高效降解地塞米松的产碱假单胞菌的驯化和筛选

目的为制备清除水环境地塞米松污染的微生物净化剂提供高效降解地塞米松的菌种。方法将从医院废水分离的可降解地塞米松的降解菌(产碱假单胞菌)接种于地塞米松磷酸钠培养液,常规孵箱37℃反复驯化培养。将驯化培养后的细菌接种于地塞米松磷酸钠琼脂平板,常规培养后,挑取单菌落,用高效液相色谱法测定其对地塞米松和地塞米松磷酸钠的降解作用并进行筛选,筛选出的菌株再经形态、染色性和16SrDNA鉴定。观察驯化菌生长特性和降解特性,并与降解菌比较。结果降解菌经驯化培养后,筛选到1株对地塞米松降解作用强的驯化菌,该菌在震荡培养下,对地塞米松磷酸钠的降解率从驯化前的50.86%提高到76.12%,将地塞米松降解为其他物质的降解率从23.63%提高到77.05%。在常规培养下,对地塞米松磷酸钠的降解率从驯化前的20.65%提高到73.84%,将地塞米松降解为其他物质的降解率从22.14%提高到43.08%(P=0.01)。驯化菌的生长曲线与降解菌相似,但降解曲线不同。在接种数小时后即出现降解作用,在48h出现降解高峰,比降解菌提前约48h。结论通过对地塞米松降解菌的驯化和筛选,成功地获得1株具有实用价值的高效降解地塞米松的驯化菌。     

高浓度有机质驯化活性污泥对比产生氢率的影响

利用驯化的活性污泥降解蔗糖制取氢气,设计了间歇浓度梯度驯化方案,驯化后不同来源活性污泥的糖代谢速率和产氢速率均有显著提高,使初始含糖量为76～84g/L(实际约6 6kgCOD/m3 ·d)培养液的比产氢率超过了含糖4 0g/L的低浓度培养液的比产氢率而无抑制现象。其中啤酒厂厌氧活性污泥、啤酒厂排污处污泥及南京城市排水沟污泥的蔗糖消耗率均达到85 %以上;比产氢率分别达2 2 4、2 35和2 14molH2 /mol蔗糖。揭示了高浓度有机质的活性污泥间歇浓度梯度驯化过程中糖代谢速率和产氢能力的演变规律,其适用于相当多的驯化活性活泥降解高浓度有机废液,以提高单位产氢能力。     

微生物絮凝剂及其产生菌的研究新进展

介绍了近几年来国内外微生物絮凝剂及其产生菌的一些发展概况,列举了近几年一些研究较深入的胞外生物高聚物絮凝剂的物质属性和化学组成.重点讨论了胞外生物高聚物絮凝剂的成分分析、絮凝机理以及影响絮凝活性的因素,详细综述了絮凝剂产生菌的遗传学和代谢机理方面的研究进展,文章最后提出微生物絮凝剂的发展趋势和研究方向.     

微生物燃料电池中假单胞菌F026的产电性能研究

基于微生物燃料电池的反应装置,从污水处理厂曝气池的污泥中通过富集,筛选和基于16S rRNA基因序列的系统发育分析等手段驯化出1株高效产电假单胞菌F026。以F026为阳极产电菌制作微生物燃料电池,考察了底物种类、温度和p H值等因素对微生物燃料电池产电性能的影响。结果表明,F026最适合在以可溶性淀粉为底物,p H为中性偏碱性,温度在30~35℃的环境下生长。在此条件下,微生物燃料电池的最高电压达到500 m V,体积功率密度达到2 W/m3。     

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。     

驯化噬菌体提高噬菌体对碳青霉烯类耐药肺炎克雷伯菌的杀菌能力

【目的】本研究旨在通过驯化提高噬菌体的裂解能力并降低其宿主菌耐受性产生的速度,从而提高对重要病原菌-碳青霉烯类耐药肺炎克雷伯菌(carbapenem-resistant Klebsiella pneumoniae, CRKp)的杀菌效果。【方法】以临床CRKp菌株Kp2092为宿主菌,利用双层琼脂平板法从污水中分离噬菌体并分析其裂解谱;对其中的广谱强裂解性噬菌体通过透射电镜观察其形态特征并进行全基因组测序;通过噬菌体-宿主连续培养进行噬菌体驯化,并比较驯化前后噬菌体生物学特性的差异。【结果】分离得到的9株肺炎克雷伯菌噬菌体中,噬菌体P55anc裂解能力强且裂解谱广,透射电镜观察发现其为短尾噬菌体。P55anc基因组全长40 301 bp,包含51个编码序列,其中27个具有已知功能,主要涉及核酸代谢、噬菌体结构蛋白、DNA包装和细胞裂解等。噬菌体P55anc经9 d的驯化后,得到3株驯化噬菌体。驯化后噬菌体杀菌能力增强,主要表现为细菌生长曲线显著下降、噬菌体暴发量增多、裂解谱扩大,且宿主菌对其产生抗性的概率显著降低。与此同时,驯化后的噬菌体在热处理、紫外暴露以及血清等环境下保持较好的稳定性。【结论】利用噬菌体-宿主连续培养的方法可对噬菌体进行驯化和筛选,驯化后的噬菌体杀菌效果更强,且在不同压力处理下的稳定性良好,而细菌产生噬菌体抗性的概率也降低。     

