RESUMEN
A process for production, isolation, and purification of melanin produced by the fermentation of Streptomyces lividans 66 harboring a recombinant plasmid pIJ702-bearing tyrosinase gene has been developed. The efficacy of melanin in the protection of mosquito larvacidal activity of Bacillus thuringiensis var. israelensis against uv light has been studied. Results obtained by the live cell counts and the bioassay of residual mosquitocidal activity of B. thuringiensis var. israelensis after exposure to uv radiation showed that melanin is an excellent photoprotective agent.
Asunto(s)
Aedes , Bacillus thuringiensis/efectos de la radiación , Toxinas Bacterianas , Melaninas/farmacología , Control de Mosquitos/métodos , Control Biológico de Vectores/métodos , Streptomyces/genética , Rayos Ultravioleta , Aedes/crecimiento & desarrollo , Animales , Bacillus thuringiensis/efectos de los fármacos , Bacillus thuringiensis/metabolismo , Toxinas de Bacillus thuringiensis , Proteínas Bacterianas/biosíntesis , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/toxicidad , Bioensayo , Endotoxinas/biosíntesis , Endotoxinas/toxicidad , Vectores Genéticos , Proteínas Hemolisinas , Larva , Melaninas/genética , Melaninas/aislamiento & purificación , Melaninas/efectos de la radiación , Monofenol Monooxigenasa/genética , Monofenol Monooxigenasa/metabolismo , Fotoquímica , Tolerancia a Radiación/efectos de los fármacos , Esporas BacterianasRESUMEN
A 19-kb plasmid, pNI100, was isolated from Nocardia italica CCRC12359; its replicon was cloned and characterized as having a single open reading frame (ORF) of 1188 bp specifying 396 amino acids (aa). Analyses of the deduced aa sequence of the Rep protein indicated that characteristics of three consensus sequences and a P-loop-like motif in the Rep protein of plasmid pSG5, a conjugative plasmid involving a rolling-circle replication mechanism, were conserved in those of plasmid pNI100. Phenotypically, a pock structure was produced in the regenerated mycelium by introducing pNI100 DNA into the Streptomyces lividans protoplast. This result strongly suggests that pNI100 is a conjugative plasmid and probably replicates by a rolling-circle replication mechanism. By using the replicon of pNI100, a bifunctional plasmid pNI105 that could replicate in both Escherichia coli and S. lividans was constructed and found to be a useful cloning shuttle vector.