bluuebunny/crossref_metadata_2025 huggingface dataset:
Serological Relatedness of
Rhizobium fredii
to Other Rhizobia and to the Bradyrhizobia
Authors: Sadowsky Michael J. , Bohlool B. Ben , Keyser Harold H.
Published: January 2020

Several isolates of
Rhizobium fredii
were examined for their serological relatedness to each other, to
Bradyrhizobium japonicum
, and to other fast- and slow-growing rhizobia. Immunofluorescence, agglutination, and immunodiffusion analyses indicated that
R. fredii
contains at least three separate somatic serogroups, USDA 192, USDA 194, and USDA 205. There was no cross-reaction between any of the
R. fredii
isolates and 13 of the 14
B. japonicum
somatic serogroups tested. Cross-reactions were obtained with antisera from
R. fredii
and serogroup 122 of
B. japonicum, Rhizobium meliloti
, and several fast-growing
Rhizobium
spp. for
Leucaena, Sesbania
, and
Lablab
species. The serological relationship between
R. fredii
and
R. meliloti
was examined in more detail, and of 23
R. meliloti
strains examined, 8 shared somatic antigens with the type strains from all three
R. fredii
serogroups. The serological relatedness of
R. fredii
to
B. japonicum
and
R. meliloti
appears to be unique since the strains are known to be biochemically and genetically diverse.
Presence of Giardia spp. and absence of Salmonella spp. in New Jersey muskrats (Ondatra zibethicus)
Authors: Kirkpatrick C E , Benson C E
Published: January 2020

Of 220 muskrat fecal specimens collected from 12 sites in southwestern New Jersey, 154 (70%) were found to contain cysts of the protozoan parasite Giardia spp. Cysts from selected muskrat fecal specimens infected Mongolian gerbils, but attempts to cultivate trophozoites removed from these gerbils were unsuccessful. Salmonella spp. were not detected in any of the muskrat fecal specimens.
Microbial degradation of oxalate in the gastrointestinal tracts of rats
Authors: Daniel S L , Hartman P A , Allison M J
Published: January 2020

Rates of oxalate degradation by mixed bacterial populations in cecal contents from wild rats ranged from 2.5 to 20.6 mumol/g (dry weight) per h. The oxalate-degrading activity in cecal contents from three strains of laboratory rats (Long-Evans, Wistar, and Sprague-Dawley) from four commercial breeders was generally lower, ranging from 1.8 to 3.5 mumol/g (dry weight) of cecal contents per h. This activity did not increase when diets were supplemented with oxalate. When Sprague-Dawley rats from a fifth commercial breeder were fed an oxalate diet, rates of oxalate degradation in cecal contents increased from 2.0 to 23.1 mumol/g (dry weight) per h. Obligately anaerobic, oxalate-degrading bacteria, similar to ruminal strains of Oxalobacter formigenes, were isolated from the latter group of laboratory rats and from wild rats. Viable counts of these bacteria were as high as 10(8)/g (dry weight) of cecal contents, which was less than 0.1% of the total viable population. This report presents the first evidence for the presence of anaerobic oxalate-degrading bacteria in the cecal contents of rats and represents the first direct measurement of the concentration of these bacteria in the large bowel of monogastric animals. We propose that methods used for the maintenance of most commercial rat colonies often preclude the intestinal colonization of laboratory rats with anaerobic oxalate-degrading bacteria.
Isolation and Characterization of a Catabolite Repression-Insensitive Mutant of a Methanol Yeast,
Candida boidinii
A5, Producing Alcohol Oxidase in Glucose-Containing Medium
Authors: Sakai Yasuyoshi , Sawai Tohru , Tani Yoshiki
Published: January 2020

Mutants exhibiting alcohol oxidase (EC 1.1.3.13) activity when grown on glucose in the presence of methanol were found among 2-deoxyglucose-resistant mutants derived from a methanol yeast,
Candida boidinii
A5. One of these mutants, strain ADU-15, showed the highest alcohol oxidase activity in glucose-containing medium. The growth characteristics and also the induction and degradation of alcohol oxidase were compared with the parent strain and mutant strain ADU-15. In the parent strain, initiation of alcohol oxidase synthesis was delayed by the addition of 0.5% glucose to the methanol medium, whereas it was not delayed in mutant strain ADU-15. This showed that alcohol oxidase underwent repression by glucose. On the other hand, degradation of alcohol oxidase after transfer of the cells from methanol to glucose medium (catabolite inactivation) was observed to proceed at similar rates in parent and mutant strains. The results of immunochemical titration experiments suggest that catabolite inactivation of alcohol oxidase is coupled with a quantitative change in the enzyme. Mutant strain ADU-15 was proved to be a catabolite repression-insensitive mutant and to produce alcohol oxidase in the presence of glucose. However, it was not an overproducer of alcohol oxidase and, in both the parent and mutant strains, alcohol oxidase was completely repressed by ethanol.
Ancymidol blocks trichothecene biosynthesis and leads to accumulation of trichodiene in Fusarium sporotrichioides and Gibberella pulicaris
Authors: Desjardins A E , Plattner R D , Beremand M N
Published: January 2020

Ancymidol, a plant growth regulator, inhibited biosynthesis of diacetoxyscirpenol by Gibberella pulicaris (Fusarium sambucinum) in a defined liquid medium. Ancymidol also inhibited biosynthesis of T-2 toxin by a wild-type strain of Fusarium sporotrichioides and biosynthesis of diacetoxyscirpenol, deacetylated calonectrin, and dideacetylated calonectrin by mutant strains of this species. Ancymidol-treated cultures accumulated the hydrocarbon trichodiene, a biosynthetic precursor of the trichothecenes. Ancymidol did not block trichodiene accumulation by a trichodiene-producing mutant strain of F. sporotrichioides. Ancymidol appears to block the trichothecene biosynthetic pathway after formation of trichodiene and before formation of trichothecenes containing four or more oxygen atoms.
High-Pressure Equipment for Growing Methanogenic Microorganisms on Gaseous Substrates at High Temperature
Authors: Bernhardt Günther , Jaenicke Rainer , Lüdemann Hans-Dietrich
Published: January 2020

