bluuebunny/crossref_metadata_2025 huggingface dataset:
Ammonium Excretion by an
l
-Methionine-
dl
-Sulfoximine-Resistant Mutant of the Rice Field Cyanobacterium
Anabaena siamensis
Authors: Thomas Selwin P. , Zaritsky Arieh , Boussiba Sammy
Published: January 2020

An ammonium-excreting mutant (SS1) of the rice field nitrogen-fixing cyanobacterium
Anabaena siamensis
was isolated after ethyl methanesulfonate mutagenesis by selection on 500 μM
l
-methionine-
dl
-sulfoximine. SS1 grew in the presence and absence of
l
-methionine-
dl
-sulfoximine at a rate comparable to that of the wild-type strain, with a doubling time of 5.6 h. The rate of ammonium release by SS1 depended on cell density; it peaked at the 12th hour of growth with 8.7 μmol mg of chlorophyll
−1
h
−1
(at a chlorophyll concentration of 5 μg ml
−1
) and slowed down to almost nil at the fourth day of growth. A similar pattern of release by immobilized SS1 was observed between 12 to 20 h after loading alginate beads in packed-bed reactors at the rate of 11.6 μmol mg of chlorophyll
−1
h
−1
. The rate was later reduced significantly due to the fast growth of SS1 on the substrate. Prolonged release of ammonium at the peak level was achieved only by maintaining SS1 under continuous cultivation at low chlorophyll levels (5 to 7 μg ml
−1
). Under these conditions, nitrogen fixation in the mutant was 30% higher than that in its parent and glutamine synthetase activity was less by 50%. Immunoblot analysis revealed that SS1 and its parent have similar quantities of glutamine synthetase protein under ammonium excretion conditions. In addition, a protein with a molecular weight of about 30,000 seems to have been lost, as seen by electrophoretic separation of total proteins from SS1.
Effect of Dicarboxylic Acids and
Aspergillus oryzae
Fermentation Extract on Lactate Uptake by the Ruminal Bacterium
Selenomonas ruminantium
Authors: Nisbet David J. , Martin Scott A.
Published: January 2020

The objective of this study was to determine the effects of
l
-aspartate, fumarate,
l
-malate, and an
Aspergillus oryzae
fermentation extract (Amaferm) on growth on lactate as well as lactate uptake by
Selenomonas ruminantium
HD4. Growth of
S. ruminantium
in medium that contained 2 g of
dl
-lactate per liter was stimulated approximately twofold by 10 mM
l
-aspartate, fumarate, or
l
-malate after 24 h. Both
l
-aspartate and fumarate increased lactate uptake over 4-fold, while
l
-malate stimulated uptake over 10-fold. Amaferm enhanced lactate uptake at all concentrations tested (0.5 to 50 g/liter), and the 10-g/liter level increased uptake over 12-fold. A filter-sterilized Amaferm filtrate increased lactate uptake over sevenfold, and growth on lactate was stimulated over twofold by either 2 or 5% (vol/vol) Amaferm filtrate. The Amaferm filtrate also increased the production of acetate, propionate, total volatile fatty acids, and
Y

lactate

from lactate-grown cells. Since the increase in propionate production was greater relative to acetate, a decrease in the acetate:propionate ratio was observed. The concentration of
l
-malate in the Amaferm filtrate was 1.45 mM, and it appeared that the
l
-malate content of Amaferm played a role in the stimulation of growth on lactate as well as lactate uptake by
S. ruminantium
treated with Amaferm.
Two Penicillium camembertii mutants affected in the production of cyclopiazonic acid
Authors: Geisen R , Glenn E , Leistner L
Published: January 2020

Penicillium camembertii was mutated and screened for cyclopiazonic acid-negative mutants. With a simple and rapid mini-extraction method for detection of cyclopiazonic acid production, we were able to isolate two strains which were affected in the production of this metabolite. One strain had completely lost the ability to synthesize detectable amounts of this secondary metabolite, whereas the other mutant produced 50 to 100 times less cyclopiazonic acid than the wild type. Also, the former strain had a changed morphology compared with the wild type. This morphological alteration appears to be coupled to the inability to produce cyclopiazonic acid because morphological revertants were able to synthesize cyclopiazonic acid to a level comparable to the wild type. The second mutant accumulated a new metabolite which was detectable by two-dimensional thin-layer chromatography. This new metabolite, however, appears not to be a direct precursor of cyclopiazonic acid.
Specific plate assay for bacterial heparinase
Authors: Zimmermann J J , Langer R , Cooney C L
Published: January 2020

A procedure was developed for detecting heparinase activity on heparin agar plates. The method is based on the differential precipitation of heparin and heparinase-generated heparin fragments by protamine sulfate. Heparinase activity is detected by the presence of clear zones against a white background. This method can be used to screen for the expression of recombinant heparinase and to identify Flavobacterium heparinum mutants expressing heparinase constitutively.
Ecophysiology of Bacteriophage S5100 Infecting
Halobacterium cutirubrum
Authors: Daniels Larry L. , Wais Allen C.
Published: January 2020

Increasing salinity reduces burst size and increases the latent period of infection of
Halobacterium cutirubrum
by lytic bacteriophage S5100. Cells become reversibly and persistently infected at saturation-level concentrations of NaCl. We propose that high salinity provides a natural refuge for sensitive host bacteria and that phage S5100 acts as a scavenger, proliferating when host viability is threatened by dilution of the environment.
Degradation of Alpha-, Beta-, and Gamma-Hexachlorocyclohexane by a Soil Bacterium under Aerobic Conditions
Authors: Sahu Siddhartha K. , Patnaik Kamala Kumari , Sharmila Manikonda , Sethunathan N.
Published: January 2020

