Insecticidal activity and biodegradation of the toxin from Bacillus thuringiensis subsp. kurstaki bound to humic acids from soil
Insecticidal activity and biodegradation of the toxin from Bacillus thuringiensis subsp. kurstaki bound to humic acids from soil
复制标题
DOI：
10.1016/s0038-0717(97)00147-8
复制
发表时间：
1998-04-01
影响因子：
9.7
通讯作者：
Stotzky, G
中科院分区：
文献类型：
--
作者：
Crecchio, C;Stotzky, G
本文研究了对鳞翅目幼虫有毒害作用的苏云金芽孢杆菌库尔斯塔克亚种（Bacillusthuringiensissubsp，kurstaki）活性毒素与两种森林土壤和两种耕作土壤中的腐殖酸的平衡吸附和结合，以及结合毒素的杀虫活性和生物降解。研究了从75%至85%的毒素添加迅速吸附到腐殖酸在平衡，和吸附到一个恒定的量的腐殖酸增加的毒素的浓度，直到达到一个平台。总酸度和腐殖酸的酚基含量的差异似乎是主要负责大量的毒素结合（吸附毒素的45-80%）后，用蒸馏水洗涤的差异。羧基的含量和聚合度（E4/E6）没有出现显着影响的差异结合。结合腐殖酸-毒素复合物对烟草天蛾幼虫有毒性。结合毒素杀死50%幼虫所需的致死浓度（LC_（50））与游离毒素相当，表明毒素与腐殖酸的结合不影响其杀虫活性。结合毒素不支持从土壤中的混合微生物培养物的生长，虽然游离毒素被迅速利用作为碳和能源的增长，表明毒素的结合腐殖酸降低其生物降解性。结果表明，B.引入转基因植物和微生物中的苏云金杆菌由于与腐殖酸结合，可以在土壤中以及在粘土上持续存在、积累和保持杀虫性，如前所述。这种持久性可能对非目标生物造成危害，并加强对耐毒素目标物种的选择。(C)1998爱思唯尔科技有限公司版权所有。
The equilibrium adsorption and binding of the active toxin from Bacillus thuringiensis subsp, kurstaki, toxic to lepidopteran larvae, to humic acids extracted from two forest and two cultivated soils, as well as the insecticidal activity and the biodegradation of the bound toxin. were studied. From 75 to 85% of the toxin added was rapidly adsorbed to the humic acids at equilibrium, and adsorption to a constant amount of humic acids increased with the concentration of the toxin until a plateau was reached. Differences in total acidity and in the content of phenolic groups of the humic acids appeared to be primarily responsible for differences in the amounts of toxin bound (45-80% of the adsorbed toxin) after extensive washing with distilled water. The content of carboxyl groups and the degree of polymerization (E4/E6) did not appear to influence significantly the differential binding. Bound humic acid-toxin complexes were toxic to larvae of the tobacco hornworm (Manduca sexta). The lethal concentration necessary to kill 50% of the larvae (LC50) Of the bound toxin was comparable with that of the free toxin, indicating that the binding of the toxin to humic acids did not affect its insecticidal activity. The bound toxin did not support the growth of a mixed microbial culture from soil, although the free toxin was rapidly utilized as a carbon and energy source for growth, indicating that binding of the toxin to humic acids reduced its biodegradability. The result of these studies indicate that the toxins from B. thuringiensis introduced in transgenic plants and microbes could persist, accumulate, and remain insecticidal in soil as a result of binding to humic acids, as well as on clays, as previously described. This persistence could pose a hazard to non-target organisms and enhance the selection of toxin-resistant target species. (C) 1998 Elsevier Science Ltd. All rights reserved.