bluuebunny/crossref_metadata_2025 huggingface dataset:
Sulfate Reduction and Methanogenesis in the Sediment of a Saltmarsh on the East Coast of the United Kingdom
Authors: Senior Eric , Lindström E. Börje , Banat Ibrahim M. , Nedwell David B.
Published: January 2020

The rates of sulfate reduction, methanogenesis, and methane loss were measured in saltmarsh sediment at monthly intervals. In addition, dissolved methane and sulfate concentrations together with pS
2−
and pH were determined. Methane formation from carbon dioxide, but not from acetate, was detected within the same horizon of sediment where sulfate reduction was most active. Sulfate reduction was about three orders of magnitude greater than annual methanogenesis. The two processes were not separated either spatially or temporally, but occurred within the same layer of sediment at the same time of the year. Their coexistence did not seem to be the result of sulfate-depleted microenvironments within which methanogenesis could occur, but the methanogenic bacteria persisted at very low rates of activity within the same environment as the sulfate reducers.
Improved Method for Determination of Respiring Individual Microorganisms in Natural Waters
Authors: Tabor Paul S. , Neihof Rex A.
Published: January 2020

A method is reported that combines the microscopic determinations of specific, individual, respiring microorganisms by the detection of electron transport system activity and the total number of organisms of an estuarine population by epifluorescence microscopy. An active cellular electron transport system specifically reduces 2-(
p
-iodophenyl)-3-(
p
-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to INT-formazan, which is recognized as opaque intracellular deposits in microorganisms stained with acridine orange. In a comparison of previously described sample preparation techniques, a loss of >70% of the counts of INT-reducing microorganisms was shown to be due to the dissolution of INT-formazan deposits by immersion oil (used in microscopy). In addition, significantly fewer fluorescing microorganisms and INT-formazan deposits, both ≤0.2 μm in size, were found for sample preparations that included a Nuclepore filter. Visual clarity was enhanced, and significantly greater direct counts and counts of INT-reducing microorganisms were recognized by transferring microorganisms from a filter to a gelatin film on a cover glass, followed by coating the sample with additional gelatin to produce a transparent matrix. With this method, the number of INT-reducing microorganisms determined for a Chesapeake Bay water sample was 2-to 10-fold greater than the number of respiring organisms reported previously for marine or freshwater samples. INT-reducing microorganisms constituted 61% of the total direct counts determined for a Chesapeake Bay water sample. This is the highest percentage of metabolically active microorganisms of any aquatic population reported using a method which determines both total counts and specific activity.
Plasmid DNA in
Streptococcus cremoris
Wg2: Influence of pH on Selection in Chemostats of a Variant Lacking a Protease Plasmid
Authors: Otto Roel , de Vos Willem M. , Gavrieli Jonah
Published: January 2020

Cleared lysates of a proteolytic (Prt
+
) strain and a naturally occurring non-proteolytic (Prt
−
) variant of
Streptococcus cremoris
Wg2 contain equal amounts of covalently closed circular plasmid DNA. An analysis of this plasmid DNA by agarose gel electrophoresis revealed the presence of at least five different plasmid species in the Prt
+
strain and only three plasmid species in the Prt
−
variant. Curing studies with acriflavine indicated that a 16-megadalton plasmid determined proteolytic activity in the Prt
+
strain. In energy-limited chemostats inoculated with both strains it was observed that the Prt
+
strain was replaced by the Prt
−
variant. This effect was most apparent when the pH of the culture was fixed at a value above 6.3. No selection for the Prt
−
variant was observed at pH 5.9. Since the two types of organisms contain equal amounts of plasmid DNA, it was concluded that the energy gain of the Prt
−
variants at pH values above 6.0 probably has to be found in protein synthesis rather than in plasmid DNA synthesis.
Effect of pH on Inorganic Carbon Uptake in Algal Cultures
Authors: Azov Y.
Published: January 2020

Biomass production by the green algae
Scenedesmus obliquus
and
Chlorella vulgaris
in intensive laboratory continuous cultures was considerably affected by the pH at which the cultures were maintained. Carbon photoassimilation experiments revealed that pH values in the range of 8 to 9 were important for determining the free CO
2
concentrations in the medium. With higher pH values, additional pH effects were observed involving a decrease in the relative high affinity of low CO
2
-adapted algae to free CO
2
. The carbon uptake rate by high CO
2
-adapted algae after transfer to low free CO
2
medium was characterized by a lag period of about 30 min, after which the affinity of the algae to CO
2
increased considerably. Both continuous growth and carbon uptake experiments indicated that artificially maintained high free CO
2
concentrations are recommended for maximal production in intensive outdoor algal cultures.
Microflora of Drainage from Ice in Fishing Vessel Fishholds
Authors: Chen Hsing-Chen , Chai Tuu-Jyi
Published: January 2020

The microbial load in ice-melt drainage collected from fishholds of fishing vessels stowing lizard fish, black croakers, cuttle fish, or nemipterids was very high, ranging from 2.1 � 10
7
to 2.2 � 10
9
/ml for bacteria and 6.3 � 10
3
to 7.2 � 10
4
/ml for yeasts and molds. Analysis of 100 colonies each randomly isolated from drainage samples of cuttle fish and lizard fish showed that the occurrence of bacterial genera as a percentage of the total was
Moraxella-Acinetobacter
, 61 to 62%;
Pseudomonas
, 19 to 21%;
Alcaligens
, 5 to 10%;
Flavobacterium
, 1 to 4%;
Micrococcus
, 1 to 4%;
Bacillus, Vibrio
0 to 2%;
Corynebacterium
, 1 to 2%; and others, 1 to 2%. The organisms demonstrated versatile hydrolytic activities to a wide range of biological substrates including casein, gelatin, starch, DNA, and RNA. The possible connection between these bacteria and the deterioration of fish quality are discussed.
Perfusion Method for Assaying Microbial Activities in Sediments: Applicability to Studies of N
2
Fixation by C
2
H
2
Reduction
Authors: Capone Douglas G. , Carpenter Edward J.
Published: January 2020

