bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecological Indicators of Native Rhizobia in Tropical Soils
Authors: Woomer Paul , Singleton Paul W. , Bohlool B. Ben
Published: January 2020

The relationship between environment and abundance of rhizobia was described by determining the populations of root nodule bacteria at 14 diverse sites on the island of Maui. Mean annual rainfall at the sites ranged from 320 to 1,875 mm, elevation from 37 to 1,650 m, and soil pH from 4.6 to 7.9. Four different soil orders were represented in this study: inceptisols, mollisols, ultisols, and an oxisol. The rhizobial populations were determined by plant infection counts of five legumes (
Trifolium repens, Medicago sativa, Vicia sativa, Leucaena leucocephala,
and
Macroptilium atropurpureum
). Populations varied from 1.1 to 4.8 log
10
cells per g of soil. The most frequently occurring rhizobia were
Bradyrhizobium
spp., which were present at 13 of 14 sites with a maximum of 4.8 log
10
cells per g of soil.
Rhizobium trifolii
and
R. leguminosarum
occurred only at higher elevations. The presence of a particular
Rhizobium
or
Bradyrhizobium
sp. was correlated with the occurrence of its appropriate host legume. Total rhizobial populations were significantly correlated with mean annual rainfall, legume cover and shoot biomass, soil temperature, soil pH, and phosphorus retention. Regression models are presented which describe the relationship of legume hosts, soil climate, and soil fertility on native rhizobial populations.
Degradation of polysaccharides and lignin by ruminal bacteria and fungi
Authors: Akin D E , Benner R
Published: January 2020

Bermudagrass (Cynodon dactylon) leaf blades and whole cordgrass (Spartina alterniflora) fiber were evaluated for degradation of cell walls by microbial groups in ruminal fluid. The groups were selected by the addition of antibiotics to the inoculum as follows: (i) whole ruminal fluid (WRF), no antibiotics; (ii) cycloheximide (C) to inhibit fungi, thus showing potential bacterial activity; (iii) streptomycin and penicillin (S,P) to inhibit fiber-degrading bacteria, showing potential fungal activity; (iv) streptomycin, penicillin, and chloramphenicol (S,P,CAM) to inhibit all bacteria including methanogens; (v) streptomycin, penicillin, and cycloheximide (S,P,C) to inhibit all microbial activity as a control; and (vi) autoclaved ruminal fluid (ARF) to inhibit all biological activity as a second control. Scanning electron microscopy of tissue degradation indicated that tissues not giving a positive histological reaction for lignin were more readily degraded. Cordgrass was more highly lignified, with more tissues resisting degradation than in bermudagrass. Patterns of degradation due to treatment resulted in three distinct groups of data based on the extent of fiber or component losses: WRF and C greater than S,P and S,P,CAM greater than S,P,C and ARF. Therefore, bacterial activity was responsible for most of the fiber loss. Fiber degradation by anaerobic fungi was significantly less (P = 0.05). Cupric oxide oxidation of undigested and digested bermudagrass fiber indicated that phenolic constituents differed in their order of resistance to removal or solubilization. Vanillyl and syringyl components of lignin were the most resistant to decomposition, whereas ferulic acid was readily solubilized from fiber in the absence of microbial activity.(ABSTRACT TRUNCATED AT 250 WORDS)
Effects of alkaline hydrogen peroxide treatment on in vitro degradation of cellulosic substrates by mixed ruminal microorganisms and Bacteroides succinogenes S85
Authors: Lewis S M , Montgomery L , Garleb K A , Berger L L , Fahey G C
Published: January 2020

The effects of sodium hydroxide (NaOH) and alkaline hydrogen peroxide (AHP) treatments on wheat straw (WS) and various cellulosic substrates were determined by measuring susceptibility to degradation by mixed ruminal organisms or Bacteroides succinogenes S85. In vitro incubations were used to measure differences in fermentation resulting from each successive step in the AHP treatment process. In vitro incubations through 48 or 108 h were conducted to measure these differences. The AHP treatment of WS increased (P less than 0.05) dry matter, neutral detergent fiber, and acid detergent fiber degradation over control WS when these substrates were incubated with mixed ruminal microorganisms or B. succinogenes S85. Fermentations containing AHP-treated WS had greater (P less than 0.05) microbial purine (RNA) and volatile fatty acid concentrations by 12 h compared with those containing untreated or NaOH-treated WS. Xylose in AHP-treated WS was utilized more extensively (P less than 0.05) by 12 h compared with the xylose of untreated or NaOH-treated WS. Treatment with AHP removed 23% of the alkali-labile phenolic compounds from WS. When substrates with high levels of crystalline cellulose (raw cotton fiber, Solka floc, and Sigmacell-50) were treated with NaOH or AHP and incubated for 108 h with B. succinogenes S85, extent of acid detergent fiber degradation of cotton fiber and Sigmacell-50 was similar to that of their respective controls. Sodium hydroxide and AHP treatments were effective in increasing acid detergent fiber degradation of the Solka floc which contained, on average, 3.3 and 4.8 percentage units more acid detergent lignin and hemicellulose, respectively, than cotton fiber and Sigmacell-50.(ABSTRACT TRUNCATED AT 250 WORDS)
Extremely Thermophilic Fermentative Archaebacteria of the Genus
Desulfurococcus
from Deep-Sea Hydrothermal Vents
Authors: Jannasch Holger W. , Wirsen Carl O. , Molyneaux Stephen J. , Langworthy Thomas A.
Published: January 2020

