印度洋表层海水石油降解菌的多样性分析

【目的】为了研究印度洋石油降解菌多样性,并获得新的石油降解菌。【方法】本研究通过印度洋表层海水样品采集、以柴油与原油1:1混合物作为碳源,从中富集、分离筛选石油降解菌,并通过PCR-DGGE对13个站点富集菌群的菌群结构进行分析。【结果】通过形态观察、生理生化反应和16SrRNA分析,共得到共29个属的51株不同的细菌,它们主要是属于α亚群和γ亚群。其中,Alcanivorax属(占18%),Novosphingobium属(占10%)和Marinobacter(占6%)Thalassospira(占6%)为主要的优势菌。通过生态多样性分析表明,Shannon-Winner指数(H)为4.57968,说明其具有较高的多样性;均匀度指数(E)为0.8664771,表示其分布比较均匀。单菌实验表明,49株具有石油降解能力其中,Sinomonas,Knoellia,Mesoflavibacter等属的细菌为首次发现有降解能力。DGGE分析表明Alcanivorax属的细菌是印度洋表层海水中的重要石油降解菌。【结论】本研究首次揭示了印度洋表层海水中石油降解菌的多样性,并获取了若干在海洋石油污染生物修复中具有应用前景的降解菌。     

一株深海热液环境来源的PAHs降解菌TVG9-Ⅶ的系统发育与降解基因

【目的】对一株深海热液环境来源的多环芳烃(PAHs)降解菌进行系统发育分析并对其降解特性和降解机制进行研究。【方法】对16S rRNA基因进行扩增和测序,进行基于16S rRNA基因序列的系统发育分析;利用GC-MS测定其对PAHs的降解率;通过构建基因组Fosmid文库,克隆PAHs降解基因簇;并利用RT-PCR和qPCR研究关键降解酶基因在不同PAHs诱导下的表达情况。【结果】从西南太平洋劳盆地热液沉积物中分离到一株PAHs降解菌株TVG9-Ⅶ,系统发育分析结果表明,该菌株属于新鞘氨醇杆菌属(Novosphingobium),与该属的Novosphingobium indicum H25T系统发育关系最为密切,它们的16S rRNA基因序列相似性高达99.7%。该菌株在21 d内对菲、荧蒽和芘的降解率分别为95.2%,57.3%和69.6%。从Fosmid文库中筛选得到一个负责PAHs降解的上游基因簇,包含了PAHs起始降解双加氧酶大小亚基(pheA1a/b)基因和一个脱氢酶基因;RT-PCR和qPCR实验表明,双加氧酶大亚基基因pheA1a在菲的诱导下上调表达4.2倍,而在萘及高环荧蒽和芘的诱导下无上调。【结论】菌株TVG9-Ⅶ是Novosphingobium属深海热液来源的PAHs降解菌,具有良好的降解特性,特别是对高环PAHs的降解效果较好。     

厦门近海海水中多环芳烃降解菌的原位富集与降解菌多样性

摘要：【目的】为了分析厦门近海原位海水中多环芳烃降解菌的多样性。【方法】将涂有菲的聚氯乙烯（PVC）板悬挂在厦门国际邮轮码头的海水中,进行菲降解菌的原位富集。利用变性梯度凝胶电泳（Denaturing gradient gel electrophoresis,DGGE）和16S rRNA基因文库两种方法分析了在PVC板表面富集微生物的菌群结构。之后,在实验室模拟原位条件下,对PVC板表面富集的菲降解菌群进行进一步富集、分离和初步鉴定。【结果】PVC板在海水中浸没6 d后,16S rRNA基因文库分析表明,在涂菲的PVC板表面富集的菌群中解环菌属（Cycloclasticus）对应的克隆子占文库总克隆子的50%;在未涂菲的PVC板表面吸附的菌群中红杆菌科（Rhodobacteraceae）为优势菌,其对应的克隆子占文库总克隆子的47%;而解环菌属的克隆子只占文库总克隆子的2%。DGGE的分析结果也证明解环菌是菲原位富集降解菌群中的优势菌。实验室进一步富集后,从该菌群中分离鉴定出14株细菌,其中一株新鞘氨醇杆菌B14(Novosphingobium sp.B14)具有菲降解能力。但是,解环菌未能获得纯培养。【结论】菲原位富集发现,厦门近海水体中解环菌是多环芳烃的主要降解菌。     

