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At least 1,333 records · Page 74Linked to original sources
PubMed2003

Sol-gel column technology for capillary isoelectric focusing of microorganisms and biopolymers with UV or fluorometric detection.

The sol-gel surface modification is used for capillary isoelectric focusing of microorganisms and biopolymers. The coating strongly decreases the electroosmotic flow so that it enables the use of the short capillaries down to 100 mm in the separation length. The examples of capillary isoelectric focusing of the low-molecular-mass pI markers and mixed cultures of microbial populations of Escherichia coli, Candida albicans, Staphylococcus epidermidis, and Enteroccocus faecalis with UV detection are shown. It is possible to quantify bacterial cells according to their peak areas; the minimum detectable number of microbial cells was 5 x 10(2)-1 x 10(3). The compatibility of sol-gel capillaries with sensitive fluorometric detection of fluorescent pI markers together with fluorescein labeled proteins is demonstrated.

Bacteria↗
PubMed1976

Determination of relationship between heating value and the thermal resistance of microorganisms in canned meat.

Meat was sterilized with gamma-radiation in an aluminum foil bag and then contaminated with a determined quantity of Bacillus subtilis spores. The bag was then placed in the centre of a can filled with meat. After autoclave sterilization, the whole contents of the aluminum foil bags were examined for the quantity of survived bacteria. This procedure enables the determination of thermal resistance of some bacteria on the condition that appears during typical heating processes. Moreover from all the critical areas all surviving microorganisms can be determined.

Aluminum↗
PubMed1992

[Kinetics of thermal killing of microorganisms in egg yolk].

Egg yolk is relating to its germ content and enzyme activity only restricted storable. Unpasteurized egg yolk get spoiled between a few hours and days. The rapid spoilage can be reduced by a pasteurization and following cold storage. The storage stability of egg yolk can be increased by additives, e.g. salt or saccharose. Kinetic results of the thermal microorganisms destruction in the egg yolk with and without stabilizing additives are presented in this article. It will be shown that the evaluation method from REICHART gives representative results for mixed cultures, too. A further evaluation method by a differential equation will be demonstrated and discussed.

Bacteria↗
PubMedDate not supplied

Effect of olive mill wastewaters on the oxygen consumption by activated sludge microorganisms: an acute toxicity test method.

The test for inhibition of oxygen consumption by activated sludge (ISO 8192-1986 (E)) was evaluated as a tool for assessing, the acute toxicity of olive mill wastewaters (OMW). According to the ISO test, information generated by this method may be helpful in estimating the effect of a test material on bacterial communities in the aquatic environment, especially in aerobic biological treatment systems. However, the lack of standardized bioassay methodology for effluents imposed that the test conditions were modified and adapted. The experiments were conducted in the presence or absence of an easily biodegradable carbon source (glucose) with different contact times (20 min and 24 h). The results obtained showed a remarkable stimulatory effect of this effluent to the activated sludge microorganisms. In fact, the oxygen uptake rate values increase with increasing effluent concentrations and contact times up to 0.98 microl O(2) h(-1) mg(-1) dry weight for a 100% OMW sample, 24 h contact time, with blanks exhibiting an oxygen uptake rate of ca. 1/10 of this value (0.07-0.10). It seems that the application of the ISO test as an acute toxicity test for effluents should be reconsidered, with convenient adaptation for its utilization as a method of estimating the effect on bacterial communities present in aerobic biological treatment systems.

Bacteria, Aerobic↗
PubMed1985

Adaptation games between microorganisms sharing a common substrate niche.

Microorganisms adapt their enzymic outfit to the ambient substrate supply. If several species compete for a limiting substrate, then reciprocal influence on the state of adaptation results, which has been envisaged in the paper as strategic game. The most important types of strategies, which are assessed by the governing selection rule, are called aggressive, neutral and cooperative. A cooperative strategy brings the highest advantage, but triggers the temptation to increase the gain by defection. The neutral strategy, i.e. acting as if the competitor were alone in the medium, is promising only when the selection rule favours product maximization, whereas as aggressive strategy, e.g. maximizing the difference between own and foreign profit, is most effective on growth rate maximization as selection criterion. Gruelling competition reduces the metabolic output and weakens the community as a whole against other systems.