A perfusion method for assaying nitrogenase activity (acetylene reduction) in marine sediments was developed. The method was used to assay sediment cores from
Spartina alterniflora
(salt marsh),
Zostera marina
(sea grass), and
Thalassia testudinum
(sea grass) communities, and the results were compared with those of conventional sealed-flask assays. Rates of ethylene production increased progressively with time in the perfusion assays, reaching plateau values of 2 to 3 nmol � g of dry sediment
−1
� h
−1
by 10 to 20 h. Depletion of interstitial NH
4
+
was implicated in this stimulation of nitrogenase activity. Initial acetylene reduction rates determined by the perfusion assay of cores from the
Spartina
community ranged from 0.15 to 0.60 nmol of C
2
H
4
� g of dry sediment
−1
� h
−1
. These rates were similar to those for sediments assayed in sealed flasks without seawater when determined over linear periods of C
2
H
4
production. Initial values obtained by using the perfusion method were 0.66 nmol of C
2
H
4
� g of dry sediment
−1
� h
−1
for sediments from
Zostera
communities and 0.70 nmol of C
2
H
4
� g of dry sediment
−1
� h
−1
for sediments from
Thalassia
communities. In all cases, rates determined by simultaneous slurry assays were lower than those determined by the perfusion method.
Effects of kepone on growth and respiration of several estuarine bacteria
Authors: Mahaffey W R , Pritchard P H , Bourquin A W
Published: January 2020

The toxicity of Kepone to mixed populations of estuarine microorganisms was determined by standard plate assays on Zobell marine medium containing 0.02, 0.20, and 2.0 mg of Kepone per liter. Under aerobic conditions, Kepone reduced the number of colony-forming units at all concentrations tested, but had no effect on the number of anaerobic microorganisms. Gram-positive organisms were more sensitive to Kepone than were gram-negative organisms. Growth of gram-negative isolates was not inhibited in nutrient broth, but was significantly inhibited in a minimal salts broth. Oxygen uptake by most isolates was reduced 25 to 100% by 20 ppm (20 mg/ml) of Kepone. Oxygen evolution was observed when several gram-positive isolates were exposed to Kepone concentrations of 20 ppm. Pentachlorophenol at concentrations above 28 ppm produced effects similar to those produced by Kepone. Inhibition of electron transport by Kepone was demonstrated by a significant reduction in the specific activities of NADH oxidases and succinooxidase.
Development of a method for detection of human rotavirus in water and sewage
Authors: Smith E M , Gerba C P
Published: January 2020

The simian rotavirus SA11 was used to develop a simple, reliable, and efficient method to concentrate rotavirus from tap water, treated sewage, and raw sewage by absorption to and elution from Filterite fiberglass-epoxy filters. SA11 adsorbed optimally to Filterite filters from water containing 0.5 mM AlCl3 at pH 3.5. Filter-bound virus was eluted with 0.05 M glycine-NaOH supplemented with 10% tryptose phosphate broth at pH 10. SA11 was quantitated by plaque assay, whereas human rotavirus was detected by immunofluorescence. The method was applied to detect rotavirus in raw and treated sewage at two Houston, Tex., sewage treatment plants. The sewage isolates were identified as rotavirus, probably a human strain, based on several criteria. The sewage isolates were detectable by an immunofluorescence test, using anti-SA11 serum which would detect the simian, human bovine, and porcine rotaviruses. No reaction was noted by immunofluorescence with the reoviruses or several common enteroviruses. The sewage isolates were neutralized by convalescent sera from a human adult and infant who had been infected by rotavirus as well as by a hyperimmune serum prepared in guinea pigs against purified human rotavirus. Preimmune or preillness sera did not react with the isolates by neutralization or immunofluorescence. The natural isolates were sensitive to pH 11 and other inactivating agents, similar to SA11. The buoyant density of the sewage isolates in CsCl gradients was 1.36 g/cm3, which is the value usually reported for complete, infectious rotavirus particles. The double-shelled particle diameter was 67.1 +/- 2.4 nm. Finally, electron micrographs of cell lysates inoculated with the sewage isolate showed particles displaying characteristic rotavirus morphology.
Glutamine and proline accumulation by Staphylococcus aureus with reduction in water activity
Authors: Anderson C B , Witter L D
Published: January 2020

Proline and glutamine were found to be the predominant free amino acids in Staphylococcus aureus MF-31 challenged by 5.8 or 10% NaCl in the growth medium. The accumulation of glutamine was the result of its synthesis, whereas the accumulation of proline was by transport.
Identification of volatile organic compounds produced by fluorescent pseudomonads on chicken breast muscle
Authors: Pittard B T , Freeman L R , Later D W , Lee M L
Published: January 2020

