bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective Medium for Enumeration of Tannin-Protein Complex-Degrading
Streptococcus
spp. in Feces of Koalas
Authors: Osawa Ro , Mitsuoka Tomotari
Published: January 2020

A selective agar plate medium (tannin-treated brain heart infusion agar supplemented with colistin-oxolinic acid) was developed to enumerate tannin-protein complex-degrading
Streptococcus bovis
in the feces of koalas. This medium was successfully used to enumerate strains from fecal samples but failed to enumerate those from pure cultures.
Does single-amino-acid replacement work in favor of or against improvement of the thermostability of immobilized enzyme?
Authors: Koizumi J , Zhang M , Imanaka T , Aiba S
Published: January 2020

Thermostabilities of kanamycin nucleotidyltransferase and of its mutants that became thermostable, in the free state, because of single-amino-acid replacements were studied after immobilization of the enzymes on cyanogen bromide-activated Sephadex G-200 particles. Lys in place of Gln at position 102 decreased the thermostability of the immobilized enzyme, whereas replacement with other amino acids enhanced it.
Vibrios associated with red tides caused by Mesodinium rubrum
Authors: Romalde J L , Barja J L , Toranzo A E
Published: January 2020

Vibrios were isolated from red tides caused by Mesodinium rubrum and also throughout the year in the Ria de Pontevedra, Spain. The isolates were grouped into 14 phena by numerical toxonomy. Strains associated with red tides were restricted to four phena: phena I and II were Vibrio alginolyticus, and phena III and IV were Vibrio tubiashii and Vibrio anguillarum, respectively. V. anguillarum-like strains (phena V through XI) predominated throughout the year outside the red tide areas. Cytotoxicity assays conducted in different poikilothermic and homoiothermic cell lines showed that cytotoxin production was not necessarily associated with the species selected during the red tides.
DNA, a Possible Site of Action of Aluminum in
Rhizobium
spp
Authors: Johnson A. C. , Wood M.
Published: January 2020

Al was found to penetrate the cell envelopes of both sensitive and tolerant
Rhizobium
strains and bind to DNA in vivo. Despite causing a reduction in viability, Al stimulated DNA synthesis in the sensitive strain, which suggested that an excision repair mechanism was operating. The Al-stimulated DNA synthesis was reduced by the simultaneous addition of chloramphenicol. In contrast to the sensitive strain, DNA synthesis was unaffected by Al binding to DNA in the tolerant strain. It is proposed that Al enters the cell and binds to the DNA helix, increasing stabilization and preventing successful replication. Different repair mechanisms appear to operate in response to Al in tolerant and sensitive strains.
Bacterial Degradation of Ring-Chlorinated Acetophenones
Authors: Higson Frank K. , Focht Dennis D.
Published: January 2020

Two strains,
Alcaligenes
sp. strain ACA and
Pseudomonas fluorescens
ACB, isolated from acetophenone and 4′-hydroxyacetophenone enrichments, respectively, cometabolize a range of chlorinated acetophenones (CAs). A biological Baeyer-Villiger reaction converts the CA to chlorophenyl acetate. This is evident only in the presence of an esterase inhibitor, since the CA is normally rapidly hydrolyzed to a chlorophenol which has the same substitution pattern as the original ketone. The oxygenase that attacks the ketone uses NADPH in the incorporation of one atom of
18
O
2
and is strongly inhibited by phenols that bear an
ortho
or
meta
chlorine or bromine, but much less by cresols or phenol itself. A feedback phenomenon may thus account for the inability of strain ACA to grow on CAs, which also fail to induce the cells for their own metabolism.
Isolation and characterization of disaggregatase from Methanosarcina mazei LYC
Authors: Xun L Y , Mah R A , Boone D R
Published: January 2020

At certain stages in its growth cycle, Methanosarcina mazei produces an enzyme (disaggregatase) that causes aggregates to separate into single cells. M. mazei S-6 and LYC both produce this enzymatic activity, although the specificities of activities differ. The disaggregatase of M. mazei S-6 had little effect on strain LYC cells, but the disaggregatase of M. mazei LYC disaggregated both strain LYC and strain S-6 cells. The disaggregatase of M. mazei LYC was purified by column chromatography, and it apparently consisted of two similar subunits with a combined molecular size of about 180,000 Da. Strain S-6 culture supernatants contained 14 U of activity per liter when activity was measured as uronic acids released from purified cell wall material. When the activity was quantified as the release of uronic acids from boiled M. mazei S-6 cells, the highest activity was found at pH 4.7 and at 35 degrees C.
Comparative study on the natural occurrence of Fusarium mycotoxins (trichothecenes and zearalenone) in corn and wheat from high- and low-risk areas for human esophageal cancer in China
Authors: Luo Y , Yoshizawa T , Katayama T
Published: January 2020

A comparative study on the natural occurrence of Fusarium toxins was done with 47 corn and 30 wheat samples collected in 1989 from Linxian and Shangqiu Counties in Henan Province, People's Republic of China, high- and low-risk areas, respectively, for esophageal cancer. Three trichothecenes (deoxynivalenol [DON], 15-acetyldeoxynivalenol [15-ADON], and nivalenol [NIV]) and zearalenone (ZEA) were detected in corn samples, and DON, NIV, and ZEA were found in wheat samples. Compared with Shangqiu corn, the incidence and mean level of DON in Linxian were 2.4 and 5.8 times higher, respectively, and those of 15-ADON were 16.3 and 2.6 times higher, respectively. The incidence and level of trichothecenes in wheat samples were significantly lower than those in corn. However, the level of DON in Linxian wheat was 3.3 times higher than in Shangqiu wheat. This is the first report indicating a significant difference in the natural occurrence of Fusarium toxins in main staple foods between high- and low-risk areas for esophageal cancer in the People's Republic of China.
Streptomyces thermoautotrophicus
sp. nov., a Thermophilic CO- and H
2
-Oxidizing Obligate Chemolithoautotroph
Authors: Gadkari Dilip , Schricker Karl , Acker Georg , Kroppenstedt Reiner M. , Meyer Ortwin
Published: January 2020

