改变凋落物和根系输入对米槠天然林土壤微生物群落的影响

伴随气候变化下亚热带地区米槠天然林净初级生产力变化,凋落物以及植物根系输入亦会发生改变,这将显著影响土壤微生物群落。于2019年7月在设置7年的米槠天然林植物残体添加和去除试验（the detritus input and removal treatments,DIRT）样地采集不同处理（对照、去除地上凋落物、去除地下根系、无凋落物输入、添加双倍地上凋落物）的2个土层土壤（0—10,10—20 cm）,测定微生物磷脂脂肪酸（phospholipid fatty acid,PLFA）含量,计算各微生物群落比值以及多样性,进一步揭示凋落物和植物根系输入对亚热带米槠天然林土壤微生物群落组成和多样性的影响。结果表明：（1）不同处理下0—10 cm土层微生物磷脂脂肪酸含量约为10—20 cm土层的2倍;（2）地上凋落物变化均使得革兰氏阳性菌、阴性菌及放线菌等细菌含量出现不同程度的下降,但不会对丛枝菌根等真菌含量产生影响,而去除根系处理显著降低丛枝菌根真菌含量;（3）微生物群落Shannon-wiener、Simpson多样性指数不受凋落物输入的影响,凋落物去除降低表层土壤微生物群落的Margalef丰富度,提高Pielou均匀度,表明0—10 cm土层微生物群落含量与分布状况受凋落物输入变化影响较大;（4）地下植物根系存在可提高真菌（如丛枝菌根真菌）含量,而地上凋落物输入主要改变细菌丰度以及群落结构。可溶性有机碳以及矿质氮是影响不同处理土壤微生物群落组成和多样性的主要因素。可见,凋落物和根系输入通过土壤理化性质的变化而影响了微生物群落,研究结果可为全面认识植物、土壤与微生物间的相互作用对森林生产力的影响提供科学依据。     

Influences of past application rates of nitrogen and a catch crop on soil microbial communities between an intensive rotation

The aim of this study was to investigate influences of six-year past application rates of nitrogen and a catch crop, sweet corn (Zea mays L. ssp. Saccharata Sturt), on soil microbial community and diversity in a greenhouse-based intensive vegetable soil in eastern China. Soil electrical conductivity, pH, mineral nitrogen, phospholipid fatty acids (PLFA) profiles and carbon source utilization patterns under five annually past nitrogen rates (0, 348, 522, 696 and 870?kg?nitrogen?ha^?1) were evaluated after the establishment of sweet corn during 1–1.5-month fallow period over three-year tomato/cucumber/celery rotations. The past nitrogen application rates exerted significant effects on soil electrical conductivity, pH, nitrate-nitrogen, ammonium-nitrogen and carbon source utilization patterns, but not on PLFAs profiles. The sweet corn had a significant effect on soil chemical properties, total and actinobacterial PLFAs, but not on carbon source utilization patterns. Soil electrical conductivity, nitrate-nitrogen and the total PLFAs decreased whilst soil organic carbon, pH and the actinobacterial PLFAs increased after the establishment of sweet corn. Soil microbial functional diversity from carbon source utilization patterns and actinobacterial PLFAs were greatest after the establishment of sweet corn at a 60% of the conventional nitrogen rate (i.e. 522?kg?nitrogen?ha^?1). Soil electrical conductivity and ammonium-nitrogen were two key factors to determine carbon source utilization patterns, whilst soil pH was the key factor to determine PLFAs profiles. A combination of the catch crop sweet corn during summer fallow and a 60% of the conventional nitrogen rate is a sustainable pathway of utilizing greenhouse-based intensive vegetable soils in eastern China.     

磷脂对奶牛产奶性能及乳成分的影响

本实验选用14头年龄、胎次、产奶量、乳成分基本一致的奶牛,分为对照组和试验组。试验组奶牛日粮用未经包被处理的大豆磷脂替代玉米(占日粮2%),预饲10天后,测定此后48天内每天每头的产奶量,并定期检测乳脂率,乳蛋白。结果发现:试验组比对照组产奶量增加0.9kg/天.头,乳脂率及乳蛋白上下变化不大,统计检验差异均不显著(P>0.05)。     

潜流式人工湿地消纳城市污水厂尾水微生物特性及机制

为揭示潜流式人工湿地消纳城市污水厂尾水微生物特性及机制,以位于常州市城北污水处理厂内的潜流式人工湿地消纳城市污水厂尾水旁路试验系统中的植物根系、湿地填料及湿地土壤中微生物为研究对象,通过镜检、脲酶、磷脂脂肪酸（PLFA）等分析手段对其进行相关研究。结果表明,植物根系、填料中含有团藻等菌胶团和轮虫、变形虫等原生动物,团藻等菌胶团通过自身新陈代谢及光合作用,利用尾水中N、P进行生物代谢,去除低碳源条件下尾水中的N、P等。湿地脲酶平均含量（N）约为22.43 mg/g,其活性与TN的去除呈线性相关,活性越高,TN去除率越高。消纳城市污水厂尾水湿地填料中饱和脂肪酸（PLFA）含量为99.30%,不饱和脂肪酸含量仅为0.70%,这与潜流式人工湿地处理城市污水中的PLFA含量有很大差别（分别为76.97%、23.03%）。以脂肪酸生物标记量为指标,显示湿地填料中形成了以好养细菌为优势种群的微生物生态结构。团藻、好氧微生物是低碳源尾水中TN等污染物去除的主要载体微生物。     

