Isolation,Identification and Drug Sensitivity Analysis of Pseudomonas aeruginosa from Minks

In order to provide therapeutical guidance for drug admistration,the bacteria from five dead minks suffering with typical symptoms provided by mink farms in Shandong province were isolated and identified,and the drug sensitivity was tested.The bacteria were isolated with TSA plates,and identified using biochemical methods and PCR assay.The drug sensitivity of the isolates to antimicrobial agents was investigated using K-B method.PCR was used to detect the resistance genes.A total of 5 Pseudomonas aeruginosa isolates were obtained from sick minks.The drug sensitivity results showed that 5 strains were sensitive to fluoroquinolone,the third and fourth generations cephalosporin drugs,but were resistant to aminoglycoside,tetracycline,chloramphenicol,penicillin,the first and second generations cephalosporin drugs.There were six resistance genes were detected,aadA1,aac(3')-Ⅱc,aac(6')-Ⅰb,tetA,tetK and cat2.All of the isolates were detected more than three kinds of resistance genes.The result showed that 5 strains were all Pseudomonas aeruginosa,and Pseudomonas aeruginosa was the main cause of mink hemorrhagic pneumonia.The resistance of 5 strains were very serious and mainly for multiple drug resistance phenomenon.The resistance genes detected in the mink were various,and could cause the resistance to the drugs.     

3-蒈烯对铜绿假单胞菌的抑菌活性及机理初探

为了开发一种新的食品防腐保鲜剂,本文初步研究了3-蒈烯对铜绿假单胞菌的抑菌活性及机理。通过肉汤稀释法测定最小抑菌浓度（MIC）和最小杀菌浓度（MBC）,评价了3-蒈烯的抑菌活性,考察了3-蒈烯对细菌生长曲线、细胞形态、细胞膜通透性、膜电位及呼吸链脱氢酶等的影响。结果表明：3-蒈烯对铜绿假单胞菌的MIC为20 mL/L,MBC为40 mL/L。3-蒈烯可以抑制铜绿假单胞菌的生长,破坏细胞的正常形态,提高细胞膜的通透性,造成蛋白质、电解质的外泄。3-蒈烯能够降低铜绿假单胞菌菌体的膜电位,干扰细胞正常代谢活动,还能抑制细胞内呼吸链脱氢酶的活性。综上所述,3-蒈烯通过破坏铜绿假单胞菌细胞膜,抑制细菌正常生长,导致细菌细胞死亡。     

雏鸡绿脓杆菌病的诊断

报告了３个疫点肉用仔鸡群中自发的败血型绿脓杆菌病．总共３８５０羽３～５日龄雏鸡中，在２０ｄ流行期间，９１０羽发病，其中５７６羽死亡．从病死鸡的心血和肝中分离到绿脓杆菌而证实了临床诊断．     

1株林麝源绿脓杆菌的分离鉴定及全基因组序列分析

旨在确定甘肃省天水市某林麝养殖场致死林麝的病原菌,并开展其致病性和耐药性研究及全基因组序列分析。采集病死林麝肺,通过细菌的分离纯化、生化鉴定和16S rRNA基因序列分析,对分离菌进行鉴定;随后对其致病性和药物敏感性进行分析,并在分离菌全基因组测序的基础上,对分离菌全基因组序列进行组装和注释,对毒力基因toxA和exoT进行遗传进化分析。结果表明,从病死林麝肺中分离到一株绿脓杆菌,命名为TS2019。致病性试验测得分离菌对小鼠的LD₅₀为2.82×10⁷CFU·mL^-1;药敏试验结果表明,TS2019具有多重耐药性,但对环丙沙星、洛美沙星等药物敏感。基因组测序表明,TS2019基因组全长为6 308 327 bp,编码5 929个基因,其中有1 035个编码产物参与新陈代谢途径;全基因组中有毒力因子编码基因875个,产物有黏附蛋白、调控因子、毒性蛋白等;有四环素类、氨基糖苷类等抗生素耐药相关基因5 288个。遗传进化分析表明,TS2019毒力基因toxA、exoT与GenBank中绿脓杆菌众多菌株相应基因序列相似性均高于99%,其中eoxT基因与中国杭州人源分离株P33的遗传关系最近,但处于独立分支。本研究从病死林麝肺分离鉴定到一株绿脓杆菌,并证实该菌有较强致病性和多重耐药性,其毒力基因toxA和exoT与GenBank中绿脓杆菌相应基因序列具有高度相似性。研究结果为林麝绿脓杆菌感染相关疾病的防治提供了理论支持,也为绿脓杆菌致病机制和耐药机制的深入研究奠定了基础。     

