bluuebunny/crossref_metadata_2025 huggingface dataset:
Specific phases of root hair attachment in the Rhizobium trifolii-clover symbiosis
Authors: Dazzo F B , Truchet G L , Sherwood J E , Hrabak E M , Abe M , Pankratz S H
Published: January 2020

The time course and orientation of attachment of Rhizobium trifolii 0403 to white clover root hairs was examined in slide cultures by light and electron microscopy. Inocula were grown for 5 days on defined BIII agar medium and represented the large subpopulation of fully encapsulated single cells which uniformly bind the clover lectin trifoliin A. When 10(7) cells or more were added per seedling, bacteria attached within minutes, forming randomly oriented clumps at the root hair tips. Several hours later, single cells attached polarly to the sides of the root hair. This sequence of attachment to clover root hairs was selective for R. trifolii at inoculum sizes of 10(7) to 4 X 10(8) per seedling, specifically inhibited if 2-deoxy-D-glucose, a hapten for trifoliin A, was present in the inoculum, and not observed when 4 X 10(8) cells were added to alfalfa seedling roots or to large clover root cell wall fragments which lacked trifoliin A but still had trifoliin A receptors. Once attached, R. trifolii 0403 became progressively less detachable with 2-deoxy-D-glucose. At smaller inoculum sizes (10(5) to 10(6) cells per seedling), there was no immediate clumping of R. trifolii at clover root hair tips, although polar binding of bacteria along the root hair surface was observed after 4 h. The interface between polarly attached bacteria and the root hair cell wall was shown to contain trifoliin A by immunofluorescence microscopy. Also, this interface was shown by transmission electron microscopy to contain electron-dense granules of host origin. Scanning electron microscopy revealed an accumulation of extracellular microfibrils associated with the lateral and polar surfaces of the attached bacteria, detectable after 12 h of incubation with seedling roots. At this same time, there was a significant reduction in the effectiveness of 2-deoxy-D-glucose in dislodging bacteria already attached to root hairs and an increase in firm attachment of bacteria to the root hair surface, which withstood the hydrodynamic shear forces of high-speed vortexing. These results are interpreted as a sequence of phases in attachment, beginning with specific reversible interactions between bacterial and plant surfaces (phase I attachment), followed by production of extracellular microfibrils which firmly anchor the bacterium to the root hair (phase 2 adhesion). Thus, attachment of R. trifolii to clover root hairs is a specific process requiring more than just the inherent adhesiveness of the bacteria to the plant cell wall.(ABSTRACT TRUNCATED AT 400 WORDS)
Microbial colonization of human ileal conduits
Authors: Chan R C , Reid G , Bruce A W , Costerton J W
Published: January 2020

Morphological and microbiological techniques were used to locate and identify the microorganisms that colonized the human ileal conduits in 17 different patients from 5 days after surgery up to as many as 16 years of service as a urine conduit. The ecological sequence of this colonization assumes some practical importance because the ascending growth of pathogenic organisms in this essentially open, unvalved urinary tract diversion system leads to the development of life-threatening pyelonephritis. Extensive examination of the microvillus surfaces of the ilea of five accident victims by both transmission and scanning electron microscopy showed that these tissue surfaces were not colonized by bacteria, even in the absence of prophylactic antibiotic therapy, and that these surfaces were not occupied by adherent microorganisms after several years of service as a urine conduit, even when the skin surface stoma and the conduit contents were heavily colonized by bacteria and yeasts. During the initial period (10 days) of postoperative antibiotic therapy, the mucus and urine within the conduit were largely colonized by yeasts. A mixed population of yeasts and gram-positive cocci subsequently developed in the conduit itself, and gram-positive cocci were seen to be avidly adherent to epidermal cells at the stoma. As antibiotic protection was gradually withdrawn, gram-negative organisms became a part of the mixed microbial flora of the conduit contents, and some of the potentially pathogenic organisms of this group (e.g., Escherichia spp., Proteus spp., Pseudomonas spp., etc.) were isolated from patients with pyelonephritis that appeared to come from the ileal conduit.(ABSTRACT TRUNCATED AT 250 WORDS)
Production of monoclonal antibodies to staphylococcal enterotoxin A
Authors: Edwin C , Tatini S R , Strobel R S , Maheswaran S K
Published: January 2020

Spleen cells from mice immunized with staphylococcal enterotoxin A were successfully fused with NS-1 mouse myeloma cells. Two of the four clones studied produced monoclonal antibodies to staphylococcal enterotoxin A in growth medium which showed titers of greater than 10(6) to 10(7) when tested by the indirect enzyme-linked immunosorbent assay. These monoclonal antibodies showed reactivity with enterotoxins A and E in the enzyme-linked immunosorbent assay. However, the reactivity was higher with enterotoxin A than with enterotoxin E. Nanogram quantities of crude staphylococcus enterotoxin A from Staphylococcus aureus growth were detected by the monoclonal antibodies in electroimmunoblots via autoradiography.
Detection and quantitation of T-2 mycotoxin with a simplified protein synthesis inhibition assay
Authors: Thompson W L , Wannemacher R W
Published: January 2020

