Biodegradation of crude oil by Pseudomonas aeruginosa in the presence of rhamnolipids

INTRODUCTION Oily wastewater, especially from oil field, hasposed a great hazard for terrestrial and marine eco-systems. The traditional treatment of oily wastewater,such as containment and collection using floatingbooms, adsorption by natural or synthetic materials,etc., can not degrade the crude oil thoroughly (Ollis,1992). So far, biodegradation suggests an effectivemethod. During biodegradation, crude oil is used asan organic carbon source by a microbial process,resulting in the brea…     

Biodegradation of crude oil by Pseudomonas aeruginosa in the presence of rhamnolipids

The potential biodegradation of crude oil was assessed based on the development of a fermentative process with a strain ofPseudomonas aeruginosa which produced 15.4 g/L rhamnolipids when cultured in a basal mineral medium using glycerol as a sole carbon source. However, neither cell growth nor rhamnolipid production was observed in the comparative culture system using crude oil as the sole carbon source instead. As rhamnolipid, an effective biosurfactant, has been reported to stimulate the biodegradation of hydrocarbons, 1 g/L glycerol or 0.22 g/L rhamnolipid was initially added into the medium to facilitate the biodegradation of crude oil. In both situations, more than 58% of crude oil was degraded and further converted into accumulated cell biomass and rhamnolipids. These results suggest thatPseudomonas aeruginosa could degrade most of crude oil with direct or indirect addition of rhamnolipid. And this conclusion was further supported by another adsorption experiment, where the adsorption capacity of crude oil by killed cell biomass was negligible in comparison with the biologic activities of live cell biomass. Project supported by Science Foundation from China Petroleum and Chemical Corporation, China     

高产柠檬酸突变菌株以玉米粉为原料的生物反应器扩大生产研究

研究目的：研究高产黑曲霉突变菌株以玉米粉为原料的生物反应器扩大发酵,以期获得适合于工业化生产柠檬酸的发酵工艺。 创新要点：以玉米粉为原料,系统地研究了筛选得到的高产菌株在50L生物反应器中不同糖浓度发酵生产柠檬酸的特性,最终优化出适合于工业化生产柠檬酸的发酵工艺。 研究方法：（1）利用淀粉酶对粉碎后的玉米进行液化,然后过滤,最终得上清液;（2）以50L生物反应器作为发酵设备,对筛选得到的高产柠檬酸菌株进行扩大培养;（3）通过测定不同培养时期中积累的柠檬酸含量和剩余的残总糖,最终优化出高效率生产柠檬酸的发酵工艺。 重要结论：以不同糖浓度的液化玉米粉上清液作为碳源,突变菌株H4002能积累177．7--196．0g,L的柠檬酸,效率能达到2．96～3．27g/（L·h）,尤其当糖浓度为210g／L,H4002菌株表现出最佳的柠檬酸生产水平,如柠檬酸积累187．5g/L,生产效率达3．13g／（L·h）。上述结果说明了突变菌株H4002拥有快速生产柠檬酸的能力。     

Biotreatment of oily wastewater by rhamnolipids in aerated active sludge system

Oily wastewater generated by various industries creates a major ecological problem throughout the world. The tra-ditional methods for the oily wastewater treatment are inefficient and costly. Surfactants can promote the biodegradation of pe-troleum hydrocarbons by dispersing oil into aqueous environment. In the present study, we applied rhamnolipid-containing cell-free culture broth to enhance the biodegradation of crude oil and lubricating oil in a conventional aerobically-activated sludge system. At 20 ℃, rhamnolipids (11.2 mg/L) increased the removal efficiency of crude oil from 17.7% (in the absence of rham-nolipids) to 63%. At 25 ℃, the removal efficiency of crude oil was over 80% with the presence of rhamnolipids compared with 22.3% in the absence of rhamnolipids. Similarly, rhamnolipid treatment (22.5 mg/L) for 24 h at 20 ℃ significantly increased the removal rate of lubricating oil to 92% compared with 24% in the absence of rhamnolipids. The enhanced removal of hydrocarbons was mainly attributed to the improved solubility and the reduced interracial tension by rhamnolipids. We conclude that a direct application of the crude rhamnolipid solution from cell culture is effective and economic in removing oily contaminants from wastewater.     

Changes in the physiological properties and kinetics of citric acid accumulation via carbon ion irradiation mutagenesis of <Emphasis Type="Italic">Aspergillus niger</Emphasis>

The objective of this work was to produce citric acid from corn starch using a newly isolated mutant of Aspergillus niger, and to analyze the relationship between changes in the physiological properties of A. niger induced by carbon ion irradiation and citric acid accumulation. Our results showed that the physiological characteristics of conidia in A. niger were closely related to citric acid accumulation and that lower growth rate and viability of conidia may be beneficial to citric acid accumulation. Using corn starch as a raw material, a high-yielding citric acid mutant, named HW2, was obtained. In a 10-L bioreactor, HW2 can accumulate 118.9 g/L citric acid with a residual total sugar concentration of only 14.4 g/L. This represented an 18% increase in citric acid accumulation and a 12.5% decrease in sugar utilization compared with the original strain.     

