优化氮源种类及碳氮比对阿魏菇液体种生长的效应

[目的]阿魏菇液体培养过程中氮源种类及碳氮比的优化研究,为阿魏菇生理活性物质代谢、分析与提取提供技术保障,同时为野生菌种质资源的保护、菌株保存和驯化提供方法.[方法]选择6种有机氮源、2种无机氮源以及8个碳氮比梯度,采用液体培养技术通过菌球直径、菌球密度、菌丝生长量等生物量指标测定,反映阿魏菇液体培养的氮代谢特性.[结果]不同氮源种类及浓度显著或极显著影响了阿魏菇液体种的生长.黄豆、黄豆芽是阿魏菇液体种培育的良好氮源,菌球密度分别达到26.67;和24.00;,是对照的145;和131;.其次是蛋白胨、酵母片,甘氨酸与硫酸铵、硝酸钾之间差异不显著,尿素是最差的氮源.2.5;黄豆芽和黄豆均可以获得阿魏菇液体种最高的生物量,是可以取代蛋白胨的有机氮源.适宜阿魏菇液体种生长的碳氮比是20∶1.[结论]阿魏菇液体种培养过程中存在氮源的选择性差异,天然有机氮源优于其他形式的各种氮源,同时氮源浓度的变化极显著影响了液体种的生产能力,阿魏菇液体种培育过程中对氮源浓度的要求相对较高.     

城市绿化植物减噪研究进展

绿化植物不仅具有美化和改善人居环境的作用, 还具有重要的减噪功能。文中从绿化植物减噪机理、减噪效果及影响因素等方面进行综述, 提出了绿化防噪设计时的3点建议和将来开展绿化植物减噪研究的重点。     

基于模型的上海郊区地下水氮素非点源污染特征研究

农业非点源污染是造成上海郊区地下水污染的主要因素,定量分析预测农业生产过程氮素的迁移转化规律是有效控制地下水污染的重要环节。以上海市浦东新区新场镇果园村的桃园为研究对象,借助生物地球化学过程模型(DNDC)和长期水文影响评价模型(L-THIA),基于连续观测数据,详细分析了农业生产过程中氮素造成的非点源污染,特别是对周边地表、地下水的影响。结果表明,地表水总氮均值达6.34mg·L-1,远劣于地表水Ⅴ类标准(≤2.0mg·L-1);地下水中总氮均值达16.85mg·L-1,远劣于地表水Ⅴ类标准(≤2.0mg·L-1)。约有20%采样点硝态氮含量属于地下水Ⅴ类(>30mg·L-1)。野外检测数据表明,该区地表水、地下水污染均严重超标,不宜饮用。模型分析显示,水体污染源主要来自桃园生产中施用的肥料,其中就模拟结果的数值可以得出,大约年农田氮输入量的1.7%通过土壤径流进入地表水,约3.5%经过土壤渗漏进入地下水,实测地下水中氮含量占桃园总氮输入量的5.8%。因此,合理调整施肥措施和施肥结构是减少土壤-水体中氮素污染的有效途径。     

天津大沽排水河沉积物典型持久性有机污染物的分布特征与来源解析

分别使用气相色谱质谱仪和气相色谱仪对2010年5月采集的天津市大沽排水河8个沉积物样的16种多环芳烃(PAHs)和7种有机氯农药(OCPs)进行了调查,结果表明,沉积物中PAHs的总含量范围为370～5607ng·g-1,平均浓度为2041ng·g-1,OCPs的总含量范围为42.2～680ng·g-1,平均浓度为222ng·g-1。对其组成特征及来源进行了分析,结果表明,沉积物中PAHs主要以3～4环为主,5～6环较少,沉积物中PAHs主要来自化石燃料的燃烧或交通源贡献,以及少量石油产品的输入。滴滴涕(DDT)及其代谢产物的含量明显低于林丹类物质(HCHs),HCHs有新的输入,DDT没有新的输入,其降解方式主要是厌氧降解。     

烟草香气物质来源

综述了烟草香气物质来源的主要途径,包括种植产生的物质基础,加工中香味前体物的降解,香精香料的添加和燃烧的反应产物.     