The novel thermophilic CO- and H
2
-oxidizing bacterium UBT1 has been isolated from the covering soil of a burning charcoal pile. The isolate is gram positive and obligately chemolithoautotrophic and has been named
Streptomyces thermoautotrophicus
on the basis of G+C content (70.6 ± 0.19 mol%), a phospholipid pattern of type II, MK-9(H
4
) as the major quinone, and other chemotaxonomic and morphological properties.
S. thermoautotrophicus
could grow with CO (

t
d

= 8 h), H
2
plus CO
2
(

t
d

= 6 h), car exhaust, or gas produced by the incomplete combustion of wood. Complex media or heterotrophic substrates such as sugars, organic acids, amino acids, and alcohols did not support growth. Molybdenum was required for CO-autotrophic growth. For growth with H
2
, nickel was not necessary. The optimum growth temperature was 65°C; no growth was observed below 40°C. However, CO-grown cells were able to oxidize CO at temperatures of 10 to 70°C. Temperature profiles of burning charcoal piles revealed that, up to a depth of about 10 to 25 cm, the entire covering soil provides a suitable habitat for
S. thermoautotrophicus
. The

K
m

was 88 μl of CO liter
−1
and
V
max
was 20.2 μl of CO h
−1
mg of protein
−1
. The threshold value of
S. thermoautotrophicus
of 0.2 μl of CO liter
−1
was similar to those of various soils. The specific CO-oxidizing activity in extracts with phenazinemethosulfate plus 2,6-dichlorophenolindophenol as electron acceptors was 246 μmol min
−1
mg of protein
−1
. In exception to other carboxydotrophic bacteria,
S. thermoautotrophicus
CO dehydrogenase was able to reduce low potential electron acceptors such as methyl and benzyl viologens.
Production, Purification, and Properties of Extracellular Carboxyl Esterases from
Bacillus subtilis
NRRL 365
Authors: Meghji K. , Ward O. P. , Araujo A.
Published: January 2020

Bacillus subtilis
NRRL 365 produced high extracellular carboxyl esterase activity in submerged culture media containing wheat bran, corn steep liquor, and salts. Supplementation of this medium with glucose reduced esterase activity to 37% of that in the unsupplemented control. Esterase activity was purified by ammonium sulfate fractionation, DEAE-Sephadex A-50 ion-exchange chromatography with sodium chloride gradient elution, and preparative polyacrylamide gel electrophoresis. The resultant purified components, esterases I and II, manifested single bands following silver staining of polyacrylamide gel electrophoresis gels and had final specific activities of 80 and 520 U/mg, respectively. Molecular weights for components I and II were 36,000 and 105,000 to 110,000, respectively. Esterases I and II both had a pH optimum of 8.0, with relative activities of 10 and 85%, respectively, at pH 9.0.

K
m

s with
p
-nitrophenylacetate were 0.91 mM for esterase I and 0.67 mM for esterase II. In general, patterns of enzyme inhibition were similar for both components. Differences were observed in the relative activities of esterases I and II towards
p
-nitrophenyl esters of acetate, propionate, and butyrate; Activity ratios for components I and II were 100:94:48 and 100:36:23, respectively. The purified components did not hydrolyze long-chain triglycerides and did not manifest proteolytic activity.
Distribution of Hydrogenase Genes in
Desulfovibrio
spp. and Their Use in Identification of Species from the Oil Field Environment
Authors: Voordouw Gerrit , Niviere Vincent , Ferris F. Grant , Fedorak Phillip M. , Westlake Donald W. S.
Published: January 2020

The distribution of genes for [Fe], [NiFe], and [NiFeSe] hydrogenases was determined for 22
Desulfovibrio
species. The genes for [NiFe] hydrogenase were present in all species, whereas those for the [Fe] and [NiFeSe] hydrogenases had a more limited distribution. Sulfate-reducing bacteria from 16S rRNA groups other than the genus
Desulfovibrio
(R. Devereux, M. Delaney, F. Widdel, and D. A. Stahl, J. Bacteriol. 171:6689-6695, 1989) did not react with the [NiFe] hydrogenase gene probe, which could be used to identify different
Desulfovibrio
species in oil field samples following growth on lactate-sulfate medium.
Pectin Lyase Activity in a
Penicillium italicum
Strain
Authors: Alaña Aitor , Alkorta Itziar , Domínguez Juan B. , Llama Maria J. , Serra Juan L.
Published: January 2020

An extracellular pectin lyase (PNL) [poly-(methoxygalacturonide)lyase; EC 4.2.2.10] produced by
Penicillium italicum
CECT 2294 grown on a surface bran (natural medium) or in a submerged (synthetic medium) culture was investigated. Both culture filtrates showed macerating activity at low pH on cucumber, potato, and orange tissues. The physicochemical properties of the enzyme obtained from both culture methods were identical, as well as its catalytic properties, which were assayed by different methods. The molecular mass of the PNL obtained by gel filtration chromatography was 22 kDa; the isoelectric point was 8.6, as determined by chromatofocusing; and the enzyme was able to catalyze the eliminative cleavage of pectins with low (37%) and high (from 54 to 82%) degrees of esterification. The PNL produced in liquid medium showed a

