bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Veratryl Alcohol and Hydrogen Peroxide on Ligninase Activity and Ligninase Production by
Phanerochaete chrysosporium
Authors: Tonon Frank , Odier Etienne
Published: January 2020

Veratryl alcohol, added as a supplement to cultures of
Phanerochaete chrysosporium
, enhanced ligninase activity through protection of the ligninase against inactivation by hydrogen peroxide produced by this fungus in cultures. In the presence of veratryl alcohol, the loss of ligninase activity observed in non-protein-synthesizing cultures (cycloheximide-treated) equaled the extracellular protein turnover. When cultures were not supplemented with veratryl alcohol, inactivation of ligninase by hydrogen peroxide added to protein turnover, resulting in a more rapid loss of ligninase activity. Although all ligninase isoenzymes are sensitive to inactivation by hydrogen peroxide, only the isoenzyme of the highest specific activity (80.6 nkat · mg of protein
−1
;
M
r
, 41,800; pI, 3.96) was found to be protected by veratryl alcohol. The concentration of veratryl alcohol necessary for full protection of ligninase activity varied according to the concentration of hydrogen peroxide present in the medium, which depended on the nature of the carbon source (glucose or glycerol). It is proposed that the nature of the carbon source influences the overall ligninase activity not only directly, by affecting the rate and the type of synthesized ligninase, but also by affecting the rate of hydrogen peroxide production, bringing about different rates of inactivation.
Effects of Mannose on the Growth of N
2
-Fixing
Azotobacter vinelandii
Authors: Wong Tit-Yee
Published: January 2020

Mannose is not a suitable substrate for N
2
-fixing
Azotobacter vinelandii
. However, when H
2
gas is provided,
A. vinelandii
can grow mixotrophically with H
2
as the energy source and mannose as the carbon source (T.-Y. Wong and R. J. Maier, J. Bacteriol. 163:528-533, 1985). In this report, seven sugars were used to determine whether
A. vinelandii
could derive energy from these sugars for mannose utilization. Supplementation of fructose- or galactose-limited medium with mannose did not influence the biomass produced by N
2
-fixing
A. vinelandii.
The presence of mannose in glucose- or maltose-limited cultures increased cell yield slightly. The addition of mannose decreased the total biomass in the melibiose-limited culture slightly. Mannose was a potent inhibitor of growth when sucrose or turanose was used as the primary sugar. The inhibitory effect of mannose on utilization of sucrose and turanose seems to be related to the energy requirement of the N
2
-fixing processes.
Synthetic enterotoxin B DNA probes for detection of enterotoxigenic Staphylococcus aureus strains
Authors: Notermans S , Heuvelman K J , Wernars K
Published: January 2020

DNA-DNA colony hybridization experiments with three different synthetic probes were carried out with 210 strains of Staphylococcus aureus. The synthetic probes encoded the amino acids 15 to 29 (probe 1), 179 to 192 (probe 2), and 207 to 219 (probe 3) of staphylococcal enterotoxin B (SEB). The amino acid sequences of these parts of SEB are identical to those of SEC1. All 21 SEB-producing strains tested reacted with each of the three probes. Of the 69 SEC-producing strains, 21 reacted with probe 1, none reacted with probe 2, and all 69 reacted with probe 3. With other strains no hybridization signals were obtained. The results presented here show that with a single synthetic DNA probe (probe 3) both SEB- and SEC-producing strains are detectable.
Use of a unique gene sequence as a probe to enumerate a strain of Bacteroides ruminicola introduced into the rumen
Authors: Attwood G T , Lockington R A , Xue G P , Brooker J D
Published: January 2020

Cloned fragments of genomic DNA from the ruminal anaerobe Bacteroides ruminicola subsp. brevis B14 were isolated and used as hybridization probes to identify closely related bacterial species. One DNA fragment unique to strain B14 was tested to determine its sensitivity in detecting homologous sequences among total ruminal microbial DNA. In a DNA titration experiment, the probe was capable of detecting strain B14 sequences in vitro down to 0.1% of the total bacterial DNA present in a hybridization assay. There was no detectable signal for total ruminal bacterial DNA. The specificity of this DNA fragment was exploited to enumerate strain B14 in a fresh mixed suspension of ruminal bacteria in vitro and after inoculation of the strain into the rumen. In vitro strain B14 had a half-life of 9 h. However, following inoculation into the rumen there was a very rapid loss of the strain to below the detectable limit within 3 h. The half-life was less than 30 min. This loss was not due to ruminal dilution or to bacteriophage attack but was possibly the result of a specific bacteriocinlike activity present in the rumen and detectable in fresh ruminal fluid.
Temporal and geographical distributions of epilithic sodium dodecyl sulfate-degrading bacteria in a polluted South Wales river
Authors: Anderson D J , Day M J , Russell N J , White G F
Published: January 2020

Epilithic bacteria were isolated nonselectively from riverbed stones and examined by gel zymography for their ability to produce alkylsulfatase (AS) enzymes and thus to metabolize alkyl sulfate surfactants such as sodium dodecyl sulfate. The percentages of AS+ isolates from stone epilithon at five sites from the source to the river mouth were measured on five sampling days spread over 1 year. The results showed that (i) the prevalence of epilithic AS+ strains (as a percentage of all isolates) was much higher at polluted sites than at the source; (ii) when averaged over the whole river, percentages of AS+ strains were significantly higher at the end of summer compared with either the preceding or the following winter; (iii) analysis of site-sampling time interactions indicated that water quality factors (e.g., biochemical oxygen demand and dissolved oxygen concentration) rather than climatic factors determined the distributions of epilithic AS+ isolates; (iv) constitutive strains were the most prevalent (7.2% of all isolates), with smaller numbers of isolates with inducible (4.5%) and repressible (1.7%) enzymes.
Trichloroethylene metabolism by microorganisms that degrade aromatic compounds
Authors: Nelson M J , Montgomery S O , Pritchard P H
Published: January 2020