Two strains of extremely thermophilic, anaerobic bacteria are described that are representative of isolates obtained from a variety of oceanic hydrothermal vent sites at depths from 2,000 to 3,700 m. The isolates were similar in their requirements for complex organic media, elemental sulfur, and seawater-range salinities (optimum, 2.1 to 2.4%); their high tolerance for sulfide (100 mM) and oxic conditions below growth-range temperatures (50 to 95°C); and their archaebacterial characteristics: absence of murein, presence of certain diand tetraethers, and response to specific antibiotics. The two strains (S and SY, respectively) differed slightly in their optimum growth temperatures (85 and 90°C, optimum pHs for growth (7.5 and 7.0), and DNA base compositions (52.01 and 52.42 G+C mol%). At their in situ pressure of about 250 atm (25,313 kPa), growth rates at 80 and 90°C were about 40% lower than those at 1 atm (101.29 kPa), and no growth occurred at 100 and 110°C, respectively, at either pressure. In yeast extract medium, only 2% of the organic carbon was used and appeared to stem largely from the proteinaceous constituents. According to physiological criteria, the isolates belong to the genus
Desulfurococcus.
Cecal and fecal bacterial flora of the Mongolian gerbil and the chinchilla
Authors: Worthington J M , Fulghum R S
Published: January 2020

The Mongolian gerbil is being increasingly used as a laboratory animal and as a pet. Both chinchillas and gerbils are used as animal models for otitis media and other otic research. Previously, only incomplete information was available regarding the indigenous bacterial flora of the lower intestinal tracts of these coprophagic animals. Using the strict anaerobic methodology of the Virginia Polytechnic Institute Anaerobe Laboratory, we studied the predominant bacterial flora of the cecum and fecal pellets of the gerbil and the chinchilla and the bacterial flora of digesta pellets in the proximal colon. We found species of the following anaerobic genera in high dilutions of gerbil fecal pellets: Bifidobacterium, Clostridium, Propionibacterium, Lactobacillus, and Bacteroides. Only lactobacilli were found in high dilutions of digesta from the upper colon, although the cecum yielded Peptostreptococcus, Bifidobacterium, Clostridium, Lactobacillus, Propionibacterium, and Bacteroides species from high dilutions of cecal contents. The facultatively anaerobic and aerobic flora isolated consisted of species of Bacillus, Streptococcus, Staphylococcus, Acinetobacter, Alcaligenes, Escherichia, Pasteurella, and Pseudomonas plus several unidentifiable organisms. Species of Bifidobacterium, Bacteroides, Eubacterium, and anaerobic Lactobacillus were isolated from chinchillas.
Identification of Moraxella bovis by qualitative genetic transformation and nutritional assays
Authors: Juni E , Heym G A , Newcomb R D
Published: January 2020

Strains of Moraxella bovis were identified definitively through the combined use of a qualitative genetic transformation assay and determination of the ability of the organism under examination to grow in a defined medium (medium MB). Except for weak transformation by DNA from strains of M. lacunata, M. nonliquefaciens, and M. (Branhamella) ovis, DNA samples from all other members of the genus Moraxella failed to transform either of the two M. bovis auxotrophs used in this study.
One-Step Purification of a Lipolytic Enzyme from
Bacillus pumilus
by Mild Hydrophobic Interaction Chromatography on Polyoxyalkylene Glycol-Bound Sepharose 6B
Authors: Mathis Roland , Mourey André , Hubert Patrick
Published: January 2020

An esterase from
Bacillus pumilus
was obtained in a highly purified form, starting from a crude extract, by a new chromatographic technique requiring no detergent during the elution step. The stationary phase involved was mildly hydrophobic and was prepared by covalent immobilization of a polyoxyalkylene glycol onto Sepharose 6B.
Populations of Anaerobic Phototrophic Bacteria in a
Spartina alterniflora
Salt Marsh
Authors: Paterek J. Robert , Paynter M. J. B.
Published: January 2020

Habitat-simulating media were used with the Hungate anaerobic roll tube technique to enumerate culturable anaerobic photosynthetic bacteria in sediment, tidal waters, and
Spartina alterniflora
plant samples collected from the salt marsh at Sapelo Island, Ga. No phototrophs were detected in samples of creekside (low marsh) sediment or in tidal waters in creekside regions. In the high marsh region, 90% of anaerobic phototrophic bacteria occurred in the top 5 mm of sediment and none were detected below 6 mm. There was a seasonal variation, with maximal populations occurring in summer and fall (mean, 4.4 × 10
5
phototrophs g of dry sediment
−1
) and minimal numbers occurring in winter (mean, 3.9 × 10
3
phototrophs g of dry sediment
−1
). During winter and late spring, phototrophs had a patchy distribution over the high marsh sediment surface. In contrast, during late summer they had a random uniform distribution. Tidal water collected over high marsh sediment contained an average of 8.7 × 10
2
phototrophs ml
−1
, with no significant seasonal variation. Anaerobic phototrophic bacteria were also cultured from the lower stem tissue of
S. alterniflora
growing in both the high (4.3 × 10
4
phototrophs g of dry tissue
−1
) and creekside (4.9 × 10
4
phototrophs g of dry tissue
−1
) marsh regions.
Chromatium buderi, Chromatium vinosum, Thiospirillum sanguineum, Rhodospirillum molischianum
, and
Chlorobium phaeobacteroides
were the predominant anaerobic phototrophic species cultured from high marsh sediment. The two
Chromatium
species were dominant.
Steady-State Effects of 2,5,2′,5′-Tetrachlorobiphenyl on Growth, Photosynthesis, and P Uptake in
Selenastrum capricornutum
Authors: Rhee G-Yull , Shane Lana , DeNucci Allan
Published: January 2020