K
m

for pectin (degree of esterification, 70%) of 3.2 mg/ml, and the optimum pH was 6.0 to 7.0. This enzyme was stable at 50°C and at pH 8.0. The ability of this PNL to macerate plant tissues in acidic environmental conditions, its stability at low pH and temperatures up to 50°C (thus preventing mesophilic microbial growth), and the absence of pectinesterase make this preparation useful for the food industry.
Influence of hydrogen-consuming bacteria on cellulose degradation by anaerobic fungi
Authors: Marvin-Sikkema F D , Richardson A J , Stewart C S , Gottschal J C , Prins R A
Published: January 2020

The presence of methanogens Methanobacterium arboriphilus, Methanobacterium bryantii, or Methanobrevibacter smithii increased the level of cellulose fermentation by 5 to 10% in cultures of several genera of anaerobic fungi. When Neocallimastix sp. strain L2 was grown in coculture with methanogens the rate of cellulose fermentation also increased relative to that for pure cultures of the fungus. Methanogens caused a shift in the fermentation products to more acetate and less lactate, succinate, and ethanol. Formate transfer in cocultures of anaerobic fungi and M. smithii did not result in further stimulation of cellulolysis above the level caused by H2 transfer. When Selenomonas ruminatium was used as a H2-consuming organism in coculture with Neocallimastix sp. strain L2, both the rate and level of cellulolysis increased. The observed influence of the presence of methanogens is interpreted to indicate a shift of electrons from the formation of electron sink carbon products to H2 via reduced pyridine nucleotides, favoring the production of additional acetate and probably ATP. It is not known how S. ruminantium exerts its influence. It might result from a lowered production of electron sink products by the fungus, from consumption of electron sink products or H2 by S. ruminantium, or from competition for free sugars which in pure culture could exert an inhibiting effect on cellulolysis.
Purification and properties of an acetylxylan esterase from Fibrobacter succinogenes S85
Authors: McDermid K P , Forsberg C W , MacKenzie C R
Published: January 2020

An acetylxylan esterase (EC 3.1.1.6) was purified to apparent homogeneity from the nonsedimentable extracellular culture fluid of Fibrobacter succinogenes S85 grown on cellulose. This enzyme had an apparent molecular mass of 55 kDa and an isoelectric point of 4.0. The temperature and pH optima were 45 degrees C and 7.0, respectively. The apparent Km and Vmax were 2.7 mM and 9,100 U/mg, respectively, for the hydrolysis of alpha-naphthyl acetate. The enzyme cleaved acetyl residues from birchwood acetylxylan but did not hydrolyze carboxymethylcellulose, larchwood xylan, ferulic acid-arabinose-xylose polymer, p-nitrophenyl-alpha-L-arab-inofuranoside, or longer-chain naphthyl fatty acid esters. The esterase enzyme may play a role in enhancing hemicellulose degradation by F. succinogenes, thereby allowing it greater access to cellulose present in forage cell walls.
Interactions between
Shewanella colwelliana
, Oyster Larvae, and Hydrophobic Organophosphate Pesticides
Authors: Labare Michael P. , Weiner Ronald M.
Published: January 2020

Shewanella colwelliana
(strain D) is a periphytic estuarine bacterium that forms biofilms beneficial to oyster set. Our study examined whether these and other films concentrated two hydrophobic, organophosphate pesticides, Abate and malathion, that are detected in Chesapeake Bay oyster waters. Both biofilms and purified exopolysaccharide of
S. colwelliana
did not adsorb more of the Abate or malathion than could be accounted for by adsorption to control surfaces. Similar results were obtained by using
Deleya marina, Hyphomonas
MHS3, and autochthonous biofilms. Conversely, decapsulated
S. colwelliana
D cells, prepared in the laboratory, bioconcentrated Abate. Significantly, the
S. colwelliana
D biofilms exposed to Abate did not inhibit the settlement and metamorphosis of
Crassostrea gigas
larvae.
Purification and characterization of a novel nucleoside phosphorylase from a Klebsiella sp. and its use in the enzymatic production of adenine arabinoside
Authors: Ling F , Inoue Y , Kimura A
Published: January 2020

An adenosine-assimilating bacterium, Klebsiella sp. strain LF1202, inducibly formed a novel nucleoside phosphorylase which acted on both purine and pyrimidine nucleosides when the cells were cultured in medium containing adenosine as a sole source of carbon and nitrogen. The enzyme was purified (approximately 83-fold, with a 17% activity yield) to the homogeneous state by polyacrylamide gel electrophoresis. The molecular weight of the purified enzyme was calculated to be 125,000 by gel filtration of Sephadex G-200 column chromatography, although the enzyme migrated as a single protein band with a molecular weight of 25,000 on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis; thus, it was thought to consist of five identical subunits. Besides purine nucleosides (adenosine, inosine, and guanosine), the purified enzyme also acted on pyrimidine nucleosides such as uridine, 2'-deoxyuridine, and thymidine. The purified enzyme catalyzed the synthesis of adenine arabinoside, a selective antiviral pharmaceutic agent, from uridine arabinoside and adenine.
Dynamics of Yeast Populations during Cider Fermentation in the Asturian Region of Spain
Authors: Cabranes Carmen , Moreno Javier , Mangas Juan J.
Published: January 2020