Trichloroethylene (TCE) was metabolized by the natural microflora of three different environmental water samples when stimulated by the addition of either toluene or phenol. Two different strains of Pseudomonas putida that degrade toluene by a pathway containing a toluene dioxygenase also metabolized TCE. A mutant of one of these strains lacking an active toluene dioxygenase could not degrade TCE, but spontaneous revertants for toluene degradation also regained TCE-degradative ability. The results implicate toluene dioxygenase in TCE metabolism.
Isolation and identification of a morpholine-degrading bacterium
Authors: Cech J S , Hartman P , Slosárek M , Chudoba J
Published: January 2020

A gram-positive, slowly growing rod effectively utilizing morpholine as the sole source of organic carbon, nitrogen, and energy was isolated from a mixed culture in a laboratory reactor. The strain was tentatively identified as Mycobacterium aurum. Its growth characteristics at 20 degrees C and pH 6.5 were as follows: maximum specific growth rate, 0.052 h-1; half-velocity constant, 1.3 mg/liter; and yield, 0.37 g/g. The optimum temperature and pH were 31 degrees C and 6.0, respectively.
Expression of Solvent-Forming Enzymes and Onset of Solvent Production in Batch Cultures of
Clostridium beijerinckii
(“
Clostridium butylicum
”)
Authors: Yan Run-Tao , Zhu Chang-Xi , Golemboski Christine , Chen Jiann-Shin
Published: January 2020

Clostridium beijerinckii
(“
Clostridium butylicum
”) NRRL B592 and NRRL B593 were grown in batch cultures without pH control. The use of more sensitive and accurate procedures for the determination of solvents in cultures led to the recognition of the onset of solvent production about 2 h earlier than the previously assigned point and at a higher culture pH for both strains. Reliable assays for solvent-forming enzyme activities in cell extracts have also been developed. The results showed that activities of solvent-forming enzymes in strain NRRL B592 started to increase about 1 h before the measured onset of solvent production and that the increase in activities of solvent-forming enzymes was not simultaneous. The degree of increase of these enzyme activities for both strains ranged from 2- to 165-fold, with acetoacetate decarboxylase and butanol-isopropanol dehydrogenase showing the largest activity increases. However, the pattern of increase of enzyme activities differed significantly in the two strains of
C. beijerinckii.
When an increase in solvent-forming enzyme activities was first detected in strain NRRL B592, the culture pH was at 5.7 and the concentrations of total acetic and butyric acids were 5.2 and 3.6 mM, respectively. For strain NRRL B593, the corresponding pH was 5.5. Thus, the culture conditions immediately preceding the expression of solvent-forming enzyme activities differed significantly from those that have been correlated with the production of solvents at later stages of growth.
Seasonal and Diel Variability in Dissolved DNA and in Microbial Biomass and Activity in a Subtropical Estuary
Authors: Paul John H. , DeFlaun Mary F. , Jeffrey Wade H. , David Andrew W.
Published: January 2020

Dissolved DNA and microbial biomass and activity parameters were measured over a 15-month period at three stations along a salinity gradient in Tampa Bay, Fla. Dissolved DNA showed seasonal variation, with minimal values in December and January and maximal values in summer months (July and August). This pattern of seasonal variation followed that of particulate DNA and water temperature and did not correlate with bacterioplankton (direct counts and [
3
H]thymidine incorporation) or phytoplankton (chlorophyll
a
and
14
CO
2
fixation) biomass and activity. Microautotrophic populations showed maxima in the spring and fall, whereas microheterotrophic activity was greatest in late summer (September). Both autotrophic and heterotrophic microbial activity was greatest at the high estuarine (low salinity) station and lowest at the mouth of the bay (high salinity station), irrespective of season. Dissolved DNA carbon and phosphorus constituted 0.11 ± 0.05% of the dissolved organic carbon and 6.6 ± 6.5% of the dissolved organic phosphorus, respectively. Strong diel periodicity was noted in dissolved DNA and in microbial activity in Bayboro Harbor during the dry season. A noon maximum in primary productivity was followed by an 8 p.m. maximum in heterotrophic activity and a midnight maximum in dissolved DNA. This diel periodicity was less pronounced in the wet season, when microbial parameters were strongly influenced by episodic inputs of freshwater. These results suggest that seasonal and diel production of dissolved DNA is driven by primary production, either through direct DNA release by phytoplankton, or more likely, through growth of bacterioplankton on phytoplankton exudates, followed by excretion and lysis.
Optimization of Banana Juice Fermentation for the Production of Microbial Oil
Authors: Vega Esther Z. , Glatz Bonita A. , Hammond Earl G.
Published: January 2020