We describe a simple, rapid, and sensitive bioassay for the detection and quantitation of T-2 mycotoxin by using a protein synthesis assay in cultured cells. Increased sensitivity of the cells to the mycotoxin occurred with time up to ca. 60-min. Time and dose response curves show that an average of 10 to 20 ng of T-2 per ml was sufficient to cause 50% inhibition of protein synthesis in tissue culture cells. A wide range of tissue culture cells with varied type, tissue, and species sources and growth characteristics were tested by this system. All showed approximately the same sensitivity to the mycotoxin. A slight modification of the procedure was used for suspended cultures of mitogen-stimulated lymphocytes, which also showed an equal degree of sensitivity to the mycotoxin. By simply changing the labeled precursor, the inhibition of RNA, DNA, and protein synthesis by T-2 mycotoxin can be compared. Although T-2 mycotoxin had little effect on RNA synthesis, DNA and protein synthesis were equally inhibited. Because of its sensitivity and its capacity to quickly assay a large number of samples, this technique has been a valuable tool in screening samples for the presence of active toxin and has been used to help establish laboratory safety standards for the inactivation of T-2 mycotoxin by chemical agents. It is presently being used in studies of mycotoxin mechanism of action and approaches toward in vivo neutralization of the toxic effects of mycotoxins.
Effect of organic contamination upon microbial distributions and heterotrophic uptake in a Cape Cod, Mass., aquifer
Authors: Harvey R W , Smith R L , George L
Published: January 2020

Bacterial abundance, distribution, and heterotrophic uptake in a freshwater aquifer contaminated by treated sewage were determined from analyses of groundwater and sediment-core samples. The number of free-living (unattached) bacteria in contaminated groundwater declined steadily with increasing distance from the source of sewage infiltration, from 1.94 (+/- 0.20) X 10(6) ml-1 at 0.21 km to 0.25 (+/- 0.02) X 10(6) ml-1 at 0.97 km. Bacterial abundance in groundwater sampled at 0.31 km correlated strongly with specific conductance and increased sharply from 4.0 (+/- 0.3) X 10(4) ml-1 at a depth of 6 m to 1.58 (+/- 0.12) X 10(6) ml-1 at 14 m, then declined at 20 and 31 m to 1.29 (+/- 0.12) X 10(6) and 0.96 (+/- 0.12) X 10(6) ml-1, respectively. A majority of the bacteria in contaminated and uncontaminated zones of the aquifer were bound to the surfaces of particulates, less than 60 micron in diameter. The glucose uptake rate, assayed at in situ and 5 microM concentrations, declined steadily in contaminated groundwater sampled along a transect. A preparative wet-sieving technique for use in processing core samples for bacterial enumeration is described and evaluated.
In situ identification of bacterial species in marine microfouling films by using an immunofluorescence technique
Authors: Zambon J J , Huber P S , Meyer A E , Slots J , Fornalik M S , Baier R E
Published: January 2020

An immunofluorescence technique was developed for the in situ identification of specific bacteria in marine microfouling films. Microorganisms adherent to glass plates after 30 days of immersion in a synthetic seawater system were cultured and classified by biochemical tests, flagellar arrangement, and the API 20E system. All isolates were gram-negative aerobic or facultative motile rods, predominantly Pseudomonas spp. Rabbit antisera to the five dominant organisms including Achromobacter spp., Comamonas terrigena, P. putrefaciens, a yellow-pigmented Pseudomonas sp., and Vibrio alginolyticus were prepared. These antisera were shown to be species specific in indirect immunofluorescence assays against a battery of 26 marine isolates from 14 bacterial species, with the exception of antisera to the Pseudomonas spp, which cross-reacted with each other but not with test bacteria of other genera. These immunofluorescent reagents enabled the in situ identification of all five bacterial species in microfouling films. Low-surface-energy test plates had smaller numbers of adherent bacteria in microfouling films than medium-surface-energy test plates, suggesting that the degree of microfouling may be influenced by the surface energy. In addition, the reagents could identify up to 39% of the attached bacteria in microfouling films spontaneously formed on steel plates in flow cells deployed in different areas of the Atlantic Ocean. The microbial composition of the ocean-formed films varied with the geographical area of their formation. The present results indicate that immunofluorescence techniques may provide a rapid and reliable means to identify, in situ, specific bacteria in marine microfouling films.
Assessing Phytoplankton and Bacterioplankton Production During Early Spring in Lake Erken, Sweden
Authors: Bell Russell T. , Kuparinen Jorma
Published: January 2020

The spring development of both phytoplankton and bacterioplankton was investigated between 18 April and 7 May 1983 in mesotrophic Lake Erken, Sweden. By using the lake as a batch culture, our aim was to estimate, via different methods, the production of phytoplankton and bacterioplankton in the lake and to compare these production estimates with the actual increase in phytoplankton and bacterioplankton biomass. The average water temperature was 3.5�C. Of the phytoplankton biomass, >90% was the diatom
Stephanodiscus hantzchii
var.
pusillus
, by the peak of the bloom. The
14
C and O
2
methods of estimating primary production gave equivalent results (
r
= 0.999) with a photosynthetic quotient of 1.63. The theoretical photosynthetic quotient predicted from the C/NO
3
N assimilation ratio was 1.57. The total integrated incorporation of [
14
C]bicarbonate into particulate material (>1 μm) was similar to the increase in phytoplankton carbon determined from cell counts. Bacterioplankton increased from 0.5 � 10
9
to 1.52 � 10
9
cells liter
−1
(∼0.5 μg of C liter
−1
day
−1
). Estimates of bacterioplankton production from rates of [
3
H]thymidine incorporation were ca. 1.2 to 1.7 μg of C liter
−1
day
−1
. Bacterial respiration, measured by a high-precision Winkler technique, was estimated as 4.8 μg of C liter
−1
day
−1
, indicating a bacterial growth yield of 25%. The bulk of the bacterioplankton production was accounted for by algal extracellular products. Gross bacterioplankton production (production plus respiration) was 20% of gross primary production, per square meter of surface area. We found no indication that bacterioplankton production was underestimated by the [
3
H]thymidine incorporation method.
Variation in Preference for
Rhizobium meliloti
Within and Between
Medicago sativa
Cultivars Grown in Soil
Authors: Bromfield E. S. P.
Published: January 2020

