bluuebunny/crossref_metadata_2025 huggingface dataset:
Injured coliforms in drinking water
Authors: McFeters G A , Kippin J S , LeChevallier M W
Published: January 2020

Coliforms were enumerated by using m-Endo agar LES and m-T7 agar in 102 routine samples of drinking water from three New England community water systems to investigate the occurrence and significance of injured coliforms. Samples included water collected immediately after conventional treatment, during the backwash cycle, at various points in the distribution system, and 1 week after the break and subsequent repair of a distribution main. Injured coliforms in these samples averaged greater than 95%. m-T7 agar yielded 8- to 38-fold more coliforms than did m-Endo agar LES. The geometric mean of coliforms recovered by m-Endo agar LES was less than 1 confirmed coliform per 100 ml, although m-T7 agar yielded 5.7 to 67.5 confirmed coliforms per 100 ml. In addition, the majority of these samples giving positive results on m-T7 agar produced no detectable counts on m-Endo agar LES. These findings indicated that coliforms were injured and largely undetected by use of accepted analytical media in the systems examined.
Comparison of Cellulolytic Activities in
Clostridium thermocellum
and Three Thermophilic, Cellulolytic Anaerobes
Authors: Reynolds Paul H. S. , Sissons Christopher H. , Daniel Roy M. , Morgan Hugh W.
Published: January 2020

Avicelase, carboxymethyl cellulase (CMCase), and β-glucosidase activities have been compared between
Clostridium thermocellum
and three extremely thermophilic, cellulolytic anaerobes, isolates TP8, TP11, and KT8. The three isolates were all small, gram-negative staining, oval-ended rods which occurred singly and, at exponential phase, in long chains. They were nonflagellated and no spores were visible. The KT8 and TP11 isolates caused clumping of the cellulose during growth. In all four organisms the CMCase activity paralleled cell growth; however, in
C. thermocellum
and TP8 the avicelase activity did not increase until early stationary phase. Total CMCase activity in
C. thermocellum
was significantly higher than in the three isolates; however, avicelase activities were much more comparable among the four organisms.
C. thermocellum
produced higher levels of ethanol, and all four organisms produced similar concentrations of acetate. The amounts of free and bound CMCase and avicelase activities were investigated. In
C. thermocellum
and TP8 most of the CMCase and avicelase activities were bound to the cellulose in the medium. In contrast, most of the CMCase activity in TP11 and KT8 was free in the culture supernatant; a significant percentage of avicelase activity was also free. The TP8 isolate was also grown on a defined medium with urea as sole nitrogen source and cellulose serving as the carbon source. Under these conditions the pattern of enzyme production was the same as that in the enriched medium, although the level of that production was considerably reduced.
Transformation and transfection of anthracycline-producing streptomycetes
Authors: Lampel J S , Strohl W R
Published: January 2020

Streptomyces peucetius and Streptomyces strain C5, producers or anthracycline antibiotics, were converted to protoplasts from vegetatively growing mycelia. Conditions are described for maximal protoplast formation (greater than 99%) and for regeneration frequencies of up to 13%. Streptomycete plasmids pIJ61, pIJ702, and pIJ922, from the replicons SLP1, pIJ101, and SCP2, respectively, were isolated from Streptomyces lividans 66 and successfully introduced into S. peucetius and Streptomyces strain C5 by polyethylene glycol-mediated protoplast transformation. Frequencies of up to 10(6) transformations X microgram of plasmid DNA-1 were achieved by these procedures. Analyses showed that the two anthracycline-producing strains can stably harbor the plasmids without deletion of plasmid sequences or loss of the plasmids for several transfers through selective media. Fragments of DNA from S. peucetius ligated into pIJ702 and introduced into Streptomyces strain C5 were stable after several transfers through selective media. Both anthracycline producers also were sensitive to infection and transfection by actinophages KC401 and KC515, clear plaque derivatives of bacteriophage phi C31. Optimal conditions were determined for the transfection of S. peucetius and Streptomyces strain C5 protoplasts with phi C31 KC401 and KC515 DNA with liposome-assisted, polyethylene glycol-mediated protoplast transfection.
Activity Measurements of Planktonic Microbial and Microfouling Communities in a Eutrophic Estuary
Authors: Jeffrey Wade H. , Paul John H.
Published: January 2020

[
3
H]thymidine incorporation, the rate of reduction of iodonitrotetrazolium violet (INT) to INT formazan normalized to DNA, and the ratio of ATP to DNA were adapted to measure the activity of attached and unattached microbial assemblages of Bayboro Harbor, Fla. Activity measurements by [
3
H]thymidine incorporation were made of cells attached to polystyrene culture dishes, in unfiltered water samples, and in the <1-μm-filtered fraction. In most cases, the activity of attached cells was greater than that of unattached cells either in unfiltered water samples or in the <1-μm fraction. The calculated thymidine incorporation rates for cells in the >1-μm fraction were higher than those for cells either in unfiltered water or in the <1-μm-filtered fraction. By the rate of reduction of INT to INT formazan normalized to DNA and by ATP-to-DNA ratios, attached cells were also more active than cells in unfiltered water samples. These results indicate that the microenvironment afforded by attachment is a more beneficial habitat for microbial growth. Reasons for greater activity by natural populations of attached bacteria are discussed.
Metabolism and Metal Binding by Surface-Colonizing Bacteria: Results of Microgradient Measurements
Authors: Kepkay P. E. , Schwinghamer P. , Willar T. , Bowen A. J.
Published: January 2020