对Bt蛋白敏感敏感和敏感的棉铃虫中肠细菌群落的比较

摘要：【目的】通过比较Cry1Ac蛋白抗性及敏感棉铃虫中肠细菌群落的结构组成,研究中肠微生物是否与棉铃虫Bt抗性产生有关。【方法】首先提取了棉铃虫中肠微生物基因组DNA,通过PCR扩增获得了16S rDNA全长片段及V3区。采用基于16S rDNA 的免培养技术—16S rDNA文库建立和变性梯度凝胶电泳（DGGE）研究了国内特有的Bt抗性和敏感品系棉铃虫中肠细菌群落组成,并对其进行分析和比较。【结果】16S rDNA文库测序结果表明,抗性品系与敏感品系棉铃虫中肠细菌群落特别是优势菌群非常相似,但在部分劣势菌群上存在差异。抗性品系中主要优势菌有：不可培养微生物（Uncultured bacterium）占56.4%,鹑鸡肠球菌（Enterococcus gallinarum）占17.0%,铅黄肠球菌（Enterococcus casseliflavus）占17.0%;敏感品系中主要优势菌为不可培养微生物（Uncultured bacterium）60.2%,鹑鸡肠球菌（Enterococcus gallinarum）占19.3%,铅黄肠球菌（Enterococcus casseliflavus）占14.7%。随后进行的PCR验证表明,部分有差异的劣势菌在两种品系虫体都存在。DGGE图谱分析表明,这两个品系棉铃虫中肠菌群相似性达到92.3%。【结论】敏感品系与抗性品系棉铃虫肠道菌群组成极其相似,推测抗性的产生与肠道微生物无直接关系。     

南大西洋深海热液区可培养硫氧化微生物多样性及其硫氧化特性

【目的】探索南大西洋热液环境中的硫氧化细菌多样性并研究其硫氧化特性。【方法】通过富集培养和分离纯化获得硫氧化细菌,利用变性梯度凝胶电泳(DGGE)分析富集菌群组成结构,采用离子色谱法对获得的硫氧化细菌硫氧化特性进行检测。【结果】从南大西洋深海环境样品中共分离到48株菌,分属于alpha-Proteobacteria(28株,58.3%)、Actinobacteria(11株,22.9%)和gama-Proteobacteria(9株,18.8%)共3个门,其中Thalassospira、Martelella和Microbacterium为优势属。DGGE结果表明深海热液环境样品中微生物多样性丰富且不同站位存在差异。硫氧化特性研究结果表明,约60%的分离菌株具有硫氧化能力,可以氧化S_2O_3~(2–)生成SO_4~(2–)。获得一株硫氧化能力较强的潜在新种L6M1-5,在实验条件下可高效氧化S_2O_3~(2–),最大氧化速率可达0.56 mmol/(L·h)。【结论】南大西洋深海热液环境中可培养硫氧化细菌多样性丰富,为研究热液环境中的硫循环过程提供了实验材料和理论参考;同时高效硫氧化菌的获得,为工业化含硫废水的处理提供了良好的菌种资源。     

基于转录组与翻译组的海洋食烷菌(Alcanivorax)烷烃代谢调控研究

【目的】食烷菌是海洋烃类降解优势菌,其烷烃代谢调控机制有待深入研究。本研究拟从食烷菌转录和翻译水平上认识烷烃降解的调控过程。【方法】分别以乙酸和正十六烷(C16)为唯一碳源与能源,获取柴油食烷菌(Alcanivorax dieselolei) B5菌株的转录组和翻译组数据,并整合数据计算得到该菌在2种碳源培养条件下基因的翻译效率。采用基因本体论(gene ontology, GO)和京都基因和基因组百科全书(Kyoto encyclopedia of genes and genomes, KEGG)对差异翻译和翻译效率基因进行功能和代谢通路注释。【结果】当以C16为唯一碳源与能源时,B5菌株烷烃代谢途径的关键基因在转录与翻译水平均大量提升,包括烷烃单加氧酶、细胞色素P450氧化酶、醇脱氢酶和醛脱氢酶等。KEGG富集结果表明,翻译水平显著上调基因参与了肽聚糖生物合成、脂肪酸降解、氯代烷烃降解、氧化磷酸化和生物膜形成等通路;翻译效率差异基因主要富集在铁载体非核糖体肽的生物合成、氧化磷酸化和不饱和脂肪酸的生物合成等途径。通过转录组和翻译组学的联合分析显示,为了适应烷烃氧化,B5有效地协调了转...     