Variation in nodulation preferences for
Rhizobium
strains within and between
Medicago sativa
cultivars was assessed in the greenhouse with plants grown in Leonard jars and two soils of diverse origin (Lanark and Ottawa), using inocula consisting of effective individual or paired strains of
R. meliloti
which could be recognized by high-concentration antibiotic resistance. The results indicated considerable variability in host preferences for
R. meliloti
among plants within cultivars but not between cultivars. The implications of this variation are discussed from the point of view of possible improvement of symbiotic nitrogen fixation. With one exception, the differences in nodulation success between inoculant
R. meliloti
strains were consistent in Leonard jars and both soils. All introduced strains formed significantly more nodules in Renfrew soil containing few native rhizobia than in Ottawa soil with a large resident
R. meliloti
population. Plants grown in Lanark soil without inoculation were ineffectively nodulated by native rhizobia and yielded significantly less growth than those receiving inoculation. In contrast, the yield of inoculated plants in Ottawa soil did not significantly differ from those without inoculation due to effective nodulation by native
R. meliloti.
The data indicated synergistic effects on yield by certain paired strain inocula relative to the same strains inoculated individually in Lanark but not in Ottawa soil or Leonard jars.
Underexpression of Ap from R-Plasmids in Fast-Growing
Rhizobium
Species
Authors: Sikka Virendra K. , Kumar Sushil
Published: January 2020

The presence of the plasmid RP1 in the cells of
Rhizobium leguminosarum
strains Rld1, 300, and 248,
R. phaseoli
1233,
R. trifolii
strains T1 and 6661, and
R. meliloti
4013 was found to appreciably increase bacterial resistance toward kanamycin and tetracycline but not toward ampicillin. The presence of 16 other R-plasmids in
R. leguminosarum
was also found to either not increase or only marginally increase bacterial resistance toward ampicillin. It appears now that underexpression of the plasmid-specified ampicillin function is common to most fast- and slow-growing rhizobia.
N
2
O Evolution by Green Algae
Authors: Weathers Pamela J.
Published: January 2020

Evidence is presented here that axenic cultures of
Chlorella, Scenedesmus, Coelastrum
, and
Chlorococcum
spp. evolve N
2
O when grown on NO
2
−
, showing that the Chlorophyceae are a source of N
2
O in aquatic systems.
Effect of Culture Conditions on the Production of Tyrosine Phenol-Lyase by
Erwinia herbicola
Authors: Para G. M. , Baratti J. C.
Published: January 2020

The effect of environmental parameters on the growth and the tyrosine phenol-lyase content of
Erwinia herbicola
was investigated. On mineral medium containing glycerol,
l
-tyrosine increased the enzyme content 23-fold. When the
l
-tyrosine was also the carbon source, bacterial growth was 300 times greater than the basal level. On a rich medium, tyrosine phenol-lyase production was strongly dependent on pH and aeration. Catabolite repression and induction both probably control enzyme content.
Hydroxyproline-Rich Protein Material in Wood and Lignin of
Fagus sylvatica
Authors: Dill Ingrid , Salnikow Johann , Kraepelin Gunda
Published: January 2020

The nitrogen content, distribution, and amino acid composition of protein material were determined in wood and lignin of
Fagus sylvatica.
The data indicated that the nitrogen originated from hydroxyproline-rich cell wall glycoprotein, about half of which may be bound to the lignin polymer. The implications for lignocellulose biodegradation are discussed.
Monitoring of filamentous fungal growth by in situ microspectrophotometry, fragmented mycelium absorbance density, and 14C incorporation: alternatives to mycelial dry weight
Authors: Granade T C , Hehmann M F , Artis W M
Published: January 2020

Monitoring of filamentous fungal growth by spectrophotometry is generally considered not feasible. This report describes the monitoring of growth of the filamentous fungi Trichophyton mentagrophytes, Rhizopus oryzae, and Sporothrix schenckii in broth by two new spectrophotometric methods and by 14C incorporation from [U-14C]glucose. Microcultures (200 microliter) were prepared in 96-well, flat-bottom microtiter trays, and macrocultures (4 ml) were prepared in glass vials proportionally scaled up from microcultures. Mycelium accumulation in microcultures was measured without terminating the cultures by in situ microspectrophotometry. Accumulation in macrocultures was monitored by uniformly fragmenting the mycelium with a Broeck tissue grinder and by measuring absorbance density in plastic cuvettes with a dual-beam spectrophotometer. Absorbance measurements were found to increase linearly with mycelial weight. In situ absorbance correlated with absorbance density of fragmented mycelium, indicating that both methods monitored growth equivalently. Both defined lag-, exponential-, and stationary-growth phases. Increases in 14C incorporation, absorbance, and mycelial dry weight were kinetically identical for macrocultures and microcultures of T. mentagrophytes. For R. oryzae and S. schenckii, with the exception of R. oryzae growing in microcultures, incorporation of 14C also defined lag, exponential, and stationary growth after selection of the appropriate isotope-specific activity. This incorporation correlated directly with absorbance. We conclude that in situ microspectrophotometry, fragmented mycelium absorbance density, and, to a lesser extent, 14C incorporation can be used to effectively monitor filamentous fungal growth.
Growth of phenol-mineralizing microorganisms in fresh water
Authors: Rubin H E , Schmidt S
Published: January 2020