The influence of different cidermaking systems and apple mixtures on the dynamics of yeast populations in cider manufactured in Asturias (northern Spain) were studied. Results obtained in an experimental pilot plant were compared with those found in Asturian cider plants by using traditional techniques.
Saccharomyces cerevisiae
and
Kloeckera apiculata
were found in all cases.
Variation in polygalacturonase production among Aspergillus flavus isolates
Authors: Cotty P J , Cleveland T E , Brown R L , Mellon J E
Published: January 2020

Pectinase production by Aspergillus flavus was determined by measuring clear zones formed around colonies stained with ruthenium red. Several isolates produced red zones instead of clear zones. Red zones were reproduced with pectinesterase and correlated with absence of specific polygalacturonases. Of 87 isolates tested, 15 produced red zones.
Bactericidal effectiveness of modulated UV light
Authors: Bank H L , John J , Schmehl M K , Dratch R J
Published: January 2020

Studies were designed to evaluate the effectiveness of pulsed modulated UV light waveforms for killing bacteria. Exposure of five strains of bacteria to the modulated information encoded in the light decreased the colony population from a confluent lawn to less than 20 colonies. However, approximately 2,000 colonies survived treatment with the same intensity and time of exposure to UV light lacking the modulated information.
Intrageneric coaggregation among strains of human oral bacteria: potential role in primary colonization of the tooth surface
Authors: Kolenbrander P E , Andersen R N , Moore L V
Published: January 2020

Of the 122 human oral bacterial strains tested from 11 genera, only streptococci and a few actinomyces exhibited coaggregation among the strains within their respective genera. Eight of the ten streptococci showed multiple intrageneric coaggregations, all of which were inhibited by galactosides. The widespread intrageneric coaggregation among the streptococci and the less extensive coaggregation among the actinomyces offers an explanation for their accretion on cleaned tooth surfaces and their dominance as primary colonizers.
Mineralization of Surfactants by the Microbiota of Submerged Plant Detritus
Authors: Federle Thomas W. , Ventullo Roy M.
Published: January 2020

In wetlands and canopied bodies of water, plant detritus is an important source of carbon and energy. Detrital materials possess a large surface area for sorption of dissolved organics and are colonized by a large and diverse microbiota. To examine the biodegradation of surfactants by these microorganisms, submerged oak leaves were obtained from a laundromat wastewater pond, its overflow, and a pristine control pond. Leaves were cut into disks and incubated in sterile water amended with 50 μg of
14
C-labeled linear alkylbenzene sulfonate (LAS), linear alcohol ethoxylate, stearyltrimethyl ammonium chloride, distearyldimethyl ammonium chloride, benzoic acid, or mixed amino acids per liter. Sorption of the test compounds to the detritus and evolution of
14
CO
2
were followed with time. All of the compounds sorbed to the detritus to various degrees, with LAS and stearyltrimethyl ammonium chloride the most sorptive and benzoic acid the least. All compounds were mineralized without a lag. With leaves from the laundromat wastewater pond, half-lives were 12.6 days for LAS, 8.4 days for linear alcohol ethoxylate, 14.2 days for stearyltrimethyl ammonium chloride, 1.0 days for benzoic acid, and 2.7 days for mixed amino acids. Mineralization of LAS and linear alcohol ethoxylate by control pond leaves was slower and exhibited an S-shaped rather than a typical first-order pattern. This study shows that detritus represents a significant site of surfactant removal in detritus-rich systems.
Enumeration and biomass estimation of planktonic bacteria and viruses by transmission electron microscopy
Authors: B�rsheim K Y , Bratbak G , Heldal M
Published: January 2020

Bacteria and virus particles were harvested from water samples by ultracentrifugation directly onto Formvar-coated electron microscopy grids and counted in a transmission electron microscope. With this technique, we have counted and sized bacteria and viruses in marine water samples and during laboratory incubations. By X-ray microanalysis, we could determine the elemental composition and dry-matter content of individual bacteria. The dry weight/volume ratio for the bacteria was 600 fg of dry weight microns-3. The potassium content of the bacteria was normal compared with previous estimates from other bacterial assemblages; thus, this harvesting procedure did not disrupt the bacterial cells. Virus particles were, by an order of magnitude, more abundant than bacteria in marine coastal waters. During the first 5 to 7 days of incubation, the total number of viruses increased exponentially at a rate of 0.4 day-1 and thereafter declined. The high proliferation rate suggests that viral parasitism may affect mortality of bacteria in aquatic environments.
Enumeration of total coliforms and Escherichia coli from source water by the defined substrate technology
Authors: Edberg S C , Allen M J , Smith D B , Kriz N J
Published: January 2020

Many water utilities are required to monitor source water for the presence of total coliforms, fecal coliforms, or both. The Colilert system, an application of the defined substrate technology, simultaneously detects the presence of both total coliforms and Escherichia coli directly from a water sample. After incubation, the formula becomes yellow if total coliforms are present and fluorescent at 366 nm if E. coli is in the same sample. No confirmatory tests are required. The Colilert system was previously assessed with distribution water in a national evaluation in both most-probably-number and presence-absence formats and found to produce data equivalent to those obtained by using Standard Methods for the Examination of Water and Wastewater (Standard Methods). The Colilert system was now compared with Standard Methods multiple-tube fermentation (MTF) for the enumeration of total coliforms and E. coli from surface water. All MTF tubes were confirmed according to Standard Methods, and subcultures were made to identify isolates to the species level. The Colilert system was found equally sensitive to MTF testing by regression, t test, chi-square, and likelihood fraction analyses. Specificity of the Colilert system was shown by the isolation of a species of total coliform or E. coli after the appropriate color change. The Colilert test can be used for source water samples when enumeration is required, and the benefits previously described for distribution water testing--sensitivity, specificity, less labor, lower cost, faster results, no noncoliform heterotroph interference--are applicable to this type of water analysis.
Effects of growth temperature and strictly anaerobic recovery on the survival of Listeria monocytogenes during pasteurization
Authors: Knabel S J , Walker H W , Hartman P A , Mendonca A F
Published: January 2020

