Benthic microbial indicators of fish farm impact in a coastal area of the Tyrrhenian Sea

We studied the impact of organic loads due to the biodeposition of a fish farm in a non-impacted coastal area of the Tyrrhenian Sea (Western Mediterranean). Sediment chemistry and benthic microbial community were investigated from July 1997 to February 1998 on monthly basis at two stations: one was located under the fish farm, while the second was about 1 km away, and served as a reference site. The presence of the cage induced rapid changes in the benthic conditions: the sediments were rapidly (after 6 weeks) reduced. A significant accumulation of biopolymeric carbon was observed beneath the cage both 2 weeks after the initial cage deployment, on non-impacted sediments, and 5–7 months after, and appeared to be related to the fish farm production cycle. The density of microbial communities beneath the fish farm increased only during the first month of farming activity (July) and partially 7 months after cage disposal (i.e. in January), when there was a significant sediment organic enrichment. Additional evidence of rapid impact of the fish farm on the benthic bacterial communities is provided by the increase in the numbers of autofluorescent microbial cells. The photosynthetic eukaryotic cells displayed a highly reduced contribution to total autofluorescent microbial density, indicating that their decrease is related with biopolymeric carbon accumulation, and probably was due also to “shadow effect” induced by suspended material, coming from the fish farm, on the environment below. We propose here, to apply the ratio of culturable heterotrophic bacteria to microbial direct counts (CFU/MDC) to detect fish farm impact. In cage sediments, organic enrichment and the consequent modification of the characteristics of the benthic environment, determined an increase in aerobic heterotrophic bacteria and vibrio density indicating that they are efficient colonizers of organic-rich sediments. Densities of Escherichia coli and Enterococci were not significantly higher than in the reference site, and are likely of terrestrial origin. Thus they cannot be used as specific indicators of fish farm impact.     

分泌抗金黄色葡萄球菌细菌素乳酸菌的分离鉴定

为分离和筛选产抗金黄色葡萄球菌乳酸菌素的优势乳酸菌,利用乳酸菌分离培养基MRS从收集的各种腌制菜汁中分离培养乳酸菌,通过细菌培养特性、革兰氏染色特点、生理生化特性初步鉴定,同时根据Genbank中乳酸菌的16SrDNA序列设计特异性引物,采用PCR方法进一步鉴定,并以金黄色葡萄球菌为指示菌对乳酸菌的发酵上清液进行抑菌特性研究。结果表明,从腌渍菜汁中分离获得90株产酸菌,通过形态学、生理生化特性和PCR鉴定,结果73株产酸菌为乳酸杆菌;分泌产物抑菌试验表明,有10株菌具有抑制金黄色葡萄球菌活性,经酸排除和过氧化氢排除试验,仍然有5株乳酸菌的分泌产物具有抑制金黄色葡萄球菌活性。可见,从腌渍菜汁分离到的乳酸菌具有抑制金黄色葡萄球菌活性的特性,主要是通过分泌乳酸菌素来发挥作用。     

荧光定量PCR法比较研究健康和子宫内膜炎奶牛阴道菌群结构

为揭示奶牛阴道菌群结构与子宫内膜炎发生关系,本实验选择健康奶牛和患有子宫内膜炎奶牛各5头,采集其阴道粘液样品,提取样品总DNA,利用SYBR Green Ⅰ荧光定量PCR方法对这两类奶牛阴道菌群结构的差异进行了检测.检测结果显示,健康奶牛阴道内乳杆菌属(p＜0.05)、芽孢杆菌属(p＜0.05)和魏斯氏菌属(p＜0.01)的细菌数量显著或极显著高于子宫内膜炎奶牛,而子宫内膜炎奶牛阴道内大肠杆菌数量显著高于健康奶牛(p＜0.05).研究结果表明,阴道菌群结构失衡可能是奶牛子宫内膜炎发生的原因.     