Four different fluorescent pseudomonads were isolated from spoiled, uncooked chicken breasts and were grown in pure culture on initially sterile chicken breast muscle at 2 to 6 degrees C for 14 days. The volatile compounds produced by each culture were concentrated on a porous polymer precolumn and separated and identified by high-resolution gas chromatography-mass spectrometry.
Effect of environmental conditions during heating on commercial spore strip performance
Authors: Smith G M , Kopelman M , Jones A , Pflug I J
Published: January 2020

Commercial biological indicator spore strips in glassine envelopes, produced by three manufacturers, were evaluated by fraction-negative procedures after being heated at 121.0 +/- 0.05 degrees C. Only one type of spore strip met the manufacturer's specifications. The strips of one manufacturer were further evaluated by fraction-negative and survivor curve-plate count procedures after being heated under several conditions (enclosed in glassine envelopes, in trypticase soy broth plus 0.0015% bromocresol purple, in Trypticase soy broth alone in Water for Injection, directly); Trypticase soy broth plus bromocresol purple and tryptic soy agar, respectively, were used as recovery media. The heating condition affected the D-value of the spore strip. Recovery procedures also had an effect; in all cases, the D-values obtained from the survivor curve tests were larger than those obtained from fraction-negative tests carried out under the same conditions. To determine if the differences in D-values between the two evaluation procedures were caused by the recovery media, we evaluated, by both methods, one type of spore strip heated directly and in glassine envelopes, using tryptic soy agar plus bromocresol purple and Trypticase soy broth plus 1.5% agar, respectively, as the recovery media. The survivor curve results showed that for both enclosed and unenclosed spore strips, there was a marked difference between the two recovery media; however, there was no difference when fraction-negative tests were used.
Structure-Activity Relationships in Microbial Transformation of Phenols
Authors: Paris D. F. , Wolfe N. L. , Steen W. C.
Published: January 2020

The second-order rate constants for the microbial transformation of a series of phenols were correlated with the physicochemical properties of the phenols. The compounds studied were phenol,
p
-methylphenol,
p
-chlorophenol,
p
-bromophenol,
p
-cyanophenol,
p
-nitrophenol,
p
-acetylphenol, and
p
-methoxyphenol. Phenol-grown cells of
Pseudomonas putida
U transformed these compounds. Microbial transformation rate constants ranged from (1.5 ± 0.99) × 10
−14
liter · organism
−1
· h
−1
for
p
-cyanophenol to (7.0 ± 1.3) × 10
−12
liter · organism
−1
· h
−1
for phenol. Linear regression analyses of rate constants and electronic, steric, and hydrophobic parameters showed that van der Waal's radii gave the best coefficient of determination (

r
2

= 0.956). Products identified by thin-layer chromatography and liquid chromatography indicated that the phenols were microbially oxidized to the corresponding catechols.
Continuous and static fermentation of glucose to ethanol by immobilized Saccharomyces cerevisiae cells of different ages
Authors: McGhee J E , St Julian G , Detroy R W
Published: January 2020

Glucose was converted to ethanol by calcium-alginate-entrapped Saccharomyces cerevisiae NRRL Y-2034 cells that were 24, 48, 72, and 96 h old in continuous-flow and static repeated-batch fermentors. In general, older yeast cells were more efficient than younger ones. In most cases, the continuous fermentations were better than the static ones in producing maximum ethanol yields (5.11 g/10 g of glucose) over extended time periods. The best static fermentation (with 24-h-old cells) converted 100% of the glucose to ethanol for about 12 days, whereas the best continuous fermentation (with 96-h-old cells) converted 100% of the glucose for a remarkable period of about 3 months.
Factors Affecting the Toxic Effect of Tin on Estuarine Microorganisms
Authors: Hallas Laurence E. , Thayer John S. , Cooney Joseph J.
Published: January 2020

Inorganic tin (SnCl
4
·H
2
O) is toxic to microbial populations obtained from estuarine sediments plated on nutrient medium solidified with either agar or purified agar. The use of gelatin as a gelling agent decreased the apparent toxicity of tin, and toxicity was markedly reduced in medium solidified with silica gel. There was no evidence that toxic agar-tin complexes were involved. Cd, Cu, Pb, Ni, and Zn exhibited similar toxicity patterns; therefore, toxicity levels determined in the laboratory should be extrapolated to the environment with caution. The addition of cysteine to the medium had no effect on tin toxicity. Serine or 3-hydroxyflavone enhanced toxicity, while humic acids or gelatin inhibited toxicity. Replacement of SO
4
2−
with NO
3
−
did not alter tin toxicity, but replacement of Cl
−
with NO
3
−
decreased tin toxicity. Thus, the toxic effect(s) of tin depend as much on the chemical speciation of the metal as on the total concentration of the metal in the medium.
Assessing Biomass and Production of Bacteria in Eutrophic Lake Mendota, Wisconsin
Authors: Pedrós-Alió Carlos , Brock Thomas D.
Published: January 2020

Estimates were made of the biomass and production of heterotrophic bacteria in the epilimnion of Lake Mendota, Wis. Cell counts were done with epifluorescence microscopy and varied from 3 × 10
5
bacteria per ml in winter to 3 × 10
6
bacteria per ml in summer. Cell volumes were measured in scanning electron micrographs. The average cell volume was 0.159 μm
3
. Annual variations and depth distribution were studied. Production was estimated from the frequency of dividing cells and from dark radioactive sulfate uptake. Annual productivity and daily average productivity were very close with both methods: 107 to 205 g of C per m
2
per year for sulfate and 89 to 117 g of C per m
2
per year for frequency of dividing cells. Zooplankton feeding removed 2 to 10% of the bacterial net production annually. When compared with biomass changes and losses due to zooplankton feeding, production values were very high. Therefore, it was suggested that other loss factors have to be more important than zooplankton feeding in controlling the bacterial population. Bacterial heterotrophic production was about 50% of gross primary production.
Production of Axenic
Gonyaulax
Cultures by Treatment with Antibiotics
Authors: Divan Charles L. , Schnoes Heinrich K.
Published: January 2020

