灭活鳗弧菌(Vibrio anguillarum)刺激后中国明对虾(Fenneropenaeus chinensis)血液抗菌活性的变化

采用对中国明对虾(Fenneropenaeuschinensis)人工注射灭活鳗弧菌,利用溶壁微球菌(Micrococcusluteus)和鳗弧菌(Vibrioanguillarum)作为测试菌株,对在抑菌活性检测中最为常用的抑菌圈法、辐射扩散法和液体培养基微量稀释检测法进行了技术改进并比较了它们的检测效果,并检测了阳离子交换柱层析法初步分离的中国明对虾血淋巴主要组分的抗菌活性,进行了细菌攻毒前后中国明对虾血浆及血细胞抗菌活性变化的研究。结果表明,液体培养基微量稀释检测法抑菌效果在三种方法中灵敏度最高,抑菌圈法灵敏度最低,但对于蛋白含量较高的样品,辐射扩散法被证明在抑菌活性检测方面更为适用。利用改进的辐射扩散法对灭活鳗弧菌攻毒前后的中国明对虾血细胞和血浆的抑菌活性进行了检测,结果显示,虽然感染后血细胞数目显著降低(P<0·05),但其抑菌能力却明显增强(P<0·05),相对而言,血浆抑菌活性变化不显著(P>0·05),说明血细胞在受到免疫刺激后抗菌因子的表达进一步加强。

杂合抗菌肽KL-21与抗生素体外协同抗菌效果研究

为了进一步研究杂合抗菌肽KL-21的抗菌活性和探索其应用潜力,试验测定了KL-21和抗生素对4种常见致病菌的抑菌活性,同时评估了KL-21与4种常见抗生素联用的协同效果。试验采用微量倍比稀释法测定KL-21和4种抗生素的最小抑菌浓度(MIC)及最小杀菌浓度(MBC),利用棋盘试验法测得部分抑菌浓度指数(FIC)评估联用后的协同效果。结果表明,KL-21对4种致病菌均有良好的抑菌活性,与卡那霉素、庆大霉素、链霉素及氯霉素联合使用时具有协同或部分协同作用,可以将抗生素体外抑菌试验的MIC减少至1/16~1/2,为人工设计杂合抗菌肽KL-21的实际应用提供了参考,为畜牧生产以及动物疫病治疗提供更多选择。

Antimicrobial potential of Actinomycetes species isolated from marine environment

Objective:To evaluate the antimicrobial activity of Actinomycetes species isolated from marine environment.Methods:Twenty one strains of Actinomyceteswere isolated from samples of Royapuram, Muttukadu, Mahabalipuram sea shores and Adyar estuary. Preliminary screening was done using cross-streak method against two gram-positive and eight gram-negative bacteria.The most potent strains C11 and C12 were selected from which antibacterial substances were extracted. The antibacterial activities of the extracts were performed using Kirby-Bauer disc diffusion method. Molecular identification of those isolates was done.Results:All those twenty one isolates were active against at least one of the test organisms. Morphological characters were recorded. C11 showed activity againstStaphylococcusspecies(13.0暲0.5 mm),Vibrio harveyi(11.0暲0.2 mm),Pseudomonas species(12.0暲0.3 mm). C12 showed activity against Staphylococcus species(16.0暲0.4 mm),Bacillus subtilis(11.0暲0.2 mm),Vibrio harveyi(9.0暲0.1 mm),Pseudomonas species(10.0暲0.2 mm). 16S rRNA pattern strongly suggested that C11 and C12 strains were Streptomyces species.Conclusions:The results of the present investigation reveal that the marineActinomycetesfrom coastal environment are the potent source of novel antibiotics.Isolation, characterization and study of Actinom ycetescan be useful in discovery of novel species of Actinomy cetes.