A
Pseudomonas
sp., isolated from sugarcane rhizosphere soil, readily metabolized not only alpha and gamma isomers of hexachlorocyclohexane, but also the thermodynamically more stable beta isomer, under aerobic conditions. Bacterial degradation of the three isomers led to the accumulation of a transitory metabolite and eventual release of covalently linked chlorine as chloride in stoichiometric amounts.
Purification and characterization of acidolysin, an acidic metalloprotease produced by Clostridium acetobutylicum ATCC 824
Authors: Croux C , Paquet V , Goma G , Soucaille P
Published: January 2020

Acidolysin an extracellular protease produced by Clostridium acetobutylicum ATCC 824 was purified to homogeneity by anion-exchange chromatography with a recovery of 91%. The enzyme was a monomeric protein with a molecular weight of 44,000 as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and an acidic isoelectric point of 3.3. Acidolysin was very sensitive to metal-chelating agents and phosphoramidon and was unaffected by sulfhydryl reagents. It was shown to be a calcium- and zinc-containing protease. It exhibited optimal activity against Azocoll at pH 5 and 45 degrees C. It was stable at low pH and heat labile above 50 degrees C. It exhibited specificity toward peptide bonds formed by the amino group of hydrophobic amino acids (isoleucine, leucine, and phenylalanine) and its NH2-terminal amino acid sequence showed a high degree of similarity with that of Bacillus subtilis neutral metalloprotease A. Acidolysin is the first phosphoramidon-sensitive, acidic zinc metalloprotease reported.
Extracellular beta-galactosidase activity of a Fibrobacter succinogenes S85 mutant able to catabolize lactose
Authors: Javorsky P , Lee S F , Gibbins A M , Forsberg C W
Published: January 2020

Fibrobacter succinogenes S85 is unable to grow with lactose as the source of carbohydrate, although it does exhibit low beta-galactosidase (EC 3.2.1.23) activity. Spontaneous mutants of strain S85 able to grow on lactose were isolated after spreading cells on a chemically defined agar medium with lactose as the carbohydrate source. A lactose-catabolizing isolate, designated L2, exhibited a sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein profile and an immunoblot profile with polyclonal antibodies to whole cells of S85 which were identical to those observed for S85. Strain L2 exhibited both cell-associated and extracellular beta-galactosidase activity with either p-nitrophenyl-beta-D-galactopyranoside or lactose as the substrate. The cell-associated enzyme exhibited the greatest activity in the periplasmic space. Enzyme production was partially inhibited by glucose. The beta-galactosidase was activated by divalent cations and exhibited a pH optimum of 6.5. Analysis of the extracellular culture fluid revealed that glucose derived from the hydrolysis of lactose was used for growth, but galactose was not metabolized further. Cells were unable to take up the lactose analog, methyl-beta-D-thiogalactopyranoside. These data suggest that beta-galactosidase of F. succinogenes L2 cleaves lactose outside the cells and that the glucose released is catabolized while the galactose accumulates in the extracellular culture fluid.
Degradation of the metal-cyano complex tetracyanonickelate(II) by cyanide-utilizing bacterial isolates
Authors: Silva-Avalos J , Richmond M G , Nagappan O , Kunz D A
Published: January 2020

Ten bacterial isolates capable of growth on tetracyanonickelate(II) [K2[Ni(CN)4]] (TCN) as the sole nitrogen source were isolated from soil, freshwater, and sewage sludge enrichments. Seven of the 10 were identified as pseudomonads, while the remaining 3 were classified as Klebsiella species. A detailed investigation of one isolate, Pseudomonas putida BCN3, revealed a rapid growth rate on TCN (generation time, 2 h), with substrate removal and growth occurring in parallel. In addition to TCN, all isolates were able to utilize KCN, although the latter was significantly more toxic; MICs ranged from 0.2 to 0.8 mM for KCN and greater than or equal to 50 mM for TCN. While growth occurred over a wide range of TCN concentrations (0.25 to 16 mM), degradation was most substantial under growth-limiting conditions and did not occur when ammonia was present. In addition, cells grown on TCN were found to accumulate nickel cyanide [Ni(CN)2] as a major biodegradation product. The results show that bacteria capable of growth on TCN can readily be isolated and that degradation (i) appears to parallel the capacity for growth on KCN, (ii) does not occur in the presence of ammonia, and (iii) proceeds via the formation of Ni(CN)2 as a biological metabolite.
Volatile metabolites and other indicators of Penicillium aurantiogriseum growth on different substrates
Authors: Börjesson T , Stöllman U , Schnürer J
Published: January 2020

Penicillium aurantiogriseum Dierckx was cultivated on six agar substrates (barley meal agar, oat meal agar, wheat meal agar, malt extract agar, Czapek agar, and Norkrans agar) and on oat grain for 5 days in cultivation vessels provided with an inlet and an outlet for air. Volatile metabolites produced by the cultures were collected on a porous polymer adsorbent by passing an airstream through the vessel. Volatile metabolites were collected between days 2 and 5 after inoculation. CO2 production was simultaneously measured, and after the cultivation period ergosterol contents and the numbers of CFU of the cultures were determined. Alcohols of low molecular weight and sesquiterpenes were the dominant compounds found. During growth on oat grain the production of 8-carbon alcohols and 3-methyl-1-butanol was higher and the production of terpenes was lower than during growth on agar substrates. The compositions of the volatile metabolites from oat grain were more similar to those from wheat grain, which was used as a substrate in a previous investigation, than to those produced on any of the agar substrates. Regarding the agar substrates, the production of terpenes was most pronounced on the artificial substrates (Czapek agar and Norkrans agar) whereas alcohol production was highest on substrates based on cereals. The production of volatile metabolites was highly correlated with the production of CO2 and moderately correlated with ergosterol contents, whereas no correlation with the numbers of CFU was found. Thus, the volatile metabolites formed and the ergosterol contents of fungal cultures should be good indicators of present and past fungal activity.
Differentiation of Penicillium griseofulvum Dierckx isolates by enzyme assays and by patulin and griseofulvin analyses
Authors: Jimenez M , Mateo R , Querol A , Mateo J J , Hernandez E
Published: January 2020