湛江东海岛对虾育苗场水体细菌的抗生素耐药性

利用K-B纸片扩散法研究分离自湛江东海岛6个对虾育苗场(分别编号为YF,JD,DC,HM,SD,XR)水体中的217株细菌菌株对12种抗生素的耐药性。研究结果表明,参试的12种抗生素之间的细菌耐药性差异显著(ANOVA,P0.05),6个育苗场内细菌对多粘菌素B、左氟沙星和环丙沙星高度敏感,对氨苄西林、甲氧苄胺嘧啶、复方新诺明和四环素则高度耐药;多重耐药菌株在每个育苗场中均有发现,52.07%的菌株呈现多重耐药性,未发现对参试的12种抗生素100%耐药的菌株。统计分析结果显示,尽管HM和XR育苗场的细菌耐药性比其他育苗场高,但6个对虾育苗场之间水体细菌的抗生素耐药性无显著差异(ANOVA,P0.05)。     

不同复配基质理化性质及其对辣椒幼苗生长发育的影响

为确定适宜辣椒无土穴盘育苗基质配方,以玉米芯为发酵原料,EM酵素菌、有机物料腐熟剂、金宝贝菌剂为发酵菌剂,以筛选出最佳的发酵菌剂,后将用最佳菌剂发酵好的玉米芯与蛭石、珍珠岩按不同比例复配,进行育苗配比优化试验。结果表明,EM酵素菌为最佳发酵菌剂;玉米芯固持作用差,适合与其他基质复配,可形成理化性质良好的有机型基质,以复配基质处理A1（玉米芯：蛭石=1：1）和A4（玉米芯：蛭石：珍珠岩=2：1：1）辣椒幼苗干质量、鲜质量、壮苗指数较高,与对照水平相似,且出苗率较高,出苗期较集中。     

硝化细菌分子生态学研究进展

硝化细菌在促进水域生态系统的氮循环、保持健康水产养殖环境方面发挥着巨大作用。本文分析了硝化细菌分子生态学研究的意义,介绍了硝化细菌的主要种类及其系统进化关系,综述了硝化细菌分子生态学研究进展,并对中国的研究现状进行了分析。结合作者的工作实践,认为中国应加强对水产养殖环境硝化细菌分子生态学研究,为养殖环境的污染防治和微生态制剂的研制等提供理论依据。     

固定化微藻对养殖对虾细菌数量的影响

以固定化技术为基础,人工制成微藻藻珠,引入波吉卵囊藻(Oocystisborgeisnow)和微绿球藻(Nannochloropsis oculata)于凡纳对虾(Litopenaeusvannamei)养殖环境中,采用直接计数法研究了养殖水体、对虾肌肉、对虾肝胰脏中异养菌及弧菌的数量变化。结果表明,引入藻珠能抑制异养菌和弧菌的生长,并能改善水质。试验末期,试验1、2、3组水样中弧菌数量分别降低了95%、95%、81.7%,异养菌数量降低了72.3%、77.1%、95.6%。可见固定化微藻在一定程度上能改善虾池细菌生态系,有助于预防对虾疾病。     

头孢氨苄对斑节对虾幼体发育及育苗水体细菌数量的影响

研究了不同浓度头孢氨苄(Cefalexin)对斑节对虾Penaeusmonodon幼体发育以及对斑节对虾育苗水体中异养菌总数和弧菌数量的影响。在试验初期,无论是对照组还是施用头孢氨苄的各试验组,育苗水体中的总异养菌数量和弧菌数量都呈现出较为明显的上升趋势;在第二次施用头孢氨苄后,各试验组的异养菌总数和弧菌数量的增幅明显低于对照组(或出现异养菌总数和弧菌数量缓慢下降),而对照组异养菌总数和弧菌数量则呈现显著的上升。施用0.5～1.0μL·L-1头孢氨苄对育苗水体中的总异养菌有显著的杀灭及抑制作用,但对弧菌数量杀灭及抑制作用并不显著;施用1.5μL·L-1头孢氨苄对育苗水体中的总异养菌和弧菌数量的杀灭及抑制作用显著。当幼体变态发育至仔虾第8天(P8)时,对照组异养菌总数和弧菌数量分别达6.33×105和3.55×104CFU·mL-1,均远远高于试验组的异养菌总数和弧菌数量增长的幅度。试验组的幼体变态到P1期的时间,比对照组缩短了10h以上;试验组的成苗率也比对照组提高了3.2%～13.1%。     

福建省主要海水养殖鱼类疾病及其防治

本文通过对福建省沿海海水养殖鱼类发生的疾病种类、主要发病鱼类、疾病主要症状、流行情况及防治方法进行调查，总结出福建省海水养殖鱼类近三年共发生24种疾病，其中病毒性疾病2种，细菌性疾病4种，寄生虫性疾病11种，不明原因疾病7种。这些疾病中危害较大的主要是病毒病、弧菌病和本尼登虫病。