几株新鞘氨醇杆菌的趋化性及其相关基因组成特点

【目的】选择了几株隶属于新鞘氨醇杆菌属(Novosphingobium)的有和没有多环芳烃(PAHs)降解能力的细菌,在基因组水平比较分析它们的趋化通路,并探究其中一些菌株对芳香化合物和三羧酸(TCA)循环中间代谢产物的趋化性。【方法】通过基因组的比较分析,研究了几株新鞘氨醇杆菌的趋化蛋白组成和趋化基因分布,并采用滴定法和游动平板法检测了相关菌对芳香族化合物和TCA循环中间代谢产物的趋化性。【结果】N.pentaromativorans US6-1、N.pentaromativorans F2、Novosphingobium indicum K13、Novosphingobium stygium DSM 12445、Novosphingobium sp.C2AC等5株新鞘氨醇杆菌对芳香族化合物和TCA循环中间代谢物具有不同程度的趋化性;所选的7株已完成基因组测序的新鞘氨醇杆菌N.pentaromativorans F2、N.pentaromativorans US6-1、Novosphingobium sp.PP1Y、Novosphingobium sp.AP12、Novosphingobium sp.Rr 2-17,Novosphingobium sp.B-7和Novosphingobium sp.DSM 19370均含有趋化蛋白MCP、CheW、CheA、CheB、CheR和CheY,且亲缘关系最近的US6-1、F2和PP1Y 3株菌的che基因簇中的基因排列一致,为che W-Y-D-B-R-A-(X);新鞘氨醇杆菌的趋化系统属Fla类型。【结论】几株新鞘氨醇杆菌都具有较为完整的趋化通路,且对多种芳烃及其代谢物的趋化性各不相同,其中菌株US6-1趋化现象最明显。     

饲喂肉杆菌Hg4-03对贡嘎蝠蛾幼虫肠菌生物多样性的影响

【目的】研究贡嘎蝠蛾幼虫肠道优势菌肉杆菌(Carnobacterium sp.)Hg4-03作为食物添加剂对实验室饲养的4龄贡嘎蝠蛾幼虫肠道菌群的影响。【方法】采用16S rDNA序列与PCR/DGGE(Denaturing gradient gel electrophoresis)分析技术相结合的方法,健康幼虫被随机分为处理组1、处理组2和对照组,两组处理组分别饲喂添加不同浓度肉杆菌Hg4-03的天然饲料,对照组只饲喂天然饲料。14 d和28 d后每组随机解剖6条幼虫,收集肠道样品,经细菌通用引物扩增细菌16S rDNA,DGGE分离并进行细菌多样性图谱分析。【结果】饲喂肉杆菌Hg4-03后幼虫肠道菌群的多样性指数呈上升趋势;处理组幼虫肠道中肉杆菌Hg4-03含量增加,且处理组中枯草芽孢杆菌(Bacillus subtilis)的量也明显增加。【结论】将肉杆菌Hg4-03作为益生菌饲喂贡嘎蝠蛾幼虫有助于维持幼虫肠道菌群多样性平衡,这为贡嘎蝠蛾人工或半人工养殖提供了一定的参考价值。     

