bluuebunny/crossref_metadata_2025 huggingface dataset:
Production of superoxide and hydrogen peroxide in medium used to culture Legionella pneumophila: catalytic decomposition by charcoal
Authors: Hoffman P S , Pine L , Bell S
Published: January 2020

The difficulties associated with the growth of Legionella species in common laboratory media may be due to the sensitivity of these organisms to low levels of hydrogen peroxide and superoxide radicals. Exposure of yeast extract (YE) broth to fluorescent light generated superoxide radicals (3 microM/h) and hydrogen peroxide (16 microM/h). Autoclaved YE medium was more prone to photochemical oxidation than YE medium sterilized by filtration. Activated charcoals and, to a lesser extent, graphite, but not starch, prevented photochemical oxidation of YE medium, decomposed hydrogen peroxide and superoxide radicals, and prevented light-accelerated autooxidation of cysteine. Also, suspensions of charcoal in phosphate buffer and in charcoal yeast extract medium readily decomposed exogenous peroxide (17 and 23 nmol/ml per min, respectively). Combinations of bovine superoxide dismutase and catalase also decreased the rate of photooxidation of YE medium. Medium protected from light did not accumulate appreciable levels of hydrogen peroxide, and autoclaved YE medium protected from light supported good growth of Legionella micdadei. Various species of Legionella (10(4) cells per ml) exhibited sensitivity to relatively low levels of hydrogen peroxide (26.5 microM) in challenge experiments. The level of hydrogen peroxide that accumulated in YE medium over a period of several hours (greater than 50 microM) was in excess of the level tolerated by Legionella pneumophila, which contained no measurable catalase activity. Strains of L. micdadei, Legionella dumoffi, and Legionella bozmanii contained this enzyme, but the presence of catalase did not appear to confer appreciable tolerance to exogenously generated hydrogen peroxide.
Ascorbic acid inhibition of Campylobacter jejuni growth
Authors: Fletcher R D , Albers A C , Chen A K , Albertson J N
Published: January 2020

The inhibitory effect of ascorbic acid on Campylobacter jejuni is described. In vitro growth of clinical strains, as measured spectrophotometrically, was inhibited by 0.5 mg of freshly prepared L-ascorbic acid per ml. Alkaline-treated or aged L-ascorbic acid increased inhibition, as did copper; however, L-cysteine, L-cystine, and glutathione prevented inhibition. Biochemical analysis of the medium and cultures indicated that one or more of the oxidation products of L-ascorbic acid, e.g., L-dehydroascorbic acid or L-diketogulonic acid, were more effective inhibitors than was reduced L-ascorbic acid.
Nutritional versatility of a starch-utilizing Flavobacterium at low substrate concentrations
Authors: van der Kooij D , Hijnen W A
Published: January 2020

A starch-utilizing yellow-pigmented bacterium, isolated from tap water, was tested for the utilization of 64 natural compounds at a concentration of 1 g/liter by measuring colony growth on agar media. Only 12 carbohydrates and glycerol promoted growth. Growth experiments with the organism in pasteurized tap water supplied with mixtures of substrates at concentrations of 1 or 10 micrograms of C of each substrate per liter, followed by separate experiments with a number of carbohydrates at 10 micrograms of C per liter showed that of these 64 natural compounds only sucrose, maltose, raffinose, starch, and glycerol promoted growth at very low concentrations. Also maltotriose, -tetraose, -pentaose, -hexaose, and stachyose, which were not included in the mixtures, enhanced growth, and generation times of 3 to 5 h at 10 micrograms of C per liter were observed. The organism, which was tentatively identified as a Flavobacterium species, thus appeared to be highly specialized in the utilization of glycerol and a number of oligo- and polysaccharides at very low concentrations.
Influence of Substratum Wettability on Attachment of Freshwater Bacteria to Solid Surfaces
Authors: Pringle James H. , Fletcher Madilyn
Published: January 2020

We studied the attachment of a number of freshwater bacteria from River Sowe, Coventry, England, to test substrata. The attachment of each organism to hydrophobic and hydrophilic surfaces was evaluated, and further studies evaluated the attachment of selected isolates to a number of substrata with a range of water wettabilities. The wettability of each substratum was determined by contact angle measurements and was expressed as the work of adhesion (W
A
). No generic pattern of attachment to the test surfaces was found, although the majority of the organisms isolated showed a preference for the hydrophobic surface. A more detailed study of selected isolates showed a relationship between W
A
and number of attached cells. Each bacterium attached in maximum numbers to a surface that was characteristic of that organism and that had a W
A
between 75 and 105 mJ m
−2
.
Effects of Nitrogen Supplements on Degradation of Aspen Wood Lignin and Carbohydrate Components by
Phanerochaete chrysosporium
Authors: Reid Ian D.
Published: January 2020

A supplement of KH
2
PO
4
, MgSO
4
, CaCl
2
, trace elements, and thiamine accelerated the initial rate of aspen wood decay by
Phanerochaete chrysosporium
but did not increase the extent of lignin degradation. Asparagine, casein hydrolysate, and urea supplements (1% added N) strongly inhibited lignin degradation and weight loss. The complex nitrogen sources peptone and yeast extract stimulated lignin degradation and weight loss. Albumen and NH
4
Cl had intermediate effects. Conversion of [
14
C]lignin to
14
CO
2
and water-soluble materials underestimated lignin degradation in the presence of the complex N sources. The highest ratio of lignin degradation to total weight loss and the largest increase in cellulase digestibility occurred during the decay of unsupplemented wood. Rotting of aspen wood by
P. chrysosporium
gives smaller digestibility increases than have been found with some other white-rot fungi.
Effects of Fusariotoxin T-2 on
Saccharomyces cerevisiae
and
Saccharomyces carlsbergensis
Authors: Schappert Keith T. , Khachatourians George G.
Published: January 2020

