Dietary intake of probiotics and maslinic acid in juvenile dentex (Dentex dentex L.): effects on growth performance, survival and liver proteolytic activities

Two feeding trials were carried out to evaluate the efficiency of probiotics and maslinic acid, on growth and survival of juvenile dentex; liver proteolytic activities were also investigated in the second trial. For experiment 1, triplicate groups were fed six diets with two probiotics (Bacillus toyoi, T, and B. cereus, E) at increasing levels (0.5, 1 and 2 g kg^?1 diet) and a control diet. Growth and feed conversion were not significantly influenced by the probiotics. The diet T1 produced the lower mortality, whereas diet E1 rendered the higher mortality. It was concluded that no significant effects on growth and survival were found following the addition of two kinds of probiotics to dentex diets. However, the diet E0.5 showed a tendency to ameliorate the growth and feed utilization of the diet. In a second trial, triplicate groups were fed four diets with increasing levels of maslinic acid (0, 20, 40 and 80 mg kg^?1 diet). Growth of fish given diets with the highest level of maslinic acid (D80) was slightly but not significantly lower than those from the other groups. Furthemore, mortality of fish fed diet D40 was the lowest. Changes in liver proteasome and endoprotease activities measured on sodium dodecyl sulphate (SDS)/gelatin gels were also detected in a dose‐dependent manner. It was concluded that a dietary maslinic acid at a level of 80 mg kg^?1 diet seems to be too high for juvenile dentex to maintain a maximal growth and survival rate.     

山姜对益生芽孢杆菌体外抑菌活性试验研究

为研究中草药山姜粗提液对益生芽孢杆菌体外抑菌效果,特采用试管二倍稀释法和管碟法检测不同浓度的山姜煎煮液和乙醇提取液在体外对蜡样芽孢杆菌PAS38菌株和枯草芽孢杆菌Pab04菌株的最小抑菌浓度(MIC)和抑菌直径,并以肠毒性大肠杆菌(ETEC)、4μg/mL硫酸庆大霉素作阳性对照,生理盐水作阴性对照。结果表明,山姜煎煮液和乙醇提取液对两株益生芽孢杆菌和ETEC无抑菌作用,硫酸庆大霉素对蜡样芽孢杆菌PAS38和枯草芽孢杆菌Pab04菌株MIC均为1.25μg/mL,对ETEC的最低抑菌浓度MIC为0.625μg/mL。山姜煎煮液和乙醇提取液对受试菌株抑菌直径与生理盐水相比差异不显著(P>0.05),硫酸庆大霉素与其相比差异极显著(P<0.01)。山姜粗提液对两株益生芽孢杆菌无明显抑菌作用。     

防治十字花科作物根肿病的油菜内生细菌分离与鉴定

为探寻对十字花科根肿病有生防作用的菌株,本文从油菜根内组织分离内生细菌,通过根肿菌孢子裂解、盆栽防病试验证明其功能,并经形态学、生理生化和16S RNA基因序列鉴定其分类地位。研究结果表明,从油菜品种KT1004和Y05-84-5-1根部分离出51株内生菌,其中YN201305和YN201310对十字花科根肿病菌有明显裂解和抑制作用。盆栽试验表明,应用浓度107 CFU/mL的菌液,在播种时和播种后间隔5d,浇灌1次,共浇灌4次。45d苗龄调查结果,二者对大白菜品种鸿源83的根肿病防治效果分别达65.12%和77.92%。经鉴定,YN201305为短小芽孢杆菌,YN201310为枯草芽孢杆菌。     

Coupled magnetic nanoparticle-mediated isolation and single-cell image recognition to detect Bacillus' cell size in soil

Microbial morphology fundamentally constrains how species interact with their environment, and hence ultimately affects their niche. However, the methodology of functional microbes in the soil ecosystem is still poorly studied since it is difficult to capture and identify the active monospecific community from the complicated environment and enormous number of microbial species in soils. To comprehensively reveal the morphology of active microbes in soil ecosystem, magnetic nanoparticle-mediated isolation (MMI) and single-cell image recognition (SCIR) were employed to study soil active Bacillus community, which functionally boosted the soil fertility in organic fertilisation compared to mineral fertilisation and unfertilised control treatments in our previous study. The results showed that MMI and SCIR can efficiently isolate active Bacillus from soil particles and other microorganisms. High throughput sequencing showed that the captured Bacillus showed similar community structure in different long-term fertilisation soils, while SCIR revealed that the active Bacillus was greater in number and larger in size in organic fertilisation treatment compared to mineral fertilisation and unfertilised control treatments. Our study demonstrates that the combination of MMI and SCIR is a potentially powerful tool to capture and identify the morphology of active and functional microbes in the soil ecosystem.     

