Vector control, the most efficient tool to reduce mosquito-borne disease transmission, has been compromised by the rise of insecticide resistance. Recent studies suggest the potential of mosquito-associated microbiota as a source for new biocontrol agents or new insecticidal chemotypes. In this study, we identified a strain of Serratia marcescens that has larvicidal activity against Anopheles dirus, an important malaria vector in Southeast Asia. This bacterium secretes heat-labile larvicidal macromolecules when cultured under static condition at 25°C but not 37°C. Two major protein bands of approximately 55 kDa and 110 kDa were present in spent medium cultured at 25°C but not at 37°C. The Liquid Chromatography-Mass Spectrometry (LC-MS) analyses of these two protein bands identified several proteases and chitinases that were previously reported for insecticidal properties against agricultural insect pests. The treatment with protease and chitinase inhibitors led to a reduction in larvicidal activity, confirming that these two groups of enzymes are responsible for the macromolecule's toxicity. Taken together, our results suggest a potential use of these enzymes in the development of larvicidal agents against Anopheles mosquitoes.

中文翻译：

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粘质沙雷氏菌分泌蛋白酶和几丁质酶，对幼虫按蚊有杀幼虫活性

媒介控制是减少蚊子传播疾病的最有效工具，但由于杀虫剂耐药性的提高而受到损害。最近的研究表明，与蚊子有关的微生物群有可能成为新的生物防治剂或新的杀虫化学型的来源。在这项研究中，我们确定了一种沙雷氏沙雷氏菌的菌株，该菌株具有抗拟按蚊的杀幼虫活性。是东南亚重要的疟疾媒介。在25°C而不是37°C的静态条件下培养时，该细菌会分泌热不稳定的幼虫大分子。在25°C而不是37°C下培养的废培养基中存在两条大约55 kDa和110 kDa的主要蛋白带。对这两个蛋白条带的液相色谱-质谱分析（LC-MS）分析确定了几种蛋白酶和几丁质酶，这些蛋白酶和几丁质酶以前据报道对农业害虫具有杀虫性能。蛋白酶和几丁质酶抑制剂的处理导致幼虫活性的降低，证实这两组酶是大分子毒性的原因。综上所述，我们的结果表明这些酶在开发针对按蚊的杀幼虫剂中的潜在用途。 蚊子。