典型农田土壤的磷脂脂肪酸分析方法的比较

以湖北省武穴市典型农田土壤为研究对象,对现有的磷脂脂肪酸(PLFA)提取方法加以改进,分别通过设置不同甲醇萃取时间、不同土壤样品量梯度以及不同正己烷溶解量梯度以确定磷脂脂肪酸提取过程中的甲醇萃取效率、最适土样量和最适溶解量。试验发现,甲醇开始萃取得到的待测样品即为目标样品,用于PLFA提取的武穴典型农田土壤最适提取量为2g,用250μL正己烷溶解的待测样品经检测能够得到有效完整的磷脂脂肪酸数据。为验证改进后的磷脂脂肪酸提取方法的效果,进一步分析了武穴地区种植不同农作物(一季稻、双季稻和油菜)的农田土壤微生物组成,结果表明,该方法的稳定性和重复性良好,能够反映武穴地区典型农田土壤的微生物群落结构。     

Lipid class composition of benthic-pelagic fishes (Cottocomephorus, Cottoidei) from Lake Baikal

A study was made of the lipid class composition in liver, gonads and red and white muscles of two endemic Baikal fish species Cottocomephorus grewingki and Cottocomephorus inermis. The main lipid classes were triacylglycerols and phospholipids. The highest levels of triacylglycerol (81.8%) were found in the liver of C. inermis males, and of phospholipid (38.3%) – in males testes of both species. The main phospholipid classes were phosphatidylcholine and phosphatidylethanolamine, which varied in examined organs and tissues in both fish species from 44.3 to 78.7%, and from 16.8 to 42.1%, respectively.     

鱼虾需要的脂肪酸、胆固醇和磷脂

脂类的脂肪酸,类脂质的胆固醇和磷脂,有的可由鱼虾机体生物合成,有的则不能或合成量远远达不到不能满足鱼虾在发育生长阶段的需要。由此而产生的缺乏症,严重影响幼龄期鱼虾的生存和生长。改善鱼虾对脂肪酸、胆固醇和磷脂的需求,是用提高外源性营养水平的办法。因此,认识脂肪酸、胆固醇和磷脂在鱼虾生命活动中的生理功能、缺乏症和需要量,对制定鱼虾的饲料标准和提高鱼虾的生存率、生长率都有十分重要的意义。     

套种棘托竹荪对毛竹林土壤理化性质、磷脂脂肪酸特性和酶活性的影响

对套种棘托竹荪(Dictyophora echinovolvata)毛竹(Phyllostachys heterocycla cv.pubescens)林土壤理化性质、土壤磷脂脂肪酸特性及其土壤酶活性进行了研究.结果表明:相比未套种林分毛竹林套种棘托竹荪能显著增加土壤有机质含量(P＜0.05),土壤pH值提高了4.97％;显著提高了全氮、速效氮、全磷的含量,增加了钾的活性(P＜0.05);微生物群落结构存在差异,套种显著提高了土壤总PLFA、细菌和真菌的含量(P＜0.05),细菌/真菌比值有所下降;脲酶、蔗糖酶、蛋白酶、氧化氢酶、磷酸酶的活性显著升高(P＜0.05),分别比未套种提高了58.33％、50.00％、21.43％、19.12％、5.43％.     

Characteristics of soil microbial biomass and community composition in Pinus yunnanensis var. Tenuifolia secondary forests

Pinus yunnanensis var. Tenuifolia is an important species of timber and grease in southern China, but the characteristics of the soil microbial community in P. yunnanensis var. natural secondary forests are still poorly understood. Using a fumigation-extraction method and phospholipid fatty acid (PLFA) analysis, we study microbial biomass and community composition in the topsoil (0–10 cm) of three types of secondary forests (PYI, PYII, PYIII) dominated by P. yunnanensis var. to varing degrees. Microbial biomass carbon and nitrogen, total PLFA, and PLFA contents of bacterial, fungal, and arbuscular mycorrhizal fungi were significantly lower in PYI than PYII or PYIII, and there were significant differences in the monounsaturated/saturated fatty acid ratio among the tested forests. Principal component analysis indicated that the soil microbial community structure of the tested forests differed significantly. The changes in soil microbial biomass and community composition were positively correlated with soil water content, pH, organic matter (SOM), total nitrogen (TN), and total phosphorus. Season did not significantly affect the soil microbial community structure, but significantly affected soil microbial biomass, SOM, and TN, which were higher in the dry season than in the wet season.     

复合维生素脂质体的制备

以大豆粉末磷脂为壁材,以盐酸硫胺素（维生素B1）、核黄素（维生素B2）、盐酸吡哆醇（维生素B 6）、叶酸、烟酰胺的混合物为芯材,采用冷冻干燥-粉碎-筛分工艺,制备了复合维生素脂质体,考察了壁材/芯材比对脂质体中维生素荷载量及包埋率的影响。结果表明,随着壁材/芯材比的增加,维生素的包埋率增加而荷载量降低,比较合适的壁材/芯材比为15:1（w/w）。