Chen Yuehua, Deng Yinyue, Wang Jinhong, Cai Jun, Ren Gaixin
Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, PR China.
J Gen Appl Microbiol. 2004 Aug;50(4):183-8. doi: 10.2323/jgam.50.183.
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.
苏云金芽孢杆菌L-7601是一株抗紫外线的野生型菌株，属于苏云金芽孢杆菌松毛虫亚种血清型H4a4b。它从自然界分离得到，在生长指数期产生深棕色色素。苏云金芽孢杆菌L-7601能够在不含L-酪氨酸的普通营养丰富培养基中产生色素。基于化学测试、吸光度和傅里叶变换红外光谱分析，该色素被鉴定为黑色素。苏云金芽孢杆菌L-7601对紫外线具有很强的抗性。照射30分钟后，其存活率比无色素的苏云金芽孢杆菌科默里亚种15A3菌株高17倍。对经紫外线照射后含和不含苏云金芽孢杆菌L-7601产生的色素的苏云金芽孢杆菌制剂对棉铃虫和甜菜夜蛾幼虫的残留杀虫活性进行生物测定的结果表明，该色素是杀虫蛋白的一种优良紫外线保护剂。
