土壤富硒细菌的筛选、鉴定

从广西不同富硒区土壤中分离出32株耐硒细菌,通过优化加硒时间、培养时间及加硒浓度进行富硒试验,筛选获得4株富硒能力较强的细菌,进一步通过对4株细菌16S rDNA序列分析及系统发育树分析明确了各菌株的种属关系。经鉴定,YLB1-6为Bacillus cereus,TXB1-10为Sinomonas sp.,TXB2-5为Bacillus thuringiensis,GPB1-5为Achromobacter denitrificans。在最适加硒时间、培养时间及适宜加硒浓度条件下,各菌株的硒转化率分别为:YLB1-674.22%,TXB1-1066.05%,TXB2-555.31%,GPB1-563.30%。各菌株处理能显著提高土壤可交换态硒含量,对土壤硒起到较强活化作用。土壤富硒细菌为硒转化提供更多的高效微生物载体,并为富硒产品开发研究提供技术支持。     

土壤耐硒菌株筛选及其硒活化能力评价研究

  目的  从湖北省恩施市双河镇新塘乡渔塘坝硒矿床采集矿渣、淤泥、农田土壤,从中筛选分离出耐硒菌株,并对筛选出菌株的活化土壤硒的能力进行评价。  方法  采用稀释涂布平板法和平板划线法分离、筛选出耐受亚硒酸钠浓度较高的菌株,根据菌株形态学特征和用分子生物学方法对其进行分类鉴定,再将分离得到的耐硒菌株分别接种于酸性富硒赤红壤中进行培养,通过测定培养后土壤中的硒含量评价两菌株活化土壤硒的能力。  结果  筛选出了细菌B-1和真菌B-2两耐硒菌株;细菌B-1被鉴定为嗜麦芽寡养单胞菌（Stenotrophomonas maltophilia）,其可耐亚硒酸钠浓度为17000 μg mL?1,在温度20 ~ 35 ℃、pH 5 ~ 9、盐浓度0 ~ 3%条件下可正常生长;真菌B-2被鉴定为聚多曲霉（Aspergillus sydowii）,该菌株可耐亚硒酸钠浓度为6000 μg mL?1,在温度25 ~ 30 ℃、pH 4 ~ 7、盐浓度2% ~ 5%条件下可正常生长。添加两耐硒菌株培养后土壤的可溶态硒和可交换态硒含量均显著提高。  结论  筛选出具有较高的硒耐受性和较强的活化酸性富硒土壤中硒的能力的菌株,可为富硒土壤资源开发利用提供生物种质资源和技术手段,对富硒微生物肥料研发、富硒农产品生产和硒污染土壤环境修复也有重要意义。     

芽孢杆菌生物合成纳米硒条件优化及活性评价

作为生防菌的枯草芽孢杆菌XP（Bacillus subtilis subspecies stercoris strain XP）不仅具有较强的耐硒与耐盐能力,而且还可将毒性较高的无机硒转化为安全性高、生物活性好的纳米硒 (SeNP),然而目前其合成SeNP的效率并不高。为提升菌株XP生物合成SeNP的效率,该研究针对其合成工艺条件做了进一步优化。首先,通过单因素试验,初步筛选出适宜范围量值的初始亚硒酸盐Se (IV)浓度、摇床转速、XP接种量;其次,将这三个因子作为影响因素,以SeNP产量为响应指标,利用Box-Behnken响应面法 (RSM) 进行分析;最终,通过响应面法获得枯草芽孢杆菌XP产SeNP的最优发酵工艺条件。研究结果表明,枯草芽孢杆菌XP合成纳米硒的最佳发酵条件为：初始Se (IV) 3.4 mmol/L、摇床转速157 r/min、菌株XP接种量9.9%,此发酵条件下纳米硒的产量达到1.82 mmol/L,相对优化前提升了60%以上。此外,通过种子发芽试验,进一步证明此工艺条件下合成的纳米硒具有较高的生物活性,可有效提升油麦菜种子活力,促进种子萌发。     

