异化铁还原梭菌Clostridium bifermentans EZ-1产氢与电化学特性

【目的】从黄河三角洲滨海湿地土壤中获得同时具备产氢、产电以及异化铁还原能力的多功能菌株。【方法】通过厌氧分离技术从黄河三角洲土壤中分离得到纯菌株,16S r RNA基因测序后与数据库已有序列进行比对。利用革兰氏染色及扫描电镜观察菌株形态,并用气相色谱(gas chromatography,GC)和液相色谱(high performance liquid chromatography,HPLC)检测其生理代谢底物和产物。通过添加不同形态铁氧化物检测该菌株Fe(Ⅲ)的还原能力。构建微生物燃料电池(Microbial fuel cells,MFCs)检测该菌株的电化学活性。【结果】16S r RNA基因序列比对发现其与双酶梭菌Clostridium bifermentans的相似性达97.99%。革兰氏染色结果显示为阳性菌。能够利用葡萄糖为底物发酵产生氢气、二氧化碳、乙酸和丁酸。Fe(Ⅲ)还原能力检测发现,其不仅可以还原柠檬酸铁(FeC_6H_5O_7)中可溶性的Fe(Ⅲ),还可以还原无定形铁水铁矿(FeOOH)和晶型纳米磁铁矿(Fe_3O_4)中的Fe(Ⅲ)。此外,经MFCs检测发现,该菌具有电化学活性,最大电流输出密度可达6.5 m A/m~2,且在0.15 V位置存在氧化峰。【结论】本研究从土壤中成功分离得到了一株同时具有产氢、产电以及异化铁还原能力的多功能梭菌菌株,保藏并命名为Clostridium bifermentans EZ-1。     

微嗜酸寡养单胞菌EFS1的产电性能及在污水处理中的应用

【背景】微生物燃料电池(Microbial Fuel Cell,MFC)作为一种新型的燃料电池资源,在产电的同时可应用于污水处理领域,达到资源最大化的目的。【目的】从MFC中分离获得一株可培养微生物,研究其产电特性及在污水处理中的微生物絮凝、重金属耐受、苯酚降解性能,为扩展产电菌资源库提供理论基础。【方法】利用WO_3纳米探针从MFC阳极中筛选获得一株具备产电和絮凝性能的菌株,命名为EFS1。运用循环伏安分析结合扫描电镜观测阳极电极;改变外电阻测定极化曲线和功率密度曲线。测定菌株的絮凝、重金属耐受及苯酚降解性能。【结果】经16S rRNA基因序列分析,结合形态学和生理生化鉴定菌株EFS1为微嗜酸寡养单胞菌(Stenotrophomonas acidaminiphila)。菌株EFS1具有稳定的产电周期,周期电压最高可达300m V,功率密度可达56.25m W/m~2;扫描电镜发现菌株存在直接接触电极及分泌电子中介体传递电子的方式;MFC内阻为1 000Ω左右。有氧条件下菌株的絮凝率可达到70%,存在电子受体的无氧环境中可达到80%;该菌株还具有良好的Cd~(2+)、Cu~(2+)、Mn~(2+)耐受性及苯酚降解性能,在48 h、2–4 mg/L时苯酚降解率达到了100%。【结论】研究验证了产电菌EFS1具备絮凝能力、重金属耐受、苯酚降解的可能性,为产电菌的开发及污水处理方面提供理论依据。     

一株产电菌Nitratireductor sp. WJ5-4的筛选及产电分析

【目的】从生物垃圾燃料电池阳极淋洗液中分离一株产电菌WJ5-4,研究其产电特性。【方法】根据菌株的形态、生理生化性质及16S r RNA基因测序分析确定其种属,以该菌株为产电菌,以生物垃圾为底物,构建微生物燃料电池(Microbial fuel cell,MFC),研究在不同接种浓度和底物固含量条件下菌株的产电性能。【结果】菌株WJ5-4被初步鉴定属于Nitratireductor属,当接种量200 m L时可获得最大功率密度135.16 m W/m2、稳定电压370 m V和总有机碳(Total organic carbon,TOC)降解率41.46%。当底物固含量为23%时,可获得最大功率密度163.69 m W/m2、稳定电压434 m V和TOC降解率46.29%。【结论】WJ5-4菌能够利用较高固含量的生物垃圾产电,产电周期较长,为下一步微生物燃料电池处理生物垃圾提供科学依据。     

