混合培养对固氮菌和纤维素分解菌生长及固氮的影响

对筛选的自生固氮菌和纤维素分解菌进行混合培养,研究了菌数与菌液含氮量的变化情况,并与各单独培养进行了比较。实验证明在混合培养条件下,两种菌能相互利用、相互促进,混合培养液的菌数增加,固氮菌的固氮能力提高。这两种菌可混合培养制成混合菌剂。     

混合培养对固氮菌和纤维素分解菌生长及固氮的影响

对筛选的自生固氮菌和纤维素分解菌进行混合培养,研究了菌数与菌液含氮量的变化情况,并与各单独培养进行了比较。实验证明：在混合培养条件下,两种菌能相互利用,相互促进,混合培养液的菌数增加,固氮菌的固氮能力提高。这两种菌可混合培养制成混合菌剂。     

不同培养条件对堆肥中降解纤维素林丹复合菌系分解能力的影响

该论文作者对一组高效降解纤维素林丹的复合微生物菌系在不同培养条件下的降解能力进行了研究,结果表明,该复合菌系对滤纸、脱脂棉、稻秸粉和锯末等不同纤维素材料均有较强的降解能力,但相比之下对天然纤维素含量高的碳源(如滤纸、脱脂棉)降解效果更好.最佳的碳源浓度为0.5%和1%.有机复合氮源对降解效果的影响明显优于无机氮源,氮源浓度以0.25%和0.5%为宜.它能在较大的pH值范围内均保持高的纤维素降解活性,但在中性及偏碱环境中活性最强.在纤维素降解最佳的pH值7～9范围内,也同样有利于林丹的降解,而在纤维素降解较少的pH值为10的条件下,林丹的降解率仍高达49.6%.培养复合菌系的溶解氧范围以0.07～0.13 mg/L,为宜,最适生长和降解纤维素林丹的温度为50～60℃.     

高效纤维素优势分解菌的筛选和鉴定

本试验基于获得高效纤维素优势分解菌的目的,通过分离纯化初步得到30株菌株,利用刚果红染色法初筛共得到14株纤维素分解菌,并通过滤纸条崩解实验进一步进行筛选得到5株效果较好的纤维素分解菌,通过发酵产酶利用DNS显色法测定CMC酶活力和FPA酶活力最终确定了4株优势纤维素分解菌,通过测定4株菌株的羧甲基纤维素酶(CMCase)、滤纸酶(FPA)以及β-葡萄糖苷酶(β-Gase)活,验证4株纤维素优势分解菌的产酶能力,并分别命名为X-1、X-6、X-7和X-11,并将该4株优势纤维素分解菌应用于秸秆的液态发酵,其对秸秆的降解率较自然降解相比,降解率分别提高了31.92%、40.15%、35.29%和39.98%。对4株优势菌株进行了分子鉴定,根据16S r DNA序列比对结果表明,菌株X-1、X-7和X-11均为粪产碱杆菌;菌株X-6属于解糖假苍白杆菌。     

稻草秸秆纤维素分解菌的分离筛选

本研究基于获得高效木质纤维素分解菌的目的,以刚果红纤维素琼脂和滤纸条培养基为初筛培养基,从分离获得的124株真菌中筛选出透明圈与菌落直径比值较大、滤纸条分解能力较强的11个菌株。经液体发酵,测定其酶活力,复筛得到羧甲基纤维素酶活和滤纸酶活均较高的4个菌株;并进行了不同碳源和不同pH对筛选菌株产酶能力的影响试验,发现不同菌株对不同纤维素物质的分解能力不一样,同一菌株对不同纤维素碳源的利用能力也不相同。     