The production of patulin and griseofulvin by 49 different isolates of Penicillium griseofulvum Dierckx was analyzed by high-performance liquid chromatography. Eleven isolates were obtained from pistachio nuts, 37 were obtained from wheat seeds, and 1 was obtained from the American Type Culture Collection. Activities of 19 enzymes were also assayed by the API ZYM system. From these results it may be deduced that there are two different groups among the strains tested which cannot be distinguished by morphological and cultural characteristics. One group of isolates did not produce detectable amounts of patulin and griseofulvin when grown in sucrose-yeast extract and Wickerham media, while enzymatic activities were quantitatively distinct from the other group, which produced patulin and griseofulvin in variable proportions. Leucine arylamidase, phosphoamidase, and beta-D-glucosidase are the main enzymes with differing activities between the two groups. Differences in physiological characteristics among isolates of a single species reveal shortcomings in the classification of the penicillia based only on morphological criteria. Thus, determination of the ability to yield mycotoxins and antibiotics as well as determination of enzymatic activities appear to be very valuable tools in the taxonomy of these fungi and for food toxicology.
Remnants of an ancient pathway to L-phenylalanine and L-tyrosine in enteric bacteria: evolutionary implications and biotechnological impact
Authors: Bonner C A , Fischer R S , Ahmad S , Jensen R A
Published: January 2020

The pathway construction for biosynthesis of aromatic amino acids in Escherichia coli is atypical of the phylogenetic subdivision of gram-negative bacteria to which it belongs (R. A. Jensen, Mol. Biol. Evol. 2:92-108, 1985). Related organisms possess second pathways to phenylalanine and tyrosine which depend upon the expression of a monofunctional chorismate mutase (CM-F) and cyclohexadienyl dehydratase (CDT). Some enteric bacteria, unlike E. coli, possess either CM-F or CDT. These essentially cryptic remnants of an ancestral pathway can be a latent source of biochemical potential under certain conditions. As one example of advantageous biochemical potential, the presence of CM-F in Salmonella typhimurium increases the capacity for prephenate accumulation in a tyrA auxotroph. We report the finding that a significant fraction of the latter prephenate is transaminated to L-arogenate. The tyrA19 mutant is now the organism of choice for isolation of L-arogenate, uncomplicated by the presence of other cyclohexadienyl products coaccumulated by a Neurospora crassa mutant that had previously served as the prime biological source of L-arogenate. Prephenate aminotransferase activity was not conferred by a discrete enzyme, but rather was found to be synonymous with the combined activities of aspartate aminotransferase (aspC), aromatic aminotransferase (tyrB), and branched-chain aminotransferase (ilvE). This conclusion was confirmed by results obtained with combinations of aspC-, tyrB-, and ilvE-deficient mutations in E. coli. An example of disadvantageous biochemical potential is the presence of a cryptic CDT in Klebsiella pneumoniae, where a mutant carrying multiple enzyme blocks is the standard organism used for accumulation and isolation of chorismate.(ABSTRACT TRUNCATED AT 250 WORDS)
Oxygen requirements of yeasts
Authors: Visser W , Scheffers W A , Batenburg-van der Vegte W H , van Dijken J P
Published: January 2020

Type species of 75 yeast genera were examined for their ability to grow anaerobically in complex and mineral media. To define anaerobic conditions, we added a redox indicator, resazurin, to the media to determine low redox potentials. All strains tested were capable of fermenting glucose to ethanol in oxygen-limited shake-flask cultures, even those of species generally regarded as nonfermentative. However, only 23% of the yeast species tested grew under anaerobic conditions. A comparative study with a number of selected strains revealed that Saccharomyces cerevisiae stands out as a yeast capable of rapid growth at low redox potentials. Other yeasts, such as Torulaspora delbrueckii and Candida tropicalis, grew poorly mu max, 0.03 and 0.05 h-1, respectively) under anaerobic conditions in mineral medium supplemented with Tween 80 and ergosterol. The latter organisms grew rapidly under oxygen limitation and then displayed a high rate of alcoholic fermentation. It can be concluded that these yeasts have hitherto-unidentified oxygen requirements for growth.
Characterization of Peroxidase Secretion and Subcellular Organization of
Phanerochaete chrysosporium
INA-12 in the Presence of Various Soybean Phospholipid Fractions
Authors: Capdevila Cecile , Moukha Serge , Ghyczy Miklos , Theilleux Jacques , Gelie Brigitte , Delattre Michel , Corrieu Georges , Asther Marcel
Published: January 2020

Stimulation of lignin peroxidase production by exogenous phospholipids depends on the composition of the phospholipid fraction prepared by using the Nattermann process. The fraction composed mainly of negatively charged phospholipids (NAT 89) was the most efficient source for exoprotein secretion by
Phanerochaete chrysosporium
INA-12. The results of biochemical marker assays and ultrastructural morphology determination by electron microscopy were correlated. Activities of succinate dehydrogenase, a mitochondrial marker, and cytochrome
c
oxidoreductase, an endoplasmic reticulum (ER) marker, were increased 1.3- and 2.2-fold, respectively, in the presence of NAT 89. Electron microscopy observations suggested that the amount of mitochondria and ER in culture containing phospholipids was increased at the optimum day of lignin peroxidase production. Therefore, phospholipids enhanced energetic metabolism of strain INA-12 and markedly modified fungus physiology. Since ER is involved in enzyme synthesis, we suggest that its increased amount in mycelium cultured with NAT 89 is directly associated with the higher production of lignin peroxidase.
Microflora of partially processed lettuce
Authors: Magnuson J A , King A D , Török T
Published: January 2020

