啶酰菌胺在斑马鱼体内的富集特性及其对SDH和复合物Ⅱ活性的抑制

为进一步探索啶酰菌胺对水生生物的毒性,选择斑马鱼为供试生物,采用半静态法,研究了啶酰菌胺在斑马鱼体内的富集与消除规律及对其肝脏和鳃的毒性作用。结果表明,斑马鱼暴露于0.08、0.32 mg·L~(-1)中,14 d后均达到富集平衡,28 d生物富集系数(BCF_(28 d))分别为35.50和36.72。在0.16、0.32 mg·L~(-1)浓度下,斑马鱼的比肝重(HSI)和比鳃重(BSI)均明显高于对照组,而肝脏和鳃中琥珀酸脱氢酶(SDH)和线粒体呼吸链复合物II活性均明显低于对照组,浓度低于0.08 mg·L~(-1)时,对斑马鱼无明显影响。由此可知,啶酰菌胺对斑马鱼为中等富集性,并对其肝脏和鳃有一定毒性作用。     

Biodegradable nanocomposites based on poly(butylene succinate)/organoclay

In this work, we try to incorporate the inorganic system into the biodegradable polymers to compose an organic/inorganic polymer hybrid. Various nanocomposites of poly(butylene succinates) (PBS) with different ratios of organically modified layered silicates (OMLS) prepared by solution blending were investigated. The OMLS used for the preparation of nanocomposites were functionalized ammonium salts modified montmorillonite. The effects of OMLS on the nanocomposites were investigated by XRD, TEM, DMA and TGA in the aspect of the d-spacing of clay, mechanical and thermal properties. Interestingly, all these nanocomposites exhibited improved properties when compared with the pristine PBS sample. XRD indicates that the layers of clay were intercalated by the modifiers, and the interlayer distance of organoclay in the nanocomposites could be extended to about 29.4 Å. Moreover, the thermal stability of the nanocomposites was enhanced by the addition of organoclay via TGA study, closely related to the organoclay content in the PBS matrix. DMA data shows that the storage and loss moduli were concurrently enhanced by the addition of organoclay as compared to the pristine PBS sample. Moreover, the glass transition temperatures also increased about 5 to 20 °C (from DMA, peak of tanδ) for the various organoclay-containing samples. The enhanced mechanical and thermal properties can be achieved from these organoclay modified-nanocomposites.     

Effect of Degree of Substitution of Octenyl Succinate Starch on Enzymatic Degradation

Octenyl succinate starch of degree of substitution (ds) 0.03, 0.07, and 0.11 was synthesized in an aqueous medium. These compounds were then tested for the susceptibility to enzymatic degradation. The multiple-enzyme regime of -amylase, amyloglucosidase, and pullulanase was chosen for the evaluation. This combination of enzymes had been proven to degrade 99.5% of unmodified starch to glucose and hence was chosen for this study. It was found that even small amounts of subsituent caused a considerable decrease in the extent of degradation. The net extent of degradation decreased with increasing ds. Surprisingly, the amount of glucose from all three substituted substrates was quite similar, suggesting the effect small amounts of subtituent had on the enzymatic activity.     

降解聚丁二酸丁二醇酯菌株的诱变选育及降解性能

诱变选育是基因资源开发的重要手段之一,为了对降解聚丁二酸丁二醇酯(PBS)菌株的降解性能进行改良,选择具有一定降解PBS能力的尖孢镰刀菌(Fusarium oxysporum)DSCF-8为出发菌株,分别研究了其在5种诱变途径下的突变效应及最佳诱变条件,测定了突变菌株D8B14在不同条件下的降解性能。结果表明,复合诱变途径的高效降解菌株获得率大于单因子诱变途径,分别达到了4.55%和1.30%,但突变株的降解特性遗传不稳定;硫酸二乙酯单因子诱变效应大于紫外线诱变和微波诱变,且得到的突变株较复合诱变得到的菌株具有更强的遗传稳定性,最佳诱变条件为5%的浓度处理40 min。硫酸二乙酯诱变得到的突变株D8B14传代稳定且降解性能优异,其对PBS薄膜的降解率较出发菌株提高了34.49%,粗酶液酶活性提高率为23.86%。该突变株在35℃条件下仍表现出较高的降解能力,对不同的初始pH条件亦具有更强的耐受能力,尤其在pH 4.0或pH 9.0的酸性和碱性条件下,降解率分别提高了13.26%和27.04%。     

