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At least 199 records · Page 11Linked to original sources
PubMed1989

[Relation of bacitracin synthesis and manganese content in Bacillus licheniformis: antibiotic production in colonies forming on media with high levels of Mn2+].

Population of B. licheniformis is not homogeneous with respect to its sensitivity to Mn2+. Active bacitracin producing cultures with high and low sensitivity to exogenic manganese are described. In media containing high sublethal concentrations of Mn2+ there were detected two types of bacitracin-producing colonies i.e. light and dark differing likely in the mechanisms of their cell protection from the metal excess. Since bacitracin production did not always correlate with sensitivity to Mn2+ at the level of the colony formation the use of Mn2+ as a selective factor for isolating inactive strains of B. licheniformis is of low efficiency.

Bacillus↗
PubMed1986

[Disordered bacitracin synthesis and sporulation in mutant Bacillus licheniformis with decreased proteolytic activity].

The vegetative cells of B. licheniformis, producing bacitracin, a feed grade peptide antibiotic were exposed to nitroso guanidine and six mutants with lowered activity of serine exoprotease in the culture fluid were isolated. It was found that synthesis of bacitracin and sporulation of the mutants were impaired. The cause of the impairment is not known. The results are discussed from two viewpoints: serine exoprotease is responsible for positive regulation of bacitracin biosynthesis and sporulation at the account of forming an amino acid pool in the medium, simultaneous changing of the three features in the mutants may be due either to a single pleiotropic mutation or to multiple mutations independently induced by nitroso guanidine.

Bacillus↗
PubMedDate not supplied

[Effect of temperature on exoprotease and bacitracin synthesis and sporulation in Bacillus licheniformis 28KA].

By means of physiological experiments the effect of temperatures ranging from 30 degrees C to 55 degrees C on the synthesis of exoprotease and bacitracin, as well as on sporification in Bacillus licheniformis 28KA was studied. The synthesis of exoprotease and sporification were found to be less stable to the temperature variation than the vegetative growth of the microorganism. The temperature, favourable for the maximum yield of then enzyme and spores, is 10 degrees below the temperature which is optimal for the growth of the organism (50 degrees C). The synthesis of bacitracin is substantially sensitive to the temperature variation. The maximum synthesis of the antibiotic was observed at 50 degrees C. High concentrations of glucose inhibit the synthesis of the enzyme and bacitracin, as well as sporification in Bacillus licheniformis 28KA.

Bacillus↗
PubMed1980

Bacitracin treatment of antibiotic-associated colitis and diarrhea caused by Clostridium difficile toxin.

Four cases of antibiotic-associated colitis and diarrhea caused by Clostridium difficile were successfully treated with oral bacitracin, 25,000 units four times daily for 7-10 days. Diarrhea resolved in all of the cases, in 2 days, with disappearance of Clostridium difficile toxin in the stools in 3 out of 4 patients so measured. Two of the patients treated had relapses after vancomycin, while the other 2 were experiencing the first episodes. One patient relapsed after bacitracin treatment, but was treated successfully with vancomycin. Our preliminary experience indicates that bacitracin, being less expensive and more readily available world-wide than vancomycin, could be used as an alternative drug for toxin-induced colitis or diarrhea.

Adult↗
PubMed1993

[Differentiation of serologic group A streptococci from group C and G using disks with various bacitracin levels].

It was revealed that a diameter of the inhibition zone of 10 mm or more surrounding a disk with 0.04 U bacitracin differentiates reliably strains of the serological group A form strains of group C and G with the exception of 7.3% strains of group C and G with a high susceptibility for bacitracin. The disks with a higher bacitracin content gives less reliable results.

Bacitracin↗
PubMed2001

Analysis of bacitracin by micellar electrokinetic capillary chromatography with mixed micelle in acidic solution.

A method used for quantitative analysis of bacitracin with micellar electrokinetic capillary chromatography (MEKC) is described. As capillary zone electrophoresis gave poor separation selectivity, MEKC was preferable. It was found that a zwitterionic surfactant, 3-(N,N-dimethylhexadecylammonium)-propanesulfonate (PAPS) gave the best selectivity among the several surfactants studied. As the analytes tend to adsorb onto the capillary wall due to their positive charge, an acidic solution composed of Tris-phosphate buffer at pH 2.5 was necessary to diminish such adsorption. The peak tailing caused by relatively strong ion pair interaction between the analyte and PAPS micelle could be reduced by adding nonionic surfactant Brij 35 to the PAPS solution. This phenomenon is possibly explained by a mixed micelle mechanism. In order to obtain the optimal conditions and to test the method robustness, a central composite experimental design was performed. The optimal conditions are as follows: 44 cm length of fused-silica capillary with 50 microm inner diameter, 90 mM Tris-phosphate buffer (pH 2.5) containing 17 mM PAPS and 0.3% w/v-Brij 35, 18 kV applied voltage, UV detection at 192 nm and 25 degrees C column temperature. Under the optimal conditions, more than 50 peaks could be obtained in 30 min. The method had a linearity range from 1 to 0.05 mg/mL (concentration of bacitracin A). The limit of quantitation (LOQ) and limit of detection (LOD) were 0.005 and 0.0012 mg/mL, respectively.

