红树植物根泌物及其化感抑藻作用的探究

由海水富营养化引发的赤潮是影响全球海洋环境状况的突出问题之一。如何更好地对其进行防治是当前近岸海域生态环境保护工作的重要课题与研究热点。浮游藻类作为赤潮灾害的主要参与者,抑制其生长繁殖无疑是防治赤潮的关键。本文在总结植物根系分泌物的种类及其对根系微生物的化感作用、植物化感抑藻的研究现状并列举有抑藻活性的水生植物种类的基础上,设计实验方案探讨红树根泌物对藻类是否具有化感作用以及红树根泌物的成分,在得到负效应存在的结果的前提下预测红树根泌物中包括单宁、氨基酸、低分子量有机酸、脱氢酶这几类化合物,并讨论红树根泌物的抑藻机理。     

烟草化感自毒作用与其连作障碍研究的启示

介绍了植物化感自毒作用的概念、产生机理和作用特点,对烟草连作导致其产量和品质下降,土壤营养失衡和病虫害的发生进行了综述,认为烟草的品质成分与化感自毒物质的同质性是烟草栽培中连作障碍与化感自毒作用更强烈的根本原因。提出了深化烟草化感自毒作用研究,强化栽培技术的"地域性",构建现代烟草农业的生态格局等实现烟叶生产可持续发展的措施。     

浙大教授发现稗稻相争的“秘密武器”

<正>浙江大学农学院樊龙江教授团队对田间头号杂草——稗草进行了全基因组测序和水稻化感互作实验,找到了稗草与水稻相争的"秘密武器",并对水稻育种指出了一种新的基因资源。相关研究论文在《自然·通讯》上发表。植物化感作用简单地说就是植物会释放"化学武器"。生长过程中,植物会向环境释放特定的防御性化学物质,从而影响邻近植物生长。樊龙江团队通过基因组研究发现,稗草能分泌一种叫     

植物化感作用研究现状及其在烟草栽培中的作用展望

从植物化感物质的种类、释放途径、作用机理、表现形式等角度概述了植物化感作用的原理。综述了植物化感作用在分子水平、土壤生态系统水平上和环境胁迫下化感效应的研究现状,探讨了研究植物化感作用在烟草栽培中的应用。      

南美白对虾养殖水体中抑藻细菌的分离及鉴定

本研究从南美白对虾养殖水体中分离出10株细菌,进行分子鉴定和系统进化树分析,并评价了它们对鱼腥藻Anabaena cylindricaFACHB-82的抑藻效果。16Sr RNA基因分析表明,分离的10株细菌中三株与假单胞菌Pseudomonas plecoglossicidc、Pseudomonas protegens和Pseudomonas monteilii最为相似,一株与气单胞菌Aeromonas veronii相似,两株与陶厄式菌Thauera mechernichensis和Thauera aromatica相似,枯草芽孢杆菌Bacillus subtilis、微杆菌Microbacterium flavum、黄杆菌Flavobacterium cauense以及金黄杆菌Chryseobacterium nakagawai各一株相似。抑藻结果表明细菌AB-3抑藻效果最好,其对鱼腥藻的生长抑制率达到87.11%。此外,AB-3菌对水华束丝藻Aphanizomenon flos-aquae和铜绿微囊藻Microcystis aeruginosa生长抑制率分别达到79.89%和23.65%,对小球藻Chlorella vulgaris也有一定的抑藻效果,但对衣藻Chlamydomonas reinhardtii抑藻效果不显著。本研究从水体中分离筛选出的一株陶厄氏菌AB-3,对试验的蓝藻都具有显著的抑藻效果,同时该菌对绿藻抑藻效果小或是没有抑制。     

烟草残体腐解液及其组分的化感潜力研究

以对化感物质具有高敏感性的莴苣(Lactuca sativa)种子为指示材料,研究了烟草品种K326形成的顶、腋芽等残体腐解液的化感潜力,同时将残体腐解液(各组分)分离后分别进行化感潜力的生物测定。结果表明:1）烟草残体腐解液对莴苣种子萌发及幼苗生长具有显著的抑制作用,且表现出低促高抑的双重浓度效应;2）腐解液及其组分对种苗各部分生长的抑制强度表现为:胚根＞胚轴＞子叶;3）将烟草残体腐解液分离后进行的生物测定表明,其酸溶性组分的生长抑制作用强度＞碱溶性组分＞中性组分,在烟草残体腐解液中酸溶性组分的化感物质是形成生长抑制作用的主体,而中性及碱溶性组分中的化感物质在一定浓度范围内对生长具有促进效应。      