一株高效还原亚硒酸盐的粘质沙雷氏菌的分离鉴定及特性

从广西钦州市钦北区的富硒土壤中筛选出一株可高效还原亚硒酸盐的细菌QZB-1。16S rDNA基因序列分析确定菌株为粘质沙雷氏菌(Serratia marcescens)。研究发现菌株QZB-1可耐高达180 mmol/L的亚硒酸盐。进一步研究发现菌株QZB-1在36 h之内对1 mmol/L亚硒酸盐的还原率为95%，随着硒浓度升高还原率有所下降。正交实验表明，对菌株还原亚硒酸盐的影响程度依次是初始亚硒酸盐浓度>培养时间>接种量，最佳还原条件是初始亚硒酸盐浓度为1 mmol/L，接种量为10%，培养时间为36 h，此时菌株QZB-1对亚硒酸盐的还原率大于98.55%。研究结果表明新型亚硒酸盐还原菌粘质沙雷氏菌QZB-1可高效还原亚硒酸盐为单质纳米硒，可高效应用于亚硒酸盐污染水体和土壤的治理。     

外源硒（Se(4＋)和Se(6＋））污染对土壤酶活性的影响

利用盆栽试验,研究了不同浓度、不同价态外源硒（Se4＋、Se6＋）对连续种植小白菜土壤中过氧化氢酶、脱氢酶、脲酶和碱性磷酸酶活性的影响,为土壤硒污染的生态风险评价和管理提供科学依据。结果表明：低浓度硒对土壤酶活性有不同程度的激活效应,而高浓度硒对4种土壤酶均产生抑制作用;外源硒对脲酶及脱氢酶活性的抑制作用大于碱性磷酸酶和过氧化氢酶。外源Se4＋及Se6＋浓度与土壤脲酶活性间都存在显著的负相关（P〈0.01）,且同浓度两个价态硒差异显著（P〈0.05）,说明脲酶可作为土壤硒污染程度的生态风险评价的生物指标;而过氧化氢酶、脱氢酶及碱性磷酸酶只能表征一定时间段内土壤硒污染的程度。土壤酶的ED5（0生态剂量）均随硒施入时间的延长而增大,以脲酶的ED50值最小,Se6＋的ED50小于Se4＋,生态毒性大于Se4＋。     

施纳米硒对小麦籽粒硒含量及其品质性状的影响

【目的】研究基施纳米硒肥对不同小麦品种籽粒百粒重、硒含量、硒形态,其他矿质元素以及面粉糊化特性的影响,为利用纳米硒肥进行小麦硒生物强化提供参考。 【方法】选择 110 份小麦品种 (系),在扬州大学农学院网室种植,采用的施肥方式为基施纳米硒肥,设每千克土施 Se 0 (CK)、100 (Se100)、150 (Se150) mg 2 次重复,随机区组设计。小麦成熟期收获籽粒,测定百粒重。利用离子发射光谱 – 原子吸收仪测定了籽粒 Se、Ca、Mg、Cu、Fe、Mn、Zn 及 S 含量。选择高硒处理中硒含量前 10 名的品种,利用 LC-UV-AFS 测定了籽粒中不同形态硒的含量。随机挑选 59 个品种并利用 RVA 仪 (快速粘度分析仪) 测定其面粉糊化特性的特征值。利用 MATLAB 和 SPSS 软件进行数据分析。 【结果】基施硒 0、100、150 mg/kg 土,小麦籽粒的百粒重均值分别为 3.78、4.11 和 3.70 g,籽粒中总硒含量分别为 2.00、12.46 和 17.35 mg/kg。籽粒中的硒主要以有机态形式存在,以硒蛋氨酸含量最多,其次是硒甲基化半胱氨酸和少量的硒半胱氨酸,无机态硒仅微量存在于极少数品种中。基施硒肥对测定的矿质元素的吸收积累既有协同也有拮抗作用,对小麦面粉的糊化特性没有显著影响。糊化特性取决于基因型,不同品种间存在极显著差异。 【结论】硒肥可以提高小麦籽粒中的硒含量,但增幅因品种而异;硒强化后籽粒中硒主要以有机态形式存在;低浓度硒处理可以提高小麦籽粒的百粒重,且不会影响小麦的面粉糊化特性。     

叶面喷施锌或硒对生菜吸收镉的拮抗作用研究

环境污染导致水和土壤中镉等重金属元素超标，是多年来造成农产品质量不合格的重要原因之一。农作物中的重金属元素最终会通过食物链进入人体，对人体造成危害。因此研究如何抑制农作物对镉的吸收在理论上和应用上都有重大意义，前人也做了一些相关的工作。众所周知，硒和锌是对人体有益的微量元素。缺硒会得各种各样的疾病，研究还表明硒具有抗癌作用，近年来人们对富硒食品做了大量的研究；锌是许多金属酶的重要组成部分，并能激活多种酶，因此锌在生物的正常代谢过程中起着重要作用。当镉与锌、硒共存的时候，它们之间有复杂的相互作用。     