A
Fusarium
metabolite, T-2 toxin, inhibits the growth of
Saccharomyces carlsbergensis
and
Saccharomyces cerevisiae
. The growth inhibitory concentrations of T-2 toxin were 40 and 100 μg/ml, respectively, for exponentially growing cultures of the two yeasts.
S. carlsbergensis
was more sensitive to the toxin and exhibited a biphasic dose-response curve. Addition of the toxin at 10 μg/ml of
S. carlsbergensis
culture resulted in a retardation of growth as measured turbidimetrically, after only 30 to 40 min. This action was reversible upon washing the cells free of the toxin. The sensitivity of the yeasts to the toxin was dependent upon the types and concentrations of carbohydrates used in the growth media. The sensitivity of the cells to the toxin decreased in glucose-repressed cultures. These results suggest that T-2 toxin interferes with mitochondrial functions of these yeasts.
Microbial Resolution of α-Hydroxy Acids by Enantiospecifically Dehydrogenating Bacteria from Soil
Authors: Sawada Toyoaki , Ogawa Mayumi , Ninomiya Rieko , Yokose Kazuteru , Fujiu Morio , Watanabe Kimihiro , Suhara Yasuji , Maruyama Hiromi B.
Published: January 2020

Thirty-three bacterial strains were isolated from soil, utilizing optically asymmetric degradation of
dl
-2-hydroxy-4-methylpentanoic acid (
dl
-HMPA) as the screening probe. Those strains were distributed in the following group and genera:
Coryneform
and
Bacillus, Pseudomonas,
and
Streptomyces.
Among them, the most potent strains,
Bacillus freudenreichii
NRS-137KH20B and
Brevibacterium albidum
NRS-130KH20B, could perform the resolution of more than 30 g of
dl
-HMPA per liter within 4 to 5 days of fermentation. Optically pure
l
- and
d
-HMPA enantiomers were obtained in more than 80% theoretical yield, whereas the transformed enantiomer was almost quantitatively recovered as 2-oxo-4-methyl-pentanoic acid in the culture broth. The enantiospecific dehydrogenation responsible for this resolution reaction had a rather wide substrate specificity on straight or branched aliphatic C
4
to C
16
2-hydroxy acids, exhibiting the optima at chain lengths of either C
7
or C
5
, although the enantiospecificity was not changed by chain length. The process was thus successfully extended to the preparation of optically pure C
5
to C
9
2-hydroxy acids.
Lignin Degradation by
Streptomyces viridosporus
: Isolation and Characterization of a New Polymeric Lignin Degradation Intermediate
Authors: Crawford Don L. , Pometto Anthony L. , Crawford Ronald L.
Published: January 2020

A new, quantitatively significant intermediate formed during lignin degradation by
Streptomyces viridosporus
T7A was isolated and characterized. In
Streptomyces
-inoculated cultures, the intermediate, an acid-precipitable, polyphenolic, polymeric lignin (APPL), accumulated in the growth medium. The APPL was a water-soluble polymer probably consisting of a heterogeneous mixture of molecular weight components of ≥20,000. APPLs were precipitable from culture filtrates after they had been acidified to pH <3 to 5. Noninoculated controls yielded little APPL, but supernatant solutions from inoculated cultures produced quantities of APPL that correlated with the biodegradability of the lignocellulose type. Maximal recovery of APPL was obtained from corn lignocellulose, reaching 30% of the initial lignin present in the substrate. APPLs contained small amounts of carbohydrate, organic nitrogen, and inorganic materials. The lignin origin of APPLs was confirmed by chemical analyses, which included acidolysis, permanganate oxidation, elemental analyses, functional group analyses, nuclear magnetic resonance spectroscopy, and
14
C isotopic techniques. Analyses of APPLs from corn lignocelluloses showed that
S. viridosporus
-degraded APPLs were lignin derived but significantly different in structure from APPLs derived from uninoculated controls or from a standard corn milled-wood lignin. Degraded APPLs were enriched in phenolic hydroxyl groups and, to a small extent, in carboxyl groups. Degradative changes appeared to be largely oxidative and were thought to involve substantial cleavage of
p
-hydroxy ether linkages and methoxyl groups in the lignin.
Production and Characterization of Amylase from
Calvatia gigantea
Authors: Kekos D. , Macris B. J.
Published: January 2020

α-Amylase (EC 3.2.1.1) was excreted by
Calvatia gigantea
in liquid growth media containing different sources of starch. Among the factors affecting enzyme production in shake flasks were the type and the concentration of starch and the nitrogen source supplied. Optimum cultural conditions for maximum enzyme production were: soluble starch concentration, 5%; inoculum size, 3.75 × 10
5
conidia per ml; 5-day cultivation time at 28 to 30°C. The observed maximum yield of 81.3 U of saccharifying enzyme activity per ml of growth medium was the highest ever reported in the literature for submerged cultures. Partially purified enzyme functioned optimally at pH 4.5 to 5.5 and 53 to 58°C. The activation energy of enzymic hydrolysis of starch in the range of 20 to 40°C was 8,125 cal/mol (ca. 3.41 × 10
4
J). The apparent

K
m

value of the enzyme at 25°C was 7.68 × 10
−4
g/ml. Some of the properties of the enzyme under investigation were similar to those of α-amylases excreted from molds producing large amounts of the enzyme.
Survival of Natural Sewage Populations of Enteric Bacteria in Diffusion and Batch Chambers in the Marine Environment
Authors: Lessard Evelyn J. , Sieburth John McN.
Published: January 2020