水热条件和施肥对黑土中微生物群落代谢特征的影响

选择位于我国东部3个不同气候带(温带、暖温带、中亚热带)的农业生态试验站(海伦站、封丘站、鹰潭站),设置水热变化梯度下的土壤置换试验,利用Biolog方法,研究了水热因子和施肥对单作玉米的黑土中微生物群落的影响。结果表明,在3种气候条件下,施用NPK肥均提高了黑土中细菌群落的碳源代谢活性(Average well color development,AWCD值表示)。在玉米抽雄期,施肥处理(NPK)黑土中AWCD值大小顺序为:鹰潭站(中亚热带)>海伦站(温带)>封丘站(暖温带),不施肥(CK)处理为:鹰潭站(中亚热带)>封丘站(暖温带)>海伦站(温带)。说明不施肥时黑土中微生物代谢活性随月均温度的提高而增加,而施肥和降水影响了温度对黑土中微生物代谢活性的作用。主成分分析表明,黑土中微生物群落代谢特征在海伦站(温带)和封丘站(暖温带)之间变化较小,而在鹰潭站(中亚热带)黑土中微生物群落的代谢指纹发生明显改变。气候条件变化导致的黑土中微生物代谢碳源的分异主要表现在:α-丁酮酸、腐胺、D,L-α-甘油、L-苏氨酸(r>0.9);而施肥导致的黑土中微生物代谢碳源的分异主要表现为:β-甲基-D-葡萄糖苷、葡萄糖-1-磷酸盐和丙酮酸甲脂。总体上,不同气候带水热条件的变化和施肥均影响了黑土中微生物群落的代谢活性和代谢特征的变化。     

不同施肥制度对玉米生育期土壤微生物量的影响

通过测定不同施肥制度下玉米土壤微生物量碳、氮的动态变化,探讨了不同施肥制度对玉米土壤的培肥效应。研究结果表明,与无肥、单施有机肥、单施化肥相比,有机肥与N、P、K肥配合施用能显著增加玉米各生育时期的土壤微生物量碳、氮,促进土壤微生物量显著增长,增强了土壤养分容量的供应强度,有利于培肥土壤。     

祁连山不同森林植被类型对土壤微生物影响的研究

通过研究不同植被类型下土壤微生物区系、土壤酶活性和土壤生化作用强度,分析了祁连山不同森林植被类型土壤微生物的数量变化、垂直分布、土壤呼吸强度和纤维素分解能力等的变化规律和特征。     

水热条件和人类活动对山西省植被覆盖变化的影响

基于山西省1999—2010年的SPOT Vegetation数据及气象资料,运用Sen趋势度+Mann—Kendall法、残差分析法和相关分析法,对山西省近12a植被覆盖的时空变化进行了分析,探讨了水热条件与人类活动对植被覆盖变化的影响。从年际变化来看,1999—2010年山西省生长季植被NDVI呈现显著上升趋势,其增加速率为0.199 4/a;从空间格局来看,大部分地区NDVI有增加趋势,其中极显著增加的区域占72.94%,主要分布在山西省的黄土丘陵沟壑区及山区;NDVI减少区域极小,仅占0.21%,呈不均匀零星分布。降水量与生长季NDVI的相关性较高,从整体上呈现出由北向南逐渐减少的特点,其中98.54%的区域呈正相关关系;此外,气温与生长季NDVI的相关性较低,平均相关系数仅为-0.415。人类活动对山西省植被覆盖变化的正面和负面作用并存,但正影响远大于负影响,说明近年来退耕还林草以及水土流失治理的生态效益正在显现。     

石油降解菌的筛选、鉴定及菌群构建

从胜利油田石油污染土壤中富集、分离得到236株能以石油作为唯一碳源和能源的石油降解菌株；采用选择性培养基进行复筛得到直链烷烃降解菌31株、环烷烃降解菌28株、芳烃降解菌3株以及表面活性剂产生菌24株；从3种不同烃类降解菌和表面活性剂产生菌中选择菌株，构建石油降解微生物菌群，结果表明，由菌株SL-51、SL-84、SL-133和SL-163组成的菌群c9降解石油能力最强，菌群C9在含原油浓度为0．5％的无机盐培养液中，5d内原油的降解率达到了55．5％；气相色谱分析结果证明，菌群C9能有效降解原油中的饱和烃和芳烃组分；通过16SrDNA序列分析，初步鉴定SL-51和SL-163属于红球菌属（Rhodococcus spp．），SL-84、SL-133两株菌分别属于苍白杆菌属（Ochrobactrum sp．）、铜绿假单胞菌属（Pseudomonas sp．）。     

Effects of filter type and extraction efficiency on nitrogen mineralization measurements using the aerobic leaching soil incubation method