耐铜菌株TLSB2-K的鉴定及其铜富集能力测定

[目的]研究菌株TLSB2-K的铜耐性以及其铜富集能力的特性.[方法]通过形态观察、革兰氏染色和16S rDNA序列比对,对前期分离的菌株TLSB2-K进行了鉴定,并采用振荡培养法,探讨了温度、pH值和渗透压对菌株生长的影响,以及铜胁迫下菌株对铜的耐性及富集能力.[结果]TLSB2-K属于蜡样芽孢杆菌(Bacillus cereus),最适生长条件为:温度为27℃、pH值为7、渗透压为1.1％ NaC1.铜浓度100～500 mg/L范围内,菌体生长良好,铜浓度在100～400 mg/L范围内,菌体铜含量随着铜浓度的升高而增加,当铜浓度400 mg/L胁迫培养30 h,菌体铜含量达到最大值2 250mg/kg;菌株的最高铜耐受浓度为700 mg/L.[结论]菌株TLSB2-K具有较强的铜耐性和较高的铜富集能力,具有重要的理论研究和工程应用价值.     

New Extracellular Bacillus subtilis Lectins with Sialic Acid-Specificity

The purpose of this work is to perform a detailed study of carbohydrate specificity of the new extracellular bacilli lectins which is considered to determine mechanisms of the lectins action. Sources of lectins were bacterial strains from Ukrainian collection of microorganisms. The optimized protocol of bacilli lectins isolation and purification included precipitation with ammonium sulfate with subsequent gel filtration chromatography on Sepharose CL-6B. Hemagglutinating activity of bacilli lectins and their fine carbohydrate specificity to sialic acids and their derivatives as well as sialic asid-containing and asialic glycoconjugates were studied. The ability of extracellular bacilli lectins to discriminate a- and 13-conformation of carbohydrate molecule and the type of connection between the monomers was determined. Studied lectins showed the most affinity to glycoconjugates containing both types of sialic acids （N-acetylneuraminic acid （Neu5Ac） and N-glycolylneuraminic acid （NeuGc）） and it is supposed to be a basis of their diagnostic and analytical potential.     

产挥发性物质芽胞杆菌对枇杷炭疽病菌的抑制作用及其鉴定

采用二分隔特殊平板研究芽胞杆菌挥发性物质对枇杷炭疽病菌Colletotrichum acutatum的抑制作用。研究结果表明,筛选得到的8株芽胞杆菌菌株中,抑菌效果最好的菌株为FJA T-4748,抑菌率达90.06％;其次为FJAT-10011,抑菌率达54.99％。经16S rDNA序列鉴定结合菌落形态观察,确认这8株芽胞杆菌分别为解木糖赖氨酸芽胞杆菌 Lysinibacillus xylanilyticus、波茨坦短芽胞杆菌 Brevibacillus borstelensis、短短芽胞杆菌Brevibacillus brevis、土壤短芽胞杆菌 Brevibacillus agri、阿氏芽胞杆菌 Bacillus aryabhattai、美丽短芽胞杆菌Brevibacillus formosus及简单芽胞杆菌Bacillus simplex。本研究筛选的产挥发性物质芽胞杆菌菌株可为枇杷采后炭疽病的生物防治提供菌株参考。     

香蕉枯萎病拮抗菌株BS11抗真菌活性物质的研究

[目的]对枯草芽孢杆菌BS11抗真菌活性物质进行研究,为该菌株的进一步开发应用提供参考。[方法]比较了枯草芽孢杆菌BS11在LB和NB培养基上的生长情况,比较了3种方法提取该菌株活性物质的效果,并探讨了该菌株的最佳培养条件。[结果]以香蕉枯萎病菌为指示菌,发现拮抗菌在LB和NA 2种不同培养基中有很明显的差别,LB培养基中生长繁殖速度快,但上清液活性很低,NA培养基中繁殖速度较慢,上清液活性却较好;乙醇沉淀法和乙酸乙酯萃取法均不能提取到活性物质,硫酸铵沉淀法基本上可将活性物质提取出来;BS11最佳的培养条件为初始p H7,温度30℃,通气量60 ml;发酵上清液有蛋白酶、纤维素酶活性,但没有几丁质酶活性。[结论]枯草芽孢杆菌BS11株所产的抗真菌活性物质具有性质稳定、广谱、易于提取等优点,为其应用于植物病害防治提供了理论依据。     

Bacillus subtilis PTS-394对番茄根系及根围微生态的影响

为了明确枯草芽孢杆菌(Bacillus subtilis)PTS-394对番茄根系及根围微生态的影响,本研究采用生理生化方法测定了番茄根系活力和根围土壤酶活性,并测定了番茄根冠比及根系周围可培养微生物的数量。结果表明,枯草芽孢杆菌PTS-394能够显著促进番茄根系生长,促进生长率达25%;同时PTS-394还能够提高根系活力,在PTS-394处理后第12 h、24 h,根系活力均比对照显著增高,增高比例分别为17.0%和25.6%,随后根系活力和对照基本持平并保持一致。枯草芽孢杆菌PTS-394的施用对番茄根围土壤中的放线菌具有显著的促进作用,对真菌具有轻微的抑制作用,而对细菌则无明显作用。此外,PTS-394能够促进番茄根围土壤脲酶和土壤蔗糖酶的活性,但其对2种酶的作用均有时效性,其影响会随着时间的变化而逐渐减弱。