黄孢原毛平革菌BKMF-1767产絮凝剂PCF-1767的絮凝特性及其机理解析

【背景】传统絮凝剂的使用会带来安全和环境污染方面的问题,而微生物絮凝剂具有无毒、无二次污染、易生物降解的优点,因此寻找高效廉价的微生物絮凝剂具有重要意义。【目的】研究黄孢原毛平革菌BKMF-1767产生的胞外多糖絮凝剂的絮凝特性及机理。【方法】使用高岭土进行PCF-1767的絮凝活性测定,分析絮凝剂获取时间、Ca2+浓度、投加量、pH、温度对絮凝效率的影响,并测定PCF-1767的热稳定性。测定絮凝剂的单糖组成、糖苷键连接类型、多糖分子量、Zeta电位变化、对絮体形态观察,探讨了PCF-1767的絮凝机理。【结果】培养6–12 d获得的PCF-1767的絮凝活性良好;7 d絮凝剂要获得较好的絮凝效率至少需加入2 mmol/L Ca2+作为助凝剂,最佳投加浓度为0.75–1.35 mg/L,最适pH为3.0-9.0,对温度高于50°C的废水絮凝活性逐渐降低,经过沸水浴处理3 h后的絮凝活性几乎不变。PCF-1767中多糖的一级结构主要由葡萄糖以→4)Glup(1→的方式连接,多糖分子量随培养时间的延长而增大,变化范围为9.897×105–2.126×106 Da。结合Zeta电位变化与絮...     

活性污泥菌胶团/生物絮团形成菌的分离鉴定及基因组分析

从云南省泸西县的污水处理厂分离到一株菌胶团形成菌YN12,经过鉴定与象牙白伪杜擀氏菌(Pseudoduganella eburnea)10R5-21T模式株具有较近的亲缘关系,属于同一物种。为揭示该菌株与其他活性污泥细菌间菌胶团形成机制及碳源利用方面的异同,对该菌株进行全基因组测序、组装、注释及比较基因组学分析。结果表明:P. eburnea YN12株基因组大小约为5934 kb, G+C含量为63.9%,包含5313个蛋白质编码序列,具有与喜树脂动胶菌(Zoogloea resiniphila)MMB株、解叔丁醇水居菌(Aquincola tertiaricarbonis)RN12株及解壳聚糖松江菌(Mitsuaria chitosanitabida)XHY-A6株相似的胞外多糖生物合成途径、PrsK-PrsR双组分系统和PEP-CTERM胞外蛋白家族,共同介导和调控的菌胶团形成机制。与后者相比,菌株YN12中胞外多聚物(Extracellular polymeric substances, EPS)形成相关基因集中在大小约为72 kb的大型基因簇上,且能吸收利用的碳源特别是单糖、...     

筛选生物转化H_2/CO_2气体产乙酸的同型产乙酸菌混培物

同型产乙酸菌是一类具有巨大工业应用潜力的微生物类群,可利用合成气生成乙醇和乙酸等燃料和化学品。本研究采集城市污泥样品利用Hungate滚管法进行同型产乙酸菌的筛选,并利用其进行H2/CO2气体的生物转化,研究了p H对其乙酸和乙醇生成情况的影响。结果表明,所获得的同型产乙酸菌混培物组成为永达尔梭菌,纺缍形赖氨酸芽胞杆菌和蜡样芽胞杆菌等。该混培物最适p H为5-7。p H为7时混培物利用H2/CO2气体得到乙酸浓度可达到31.69 mmol/L。本研究获得了一种可利用H2/CO2合成乙酸的同型产乙酸菌混培物,为合成气生物转化的工业应用提供了有效的微生物资源。     

海洋产电菌Shewanella marisflavi EP1的脱色特性

以一株新筛选得到的海洋产电菌Shewanella marisflavi EP1作为实验材料,研究了该菌株关于偶氮、蒽醌、三苯基甲烷等染料的脱色能力及脱色机制。结果表明,该菌株对这些染料均具有较好的脱色能力,最高脱色容量达到925 mg染料/(g细胞干重.d)。EP1能利用葡萄糖、蔗糖、木糖、乳酸、甲酸、柠檬酸等多种碳源将单偶氮染料丽春红2R脱色。脱色的pH、温度和NaCl浓度范围分别是:pH 6-10、15°C-40°C、0-8%。最优脱色条件:乳酸,pH 8、35°C、1%-2%NaCl,10 h内脱色率高达99.95%。分光光谱结果表明,在0-8%NaCl浓度范围内EP1脱色机制为降解脱色。     