骆驼瘤胃内降解含氮杂环化合物细菌的多样性

【目的】作为典型的荒漠动物,骆驼能够采食其他动物不能够食用的具有强烈气味的或有毒的植物,而不影响其正常生理代谢。研究发现骆驼采食的植物毒素与吡啶、喹啉、吲哚等杂环化合物具有相似的化学结构,所以研究骆驼体内是否存在潜在的杂环化合物降解菌具有重要意义。【方法】本研究采集3头骆驼瘤胃内容物,分别以吡啶、喹啉和吲哚3种含氮杂环化合物为唯一碳源和氮源进行5代富集培养。通过高通量测序技术对瘤胃内容物和5代富集培养细菌进行了测序分析。【结果】骆驼肠道中降解杂环化合物(吡啶、喹啉、吲哚)细菌群体样品中变形菌门、放线菌门、拟杆菌门、浮霉菌门和厚壁菌门等5个门类丰富度最高。骆驼瘤胃内降解吡啶的优势菌可能属于鞘氨醇杆菌属和不动杆菌属,降解吲哚的优势菌主要属于芽孢杆菌属,而降解喹啉的优势菌可能以赖氨酸芽孢杆菌属和鞘氨醇杆菌属为主。【结论】骆驼瘤胃原始样品经过吡啶、喹啉、吲哚富集5代后,与原始样品比较优势菌群发生了较大的改变,这说明骆驼瘤胃内蕴含降解吡啶、吲哚和喹啉的细菌,但对吡啶、吲哚和喹啉的降解过程中发挥降解作用的细菌群落存在差异。     

冲绳海槽热液区可培养硫氧化细菌多样性及其硫氧化特性

冲绳海槽热液区独特的地质环境孕育了特殊的生物群落,硫氧化细菌作为生物地球化学循环的重要参与者在热液生态系统中发挥着至关重要的作用。【目的】通过硫氧化菌株的分离培养揭示冲绳海槽热液区可培养硫氧化细菌的多样性和硫氧化活性。【方法】采用多种培养基对冲绳海槽热液区不同沉积物样品中的硫氧化细菌进行富集培养和分离纯化;利用16S rRNA基因序列确定硫氧化细菌的分类地位并进行系统发育分析;采用碘量法对典型硫氧化菌株硫氧化活性进行检测。【结果】本研究从冲绳海槽热液区样品中共分离鉴定85株硫氧化细菌,分属于α-变形菌纲、γ-变形菌纲、放线菌门和厚壁菌门,优势属为氢弧菌属(Hydrogenovibrio)、拉布伦氏菌属(Labrenzia)、深海海旋菌属(Thalassospira)和海杆状菌属(Marinobacter)。硫氧化活性检测结果表明,7株典型硫氧化菌株对硫代硫酸钠的降解活性介于31%–100%之间,其中泰坦尼克号盐单胞菌SOB56 (Halomonas titanicae SOB56)、南极海杆状菌SOB93(Marinobacter antarcticus SOB93)、印度硫氧化粗杆菌SOB107 (Thioclava indica SOB107)和嗜温氢弧菌CJG136 (Hydrogenovibrio thermophiles CJG136)可以完全降解硫代硫酸钠。【结论】冲绳海槽热液区可培养硫氧化细菌的多样性丰富,为研究该热液区的硫循环过程提供了实验材料和理论基础,多种硫氧化活性菌株的获得极大地丰富了菌种资源,为探究深海热液区硫循环的能量代谢途径和分子机制奠定基础。     

Biodiversity of polycyclic aromatic hydrocarbon-degrading bacteria from deep sea sediments of the Middle Atlantic Ridge

The bacteria involved in the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in deep sea subsurface environments are largely unknown. In order to reveal their biodiversity, sediments from 2.2 m under the bottom surface at a water depth of 3542 m were sampled on the Middle Atlantic Ridge with a gravity column sampler. The sediments were promptly enriched with either crude oil or a mixture of PAHs (naphthalene, phenanthrene and pyrene) as the sole carbon source, and further enriched with the PAH mixture mentioned above in the lab. The resulting consortia were named C2CO and C2PPN respectively. Their bacterial composition was analysed with plate cultivation, PCR-DGGE and 16S rDNA library analysis. On plates, isolates belonging to Pseudoalteromonas , Halomonas , Marinobacter , Thalassospira and Tistrella dominated the culturable populations. With PCR-DGGE, five major bands closely related to Cycloclasticus , Alteromonas , Thalassospira , Alcanivorax and Rhodospirillaceae were detected in consortium C2CO, while only one major band of Cycloclasticus was detected in consortium C2PPN. In addition, the dynamics of community structure in response to aromatic substrate alterations were examined. As a result, three ribotypes of Cycloclasticus were detected by 16S rDNA library analysis, one which played a key role in phenanthrene degradation; two Alteromonas bacteria dominated the naphthalene reselected consortium. Although bacteria of the two genera grew as the main members of the communities, none of them were isolated, probably owing to their poor cultivability. These results confirm that bacteria of Cycloclasticus are important obligate PAH degraders in marine environments, and coexist with other degrading bacteria that inhabit the deep subsurface sediment of the Atlantic. This supports the view that PAH accumulation and bioattenuation occur in remote areas consistently and continuously.     

