Short-term impact of dry olive mill residue addition to soil on the resident microbiota

The short-term response of the resident soil bacterial and fungal communities to the addition of 5% (w/w) of either dry olive mill residue (DOR), DOR treated with Phlebia sp. (PTDOR) or DOR previously extracted with water (WEDOR) was investigated. As opposed to bacteria, the diversity of fungi increased upon the amendments as assessed by denaturing gradient gel electrophoresis of 18S rDNA. Over the first 30 days, phospholipid fatty acids analyses indicated a gradual decrease in the relative abundances of Gram⁺ bacteria (from 44.8% to 37.9%) and a concomitant increase of Gram⁻ bacteria (from 37.3% to 51.2%) in DOR-amended soil. A considerable increase in the fungal/bacterial ratio was observed after 7 days in DOR, WEDOR and PTDOR-amended soils with respect to the control (0.316, 0.165 and 0.265, respectively, vs. 0.011). The overall microbial activity was stimulated by the amendments as indicated by the higher activity levels of both dehydrogenase and fluorescein diacetate hydrolase. These results indicate that DOR at the application level examined is not toxic on soil microorganisms.     

Measurements of total and culturable bacteria in the alfresco atmosphere using a wet-cyclone sampler

Alfresco (def. clean, outdoor) airborne bacteria were collected with a commercially available wet-cyclone bioaerosol sampler to demonstrate its use, sample processing and resultant observations of total and culturable bacteria in mid-summer in the mid-Willamette River Valley, OR. Some critiques of the system are given. The maximum and minimum total and culturable airborne bacterial concentrations in the samples were 5.9 × 10⁵ and 8.8 × 10² cells m⁻³, and 1.3 × 10⁴ and 3.1 CFU m⁻³, respectively. What is thought to be a diurnal cycle was also observed for both fractions with highest concentrations during the day and lowest at dawn and dusk. The culturable bacteria as a percentage of the total, was maximal at mid-day (≈ 3%) and minimal at early morning and late evening (≈ 0.5–2%). Contrarily, the total bacteria in the downwind dust plume of a grass seed combine was 2.9 × 10⁶ cells m⁻³ and of these approximately 73% were culturable, a much greater culturable percentage than found in the alfresco outdoor atmosphere.     

不同演替阶段岩溶石灰土可培养细菌的群落特征

岩溶土壤是岩溶生态系统的重要组成部分,其母质碳酸盐岩在气候、地形、时间及生物等因素的综合作用下可依次演替出黑色石灰土、棕色石灰土、黄色石灰土和红色石灰土.[目的]了解可培养细菌群落对岩溶石灰土演替过程的响应,可为岩溶石漠化治理、生态恢复和重建等提供理论依据.[方法]以黑色石灰土、棕色石灰土、黄色石灰土和红色石灰土为研究...     

贝壳砂改良土壤中反硝化细菌的分析

【目的】通过对一处经过长期使用贝壳砂进行改良的土壤中的反硝化细菌的多样性和细菌分离分析,研究该土壤中反硝化细菌的组成特征。【方法】采用454焦磷酸测序的方法分析了土壤样品中微生物群落的组成,选用Giltay培养基培养、鉴定从土壤中挑选的分离物的反硝化能力,并对具有反硝化能力的微生物进行了16S rRNA基因鉴定。【结果】该土壤样品中占据优势地位的为Proteobacteria、Acidobacteria、Bacteroidetes、Chloroflexi等门的微生物,属的水平上则有近70%尚未确立分类地位。所分离的细菌中,共得到12株厌氧条件下具有较高硝酸盐去除效率的微生物,分属Pseudomonas、Aeromonas、Serratia和Acinetobacter,均为γ变形菌纲的微生物。【结论】该土壤中具有较高的微生物多样性,包括很多未知类型的微生物和众多类型的反硝化细菌;分离到了11株具有反硝化能力的菌株,可用于该土壤的反硝化过程的进一步研究。     

