Effects of Low- Intensity Ultrasound Treatment on Excess Sludge

In this study the influence of the low-intensity ultrasound treatment on excess sludge has been observed.The oxygen uptake rate(OUR),soluble chemical oxygen demand(SCOD),soluble total nitrogen(TN) and soluble total phosphorus(TP) were examined for three power levels of 0.03 W/mL, 0.05 W/mL and 0.1 W/mL as well as two time series of 0~5 min and 0~30 min.It showed that there were two stages of ultrasonic treatment: the first stage took place within the flocs in four minutes,in which SCOD,TN,TP were dissolved from flocs.In the second stage,the microbial activities have been strengthened,as well as OUR,TN,TP have increased greatly.     

Study on Genetic Fingerprinting Technique of Microbial Communities

The 99% of all microorganisms in naturecannot be isolated by standard culture methods without conspicuous external characters to classify them morphologically. In addition, classification based on physiological or biochemical features are often fuzzy. Molecular techniques are used for uncultured microorganisms to explore the diversity of microbial communities and novel resources without the need of cultivation. DNA dynamics and cloning of PCR products obtained from environmental DNA is now routinely used to identify microbial populations in microbial ecology. For practical reasons the approach is not suited to study the complex dynamics of microbial communities in environment. Genetic fingerprinting techniques are better tools, which give complement for the traditional microbiological methods. The methods are rapid and relatively easy to perform, and they allow the simultaneous analysis of multiple samples, which makes it possible to compare the genetic diversity of microbial communities from different habitats, or to study the behaviour of individual communities over time.     

园林植物土壤酶活性和微生物活性对盐碱胁迫的响应

以园林植物石楠为试材,通过混合2种中性盐(NaCl和Na2SO4)和2种碱性盐(NaHCO3和Na2CO3)分别模拟不同强度的盐、碱胁迫条件,对园林植物(石楠)进行3年(2015—2017年)的胁迫处理,以期探讨盐碱胁迫对园林植物土壤酶活性和微生物的影响。结果表明:1)土壤中有机酸含量随着盐碱浓度的增加呈逐渐降低趋势。随胁迫强度增加,盐、碱胁迫均使土壤中Na⁺浓度大幅度上升,K⁺浓度大幅度下降,但碱胁迫下Na⁺浓度上升幅度和K⁺浓度下降幅度均大于盐胁迫。2)随着盐碱浓度的增加,土壤中氨基酸类、碳水化合物类、羧酸类、聚合物类、胺类、酚酸类碳源呈逐渐降低趋势,总体而言,碳水化合物和羧酸类碳源是盐碱胁迫下园林植物土壤微生物的主要碳源,其次为氨基酸类、酚酸类和聚合物类,胺类碳源的利用率最小。3)土壤微生物物种丰富度指数(H)、均匀度指数(E)和碳源利用丰富度指数(S)、土壤微生物量碳、微生物呼吸和微生物代谢熵随盐碱浓度的增加而增加。4)土壤糖苷酶、几丁质酶、亮氨酸氨基肽酶、碱性磷酸酶、酚氧化酶δ和过氧化物酶δ随盐碱浓度的增加呈逐渐降低趋势。5)交互作用分析显示,盐胁迫、碱胁迫、盐胁迫×碱胁迫对有机酸、Na⁺、K⁺、Na⁺/K⁺、物种丰富度指数(H)、碳源利用丰富度指数(S)、土壤微生物量碳、土壤微生物呼吸、土壤微生物代谢熵、糖苷酶和碱性磷酸酶具有显著的影响(P<0.05),其中碱胁迫对土壤酶活性和微生物群落多样性的影响高于盐胁迫,并且盐胁迫×碱胁迫的影响高于单独盐胁迫或碱胁迫.     