The steady-state effect of 2,5,2′,5′-tetrachlorobiphenyl (TCBP) on the green alga
Selenastrum capricornutum
was investigated in a P-limited two-stage chemostat system. The partition coefficient of this polychlorinated biphenyl congener was 5.9 × 10
4
in steady-state cultures. At a cellular TCBP concentration of 12.2 × 10
−8
ng · cell
−1
, growth rate was not affected. However, photosynthetic capacity (
P
max
) was significantly enhanced by TCBP (56 × 10
−9
μmol of C · cell
−1
· h
−1
versus 34 × 10
−9
μmol of C · cell
−1
· h
−1
in the control). Photosynthetic efficiency, or the slope of the photosynthesis-irradiance curve, was also significantly higher. There was little difference in the cell chlorophyll
a
content, and therefore the difference in these photosynthetic characteristics was the same even when they were expressed on a per-chlorophyll
a
basis. Cell C content was higher in TCBP-containing cells than in TCBP-free cells, but approximately 36% of the C fixed by cells with TCBP was not incorporated as cell C. The maximum P uptake rate was also enhanced by TCBP, but the half-saturation concentration appeared to be unaffected.
Oxidation of substituted phenols by Pseudomonas putida F1 and Pseudomonas sp. strain JS6
Authors: Spain J C , Gibson D T
Published: January 2020

The biodegradation of benzene, toluene, and chlorobenzenes by Pseudomonas putida involves the initial conversion of the parent molecules to cis-dihydrodiols by dioxygenase enzyme systems. The cis-dihydrodiols are then converted to the corresponding catechols by dihydrodiol dehydrogenase enzymes. Pseudomonas sp. strain JS6 uses a similar system for growth on toluene or dichlorobenzenes. We tested the wild-type organisms and a series of mutants for their ability to transform substituted phenols after induction with toluene. When grown on toluene, both wild-type organisms converted methyl-, chloro-, and nitro-substituted phenols to the corresponding catechols. Mutant strains deficient in dihydrodiol dehydrogenase or catechol oxygenase activities also transformed the phenols. Oxidation of phenols was closely correlated with the induction and activity of the toluene dioxygenase enzyme system.
Sub-Parts-Per-Billion Nitrate Method: Use of an N
2
O-Producing Denitrifier to Convert NO
3
−
or
15
NO
3
−
to N
2
O
Authors: Christensen Søren , Tiedje James M.
Published: January 2020

A more sensitive analytical method for NO
3
−
was developed based on the conversion of NO
3
−
to N
2
O by a denitrifier that could not reduce N
2
O further. The improved detectability resulted from the high sensitivity of the
63
Ni electron capture gas chromatographic detector for N
2
O and the purification of the nitrogen afforded by the transformation of the N to a gaseous product with a low atmospheric background. The selected denitrifier quantitatively converted NO
3
−
to N
2
O within 10 min. The optimum measurement range was from 0.5 to 50 ppb (50 μg/liter) of NO
3
−
N, and the detection limit was 0.2 ppb of N. The values measured by the denitrifier method compared well with those measured by the high-pressure liquid chromatographic UV method above 2 ppb of N, which is the detection limit of the latter method. It should be possible to analyze all types of samples for nitrate, except those with inhibiting substances, by this method. To illustrate the use of the denitrifier method, NO
3
−
concentrations of <2 ppb of NO
3
−
N were measured in distilled and deionized purified water samples and in anaerobic lake water samples, but were not detected at the surface of the sediment. The denitrifier method was also used to measure the atom% of
15
N in NO
3
−
. This method avoids the incomplete reduction and contamination of the NO
3
−
-N by the NH
4
+
and N
2
pools which can occur by the conventional method of
15
NO
3
−
analysis. N
2
O-producing denitrifier strains were also used to measure the apparent

K
m

values for NO
3
−
use by these organisms. Analysis of N
2
O production by use of a progress curve yielded

K
m

values of 1.7 and 1.8 μM NO
3
−
for the two denitrifier strains studied.
Bioluminescence Assay for Measuring the Number of Bacteria Adhering to the Hydrocarbon Phase in the BATH Test
Authors: Vanhaecke Erwin , Pijck Jacques
Published: January 2020

A thorough validation of the bacterial adherence to hydrocarbons (BATH) test was performed by means of a bioluminescence assay. Ten different gram-negative strains were subjected to the BATH test. For the calculation of the adhesion index, several factors had to be taken into account: ATP leakage, the action of ATP-hydrolyzing enzymes, the change in the extraction efficiency of Nucleotide-Releasing Reagent for Microbial Cells (NRB; Lumac bv) after vortexing and the difference in light production after the addition of NRB. When the adhesion index values obtained by bioluminescence measurement were used as reference, the total plate count technique appeared to be unreliable in estimating the number of bacteria adhering to the hydrocarbon phase. A highly significant correlation was established, however, between those reference values and the adhesion index values obtained by the optical density reading for octane and especially for hexadecane. With xylene, no correlation was found between the optical density reading values and the total plate count or bioluminescence values.
Microbially Mediated Mn(II) Oxidation in an Oligotrophic Arctic Lake
Authors: Johnston Carl G. , Kipphut George W.
Published: January 2020

Rates of oxidation of Mn(II) were measured by an in situ incubation technique in the water column of Toolik Lake, Alaska. Measured rates were lower than those observed in other aquatic systems but were sufficient to oxidize all Mn(II) in the lake within a 3-month period. Measured rates compared favorably with rates estimated from a previous study of the geochemical cycling of Mn in Toolik Lake. The Mn(II) oxidation was largely microbially mediated, as indicated by inhibition of oxidation rates by sodium azide. Azide had been previously demonstrated to be a suitable microbial poison for studying Mn(II) oxidation in seawater. This study demonstrates that azide is also a suitable poison for freshwaters and that it inhibits microbial but not abiotic oxidation of Mn(II). Manganese(II) oxidation rates were similar during cold, under-ice conditions in early spring and during warmer summer conditions. This observation suggests that Mn(II) concentration, rather than temperature or oxygen concentration, is the most important factor regulating Mn(II) oxidation rates in Toolik Lake.
Factors influencing Clostridium botulinum spore germination, outgrowth, and toxin formation in acidified media
Authors: Wong D M , Young-Perkins K E , Merson R L
Published: January 2020