The effects of amphotericin B, chloramphenicol, dihydrostreptomycin sulfate, neomycin sulfate, polymyxin B sulfate, potassium penicillin G, and streptomycin sulfate (used singularly and in various combinations at different concentrations) on the growth and development of four marine dinoflagellates of the genus
Gonyaulax
and associated bacteria were studied. The combination of amphotericin B, dihydrostreptomycin, neomycin, and penicillin G was highly effective in eliminating bacteria and fungi without reducing dinoflagellate growth and provided a useful method for obtaining axenic cultures of two
Gonyaulax
species,
G. catenella
and
G. excavata.
Production of Polyvinyl Alcohol Oxidase by a Symbiotic Mixed Culture
Authors: Shimao Masayuki , Taniguchi Yoshifumi , Shikata Shitsuu , Kato Nobuo , Sakazawa Chikahiro
Published: January 2020

Production of polyvinly alcohol (PVA) oxidase by
Pseudomonas
sp. strain VM15C, a PVA degrader of a symbiotic PVA-utilizing mixed culture, was examined in various cultures. Despite the absence of PVA in the culture in nutrient broth, VM15C showed approximately the same productivity of PVA oxidase activity as that in the culture with PVA as the sole carbon source, whereas the productivity in the culture with glucose was lower than that of either the nutrient broth or the PVA culture. PVA oxidase activity produced in the nutrient broth culture was predominantly present in the cells, and most of the activity appeared to be in the cytoplasm. In contrast, in the culture with PVA as the sole carbon source, the activity was present in the culture fluid in a larger ratio than in the nutrient broth culture. Thus, production of PVA oxidase activity by this strain was constitutive and repressible, although localization of the produced activity was changed by growth conditions.
Response of intestinal flora of laboratory-reared leopard frogs (Rana pipiens) to cold and fasting
Authors: Gossling J , Loesche W J , Nace G W
Published: January 2020

The bacterial flora of the large intestine was examined in 35 laboratory-reared leopard frogs (Rana pipiens) subjected to one of the following four treatments: (i) normal feeding at 21 degrees C (10 frogs); (ii) fasting for 2 weeks at 21 degrees C (8 frogs); (iii) chilling for 1 week at 4 degrees C (9 frogs); and (iv) simulated hibernation for 3 weeks at 4 degrees C (8 frogs). Bacteria from the intestinal contents and mucosa were counted microscopically and by colony counting after strictly anaerobic culturing. The predominant bacteria were isolated and partially characterized. Fasting for 2 weeks produced no significant changes in total counts or in the types of bacteria cultured. Chilling, whether rapid or in the course of simulated hibernation, was associated with a decrease in the numbers and variety of bacteria. Thus it appears that the lowering of temperature rather than the absence of food is the important factor in the reduction of bacterial flora seen in hibernating frogs. However, the bacteria showed some adaptation to the low temperature, as the longer the host had been at 4 degrees C, the higher the proportion of bacteria which could grow when cultured at that temperature.
Root Surface Association in Relation to Nodulation of
Medicago sativa
Authors: van Rensburg Henri Jansen , Strijdom Barend W.
Published: January 2020

Nine strains of
Rhizobium meliloti
, ranging in competitive ability on
Medicago sativa
from excellent to poor in autoclaved soils, were paired in 29 combinations and used to inoculate
M. sativa
in a liquid rooting medium. A positive correlation (
r
= 0.545) between strain ratios in nodules after 28 days and root surface cell ratios after 7 days was determined. Two cell fractions from the root surface, representing loosely and firmly adhering cells, were investigated. Infectivity was linked to the more firmly adhering cells. A significant relationship was established between the cell ratios of competing strains in the two fractions. In another experiment, adherence of cells of both infective and noninfective
Rhizobium
strains to roots of
M. sativa
and
Trifolium repens
was demonstrated; the ratios of loosely to firmly adhering cells on the root surface were significantly narrower with the infective combinations than with noninfective strain-legume associations.
Competitive Abilities of
Rhizobium meliloti
Strains Considered to Have Potential as Inoculants
Authors: van Rensburg Henri Jansen , Strijdom Barend W.
Published: January 2020

Twenty four strains of
Rhizobium meliloti
considered to have potential for inoculant production were grouped in pairs and tested for their ability to compete for nodulation on
Medicago sativa, Medicago truncatula
, and
Medicago littoralis
. At the outset, each pair of strains, which consisted of a wild type and a selected streptomycin-resistant mutant of another strain, was tested in an autoclaved soil. Six strain pairs, each consisting of a good and a poor competitor, reacted consistently when tested in each of five other autoclaved soils; eight pairs consisting of strains with comparable competitive abilities varied in their reactions in some of the soils, or even in the same soil when retested. An effect of soil pH on competitive ability was observed with some of these strains. Not all of the strains identified as good competitors on one or more of the
Medicago
spp. in the autoclaved soils were able to nodulate these plants satisfactorily in a field soil containing an established population of
R. meliloti
. Strain RF24, which seemed to be the best competitor on each of the three
Medicago
spp., grouped among the less effective strains on two of the legumes. Two strains of
R. meliloti
frequently used for inoculant production differed markedly with regard to competitive ability; this places some doubt on the relevancy of singling out competitive ability for special attention when selecting a strain for inoculant production.
Survival in lake water of Klebsiella pneumoniae discharged by a paper mill
Authors: Niemelä S I , Väätänen P
Published: January 2020