石灰联合碳铵熏蒸对连作香蕉生长和根际微生物群落结构的影响

摘 要：由于长期连作导致香蕉枯萎病大量爆发,造成香蕉种植面积锐减,已严重影响海南香蕉产业的发展,因而急需寻求能够缓解或克服香蕉连作障碍的有效措施。本实验旨在探究使用绿色土壤熏蒸剂对长期连作蕉园的香蕉枯萎病的防控效果,特别是对植株生长发育、土壤化学性质和根际微生物区系的影响。田间试验共设置两个处理：石灰碳铵熏蒸处理（LAB）和对照处理（CK）。结果表明: LAB处理可以显著降低香蕉枯萎病发病率,与CK处理相比两季分别降低40%和46.62%,显著增加香蕉亩产量,与CK处理相比两季分别增产45.56%和75.99%。LAB处理可以显著提高土壤pH,改善土壤酸化,使酸性土壤维持中性水平,同时,增加土壤有机质含量,并且显著提高土壤速效磷（两季分别提高28.33%和89.14%）和速效钾含量（23.92%和38.67%）。并且LAB处理明显改变香蕉根际微生物群落结构,可以显著降低变形菌门和子囊菌门相对丰度,显著增加放线菌门等相对丰度,同时显著降低病原菌镰刀菌属相对丰度,并且显著提高部分土壤拮抗菌属的相对丰度,如链霉菌属、红球菌属和曲霉属。因此,石灰碳铵熏蒸有效改善香蕉根际微生物群落结构,有效防控香蕉枯萎病的发生并促进其植株生长。     

次生盐化对溪流底栖分解者和凋落物分解的影响

次生盐化是人类活动引起的淡水水体盐度异常增高的现象。目前,次生盐化已经由干旱区的局域环境问题,蔓延成为全球性生态问题,严重威胁淡水生态系统生物多样性、生态系统功能和生态系统服务。然而,次生盐化对溪流生态系统的效应尚不清晰,本研究以分解者亚系统结构和功能为切入点,解析次生盐化对溪流分解者群落和凋落物分解过程的影响,以期为河溪生态系统保护、管理、修复提供理论依据。已有研究表明,在盐化溪流中,（1）细菌群落和真菌群落对盐化过程的响应模式存在显著不同,相应作用路径对凋落物分解过程变化的调控能力也不同,真菌响应更为复杂;（2）盐化可通过致死效应和亚致死效应对底栖动物群落产生显著影响,撕食者通常对盐度敏感,盐化作用下底栖撕食者变化对凋落物分解过程的影响非常重要;（3）凋落物分解速率普遍降低,但凋落物分解过程与水体盐化特征和模式之间的关系尚未确定。后续的研究重点应包括溪流盐化时空动态的生态效应研究、凋落物分解的元素释放动态等过程参数监测、溪流次生盐化与其他因素（全球变化、富营养化、新兴污染物等）的交互作用研究等     

添加芽孢杆菌对草鱼池塘中真核微生物的影响

为了研究添加芽孢杆菌对池塘中真核微生物群落结构和理化因子的影响,采用高通量测序技术分析了实验组(添加芽孢杆菌池塘)与对照组(普通池塘)水体真核微生物群落结构,同时分析了两组池塘的水体理化指标。结果表明:8、9月实验组池塘水体中TN、NH_4~+-N、NO_3~--N含量显著低于对照组(P0.05)。水体中梅尼小环藻(Cyclotella meneghiniana)、红囊藻(Hedriocystis)、蓝隐藻(Chroomonas)、丝孢酵母属(Trichosporon)和小环藻属(Cyclotella)真核微生物丰度显著高于对照组(P0.05)。实验组池塘水体真核微生物Chao1指数和Shannon指数显著高于对照组(P0.05)。实验结果证实:通过向池塘添加芽孢杆菌,可以改变水体中真核微生物群落的结构,从而实现对池塘理化因子的调节。研究结果对于降低水产养殖尾水对水域环境的污染具有一定的意义。     