Bacteria, yeasts, and molds isolated from partially processed iceberg lettuce were taxonomically classified. The majority of bacterial isolates were gram-negative rods. Pseudomonas, Erwinia, and Serratia species were commonly found. Yeasts most frequently isolated from lettuce included members of the genera Candida, Cryptococcus, Pichia, Torulaspora, and Trichosporon. Comparatively few molds were isolated; members of the genera Rhizopus, Cladosporium, Phoma, Aspergillus, and Penicillium were identified.
Cloning of the listeriolysin O gene and development of specific gene probes for Listeria monocytogenes
Authors: Datta A R , Wentz B A , Russell J
Published: January 2020

A clone containing 3.1 kb of Listeria DNA was selected from a gene library of Listeria monocytogenes Scott A strain. The Escherichia coli clone produced hemolysin on sheep blood agar and in sonicated extracts but very little in the culture supernatant. This 3.1-kb DNA fragment and a 650-bp HindIII fragment located within the listeriolysin gene were used as probes in a colony hybridization assay. Both probes were specific for L. monocytogenes and did not hybridize with any other Listeria strains at high stringency. Two synthetic probes, one from the 650-bp HindIII fragment and one from the carboxy-terminal region of the protein, were also specific for L. monocytogenes.
Sheen Screen, a Miniaturized Most-Probable-Number Method for Enumeration of Oil-Degrading Microorganisms
Authors: Brown Edward J. , Braddock Joan F.
Published: January 2020

Sheen Screen is a miniaturized method for enumerating oil-degrading microorganisms. The technique relies on the ability of oil-degrading microorganisms to emulsify oil when provided as a sole carbon source in 24-well tissue culture plates. Sediments that actively respire hydrocarbons have high numbers of Sheen Screen-positive microorganisms.
Aerobic and anaerobic growth of rifampin-resistant denitrifying bacteria in soil
Authors: Murray R E , Parsons L L , Smith M S
Published: January 2020

The growth and survival of several rifampin-resistant isolates of denitrifying bacteria were examined under anaerobic (denitrifying) and aerobic conditions. Two isolates added to nonsterile Bruno soil at densities of between 10(4) and 10(6) CFU g dry soil-1 exhibited an initial period of growth followed by a gradual decline in numbers. After 28 days, both isolates maintained viable populations of between 10(4) and 10(5) CFU g dry soil-1 under both denitrifying and aerobic conditions. One of the isolates consistently grew better under denitrifying conditions, and the other isolate consistently grew better under aerobic conditions. The relative pattern of denitrifying versus aerobic growth for each organism was not affected by the addition of glucose. The growth yields of the two isolates varied with soil type, but the relative pattern of denitrifying versus aerobic growth was consistent in three soils with greatly different properties. Five of nine isolates introduced into Bruno soil at low population densities (approximately 10(5) CFU g dry soil-1) exhibited better growth after 2 days under denitrifying conditions. It was not possible to predict the prevalence of the denitrifying or aerobic mode of growth in nonsterile soil from the growth characteristics of the isolates in pure cultures or sterile soil.
Bacterial conversion of glycerol to beta-hydroxypropionaldehyde
Authors: Vancauwenberge J E , Slininger P J , Bothast R J
Published: January 2020

beta-hydroxypropionaldehyde (3-HPA) can be oxidized to acrylic acid, an industrially important chemical used in the manufacture of synthetic plastics and other polymers. Of 19 genera and 55 strains tested, 3 Klebsiella and 2 Enterobacter strains produced 3-HPA. The most efficient strain was Klebsiella pneumoniae NRRL B-4011. Under optimum conditions (28 degrees C; 40 g of semicarbazide hydrochloride per liter, 70 g of glycerol per liter; and pH 6.0), 3.1 g of B-4011 cells per liter accumulated 22 g of 3-HPA per liter at a specific rate of 0.83 g/g per h; however, 14.5 g of cells per liter accumulated 46 g of 3-HPA per liter at a specific rate of 0.41 g/g per h.
Transfer of the toxin protein genes of Bacillus sphaericus into Bacillus thuringiensis subsp. israelensis and their expression
Authors: Bourgouin C , Del�cluse A , de la Torre F , Szulmajster J
Published: January 2020

The genes encoding the toxic determinants of Bacillus sphaericus have been expressed in a nontoxic and a toxic strain of Bacillus thuringiensis subsp. israelensis. In both cases, the B. sphaericus toxin proteins were produced at a high level during sporulation of B. thuringiensis and accumulated as crystalline structures. B. thuringiensis transformants expressing B. sphaericus and B. thuringiensis subsp. israelensis toxins did not show a significant enhancement of toxicity against Aedes aegypti, Anopheles stephensi, and Culex pipiens larvae.
Occurrence of a
Thiothrix
sp. Attached to Mayfly Larvae and Presence of Parasitic Bacteria in the
Thiothrix
sp
Authors: Larkin John M. , Henk Margaret C. , Burton Sheril D.
Published: January 2020

Larvae of the mayfly (
Drunella grandis
[Eaton]) from Diamond Fork Creek, Utah, were covered with a heavy growth of the sulfide-oxidizing bacterium
Thiothrix.
The bacterium did not seem to harm the mayfly, but the
Thiothrix
trichomes were parasitized by three morphologically distinct bacteria, two of which were cytoplasmic and one of which was probably periplasmic. At least two of the parasites destroyed the cytoplasmic contents of the
Thiothrix
sp., thus killing the host cell. Attempts to obtain the parasites in pure culture were unsuccessful.
Purification of DNA for bacterial productivity estimates
Authors: Burnison B K , Nuttley D J
Published: January 2020

