title: Characterization of melanin produced by a wild-type strain of Bacillus thuringiensis.
abstract: Bt L-7601 is a UV resistant wild-type strain, which belongs to Bacillus thuringiensis subsp. dendrolimus serotype H4a4b. It was isolated from nature, and produced a dark brown pigment during the exponential phase of growth. Bt L-7601 had the ability to produce pigment in a general nutrition-abundant medium, which had no L-tyrosine. The pigment was identified as melanin based on chemical testing, its light absorbance, and FT-IR analysis. Bt L-7601 has a strong resistance to UV light. After 30 min irradiation its survival rate was 17 times higher than that of the strain B. thuringiensis subsp. colmeri 15A3, which had no pigment. Results of the bioassays of residual insecticidal activity of Bt formulation with and without pigment produced by Bt L-7601 against larvae of Helicoverpa armigera and Spodoptera exigua after exposure to UV irradiation showed that the pigment is an excellent UV protective agent for the insecticidal proteins.
authors.affiliation: Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, PR China. yhchen@nankai.edu.cn
authors.forename: Yuehua
authors.initials: Y
authors.lastname: Chen
authors.forename: Yinyue
authors.initials: Y
authors.lastname: Deng
authors.forename: Jinhong
authors.initials: J
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Cai
authors.forename: Gaixin
authors.initials: G
authors.lastname: Ren
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000494:pharmacology; D001427:Bacterial Toxins / Q000494:pharmacology; D004731:Endotoxins / Q000494:pharmacology; D006460:Hemolysin Proteins; D007814:Larva / Q000254:growth & development; D008543:Melanins / Q000096:biosynthesis* / Q000737:chemistry / Q000494:pharmacology*; D009036:Moths / Q000254:growth & development; D010572:Pest Control, Biological; D018411:Spodoptera / Q000254:growth & development; D014466:Ultraviolet Rays
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D008543:Melanins; C030956:insecticidal crystal protein, Bacillus Thuringiensis