A method was developed to enumerate the procaryotic and eucaryotic phenol-mineralizing microorganisms present in samples of fresh water. Sixty-five percent or greater mineralization of [U-14C]phenol was considered a positive tube (contained phenol-mineralizing microorganisms) in the most-probable-number technique. Replicate most-probable-number tubes contained no microbial inhibitors, streptomycin and tetracycline, or cyclohexamide and nystatin plus 200 pg to 100 micrograms of phenol per ml. Phenol mineralization rates were obtained by measuring the amount of exogenous phenol that disappeared from solution over time in the presence or absence of the microbial inhibitors. Initially, less than 100 phenol-mineralizing bacteria per ml and 1 phenol-mineralizing fungus per ml were present at both 200 pg and 100 micrograms of phenol per ml. Phenol mineralization rates were 6.3 times greater for the mineralizing bacteria than for the fungi at 200 pg of phenol per ml. Phenol concentrations above 10 micrograms/ml were inhibitory to the microorganisms capable of mineralizing phenol. The phenol mineralizers grew in the water samples in the absence of phenol, indicating that there were sufficient indigenous nutrients in the lake water to support growth. There was no difference in the growth rate of these microorganisms in the presence or absence of 1 ng of phenol per ml, whereas the growth rate was more rapid at 1 microgram of phenol per ml than in its absence. There was a correlation between microbial growth and the amount of phenol mineralized at 1 microgram but not at 1 ng of phenol per ml.(ABSTRACT TRUNCATED AT 250 WORDS)
Enrichment and Isolation of Rumen Bacteria That Reduce
trans
- Aconitic Acid to Tricarballylic Acid
Authors: Russell James B.
Published: January 2020

Bacteria from the bovine rumen capable of reducing
trans
-aconitate to tricarballylate were enriched in an anaerobic chemostat containing rumen fluid medium and aconitate. After 9 days at a dilution rate of 0.07 h
−1
, the medium was diluted and plated in an anaerobic glove box. Three types of isolates were obtained from the plates (a crescent-shaped organism, a pleomorphic rod, and a spiral-shaped organism), and all three produced tricarballylate in batch cultures that contained glucose and
trans
-aconitate. In glucose-limited chemostats (0.10 h
−1
),
trans
-aconitate reduction was associated with a decrease in the amount of reduced products formed from glucose. The crescent-shaped organism produced less propionate, the pleomorphic rod produced less ethanol, and the spiral made less succinate and possibly H
2
. Aconitate reduction by the pleomorphic rod and the spiral organism was associated with a significant increase in cellular dry matter. Experiments with stock cultures of predominant rumen bacteria indicated that
Selenomonas ruminantium
, a species taxonomically similar to the crescent-shaped isolate, was an active reducer of
trans
-aconitate. Strains of
Bacteroides ruminicola, Butyrivibrio fibrisolvens
, and
Megasphaera elsdenii
produced little if any tricarballylate.
Wolinella succinogenes
produced some tricarballylate. Based on its stability constant for magnesium (
K
eq
= 115), tricarballylate could be a factor in the hypomagnesemia that leads to grass tetany.
d
-Glucose Transport System of
Zymomonas mobilis
Authors: DiMarco Anthony A. , Romano Antonio H.
Published: January 2020

The properties of the
d
-glucose transport system of
Zymomonas mobilis
were determined by measuring the uptake of nonmetabolizable analogs (2-deoxy-
d
-glucose and
d
-xylose) by wild-type cells and the uptake of
d
-glucose itself by a mutant lacking glucokinase.
d
-Glucose was transported by a constitutive, stereospecific, carrier-mediated facilitated diffusion system, whereby its intracellular concentration quickly reached a plateau close to but not above the external concentration.
d
-Xylose was transported by the
d
-glucose system, as evidenced by inhibition of its uptake by
d
-glucose.
d
-Fructose was not an efficient competitive inhibitor of
d
-glucose uptake, indicating that it has a low affinity for the
d
-glucose transport system. The apparent
K

m

of
d
-glucose transport was in the range of 5 to 15 mM, with a
V
max
of 200 to 300 nmol min
−1
mg of protein
−1
. The
K

m

of
Z. mobilis
glucokinase (0.25 to 0.4 mM) was 1 order of magnitude lower than the
K

m

for
d
-glucose transport, although the
V
max
values for transport and phosphorylation were similar. Thus, glucose transport cannot be expected to be rate limiting at concentrations of extracellular glucose normally used in fermentation processes, which greatly exceed the
K

m

for the transport system. The low-affinity, high-velocity, nonconcentrative system for
d
-glucose transport described here is consistent with the natural occurrence of
Z. mobilis
in high-sugar environments and with the capacity of
Z. mobilis
for rapid conversion of glucose to metabolic products with low energetic yield.
Production of D- and L-xylulose by mutants of Klebsiella pneumoniae and Erwinia uredovora
Authors: Doten R C , Mortlock R P
Published: January 2020

D-Xylulose and L-xylulose were produced biologically by the oxidation of a corresponding pentitol. A Klebsiella pneumoniae mutant was constructed for the oxidation of D-arabitol to D-xylulose. This mutant constitutively synthesized the D-arabitol permease system and D-arabitol dehydrogenase but was unable to produce the D-xylulokinase of the D-arabitol pathway or the D-xylose isomerase and D-xylulokinase of the D-xylose pathway. An Erwinia uredovora mutant which constitutively synthesized a novel xylitol-4-dehydrogenase but could not synthesize L-xylulokinase was used for the oxidation of xylitol to L-xylulose. Washed cell suspensions of either mutant incubated with 0.5% pentitol would oxidize 60 to 65% of the pentitol to the corresponding ketopentose in 18 h and excrete the ketopentose into the medium. Ketopentoses were rapidly purified from the remaining pentitol by hydroxyl affinity chromatography.
Tolerance of Acinetobacter calcoaceticus RAG-1 to the cationic surfactant cetyltrimethylammonium bromide: role of the bioemulsifier emulsan
Authors: Shabtai Y , Gutnick D L
Published: January 2020