Short-term (65-h) bacterial colonization of 0.2-μm (pore size) filters submerged in water from Lake Charlotte, Nova Scotia, was characterized by a well-defined succession of cell types, in which small cocci gave way to larger, rod-shaped cells. This succession agrees with the concept of attachment as a strategy for survival, in which inactive cocci can attach to a surface and grow into larger, rod-shaped cells by using endogenous nutrients and the nutrients accumulated at the solid-liquid interface. Analyses of oxygen and CO
2
microgradients above colonized surfaces indicated that a peak of respiration accompanied the succession of rods from cocci. CO
2
fixation then became apparent as the rods began to bind manganese and iron to their surfaces. This means that survival by attachment may not be just the province of heterotrophs. It could also be a strategy adopted by metal-oxidizing chemoautotrophs. Long-term (34-day) colonization of similar filters indicated that, while a succession of attached cell types may indeed be a natural occurrence, other factors (such as the selective grazing of larger cells) tend to obscure the development of this succession.
Catabolic Fate of
Streptomyces viridosporus
T7A-Produced, Acid-Precipitable Polymeric Lignin upon Incubation with Ligninolytic
Streptomyces
Species and
Phanerochaete chrysosporium
Authors: Pometto Anthony L. , Crawford Don L.
Published: January 2020

Degradation of ground and hot-water-extracted corn stover (
Zea mays
) lignocellulose by
Streptomyces viridosporus
T7A generates a water-soluble lignin degradation intermediate termed acid-precipitable polymeric lignin (APPL). The further catabolism of T7A-APPL by
S. viridosporus
T7A,
S. badius
252, and
S. setonii
75Vi2 was followed for 3 weeks in aerated shake flask cultures at 37°C in a yeast extract-glucose medium containing 0.05% (wt/vol) T7A-APPL. APPL catabolism by
Phanerochaete chrysosporium
was followed in stationary cultures in a low-nitrogen medium containing 1% (wt/vol) glucose and 0.05% (wt/vol) T7A-APPL. Metabolism of the APPL was followed by turbidometric assay (600 nm) and by direct measurement of APPL recoverable from the medium. Accumulation and disappearance of soluble low-molecular-weight products of APPL catabolism were followed by gas-liquid chromatography and by high-pressure liquid chromatography, utilizing a diode array detector. Identified and quantified compounds present in culture media included
p
-coumaric acid, ferulic acid,
p
-hydroxybenzoic acid,
p
-hydroxybenzaldehyde, protocatechuic acid, vanillic acid, and vanillin. The further catabolism of these APPL-derived aromatic compounds varied with the culture examined, and only
S. setonii
and
P. chrysosporium
completely degraded all of them. Some new intermediates of APPL metabolism also appeared in culture media, but the patterns were culture specific. Additional evidence from high-pressure liquid chromatography analyses indicated that one strain,
S. badius
, converted a water-soluble fraction evident by high-pressure liquid chromatography (7 to 10 min retention time range) into new products appearing at shorter retention times. Mineralization of a [
14
C-lignin]APPL was also followed. The percent
14
C recovered as
14
CO
2
,
14
C-APPL,
14
C-labeled water-soluble products, and cell mass-associated radioactivity, were determined for each microorganism after 1 and 3 weeks of incubation in bubbler tube cultures at 37°C.
P. chrysosporium
evolved the most
14
CO
2
(10%), and
S. viridosporus
gave the greatest decrease in recoverable
14
C-APPL (23%). The results show that
S. badius
was not able to significantly degrade the APPL, while the other microorganisms demonstrated various APPL-degrading abilities. The significance of these findings relative to the fate of APPLs in nature was discussed.
Measurement of Nitrous Oxide Reductase Activity in Aquatic Sediments
Authors: Miller L. G. , Oremland R. S. , Paulsen S.
Published: January 2020

Denitrification in aquatic sediments was measured by an N
2
O reductase assay. Sediments consumed small added quantities of N
2
O over short periods (a few hours). In experiments with sediment slurries, N
2
O reductase activity was inhibited by O
2
, C
2
H
2
, heat treatment, and by high levels of nitrate (1 mM) or sulfide (10 mM). However, ambient levels of nitrate (<100 μM) did not influence activity, and moderate levels (about 150 μM) induced only a short lag before reductase activity began. Moderate levels of sulfide (<1 mM) had no effect on N
2
O reductase activity. Nitrous oxide reductase displayed Michaelis-Menten kinetics in sediments from freshwater (
K

m

= 2.17 μM), estuarine (
K

m

= 14.5 μM), and alkaline-saline (
K

m

= 501 μM) environments. An in situ assay was devised in which a solution of N
2
O was injected into sealed glass cores containing intact sediment. Two estimates of net rates of denitrification in San Francisco Bay under approximated in situ conditions were 0.009 and 0.041 mmol of N
2
O per m
2
per h. Addition of chlorate to inhibit denitrification in these intact-core experiments (to estimate gross rates of N
2
O consumption) resulted in approximately a 14% upward revision of estimates of net rates. These results were comparable to an in situ estimate of 0.022 mmol of N
2
O per m
2
per h made with the acetylene block assay.
Energetics of Leucyl-Leucine Hydrolysis in
Streptococcus cremoris
Wg
2
Authors: van Boven Aart , Konings Wil N.
Published: January 2020