PBS降解过程对植物发芽和生理特性的影响研究

采用青菜（Green vegetables）和生菜（Romaine lettuce）的种子发芽和室外盆栽实验,通过考察植物的种子发芽、生物量以及叶绿素质量浓度等指标,研究了可生物降解材料聚丁二酸丁二醇酯（PBS）对青菜和生菜发芽和生长过程中生理特性（植株地上鲜、干质量,地下鲜、干质量,株高,根长,叶片数,叶绿素质量浓度）的影响。研究结果表明：（1）土壤中加入PBS有利于青菜种子的发芽,较大幅度的提高了其发芽率、苗长、根长等,并且随着PBS质量分数的增加这种促进作用越发明显,PBS×100处理组的苗长和根长较空白对照组分别增长了12.9%和26.1%;（2）低质量分数的PBS对青菜和生菜的发芽、生长以及叶绿素的合成具有一定的促进作用,但是高质量分数的PBS则会产生轻微的抑制作用。     

聚丁二酸丁二醇酯生物降解酶及其催化性能研究

聚丁二酸丁二醇酯(PBS)在微生物存在条件下,可降解为低分子量的小分子。文章以实验室自行分离的、能有效降解PBS的菌株ZM-P1为出发菌株进行PBS的降解研究,对降解液中的解聚酶进行分离纯化,研究其生化性质及催化性能。研究结果表明:所得蛋白经过SDS-PAGE电泳鉴定为脂肪酶,该脂肪酶最适温度为60℃,在30~60℃内趋于稳定;其最适pH为9.0,pH 6~9范围内酶的活性稳定;Mg2+对该脂肪酶有较强的促进作用,Zn2+和Na+对该脂肪酶影响较小,Ca2+和EDTA对其有明显抑制作用。降解后PBS数均分子量与重均分子量下降,结晶颗粒减小,热稳定也有所下降,说明该菌株对PBS有较为明显的降解效果。     

Radiation Crosslinking of Poly(Butylene Succinate) in the Presence of Inorganic Material and Its Biodegradability

Three kinds of poly(butylene succinate)s (PBS) with different molecular weight were irradiated with electron beams in the presence of inorganic material. Fourteen kinds of inorganic materials were used in this work. The presence of inorganic material inside cross-linked PBS samples enhances the yield of gel formation. The heat stabilities of PBS samples were checked; it was found that silicon dioxide and carbon black significantly improve these properties. Enzymatic and soil burial tests were performed; the presence of these inorganic materials in cross-linked PBS accelerates the rate of biodegradation.     

碲化镉量子点对小鼠肝脏超微结构及重要生物酶活性的影响

探讨了碲化镉量子点(cadmium telluride quantum dots,CdTeQDs)对小鼠肝组织超微结构及琥珀酸脱氢酶(succinate dehydrogenase,SDH)和三磷酸腺苷酶(adenosine triphosphatase,ATPase)活性的影响。将20只雄性ICR小鼠随机分成QDs染毒组和对照组,采用尾静脉注射方式进行一次性染毒,染毒组每只小鼠注射2μmol·kg-1体重的CdTeQDs(以Cd~(2+)的摩尔浓度计算)。每5只为一组分别在染毒后的1 d、3 d和7 d处死小鼠,另外5只注射生理盐水作为对照组。取部分肝组织在透射电镜下观察其超微结构变化并使用试剂盒测定肝脏中SDH、Na~+/K~+-ATP酶、Ca~(~(2+))/Mg~(2+)-ATP酶的活性。结果显示CdTeQDs暴露后染毒组小鼠肝细胞胞浆疏松,线粒体出现肿胀、空泡、嵴减少等结构变化,表明肝细胞受到损伤且染毒1 d后损伤最严重;肝脏中染毒组SDH活性与对照组相比显著降低(P0.05);染毒1 d后,Na~+/K~+-ATP酶和Ca~(2+)/Mg~(2+)-ATP酶活性与对照组相比显著升高,随着染毒后时间的延长,其活性呈现下降的变化趋势。单次量注射CdTeQDs能够引起小鼠肝脏损伤,抑制SDH活性,引起ATP酶活性改变,这些症状在暴露时间内呈现恢复趋势。     

不同相对分子质量PBS基共聚物的降解产物对土壤微生物的影响研究

以陕西花园土为供试土样,采用室内模拟实验,在土壤中加入一定量的聚丁二酸丁二醇酯（PBS）,研究不同数均相对分子质量的PBS（Mn分别为3.46×103、8.13×103、1.60×104、3.50×104）对土壤呼吸强度,微生物（细菌（bacteria）、真菌（fungi）、放线菌（actinomycetes））数量的影响,以此来探讨PBS降解产物对土壤微生物生理特性的影响。研究结果表明：①相对分子质量为3.46×103和8.13×103的PBS在其质量分数较低时有利于土壤呼吸强度的增加,有利于细菌的生长,最大增长幅度达到40%,在其质量分数较高时有利于真菌生长,最大增长幅度达到500%。②相对分子质量为1.60×104和3.00×104的PBS随着PBS质量分数的升高,对土壤呼吸强度和微生物数量的促进作用相应增加,对土壤呼吸强度的提高幅度最大达11.6%,对真菌的提高幅度达178%。