Emulsan, the polyanionic heteropolysaccharide bioemulsifier produced by Acinetobacter calcoaceticus RAG-1, was found to enhance the tolerance of RAG-1 cells to the toxic effects of the cationic detergent cetyltrimethylammonium bromide (CTAB). Emulsan-mediated tolerance was obtained with the purified deproteinated apoemulsan; ca. 9 micrograms of apoemulsan neutralized 1 microgram of CTAB. Deesterified apoemulsan was only half as effective in protecting the cells from CTAB toxicity. Tolerance was also mediated by the cell-associated emulsan minicapsule. Mutants lacking this capsule were more sensitive to CTAB than the corresponding parent. The growth of mutants and parent cells in mixed-culture experiments demonstrated that the cell-associated polymer mediates CTAB tolerance in the early stages of growth. Once sufficient cell-free polymer has been released into the aqueous medium (ca. 0.5 micrograms/ml), this extracellular emulsan also plays a role in CTAB tolerance.
Detection of false-positives among total and fecal coliform counts by factorial analysis of correspondence
Authors: Joncas M , Michaud S , Carmichael J P , Lavoie M C
Published: January 2020

Application of an analysis of correspondence to the biochemical characteristics of total and fecal coliforms isolated in the Ivory Coast permitted us to separate two small clusters of isolates different from the main clusters, which included isolates from human and animal feces. The isolates grouped in the small clusters were from water samples. An analysis of the biochemical characteristics which permitted the segregation of the "water-specific" isolates from the main clusters indicates that water-specific total coliforms were citrate positive, indole negative, and amygdaline positive. Water-specific fecal coliforms were either citrate positive, indole negative, amygdaline positive, and inositol negative or indole negative, amygdaline positive, and inositol positive. Any isolates not fitting the above patterns could be considered of fecal origin. If this observation is confirmed under temperate climates and for a greater number of isolates, these simple tests could be used to confirm the fecal origin of coliforms.
Biotransformation of trichloroethylene in soil
Authors: Wilson J T , Wilson B H
Published: January 2020

Trichloroethylene was shown to degrade aerobically to carbon dioxide in an unsaturated soil column exposed to a mixture of natural gas in air (0.6%).
Production and Consumption of H
2
during Growth of
Methanosarcina
spp. on Acetate
Authors: Lovley Derek R. , Ferry James G.
Published: January 2020

Methanosarcina
sp. strain TM-1 and
Methanosarcina acetivorans
produced and consumed H
2
to maintain H
2
partial pressures of 16 to 92 Pa in closed cultures during growth on acetate. Strain TM-1 produced H
2
continuously when H
2
was continuously removed from the culture. The potential physiological significance of H
2
in acetate metabolism to methane is discussed.
Modulation of cytotoxin production by Clostridium difficile in the intestinal tracts of gnotobiotic mice inoculated with various human intestinal bacteria
Authors: Corthier G , Dubos F , Raibaud P
Published: January 2020

Gnotobiotic mice died 2 days after inoculation of a cytotoxigenic Clostridium difficile strain. Protection occurred when mice were previously inoculated with a strain of Escherichia coli or Bifidobacterium bifidum. Intestinal cytotoxin production was highly reduced in the surviving mice, whereas the C. difficile population level did not decrease to a great extent.
Cytochemical Localization of Urease in a Rumen
Staphylococcus
sp. by Electron Microscopy
Authors: McLean R. J. C. , Cheng K.-J. , Gould W. D. , Costerton J. W.
Published: January 2020

We describe a technique whereby intracellular urease activity can be localized by transmission electron microscopy. The ammonia produced from the enzymatic hydrolysis of urea is first precipitated with sodium tetraphenylboron and then replaced with silver to produce electron-dense silver tetraphenylboron. This direct reaction product deposition procedure was used to demonstrate the presence of membrane-bound urease of
Staphylococcus
sp. H3-22, a gram-positive ruminal bacterium.
Possible implications of reciprocity between ethylene and aflatoxin biogenesis in Aspergillus flavus and Aspergillus parasiticus
Authors: Sharma A , Padwal-Desai S R , Nadkarni G B
Published: January 2020

Aspergillus flavus and Aspergillus parasiticus produced ethylene during early growth. However, the onset of toxin biosynthesis was marked by the absence of ethylene evolution. 2-Chloroethyl phosphonic acid, an ethylene-generating compound, inhibited aflatoxin biosynthesis in vivo. The reciprocal relationship between the production of aflatoxin and ethylene by the organism may indicate the involvement of the latter in the regulation of aflatoxin biogenesis.
Characterization of a Marine Bacterium Associated with
Crassostrea virginica
(the Eastern Oyster)
Authors: Weiner Ronald M. , Segall Anca M. , Colwell Rita R.
Published: January 2020