Listeria monocytogenes F5069 was suspended in either Trypticase soy broth-0.6% yeast extract (TSBYE) or sterile, whole milk and heated at 62.8 degrees C in sealed thermal death time tubes. Severely heat-injured cells were recovered in TSBYE within sealed thermal death time tubes because of the formation of reduced conditions in the depths of the TSBYE. Also, the use of strictly anaerobic Hungate techniques significantly increased recovery in TSBYE containing 1.5% agar compared with aerobically incubated controls. The exogenous addition of catalase, but not superoxide dismutase, slightly increased the recovery of heat-injured cells in TSBYE containing 1.5% agar incubated aerobically. Growth of cells at 43 degrees C caused a greater increase in heat resistance as compared with cells heat shocked at 43 degrees C or cells grown at lower temperatures. Growth of L. monocytogenes at 43 degrees C and enumeration by the use of strictly anaerobic Hungate techniques resulted in D62.8 degrees C values that were at least sixfold greater than those previously obtained by using cells grown at 37 degrees C and aerobic plating. Results indicate that, under the conditions of the present study, high levels of L. monocytogenes would survive the minimum low-temperature, long-time treatment required by the U.S. Food and Drug Administration for pasteurizing milk. The possible survival of low levels of L. monocytogenes during high-temperature, short-time pasteurization and enumeration of injured cells by recovery on selective media under strictly anaerobic conditions are discussed.
Purification and Partial Characterization of a Prolyl-Dipeptidyl Aminopeptidase from
Lactobacillus helveticus
CNRZ 32
Authors: Khalid Noraini M. , Marth Elmer H.
Published: January 2020

X-prolyl-dipeptidyl aminopeptidase, which hydrolyzed Gly-Pro-
p
-nitroanilide (relative activity [RA] = 100%) and Arg-Pro-
p
-nitroanilide (RA, 130%), was purified to homogeneity from the cell extract of
Lactobacillus helveticus
CNRZ 32. The enzyme also hydrolyzed Ala-Pro-Gly (RA, 11%) and Ala-Ala-
p
-nitroanilide (RA, 2%) but was not active on Ala-Leu-Ala, dipeptides, and endopeptidase and carboxypeptidase substrates. The enzyme was purified 145-fold by streptomycin sulfate precipitation, ammonium sulfate fractionation, and a series of column chromatographies on DEAE-cellulose, arginine-Sepharose 4B, and glycyl-prolyl-AH-Sepharose 4B. The purified enzyme appeared as a single band on native polyacrylamide gel and sodium dodecyl sulfate-polyacrylamide gel electrophoreses and had a molecular weight of 72,000. Optima for activity by the purified enzyme were pH 7.0 and 40�C. The enzyme was incubated at 40�C for 15 min with various metal ions. It was activated by Mg
2+
(2.5 mM), Ca
2+
(0.1 to 2.5 mM), Na
+
(10 to 50 mM), and K
+
(10 to 50 mM) and was inhibited by Hg
2+
(0.1 to 2.5 mM), Cu
2+
(0.1 to 2.5 mM), and Zn
2+
(0.1 to 2.5 mM). Enzyme activity was partially inhibited by EDTA (1.0 mM, 20 h at 40�C), 1,10-phenanthroline (1.0 mM, 15 min at 40�C), phenylmethylsulfonyl fluoride (1.0 mM),
N
-ethylmaleimide (1.0 mM), and iodoacetate (1.0 mM). It was completely inhibited by diisopropyl fluorophosphate (1.0 mM, 2 h at 40�C) and
p
-chloromercuribenzoate (1.0 mM, 15 min at 40�C). The enzyme was not affected by dithioerythritol (1.0 to 10 mM).
Transport of a genetically engineered Pseudomonas fluorescens strain through a soil microcosm
Authors: Trevors J T , van Elsas J D , van Overbeek L S , Starodub M E
Published: January 2020

Vertical soil microcosms flushed with groundwater were used to study the influence of water movement on survival and transport of a genetically engineered Pseudomonas fluorescens C5t strain through a loamy sand and a loam soil. Transport of cells introduced into the top 1 cm of the vertical soil microcosms was dependent on the flow rate of water and the number of times microcosms were flushed with groundwater. The presence of wheat roots growing downward in the microcosms contributed only slightly to the movement of P. fluorescens C5t cells to lower soil regions of the loamy sand microcosms, but enhanced downward transport in the loam microcosms. Furthermore, the introduced P. fluorescens C5t cells were detected in the effluent water samples even after three flushes of groundwater and 10 days of incubation. As evidenced by a comparison of counts from immunofluorescence and selective plating, nonculturable C5t cells occurred in day 10 soil and percolated water samples, primarily of the loamy sand microcosms. Vertical soil microcosms that use water movement may be useful in studying the survival and transport of genetically engineered bacteria in soil under a variety of conditions prior to field testing.
Omasal ciliated protozoa in cattle, bison, and sheep
Authors: Towne G , Nagaraja T G
Published: January 2020

