环境团面试题目及英文摘要.docx

1. 细菌吸收营养物质的方式有哪几种？ 水及小分子溶质可经过半透膜性质的细胞壁及细胞膜进入菌体。大分子的营养物质如蛋白质、多糖和脂类必须在细菌分泌的胞外酶作用下，分解为小分子可溶性物质后才被吸收。营养物质进入菌体的方式有：易化扩散、主动运转及基团移位。1.易化扩散：又称简单扩散。物质进入菌体仅以该物质在菌体内外之浓度差而透入，为一种不需能量的被动吸收。2.主动运转：又称主动吸收。其特点为：物质可逆浓度梯度由低浓度向高浓度转运；需要能量（可由细胞膜上的呼吸链供给）。3.基团移位：细菌对糖的吸收和积累，需要磷酸转运系统，即转运过程中必须磷酰化，这种物质运转方式称基团移位。2. 微生物之间的关系，举例说明。微生物与其他生物之间也是如此。它们之间的相互关系，忽略陌生，归纳起来基本上可分为互生、共生、寄生、拮抗(对抗) 4种。互生互惠互利互生关系分为偏利关系和互利关系，偏利关系指只有一方获利（奉献），互利则是互惠互利。共生共同依存互生关系的极端表现，形成特殊的共生体，不能分开独自生活拮抗(对抗)“竞争、斗争、战争”，包括竞争、毒害、捕食三种类型。举例：地衣中的真菌与藻类是共生关系；青霉菌与其周围细菌的是拮抗关系；活性污泥中细菌间的相互关系是竞争、互生（同种）等；冬虫夏草，是子囊菌寄生于鳞翅目幼虫而形成的。冬季，虫体蛰伏在土中，真菌孢子侵入虫体，并生长发育，使虫体内充满菌丝，幼虫死亡。来年温暖潮湿时，自幼虫的头部长出棒状子实体露出土面，形似野草，故谓“冬虫夏草”。3.细菌基因转移和重组的方式？1.接合作用：当细菌与细菌相互接触时，质粒DNA就可从一个细菌转移到另一个细菌。2.转化作用：由外源性DNA导入宿主细胞，并引起生物类型改变或使宿主细胞获得新的遗传表型的过程，称为转化作用。3.转导作用：当病毒从被感染的细胞释放出来，再次感染另一细胞时，发生在供体细胞与受体细胞之间的DNA转移及基因重组称为转导作用。4.转座(转位)：转座是指一个或一组基因从一个位置转到基因组的另一个位置。可分为插入序列转座和转座子转座。5基因重组:不同DNA分子间发生的共价连接称基因重组。有两种类型：位点特异的重组和同源重组4.什么是赤潮和水华，引发的原因？赤潮：海洋中一些微藻、原生动物或细菌在一定环境条件下爆发性增殖或聚集达到某一水平，引起水体变色或对海洋中其他生物产生危害的一种生态异常现象。 水华：就是淡水水体中藻类大量繁殖的一种自然生态现象，是水体富营养化的一种特征，主要由于生活及工农业生产中含有大量氮、磷的废污水进入水体后，蓝藻（严格意义上应称为蓝细菌）、绿藻、硅藻等藻类成为水体中的优势种群，大量繁殖后使水体呈现蓝色或绿色的一种现象。5. 如何调查土壤中微生物种类？1、经典的选择培养法：即采用选择培养的方法，对土壤样品中的细菌、放线菌、酵母菌、丝状真菌等几大类微生物进行分类培养，还可以采用详细的选择培养方式比如无氮培养基培养固氮微生物、利用MPN法测定氮循环微生物等等，从功能角度再细分一下微生物的种类组成；还可以通过寡营养、富营养、长周期培养等方法做进一步详细的分析。2、分子微生态学方法是基于DNA分析和测序基础上的分子微生态学研究方法，常用的有DGGE（变性梯度凝胶电泳）、克隆文库构建、T-RFLP以及宏基因组技术，对样品中的DNA进行电泳乃至测序分析，从分子水平确定样品中微生物的种类和数量。6.宏基因组学的概念及其应用？宏基因组学 (或元基因组学, metagenomics) 就是一种以环境样品中的微生物群体基因组为研究对象, 以功能基因筛选和/或测序分析为研究手段, 以微生物多样性、 种群结构、 进化关系、 功能活性、 相互协作关系及与环境之间的关系为研究目的的新的微生物研究方法。一般包括从环境样品中提取基因组 DNA, 进行高通量测序分析，或克隆DNA到合适的载体,导入宿主菌体,筛选目的转化子等工作。应用：极端环境中的微生物群落及功能的分析，如极地、深海、热泉等环境；从环境中探索寻找新的功能基因及无法培养的新的物种资源；利用宏基因学指导疾病的治疗，如各种胃肠道疾病与体内微生物群落的关系等。Transcriptome sequencing and annotation of the microalgae Dunaliella tertiolecta: Pathway description and gene discovery for production of next-generation biofuelsBackground: Biodiesel or ethanol derived from lipids or starch produced by microalgae may overcome many of the sustainability challenges previously ascribed to petroleum-based fuels and first generation plant-based biofuels. The paucity of microalgae genome sequences, however, limits gene-based biofuel feedstock optimization studies. Here we describe the sequencing and de novo transcriptome assembly for the non-model microalgae species, Dunaliella tertiolecta, and identify pathways and genes of importance related to biofuel production. Results: Next generation DNA pyrosequencing technology applied to D. tertiolecta transcripts produced 1,363,336 high quality reads with an average length of 400 bases. Following quality and size trimming, 45% of the high quality reads were assembled