番石榴叶挥发油的抗菌性及优化提取研究

分别由酸疮痂链霉菌（Streptomyces acidiscabies, SA）、茄科雷尔氏菌（Ralstonia solanacearum, RS）和胡萝卜软腐欧文氏菌（Erwinia carotovora subsp. carotovora Borgey, ECCB）引起的植物疮痂病、青枯病、软腐病是农作物生产中常见多发的细菌病害。番石榴叶挥发油由多种活性物质组成，具有广谱抗微生物活性。本研究旨在提取并配置番石榴叶挥发油抗菌液，针对酸疮痂链霉菌、茄科雷尔氏菌、胡萝卜软腐欧文氏菌等3种病原菌进行挥发油的抗性研究，为农作物病害生物防治储备资源。采用添加锂盐结合微波辅助水蒸馏法提取番石榴叶挥发油，通过滤纸片扩散法和最小抑制浓度（MIC）评价了番石榴叶挥发油对3种供试菌株的抗菌效果，单因素结合响应面试验优化提取工艺，采用气相色谱-质谱联用技术（GC-MS）测定番石榴叶挥发油的化学成分。结果表明：番石榴叶挥发油对酸疮痂链霉菌、茄科雷尔氏菌、胡萝卜软腐欧文氏菌均表现出良好的抑制效果，抑菌圈直径范围为20.57～23.24 mm，抑菌率均达到60%以上，MIC值分别为3.13、1.56、3.13...

Antibacterial Activity and Optimal Extraction of Volatile Oil from Guava Leaves

Streptomyces acidiscabies (SA), Ralstonia solanacearum (RS) and Erwinia carotovora subsp carotovora borgey (ECCB) cause plant scab, brucellosis and soft rot of carrot, respectively. These are common and prevalent bacterial disease in crop production. The volatile oil of Guava leaves consists of a variety of active substances with broad-spectrum anti-microbial activity. The aim of this study was to extract and configure an antimicrobial solution of guava leaves volatile oil to conduct a volatile oil resistance study against three disease bacteria, SA, RS and ECCB, to reserve resources for biological control agents. The volatile oil of guava leaves was extracted by the addition of lithium salt combined with microwave-assisted hydrodistillation, the antibacterial effect of guava leaf volatile oil on three test strains was evaluated by the filter paper diffusion method and minimum inhibitory concentration (MIC), and the extraction process was optimized by single factor combined with response surface experiments. The chemical components of guava leaf volatile oil were determined by gas chromatography-mass spectrometry (GC-MS). The results showed that the oil exhibited excellent inhibitory effects against SA, RS and ECCB, with the inhibition circle diameters ranging from 20.57 to 23.24 mm and the inhibition rates reaching more than 60%, and the MIC values of 3.13 μg/mL, 1.56 μg/mL and 3.13 μg/mL, respectively. The oil had the greatest inhibitory effect on RS, the diameter of the inhibition circle was (23.24±0.47)mm, which was highly sensitive, and also had certain inhibitory effect on SA and ECCB. The optimum process conditions for the extraction process were liquid to material ratio of 10 mL/g DW, microwave power of 660 W and microwave time of 43 min. The yield of the oil obtained under the conditions was (10.23±0.17)mL/kg DW, and the validity and reproducibility of the method were verified by three parallel experiments. The components of the oil were detected to be mainly terpenes and alcohols, with relatively high content of β-caryophyllene (28.36%), l-calamenene (11.47%), (-)-globulol (11.31%) and α-pinene (10.01%). The substances that played a major role in the antibacterial experiment were β-caryophyllene, α-pinene, eugenol, and D-limonene. It was speculated that the mechanism of guava leaf volatile oil inhibition on the test strain was the damage to its cell structure, which resulting in the leakage of intracellular material. The above results demonstrated that the guava leaf volatile oil has an excellent antimicrobial activity and considerable extraction rate, the results of the study would provide a reference for the development and application of guava leaves and integrated control of crop diseases.