三种土壤微生物总DNA提取方法的比较

本文对3种常用的土壤微生物总DNA提取方法Martin法、高盐改进法及试剂盒法进行了比较,并通过DNA得率、纯度及16S rDNA V3可变区的PCR扩增结合DGGE法（denatumg gradient gel electrophoresis）,分别对3种方法进行评价。结果表明,3种方法提取的DNA均能满足土壤微生物多样性分析的要求。其中试剂盒方法操作简单,提取的DNA质量较高,但DNA得率较低且成本昂贵。Martin法和高盐改进法用时较长,DNA得率较高,纯度较低,但对后续PCR扩增和DGGE分析没有明显影响,且成本低廉。     

Impact of effective microorganisms and other biofertilizers on soil microbial characteristics,organic‐matter decomposition,and plant growth

Incubation and pot experiments were conducted to investigate the impact of commercially distributed biofertilizers (effective microorganisms [EM], BIOSTIMULATOR, BACTOFIL‐A, and BACTOFIL‐B) on soil microbial‐biomass content and activity, net N mineralization in soil, and growth of Lolium perenne. According to the manufacturers, the products tested are based on microbial inoculants or organic growth stimulants, and are supposed to influence soil microbial properties and improve soil conditions, organic‐matter decomposition, and plant growth. In the incubation experiment (40 d, 20.6°C, 50% maximum water‐holding capacity), EM was repeatedly applied to soil together with different organic amendments (nonamended, chopped straw, and lupine seed meal). Under the experimental conditions of this study, no or only marginal effects of EM on organic C, total N, and mineral N in soil could be observed. In soil treatments without any organic amendment, EM suspension slightly enhanced microbial activity measured as soil CO₂ evolution. In soil with easily degradable plant residues (lupine seed meal), EM suspension had a suppressive effect on microbial biomass. However, comparisons with sterilized EM and molasses as the main additive in EM suspension showed that any effect of EM could be explained as a pure substrate effect without the influence of added living organisms. In the pot experiment with Lolium perenne (air‐conditioned greenhouse cabin, 87 d, 16.8°C, 130 klxh d^–1 light quantity), the products EM, BIOSTIMULATOR, BACTOFIL‐A, and BACTOFIL‐B were tested in soil with growing plants. The products were repeatedly applied for a period of 42 d. Within this study, no effects of the different biofertilizers on mineral N in soil were detectable. There were clear suppressive effects of all tested biofertilizers on microbial‐biomass content and activity. Comparisons with sterilized suspensions showed that the effects were not due to living microorganisms in the suspensions, but could be traced back to substrate‐induced processes.     

转双价棉种植对土壤酶活性及土壤微生物的影响

转 Bt＋CpTI基因棉因其具有强有效的杀虫性能,近年来种植面积不断扩大,其种植对土壤生态系统的影响是环境风险评价的重要组成部分。本研究以转基因双抗虫棉sGK321和亲本同源常规棉石远321为研究对象,通过比较分析了不同生育期（苗期、蕾期、花铃期、吐絮期）转双价基因棉与其非转基因棉亲本在大田条件下种植13年后,根围土壤酶活性（脲酶、碱性磷酸酶、过氧化氢酶）变化和土壤可培养微生物（细菌、真菌、放线菌）数量的变化。结果表明,转双价棉与常规棉根际土壤脲酶、过氧化氢酶和碱性磷酸酶活性以及土壤可培养细菌、真菌、放线菌数量随生育进程的推进变化趋势一致。土壤细菌和放线菌数量在同一时期均无显著差异;土壤脲酶、过氧化氢酶、碱性磷酸酶和土壤真菌数量在一些时期差异明显,转双价棉脲酶苗期、碱性磷酸酶苗期和蕾期,土壤可培养真菌数量花铃期低于常规棉,土壤过氧化氢酶苗期、碱性磷酸酶花铃期高于同源常规棉。聚类分析表明,土壤酶活性和土壤微生物种群数量变化主要受生育期的影响,而转双价 Bt＋CpTI种植对土壤酶活性和微生物影响是有限的。     

Investigation of Associations Between Rhizosphere Microorganisms and the Chemical Composition of Flue-Cured Tobacco Leaves Using Canonical Correlation Analysis

Canonical correlation analysis was applied to determine the relationship of rhizosphere microorganisms to common chemical components in flue-cured tobacco leaves. The results were as follows: (1) The chemical composition of the tobacco was related to the major microbial physiological groups in the rhizosphere soil. No close relationship was found with the populations of bacteria, fungi, and actinomycetes. (2) Greater contents of total nitrogen and potassium in tobacco leaves were associated with larger populations of aerobic nitrogen-fixing bacteria and with smaller populations of aerobic cellulose-decomposing bacteria. In addition, potassium content was also negatively correlated with nitrosobacteria counts but showed no close relationship with the potassium bacteria in the rhizosphere. The nicotine content was associated with greater populations of nitrosobacteria and nitrobacteria, and the content of water-soluble total sugar was positively correlated with the counts of nitrosobacteria.     

