乳源蜡样芽胞杆菌耐药性、毒力因子检测及分子特征研究

为了解乳品来源蜡样芽胞杆菌携带的毒力因子、分子特征及耐药性,对2016—2019年分离自乳品的122株蜡样芽胞杆菌,采用纸片扩散法（K-B纸片法）测定了分离株对氯霉素、庆大霉素等9种抗生素的耐药性,使用聚合酶链式反应法检测了菌株携带的毒力因子,同时采用脉冲场凝胶电泳（pulsed field gel electrophoresis,PFGE）检测分离株的分子特征。结果表明,122株蜡样芽胞杆菌均对氯霉素、庆大霉素、阿米卡星敏感;对红霉素、克林霉素和环丙沙星的中介率分别为5.74%、4.92%和0.82%, 9.84%的菌株对复方新诺明具有耐药性,8.20%的菌株对四环素具有耐药性,4.10%的菌株对利福平具有耐药性。122株蜡样芽孢杆菌都检出了蜡样芽孢杆菌的非溶血型肠毒素基因nheA、nheB及肠毒素FM基因entFM;nheC、bceT、cytK、hblA、hblC、hblD、ces和EM1基因的检出率分别为99.18%、37.70%、31.15%、29.51%、24.59%、8.20%、、6.56%和6.56%。122株蜡样芽胞杆菌被分成15簇,未见明显的优势带型。由此可见,2016—2019年收集的蜡样芽胞杆菌乳品分离株携带多种毒力基因,约10%的菌株对复方新诺明、四环素、利福平等具有耐药性,PFGE呈现多种带型,为蜡样芽孢杆菌引起的食源性疾病的预警、预防和治疗提供参考。     

日粮中裂殖壶藻渣对多鳞白甲鱼生长、脂代谢及健康的影响

本研究旨在探究裂殖壶藻渣作为饲料原料对土著鱼类多鳞白甲鱼的生长性能、脂质代谢及健康状况的影响。在五种等氮等脂饲料中分别添加0g/kg(DS0)、30g/kg(DS3)、60g/kg(DS6)、90g/kg(DS9)和120g/kg(DS12)的裂殖壶藻渣,饲喂养殖于室内循环水系统的180尾多鳞白甲鱼（9.00g±0.25g/尾,12尾/缸）56天。结果显示：（1）增重率(WG)、特定生长率(SGR)及饲料系数(FCR)在各组间无显著差异(P>0.05);（2）DS9组和DS12组的肥满度(CF)、肝体比(HSI)、腹脂指数(IFI)、肝脏和腹脂甘油三脂(TG)含量均显著低于对照组(P<0.05);（3）DS6、DS9和DS12组肌肉中DHA含量、∑n-3 LC PUFA（N-3长链多不饱和脂肪酸）含量、n-3/n-6 PUFA比例、胆固醇血症指数(h/H)和血脂质量指数(FLQ)显著高于对照组,而动脉粥样硬化指数(AI)和血栓形成指数(TI)均显著低于对照组(P<0.05);（4）所有处理组肝脏的脂肪酸合成酶(FAS)和乙酰辅酶A羧化酶1(ACC1)的mRNA表达水平显著低于对照组(P<0.05);DS6、DS9和DS12组腹腔脂肪组织的乙酰辅酶A羧化酶2(ACC2)和甘油三酯水解酶(ATGL)的mRNA表达水平显著高于对照组(P<0.05)。（5）所有处理组血清中超氧化物歧化酶(SOD)活性显著高于对照组,丙二醛(MDA)含量显著低于对照组(P<0.05)。研究表明,在日粮中添加90g/ kg的裂殖壶藻渣可能通过影响脂代谢相关基因的表达显著降低多鳞白甲鱼腹腔脂肪和肝脏脂肪蓄积,并提升其肌肉营养价值,增强机体抗氧化能力。     

Active metabolism in larval and juvenile fish: ontogenetic changes,effect of water temperature and fasting

Oxygen consumption, ammonia excretion and fish swimming speed were measured in fish induced to swim by optomotor reaction in a circular metabolism chamber. The relationship between the swimming speed and fish metabolism described by exponential equations allowed the extrapolation to the standard metabolism, i.e. at zero swimming speed. The partitioning of the catabolised protein in the energy supply was estimated based on AQ (volume of ammonia/ volume of oxygen) values. Weight specific standard metabolism, as expressed by the ammonia excretion rate, decreased by one order of magnitude in coregonids as the fish grew from 20 to 780 mg body weight. The slope of the relationship between oxygen uptake and swimming speed decreased in coregonid ontogenesis. In salmon, after 12 days of fasting 28% of energy used was derived from protein, whilst coregonid juveniles utilized mostly lipid. Active swimming in fasted juveniles of coregonid, as well as in salmon, led to the accelerated utilization of protein as a source of energy, based on AQ coefficients. In juveniles acclimated to a range of water temperatures from 14 to 26°C, the changes in standard or active metabolic rate (expressed as oxygen uptake or ammonia excretion) were described by Q₁₀ coefficients. They were generally higher for the ammonia excretion rate than for the oxygen uptake rate and for active metabolism than for standard metabolism. Utilization of protein as energy for swimming differed significantly between the species, being in general one order of magnitude higher in coregonids than in salmon. The use of protein for swimming activity tended to decrease during coregonid ontogenesis.     