Tistrella mobilis gen nov,sp nov,a novel polyhydroxyalkanoate-producing bacterium belonging to alpha-Proteobacteria

Strain IAM 14872, isolated from wastewater in Thailand, is capable of producing polyhydroxyalkanoate. This bacterium is Gram-negative, rod-shaped, strictly aerobic and highly motile with a single polar flagellum. Both oxidase and catalase activities are positive. The G+C content of DNA is 67.5% and Q-10 is the major quinone. The major cellular fatty acids are C(18:1)omega7c, 2-OH C(18:0) and 3-OH C(14:0). On the basis of the 16S rDNA sequence analysis and phenotypic properties, it is proposed that the strain IAM 14872 be classified in a new genus as Tistrella mobilis gen. nov., sp. nov. The type strain is IAM 14872(T) (=TISTR 1108(T)).     

Isolation and characterization of pyrene metabolizing microbial consortia from the plant rhizoplane

Most research on the ecology of PAH degrading bacteria in the rhizosphere has focused on individual strains that grow on specific PAHs. Thus, there are fundamental questions as to importance of microbial consortia for PAH degradation in the plant rhizosphere. The study reported here characterized cultivable pyrene degrading rhizoplane microbial communities from two different plant species using a root printing technique on agar plates. Colonies were revealed by formation of clearing zones on medium containing a thin film of pyrene on the surface of a mineral nutrient agar. Prints of the rhizoplane colonies were obtained from roots of Melilotus officinalis (sweet yellow clover) and Andropogon gerardii (big bluestem) plants. Phylogenetic characterizations of selected pyrene degrading colonies were assessed by PCR-DGGE and DNA sequencing. Results showed that different populations of cultivable pyrene degraders were obtained from representative consortia that were examined. Many of the PAH degrading consortia consisted of mixtures of bacterial species that were unable to degrade pyrene by themselves. While this study focused on culturable PAH degraders, the results suggest that pyrene degradation in the rhizosphere commonly involves the activity of bacterial consortia in which various species of bacteria interact to achieve PAH degradation.     

多环芳烃降解菌的筛选、鉴定及降解特性

【目的】多环芳烃(PAHs)是一类普遍存在于环境中且具有高毒性的持久性有机污染物,高效降解菌的筛选对利用生物修复技术有效去除环境中的多环芳烃具有重要意义。研究拟从供试菌株中筛选多环芳烃高效降解菌,并分析其降解特性,为多环芳烃污染环境的微生物修复提供资源保障和科学依据。【方法】采用平板法从25株供试菌株中筛选出以菲和芘为唯一碳源和能源的高效降解菌,经16S rRNA基因序列进行初步鉴定,通过单因素实验法分析其在液体培养基中的降解特性。【结果】筛选出的3株多环芳烃高效降解菌SL-1、02173和02830经16S rRNA基因序列分析,02173和02830分别与假单胞菌属中的Pseudomonas alcaliphila和Pseudomonas corrugate同源性最近,SL-1为本课题组发表新类群Rhizobium petrolearium的模式菌株;降解实验表明,菌株SL-1 3 d内对单一多环芳烃菲(100 mg/L)和芘(50 mg/L)的降解率分别达到100%和48%,5 d后能够降解74%的芘;而其3 d内对混合PAHs中菲和芘的降解率分别为75.89%和81.98%。菌株02173和02830 3 d内对混合多环芳烃中萘(200 mg/L)、芴(50 mg/L)、菲(100 mg/L)和芘(50 mg/L)的降解率均分别超过97%。【结论】筛选出的3株PAHs降解菌SL-1、02173和02830不仅可以高效降解低分子量PAHs,还对高分子量PAHs具有很好的降解潜力。研究表明,由于共代谢作用低分子量多环芳烃可促进高分子量多环芳烃的降解,而此时低分子量多环芳烃的降解将受到抑制。     