Adaptation, Physiological↗
PubMed1985

Uptake of nourseothricin by the producing microorganism, Streptomyces noursei.

The uptake of 14C-(U)-nourseothricin by stationary phase mycelium of Streptomyces noursei JA 3890 b-NG 13/14 was demonstrated. An energy-dependent transport system appears to be involved in the transport of the antibiotic. Relatively large quantities of the antibiotic were adsorbed to the surface of mycelium. Degradation of nourseothricin by the producing microorganism was not detectable.

Anti-Bacterial Agents↗
PubMed1993

Steroid metabolism with intestinal microorganisms.

As a result of the metabolic activities of numerous anaerobic microorganisms with sterols, bile acids and steroid hormones as substrates in connection with the enterohepatic circulation of these compounds, the intestine may be considered as an "endocrine" active site or organ. The review summarizes transformations of steroids by anaerobic intestinal bacteria, the physiological and supposed pathophysiological meaning thereof. The aim is to recommend further investigation in this field with respect to both the elucidation of the reactions and biological responses.

Animals↗
PubMed1979

[Effect of alternating milieu changes on specific substrate consumption in microorganisms].

In technical microbiology microorganisms often undergo alternating milieu changes. For instance, this is the case in recirculation reactors. The organisms react on these changes with an increase of entropy production and in connection with this with increasing substrate consumption. This increasing substrate consumption contradicts the aim of an optimum yield from a given substrate. Thus, studies of the reaction of microbial growth to alternating milieu changes are of great importance. A simple model of the influence of alternating milieu changes on specific substrate consumption is given. In it the biological conversion of substances is built up by an irreversible consecutive reaction. After preliminary examinations on the analogue computer the reaction of the model to alternating perturbations is simulated on the digital computer. The results of the stimulations are compared with experimental data. The good agreement of experiment and model justifies the use of the simple formulation in the preparation of technical processes.

Candida albicans↗
PubMed1981

Enzymes of glucose isomerization in various microorganisms.

Screening tests for glucose-isomerizing strains of various type, reference and laboratory strains of bacteria including actinomycetes, and yeasts were carried out. The ability to convert glucose to fructose was found to be widely distributed among various microorganisms. It was shown that glucose-isomerizing ability was most prevalent in the genera Aerobacter and Escherichia, but was not found in the bacterial genera belonging to the order Pseudomonadales. Although their activities were not very high (probably due to unsuitable culture conditions) more than 70% of the actinomycetes and 60% of the yeasts grown on xylose possessed glucose-isomerizing activity.

Actinomycetales↗
PubMed1984

Inducers of both cytodifferentiation and anthracycline biosynthesis of Streptomyces griseus and their occurrence in actinomycetes and other microorganisms.

Many taxonomically different strains of actinomycetes as well as several other procaryotic and eucaryotic microorganisms were shown to produce inducers of cytodifferentiation and anthracycline biosynthesis being active towards blocked mutant ZIMET 43682 of Streptomyces griseus. 37 out of 40 strains of the species of S. griseus (92.5%) yielding different kinds of antibiotics were able to induce both the formation of aerial mycelium in the indicator strain ZIMET 43682 concomitant with the biosynthesis of anthracycline antibiotics. 80 (26.3%) out of 304 strains belonging to 94 different Streptomyces species were also producers of inducing agents. Among 77 strains of actinomycetes belonging to 28 different genera being apart from Streptomyces, 12 strains displayed inducing activity (15.6%). The results obtained so far support the conclusion that the formation of inducing agents was neither associated with a particular species of Streptomyces nor its capacity to produce a given antibiotic. The occurrence of inducers has been observed even with members of other genera. Few strains were capable of inducing only one of the differentiation-associated functions. Some strains of Streptomyces species produced at least two different kinds of inducers discernible by their Rf values on TLC.