Apiotrichum curvatum
ATCC 20509 (formerly
Candida curvata
D), a lipid-accumulating yeast, was grown in banana juice. The optimum conditions for biomass production in shake flasks were 30°C growth temperature, efficient aeration, a juice concentration of 25%, and preliminary heat treatment at less than sterilization conditions. Under controlled conditions in a fermentor, 20% banana juice was optimum. High concentrations of yeast extract (0.3%) increased biomass production by 40% but decreased oil production by 30%. A lower yeast extract concentration (0.05%) increased biomass production by 2% and oil production by 25%. The best growth and oil production were observed when asparagine (1.4 g/liter) and mineral salts were added to the banana juice. The addition of minerals seemed to improve the utilization of carbon. Growth inhibition was observed when the fermentor was aerated with pure oxygen, even when additional nutrients were present. A fed-batch process permitted the juice concentration to be increased from 15 to 82%; biomass accumulation was three times higher than in batch fermentations. However, the cellular lipid content was only 30% of dry weight, and chemical oxygen demand reduction was slow and inefficient.
Isolation and characterization of "Methanosphaera cuniculi" sp. nov
Authors: Biavati B , Vasta M , Ferry J G
Published: January 2020

A nonmotile, gram-positive, spherical organism was isolated from the intestinal tracts of rabbits. Both hydrogen and methanol were required for growth. No methane was produced from hydrogen-carbon dioxide, formate, acetate, methylamines, ethanol, or isopropanol. The optimum pH was 6.8, and the optimum temperature was 35 to 40 degrees C. The DNA G+C content is 23 mol%. The pseudomurein cell wall contained serine. These characteristics and the immunological fingerprinting results are consistent with its placement in the genus Methanosphaera as a new species.
Amylolytic activity of selected species of ruminal bacteria
Authors: Cotta M A
Published: January 2020

A variety of species of ruminal bacteria were screened for the ability to grow in starch-containing medium and produce amylase. Of those tested, the highest levels of amylase were produced by Streptococcus bovis JB1 and Ruminobacter amylophilus H18. Other strains that grew well on starch and produced amylase included Butyrivibrio fibrisolvens A38 and 49 and Bacteroides ruminicola 23 and B14. Varying the carbohydrate source provided for growth resulted in changes in the growth rate and level of amylase produced by these strains. All strains grew rapidly in starch-containing medium, and the rates of growth were generally more rapid than those observed for maltose-grown cultures. For S. bovis JB1, B. ruminicola 23 and B14, and B. fibrisolvens 49 and A38, amylase was produced when growth was on maltose or starch, but this activity was greatly reduced in glucose-grown cultures. The distribution of amylolytic activity between cellular and extracellular fractions was sometimes affected by the carbohydrate provided for growth. If S. bovis JB1 and B. fibrisolvens 49 were grown on starch, amylase was largely associated with cell pellets; however, if grown on maltose these strains produced activities that were almost entirely present in the extracellular fluid fractions. Although not as dramatic, a similar shift in the location of amylase activities was noted for the two B. ruminicola strains when grown on the same substrates. Growth on maltose or starch had little influence on either the predominantly cell-associated activity of B. fibrisolvens A38 or the activity of R. amylophilus H18, which was equally divided between cell pellet and extracellular fluid fractions.(ABSTRACT TRUNCATED AT 250 WORDS)
Conjugal transfer of group B streptococcal plasmids and comobilization of Escherichia coli-Streptococcus shuttle plasmids to Lactobacillus plantarum
Authors: Shrago A W , Dobrogosz W J
Published: January 2020

The antibiotic resistance group B streptococcal plasmids, pIP501 and pVA797, were conjugally transferred from Streptococcus faecalis to Lactobacillus plantarum. The Escherichia coli-Streptococcus shuttle plasmids, pVA838 and pSA3, were mobilized from S. sanguis to L. plantarum by pVA797 via cointegrate formation. pVA838 readily resolved from pVA797 and was present in L. plantarum as deletion derivatives. The pVA797::pSA3 cointegrate failed to resolve in L. plantarum.
Eurotium spp. and echinulin in feed refused by swine
Authors: Vesonder R F , Lambert R , Wicklow D T , Biehl M L
Published: January 2020

Feed refused by swine contained a high-propagule density of Eurotium chevalieri Mangin (anamorph, Aspergillus chevalieri (Mangin) Thom and Church), Eurotium amstelodami Mangin (anamorph, Aspergillus amstelodami (Mangin Thom and Church), and Aspergillus candidus Link. Echinulin (8 micrograms/g of feed) was detected in the feed. Isolates of E. chevalieri and E. amstelodami but not A. candidus produced echinulin on rice or cracked corn. Mice refused to drink water containing 90 micrograms of echinulin per ml. This is the first report of the alkaloid echinulin in feed refused by swine.
Intergeneric rosettes: sequestered surface recognition among human periodontal bacteria
Authors: Kolenbrander P E , Andersen R N
Published: January 2020

The human oral bacteria, Streptococcus sanguis and Bacteroides loescheii, when mixed in equal numbers in vitro, formed large settling coaggregates. As the relative number of each cell type was changed, coaggregates became smaller until at cell-type ratios of 10 to 1, rosettes formed. Rosettes consisting of a streptococcal cell in the center surrounded by bacteroides cells exhibited surface recognition properties of only the bacteroides, which coaggregated with many other cell types such as Actinomyces naeslundii, and formed large settling multigeneric aggregates. The ecological significance of these results derives from the following: (i) the direct demonstration that intergeneric coaggregates can protect the central cell from or prevent its access to other cells in the environment, and (ii) the potential for these effects to occur during bacterial succession of various cell types observed in progressively more severe stages of human periodontal disease.
Effects of Metals on 3-Acetyldeoxynivalenol Production by
Fusarium graminearum
R2118 in Submerged Cultures
Authors: Vasavada Amit B. , Hsieh Dennis P. H.
Published: January 2020