into 33,307 isotigs with a 31-fold coverage and 376,482 singletons. Assembled sequences and singletons were subjected to BLAST similarity searches and annotated with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) orthology (KO) identifiers. These analyses identified the majority of lipid and starch biosynthesis and catabolism pathways in D. tertiolecta.Conclusions: The construction of metabolic pathways involved in the biosynthesis and catabolism of fatty acids, triacylglycrols, and starch in D. tertiolecta as well as the assembled transcriptome provide a foundation for the molecular genetics and functional genomics required to direct metabolic engineering efforts that seek to enhance the quantity and character of microalgae-based biofuel feedstock.The metagenomics of soilAbstract: Phylogenetic surveys of soil ecosystems have shown that the number of prokaryotic species found in a single sample exceeds that of known cultured prokaryotes. Soil metagenomics, which comprises isolation of soil DNA and the production and screening of clone libraries, can provide a cultivation-independent assessment of the largely untapped genetic reservoir of soil microbial communities. This approach has already led to the identification of novel biomolecules. However, owing to the complexity and heterogeneity of the biotic and abiotic components of soil ecosystems, the construction and screening of soil-based libraries is difficult and challenging. This review describes how to construct complex libraries from soil samples, and how to use these libraries to unravel functions of soil microbial communities.Nuclear Genome Sequence Survey of the Dinoflagellate Heterocapsa triquetraAbstract: Dinoflagellates have among the largest nuclear genomes known, but we know little about their contents or organisation. Given the interest in dinoflagellate ecology, cell biology, and evolutionary biology, there are many reasons to thoroughly investigate the contents of dinoflagellate genomes, but because of their large size the only thorough samples to date have relied on expressed sequence tag surveys to analyse cDNAs. To complement this, there are some studies of the physical properties of dinoflagellate chromosomes, but no direct survey of the nature of the sequences contained within them. To start to build a picture of the contents of these genomes, we have sequenced over 230,000 bp from the nuclear genome of Heterocapsa triquetra, which has been estimated to be 1823 billion base pairs in total. The survey includes one putative gene with two relict spliced leaders, one putative pseudogene, and a small number of low complexity repeats, transposons, and other putat