[methyl-3H]thymidine-labeled DNA from natural populations of aquatic bacteria was completely separated from RNA and protein by hydroxylapatite chromatography. The procedure was validated by monitoring increases in Escherichia coli cell count, A550, DNA concentration, and thymidine incorporation into DNA isolated by the proposed technique. The procedure can be used in the field and does not rely on the use of acid-base hydrolysis or volatile organic solvents.
Rapid detection of chlorine-induced bacterial injury by the direct viable count method using image analysis
Authors: Singh A , Yu F P , McFeters G A
Published: January 2020

A modified direct viable count method to detect living bacteria was used with image analysis for the rapid enumeration of chlorine-injured cells in an Escherichia coli culture. The method was also used for determining chlorine-induced injury in coliform isolates and enteric pathogenic bacteria. Cultures were incubated in phosphate-buffered saline, containing 0.3% Casamino Acids (Difco Laboratories, Detroit, Mich.), 0.03% yeast extract, and optimal concentrations of nalidixic acid. Samples were withdrawn before and after incubation and stained with acridine orange, and cell lengths and breadths were measured by computerized image analysis. After incubation, cells which exceeded the mean preincubation length (viable cells) were enumerated and the results were compared with those obtained by the plate count method. Injury in the chlorine-exposed cell population was determined from the difference in viable count obtained with a nonselective Casamino Acids-yeast extract-nalidixic acid medium and a selective Casamino Acids-yeast extract-nalidixic acid medium containing sodium deoxycholate or sodium lauryl sulfate. The levels of injury determined by the direct viable count technique by using image analysis were comparable to those determined by the plate count method. The results showed that image analysis, under optimal conditions, enumerated significantly higher numbers of stressed E. coli than the plate count method did and detected injury in various cultures in 4 to 6 h.
Distribution of alginate gene sequences in the Pseudomonas rRNA homology group I-Azomonas-Azotobacter lineage of superfamily B procaryotes
Authors: Fialho A M , Zielinski N A , Fett W F , Chakrabarty A M , Berry A
Published: January 2020

Chromosomal DNA from group I Pseudomonas species, Azotobacter vinelandii, Azomonas macrocytogens, Xanthomonas campestris, Serpens flexibilis, and three enteric bacteria was screened for sequences homologous to four Pseudomonas aeruginosa alginate (alg) genes (algA, pmm, algD, and algR1). All the group I Pseudomonas species tested (including alginate producers and nonproducers) contained sequences homologous to all the P. aeruginosa alg genes used as probes, with the exception of P. stutzeri, which lacked algD. Azotobacter vinelandii also contained sequences homologous to all the alg gene probes tested, while Azomonas macrocytogenes DNA showed homology to all but algD. X. campestris contained sequences homologous to pmm and algR1 but not to algA or algD. The helical bacterium S. flexibilis showed homology to the algR1 gene, suggesting that an environmentally responsive regulatory gene similar to algR1 exists in S. flexibilis. Escherichia coli showed homology to the algD and algR1 genes, while Salmonella typhimurium and Klebsiella pneumoniae failed to show homology with any of the P. aeruginosa alg genes. Since all the organisms tested are superfamily B procaryotes, these results suggest that within superfamily B, the alginate genes are distributed throughout the Pseudomonas group I-Azotobacter-Azomonas lineage, while only some alg genes have been retained in the Pseudomonas group V (Xanthomonas) and enteric lineages.
Enhanced Yield of Shiitake by Saccharide Amendment of the Synthetic Substrate
Authors: Royse D. J. , Bahler B. D. , Bahler C. C.
Published: January 2020

Three experiments were performed to determine the effect of selected saccharides on mushroom yield and basidiome size of shiitake (
Lentinula edodes
) when grown on a synthetic substrate. Substrate formulations of sawdust, wheat bran, and millet were nonamended or amended with sucrose, fructose, or glucose. Addition of sucrose (0.6 to 1.2% [dry weight]) to the substrate stimulated mushroom yield by 11 to 20% or more. Addition of fructose at 1.2% and glucose at 0.6% resulted in similar yield increases. Most of the yield increase occurred on the first break. The substrate amended with 1.2% sucrose tended to have a more synchronous maturation for the second break resulting in fewer days when mushrooms were harvested.
Evidence that Escherichia coli accumulates glycine betaine from marine sediments
Authors: Ghoul M , Bernard T , Cormier M
Published: January 2020

Escherichia coli grew faster in autoclaved marine sediment than in seawater alone. When E. coli was cultivated in sediment diluted with minimal medium M63 at 0.6 M NaCl, supplemented or not supplemented with glucose or with seawater, the osmoprotector glycine betaine was accumulated in the cells. The best growth occurred on glucose. Accumulation of glycine betaine was not observed with E. coli was grown in sterile seawater alone. The fact that E. coli grew better in the sediments than in seawater is attributed somewhat to the high content of organic matter in the sediment but mainly to the accumulation of glycine betaine. Thus, osmoprotection should be considered to be an additional factor in bacterial survival in estuarine sediments.
Equilibrium temperature in a clump of bacteria heated in fluid
Authors: Davey K R
Published: January 2020

