Impact of Faba Bean-Seed Rhizobial Inoculation on Microbial Activity in the Rhizosphere Soil during Growing Season

Inoculation of legume seeds with Rhizobium affects soil microbial community and processes, especially in the rhizosphere. This study aimed at assessing the effect of Rhizobium inoculation on microbial activity in the faba bean rhizosphere during the growing season in a field experiment on a Haplic Luvisol derived from loess. Faba bean (Vicia faba L.) seeds were non-inoculated (NI) or inoculated (I) with Rhizobium leguminosarum bv. viciae and sown. The rhizosphere soil was analyzed for the enzymatic activities of dehydrogenases, urease, protease and acid phosphomonoesterase, and functional diversity (catabolic potential) using the Average Well Color Development, Shannon-Weaver, and Richness indices following the community level physiological profiling from Biolog EcoPlate™. The analyses were done on three occasions corresponding to the growth stages of: 5–6 leaf, flowering, and pod formation. The enzymatic activities were higher in I than NI (p < 0.05) throughout the growing season. However, none of the functional diversity indices differed significantly under both treatments, regardless of the growth stage. This work showed that the functional diversity of the microbial communities was a less sensitive tool than enzyme activities in assessment of rhizobial inoculation effects on rhizosphere microbial activity.     

Responses of Soil Microbial Communities in the Rhizosphere of Cucumber (Cucumis sativus L.) to Exogenously Applied p-Hydroxybenzoic Acid

Changes in soil biological properties have been implicated as one of the causes of soil sickness, a phenomenon that occurs in continuous monocropping systems. However, the causes for these changes are not yet clear. The aim of this work was to elucidate the role of p-hydroxybenzoic acid (PHBA), an autotoxin of cucumber (Cucumis sativus L.), in changing soil microbial communities. p-Hydroxybenzoic acid was applied to soil every other day for 10?days in cucumber pot assays. Then, the structures and sizes of bacterial and fungal communities, dehydrogenase activity, and microbial carbon biomass (MCB) were assessed in the rhizosphere soil. Structures and sizes of rhizosphere bacterial and fungal communities were analyzed by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and real-time PCR, respectively. p-Hydroxybenzoic acid inhibited cucumber seedling growth and stimulated rhizosphere dehydrogenase activity, MBC content, and bacterial and fungal community sizes. Rhizosphere bacterial and fungal communities responded differently to exogenously applied PHBA. The PHBA decreased the Shannon-Wiener index for the rhizosphere bacterial community but increased that for the rhizosphere fungal community. In addition, the response of the rhizosphere fungal community structure to PHBA acid was concentration dependent, but was not for the rhizosphere bacterial community structure. Our results indicate that PHBA plays a significant role in the chemical interactions between cucumber and soil microorganisms and could account for the changes in soil microbial communities in the continuously monocropped cucumber system.     

Dynamics of Bacterial Community Structure in the Rhizosphere and Root Nodule of Soybean: Impacts of Growth Stages and Varieties

Bacterial communities in rhizosphere and root nodules have significant contributions to the growth and productivity of the soybean (Glycine max (L.) Merr.). In this report, we analyzed the physiological properties and dynamics of bacterial community structure in rhizosphere and root nodules at different growth stages using BioLog EcoPlate and high-throughput sequencing technology, respectively. The BioLog assay found that the metabolic capability of rhizosphere is in increasing trend in the growth of soybeans as compared to the bulk soil. As a result of the Illumina sequencing analysis, the microbial community structure of rhizosphere and root nodules was found to be influenced by the variety and growth stage of the soybean. At the phylum level, Actinobacteria were the most abundant in rhizosphere at all growth stages, followed by Alphaproteobacteria and Acidobacteria, and the phylum Bacteroidetes showed the greatest change. But, in the root nodules Alphaproteobacteria were dominant. The results of the OTU analysis exhibited the dominance of Bradyrhizobium during the entire stage of growth, but the ratio of non-rhizobial bacteria showed an increasing trend as the soybean growth progressed. These findings revealed that bacterial community in the rhizosphere and root nodules changed according to both the variety and growth stages of soybean in the field.     