The effects of selected metals (Mg
2+
, Mn
2+
, Zn
2+
, and Fe
2+
) on 3-acetyldeoxynivalenol (3-ADN) production by
Fusarium graminearum
R2118 and on its mycelial growth were investigated by using a two-stage submerged-culture technique. In certain concentrations ranges, Mg
2+
and Fe
2+
stimulated growth but suppressed 3-ADN production; at other concentrations, Mg
2+
, Fe
2+
, and Zn
2+
suppressed growth but stimulated 3-ADN production. In contrast, Mn
2+
stimulated growth but totally inhibited 3-ADN production at all concentrations tested. In general, the production of 3-ADN was inversely related to the growth rate of the fungus with these metals. Mn
2+
appears to be a crucial factor regulating the onset of 3-ADN biosynthesis.
Interference Competition among Coprophilous Fungi: Production of (+)-Isoepoxydon by
Poronia punctata
Authors: Gloer James B. , Truckenbrod S. M.
Published: January 2020

(+)-Isoepoxydon has been established as the major causative agent of interference competition between
Poronia punctata
(NRRL 6457), a late fungal colonist of cattle dung, and two early-occurring dung colonists,
Ascobolus furfuraceus
(NRRL 6460) and
Sordaria fimicola
(NRRL 6459). This compound was isolated from ethyl acetate extracts of liquid cultures of
P. punctata
by silica gel chromatography and identified by mass spectrometry and proton and carbon nuclear magnetic resonance spectroscopy. The isolation process was guided by in vitro bioassays for antifungal activity against
A. furfuraceus
and
S. fimicola.
(+)-Isoepoxydon has been implicated as an intermediate in the biosynthesis of patulin, a mycotoxin produced by
Penicillium
spp., but no patulin could be detected in cultures of
P. punctata.
Enrichment and isolation of a ruminal bacterium with a very high specific activity of ammonia production
Authors: Russell J B , Strobel H J , Chen G J
Published: January 2020

When mixed ruminal bacteria were inoculated into semicontinuous cultures (25% transfer every other day) containing lactate, dulcitol, pectin, or xylose and Trypticase (1 g/liter) as the sole nitrogen source, the specific activity of ammonia production increased. The greatest enrichment was observed with lactate and xylose, and in these cases the specific rate of ammonia production was eightfold higher than that of the ruminal fluid control (approximately 35 nmol of ammonia per mg of protein per min). Isolates with different morphologies were obtained from each of the enrichments, but in no case did the specific activity of any isolate exceed that of the mixed ruminal bacteria. If Trypticase (15 g/liter) was used as the only energy and nitrogen source, there was an even greater increase in ammonia production, and two monensin-sensitive bacteria, a Peptostreptococcus species and a Clostridium species, were obtained. The Peptostreptococcus species was unable to grow on any of 25 carbohydrate or carbohydrate derivatives tested; but the Clostridium species was able to use glucose, maltose, fructose, cellobiose, trehalose, sorbitol, and salicin as energy sources. Neither organism was able to grow in the absence of an amino acid source, but growth rates on Trypticase were greater than 0.35/h. The specific activities of ammonia production were 346 and 427 nmol/mg of protein per min for strains of Peptostreptococcus and Clostridium, respectively. Megasphaera elsdenii and Bacteroides ruminicola, previously isolated ruminal ammonia producers, had specific activities of only 11 and 19 nmol of ammonia per mg of protein per min, respectively. The most probable number of Clostridium species in ruminal fluid was less than 10(3)/ml, but the Peptostreptococcus species was present at 10(8)/ml.(ABSTRACT TRUNCATED AT 250 WORDS)
Development of Host Range Mutants of
Xanthomonas campestris
pv.
translucens
Authors: Mellano Valerie J. , Cooksey Donald A.
Published: January 2020

Xanthomonas campestris
pv.
translucens
is the causal agent of bacterial leaf streak of cereal grains and grasses, and individual strains within the pathovar differ in their host range among the cereals. Coinoculation of a wide-host-range and a narrow-host-range strain resulted in the wide-host-range reaction. Transposon and chemical mutagenesis of the wide-host-range strain Xct4, pathogenic on barley, wheat, rye, and triticale, resulted in variants with reduced host range. When pathogenicity was inactivated independently for barley, wheat, triticale, and rye, wild-type symptoms were retained on the other members in the host range. Testing of some host range mutants on additional varieties of the cereals indicated some cultivar specificity. In addition, mutants nonpathogenic on combinations of the hosts or on all hosts were isolated. This suggests that there are independent positive factors determining host range in this species, rather than an avirulence gene system such as those determining race specificity in other plant pathogens.
High-resolution solid-state 13C nuclear magnetic resonance of bacterial spores: identification of the alpha-carbon signal of dipicolinic acid
Authors: Lundin R E , Sacks L E
Published: January 2020

Natural-abundance solid-state 13C nuclear magnetic resonance spectra were obtained for bacterial spores for the first time by using the technique of cross-polarization magic-angle-spinning nuclear magnetic resonance spectroscopy. A resonance at about 150 ppm, detectable in spore samples having a Mn content of less than 0.05%, was consistent with an identification as the alpha-carbon signal of calcium dipicolinate; this signal was missing from a spore sample treated with acid to release dipicolinate and from a spore coat preparation. Carbohydrate peaks were particularly intense in spores and coat preparations of Bacillus macerans. Signals ascribable to beta-hydroxybutyrate were prominent in a B. cereus sample.
Transfer and Occurrence of Large Mercury Resistance Plasmids in River Epilithon
Authors: Bale M. J. , Fry J. C. , Day M. J.
Published: January 2020