High-pressure, high-temperature investigations on thermophilic microorganisms that grow on hydrogen or other gaseous substrates require instrumentation which provides sufficient substrate for cell proliferation up to 2 × 10
8
to 3 × 10
8
cells per ml under isothermal and isobaric conditions. To minimize H
2
leakage and to optimize reproducibility at high pressure and high temperature, 10-ml nickel tubes with a liquid/gas ratio of 1:2 were used in a set of autoclaves connected in series. By applying a hydraulic pump and a 2.5-kW heating device, fast changes in temperature (up to 400°C) and pressure (up to 400 MPa) can be accomplished within less than 10 min. To quantify bacterial growth, determinations of cell numbers per unit volume yielded optimum accuracy. Preliminary experiments with the thermophilic, methanogenic archaebacterium
Methanococcus thermolithotrophicus
showed that bacterial growth depends on both temperature and pressure. At the optimum temperature, increased hydrostatic pressure up to 50 MPa enhanced the growth yield; at a pressure of >75 MPa, cell lysis dominated. Changes in cell proliferation were accompanied by changes in morphology.
Properties of Alanine Dehydrogenase and Aspartase from
Propionibacterium freudenreichii
subsp.
shermanii
Authors: Crow Vaughan L.
Published: January 2020

During lactate fermentation by
Propionibacterium freudenreichii
subsp.
shermanii
ATCC 9614, the only amino acid metabolized was aspartate. After lactate exhaustion, alanine was one of the two amino acids to be metabolized. For every 3 mol of alanine metabolized, 2 mol of propionate, 1 mol each of acetate and CO
2
, and 3 mol of ammonia were formed. The specific activity of alanine dehydrogenase was 0.08 U/mg of protein during lactate fermentation, and it increased to 0.9 U/mg of protein after lactate exhaustion. Alanine dehydrogenase and aspartase, key enzymes in the metabolism of alanine and aspartate, respectively, were partially purified, and some of their properties were studied. Alanine dehydrogenase had a pH optimum of 9.2 to 9.6 and high

K
m

values for both NAD
+
(1 to 4 mM) and alanine (7 to 20 mM). Activity was inhibited by low concentrations of pyruvate and NADH. The pH optimum of aspartase decreased from ∼7.5 to ∼6.4 when the MgCl
2
and aspartate concentrations were decreased. Plots of aspartate concentration versus activity showed either hyperbolic or sigmoidal kinetics (interaction coefficient, up to a value of 3.1), depending on pH and MgCl
2
concentration. MgCl
2
was either an activator or an inhibitor, depending on pH and its concentration. Aspartase activity was inhibited by low concentrations of fumarate. The properties of alanine dehydrogenase and aspartase are consistent with the finding that aspartate is metabolized during lactate fermentation, while alanine is only fermented after lactate exhaustion and then at a slow rate.
Fractionation of Stable Carbon Isotopes during Chemoautotrophic Growth of Sulfur-Oxidizing Bacteria
Authors: Ruby Edward G. , Jannasch Holger W. , Deuser Werner G.
Published: January 2020

Laboratory-grown strains of chemoautotrophic
Thiomicrospira
sp. strain L-12 and
Thiobacillus neapolitanus
produced cell carbon that was 24.6 to 25.1 ppt (24.6 to 25.1 mg/g) lower in
13
C isotope abundance than the ambient source of carbon dioxide and bicarbonate. This degree of
13
C isotope depletion was comparable to that found in organic material produced in deep-sea hydrothermal-vent communities.
Plasmid-encoded copper resistance and precipitation by Mycobacterium scrofulaceum
Authors: Erardi F X , Failla M L , Falkinham J O
Published: January 2020

A copper-tolerant Mycobacterium scrofulaceum strain was able to remove copper from culture medium by sulfate-dependent precipitation as copper sulfide. Such precipitation of copper sulfide was not observed in a derivative that lacks a 173-kilobase plasmid. In addition, the plasmid-carrying strain has a sulfate-independent copper resistance mechanism.
Transposon Mutants of
Bradyrhizobium japonicum
Altered in Attachment to Host Roots
Authors: Vesper Stephen J. , Malik Nasir S. A. , Bauer Wolfgang D.
Published: January 2020

Transposon mutants of
Bradyrhizobium japonicum
110 ARS were produced and screened for changes in attachment ability. Mutant CFK4 produced twice as many piliated cells, attached in 2.5-fold-higher numbers to soybean root segments, and colonized roots in about 2-fold-higher numbers than did the parental strain, 110 ARS. Mutants CFK35 and CFK38 were reduced in their attachment about 2-fold and 3.5-fold, respectively. This corresponded to reductions in piliated cells in their populations, reduced reaction with anti-pilus antiserum, and reduced hydrophobic attachment. Mutants CFK4 and CFK38 nodulated soybeans at about the same level as the parent strain, but CFK35 induced only pseudonodules. Two-dimensional gel analyses of the proteins from the mutants showed relatively few changes in proteins.
Use of
Chloroflexus
-Specific Antiserum To Evaluate Filamentous Bacteria of a Hot Spring Microbial Mat
Authors: Tayne Timothy A. , Cutler Jim E. , Ward David M.
Published: January 2020