A gram-negative bacterium found to be closely associated with oysters has been isolated and characterized. The organism, designated LST, has a generation time of 106 min in Marine broth under optimal growth conditions at 25°C. During the decline phase of growth, it exhibits a morphological transition from a motile rod (ca. 1 μm in length) to an elongated, 3- to 40-μm, nonmotile, tightly coiled helix. LST synthesizes and releases a pigment in the stationary and decline phases of growth. Identified as melanin on the basis of chemical properties and UV absorbance maxima, the pigment comprises polymers of heterogeneous molecular weights, ranging from 12,000 to 120,000. The guanosine-plus-cytosine content of the LST DNA is 46%, and results of phenetic analysis and DNA-DNA hybridization indicate that this bacterium represents a new species. LST adheres to a variety of surfaces, including glass, plastics, and oyster shell, and has been shown to promote the settlement of oyster larvae.
Biotransformation of dehydroabietic acid with resting cell suspensions and calcium alginate-immobilized cells of Mortierella isabellina
Authors: Kutney J P , Choi L S , Hewitt G M , Salisbury P J , Singh M
Published: January 2020

Mortierella isabellina ATCC 38063 is a zygomycete capable of hydroxylating fish-toxic resin acids which occur in certain pulp mill effluents to nontoxic metabolites. Addition of dehydroabietic acid (1) (80 mg/liter) to a freshly inoculated culture of M. isabellina in dextrose-yeast extract broth resulted in precursor disappearance in 28 to 30 h. During growth phase, hydroxylation occurred at C-2, whereas hydroxylation at C-15 and C-16 commenced with onset of stationary phase. Alternatively, 1 added to stationary-phase culture (40 mg/liter) disappeared within 2 h and hydroxylation occurred concurrently at C-2, C-15, and C-16. Enzymatic activity of stationary-phase culture was totally cell associated and was present despite the absence of 1 during the preparatory growth phase. Resuspension of mature fungi as free mycelia or immobilized in calcium alginate beads did not diminish the effectiveness of the biotransformation, although two new metabolites, 15-hydroxy-8,9,11,12-tetradehydro-7,8-dihydroabietic acid (5) and 16-hydroxy-8,9,11,12-tetradehydro-7,8-dihydroabietic acid (7) were formed. Immobilized mycelia retained hydroxylase activity for greater than 110 days whether or not they were challenged with fresh 1 on a regular basis. In this respect they are more long-lived than resuspended free mycelia are.
Cloning of the pullulanase gene and overproduction of pullulanase in Escherichia coli and Klebsiella aerogenes
Authors: Takizawa N , Murooka Y
Published: January 2020

The pullulanase gene (pul) of Klebsiella aerogenes was cloned into a pBR322 vector in Escherichia coli. Deletion analysis of the recombinant plasmid showed that the pul coding sequence, probably with the regulator gene, was located entirely within a 4.2-kilobase segment derived from the chromosomal DNA of K. aerogenes. E. coli cells carrying the recombinant plasmids produced about three- to sevenfold more pullulanase than did the wild-type strain of K. aerogenes W70. When the cloned cells of E. coli were grown with pullulan or maltose, most pullulanase was produced intracellularly, whereas K. aerogenes produced pullulanase extracellularly. Transfer of the plasmid containing the pul gene into K. aerogenes W70 resulted in about a 20- to 40-fold increase in total production of pullulanase, and the intracellular enzyme level was about 100- to 150-fold higher than that of the parent strain W70. The high level of pullulanase activity in K. aerogenes cells carrying the recombinant plasmid was maintained for at least 2 weeks.
Colonization of chicken cecae by Escherichia coli associated with hemorrhagic colitis
Authors: Beery J T , Doyle M P , Schoeni J L
Published: January 2020

Bacterial enumeration, histologic examination, and immunoperoxidase staining demonstrated the ability of an Escherichia coli strain associated with hemorrhagic colitis (serotype O157:H7) to colonize chicken cecae for up to 90 days postinoculation after a peroral challenge at 1 day of age. The bacteria induced mild, transient, mucous membrane damage confined to the proximal cecae of healthy, normal-appearing chickens, principally at 14 to 28 days postinoculation. Attachment, effacement, and penetration of the cecal surface epithelium by E. coli O157:H7 were observed. With the exception of splenic, hepatic, and cecal tonsil immune-related changes and cecal damage and colonization, no other organ systems or portions of the gastrointestinal tract were affected by the bacteria. Bacterial counts indicated that E. coli O157:H7 was predominantly present in the cecae (often at levels greater than 10(6) CFU/g of tissue and contents) and to a lesser extent in the colon. Our results suggest that E. coli O157:H7 colonizes chicken cecae and is passed through the colon with fecal excrement. The ability of this organism to colonize chicken cecae indicates that chickens may serve as hosts and possibly as reservoirs for E. coli O157:H7.
Role of the Cell Surface of
Methanosarcina mazei
in Cell Aggregation
Authors: Robinson Ralph W. , Aldrich H. C. , Hurst Steven F. , Bleiweis A. S.
Published: January 2020

Colonial aggregates of
Methanosarcina
(=
Methanococcus
)
mazei
were examined with scanning and transmission electron microscopy. Cells are irregular and grouped into multicellular sarcinal colonies, which may disaggregate in older cultures. The protoplast is bounded by a typical trilaminar plasma membrane, outside of which is a matrix of loose fibrils. The presence and compactness of matrix material are responsible for the close packing of cells, and colony disaggregation seems to be the result of matrix shedding and degradation. The cell envelope contains complex hetero polysaccharides of
N
-acetylgalactosamine and galacturonic and glucuronic acids. Polymers extruded by
M. mazei
are likely quite adhesive in nature, accounting for its strong adherence to surfaces and hardiness compared with many other methanogens.
Population Dynamics of Soil Pseudomonads in the Rhizosphere of Potato (
Solanum tuberosum
L.)
Authors: Loper Joyce E. , Haack Caryn , Schroth Milton N.
Published: January 2020