茅尾海红树根际土壤可培养细菌多样性及抑菌活性研究

为挖掘茅尾海红树植物根际土壤可培养细菌资源,研究其抑菌活性,该文使用培养基对茅尾海5种红树植物(红海榄、黄槿、无瓣海桑、桐花树、阔苞菊)的7份根际土壤进行富集培养,选用6种不同分离培养基对富集样品进行可培养细菌的分离纯化,基于菌株16S rRNA基因序列信息进行物种多样性分析,并采用纸片法筛选具有抑制表皮葡萄球菌、耐甲氧西林金黄色葡萄球菌、铜绿假单胞菌活性的菌株。结果表明:(1)从7份红树植物根际土壤样品中分离到120种可培养细菌,隶属于35科47属,其中链霉菌属(Streptomyces sp.)占菌种总数的 14.2%,同时发现5种潜在新菌株。(2)通过抑菌活性初筛,发现9种细菌的发酵粗提物对至少一种致病菌具有抑菌活性。综上表明,茅尾海红树植物根际土壤可培养细菌多样性丰富,并且部分菌株具有抑制人类致病菌活性。该研究结果为新型抗生素的开发与利用提供了菌种资源。     

粉煤灰改良砂姜黑土对麦田生态因子及重金属残留的影响

采用盆栽试验,研究了粉煤灰改良砂姜黑土对麦田生态因子及Cd、Cr、Pb、Hg和As残留的影响.结果表明,粉煤灰改良砂姜黑土可以降低土壤容重和土壤比重,减少土壤粘粒含量,增加土壤孔隙度和土壤渗透系数,提高耕层地温,促进土壤微生物活动和养分转化;土壤含水量高时具有散湿作用,土壤含水量低于10%后,具有保墒作用;在粉煤灰用量为6×10⁴～18×10⁴kg·hm^-2的条件下,土壤及小麦子粒中重金属元素的积累量远低于国际污染标准值,即在此范围内,施用粉煤灰改良砂姜黑土是安全可靠的.     

不同连作年限草莓根际细菌和真菌多样性变化

【目的】以不同连作年限草莓根际土壤为材料,探讨不同连作年限土壤细菌、真菌多样性的变化,以期为草莓连作障碍调控提供理论依据。【方法】将没有连作(CK)、连作1年(1Y)、连作8年(8Y)的土壤分别与珍珠岩以3:1的体积充分混匀装盆,"宁玉"草莓苗于2016年9月10日定植于盆栽土壤中,定植后50 d时(开花前)进行土壤取样,提取基因组DNA,通过PCR扩增建立文库,利用Mi Seq平台Illumina第二代高通量测序技术并结合相关生物信息学方法,分析土壤细菌16S rRNA基因V4+V5区域和真菌ITS1+ITS2区域的丰富度和多样性指数以及群落结构。【结果】从9个草莓根际土壤样本中获得3 192个细菌分类操作单元OTU和762个真菌OTU,其中,变形菌门、厚壁菌门、放线菌门、拟杆菌门和蓝藻门为草莓根际土壤的优势菌种,在CK、1Y、8Y草莓根际土壤中分别占细菌总数的87.86%、64.83%和61.79%;子囊菌门和担子菌门为优势真菌,在CK、1Y、8Y草莓根际土壤中分别占真菌群落的69.17%、69.06%和76.18%。从门的分类水平看,酸杆菌门、放线菌门、拟杆菌门、厚壁菌门、绿弯菌门、蓝菌门、浮霉菌门、芽单胞菌门、变形菌门以及真菌担子菌门、接合菌门、壶菌门的比例在不同连作年限的草莓根际土壤中显著改变(P0.05)。属水平的分析也表明,共有29个细菌属和19个真菌属的比例发生改变(P0.05)。【结论】随连作年限的延长,草莓根际土壤生态系统中细菌和真菌群落各门类组成的比例会发生显著变化。     