Clostridium botulinum type A spores were inoculated at a level of 10(7) spores per ml into sterile beef media with protein concentrations of 1, 2, 3, 4, or 6% and acidified to pH values of 2.01 to 4.75 with hydrochloric acid or 4.19 to 4.60 with citric acid. All experimental manipulations, including blending, acidification, inoculation, incubation (30 degrees C), and analyses, were conducted in an anaerobic chamber-incubator in which atmospheric oxygen levels were maintained below 2 ppm (2 microliters/liter). Under these strict anaerobic conditions (oxidation-reduction values in media ranging from -370 to -391 mV), C. botulinum spores were consistently found to germinate, grow, and produce toxin below pH 4.6. The boundary between toxic and atoxic samples in HC1-acidified beef media was mediated by titratable acidity, pH, and protein concentration. A limiting acidity was not established for the citrate-acidified samples; all blends tested (1, 2, 3, and 4% protein and titratable acidities of 0.091 to 0.453%) became toxic within 5 weeks. At the same pH and protein concentration, citric acid was less effective than HC1 in preventing the germination of C. botulinum spores. Higher levels of cell proliferation in the beef protein, as well as enhanced gas production and putrefactive degradation, indicated that beef was a better substrate than soy for C. botulinum spores under these conditions. Reducing the inoculum to 10(4) delayed but did not prevent spore outgrowth and toxin release at pH levels below 4.6.
Hydrogen Partial Pressures in a Thermophilic Acetate-Oxidizing Methanogenic Coculture
Authors: Lee Monica J. , Zinder Stephen H.
Published: January 2020

Hydrogen partial pressures were measured in a thermophilic coculture comprised of a eubacterial rod which oxidized acetate to H
2
and CO
2
and a hydrogenotrophic methanogen,
Methanobacterium
sp. strain THF. Zinder and Koch (S. H. Zinder and M. Koch, Arch. Microbiol. 138:263-272, 1984) originally predicted, on the basis of calculations of Gibbs free energies of reactions, that the H
2
partial pressure near the midpoint of growth of the coculture should be near 4 Pa (ca. 4 × 10
−5
atm; ca. 0.024 μM dissolved H
2
) for both organisms to be able to conserve energy for growth. H
2
partial pressures in the coculture were measured to be between 20 and 50 Pa (0.12 to 0.30 μM) during acetate utilization, approximately one order of magnitude higher than originally predicted. However, when Δ
G

f

(free energy of formation) values were corrected for 60°C by using the relationship Δ
G

f

= Δ
H

f

−
T
Δ
S
(Δ
H

f

is the enthalpy or heat of formation, Δ
S
is the entropy value, and
T
is the temperature in kelvins), the predicted value was near 15 Pa, in closer agreement with the experimentally determined values. The coculture also oxidized ethanol to acetate, a more thermodynamically favorable reaction than oxidation of acetate to CO
2
. During ethanol oxidation, the H
2
partial pressure reached values as high as 200 Pa. Acetate was not used until after the ethanol was consumed and the H
2
partial pressure decreased to 40 to 50 Pa. After acetate utilization, H
2
partial pressures fell to approximately 10 Pa and remained there, indicating a threshold for H
2
utilization by the methanogen. Axenic cultures of the acetate-oxidizing organism were combined with pure cultures of either
Methanobacterium
sp. strain THF or
Methanobacterium thermoautotrophicum
ΔH to form reconstituted acetate-oxidizing cocultures. The H
2
partial pressures measured in both of these reconstituted cocultures were similar to those measured in the original acetate-oxidizing rod coculture. Since
M. thermoautotrophicum
ΔH did not use formate as a substrate, formate is not necessarily involved in interspecies electron transfer in this coculture.
Adaptation of Phytoplankton-Degrading Microbial Communities to Thermal Reactor Effluent in a New Cooling Reservoir
Authors: Schoenberg Steven A. , Benner Ronald , Sobecky Patricia , Hodson Robert E.
Published: January 2020

In water column and sediment inocula from a nuclear reactor cooling reservoir, natural phytoplankton substrate labeled with
14
C was used to determine aerobic and anaerobic mineralization rates for a range of temperatures (25, 40, 55, and 70°C) expected during reactor operation. For experiments that were begun during reactor shutdown, aerobic decomposition occurred at temperatures of <55°C. After 2 months of reactor operation, aerobic rates increased substantially at 55 and 70°C, although maximum rates were observed at temperatures of ≤40°C. The temperature range for which maximum anaerobic mineralization (i.e., the sum of CH
4
and CO
2
) was observed was 25 to 40°C when the reactor was off, expanding to 25 to 55°C during reactor operation. Increased rates at 55°C, but not 70°C, correlated with an increase in the ratio of cumulative methane to carbon dioxide produced over 21 days. When reduced reactor power lowered the maximum temperature of the reservoir to 42°C, aerobic decomposition at 70°C was negligible, but remained substantial at 55°C. Selection for thermophilic decomposers occurred rapidly in this system in both aerobic and anaerobic communities and did not require prolonged exposure to elevated temperatures.
Production and Characteristics of Raw-Potato-Starch-Digesting α-Amylase from
Bacillus subtilis
65
Authors: Hayashida Shinsaku , Teramoto Yuji , Inoue Takehiro
Published: January 2020