Rhizosphere population dynamics of seven
Pseudomonas fluorescens
and
Pseudomonas putida
strains isolated from rhizospheres of various agricultural plants were studied on potato (
Solanum tuberosum
L.) in field soil under controlled environmental conditions. Rhizosphere populations of two strains (B10 and B4) were quantitatively related to initial seed piece inoculum levels when plants were grown at −0.3 bar matric potential. At a given inoculum level, rhizosphere populations of strain B4 were consistently greater than those of strain B10. In vivo growth curves on 4-cm root tip-proximal segments indicated that both strains grew at similar rates in the potato rhizosphere, but large populations of strain B10 were not maintained at 24°C after 7 h, whereas those of strain B4 were maintained for at least 40 h. Although both strains grew more rapidly in the rhizosphere at 24°C than at 12°C, their rhizosphere populations after seed piece inoculation were generally greater at 12 or 18°C, indicating that in vivo growth did not solely determine rhizosphere populations in these studies. In vitro osmotolerance of seven
Pseudomonas
strains (including strains B4 and B10) was correlated with their abilities to establish stable populations in the rhizosphere of potato. Stability of rhizosphere populations of the
Pseudomonas
strains studied here was maximized at low (i.e., 12°C) soil temperatures. These results indicate that
Pseudomonas
strains differ in their capacity to maintain stable rhizosphere populations in association with potato. This capacity, distinct from the ability to grow in the rhizosphere, may limit the establishment of rhizosphere populations under some environmental conditions.
Activated Sludge Biodegradation of 12 Commercial Phthalate Esters
Authors: O'Grady Dean P. , Howard Philip H. , Werner A. Frances
Published: January 2020

The activated sludge biodegradability of 12 commercial phthalate esters was evaluated in two test systems: (i) a semicontinuous activated sludge test and (ii) an acclimated 19-day die-away procedure. Both procedures demonstrated that phthalate esters are rapidly biodegraded under activated sludge conditions when loss of the parent phthalate ester (primary degradation) is measured.
Biotransformations of 1',2'-dihydrorotenone by Streptomyces griseus
Authors: Sariaslani F S , Rosazza J P
Published: January 2020

Dihydrorotenone yields three major products when incubated with growing cultures of Streptomyces griseus. These were isolated by solvent extraction and characterized by spectral methods as 1',2'-dihydro-6abeta-hydroxyrotenone, 1',2'-dihydro-2',6abeta-dihydroxyrotenone, and 1',2'-dihydro-1',6abeta-dihydroxyrotenone.
Modified membrane-filter procedure for concentration of enteroviruses from tap water
Authors: Shields P A , Berenfeld S A , Farrah S R
Published: January 2020

Enteroviruses added to 114 liters of dechlorinated tap water were recovered in a 16-ml sample by a two-stage concentration procedure in which different types of membrane filters were used in each concentration stage. Viruses in tap water at pH 3.5 were first adsorbed to 10-in. (ca. 25.4-cm) epoxy-fiber glass filters (Filterite). Viruses adsorbed to these filters were eluted with a solution of 0.2 M sodium trichloroacetate buffered at pH 9 with 0.2 M lysine. Viruses in this solution were adsorbed to 47-mm asbestos filters (Seitz) without pH adjustment or other modification of the solution. Viruses were recovered from the Seitz filters with 16 ml of either Casitone or fetal calf serum at pH 9. With these procedures ca. 45% of several types of enteroviruses added to 114 liters of tap water could be recovered in the final 16-ml sample.
Method for improving the detection of viruses in fecal samples
Authors: Pontefract R D , Bergeron G
Published: January 2020

A method is described that improved the detection of viruses in fecal samples by electron microscopy. The virus particles were concentrated, and much of the background debris was removed by adsorption of viruses on meat protein added to the fecal sample at a low pH and a low salt concentration. Viruses were eluted by raising the pH and the salt concentration. Further concentration was achieved by acid precipitation and vacuum dialysis.
Possible Involvement of Phage-Like Structures in Antagonism of Cowpea Rhizobia by
Rhizobium trifolii
Authors: Joseph M. V. , Desai J. D. , Desai A. J.
Published: January 2020

A reduction in the viability of cowpea rhizobia was observed when
Rhizobium trifolii
IARI and cowpea
Rhizobium
strain 3824 were inoculated together in soil. The reduction in number of cowpea rhizobia in soil was found to be associated with the reduction in number of nodules per plant and retardation in plant growth. An antimicrobial substance was isolated from
R. trifolii
which, on electron microscopic investigation, demonstrated the presence of several phage-like structures.
Quantitative Addition of Dissolved Oxygen to In Situ Benthic Chamber Systems by Use of Catalase and Hydrogen Peroxide
Authors: Hickey Christopher W.
Published: January 2020

A methodology for reoxygenation of in situ benthic chamber systems by enzymatic catalysis of hydrogen peroxide with catalase was developed. For a 10-liter benthic chamber, the injection of 1 ml of catalase suspension (26,000 U ml
−1
) followed by 10 ml of 0.5 M hydrogen peroxide solution resulted in complete reoxygenation within 2.5 min at 25°C.
Influence of Manganese on Growth of a Sheathless Strain of
Leptothrix discophora
Authors: Adams Lee F. , Ghiorse William C.
Published: January 2020