Changes in Rhizosphere Soil Fungal Communities of Pinus tabuliformis Plantations at Different Development Stages on the Loess Plateau

The soil fungal community is an important factor in the forest ecosystems, and a better understanding of its composition and dynamic changes will contribute to the maintenance, preservation, and sustainable development of the forest ecosystems. Pinus tabuliformis has been widely planted for local ecological restoration on the Loess Plateau in China in recent decades. However, these plantations have been degraded to different degrees with increasing stand age. Hence, we tried to find the possible causes for the plantation degradation by analyzing soil environmental changes and soil fungal community composition at different stand ages. We collected rhizosphere soil samples from young (10-year-old), middle-aged (20-year-old), and near-mature (30-year-old) P. tabuliformis plantations in this region and characterized their soil properties and soil fungal community diversity and composition. Our results showed that with increasing stand age, the contents of organic carbon, ammonium nitrogen (AN) and nitrate nitrogen (NN) in the soil increased significantly, while the content of available phosphorus (AP) decreased significantly. The main factors affecting the composition of the soil fungal community were the contents of AP, AN, and NN in the soil. In addition, the genus Suillus was the dominant ectomycorrhizal (ECM) fungus in all periods of P. tabuliformis plantations in this region. The results of structural equation modeling showed that the community composition of ECM fungi was significantly correlated with stand age, soil NN, and AP contents, and that of pathogenic (PAG) fungi was significantly correlated with soil AN and AP contents. The decrease in the relative abundance of ECM fungi and the increase in the relative abundance of PAG fungi would exacerbate the degradation of P. tabulaeformis plantation. Our results illustrated that the content of soil AP is not only an important factor limiting the development of plantations, but it also significantly affects the community composition of soil fungi in the rhizosphere of the P. tabuliformis plantation. This study provides a novel insight into the degradation of P. tabuliformis plantations and builds a solid foundation for their subsequent management, restoration, and sustainable development on the Loess Plateau of China.     

CAN SIMULTANEOUS INHIBITION OF SEEDLING GROWTH AND STIMULATION OF RHIZOSPHERE BACTERIAL POPULATIONS PROVIDE EVIDENCE FOR PHYTOTOXIN TRANSFER FROM PLANT RESIDUES IN THE BULK SOIL TO THE RHIZOSPHERE OF SENSITIVE SPECIES?

In order to demonstrate that allelopathic interactions are occurring, one must, among other things, demonstrate that putative phytotoxins move from plant residues on or in the soil, the source, through the bulk soil to the root surface, a sink, by way of the rhizosphere. We hypothesized that the incorporation of phytotoxic plant residues into the soil would result in a simultaneous inhibition of seedling growth and a stimulation of the rhizosphere bacterial community that could utilize the putative phytotoxins as a sole carbon source. If true and consistently expressed, such a relationship would provide a means of establishing the transfer of phytotoxins from residue in the soil to the rhizosphere of a sensitive species under field conditions. Presently, direct evidence for such transfer is lacking. To test this hypothesis, cucumber seedlings were grown in soil containing various concentrations of wheat or sunflower tissue. Both tissue types contain phenolic acids, which have been implicated as allelopathic phytotoxins. The level of phytotoxicity of the plant tissues was determined by the inhibition of pigweed seedling emergence and cucumber seedling leaf area expansion. The stimulation of cucumber seedling rhizosphere bacterial communities was determined by the plate dilution frequency technique using a medium containing phenolic acids as the sole carbon source. When sunflower tissue was incorporated into autoclaved (to reduce the initial microbial populations) soil, a simultaneous inhibition of cucumber seedling growth and stimulation of the community of phenolic acid utilizing rhizosphere bacteria occurred. Thus, it was possible to observe simultaneous inhibition of cucumber seedlings and stimulation of phenolic acid utilizing rhizosphere bacteria, and therefore provide indirect evidence of phenolic acid transfer from plant residues in the soil to the root surface. However, the simultaneous responses were not sufficiently consistent to be used as a field screening tool but were dependent upon the levels of phenolic acids and the bulk soil and rhizosphere microbial populations present in the soil. It is possible that this screening procedure may be useful for phytotoxins that are more unique than phenolic acids.     

