Production and characterization of biosurfactant from Bacillus subtilis CCTCC AB93108

The production and properties of the biosurfactant synthesized by Bacillus subtilis CCTCC AB93108 were studied. The maximum concentration of the surfactant is 1.64 g/L when the bacteria grow in a medium supplemented with glucose as carbon sources. The isolated biosurfactant is a complex of protein and polysaccharide without lipids. It reduces the surface tension of distilled water to 45.9 mN/m, and its critical micelle concentration (CMC) is 2.96 g/L. It can stabilize emulsions of several aromatic and aliphatic hydrocarbons, such as benzene, xylene, n-pentane, n-nonane, gasoline and diesel oil. It presents high emulsification activity and stability in a wide range of temperature (4-100℃) and a long period of duration.     

Performance evaluation of an ANN–GA aided experimental modeling and optimization procedure for enhanced synthesis of marine biosurfactant in a stirred tank reactor

BACKGROUND: An improved resilient back‐propagation neural network modeling coupled with genetic algorithm aided optimization technique was employed for optimizing the process variables to maximize lipopeptide biosurfactant production by marine Bacillus circulans. RESULTS: An artificial neural network (ANN) was used to develop a non‐linear model based on a 2⁴ full factorial central composite design involving four independent parameters, agitation, aeration, temperature and pH with biosurfactant concentration as the process output. The polynomial model was optimized to maximize lipopeptide biosurfactants concentration using a genetic algorithm (GA). The ranges and levels of these critical process parameters were determined through single‐factor‐at‐a‐time experimental strategy. Improved ANN‐GA modeling and optimization were performed using MATLAB v.7.6 and the experimental design was obtained using Design Expert v.7.0. The ANN model was developed using the advanced neural network architecture called resilient back‐propagation algorithm. CONCLUSION: Process optimization for maximum production of marine microbial surfactant involving ANN‐GA aided experimental modeling and optimization was successfully carried out as the predicted optimal conditions were well validated by performing actual fermentation experiments. Approximately 52% enhancement in biosurfactant concentration was achieved using the above‐mentioned optimization strategy. © 2012 Society of Chemical Industry     

生物表面活性剂在日化行业的研究及应用进展

综述了生物表面活性剂在日化行业的研究进展和用于日化行业的生物表面活性剂新产品,探讨了生物表面活性剂在日化行业的应用优势及限制因素,指出了应对措施并对其在日化行业的应用前景进行了展望。     

Production of surface-active sophorolipid biosurfactant and crude oil degradability by novel Rhodotorula mucilaginosa strain SKF2

Biosurfactants are produced by important types of microorganisms such as bacteria, yeast, and filamentous fungi and have been used in a variety of industries. Among the 15 crude oil-degrading fungi, the two molds and one yeast were identified by 18S rDNA sequences as Mucor circinelloides strain SKMC, Fusarium fujikuroi strain DB2, and Rhodotorula mucilaginosa strain SKF2. These strains were isolated from crude oil–contaminated soil, diesel oil–contaminated soil, and activated sludge in the Oil Refinery Plant in Isfahan, Iran, respectively. The yeast strain was identified as a novel crude oil–degrading and biosurfactant-producing fungi in the presence of (1% v/v) Iranian light crude oil in the minimal salt medium (MSM). The highest amount of the dry weight of produced biosurfactant was measured at 6.2 g L⁻¹. Chemical nature of produced biosurfactant was determined as a surface-active sophorolipid biosurfactant compound by thin-layer chromatography, Fourier transform infra-red spectroscopy, and gas chromatography–mass spectrometry (GC–MS) analysis. The residual hydrocarbons in the MSM were analyzed by GC–MS, and it was shown that octadecane and docosane were eliminated by this novel strain completely.     

Bacillus sp.W112产生表面活性剂条件优化及其特性

从大庆油田油水混合样中分离得到一株芽孢杆菌(Bacillus sp. W112). 菌株发酵液具有较高的表面活性,而且其表面活性剂具有较好的温度、pH和盐稳定性. 对表面活性剂产生条件进行优化,确定了最佳碳源为30 g/L麦芽糖,最佳氮源为1.5 g/L的混合氮源[硫酸铵+硝酸钠(1:2, j)],培养温度为37℃,在500 mL三角瓶中的装液量为100 mL,pH值为7.0,接种量为10%(j). 通过盐酸沉淀-化学试剂萃取法提取得到浅黄色固体产物,通过红外光谱分析,初步确定为一种脂肽类表面活性剂.     