The survival of natural populations of
Escherichia coli
and enterococci in sewage was measured in large-volume diffusion chambers in an estuary and a salt marsh. The 5-liter chambers, with polycarbonate membrane sidewalls, were found to be suitable for up to week-long experiments. Decay rates, measured monthly from February to August 1978, ranged from 0.042 to 0.088 h
−1
(time for 90% of the population to die = 25 to 55 h) for
E. coli
and 0.019 to 0.083 h
−1
(time for 90% of the population to die = 29 to 122 h) for enterococci and were significantly correlated with temperature. In contrast to the diffusion culture experiments, the decay of
E. coli
in batch culture did not correlate with temperature. Enterococci survived longer than
E. coli
in the Narragansett Bay (estuary) experiments, but survived less well in the more eutrophic salt marsh. The effect of light on survival was examined with light/dark experiments and sampling at frequent intervals over the diel cycle. Diel changes in survival were not evident in the Narragansett Bay experiments.
E. coli
, however, exhibited a diel pattern of growth during the day and death at night in the salt marsh. There was no significant difference in decay rates between light and dark diffusion chambers, nor were decay rates correlated with light intensity. In concurrent batch experiments, survival was significantly greater in the dark for both organisms. These results suggest that the effect of light is complex and that conditions in batch culture may modify the survival of enteric bacteria. Observations made in diffusion chambers may more closely follow the in situ survival of enteric microorganisms.
Occurrence and pathogenicity of Naegleria fowleri in artificially heated waters
Authors: Sykora J L , Keleti G , Martinez A J
Published: January 2020

The occurrence of pathogenic Naegleria fowleri in thermal discharges, recipient waters, and cooling towers of eight power plants located in western Pennsylvania was investigated for 2 years in conjunction with several environmental measurements. Pathogenic N. fowleri was detected in one cooling tower and in the discharge, receiving waters, or both of five of eight localities. The occurrence of this organism was related to elevated temperatures, but no significant correlation was found for other biological and chemical parameters. Laboratory experiments on the effect of pH on pathogenic N. fowleri documented 100% survival at a range from 2.1 to 8.15. Higher pH reduced or killed the amoebae. No case of human primary amoebic meningoencephalitis occurred during the study.
Metabolic effects of low aflatoxin B1 levels on broiler chicks
Authors: Maurice D V , Bodine A B , Rehrer N J
Published: January 2020

The effects of daily ingestion of aflatoxin B1 (AFB1) on growth, feed intake, plasma glucose, plasma cholesterol, plasma amino acids, plasma albumin, plasma ceruloplasmin, muscle amino acids, liver lipid, and bone strength were studied. For 3 weeks, beginning at an age of 2 days, broiler chicks were dosed daily per os with 50 or 100 micrograms of AFB1 per kg of body weight. Body weight and feed consumption were recorded daily, and metabolic responses were determined at 3 weeks. Treatment with AFB1 did not significantly alter body weight or feed intake. Relative liver weight showed a significant increase at the highest dose, with a significant concomitant increase in liver lipid and decrease in hepatic zinc. Relative spleen and heart weights were not affected by the toxin. Plasma glucose and cholesterol were significantly elevated at the highest dose. AFB1 significantly decreased plasma lysine and histidine and significantly increased muscle histidine, arginine, and valine. AFB1 decreased plasma albumin and markedly increased plasma ceruloplasmin. Dimensions of the long bones (femur and tibiotarsus) were not altered by the toxin. However, AFB1 caused a significant linear decline in the resistance of bone to breakage ("bone breaking strength"). The results indicate that low levels of AFB1 reduced bone strength in broiler chicks. The alterations in blood parameters indicated that AFB1 can disrupt metabolism even at low levels.
Buoyant Densities and Dry-Matter Contents of Microorganisms: Conversion of a Measured Biovolume into Biomass
Authors: Bakken Lars R. , Olsen Rolf A.
Published: January 2020

Several isolates of bacteria and fungi from soil, together with cells released directly from soil, were studied with respect to buoyant density and dry weight. The specific volume (cubic centimeters per gram) of wet cells as measured in density gradients of colloidal silica was correlated with the percent dry weight of the cells and found to be in general agreement with calculations based on the partial specific volume of major cell components. The buoyant density of pure bacterial cultures ranged from 1.035 to 1.093 g/cm
3
, and their dry-matter content ranged from 12 to 33% (wt/wt). Average values proposed for the conversion of bacterial biovolume into biomass dry weight are 1.09 g/cm
3
and 30% dry matter. Fungal hyphae had buoyant densities ranging from 1.08 to 1.11 g/cm
3
, and their dry-matter content ranged from 18 to 25% (wt/wt). Average values proposed for the conversion of hyphal biovolume into biomass dry weight are 1.09 g/cm
3
and 21% dry matter. Three of the bacterial isolates were found to have cell capsules. The calculated buoyant density and percent dry weight of these capsules varied from 1.029 g/cm
3
and 7% dry weight to 1.084 g/cm
3
and 44% dry weight. The majority of the fungi were found to produce large amounts of extracellular material when grown in liquid cultures. This material was not produced when the fungi were grown on either sterile spruce needles or membrane filters on an agar surface. Fungal hyphae in litter were shown to be free from extracellular materials.
Effects of storage on microbial loads of two commercially important shellfish species, Crassostrea virginica and Mercenaria campechiensis
Authors: Hood M A , Ness G E , Rodrick G E , Blake N J
Published: January 2020