Omasal contents were collected from slaughtered cattle (n = 54), bison (n = 15), and sheep (n = 40) to determine numbers and generic distribution of ciliated protozoa. Total protozoan numbers were significantly lower in omasal contents than in ruminal contents of all three species, but the percent composition of all protozoan genera was similar between omasal and ruminal populations. The highest numbers of omasal protozoa found were 7.61 X 10(5)/g in cattle, 7.01 X 10(5)/g in bison, and 1.29 X 10(6)/g in sheep. Omasal dry matter was significantly higher than ruminal dry matter in all species and ranged up to 51.5% in cattle fed high-concentrate diets. The omasal pH was similar to the ruminal pH in all species. The number of omasal laminae averaged 149, 145, and 74 for cattle, bison, and sheep, respectively. Although protozoan concentrations in omasal contents were approximately 80% lower than those in ruminal contents, the omasum harbored relatively high numbers of ciliated protozoa. The resident omasal protozoa are extremely difficult to remove, particularly in cattle, and apparently are responsible for reinoculating transiently defaunated rumens.
Increased Sporulation of Vesicular-Arbuscular Mycorrhizal Fungi by Manipulation of Nutrient Regimens
Authors: Douds David D. , Schenck N. C.
Published: January 2020

Adjustment of pot culture nutrient solutions increased root colonization and sporulation of vesicular-arbuscular mycorrhizal (VAM) fungi.
Paspalum notatum
Flugge and VAM fungi were grown in a sandy soil low in N and available P. Hoagland nutrient solution without P enhanced sporulation in soil and root colonization of
Acaulospora longula, Scutellospora heterogama, Gigaspora margarita,
and a wide range of other VAM fungi over levels produced by a tap water control or nutrient solutions containing P. However,
Glomus intraradices
produced significantly more spores in plant roots in the tap water control treatment. The effect of the nutrient solutions was not due solely to N nutrition, because the addition of NH
4
NO
3
decreased both colonization and sporulation by
G. margarita
relative to levels produced by Hoagland solution without P.
Production of Bakers' Yeast in Cheese Whey Ultrafiltrate
Authors: Champagne C. P. , Goulet J. , Lachance R. A.
Published: January 2020

A process for the production of bakers' yeast in whey ultrafiltrate (WU) is described. Lactose in WU was converted to lactic acid and galactose by fermentation.
Streptococcus thermophilus
was selected for this purpose. Preculturing of
S. thermophilus
in skim milk considerably reduced its lag. Lactic fermentation in 2.3×-concentrated WU was delayed compared with that in unconcentrated whey, and fermentation could not be completed within 60 h. The growth rate of bakers' yeast in fermented WU differed among strains. The rate of galactose utilization was similar for all strains, but differences in lactic acid utilization occurred. Optimal pH ranges for galactose and lactic acid utilization were 5.5 to 6.0 and 5.0 to 5.5, respectively. The addition of 4 g of corn steep liquor per liter to fermented WU increased cell yields. Two sources of nitrogen were available for growth of
Saccharomyces cerevisiae
: amino acids (corn steep liquor) and ammonium (added during the lactic acid fermentation). Ammonium was mostly assimilated during growth on lactic acid. This process could permit the substitution of molasses by WU for the industrial production of bakers' yeast.
Stability of Markers Used for Identification of Two
Rhizobium galegae
Inoculant Strains after Five Years in the Field
Authors: Lindstr�m K. , Lipsanen P. , Kaijalainen S.
Published: January 2020

The stability of identification markers was examined for two
Rhizobium galegae
inoculant strains after 5 years in the field. The two strains are genetically closely related, but differ in their lipopolysaccharides. Strain HAMBI 540 has lipopolysaccharide of the rough type, whereas that of strain HAMBI 1461 is of the smooth type. The properties that were examined for 10 field isolates of each inoculant type were symbiotic phenotype, phage type, intrinsic antibiotic resistance, maximum growth temperature, lipopolysaccharide and total soluble protein patterns, immunological properties, DNA restriction profiles, and DNA hybridization patterns, which were determined by using
nifHDK
and
recA
sequences as probes. Of these properties, all remained stable in soil, with the exception of some variation in intrinsic antibiotic resistance and the acquisition of an extra
Eco
RI restriction fragment by one of the isolates. Thus, both the rough and the smooth lipopolysaccharide phenotypes persisted equally well in soil.
Role of Microniches in Protecting Introduced
Rhizobium leguminosarum
biovar
trifolii
against Competition and Predation in Soil
Authors: Postma J. , Hok-A-Hin C. H. , van Veen J. A.
Published: January 2020

The importance of microniches for the survival of introduced
Rhizobium leguminosarum
biovar
trifolii
cells was studied in sterilized and recolonized sterilized loamy sand and silt loam. The recolonized soils contained several species of soil microorganisms but were free of protozoa. Part of these soil samples was inoculated with the flagellate
Bodo saltans
, precultured on rhizobial cells. The introduced organisms were enumerated in different soil fractions by washing the soil, using a standardized washing procedure. With this method, free organisms and organisms associated with soil particles or aggregates >50 μm were separated. The total number of rhizobia was influenced slightly (silt loam) or not at all (loamy sand) by the recolonization with microorganisms or by the addition of flagellates alone. However, when both flagellates and microorganisms were present, numbers of rhizobia decreased drastically. This decrease was more than the sum of both effects separately. Nevertheless, populations of rhizobia were still higher than in natural soil. In the presence of flagellates, higher percentages of rhizobia and other microorganisms were associated with soil particles or aggregates >50 μm than in the absence of flagellates. In recolonized soils, however, the percentages of particle-associated rhizobia were lower than in soils not recolonized previous to inoculation. Thus, the presence of other microorganisms hindered rhizobial colonization of sites where they are normally associated with soil particles or aggregates.
Vapor-phase hydrogen peroxide as a surface decontaminant and sterilant
Authors: Klapes N A , Vesley D
Published: January 2020