In situ mating experiments were done in the River Taff, South Wales, United Kingdom, by using a natural mercury resistance plasmid (pQM1) isolated from a mixture of epilithic bacteria in vitro. The river temperature from March to November was found to influence transfer frequencies strongly (6.8 × 10
−9
to 1.5 × 10
−2
per recipient). A linear relationship existed between log
10
transfer frequency and river temperature (6 to 21°C), a 2.6°C change in temperature giving a 10-fold change in transfer frequency. In vitro experiments showed that pQM1 transferred most efficiently between fluorescent pseudomonads and that one epilithic isolate (
Pseudomonas fluorescens
) was an efficient donor in situ. Experiments with a
P. putida
recipient showed that intact epilithic bacterial communities could transfer mercury resistance plasmids in situ at frequencies of up to 3.75 × 10
−6
per recipient. Nineteen of the large (>250-kilobase) plasmids isolated by transfer into
P. putida
were studied in detail and grouped into seven types by restriction digests. Mercury resistance and UV resistance were found to be common linked phenotypes in 19 of the 23 plasmids tested.
Lysis of Halobacteria in Bacto-Peptone by Bile Acids
Authors: Kamekura Masahiro , Oesterhelt Dieter , Wallace Rebecca , Anderson Peter , Kushner Donn J.
Published: January 2020

All tested strains of halophilic archaebacteria of the genera
Halobacterium, Haloarcula, Haloferax
, and
Natronobacterium
lysed in 1% Bacto-Peptone (Difco) containing 25% NaCl, whereas no lysis was observed with other strains belonging to archaebacteria of the genera
Halococcus, Natronococcus
, and
Sulfolobus
, methanogenic bacteria, and moderately halophilic eubacteria. Substances in Bacto-Peptone which caused lysis of halobacteria were purified and identified as taurocholic acid and glycocholic acid. High-performance liquid chromatography analyses of peptones revealed that Bacto-Peptone contained nine different bile acids, with a total content of 9.53 mg/g, whereas much lower amounts were found in Peptone Bacteriological Technical (Difco) and Oxoid Peptone. Different kinds of peptones can be used to distinguish halophilic eubacteria and archaebacteria in mixed cultures from hypersaline environments.
Relationship between Methanogenic Cofactor Content and Maximum Specific Methanogenic Activity of Anaerobic Granular Sludges
Authors: Gorris Leon G. , de Kok Theo M. , Kroon Bernd M. , van der Drift Chris , Vogels Godfried D.
Published: January 2020

In this study we investigated whether a relationship exists between the methanogenic activity and the content of specific methanogenic cofactors of granular sludges cultured on different combinations of volatile fatty acids in upflow anaerobic sludge blanket or fluidized-bed reactors. Significant correlations were measured in both cases between the contents of coenzyme F
420
−2 or methanopterin and the maximum specific methanogenic activities on propionate, butyrate, and hydrogen, but not acetate. For both sludges the content of sarcinapterin appeared to be correlated with methanogenic activities on propionate, butyrate, and acetate, but not hydrogen. Similar correlations were measured with regard to the total content of coenzyme F
420
−4 and F
420
−5 in sludges from fluidized-bed reactors. The results indicate that the contents of specific methanogenic cofactors measured in anaerobic granular sludges can be used to estimate the hydrogenotrophic or acetotrophic methanogenic potential of these sludges.
Production, Distribution, and Kinetic Properties of Inulinase in Continuous Cultures of
Kluyveromyces marxianus
CBS 6556
Authors: Rouwenhorst Robert J. , Visser Leo E. , Van Der Baan Adriaan A. , Scheffers W. Alexander , Van Dijken Johannes P.
Published: January 2020

From a screening of several
Kluyveromyces
strains, the yeast
Kluyveromyces marxianus
CBS 6556 was selected for a study of the parameters relevant to the commercial production of inulinase (EC 3.2.1.7). This yeast exhibited superior properties with respect to growth at elevated temperatures (40 to 45°C), substrate specificity, and inulinase production. In sucrose-limited chemostat cultures growing on mineral medium, the amount of enzyme decreased from 52 U mg of cell dry weight
−1
at
D
= 0.1 h
−1
to 2 U mg of cell dry weight
−1
at
D
= 0.8 h
−1
. Experiments with nitrogen-limited cultures further confirmed that synthesis of the enzyme is negatively controlled by the residual sugar concentration in the culture. High enzyme activities were observed during growth on nonsugar substrates, indicating that synthesis of the enzyme is a result of a derepression/repression mechanism. A substantial part of the inulinase produced by
K. marxianus
was associated with the cell wall. The enzyme could be released from the cell wall via a simple chemical treatment of cells. Results are presented on the effect of cultivation conditions on the distribution of the enzyme. Inulinase was active with sucrose, raffinose, stachyose, and inulin as substrates and exhibited an S/I ratio (relative activities with sucrose and inulin) of 15 under standard assay conditions. The enzyme activity decreased with increasing chain length of the substrate.
Rapid and correct identification of intestinal Bacteroides spp. with chromosomal DNA probes by whole-cell dot blot hybridization
Authors: Morotomi M , Ohno T , Mutai M
Published: January 2020

A dot blot hybridization procedure with 32P-labeled whole chromosomal DNA of the type strains as probes was developed as a rapid and simple method for identification of intestinal Bacteroides species. Bacterial cells were fixed onto membrane filters by slight suction, treated with 0.5 N NaOH, and hybridized with these probes. Of 65 Bacteroides strains isolated from 19 human fecal specimens, which were identified as B. fragilis, B. thetaiotaomicron, B. ovatus, B. caccae, B. uniformis, B. stercoris, B. vulgatus, B. distasonis, and B. merdae by conventional phenotypic characterization, 62 (95%) were correctly identified with this hybridization procedure.
Degradation of polycyclic aromatic hydrocarbon compounds under various redox conditions in soil-water systems
Authors: Mihelcic J R , Luthy R G
Published: January 2020

