipes
(20.2 to 43.3 nmol · termite
−1
· h
−1
) revealed that this activity could support 77 to 100% of the respiratory requirements of the termite (51.6 to 63.6 nmol of O
2
· termite
−1
· h
−1
). This conclusion was buttressed by the demonstration of acetate in
R. flavipes
hemolymph (at 9.0 to 11.6 mM), but not in feces, and by the ability of termite tissues to readily oxidize acetate to CO
2
. About 85% of the acetate produced by the hindgut microbiota was derived from cellulose C; the remainder was derived from hemicellulose C. Selective removal of major groups of microbes from the hindgut of
R. flavipes
indicated that protozoa were primarily responsible for acetogenesis but that bacteria also functioned in this capacity. H
2
and CH
4
were evolved by
R. flavipes
(usually about 0.4 nmol · termite
−1
· h
−1
), but these compounds represented a minor fate of electrons derived from wood dissimilation within
R. flavipes.
A working model is proposed for symbiotic wood polysaccharide degradation in
R. flavipes
, and the possible roles of individual gut microbes, including CO
2
-reducing acetogenic bacteria, are discussed.
Growth characteristics of Saccharomyces rouxii isolated from chocolate syrup
Authors: Restaino L , Bills S , Tscherneff K , Lenovich L M
Published: January 2020

We investigated the growth parameters of Saccharomyces rouxii isolated from spoiled chocolate syrup. The optimum pH range for S. rouxii was 3.5 to 5.5, whereas the minimum and maximum pH values that permitted growth were 1.5 and 10.5, respectively. For cells grown in 0 and 60% sucrose the optimum water activity (aw) values were 0.97 and 0.96, respectively. The optimum temperature for S. rouxii increased with a decreasing aw regardless of whether glucose or sucrose was used as the humectant. The optimum temperatures for S. rouxii were 28 degrees C at an aw of greater than 0.995 and 35 degrees C at an aw of 0.96 to 0.90 in 2 X potato dextrose broth with sucrose. Increasing the sorbate concentration (from 0.03 to 0.10%) caused the growth of S. rouxii to become more inhibited between aws of greater than 0.995 and 0.82. S. rouxii did not grow when the sorbate level was 0.12% (wt/vol). At lower sorbate levels, the effect of sorbate on the growth of S. rouxii depended on the aw level. Lowering the aw enhanced the resistance of S. rouxii to increasing concentrations of potassium sorbate. Permeability and polyol production are discussed with respect to sorbate tolerance of S. rouxii at different aw levels.
Computation of Most Probable Numbers
Authors: Russek Estelle , Colwell Rita R.
Published: January 2020

A rapid computational method for maximum likelihood estimation of most-probable-number values, incorporating a modified Newton-Raphson method, is presented. The method offers a much greater reliability for the most-probable-number estimate of total viable bacteria, i.e., those capable of growth in laboratory media.
Colonization of gnotobiotic mice by Roseburia cecicola, a motile, obligately anaerobic bacterium from murine ceca
Authors: Stanton T B , Savage D C
Published: January 2020

In scrapings of mouse cecal mucosae, motile bacteria outnumbered nonmotile bacteria by a ratio of 2:1. Obligately anaerobic bacteria were obtained from such scrapings through the use of techniques designed for the selective isolation of motile bacteria. One of the isolates, Roseburia cecicola, was rapidly motile in broth by means of 20 to 35 flagella arranged in a fascicle on each cell. R. cecicola cells colonized germfree mice (3 x 10(9) to 1 x 10(10) CFU/g of cecum) within 11 days after the animals were inoculated intragastrically with 2 x 10(8) CFU per mouse. In such monoassociated gnotobiotes, the bacteria were found primarily in the cecum, dispersed in the lumen among particles of digesta, and in the mucus over the epithelial surface. Between 2 and 3 weeks after birth, offspring of monoassociated adult mice were colonized by the bacterium (2 x 10(9) to 1 x 10(10) CFU/g of cecum). These results indicate that R. cecicola is suitable for studies of the ecology of host-associated microorganisms, particularly for investigation of the role of motility and possibly also chemotaxis in bacterial colonization of the mammalian gastrointestinal tract.
Toxicity of
Bacillus thuringiensis
var.
israelensis
Crystals to
Aedes aegypti
Larvae: Carbonate Reversal
Authors: Schnell Danny J. , Nickerson Kenneth W.
Published: January 2020

The toxicity of purified
Bacillus thuringiensis
var.
israelensis
crystals to larvae of
Aedes aegypti
could be reversed 100-fold by levels of K
2
CO
3
as low as 0.15%.
Microbial Activity at the Sediment-Water Interface in Halifax Harbor, Canada
Authors: Novitsky James A.
Published: January 2020