Domestication to crop improvement: genetic resources for Sorghum and Saccharum (Andropogoneae)

BACKGROUND: Both sorghum (Sorghum bicolor) and sugarcane (Saccharum officinarum) are members of the Andropogoneae tribe in the Poaceae and are each other's closest relatives amongst cultivated plants. Both are relatively recent domesticates and comparatively little of the genetic potential of these taxa and their wild relatives has been captured by breeding programmes to date. This review assesses the genetic gains made by plant breeders since domestication and the progress in the characterization of genetic resources and their utilization in crop improvement for these two related species. GENETIC RESOURCES: The genome of sorghum has recently been sequenced providing a great boost to our knowledge of the evolution of grass genomes and the wealth of diversity within S. bicolor taxa. Molecular analysis of the Sorghum genus has identified close relatives of S. bicolor with novel traits, endosperm structure and composition that may be used to expand the cultivated gene pool. Mutant populations (including TILLING populations) provide a useful addition to genetic resources for this species. Sugarcane is a complex polyploid with a large and variable number of copies of each gene. The wild relatives of sugarcane represent a reservoir of genetic diversity for use in sugarcane improvement. Techniques for quantitative molecular analysis of gene or allele copy number in this genetically complex crop have been developed. SNP discovery and mapping in sugarcane has been advanced by the development of high-throughput techniques for ecoTILLING in sugarcane. Genetic linkage maps of the sugarcane genome are being improved for use in breeding selection. The improvement of both sorghum and sugarcane will be accelerated by the incorporation of more diverse germplasm into the domesticated gene pools using molecular tools and the improved knowledge of these genomes.     

Domestication reduces the capacity to escape from predators

Phenotypic plasticity in response to variations in predatory pressure frequently occurs in wild populations, but it may be more evident and critical in species subjected to high exploitation rates and aquaculture. The Chilean scallop Argopecten purpuratus is becoming a domesticated species and the production of hatchery-reared scallops (closed environment), has implied the development of successive generations of individuals deprived of several stimuli normally present in their natural habitats (e.g. predators). We compared the escape capacities between wild and cultured A. purpuratus and also evaluated the effect of reproductive investment on the escape response capacities. Wild and cultured scallops, at different reproductive stages (maturing, mature and spawned), were stimulated to escape with the predatory sea star Meyenaster gelatinosus. We recorded: (1) the time to reaction, (2) the total number of claps, the duration of the clapping response and the clapping rate until exhaustion, (3) the time they spent closed after exhaustion, and (4) the proportion of claps recovered, the duration of the clapping response and the clapping rate after 20 min of recuperation. We found that wild A. purpuratus (1) reacted earlier when contacted by their natural predator, (2) escaped faster (greater clapping rates), (3) spent less time with their valves closed when exhausted, and (4) most of their escape capacities (i.e. claps number; clapping time; capacity of recuperation) were less affected by the energetic requirements imposed by gonad maturation and/or spawning than in cultured scallops. We considered that all these aspects of the escape response would make wild scallops less vulnerable to predation than cultured scallops, thus decreasing predation risk. Given the reduction of escape performance in cultured scallops, we suggest that this aspect should be considered for the success of culture-based restocking programs.     

Molecular Population Genetics of Rice Domestication

Domestication is a selection process that genetically modifies species to meet human needs. A most intriguing feature of domestication is the extreme phenotypic diversification among breeds. What could be the ultimate source of such genetic variations? Another notable outcome of artificial selection is the reduction in the fitness of domesticated species when they live in the wild without human assistance. The complete sequences of the two subspecies of rice cultivars provide an opportunity to address these questions. Between the two subspecies, we found much higher rates of non‐synonymous (N) than synonymous (S) substitutions and the N/S ratios are higher between cultivars than between wild species. Most interestingly, substitutions of highly dissimilar amino acids that are deleterious and uncommon between natural species are disproportionately common between the two subspecies of rice. We suggest strong selection in the absence of effective recombination may be the driving force, which we called the domestication‐associated Hill‐Robertson effect. These hitchhiking mutations may contribute to some fitness reduction in cultivars. Comparisons of the two genomes also reveal the existence of highly divergent regions in the genomes. Haplotypes in these regions often form highly polymorphic linkage blocks that are much older than speciation between wild species. Genes from such regions could contribute to the differences between indica and japonica and are likely to be involved in the diversifying selection under domestication. Their existence suggests that the amount of genetic variation within the single progenitor species Oryza rufipogon may be insufficient to account for the variation among rice cultivars, which may come from a more inclusive gene pool comprising most of the A‐genome wild species. Genes from the highly polymorphic regions also provide strong support for the independent domestication of the two subspecies. The genomic variation in rice has revealing implications for studying the genetic basis of indica‐japonica differentiation under rice domestication and subsequent improvement.     

