酸性半纤维素降解细菌的筛选与鉴定

从南方酸性水稻土和腐烂秸秆中采集样品,经初筛、复筛获得4株产生明显水解圈且D/d值较大同时传代效果稳定的酸性半纤维素降解细菌。DNS法测定4株细菌半纤维素酶活力,最终结合其产酶速度及酶活大小得到菌株NB8,液体摇瓶发酵72 h其半纤维素酶活达85.12 U/mL。经形态学观察和生理生化指标测定,初步确定该菌为芽胞杆菌属。结合16S rDNA基因序列分析结果,可以初步鉴定NB8为短小芽胞杆菌(Ba-cillus pumilus)。     

盐池采油区污染土壤石油降解菌的筛选鉴定及其降解特性

从宁夏盐池原油污染土壤中分离筛选高效石油降解菌,研究菌株的降解特性及其对污染土壤的修复效果,以期为该地区石油污染土壤的微生物修复提供高效菌源和理论依据.通过富集培养和分离纯化的方法筛选石油降解菌,结合菌株生理生化特征和16S rRNA基因序列对其进行鉴定;根据菌株产表面活性剂的能力和原油降解率,筛选2株高效菌株制备单一...     

一株高效四环素降解菌的分离鉴定及其降解性能研究

四环素类抗生素在畜牧养殖业中广泛使用,但其结构复杂,难降解,容易在水环境中积蓄,进而对生态环境产生深远影响,许多国家已将抗生素污染列为重要的环境问题展开了相关的基础研究。近年来利用微生物降解环境中的抗生素污染物成为研究热点。采用选择性培养基,从某制药厂排污口的水样中分离筛选到1株具有较高降解四环素能力的菌株4002,经形态观察、生理生化测定和16S r DNA序列分析,将该菌初步鉴定为Advenella sp.。从p H、溶氧量、无机盐等方面对菌株降解四环素的性能进行研究。结果表明,该菌株降解四环素的适宜p H为7.0,在有氧条件下,30℃,150 r/min振荡培养6 d,可使初始浓度为50μg/m L四环素降解率达57.8%。无机盐对降解率有显著影响,添加Fe SO4和Mn SO4对四环素降解有促进作用,Mg SO4影响不大,Ca SO4则有抑制作用。在培养至第8天时,培养液经HPLC检测显示6.022 min处出现新的吸收峰,推测为降解产物。     

敌敌畏降解菌的分离鉴定及降解特性研究

目的:从受有机磷农药污染的土壤中分离能降解DDVP的菌株,对其进行鉴定和降解特性研究.方法:采用DDVP为惟一碳源和能源的无机盐培养基,通过富集培养、平板划线分离得到一株优势菌,编号为DDW-1,采用形态学、生理生化和16S-rDNA序列分析对其进行鉴定,采用气相色谱测定菌株DDW-1对DDVP的降解能力,并进行底物广谱性测试和降解酶定位实验.结果:该菌株鉴定为甲基杆菌属(Methylobacterium sp.).降解特性试验结果表明,其最佳生长条件为温度28℃,初始pH为7.0,在该条件下,500mg·L-> DDVP经过DDW-1菌株代谢3d后,降解率达63.7%.结论:菌株DDW-1能降解DDVP,该菌株产胞内酶.     

透明圈法快速筛选半纤维素分解菌

半纤维素是植物性材料的重要组成成分之一 ,占 1 5 - 30 %,是陆生植物细胞壁的一种主要组分 ,较集中于初级和次级细胞壁中。半纤维素是由己糖和戊糖组成的异质多糖[1] 。微生物产生的半纤维素酶可降解半纤维素生成木糖及其它少量单糖 ,研究半纤维素生物转化具有重要意义 ,如在生物制浆 ,转化半纤维素为单糖、酒精 ,处理造纸厂废水的环境污染等方面具有广阔的应用前景 ,国外已有不少的研究者对降解半纤维素的真菌和细菌进行了研究[2 ] 。近年来 ,国内陆续出现了 7篇有关降解半纤维素真菌的研究报道 ,降解半纤维素细菌的报道只有 1篇[3 ] ,从…     

高效原油污染降解菌的筛选、鉴定及菌群的构建

为获得高效原油降解菌株,从山东某油田的含油污泥中和实验室自有菌剂以及原油污染的土壤中分离筛选得到9株微生物,分别编号SF1、SF2、SF3、SF4、SF5、SF6、SF7、SF8和SF9.研究表明,9株菌对原油均有一定的降解能力.通过16S rRNA鉴定表明:SF1为中间苍白杆菌属(Ochrobactrum inter...     