Improved production of spiramycin by mutant<Emphasis Type="Italic">Streptomyces ambofaciens</Emphasis>

Strain improvement and medium optimization to increase the productivity of spiramycin were carried out. Of oil tolerant mutant strains screened, one mutant,Streptomyces ambofaciens XC 2–37, produced 9% more spiramycin than the parent strainS. ambofaciens XC 1–29. The effects of soybean oil and propyl alcohol on spiramycin production withS. ambofaciens XC 2–37 were studied. The potency ofS. ambofaciens XC 2–37 was improved by 61.8% with addition of 2% soybean oil in the fermentation medium and 0.4% propyl alcohol at 24 hours after incubation. The suitable time for feeding propyl alcohol is at 24 hours after incubation in flask fermentation and at 20 hours after incubation in fermentor fermentation. The new process withS. ambofaciens XC 2–37 was scaled up for industrial scale production of spiramycin in a 60 m³ fermentor in Xinchang Pharmaceutical Factory, Zhejiang Medicine Company, Ltd., China, and the potency and productivity of fermentation were improved by 42.9%.     

Improved production of spiramycin by mutant Streptomyces ambofaciens

Strain improvement and medium optimization to increase the productivity of spiramycin were carried out. Of oil tolerant mutant strains screened, one mutant, Streptomyces ambofaciens XC 2-37, produced 9% more spiramycin than the parent strain S. ambofaciens XC 1-29. The effects of soybean oil and propyl alcohol on spiramycin production with S. ambofaciens XC 2-37 were studied. The potency of S. ambofaciens XC 2-37 was improved by 61.8% with addition of 2% soybean oil in the fermentation medium and 0.4% propyl alcohol at 24 hours after incubation. The suitable time for feeding propyl alcohol is at 24 hours after incubation in flask fermentation and at 20 hours after incubation in fermentor fermentation. The new process with S. ambofaciens XC 2-37 was scaled up for industrial scale production of spiramycin in a 60 m3 fermentor in Xinchang Pharmaceutical Factory, Zhejiang Medicine Company, Ltd., China, and the potency and productivity of fermentation were improved by 42.9%.     

Improved production of spiramycin by mutant Streptomyces ambofaciens

INTRODUCTION which the hydroxyl group is acetylated, and spi- ramycin III in which the same position is propio- Spiramycin belongs to the macrolide antibi- nylated (Omura et al., 1979). The addition of short-otics group. The molecular structure of spiramycin chain fatty acids stimulates the production of spi-consists of a 16-membered branched lactonic ring …     

尖孢镰刀菌产碱性低温脂肪酶发酵条件的优化

通过实验对尖孢镰刀菌NC03摇床发酵产脂肪酶的培养基组成和培养条件进行了优化,得出最佳产酶培养基组成配方为：蛋白胨5 g/L,酵母膏6 g/L,NaH2PO43 g/L;橄榄油250 mL/L,吐温80 25 mL/L。最优发酵条件为250 mL的摇瓶装液量50 mL,培养温度30℃,发酵时间84 h。经过优化后发酵液脂肪酶酶活力最高可达到11.32 U/mL,较优化前提高了3.0倍。     

Optimization of biotransformation from phytosterol to androstenedione by a mutant Mycobacterium neoaurum ZJUVN-08

Biotransformation of phytosterol(PS) by a newly isolated mutant Mycobacterium neoaurum ZJUVN-08 to produce androstenedione has been investigated in this paper.The parameters of the biotransformation process were optimized using fractional factorial design and response surface methodology.Androstenedione was the sole product in the fermentation broth catalyzed by the mutant M.neoaurum ZJUVN-08 strain.Results showed that molar ratio of hydroxypropyl-β-cyclodextrin(HP-β-CD) to PS and substrate concentrations were the two most significant factors affecting androstenedione production.By analyzing the statistical model of three-dimensional surface plot,the optimal process conditions were observed at 0.1 g/L inducer,pH 7.0,molar ratio of HP-β-CD to PS 1.92:1,8.98 g/L PS,and at 120 h of incubation time.Under these conditions,the maximum androstenedione yield was 5.96 g/L and nearly the same with the non-optimized(5.99 g/L),while the maximum PS conversion rate was 94.69% which increased by 10.66% compared with the non-optimized(84.03%).The predicted optimum conditions from the mathematical model were in agreement with the verification experimental results.It is considered that response surface methodology was a powerful and efficient method to optimize the parameters of PS biotransformation process.     