Effect of Domestication on the Spread of the [PIN+] Prion in Saccharomyces cerevisiae

Prions (infectious proteins) cause fatal neurodegenerative diseases in mammals. In the yeast Saccharomyces cerevisiae, many toxic and lethal variants of the [PSI+] and [URE3] prions have been identified in laboratory strains, although some commonly studied variants do not seem to impair cell growth. Phylogenetic analysis has revealed four major clades of S. cerevisiae that share histories of two prion proteins and largely correspond to different ecological niches of yeast. The [PIN+] prion was most prevalent in commercialized niches, infrequent among wine/vineyard strains, and not observed in ancestral isolates. As previously reported, the [PSI+] and [URE3] prions are not found in any of these strains. Patterns of heterozygosity revealed genetic mosaicism and indicated extensive outcrossing among divergent strains in commercialized environments. In contrast, ancestral isolates were all homozygous and wine/vineyard strains were closely related to each other and largely homozygous. Cellular growth patterns were highly variable within and among clades, although ancestral isolates were the most efficient sporulators and domesticated strains showed greater tendencies for flocculation. [PIN+]-infected strains had a significantly higher likelihood of polyploidy, showed a higher propensity for flocculation compared to uninfected strains, and had higher sporulation efficiencies compared to domesticated, uninfected strains. Extensive phenotypic variability among strains from different environments suggests that S. cerevisiae is a niche generalist and that most wild strains are able to switch from asexual to sexual and from unicellular to multicellular growth in response to environmental conditions. Our data suggest that outbreeding and multicellular growth patterns adapted for domesticated environments are ecological risk factors for the [PIN+] prion in wild yeast.     

烟草化感自毒物质降解复合菌剂的优化及应用效果评价

烟草(Nicotianatabacum)长期连作导致土壤中烟草自身分泌的化感自毒物质的积累,加剧了烟草青枯病(tobacco bacterial wilt, TBW)的发生,严重威胁烟草的生产并造成了巨大的经济损失。【目的】获得对长期连作烟田青枯病具有显著防治效果的复合菌剂。【方法】利用筛选到的烟草化感自毒物质降解菌株构建复合菌剂,通过正交试验和单因素试验对菌种配比和助剂进行优化,对其在温室盆栽和连作烟田生产的应用效果进行评价。【结果】正交试验结果表明,复合菌剂中芽孢杆菌(Bacillus sp.) NO1、布鲁氏菌(Brucella sp.) NO8、芽孢杆菌(Bacillus sp.) NO9和NO10的最佳菌种配比为1:3:4:2;单因素试验结果表明最佳的载体为白炭黑;最佳润湿剂和分散剂分别为六偏磷酸钠和丁基萘磺酸钠,其最佳比例为1:1,最佳用量各为2%;稳定剂甘油的最佳浓度为1.0%。盆栽试验结果显示,复合菌剂对6种化感自毒物质的降解率和对青枯病的抑制率均达到78%以上。大田试验结果显示,100倍稀释的复合菌剂对连作15年烟田中的6种化感自毒物质具有显著的降解效果,并且能明显增...     

浙江省木本植物区系特征及其与引种驯化的关系

本文对浙江省木本植物区系特征进行分析,探讨该省木本植物区系与引种驯化的关系,旨在为园林工作者更好地开展引种驯化工作、切实提高引种成功率提供参考。     

Plant Domestication and Crop Evolution in the Near East: On Events and Processes

Reconstructing the evolutionary history of crop plants is fundamental for understanding their adaptation profile and the genetic basis of yield-limiting factors, which in turn are critical for future crop improvement. A major topic in this field is the recent claim for a millennia-long ‘protracted’ domestication process. Here we evaluate the evidence for the protracted domestication model in light of published archaeobotanical data, experimental evidence and the biology of the Near Eastern crops and their wild progenitors. The crux of our discussion is the differentiation between events or ‘domestication episodes’ and the later following crop evolutionary processes under domestication (frequently termed ‘crop improvement stage’), which are by definition, still ongoing. We argue that by assuming a protracted millennia-long domestication process, one needlessly opts to operate within an intellectual framework that does not allow differentiating between the decisive (critical) domestication traits and their respective loci, and those that have evolved later during the crop dissemination and improvement following the episodic domestication event. Therefore, in our view, apart from the lack of experimental evidence to support it, the protracted domestication assumption undermines the resolution power of the study of both plant domestication and crop evolution, from the cultural as well as from the biological perspectives.