College of Life Sciences, Sun Yat-sen University, 510275 Guangzhou, China.
J Invertebr Pathol. 2010 Jun;104(2):75-82. doi: 10.1016/j.jip.2010.02.002. Epub 2010 Feb 11.
Serratia marcescens GEI strain was isolated from the gut of the workers of Chinese honey bee Apis cerana and evaluated in the laboratory for the control of Varroa destructor, a parasite of western honey bee A. mellifera. The supernatant and the collected proteins by ammonium sulfate from the bacterial cultures showed a strong miticidal effect on the female mites, with 100% mite mortality in 5days. Heat (100 degrees C for 10min) and proteinase K treatment of the collected proteins destroyed the miticidal activity. The improved miticial activity of this bacterial strain on chitin medium indicated the involvement of chitinases. The expressed chitinases ChiA, ChiB and ChiC1 from S. marcescens GEI by recombinant Escherichia coli showed pathogenicity against the mites in the laboratory. These chitinases were active in a broad pH range (5-9) and the optimum temperatures were between 60 and 75 degrees C. Synergistic effects of ChiA and ChiB on the miticidal activity against V. destructor were observed. The workers of both honey bee species were not sensitive to the spraying and feeding chitinases. These results provided alternative control strategies for Varroa mites, by formulating chitinase agents and by constructing transgenetic honey bees.
粘质沙雷氏菌 GEI 菌株从中华蜜蜂 Apis cerana 的工蜂肠道中分离出来，并在实验室中评估其对西方蜜蜂 A. mellifera 的寄生虫瓦螨的控制效果。细菌培养物的上清液和硫酸铵收集的蛋白质对雌性螨虫表现出强烈的杀螨作用，在 5 天内螨虫死亡率达到 100%。收集蛋白质的热（100°C 10 分钟）和蛋白酶 K 处理破坏了杀螨活性。该细菌菌株在几丁质培养基上提高的杀螨活性表明几丁质酶的参与。通过重组大肠杆菌表达的粘质沙雷氏菌 ChiA、ChiB 和 ChiC1 几丁质酶在实验室中对螨虫表现出致病性。这些几丁质酶在较宽的 pH 范围（5-9）内具有活性，最适温度在 60-75°C 之间。ChiA 和 ChiB 对杀螨活性表现出协同作用。两种蜜蜂的工蜂对喷洒和喂食几丁质酶均不敏感。这些结果为瓦螨的控制提供了替代策略，可通过制定几丁质酶制剂和构建转基因蜜蜂来实现。