Rock phosphate-enriched organic fertilizer with phosphate-solubilizing microorganisms improves nodulation,growth, and yield of legumes

ABSTRACT

Phosphorus availability from rock phosphate (RP) can be increased via composting with organic fertilizer and phosphate-solubilizing microorganisms (PSMs) in the soil. Incubation and pot experiments were conducted to investigate the comparative efficacy of RP-enriched organic fertilizer with PSMs vs. diammonium phosphate (DAP) as a control to enhance the production of legumes. In incubation studies, RP-enriched organic fertilizer with PSM₂ significantly increased soil aggregate stability (37%) and P-release (2.35 folds) as compared to control, whereas, in pot study, the number and dry weight of nodules plant^?1, shoot length, number of pods plant^?1, and grain yield of chickpea increased by 23%, 13%, 17%, 15%, and 15% with RP-enriched organic fertilizer + PSM₂ compared to control. Similarly, nitrogen and phosphorus contents in straw (11 and 42% respectively) and grains (11 and 13% respectively) and protein contents (16%) of chickpea were also increased. A similar trend was observed regarding the growth and yield parameters of lentil. The use of RP-enriched organic fertilizer with PSM could produce results similar to that of DAP for the optimum production of legumes.     

生物发酵肥对温室黄瓜土壤微生物组成的影响

以大棚黄瓜根区土壤为研究对象,测定了不同施肥方式下温室黄瓜地土壤微生物3大类群和主要功能群组成及土壤微生物量碳(microbial biomass carbon,MBC),研究了温室中不同施肥方式对黄瓜根区土壤微生物组成及土壤MBC(土壤微生物生物量碳)的影响,探讨了微生物发酵有机肥对土壤肥力的影响。结果表明,土壤中细菌、真菌、放线菌数量由高到低的顺序依次为:发酵肥>发酵肥+50%化肥>常规施肥>普通有机肥>CK;土壤微生物综合指标Shannon-Wiener指数以生物发酵肥最高;氨化细菌、固氮菌及纤维素分解菌数量以生物发酵肥最高,硝化细菌数量以发酵肥+50%化肥处理最高;生物发酵肥和发酵肥+50%化肥两处理的MBC均显著高于常规施肥。施用微生物发酵有机肥可显著增加土壤微生物数量及微生物的群落多样性,并有助于提高土壤综合肥力。     

施肥对植烟土壤微生物的影响

利用7年的定位施肥试验,研究了不施肥（CK）、 单施化肥（CF）和有机无机肥配施（MCF）对植烟土壤微生物的影响。平板计数、 微生物碳、 氮含量和磷脂脂肪酸的测定结果均表明,土壤微生物数量以有机无机配施的处理最多,单施化肥次之,不施肥最少。在3种施肥处理的土壤中,分别检测出20（CK）、 27（CF）和31种（MCF）磷脂脂肪酸; 施肥提高了代表细菌（1220碳）和放线菌（10Me17: 0和10Me18: 0）的磷脂脂肪酸; 但是,代表真菌的磷脂脂肪酸18: 19c无显著变化（CF）或显著降低（MCF）。有机无机肥配施处理显著提高了土壤微生物的多样性指数和优势度指数,说明有机无机配施改善了土壤生态环境,微生物种群丰富,优势种群突出。在土壤自生固氮菌、 磷细菌和钾细菌中,分离率最高的是芽孢杆菌属,在26%50%之间变化。有机无机肥配施还提高了这3种有益微生物的数量,单施化肥则无显著影响。此外,在有机无机肥配施的土壤中,自生固氮菌、 磷细菌和钾细菌的多样性指数、 均匀度指数和优势度指数均较高。从土壤微生物的角度看,生产上采用有机无机肥配施很有必要。     