Z0206细菌富硒多糖对小鼠的免疫调节作用研究

本试验通过建立环磷酰胺（CP）诱导的免疫抑制小鼠模型,研究了Z0206细菌富硒多糖的免疫调节功能。试验分为四个处理：Ⅰ组为对照组;Ⅱ组为CP组;Ⅲ组为细菌富硒多糖组;Ⅳ组为细菌富硒多糖预防组。结果表明,与对照组相比,细菌富硒多糖组小鼠免疫器官指数、NK细胞活性、血液溶血素水平（HC50）和脾细胞抗体形成数（PFC）均显著提高（p<0.05）,T细胞亚群增殖有所提高,但差异不显著（p>0.05）。与CP组相比,细菌富硒多糖预防组能使CP诱导的免疫抑制得到修复,改善试验小鼠免疫器官指数、T淋巴细胞和自然杀伤细胞（NK）活性、血液溶血素水平和脾细胞抗体形成数,差异显著（p<0.05）。提示：细菌富硒多糖能增强小鼠的免疫功能,对CP诱导的免疫抑制具有修复作用。     

磷酸盐与硒酸盐相互作用对小白菜磷和硒吸收的影响

采用土培盆栽试验方法,研究了不同浓度磷酸盐与硒酸盐相互作用对小白菜生长、磷和硒吸收的影响,旨在为安全有效地进行补硒和硒污染土壤的植物修复提供理论依据。结果表明,在试验的硒浓度范围内（1．0～5．0mg·kg-1）,硒酸盐对小白菜产生毒害作用,表现为单施硒酸盐处理较对照小白菜的根长、株高、地上部和地下部干重均下降,且高硒处理（5．0mg·kg-1）小白菜SPAD值显著下降。施用磷酸盐能显著增加小白菜生物量,明显缓解硒酸盐的毒害作用,且由于生物稀释效应导致小白菜地上、地下部硒浓度下降,但小白菜的硒吸收量增加。施磷小白菜地上部硒平均利用率提高至42％,且同等硒浓度低磷处理小白菜硒利用率高于高磷处理,表明适量施磷可提高硒的利用率。施磷时施硒对小白菜地上部磷浓度无显著影响,但由于硒的毒害作用导致磷吸收量下降。     

氨基酸硒液体肥在设施桃上的应用效果

以设施栽培的4年生中油4号油桃和春雪毛桃为试材,对氨基酸硒的应用效果进行了研究。结果表明:施用氨基酸硒液体肥显著增加栅栏组织厚度和叶片厚度及比叶重,改善桃树的叶片质量;显著促进叶绿素和类胡萝卜素等光合色素的合成,提高净光合速率,施用氨基酸硒液体肥处理净光合速率是对照的1.22～1.50倍;显著增加产量,施用氨基酸硒液体肥处理比对照高2.836～8.145 t/hm2;显著增加果实可溶性固形物和可溶性糖含量及糖酸比,改善果实品质;显著提高果实的Vc含量、超氧化物歧化酶(SOD)活性和果实硒含量,提高果实的营养与保健品质。与土施相比,叶面喷施效果更佳且经济。     

The effect of selenium biofortification in alfalfa (Medicago sativa)

Abstract

Biofortification of agricultural productions is important to enhance the quality of the products. The aims of this research were to investigate the possibility of selenium biofortification of alfalfa in the calcareous and non-calcareous soils by applying fertilizers differently (control, soil application, inoculant of seleno-bacteria, foliar application, combined soil, and foliar applications of selenate). Morpho-physiological properties and nutritional responses, such as shoot dry weight, phosphorus, potassium, selenium, zinc, and iron concentration in the plant’s tissue were measured. In all parameters, the use of selenium sources in the calcareous soils had a significant effect compared with the control treatment. Among the methods and sources of selenium, foliar application of sodium selenate gave the best response. By the usage of this treatment, Se concentration was increased up to 112.5% and 182%, respectively, compared with the control treatment in non-calcareous and calcareous soil. According to the results, inoculant of selenium bacteria and sodium selenate are recommended as a natural way to selenium biofortification in alfalfa and to improve the quality of the produced forage. In addition, attention to the biological potential of the soil and the use of native soil bacteria is also recommended.     

Improved selenium recovery from tissue with modified sample decomposition

The present paper describes a simple modification of a recently reported decomposition method for determination of selenium in biological tissue by hydride generation atomic absorption. The modified method yielded slightly higher selenium recoveries (3-4%) for selected reference tissues and fish tissue spiked with selenomethionine. Radiotracer experiments indicated that the addition of a small volume of hydrochloric acid to the wet digestate mixture reduced slight losses of selenium as the sample initially went to dryness before ashing. With the modified method, selenium spiked as selenomethionine behaved more like the selenium in reference tissues than did the inorganic spike forms when this digestion modification was used.     