The effects of storage on the microbial load in two commercially important species of shellfish were examined. Oysters (Crassostrea virginica) were stored as shellstock, shucked meats, and fully processed meats at four temperatures for up to 21 days, and clams (Mercenaria campechiensis) were stored only as shellstock. The concentrations of most microbiological groups of organisms increased with the duration and temperature of storage in both shellfish species, although the increases were significantly lower in claims. Concentrations of Vibrio cholerae rose by approximately 1 log in oysters stored as shellstock after 7 days at 2 degrees C, and Lac+ vibrios increased 2 logs at 8 degrees C. Total counts of bacteria, fungi, coliforms, fecal streptococci, Aeromonas hydrophila, and clostridia were significantly higher in shucked oysters than in those stored as shellstock. Fecal coliforms were statistically the same, but V. cholerae, Vibrio parahaemolyticus, and the Lac+ vibrios were higher in oysters stored as shellstock. The concentrations of all microbial groups were higher in fully processed oysters than in shucked meats, with the exception of the vibrios, which showed no significant difference among the treatments. The results showed that although traditional methods of storing shellfish resulted in an overall increase in the microbial load, vibrio levels increased only in oysters stored as shellstock. Although fecal coliform and total bacterial counts did not correlate with those for vibrios in fresh oysters, strong correlations were observed in oysters stored for 7 days, suggesting that these indicators may be useful in monitoring oyster quality when meats are stored for a limited time as shellstock.
Colorless Sulfur Bacteria,
Beggiatoa
spp. and
Thiovulum
spp., in O
2
and H
2
S Microgradients
Authors: Jørgensen Bo B. , Revsbech Niels P.
Published: January 2020

The interactions between colorless sulfur bacteria and the chemical microgradients at the oxygen-sulfide interface were studied in
Beggiatoa
mats from marine sediments and in
Thiovulum
veils developing above the sediments. The gradients of O
2
, H
2
S, and pH were measured by microelectrodes at depth increments of 50 μm. An unstirred boundary layer in the water surrounding the mats and veils prevented microturbulent or convective mixing of O
2
and H
2
S. The two substrates reached the bacteria only by molecular diffusion through the boundary layer. The bacteria lived as microaerophiles or anaerobes even under stirred, oxic water. Oxygen and sulfide zones overlapped by 50 μm in the bacterial layers. Both compounds had concentrations in the range of 0 to 10 μmol liter
−1
and residence times of 0.1 to 0.6 s in the overlapping zone. The sulfide oxidation was purely biological. Diffusion calculations showed that formation of mats on solid substrates or of veils in the water represented optimal strategies for the bacteria to achieve a stable microenvironment, a high substrate supply, and an efficient competition with chemical sulfide oxidation. The continuous gliding movement of
Beggiatoa
cells in mats or the flickering motion of
Thiovulum
cells in veils were important for the availability of both O
2
and H
2
S for the individual bacteria.
Photoproduction of H
2
from Cellulose by an Anaerobic Bacterial Coculture
Authors: Odom James M. , Wall Judy D.
Published: January 2020

Cellulomonas
sp. strain ATCC 21399 is a facultatively anaerobic, cellulose-degrading microorganism that does not evolve hydrogen but produces organic acids during cellulose fermentation.
Rhodopseudomonas capsulata
cannot utilize cellulose, but grows photoheterotrophically under anaerobic conditions on organic acids or sugars. This report describes an anaerobic coculture of the
Cellulomonas
strain with wild-type
R. capsulata
or a mutant strain lacking uptake hydrogenase, which photoevolves molecular hydrogen by the nitrogenase system of
R. capsulata
with cellulose as the sole carbon source. In coculture, the hydrogenase-negative mutant produced 4.6 to 6.2 mol of H
2
per mol of glucose equivalent, compared with 1.2 to 4.3 mol for the wild type.
Methanogenesis from Methanol and Methylamines and Acetogenesis from Hydrogen and Carbon Dioxide in the Sediments of a Eutrophic Lake
Authors: Lovley Derek R. , Klug Michael J.
Published: January 2020

14
C-tracer techniques were used to examine the metabolism of methanol and methylamines and acetogenesis from hydrogen and carbon dioxide in sediments from the profundal and littoral zones of eutrophic Wintergreen Lake, Michigan. Methanogens were primarily responsible for the metabolism of methanol, monomethylamine, and trimethylamine and maintained the pool size of these substrates below 10 μM in both sediment types. Methanol and methylamines were the precursors for less than 5 and 1%, respectively, of the total methane produced. Methanol and methylamines continued to be metabolized to methane when the sulfate concentration in the sediment was increased to 20 mM. Less than 2% of the total acetate production was derived from carbon dioxide reduction. Hydrogen consumption by hydrogen-oxidizing acetogens was 5% or less of the total hydrogen uptake by acetogens and methanogens. These results, in conjunction with previous studies, emphasize that acetate and hydrogen are the major methane precursors and that methanogens are the predominant hydrogen consumers in the sediments of this eutrophic lake.
Occurrence of the Rumen Ciliate
Oligoisotricha bubali
in Domestic Cattle (
Bos taurus
)
Authors: Dehority B. A. , Damron W. S. , McLaren J. B.
Published: January 2020

Oligoisotricha bubali
, previously observed twice in water buffalo, was detected in rumen contents of domestic cattle (
Bos taurus
) in two different areas of Tennessee. Concentrations ranged from <1 to 35% of the total protozoa in unweaned calves and up to 72% in older animals in feedlot. In contrast to the other genera of holotrichs, both total numbers and percent composition of
O. bubali
increased when animals were fed a corn silage-concentrate diet.
Differing L-alanine germination requirements of hypochlorite-treated Clostridium botulinum spores from two crops
Authors: Foegeding P M , Busta F F
Published: January 2020

Similar populations of hypochlorite-treated spores were enumerated from two crops of Clostridium botulinum 12885A produced by the same procedure; however, germination required different L-alanine concentrations. Lactate permitted the germination of spores from both crops with suboptimal L-alanine concentrations. The data suggest that the spores differ slightly in chemical or structural composition.
Phytol Degradation by Marine Bacteria
Authors: Gillan Francis T. , Nichols Peter D. , Johns R. B. , Bavor H. John
Published: January 2020