采伐剩余物管理措施对二代杉木人工林土壤全碳、全氮含量的长期效应

根据福建省南平市峡阳国有林场二代杉木(Cunninghamia lanceolata(Lamb.) Hook)人工林5种采伐剩余物管理措施(收获采伐剩余物和地被层、全树收获、仅收获树干和树皮以及加倍采伐剩余物、炼山)下0-40 cm深度土壤全碳、全氮含量15a的监测数据,研究了采伐剩余物管理措施对杉木林土壤碳氮含量的影响.结果显示,加倍采伐剩余物处理样地5次取样年份(造林第3年、第6年、第9年、第12年和第15年)0-10 cm土层土壤全碳、全氮含量均高于其他处理样地,但单因素方差分析显示,采伐剩余物管理措施在5次取样年份对0-10 cm、10-20 cm和20-40 cm土层全碳、全氮含量均没有显著影响(P＞0.05).重复测量方差分析显示,杉木造林15a期间土壤全碳、全氮含量随年份显著变化(P＜0.01),但处理措施以及处理措施与取样年份的交互作用对3个土层土壤全碳、全氮含量影响不显著(P＞0.05).杉木林15年生时,不同处理样地3个土层碳储量差异不显著(P＞0.05),0-40 cm土层平均值为88.71 Mg/hm2.表明采伐剩余物管理措施对亚热带杉木人工林土壤全碳、全氮含量的长期效应并不显著.     

Relative abundance of denitrifying and dinitrogen-fixing bacteria in layers of a forest soil

The populations of N(2)-fixing and denitrifying bacteria in an acid forest soil near Cologne were characterized by gene probing. The DNA isolated from the soil for this purpose was suitable for DNA-DNA hybridization using 0.4-0.7-kb probes targeting denitrification enzymes, dinitrogenase reductase (nifH) and eubacterial 16S rRNA. The densitometrical comparison of band intensities obtained in these Southern hybridizations indicated that the highest number of total bacteria, of denitrifying and N(2)-fixing microorganisms always occurred in the upper ( approximately 5 cm) soil layer. The concentration of all these organisms decreased in parallel with the soil depth. The soil investigated was rich in nitrate in all layers, and the availability of nitrate apparently did not govern the distribution of denitrifying and N(2)-fixing bacteria in this soil. Soil cores investigated in the laboratory formed N(2)O on addition of nitrate irrespective of the presence of C(2)H(2). Hybridization intensities, with a gene probe for the 16S rRNA, and MPN numbers were generally higher in soil samples taken from the roots of plants than in the bulk soil. There was no selective enrichment of denitrifying or N(2)-fixing bacteria at the roots. The data obtained by hybridizing isolated soil DNA generally matched previous results obtained with culturable bacteria.     

Effectiveness of sulfur with Acidithiobacillus and gypsum in chemical attributes of a Brazilian sodic soil

Gypsum and sulfur have been used as amendments for application in sodic and saline sodic soils, although gypsum is not effective in soil pH reduction. In this study the combined effects of elemental sulfur inoculated with Acidithiobacillus (S*) and gypsum (G) in chemical attributes of a Brazilian solodic soil was evaluated. The treatments consisted in addition of S* and G in various levels (0, 0.8, 1.6, 2.4, and 3.2 t ha⁻¹) and different mixing proportions (100:0, 75:25, 50:50, 25:75, and 100:0), acting during 15, 30, and 45 days. Sulfur inoculated with Acidithiobacillus (S*) markedly reduced soil pH in the leaching solution, especially when applied in the highest levels. Gypsum or sulfur applied individually was not satisfactory for soil reclamation. At 15 days of incubation Na⁺, Ca²⁺, and Mg²⁺ showed higher values in the leaching solution, and a marked decrease was observed in the leaching solution at 30 days. Reduction in soil electrical conductivity and in exchangeable Na⁺, Ca²⁺, and Mg²⁺ was observed and in a general way best results were achieved with S* : G in the ratio 50:50, using 2.4 and 3.2 t ha⁻¹. Sulfur with Acidithiobacillus was more effective than gypsum in decreasing soil pH, and sulfur applied with gypsum in the proportion 50:50 showed the best results in relation to exchangeable sodium and electrical conductivity and showed values below those used for classification as sodic soils.     