一株耐盐产电菌Shewanella algae E-1的分离及其产电特性分析

【背景】产电微生物的种类和电化学活性机制对微生物燃料电池的产电性能有着重要的影响。【目的】从海水中分离获得一株耐盐产电微生物,研究其产电特性并鉴定种属信息。【方法】以取自南海的海水为接种液启动并运行阳极液中含有不同盐浓度的微生物燃料电池,从富集的阳极生物膜上分离得到一株纯培养的微生物菌株,命名为E-1。通过接种于阳极液中添加不同盐浓度的微生物燃料电池中对其产电特性进行分析,并利用形态学观察、Biolog分析和16SrRNA基因序列比对相结合的方法进行种属鉴定。【结果】菌株E-1在无外源添加和外源添加6.6%NaCl条件下产生的功率密度分别为51.69 m W/m2和26.56 m W/m2,这与其良好的耐盐能力相关。菌株E-1被鉴定为海藻希瓦氏菌(Shewanella algae),表现出多样的底物利用能力,生长的温度范围为25-40°C,pH范围为5.0-10.0。【结论】这是首次对Shewanella algae种内微生物产电性能及其在微生物燃料电池中应用的报道,丰富了产电微生物的多样性,菌株E-1能够在较高盐浓度条件下表现出良好的产电性能,为微生物燃料电池在海水资源化处理方面的应用提供新的实验材料。     

微生物燃料电池利用乳酸产电性能与微生物群落分布特征

【目的】为探讨以乳酸为基质的微生物燃料电池(Microbial fuel cell,MFC)产电性能以及微生物群落在阳极膜、悬浮液、阳极沉淀污泥中的分布特征,【方法】试验建立了双室MFC,以乳酸为阳极主要碳源,研究了反应器的启动过程及产电效能,同时以电镜和PCR-变性梯度凝胶电泳(Denaturing gradient gelelectrophoresis,DGGE)技术解析了微生物群落的空间分布特征。【结果】结果表明,反应器启动第7天时外电压达到0.56 V,当外阻为80Ω时,电流密度为415 mA/m2,MFC的功率密度达到最大值82 mW/m2。电镜观察发现大量杆菌附着在阳极表面,结合较为紧密;DGGE图谱显示阳极膜表面微生物与种泥最为相似,与阳极悬浮液、底部沉淀污泥中的主要菌群一致,条带序列与睾丸酮丛毛单胞菌(Comamonas testosteroni)和布氏弓形菌(Arcobacter butzleri)等最为相似。【结论】本研究表明以乳酸为基质MFC可产生较高的功率密度,阳极附着的优势菌与接种污泥来源密切相关。     

一株产纤维素酶菌株的分离、鉴定及产酶特性

【目的】筛选并鉴定一株产纤维素酶的菌株,初步探究该菌的产酶特性,为综合利用纤维素筛选菌源。【方法】在常温条件下,采用滤纸培养基对菌种富集,采用CMC-Na初筛纤维素降解菌,采用LB培养基分离纯化菌株,经形态学、生理生化特征试验、16S r RNA基因序列测定等分析筛选菌株的系统分类地位。单因素试验确定培养时间、培养温度、初始p H及Na Cl浓度对筛选菌株产酶活力的影响。【结果】从腐烂的玉米秸秆中分离出一株在常温下产纤维素酶细菌KZ-2,根据菌落形态特征、生理生化特征鉴定以及16S r RNA基因序列分析,初步鉴定KZ-2为肠杆菌(Enterobacter sp.),为潜在新种。产酶条件实验显示:该菌使用产酶发酵培养基120 h产酶量达到最大值,在25–35°C、初始p H 4.5–5.5、Na Cl浓度1.0%–2.0%范围内为最佳产酶条件,在最适条件下酶活可达80.93 U/m L。该菌株所产纤维素酶最适反应p H为7.0,最适反应温度为50°C。【结论】KZ-2是一株具有降解纤维素能力的细菌,在常温下即可分泌纤维素酶,并且该菌株为潜在新种,具有潜在的开发价值。     