The hydrolysis of the dipeptide leucyl-leucine by whole cells of
Streptococcus cremoris
Wg
2
was dependent on the presence of the energy source lactose. Incubation of cells with uncouplers or ATPase inhibitors prevented the increase of peptidase activity upon the addition of lactose. Incubation with the ionophore nigericin resulted in decreased peptide hydrolysis activity, while incubation with valinomycin led to increased hydrolysis activity. In the presence of nigericin the ΔpH component of the proton motive force was decreased, while the electrical potential was increased. With valinomycin, the electrical potential was collapsed and the ΔpH was increased. When the external pH was decreased from 8 to 5, the rate of peptide hydrolyzing activity by whole cells increased with increasing ΔpH component. In contrast, the peptide hydrolyzing activity in the cell extract decreased with decreasing external pH. These results indicate that the ΔpH component of the proton motive force determines the leucyl-leucine hydrolyzing activity in
S. cremoris
Wg
2
.
Anomalies in mineralization of low concentrations of organic compounds in lake water and sewage
Authors: Hoover D G , Borgonovi G E , Jones S H , Alexander M
Published: January 2020

The rates of mineralization of nitrilotriacetic acid (NTA), 2,4-dichlorophenoxyacetic acid (2,4-D), p-nitrophenol, aniline, and isopropyl N-phenylcarbamate (IPC) at one or more concentrations ranging from 100 pg/ml to 1.0 microgram/ml were proportional to chemical concentrations in samples of three lakes. The rates at 100 pg of NTA, 2,4-D, p-nitrophenol, and aniline per ml in samples of one or more lakes were less than predicted, assuming the rates were linearly related to the concentration. Neither NTA nor 2,4-dichlorophenol at 2.0 ng/ml was mineralized in some lake waters, but higher levels of the two chemicals were converted to CO2 in samples of the same waters. In samples from two lakes, little or no mineralization of IPC or 2,4-D occurred at 1.0 microgram/ml, but 10 ng/ml or lower levels of the herbicides were mineralized. The mineralization in sewage of 1.0 microgram of NTA per ml was biphasic; about 20% of the substrate was mineralized in 20 h, and mineralization was only reinitiated after a period of 130 h. The biphasic transformation was not a result of the accumulation of organic products, and it was still evident if protozoan activity was inhibited. NTA also underwent a biphasic mineralization in lake waters, and the biphasic pattern was not altered by additions of growth factors and inorganic nutrients. From 40 to 60% of the carbon of aniline added to lake water at levels of 100 pg/ml to 1.0 microgram/ml was mineralized, but more than 90% of the carbon of NTA, 2,4-D, or p-nitrophenol added to lake water at 10 ng/ml or 1.0 microgram/ml was mineralized.(ABSTRACT TRUNCATED AT 250 WORDS)
Inactivation of Campylobacter jejuni by chlorine and monochloramine
Authors: Blaser M J , Smith P F , Wang W L , Hoff J C
Published: January 2020

Campylobacter jejuni and closely related organisms are important bacterial causes of acute diarrheal illness in the United States. Both endemic and epidemic infections have been associated with consuming untreated or improperly treated surface water. We compared susceptibility of three C. jejuni strains and Escherichia coli ATCC 11229 with standard procedures used to disinfect water. Inactivation of bacterial preparations with 0.1 mg of chlorine and 1.0 mg of monochloramine per liter was determined at pH 6 and 8 and at 4 and 25 degrees C. Under virtually every condition tested, each of the three C. jejuni strains was more susceptible than the E. coli control strain, with greater than 99% inactivation after 15 min of contact with 1.0 mg of monochloramine per liter or 5 min of contact with 0.1 mg of free chlorine per liter. Results of experiments in which an antibiotic-containing medium was used suggest that a high proportion of the remaining cells were injured. An animal-passaged C. jejuni strain was as susceptible to chlorine disinfection as were laboratory-passaged strains. These results suggest that disinfection procedures commonly used for treatment of drinking water to remove coliform bacteria are adequate to eliminate C. jejuni and further correlate with the absence of outbreaks associated with properly treated water.
Characterization of
Pseudomonas maltophilia
Isolates from Fleece Rot
Authors: MacDiarmid J. A. , Burrell D. H.
Published: January 2020

A total of 286 isolates of
Pseudomonas maltophilia
was collected from sheep exhibiting brown or yellowish fleece rot and from fly-strike lesions. Enzyme activities for 10 of the isolates were examined by plate tests and with the API ZYM system and compared with the enzymatic profile of a human type strain of
P. maltophilia
. The fact that ovine isolates of
P. maltophilia
are biochemically similar to pathogenic human strains suggests there may be an association between this organism and the brown to yellow type of fleece rot.
Adaptation of Aquatic Microbial Communities to Quaternary Ammonium Compounds
Authors: Ventullo Roy M. , Larson Robert J.
Published: January 2020

The effects of long-chain (C
12
to C
18
) quaternary ammonium compounds (QACs) on the density, heterotrophic activity, and biodegradation capabilities of heterotrophic bacteria were examined in situ in a lake ecosystem. Monoalkyl and dialkyl substituted QACs were tested over a range of concentrations (0.001 to 10 mg/liter) in both acute (3 h) and chronic (21 day) exposures. In general, none of the QACs tested had significant adverse effects on bacterial densities in either acute or chronic studies. However, significant decreases in bacterial heterotrophic activity were noted in acute studies at QAC concentrations from 0.1 to 10 mg/liter. Chronic exposure of lake microbial communities to a specific monoalkyl QAC resulted in an adaptive response and recovery of heterotrophic activity. No-observable-effect level in the adapted populations was >10 mg/liter. Chronic exposure also resulted in significant increases in the number and activity of bacteria capable of biodegrading the material. The increase in biodegradation capability was observed at low (microgram per liter) concentrations which are approximately the same as realistic environmental levels. In general, our studies indicated that exposure of lake microbial communities to QACs results in the development of adapted communities which are less sensitive to potential toxic effects and more active in the biodegradation of these materials.
Presumed Sexual Isolation in Yeast Populations during Production of Sherrylike Wine
Authors: Sancho E. D. , Hernandez E. , Rodriguez-Navarro A.
Published: January 2020