Bacillus subtilis CK3 used as an aquatic additive probiotics enhanced the immune response of crayfish Procambarus clarkii against newly identified Aeromonas veronii pathogen

To identify the aetiology of the disease outbreak in cultured Procambarus clarkii, a dominant bacteria strain from the diseased crayfish hepatopancreas was isolated. It was identified as Aeromonas veronii based on biochemical identification and 16S rDNA sequencing. The symptoms of artificially infected crayfish were similar to those of naturally infected P. clarkii. The A. veronii was sensitive to norfloxacin, ciprofloxacin, ceftazidime, cefuroxime and ceftriaxone antibiotics, while resistant to penicillin, ampicillin, oxacillin and piperacillin. Virulence genes such as the enterotoxin genes (act, alt and ast) and haemolytic toxin genes (hlyA and aerA) were detected. After A. veronii infection, the connections between some liver tubules disappeared, the vacuoles appeared in the brush border and the mitochondria were enlarged. The antagonistic action of previous identified B. subtilis CK3 against A. veronii was also detected. The supernatant of B. subtilis CK3 exhibits a significant bactericidal effect on A. veronii. After B. subtilis CK3 immersion, the antioxidant enzymes and immune-related enzyme activities in hepatopancreas were significantly higher than control. The accumulative mortality caused by infection of A. veronii can be significantly reduced by adding B. subtilis CK3 into the aquatic water. These results demonstrated that B. subtilis CK3 could act as a water additive to improve the immune response of P. clarkii against newly identified A. veronii. The present study will provide a new way for the prevention and control of crayfish bacterial diseases and also provide technical support for the healthy cultivation of P. clarkii.     

青蟹的营养需求研究及其配合饲料研制

青蟹属（Scylla）有锯缘青蟹（Scylla serrata），拟穴青蟹（S．paramamosain），紫螯青蟹（S．tranquebarica）和榄绿青蟹（S．olivacea）等4个种。我国以拟穴青蟹占绝对优势，它有个体大、生长快、适应性强、肉味鲜美、营养丰富等特点，已成为具有重要经济价值的海水养殖蟹类之一。     

粘帚霉对几种水生生物有害菌的抑制作用测定

采用对峙培养法测定了粘帚霉16株菌株对嗜水气单胞菌、耶耳森菌、鳗弧菌、褐藻酸降解菌-MA10和褐藻酸降解菌-MB16的作用。试验结果表明,粘帚霉中NCH-3-1、YJS-3-2、GJ-1-1、SS-1-1、SHW-2-1、SHW-1-1、BD-2-2 7株菌株对供试的5种有害菌表现出较强的抑制作用。     

罗非鱼鱼种肠炎病的病理组织学及病原体的研究

本文从病理组织学的角度,研究了罗非鱼鱼种肠炎病的发生与发展,为其诊断与防治奠定了理论基础。结果表明,该病病原体为产气单胞菌。     

灵芝活性成分的研究进展

灵芝活性成分复杂,其主要的生理活性物质有多糖类、三萜类、免疫调节蛋白类、凝集素类、核苷类、甾醇类、生物碱类和微量元素等,具有抗肿瘤、抗氧化、调节免疫、降血糖、降血脂、抗病毒、消炎抗菌等功效,因此,对其活性成分的研究具有重要意义。现对灵芝的主要活性成分及其生物活性的国内外研究现状进行综述,为灵芝产品的进一步开发利用提供理论依据。     

杨树烂皮型、水泡型溃疡病的药剂防治试验

以相关文献中药剂抑菌试验的结果为参考,选用7种常见杀菌剂,在天津汉沽地区针对烂皮型溃疡病较重的毛白杨和水泡型溃疡病较重的107杨开展药剂防治试验,防治前后分别进行病情调查,并对调查结果和防治成本进行了统计分析。防效分析结果表明:腐烂净(腐殖酸铜)、轮腐净(甲硫·福美胂)对烂皮型溃疡病防效最好,病情抑制率依次为75.33%,70.89%,且二者防效无显著差异(P0.05);80%多菌灵可湿性粉剂和轮腐净(甲硫·福美胂)对水泡型溃疡病防效最好,病情抑制率依次为72.00%,68.44%,且二者防效无显著差异(P0.05)。防治成本分析表明:不包含病斑刮除的人工费用(80元·百株-1),腐烂净(腐殖酸铜)和轮腐净(甲硫·福美胂)成本最低,分别为44.6元·百株-1和51.5元·百株-1,80%多菌灵可湿性粉剂成本较高,达到73.5元·百株-1。综合考虑防治效果和经济效益,轮腐净(甲硫·福美胂)是防治两种类型溃疡病的最优选择。     

乳酸杆菌L1对致病弧菌的抑制作用

以致病弧菌T1、T2为检测菌,采用平板抑菌圈检测法,研究乳酸杆菌L1及其代谢产物的抑菌能力。结果表明:L1发酵上清液对两种弧菌的抑制效果和发酵液对弧菌的抑菌作用相似,即对弧菌T1的抑制作用强于T2;L1 发酵液对弧菌T1、T2的抑制能力强于上清液,表明乳酸杆菌及其代谢物质对弧菌具有协同抑制作用;L1的发酵液经3倍稀释仍对弧菌T1有抑制作用;乳酸杆菌L1生长不同时期的代谢产物对弧菌的抑菌活性不同,代谢产物的抑菌能力在衰退期>稳定期>生长期;L1的发酵液经沸水浴处理15 min其抑菌活性不变,表明抑菌代谢物质具有较好的耐热性。