噬菌蛭弧菌颗粒剂制备条件的优化

试验采用海藻酸钠包埋法对噬菌蛭弧菌(Bdellovibrio bacteriovorus)进行固定化,制备得到噬菌蛭弧菌颗粒。以噬菌蛭弧菌活菌数为考核指标,优化噬菌蛭弧菌固定化条件。通过单因素试验和正交试验,评价了海藻酸钠浓度、氯化钙浓度、蛭弧菌菌液与海藻酸钠胶体溶液的比例(V/V)、玉米油浓度、包埋温度、搅拌时间、搅拌速度和交联时间对噬菌蛭弧菌固定化的影响。结果表明,作为载体配方优化因素的海藻酸钠浓度和玉米油浓度对活菌数具有显著性影响,而氯化钙浓度和蛭弧菌菌液与海藻酸钠胶体溶液的比例(V/V)影响不显著;作为过程优化因素的温度和搅拌速度对活菌数具有显著性影响,而搅拌时间和交联时间影响不显著。在海藻酸钠浓度1.5%、氯化钙浓度6.5%、蛭弧菌菌液与海藻酸钠胶体溶液的比例(V/V)50%、玉米油浓度4.5%、包埋温度47.5℃、搅拌时间40min、搅拌速度450r/min和交联时间36h的条件下,制得的固定化蛭弧菌颗粒活菌数对数值达到7.51。本方法经济、安全、保存效能好,适合在水产养殖中应用。     

蛭弧菌对草鱼片大肠杆菌生长的控制研究

[目的]研究噬菌蛭弧菌BDYJAL对新鲜草鱼片大肠杆菌生长的控制作用。[方法]进行了蛭弧菌BDYJAL对32株潜在致病菌的裂解试验;并通过设置3个组别：蛭弧菌低浓度组（蛭弧菌∶宿主=1∶1）、蛭弧菌高浓度组（蛭弧菌∶宿主=10∶1）和非添加蛭弧菌对照组,进行了蛭弧菌BDYJAL对草鱼片大肠杆菌的生长控制试验。[结果]蛭弧菌BDYJAL对32株潜在致病菌的裂解率达到了93.8%;鱼片大肠杆菌控制试验中,与对照组相比2个试验组对大肠杆菌的消除控制存在显著差异（P〈0.05）,但这2个试验组在0~36 h内的消除效果无显著差异（P〉0.05）。[结论]蛭弧菌BDYJAL能有效控制新鲜草鱼片的大肠杆菌生长。     

Isolation of Bdellovibrio as Biological Therapeutic Agents Used For the Treatment of Aeromonas hydrophila Infection in Fish

Fourteen strains of Bdellovibrio‐like organisms were isolated from cultured fish ponds using Aeromonas hydrophila J‐1 as host, one of them formed large plaques after 48 h of incubation at 28°C on a double layer plate, designated as Bdellovibrio C‐1. The Bdellovibrio was confirmed by electron microscopy and PCR amplification of Bdellovibrio‐specific 16S rDNA. The optimum temperature for the growth of BdC‐1 was between 15–37°C and with optimal activity at temperatures of 25–30°C. The ability of BdC‐1 to lyse A. hydrophila was similar in the pH range of 6.5 to 8.5. It can lyse 23 Gram‐negative bacterial strains comprising three genera of fish pathogens and one strain of Escherichia coli but cannot lyse Gram‐positive bacteria such as Bacillus subtillis and Staphylococcus aureus. Immersion of fish in water containing different concentrations of BdC‐1 was used in protection against an experimental infection of A. hydrophila J‐1. Results show that the mortality of groups immersed with BdC‐1 was lower than the group without BdC‐1. These results suggest that it may be possible to use Bdellovibrio to control the disease caused by A. hydrophila.     

噬菌蛭弧菌对鲟鱼免疫相关酶活性的影响

试验对鲟鱼基础饲料喷洒蛭弧菌制剂,喷洒量分别为0(对照组)、3、6、9mg/g,于30d后分别测定血清中免疫相关酶的活性,结果表明,相对于对照组,试验组的溶菌酶活性、AKP活性都极显著的增强(P<0.01);试验组的POD活性有显著的增强(P<0.05)。综合本次研究结果表明,饲料中添加蛭弧菌能对鲟鱼体内免疫相关酶系统产生积极的调理改善作用,使其非特异性免疫力得到改善与提高。结合养殖成本与文章结果得出的最低有效浓度,建议其适宜添加量为5～8mg/g。     

蛭弧菌对西施舌幼虫生长和培养水质的影响

研究了不同浓度蛭弧菌在西施舌幼虫培养中的应用,在温度26～27℃,以人工授精发育的西施舌幼虫为材料,测定水中氨氮、亚硝态氮浓度和pH值,并计算幼虫的生长速率以及成活率,与对照组进行比较,实验表明,氨氮浓度最多比对照组降低34%(P<0.05),亚硝态氮浓度最多降低25%(P<0.05)。结果表明,蛭弧菌100mg/L为最适浓度,在一定程度上降低水中氨氮和亚硝态氮浓度,并促进西施舌壳顶幼虫的生长,其生长速率高于对照组22%,成活率高于对照组13%,差异显著(P<0.05),但对pH值影响不显著。