Mn
2+
exerted various effects on the growth of
Leptothrix discophora
strain SS-1 in batch cultures depending on the concentration added to the medium. Concentrations of 0.55 to 5.5 μM Mn
2+
, comparable to those in the environment from which strain SS-1 was isolated, decreased cell yield and prolonged stationary-phase survival, but did not affect growth rate. Elevated concentrations of 55 to 910 μM Mn
2+
also decreased cell yield and prolonged survival, but growth rate was decreased as well. The addition of 1,820 μM Mn
2+
caused a decline in cell numbers followed by an exponential rise after 80 h of incubation, indicating the development of a population of cells resistant to Mn
2+
toxicity. When 360 μM Mn
2+
or less was added to growth flasks, Mn
2+
was oxidized to manganese oxide (MnO
x
, where x is ∼2), which appeared as brown particles in the medium. Quantification of Mn oxidation during growth of cultures to which 55 μM Mn
2+
was added showed that nearly all of the Mn
2+
was oxidized by the beginning of the stationary phase of growth (15 to 25 h). This result suggested that the decrease in cell yield observed at low and moderate concentrations of Mn
2+
was related to the formation of MnO
x
, which may have bound cationic nutrients essential to the growth of SS-1. The addition of excess Fe
3+
to cultures containing 55 μM Mn
2+
increased cell yield to levels near those found in cultures with no added Mn
2+
, indicating that iron deprivation by MnO
x
was at least partly responsible for the decreased cell yield.
Novel microbial screen for detection of 1,4-butanediol, ethylene glycol, and adipic acid
Authors: Stieglitz B , Weimer P J
Published: January 2020

A novel microbial-screening procedure was developed for separate detection of 1,4-butanediol, ethylene glycol, and adipic acid, three commercially important oxychemicals potentially derivable from bacterial omega-oxidation of n-butanol, ethanol, and hexanoic acid, respectively. The screening method involved postproduction addition of one of several specific Pseudomonas strains which produce a soluble fluorescent pigment during growth on the product of interest. A mutation and selection procedure was developed for isolation of specific strains with phenotypes for growth and pigment production on the desired product (e.g., 1,4-butanediol), but not on its bioconversion substrate (e.g., n-butanol), common by-products (e.g., n-butyrate), or product isomers. Pigment production was growth associated and required cultivation of the screening strains under limiting Fe3+ concentrations. The pigments resembled well-characterized, iron-chelating siderophores produced by other fluorescent pseudomonads. The sensitivity of the assay for product accumulation was enhanced by (i) conducting the screening in microtiter dishes to permit examination of individual isolates of putative producers and to control product diffusion, (ii) using a wavelength cutoff filter to reduce background source light, and (iii) using adapted screening strains which grew at lower (0.3 mM) concentrations of test compounds. The potential utility of the method for detecting a variety of oxidative catabolic products is discussed.
Leucine incorporation and its potential as a measure of protein synthesis by bacteria in natural aquatic systems
Authors: Kirchman D , K'nees E , Hodson R
Published: January 2020

Leucine incorporation was examined as a method for estimating rates of protein synthesis by bacterial assemblages in natural aquatic systems. The proportion of the total bacterial population that took up leucine in three marine environments was high (greater than 50%). Most of the leucine (greater than 90%) taken up was incorporated into protein, and little (less than 20%) was degraded to other amino acids, except in two oligotrophic marine environments. In samples from these two environments, ca. 50% of the leucine incorporated had been degraded to other amino acids, which were subsequently incorporated into protein. The degree of leucine degradation appears to depend on the organic carbon supply, as the proportion of 3H-radioactivity incorporated into protein that was recovered as [3H]leucine after acid hydrolysis increased with the addition of pyruvate to oligotrophic water samples. The addition of extracellular leucine inhibited total incorporation of [14C]pyruvate (a precursor for leucine biosynthesis) into protein. Furthermore, the proportion of [14C]pyruvate incorporation into protein that was recovered as [14C]leucine decreased with the addition of extracellular leucine. These results show that the addition of extracellular leucine inhibits leucine biosynthesis by marine bacterial assemblages. The molar fraction of leucine in a wide variety of proteins is constant, indicating that changes in leucine incorporation rates reflect changes in rates of protein synthesis rather than changes in the leucine content of proteins. The results demonstrate that the incorporation rate of [3H]leucine into a hot trichloroacetic acid-insoluble cell fraction can serve as an index of protein synthesis by bacterial assemblages in aquatic systems.
Use of chicken cell line LSCC-H32 for titration of animal viruses and exogenous chicken interferon
Authors: Roth S , Kaaden O R
Published: January 2020

The chicken embryo cell line LSCC-H32 was tested for the propagation and titration of several animal viruses of the families Toga-, Reo-, Rhabdo-, Herpeto-, Orthomyxo-, Paramyxo-, and Poxviridae and compared with secondary chicken embryo cells. The LSCC-H32 cells were demonstrated to be as susceptible for most of the tested viruses as were secondary chicken embryo cells. Both produced comparably sized virus plaques. The titers of Sindbis and Semliki Forest viruses in LSCC-H32 cells were 5- to 40-fold higher than in secondary chicken embryo cells or BHK-21 cells, respectively. Furthermore, exogenous chicken standard interferon was titrated in the LSCC-H32 cells, and a 50% plaque titer reduction of the challenging vesicular stomatitis virus was achieved by 0.12 IU of a standard chicken interferon preparation. Endogenous chicken interferon could not be induced by treatment of the cells with polyinosinic acid-polycytidylic acid. Due to its high plating efficiency and metabolic activities, the LSCC-H32 cell line provides a useful cell system for the titration and large-scale production of the tested animal viruses and for the titration of exogenous chicken interferon.