The influence of soil properties on the effectiveness of phenylphosphorodiamidate (PPD) in reducing ammonia volatilization from surface applied urea

Urea can be an inefficient N source due to rapid hydrolysis by soil urease leading to NH₃ volatilization. The current study investigated the effect of the urease inhibitor phenylphosphorodiamidate (PPD) incorporated at two concentrations (0.5% and 1% w/w) within the fertilizer granule on NH₃ volatilization from surface applied urea. The daily rates of NH₃ loss from 20 soils of widely differing properties from Northern Ireland were measured over 14 days using ventilated enclosures under simulated spring conditions. Cumulative loss rates were calculated and fitted to a logistic model from which total NH₃ loss (Amax) and the time to maximum rate of loss (Tmax) were determined. Stepwise multiple linear regression analysis related the effectiveness of PPD in reducing NH₃ volatilization from urea to soil properties.The total cumulative loss of ammonia from unamended urea varied from 0.37 to 29.2% depending on soil type. Ammonia volatilization appeared to be greatest on a soil with a high pH (R² = 0.65), a low titratable acidity (TA) (R² = 0.63) and a soil that was drying out (R² = 0.50). Soil pH was negatively correlated with TA (r = –0.826, P < 0.001) suggesting that soils with a low TA may have received recent lime. Including cation exchange capacity (CEC) and % N as well as pH-KCl in the multiple linear regression equation explained 86% of the variance.The effectiveness of PPD in reducing Amax varied between 0% to 91% depending on soil type, the average over all 20 soils being 30 and 36% for 0.5% and 1% PPD respectively. The most important soil properties influencing the effectiveness of the urease inhibitor were soil pH-H₂O and TA accounting for 33% and 29% of the variance respectively. PPD was less effective on a soil with a high pH and low TA. These were the soil conditions that led to high NH₃ volatilization from unamended urea and may explain why PPD had limited success in reducing ammonia loss on these soils. Multiple linear regression analysis indicated that 75% of the variation in the % inhibition of NH₃ loss by PPD could be significantly accounted for by pH-H₂O, initial soil NO ₃ ^- -N concentration, % moisture content and % moisture loss.The delay in Tmax by PPD ranged from 0.19 to 7.93 days, the average over all 20 soils being 2.5 and 2.8 days for 0.5% and 1% PPD respectively. TA, % moisture content, urease activity and CEC were soil properties that significantly explained 83% of the variation in the % delay in Tmax by PPD in multiple linear regression analysis. However, none of these soil properties were significant on their own. As urea hydrolysis occurs rapidly in soil, delaying Tmax under field conditions would increase the chance of rain falling to move the urea below the soil surface and reduce NH₃ volatilization. A urease inhibitor should be more effective than PPD on soils with a high pH and low TA to be successful in reducing high NH₃ losses.     

36%苄·二氯可湿性粉剂在土壤中的残留动态

研究36%苄·二氯可湿性粉剂在水稻苗床土壤中的残留动态,建立了样品前处理方法和分析方法.36%苄·二氯WP在稻田土壤样品的添加回收率均大于80%,在吉林省和湖南省土壤中,苄嘧磺隆的半衰期分别为2.59～2.97、1.52～1.59 d,二氯喹啉酸的半衰期分别为10.00～12.49、3.65～4.19 d,降解较快.苄嘧磺隆、二氯喹啉酸在水稻移栽前苗床土壤中均未检出.     

Does grassland vegetation drive soil microbial diversity?