深海多环芳烃降解菌新鞘氨醇杆菌H25的降解特性及降解基因

[目的]为了从深海环境中筛选新的多环芳烃降解菌,了解其降解基因及降解特性.[方法]以原油作为碳源从印度洋深海海水样品中富集筛选出降解能力较强的多环芳烃降解菌,并根据已报道的相关菌属的多环芳烃起始双加氧酶大亚基序列及侧翼序列设计兼并引物进行扩增.[结果]获得了1株能够高效降解原油、柴油及多种多环芳烃的菌株H25.经16S rDNA序列系统发育分析表明它属于新鞘氨醇杆菌属(Novosphingobium)(96%).并从该菌株中扩增获得2条相似度为91.0%双加氧酶基因片段.2条序列在NCBI上Blastn分析表明均与菌株N.aromaticivorans DSM12444T的降解质粒pNL1上的双加氧酶大亚基具有最高相似度,分别为99.6%和91.0%.根据pNL1上的双加氧酶序列设计引物获得了包含H25双加氧酶大亚基及上下游序列的2个基因片段H25 Ⅰ(2.9kb)和H25Ⅱ(4.5kb).另外,单碳降解实验表明H25对联苯、2-甲基萘、2,6-二甲基萘、菲、二苯并噻吩、二苯并呋喃等均有较好的降解能力.[结论]H25菌株是Novosphingobium属可能的新种.深海细菌在大洋环境多环芳烃污染的自然净化中起到一定作用,并在环境生物修复中有较大的应用前景.     

Development of specific oligonucleotide probes for the identification and in situ detection of hydrocarbon-degrading Alcanivorax strains

The genus Alcanivorax comprises diverse hydrocarbon-degrading marine bacteria. Novel 16S rRNA-targeted oligonucleotide DNA probes (ALV735 and ALV735-b) were developed to quantify two subgroups of the Alcanivorax / Fundibacter group by fluorescence in situ hybridization (FISH), and the conditions for the single-mismatch discrimination of the probes were optimized. The specificity of the probes was improved further using a singly mismatched oligonucleotide as a competitor. The growth of Alcanivorax cells in crude oil-contaminated sea water under the biostimulation condition was investigated by FISH with the probe ALV735, which targeted the main cluster of the Alcanivorax / Fundibacter group. The size of the Alcanivorax population increased with increasing incubation time and accounted for 91% of the 4',6-diamidino-2-phenylindole (DAPI) count after incubation for 2 weeks. The probes developed in this study are useful for detecting Alcanivorax populations in petroleum hydrocarbon-degrading microbial consortia.     

Biodegradation of polyethylene terephthalate (PET) by diverse marine bacteria in deep-sea sediments

PET plastic waste entering the oceans is supposed to take hundreds of years to degrade and tends to accumulate in the deep sea. However, we know little about the bacteria capable of plastic degradation therein. To determine whether PET-degrading bacteria are present in deep-sea sediment, we collected the samples from the eastern central Pacific Ocean and initiated microbial incubation with PET as the carbon source. After enrichment with PET for 2 years, we gained all 15 deep-sea sediment communities at five oceanic sampling sites. Bacterial isolation for pure culture and further growth tests confirmed that diverse bacteria possess degradation ability including Alcanivorax xenomutans BC02_1_A5, Marinobacter sediminum BC31_3_A1, Marinobacter gudaonensis BC06_2_A6, Thalassospira xiamenensis BC02_2_A1 and Nocardioides marinus BC14_2_R3. Furthermore, four strains were chosen as representatives to reconfirm the PET degradation capability by SEM, weight loss and UPLC-MS. The results showed that after 30-day incubation, 1.3%–1.8% of PET was lost. De-polymerization of PET by the four strains was confirmed by the occurrence of the PET monomer of MHET and TPA as the key degradation products. Bacterial consortia possessing PET-degrading potential are prevalent and diverse and might play a key role in the removal of PET pollutants in deep oceans.     