烟草漂浮育苗有害藻类致病机制及其防治研究进展

烤烟漂浮育苗技术自21世纪初叶在我国大面积应用以来,已在我国的烟叶生产中发挥了重要的积极作用。然而,漂浮育苗系统的环境特点却极易导致藻类滋生。有害藻类的大量繁殖不仅会与烟苗竞争养分和溶氧,还会导致营养液理化指标下降,不利于烟苗正常生长发育。同时,许多有害藻类产生的藻毒素能够严重抑制烟草种子萌发和幼苗生长,危害烟苗健康,诱发多种烟苗病害的发生。本文综述了烟草漂浮育苗系统中有害藻类的种类、发生特点、藻毒素种类与致病机制,提出了源头防藻、生态控藻和药剂除藻等多种防治措施和策略。并对有害藻类的新型绿色防治措施进行了展望,旨在推进我国烟草漂浮育苗系统中有害藻类的基础研究与防治技术研发。      

大蒜对不同烤烟品种的化感作用

为了明确大蒜对不同烤烟品种的化感作用,进行了大蒜挥发物、提取物及种过大蒜的土壤(0～10cm)对不同烤烟品种种子发芽率、种苗生长及成苗生长等的影响试验.结果表明:大蒜对不同烤烟品种具有一定的化感作用.不同烤烟品种的化感程度不同,对同一烤烟品种发芽、苗高及根长的化感作用或程度也不尽相同.其中.新鲜大蒜挥发物对烤烟种苗鲜物质的积累具有明显抑制作用,抑制率33.91%～57.89%;新鲜大蒜乙醇提取物对不同烤烟品种发芽具有较强的抑制作用,抑制率为7.00%～100%;种过大蒜的土壤可抑制不同烤烟品种种苗鲜物质的积累,抑制率为8.35%～60.96%.但大蒜提取物及种过大蒜的土壤对不同烤烟品种成苗无显著的抑制作用,说明在目前的烟草种植模式下,采用大蒜作为烤烟的轮作作物时,可不考虑大蒜对烤烟生长负面化感作用的影响.     

生态工程化南美白对虾养殖设施系统构建技术研究

针对南美白对虾养殖特点及存在的问题,研究一种可持续生产的生态工程化养殖设施系统,可有助南美白对虾养殖的全天候生产和养殖生产"节能、减排"。结果表明:本系统能够显著提高南美白对虾的生长速度,同时明显改善了养殖水体中氮磷营养盐的含量,并能有效抑制有害藻类的生物量。     

药食两用植物茼蒿化学成分及生物活性研究进展

茼蒿(Chrysanthemum coronarium L.)是一种菊科(Compositae)茼蒿属(Chrysanthemum)药食两用植物,目前对其化学成分分离、鉴定及生物活性研究报道较多。化学成分研究结果表明茼蒿中主要含有黄酮、酚酸、倍半萜内酯、单萜烯、二萜、甘油二酯糖苷、生物碱、植物甾醇、杂环化合物、聚乙炔类化合物和挥发油等多种类型化合物。其中黄酮类和酚酸类活性成分为茼蒿中主要的化学成分,它们广泛存在于菊科植物中。茼蒿具有多种生物活性,包括镇咳祛痰、植物化感作用、杀线虫、抗肿瘤、抗氧化和清除自由基、昆虫拒食、护肝和抗菌等。黄酮和酚酸类成分是茼蒿发挥植物化感作用和抗氧化作用的物质基础;聚乙炔类化合物和挥发油是茼蒿发挥昆虫拒食和抗菌作用的活性物质;萜类化合物尤其是倍半萜内酯则是茼蒿抗肿瘤和抗菌活性成分。     

基于红藻多糖的生物转化研究进展

与陆地生物质相比,海洋生物质因具有光合作用效率高、生长速度快、碳水化合物含量高、不含木质素等优点,受到了越来越多的关注,被称为第3代生物质资源。红藻是典型的大型海藻,其细胞壁富含多糖。本文首先介绍了红藻的分布与组成,之后围绕红藻多糖的生物转化,分别综述了其在酶解制备琼胶寡糖和3,6-内醚-L-半乳糖以及发酵生产乙醇和有机酸方面的研究进展,并对未来红藻生物质的利用方向进行了展望。     

盐藻工厂化养殖技术与产品开发(二)

