苗床添加EM菌肥对烟草幼苗生长及抗逆酶活性的影响

【目的】研究苗床添加EM菌肥对烟草幼苗生长发育及抗逆酶活性的影响,以探索培育烟草壮苗的新措施。【方法】以红花大金元和云烟85为供试材料,采用室内模拟试验,研究烟草育苗基质中添加不同质量分数EM菌肥(0(T0),5%(T1),10%(T2),15%(T3))对烟草幼苗根系形态及活力、生物量和抗逆酶活性的影响。【结果】添加EM菌肥后云烟85幼苗总根长、平均直径、总根体积、总根表面积及红花大金元总根长较对照均显著增加,随添加菌肥质量分数的增加,云烟85平均直径、总根体积、总根表面积增幅不明显;不同径级根系总长表现为≤3mm细根增幅显著;EM菌肥显著提高幼苗根系活力,红花大金元以T2最强,平均达425.45μg/(g·h),增幅74.0%,T3、T1其次,而云烟85表现为T1T2T3T0。添加EM菌肥后,红花大金元幼苗总生物量以T2(881.1mg/株)最大,增幅57.5%,云烟85总生物量随菌肥质量分数的增大有增加趋势。添加EM菌肥后烟草幼苗过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性显著增强,T2各酶活均达最高或次高。不同烟草品种对EM菌肥的响应存在差异,EM菌肥处理后红花大金元根系活力、抗逆酶活性增幅均大于云烟85,尤以叶片抗逆酶活性的表现更为突出。【结论】育苗基质中添加质量分数10%的EM菌肥可显著提高红花大金元和云烟85幼苗根系活力,促进细根生长,增加幼苗干物质积累,增强幼苗抗逆性,建议在生产中推广应用。     

Microbial diversity and activity of disturbed soil in the northern Chihuahuan Desert

 The effects of intense grazing, seasonal drought, and fire on soil microbial diversity (substrate utilization) and activity in a northern Chihuahuan Desert grassland were measured in summer 1997, winter 1998, and spring 1998. Intense livestock grazing was initiated in winter 1995, burning occurred in August 1994, and drought stresses were imposed from October 1994 to June 1997. Microbial diversity was inferred from the carbon substrate utilization patterns in both gram (+) and gram (–) Biolog plates. Microbial activity was estimated by the activity of selected enzymes. Neither microbial diversity nor activity was affected by grazing. The interaction of intense grazing and stress sub-treatments only occurred in spring for one set of diversity measurements. The maximum microbial diversity and activity occurred in the winter-drought-stress sub-plots in summer and spring. Burning reduced microbial diversity and most enzyme activities as compared to the control in summer and spring. Microbial diversity was also lower in summer-drought-stress sub-plots than in the control in summer and spring. Microbial diversity was highest in summer, intermediate in winter, and lowest in spring. Microbial activity was generally higher in summer and lower in winter. It was concluded that substrate availability was the most important factor affecting the diversity and activity of soil microorganisms within a season. Soil moisture was not the factor causing differences in microbial diversity and activity among the stress treatments, but it was a predictor for some microbial responses under a particular stress. Received: 12 August 1999     

参与水体循环的微生物群落研究

首先,分析了微生物在水体物质转化与循环中的作用,主要介绍了细菌在碳、氮、磷、硫循环中的作用;然后,探讨了微生物在水污染治理中的应用,如净化水体,作为环境污染指示生物;最后,介绍了水体微生物群落的研究方法,包括传统方法、现代分子生物学方法以及其他新的方法,并对今后微生物的研究方向进行展望。     

发酵中草药添加剂在动物生产上的应用

中草药因其无耐药性、无残留性等优点,已经成为动物饲料生产的天然绿色添加剂。微生物在对中草药的发酵过程中发生一系列生化反应,使中草药中大量活性物质析出,提高了中草药有效成分含量,提高了药效,降低中草药毒性,并产生了多种代谢产物,扩大了中药功能范围。本文主要对中草药发酵技术、作用特点及在动物生产上的应用进行了综述。     

农业废弃物静态高温堆腐过程中的生物化学变化

 以养鸡场鸡粪、小麦秸秆为原料，在静态通气条件下研究了堆腐过程中有机物料温度、微生物及酶活性变化。结果表明，发酵罐底部有机物料温度较低，中上部较高；罐内有机物料在7～8 h可以从环境温度上升到50℃，并在50℃以上持续198～483 h。持续高温时间符合消灭病原微生物标准。有机物料温度处于55℃左右的高温阶段，纤维素酶活性[0.457 mg glucose /(g·24h)]和蔗糖酶活性[87.836 mg glucose/(g·24h)]最高，脱氢酶和脲酶活性分别达到高峰值21.62 μl H＋/(g·24h) 和0.932 mg NH3/(g·24h)。堆腐后期降温阶段，多酚氧化酶活性达到最高值6.23 mg gallicin/(g·2h)。细菌和放线菌数在堆肥2 d达到高峰值，分别为2.51×1012 CFU/g和3.68×108 CFU/g，之后缓慢下降；放线菌数变化较平缓。真菌数在堆腐开始较高，随着堆体温度上升而下降；堆腐后期随着温度下降而缓慢上升。整个堆腐过程中，真菌数一直较低，而细菌和放线菌相对较高。     