Does plant diversity drive soil microbial diversity in temperate, upland grasslands? Plants influence microbial activity around their roots by release of carbon and pot studies have shown an impact of different grass species on soil microbial community structure. Therefore it is tempting to answer yes. However, evidence from field studies is more complex. This evidence is reviewed at three different scales. First, studies from the plant community scale are considered that have compared soil microbial community structure in pastures of different vegetation composition, as a consequence of pasture improvement. These show fungi dominating the biomass in unimproved pastures and bacteria when lime and fertilizers have been applied. Secondly, evidence for interactions between individual grass species and soil microbes is discussed at the level of the rhizosphere, by considering both pot experiments and field studies. These have produced contrasting and inconclusive results, often due to spatial heterogeneity of soil properties and microbial communities. In particular, increased soil pH and fertility in urine patches and other nutrient cycling processes interact to increase the spatially complexity of soil microbial communities. Finally three studies which have measured microbial community structure in the rhizoplane are considered. These show that bacterial diversity is not directly related to plant diversity, although fungal diversity is. In addition, the soil fungal community has been demonstrated to have an effect upon the composition of the bacterial community. We suggest that while current vegetation influences fungal communities (particularly mycorrhizae) and litter inputs fungal saprotrophs, bacterial community structure is influenced more by the quality or composition of soil organic matter, thereby reflecting carbon inputs to the soil over decades.     

Bisphenol A—A Dangerous Pollutant Distorting the Biological Properties of Soil

Bisphenol A (BPA), with its wide array of products and applications, is currently one of the most commonly produced chemicals in the world. A narrow pool of data on BPA–microorganism–plant interaction mechanisms has stimulated the following research, the aim of which has been to determine the response of the soil microbiome and crop plants, as well as the activity of soil enzymes exposed to BPA pressure. A range of disturbances was assessed, based on the activity of seven soil enzymes, an abundance of five groups of microorganisms, and the structural diversity of the soil microbiome. The condition of the soil was verified by determining the values of the indices: colony development (CD), ecophysiological diversity (EP), the Shannon–Weaver index, and the Simpson index, tolerance of soil enzymes, microorganisms and plants (TI_BPA), biochemical soil fertility (BA₂₁), the ratio of the mass of aerial parts to the mass of plant roots (PR), and the leaf greenness index: Soil and Plant Analysis Development (SPAD). The data brought into sharp focus the adverse effects of BPA on the abundance and ecophysiological diversity of fungi. A change in the structural composition of bacteria was noted. Bisphenol A had a more beneficial effect on the Proteobacteria than on bacteria from the phyla Actinobacteria or Bacteroidetes. The microbiome of the soil exposed to BPA was numerously represented by bacteria from the genus Sphingomonas. In this object pool, the highest fungal OTU richness was achieved by the genus Penicillium, a representative of the phylum Ascomycota. A dose of 1000 mg BPA kg⁻¹ d.m. of soil depressed the activity of dehydrogenases, urease, acid phosphatase and β-glucosidase, while increasing that of alkaline phosphatase and arylsulfatase. Spring oilseed rape and maize responded significantly negatively to the soil contamination with BPA.     

增值尿素的氨挥发特征及其对土壤微生物量碳和脲酶活性的影响

通过向普通尿素中添加风化煤粉、腐植酸钾和脱盐液,利用熔融造粒工艺制备出普通尿素（U）、风化煤尿素（F U）、腐植酸尿素（H A U）、脱盐液尿素（T U）3个增值尿素试验产品,在25℃条件下,进行土壤培养试验,研究了增值尿素的氨挥发特征及其对土壤微生物量碳、脲酶活性的影响。结果表明,与普通尿素相比,各增值尿素氨挥发累积量降低29.52%～39.78%,延迟了氨挥发的峰值;各增值尿素处理,在培养的前7天内土壤的脲酶活性降低,延缓了尿素态氮在土壤的转化速率;延缓了土壤微生物量碳峰值出现时间;风化煤和腐植酸尿素处理在整个培养期内表现处理了较好的稳定性,减少氨挥发效果明显。     

Relationships between soil urease activity and other properties of some tropical wetland rice soils

Ten Philippine wetland rice soils differing widely in pH, texture and organic matter were studied to determine relationships between urease activity and other soil properties. Simple correlation analyses of urease activity with soil properties indicated that urease activity was correlated highly significantly with total N (r = 0.91)^**, and organic C (r = 0.89^**) but was not significantly correlated with CEC, Clay, pH active Fe or active Mn content. From multiple regression analyses it was observed that organic matter content of soils measured by organic C and total N accounted for most of the variation in urease activity.     