作物种植模式对土壤微生物和农田有害生物的影响

土壤是联系地上和地下生态系统的纽带,土壤微生物在土壤养分循环和作物吸收中起关键作用,被称为土壤质量的指标。土壤微生物通过分解土壤有机物,促进养分循环利用,并调控植物生长发育,随着现代农业种植结构的变化,特别是种植制度的改变,地上植物种类和生长状况常常影响土壤中微生物的群落结构和多样性,调控着作物生长发育,农田有害生物的发生,而影响农作物生产。综述了现代农业中几种主要种植模式,如轮作、连作和覆盖等对土壤微生物群落结构及与农作物有害生物的影响,强调科学合理选择种植模式的重要性,最后,讨论了这些种植模式有待深入研究的一些关键问题。     

秸秆生物反应堆与菌肥对温室番茄土壤微环境的影响

为研究秸秆生物反应堆、微生物菌肥及两者配套措施对土壤理化性质和微生物功能多样性,以及作物生长的长期影响,试验以传统种植方式为对照(CK,常规栽培),研究了菌肥(T1,微生物菌肥4 kg/667 m2)、内置式秸秆生物反应堆(T2,秸秆(4 t/667 m2)+发酵沟菌剂(8 kg/667 m2)+腐熟猪粪(600 kg/667 m2))及2种措施配套处理(T3,秸秆(4 t/667 m2)+发酵沟菌剂(8 kg/667 m2)+微生物菌肥(4 kg/667 m2)+腐熟猪粪(600 kg/667 m2))对土壤理化性质和微生物功能多样性的影响。结果表明:1)与CK相比,秸秆生物反应堆能够在一定时期内提高土壤含水率;而菌肥能够在一定时期内降低土壤含水率,秸秆生物反应堆能够显著降低土壤酸性和电导率(EC,electrical conductivity)值,缓冲土壤酸化和次生盐渍化;而单施菌肥对土壤酸碱性和EC值没有显著影响。2)秸秆生物反应堆(T2)增加了土壤中有机质的含量和土壤微生物量,降低土壤中速效磷、钾的含量;微生物菌肥(T1)降低了土壤中有机质含量和微生物量,而显著提升了土壤的速效磷、速效钾含量,两种措施配套处理效果则更明显。3)菌肥能够改善土壤微生物对多聚物、碳水化合物和氨基酸的利用效率,而秸秆生物反应堆能够促进土壤微生物对于一部分氨基酸、羧酸类、酚酸类和胺类物质的利用。而2种措施同时使用时,其促进和改善微生物碳代谢能力的作用则更加显著。4)各处理均能够在一定程度上增加各年度番茄产量。综合考虑,认为内置式秸秆生物反应堆和菌肥配套处理(T3)能够更好的改善和修复日光温室连作土壤,增加作物产量,是一种较为有效的农艺措施。     

猪场沼液絮凝上清液的紫外线杀菌效果

猪场沼液中含有大量的微生物,为确保其排放或循环利用的卫生和环境安全,应对其进行有效的杀菌处理,目前国内沼液杀菌相关的研究缺乏。由于猪场沼液原液的色度和浊度很高,紫外线透过率很低,采用紫外线杀菌前需要对其进行预处理。该研究采用絮凝方法处理猪场沼液,对所获取的不同透射率沼液絮凝上清液进行杀菌试验,试验以细菌总数、大肠菌群和粪大肠菌群的数量变化及其杀菌率为指标,在4种沼液絮凝上清液透射率(0.01%、0.69%、3.78%和8.54%)、3种紫外线杀菌装置内水深(1、2和3 cm)和5种水力停留时间(1、5、10、15、20和30 min)试验条件下,探讨紫外线对沼液絮凝上清液杀菌的可行性及其运行效果。结果表明,絮凝上清液透射率(T254)、紫外线杀菌装置内水深和水力停留时间等因素对紫外线的杀菌效果均有极显著影响(P0.01),3种因素之间均有极显著的交互作用(P0.01)。试验紫外线灯管强度为395μW/cm2,当沼液絮凝上清液的透射率为0.69%、水力停留时间15 min和紫外线杀菌装置内水深2 cm时,紫外线对细菌总数、大肠菌群和粪大肠菌群的杀菌率分别为(99.99±1.20)%、(99.99±1.43)%和(100.00±0.01)%,使沼液絮凝上清液中粪大肠菌群的数量从3.9×106个/L下降至检出限(3个/L)以下,紫外线杀菌处理出水达到现行国家标准的无害化卫生要求,该研究可能为沼液的紫外线杀菌技术的深入研究和沼液安全循环利用提供参考。