发酵饲料对猪肉品质的影响及应用研究进展

发酵饲料作为一种新型绿色环保的功能性饲料,具有提高饲料营养价值、降低抗营养因子含量、改善饲料适口性、有益动物肠道健康、促进动物生长发育、改善动物产品质量和减排环保等特点。文章对发酵饲料的定义和益处进行了简要的概述,重点讨论了其对猪肉品质的影响、机理和其在猪肉生产上的应用,以期为发酵饲料的合理开发与高效应用提供参考。     

The effect of microorganisms,salinity and turbidity on hydraulic conductivity of irrigation channel soil

The introduction of polysaccharide producing benthic algae and bacteria could provide a low cost technique for seepage control in irrigation channels. The ability of algae and bacteria to produce polysaccharides proved to be successful in reducing the hydraulic conductivity of irrigation channel soil. Hydraulic conductivity was reduced to less than 22% of its original value within a month of inoculating soil columns with algae. Chlorophyll and polysaccharide concentrations in irrigation channel soil were measured in order to assess the growth of algae and extent of polysaccharide production, and their correlation with hydraulic conductivity of channel soil. Increases in polysaccharide occurred in the top layer (0–5 mm) of the soil column. The reduction of hydraulic conductivity was highly correlated with the amount of polysaccharides produced (r ² = 0.92). Hydraulic conductivity decreased with increasing algal and bacterial numbers. The first few millimetres of the soil core where microbial activity was concentrated, seemed effective in controlling seepage. Incorporation of extra nitrate and phosphate into algal medium did not increase the production of polysaccharides by algae in channel soil. The effect of salinity and turbidity of irrigation channel water on channel seepage was studied by measuring the effects on hydraulic conductivity of channel soils. When the electrical conductivity (EC) of the water increased above a threshold value, the hydraulic conductivity increased because of the flocculating effects on clay particles in channel soils. A relationship between sodium adsorption ratio (SAR) and EC of the channel water was established which indicated 15% increase in channel seepage due to increases in salinity. Increasing the turbidity of irrigation water (by increasing the concentration of dispersed clay) resulted in lowering the hydraulic conductivity of the channel soil due to the sealing of soil pores by dispersed clay particles. When the turbidity of the water was 10 g clay l^–1, the hydraulic conductivity was reduced by 100%. An increase in clay concentration above 1 g l^–1 resulted in significant reduction in hydraulic conductivity. Soil bowl experiments indicated that clay sealing with a coating of hydrophobic polymer on the surface could also effectively prevent seepage of saline water.     

金鸡湖与尚湖中微生物数量及群落特征的研究

对苏州地区金鸡湖与尚湖水体中的微生物数量及种群组成的研究表明，异养细菌数金鸡湖比尚湖高，分别为1．7－26万个／mL和500－80000 个／mL，高峰期出现在10月份；放线菌和霉菌数量较少，金鸡湖为0－19个／mL和0－7个／mL，尚湖为1－25个／mL和0－37个／mL。从大肠菌群数看，金鸡湖明显高于尚湖，分别为350－16000个／L和20－250个／L， 表明金鸡湖接纳生活污水和施肥养鱼对大肠菌群数的升高至关重要；金鸡湖和尚湖水体 中分别检测出8个和9个属的异养细菌，优势菌分别为弧菌属、气单胞菌属、芽孢杆菌属和不动杆菌属、假单胞菌属、芽孢杆菌属。     

Cycling of extracellular DNA in the soil environment

Upon entering the soil environment, extracellular DNA is subjected to dynamic biological, physical, and chemical factors that determine its fate. This review concerns the fate of both recombinant and non-recombinant sources of DNA. A schematic of DNA cycling coupled with genetic transformation is presented to understand its behavior in soil. Extracellular DNA may persist through cation bridging onto soil minerals and humic substances, be enzymatically degraded and restricted by DNases of microbial origin, and/or enter the microbial DNA cycle through natural transformation of competent bacteria. Lateral gene transfer may disseminate DNA through the microbial community. An understanding of DNA cycling is fundamental to elucidating the fate of extracellular DNA in the soil environment.     

控制性根系分区交替灌溉对玉米拔节期土壤微生物区系的影响

本文利用盆栽试验研究玉米常规全部根系区域灌水（全灌）、固定1/2根系区域灌水（固定灌）和交替1/2根系区域灌水（交替灌）三种灌水方式对土壤微生物区系和生物多样性指数的影响。试验结果表明：在同一灌水方式下，轻度的水分亏缺能有效地改善土壤的水分、通气等条件，从而有利于土壤微生物的繁衍发展。在不同灌水方式下，由于交替1/2根系灌水使根系区土壤处于交替干燥和湿润，在提供生命活动所需水分的同时，使土壤孔隙处于良好的通气条件下，为土壤微生物提供了有益的生存条件，因此显示出其明显的优越性。