产甲烷分离物中Clostridium spp.与Methanosarcina barkeri潜在的种间直接电子传递

【目的】革兰氏阴性菌Geobacter metallireducens可以与乙酸型产甲烷菌Methanosaeta harundinacea或Methanosarcina barkeri通过种间直接电子传递(DIET)还原CO2产甲烷。本实验室前期的研究发现Methanosarcina mazei和Geobacteraceae在铁还原富集培养中形成团聚体,可能存在直接电子传递。然而,革兰氏阳性菌(如Clostridium spp.)与产甲烷菌是否存在种间直接电子传递尚不明确。【方法】采用Hungate厌氧滚管法,以乙醇为唯一电子供体从铁还原富集培养体系中获得产甲烷分离物(S6)。通过T-RFLP及克隆文库分析群落多样性,结合循环伏安法等电化学方法研究产甲烷分离物的电活性。【结果】Clostridium spp.(与C.tunisiense相似性最高)和M.barkeri分别在S6细菌和古菌群落中占优势。S6与G.metallireducens共培养后铁还原和产甲烷能力未明显增加,Clostridium spp.可能与G.metallireducens类似,将电子直接传递给产甲烷菌M.barkeri产甲烷。此外,电化学检测发现,在用透析袋包裹电极阻碍微生物与电极表面通过直接接触形成生物膜的条件下,电流密度显著降低,并且循环伏安扫描无明显氧化还原峰。【结论】产甲烷分离物S6中存在直接电子传递途径。本工作提出在产甲烷分离物中占优势的革兰氏阳性菌Clostridium spp.和M.barkeri之间可能存在种间直接电子传递。     

洋河酒窖泥细菌群落结构与菌株产酸能力分析

【背景】窖泥微生物的种类及其代谢产物类型是影响浓香型白酒发酵过程中丁酸和己酸等白酒中主要有机酸合成的影响因素之一。【目的】揭示浓香型白酒不同窖龄窖泥细菌群落结构,研究厌氧细菌产酸性能,阐明窖泥细菌与白酒中有机酸合成的相关性。【方法】通过Illumina HiSeq高通量测序,基于16S rRNA基因序列分析不同窖龄窖泥细菌的组成。分离获得厌氧细菌,通过比较菌株产丁酸和己酸能力来分析窖泥的微生物代谢特性。【结果】洋河酒窖泥细菌主要分布于梭菌纲(Clostridia)、拟杆菌纲(Bacteroidia)、互营养菌纲(Synergistia)和芽孢杆菌纲(Bacilli)。20年窖龄的窖泥中氢孢菌属(Hydrogenispora)和瘤胃梭菌属(Ruminiclostridium)丰度显著增加。窖泥细菌间相关性分析表明,瘤胃梭菌属(Ruminiclostridium)为窖泥中影响最大的核心微生物,很多微生物与梭菌属(Clostridium)菌株之间多为相互促进关系。通过传统可培养方法共分离得到梭菌目(Clostridiales)的20株厌氧菌。其中梭菌属(Clostridium)菌株产酸能力高于其他菌属,酪丁酸梭菌(Clostridium tyrobutyricum)和丁酸梭菌(Clostridium butyricum)产丁酸和己酸的能力最强。产丁酸能力最高的菌主要分离自5年和20年窖龄窖泥,产己酸能力最高的菌分离自20年窖龄窖泥。【结论】解析了浓香型白酒不同窖龄窖泥的细菌组成,并对菌株产丁酸和己酸的能力进行了比较,为揭示窖泥微生物功能及其对白酒风味物质合成的影响奠定了相关的研究基础。     

