Molecular characterization of biosurfactant producing Bacillus cereus strain DRDU1 for its potential application in bioremediation and further EOR studies

Abstract

Environmental pollution by crude oil during petroleum exploration is a global issue of concern. It largely alters the physicochemical property of soil and water which makes them toxic for crops and aquatic organisms to survive. Bacillus cereus strain DRDU1 (Genbank accession no. KF273330.1) is an endospore forming potential hydrocarbon degrader which was isolated from an automobile engine. The isolate could achieve up to 96 and 84% kerosene and crude oil degradation with respective cfu of (6.3?±?2.31)?×?10⁹ and (13.67?±?2.52)?×?10⁸ cells/mL. On the other hand it also showed its potential to degrade 74 and 67% of kerosene and crude oil in nitrate (N) and phosphate (P) deficient media with corresponding cfu (10?±?1.73)?×?10⁸ and (6?±?2.65)?×?10⁶ cells/mL. This indicates its potential to survive under nutrient stress condition. The strain was reported to be capable of producing biosurfactant which may play role in petroleum biodegradation and may be a potential tool for Microbial Enhanced Oil Recovery (MEOR) studies in future. Herein the presence of sfp gene in the isolate was confirmed which may be responsible for its ability to synthesize biosurfactant for hydrocarbon degradation and also for its stress tolerant potential. It was further characterized and the hypothetical protein sequence encoded by this gene is also proposed.     

油田含油污泥土壤降解与修复试验研究

利用分子生物学手段,分离优选油田污泥、污水中的菌株,确定菌株处理油田污泥的潜力。筛选评价了不同生物活化剂,改善原始污泥的生物降解环境。利用研发的菌株及生物活化剂,开展了生物降解及修复试验,考察了污泥除油率变化。结果表明,w(含油)≤20%(干基)的油田污泥,经20～30天降解后,污泥除油率81.46%,再经1～2个生长周期的植物修复,污泥中w(含油)1.56%(干基),满足油田行业标准控制指标的要求。     

MEtreePOLIS 1901-2111

As the natural world continues to change, it is clear that people would rather employ technology to adapt to shifting circumstances rather than alter their lifestyles to suit nature's demands. MEtreePolis is a timeline of crucial historical developments that explores the dichotomy of nature and technology. Commencing in 1901, it shoots past the present and into the future, closing in 2111. By providing an imaginative vision of tomorrow, Matthias Hollwich and Marc Kushner provide an entertaining argument for human manipulation of the environment, suggesting that it will inadvertently trigger ‘ecological salvation’ and ‘social utopia’. Copyright © 2010 John Wiley & Sons, Ltd.     

微生物降解石油烃研究进展

石油烃对环境产生的污染是目前全球普遍关注的焦点问题,生物修复是治理石油烃污染的最为有效的途径之一。探讨了石油烃降解菌的分类、细菌对烃的黏附性以及基因工程菌的开发,讨论了微生物降解石油烃的影响因素和新的技术方法,并进行了展望。     

固定化生物吸附剂对Cd(Ⅱ)的去除性能及机理

从处理含Cd(Ⅱ)废水的人工湿地基质层中提取微生物,经过重金属浓度梯度筛选后,通过聚合酶链式反应（PCR）技术分析发现筛选后的菌群对Cd(Ⅱ)有较好的耐受性和吸附能力,菌种丰度依次为Lactococcus< Stenotrophomonas< Serratia< Pseudomona。将筛选后的微生物用包埋固定化技术制成固定化生物吸附剂,在pH=4~5、吸附时间48h、吸附剂用量（湿重）50g/L、Cd(Ⅱ)初始浓度100mg/L时,对Cd(Ⅱ)的最大去除率可达91%±2%。通过吸附平衡研究发现吸附过程符合准一级动力学模型和Langmuir模型,对Cd(Ⅱ)的最大单分子层吸附量为34.4mg/g。BET分析结果显示,固定化生物吸附剂具有介孔结构且比表面积大,有利于吸附作用的进行;傅里叶变换衰减全反射红外光谱法（FTIR-ATR）分析结果说明固定化生物吸附剂具有丰富的重金属结合点 位,—COOH、—OH、—NH和—CH基团参与了Cd(Ⅱ)的吸附过程。固定化生物吸附剂重复使用3次能保持较好的吸附效果,显示出较高的经济实用性。水环境中常见阳离子对Cd(Ⅱ)竞争吸附影响顺序依次为Na⁺+2+。     