Aerobic incubation of soils with sequential leachings to extract mineralized N is often used to determine N mineralization potential and N availability in the laboratory. This study used tropical forest soils with differing mineralogy and texture to address: (1) the effects of filter type and equilibration time on soil moisture and N mineralization and (2) the N extraction efficiency of 0.01 M CaCl₂, minus-N nutrient solution (containing 0.004 M CaCl₂) and 2 M KCl. Use of glass microfiber filters compared to cellulose acetate or polyethersulfone membrane filters resulted in a lower moisture content for both low-and high-clay soils. However, filter type did not affect N mineralization. Under 47 kPa suction, soil moisture equilibration occurred between 240 and 360 min regardless of filter type. Extraction efficiency for mineralized N using 0.01 M CaCl₂ or minus-N nutrient solution was lower in forest soils of smectitic mineralogy and soils with a higher proportion of macroaggregates. However, with the exception of allophanic soils, the cumulative amount of N mineralized measured in a long-term incubation for approximately 1 year was not different when either a leaching or an unleached incubation method was used. These results indicate that researchers may wish to conduct preliminary evaluations to determine whether their incubation method will achieve a desired uniform moisture level and N extraction efficiency.     

Effects of transient anaerobic conditions in the presence of acetylene on subsequent aerobic respiration and N2O emission by soil aggregates

Our objective was to assess the effect of anaerobic conditioning in the presence of acetylene on subsequent aerobic respiration and N₂O emission at the scale of soil aggregates. Nitrous oxide production was measured in intact soil aggregates Δ (compacted aggregates without visible porosity) and Γ (aggregates with visible porosity) incubated under oxic conditions, with or without anaerobic conditioning for 6 d. N₂O emissions were much higher in aggregates that had been submitted to anaerobic conditioning than in aggregates that did not experience this conditioning, although very little NO₃⁻ remained in soil after the anaerobic period. ¹⁵N isotope tracing technique was used to check whether N₂O came from nitrification or denitrification. The results showed that denitrification was the major process responsible for N₂O emissions. The aerobic CO₂ production rate was also measured in intact soil aggregates. It was greater in aggregates submitted to anaerobic conditioning than in those that were not, suggesting that the anaerobic conditioning lead to an accumulation of small compounds including fatty acids that are readily available for microbial decomposition in aerobic conditions. This process increases the aerobic CO₂ production and favours the N₂O emissions through denitrification.     

培养温度和土壤类型对土壤硝化特性的影响

采用室内恒温好气培养方法,研究了温度(15℃、20℃、25℃和30℃)和土壤类型(黑土、潮土和红壤)对土壤硝化率的影响。氮素加入比率为N 200 mg kg-1土壤。结果表明:在15～30℃培养范围内,随着培养温度的升高,硝化率呈升高趋势;硝态氮累积量和培养积温(培养温度×培养天数,温度以0℃为基准)之间的关系可用单参数指数模型表示。在相同培养温度条件下,供试土壤硝化率从大到小的顺序为:高有机质含量潮土>低有机质含量潮土>高有机质含量黑土>低有机质含量黑土>低有机质含量红壤>高有机质含量红壤。硝化率(25℃恒温培养)与土壤全磷含量、全钾含量、黏粒含量及pH呈极显著相关;土壤pH和全磷含量解释了硝化率差异的98.1%。土壤pH是影响其硝化率的主要因素,并抑制土壤有机质含量及温度对硝化率的影响。     

Effects of nitrite toxicity on soil bacteria under aerobic and anaerobic conditions

Isolates of a soil Pseudoimonas, as well as other soil bacteria, showed a different sensitivity towards NO^?₂ when grown under aerobic or anaerobic conditions. The tolerance to NO^?₂ was increased in the presence of O₂: for instance, a concentration of $\text{200parts}\text{10}{}^6$ of NO^?₂-N proved to be toxic to a Pseudomonas sp. under anaerobic conditions, whereas over $\text{400 parts}\text{10}{}^6$ were needed aerobically to suppress its growth completely. The addition of NO^?₃ as an electron acceptor for anaerobic respiration did not overcome the inhibitive effect of NO^?₃. The pH range, at which NO^?₂ was utilized anaerobically, was narrowed with increasing NO^?₂ concentration (pH 6.8–8.8 at $\text{70 parts}\text{10}{}^6$ of NO^?₂-N and 7.4–8.5 and $\text{140 parts}\text{10}{}^6$ of NO^?₂-N).Tolerance to nitrite varied considerably among the bacteria tested. Each species was able to overcome the inhibitory effect of NO^?₂ up to a certain concentration, while the length of the lag phase was related to NO^?₂ concentration.     