一株新型同型产乙酸菌Clostridium sp.的自养和异养生长特性

【背景】同型产乙酸菌是一类利用乙酰辅酶A途径固定CO_2合成自身细胞物质并生成乙酸、乙醇等代谢产物的厌氧菌群,其分布广泛、种类繁多且代谢多样。深入研究同型产乙酸菌菌株的代谢能力及特性,对探索该种群的生理生化特性及其环境作用至关重要。【目的】研究一株同型产乙酸菌Clostridium sp. BXX的最适培养条件及其自养与异养生长特性。【方法】设置BXX菌株培养温度10-55°C、初始pH 6.0-9.0、NaCl浓度0-2.0%、不同氮源,测定菌体细胞含量和产物生成浓度,确定菌株最适培养条件。研究BXX菌株分别以H_2/CO_2、合成气、CO、葡萄糖、1,2-丙二醇、甲酸钠、乙二醇甲醚、甘油、丙酮酸和乳酸为底物时的底物消耗、产物生成、菌体细胞含量和pH等,探究其自养和异养生长特性。【结果】BXX菌株的最适培养温度为30°C,初始pH为7.0,NaCl浓度为1.0%,氮源为酵母粉。BXX菌株能以H2/CO2、合成气、葡萄糖、1,2-丙二醇、甲酸钠、乙二醇甲醚和甘油为底物生长,不能以CO、丙酮酸或乳酸为底物生长。【结论】BXX菌株既能自养生长产乙酸,又能异养生长产乙醇。BXX菌株是乙酸发酵的优良菌种资源,有较好的工业应用潜力。     

褐藻胶降解菌的筛选、鉴定及产酶条件优化

【目的】筛选一株能降解褐藻胶的菌株,并优化产酶条件以提高褐藻胶裂解酶活力。【方法】从漳州海域采集到海水和海泥,以海藻酸钠为唯一碳源,通过富集培养、初筛、复筛筛选到一株能够降解褐藻胶的菌株。依据16S rRNA序列分析、生理生化特征、菌体形态及菌落特征对该菌进行鉴定。通过单因素和正交试验对该菌的产酶条件进行优化。【结果】该菌属于海科贝特氏菌,命名为Cobetiamarina HQZ08。该菌株最佳的产酶培养基组成为:海藻酸钠7.00g/L、蛋白胨3.00g/L、NaCl30.00g/L,K2HPO4·3H2O 1.25 g/L。最佳发酵条件为:接种量2%,接种龄12 h,培养基起始pH为7.0,培养温度25°C,培养时间24 h。优化后褐藻胶裂解酶活力达到68.5 U/mL,TLC法分析酶解产物为褐藻胶寡糖。【结论】HQZ08菌株可以用于降解褐藻胶,产生聚合度为2–6的褐藻胶寡糖。     

Foreign exploration for Scirtothrips perseae Nakahara (Thysanoptera: Thripidae) and associated natural enemies on avocado (Persea americana Miller)

Scirtothrips perseae Nakahara was discovered attacking avocados in California, USA, in 1996. Host plant surveys in California indicated that S. perseae has a highly restricted host range with larvae being found only on avocados, while adults were collected from 11 different plant species. As part of a management program for this pest, a “classical” biological control program was initiated and foreign exploration was conducted to delineate the home range of S. perseae, to survey for associated natural enemies and inventory other species of phytophagous thrips on avocados grown in Mexico, Guatemala, Costa Rica, the Dominican Republic, Trinidad, and Brazil. Foreign exploration efforts indicate that S. perseae occurs on avocados grown at high altitudes (>1500 m) from Uruapan in Mexico south to areas around Guatemala City in Guatemala. In Costa Rica, S. perseae is replaced by an undescribed congener as the dominant phytophagous thrips on avocados grown at high altitudes (>1300 m). No species of Scirtothrips were found on avocados in the Dominican Republic, Trinidad, or Brazil. In total, 2136 phytophagous thrips were collected and identified, representing over 47 identified species from at least 19 genera. The significance of these species records is discussed. Of collected material 4% were potential thrips biological control agents. Natural enemies were dominated by six genera of predatory thrips (Aeolothrips, Aleurodothrips, Franklinothrips, Leptothrips, Scolothrips, and Karnyothrips). One genus each of parasitoid (Ceranisus) and predatory mite (Balaustium) were found. Based on the results of our sampling techniques, prospects for the importation of thrips natural enemies for use in a “classical” biological control program in California against S. perseae are not promising.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

Biological control of three floating water weeds,<Emphasis Type="Italic">Eichhornia crassipes,Pistia stratiotes</Emphasis>, and <Emphasis Type="Italic">Salviniamolesta</Emphasis> in the Republic of Congo

Since 1999, four specific weevils (Coleoptera, Curculionidae) were released in the Republic of Congo against three exotic floating water weeds: Neochetina eichhorniae Warner and N. bruchi Hustache against water hyacinth, Neohydronomus affinis Hustache against water lettuce, and Cyrtobagous salviniae Calder and Sands against water fern. Recoveries of exotic weevils were made from all 24 release sites except one, and all four species have established and spread (up to 800 km for water hyacinth weevils). Within a few years of releases, control of water fern and water lettuce was such that fishing and navigation could be resumed, while reductions of water hyacinth populations were only beginning.     