铜绿假单胞菌的温度、pH值和乳酸钠主参数模型构建

采用全自动微生物生长曲线分析仪Bioscreen测定分离自腐败冷却猪肉的铜绿假单胞菌在不同温度(25~40℃)、pH值(5.0~7.5)、乳酸钠质量浓度(0~0.035 g/mL)影响下的生长曲线。基于最小二乘法运用Matlab软件中的fminsearch函数拟合铜绿假单胞菌迟滞期关于温度、pH值和乳酸钠质量浓度的主参数模型,经参数估计求得铜绿假单胞菌的最低生长温度、最适生长温度、最高生长温度、最低生长pH值、最适生长pH值、最高生长pH值、乳酸钠的最小抑菌浓度,进而通过10组随机数据进行验证。结果表明,构建的主参数模型能较好预测铜绿假单胞菌的相关生长参数,决定系数R2为0.929 1,偏差因子B f为1.097 5,准确因子A f为1.393 6,平方根误差为1.598 9。验证组的决定系数R2为0.854 6,偏差因子B f为1.122 5,准确因子A f为1.211 7,都在可接受的范围内。     

侧孢芽孢杆菌对铜绿微囊藻生长胁迫的研究

为探讨侧孢芽孢杆菌(Bacillus laterosporus)SK-1对铜绿微囊藻(Microcystis aeruginosa)生长胁迫的影响,在实验室环境下对两者共适培养基质进行了选择和优化,探究了处于不同生长期和不同初始生物量的上述两者在共基质中的数量消长规律,以及共基质体系中无机氮营养盐(NO-3-N、NO-2-N、NH+4-N)的含量变化。结果显示,将取自富营养化池塘的养殖水,添加适量葡萄糖和氨氮使得C∶N∶P的近似比为250∶10∶1的培养基质作为共适培养基质。在此基质中,不同生长时期的侧孢芽孢杆菌与铜绿微囊藻共存时的生长胁迫效应不同,处于生长稳定期的菌体对生长初期的微囊藻抑制效果最好,且在一定的浓度范围内,菌体细胞密度越大,其抑藻效果越明显。研究表明,侧孢芽孢杆菌对铜绿微囊藻生长的抑制是通过竞争营养物质与分泌胞外抑藻物质这两种方式实现的,且在藻体和菌体的不同生长阶段,这两种作用方式所占的比重不同。故在生态控藻时,须在藻类爆发生长前进行细菌种群的培育,以获得良好的生态效果。     

硝磺草酮对微囊藻和四尾栅藻光合作用及竞争的影响

采用纯培养和混合培养方法,结合调制叶绿素荧光测定技术,研究了硝磺草酮对微囊藻和四尾栅藻光合作用及种间竞争的影响。结果表明:0.5~10 mg·L-1硝磺草酮降低了微囊藻和四尾栅藻的最大光化学量子产量(Fv/Fm)和快速光曲线(RLCs)拟合参数(Ik、α、ETRmax),降低幅度与硝磺草酮浓度正相关;处理14 d时,Fv/Fm、Ik、α、ETRmax水平均达到暴露以来最小值,表明微囊藻和四尾栅藻在硝磺草酮处理期间未表现出恢复趋势。对比2种藻荧光参数变幅可知,硝磺草酮对四尾栅藻各荧光参数影响大于微囊藻,表明四尾栅藻的敏感性高于微囊藻。混合培养实验结果显示对照组微囊藻同四尾栅藻相比处于竞争劣势,而5、10 mg·L-1硝磺草酮处理时,微囊藻在与四尾栅藻的种间竞争中逐渐占据优势,且在微囊藻与四尾栅藻初始接种体积比为1∶3的混合培养体系中表现出最强的竞争力。较高浓度的硝磺草酮可使微囊藻由原劣势地位转为逐渐占据竞争优势,故硝磺草酮对水体中蓝藻水华的爆发具有潜在的促进作用。     