Anti-Bacterial Agents↗
PubMed2001

Comparison of the methylene blue and toluidine blue photobactericidal efficacy against gram-positive and gram-negative microorganisms.

BACKGROUND AND OBJECTIVE: Studies on the photobactericidal efficacy of methylene blue (MB) and toluidine blue (TB) have shown inconsistent results in the literature. This study evaluated the bactericidal efficacy of MB and TB against different bacteria under light and dark conditions to determine the most effective bactericidal dye. STUDY DESIGN/MATERIALS AND METHODS: Suspensions of Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecalis, Hemophilus influenzae, Escherichia coli, and Pseudomonas aeruginosa in saline were treated in dark and red laser light conditions in the presence of each dye using an argon pumped-dye and a diode laser emitting light at 630 and 664 nm, respectively. The effect of dye concentration, dark incubation time, the fluence and intensity of laser light on the destruction of different bacteria were compared. RESULTS: Both dyes eradicated all examined bacteria under laser light. The complete photodestruction of microorganisms was reached at TB concentrations of 1.5-7-fold less than that of MB. CONCLUSION: TB exhibits a greater bactericidal activity than MB against most bacteria in dark and light conditions. Mostly, these results are consistent with their respective dye partition coefficients.

Coloring Agents↗
PubMed2005

Degradation of simazine by microorganisms isolated from soils of Spanish olive fields.

The capability of the microbial flora isolated from an olive field soil from Andalusia to mineralize simazine has been analyzed. From this soil, a group of bacteria capable of degrading 60 mg simazine litre(-1) in less than a week has been isolated. These microorganisms showed a low capacity for degrading this herbicide to carbon dioxide. When total DNA was isolated from this group of bacteria, we were able to detect by PCR the presence of only the atzC and the trzN genes. Some components of this bacterial population have been identified by sequencing of specific fragments from bacterial 16S rDNA, including Variovorax sp, Pseudoxanthomonas mexicana Thierry et al, Acidovorax sp and Methylopila capsulata Doronina et al. These data suggest that this consortium of bacteria performs an incomplete degradation of the simazine

Bacteria↗
PubMed1993

Fast and sensitive laser-based enzymatic detection of the lactose operon in microorganisms.

This work investigates the ability of laser-based, time-resolved fluorometry to detect the lactose operon genetic marker in microorganisms and to study protein-DNA interactions. In the first study, rapid detection of the Escherichia coli lacZY operon inserted in two strains of Pseudomonas proposed as fungal biological control organisms was achieved. Optimization of incubation time, immobilization apparatus size, and reagent volumes, along with the laser-based instrumentation, yielded an assay capable of detecting 10(4) immobilized lac+ Pseudomonas fluorescens cells within a 30-min incubation time. In the second study, the synthesis of E. coli beta-galactosidase was monitored in "real-time" with observable enzymatic activity beginning 4 to 5 min after induction with isopropylthiogalactoside.

DNA Transposable Elements↗
PubMed2001

Changes in androgenic steroid profile due to urine contamination by microorganisms: a prospective study in the context of doping control.

Urine contamination by microorganisms may affect the interpretation of urinalysis in different areas of clinical diagnosis. This is particularly relevant in doping control. A prospective study was designed to assess the effects of urine contamination by selected pathogens on the endogenous androgenic steroid profile. Pooled urine from a healthy male volunteer with standard steroid profile compared with reference values for the Caucasian population was sterilized by filtration and stored in sterile glass tubes. Aliquots were inoculated with known amounts of 15 different organisms (bacteria, fungi, and moulds) and incubated at 37 degrees C for 2 weeks. Different markers of urine contamination, such as pH, deconjugation of steroids, and metabolic by-products, were determined. Alkalization of urinary pH was not a reliable indicator of urine contamination as several organisms grew in this medium and no alteration of this parameter was found. In uncontaminated urine, less than 10% of steroid glucuronide conjugates were spontaneously hydrolyzed. Higher rates of hydrolysis for sulfate conjugates were found. An unconjugated fraction higher than 10% of the total amount of testosterone was a reliable indicator of urine contamination. However, microbial production of testosterone or epitestosterone was not detected. In contrast, a few organisms were able to synthesize 5alpha-androstanedione, 5beta-androstanedione, and androstenedione using endogenous steroids as substrates.