Bacitracin↗
PubMed1991

Conformational analysis of bacitracin A, a naturally occurring lariat.

The proton nmr spectra of bacitracin A in H2O and DMSO-d6 have been assigned and the conformational behavior of the peptide in the two solvents has been compared. Although bacitracin A shows a conformational equilibrium between at least two conformations differing in the relative position of the cyclic and linear domains of the molecule, the spectra in water can be interpreted in terms of a preferred conformation in which the linear part is folded over the cyclic moiety and a turn is present around Ile(8)-DPhe(9).

Amino Acid Sequence↗
PubMed2003

Affinity capillary electrophoresis study of the linkage existing between proton and zinc ion binding to bacitracin A1.

Measurements by capillary electrophoresis (CE) of bacitracin A(1) effective mobility at different pH values permitted to estimate the five acidic dissociation constants and the Stokes radii at different protonation stages of the macrocyclic dodecapeptide. The pK(a) values were 3.6 and 4.4 for the two carboxylic groups of the lateral chains of D-Asp-11 and D-Glu-4, respectively, 6.4 for the aza-atom of the imidazole ring of His-10, 7.6 for the amino group of N-terminal Ile-1 and 9.7 for the delta-amino group of D-Orn-7, very close to the values obtained by other researchers by titration experiments. In agreement with a rigid macrocyclic structure the Stokes radii of different protonated forms ranged only between 14.3 and 14.8 A. Best fitting procedures performed on experimental mobility measured at two different pH values (5.50 and 6.72) in the presence of increasing Zn(+2) concentration allowed confirming the model that assumes the binding of Zn(+2) to P(0) peptide form with a 1.5 x 10(3) M(-1) intrinsic association constant. Following to Zn(+2) binding, the pK(a) of the amino group of N-terminal Ile-1 is shifted from 7.6 to 5.9 and the Stokes radius is reduced of about 3 A. The mean charge of the bacitracin A(1)-Zn(+2) complex resulted +1.67 and +1.12 at pH 5.50 and 6.72, respectively. These results suggest that the amino group of N-terminal Ile-1 is not essential for Zn(+2) binding.

Bacitracin↗
PubMed1975

New color reaction for determination of bacitracin in ophthalmic ointments.

A colorimetric method was developed for the rapid analysis of bacitracin in ophthalmic ointments. The method involves the oxidation of alpha-aminocarboxylic acid with sodium hypobromite in an alkaline medium and condensation of the resulting aldehyde with phloroglucinol in concentrated hydrochloric acid to yield a pink color which gives an absorbance maximum at 505 nm. The relationship between absorbance and the quantity of bacitracin reacted obeyed Beer's law over the 15-100-mug/ml concentration range studied, and the produced color was stable for several hours. Furthermore, the method, which can be applied directly to the aqueous dissolution sample, gave results comparable to the official microbiological analytical procedure. The standard deviation is equal to plus or minus 1.81%.

Bacitracin↗
PubMed1993

Purification of nonantibiotic insulinase inhibitors from bacitracin.

Bacitracin is commonly used in metabolic studies as an insulinase inhibitor. The many isoforms of the commercial preparation were fractionated by charge and size in order to find the most active rat-muscle insulinase inhibitors. CM-Sepharose chromatography revealed that most of the inhibitory activity was contained in a fraction (CM-Inh) that amounted to less than 5% of the mixture. The CM-Inh fraction could be further separated by size on Bio-Gel P4 columns. Six subgroups, each with characteristic specific activity, were isolated. The most potent inhibitor fractions have no antibiotic activity and have molecular weights about twice that of bacitracin A. The peaks isolated by means of Bio-Gel P4 chromatography can be further fractionated by reversed phase HPLC on a C8 column, and by electrophoresis on nonreducing acrylamide gels.

Amino Acids↗
PubMed1985

Bacitracin increases size of parasporal crystals and spores in Bacillus thuringiensis.

The effect of bacitracin on Bacillus thuringiensis is described. When added after the end of the exponential phase, it produces a marked increase in the size of spores and parasporal crystals. The cultures to which the antibiotic was added are able to produce more crystal proteins than non-treated cultures. The protein composition of crystals from bacitracin-treated cultures is the same as that of crystals purified from control cultures.

Bacillus thuringiensis↗
PubMed1981

Effect of enkephalins in the presence of the antibiotic bacitracin in the longitudinal muscle strip preparation from guinea-pig ileum.