微生物技术在烟草种植中的应用探究

由于我国科学技术的快速发展,在生物技术领域的研究也取得了很大的进步,微生物技术也 逐渐被广泛应用在农业生产之中。由于微生物可以在土壤中分解一些有害的物质,有效改变土壤环 境,从而促进农作物的生产量以及提供农作物的综合质量,所以也开始在烟草种植中逐步实施。对 此,本文对微生物技术在烟草种植中的应用进行探究,希望能为利用微生物技术进行烟草种植提供参 考作用。     

Effect of transferring lignocellulose-degrading bacteria from termite to rumen fluid of sheep on in vitro gas production,fermentation parameters,microbial populations and enzyme activity

The digestive tract of termite(Microcerotermes diversus) contains a variety of lignocellulose-degrading bacteria with exocellulases enzyme activity, not found in the rumen, which could potentially improve fiber degradation in the rumen. The objectives of the current study were to determine the effect of inoculation of rumen fluid(RF) with three species of bacteria isolated from termite digestive tract, Bacillus licheniformis, Ochrobactrum intermedium, and Microbacterium paludicola, on in vitro gas production(IVGP), fermentation parameters, nutrient disappearance, microbial populations, and hydrolytic enzyme activities with fibrous wheat straw(WS) and date leaf(DL) as incubation substrate. Inoculation of RF with either of three termite bacteria increased(P0.05) ammonia-N concentration compared with the control group(free of termite gut bacteria). Termite bacteria inoculation had no effect(P0.05) on gas production characteristics, dry matter, organic matter and neutral detergent fiber disappearance, pH, and concentration and composition of volatile fatty acids. Population of proteolytic bacteria and protozoa, but not cellulolytic bacteria, were increased(P0.05) when RF was inoculated with termite bacteria with both WS and DL substrates. Inoculation of RF with termite bacteria increased protease activity, while activities of carboxymethyl-cellulase, microcrystalline-cellulase, α-amylase and filter paper degrading activity remained unchanged(P0.05). Overall, the results of this study indicated that transferring lignocellulose-degrading bacteria, isolated from digestive tract of termite, to rumen liquid increased protozoa and proteolytic bacteria population and consequently increased protease activity and ammonia-N concentration in vitro, however, no effect on fermentation and fiber degradation parameters were detected. These results suggest that the termite bacteria might be rapidly lysed by the rumen microbes before beneficial effects on the rumen fermentation process could occur.     

Long-term fertilization leads to specific PLFA finger-prints in Chinese Hapludults soil

Soil microbes play essential roles in the biogeochemical processes of organic carbon and nutrient cycling. Many studies have reported various short-term effects of fertilization on soil microbes. However, less is known about the effects of longterm fertilization regimes on the rhizosphere. Therefore, the objective of this study was to explore how the soil microbial communities in the rhizosphere respond to different long-term fertilization strategies. Based on a 21-year field treatment experiment in Guizhou, China, we extracted phospholipid fatty acids(PLFAs) to determine the microbial community structure in both the non-rhizosphere(NR) and rhizosphere(R). Six treatments were included: no fertilizer(CK), mineral nitrogen fertilizer(N), N with potassium(NK), phosphorus with K(PK), NPK, and NPK combined with manure(MNPK). The results showed that total PLFAs under unbalanced mineral fertilization(N, NK and PK) were decreased by 45% on average in the NR compared with CK, whereas MNPK increased fungi and G~– bacteria abundance significantly in both the NR(by 33 and 23%) and R(by 15 and 20%), respectively. In addition, all microbial groups in the R under these treatments(N, NK and PK) were significantly increased relative to those in the NR, except for the ratio of F/B and G~+/G~–, which might be due to the high nutrient availability in the R. Soil pH and SOC significantly regulated the soil microbial community and structure, explaining 51 and 20% of the variation in the NR, respectively. However, the rhizosphere microbial community structure was only significantly affected by soil pH(31%). We concluded that the soil microbial community in the NR was more strongly affected by long-term fertilization than that in the R due to the rhizosphere effect in the agricultural ecosystem. Rhizosphere nutrient conditions and buffering capacity could help microbial communities resist the change from the long-term fertilization.