[Bacillus thuringiensis] serovar konkukian str. 97-27 RefSeq Genome. [Bacillus thuringiensis] serovar konkukian str. 97-27

Bacillus thuringiensis. This organism, also known as BT, is famous for the production of an insecticidal toxin. The bacterium was initially discovered as a pathogen of various insects and was first used as an insecticidal agent in the early part of this century. This organism, like many other Bacilli, is found in the soil, where it leads a saprophytic existence, but becomes an opportunistic pathogen of insects when ingested. The specific activity of the toxin towards insects and its lack of toxicity to animals has made this organism a useful biocontrol agent. The delta-endotoxin, which is produced during the sporulation part of the life cycle, causes midgut paralysis and disruption of feeding by the infected insect host. The presence of a parasporal crystal, which is outside the exosporium of the endospore, is indicative of production of the toxin, and serves as a marker for this species. Activation of the toxin typically requires a high pH environment such as the alkaline environments in insect midguts followed by proteolysis. Binding of the toxin to a receptor on intestinal epithelial cells serves to position the toxin to insert itself into the apical membrane where it forms a pore. The flux of water and ions into the cytoplasm results in eventual lysis leading to tissue damage. Various toxin genes specific for a variety of insects have been studied, and many are now being used in genetically modified plants which have been engineered to produce the toxin themselves, eliminating the need to produce sufficient amounts of B. thuringiensis spores. Bacillus thuringiensis subsp. konkukian serotype H34 strain 97-27. This organism was isolated from a case of severe human tissue necrosis which is unusual since human infections by this organism are rare. This isolate is very closely related to B. anthracis based on phylogenetic analysis.

苏云金杆菌（Bacillus thuringiensis，简称BT），该微生物因可合成杀虫毒素而闻名。该细菌最初被发现为多种昆虫的致病菌，并于本世纪早期首次被用作杀虫制剂。与其他芽孢杆菌类似，该菌可在土壤中以腐生方式存活，但当被昆虫摄食后，可成为昆虫的机会致病菌。该毒素对昆虫具有特异性杀虫活性，且对动物无毒性，这使得该菌成为极具应用价值的生防制剂。在其生命周期的芽孢形成阶段产生的δ-内毒素（delta-endotoxin），可导致受感染昆虫宿主的中肠麻痹，并破坏其进食行为。位于芽孢外壁之外的伴孢晶体，是该菌合成毒素的标志性结构，也可作为该物种的鉴定标记。毒素的激活通常需要高pH环境，例如昆虫中肠的碱性环境，随后需经蛋白水解作用完成活化。毒素与肠上皮细胞表面的受体结合后，可精准定位并插入顶膜形成孔道。水分与离子向细胞质内的流动最终会引发细胞裂解，进而导致宿主组织损伤。目前已针对多种昆虫研究出多款特异性毒素基因，其中许多已被应用于转基因植物（genetically modified plants）中，这类植物可自主表达毒素，无需额外制备足量的苏云金杆菌芽孢。苏云金杆菌康库肯亚种（Bacillus thuringiensis subsp. konkukian）血清型H34菌株97-27：该菌株分离自一例罕见的严重人体组织坏死病例，这类由该菌引发的人类感染十分少见。基于系统发育分析（phylogenetic analysis）结果，该分离株与炭疽芽孢杆菌（Bacillus anthracis）亲缘关系极为密切。