Antimicrobial activities of the rhizome extract of Zingiber zerumbet Linn

Objective:To investigate antimicrobial effects of ethanolic extract of Zingiber zerumbet(Z.zerumbet)(L.)Smith and its chloroform and petroleum ether soluble fractions against pathogenic bacteria and fungi.Methods:The fresh rhizomes of Zingiber zerumbet were extracted in cold with ethanol(4.0 L)after concentration.The crude ethanol extract was fractionated by petroleum ether and chloroform to form a suspension of ethanol extract(15.0 g),petroleum ether fraction(6.6 g)and chloroform soluble fraction(5.0 g).The crude ethanol extract and its petroleum ether and chloroform fractions were evaluated for antibacterial and antifungal activity against thirteen pathogenic bacteria and three fungi by the disc diffusion method.Commercially available kanamycin(30μg/disc)was used as standard disc and blank discs impregnated with the respective solvents were used as negative control.Results:At a concentration of 400μg/disc,all the samples showed mild to moderate antibacterial and antifungal activity and produced the zone of inhibition ranging from 6 mm to 10 mm.Among the tested samples,the crude ethanol extract showed the highest activity against Vibrio parahemolyticus(V.parahemolyticus).The minimum inhibitory concentration(MIC)of the crude ethanol extract and its fractions were within the value of 128-256μg/mL against two Gram positive and four Gram negative bacteria and all the samples showed the lowest MIC value against V.parahemolyticus(128μg/mL).Conclusions:It can be concluded that,potent antibacterial and antifungal phytochemicals are present in ethanol extract of Z.zerumbet(L.).

不同提取方法对北五味子提取物抑菌活性的影响

[目的]比较不同提取方法北五味子提取物抑菌活性,为进一步开发利用北五味子,增加其附加价值提供参考。[方法]采用超临界CO2萃取、乙醇提取和水提等方法对北五味子成分进行提取,研究其提取物抑菌活性。[结果]北五味子提取物对供试菌有一定抑制作用;乙醇提取物对2种菌的抑制效果均高于超临界提取物和水提取物。[结论]用醇提取法北五味子提取物抑菌活性较好,这为进一步开发利用北五味子,增加其附加价值提供了参考。

响应面法优化红花酢浆草抑菌活性物质的提取工艺研究

为建立红花酢浆草抑菌活性物质的最佳提取工艺,在单因素实验的基础上,选取提取时间、乙醇体积分数和固液比为自变量,抑菌圈直径为响应值,建立数学模型,求解得到最佳提取条件和理论最大抑菌圈并验证。结果显示,红花酢浆草抑菌活性物质的最佳提取工艺为:乙醇体积分数73%,提取时间78 min,固液比1∶31 g/m L。此时,红花酢浆草醇提取物拮抗金黄色葡萄球菌的抑菌圈直径为30.17 mm,较优化前提高67.61%。响应面优化法不仅效率高,而且可靠性强,可准确预测抑菌圈直径。同时,证明红花酢浆草的醇提取物具有较为广泛的抑菌谱。

抗弧菌杀鱼假交替单胞菌2515的潜在毒性及热处理脱毒后抗菌效果

为评估一株具有弧菌拮抗功能的杀鱼假交替单胞菌2515 Pseudoalteromonas piscicida 2515(以下简称“菌株2515”)对海水养殖动物的毒性,并确定一种有效的热处理脱毒方法,在中国明对虾Fenneropenaeus chinensis育苗水体中分别添加浓度为105、106、107、108 CFU/mL的菌株2515,测试其对中国明对虾受精卵孵化及幼体发育的影响。结果表明:水体中添加浓度高于105 CFU/mL的菌株2515后,显著降低了无节幼体变态发育至蚤状幼体的成活率(P<0.05);分别应用血平板及显微观察法测试菌株2515对羊、鱼及对虾血细胞的溶血活性,结果显示,该菌对羊及鱼红细胞均具溶血活性,而对凡纳滨对虾Litopenaeus vannamei血细胞无溶血活性;设置不同温度(40、45、50、55、60、65、75℃)热处理菌株2515及其破碎液,结果显示,55℃1 h能够灭活该菌,且失去对鱼类红细胞的溶血活性,而抑菌物质活性可提高55.8%。研究表明,菌株2515对鱼虾具有潜在毒性,选择适当热处理,既能灭活溶血活性还可提高抗菌活性。