Polyclonal antiserum prepared against
Chloroflexus aurantiacus
reacted with all
Chloroflexus
strains examined but not with other morphologically or physiologically similar bacteria. Only one of three filament types in a natural hot spring cyanobacterial mat reacted with this antiserum. Reacting filaments remained antigenically positive deep within the mat in material estimated to be several years old.
Occurrence of toxicity among protease, amylase, and color mutants of a nontoxic soy sauce koji mold
Authors: Kalayanamitr A , Bhumiratana A , Flegel T W , Glinsukon T , Shinmyo A
Published: January 2020

A soy sauce koji mold, Aspergillus flavus var. columnaris Raper and Fennel (ATCC 44310), was treated with UV irradiation to obtain mutant strains possessing high protease activities, high amylase activities, and light-colored conidia. Selected mutant strains were tested for toxicity, and some were found acutely toxic to weanling rats, although all were negative for aflatoxin production.
Development of a defined medium and two-step culturing method for improved exotoxin A yields from Pseudomonas aeruginosa
Authors: Blumentals I I , Kelly R M , Gorziglia M , Kaufman J B , Shiloach J
Published: January 2020

A two-step method is described for the production of exotoxin A by Pseudomonas aeruginosa in which a defined growth medium is modified for the toxin production phase. As a result, specific exotoxin A yields comparable to those obtained with complex media were achieved. In the development of this two-step process, several divalent metallic cations (Ca2+, Cu2+, and Mn2+), in addition to iron, were found to inhibit the yield of exotoxin A while Ca2+ and glycerol were found to increase yields. Northern blot analysis of total RNA isolates suggests that these effects on exotoxin A yields are based on events at the transcription level.
Oxidation of Dimethyl Sulfide to Dimethyl Sulfoxide by Phototrophic Purple Bacteria
Authors: Zeyer Josef , Eicher Petra , Wakeham Stuart G. , Schwarzenbach René P.
Published: January 2020

Enrichment cultures of phototrophic purple bacteria rapidly oxidized up to 10 mM dimethyl sulfide (DMS) to dimethyl sulfoxide (DMSO). DMSO was qualitatively identified by proton nuclear magnetic resonance. By using a biological assay, DMSO was always quantitatively recovered from the culture media. DMS oxidation was not detected in cultures incubated in the dark, and it was slow in cultures exposed to full daylight. Under optimal conditions, the second-order rate constant for DMS oxidation was 6 day
−1
mg of protein
−1
ml
−1
. The rate constant was reduced in the presence of high concentration of sulfide (>1 mM), but was not affected by the addition of acetate. DMS was also oxidized to DMSO by a pure strain (tentatively identified as a
Thiocystis
sp.) isolated from the enrichment cultures. DMS supported growth of the enrichment cultures and of the pure strain by serving as an electron source for photosynthesis. A determination of the amount of protein produced in the cultures and an estimation of the electron balance suggested that the two electrons liberated during the oxidation of DMS to DMSO were quantitatively used to reduce carbon dioxide to biomass. The oxidation of DMS by phototrophic purple bacteria may be an important source of DMSO detected in anaerobic ponds and marshes.
Inactivation of animal viruses during sewage sludge treatment
Authors: Spillmann S K , Traub F , Schwyzer M , Wyler R
Published: January 2020

Using a previously developed filter adsorption technique, the inactivation of a human rotavirus, a coxsackievirus B5, and a bovine parvovirus was monitored during sludge treatment processes. During conventional anaerobic mesophilic digestion at 35 to 36 degrees C, only minor inactivation of all three viruses occurred. The k' values measured were 0.314 log10 unit/day for rotavirus, 0.475 log10 unit/day for coxsackievirus B5, and 0.944 log10 unit/day for parvovirus. However, anaerobic thermophilic digestion at 54 to 56 degrees C led to rapid inactivation of rotavirus (k' greater than 8.5 log10 units/h) and of coxsackievirus B5 (k' greater than 0.93 log10 unit/min). Similarly, aerobic thermophilic fermentation at 60 to 61 degrees C rapidly inactivated rotavirus (k' = 0.75 log10 unit/min) and coxsackievirus B5 (k' greater than 1.67 log10 units/min). Infectivity of parvovirus, however, was only reduced by 0.213 log10 unit/h during anaerobic thermophilic digestion and by 0.353 log10 unit/h during aerobic thermophilic fermentation. Furthermore, pasteurization at 70 degrees C for 30 min inactivated the parvovirus by 0.72 log10 unit/30 min. In all experiments the contribution of temperature to the total inactivation was determined separately and was found to be predominant at process temperatures above 54 degrees C. In conclusion, the most favorable treatment to render sludge hygienically safe from the virological point of view would be a thermal treatment (60 degrees C) to inactivate thermolabile viruses, followed by an anaerobic mesophilic digestion to eliminate thermostable viruses that are more sensitive to chemical and microbial inactivations.
Microcycle Conidiation and Spore-Carrying Capacity of
Colletotrichum gloeosporioides
on Solid Media
Authors: Slade S. J. , Harris R. F. , Smith C. S. , Andrews J. H.
Published: January 2020

The effect of spore inoculum density, medium concentration, and temperature on slime-spot formation, spore yield, and mycelium production by
Colletotrichum gloeosporioides
on agar media were studied with a simple microplate assay. A steady-state spore yield (spore-carrying capacity) independent of inoculum density was reached only on media that supported good fungal growth and sporulation. The spore-carrying capacity was reached earlier, the denser the inoculum. On standard mycological media a high inoculum density (2.5 × 10
6
spores per ml) resulted in a slimy mass of conidia forming a slime spot, a phenomenon associated with greatly reduced mycelium formation and indicative of microcycle conidiation. In contrast, for a similar inoculum density, enhanced mycelial growth preceded sporulation and overrode slime-spot formation on highly concentrated media; a very low medium concentration resulted in much less mycelium, but spore production was also decreased. Exposure to suboptimal growth temperatures of 36 to 48°C for up to 8 days did not induce microcycle conidiation from inocula that did not form a slime spot at 28°C.
Isolation of a Pseudomonas stutzeri strain that degrades o-xylene
Authors: Baggi G , Barbieri P , Galli E , Tollari S
Published: January 2020