煤炭腐植酸作为土壤改良剂对土壤物理性质和小麦产量的影响

在巴基斯坦旁遮普的波特瓦地区(33°N,74°E),集约化土壤耕作,土壤侵蚀和低量作物残体的投入是导致土壤结构退化的原因。结构不稳定的土壤很容易受到侵蚀,反过来,土壤侵蚀又会造成作物产量的下降。因此,为了改善土壤的物理性状,在巴基斯坦旁遮普的干旱地区进行了田间试验。试验地点位于大学(拉瓦尔品第PMAS干旱农业大学)研究农场的园区内。2种不同等级(实验室级和商品级)的腐植酸(HA)各分8个水平,施用2年,处理分别为HL_0(对照,不施腐植酸),HL_1 10 kg HA/hm~2,HL_2 20 kg HA/hm~2,HL_3 30 kg HA/hm~2,HL_4 60 kg HA/hm~2,HL_5 90 kg HA/hm~2,HL_6 120 kg HA/hm~2和HL_7 150 kg HA/hm~2,各处理同时配合施用N-P-K(120-90-60 kg/hm~2)。试验期间,检测土壤总有机碳、饱和导水率、团聚体稳定性、容重、土壤含水量和作物产量。试验结果表明,腐植酸能通过影响土壤总有机碳、饱和导水率、团聚体稳定性、容重和土壤含水量等指标来改善土壤的物理性状。2年试验结果均表现为,实验室级的腐植酸比商品级的腐植酸能更好地改善土壤物理性状,从而提高小麦产量。2种不同级别的腐植酸各施用水平与对照相比,差异均显著。在120 kg/hm~2和150 kg/hm~2的腐植酸施用水平下,大多数指标均显示出了相似的结果,因此,从经济角度考虑,120 k g/hm~2的腐植酸用量为最佳施用量。     

Polycyclic Aromatic Hydrocarbons and Nitropolycyclic Aromatic Hydrocarbons in Atmospheric Particles and Soil at a Traffic Site in Hanoi,Vietnam

The concentrations of polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) in total suspended particulates (TSP) and soil were measured at a traffic site in Hanoi, a typical motorcycle city of Vietnam. TSP was collected using high-volume air sampler on Pallflex 2500QAT-UP membrane filters. PAHs and NPAHs were analyzed by high-performance liquid chromatography (HPLC) using fluorescence and chemiluminescence detectors, respectively. The average concentrations of total 10 PAHs and 10 NPAHs in soil varied from 3.4–43.7 ng g^?1 and from 112–780 pg g^?1 dry weight, respectively, which were much lower than those in TSP. The results showed that large part of the higher molecular weight PAHs in soil, especially benzo[ghi]perylene and benzo[b]fluoranthene came from the atmosphere. However, NPAHs profile showed a different pattern. 3-nitroperylene and 6-nitrochrysene were the most abundant NPAHs in soil, followed by 1-nitropyrene and 6-nitrobenzo[a]pyrene. The fate of NPAHs in soil varied depending on soil properties and chemical structure of NPAHs. The finding that the [NPAH]/[PAH] concentration ratios in soil were different from those in TSP could be due to bio-degradation and/or secondary formation of NPAHs in soil, depending on NPAHs properties.     

辛硫磷对土壤微生物种群结构的影响

采用室内培养法研究了土壤中200～1000mg／kg三种不同质量分数的辛硫磷对好氧性细菌、真菌和放线菌三大主要微生物种群数量及其优势菌生长速率的影响。结果表明,土壤中各微生物种群对不同质量分数的辛硫磷具有各自不同的反应。辛硫磷对细菌种群数量及优势细菌生长速率的影响表现为明显的刺激效应,且随加药质量分数的提高刺激效应越明显,而且对种群数量的刺激效应随加药时间延长趋势越明显;对放线菌种群数量的影响表现为抑制效应,且随药剂质量分数的提高抑制效应越明显。但随着加药时间的延长,这种抑制效应又趋于减弱．逐渐恢复到正常水平。但对优势放线菌生长速率的影响却表现为刺激效应;对真菌种群数量及优势真菌生长速率的影响也表现为抑制效应,且随药剂质量分数的提高和加药时间的延长抑制效应越明显。因此,有望从土壤中筛选到能降解辛硫磷的细菌,同时真菌可以作为土壤受辛硫磷污染的敏感指示菌。     