秸秆降解菌的筛选及对秸秆的降解效果

作物秸秆作处置不当可能严重影响农村生态环境。目前东北地区的秸秆处置方式主要为直接打碎还田,但秸秆在自然环境中不易腐化,影响春耕。从添加外源微生物促进秸秆原位腐化角度开发新型可培养秸秆降解菌,具有重要意义。本实验通过菌种富集培养、刚果红培养基初筛和滤纸条崩解试验复筛的方法,从腐烂的秸秆和牛肠道中分离筛选潜在的高效纤维素降解菌,测定其最适生长温度和pH,在液态发酵培养条件下考察菌株实际降解能力,共获得具有较高玉米秸秆降解能力的降解菌5株。5种菌株的生长峰值均出现在温度20～30℃,pH值7.5～8.5范围内。液态发酵培养15天后,秸秆失重率为菌株NX9(53.88%)>NF6(51.36%)>JF3(46.97%)>JZ8(45.2%)>JX4(35.79%)>CK(23.88%)。其中,菌株NX9(温度30℃、pH 7.5)对秸秆半纤维素和木质素的降解能力最强,15天降解率分别为48%和37.7%;筛选出的NF6和JF3属于耐冷微生物,特别是菌株NF6在4℃条件下也能生长繁殖,为北方开展"外源微生物促进秸秆原位腐化"技术提供了基础。     

高效石油降解菌的筛选及其降解性能研究

从长期被石油污染的土壤中驯化筛选、分离出2株高效石油降解菌Y-7和Y-9,通过形态学特征的观察和生理生化试验对其进行初步鉴定,鉴定结果分别为假单胞菌属(Pseudomonas sp.)和芽孢杆菌属(Bacillus sp.)。同时,研究并分析了不同pH、温度、初始石油浓度、接种量、吐温80等条件对菌体生长和石油降解率的影响。结果表明,在试验条件下,2株优势菌在初始pH为7左右,对石油的降解率可分别高达68.7%,74.5%,偏酸或偏碱的环境均不利于菌体的生长;培养温度对2株菌体生长和石油降解率的影响较大,最佳温度为35℃,降解率达到最大,分别为73.1%和69.6%;石油初始浓度大于0.4g/L时,Y-7降油率从69%降到49%,Y-9基本变化不大,控制石油物质浓度在0.4g/L,有利于对石油的生物处理;最佳接种量为2mL/L;吐温80对石油的降解促进作用有待进一步分析与研究。     

发酵床中纤维素降解菌的分离与鉴定

从发酵床垫料中初步分离出43株纤维素降解菌。采用刚果红鉴别培养基及滤纸条培养基初筛,得到5株透明圈较大且使滤纸条产生崩解的菌株,通过进一步液体发酵,测定其CMC酶活、FPA酶活和天然纤维素酶活,获得2株具有较高纤维素降解活性菌株,并分别命名为F7和F21。经16S rRNA基因序列分子生物学鉴定和系统发育分析表明,这2株纤维素降解菌分别归属为枯草芽孢杆菌(Bacillus subtilis)和链霉菌(Streptomyces sp.)。     

酸性土壤中耐铝细菌的筛选鉴定及其耐铝能力分析

以含有1mmol／LAl3＋的s—LB培养基作为筛选培养基,从酸性土壤中分离到13株耐铝的细菌菌株,选取其中6株进行形态学分析,结果观察到这些菌株的菌体均呈杆状,其中1株为革兰阳性反应,其余5株为革兰阴性反应。以细菌通用引物扩增这些菌株的16SrDNA并测序,将得到的序列与GenBank中的序列进行BLAST比对,利用MEGA4．0软件,按照Neighbor-joining法构建系统进化树,这6个菌株分别与Enterobacter endosymbiont,Serratia marcescens ,Pantoea agglomerans ,Enterobacter aerogenes .Bacillus subtilis 和 Enterobacter asburiae的亲缘关系最近。将这些菌株接种到加有2mmol／LAl3＋、pH4．5的s—LB固体培养基上培养时,它们都能生长,说明这些菌株具有较好的耐铝能力,这些菌株为进一步研究细菌的耐铝机制提供了极好的材料。     

Screening for cellulose and hemicellulose degrading enzymes from the fungal genus Ulocladium

The fungal genus Ulocladium consists mostly of saprotrophic species and can readily be isolated from dead vegetation, rotten wood, paper, textiles and other cellulose containing materials. Thus, they must produce cellulolytic and hemicellulolytic enzymes. In this study fifty Ulocladium strains from ten different species were tested for enzyme activities on 14 different azurine-cross-linked (AZCL) substrates and analyzed by multivariate analysis. The tested strains of Ulocladium were found to produce a broad enzyme profile. Most species in Ulocladium were able to produced high amounts of enzymes that degraded amylose, arabinoxylan, β-glucan, cellulose and xylan; however, variations between species as well as between individual strains in each species were seen. Overall, the enzyme profiles were found to be species specific, but also source of isolation impacted the enzymes produced. The results suggest that species identity as well as isolation source must be considered when screening microorganisms for enzymes.     