A Pseudomonas stutzeri strain capable of growing on o-xylene was isolated from enrichment cultures. The organism grew on 2,3- and 3,4-dimethylphenol but not on 2-methylbenzyl alcohol, o-tolualdehyde, or o-toluate. P. stutzeri was not able to utilize m-xylene, p-xylene, or 1,2,4-trimethylbenzene, but growth was observed in the presence of the corresponding alcohols and acids. From the Pseudomonas cultures supplied with o-xylene, 2,3-dimethylphenol was isolated and identified. When resting P. stutzeri cells were incubated with 2,3-dimethylphenol, the reaction mixture turned greenish yellow and showed spectral properties identical to those of the 3,4-dimethylcatechol meta ring fission product. Catechol 2,3-oxygenase was induced by growth on o-xylene or on 2,3- or 3,4-dimethylphenol. The suggested hypothesis is that the first metabolic steps of growth on o-xylene involve the direct oxygenation of the aromatic nucleus, followed by meta pathway reactions.
Na
+
-Stimulated Transport of
l
-Methionine in
Brevibacterium linens
CNRZ 918
Authors: Ferchichi Mohamed , Hemme Denis , Nardi Michèle
Published: January 2020

The transport of
l
-methionine by the gram-positive species
Brevibacterium linens
CNRZ 918 is described. The one transport system (

K
m

= 55 μM) found is constitutive for
l
-methionine, stereospecific, and pH and temperature dependent. Entry of
l
-methionine into cells is controlled by the internal methionine pool. Competition studies indicate that
l
-methionine and α-aminobutyric acid share a common carrier for their transport. Neither methionine derivatives substituted on the amino or carboxyl groups nor
d
-methionine was an inhibitor, whereas powerful inhibition was shown by
l
-cysteine,
s
-methyl-
l
-cysteine,
dl
-selenomethionine and
dl
-homocysteine. Sodium plays important and varied roles in
l
-methionine transport by
B. linens
CNRZ 918: (i) it stimulates transport without affecting the

K
m

, (ii) it increases the specific activity (on a biomass basis) of the
l
-methionine transport system when present with methionine in the medium, suggesting a coinduction mechanism.
l
-Methionine transport requires an exogenous energy source, which may be succinic, lactic, acetic, or pyruvic acid but not glucose or sucrose. The fact that
l
-methionine transport was stimulated by potassium arsenate and to a lesser extent by potassium fluoride suggests that high-energy phosphorylated intermediates are not involved in the process. Monensin eliminates stimulation by sodium. Gramicidin and carbonyl cyanide-
m
-chlorophenylhydrazone act in the presence or absence of Na
+
.
N
-Ethylmaleimide,
p
-chloromercurobenzoate, valinomycin, sodium azide, and potassium cyanide have no or only a partial inhibitory effect. These results tend to indicate that the proton motive force reinforced by the Na
+
gradient is involved in the mechanism of energy coupling of
l
-methionine transport by
B. linens
CNRZ 918. Thus, this transport is partially similar to the well-described systems in gram-negative bacteria, except for the role of sodium, which is very effective in
B. linens
, a species adapted to the high sodium levels of its niche.
A more accurate method for measurement of tuberculocidal activity of disinfectants
Authors: Ascenzi J M , Ezzell R J , Wendt T M
Published: January 2020

The current Association of Official Analytical Chemists method for testing tuberculocidal activity of disinfectants has been shown to be inaccurate and to have a high degree of variability. An alternate test method is proposed which is more accurate, more precise, and quantitative. A suspension of Mycobacterium bovis BCG was exposed to a variety of disinfectant chemicals and a kill curve was constructed from quantitative data. Data are presented that show the discrepancy between current claims, determined by the Association of Official Analytical Chemists method, of selected commercially available products and claims generated by the proposed method. The effects of different recovery media were examined. The data indicated that Mycobacteria 7H11 and Middlebrook 7H10 agars were equal in recovery of the different chemically treated cells, with Lowenstein-Jensen agar having approximately the same recovery rate but requiring incubation for up to 3 weeks longer for countability. The kill curves generated for several different chemicals were reproducible, as indicated by the standard deviations of the slopes and intercepts of the linear regression curves.
Adaptation to and biodegradation of xenobiotic compounds by microbial communities from a pristine aquifer
Authors: Aelion C M , Swindoll C M , Pfaender F K
Published: January 2020

The ability of subsurface microbial communities to adapt to the biodegradation of xenobiotic compounds was examined in aquifer solids samples from a pristine aquifer. An increase in the rates of mineralization of radiolabeled substrates with exposure was used as an indication of adaptation. For some compounds, such as chlorobenzene and 1,2,4-trichlorobenzene, slight mineralization was observed but no adaptation was apparent during incubations of over 8 months. Other compounds demonstrated three patterns of response. For m-cresol, m-aminophenol, and aniline intermediate rates of biodegradation and a linear increase in the percent mineralized with time were observed. Phenol, p-chlorophenol, and ethylene dibromide were rapidly metabolized initially, with a nonlinear increase in the percent mineralized with time, indicating that the community was already adapted to the biodegradation of these compounds. Only p-nitrophenol demonstrated a typical adaptation response. In different samples of soil from the same layer in the aquifer, the adaptation period to p-nitrophenol varied from a few days to as long as 6 weeks. In most cases the concentration of xenobiotic added, over the range from a few nanograms to micrograms per gram, made no difference in the response. Most-probable-number counts demonstrated that adaptation is accompanied by an increase in specific degrader numbers. This study has shown that diverse patterns of response occur in the subsurface microbial community.
Purification and Characterization of an Endoglucanase from
Pseudomonas solanacearum
Authors: Schell Mark A.
Published: January 2020