This study evaluated the microbial degradation of naphthol, naphthalene, and acenaphthene, under aerobic, anaerobic, and denitrification conditions in soil-water systems. Chemical degradation of naphthol and naphthalene in the presence of a manganese oxide was also studied. Naphthol, naphthalene, and acenaphthene were degraded microbially under aerobic conditions from initial aqueous-phase concentrations of 9, 7, and 1 mg/liter to nondetectable levels in 3, 10, and 10 days, respectively. Under anaerobic conditions naphthol degraded to nondetectable levels in 15 days, whereas naphthalene and acenaphthene showed no significant degradation over periods of 50 and 70 days, respectively. Under denitrification conditions naphthol, naphthalene, and acenaphthene were degraded from initial aqueous-phase concentrations of 8, 7, and 0.4 mg/liter to nondetectable levels in 16, 45, and 40 days, respectively. Acclimation periods of approximately 2 days under aerobic conditions and 2 weeks under denitrification conditions were observed for both naphthalene and acenaphthene. Abiotic degradation of naphthalen and naphthol were evaluated by reaction with manganese oxide, a minor soil constituent. In the presence of a manganese oxide, naphthalene showed no abiotic degradation over a period of 9 weeks, whereas the aqueous naphthol concentration decreased from 9 mg/liter to nondetectable levels in 9 days. The results of this study show that low-molecular-weight, unsubstituted, polycyclic aromatic hydrocarbons are amenable to microbial degradation in soil-water systems under denitrification conditions.
Role of Antibiosis in Competition of
Erwinia
Strains in Potato Infection Courts
Authors: Axelrood Paige E. , Rella Manuela , Schroth Milton N.
Published: January 2020

Erwinia carotovora
subsp.
betavasculorum
strains produced a bactericidal antibiotic in vitro that inhibited a wide spectrum of gram-negative and gram-positive bacteria. The optimum temperature for production was 24°C, and the addition of glycerol to culture media enhanced antibiotic production. Antibiotic production by these strains in the infection court of potato was the principal determinant enabling it to gain ascendancy over competing antibiotic-sensitive
Erwinia carotovora
subsp.
carotovora
strains. There was a complete correlation between antibiotic production by
E. carotovora
subsp.
betavasculorum
in vitro and inhibition of competing
E. carotovora
subsp.
carotovora
strains in planta. Inhibition of the latter by the former was apparent after 10 h of incubation in potato tuber wounds. Population densities of sensitive
E. carotovora
subsp.
carotovora
strains in mixed potato tuber infections with
E. carotovora
subsp.
betavasculorum
were approximately 10
6
-fold lower after 48 h of incubation than in corresponding single sensitive strain infections.
E. carotovora
subsp.
carotovora
were not inhibited in tuber infections that were incubated anaerobically. This correlated with the absence of antibiotic production during anaerobic incubation in vitro. Antibiotic-resistant strains of
E. carotovora
subsp.
carotovora
were not inhibited in planta or in vitro by
E. carotovora
subsp.
betavasculorum.
Moreover, isogenic antibiotic-negative (Ant
−
) mutant
E. carotovora
subsp.
betavasculorum
strains were not inhibitory to sensitive
E. carotovora
subsp.
carotovora
strains in tuber infections.
Metabolism of the 18O-methoxy substituent of 3-methoxybenzoic acid and other unlabeled methoxybenzoic acids by anaerobic bacteria
Authors: DeWeerd K A , Saxena A , Nagle D P , Suflita J M
Published: January 2020

O-methyl substituents of aromatic compounds can provide C1 growth substrates for facultative and strict anaerobic bacteria isolated from diverse environments. The mechanism of the bioconversion of methoxylated benzoic acids to the hydroxylated derivatives was investigated with a model substrate and cultures of one anaerobic consortium, eight strict anaerobic bacteria, and one facultative anaerobic microorganism. Using high-pressure liquid chromatography and gas chromatography-mass spectral analysis, we found that a haloaromatic dehalogenating consortium, a dehalogenating isolate from that consortium, Eubacterium limosum, and a strain of Acetobacterium woodii metabolized 3-[methoxy-18O]methoxybenzoic acid (3-anisic acid) to 3-[hydroxy-18O]hydroxybenzoic acid stoichiometrically at rates of 1.5, 3.2, 52.4, and 36.7 nmol/min per mg of protein, respectively. A different strain of Acetobacterium and strains of Syntrophococcus, Clostridium, Desulfotomaculum, Enterobacter, and an anaerobic bacterium, strain TH-001, were unable to transform this compound. The O-demethylating ability of E. limosum was induced only with appropriate methoxylated benzoates but not with D-glucose, lactate, isoleucine, or methanol. Cross-acclimation and growth experiments with E. limosum showed a rate of metabolism that was an order of magnitude slower and showed no growth with either 4-methoxysalicylic acid (2-hydroxy-4-methoxybenzoic acid) or 4-anisic acid (4-methoxybenzoic acid) when adapted to 3-anisic acid. However, A. woodii NZva-16 showed slower rates and no growth with 3- or 4-methoxysalicylic acid when adapted to 3-anisic acid in similar experiments. The results clearly indicate a methyl rather than methoxy group removal mechanism for such reactions.
Diversity of Plasmid Profiles and Conservation of Symbiotic Nitrogen Fixation Genes in Newly Isolated
Rhizobium
Strains Nodulating Sulla (
Hedysarum coronarium
L.)
Authors: Mozo Teresa , Cabrera Ezequiel , Ruiz-Argüeso Tomás
Published: January 2020