Microbial degradation of phytol is often proposed to be the primary source of the acyclic isoprenoid acids observed in sediments, yet only a limited number of these acids have been found in bacterial cultures grown on phytol. This study reports detailed capillary gas chromatography and gas chromatography-mass spectrometry analyses of the products resulting from growth of marine bacteria on phytol as the sole carbon source. We examined two strains of bacteria which were able to oxidize phytol to phytenic acid but were unable to further degrade phytol. The third isolate studied converted phytol to a mixture of five saturated isoprenoid acids. The C
17
isoprenoid acid produced was of particular interest, since its genesis from phytol would have involved several unusual intermediates. It is suggested that this acid is produced by bacterial metabolism of the C
18
isoprenoid ketone (produced from phytol abiologically under oxic conditions) and that its abundance is thus a sensitive indicator of sedimentary depositional conditions.
Threonine production by ethionine-resistant mutants of Serratia marcescens
Authors: Komatsubara S , Kisumi M , Chibata I
Published: January 2020

Ethionine reduced both the growth rate and the final growth level of Serratia marcescens Sr41. Growth inhibition was completely reversed by methionine. Strain D-315, defective in homoserine dehydrogenase I, was more sensitive to ethionine-mediated growth inhibition than was the wild-type strain. Ethionine-resistant mutants were isolated from cultures of strain D-316, which was derived from strain D-315 as a threonine deaminase-deficient mutant. Of 60 resistant colonies, 7 excreted threonine on minimal agar plates. One threonine-excreting strain, ETr17, was highly resistant to ethionine and, moreover, insensitive to methionine-mediated growth inhibition, whereas the parent strain was sensitive. When cultured in minimal medium with or without excess methionine, strain ETr17 had a higher homoserine dehydrogenase level than did strain D-316. The homoserine dehydrogenase activity was not inhibited by threonine or methionine. Transductional analysis revealed that the ethionine-resistant (etr-1) mutation carried by strain ETr17 was located in the metBM-argE region and caused the derepressed synthesis of homoserine dehydrogenase II. Strain ETr17 had a higher aspartokinase level than did the parent strain. By transductional cross with the argE+ marker, the etr-1 mutation was transferred into strain D-562 which was derived from D-505, a strain defective in aspartokinases I and III. The constructed strain had a higher aspartokinase level than did strain D-505 in medium with or without excess methionine, indicating that the etr-1 mutation led to the derepressed synthesis of aspartokinase II. Strain ETr17 produced about 8 mg of threonine per ml of medium containing sucrose and urea.
Nonlinear estimation of Monod growth kinetic parameters from a single substrate depletion curve
Authors: Robinson J A , Tiedje J M
Published: January 2020

Monod growth kinetic parameters were estimated by fitting sigmoidal substrate depletion data to the integrated Monod equation, using nonlinear least-squares analysis. When the initial substrate concentration was in the mixed-order region, nonlinear estimation of simulated data sets containing known measurement errors provided accurate estimates of the mu max, Ks, and Y values used to create these data. Nonlinear regression analysis of sigmoidal substrate depletion data was also evaluated for H2-limited batch growth of Desulfovibrio sp. strain G11. The integrated Monod equation can be more convenient for the estimation of growth kinetic parameters, particularly for gaseous substrates, but it must be recognized that the estimates of mu max, Ks, and Y obtained may be influenced by the growth rate history of the inoculum.
Biosynthesis of penitrems and roquefortine by Penicillium crustosum
Authors: Mantle P G , Perera K P , Maishman N J , Mundy G R
Published: January 2020

Roquefortine and the penitrems were biosynthesised concurrently at an approximately equimolar rate by Penicillium crustosum after growth and sporulation. [14C]mevalonic acid was incorporated (15% efficiency) into the isoprenoid regions of the penitrem and roquefortine molecules to an extent consistent with their 6:1 molar ratio of isoprenoid components. [14C]penitrem A (specific activity, 3.4 X 10(2) mu Ci mmol-1) and 14C-penitrems B, C, and E readministered to young cultures were metabolically interconverted, indicating considerable metabolic flux, though generally directed towards penitrem A as the end product and suggesting a metabolic grid for the penitrem metabolites. Addition of bromide to the medium preferentially favored the production of bromo-analogs rather than the usual chloropenitrems.
Hydrogen Metabolism by Decomposing Cyanobacterial Aggregates in Big Soda Lake, Nevada
Authors: Oremland Ronald S.
Published: January 2020

Hydrogen production by incubated cyanobacterial epiphytes occurred only in the dark, was stimulated by C
2
H
2
, and was inhibited by O
2
. Addition of NO
3
−
inhibited dark, anaerobic H
2
production, whereas the addition of NH
4
+
inhibited N
2
fixation (C
2
H
2
reduction) but not dark H
2
production. Aerobically incubated cyanobacterial aggregates consumed H
2
, but light-incubated rates (3.6 μmol of H
2
g
−1
h
−1
) were statistically equivalent to dark uptake rates (4.8 μmol of H
2
g
−1
h
−1
), which were statistically equivalent to dark, anaerobic production rates (2.5 to 10 μmol of H
2
g
−1
h
−1
). Production rates of H
2
were fourfold higher for aggregates in a more advanced stage of decomposition. Enrichment cultures of H
2
-producing fermentative bacteria were recovered from freshly harvested, H
2
-producing cyanobacterial aggregates. Hydrogen production in these cyanobacterial communities appears to be caused by the resident bacterial flora and not by the cyanobacteria. In situ areal estimates of dark H
2
production by submerged epiphytes (6.8 μmol of H
2
m
−2
h
−1
) were much lower than rates of light-driven N
2
fixation by the epiphytic cyanobacteria (310 μmol of C
2
H
4
m
−2
h
−1
).
Effects of Metals on Methanogenesis, Sulfate Reduction, Carbon Dioxide Evolution, and Microbial Biomass in Anoxic Salt Marsh Sediments
Authors: Capone Douglas G. , Reese Dwight D. , Kiene Ronald P.
Published: January 2020

