强抗镉蜡状芽孢杆菌的分离鉴定及其抗性机理

从北京市远郊东三岔地区废弃的铅锌尾矿中筛选到1株强抗镉的细菌.通过细菌形态学观察、扫描电镜、X射线衍射能谱分析、甲基乙酰甲醇试验与酪氨酸水解试验等特征生理生化试验、菌株“G＋C mol%”值以及16S rDNA扩增与序列测定,鉴定此菌株为蜡状芽孢杆菌（Bacillus cereus）.分离菌株可以在镉浓度为1?000 mg/L的固体培养基平板上生长,表明菌株具有强抗镉的能力.进一步分析了菌株在添加Cd²⁺与未添加Cd²⁺的液体培养基中的生长曲线,并通过质粒消除试验证明该菌株的抗镉性质与抗性质粒的存在有关.     

利用玉米浸泡液制备苏云金杆菌生物杀虫剂

以玉米淀粉生产过程中的浸泡液作为原料培养基,在5L发酵罐中培养苏云金杆菌生物杀虫剂,并以常规黄豆粉培养基为对照,考察了苏云金杆菌在玉米浸泡液中的生长代谢状况(包括菌体形态、菌数增长与芽孢形成)以及48h发酵液的生物毒效.研究表明,无需添加其它成分及前处理,玉米浸泡液所含营养成分即可满足苏云金杆菌生长需求,其培养的总活菌数及芽孢数在27h可达最大值1.51 ×109CFU·mL-1和1.41×109CFU·mL-1,分别比常规培养基高出59%和85%,芽孢形成与晶体释放提前约9～12h;36h扫描电镜(SEM)观察表明,发酵36h浸泡液中大部分芽孢囊已经自溶,游离出卵圆形芽孢与菱形的晶体;而此时常规培养基正处于芽孢形成后期,只有极少数的游离晶体与芽孢;48h发酵终点的生物毒效结果显示,以浸泡液为培养基的苏云金杆菌发酵液毒效(891.51 IU·μL-1)比常规培养基高89%.本试验为浸泡液的再利用提供了一条崭新的途径,同时降低了杀虫剂的生产成本.     

温度两阶段控制策略发酵生产重组角质酶

为进一步提高重组Bacillus subtilis WSHB06-07发酵生产角质酶的产量和生产强度,在pH两阶段控制策略的基础上,考察了温度(27～40℃)对菌体生长和产酶的影响.研究发现,37℃适于菌体生长而30℃适于菌体产酶.通过分析发酵过程中菌体比生长速率及产物比合成速率的变化,确定了温度两阶段控制策略,即0～4 h时控制温度37℃,4 h后将温度调至30℃.通过采用这一优化策略,角质酶酶活和生产强度分别可达312.5 U/mL和13.02 kU L-1 h-1,相比恒定温度37℃控制模式下分别提高了83.4%和10.9%.图6表2参13     

农作物秸秆酶解与磷细菌肥的生产

以农作物秸秆为酶水解原料 ,用纤维素酶进行酶水解 ,水解液用于培养磷细菌肥生产菌 ,再用粉碎至一定粒度的作物秸秆对培养菌液进行吸附。实验结果表明 ,经酶解得到的水解液在添加一定的辅料后 ,可以作为培养磷细菌的料液。适宜条件下 ,菌量可达 5 1× 1 0 8/ml。     

一株芘的高效降解菌的选育及其降解性能研究

旨在为多环芳烃污染环境的生物修复提供微生物资源和科学依据,从某焦化厂曝气池的活性污泥中分离纯化出一株降解芘的优势菌株B-1,该菌株可在以芘为惟一碳源的培养基中生长繁殖,能利用芘的最高浓度为130 mg/L左右.经形态学观察、生理生化实验及l6S rDNA序列分析,初步判断菌株B-1为芽胞杆菌属.投菌量、芘初始浓度、pH...     

枯草芽孢杆菌对Cu2+的吸附及菌体表面基团分析

以枯草芽孢杆菌(Bacillus subtilis)为生物吸附剂,讨论了其对Cu2+的生物吸附规律,并通过酸碱滴定这一表面分析手段,结合相关软件及傅里叶变换红外光谱(FTIR)分析了菌体表面主要的基团种类及数量.结果表明,枯草芽孢杆菌对Cu2+吸附的最佳条件是:pH为6、吸附时间为24 h,菌悬液用量和Cu2+初始浓度...     