The sediment-water interface in Halifax Harbor supports a microbial population of 6.95 � 10
9
cells per g (dry weight). As determined by the standard technique of suspending subsamples in filtered seawater, the uptake of added glutamic acid by this population is 113.5 ng g (dry weight)
−1
h
−1
. An alternate technique was developed to measure the heterotrophic activity of the interface over longer periods of time, using undisturbed cores with the sediment-water interface intact. Under these conditions, the microbes in the water column and the interface increased exponentially in number, with mean doubling times of 9.6 and 4.5 days, respectively. The uptake of glutamic acid by the microbial population of the interface was determined to be 12.7 ng g (dry weight)
−1
h
−1
, almost an order of magnitude less than the uptake determined by the previous method. This indicates that substrate diffusion and competition for substrate by the microbes in the water column are important factors when considering the heterotrophic activity of the sediment microbial population. After 48 h of incubation, uptake and respiration ceased, probably due to the exhaustion of labeled substrate. Additional substrate added after 48 h of incubation was taken up at a rate similar to that measured after the first addition. It appears that the microbial population of the interface is able to respond quickly and repeatedly to relatively large nutrient additions. After 10 days of incubation, the number of “viable” cells as determined by autoradiography was much smaller than the increase in numbers as determined by direct counts. Apparently a large part of the viable population is unaffected by nutrient addition.
Enhanced Mineral Uptake by
Zea mays
and
Sorghum bicolor
Roots Inoculated with
Azospirillum brasilense
Authors: Lin Willy , Okon Yaacov , Hardy Ralph W. F.
Published: January 2020

Inoculation of corn (
Zea mays
) seeds with
Azospirillum brasilense
strain Cd or Sp 7 significantly enhanced (30 to 50% over controls) the uptake of NO
3
−
, K
+
, and H
2
PO
4
−
into 3- to 4-day- and 2-week-old root segments. No gross changes in root morphology were observed; altered cell arrangement in the outer four or five layers of the cortex was seen in photomicrographs of cross sections of inoculated corn roots. The surface activity involved in ion uptake probably increased, as shown by the darker staining by methylene blue of the affected area. Shoot dry weight increased 20 to 30% in inoculated plants after 3 weeks, presumably by enhancement of mineral uptake. Corn and sorghum plants grown to maturity on limiting nutrients in the greenhouse showed improved growth from inoculation approaching that of plants grown on normal nutrient concentrations. Enhanced ion uptake may be a significant factor in the crop yield enhancement reported for
Azospirillum
inoculation.
Distribution of
Thermus
spp. in Icelandic Hot Springs and a Thermal Gradient
Authors: Kristjansson Jakob K. , Alfredsson Gudni A.
Published: January 2020

The growth range in nature of bacteria belonging to the genus
Thermus
was investigated by sampling 55 different hot springs in Iceland. The springs ranged in temperature from 32 to 99�C, and in pH from 2.1 to 10.1. Viable counts of
Thermus
spp. ranging from 10 to 10
4
CFU/100 ml of spring water were found in 27 of the springs sampled. The temperature range for these bacteria was found to be 55 to 85�C, and the pH range was from about 6.5 to above 10.
Thermus
spp. were found in springs containing up to 1 mM dissolved sulfide and having conductivity up to 2,000 μS/cm. The distribution of
Thermus
spp. in a hot spring thermal gradient was also investigated and found to agree well with the overall distribution in individual springs.
Enzyme immunoassay in which a myeloma protein is used for detection of salmonellae
Authors: Robison B J , Pretzman C I , Mattingly J A
Published: January 2020

An enzyme immunoassay (EIA) in which an immunoglobulin A monoclonal antibody from a myeloma (MOPC 467) is used was developed to detect the presence of Salmonella organisms. This myeloma protein binds to a flagellar determinant of the organisms but is not directed toward the H antigens. Of 100 strains tested, 94% were detectable with this antibody. The EIA, used with MOPC 467, is quick, sensitive, and specific, showing virtually no cross-reactivity to other enteric organisms. Initial screening of antibody reactivity was performed by Ouchterlony gel diffusion with the supernatants of heat-treated Salmonella cultures. After this, an EIA was performed on the heat extracts with the myeloma protein, which had been directly coupled to alkaline phosphatase. A positive reaction was indicated by the production of a yellow color after the addition of a substrate (p-nitrophenylphosphate), and this was quantitated by determining the absorbance at 405 nm. The EIA proved to be slightly more sensitive than the Ouchterlony analysis. The sensitivity of the EIA is such that as few as 10(6) Salmonella organisms per ml were detected. This concentration was easily obtained after a 24-h preenrichment incubation of the sample. Mixtures of Salmonella strains with a 10 x concentration of Escherichia coli did not prevent detection of the Salmonella strains. This EIA can be successfully used to detect contamination of foods, as it was used to detect the intentional contamination of infant formula in these studies. Indications are that the EIA is sensitive enough to detect Salmonella strains in M broth subcultures taken directly from a preenrichment culture. Testing of samples could thus be completed 36 h after culture initiation, rather than after 96 h, the time currently needed.