The three stages in wine production in the Montilla-Moriles region of Spain are (i) fermentation, (ii) film formation in vessels, and (iii) aging, all of which selected three yeast populations. All isolates from the three stages were classified as
Saccharomyces cerevisiae
. The distribution of characteristics of sugar fermentation (sucrose, galactose, maltose), Li
+
tolerance, and Cu
2+
tolerance was different in the strains isolated in the three stages. This finding suggests that sexual isolation in the yeast populations prevents the random distribution of taxonomic characters.
Adaptation to Hydrogen Sulfide of Oxygenic and Anoxygenic Photosynthesis among Cyanobacteria
Authors: Cohen Yehuda , Jørgensen Bo Barker , Revsbech Niels Peter , Poplawski Ricardo
Published: January 2020

Four different types of adaptation to sulfide among cyanobacteria are described based on the differential toxicity to sulfide of photosystems I and II and the capacity for the induction of anoxygenic photosynthesis. Most cyanobacteria are highly sensitive to sulfide toxicity, and brief exposures to low concentrations cause complete and irreversible cessation of CO
2
photoassimilation. Resistance of photosystem II to sulfide toxicity, allowing for oxygenic photosynthesis under sulfide, is found in cyanobacteria exposed to low H
2
S concentrations in various hot springs. When H
2
S levels exceed 200 μM another type of adaptation involving partial induction of anoxygenic photosynthesis, operating in concert with partially inhibited oxygenic photosynthesis, is found in cyanobacterial strains isolated from both hot springs and hypersaline cyanobacterial mats. The fourth type of adaptation to sulfide is found at H
2
S concentrations higher than 1 mM and involves a complete replacement of oxygenic photosynthesis by an effective sulfide-dependent, photosystem II-independent anoxygenic photosynthesis. The ecophysiology of the various sulfide-adapted cyanobacteria may point to their uniqueness within the division of cyanobacteria.
Inhibitory Effect of Autoclaving Whey-Based Medium on Propionic Acid Production by
Propionibacterium shermanii
Authors: Anderson Thomas M. , Bodie Elizabeth A. , Goodman Nelson , Schwartz Robert D.
Published: January 2020

Propionic acid production by
Propionibacterium shermanii
was compared in pasteurized and autoclaved whey-based media. Propionic acid production decreased with increasing whey concentration in autoclaved media but not in pasteurized media. Increasing the yeast extract concentration from 5 to 10 g/liter greatly reduced the inhibitory effect of autoclaving.
Enumeration by DNA colony hybridization of virulent Yersinia enterocolitica colonies in artificially contaminated food
Authors: Jagow J , Hill W E
Published: January 2020

A genetic probe was used to identify and enumerate virulent Yersinia enterocolitica colonies in 11 artificially contaminated foods. Efficiency of enumeration, determined by autoradiography after DNA colony hybridization, ranged from 66 to 100% (average, 86%) and was influenced by the number of indigenous bacteria. The use of nitrocellulose filters and agar medium had little effect on efficiency of enumeration.
Isolation of Non-O1
Vibrio cholerae
Serovars from Oregon Coastal Environments
Authors: Tison D. L. , Nishibuchi M. , Seidler R. J. , Siebeling R. J.
Published: January 2020

Water, sediment, and shellfish from three Oregon estuaries were cultured for pathogenic
Vibrio
species. Non-O1 serovars of
V. cholerae
were the most common pathogenic
Vibrio
species recovered. Non-O1
V. cholerae
were isolated from all three estuaries sampled, covering an area of about 170 miles along the Oregon coast. Non-O1
V. cholerae
were isolated from water and sediment, but not shellfish, at temperatures ranging from 11 to 19°C and salinities of 2.3 to 26‰. Sixteen isolates representing 12 different non-O1 serovars were identified, while four non-O1
V. cholerae
isolates failed to react with any of the 54 antisera tested. These results indicate that non-O1
V. cholerae
serovars can be found over a large geographic area and under a variety of environmental conditions. These organisms are apparently an autochthonous component of these estuarine microbial communities.
Susceptibility of psychrotrophic pseudomonads of milk origin to psychrotrophic bacteriophages
Authors: Patel T R , Jackman D M
Published: January 2020

A total of 47 psychrotrophic pseudomonads isolated from raw milk came from Newfoundland (19 isolates), British Columbia (6 isolates), Ontario (19 isolates), and Cork, Ireland (3 isolates). The susceptibility of these was tested against 30 bacteriophages isolated from cold-storage beef. Distinct lysotypes were observed with isolates representing different geographic regions. Phages as agents in the control of bacterial populations in milk is discussed.
Sodium-Dependent Growth of
Azotobacter chroococcum
Authors: Page William J.
Published: January 2020

