红火蚁巢穴土壤中生物碱成分分析

【目的】红火蚁Solenopsis invicta栖息在真菌和细菌较丰富的土壤环境中,容易受多种真菌和细菌性病原体的侵染,因红火蚁的毒液具有很好的防御和抗菌作用,致使红火蚁能生存于此类土壤环境中。为了探索这一奥秘,本研究旨在建立红火蚁巢穴土壤中的毒液生物碱的最佳提取方法,并对毒液生物碱成分进行定量分析。【方法】采集蚁巢周边3 m处的土壤,进行添加、回收红火蚁毒液实验。采用抽滤法提取土壤中的毒液生物碱,利用GC-FID对毒液生物碱成分进行定量分析,筛选最佳的提取溶剂,并且确定添加三乙胺的最佳体积比。然后用最优方法提取蚁巢土壤中的毒液生物碱,并进行定量分析。【结果】正己烷、二氯甲烷、乙酸乙酯、丙酮和甲醇5种提取溶剂中,正己烷处理的生物碱回收率略优。当添加的三乙胺的体积为1 mL及以上时,提取效果最佳。红火蚁巢穴土壤中的毒液生物碱成分中,trans-C15∶1的含量最高,trans-C13∶1的含量次之。巢穴土壤中总生物碱含量约为22μg/g。【结论】三乙胺有助于提取蚂蚁巢穴土壤中的毒液生物碱。红火蚁巢穴土壤中的生物碱浓度较高,有可能对巢穴土壤微生物群落产生重要影响。

Analysis of alkaloid components in the soil from the nest of the red imported fire ant,Solenopsis invicta (Hymenoptera: Formicidae)

【Aim】 The red imported fire ant, Solenopsis invicta, inhabits the soilenvironment rich in bacteria and fungi. Although they are vulnerable to infection ofbacterial and fungal diseases, fire ants with defensive and antibacterial venom alkaloidscan survive in such soil environment. This study aims to establish an optimal extractionmethod of alkaloids from the soil of the red imported fire ant nest and then to quantifythe major components of venom alkaloids. 【Methods】 In the recovery experiment, S. invictavenom was added to soil obtained 3 m away from S. invicta nests. Venom alkaloids were thenextracted from soil using a filtration method. GC-FID was used for quantitative analysisof venom alkaloids, screening of the optimal extraction solvent, and determination of theoptimal volume of triethylamine. The optimized method was used for quantitative analysis ofvenom alkaloids from the soil of ant nest. 【Results】 Among the five extraction solventsincluding n-hexane, dichloromethane, ethyl acetate, acetone and methanol, the recoveryrate of alkaloids by n-hexane extraction was relatively higher. The best extractionefficiency was achieved by adding 1 mL or more triethylamine. Among the venom alkaloids inthe soil of S. invicta nest, the content of trans-C15∶1 was the highest, followed by that of trans-C13∶1. The content of total alkaloids in S. invicta nest soil was about 22μg/g. 【Conclusion】 Triethylamine is very effective for extracting venom alkaloids fromthe soil of ant nests. The concentration of alkaloids in the soil of S. invicta nest isrelatively high, which may have an important impact on the microbial community in the nestenvironment.