A newly isolated bacterium, identified as
Bacillus subtilis
65, was found to produce raw-starch-digesting α-amylase. The electrophoretically homogeneous preparation of enzyme (molecular weight, 68,000) digested and solubilized raw corn starch to glucose and maltose with small amounts of maltooligosaccharides ranging from maltotriose to maltoheptaose. This enzyme was different from other amylases and could digest raw potato starch almost as fast as it could corn starch, but it showed no adsorbability onto any kind of raw starch at any pH. The mixed preparation with
Endomycopsis
glucoamylase synergistically digested raw potato starch to glucose at 30°C. The raw-potato-starch-digesting α-amylase showed strong digestibility to small substrates, which hydrolyzed maltotriose to maltose and glucose, and hydrolyzed
p
-nitrophenyl maltoside to
p
-nitrophenol and maltose, which is different from the capability of bacterial liquefying α-amylase.
Enumeration and isolation of cellulolytic and hemicellulolytic bacteria from human feces
Authors: Wedekind K J , Mansfield H R , Montgomery L
Published: January 2020

The fibrolytic microbiota of the human large intestine was examined to determine the numbers and types of cellulolytic and hemicellulolytic bacteria present. Fecal samples from each of five individuals contained bacteria capable of degrading the hydrated cellulose in spinach and in wheat straw pretreated with alkaline hydrogen peroxide (AHP-WS), whereas degradation of the relatively crystalline cellulose in Whatman no. 1 filter paper (PMC) was detected for only one of the five samples. The mean concentration of cellulolytic bacteria, estimated with AHP-WS as a substrate, was 1.2 X 10(8)/ml of feces. Pure cultures of bacteria isolated on AHP-WS were able to degrade PMC, indicating that interactions with other microbes were primarily responsible for previous low success rates in detecting fecal cellulolytic bacteria with PMC as a substrate. The cellulolytic bacteria included Ruminococcus spp., Clostridium sp., and two unidentified strains. The mean concentration of hemicellulolytic bacteria, estimated with larchwood xylan as a substrate, was 1.8 X 10(10)/ml of feces. The hemicellulose-degrading bacteria included Butyrivibrio sp., Clostridium sp., Bacteroides sp., and two unidentified strains, as well as four of the five cellulolytic strains. This work demonstrates that many humans harbor intestinal cellulolytic bacteria and that a hydrated cellulose source such as AHP-WS is necessary for their consistent detection and isolation.
Monoclonal antibodies which identify a genus-specific Listeria antigen
Authors: Butman B T , Plank M C , Durham R J , Mattingly J A
Published: January 2020

Fifteen murine monoclonal antibodies (MAbs) which react specifically with a protein antigen found in all species of Listeria were developed and characterized. These MAbs were tested extensively by both enzyme-linked immunosorbent assay and Western blot (immunoblot) analyses for cross-reaction with non-Listeria organisms, such as Staphylococcus, Streptococcus, Citrobacter, Pseudomonas, and Salmonella species, and were found to be nonreactive. The genus-specific antigen was identified as a heat-stable protein with a molecular weight in the range of 30,000 to 38,000 (under both reducing and nonreducing conditions), depending on the species of Listeria tested. In Listeria monocytogenes, L. innocua, L. ivanovii, and L. seeligeri the antigen has a molecular weight of approximately 30,000 to 34,000. In L. grayi and L. murrayi it has a molecular weight of approximately 35,000 to 38,000. In addition, several of the MAbs recognize lower-molecular-weight protein bands. There appear to be at least two groups of Listeria-specific MAbs based upon isotype and results of enzyme-linked immunosorbent assay and Western blot analyses. These MAbs have proven to be useful in the development of a diagnostic assay for Listeria species in food products.
Kelthane degradation by genetically engineered Pseudomonas aeruginosa BS827 in a soil ecosystem
Authors: Golovleva L A , Pertsova R N , Boronin A M , Travkin V M , Kozlovsky S A
Published: January 2020

The aim of this study was to study the degradation of kelthane by Pseudomonas aeruginosa BS827, which carried the plasmid pBS3. This plasmid encodes naphthalene oxidation. The strain was able to survive in the presence of kelthane and to retain its degradative ability. Kelthane also stabilized the biodegradative plasmid that was preserved by 70 to 100% of the cell population. Cells deficient in Nah or Sal characters were less effective in degrading kelthane, whereas plasmid-free cells lost this ability completely. Evidently, the degradative activity of P. aeruginosa BS827 was conditioned by plasmid determinants coupled with genes of the plasmid pBS3 Nah region.
Plasmid profile analysis of a salmonellosis outbreak and identification of a restriction and modification system
Authors: Whiley S J , Lanser J A , Manning P A , Murray C , Steele T W
Published: January 2020

After an outbreak of salmonellosis in humans caused by Salmonella typhimurium bacteriophage type 135, 62 isolates from human, animal, and water sources were retained for further analysis. Most of the isolates (92%) could be placed in one of five plasmid pattern groups, with a majority containing a common 60-kilobase plasmid and a smaller 3.8-kilobase-pair plasmid. This small plasmid, pIMVS1, was labeled with [32P]phosphate and used as a probe in subsequent colony and Southern hybridization studies. We concluded that pIMVS1 from isolates obtained from humans was genetically different from plasmids of a similar size found in isolates from chickens. Studies to characterize pIMVS1 were undertaken to determine if it codes for known virulence factors. It did not appear to be associated with the formation of attachment pili or major outer membrane proteins. By using transposon mutagenesis techniques, Tn3(Apr) was inserted into pIMVS1, and the existence of a restriction and modification system was deduced.
Methylcellulose inhibition of exo-beta-1,4-glucanase A from Ruminococcus flavefaciens FD-1
Authors: White B A , Rasmussen M A , Gardner R M
Published: January 2020

A homogeneous preparation of exo-beta-1,4-glucanase A from Ruminococcus flavefaciens FD-1 was competitively inhibited by low concentrations (less than 3 mM) of methylcellulose. The enzyme was also sensitive to the surfactant properties of methylcellulose at high methylcellulose concentrations.
Morphological diversity of ruminal bacteriophages from sheep and cattle
Authors: Klieve A V , Bauchop T
Published: January 2020

