球形芽孢杆菌LP1-G的发酵特性及杀蚊活性

球形芽孢杆菌（Ｂａｃｉｌｌｕｓ ｓｐｈａｅｒｉｃｕｓ）ＬＰ１－Ｇ菌株在ＭＢＳ培养基上能正常生长、发育，产生位于芽孢孢外膜外的伴孢晶体。其产生的４１．９和５１．２ｋＤ二元毒素蛋白合成于芽孢形成期，另一分子量约为４９ｋＤ蛋白和二元毒素同期合成，并随着芽孢的释放而被降解。生物测定结果表明该菌株在营养体生长阶段对致倦库蚊幼虫无毒，孢子囊初期毒力较高，并在整个芽孢形成期都维持较高的毒力水平。其全发酵液对敏感和抗性库蚊幼虫都具有中等的毒杀作用，对３～４龄幼虫４８ｈ的ＬＣ_５０。值分别为０．１１３和０．１３７ｍｇ／ｍＬ。该菌株对敏感和抗性致倦库蚊幼虫的毒杀作用可能同其产生４９ｋＤ蛋白相关。

CHARATERIZATION OF BACILLUS SPHAERICUS LP1-G AND ITS TOXICITY AGAINST SUSCEPTIBLE AND RESISTANT MOSQUITO LARVAE

Bacillus sphaericus LP1-G, belonging to serotype H3, can grow and develop well in MBS media and synthesize 41.9 and 51.2kD proteins, which resemble in a parasporal form during sporulation. SDS-PAGE analysis showed that this strain can also synthesized another 49kD peptide during sporulation. The sporangium and spore/ crystal cultures of LP1-G had medium toxicity against 3-4 instar Culex quinquefasciatus, in comparison, the vegetative culture had no toxicity against the target larvae. It has also been found that the final whole culture had same activity to both susceptible and resistant C. quinquefasciatus and the LC_50 values at 48h were 0.113 and 0.1117mg/mL respectively. It is suggested that the presence of P49 protein in LP1-G could be responsible for its toxicity against both susceptible the resistant mosquito larvae.