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At least 19 recordsLinked to original sources
PubMed2001

Optimization of tylosin feeding rate profile in production of acetyl-isovaleryl tylosin (AIV) from tylosin by Streptomyces thermotolerans YN554.

An optimal feed rate profile of a substrate (tylosin) for a novel antibiotic, acetyl-isovaleryl tylosin (AIV) production process was investigated. In the first step of optimization, a kinetic model for production of AIV from tylosin by Streptomyces thermotolerans was established properly using the least square method, followed by the confirmation that the proposed model could be used to predict the production process of AIV from tylosin. An objective function, state equations and an inequality constraint with respect to the tylosin feeding rate profile were applied to maximize the amount of AIV produced from tylosin in a fed-batch culture. The optimized tylosin feeding rate profile was determined using a direct iterative search algorithm based on the modified complex method. The simulation of AIV production at the optimal tylosin feeding profile indicates that the final amount of AIV is expected to be about 30% higher than that at the conventional constant tylosin feeding rate, which was also confirmed experimentally using a 30-l jar fermentor.

Journal Article↗
PubMedDate not supplied

Efficacy of danofloxacin and tylosin in the control of mycoplasmosis in chicks infected with tylosin-susceptible or tylosin-resistant field isolates of Mycoplasma gallisepticum.

The efficacy of danofloxacin was compared with that of tylosin in the control of induced mycoplasmosis. In three experiments, disease was induced in broiler chicks by intrapulmonary injection of field isolates of Mycoplasma gallisepticum (MG) originating from Brazil, a different isolate being used for each experiment. Starting the day after inoculation, groups of chicks were medicated for 3 days via the drinking water with danofloxacin (50 ppm) or tylosin (500 ppm) or were left as unmedicated controls. Chicks were observed for 21 days. A severe mycoplasmosis was induced in unmedicated birds, characterized by mortality, depression, and respiratory signs. Danofloxacin was highly efficacious in controlling this infection in all three experiments, whereas tylosin was efficacious in only one. This difference could be related directly to the reduced in vitro susceptibility to tylosin displayed by the two isolates of MG. In the two experiments where isolates were tylosin-resistant, danofloxacin was significantly (P < or = 0.05) superior to tylosin in reducing mortality, maintaining weight gain, and reducing the prevalence of air-sac lesions, isolation of MG, and seroconversion.

Air Sacs↗
PubMed1999

Bacterial flora of liver abscesses in feedlot cattle fed tylosin or no tylosin.

Bacterial flora of liver abscesses from cattle fed tylosin or no tylosin and susceptibilities of the predominant bacterial isolates to tylosin and other antimicrobial compounds were determined. Abscessed livers were collected at slaughter from cattle originating from feedlots that had fed tylosin (n = 36) or no tylosin (n = 41) for at least 2 yr, and segments of livers with one or two intact abscesses were transported to the laboratory. Abscesses were cultured for anaerobic and facultative bacteria. Fusobacterium necrophorum, either as single culture or mixed with other bacteria, was isolated from all abscesses. The incidence of subsp. necrophorum, as part of the mixed infection, was lower (P < .05) in the tylosin group than in the no-tylosin group (33 vs 61%). However, the incidence of Actinomyces pyogenes was higher (P < .01) in the tylosin group than in the no-tylosin group (53 vs 10%). Totals of 119 F. necrophorum and 21 A. pyogenes isolates were used for determinations of susceptibilities to bacitracin, oxytetracycline, chlortetracycline, lasalocid, monensin, tylosin, tilmicosin, and virginiamycin. The minimum inhibitory concentrations (MIC) of antibiotics were determined with a broth microdilution method. The mean MIC of tylosin for F. necrophorum and A. pyogenes were not different between isolates from tylosin and no-tylosin groups. We concluded that continuous feeding of tylosin did not induce resistance in F. necrophorum or A. pyogenes. Also, the higher incidence of mixed infection of F. necrophorum and A. pyogenes in liver abscesses of tylosin-fed cattle suggests a potential synergistic interaction between the two organisms in causing liver abscesses.

Actinomyces↗
PubMed1997

[Tylosin-specific proliferation in vitro of the peripheral blood mononuclear cells in occupational tylosin allergy].