绿色微囊藻等不同食物对大型生长和脂类成分的影响

The growth and reproduction of Daphnia magna fed with Microcystis viridis and Chlorella spp respectively and 20% fish oil + 80% yeast and yeast were studied. The intrinsic rate of natural increase of Daphnia magna (rm) was 0.243 fed with Microcystis viridis, 0.301 with Chlorella spp., 0.244 with 20% fish oil + 80% yeast and 0.193 with yeast. The result showed that：Daphnia magna fed with Microcystis viridis had lower growth rates than that fed with Chlorella spp. an d 20% fish oil + 80% yeast which both had full fatty acids. And the Daphnia magna fed with yeast was the lowest. So the fatty acids composition of diet may affect the growth of Daphnia magna. This paper further examined total lipids and main HUFA (EPA and DHA) compositions of the continuous three generations of Daphnia magna (in order to get rid of t he effects of former diet) fed with different of above diets (except the yeast). The result showed that:the three generations of the D. magna fed with Microcystis viridis had the lowest total lipids and the percentages of the HUFA (EPA, and no DHA) have a significant decrease and get the lowest EPA in the final experiment because of the very low HUFA especially EPA and DHA in Microcystis viridis. So the results indicate that Microcystis viridis with low HUFA made the lower growth rate, spawn ing rate and hatching rate of Daphnia magna.     

In situ studies on the bioaccumulation of microcystins in the phytoplanktivorous silver carp (Hypophthalmichthys molitrix) stocked in Lake Taihu with dense toxic Microcystis blooms

The phytoplanktivorous silver carp is an important biomanipulation fish to control cyanobacterial blooms and is also a food fish with the greatest production in China. The accumulation of the hepatotoxic microcystins (MCs) determined by LC-MS in various organs of silver carp was studied monthly in Lake Taihu dominated by toxic Microcystis aeruginosa. Average recoveries of spiked fish samples were 78% for MC-RR and 81% for MC-LR. The highest content of MCs was found in the intestine (97.48 μg g^− 1 DW), followed by liver (6.84 μg g^− 1 DW), kidney (4.88 μg g^− 1 DW) and blood (1.54 μg g^− 1 DW), and the annual mean MC content was in the order of intestine > liver > kidney > blood > muscle > spleen > gallbladder > gill. Silver carp could effectively ingest toxic Microcystis cells (up to 84.4% of total phytoplankton in gut contents), but showed fast growth (from 141 g to 1759 g in 1 year in mean weight). Silver carp accumulated less microcystins in liver than other animals in the same site or other fish from different water bodies at similar level of toxin ingestion. There was possible inhibition of the transportation of the most toxic MC-LR across the gutwall. Muscle of silver carp in Lake Taihu should not be consumed during period of dense Microcystis blooms while viscera were risky for consumption in more months.     

室内模拟水华蓝藻对沉积物中Cd迁移释放的影响

室内模拟太湖沉积物中重金属Cd在蓝藻水华爆发时的迁移释放,通过研究水华蓝藻的主要藻种群铜绿微囊藻(Microcystis aeruginosa)的生长对沉积物-水界面环境条件(如pH值、溶解氧、氧化还原电位)和不同深度沉积物氧化还原电位的影响来进一步分析铜绿微囊藻爆发时对沉积物中Cd迁移释放的影响.结果表明,铜绿微囊藻生长影响了界面pH值和溶解氧条件,改变了不同深度沉积物中的氧化还原电位,提高了Cd从沉积物内部向水体系中扩散的速率,铜绿微囊藻能够吸附上覆水中的Cd进而影响Cd在沉积物-水界面的交换.