Forty-five
Rhizobium
strains nodulating sulla (
Hedysarum coronarium
L.), isolated from plants grown in different sites in Menorca Island and southern Spain, were examined for plasmid content and the location and organization of
nif
(nitrogen fixation) and
nod
(nodulation) sequences. A great diversity in both number and size of the plasmids was observed in this native population of strains, which could be distributed among 19 different groups according to their plasmid profiles. No correlation was found between plasmid profile and geographical origin of the strains. In each strain a single plasmid ranging from 187 to 349 megadaltons hybridized to
Rhizobium meliloti nifHD
and
nodD
DNA, and in three strains the spontaneous loss of this plasmid resulted in the loss of the nodulation capacity. In addition to the symbiotic plasmid, 18 different cryptic plasmids were identified. A characteristic cryptic plasmid of >1,000 megadaltons was present in all strains. Total DNA hybridization experiments, with
nifHD
and portions of
nodC
and
nodD
genes (coding for common nodulation functions) from
R. meliloti
as probes, demonstrated that both the sequence and organization of
nif
and common
nod
genes were highly conserved within rhizobia nodulating sulla. Evidence for reiteration of
nodD
sequences and for linkage of
nodC
to at least one copy of
nodD
was obtained for all the strains examined. From these results we conclude that
Rhizobium
strains nodulating sulla are a homogeneous group of symbiotic bacteria that are closely related to the classical fast-growing group of rhizobia.
Effects of some alkyl phenols on methanogenic degradation of phenol
Authors: Wang Y T , Suidan M T , Pfeffer J T , Najm I
Published: January 2020

The effects of six phenolic compounds (o-, m-, and p-cresol and 2-, 3-, and 4-ethylphenol) on the anaerobic biodegradation of phenol was examined in batch methanogenic cultures. Results showed that ethylphenols were more inhibitory of phenol degradation than were cresols. The inhibitory effects of the three isomers of cresol and ethylphenol did not vary with the isomer but rather with the substituted functional group.
Narrow- and Broad-Host-Range Symbiotic Plasmids of
Rhizobium
spp. Strains That Nodulate
Phaseolus vulgaris
Authors: Brom Susana , Martinez Esperanza , Dávila Guillermo , Palacios Rafael
Published: January 2020

Agrobacterium
transconjugants containing symbiotic plasmids from different
Rhizobium
spp. strains that nodulate
Phaseolus vulgaris
were obtained. All transconjugants conserved the parental nodulation host range. Symbiotic (Sym) plasmids of
Rhizobium
strains isolated originally from
P. vulgaris
nodules, which had a broad nodulation host range, and single-copy nitrogenase genes conferred a Fix
+
phenotype to the
Agrobacterium
transconjugants. A Fix
−
phenotype was obtained with Sym plasmids of strains isolated from
P. vulgaris
nodules that had a narrow host range and reiterated
nif
genes, as well as with Sym plasmids of strains isolated from other legumes that presented single
nif
genes and a broad nodulation host range. This indicates that different types of Sym plasmids can confer the ability to establish an effective symbiosis with
P. vulgaris.
Frequency and Characteristics of Plasmids in Bacteria Isolated from Deep-Sea Amphipods
Authors: Wortman Alan T. , Colwell Rita R.
Published: January 2020

Bacterial strains isolated from deep-sea amphipods were identified, classified, and screened for plasmid content. Plasmids were common, with 11 of 16 isolates carrying one or more plasmids; these ranged in size from 2.9 to 63 megadaltons. Several of the strains demonstrated distinctly different phenotypic traits yet contained plasmids of the same molecular weight. Results of agarose gel electrophoresis, DNA hybridization, and restriction analysis indicate that the plasmids detected in these deep-sea isolates are identical, suggesting that transmission may occur in the deep-sea environment and that plasmids are common in some deep-sea habitats.
Enumeration of Free-Living Aerobic N
2
-Fixing H
2
-Oxidizing Bacteria by Using a Heterotrophic Semisolid Medium and Most-Probable-Number Technique
Authors: Barraquio Wilfredo L. , Dumont Ann , Knowles Roger
Published: January 2020

A heterotrophic semisolid medium was used with two sensitive assay methods, C
2
H
2
reduction and O
2
-dependent tritium uptake, to determine nitrogenase and hydrogenase activities, respectively. Organisms known to be positive for both activities showed hydrogenase activity in both the presence and absence of 1% C
2
H
2
, and thus, it was possible to test a single culture for both activities. Hydrogen uptake activity was detected for the first time in N
2
-fixing strains of
Pseudomonas stutzeri.
The method was then applied to the most-probable-number method of counting N
2
-fixing and H
2
-oxidizing bacteria in some natural systems. The numbers of H
2
-oxidizing diazotrophs were considerably higher in soil surrounding nodules of white beans than they were in the other systems tested. This observation is consistent with reports that the rhizosphere may be an important ecological niche for H
2
transformation.
Novel approach for modifying microporous filters for virus concentration from water
Authors: Preston D R , Vasudevan T V , Bitton G , Farrah S R , Morel J L
Published: January 2020