The majority of
Azotobacter chroococcum
strains in a collection obtained from Alberta soils were absolutely dependent on Na
+
for growth. Two strains from the American Type Culture Collection also were either Na
+
dependent or were stimulated by Na
+
. Optimal growth required 0.8 mM Na
+
and was limited at 0.2 to 0.35 mM Na
+
. Growth promoted by 0.8 mM Na
+
was inhibited by Rb
+
> K
+
>> NH
4
+
but was not affected by Li
+
. Growth inhibition by Rb
+
and K
+
was overcome by increasing the Na
+
concentration present in the medium. Excellent growth in media containing limiting Na
+
was obtained when 25 mM Li
+
or 25 mM Mg
2+
was added. Li
+
was significantly more effective in replacing Na
+
than was Mg
2+
. Na
+
was required for growth on all C sources (glucose, sucrose, melibiose, and mannitol) and N sources (N
2
, NH
4
+
, and NO
3
−
) and was required throughout the pH range of growth. Cells suspended in Na
+
-deficient medium or in distilled water did not appear to lyse or lose viability.
Method for determining the temporal response of microbial phosphate transport affinity
Authors: Molot L A , Brown E J
Published: January 2020

Nutrient transport affinities of nutrient-starved microbial populations were measured as initial slopes of plots of limiting-nutrient transport rates versus extracellular limiting-nutrient concentrations. A method was devised for the determination of soluble reactive phosphate (Pi) affinity in Pi-limited continuous culture (aT), which was then used as an indicator of the effects of light/dark cycle (LD) perturbations on the temporal Pi transport abilities of three species of freshwater algae. Cell division was asynchronous for the green alga Selenastrum capricornutum grown in continuous cultures exposed to LD cycles. An apparent rhythm in aT for Pi was greatly affected by the population size parameter. Cell division was phased for the green alga Scenedesmus quadricauda grown in LD continuous culture. A rhythm in aT for Pi was not greatly affected by the biomass parameter. Cell division was also phased in LD continuous culture for the blue-green alga (cyanobacterium) Synechococcus Nägeli, but rhythms in other parameters could not be detected. Synechococcus Nägeli was an extremely efficient Pi transporter at low Pi concentrations in LD continuous culture, and so aT could not be calculated. The results demonstrate that aT is well suited to describing the temporal response of Pi transport in LD-perturbed, Pi-limited continuous culture.
Comparison of Hup Trait and Intrinsic Antibiotic Resistance for Assessing Rhizobial Competitiveness Axenically and in Soil
Authors: El Hassan G. A. , Hernandez B. S. , Focht D. D.
Published: January 2020

The competitiveness of dual-strain inocula of cowpea rhizobia for nodulation of
Vigna unguiculata
(L.) Walp. was studied axenically between one slow-growing strain (P132, HP147, 401, or 22A1) and one fast-growing strain (176A26 or 176A28) at logarithmic inoculum ratios ranging from 10
3
to 10
−3
. Nodule infectivity was determined by multiple intrinsic antibiotic resistance, since both fast-growing strains were sensitive. Different hydrogen uptake (Hup) efficiencies of dual-strain inocula allowed for the comparison of an indirect rapid method. Infectivity data based on antibiotic resistance and Hup efficiency were fit to linearized fractile plots of log-normal distributions to determine C
AB
(percent infectivity at a 1:1 inoculum density) or I
50
(inoculum ratio at 50% infectivity). The slow growers were always better competitors and had I
50
values which ranged from 7 to 160,000 and C
AB
values which ranged from 62 to 97%. P132 was the best competitor of all those tested. Antibiotic resistance and Hup efficiency methods were in agreement with 401 (Hup
−
) and 176A26 (Hup
+
), but the Hup efficiency method overestimated the I
50
index with 22A1 (Hup
−
) and 176A28 (Hup
+
). The competition of each of the four slow-growing strains with indigenous rhizobia was examined in
Cajanus cajan
from three tropical soils. Nodule infectivity for all strains ranged from 42 to 96%, and P132 was the best competitor in all the soils. Hup efficiency overestimated infectivity by about 2-fold when Hup
+
inocula (P132 and HP147) were used but underestimated infectivity by more than 100-fold when Hup
−
inocula (401 and 22A1) were used. Although the Hup trait has limited quantitative usage axenically, it is only qualitative in soil competition studies and can only be used with Hup
+
inocula.
Electron microscopic heteroduplex study and restriction endonuclease cleavage analysis of the DNA genomes of three lactic streptococcal bacteriophages
Authors: Jarvis A W , Meyer J
Published: January 2020

Three lactic streptococcal bacteriophages were compared with one another by electron microscopic analysis of heteroduplex DNA molecules. The phages were almost identical in morphology and had been isolated over a period of 10 years on different strains of Streptococcus cremoris from cheese plants situated in different parts of New Zealand. There was a high degree of homology between the DNAs, in agreement with Southern blot hybridization data reported earlier. There were, however, distinct regions of nonhomology, mostly between 0.45 and 1.71 kilobases in length, suggestive of the occurrence of block recombination events. A deletion of 2.23 kilobases in the two more recently isolated phages, or an insertion in the first isolate, was found. All three phage DNAs showed differences in restriction endonuclease cleavage sites. Alignment of the restriction endonuclease maps with the heteroduplex maps showed that differences in cleavage sites occurred most frequently in regions of nonhomology. However, differences in cleavage sites in regions of apparent homology were also detected, indicating that point mutations may have occurred in addition to block recombination events.
Sulfate Reduction Relative to Methane Production in High-Rate Anaerobic Digestion: Microbiological Aspects
Authors: Isa Zaid , Grusenmeyer Stéphane , Verstraete Willy
Published: January 2020

In the high-rate anaerobic reactors studied (ca. 10 g of chemical oxygen demand [COD] removed per liter of reactor per day), the sulfate-reducing bacteria (SRB) were poor competitors of methane-producing bacteria (MPB), scavenging only on the order of 10 to 20% of the total electron flow. The relatively noncompetitive nature of the SRB in this type of reactor is in sharp contrast to the tendency of the SRB to dominate in natural environments and in other types of anaerobic digesters. Various factors such as the feedback inhibition of H
2
S on the SRB, iron limitation, the origin of the SRB inocula, biokinetics, and thermodynamics were investigated. The outcome of the SRB-MPB competition under the reactor conditions studied appeared to be particularly determined by two factors. The SRB, as predicted by the
V
max
-