The feasibility of utilizing vapor-phase hydrogen peroxide (VPHP) as a surface decontaminant and sterilant was evaluated in a centrifuge application. The prototype VPHP decontamination system, retrofitted into a Beckman L8-M ultracentrifuge, was designed to vaporize a 30% (wt/wt) solution of aqueous hydrogen peroxide continuously injecting and withdrawing VPHP in a deep-vacuum flow-through system. VPHP cycles of 4, 8, 16, and 32 min were examined for cidal activity against spores of Bacillus subtilis subsp. globigii and Bacillus stearothermophilus. Spore inocula (approximately 10(6)/coupon) were dried onto 0.5-in. (1.27-cm)-square stainless-steel coupons, and coupons were suspended in the centrifuge chamber, the space between the refrigeration can and the barrier ring (inner gap), and the space between the barrier ring and the vacuum ring (outer gap). At a chamber temperature of 4 degrees C, B. subtilis subsp. globigii spores were inactivated within 8 min, while inactivation of spores located in the outer gap at 27 degrees C required 32 min. The elevated temperature and high surface area/volume ratios in the outer gap may serve to decompose the gas more rapidly, thus reducing cidal efficacy. Of the two test spores, B. stearothermophilus was more resistant to VPHP. Nonetheless, VPHP was shown to possess significant sporicidal capability. For practical decontamination applications of the type described, VPHP shows promise as an effective and safer alternative to currently used ethylene oxide or formaldehyde vapors.
Chlorine Dioxide Gas Sterilization under Square-Wave Conditions
Authors: Jeng David K. , Woodworth Archie G.
Published: January 2020

Experiments were designed to study chlorine dioxide (CD) gas sterilization under square-wave conditions. By using controlled humidity, gas concentration, and temperature at atmospheric pressure, standard biological indicators (BIs) and spore disks of environmental isolates were exposed to CD gas. The sporicidal activity of CD gas was found to be concentration dependent. Prehumidification enhanced the CD activity. The
D
values (time required for 90% inactivation) of
Bacillus subtilis
subsp.
niger
ATCC 9372 BIs were estimated to be 1.5, 2.5, and 4.2 min when exposed to CD concentrations of 30, 15, and 7 mg/liter, respectively, at 23�C and ambient (20 to 40%) relative humidity (RH). Survivor tailings were observed. Prehumidification of BIs to 70 to 75% RH in an environmental chamber for 30 min resulted in a
D
value of 1.6 min after exposure to a concentration of 6 to 7 mg of CD per liter at 23�C and eliminated survivor tailing. Prolonging prehumidification at 70 to 75% RH for up to 16 h did not further improve the inactivation rate. Prehumidification by ultrasonic nebulization was found to be more effective than prehumidification in the environmental chamber, improving the
D
value to 0.55 min at a CD concentration of 6 to 7 mg/liter. Based on the current observations, CD gas is estimated, on a molar concentration basis, to be 1,075 times more potent than ethylene oxide as a sterilant at 30�C. A comparative study showed
B
.
subtilis
var.
niger
BIs were more resistant than other types of BIs and most of the tested bacterial spores of environmental isolates.
Production of staphylococcal enterotoxins C1 and C2 and thermonuclease throughout the growth cycle
Authors: Otero A , Garc�a M L , Garc�a M C , Moreno B , Bergdoll M S
Published: January 2020

Synthesis of enterotoxins C1 and C2 and thermonuclease throughout the growth cycle was investigated with Staphylococcus aureus type strains FRI137 and FRI361 and S. aureus isolates M5 (C1) and L2 (C2) of animal origin. Both enterotoxins were produced during the exponential growth phase or at the beginning of the stationary phase. The minimal incubation time (7 to 12 h) and the lowest population (10(7) to 2 x 10(9) CFU/ml) associated with detectable enterotoxin (1 to 6.5 ng/ml) were related to the total amount of toxin produced after 24 h. Thermonuclease was detected in all samples whenever enterotoxins were detected. Furthermore, strain FRI137 produced thermonuclease earlier and at lower cell populations than it did enterotoxin C1. Patterns of enterotoxin and thermonuclease synthesis did not correlate. The concentration of toxins increased throughout the growth cycle, while the concentration of thermonuclease remained constant during the last hours of the growth cycle.
Kinetics of Sulfur Oxidation at Suboptimal Temperatures
Authors: Ahonen Lasse , Tuovinen Olli H.
Published: January 2020

Chemolithoautotrophic bacteria were enriched from mine water at incubation temperatures ranging from 4 to 46�C, using elemental sulfur as a substrate in acid mineral salts media. Thiobacillus-type bacteria were successfully enriched for at all test temperatures except 46�C. Changes in pH (−
d
pH/
dt
) were used to estimate the rate constants for the enrichment cultures. The rate constants yielded a linear Arrhenius plot, an activation energy of 65 kJ/mol, and a temperature coefficient (
Q
10
) of 2.1 for the 4 to 37�C temperature interval.
Size-selective grazing on bacteria by natural assemblages of estuarine flagellates and ciliates
Authors: Gonzalez J M , Sherr E B , Sherr B F
Published: January 2020