Bacterial Inoculant and Sucrose Amendments Improve the Growth of Rheum palmatum L. by Reprograming Its Metabolite Composition and Altering Its Soil Microbial Community

Rheum palmatum L. is an important traditional Chinese medicinal herb now in demand worldwide. Recently, the theoretical framework suggested that sucrose triggers colonization of PGPM (plant growth-promoting microbes) in the rhizosphere, but their interactions on the plant remain largely unknown. Here, we applied three concentrations of both Bacillus amyloliquefaciens EZ99 inoculant (1.0 × 10⁵, 1.0 × 10⁶, and 1.0 × 10⁷ colony-forming units (CFU)/mL, denoted as LB, MB, and HB, respectively) and sucrose (0.15, 1.5, and 15 g/L, denoted as LS, MS, and HS, respectively) to investigate their co-effects on R. palmatum in a field experiment. The results showed that LB + MS (1.0 × 10⁵ CFU/mL Bacillus + 1.5 g/L sucrose) and LB + LS (1.0 × 10⁵ CFU/mL Bacillus + 0.15 g/L sucrose) treatments significantly increased root fresh weight (p ≤ 0.05). Metabolite analysis revealed that the treatment LB + LS significantly increased the relative content of major active components in rhubarb, namely anthraquinones and phenolic compounds, by 1.5% and 2.3%. Although high sucrose addition increased the activities of certain soil enzymes, the LB + LS treatment significantly increased total potassium (TK), whereas it decreased available potassium (AK), which facilitated the potassium utilization in rhizosphere soil. Furthermore, rhizosphere microbiomes revealed that fungal diversity was augmented in LB + LS treatment, in which the common causative fungal pathogen Fusarium spp. showed an effective suppression. Additionally, the redundancy analysis and Spearman correlations revealed a positive relationship of Sphingomonas associated with change in potassium bioavailability. Altogether, our findings suggest that the combined application of a bacterial inoculant and sucrose can improve the growth and quality of R. palmatum, and stimulate uptake of plant nutrients that contribute to alter the microbial community for biocontrol potential. Hence, this work not only has broad application prospects across economical plants, but also emphasizes agroecological practices for sustainable agriculture.     

玉米根系土壤中汞的变化

采用根系箱试验和连续化学萃取法,结合氢化物原子吸收光谱法,研究了玉米根系土壤中各种汞的形态变化。结果表明,在玉米生长45天内,根系土壤中汞的形态有了较为明显的变化。从土壤加汞量对玉米的影响来看,土壤中汞污染程度越大,其在玉米中的积累越多,生物毒性更强,对环境的危害越大。     

外源微生物对土壤中镉形态及微生物多样性的影响

采用土壤盆栽模拟实验,研究接种氧化节杆菌、耳葡萄球菌、嗜麦芽窄食单胞菌对紫花苜蓿吸收土壤中Cd的作用效果．结果表明,3种微生物在土壤中Cd浓度分别为5、20、50mg?kg-1时均能增强紫花苜蓿对Cd的富集吸收,在3种加菌处理中紫花苜蓿地上部分的Cd积累量与单种植苜蓿处理相比分别显著提高了11.38%~20.67%、5.58%~16.54%、20.68~23.51%;地下部分分别显著提高了19.50%~32.30%、8.62%~19.38%、22.77%~39.23%．各处理中根际和非根际土壤Cd形态分布均为残渣态>交换态>碳酸盐结合态>铁锰结合态>有机结合态．紫花苜蓿可促进土壤中Cd向交换态EXC转化,与未种植物处理相比,其根际土壤中EXC态Cd显著提高了3.40%~6.51%;非根际提高了3.16%~5.48%．3种微生物加入显著增强了植物对土壤中Cd向EXC态转化作用,根际土壤中EXC态Cd与未种植物处理分别增加了11.23%~21.49%、6.37%~13.27%、10.78%~27.76%;非根际提高了7.71%~16.30%、4.64%~13.84%、9.62%~20.75%．BIOLOG ECO微平板法分析结果表明,外源微生物加入对Cd污染土壤中微生物数量、活性、多样性指数等均有显著性增大;主成分分析表明不同处理下土壤微生物利用碳源的种类和能力有所差异;聚类分析结果可合理地将各处理按对土壤中Cd有效态转化作用情况归类．     