K
m

kinetics, competed most effectively at low substrate levels (<0.5 g of COD per liter). The MPB, however, appeared to colonize and adhere much more effectively to the polyurethane carrier matrix present in the reactor, thus compensating for the apparent lower growth rates. Even if the reactor was initially allowed to be predominantly colonized by SRB, the MPB could regain dominance.
Location of bacteria in the mid-colon of the rat
Authors: Bollard J E , Vanderwee M A , Smith G W , Tasman-Jones C , Gavin J B , Lee S P
Published: January 2020

The distribution of microorganisms in the mid-colon of the rat was studied by light and scanning electron microscopy. An antiserum against rat colon mucus was used to stabilize the mucus in situ. In samples not incubated with antiserum, the mucus disintegrated and contracted into patchy strands only partly covering the luminal surface of the colon. Bacteria were seen within fecal pellets, tangled among the strands of mucus, and scattered on the epithelial surface. However, when incubated with antiserum, mucus almost completely filled the lumen and coated the fecal pellets. Bacteria in these stabilized preparations were limited mainly to the fecal pellets, and there were small numbers scattered in the luminal mucus, but none were observed on the epithelial surface or within the crypts. Latex particles introduced into the lumen with the antiserum or with phosphate-buffered saline showed the same distribution as the bacteria. These findings are at variance with previous reports that organisms occur in abundance in the mucous layer, adjacent to cell surfaces, and inside crypts. Our results suggest that conventional preparation for microscopy without prior stabilization of the mucus in situ may lead to artifactual redistribution of microorganisms and emphasize the importance of mucus in maintaining mucosal-floral homeostasis in the colon.
Evaluation of Different Assay Systems for Identification of Environmental
Aeromonas
Strains
Authors: Toranzo Alicia E. , Santos Ysabel , Nieto Teresa P. , Barja Juan L.
Published: January 2020

Important biochemical reactions in conventional tests were compared with counterpart reactions in two multiple test systems, API-20E (Analytab Products, Plainview, N.Y.) and
Aeromonas hydrophila
medium, to evaluate their accuracy for the identification of motile
Aeromonas
spp. isolated from fish. In a total of 49
Aeromonas
spp. isolates and 10
A. hydrophila
reference strains, false-negative or -positive reactions were detected in the Voges-Proskauer test, indole production, gelatinase activity, production of gas, fermentation of arabinose, and lysine decarboxylase reaction. A good correlation was found, among the three identification systems, for the fermentation of mannitol and inositol as well as for the arginine dihydrolase and ornithine decarboxylase tests. The failure of
A. hydrophila
medium in the detection of gas indicates that this medium is not entirely suitable for defining aerogenic or anaerogenic strains. From the results of the present study, we consider that of the identification method and taxonomic scheme to be adopted for environmental
Aeromonas
spp. must be standardized.
Heme requirement for growth of fastidious atypical strains of Aeromonas salmonicida
Authors: Ishiguro E E , Ainsworth T , Kay W W , Trust T J
Published: January 2020

The growth of fastidious atypical strains of the fish pathogen Aeromonas salmonicida on both solid and liquid media was dependent specifically on a source of heme which was apparently required for initiation of growth at low inoculum densities. Thus, hemin enhanced the plating efficiencies of such strains on solid medium and significantly reduced their inoculum-size-dependent lag times in broth. The heme requirement could also be satisfied by hematoporphyrin and, less effectively, by hemoglobin. Since the requirement was a stable property of all 17 strains tested, it may prove to be another taxonomic criterion by which the atypical strains can be differentiated from the typical strains of A. salmonicida.
Growth characteristics of selected fungi on polyvinyl chloride film
Authors: Roberts W T , Davidson P M
Published: January 2020

The objective of this study was to determine if plasticized polyvinyl chloride film would support the growth of any of nine species of fungi. The film was suspended in distilled water with no nutrients or with glucose or ammonium sulfate. Spores of each of the test species were inoculated into the suspension medium, and the mixture was incubated at 30 degrees C for up to 18 weeks. Most species were found to be capable of utilizing the film for carbon or nitrogen when the other nutrient was supplied. Only two species, Aspergillus fischeri and Paecilomyces sp., were found to be capable of utilizing components of the film without added nutrients. Components of the polyvinyl chloride film were then incorporated into mineral salts medium to determine if these components could serve as carbon sources in the presence of ammonium nitrate. The only component found to be utilized by all the fungi as a carbon source was epoxidized oil, a plasticizer-stabilizer. Calcium-zinc stearate was an available carbon source for all except the Penicillium and Verticillium strains. The only other component utilized was a stearamide, which was metabolized solely by the Aspergillus sp. Only the stearamide contained enough nitrogen to serve as a primary source in the film. The compound, however, did not support growth of fungi in the presence of glucose. It was theorized that either the nitrogen of the stearamide was more readily available to the fungi in the whole film due to the presence of trace nutrients or the nitrogen was supplied by exogenous sources.
Involvement of a Plasmid in Production of Ropiness (Mucoidness) in Milk Cultures by
Streptococcus cremoris
MS
Authors: Vedamuthu Ebenezer R. , Neville Justine M.
Published: January 2020