Evaluation of bacterial strategies to promote the bioavailability of polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbon (PAHs)-degrading bacteria may enhance the bioavailability of PAHs by excreting biosurfactants, by production of extracellular polymeric substances, or by forming biofilms. We tested these hypotheses in pure cultures of PAHs-degrading bacterial strains. Most of the strains did not substantially reduce the surface tension when grown on PAHs in liquid shaken cultures. Thus, pseudo-solubilization of PAHs in biosurfactant micelles seems not to be a general strategy for these isolates to enhance PAHs-bioavailability. Three semi-colloid Sphingomonas polysaccharides all increased the solubility of PAHs (Gellan 1.3- to 5.4-fold, Welan 1.8- to 6.0-fold and Rhamsan 2.4- to 9.0-fold). The increases were most pronounced for the more hydrophobic PAHs. The polysaccharide-sorbed PAHs were bioavailable. Mineralization rates of 9-[14C]-phenanthrene and 3-[14C]-fluoranthene by Sphingobium EPA505, were similar with and without sphingans, indicating that mass-transfer rates from PAHs crystals to the bulk liquid were unaffected by the polysaccharides. Biofilm formation on PAHs crystals may favor the diffusive mass transfer of PAHs from crystals to the bacterial cells. A majority of the PAHs-degraders tested formed biofilms in microtiter wells coated with PAHs crystals. For strains capable of growing on different PAHs; the more soluble the PAHs, the lower the percentage of cells attached. Biofilm formation on PAHs-sources was the predominant mechanism among the tested bacteria to overcome mass transfer limitations when growing on poorly soluble PAHs.     

胜利油田滩涂区石油降解菌的筛选、鉴定及其多样性分析

基于传统的实验方法,对胜利油田滩涂区土壤中石油降解菌进行了筛选和鉴定,并利用PCR-DGGE (变性梯度凝胶电泳)技术分析了胜利油田滩涂区的菌群多样性.结果表明：由研究区土壤中筛选出13株石油降解菌,其中,6株石油降解菌的石油降解率>90%,能降解大部分C₁₂～C₂₆的石油烷烃,系统发育学鉴定为Alcanivorax、Halomonas和Marinobacter,均属于γ-proteobacteria分支;胜利油田滩涂区未培养优势菌有Sulfurovum、Gillisia和Arcobacter;该区优势菌群中γ-proteobacteria所占比重较大,其次为α-proteobactiria、ε-proteobactiria、Actinobacteria 和Flavobacteria.     

我国主要河口沉积物中多环芳烃细菌降解及生物修复强化方式的研究进展

河口是海洋及陆地交互作用的集中地带,其生态环境的健康状况对所在地区人类居住及社会经济的可持续发展十分重要。近年来,河口城市的快速发展导致了大量的多环芳烃(polycyclic aromatic hydrocarbons,PAHs)在河口沉积物中积累,持久地影响水生生态系统的健康,其降解与转化逐渐成为近年来的研究热点。本文总结发现,我国主要河口(珠江口、长江口、辽河口、海河口)沉积物中的PAHs降解菌主要分布于假单胞菌门、放线菌门及芽孢杆菌门,其中克雷伯氏菌属、芽孢杆菌属及假单胞菌属报道较多。在河口沉积物中,PAHs的细菌降解主要是通过低效率的厌氧降解途径。低氧、高盐度是PAHs细菌降解的不利条件,温度与pH值的变化也为实地生物修复的应用效率带来了不确定性。表面活性剂、营养物与外源电子受体的添加以及共代谢作用均可促进沉积物细菌对PAHs的降解。目前多数研究以实验室规模开展,而河口沉积物生境复杂,建议未来针对河口沉积物的环境特点进行PAHs降解功能菌株种质资源的挖掘,并根据实际情况灵活制定强化策略。本综述为进一步从我国主要河口沉积物中筛选PAHs高效降解菌及其利用提供了思路与参考。