Comparative analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of culture supernatants of a virulent
Pseudomonas solanacearum
strain and of a spontaneous avirulent mutant derived from it was performed. The results show that the levels of two major polypeptides with molecular masses of 43 and 25 kilodaltons (kDa) were markedly reduced in the spent culture medium of the avirulent mutant. In addition, enzyme assays showed that the level of carboxymethyl cellulase (endoglucanase) activity in the culture supernatants of the avirulent mutant was reduced over 25-fold, whereas polygalacturonase activities in both strains were nearly identical. Purification of the endoglucanase from the spent culture medium of the virulent
P. solanacearum
strain by adsorption to phosphocellulose, salt elution, and gel-filtration chromatography yielded a >95% pure preparation of the 43-kDa polypeptide. The kinetic and enzymatic properties of the purified endoglucanase were subsequently analyzed. Antibody prepared against the purified 43-kDa endoglucanase was used to demonstrate its production by several strains of
P. solanacearum
races 1 and 2.
Conservation of a Symbiotic DNA Region in Soybean Root Nodule Bacteria
Authors: Hahn Matthias , Hennecke Hauke
Published: January 2020

Bradyrhizobium japonicum
USDA 3I1b110 contains a DNA region in which symbiotic genes and many repeated sequences are closely linked. Hybridization analysis revealed that this region was highly conserved in some
B. japonicum
strains (USDA 24, USDA 122, USDA 123, ATCC 10324, 61A24) but not in others (USDA 76, 61A76, 61A101). The genomic presence of multiple copies of one of the repeated sequences (RSα) appeared to be specifically characteristic for soybean root nodule bacteria, including the fast-growing
Rhizobium fredii,
which carries most of these RSα copies on the symbiotic plasmid.
New selective and differential medium for Vibrio cholerae and Vibrio vulnificus
Authors: Massad G , Oliver J D
Published: January 2020

Thiosulfate-citrate-bile salts-sucrose agar has been routinely used for the isolation of pathogenic vibrios, although its selectivity for Vibrio cholerae and Vibrio vulnificus is inadequate. Therefore, a new plating medium, cellobiose-polymyxin B-colistin agar, was developed for the isolation of these two species. Cellobiose-polymyxin B-colistin agar demonstrated a significant advantage over other media designed for the isolation or differentiation of vibrios: of both the 136 strains representing 19 Vibrio species and the marine isolates of the genera Pseudomonas, Flavobacterium, and Photobacterium, only V. vulnificus and V. cholerae were able to grow. Furthermore, the fermentation of cellobiose by V. vulnificus allowed for the easy differentiation of these two species. This medium offers significant potential as a selective and differential medium for these two pathogenic vibrios.
In situ survival of Vibrio cholerae and Escherichia coli in tropical coral reefs
Authors: P�rez-Rosas N , Hazen T C
Published: January 2020

Vibrio cholerae and Escherichia coli were inoculated into membrane diffusion chambers and placed around two small coral reef islands in Puerto Rico and monitored for 5 days. Several chambers were also buried in the sands of one of the reefs. Both E. coli and V. cholerae densities declined by 2 orders of magnitude, as measured by direct particle counts with a Coulter Counter (Coulter Electronics, Inc., Hialeah, Fla.). However, the density of neither bacteria changed dramatically when the same samples were analyzed by epifluorescent direct counts. Differences in the two direct count methods were accounted for by changes in cell morphology that occurred in both bacteria after exposure to seawater. Morphological changes occurred more rapidly in E. coli compared with those in V. cholerae. Bacteria in chambers exposed to sediment did not show significant changes in morphology and had only a slight decline in density. Physiological activity declined by more than 40% for both bacteria within 24 h. The decline in activity was less severe in the sediments. Tropical coral reef sands and turtle grass beds were shown to be less stressful environments for V. cholerae and E. coli than would have been predicted from temperature and microcosm studies. V. cholerae can survive the in situ conditions of a tropical coral reef and could become a source of bacterial contamination for fish and shellfish in this environment. The simultaneous monitoring of E. coli levels established that this bacteria can not be used as an indicator of V. cholerae or other fecal-borne pathogens in coral reef environments because of the greater stress these environments put on E. coli. Both bacteria could be of greater public health importance in tropical marine areas than previously imagined.
Intracellular ethanol accumulation in Saccharomyces cerevisiae during fermentation
Authors: D'Amore T , Panchal C J , Stewart G G
Published: January 2020

An intracellular accumulation of ethanol in Saccharomyces cerevisiae was observed during the early stages of fermentation (3 h). However, after 12 h of fermentation, the intracellular and extracellular ethanol concentrations were similar. Increasing the osmotic pressure of the medium caused an increase in the ratio of intracellular to extracellular ethanol concentrations at 3 h of fermentation. As in the previous case, the intracellular and extracellular ethanol concentrations were similar after 12 h of fermentation. Increasing the osmotic pressure also caused a decrease in yeast cell growth and fermentation activities. However, nutrient supplementation of the medium increased the extent of growth and fermentation, resulting in complete glucose utilization, even though intracellular ethanol concentrations were unaltered. These results suggest that nutrient limitation is a major factor responsible for the decreased growth and fermentation activities observed in yeast cells at higher osmotic pressures.
Capacity of aquatic bacteria to act as recipients of plasmid DNA
Authors: Genthner F J , Chatterjee P , Barkay T , Bourquin A W
Published: January 2020