Curing and genetic transfer experiments showed that lactose-fermenting ability (Lac
+
) and the ability to produce mucoidness in milk cultures (Muc
+
) in
Streptococcus cremoris
MS were coded on plasmids. The Lac
+
phenotype was associated with a 75.8-megadalton plasmid, pSRQ2201. The Muc
+
phenotype was associated with a 18.5-megadalton plasmid, pSRQ2202. The Lac plasmid, pSRQ2201, was first conjugatively transferred from
S. cremoris
MS to Lac
−
S. lactis
ML-3/2.2. Later, the Muc plasmid, pSRQ2202, was conjugatively transferred from Lac
−
Muc
+
S. cremoris
MS04 to Lac
+
nonmucoid
S. lactis
transconjugant ML-3/2.201. Subsequently, pSRQ2201 and pSRQ2202 were cotransferred from Lac
+
Muc
+
S. lactis
transconjugant ML-3/2.202 to Lac
−
, nonmucoid, malty
S. lactis
4/4.2 and
S. lactis
subsp.
diacetylactis
SLA3.25. Transconjugants showing pSRQ2201 were Lac
+
; those containing pSRQ2202 were Muc
+
. With the transfer of pSRQ2202, the transconjugants
S. lactis
ML-3/2.202 and
S. lactis
subsp.
diacetylactis
SLA3.2501 not only acquired the Muc
+
phenotype but also resistance to bacteriophages, which were lytic to the respective parent strains
S. lactis
ML-3/2.201 and
S. lactis
subsp.
diacetylactis
SLA3.25.
Fungitoxic effects of nonprotein imino acids on growth of saprophytic fungi isolated from the leaf surface of Calliandra haematocephala
Authors: Brenner S A , Romeo J T
Published: January 2020

Four saprophytic and pathogenic fungi were isolated from the leaf surface of Calliandra haematocephala, a tropical legume known to contain large amounts of rare nonprotein imino acids in its leaves and seeds. The fungi Aspergillus niger, Aspergillus sp., Curvularia sp., and Penicillium sp. were cultured in the laboratory and tested for susceptibility to leaf extracts of the host plant and to proline, pipecolic acid, cis-5-hydroxypipecolic acid, and 2,4-trans-4,5-cis-4,5-dihydroxypipecolic acid. Fungal spore germination and germ tube growth were measured. Aspergillus sp. was inhibited by plant extracts and by pipecolic acid and cis-5-hydroxypipecolic acid. Curvularia sp. growth was stimulated by plant extracts and by pipecolic acid. The other two fungi were unaffected by any of the treatments. The data indicate that imino acids may play a role in the specific resistance of Calliandra spp. to Aspergillus sp.
Effects of Long-Term Preservation of
Frankia
Strains on Infectivity, Effectivity, and In Vitro Nitrogenase Activity
Authors: Fontaine Mark S. , Young Patricia H. , Torrey John G.
Published: January 2020

Frankia
strain HFP ArI3 which had been preserved for 27 months by being lyophilized, frozen in glycerol, or stored in complex medium was successfully used as an inoculum after being subcultured for inducing nodulation and nitrogen fixation of
Alnus rubra.
Glycerol-preserved HFP ArI3 produced significantly lower rates of nitrogenase activity than did lyophilized or complex-medium-preserved inocula. Bacteria that had been preserved by all three methods were successfully induced to fix atmospheric nitrogen by being cultured in nitrogen-free medium. Subculturing of these cells in nitrogen-free medium a second and third time yielded increasing rates of nitrogenase activity. Initial nitrogenase activity was detected on days 5, 4, and 3 during the first, second, and third subcultures after preservation, respectively. Maximum activity was observed on days 11, 10, and 8 during the first, second, and third subcultures, respectively. A description is given of standard culture techniques used in our laboratory for
Frankia
isolates, and methods used to distribute
Frankia
cultures by mail are described.
Evaluation of culture media for recovery of Staphylococcus aureus from swimming pools
Authors: Alico R K , Dragonjac M F
Published: January 2020

Several selective media were evaluated for the primary isolation and enumeration of Staphylococcus aureus from halogenated indoor swimming pool waters. Standard plate counts of the viable population and total coliform densities were also determined to ascertain their value as indicator systems. All studies were done with membrane filters. The most selective, accurate, and reliable medium was Vogel-Johnson (VJ) medium supplemented with 0.5% pyruvate. This medium recovered two times more typical colonies than VJ medium alone, and subsequent identification of these well-defined black colonies proved that approximately 80% were S. aureus. The S. aureus recoveries correlated well with halogen levels and bather density use also. In contrast, VJ medium alone was 60% selective for S. aureus, and VJ medium supplemented with catalase did not increase either the percent recovery or the selectivity over that of VJ medium alone. Standard plate counts did not correlate with halogen levels, bather density, or total viable colonies. Coliforms were rarely recovered from indoor pool waters and were not considered to be useful indicators of water quality.
Improved Method of Typing
Bradyrhizobium japonicum
in Soybean Nodules
Authors: Lieberman Mark Tony , Zablotowicz Robert M. , Davis-Omholt Naida P.
Published: January 2020