Androgens↗
PubMed2001

Selective and sensitive detection of pectin lyase activity using a colorimetric test: application to the screening of microorganisms possessing pectin lyase activity.

Several methods have been described for the detection and quantification of polygalacturonase (PG) and pectin lyase (PL) activities. The most frequently used tests are the Nelson method using copper(II) and an arsenomolybdate reagent to detect PG activity, and the colorimetric method using thiobarbituric acid (TBA) to detect PL activity. We observed that none of these methods are suitable to differentiate between these two enzymatic activities. Therefore, we optimized the test conditions of the TBA method. As a result, the detection of the enzymatic beta-elimination (PL activity) became sensitive and selective. A basic pretreatment at 80 degrees C for 5 min of the solution which contains the pectin fragments of the PL activity furnished aldehydes which were condensed with TBA or its derivatives. After acidification of the medium, a pink fluorescent dye was detected spectrophotochemically (lambda = 550 nm). The interference of galacturonic acid or oligomers resulting from PG activity was completely eliminated. The most sensitive reagent was N-(pyridin-2-yl)-thiobarbituric acid. The application of this method with the new reagent was extended to the screening of microorganisms possessing the PL activity. The obtained results confirm that Aspergillus niger strain and a Saccharomyces cerevisiae SCPP strain possess this activity.

Aspergillus niger↗
PubMed1998

Butyrivibrio spp. and other xylanolytic microorganisms from the rumen have cinnamoyl esterase activity.

High concentrations of hydroxycinnamic acids in the hemicellulosic fraction of dry season tropical grasses may influence the rate of microbial degradation of arabinoxylans by ruminant animals. The ability of 22 strains of Butyrivibrio fibrisolvens, other ruminal bacteria (Ruminococcus albus SY3, Ruminococcus flavefaciens RF1,Prevotella ruminicola AR20) and the ruminal phycomycete Neocallimastix patriciarum CX to digest the tropical grass Heteropogon contortus(spear grass) and hydrolyse esterified ferulic and p-coumaric acid was examined. Significant digestion (8-36%) of spear grass occurred with the B. fibrisolvens strains H17c, A38, LP92-1-1, 49,R. albus SY3 and N. patriciarum. Hydrolysis of ester-linked ferulic and p-coumaric acid occurred with all organisms except B. fibrisolvens strains GS113, OB156 and LP1028 and P. ruminicola AR20. The ratio of ferulic to p-coumaric acid hydrolysed by different strains of Butyrivibrio spp. varied markedly from 0.96 for AR 51 to 0.16 for A38. Butyrivibrios which were fibrolytic (H17c and A38) had higher extracellular cinnamoyl esterase activity than bacteria that did not digest spear grass fibre (LP 91-4-1 and AR 20) which had low activities or only produced cell associated enzyme. Cell associated and extracellular esterase activity were induced when Butyrivibrio spp. strains H17c, A38 and E14 and the Ruminococcus spp. were grown on birchwood xylan but induction did not occur to the same extent with N. patriciarum. This is the first reported observation of cinnamoyl esterase activity in the genus Ruminococcus. The fungus N. patriciarum had significantly higher digestibility of spear grass and solubilisation of phenolic acids than the bacteria. The study shows that high levels of extracellular cinnamoyl esterases are characteristic of a selection of fibre-degrading ruminal bacteria and fungi which probably indicates that these enzymes are common amongst xylanolytic ruminal microorganisms.

Journal Article↗