蔬菜农药残留问题分析及控制对策

介绍了当前蔬菜农药残留的主要来源及类型,探讨了蔬菜中农药残留对人畜和环境的危害,分析了蔬菜农药残留超标的根本原因,并提出了降低农药残留的对策,以提高农产品质量安全水平。     

降雨径流对农田面源污染物产出的影响

试验通过模拟降雨的方法,探索降雨与农田土壤泥沙产出量的关系。试验表明,10%坡度条件下的泥沙累积量普遍高于相同降雨指数情况下5%的泥沙累积量,在坡度相同的条件下,泥沙累积量随着降雨量的增加而增加,在坡度为10%降雨量为150mm·h-1条件下,泥沙累积量最大,30min时,泥沙累积量可达到350kg。试验还对数据进行了回归分析,得到了相关的拟合函数。     

景宁惠明茶溯源与产业发展历程

产于浙南山区的惠明茶,因其品质特优,1915年在巴拿马万国博览会上荣获金奖,从此名扬四海。本文阐述了景宁惠明茶的历史渊源与茶产业的发展历程以及成为当地农民致富的支柱产业。     

Improvement of growth and gymnemic acid production by altering the macro elements concentration and nitrogen source supply in cell suspension cultures of Gymnema sylvestre R. Br

Gymnema sylvestre is an important medicinal plant which bears bioactive compound namely gymnemic acids. The present work deals with optimization of cell suspension culture system of G. sylvestre for the production of biomass and gymnemic acid and we investigated effects of macro elements (NH₄NO₃, KNO₃, CaCl₂, MgSO₄ and KH₂PO₄ - 0.0, 0.5, 1.0, 1.5 and 2.0× strength) and nitrogen source [NH₄⁺/NO₃⁻ ratio of: 0.00/18.80, 7.19/18.80, 14.38/18.80, 21.57/18.80, 28.75/18.80, 14.38/0.00, 14.38/9.40, 14.38/18.80, 14.38/28.20 and 14.38/37.60 (mM)] of Murashige and Skoog medium on accumulation of biomass and gymnemic acid content. The highest accumulation of biomass (165.00 g l⁻¹ FW and 15.42 g l⁻¹ DW) was recorded in the medium with 0.5× concentration of NH₄NO₃ and the highest production of gymnemic acid content was recorded in the medium with 2.0× KH₂PO₄ (11.32 mg g⁻¹ DW). The NH₄⁺/NO₃⁻ ratio also influenced cell growth and gymnemic acid production; both parameters were greater when the NO₃⁻ concentration was higher than that of NH₄⁺. Maximum biomass growth (159.72 g l⁻¹ of FW and 14.95 g l⁻¹ of DW) was achieved at an NH₄⁺/NO₃⁻ ratio of 7.19/18.80, and gymnemic acid production was also greatest at the same concentration of NH₄⁺/NO₃⁻ ratio (11.35 mg g⁻¹ DW).     

Evaluation of apparent digestibility coefficients of individual feed ingredients in spotted rose snapper Lutjanus guttatus (Steindachner, 1869)

Apparent digestibility coefficients (ADCs) for dry matter, crude protein, energy and essential amino acids for five commonly used feed ingredients were determined for juvenile spotted rose snapper Lutjanus guttatus (average body weight 90.6 g). ADCs were determined using the stripping technique to collect faeces after fish were fed a reference diet and test diets composed of 700 g kg^?1 reference diet and 300 g kg^?1 test ingredient. Chromic oxide (Cr₂O₃) was used as an inert indicator. Ingredients tested included sardine fishmeal (FM), canola meal (CM), tuna by‐products meal (TBM), poultry by‐product meal pet grade (PBM‐PG) and solvent‐extracted soybean meal (SBM). In general, all ingredients showed high digestibility values for all essential amino acids, although differences were detected among ingredients. ADC values for dry matter, protein and energy ranged 77.0–80.4%, 84.3–82.5% and 89–88.8%, respectively, for marine ingredient and land‐based animal protein sources, and 75.0–74.2%, 81.5–80.9% and 87.4–86.8%, respectively, for the plant‐based protein source. SBM, TBM and PBM‐PG should be further evaluated in feeding trials as partial FM replacements in rose snapper L. guttatus diets. Knowledge of ADC values for these ingredients will allow feed producers to develop nutritionally balanced, low‐cost feed formulations for this species.