A total of 68 gram-negative freshwater bacterial isolates were screened for their ability to receive and express plasmids from Pseudomonas aeruginosa donors. The plate mating technique identified 26 of the isolates as recipient active for the self-transmissible wide-host-range plasmid R68; 10 were recipient active by R68 mobilization for the wide-host-range plasmid cloning vector R1162. Frequencies of transfer were compared by using three conjugal transfer procedures: broth, plate, and filter mating. For every recipient tested, a solid environment was superior to a liquid environment for transfer. The broth mating technique failed to demonstrate R68 transfer in 63% of the recipient-active isolates. Filter mating, in general, yielded the highest transfer frequencies. The more-rapid plate mating procedure, however, was just as sensitive for testing the capacity of natural isolates to participate in conjugal plasmid transfer.
Synthesis of an Iron-Oxidizing System during Growth of
Thiobacillus ferrooxidans
on Sulfur-Basal Salts Medium
Authors: Sugio Tsuyoshi , Wada Kimihito , Mori Manami , Inagaki Kenji , Tano Tatsuo
Published: January 2020

It was found that the de novo synthesis of not only sulfur:ferric ion oxidoreductase (ferric ion-reducing system) but also iron oxidase was absolutely required when
Thiobacillus ferrooxidans
AP19-3 was grown on sulfur-salts medium. The results strongly suggest that iron oxidase is involved in sulfur oxidation. This bacterium could not grow on sulfur-salts medium under anaerobic conditions with Fe
3+
as a terminal electron acceptor, suggesting that energy conservation by electron transfer between elemental sulfur and Fe
3+
is not available for this bacterium.
Existence of a new type of sulfite oxidase which utilizes ferric ions as an electron acceptor in Thiobacillus ferrooxidans
Authors: Sugio T , Katagiri T , Moriyama M , Zh�n Y L , Inagaki K , Tano T
Published: January 2020

A new type of sulfite oxidase which utilizes ferric ion (Fe3+) as an electron acceptor was found in iron-grown Thiobacillus ferrooxidans. It was localized in the plasma membrane of the bacterium and had a pH optimum at 6.0. Under aerobic conditions, 1 mol of sulfite was oxidized by the enzyme to produce 1 mol of sulfate. Under anaerobic conditions in the presence of Fe3+, sulfite was oxidized by the enzyme as rapidly as it was under aerobic conditions. In the presence of o-phenanthroline or a chelator for Fe2+, the production of Fe2+ was observed during sulfite oxidation by this enzyme under not only anaerobic conditions but also aerobic conditions. No Fe2+ production was observed in the absence of o-phenanthroline, suggesting that the Fe2+ produced was rapidly reoxidized by molecular oxygen. Neither cytochrome c nor ferricyanide, both of which are electron acceptors for other sulfite oxidases, served as an electron acceptor for the sulfite oxidase of T. ferrooxidans. The enzyme was strongly inhibited by chelating agents for Fe3+. The physiological role of sulfite oxidase in sulfur oxidation of T. ferrooxidans is discussed.
A new selective medium for isolating Listeria spp. from heavily contaminated material
Authors: Bannerman E S , Bille J
Published: January 2020

Food-associated outbreaks of human listeriosis have emphasized the importance and necessity of screening food for the presence of Listeria isolates-selective agar medium combining acriflavine (10 mg/liter) with ceftazidime (50 mg/liter) was developed. A total of 1,099 cheese production specimens were cultured, from which 157 Listeria isolates. (14.3%) grew. When compared with modified McBride agar, the acriflavine-ceftazidime agar recovered more Listeria isolates (98 versus 65%, P less than 0.001) more rapidly (57% after 48 h of incubation of the enrichment broth versus 35%, P less than 0.01) and in greater amounts. Acriflavine-ceftazidime selective agar medium proved to be a highly sensitive medium to recover Listeria spp. from heavily contaminated food products.
Photosynthetic Potential and Light-Dependent Oxygen Consumption in a Benthic Cyanobacterial Mat
Authors: J�rgensen Bo Barker , Cohen Yehuda , Revsbech Niels Peter
Published: January 2020

The potential to carry out oxygenic photosynthesis after prolonged burial below the photic zone was studied at 0.1-mm depth intervals in the thick, laminated
Microcoleus chthonoplastes
mats growing in Solar Lake, Sinai. The buried mat community lost about 20% of its photosynthetic potential with depth per annual layer down to 8- to 10-year-old layers at a 14-mm depth. In some of the older layers, below a 30-mm depth, light-dependent oxygen consumption which increased with increasing light intensity was observed. Possible mechanisms for this phenomenon are (i) pseudocyclic electron transport (Mehler reaction), (ii) interactions between respiratory electron transport and photosynthetic electron transport, (iii) photorespiration, and (iv) photooxidation.
Metabolism of 6-nitrochrysene by intestinal microflora
Authors: Manning B W , Campbell W L , Franklin W , Delclos K B , Cerniglia C E
Published: January 2020

Since bacterial nitroreduction may play a critical role in the activation of nitropolycyclic aromatic hydrocarbons, we have used batch and semicontinuous culture systems to determine the ability of intestinal microflora to metabolize the carcinogen 6-nitrochrysene (6-NC). 6-NC was metabolized by the intestinal microflora present in the semicontinuous culture system to 6-aminochrysene (6-AC), N-formyl-6-aminochrysene (6-FAC), and 6-nitrosochrysene (6-NOC). These metabolites were isolated and identified by high-performance liquid chromatography, mass spectrometry, and UV-visible spectrophotometry and compared with authentic compounds. Almost all of the 6-NC was metabolized after 10 days. Nitroreduction of 6-NC to 6-AC was rapid; the 6-AC concentration reached a maximum at 48 h. The ratio of the formation of 6-AC to 6-FAC to 6-NOC at 48 h was 93.4:6.3:0.3. Interestingly, compared with results in the semicontinuous culture system, the only metabolite detected in the batch studies was 6-AC. The rate of nitroreduction differed among human, rat, and mouse intestinal microflora, with human intestinal microflora metabolizing 6-NC to the greatest extent. Since 6-AC has been shown to be carcinogenic in mice and since nitroso derivatives of other nitropolycyclic aromatic hydrocarbons are biologically active, our results suggest that the intestinal microflora has the enzymatic capacity to generate genotoxic compounds and may play an important role in the carcinogenicity of 6-NC.
Effects of Cellulolytic Ruminal Bacteria and of Cell Extracts on Germination of
Euonymus americanus
L. Seeds
Authors: Howard Gary T. , Elliott Larry P.
Published: January 2020