大港孔店油田本源微生物代谢产物监测分析

应用放射性同位素示踪剂技术研究了大港孔店北二断块水动力学关系,结果表明该区块注水井和采油井之间具有紧密的水动力学连通关系。在本源微生物驱油试验阶段,对试验区微生物及其代谢物在地层中的分布状况进行了3年连续监测,表明本源菌激活期间菌数增加102~105倍,原油部分氧化,使得低分子脂肪酸(乙酸盐,甲酸盐,丁酸盐等)含量约增加10~100倍,碳酸氢盐从0·4~0·6g/L增加到0·7~1·8g/L,产生的生物表面活性剂使地层水平均表面张力降低至48~33·3mN/m,地层水相对石蜡平均界面张力降至25~13·7mN/m,产生的生物多糖代谢物使地层水平均粘度增至0·76mPa·s,最高达0·83mPa·s。这些变化改变了油层物理化学和生态环境,改善了原油流动性,尤其是水动力学连通关系最好的井地层水组成的改变和增油降水效果最为明显。试验区监测结果表明,微生物及代谢物随注入水主流动方向运移,生物表面活性剂和低分子脂肪酸及生物聚合物的作用是提高原油采收率的主要机理。     

中间苍白杆菌对含蜡原油除蜡降粘分析

蜡质不仅使含蜡原油黏度升高，而且会析出积聚在管壁上降低管输效率。从原油污染淤泥中分离出一株产表面活性剂的烃降解菌F-1，经16S rDNA鉴定为中间苍白杆菌。与原油作用7 d 后，能将蜡含蜡量为15.2%的高含蜡原油处理为蜡含蜡量为9.1%的含蜡原油，原油蜡质量分数降低40.1%，原油黏度降低21%以上，细胞疏水性达28.1%。通过傅里叶红外光谱鉴定该菌产生的生物表面活性剂为脂肽类。添加该菌上清液到液体石蜡 可形成91.49 mm的排油圈，能够显著降低培养基表面张力，对液体石蜡乳化系数达到65%。     

生物表面活性剂驱油性能研究

为探讨生物表面活性剂菌种采油性能及矿场应用潜力,在吉林油区广泛取样,采用特定培养基对菌种进行筛选,在建立生物表面活性剂检测方法的基础上,对菌种生长代谢及发酵环境条件进行了分析。采用色谱法对菌种作用原油后组分变化进行了定性分析,在室内物模驱油效率试验的基础上,进行了矿场清防蜡应用试验。原油经生物表面活性剂菌作用后,油水界面张力降低到10～mN／m,原油黏度下降50％;室内物模驱油效率试验提高采收率10％以上,矿场清防蜡有效率〉65％,单井平均增油73．5t;在微生物强化水驱、油井清防蜡及近井解堵等MEOR工艺方面具有良好的应用前景。     

采油菌B36的室内研究

从胜利油田油水样中分离出一珠细菌B36 ,该菌耐温耐盐性良好 ,能以烃类作为唯一的碳源。该菌 5 0℃时在含有混合石蜡 (>C16原油馏分 )及其他营养物的培养基中摇床培养 12h后 ,培养液中菌数高达 7× 10 5个 /mL ,培养液表面张力由 6 1mN/m降至 32mN/m ,pH值由 7.0降至 5 .4。由培养 36h的上述培养液中分离出黄色粉末状表面活性物质 ,其产量为 0 .6 5 g/L ,经鉴定为脂肽。该菌分别与原油和混合石蜡在不含混合石蜡的培养液中培养 6d后 ,含水原油 5 0℃粘度由 6 5 .6mPa·s降至 15 .3mPa·s,6 0℃界面张力由 30 .6mN/m降至 1.2mN/m ,无水原油凝固点由 4 4℃降至 36℃ ,初馏点下降 ,终馏点升高 ,可馏出物 (轻组分 )由 4 5 .1%增至 5 7.8% ;混合石蜡 2d降解率为2 .1% ,6d降解率达 2 5 .8%。B36是一种有应用前景的采油微生物