Agricultural use of three organic residues: effect on orange production and on properties of a soil of the ‘Comarca Costa de Huelva’ (SW Spain)

Disposal of urban, agricultural and industrial organic residues impliesan increasing problem because of all the economic and environmentalrepercussions involved. One of the most adequate ways of managing this problemis the agricultural use of these wastes as organic amendments. Three organicresidues (AC, olive mill waste water sludge compost; MWC, municipal solid wastecompost; and PS, paper mill sludge) were used in a 3-year field experimentinvolving orange production. The effect of their application on crop productionand on soil quality was investigated. Soil samples (0–20 cm depth)collected 11 months after the last soil amendment were analysed for: pH and EC,Kjeldahl-N, available-P, available-K, total organic carbon, humic substances,dehydrogenase, phosphatase, -glucosidase, urease andbenzoyl-argininamidehydrolysing protease (BAA-protease) activities. Generally, the application of the MWC and PSincreased orange yield when compared to control. Moreover, total organic carbonand humic substances significantly increased in soils treated with all theorganic amendments. Organic fertilisation increased the Kjeldahl-N andavailable-P contents of the soil. The application of the organic residues also causedsignificant increases in dehydrogenase, -glucosidase, urease andBAA-protease activities of the soil. Significant positive correlations (p <0.01) between these enzymatic activities and total organic carbon were foundforall treatments. Significant positive correlation between dehydrogenase, urease,-glucosidase, and BAA-protease and orange yield was also found. However,a clear inhibition of phosphatase activity was observed in soils treated withPS. The results indicate that the repeated application to the soil of moderateamounts of organic amendments has positive effects on the chemical andbiochemical properties of the soil, as well as on the orange yield.     

油井土、废玻璃基多孔陶瓷的制备及结构表征

利用油井土、废玻璃作为主要原料,同时以碳酸钙作为造孔剂,通过控制烧结过程,最终制备多孔陶瓷材料,并利用XRD、SEM等对样品进行结构表征。本研究的目的是为了研究油井土、废玻璃、碳酸钙的比例以及烧结温度对孔隙率、机械强度、体积密度、吸水率、微观结构和结晶程度的影响。结果表明样品A3呈现大孔均匀的微观结构,是通过添加35wt％油井土、40wt％废玻璃、20wt％碳酸钙、5wt％硅酸钠在较低的烧结温度下来获得,其孔隙率、抗压强度、抗弯强度、体积密度和吸水率的值分别为52．38％、4．43 MPa、12．59 MPa、1．07 g／cm3和29．56％。并观察到其机械强度、吸水率和微观结构（孔径及孔径分布）有良好的相关性。     

Characterization of Thermophilic Halotolerant Aeribacillus pallidus TD1 from Tao Dam Hot Spring, Thailand

The bacterial strain TD1 was isolated from Tao Dam hot spring in Thailand. Strain TD1 was Gram positive, rod-shaped, aerobic, motile, and endospore forming. The cell was 2.0-40 μm in length and about 0.4 μm in diameter. The optimum growth occurred at 55-60 °C and at pH 7-8. Strain TD1 was able to grow on medium containing up to 10% NaCl. The DNA G+C content was 38.9 mol%. The cellular fatty acid content was mainly C(16:0), which comprised 25.04% of the total amount of cellular fatty acid. 16S rDNA showed 99% identity to Aeribacillus pallidus DSM 3670(T). Bayesian tree analysis strongly supported the idea that strain TD1 is affiliated with genus Aeribacillus, as Aeribacillus pallidus strain TD1. Although the 16S rDNA of A. pallidus strain TD1 is similar to that of A. pallidus DSM 3670(T), some physiological properties and the cellular fatty acid profiles differ significantly. A. pallidus strain TD1 can produce extracellular pectate lyase, which has not been reported elsewhere for other bacterial strains in the genus Aeribacillus. A. pallidus strain TD1 may be a good candidate as a pectate lyase producer, which may have useful industrial applications.