In past attempts, the experimental germination of the seeds of
Euonymus americanus
L. in vitro has had little success. However, treatment of seeds with ruminal fluid containing viable microflora has been successful in stimulating germination. In the presence of the cellulolytic ruminal bacterium,
Clostridium cellobioparum
ATCC 15832, seeds of
E. americanus
were stimulated to germinate. Subsequent studies were designed to determine whether the bacterium synthesized a cellulolytic enzyme responsible for initiating germination. The cell-free endocellulase from
C. cellobioparum
induced germination of the seeds. To support the hypothesis that the endocellulase from
C. cellobioparum
was responsible for triggering germination, a 1,4-β-
d
-glucan glucanohydrolase (EC 3.2.1.4) from
Penicillum funiculosum
was used to treat the seeds. In addition, no germination was obtained from seeds treated with a commercial exocellulase enzyme. Also,
Ruminococcus flavefaciens
FD-1 was found to initiate germination of
E. americanus
seeds. Thus, cellulase activity is indicated in the degradation of the testa of the seed, allowing imbibition and germination.
Nucleotide sequence of the cell wall proteinase gene of Streptococcus cremoris Wg2
Authors: Kok J , Leenhouts K J , Haandrikman A J , Ledeboer A M , Venema G
Published: January 2020

A 6.5-kilobase HindIII fragment that specifies the proteolytic activity of Streptococcus cremoris Wg2 was sequenced entirely. The nucleotide sequence revealed two open reading frames (ORFs), a small ORF1 with 295 codons and a large ORF2 containing 1,772 codons. For both ORFs, there was no stop codon on the HindIII fragment. A partially overlapping PstI fragment was used to locate the translation stop of the large ORF2. The entire ORF2 contained 1,902 coding triplets, followed by an apparently rho-independent terminator sequence. The inferred amino acid sequence would result in a protein of 200 kilodaltons. Both ORFs have their putative transcription and translation signals in a 345-base-pair ClaI fragment. ORF2 is preceded by a promoter region containing a 15-base-pair complementary direct repeat. Both the truncated 33- and the 200-kilodalton proteins have a signal peptide-like N-terminal amino acid sequence. The protein specified by ORF2 contained regions of extensive homology with serine proteases of the subtilisin family. Specifically, amino acid sequences involved in the formation of the active site (viz., Asp-32, His-64, and Ser-221 of the subtilisins) are well conserved in the S. cremoris Wg2 proteinase. The homologous sequences are separated by nonhomologous regions which contain several inserts, most notably a sequence of approximately 200 amino acids between the His and Ser residues of the active site.
Construction of a Stable α-Galactosidase-Producing Baker's Yeast Strain
Authors: Liljestr�m-Suominen Pirkko L. , Joutsjoki Vesa , Korhola Matti
Published: January 2020

Molasses is widely used as a substrate for commercial yeast production. The complete hydrolysis of raffinose, which is present in beet molasses, by
Saccharomyces
strains requires the secretion of α-galactosidase, in addition to the secretion of invertase. Raffinose is not completely utilized by commercially available yeast strains used for baking, which are Mel
−
. In this study we integrated the yeast
MEL1
gene, which codes for α-galactosidase, into a commercial
mel
0
baker's yeast strain. The Mel
+
phenotype of the new strain was stable. The
MEL1
gene was expressed when the new Mel
+
baker's yeast was grown in molasses medium under conditions similar to those used for baker's yeast production at commercial factories. The α-galactosidase produced by this novel baker's yeast strain hydrolyzed all the melibiose that normally accumulates in the growth medium. As a consequence, additional carbohydrate was available to the yeasts for growth. The new strain also produced considerably more α-galactosidase than did a wild-type Mel
+
strain and may prove useful for commercial production of α-galactosidase.
Isolation of Auxotrophic Mutants of
Methylophilus methylotrophus
by Modified-Marker Exchange
Authors: Bohanon Michael J. , Bastien Cathryn A. , Yoshida Roberta , Hanson Richard S.
Published: January 2020

A method for stabilizing a transposon (Tn
5
) has been developed which allows the isolation of stable auxotrophic mutants of
Methylophilus methylotrophus
ASI. Insertion of Tn
5
into a cloned
M. methylotrophus
ASI DNA fragment encoding anthranilate synthase followed by transfer of the vector with the modified
trpE
gene to
M. methylotrophus
ASI resulted in unstable auxotrophs among the recombinants. Deletion of IS
50
R, which encodes transposase production from Tn
5
, stabilized the transposon after mobilization to
M. methylotrophus
ASI. When
trpE
genes with the modified Tn
5
inserts were mobilized into
M. methylotrophus
ASI, stable, kanamycin-resistant tryptophan auxotrophs were obtained by double-crossover homologous recombination with the chromosome.
Nucleotide sequence and expression of the Enterobacter aerogenes alpha-acetolactate decarboxylase gene in brewer's yeast
Authors: Sone H , Fujii T , Kondo K , Shimizu F , Tanaka J , Inoue T
Published: January 2020