Evaluation of microbially enhanced composting of sophora flavescens residues

The effects of inoculants on the composting of Sophora flavescens residues were evaluated based on several physical, chemical and biological parameters, as well as the infrared spectra. Compared to the control compost without inoculants, the treatment compost with inoculants (Bacillus subtilis strain G-13 and Chaetomium thermophilum strain GF-1) had a significantly longer thermophilic duration, higher cellulase activity and a higher degradation rate of cellulose, hemicellulose and lignin (P < 0.05). Thus, a higher maturity degree of compost with apparently lower C:N ratio (15.88 vs. 17.77) and NH₄-N:NO₃-N ratio (0.16 vs. 0.20) was obtained with the inoculation comparing with the control (P < 0.05). Besides, the inoculants could markedly accelerate the composting process and increase the maturity degree of compost as indicated by the germination index (GI) in which the treatment reached the highest GI of 133.2% at day 15 while the control achieved the highest GI of 125.7% at day 30 of the composting. Inoculation with B. subtilis and C. thermophilum is a useful method to enhance the S. flavescens residues composting according to this study.     

表面活性剂对Bacillus pumilus strain Bap9 降解苯并[a]芘的影响

研究了非离子型表面活性剂Triton X-100(TX-100)和Tween80(TW-80)对苯并[a]芘的增溶特性及对苯并[a]芘高效降解菌Bacillus pumilus strain Bap9生长的影响,结果表明,2种表面活性剂对苯并[a]芘均有良好的增溶效果,均能作为碳源和能源被菌株Bap9所利用,TX-100增溶能力和增殖能力相对更强;不同浓度的TX-100对菌株降解苯并[a]芘的影响不同,当浓度为1 000 mg/L时,对降解的促进作用最强,可将苯并[a]芘降解率提高20.8%;在苯并[a]芘降解过程中,TX-100亦能作为碳源被菌株Bap9利用,不产生二次污染,因此可用于苯并[a]芘污染环境的生物修复。     

具有降解亚硝酸盐活性的解淀粉芽孢杆菌的分离与安全性分析

从养殖污泥中分离筛选了一株优良的亚硝酸盐降解菌YX01,经ARIS 2X细菌自动鉴定系统以及16SrRNA系统发育分析,该菌株被鉴定为解淀粉芽孢杆菌(Bacillus am yloliquefaciens,GenBank登录号为JX649949),其16S rRNA序列与基因库中 芽孢杆菌属菌株的16S rRNA序列有99％～100％的同源性,而且与解淀粉芽孢杆菌菌株LD5(GenBank登录号:GQ853414)的亲缘关系最近.该亚硝酸盐降解菌YX01在浓度为2.0×107～2.0×109cfu/L时对小球藻(Chlorella sp.)生长有促进作用;在浓度大于2.0×1011cfu/L时对小球藻生长具有显著抑制作用;亚硝酸盐降解菌YX01对小球藻的半数抑制浓度(IC50)大于2.0×1011cfu/L.亚硝酸盐降解菌YX01对大型蚤(Daphnia magna)的48h-半数致死浓度(LC50)大于2.0×1011cfu/L,对草鱼(Ctenopharyngodon idellus)的96h-LC50大于2.0×1011cfu/kg.经分析,亚硝酸盐降解菌YX01为无毒菌株.     

Effects of Mn(II) and Fe(II) on microbial removal of arsenic (III)

Goal, scope, and background  Arsenic contamination in groundwater creates severe health problems in the world. There are many physiochemical and biological methods available for remediation of arsenic from groundwater. Among them, microbial remediation could be taken as one of the least expensive methods, though it takes longer treatment time. The main objective of this research was to study the improvement on remediation by addition of some essential ion salts such as Mn and Fe. Materials and methods   Staphylococcus aureus, Bacillus subtilis, Klebsiella oxytoca, and Escherichia coli were taken as model microbes from Dhulikhel, 30 km east from Kathmandu, Nepal. Results and discussion  Microbes used in this study showed different abilities in their removal of As(III) with and without addition of Mn and Fe salts. The trend of remediation increased with time. S. aureus was found to be the best among the microbes used. It showed almost 100% removal after 48-h culture, both with and without Fe and Mn salts. Rate of removal of As increased with addition of Fe and Mn for all microbes. Removal efficiency was found to increase by about 32% on average after addition of salts in 24-h cultures of S. aureus.