黄芩乙醇提取物通过下调NAD特异的谷氨酸脱氢酶抑制哈维氏弧菌生长

哈维氏弧菌（Vibrio harveyi）是水产动物的常见致病菌，对人类健康和水产经济带来巨大威胁。抗生素的滥用使得药物残留和耐药性问题变得日益严重。因此，迫切需要寻找新型、不易产生耐药性和低毒的抗菌物质。本文研究黄芩醇提物对哈维氏弧菌的抑制作用及抑菌机制。实验结果表明，黄芩醇提物对哈维氏弧菌的抑菌圈为18.33±0.58 mm，最低抑菌浓度（MIC）和最小杀菌浓度（MBC）分别为7.92 mg/mL和15.84 mg/mL。经分析型扫描电镜（SEM）观察和细菌胞内外蛋白质浓度测定，发现实验组菌体表面虽有细小破裂，但形态依然完整，表面光滑，菌体细胞膜仍保持相对完整性；通过SDS-PAGE、蛋白质质谱(MALDI-TOF-TOF MS)和实时荧光定量PCR分析，显示黄芩醇提物抑制哈维氏弧菌体内NAD特异性的谷氨酸脱氢酶（NAD-specific glutamate dehydrogenase, NAD-GDH）及其mRNA的表达。本研究表明，黄芩醇提物通过下调NAD特异性的谷氨酸脱氢酶表达而抑制哈维氏弧菌的生长，为中药应用于水产养殖提供了新的证据。

Ethanol-extracts from Scutellaria Inhibit the Growth of Vibrio harveyi by Downregulating NAD+-dependent Glutamate Dehydrogenase#br#

Vibrio harveyi is one of common pathogenic bacteria, which is seriously imperilling human health and aquatic industry. Because of antibiotics abuse, drug residues and drug-resistance are becoming more serious. It is urgent to look for new alternatives with low toxicity and susceptiblilty to drug-resistance.In this study, we reveal the antibacterial effects of the ethanol extracts from Scutellaria on V. harveyi. The results showed that the ethanol extracts of Scutellaria had a strong inhibitory effect on V. harvey, the diameter of inhibition zone was 18.33±0.58 mm. The minimum inhibitory concentrations (MIC) and minimal bactericidal concentration (MBC) were 7.92 mg/mL and 15.84 mg/mL, respectively. By observation with scanning electron microscope (SEM) and concentration determination of intracellular and extracellular proteins, we found that although there were many little pores on the surface of V. harveyi, it remained smooth and integrated. After treated with ethanol extracts of Scutellaria, a band of protein disappeared in SDS-PAGE which was identified as NAD-specific glutamate dehydrogenase (NAD-GDH) by MALDI TOF-TOF-MS. Furthermore, the real-time PCR results showed that the mRNA levels of this gene were affected by ethanol extracts of Scutellaria. These results are in good agreement with Scutellaria application in aqueous infection, and indicate that ethanol extracts of Scutellaria inhibit V. harveyi growth effectively through downregulating the expression of NAD-dependent glutamate dehydrogenase, which provides new evidence for the application of traditional Chinese medicine in the fields of aquaculture.