Tylosin-specific lymphocyte proliferation in vitro and its restriction of HLA class II antigens have been investigated in 21 allergic workers exposed to tylosin. Nine workers from tylosin industry without allergic symptoms and five nonexposed nonallergic subjects served as controls. The results showed a significantly higher lymphocyte proliferative response to tylosin in allergic workers compared to control groups. Lymphocyte proliferation was observed in five workers with allergic complaints but negative skin tests. The tylosin concentration leading to maximal proliferative response varied from 10 to 1000 micrograms/ml among individuals. Six from seven workers with maximal response to the lowest concentration of tylosin carried HLA-DQ2 antigen. Lymphocyte from most control subjects did not respond in vitro to tylosin. Weak proliferative response to tylosin was observed in two workers without clinical symptoms of allergy. No association was found between lymphocyte reactivity to PHA and tylosin in the three studied groups. In conclusion, tylosin leads to a specific activation of T lymphocytes in occupationally sensitized workers. Possibly, the T cell recognition of the hapten/protein complex is restricted by HLA-DQ2 antigen in tylosin occupational allergy. Lymphocyte stimulation test can be used for the diagnosis of tylosin occupational allergy, as well as for the detection of latently sensitized workers.

Adult↗
PubMed1986

Cloning and expression of a tylosin resistance gene from a tylosin-producing strain of Streptomyces fradiae.

A gene conferring high-level resistance to tylosin in Streptomyces lividans and Streptomyces griseofuscus was cloned from a tylosin-producing strain of Streptomyces fradiae. The tylosin-resistance (Tylr) gene (tlrA) was isolated on five overlapping DNA fragments which contained a common 2.6 Kb KpnI fragment. The KpnI fragment contained all of the information required for the expression of the Tylr phenotype in S. lividans and S. griseofuscus. Southern hybridization indicated that the sequence conferring tylosin resistance was present on the same 5 kb SalI fragment in genomic DNA from S. fradiae and several tylosin-sensitive (Tyls) mutants. The cloned tlrA gene failed to restore tylosin resistance in two Tyls mutants derived by protoplast formation and regeneration, and it restored partial resistance in a Tyls mutant obtained by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) mutagenesis. The tlrA gene conferred resistance to tylosin, carbomycin, niddamycin, vernamycin-B and, to some degree, lincomycin in S. griseofuscus, but it had no effect on sensitivity to streptomycin or spectinomycin, suggesting that the cloned gene is an MLS (macrolide, lincosamide, streptogramin-B)-resistance gene. Twenty-eight kb of S. fradiae DNA surrounding the tlrA gene was isolated from a genomic library in bacteriophage lambda Charon 4. Introduction of these DNA sequence into S. fradiae mutants blocked at different steps in tylosin biosynthesis failed to restore tylosin production, suggesting that the cloned Tylr gene is not closely linked to tylosin biosynthetic genes.

Cloning, Molecular↗
PubMed1983

Biosynthesis of the macrolide antibiotic tylosin. A preferred pathway from tylactone to tylosin.

The efficiencies of bioconversion of twenty-three potential intermediates in the biosynthesis of tylosin were determined with a mutant strain blocked only in tylactone biosynthesis. The results indicated that tylactone, the first intermediate excreted by Streptomyces fradiae, is converted to tylosin by a preferred sequence of reactions which include: (1) addition of mycaminose to the C-5 hydroxyl position of the lactone; (2) hydroxylation of the C-20 methyl group to a hydroxymethyl group; (3) dehydrogenation of the C-20 hydroxymethyl group to a formyl group; (4) hydroxylation of the C-23 methyl group to a hydroxymethyl; (5) addition of 6-deoxy-D-allose to the C-23 hydroxymethyl group; (6) addition of mycarose to the 4'-hydroxyl group of mycaminose; (7) addition of a methyl group to the 2"'-hydroxyl position of demethylmacrocin, and (8) addition of a methyl group to the 3"'-hydroxyl position of macrocin to produce tylosin. The intermediates which lacked both neutral sugars (mycarose and 6-deoxy-D-allose) were biologically unstable, and substantial quantities of these compounds were degraded during standard bioconversion experiments. However, the amount of one such intermediate (O-mycaminosyltylonolide) degraded was substantially reduced when low concentrations of the compound were used for bioconversion, and under these conditions, much higher efficiencies of bioconversion to tylosin were obtained. We have shown that a mutant blocked in hydroxylation of the C-20 methyl group is also blocked in the further dehydrogenation of the C-20 hydroxymethyl group to a formyl group, and have confirmed in in vitro studies that the 2"'-O-methylation of demethylmacrocin must proceed the 3"'-O-methylation of macrocin to produce tylosin.