盐藻是一种光能转化率高、生产繁殖快、适于养殖的单细胞藻。文章从养殖地域的选择、藻种的选育、培养介质、室外养殖设施、培养方式、培养条件的控制、敌害防治及采收等方面对盐藻的工厂化养殖技术做了全面介绍。在产品开发方面,介绍了盐藻粉的营养成分和氨基酸组成,介绍了盐藻粉软胶囊的3项功能试验结果,试验结果表明盐藻粉具有抗辐射、调节免疫和抑制肿瘤的作用;还对盐藻的胡萝卜素的几种产品形式及营养评价做了简要介绍。最后,对盐藻工厂化养殖中存在的问题做了简要讨论,对盐藻胡萝卜素产业的发展前景做了展望。     

Controlling algal growth in photo-dependent decolorant sludge by photocatalysis

In the treatment of synthetic dye wastewater by photosynthetic bacteria under optical irradiation, excessive algal growth and adhesion on the walls of the reactor are serious problems. The adverse effects of excessive algal growth on photosynthetic bacterial activity are significantly greater than those of the decreased optical irradiation of the solution. In this report, we investigated the effects of photocatalysis on the growth of algae (Chroococcus sp.) and photosynthetic bacteria. The different sensitivities of Chroococcus sp. and photosynthetic bacteria to photocatalysis were observed by an ATP assay. Moreover, from microscopy findings, some algae were damaged by TiO2 with UV. We suggested that some algae suffered from membrane damage and consequently cell substances were released, resulting in the increase of dissolved material following treatment using TiO2 with UV.     

Effects of three pharmaceutical and personal care products on natural freshwater algal assemblages

Treated wastewaters in the United States contain detectable quantities of surfactants, antibiotics, and other types of antimicrobial chemicals contained in pharmaceutical and personal-care products (PPCPs) that are released into stream ecosystems. The degradation characteristics of many of these chemicals are not yet known, nor are the chemical properties of their byproducts. They also are not currently mandated for removal under the U.S. Clean Water Act. Three representative PPCPs were individually tested in this study using a series of laboratory dilution bioassays: Ciprofloxacin (an antibiotic), Triclosan (an antimicrobial agent), and Tergitol NP 10 (a surfactant), to determine their effects on natural algal communities sampled both upstream and downstream of the Olathe, KS wastewater treatment plant (WWTP). There were no significant treatment effects on algal community growth rates during the exponential phase of growth, but significant differences were observed in the final biomass yields (p < 0.001). All three compounds caused marked shifts in the community structure of suspended and attached algae at both the upstream and downstream sites (p < 0.05). Increasing the concentrations of all three compounds over a 3 orders of magnitude range also caused a consistent decline in final algal genus richness in the bioassays. Our results suggest that these three PPCPs may potentially influence both the structure and the function of algal communities in stream ecosystems receiving WWTP effluents. These changes could result in shifts in both the nutrient processing capacity and the natural food web structure of these streams.     

Algal uptake of hydrophobic and hydrophilic dissolved organic nitrogen in effluent from biological nutrient removal municipal wastewater treatment systems

Dissolved organic nitrogen (DON) accounts for a large fraction of the total nitrogen discharged to surface waters by municipal wastewater treatment plants designed for biological nutrient removal (BNR). Previous research indicates that some but not all of the DON in wastewater effluent is available to bacteria and algae over time scales that are relevant to rivers and estuaries. To separate bioavailable DON from nitrate and less reactive DON species, an XAD-8 resin coupled with an anion exchange treatment was employed prior to chemical analysis and algal bioassays. Analysis of effluent samples from a range of municipal BNR plants (total DON concentrations ranging from 0.7 to 1.8 mg N/L) employing a range of technologies indicated that hydrophilic DON, which typically accounted for approximately 80% of the total DON, stimulated algal growth, whereas hydrophobic DON, which accounted for the remaining DON, remained at nearly constant concentrations and had little or no effect on algal growth during a 14-day incubation period. The hydrophobic DON exhibits characteristics of humic substances, and is likely to persist for long periods in the aquatic environment. The distinct differences between these two classes of DON may provide a basis for considering them separately in water quality models and effluent discharge regulations.     

Energy-water nexus for mass cultivation of algae

Microalgae are currently considered a potential feedstock for the production of biofuels. This work addresses the energy needed to manage the water used in the mass cultivation of saline, eukaryotic algae grown in open pond systems. Estimates of both direct and upstream energy requirements for obtaining, containing, and circulating water within algae cultivation systems are developed. Potential productivities are calculated for each of the 48 states within the continental U.S. based on theoretical photosynthetic efficiencies, growing season, and total available land area. Energy output in the form of algal biodiesel and the total energy content of algal biomass are compared to energy inputs required for water management. The analysis indicates that, for current technologies, energy required for water management alone is approximately seven times greater than energy output in the form of biodiesel and more than double that contained within the entire algal biomass. While this analysis addresses only currently identified species grown in an open-pond system, the water management requirements of any algae system will be substantial; therefore, it is critical that an energy assessment of water management requirements be performed for any cultivation technology and algal type in order to fully understand the energy balance of algae-derived biofuels.     