Large numbers of bacteriophages (2 x 10(7) to 1 x 10(8)/ml) were present in ruminal fluid from sheep and cattle. Twenty-six distinct types were identified and placed in three morphological groups; several phages possessed unusual structural features. The large numbers and diversity of phages observed indicates a possible role in bacterial lysis and hence in the population dynamics of the ruminal bacteria.
Diazotrophy and Nitrogenase Activity in the Archaebacterium
Methanosarcina barkeri
227
Authors: Lobo Anthony L. , Zinder Stephen H.
Published: January 2020

Nitrogen fixation (diazotrophy) has recently been demonstrated in several methanogenic archaebacteria. To compare the process in an archaebacterium with that in eubacteria, we examined the properties of diazotrophic growth and nitrogenase activity in
Methanosarcina barkeri
227. Growth yields with methanol or acetate as a growth substrate were significantly lower in N
2
-grown cultures than in NH
4
+
-grown cultures, and the culture doubling times were increased, indicating that diazotrophy was energetically costly, as it is in eubacteria. Growth of nitrogen-fixing cells was inhibited when molybdenum was omitted from the medium; addition of 10 nM molybdate stimulated growth, while 1 μM molybdate restored maximum diazotrophic growth. Omission of molybdenum did not inhibit growth of ammonia-grown cells. Tungstate (100 μM) strongly inhibited growth of molybdenum-deficient diazotrophic cells, while ammonia-grown cells were unaffected. The addition of 100 nM vanadate or chromate did not stimulate diazotrophic growth of molybdenum-starved cells. These results are consistent with the presence of a molybdenum-containing nitrogenase in
M. barkeri.
Acetylene, the usual substrate for assaying nitrogenase activity, inhibited methanogenesis by
M. barkeri
and consequently needed to be used at a low partial pressure (0.3% of the headspace) when acetylene reduction by whole cells was assayed. Whole cells reduced 0.3% acetylene to ethylene at a very low rate (1 to 2 nmol h
−1
mg of protein
−1
), and they “switched off” acetylene reduction in response to added ammonia or glutamine. Crude extracts from diazotrophic cells reduced 10% acetylene at a rate of 4 to 5 nmol of C
2
H
4
formed h
−1
mg of protein
−1
when supplied with ATP and reducing power, while extracts of
Klebsiella pneumoniae
prepared by the same procedures had rates 100-fold higher. Acetylene reduction by extracts required ATP and was completely inhibited by 1 mM ADP in the presence of 5 mM ATP. The low rates of C
2
H
2
reduction could be due to improper assay conditions, to switched-off enzyme, or to the nitrogenase's having lower activity towards acetylene than towards dinitrogen.
Enhancement of Butanol Formation by
Clostridium acetobutylicum
in the Presence of Decanol-Oleyl Alcohol Mixed Extractants
Authors: Evans Patrick J. , Wang Henry Y.
Published: January 2020

Extractive fermentation has been proposed to enhance the productivity of fermentations that are end product inhibited. Unfortunately, good extractants for butanol, such as decanol, are toxic to
Clostridium acetobutylicum.
The use of mixed extractants, namely, mixtures of toxic and nontoxic coextractants, was proposed to circumvent this toxicity. Decanol appeared to inhibit butanol formation by
C. acetobutylicum
when present in a mixed extractant that also contained oleyl alcohol. However, maintenance of the pH at 4.5 alleviated the inhibition of butanol production and the consumption of butyrate during solventogenesis. A mixed extractant that contained 20% decanol in oleyl alcohol enhanced butanol formation by 72% under pH-controlled conditions. The production of acetone and acetoin was also increased, even though these two products were not extractable. The enhancement of butanol formation was not limited by the toxicity of decanol. Supplementation of glucose and butyrate in the extractive fermentation yielded a 47% increase in butanol. The enhancement of butanol formation appeared to be dependent on the presence of dissolved decanol in the broth but was not observed unless an organic phase was present to extract butanol. A mechanism for the effects of decanol on product formation is proposed.
Ice Nucleation Activity in Lichens
Authors: Kieft Thomas L.
Published: January 2020

A newly discovered form of biological ice nucleus associated with lichens is described. Ice nucleation spectra of a variety of lichens from the southwestern United States were measured by the drop-freezing method. Several epilithic lichen samples of the genera
Rhizoplaca, Xanthoparmelia
, and
Xanthoria
had nuclei active at temperatures as warm as −2.3°C and had densities of 2.3 × 10
6
to more than 1 × 10
8
nuclei g
−1
at −5°C (2 to 4 orders of magnitude higher than any plants infected with ice nucleation-active bacteria). Most lichens tested had nucleation activity above −8°C. Lichen substrates (rocks, plants, and soil) showed negligible activity above −8°C. Ice nucleation-active bacteria were not isolated from the lichens, and activity was not destroyed by heat (70°C) or sonication, indicating that lichen-associated ice nuclei are nonbacterial in origin and differ chemically from previously described biological ice nuclei. An axenic culture of the lichen fungus
Rhizoplaca chrysoleuca
showed detectable ice nucleation activity at −1.9°C and an ice nucleation density of 4.5 × 10
6
nuclei g
−1
at −5°C. It is hypothesized that these lichens, which are both frost tolerant and dependent on atmospheric moisture, derive benefit in the form of increased moisture deposition as a result of ice nucleation.
Mechanisms of DNA Utilization by Estuarine Microbial Populations
Authors: Paul John H. , DeFlaun Mary F. , Jeffrey Wade H.
Published: January 2020