The nucleotide sequence of a 1.4-kilobase DNA fragment containing the alpha-acetolactate decarboxylase gene of Enterobacter aerogenes was determined. The sequence contains an entire protein-coding region of 780 nucleotides which encodes an alpha-acetolactate decarboxylase of 260 amino acids. The DNA sequence coding for alpha-acetolactate decarboxylase was placed under the control of the alcohol dehydrogenase I promoter of the yeast Saccharomyces cerevisiae in a plasmid capable of autonomous replication in both S. cerevisiae and Escherichia coli. Brewer's yeast cells transformed by this plasmid showed alpha-acetolactate decarboxylase activity and were used in laboratory-scale fermentation experiments. These experiments revealed that the diacetyl concentration in wort fermented by the plasmid-containing yeast strain was significantly lower than that in wort fermented by the parental strain. These results indicated that the alpha-acetolactate decarboxylase activity produced by brewer's yeast cells degraded alpha-acetolactate and that this degradation caused a decrease in diacetyl production.
Purification and Characterization of a Dipeptidase from
Streptococcus cremoris
Wg2
Authors: van Boven A. , Tan P. S. T. , Konings W. N.
Published: January 2020

A dipeptidase was purified to homogeneity from a crude cell extract of
Streptococcus cremoris
Wg2 by DEAE-Sephacel column chromatography followed by preparative disc gel electrophoresis. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme showed a single protein band with a molecular weight of 49,000. The dipeptidase is capable of hydrolyzing a range of dipeptides, but not peptides with longer chains. The enzyme was shown to be a metallo-Mn
2+
enzyme with a pH optimum of 8 and a temperature optimum of 50�C. The enzyme is strongly inhibited by thiol-reducing reagents but not by sulfhydryl reagents. Kinetic studies indicated that the enzyme has a relatively low affinity for leucyl-leucine and alanyl-alanine (
K

m

, 1.6 and 7.9 mM, respectively) but can hydrolyze these substrates at very high rates (
V
max
, 3,700 and 13,000 μmol/min per mg of protein, respectively).
Cloning and Mapping of a Novel Nodulation Region from
Bradyrhizobium japonicum
by Genetic Complementation of a Deletion Mutant
Authors: Hahn Matthias , Hennecke Hauke
Published: January 2020

The phenotypes of a set of
Bradyrhizobium japonicum
110 mutants with large deletions in the region of symbiotic gene cluster I were tested. The majority of the mutants showed a delayed nodulation on soybean and, by mixed-infection experiments, were found to be strongly reduced in their competitiveness. Phenotypic comparison of mutants with different deletion endpoints allowed a preliminary localization of two genomic regions, called
nod-1
and
nod-2
, which were required for normal nodulation on soybean. Loss of
nod-1
was found to result in a Nod
−
phenotype on cowpea, mung bean, and siratro. A recombinant cosmid was identified which fully restored nodulation ability of a mutant lacking
nod-1
. Using Tn
5
-containing derivatives and subclones of this cosmid for complementation, we delimited the
nod-1
region to a DNA segment of 3.1 to 3.5 kilobase pairs.
Delignification of Wood Chips and Pulps by Using Natural and Synthetic Porphyrins: Models of Fungal Decay
Authors: Paszczyński Andrzej , Crawford Ronald L. , Blanchette Robert A.
Published: January 2020

Kraft pulps, prepared from softwoods, and small chips of birch wood were treated with heme and
tert
-butyl hydroperoxide in aqueous solutions at reflux temperature. Analyses of treated pulps showed decreases in kappa number (a measure of lignin content) from about 36 to less than 2, with concomitant increases in brightness (80% increase in the better samples). Analyses of treated wood chips revealed selective delignification and removal of hemicelluloses. After 48 h of treatment, lignin losses from the wood chips approached 40%, and xylose/mannose (hemicellulose) losses approached 70%, while glucose (cellulose) losses were less than 10%. Examination of delignified chips by transmission electron microscopy showed that the removal of lignin occurred in a manner virtually indistinguishable from that seen after decay by white rot fungi. Various metalloporphyrins, which act as biomimetic catalysts, were compared to horseradish peroxidase and fungal manganese peroxidase in their abilities to oxidize syringaldazine in an organic solvent, dioxane. The metalloporphyrins and peroxidases behaved similarly, and it appeared that the activities of the peroxidases resulted from the extraction of heme into the organic phase, rather than from the activities of the enzymes themselves. We concluded that heme-
tert
-butyl hydroperoxide systems in the absence of a protein carrier mimic the decay of lignified tissues by white rot fungi.

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Characterization of bacteriophage nucleic acids obtained from Clostridium botulinum types C and D
Authors: Fujii N , Oguma K , Yokosawa N , Kimura K , Tsuzuki K
Published: January 2020

Nontoxigenic strains of Clostridium botulinum types C and D are converted to toxigenic strains by infection with specific Tox+ bacteriophages. The nucleic acids were extracted from five converting phages, c-st, c-468, c-203, c-d6f, and d-1873, and one nonconverting phage, c-n71, and treated with nucleases. The nucleic acids isolated were not digested by RNase A, but were digested by DNase I and exonuclease III, indicating that they were double-stranded DNA. On the basis of the restriction endonuclease digestion patterns on 0.8% agarose gel electrophoresis, the length of c-st, c-n71, c-468, and c-d6f phage DNAs was estimated to be about 110 kilobase pairs and that of c-203 and d-1873 was about 150 kilobase pairs. The digestion patterns of c-st, c-468, and c-n71 phage DNAs by PstI and HindIII were very similar. High homology was observed in the dot hybridization test. For other phages and nucleases, a good similarity was not observed. Only a little similarity was observed between c-203 and c-d6f phages. The existence of the structural genes for the toxin in both c-st and c-n71 phages was confirmed by the hybridization test with these phage DNAs and the oligonucleotide probe which represented the DNA sequence predicted for the N-terminal amino acids (2 to 17) of C. botulinum type C toxin. The loss of the converting ability of c-n71 phage may be caused not by the deletion of the tox+ gene but rather by the base mutation in c-st phage DNA.