The effects of several metals on microbial methane, carbon dioxide, and sulfide production and microbial ATP were examined in sediments from
Spartina alterniflora
communities. Anaerobically homogenized sediments were amended with 1,000 ppm (ratio of weight of metal to dry weight of sediment) of various metals. Time courses in controls were similar for CH
4
, H
2
S, and CO
2
, with short initial lags (0 to 4 h) followed by periods of constant gas production (1 to 2 days) and declining rates thereafter. Comparisons were made between control and experimental assays with respect to initial rates of production (after lag) and overall production. Methane evolution was inhibited both initially and overall by CH
3
HgCl, HgS, and NaAsO
2
. A period of initial inhibition was followed by a period of overall stimulation with Hg, Pb, Ni, Cd, and Cu, all as chlorides, and with ZnSO
4
, K
2
CrO
4
, and K
2
Cr
2
O
7
. Production of CO
2
was generally less affected by the addition of metals. Inhibition was noted with NaAsO
2
, CH
3
HgCl, and Na
2
MoO
4
. Minor stimulation of CO
2
production occurred over the long term with chlorides of Hg, Pb, and Fe. Sulfate reduction was inhibited in the short term by all metals tested and over the long term by all but FeCl
2
and NiCl
2
. Microbial biomass was decreased by FeCl
2
, K
2
Cr
2
O
7
, ZnSO
4
, CdCl
2
, and CuCl
2
but remained generally unaffected by PbCl
2
, HgCl
2
, and NiCl
2
. Although the majority of metals produced an immediate inhibition of methanogenesis, for several metals this was only a transient phenomenon followed by an overall stimulation. The initial suppression of methanogenesis may be relieved by precipitation, complexation, or transformation of the metal (possibly by methylation), with the subsequent stimulation resulting from a sustained inhibition of competing organisms (e.g., sulfate-reducing bacteria). For several environmentally significant metals, severe metal pollution may substantially alter the flow of carbon in sediments.
Physiology of Ex Planta Nitrogenase Activity in
Rhizobium japonicum
Authors: Agarwal Arun K. , Keister Donald L.
Published: January 2020

Thirty-nine wild-type strains of
Rhizobium japonicum
have been studied for their ability to synthesize nitrogenase ex planta in defined liquid media under microaerobic conditions. Twenty-one produced more than trace amounts of acetylene reduction activity, but only a few of these yielded high activity. The oxygen response curves were similar for most of the nitrogenase-positive strains. The strains derepressible for activity had several phenotypic characteristics different from non-derepressible strains. These included slower growth and lower oxygen consumption under microaerobic conditions and lower extracellular polysaccharide production. Extracellular polysaccharide production during growth on gluconate in every nitrogenase-positive strain assayed was lower under both aerobic and microaerobic conditions than the non-derepressible strains. These phenotypic characteristics may be representative of a genotype of a subspecies of
R. japonicum.
These studies were done in part to enlarge the base number of strains available for studies on the physiology, biochemistry, and genetics of nitrogen fixation.
Bacterioplankton in Antarctic Ocean Waters During Late Austral Winter: Abundance, Frequency of Dividing Cells, and Estimates of Production
Authors: Hanson R. B. , Shafer David , Ryan Theresa , Pope Daniel H. , Lowery H. Kenneth
Published: January 2020

Bacterioplankton productivity in Antarctic waters of the eastern South Pacific Ocean and Drake Passage was estimated by direct counts and frequency of dividing cells (FDC). Total bacterioplankton assemblages were enumerated by epifluorescent microscopy. The experimentally determined relationship between in situ FDC and the potential instantaneous growth rate constant (μ) is best described by the regression equation ln μ = 0.081 FDC − 3.73. In the eastern South Pacific Ocean, bacterioplankton abundance (2 × 10
5
to 3.5 × 10
5
cells per ml) and FDC (11%) were highest at the Polar Front (Antarctic Convergence). North of the Subantarctic Front, abundance and FDC were between 1 × 10
5
to 2 × 10
5
cells per ml and 3 to 5%, respectively, and were vertically homogeneous to a depth of 600 m. In Drake Passage, abundance (10 × 10
5
cells per ml) and FDC (16%) were highest in waters south of the Polar Front and near the sea ice. Subantarctic waters in Drake Passage contained 4 × 10
5
cells per ml with 4 to 5% FDC. Instantaneous growth rate constants ranged between 0.029 and 0.088 h
−1
. Using estimates of potential μ and measured standing stocks, we estimated productivity to range from 0.62 μg of C per liter · day in the eastern South Pacific Ocean to 17.1 μg of C per liter · day in the Drake Passage near the sea ice.
Initial Effects of the Mount St. Helens Eruption on Nitrogen Cycle and Related Chemical Processes in Ryan Lake
Authors: Dahm Clifford N. , Baross John A. , Ward Amelia K. , Lilley Marvin D. , Sedell James R.
Published: January 2020