Industrial potential of carotenoid pigments from microalgae: Current trends and future prospects

Microalgae are rich source of various bioactive molecules such as carotenoids, lipids, fatty acids, hydrocarbons, proteins, carbohydrates, amino acids, etc. and in recent Years carotenoids from algae gained commercial recognition in the global market for food and cosmeceutical applications. However, the production of carotenoids from algae is not yet fully cost effective to compete with synthetic ones. In this context the present review examines the technologies/methods in relation to mass production of algae, cell harvesting for extraction of carotenoids, optimizing extraction methods etc. Research studies from different microalgal species such as Spirulina platensis, Haematococcus pluvialis, Dunaliella salina, Chlorella sps., Nannochloropsis sps., Scenedesmus sps., Chlorococcum sps., Botryococcus braunii and Diatoms in relation to carotenoid content, chemical structure, extraction and processing of carotenoids are discussed. Further these carotenoid pigments, are useful in various health applications and their use in food, feed, nutraceutical, pharmaceutical and cosmeceutical industries was briefly touched upon. The commercial value of algal carotenoids has also been discussed in this review. Possible recommendations for future research studies are proposed.     

Natural decoloration,composition and increase in dietary fibre content of an edible marine algae,Ulva rigida (Chlorophyta), grown under different nitrogen conditions

The colour, dietary fibre content and characteristics of the edible marine green algae, Ulva rigida, were investigated in relation with the nitrogen content of the algal culture medium. Colour brightness decreased and total nitrogen of the algae increased in nitrogen-enriched conditions. When nitrogen-enriched seaweeds were grown again in normal seawater for 10 days, colour brightness increased and total nitrogen concentration fell. Total dietary fibre content of the wild and nitrogen enriched algae were close (～38.0% DW) but increased markedly when the nitrogen-rich plants were cultured in normal sea-water (54.4% after 10 days). Soluble fibre were xylorhamnoglucuronan sulphate (ulvan) with close molar compositions for all the seaweed samples. Insoluble polysaccharides were composed of glucose, xylose, uronic acid, rhamnose and sulphate which molar proportions varied for the different algal samples. The soluble fibre intrinsic viscosity and the water holding capacity of insoluble fibre were not markedly affected by the growth conditions. This report demonstrates that edible seaweed aquaculture provides an alternative or a complement to post-harvest transformations of seaweeds to modify organoleptic and nutritional characteristics.     

褐藻胶的降解方法及其产物生物活性研究进展

褐藻胶是褐藻中含有的酸性多糖,由β-D-甘露糖醛酸及其C5差向异构体α-L-古罗糖醛酸两种单体组成。经降解后的小分子寡糖具有增强植物抗逆性、促进生长作用、抗菌活性、抗肿瘤活性、抗炎活性以及抗氧化活性等多种生理活性。目前,褐藻胶寡糖制备的方法主要有化学降解法、物理降解法和生物降解法。本文概述了褐藻胶结构、褐藻胶降解方法以及褐藻胶寡糖生理活性研究现状,其中重点介绍了生物降解的方法,并对褐藻胶裂解酶及其降解产物的应用进行了展望。     

Key parameters for the consumption suitability of offshore cultivated blue mussels (<Emphasis Type="Italic">Mytilus edulis</Emphasis> L.) in the German Bight

The occurrence and composition of toxic algae, and presence of viruses and other human microbial pathogens in production areas of mussels are factors determining suitability of mussel products for human consumption. As bivalves feed by filtering large volumes of water, potentially toxic viruses, algae, and bacteria as well as phytoplankton are ingested. With the expansion of mussel aquaculture and subsequent increase in human consumption of mussel products, improved risk management is required for consumer protection. For example, shifting production to offshore areas (e.g. wind farms) can decrease the hazards of infection due to dilution of contaminants, and increase overall health of mussels. In addition, the deployment of off-bottom cultivation methods such as longlines increases the condition index, growth, and aesthetic appearance of mussels. However, other hazards like algal toxins not yet monitored on a regular basis, may play a more important rule offshore. Here, we present an analysis of biological, economic, and consumer health-related aspects of mussel cultivation under near- and offshore conditions.