The antibiotic bacitracin (5 x 10(-5) -4 x 10(-4) M) increase the inhibition of the contractile response caused by both enkephalin release and direct application of Met-enkephalin 5 x 10(-7) M in the longitudinal muscle strip preparation from guinea-pig ileum. This effect is attributed to an inhibition of enkephalin degrading peptidases by bacitracin.

Animals↗
PubMed1979

Amino acid control mechanism for bacitracin formation by Bacillus licheniformis.

Several amino acids affected the amount of bacitracin produced by Bacillus licheniformis ATCC 10716 and the high-yielding mutant B. licheniformis AL. The possibility of an amino acid control mechanism for bacitracin biosynthesis is discussed. The two strains showed a different response to the addition of some amino acids. This indicate that they may have differences in their amino acid control mechanism.

Amino Acids↗
PubMed1990

Bacitracin U.S.P. contains a factor that stimulates receptors for 5-hydroxytryptamine on rabbit aortic strips.

Bacitracin (BAC) U.S.P., obtained in the form of sterile powder, elicits dose-dependent and non-tachyphylactic contractions of the rabbit isolated aorta and of other rabbit vessels. The use of several pharmacologic antagonists suggests that BAC is a 5-hydroxytryptamine mimetic in aortic strips, since the antibiotic is competitively antagonized by methysergide and ketanserin with pA2 values compatible with an agonist action on the 5-HT2 receptors found in the aortic preparation. It remains to be determined whether bacitracin A, the chief constituent of BAC U.S.P., is the 5-HT agonist.

Animals↗
PubMed1985

The binding of somatostatin to rat synaptosomal membranes: effects of detergent solubilisation and of bacitracin.

Specific high and low affinity binding sites for somatostatin have been demonstrated in rat brain synaptosomal membranes using 125I [Tyr"] somatostatin tracer. When incubations were carried out in the presence of low concentrations of bacitracin (0.01% w/v), a 66% increase in association constant of the high affinity binding site to Ka = 1.71 X 10(10) M-1 and a 70% increase in the Ka of the low affinity site to 0.034 X 10(10) M-1 were observed; a similar (50%) increase in the binding capacity of the low affinity site but no increase in the binding capacity of the high affinity site was seen. These results may indicate a direct effect of bacitracin on the membrane that is distinct from its effect as an inhibitor of tracer degradation. The somatostatin-binding capacity of the membranes was solubilised by treatment with Triton X-100 and the apparent molecular weight of the receptor-ligand-detergent micelle complex was estimated by gel filtration to be approximately 250,000.

Animals↗
PubMed1990

Simultaneous contact allergy to neomycin, bacitracin, and polymyxin.

Simultaneous contact allergy to neomycin, bacitracin, and polymyxin was seen in two patients. Although neomycin sensitivity is common, bacitracin and polymyxin are less frequently considered as causes of allergic contact dermatitis. Allergy to all three items simultaneously has not been previously reported.

Adult↗
PubMedDate not supplied

Lack of inhibitory effect of aprotinin and bacitracin on the spinal release of Met-enkephalin induced by intraventricular beta-endorphin.

We have previously reported that administration of beta-endorphin intraventricularly in the rat increases the release of immunoreactive Met-enkephalin from the spinal cord. To further eliminate the possibility that the increase in Met-enkephalin might arise from the degradation of beta-endorphin injected, the effect of peptidase inhibitors, aprotinin and bacitracin, on the spinal fluid content of Met-enkephalin released by intraventricular beta-endorphin was studied using an intrathecal perfusion technique in urethane anesthetized rats. Inhibition of peptidases by intraventricular aprotinin and bacitracin did not decrease nor enhance the increased content of Met-enkephalin in the spinal perfusate produced by intraventricular beta-endorphin. The result indicates that the Met-enkephalin arises from neuronal release in the spinal cord rather than from degradation of the beta-endorphin injected intraventricularly.

Animals↗
PubMed1989

Flow microcalorimetric assay of antibiotics--I. Polymyxin B sulphate and its combinations with neomycin sulphate and zinc bacitracin on interaction with Bordetella bronchiseptica (NCTC 8344).

A flow microcalorimetric assay for polymyxin B sulphate has been developed which has a better reproducibility (relative standard deviation less than 3%) and sensitivity (0.35 micrograms ml-1) than conventional microbiological assays, and requires an assay time of ca. 4.5 h. The combinations with zinc bacitracin, with neomycin sulphate, and with both zinc bacitracin and neomycin sulphate indicate antagonism between these antibiotics upon interaction with Bordetella bronchiseptica (NCTC 8344). The combinations of all three antibiotics assayed were: (1) equimolar proportions; and (2) those proportions present in the commercial preparation TrisepR (ICI, Macclesfield, UK).

Bacitracin↗