Ryan Lake, a 1.6-hectare basin lake near the periphery of the tree blowdown area in the blast zone 19 km north of Mount St. Helens, was studied from August to October 1980 to determine the microbial and chemical response of the lake to the eruption. Nutrient enrichment through the addition of fresh volcanic material and the organic debris from the surrounding conifer forest stimulated intense microbial activity. Concentrations of such nutrients as phosphorus, sulfur, manganese, iron, and dissolved organic carbon were markedly elevated. Nitrogen cycle activity was especially important to the lake ecosystem in regulating biogeochemical cycling owing to the limiting abundance of nitrogen compounds. Nitrogen fixation, both aerobic and anaerobic, was active from aerobic benthic and planktonic cyanobacteria with rates up to 210 nmol of N
2
cm
−1
h
−1
and 667 nmol of N
2
liter
−1
h
−1
, respectively, and from anaerobic bacteria with rates reaching 220 nmol of N
2
liter
−1
h
−1
. Nitrification was limited to the aerobic epilimnion and littoral zones where rates were 43 and 261 nmol of NO
2
liter
−1
day
−1
, respectively. Potential denitrification rates were as high as 30 μmol of N
2
O liter
−1
day
−1
in the anaerobic hypolimnion. Total bacterial numbers ranged from 1 × 10
6
to 3 × 10
8
ml
−1
with the number of viable sulfur-metal-oxidizing bacteria reaching 2 × 10
6
ml
−1
in the hypolimnion. A general scenario for the microbial cycling of nitrogen, carbon, sulfur, and metals is presented for volcanically impacted lakes. The important role of nitrogen as these lakes recover from the cataclysmic eruption and proceed back towards their prior status as oligotrophic alpine lakes is emphasized.
Comparison between direct methods for determination of microbial cell volume: electron microscopy and electronic particle sizing
Authors: Montesinos E , Esteve I , Guerrero R
Published: January 2020

Size frequency distributions of different phototrophic and heterotrophic microorganisms were determined by means of scanning and transmission electron microscopy and electronic particle sizing. Statistically significant differences existed among the three techniques used in this study. Cells processed for electron microscopy showed lower mean cellular volumes than those processed for electronic particle sizing, reflecting a shrinkage by factors ranging from 1.1 to 6.2 (mean, 2.3). Processing of cells for scanning electron microscopy caused higher shrinkage than processing for transmission electron microscopy. Shrinkage was dependent neither on the size nor on the cell wall type of the microorganism. When processed for scanning electron microscopy, phototrophic bacteria were strongly shrunken, whereas heterotrophic microorganisms were less affected. A direct relationship existed among phototrophic bacteria between percentage of shrinkage and specific pigment content. This was probably a consequence of the pigment extraction by organic solvents during the dehydration process, previous to the critical point drying, necessary to examine the specimens under the scanning electron microscope.
Isolation and Partial Characterization of Two
Aeromonas hydrophila
Bacteriophages
Authors: Chow Mitchell S. , Rouf M. A.
Published: January 2020

Two
Aeromonas hydrophila
bacteriophages, Aeh1 and Aeh2, were isolated from sewage. Both phages showed binal symmetry. The dimensions of
A. hydrophila
phages Aeh1 and Aeh2 differed from those of the other
Aeromonas
phages. Also, phage Aeh2 was the largest
Aeromonas
phage studied to date. Phage Aeh1 formed small, clear plaques, and phage Aeh2 formed turbid plaques with clear centers. Both phages were sensitive to chloroform treatment, being totally inactivated after treatment for 1 h at 60°C at pH 3 and 11. However, the infectivity of Aeh1 phage stocks increased by approximately fivefold after they were treated at pH 10 for 1 h at 22°C. Phages Aeh1 and Aeh2 were serologically unrelated and had latent periods of 39 and 52 min, respectively. The average burst sizes of phages Aeh1 and Aeh2 were 17 and 92 PFU per cell, respectively. Phage Aeh1 infected 13 of 22
A. hydrophila
strains tested, whereas phage Aeh2 infected only its original host. Phage Aeh1 infected some
A. hydrophila
strains only at or below 37°C. Neither phage infected the two
A.
(
Plesiomonas
)
shigelloides
strains used in this study.
Recovery from nutrient starvation by a marine Vibrio sp
Authors: Amy P S , Pauling C , Morita R Y
Published: January 2020

A marine psychrophilic Vibrio sp., Ant-300, recovered from starvation after the addition of 1 volume of complete nutrient medium to 9 volumes of starvation menstruum. Turbidity (measured by optical density), viable cell counts, cell size (measured from electron micrographs), and cellular concentrations of protein, DNA, and RNA were monitored with recovery time. The usual growth curve of bacterial cultures was observed. On a per viable cell basis, protein, DNA, and RNA increased to maximum values just before cell division and then returned to close to the initial starved-cell value during the stationary phase. Cells under complete starvation conditions or missing only one nutrient in the stationary phase responded with cell division resulting in many smaller cells. The length of the lag phase during recovery was directly proportional to the length of the prior starvation period, even when identical numbers of cells were used for recovery. Cells appeared to pass more deeply into dormancy with starvation time.
Estimating Bacterioplankton Production by Measuring [
3
H]thymidine Incorporation in a Eutrophic Swedish Lake
Authors: Bell Russell T. , Ahlgren Gunnel M. , Ahlgren Ingemar
Published: January 2020

