高含固率木质纤维素厌氧发酵物总DNA的4种提取方法比较

不同的样本特性和提取方法对获得微生物总DNA的质量有重要影响。文章基于高含固率木质纤维素厌氧发酵物腐殖酸、酚类物质含量高、质地均一性差、微生物浓度低的特点,研究了4种方法提取不同高含固率粪秸厌氧发酵物中微生物总DNA的效果。结果表明,常规的十二烷基磺酸钠法(sodium dodecyl sulfate,SDS)、十二烷基磺酸钠和溴化十六烷基三甲铵结合法(sodium dodecyl sulfate and cetyltrimethyl ammonium bromide,SDS-CTAB)和商业的粪便试剂盒法提取的DNA质量均较差,SDS法和试剂盒法未能获得聚合酶链式反应(polymerase chain reaction,PCR)扩增目的条带,SDS-CTAB法得到的条带较模糊;改进SDS-CTAB法获得的DNA杂质少、纯度高,具有较好的稳定性,A260/A280和A260/A230值分别为1.74~1.86和1.65~1.86,每克样品的DNA浓度在50 ng·μL^-1以上,电泳条带单一齐整、清晰明亮,PCR扩增的目的条带清晰度高,适宜后续分子生物学技术的分析。林格氏液洗脱、聚乙烯吡咯烷酮-40(Polyvinyl Pyrrolidone-40,PVP-40)洗涤液除杂以及裂解液和多种酶联合破壁是改进SDS-CTAB法获得该类专一性样本高质量微生物总DNA的关键步骤。     

Innovative liquid formulation of digestates for producing a biofertilizer based on Bacillus siamensis: Field testing on sweet pepper

A biofertilizer (BF) based on the plant growth promoting rhizobacterium (PGPR) Bacillus siamensis was produced using anaerobic digestate (AD) as the main ingredient of the growth medium, alongside a carbon source from residual origin. The use of residues for the growth of PGPR reduces the production costs of biofertilizers, but makes an assessment of the possible toxicity of residues for the bacteria or plants necessary. Therefore, the growth medium of PGPR was first optimized using the response surface methodology (RSM), followed by phytotoxicity tests and a field trial of the BF in a sweet pepper (Capsicum annuum L.) crop at two different locations. AD at 50% dilution, supplemented with 2.3% sugar beet molasses, was the optimum growth medium for producing the BF, with a bacterial concentration of 10⁹ cfu mL⁻¹. In the field trial, the treatments inoculated with BF and fertilized with decreased mineral N (80%) produced significantly better yields per ha than the controls with decreased N (80%) and full N (100%) without BF. This indicates improved efficiency of N use by the crop, as a consequence of the use of BF.     

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。     

Amount and speciation of N leached from a sandy soil fertilized with urea,liquid digestate,struvite and NH4-enriched chabazite zeolite-tuff

The large use and the bad management of fertilizers that are applied to soil for improving crop production have dramatically impaired soil, water, and air quality. To meet the requirements to reduce nitrogen (N) losses and all the related negative impacts on the environment and food production, it is mandatory to substitute or at least partially substitute the use of inefficient and unsustainable fertilizers with more efficient alternatives. The aim of this paper was to address the amount and speciation of the N released by a sandy soil fertilized with “slow-release fertilizers” and traditional fertilizers (urea and liquid digestate) by means of a series of column leaching experiments. The slow-release alternatives were represented by NH₄-enriched zeolitic tuff and struvite, both obtained by recovering the N from liquid digestate. The treatments consisted of sandy soil fertilized with (i) urea (U) (ii) liquid digestate (LD), (iii) NH₄-enriched zeolitic tuff (N-CHA) and (iv) struvite (STRV). Eight different flushing events were performed over 38 days, leachates were collected and analysed for total Kjeldahl N, organic-N, NH₄⁺-N, NO₃⁻-N, NO₂⁻-N and pH. U and LD lost the majority of N within the first 2 flushing events as organic N and NH₄⁺-N, respectively. On the other hand, STRV and N-CHA lost less N over the whole course of the experiment and with more balanced speciation. The mass balance outlined that after the experiment, native soil N was mined in U and LD treatments while in N-CHA and STRV a fraction of N from the fertilizers was still present. The results showed a slow release of N which can be used more efficiently in agricultural applications, minimizing the N losses.     