A molecular phylogeny of Hebeloma species from Europe

In order to widen the scope of existing phylogenies of the ectomycorrhizal agaric genus Hebeloma a total of 53 new rDNA ITS sequences from that genus was generated, augmented by sequences retrieved from GenBank, and analysed using Bayesian, strict consensus and neighbour joining methods. The lignicolous Hebelomina neerlandica, Gymnopilus penetrans, and two species of Galerina served as outgroup taxa. Anamika indica, as well as representatives of the genera Hymenogaster and Naucoria, were included to test the monophyly of Hebeloma, which is confirmed by the results. Hebeloma, Naucoria, Hymenogaster and Anamika indica cluster in a strongly supported monophyletic hebelomatoid clade. All trees largely reflect the current infrageneric classification within Hebeloma, and divide the genus into mostly well-supported monophyletic groups surrounding H. crustuliniforme, H. velutipes, H. sacchariolens, H. sinapizans, and H. radicosum, with H. sarcophyllum being shown at an independent position; however this is not well supported. The section Indusiata divides with strong support into three groups, the position of the pleurocystidiate Hebeloma cistophilum suggests the possible existence of a third subsection within sect. Indusiata. Subsection Sacchariolentia is raised to the rank of section.     

Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Die GattungKarschia — Bindeglied zwischen bitunicaten Ascomyceten und lecanoralen Flechtenpilzen?

The genusKarschia, in the earlier sense, including saprophytes and parasites on lichens, has been thought to be a non-lichenized parallel genus of the lichen genusBuellia. Modern workers included it on the one hand inBuellia, on the other hand combined it with bitunicate ascomycetes. It is now proved thatKarschia is heterogeneous and contains but superficially similar members both of the genusBuellia of theLecanorales and of typical or masked bitunicateAscomycetes. Therefore, it can not be regarded as a link betweenLecanorales andDothideales. The type species ofKarschia belongs to theDothideales.

     

Demographic characteristics of an intertidal bay goby (Lepidogobius lepidus)

Synopsis In a fourteen month study (May 1976 – June 1977) I examined the following characteristics of an intertidal bay goby (Lepidogobius lepidus) in Morro Bay, California, U.S.A.: annual and seasonal patterns of abundance, age composition and growth rates, survivorship and mortality patterns, and the reproductive cycle for female gobies. Fishes were collected with the aid of quinaldine and otoliths and ovaries removed. Age and growth rates were estimated from otolith annuli using a back calculation formula and a Brody-Bertalanffy growth curve. Mortality rates were derived using the methods of Heincke (1913), Robson & Chapman (1960), mean age, and a catch curve (Ricker 1975). A gonad index was used to describe the annual reproductive cycle. Results indicated that abundance fluctuated seasonally and that these fluctuations appeared to be caused by reproductive emigrations. Bay gobies reached an age of 7+ and a standard length of 87 mm. Growth was relatively constant (6 mm yr⁻¹) until age 5, at which point it began to decline. The mean rates of survivorship, mortality, and instantaneous mortality were 0.75, 0.25, and 0.29 respectively. Mortality rates for individual age classes ranged from 0.13 to 0.51 and increased with age. This stock appears to reproduce mainly during the winter.     

Systematic significance of mature embryo of bamboos

The mature embryo of seven species belonging to five genera of Indian bamboos is described. In all these the basic pattern of embryo organisation is same: the scutellar and coleoptilar bundles are not separated by an internode, the epiblast is absent, the lower portion of the scutellum and the coleorhiza are separated by a cleft and the margins of embryonic leaves overlap. The features unique to fleshy fruited bamboos are: presence of a massive scutellum, the juxtaposition of plumule and radicle and the occurrence of a bud in the axil of the coleoptile. The fleshy fruit bearing bamboos should be classified into one group, the tribeMelocanneae. Evidence is provided to recognise additional groups in the subfamilyBambusoideae.