We investigated survival of Klebsiella pneumoniae in freshwater, by determining bacterial densities at eight temperatures between 0 and 20 degrees C at various distances from the discharge area in a lake receiving bacteria mainly from a paper mill. An mFC-inositol-carbenicillin-agar medium was used for Klebsiella enumeration by the membrane filter method. About 90% of the bacteria forming typical colonies on this medium were identified as Klebsiella species. About 10% of the bacteria were false positive, and, an equal percentage were false negative. Semilogarithmic plots of bacterial densities as a function of distance were found to be linear, with slopes depending on water temperature. The average velocity of the flow was estimated from the travel-of-bacterial-density minima caused by production stops. Regression equations were calculated for the dependence of death rate on temperature alone and on both temperature and discharge. The temperature coefficient (Q10) of the death rate was estimated to be 2.1 +/- 0.4. The decimal reduction time (T90) of K. pneumoniae at 0 degrees C was calculated to be about 24 days, and that at 20 degrees C was slightly over 5 days. The regression model was verified by independent observations. Factors affecting the reliability of the estimates were evaluated.
Effect of oilseed cakes on alpha-amylase production by Bacillus licheniformis CUMC305
Authors: Krishnan T , Chandra A K
Published: January 2020

The effects of oilseed cakes on extracellular thermostable alpha-amylase production by Bacillus licheniformis CUMC305 was investigated. Each oilseed cake was made of groundnut, mustard, sesame, linseed, coconut copra, madhuca, or cotton. alpha-Amylase production was considerably improved in all instances and varied with the oilseed cake concentration in basal medium containing peptone and beef extract. Maximum increases were effected by a low concentration (0.5 to 1.0%) of groundnut or coconut, a high concentration (3%) of linseed or mustard, and an Rintermediate concentration (2%) of cotton, madhuca, or sesame. The oilseed cakes made of groundnut or mustard could completely replace the conventional peptone-beef extract medium as the fermentation base for the production of alpha-amylase by B. licheniformis. The addition of corn steep liquor to cotton, linseed, sesame, or madhuca cake in the medium improved alpha-amylase production.
1,4-Naphthoquinone and other nutrient requirements of Succinivibrio dextrinosolvens
Authors: Gomez-Alarcon R A , O'Dowd C , Leedle J A , Bryant M P
Published: January 2020

Three strains of Succinivibrio dextrinosolvens isolated from the rumen of cattle or sheep under diverse conditions grew well in a minimal medium containing glucose, minerals, cysteine, methionine, leucine, serine, ammonia, 1,4-naphthoquinone, p-aminobenzoic acid, and bicarbonate-carbonic acid buffer, pH 6.7. When menadione or vitamin K5 was substituted for 1,4-naphthoquinone, the growth rate was somewhat depressed. Growth was poor with vitamin K1 and ammonia, further addition of the amino acids aspartic acid, arginine, histidine, and tryptophan was necessary for good growth of type strain 24, but the other two strains grew well only in media containing ammonia. Strains C18 and 22B produced urease and grew well when ammonia replaced urea. When urea replaced ammonia, strain 24 grew poorly and urease activity could not be detected. Strain 24 required no B-vitamins, but the other two strains were stimulated by p-aminobenzoic acid. The methionine requirement was not placed by vitamin B12, betaine, or homocysteine. Cysteine was replaced by sulfide in strain 24 but less well in the other two strains. Very poor growth was obtained when sulfate replaced cysteine. The half-saturation constant for ammonia during growth of S. dextrinosolvens is more than 500 microM, a much higher value than that of many rumen bacteria.
Relationship between fluorescein diacetate-stained hyphae and oxygen utilization, glucose utilization, and biomass of submerged fungal batch cultures
Authors: Ingham E R , Klein D A
Published: January 2020

The relationship between fungal activity and staining with fluorescein diacetate (FDA) was investigated by growing Penicillium citrinum and Rhizoctonia solani in submerged batch cultures at different initial glucose concentrations and aeration rates. A modified FDA staining method, similar to the Jones and Mollison technique (P. Jones and J. Mollison, J. Gen. Microbiol. 2:54-69, 1948), was developed to assess both total and FDA-stained hyphae. In previous studies, soil hyphae stained with FDA were considered viable. However, determination of a quantitative relationship between FDA staining and fungal activity is necessary before such an assumption can be made. Growth rates and the rate of change in the percentage of FDA-stained hyphae were significantly correlated. The regression equation calculated for the relationship was: growth rate (mg . ml-1 . h-1) = 0.34 + 1.1 (rate of change in the percentage of FDA-stained hyphae [. ml-1 . h-1]). Changes in activity as measured by O2 utilization, glucose utilization, and biomass correlated significantly with changes in the percentage of FDA-stained hyphae, although the relationships among these parameters were different for each fungal species. Fungal growth stage was also correlated with the percentage of FDA-stained hyphae. Staining was 10% or greater during fungal growth and less than 10% during the late growth, stationary, and death phases. Thus, the rate of change in the percentage of FDA-stained hyphae can be used to predict fungal activity rate changes for single fungal cultures and growth rates for mixed fungal cultures, and the growth stage can be assessed by the percentage of FDA-stained hyphae.
Field Observations of Methane Concentrations and Oxidation Rates in the Southeastern Bering Sea
Authors: Griffiths Robert P. , Caldwell Bruce A. , Cline Joel D. , Broich William A. , Morita Richard Y.
Published: January 2020