填埋场中硫化氢恶臭污染防治技术研究进展

硫化氢是垃圾填埋场恶臭污染的主要贡献者之一,填埋场中的硫化氢恶臭污染不仅危害现场工人的身体健康,而且影响周围居民的正常生活。该文概述了垃圾填埋场中硫化氢恶臭的污染状况和特征,从硫化氢的源头控制和末端治理两方面阐述了垃圾填埋场硫化氢恶臭防治技术的研究进展。目前,有关填埋场硫化氢恶臭的控制技术主要集中在末端处理,如对填埋气中的硫化氢进行净化或者采用高效的覆盖层材料来减少硫化氢释放,而对于填埋场内的源头控制手段还非常有限。该文着重提出了利用填埋场堆体内部含量丰富的铁资源的微生物氧化还原以及反硝化脱硫菌的特征代谢作用进行硫化氢的内源削减两大方法,并探讨了其他相关技术的发展趋势,对完善填埋场的硫化氢恶臭污染控制理论与实践具有参考价值。     

A bacteriological assessment of the Mersey Estuary and North Wirral Coast,UK

The River. Mersey and its Estuary is assessed for the effects of pollution by using biological indicators; a sampling program for certain bacteria indicates that there is often gross pollution, although there is a wide range of observed values on both short time and space scales. This study considers bacteriological contamination in order to supplement existing survey data on heavy metals, dissolved oxygen, biochemical oxygen demand and suspended solids.     

富硒土壤生物转硒技术的研究进展

本文论述了生物转硒技术的应用价值和意义,总结了有机硒生成的专利和生物转硒的技术特点,并对生物转硒技术的发展进行了展望。     

The influence of fluorine,boron, selenium,and arsenic pollution on the biological properties of ordinary chernozems

In most cases, fluorine, boron, selenium, and arsenic pollution deteriorates the ecological-biological properties of ordinary chernozems: the number of saprotrophic bacteria (especially those of the Azotobacter genus) that of fungi, and the enzymatic activity decreases, while the phytotoxicity becomes higher, etc. The consequences of this pollution are related to the nature of the element, its concentration in the soil, the chemical form of the compound, and the time period from the moment of pollution. The elements studied form the following sequences according to their effect on the properties of an ordinary chernozem: B > Se > As > F (when the maximum permissible concentration (MPS) of these elements was accepted as the unit of measure) and Se > As > B > F (when the units of measurement were mg/kg or mmol/kg of soil).     

Bacterial Physiological State in Wastewater: Monitoring Maintenance and Production with Leu/TdR Ratio for Less Pollution

In domestic wastewater, bacterial physiology controls cell production (growth, replication) and cell maintenance, determining how energy is allocated between these two processes. The aim here was to develop a method to quantify these cellular processes so that the bacterial physiological state could be manipulated to lower this source of pollution. We simultaneously used the incorporation of radiolabelled thymidine into DNA (a measure of new cell synthesis) and leucine into protein in wastewater to quantitatively distinguish bacterial growth from maintenance processes. We found that DNA and protein syntheses were coupled in wastewater after substrate enrichment (with glucose or acetate)??balanced growth. Once the substrate was depleted, the two processes became uncoupled??unbalanced growth. In this physiological state, the bacteria were synthesising protein, but fewer bacteria were replicating. More energy was allocated to cell maintenance than replication. A mean Leu/TdR ratio of 7.4 was determined for wastewater and was similar to natural aquatic ecosystems. As the bacterial growth rate decreased, the Leu/TdR ratios increased. We show how the simultaneous measurement of [³H]Leu and [³H]TdR quantitatively distinguishes balanced from unbalanced growth. Low [³H]Leu/[³H]TdR ratios indicated bacteria were physiologically stressed, an ideal state for biological wastewater treatment processes (WWTP) as the bacteria divert more energy to maintenance activities instead of growth. Leu/TdR ratios of 70 have been recorded in natural aquatic ecosystems which suggests WWTP have potential to be manipulated to achieve much higher Leu/TdR ratios than we report here. Changes to plant operation to improve operation efficiency include finding the optimum rate of substrate (pollution supply) or alternating aerobic and anaerobic periods to maximise the Leu/TdR ratio to achieve less biomass production for land disposal and more cost-effective operation that generates less pollution in the effluent.