Shifts in alkane-degrading bacteria genotypes during bioremediation of a vegetated coastal soil

The effect of plants (milo, oleander and buffelgrass) and hexadecane (1 g/kg of soil) on the diversity of hexadecane-degraders in a coastal soil was investigated. Hexadecane was rapidly degraded during the first 56 days. Its depletion was not plant-enhanced but was slightly retarded by milo and buffelgrass. The diversity of the dominant cultured hexadecane-degrading bacteria was based on sequencing of the V6-8 region of 16S rDNA. On day 0, Alphaproteobacteria prevailed. By day 56, Gammaproteobacteria dominated the contaminated samples whereas similar numbers of Alphaproteobacteria and Gammaproteobacteria genotypes occurred in the uncontaminated samples. Bacteria related to Alcanivorax, a specialized alkane-degrading marine bacterium, were found in all contaminated samples except for buffelgrass rhizospheres, which solely harbored Pseudomonas indica. On day 114, when hexadecane was highly depleted in the contaminated treatments, similar numbers of Alpha- and Gammaproteobacteria genotypes occurred in contaminated and uncontaminated samples. At this stage Alcanivorax had virtually disappeared. Thus in this coastal soil the prevalence of the alkane-dependent Alcanivorax may be a useful indicator of bioremediation progress provided the plant cover favors the dominance of Alcanivorax.     

Stable soil pH of thai mangroves in dry and rainy seasons and its relation to zonal distribution of mangroves

Soil characteristics of mangrove forests at Amphur Laemngob, Trat Province, east Thailand were investigated in both dry andrainy seasons. Sonneratia alba, Avicennia alba andRhizophora mucronata mainly grew as seaward mangroves.Rhizophora apiculata, Ceriops tagal, Excoecaria agallocha andBruguiera gymnorrhiza grew as meso mangroves in most cases.Lumnitzera racemosa was found as a landward mangrove. The salinity of the soil in which these 8 species grew was significantly higher in the dry season than in the rainy season. Soil pH did not change irrespective of the season. Each species seemed to grow at inherent soil pH. Bruguiera gymnorrhiza, Sonneratia alba andAvicennia marina were found both in Japan and Thailand. The soil pH of each mangrove species was similar in Japan and Thailand. The soil salinity of each mangrove species in Japan was similar to that in Thailand in the dry season. It was suggested that soil pH and salinity in the dry season are the important factors governing the zonal distribution of mangroves.     

蚯蚓对秸秆还田土壤细菌生理菌群数量和酶活性的影响

在连续7a稻麦轮作系统中,通过测定作物收获后表层土壤(0-20cm)中4种细菌生理菌群数量和4种酶活性的变化,研究接种蚯蚓(Metaphire guillelmi)对秸秆(表施或混施)还田土壤的细菌生理菌群数量和酶活性的影响。试验设5个处理:对照、秸秆表施、秸秆混施、秸秆表施且接种蚯蚓、秸秆混施且接种蚯蚓。结果表明,单独秸秆还田促进了土壤氨化细菌、固氮菌、纤维素分解菌和无机磷分解菌数量增加,且土壤酶活性显著地增强;在秸秆表施方式下,接种蚯蚓使得上述4种细菌生理菌群微生物的数量增加;秸秆混施方式下,接种蚯蚓增加氨化细菌和无机磷分解菌数量,且土壤蛋白酶和蔗糖酶活性显著地增强(P0.05)。另外,蚓粪中4种细菌生理菌群微生物数量和水解酶活性都远远高于其周围土壤。在秸秆还田的作物轮作系统中,蚯蚓活动进一步增加土壤微生物数量和酶活性,对改善农田土壤肥力有着重要意义。     

Seasonal fluctuations of aerobic cellulolytic bacteria,and cellulase and respiratory activities in a soil profile under a forest

The amount of cellulase activity and¹⁴CO₂ evolution declined with profile depth. These properties varied seasonally, being highest in autumn and lowest in winter. Cytophaga hutchinsonii andCytophaga rubra were the most common species of cellulolytic bacteria found by the dilution-plate method;Bacillus circulans andCellulomonas fimi were also isolated.Cellulolytic bacterial numbers-¹⁴CO₂ evolution, cellulolytic bacterial numbers-cellulase activity and¹⁴CO₂ evolution-cellulase activity were correlated positive-linear and significantly.     