Measurements of methane oxidation rates were made in southeastern Bering Sea water samples with [
14
C]methane. The rate at which
14
CO
2
evolved from samples exposed to one methane concentration was defined as the relative methane oxidation rate. Rate determinations at three methane concentrations were used to estimate methane oxidation kinetics. The rate constant calculated from the kinetics and the observed methane concentration in the same water sample were used to calculate an in situ methane oxidation rate and the turnover time. First-order kinetics were observed in essentially all experiments in which methane oxidation kinetics were measured. Relative methane oxidation rates were greater in waters collected at inshore stations than at the offshore stations and were greater in bottom samples than in surface samples. In most water samples analyzed, there was essentially no radioactivity associated with the cells. The resulting respiration percentages were therefore very high with a mean of >98%. These data suggest that most of the methane was used by the microflora as an energy source and that very little of it was used in biosynthesis. The relative methane oxidation rates were not closely correlated with methane concentrations and did not appear to be linked to either oxygen or dissolved inorganic nitrogen concentrations. However, there was a significant correlation with relative microbial activity. Our data suggest that the methane oxidizers were associated with the general microbial heterotrophic community. Since these organisms did not appear to be using methane as a carbon source, it is unlikely that they have been isolated and identified as methane oxidizers in the past.
Evaluation of factors affecting the membrane filter technique for testing drinking water
Authors: Hsu S C , Williams T J
Published: January 2020

The following studies were done in response to questions regarding the adoption and use of the membrane filter (MF) technique for testing drinking water for the total coliform indicator group. A comparison with the most-probable-number technique showed that MF procedures with m-Endo agar LES were somewhat superior to the most-probable-number methods in terms of numbers of coliform organims recovered. Medium preparation and storage studies indicated that rehydration of m-Endo agar LES should be done with boiling water for less than 15 min, that m-Endo agar LES should not be exposed to light for more than 4 to 6 h, and that m-Endo agar LES plates may be used for up to 4 weeks and broth verification media for up to 3 weeks under given storage conditions. MF culture colonies were commonly found which did not produce sheen as expected for coliforms and yet were verified as coliforms. The occurrence and morphology of these atypical colonies were studied. Parallel inoculation of both lauryl tryptose (LT) and brilliant green bile (BGB) broth was found to be a better colony verification approach than recommended LT preenrichment before transfer to BGB. Comparison of parallel verification results indicated very little justification for the use of LT medium in MF verification procedures. In the case of overgrown or confluent cultures, the best coliform recoveries resulted from swabbing the MF plate and directly inoculating BGB medium with the swab. The occurrence of overgrowth was defined and evidence was collected suggesting that overgrowth is a function of sample holding time. Evaluation of routine test data and bacterial population reductions as a function of time indicated that nonquantitative recovery of coliforms may not be significantly affected for at least a 72-h sample holding time.
Microbial Metal Tolerance in Bermuda Carbonate Sediments
Authors: Hines Mark E. , Jones Galen E.
Published: January 2020

The recovery of aerobic heterotrophic bacteria from Bermuda carbonate sediments on metal-supplemented media varied as much as 44-fold over a 15-cm depth. Distributional relationships with sulfate-reducing bacteria and sediment character indicated that metal tolerance was a function of metal bioavailability.
Airstream Fractionation of Vesicular-Arbuscular Mycorrhizal Fungi: Concentration and Enumeration of Propagules
Authors: Tommerup Inez C.
Published: January 2020

Spores and fragments of vesicular-arbuscular mycorrhizal fungi in dry soils were concentrated up to 100-fold when the soils were partitioned by fluidization and elutriation with a series of upward airstreams at progressively increasing velocities. The propagules were transported with the finer soil particles according to their equivalent spherical diameters. The system was used to predict the transport of propagules by wind. Concentrated propagules were rapidly separated from the soil particles in each soil fraction by an aqueous flotation method. The technique is proposed as a quantitative method for estimating the numbers of spores and fragments of mycorrhizae. The scheme includes a viability test that was used to differentiate between potentially infective propagules and those that were either dormant or incapable of regrowth.
Viability and release of Salmonella charity and Escherichia coli from oyster feces
Authors: Rowse A J , Fleet G H
Published: January 2020

Sydney Rock oysters (Crassostrea commercialis) contaminated with Salmonella charity and Escherichia coli produced feces containing viable cells of these species. The level of these bacteria in the feces depended upon the level of oyster contamination. Both S. charity and E. coli were released from the feces into overlying seawater. The extent of release into seawater depended upon the physical state of the fecal material, water temperature, and the time of contact with the water. The viability of S. charity and E. coli associated with the feces and released into seawater decreased with time and was a function of seawater temperature. The association and release of bacteria from oyster feces has important implications in oyster purification and purification tank design and may lead to a recontamination of purified oysters.
Influence of Plant Phenolic Acids on Growth and Cellulolytic Activity of Rumen Bacteria
Authors: Chesson Andrew , Stewart Colin S. , Wallace R. John
Published: January 2020