生物炭对混施沼肥秸秆还田腐解特性的影响

为提高秸秆与沼肥同步翻埋还田的腐解效果,在室温条件下,秸秆中混施沼肥,采用网袋法模拟翻埋还田,在105 d的试验周期内,探讨在土壤中配施生物炭对秸秆与沼肥同步翻埋还田腐解的影响规律。结果表明,在土壤中配施生物炭能显著提高秸秆各指标的降解速度,且不同土壤之间玉米秸秆的降解率表现为砂土组大于壤土组,添加生物炭组大于未添加生物炭组,试验结束时,壤土组、壤土+生物炭组、砂土组、砂土+生物炭组的降解率分别为69.96%、74.63%、78.19%和79.14%;腐解前49 d为秸秆各组分的快速腐解期,后期腐解速率逐渐变慢;秸秆的降解率与纤维素降解率具有显著的相关性,添加生物炭对木质素的降解具有显著的促进作用,且木质素的降解与有机碳的降解呈正相关性。     

施用沼液对设施番茄生长与土壤生态环境的影响

为探求番茄全生育期施用沼液对其生长及土壤环境的影响,系统研究了沼液配比及灌溉量对番茄农艺性状、品质、产量、土壤理化环境和土壤生物学特性的影响。结果表明:T3处理(沼液配比1∶4,作物-皿系数(Kc)为1. 0)番茄的株高、茎粗和单株叶面积均为各处理最大,分别比纯水处理(C0)高24. 11%、15. 59%和33. 92%。与C0处理相比,灌施沼液可以增加番茄产量、改善番茄品质和口味,T2处理(沼液配比1∶4,Kc为0. 8)能够获得最高产量、最高的维生素C及可溶性总糖含量。灌施沼液可以降低土壤容重和土壤p H值,增大土壤总孔隙度及土壤饱和导水率,灌施沼液各处理土壤有机质含量随土层深度呈先增加后降低的趋势。灌施沼液还可以增加各生育期内细菌、真菌、放线菌数量,其中土壤细菌、真菌数量均表现出自苗期到果实膨大期呈增加趋势,阈值出现在果实膨大期,而后逐渐降低,放线菌数量自苗期到果实成熟期呈逐渐增加的趋势,阈值出现在果实成熟期。施用沼液各处理土壤中过氧化氢酶、蔗糖酶、脲酶的活性在番茄生育期内分别表现为持续增大、先增加后降低和先降低后上升的变化规律,阈值分别出现在果实成熟期和果实膨大期、开花结果期。综合分析试验结果,T2处理更有利于番茄的生长、产量品质的形成以及土壤环境的改善。     

鸡粪发酵液培养的小球藻水热液化制备生物原油及其特性

为探索沼液资源再利用,以鸡粪沼气发酵液培养的小球藻为原料,采用水热液化技术制备生物原油。采取正交试验,在温度250~330℃、时间30~90 min及含固量15%~25%下,探讨了水热反应后各相产物特性及元素回收效率。生物原油产率为13.23%~23.83%,最高产油率在330℃、60 min、15%时取得。生物原油中碳、氢及氮回收率分别是16.13%~31.14%、19.18%~34.89%及5.97%~14.32%,最高碳回收率及最低氮回收率分别在330℃、60 min、15%及250℃、30 min、15%时获得。水热液化各相产物中,碳、氢及氮回收率在水相中占主导地位,分别为48.74%~60.43%、46.81%~62.13%及74.84%~82.67%。热重分析暗示生物原油可能适合制备润滑油。此外,GC-MS分析表明生物原油中烃类物质质量分数为16.14%~24.91%,主要为低碳链烃类,如甲苯及二氢茚等。     

生物肥料磷的利用效率：生物有效性和组分

Although to date some technologies producing bio-based phosphorus (P) fertilizers have been proposed and implemented, the efficient use of the recovered products is still limited due to legislative constraints and lack of insights in the P release with time and in the corresponding mechanisms. The aim of this work was to evaluate the fertilizer performance in terms of P release and use efficiency of recovered struvite, FePO₄-sludge, digestate, and animal manure as compared to fossil reserve-based mineral triple superphosphate (TSP). First, product physicochemical characteristics and P fractions in the context of European fertilizer legislation were assessed. Next, a controlled greenhouse experiment was set up to evaluate plant reactions as well as changes of P availability in a nutrient-rich sandy soil with high P status and a nutrient-poor Rheinsand soil with low P status. Soil P fractions were determined in the extracts with water, ammonium lactate and CaCl₂, and in soil solution sampled with Rhizon soil moisture samplers. Based on all results, it is worth conducting long-term field trials to evaluate the P release effect of struvite and digestate as compared to animal manure and TSP on different soil types with varying P status. These products showed promise as sustainable substitutes for conventional P fertilizers and could contribute to a more efficient use of P in agriculture. A refined classification of P application standards/recommendations in terms of soil P status, soil texture, and fertilizer characteristics, next to the crop P demand, is recommended. Moreover, the additional use of Rhizon samplers for determination of direct available P, including dissolved organic P, is proposed for better understanding and categorization of different P fertilizers in environmental and fertilizer legislations.