正己醇降解菌的分离、筛选及分类鉴定

为获得可降解正己醇的真菌菌种,分别以苹果园土壤、苹果渣、苹果酒醪和醋醅为分离源,采用富集培养和紫外线定向诱变,得到了两株能在pH3.8-4.0的条件下降解正己醇的真菌菌株TF和TM。菌株TM和TF在马铃薯葡萄糖培养液中对4.0mg/mL正己醇的降解率分别为45.60±5.43%和23.82±9.27%,与对照在α=0.01水平上差异显著。结合形态学特征及26S rDNA D1/D2区(菌株TM)和ITS区(菌株TF)序列分析,对两株菌进行了分类鉴定。结果表明:菌株TM属于地霉属Geotrichum,菌株TF为白地霉Geotrichum candidum(有性型Galactomyces geotrichum)。     

聚乳酸降解菌株筛选鉴定及降解过程优化

【目的】筛选能够降解聚乳酸的微生物, 提高聚乳酸的降解速率并鉴定聚乳酸降解酶种类。【方法】以明胶为唯一碳源, 筛选能够降解聚乳酸的微生物; 通过优化明胶添加浓度、聚乳酸添加量以及金属离子种类提高聚乳酸的降解速率; 通过分析降解过程中代谢产物和酶活力变化明确聚乳酸降解酶类别。【结果】筛选获得一株聚乳酸降解菌株, 鉴定为Lentzea waywayandensis; 经优化培养, 聚乳酸在25 d后失重84.8%; 降解过程中, 检测到乳酸的产生, 体外酶活实验仅检测到蛋白酶活力。【结论】明胶作为唯一碳源适用于聚乳酸降解菌株的筛选; 明胶作为碳源的同时可以作为诱导剂诱导菌株L. waywayandensis降解聚乳酸; 此外, 研究表明蛋白酶在聚乳酸降解过程中发挥重要作用。     

Distribution of tannic acid degrading microorganisms in the soil and comparative study of tannase from two fungal strains

A quantitative survey on microbial population including tannase producing organisms have been made from different soil samples. Most of the samples harbour negligible number of tannase producers in comparison to total microbial flora. Among the tannase producers, fungal members are more frequent than bacteria. Tannase production and tannic acid degradation have been studied in two newly isolated potent fungal strains. Both the strains produce maximum tannase at their stationary phases of growth. Enzymes produced by both the strains remain active within pH 3.5-6.0 and temperature 30-60 degrees C.     

Dynamics of microbial populations in soil: Indigenous microorganisms degrading 2,4-dinitrophenol

The mineralization of 2,4-dinitrophenol (DNP) and changes in the DNP-mineralizing population over a wide range of DNP concentrations were monitored to evaluate the dynamics of the DNP-mineralizing populations in two soils (soils 1 and 2). Curves of CO₂ evolution were analyzed using nonlinear regression analysis and models incorporating parameters for population size and growth rate. The results of these analyses were compared to independent estimates of the DNP-mineralizing population from most-probable-number (MPN) determinations. The combined results of these analyses showed that 0.1g of DNP g^–1 of soil was too low a concentration to support maintenance or growth of the DNP-mineralizing population, whereas all higher concentrations supported either maintenance or growth of the population in soil 1. Independent estimates of population size showed good agreement between the nonlinear regression and MPN techniques, especially at initial DNP concentrations below 100g g^–1. Estimates of both population size and maximum specific growth rate varied with concentration, possibly indicating the existence of two different DNP-mineralizing populations in soil 1. In the other soil tested (soil 2), the population of DNP-mineralizers was much lower than in the first soil, and no evidence of two populations was obtained. In soil 2, good agreement between the nonlinear regression and MPN estimates of population size was also obtained. Results of this study demonstrate the power of using testable models of population dynamics to obtain useful estimates of parameters of microbial growth and survival in soil.     