A theoretical model was developed and used to estimate quantitatively the "worst case", i.e., the longest, time to reach equilibrium temperature in the center of a clump of bacteria heated in fluid. For clumps with 10 to 10(6) cells heated in vapor, such as dry and moist air, and liquid fluids such as purees and juices, predictions show that temperature equilibrium will occur with sterilization temperatures up to 130 degrees C in under 0.02 s. Model development highlighted that the controlling influence on time for heating up the clump is the surface convection thermal resistance and that the internal conduction resistance of the clump mass is negligible by comparison. The time for a clump to reach equilibrium sterilization temperature was therefore decreased with relative turbulence (velocity) of the heating fluid, such as occurs in many process operations. These results confirm widely held suppositions that the heat-up time of bacteria in vapor or liquid is not significant with usual sterilization times.
Direct Selection of
Clostridium acetobutylicum
Fermentation Mutants by a Proton Suicide Method
Authors: Cueto Pablo H. , M�ndez Beatriz S.
Published: January 2020

Clostridium acetobutylicum
ATCC 10132 mutants altered in acetic acid synthesis or in the shift to solventogenesis were directly selected by a proton suicide method after mutagenic treatment, by using bromide and bromate as selective agents. The mutants were characterized according to their solvent and acid production. On the selection plates they differed in colony phenotype from the parent strain.
Nitrogen Fixation Dynamics of Two Diazotrophic Communities in Mono Lake, California
Authors: Oremland Ronald S.
Published: January 2020

Two types of diazotrophic microbial communities were found in the littoral zone of alkaline hypersaline Mono Lake, California. One consisted of anaerobic bacteria inhabiting the flocculent surface layers of sediments. Nitrogen fixation (acetylene reduction) by flocculent surface layers occurred under anaerobic conditions, was not stimulated by light or by additions of organic substrates, and was inhibited by O
2
, nitrate, and ammonia. The second community consisted of a ball-shaped association of a filamentous chlorophyte (
Ctenocladus circinnatus
) with diazotrophic, nonheterocystous cyanobacteria, as well as anaerobic bacteria (
Ctenocladus
balls). Nitrogen fixation by
Ctenocladus
balls was usually, but not always, stimulated by light. Rates of anaerobic dark fixation equaled those in the light under air. Fixation in the light was stimulated by 3-(3,4-dichlorophenyl)-1, 1-dimethylurea and by propanil [
N
-(3,4-dichlorophenyl)propanamide]. 3-(3,4-Dichlorophenyl)-1,1-dimethyl urea-elicited nitrogenase activity was inhibited by ammonia (96%) and nitrate (65%). Fixation was greatest when
Ctenocladus
balls were incubated anaerobically in the light with sulfide. Dark anaerobic fixation was not stimulated by organic substrates in short-term (4-h) incubations, but was in long-term (67-h) ones. Areal estimates of benthic N
2
fixation were measured seasonally, using chambers. Highest rates (∼29.3 μmol of C
2
H
4
m
−2
h
−1
) occurred under normal diel regimens of light and dark. These estimates indicate that benthic N
2
fixation has the potential to be a significant nitrogen source in Mono Lake.
Bioconversion of Cinnamic Acid to Acetophenone by a Pseudomonad: Microbial Production of a Natural Flavor Compound
Authors: Hilton Matthew D. , Cain Wendy J.
Published: January 2020

A mutant derivative of a novel pseudomonad isolated from the soil accumulated acetophenone when supplied with cinnamic acid. The microorganism has been identified as an unclassified
Pseudomonas
sp., similar to
Pseudomonas acidovorans.
Mass spectrum analysis of the product acetophenone derived from catabolism of cinnamic acid in the presence of
18
O
2
or H
2
18
O supported the conclusion that cinnamic acid degradation is initiated by addition of water to the double bond of the side chain, followed by dehydrogenation to generate 3-keto-3-phenylpropionic acid. The intermediate 3-keto-3-phenylpropionic acid is accumulated in cultures of the mutant during active cinnamic acid catabolism. However, this intermediate is unstable so a portion of it spontaneously decarboxylates to form acetophenone. Neither 3-keto-3-phenylpropionic acid nor acetophenone is a precedented intermediate in cinnamic acid degradation. Isolation of the novel strain and mutant provide the rudiments for a process to produce natural acetophenone by biotransformation of natural cinnamic acid.
Identification of
Phytophthora citrophthora
with Cloned DNA Probes
Authors: Goodwin P. H. , Kirkpatrick B. C. , Duniway J. M.
Published: January 2020

Two different DNA fragments, one of 2.9 kilobases and the other of 5.1 kilobases, were cloned from
Phytophthora citrophthora
and showed no homology with DNA from plants and other related fungi. These DNA probes hybridized with DNA from 12 different
P. citrophthora
isolates obtained from a variety of hosts but did not hybridize with DNA from 6
P. citrophthora
isolates obtained from cacao. Southern blot analysis revealed that the probes contained repetitive DNA, and restriction fragment length polymorphisms were identified among several
P. citrophthora
isolates. Of the isolates tested, two major groups were observed whose genetic similarity correlated with geographical distribution. One of the DNA probes was used to detect
P. citrophthora
growing from infected citrus roots incubated on semiselective medium.
P. citrophthora
was not detected by a hybridization assay of total DNA extracted directly from infected roots.
Influence of transition metals added during sporulation on heat resistance of Clostridium botulinum 113B spores
Authors: Kihm D J , Hutton M T , Hanlin J H , Johnson E A
Published: January 2020