利用响应面法对L-2菌株降解石油烃进行优化

从石油烃污染土壤中分离得到菌株L-2,对石油烃（TPH）的降解进行研究。通过16S rRNA鉴定L-2为肠杆菌属。采用基于Box-Behnken设计（BBD）的响应面方法（RSM）,考察温度、pH和TPH质量浓度3个自变量对TPH降解率的交互效应,建立二次回归方程预测模型,确定3个实验因素的最佳组合,通过方差分析验证该二次模型的有效性。确定系数R²=0.9943,表明二次模型与实验数据吻合较好。响应面优化得到最佳降解条件：温度为30℃,pH为7.13和TPH质量浓度为3.93g/L,TPH降解率为87.79%。结果表明,温度对TPH降解速率的影响（P<0.0001）较其他两个参数更显著。GC/MS结果表明菌株L-2可降解十六烷(C₁₆)至二十五烷(C₂₅)范围内的TPH组分。     

Remediation of Oil Contaminated Media Using Organic Material Supplementation

With the fact that anthropogenic activities are inevitable, especially with the continuous use of fossil fuels and other sources of hydrocarbons, environmental pollution appears to be a recurring issue. However, nascent science and technologies try to identify and apply varied options that can remedy polluted sites, which include oil spill situations. The present review elucidates the remediation options on the event of oil spill/contamination with emphasis on the adoption of biological treatment (supplement addition and phytoremediation), and overview on the potential relevance of remediation via advances in nanotechnology. The associated negativities and cost tend to outweigh the advantages of both methods when sustainability is considered.     

Utilisation of C2–C4 gaseous hydrocarbons and isoprene by microorganisms

Microorganisms able to grow on low molecular weight aliphatic hydrocarbon gases, i.e. the n‐alkanes, ethane, propane and butane, and the terminal alkenes, ethylene, propylene and butylene, are not uncommon but mainly belong to certain taxonomic groups. These microbes are described in this review together with the pathways by which the hydrocarbons are assimilated. Microbial oxidation of the volatile alkadiene, isoprene, is also discussed. Avenues for possible commercial exploitation of these metabolic activities are also reviewed. Short‐chain n‐alkane‐utilising organisms have been investigated as tools in petroleum exploration and for production of single cell protein. More recently microbes grown on gaseous hydrocarbons other than methane have been evaluated for use in biotechnological production of epoxides, synthesis of chiral epoxyalkanes and as catalysts in bioremediation systems. Copyright © 2005 Society of Chemical Industry     

Bioprocesses for air pollution control

Bioprocesses have been developed as relatively recent alternatives to conventional, non‐biological technologies, for waste gas treatment and air pollution control in general. This paper reviews major biodegradation processes relevant in this field as well as both accepted and major innovative bioreactor configurations studied or used nowadays for the treatment of polluted air, i.e. biofilters, one‐ and two‐liquid phase biotrickling filters, bioscrubbers, membrane bioreactors, rotating biodiscs and biodrums, one‐ and two‐liquid phase suspended growth bioreactors, as well as hybrid reactor configurations. Some of these bioreactors are being used at full‐scale for solving air pollution problems, while others are still at the research and development stage at laboratory‐ or pilot‐scale. Copyright © 2009 Society of Chemical Industry     

Isolation and Characteristics of a Microbial Consortium for Effectively Degrading Phenanthrene

A microbial consortium (named W4) capable of aerobic biodegradation of solid phenanthrene as the sole source of carbon and energy was isolated by selective enrichment from petroleum-contaminated soil in the Henan oilfield, China. The strains of the consortium were identified as Sphingomonas cloacae, Rhizobium sp., Pseudomonas aeruginosa and Achromobacter xylosoxidans respectively by means of genetic methods. The major metabolites of phenanthrene were analyzed by gas chromatography-mass spectrometry (GC-MS). The biodegradation percentage of solid phenanthrene at 200 mg/L in liquid medium after 7 days of growth was greater than 99%. The degradation of phenanthrene was compared between individual predominant strains and the microbial consortium in different treatment processes. The microbial consortium showed a significant improvement of phenanthrene degradation rates in either static or shaking culture. The degradation percentage of phenanthrene by the consortium W4 decreased to some degree when C16 coexisted, however it was hardly affected by C30. Furthermore, the ability of consortium W4 to remediate oil sludge from the Dagang oil refinery was studied by composting; and it was found that the consortium W4 could obviously remove polycyclic aromatic hydrocarbons (PAHs) and paraffinic hydrocarbons. All the results indicated that the microbial consortium W4 had a promising application in bioremediation of oil-contaminated environments and could be potentially used in microbial enhanced oil recovery (MEOR).