Leucomycins↗
PubMed2004

Tylosin detection in animal feed by liquid chromatography-tandem mass spectrometry with enzymatic hydrolysis of the tylosin urea adduct.

When the use of tylosin as a feed additive was forbidden by Council Regulation 2821/98, the necessity of a chemical confirmation method for the monitoring of the ban was created. Recently a method was developed for the detection of tylosin in animal feed by means of LC-MS/MS. During the validation high deviating values for the decision limit, detection capability, and repeatability for tylosin in cattle feed were observed, and the presence of urea and the formation of a tylosin urea adduct (TUA) were suggested as possible explanations. In this study two hydrolysis approaches for the TUA adduct were compared, namely, a chemical hydrolysis and an enzymatic hydrolysis with urease. The latter yielded a more complete hydrolysis of urea and was used for further validation. The recovery increased by approximately 15-25% depending on the amount of urea present in the feed (0.5-2%). The decision limit and detection capability were hardly influenced by the enzymatic hydrolysis.

Animal Feed↗
PubMed1981

Metabolic regulation in tylosin-producing Streptomyces fradiae: phosphate control of tylosin biosynthesis.

The effects of increased concentration of inorganic phosphate on the biosynthesis of tylosin, the level of the intracellular adenylates, the energy charge, and the activities of enzymes involved in the synthesis of tylonolide precursors were studied in Streptomyces fradiae NRRL 2702. No metabolic response was observed when elevated levels of inorganic phosphate were added in idiophase. Increased initial levels of inorganic phosphate suppressed tylosin production and markedly increased the levels of the adenylates, although the adenylate energy charge was unchanged. Higher growth and glucose uptake rates were also observed. The activities of methylmalonyl-coenzyme A carboxyltransferase (EC 2.1.3.1) and propionyl-coenzyme A carboxylase (EC 6.4.1.3) were suppressed by the increased concentration of inorganic phosphate. The results indicated that the rate of tylosin synthesis was inversely related to the absolute level of the adenylates rather than to the energy charge.

Adenosine Diphosphate↗
PubMed2001

Biodegradability of metronidazole, olaquindox, and tylosin and formation of tylosin degradation products in aerobic soil--manure slurries.

The use of veterinary drugs (primarily antibiotics) in animal husbandry harbors the risk that these compounds end up in the farmland when manure is used as fertilizer. The biodegradability of three compounds, olaquindox (OLA), metronidazole (MET), and tylosin (TYL), was simulated in soil--manure slurries with 50 g of soil per liter. Supplemental batch sorption tests revealed that insignificant amounts of OLA and MET were located in the soil phase, whereas only 0.1 to 10% of the added amounts of TYL remained in the liquid phase. This may reduce the bioavailability and thus biodegradation rates of TYL. Unidentified metabolites of OLA and TYL and four known TYL metabolites were detected using HPLC. However, none of these substances were seen to persist in the biodegradation experiments, indicating that OLA and TYL most likely were mineralized in the experiments. Neither the use of sandy or clayey soil nor the use of 0, 1, or 10% (V/V) of manure added to these soils had a significant effect on the degradation rates. Degradation half-lives for the primary degradation were 3.3--8.1 days for TYL, 5.8--8.8 days for OLA, and 13.1--26.9 days for MET. Based on comparisons of results obtained with the benchmark chemical aniline and degradation half-lives of this compound in nature, it was assessed that results obtained with the current test method slightly overestimate real-world biodegradation rates.

Aerobiosis↗
PubMed1989

[Molecular cloning of tylosin-producing Streptomyces fradiae B-45 genes determining increased inducible resistance to tylosin in Streptomyces lividans TK64].

DNA of S. fradiae B-45 partially cleaved by Sau3A restrictase was cloned in S. lividans TK64 in the plasmid vector pIJ702. Three recombinant plasmids pVG251, pVG262, and pVG253 with tlr1, tlr2 and tlr3 genes were isolated from the transformed clones of S. lividans TK64 with higher inducible resistance to tylosin as compared to the plasmid-free strain. DNA-DNA blot hybridization was performed between the total DNA cleaved by several restrictases from S. fradiae B-45 and some other strains and the DNA probes containing the tlr genes. It was shown that tlr1 and tlr3 genes were unique in S. fradiae B-45. Sequences homologous to tlr2 gene were present both in DNA of S. fradiae B-45 in 7 copies and in strains of S. antibiotics and S. hygroscopicus producing respectively oleandomycin and turimycin.

Cloning, Molecular↗