An improved method for antibiotic resistance recovery of
Bradyrhizobium japonicum
from soybean (
Glycine max
(L.) Merr.) nodules that is simple, time saving, and economical was developed. This technique involves the use of two 96-well microtiter plates as a multinodule sterilization chamber and a template and a third plate as a 16-point replicator constructed with steel nails affixed to the plate with epoxy cement. With this system a team of four technicians could type 3,000 nodules per day. This method was useful in assessing strain establishment and interstrain competition when one or more uniquely labeled strains of
B. japonicum
were inoculated onto either growth-room- or field-grown soybeans. Contamination was low and reproducibility across replicates approached the theoretical upper limit. Simplicity in design and use made this recovery method especially adaptable for field studies in which large numbers of nodules were required to provide a representative statistical sample offering good precision.
Influence of Oxygen and pH on Methanethiol Production from
l
-Methionine by
Brevibacterium linens
CNRZ 918
Authors: Ferchichi Mohamed , Hemme Denis , Bouillanne Christian
Published: January 2020

The effects of dissolved oxygen concentration and pH on the growth of
Brevibacterium linens
CNRZ 918 and its production of methanethiol from
l
-methionine were investigated. Optimal specific methanethiol production was obtained at 25% saturation of dissolved oxygen and at a pH between 8 and 9, whereas optimal cell growth occurred at 50% oxygen saturation and when the pH was maintained constantly at 7. Methanethiol production by nonproliferating bacteria required the presence of
l
-methionine (7 mM) in the culture medium. This was probably due to the induction of enzyme systems involved in the process. The intracellular concentration of
l
-methionine seemed to play a key role in this process.
B. linens
CNRZ 918 tolerated alkaline pHs with a maximal growth pH of approximately 9. Its orange pigmentation seemed to depend on the presence of
l
-methionine in the culture medium and on the concentration of dissolved oxygen.
Production and Properties of Xylan-Degrading Enzymes from
Cellulomonas uda
Authors: Rapp Peter , Wagner Fritz
Published: January 2020

Xylan degradation and production of β-xylanase and β-xylosidase activities were studied in cultures of
Cellulomonas uda
grown on purified xylan from birchwood. β-Xylanase activity was found to be associated with the cells, although in various degrees. The formation of β-xylanase activity was induced by xylotriose and repressed by xylose. β-Xylosidase activity was cell bound. Both constitutive and inducible β-xylosidase activities were suggested. β-Xylanase and β-xylosidase activities were inhibited competitively by xylose. β-Xylanase activity had a pronounced optimum pH of 5.8, whereas the optimum pH of β-xylosidase activity ranged from 5.4 to 6.1. The major products of xylan degradation by a crude preparation of β-xylanase activity, in decreasing order of amount, were xylobiose, xylotriose, xylose, and small amounts of xylotetraose. This pattern suggests that β-xylanase activity secreted by
C. uda
is of the endosplitting type. Supernatants of cultures grown on cellulose showed not only β-glucanase but also β-xylanase activity. The latter could be attributed to an endo-1,4-β-glucanase activity which had a low β-xylanase activity.
Method for Detection of Microorganisms That Produce Gaseous Nitrogen Oxides
Authors: Jenneman Gary E. , Montgomery Anne D. , McInerney Michael J.
Published: January 2020

A method was developed to detect NO- or N
2
O-producing bacteria in solid or liquid medium by their ability to oxidize the redox indicator resazurin from its reduced colorless form to its oxidized pink form. The method was sensitive to as little as 35 nM N
2
O or 0.5 nM NO. Ninety-one percent of the colonies that oxidized resazurin on plates also produced N
2
O in slant cultures. Forty-four percent of the colonies that did not oxidize resazurin did produce N
2
O. This percentage was reduced to 15% when colonies in which the coloration was difficult to discern were picked to slants to determine whether they oxidized the slant. The production of N
2
O preceded the oxidation of resazurin by liquid cultures of
Escherichia coli
and a sludge isolate. With the denitrifying sewage isolate, the disappearance of N
2
O was followed by the return of resazurin to its reduced state.
Wolinella succinogenes
was found to produce small amounts of N
2
O from NO
3
−
, which resulted in a transient oxidation of resazurin.
Optimization of the BGM cell line culture and viral assay procedures for monitoring viruses in the environment
Authors: Dahling D R , Wright B A
Published: January 2020

An in-depth study of the continuous cell line designated BGM is described herein, and recommendations are made for standardizing cell culture and viral assay procedures. Based on data gathered from a survey of 58 laboratories using this cell line, a research plan was developed that included the study of growth media, sera, NaHCO3 levels, culture bottles, cell concentration, overlay media, agar, virus infection conditions, and cell-dissociating agents. Additionally, a comparative virus isolation study with BGM cells and nine other cell types was conducted with 37 sewage samples collected from nine different geographic areas. The results of the study indicated that the BGM cell line is superior for virus isolation when compared with the other cell types and that certain media and additives tend to increase BGM cell sensitivity to a specific group of viruses. A standardized procedure for cultivation of BGM cells is described which provides a more effective enterovirus assay system.
Effect of culture conditions on tremorgen production by some Penicillium species
Authors: di Menna M E , Lauren D R , Wyatt P A
Published: January 2020

Four strains each of seven tremorgenic Penicillium species were grown under various conditions and tested for tremorgen production by intraperitoneal injection of mice and by chemical analysis. Half of the strains had previously been found to be tremorgenic on bioassay after growth on Czapek Dox yeast extract broth or potato-milk-sucrose broth for 3 weeks at 26 degrees C. In the tests reported here nearly all previously nontremorgenic strains were either tremorgenic to mice or produced tremorgens detectable by chemical analysis but did so after longer incubation periods than used in the original screening. Bioassay was not suitable for the estimation of absolute levels but was preferable to chemical analysis when the identity of the tremorgens was not known. Species and strains within species gave different responses to changes in culture medium, incubation temperature, light irradiation, and shaking. Overall, tremorgen production was maximal at 20 or 26 degrees C, increased with time, and was reduced in shaken culture.