The mechanisms of utilization of DNA by estuarine microbial populations were investigated by competition experiments and DNA uptake studies. Deoxyribonucleoside monophosphates, thymidine, thymine, and RNA all competed with the uptake of radioactivity from [
3
H]DNA in 4-h incubations. In 15-min incubations, deoxyribonucleoside monophosphates had no effect or stimulated [
3
H]DNA binding, depending on the concentration. The uptake of radioactivity from [
3
H]DNA resulted in little accumulation of trichloroacetic acid-soluble intracellular radioactivity and was inhibited by the DNA synthesis inhibitor novobiocin. Molecular fractionation studies indicated that some radioactivity from [
3
H]DNA appeared in the RNA (10 and 30% at 4 and 24 h, respectively) and protein (approximately 3%) fractions. The ability of estuarine microbial assemblages to transport gene sequences was investigated by plasmid uptake studies, followed by molecular probing. Although plasmid DNA was detected on filters after filtration of plasmid-amended incubations, DNase treatment of filters removed this DNA, indicating that there was little transport of intact gene sequences. These observations led to the following model for DNA utilization by estuarine microbial populations. (i) DNA is rapidly bound to the cell surface and (ii) hydrolyzed by cell-associated and extracellular nonspecific nucleases. (iii) DNA hydrolysis products are transported, and (iv) the products are rapidly salvaged into nucleic acids, with little accumulation into intracellular nucleotide pools.
Mineralization of Trichloroethylene by Heterotrophic Enrichment Cultures
Authors: Fliermans C. B. , Phelps T. J. , Ringelberg D. , Mikell A. T. , White D. C.
Published: January 2020

Microbial consortia capable of aerobically degrading more than 99% of exogenous trichloroethylene (TCE) (50 mg/liter) were collected from TCE-contaminated subsurface sediments and grown in enrichment cultures. TCE at concentrations greater than 300 mg/liter was not degraded, nor was TCE used by the consortia as a sole energy source. Energy sources which permitted growth included tryptone-yeast extract, methanol, methane, and propane. The optimum temperature range for growth and subsequent TCE consumption was 22 to 37°C, and the pH optimum was 7.0 to 8.1. Utilization of TCE occurred only after apparent microbial growth had ceased. The major end products recovered were hydrochloric acid and carbon dioxide. Minor products included dichloroethylene, vinylidine chloride, and, possibly, chloroform.
Selective medium for isolation and enumeration of Bifidobacterium spp
Authors: Muñoa F J , Pares R
Published: January 2020

A new method was developed for the isolation and enumeration of Bifidobacterium spp. from natural aquatic environments. The method was based on the utilization of a new medium, Bifidobacterium iodoacetate medium 25, and resuscitation techniques were used to isolate injured bifidobacteria. The new medium was tested with a nonselective reference medium on sewage and sewage-polluted surface waters. Relatively little colonial growth of any other bacterial genera occurred; when such colonies did grow, Bifidobacterium could be easily differentiated by its colonial morphology or, after Gram staining, by its typical bifidobacterial morphology.
Molecular Cloning and Expression of Cellulase Genes from
Ruminococcus albus
8 in
Escherichia coli
Bacteriophage λ
Authors: Howard Gary T. , White Bryan A.
Published: January 2020

A genomic library of
Ruminococcus albus
8 DNA was constructed by using the
Escherichia coli
bacteriophage λDASH. Recombinants were screened for cellulolytic activity by plating in soft agar (0.7%) overlays containing either 1% (wt/vol) carboxymethyl cellulose (CMC), 4-methylumbelliferyl-β-
d
-cellobioside (MUC, 1 mg/ml), or 1% (wt/vol) Ostazin brilliant red-hydroxyethyl cellulose (OBR-HEC). One hundred and three recombinant phage exhibiting activity against OBR-HEC were found, and these fell into different classes based on the size of the zone of hydrolysis. Twenty-one recombinant phage exhibiting activity against CMC and 19 recombinant phage exhibiting activity against MUC were isolated. Four OBR-HEC
+
, five CMC
+
, and seven MUC
+
clones were further analyzed by restriction endonuclease mapping and cellulase substrate specificity to identify unique clones and to determine their cellulase type. Three different clone types representing endoglucanase activity were identified. Three clones that appeared to encode exoglucanase type activity and four clones that had a mixed specificity, including β-glucosidase activity, were also identified.
Efficacy of chemical dosing methods for isolating nontuberculous mycobacteria from water supplies of dialysis centers
Authors: Carson L A , Cusick L B , Bland L A , Favero M S
Published: January 2020

Investigations of nontuberculous mycobacterium (NTM) infections associated with various environmental sources have been hampered by the lack of adequate techniques for selective isolation of these organisms from environmental fluids. This study compared chemical dosing techniques for recovery of NTM from water samples collected from 115 randomly selected dialysis centers. Cell suspensions of NTM group II and IV isolates and gram-negative bacteria were exposed to solutions containing sodium hypochlorite (0.2 micrograms/ml of free available chlorine), formaldehyde (1, 0.75, or 0.5%), oxalic acid (1.25%), cetylpyridinium chloride (25 micrograms/ml), or cetyltrimethylammonium bromide (100 micrograms/ml). Results of standard membrane filtration assays with laboratory test strains and water samples from dialysis centers showed that 5 min of exposure to 1% formaldehyde effectively reduced gram-negative bacterial populations and allowed increased recovery of NTM in environmental fluids containing mixed microbial populations.
Survival of Escherichia coli with and without ColE1::Tn5 after aerosol dispersal in a laboratory and a farm environment
Authors: Marshall B , Flynn P , Kamely D , Levy S B
Published: January 2020