Influence of the water regime on denitrification and aerobic respiration in soil

Summary The influence of soil moisture on denitrification and aerobic respiration was studied in a mull rendzina soil. N₂O formation did not occur below –30 kPa matric water potential (_m), above 0.28 air-filled porosity (a) and below 0.55 fractional water saturation (_v/PV volumetric water content/total pore volume). Half maximum rates of N₂O production and O₂ consumption were obtained between _m = –1.2 and –12 kPa,a = 0.05 and 0.23, and _v/PV = 0.63 and 0.92. No oxygen consumption was measured at _v/PC 1.17. O₂ uptake and denitrification occurred simultaneously arounda = 0.10 (at _m = –10 kPa and _v/PV = 0.81) at mean rates of 3.5 µl O₂ and 0.3 µl N₂ h^–1g^–1 soil. Undisturbed, field-moist soil saturated with nitrate solution showed constant consumption and production rates, respectively, of 0.6 µl O and 0.22 µl N₂O h^–1g^–1 soil, whereas the rates of air-dried remoistened soil were at least 10 times these values. The highest rates obtained in remoistened soil amended with glucose and nitrate were 130 µl O₂ and 27 µl N₂O h^–1g^–1 soil.     

Effects of soil invertebrates on the survival of some genetically engineered bacteria in leaf litter and soil

Seven bacterial strains, most of them bearing natural or recombinant plasmids, were introduced in oak leaf litter or soddy-podzolic soil. In these substrata, which contained litter-dwelling diplopods and isopods, or endogenic earthworms, bacteria survival was followed. In the absence of the animals, the numbers of introduced strains gradually decreased. In the presence of the animals, plasmid-bearing strains of Pseudomonas putida survived at 10⁵–10⁷ CFUs g^-1 up to 1.5 months in both leaves and soil. The total numbers of bacteria found in excrements from the soil macrofauna were 5–15 times higher than in the food. The numbers of P. putida in the excrements were equal to or higher than in the food. The numbers of Pseudomonas stutzeri JM302 (pLV1013) and Azospirillum brasiliense ATCC29710 (pFACII) in the excrements were always 2–10 times lower than in the food. The digestive fluid taken from the middle part of the gut of the diplopod Pachyiulus flavipes showed a strong antibacterial activity. Those bacteria with lower survival in the gut appeared to be more sensitive to digestion by the midgut fluid. In contrast, the hindgut fluid did not suppress the viability of P. stutzeri JM302 (pLV1013). We postulate that the introduced bacteria partially survive the midgut passage and then multiply with a high growth rate in the hindgut of the animals. The environmental consequences of the interactions between soil invertebrates and the released bacteria are discussed.Dedicated to Professor J. C. G. Ottow on the occasion of his 60th birthday     

Influence of growth-promoting bacteria on the growth of wheat in different soils and temperatures

Plant-growth-promoting bacteria isolated from the rhizosphere, phyllosphere and soil of the root zone in different climatic regions of Germany and Uzbekistan were analysed for plant-growth-promoting effects and nutrient uptake on winter wheat on different soils and under different temperature regimes. The investigations were carried out in pot experiments using loamy sand and sandy loam soils from Müncheberg, Germany and Calcisol soil from Tashkent, Uzbekistan. The temperature and soil types were found to influence growth-promoting effects. Inoculation with bacterial strains Pseudomonas fluorescens PsIA12, Pantoea agglomerans 050309 and Mycobacterium sp. 44 isolated from Müncheberg (semi-continental climate) was found to significantly increase the root and shoot growth of winter wheat at 16 °C compared to 26 °C in loamy sand. Mycobacterium phlei MbP18 and Mycoplana bullata MpB46 isolated from Tashkent (semi-arid climate) were found to significantly increase the root and shoot growth of winter wheat in nutrient-poor Calcisol at 38 °C as well as in nutrient-rich loamy sand at 16 °C. Bacterial inoculation also resulted in significantly higher N, P, and K contents of plant components. The bacteria isolates were able to survive in the rhizosphere and in the soil of winter wheat after root and shoot inoculation.