Isolated rumen bacteria were examined for growth and, where appropriate, for their ability to degrade cellulose in the presence of the hydroxycinnamic acids
trans-p
-coumaric acid and
trans
-ferulic acid and the hydroxybenzoic acids vanillic acid and 4-hydroxybenzoic acid. Ferulic and
p
-coumaric acids proved to be the most toxic of the acids examined and suppressed the growth of the cellulolytic strains
Ruminococcus albus, Ruminococcus flavefaciens
, and
Bacteroides succinogenes
when included in a simple sugars medium at concentrations of >5 mM. The extent of cellulose digestion by
R. flavefaciens
and
B. succinogenes
but not
R. albus
was also substantially reduced. Examination of rumen fluid from sheep maintained on dried grass containing 0.51% phenolic acids showed the presence of phloretic acid (0.1 mM) and 3-methoxyphloretic acid (trace) produced by hydrogenation of the 2-propenoic side chain of
p
-coumaric and ferulic acids, respectively. The parent acids were found in trace amounts only, although they represented the major phenolic acids ingested. Phloretic and 3-methoxyphloretic acids proved to be considerably less toxic than their parent acids. All of the cellulolytic strains (and
Streptococcus bovis
) showed at least a limited ability to hydrogenate hydroxycinnamic acids, with
Ruminococcus
spp. proving the most effective. No further modification of hydroxycinnamic acids was produced by the single strains of bacteria examined. However, a considerable shortfall in the recovery of added phenolic acids was noted in media inoculated with rumen fluid. It is suggested that hydrogenation may serve to protect cellulolytic strains from hydroxycinnamic acids.
Cowpea Rhizobia Producing Dark Nodules: Use in Competition Studies
Authors: Eaglesham Allan R. J. , Ahmad Mohamed H. , Hassouna Salah , Goldman Barbara J.
Published: January 2020

During a program of screening rhizobia from West Africa, it was found that some strains produced nodules of unusually dark appearance on cowpeas, but not on peanuts, soybeans, pigeon peas, or mung beans. The dark pigmentation was in the bacteroid zone, was not correlated with nodule effectiveness, and was additional to the leghemoglobin pigment. Only rhizobial strains with a nongummy (“dry”) colony morphology produced dark nodules. Visually distinguishable pink and dark nodules formed on the same root when a mixture of pink and dark strains was applied as inoculum. The dark-nodule phenotype was therefore appraised as a marker and found to be useful for studying nodulation competition with strains of the orthodox pink-nodule type. The competitiveness of 10 pink-nodule strains was examined relative to a black-nodule strain, IRc 256; a range of competitiveness was obtained of less competitive than, equally competitive to, or more competitive than IRc 256. Patterns of primary (early) nodulation were generally the same as patterns of secondary (later) nodulation. Mixed infections by dark and pink strains produced piebald nodules, the frequency of occurrence of which was much greater among primary than among secondary nodules.
Competitive Dominance by a Bacteriocin-Producing
Vibrio harveyi
Strain
Authors: Hoyt Peter R. , Sizemore Ronald K.
Published: January 2020

Vibrio (Beneckea) harveyi
, a bioluminescent marine bacterium, has been shown to produce a bacteriocin-like substance the production of which is mediated by a plasmid. This substance is assumed to be proteinaceous because of its sensitivity to certain proteolytic enzymes. It is stable at low temperatures and can be concentrated by ammonium sulfate precipitation or negative-pressure dialysis. The molecular weight of the bacteriocin was determined to be 2.4 × 10
4
by molecular exclusion chromatography. Competition experiments indicated that bacteriocin-producing strains predominated over cured variants of the same strain in broth culture experiments. We studied several environmental parameters (pH, salinity, temperature, nutrient concentration) to determine their effects on the competitive advantage bestowed on a bacteriocin-producing strain. Under simulated free-living conditions, no competitive advantage attributable to bacteriocin production was observed. In a simulated enteric habitat, a bacteriocin-producing strain showed dramatic (>90%) inhibition of the sensitive strain within 24 h.
Commensalistic Interaction Between
Lactobacillus acidophilus
and
Propionibacterium shermanii
Authors: Liu Jennifer A. P. , Moon Nancy J.
Published: January 2020

Propionibacterium shermanii
and
Lactobacillus acidophilus
were grown in batch mixed culture in a 5-liter fermenter under controlled conditions of pH 5.8 and 35°C on a semisynthetic medium with glucose as an energy source. Cellular efficiencies and fermentation balances were developed for this pair and compared with
P. shermanii
grown in pure culture on glucose, lactate, and a mixture of these substrates and with
L. acidophilus
grown on glucose.
P. shermanii
had ATP yield coefficient values of 17 for each substrate alone but had an average value of 30 for substrate mixtures. Growth rates were similar for
P. shermanii
on glucose or lactate but higher cell yields were observed for glucose.
P. shermanii
used both lactate and glucose in mixed substrate until lactate was exhausted, and growth rates slowed thereafter.
L. acidophilus
had a similar ATP yield coefficient of 15 but produced lower cell yields than did
P. shermanii
on glucose. Mixed culture of both microorganisms on glucose resulted in much faster and nearly equal growth rates for both and no lactate accumulation in the medium. Acetic acid production rates per generation were lower in mixed culture, suggesting use by the growing culture. The cause of the synergistic effect was not determined but may be due to the rapid production and removal of lactate or CO
2
enhancement in mixed culture.
Improved Stomacher 400 Bag Applicable to the Spiral Plate System for Counting Bacteria
Authors: Konuma H. , Suzuki A. , Kurata H.
Published: January 2020