Electronegative microporous filters composed of epoxyfiberglass (Filterite) were treated with cationic polymers to enhance their virus-adsorbing properties. This novel and inexpensive approach to microporous filter modification entails soaking filters in an aqueous solution of a cationic polymer such as polyethyleneimine (PEI) for 2 h at room temperature and then allowing the filters to air dry overnight on absorbent paper towels. PEI-treated filters were evaluated for coliphage (MS2, T2, and phi X174) and enterovirus (poliovirus type 1 and coxsackievirus type B5) adsorption from buffer at pH 3.5 to 9.0 and for indigenous coliphages from unchlorinated secondary effluent at ambient pH. Adsorbed viruses were recovered with 3% beef extract (pH 9). Several other cationic polymers were used to modify epoxyfiberglass filters and were evaluated for their ability to concentrate viruses from water. Zeta potentials of disrupted filter material indicated that electronegative epoxyfiberglass filters were made more electropositive when treated with cationic polymers. In general, epoxyfiberglass filters treated with cationic polymers were found to adsorb a greater percentage of coliphages and enteroviruses than were untreated filters.
Microbial Biomass, Activity, and Community Structure of Water and Particulates Retrieved by Backflow from a Waterflood Injection Well
Authors: McKinley Vicky L. , Costerton J. William , White David C.
Published: January 2020

Oil field injection water was allowed to back flow from two wells at the Packard drill site in Los Angeles, Calif., and was sampled at various times to obtain information about the biomass, potential activity, and community structure of the microbiota in the reservoir formation and in the injection water. Biomass was greatest in water samples that came from the zone near the injection site and dropped off sharply in subsequent samples, which were assumed to come from zones farther away from the well. Samples obtained from near the well also had visible exopolysaccharide blankets, as seen in scanning electron microscopic preparations. In one of the wells that was sampled, rates of glucose or acetate incorporation into microbial lipids correlated with biomass; but in the other well, activities correlated with the sampling time (volume of water that back flowed). Transmission electron micrographs showed a diverse, gram-negative bacterial population in a variety of physiological states. The analysis of the phospholipid ester-linked fatty acid profiles of the samples revealed consistently large proportions of 18:1ω7c fatty acids, indicating the presence of many anaerobes, facultative organisms, or both. Proportions of cyclopropyl fatty acids and ratios of
trans/cis
monoenoic compounds increased with the volume of water that back flowed (analogous with the distance into the formation), while the ratio of unsaturated/saturated compounds decreased, possibly indicating higher levels of stress or starvation in the microbial communities farthest from the injection well. Greater than 90% of the total biomass was trapped on glass fiber filters, indicating that the microbiota were largely attached to particles or were clumped. These sampling techniques and analytical methods may prove useful in monitoring for problems with microbes (e.g., plugging) in waterflood operations and in the preparation of water injection wells for enhanced oil recovery by the use of microbes.
The mannoprotein of Saccharomyces cerevisiae is an effective bioemulsifier
Authors: Cameron D R , Cooper D G , Neufeld R J
Published: January 2020

The mannoprotein which is a major component of the cell wall of Saccharomyces cerevisiae is an effective bioemulsifier. Mannoprotein emulsifier was extracted in a high yield from whole cells of fresh bakers' yeast by two methods, by autoclaving in neutral citrate buffer and by digestion with Zymolase (Miles Laboratories; Toronto, Ontario, Canada), a beta-1,3-glucanase. Heat-extracted emulsifier was purified by ultrafiltration and contained approximately 44% carbohydrate (mannose) and 17% protein. Treatment of the emulsifier with protease eliminated emulsification. Kerosene-in-water emulsions were stabilized over a broad range of conditions, from pH 2 to 11, with up to 5% sodium chloride or up to 50% ethanol in the aqueous phase. In the presence of a low concentration of various solutes, emulsions were stable to three cycles of freezing and thawing. An emulsifying agent was extracted from each species or strain of yeast tested, including 13 species of genera other than Saccharomyces. Spent yeast from the manufacture of beer and wine was demonstrated to be a possible source for the large-scale production of this bioemulsifier.
Novel Mode of Microbial Energy Metabolism: Organic Carbon Oxidation Coupled to Dissimilatory Reduction of Iron or Manganese
Authors: Lovley Derek R. , Phillips Elizabeth J. P.
Published: January 2020

A dissimilatory Fe(III)- and Mn(IV)-reducing microorganism was isolated from freshwater sediments of the Potomac River, Maryland. The isolate, designated GS-15, grew in defined anaerobic medium with acetate as the sole electron donor and Fe(III), Mn(IV), or nitrate as the sole electron acceptor. GS-15 oxidized acetate to carbon dioxide with the concomitant reduction of amorphic Fe(III) oxide to magnetite (Fe
3
O
4
). When Fe(III) citrate replaced amorphic Fe(III) oxide as the electron acceptor, GS-15 grew faster and reduced all of the added Fe(III) to Fe(II). GS-15 reduced a natural amorphic Fe(III) oxide but did not significantly reduce highly crystalline Fe(III) forms. Fe(III) was reduced optimally at pH 6.7 to 7 and at 30 to 35°C. Ethanol, butyrate, and propionate could also serve as electron donors for Fe(III) reduction. A variety of other organic compounds and hydrogen could not. MnO
2
was completely reduced to Mn(II), which precipitated as rhodochrosite (MnCO
3
). Nitrate was reduced to ammonia. Oxygen could not serve as an electron acceptor, and it inhibited growth with the other electron acceptors. This is the first demonstration that microorganisms can completely oxidize organic compounds with Fe(III) or Mn(IV) as the sole electron acceptor and that oxidation of organic matter coupled to dissimilatory Fe(III) or Mn(IV) reduction can yield energy for microbial growth. GS-15 provides a model for how enzymatically catalyzed reactions can be quantitatively significant mechanisms for the reduction of iron and manganese in anaerobic environments.