The survival of a laboratory strain and a naturally occurring fecal strain of Escherichia coli, with and without a Tn5-containing derivative of ColE1, was examined after aerosol dispersal in a laboratory office and a barn under ambient temperature and humidity conditions. Following the release of paired strains, air and diverse types of surfaces were assayed for the test organisms. In both environments, the number of airborne bacteria declined rapidly within the first 2 h. Longer survival was found on surfaces and varied with surface type: recovery was greatest from wood products. Organisms persisted for 1 day in the office and for up to 20 days in the barn. Survival of the fecal strain was better than that of the laboratory strain in both test environments. In general, plasmid-bearing strains fared similarly to their plasmidless parents, but in several comparisons the ColE1::Tn5-containing strain showed enhanced survival. These studies have implications for the present and proposed release of genetically engineered organisms with and without plasmid vectors.
Production of Mannitol by Fungi from Cotton Dust
Authors: Domelsmith Linda N. , Klich Maren A. , Goynes Wilton R.
Published: January 2020

Cotton dust associated with high pulmonary function decrements contains relatively high levels of mannitol. In this study, cotton leaf and bract tissue and dust isolated from cotton leaf tissue were examined by optical microscopy, scanning electron microscopy, and capillary gas chromatography.
Alternaria alternata, Cladosporium herbarum, Epicoccum purpurascens
, and
Fusarium pallidoroseum
were isolated from cotton leaf dust. The fungal samples, cotton dust, and cotton leaf contained mannitol. This study demonstrates that fungi from a late-fall harvest of cotton leaf material produce mannitol and are a probable source of the mannitol found in cotton dust.
Effect of Root Agglutinin on Microbial Activities in the Rhizosphere
Authors: Chao Wei-Liang , Li Ren-Ki , Chang Wen-Teh
Published: January 2020

A total of 220 bacterial isolates were obtained from pea rhizosphere and nonrhizosphere samples. Of these samples, 100 isolates were chosen randomly to test for their agglutinative reaction against pea root exudate. The percentage of positive agglutination of bacteria isolated from the nonrhizosphere sample was significantly lower than that of bacteria isolated from the rhizosphere sample. Moreover, this agglutinative reaction could not be blocked either by treating the bacterial cells or root exudate with different carbohydrates before they were mixed or by boiling the root exudate first. Bacteria that could be agglutinated by pea root exudate followed the downward growth of the pea root through the soil profile. The greater abilities of such bacteria to colonize the pea rhizosphere were indicated by their higher rhizosphere-colonizing (rhizosphere/nonrhizosphere) ratios, whether the bacteria were added alone or together with nonagglutinating bacteria. However, bacteria did show different agglutinative reactions toward root exudates obtained from different plants.
Degradation of naphthalene-2,6- and naphthalene-1,6-disulfonic acid by a Moraxella sp
Authors: Wittich R M , Rast H G , Knackmuss H J
Published: January 2020

A naphthalene-2,6-disulfonic acid (2,6NDS)-degrading Moraxella strain was isolated from an industrial sewage plant. This culture could also be adapted to naphthalene-1,6-disulfonic acid as growth substrate. Regioselective 1,2-dioxygenation effected desulfonation and catabolism to 5-sulfosalicylic acid (5SS), which also could be used as the sole carbon source. 5SS-grown cells exhibited high gentisate 1,2-dioxygenase activity. Neither 5SS- nor gentisate-grown cells oxidized 2,6NDS; therefore, 2,6NDS or an early metabolite must serve as an inducer of the initial catabolic enzyme(s).
Isolation of Plasmid-Harboring
Serratia plymuthica
from Facultative Gut Microflora of the Tobacco Hornworm,
Manduca sexta
Authors: Toth-Prestia Cynthia , Hirshfield Irvin N.
Published: January 2020

Aseptic isolation of the facultative gut microflora of the tobacco hornworm,
Manduca sexta
, yielded four microorganisms. Two were gram-positive
Bacillus
spp., one was
Serratia plymuthica
, and another was the yeast
Candida guilliermondii
. The three bacterial species were screened for extrachromosomal DNA, and
S. plymuthica
was found to have a 6.4-kilobase plasmid, which was designated pCP-1.
Phenotypic and genotypic characterization of tetracycline- and oxytetracycline-resistant Aeromonas hydrophila from cultured channel catfish (Ictalurus punctatus) and their environments
Authors: DePaola A , Flynn P A , McPhearson R M , Levy S B
Published: January 2020

Oxytetracycline-resistant (OTcr) and tetracycline-resistant (Tcr) Aeromonas hydrophila were isolated commonly from catfish intestinal contents and the water and sediment of catfish culture ponds, but less frequently in market catfish. Isolates demonstrated two resistance phenotypes, Tcr OTcr and Tcs OTcr, when plated directly on to MacConkey agar containing 30 micrograms of tetracycline or oxytetracycline per ml. Tcs OTcr isolates expressed Tcr after induction by 1 h of growth in tryptic soy broth containing 1 microgram of tetracycline per ml. Over 90% of the resistant aeromonads hybridized with DNA probes for class A or class E Tcr determinants; class E was twice as prevalent as class A. The distribution of class A and E Tcr determinants varied with the Tcr phenotypes. Prior to induction, 86% of isolates with class A determinants were Tcr as well as OTcr, while only 16% with class E determinant were Tcr. Three of 5 Tcr aeromonads without class A or class E determinants and 1 of 14 with class E determinants transferred Tcr to Escherichia coli.
Consequences of Accounting for Isotopic Dilution in Thymidine Incorporation Assays
Authors: Chrzanowski Thomas H.
Published: January 2020

Rates of thymidine incorporation into DNA were corrected for isotope dilution by internal nucleotide pools and were compared with rates obtained from uncorrected data. Differences as large as 109% were observed between corrected and uncorrected estimates of thymidine incorporation. The degree of underestimation varied seasonally and, to a lesser extent, spatially.