Bacterioplankton abundance, [
3
H]thymidine incorporation,
14
CO
2
uptake in the dark, and fractionated primary production were measured on several occasions between June and August 1982 in eutrophic Lake Norrviken, Sweden. Bacterioplankton abundance and carbon biomass ranged from 0.5 � 10
9
to 2.4 � 10
9
cells liter
−1
and 7 to 47 μg of C liter
−1
, respectively. The average bacterial cell volume was 0.185 μm
3
. [
3
H]thymidine incorporation into cold-trichloroacetic acid-insoluble material ranged from 12 � 10
−12
to 200 � 10
−12
mol liter
−1
h
−1
. Bacterial carbon production rates were estimated to be 0.2 to 7.1 μg of C liter
−1
h
−1
. Bacterial production estimates from [
3
H]thymidine incorporation and
14
CO
2
uptake in the dark agreed when activity was high but diverged when activity was low and when blue-green algae (cyanobacteria) dominated the phytoplankton. Size fractionation indicated negligible uptake of [
3
H]thymidine in the >3-μm fraction during a chrysophycean bloom in early June. We found that >50% of the
3
H activity was in the >3-μm fraction in late August; this phenomenon was most likely due to
Microcystis
spp., their associated bacteria, or both. Over 60% of the
14
CO
2
uptake in the dark was attributed to algae on each sampling occasion. Algal exudate was an important carbon source for planktonic bacteria. Bacterial production was roughly 50% of primary production.
Influence of Environmental Factors and Medium Composition on
Vibrio gazogenes
Growth and Prodigiosin Production
Authors: Allen Garry R. , Reichelt John L. , Gray Peter P.
Published: January 2020

Vibrio gazogenes
ATCC 29988 growth and prodigiosin synthesis were studied in batch culture on complex and defined media and in chemostat cultures on defined medium. In batch culture on complex medium, a maximum growth rate of 0.75 h
−1
and a maximum prodigiosin concentration of 80 ng of prodigiosin � mg of cell protein
−1
were observed. In batch culture on defined medium, maximum growth rates were lower (maximum growth rate, 0.40 h
−1
), and maximum prodigiosin concentrations were higher (1,500 ng � mg of protein
−1
). In batch culture on either complex or defined medium, growth was characterized by a period of logarithmic growth followed by a period of linear growth; on either medium, prodigiosin biosynthesis was maximum during linear growth. In batch culture on defined medium, the initial concentration of glucose optimal for growth and pigment production was 3.0%; higher levels of glucose suppressed synthesis of the pigment.
V. gazogenes
had an absolute requirement for Na
+
; optimal growth occurred in the presence of 100 mM NaCl. Increases in the concentration of Na
+
up to 600 mM resulted in further increases in the concentration of pigment in the broth. Prodigiosin was synthesized at a maximum level in the presence of inorganic phosphate concentrations suboptimal for growth. Concentrations of KH
2
PO
4
above 0.4 mM caused decreased pigment synthesis, whereas maximum cell growth occurred at 1.0 mM. Optimal growth and pigment production occurred in the presence of 8 to 16 mg of ferric ion � liter
−1
, with higher concentrations proving inhibitory to both growth and pigment production. Both growth and pigment production were found to decrease with increased concentrations of
p
-aminobenzoic acid. The highest specific concentration of prodigiosin (3,480 ng � mg protein
−1
) was observed in chemostat cultures at a dilution rate of 0.057 h
−1
. The specific rate of prodigiosin production at this dilution rate was approximately 80% greater than that observed in batch culture on defined medium. At dilution rates greater than 0.057 h
−1
, the concentration of cells decreased with increasing dilution rate, resulting in a profile comparable to that expected for linear growth kinetics. No explanation could be found for the linear growth profiles obtained for both batch and chemostat cultures.
Decolorization of Several Polymeric Dyes by the Lignin-Degrading Basidiomycete
Phanerochaete chrysosporium
Authors: Glenn Jeffrey K. , Gold Michael H.
Published: January 2020

The polymeric dyes Poly B-411, Poly R-481, and Poly Y-606 were examined as possible alternatives to the radiolabeled lignin previously used as a substrate in lignin biodegradation assays. Like lignin degradation, the decolorization of these dyes by the white rot basidiomycete
Phanerochaete chrysosporium
occurred during secondary metabolism, was suppressed in cultures grown in the presence of high levels of nitrogen, and was strongly dependent on the oxygen concentration in the cultures. A variety of inhibitors of lignin degradation, including thiourea, azide, and 4′-
O
-methylisoeugenol, also inhibited dye decolorization. A pleiotropic mutant of
P. chrysosporium
, 104-2, lacking phenol oxidase and ligninolytic activity was also not able to decolorize the polymeric dyes, whereas a phenotypic revertant strain, 424-2, regained this capacity. All of these results suggest that the ligninolytic degradation activity of the fungus was responsible for the decolorization of these dyes.
Protein Patterns of Growing and Starved Cells of a Marine
Vibrio
sp
Authors: Amy Penny S. , Morita Richard Y.
Published: January 2020

Fingerprint protein patterns were produced by two-dimensional polyacrylamide electrophoresis on lysed cells of a
Vibrio
sp., Ant-300, which were prepared from growing and starved cultures. The cells were labeled with [
35
S]methionine during growth and subsequently starved for up to 30 days. Samples were taken at selected time points representing stages in the starvation-survival process. Unlabeled starved cells were allowed to recover in the presence of [
35
S]methionine to determine protein changes associated with the recovery from starvation. All growth conditions produced similar protein fingerprints; however, some protein spots disappeared, whereas others were seen only during starvation.

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Isolation of proteolytic rumen bacteria by use of selective medium containing leaf fraction 1 protein (ribulosebisphosphate carboxylase)
Authors: Hazlewood G P , Orpin C G , Greenwood Y , Black M E
Published: January 2020

The principle proteolytic bacteria isolated from bovine rumen contents by virtue of the ability to obtain nitrogen from the proteolysis of leaf fraction 1 protein (ribulosebisphosphate carboxylase, EC 4.1.1.39) were identified as Streptococcus bovis and Butyrivibrio spp. Substitution of fresh fodder, rich in soluble protein, for a hay-concentrates diet resulted in enhanced ruminal proteolytic activity and a significant increase in the number of bacteria able to use fraction 1 protein as the sole nitrogen source. Isolated proteolytic bacteria degraded fraction 1 protein and casein readily. Bovine serum albumin was attacked by Butyrivibrio spp. but was resistant to proteolysis by the streptococci.