大气CO2与吡虫啉对甘蓝土壤细菌与微生物生物量C的影响

采用田间开顶式CO2控制气室(OTC),研究了375μL/L、750μL/L两个CO2浓度和CK、LC50、LC903种吡虫啉浓度处理条件下,甘蓝根际土壤细菌与非根际土壤微生物生物量C的变化。750μL/L CO2处理对甘蓝根际细菌数量显著增加(P0.01),而在同一CO2水平下各农药处理间并无显著差异;根区土壤微生物生物量C只有在750μL/L CO2且无吡虫啉处理的条件下显著(P0.05)下降,在LC50、LC90处理的影响下并不显著。同一CO2水平下,根区土壤微生物生物量C受农药处理的影响不明显。     

Lysis of mycelium ofFusarium oxysporum f. sp.udum in soil amended with organic matters

Summary Autoclaved or natural field soil amended with 0.1 to 5.0 per cent (W/W) of margosa cake, rice husk and sawdust with or without supplemental nitrogen were tested for lytic activity and bacterial numbers. Generally, non-amended autoclaved soil caused little or no lysis of mycelium ofF. oxysporum f. sp.udum; non-amended natural soil caused more lysis. Amendment of soil with margosa cake, rice husk or saw-dust with or without supplemental nitrogen greatly enhanced its lytic effect on the fungus. The degree of lysis depended on the dosage of amendment used and the stage of its decomposition in the soil. The extent of lysis increased as the bacterial population increased. Amongst bacteria,Bacillus subtilis was very common in most lytic zones.     

Isolation and characterization of bacteria from soil contaminated with diesel oil and the possible use of these in autochthonous bioaugmentation

Two bacterial species (isolates N and O) were isolated from a paddy soil microcosm that had been artificially contaminated with diesel oil to which extrinsic Pseudomonas aeruginosa strain WatG, had been added exogenously. One bacterial species (isolate J) was isolated from a similar soil microcosm that had been biostimulated with Luria–Bertani (LB) medium. Isolates N and O, which were tentatively identified as Stenotrophomonas sp. and Ochromonas sp., respectively, by sequencing of their 16 S rRNA genes had no ability to degrade diesel oil on their own in any liquid medium. When each strain was cocultivated with P. aeruginosa strain WatG in liquid mineral salts medium (MSM) containing 1% diesel oil, isolate N enhanced the degradation of diesel oil by P. aeruginosa strain WatG, but isolate O inhibited it. In contrast, isolate J, which was tentatively identified as a Rhodococcus sp., degraded diesel oil contained not only in liquid LB and MSM, but also in paddy soil microcosms supplemented with LB medium. The bioaugmentation capacity of isolate J in soil microcosms contaminated with diesel oil was much higher than that of P. aeruginosa strain WatG. The possibility of using isolate J for autochthonous bioaugmentation is discussed.     

Molecular bacterial diversity of a forest soil under residue management regimes in subtropical Australia

A major operational change in exotic pine plantations of subtropical Australia has been the decision to retain postharvest residues on site. A long-term field experiment was established in February 1996 to examine the impacts of residue management regimes [i.e. the postharvest residues removed (G0R), natural amount of residues retained (G1R) and residue quantity doubled and retained (G2R)] on tree growth (F1 hybrid pine) and sustainable soil management. Twelve soil samples, which included the above three residue regimes with four replicates, were collected at plantation age 6.4 years. A 16S rRNA gene clone library was established following soil community DNA extraction, polymerase chain reaction amplification and cloning. A total of 324 clones, including 27 from each sample, were randomly selected and sequenced to represent the bacterial composition and diversity of the clone library and thus the soil bacterial community under the residue management regimes. Phylogenetic analyses indicated that Acidobacteria (37.6%) and Proteobacteria (35.6%) were the dominant components of the soil bacterial community, followed by Actinobacteria (14.7%), Chlamydiae/Verrucomicrobia (7.3%), Unclassified Bacteria (3.8%) and Gemmatimonadetes (1.0%). Analysis of molecular variance revealed that there was no significant difference in bacterial composition and diversity among the residue management regimes or their replicated samples.