The small average cell size of in situ bacterioplankton, relative to cultured cells, has been suggested to be at least partly a result of selection of larger-sized cells by bacterivorous protozoa. In this study, we determined the relative rates of uptake of fluorescence-labeled bacteria (FLB), of various cell sizes and cell types, by natural assemblages of flagellates and ciliates in estuarine water. Calculated clearance rates of bacterivorous flagellates had a highly significant, positive relationship with size of FLB, over a range of average biovolume of FLB of 0.03 to 0.08 microns3. Bacterial cell type or cell shape per se did not appear to affect flagellate clearance rates. The dominant size classes of flagellates which ingested all types of FLB were 3- to 4-microns cells. Ciliates also showed a general preference for larger-sized bacteria. However, ciliates ingested a gram-positive enteric bacterium and a marine bacterial isolate at higher rates than they did a similarly sized, gram-negative enteric bacterium or natural bacterioplankton, respectively. From the results of an experiment designed to test whether the addition of a preferentially grazed bacterial strain stimulated clearance rates of natural bacterioplankton FLB by the ciliates, we hypothesized that measured differences in rates of FLB uptake were due instead to differences in effective retention of bacteria by the ciliates. In general, clearance rates for different FLB varied by a factor of 2 to 4. Selective grazing by protozoa of larger bacterioplankton cells, which are generally the cells actively growing or dividing, may in part explain the small average cell size, low frequency of dividing cells, and low growth rates generally observed for assemblages of suspended bacteria.
Detection of ruminal bacteria that degrade toxic dihydroxypyridine compounds produced from mimosine
Authors: Allison M J , Hammond A C , Jones R J
Published: January 2020

Leucaena leucocephala, a tropical leguminous shrub, contains a toxic amino acid, mimosine. Successful utilization of leucaena as a ruminant forage depends on colonization of the rumen by bacteria that degrade dihydroxypyridines (DHP), which are toxic intermediates in the metabolism of mimosine. Populations in the rumina of animals in some parts of the world, however, do not include bacteria that are able to carry out this degradation. We thus describe tests for the presence of DHP degraders in ruminal populations that are based on degradation (loss) of DHP compounds from culture media. Results obtained with the tests indicate that DHP degraders were not part of microbial populations in the rumina of cattle, sheep, and goats in Iowa, while most rumen samples examined from animals from the Virgin Islands and Haiti contained DHP degraders. These results confirm and extend the findings of others about geographic limits to the distribution of these important ruminal bacteria.
Improved Method of Enumeration of Attached Bacteria for Study of Fluctuation in the Abundance of Attached and Free-Living Bacteria in Response to Diel Variation in Seawater Turbidity
Authors: Yoon Won Bae , Rosson Reinhardt A.
Published: January 2020

Sample preparation for enumerating attached bacteria in turbid seawater by epifluorescence microscopy was improved by treating samples with a surfactant (Tween 80) followed by sonication. With optimal treatment with Tween 80 (final concentration, 10 ppm [10 μg/ml]) and sonication, as many as 10 times more attached bacteria were enumerated from turbid seawater relative to the number enumerated from an untreated control. Dispersion of bacteria by sonication alone resulted in the enumeration of only 42 to 72% of the attached bacteria. By this technique, fluctuations in the number of attached and free-living bacteria were determined in water from Aransas Pass, Tex., where surface sediments are resuspended on a regular basis by tidal currents. The abundance of attached bacteria increased in proportion to the seawater turbidity that resulted from sediment resuspension. The variation in abundance of free-living bacteria was not directly related to seawater turbidity. However, the magnitude of fluctuation in the abundance of free-living bacteria was related to the extent of turbidity variation during diurnal tides.
Deposition of manganese in a drinking water distribution system
Authors: Sly L I , Hodgkinson M C , Arunpairojana V
Published: January 2020

The deposition of manganese in a water distribution system with manganese-related "dirty water" problems was studied over a 1-year period. Four monitoring laboratories with Robbins biofilm sampling devices fitted to the water mains were used to correlate the relationship among manganese deposition, the level of manganese in the water, and the chlorination conditions. Manganese deposition occurred by both chemical and microbial processes. Chemical deposition occurred when Mn(II) not removed during water treatment penetrated the filters and entered the distribution system, where it was oxidized by chlorine and chlorine dioxide used for disinfection. Microbial deposition occurred in areas with insufficient chlorination to control the growth of manganese-depositing biofilm. At 0.05 mg of Mn(II) per liter, the chemical deposition rate was much greater than microbial deposition. Significant deposition occurred at 0.03 mg of manganese per liter, and dirty water complaints were not eliminated until manganese levels were continuously less than 0.02 mg/liter and chlorination levels were greater than 0.2 mg/liter. A guideline level of 0.01 mg of manganese per liter is recommended.
Effects of medium quality on the expression of human interleukin-2 at high cell density in fermentor cultures of Escherichia coli K-12
Authors: MacDonald H L , Neway J O
Published: January 2020

We examined the ability of transformed Escherichia coli cells in fermentor cultures to accumulate interleukin-2 (IL-2) intracellularly under temperature-regulated control of the phage lambda pL promoter. Induction of expression was undertaken at different culture optical densities, and specific IL-2 accumulation was found to decrease with increasing cell density at induction. Induction at higher culture optical densities was also accompanied by decreased growth during induction and increased acetate accumulation in the culture medium. Experiments were undertaken to study the effect of replacing spent medium by perfusion with fresh medium both before induction and during IL-2 expression at high cell density. Improved IL-2 expression was seen only when perfusion was continued past 1.6 h after the start of induction, and it was accompanied by a significant reduction in acetate buildup. Further improvements were not seen when perfusion was continued beyond hour 3 of induction. Replenishing medium components and decreasing the concentration of diffusible inhibitors before induction did not alleviate acetate buildup, growth limitation, or limitation of IL-2 synthesis. These results suggested that accumulation of diffusible inhibitors such as acetate during induction may be a significant factor limiting IL-2 expression in high-density cultures, but other factors intrinsic to the organism or the protein also played a major role.