Sporulation of Clostridium botulinum 113B in a complex medium supplemented with certain transition metals (Fe, Mn, Cu, or Zn) at 0.01 to 1.0 mM gave spores that were increased two to sevenfold in their contents of the added metals. The contents of calcium, magnesium, and other metals in the purified spores were relatively unchanged. Inclusion of sodium citrate (3 g/liter) in the medium enhanced metal accumulation and gave consistency in the transition metal contents of independent spore crops. In citrate-supplemented media, C. botulinum formed spores with very high contents of Zn (approximately 1% of the dry weight). Spores containing an increased content of Fe (0.1 to 0.2%) were more susceptible to thermal killing than were native spores or spores containing increased Zn or Mn. The spores formed with added Fe or Cu also appeared less able to repair heat-induced injuries than the spores with added Mn or Zn. Fe-increased spores appeared to germinate and outgrow at a higher frequency than did native and Mn-increased spores. This study shows that C. botulinum spores can be sensitized to increased thermal destruction by incorporation of Fe in the spores.
HCO
3
−
Fixation by Naturally Occurring Tufts and Pure Cultures of
Thiothrix nivea
Authors: McGlannan Michael F. , Makemson John C.
Published: January 2020

Naturally occurring tufts of the mixotroph
Thiothrix nivea
blanketed the East Everglades (Dade County, Fla.) Chekika artesian well and runoff areas. The rate of HCO
3
−
fixation by these
Thiothrix
tufts was determined to be 14.0 ± 5.4 nmol of HCO
3
−
per min per mg of dry weight, which reflected a growth rate of 5.0%/h. The addition of 10 mM glucose, ribose, acetate, or pyruvate or 0.05% Casamino Acids (Difco Laboratories, Detroit, Mich.) did not appear to alter the HCO
3
−
fixation rate. Whereas 1 mM acetate or 10 mM lactate, ethanol, glycerol, α-ketoglutarate, succinate, fumarate, or citrate slightly stimulated HCO
3
−
fixation, 5 to 10 mM malate inhibited HCO
3
−
fixation by 90%. Pure
Thiothrix
cultures isolated from Chekika fixed HCO
3
−
at rates as high as 29.9 ± 2.8 nmol of HCO
3
−
per min per mg of dry weight in the presence of growth medium. Malate did not have a suppressive effect but rather slightly stimulated in vivo HCO
3
−
fixation.
DNA hybridization to compare species compositions of natural bacterioplankton assemblages
Authors: Lee S , Fuhrman J A
Published: January 2020

Little is known about the species composition and variability of natural bacterial communities, mostly because conventional identification requires pure cultures, but less than 1% of active natural bacteria are cultivable. This problem was circumvented by comparing species compositions via hybridization of total DNA of natural bacterioplankton communities for the estimation of the fraction of DNA in common between two samples (similarity). DNA probes that were labeled with 35S by nick translation were hybridized to filter-bound DNA in a reciprocal fashion; similarities (in percent) were calculated by normalizing the values to self-hybridizations. In tests with DNA mixtures of pure cultures, the experimentally observed similarities agreed with expectations. However, reciprocal similarities (probe and target reversed) were often asymmetric, unlike those of DNA from single strains. This was due to the relative complexity and G + C content of DNA, which provided a means to interpret the asymmetry that was occasionally observed in natural samples. Natural bacteria were collected by filtration from Long Island Sound (LIS), N.Y., the Caribbean and Sargasso seas, and a coral reef lagoon near Bermuda. The samples showed similarities of less than 10 to 95%. The LIS and Sargasso and Caribbean sea samples were 20 to 50% similar to each other. The coral reef sample was less than 10% similar to the others, indicating its unique composition. Seasonality was also observed; an LIS sample obtained in the autumn was 40% similar to two LIS samples obtained in the summer; these latter two samples were 95% similar. We concluded that total DNA hybridization is a rapid, simple, and unbiased method for investigating the variation of bacterioplankton species composition over time and space, avoiding the need of culturing.
Bacterioplankton and Organic Carbon Dynamics in the Lower Mesohaline Chesapeake Bay
Authors: Jonas Robert B. , Tuttle Jon H.
Published: January 2020

The mesohaline portion of the Chesapeake Bay is subject to annual summertime hypoxia and anoxia in waters beneath the pycnocline. This dissolved oxygen deficit is directly related to salinity-based stratification of the water column in combination with high levels of autochthonously produced organic matter and a very high abundance of metabolically active bacteria. Throughout the water column in the lower, mesohaline part of the bay, between the Potomac and Rappahannock rivers, near the southern limit of the mainstem anoxia, bacterial abundance often exceeded 10 × 10
6
cells per ml and bacterial production exceeded 7 × 10
9
cells per liter per day during summer. Bacterial biomass averaged 34% (range, 16 to 126%) of the phytoplankton biomass in summer. These values are equal to or greater than those found farther north in the bay, where the oxygen deficit is more severe. Seasonal variations in bacterial abundance and production were correlated with phytoplankton biomass (lag time, 7 to 14 days), particulate organic carbon and nitrogen, and particulate biochemical oxygen demand in spring; but during summer, they were significantly correlated only with dissolved biochemical oxygen demand. During summer, dissolved biochemical oxygen demand can account for 50 to 60% of the total biochemical oxygen demand throughout the water column and 80% in the bottom waters. There is a clear spring-summer seasonal shift in the production of organic matter and in the coupling of bacteria and autochthonous organic matter. The measurement of dissolved, microbially labile organic matter concentrations is crucial in understanding the trophic dynamics of the lower mesohaline part of the bay. The absolute levels of organic matter in the water column and the bacterial-organic carbon relationships suggest that a lower bay source of organic matter fuels the upper mesohaline bay oxygen deficits.
High diversity in DNA of soil bacteria
Authors: Torsvik V , Goksøyr J , Daae F L
Published: January 2020