Selection of vinasse degrading microorganisms

Vinasse is a highly colored effluent with a high pollutant potential when disposed in the environment. Assays for decolorization of vinasse were performed, selecting the fungus Pleurotus sajor-caju CCB 020. The discoloration was cocominant with the increase of the activities of laccase, manganese-peroxidase and peroxidases. P. sajor-caju demonstrated a rise in biomass production (1.06 g 100 ml⁻¹), and the enzyme activities such as laccase (varying from 400 to 450 IU l⁻¹) reached between the 9th and 10th day of growth and for MnP at the 12th day of cultivation (varying from 60 to 100 IU l⁻¹). It was concluded that the system P. sajor-caju/vinasse can be utilized as a bioprocess for color removal and degradation of complex vinasse compounds. It was observed an improvement in the characteristics and detoxification allowing its utilization as reused water, laccase and manganese-peroxidase enzymes production and for fungal biomass production with a high nutritional value.     

Screening for novel lipolytic enzymes from uncultured soil microorganisms

The construction and screening of metagenomic libraries constitute a valuable resource for obtaining novel biocatalysts. In this work, we present the construction of a metagenomic library in Escherichia coli using fosmid and microbial DNA directly isolated from forest topsoil and screened for lipolytic enzymes. The library consisted of 33,700 clones with an average DNA insert size of 35 kb. Eight unique lipolytic active clones were obtained from the metagenomic library on the basis of tributyrin hydrolysis. Subsequently, secondary libraries in a high-copy-number plasmid were generated to select lipolytic subclones and to characterize the individual genes responsible for the lipolytic activity. DNA sequence analysis of six genes revealed that the enzymes encoded by the metagenomic genes for lipolytic activity were novel with 34–48% similarity to known enzymes. They had conserved sequences similar to those in the hormone-sensitive lipase family. Based on their deduced amino acid similarity, the six genes encoding lipolytic enzymes were further divided into three subgroups, the identities among which ranged from 33% to 45%. The six predicted gene products were successfully expressed in E. coli and secreted into the culture broth. Most of the secreted enzymes showed a catalytic activity for hydrolysis of p-nitrophenyl butyrate (C₄) but not p-nitrophenyl palmitate (C₁₆).     

一株十溴联苯醚高效好氧降解菌的筛选、鉴定及降解特性

【目的】从广东贵屿镇电子垃圾拆解地采集的沉积物样品中分离十溴联苯醚(BDE-209)高效好氧降解菌,并考察其对BDE-209的降解特性。【方法】通过生理生化实验和16S rRNA测序鉴定菌种,正交实验优化降解条件,并分析不同降解体系及影响因素对菌降解BDE-209的影响。【结果】鉴定结果显示,该BDE-209好氧降解菌为短短芽孢杆菌(Brevibacillus brevis)。B.brevis对1 mg/L BDE-209 5 d的降解率可达54.38%。正交实验结果表明,B.brevis降解BDE-209的最优条件为:pH 7,投菌量3 g/L,温度30°C。降解特性研究结果显示B.brevis对BDE-209降解的最佳菌龄为36 h,最佳氮源为(NH4)2SO4,B.brevis对Cu2+、Cd2+有较好的耐受性,但Cu2+和Cd2+的存在会影响其对BDE-209的降解。当Cu2+浓度在1 5 mg/L,Cd2+浓度在0.3 0.5 mg/L范围内时,B.brevis对BDE-209降解均可达50%以上。【结论】B.brevis对BDE-209有很好的降解效率,研究结果对BDE-209的好氧微生物降解及环境中BDE-209的生物修复具有较好的科学意义和应用价值。     

Biodegradation of polyhydroxyalkanoates by soil microbial communities of different structures and detection of PHA degrading microorganisms

Biodegradation of microbial linear polymers of hydroxyalkanoic acids (polyhydroxyalkanoates, PHAs) by soil microbial communities of different structures has been studied during two field seasons in different weather conditions. This process was shown to be influenced by the polymer chemical composition, temperature, humidity, and the microbial soil component. The PHA degradation was accompanied by a decrease in the polymer molecular weight and an increase in the degree of crystallinity, indicating the preferential destruction of the amorphous phase compared to the crystalline one. The quantity of the true PHA destructors developing at the surface of the polymer samples was lower than the quantity of accompanying bacteria. The dominant PHA degrading microorganisms under the test conditions were identified as bacteria of the genera Variovorax, Stenotrophomonas, Acinetobacter, Pseudomonas, Bacillus, and Xanthomonas and as micromycetes from Penicillium, Paecilomyces, Acremonium, Verticillium, and Zygosporium.