南通沿海滩涂耐盐植物重金属抗性内生细菌的筛选及生物多样性

【目的】沿海滩涂耐盐植物重金属抗性内生细菌的筛选及其促生长潜在能力的研究有助于我们获得一些能够耐受并促进耐盐植物在被Cd2+、Pb2+、Hg2+、Cu2+,Zn2+等重金属离子污染的贫瘠的沿海滩涂上正常生长的菌株,达到既能够利用广袤的滩涂生物资源产生经济价值又能够净化生态环境的目的。【方法】以江苏南通沿海滩涂地区的4种耐盐植物为材料,采用稀释平板涂布法从中分离得到45株内生细菌,从中挑取23株代表性的菌株,对其进行抗重金属Cu2+、Pb2+、Cd2+、Zn2+,Hg2+的活性筛选;固氮、解磷、吲哚乙酸(IAA)的产生、1-氨基环丙烷-1-羧酸(ACC)脱氨酶活性等促生指标以及NaCl耐受能力的筛选。【结果】发现分离所得的大多数细菌能够耐受高浓度的Cu2+以及Pb2+,但是对Cd2+、Zn2+,Hg2+的耐受能力则较弱;26.1%的细菌具有固氮能力,21.7%的细菌具有解磷能力,60.9%的细菌能够产生IAA,39.1%的细菌含有ACC脱氨酶。对他们进行16S rRNA基因鉴定后发现,他们分属于芽胞杆菌属(Bacillus)、喜盐芽胞杆菌属(Halobacillus)、海洋芽胞杆菌属(Oceanobacillus)、微小杆菌属(Exiguobacterium)、沙雷氏菌属(Serratia)、短波单胞菌属(Brevundimonas)、弧菌属(Vibrio)、葡萄球菌属(Staphylococcus)共8个属,显示了丰富的多样性。其中菌株KLBMP 2432以及菌株KLBMP 2447为潜在的新种。【结论】沿海滩涂地区的耐盐植物内生细菌具有丰富多样的生物多样性以及促生长能力,且存在潜在的新种资源,并对重金属Cu2+,Pb2+具有较强的抗性。     

<Emphasis Type="Italic">Sphingomonas humi</Emphasis> sp. nov., isolated from soil

A Gram-negative, non-motile, non-spore-forming, small, orange, rod-shaped bacterium was isolated from soil in South Korea and characterized to determine its taxonomic position. Phylogenetic analysis based on 16S rRNA gene sequence examination revealed that strain PB323^T belongs to the family Sphingomonadaceae. The highest degree of sequence similarity was found with Sphingomonas kaistensis PB56^T (98.9%), followed by Sphingomonas astaxanthinifaciens TDMA-17^T (98.3%). Chemotaxonomic characteristics (the G+C content of the genomic DNA 69.0 mol%, Q-10 quinone system, C_18:1 ω7c/ω9t/ω12t, C_16:1 ω7c/C_15:0 iso 2OH, C_17:1 ω6c, and C16:0 as the major fatty acids) corroborated assignment of strain PB323^T to the genus Sphingomonas. Results of physiological and biochemical tests clearly demonstrate that strain PB323^T represents a distinct species and support its affiliation with the genus Sphingomonas. Based on these data, PB323^T (=KCTC 12341^T =JCM 16603T =KEMB 9004-003^T) should be classified as a type strain of a novel species, for which the name Sphingomonas humi sp. nov. is proposed.     

Membrane-associated phosphoinositides-specific phospholipase C forms from <Emphasis Type="Italic">Catharanthus roseus</Emphasis> transformed roots

We have previously reported that Catharanthus roseus transformed roots contain at least two phosphatidylinositol 4,5-bisphosphate-phospholipase C (PLC) activities, one soluble and the other membrane associated. Detergent, divalent cations, and neomycin differentially regulate these activities and pure protein is required for a greater understanding of the function and regulation of this enzyme. In this article we report a partia purification of membrane-associated PLC. We found that there are at least two forms of membrane-associated PLC in transformed roots of C. roseus. These forms were separated on the basis of their affinity for heparin. One form shows an affinity for heparin and elutes at approx 600 mM KCl. This form has a molecular mass of 67 kDa by size exclusion chromatography and Western blot analysis, whereas the other form does not bind to heparin and has a molecular mass of 57 kDa. Possible differential regulation of these forms during transformed root growth is discussed.     

A solution approach for deriving alternative fuel station infrastructure requirements

When an alternative fuel is introduced, the infrastructure through which that fuel is made available to the market is often underdeveloped. Transportation service providers relying on such infrastructures are unlikely to adopt alternative fuel vehicles as it may impose long detours for refueling. In this paper, we design and apply a new solution approach to derive minimum infrastructure requirements, in terms of the number of alternative fuel stations. The effectiveness of our approach is demonstrated by applying it to the case of introducing liquefied natural gas (LNG) as a transportation fuel in The Netherlands. From this case, we learn that, depending on the driving range of the LNG trucks and the size of area on which those trucks operate, a minimum of 5–12 LNG fuel stations is necessary to render LNG trucks economically and environmentally beneficial.     

Interplay between glutathione,Atx1 and copper. 1. Copper(I) glutathionate induced dimerization of Atx1

Copper is both an essential element as a catalytic cofactor and a toxic element because of its redox properties. Once in the cell, Cu(I) binds to glutathione (GSH) and various thiol-rich proteins that sequester and/or exchange copper with other intracellular components. Among them, the Cu(I) chaperone Atx1 is known to deliver Cu(I) to Ccc2, the Golgi Cu–ATPase, in yeast. However, the mechanism for Cu(I) incorporation into Atx1 has not yet been unraveled. We investigated here a possible role of GSH in Cu(I) binding to Atx1. Yeast Atx1 was expressed in Escherichia coli and purified to study its ability to bind Cu(I). We found that with an excess of GSH [at least two GSH/Cu(I)], Atx1 formed a Cu(I)-bridged dimer of high affinity for Cu(I), containing two Cu(I) and two GSH, whereas no dimer was observed in the absence of GSH. The stability constants (log β) of the Cu(I) complexes measured at pH 6 were 15–16 and 49–50 for CuAtx1 and Cu₂^I(GS⁻)₂(Atx1)₂, respectively. Hence, these results suggest that in vivo the high GSH concentration favors Atx1 dimerization and that Cu₂^I(GS⁻)₂(Atx1)₂ is the major conformation of Atx1 in the cytosol.