A stomacher 400 bag was slightly modified, constructed, and tested in combination with the spiral plating technique. Use of the modified bag resulted in more rapid sample preparation and saved both labor and glassware because of the avoidance of large particles of solids and fatty foods blocking the hole of the dispensing stylus tube.
Inactivation of Glutamine Synthetase by Ammonia Shock in the Gram-Positive Bacterium
Streptomyces cattleya
Authors: Wax Richard , Synder Linda , Kaplan Louis
Published: January 2020

In cultures of the gram-positive bacterium
Streptomyces cattleya
, a rapid inactivation of glutamine synthetase was seen after ammonia shock. pH activity curves for ammonia-shocked and control cultures are shown. A peak of glutamine synthetase activity was seen during fermentation for production of the antibiotic thienamycin.
Chemical and Physical Characterization of Interfacial-Active Lipids from
Rhodococcus erythropolis
Grown on
n
-Alkanes
Authors: Kretschmer Axel , Bock Hans , Wagner Fritz
Published: January 2020

Lipophilic compounds of the culture suspension containing
Rhodococcus erythropolis
DSM43215 had surfactant properties when the bacteria were cultivated with
n
-alkanes as the sole carbon source. Thirteen main components from a dichloromethane-methanol extract of the
R. erythropolis
cultures were isolated and characterized to specify quantitatively their surfactant properties, e.g., minimum surface and interfacial tensions and critical micelle concentrations. The interfacial activity of the organic extract was dominated by α,α-trehalose-6,6′-dicorynomycolates which reduced interfacial tension from 44 to 18 mN/m. Phosphatidylethanolamines which were also present in the organic extract reduced the interfacial tension below 1 mN/m. The trehalose corynomycolates had extremely low critical micelle concentrations in high-salinity solutions, and the interfacial properties were stabile in solutions with a wide range of pH and ionic strength.
Bacterial Nitration of 4-Chlorobiphenyl
Authors: Sylvestre Michel , Massé Robert , Messier François , Fauteux Johanne , Bisaillon Jean-Guy , Beaudet Réjean
Published: January 2020

In the course of a study dealing with the biodegradation of 4-chlorobiphenyl by strain B-206, we noticed that the gram-negative bacterium accumulated different metabolic intermediates depending on the nitrogen source of the medium. Hence, in the presence of nitrate, strain B-206 produced four compounds which were identified as 2- and 4-hydroxy-4′-chlorobiphenyl and 2- and 4-hydroxy-mononitro-4′-chlorobiphenyl. The accumulation of these compounds in the culture medium indicated the presence of a monooxygenase in strain B-206 leading to the production of arene oxide intermediates. The possible transformation of 4-chlorobiphenyl to an arene oxide by this bacterial strain is a matter of concern because of the high reactivity of these arene oxides with biological material.
Nodulation of Pole Bean (
Phaseolus vulgaris
L.) by
Rhizobium
Species of Two Cross-Inoculation Groups
Authors: Bal Arya K. , Shantharam S. , Wong Peter P.
Published: January 2020

Physiology and morphology of pole bean (
Phaseolus vulgaris
L. cv Kentucky Wonder) root nodules induced by two
Rhizobium
species of different cross-inoculation groups have been compared. Root nodules induced by
Rhizobium
sp. 127E15, which is a strain of the cowpea group
Rhizobium
, were pinkish, had irregular shapes, and were only partially effective. Their peak acetylene reduction activity was 4.36 μmol of C
2
H
4
formed per g of fresh nodules per h at 30 days after inoculation. The effective nodules induced by
Rhizobium phaseoli
127K14, which is a strain of the bean group
Rhizobium
, were dark red, spherical, and showed peak acetylene reduction activity of 15.95 μmol of C
2
H
4
formed per g of fresh nodules per h at 15 days after inoculation. The partial effectiveness of 127E15-induced nodules was associated with fewer infected cells, a delay in the increase of bacteroid population within the host cells, abundance of cytoplasmic vesicles in the host cells, more bacteroids within a membrane envelope (peribacteroid membrane), and the inability of bacteroids to completely fill up the host cytoplasmic space. The 127K14-induced nodules were fully mature, with host cells filled with bacteroids by 12 days after inoculation. In contrast, the 127E15-induced nodules did not reach a similar developmental stage even 30 days after inoculation.
Fungal Invertase as an Aid for Fermentation of Cane Molasses into Ethanol
Authors: Park Y. K. , Sato H. H.
Published: January 2020

Comparative studies of the fermentation of cane molasses into ethanol by
Saccharomyces cerevisiae
in the presence or absence of fungal invertase were performed. When cane molasses was fermented by the yeast at 30°C and pH 5.0, the presence of the enzyme had no effect on ethanol production. At pH 3.5, ethanol production was increased by the addition of invertase. At 40°C, the addition of invertase increased ethanol production by 5.5% at pH 5.0 and by 20.9% at pH 3.5.
Improved Medium for Isolation of
Azospirillum
spp
Authors: Cáceres Enrique A. Rodríguez
Published: January 2020

Colonies of
Azospirillum
spp. could be readily distinguished from colonies of other diazotrophs by scarlet coloration in culture media in which Congo red was included.