Soil bacterium DNA was isolated by minor modifications of previously described methods. After purification on hydroxyapatite and precipitation with cetylpyridinium bromide, the DNA was sheared in a French press to give fragments with an average molecular mass of 420,000 daltons. After repeated hydroxyapatite purification and precipitation with cetylpyridinium bromide, high-pressure liquid chromatography analysis showed the presence of 2.1% RNA or less, whereas 5-methylcytosine made up 2.9% of the total deoxycytidine content. No other unusual bases could be detected. The hyperchromicity was 31 to 36%, and the melting curve in 1 X SSC (0.15 M NaCl plus 0.015 M sodium citrate) corresponded to 58.3 mol% G+C. High-pressure liquid chromatography analysis of two DNA samples gave 58.6 and 60.8 mol% G+C. The heterogeneity of the DNA was determined by reassociation of single-stranded DNA, measured spectrophotometrically. Owing to the high complexity of the DNA, the reassociation had to be carried out in 6 X SSC with 30% dimethyl sulfoxide added. Cuvettes with a 1-mm light path were used, and the A275 was read. DNA concentrations as high as 950 micrograms ml-1 could be used, and the reassociation rate of Escherichia coli DNA was increased about 4.3-fold compared with standard conditions. C0t1/2 values were determined relative to that for E. coli DNA, whereas calf thymus DNA was reassociated for comparison. Our results show that the major part of DNA isolated from the bacterial fraction of soil is very heterogeneous, with a C0t1/2 about 4,600, corresponding to about 4,000 completely different genomes of standard soil bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)
Tissue distribution of a coliphage and Escherichia coli in mussels after contamination and depuration
Authors: Power U F , Collins J K
Published: January 2020

Experiments were undertaken to determine the tissue distribution of Escherichia coli and a coliphage after contamination of the common mussel (Mytilus edulis). Mussels were contaminated with high levels of feces-associated E. coli and a 22-nm icosahedral coliphage over a 2-day period in a flowing-seawater facility. After contamination, individual tissues were carefully dissected and assayed for E. coli and the coliphage. Contaminated mussels were also analyzed to determine the tissue distribution of the contaminants after 24- and 48-h depuration periods. The majority of each contaminant was located in the digestive tract (94 and 89% of E. coli and coliphage, respectively). Decreasing concentrations were found in the gills and labial palps, foot and muscles, mantle lobes, and hemolymph. Our results indicate that contamination above levels in water occurred only in the digestive tract. Contaminated mussels were depurated in a commercial-scale recirculating UV depuration system over a 48-h period. The percent reductions of E. coli occurred in the following order: digestive tract, hemolymph, foot and muscles, mantle lobes, and gills and labial palps. The percent reductions of the coliphage were different, occurring in the following order: hemolymph, foot and muscles, gills and labial palps, mantle lobes, and digestive tract. Our results clearly demonstrate that E. coli and the coliphage are differentially eliminated from the digestive tract. The two microorganisms are eliminated at similar rates from the remaining tissues. Our results also clearly show that the most significant coliphage retention after depuration for 48 h is in the digestive tract. Thus, conventional depuration practices are inappropriate for efficient virus elimination from mussels.
Plasmid profiling of Vibrio salmonicida for epidemiological studies of cold-water vibriosis in Atlantic salmon (Salmo salar) and cod (Gadus morhua)
Authors: Sørum H , Hvaal A B , Heum M , Daae F L , Wiik R
Published: January 2020

In 1988, a new plasmid profile was observed for Vibrio salmonicida isolated from cod (Gadus morhua) and Atlantic salmon (Salmo salar) in fish farms in northern Norway. This new plasmid profile, which consisted of plasmids of 61, 21, 3.4, and 2.8 megadaltons, is 1 of 11 plasmid profiles which have so far been observed for V. salmonicida. Plasmid profiling and plasmid DNA hybridization were used in epidemiological studies of cold-water vibriosis. Our results indicate that V. salmonicida was transmitted from Atlantic salmon to cod and vice versa. The 61-megadalton plasmid was found exclusively in V. salmonicida strains originating from northern Norway, which is the only area in which this plasmid has ever been observed. Plasmid DNA hybridization and restriction endonuclease analysis show that the plasmid DNA of V. salmonicida remained stable throughout a 7-year survey.
Low-pH-induced effects on patterns of protein synthesis and on internal pH in Escherichia coli and Salmonella typhimurium
Authors: Hickey E W , Hirshfield I N
Published: January 2020

Escherichia coli and Salmonella typhimurium were grown in a supplemented minimal medium (SMM) at a pH of 7.0 or 5.0 or were shifted from pH 7.0 to 5.0. Two-dimensional gel electrophoretic analysis of proteins labeled with H2(35)SO4 for 20 min during the shift showed that in E. coli, 13 polypeptides were elevated 1.5- to 4-fold, whereas in S. typhimurium, 19 polypeptides were increased 2- to 14-fold over the pH 7.0 control. Upon long-term growth at pH 5.0, almost double the number of polypeptides were elevated twofold or more in S. typhimurium compared with E. coli. In E. coli, there was no apparent induction of heat shock proteins upon growth at pH 5.0 in SMM. However, growth of E. coli in a complex broth to pH 5.0, or subsequent growth of fresh E. coli cells in the filtrate from this culture, showed that a subset of five polypeptides is uniquely induced by low pH. Two of these polypeptides, D60.5, the inducible lysyl-tRNA synthetase, and C62.5, are known heat shock proteins. Measurements of the internal pH (pHi) and growth rates of both organisms were made during growth in SMM at pH 7.0, pH 5.0, and upon the pH shift. The data show that the pHi of E. coli decreases more severely than that of S. typhimurium at an external pH of 5.0; the growth rate of E. coli is about one-half that of S. typhimurium at this pH, whereas the two organisms have the same growth rate at pH 7.0. The two-dimensional gel, growth, and pHi experiments collectively suggest that, at least in SMM, S. typhimurium is more adaptive to low-pH stress than is E. coli.