Studies on optimization of nitrogen sources for astaxanthin production by <Emphasis Type="Italic">Phaffia rhodozyma</Emphasis>

Fermentation ofPhaffia rhodozyma is a major method for producing astaxanthin, an important pigment with industrial and pharmaceutical application. To improve astaxanthin productivity, single factor and mixture design experiments were used to investigate the effects of nitrogen source on Phaffia rhodozyma cultivation and astaxanthin production. Results of single factor experiments showed nitrogen source could significantly affect P. rhodozyma cultivation with respect to carbon source utilization, yeast growth and astaxanthin accumulation. Further studies of mixture design experiments using （NH4）2SO4, KNO3 and beef extract as nitrogen sources indicated that the proportion of three nitrogen sources was very important to astaxanthin production. Validation experiments showed that the optimal nitrogen source was composed of 0.28 g/L （NH4）2SO4, 0.49 g/L KNO3 and 1.19 g/L beef extract. The kinetic characteristics of batch cultivation were investigated in a 5-L pH-stat fermentor. The maximum amount of biomass and highest astaxanthin yield in terms of volume and in terms of biomass were 7.71 mg/L and 1.00 mg/g, respectively.     

光照和肌醇对木霉生长和产脂能力影响

木霉菌的许多种属都能够产生脂类物质,并且已经被用来研究脂类物质的生产.本研究主要探索光照和肌醇对木霉生物量积累和油脂量积累的作用.结果表明：与遮光处理组相比,正常光照培养条件更易于菌株成熟孢子的形成,并且正常光照培养也利于菌株L1生物量和油脂量的积累;肌醇的添加会促进菌株生物量的积累,但是对菌株L1油脂量的积累有一定的抑制作用,对菌株L2,相比无肌醇添加组,肌醇的添加在一定的培养时间上有利于油脂的形成.同时发现光照和肌醇能够影响木霉的脂类构成.     

温度、pH及碳氮源对产色素青霉菌株（Penicilliumsp．）生长的影响

PSO312是从土壤分离的1个青霉菌株,生长中能产生不同酸碱性条件下显黄色与紫红色等天然色素物质．通过菌株固体平板上恒温培养,168h测定菌落直径的方法研究了温度、pH及碳、氮源对菌株（Penicilliumsp．）生长的影响．研究表明31℃为菌株生长的最适温度．31℃培养以pH2—3的最快,pH8—9生长次之,24℃培养以pH8—9生长最快,pH3—4其次．菌株以蛋白胨4g／L、牛肉膏4g／L、酵母膏2g／L及尿素2g／L为氮源培养的菌落直径分别为55．75mm、51．5mm、55．5mm及25．3mm．在（NH4）2SO4 2g／L、NH4NO3 3g／L、NaNO3 4g／L、KN034g／L用量之上培养生长最快,菌落直径分别为35mm、34mm、35mm、及32mm．葡萄糖、蔗糖用量30g／L、果糖20g／L及乳糖25g／L的生长速率最快,菌落直径分别为45mm、38mm、38mm及39mm．丙三醇与淀粉25g／L培养的菌落直径均为39mm．     

饲用益生菌的筛选及发酵特性研究

以饲料为原料筛选出一株既产乳酸又产芽孢的益生菌,经过分子生物学鉴定为凝结芽孢杆菌(Bacillus coagulans),命名为T-8。从培养基碳源、氮源、有机物浸出液、培养基pH、培养温度、培养时间等方面对菌株T-8展开发酵特性研究,结果表明,最优培养基配方为:玉米粉6 g/L、豆粕粉15 g/L、小麦麸皮浸出液60%、酵母粉5 g/L、蛋白胨10 g/L、氯化钠10 g/L,pH 5.0。以5%的接种量将种子液转接至最优培养基,在47℃的摇床中以200 r/min的转速振荡培养28 h,菌株T-8的细胞密度达到4.8×10⁹ CFU/mL,芽孢率达到95.2%。本试验可为益生菌凝结芽孢杆菌应用于饲用微生物菌剂的工业化生产提供参考。     

石油污染物对日本三角涡虫的毒理作用、摄食及再生的影响

研究石油污染物对日本三角涡虫的急性毒性、摄食及再生的影响。结果表明,石油污染物对日本三角涡虫的24hLC50、48hLC50分别为83.47g／L、56.83g／L;≤6.67g／L的污染物对日本三角涡虫摄食的影响随污染浓度的增大与染毒时间的延长而增强;≥10.00g／L的污染物对涡虫再生的影响显著（P〈0.05）,且随处理时间的延长而影响逐渐减小。表明日本三角涡虫可作为检测石油污染物对水体污染程度的指示生物。     

Biosynthesis of (<Emphasis Type="Italic">R</Emphasis>)-2-hydroxy-3-phenylpropionic acid using whole recombinant <Emphasis Type="Italic">Escherichia coli</Emphasis> cells in an aqueous/<Emphasis Type="Italic">n</Emphasis>-octane biphasic system

(R)-2-hydroxy-3-phenylpropionic acid (PLA) is an ideal antimicrobial compound with broad-spectrum activity against a wide range of Gram-positive bacteria, some Gram-negative bacteria, and fungi. We studied the bioconversion of phenylpyruvate (PPA) to PLA using whole recombinant Escherichia coli cells in a series of buffer/organic solvent systems. Octane was found to be the best organic solvent. The optimum volume ratio of the water phase to the n-octane phase, conversion temperature, substrate concentration, and cell concentration were 6:4, 40 °C, 12.5 g/L, and 30 g/L wet cells, respectively. Under the optimized conditions, the average PLA productivity in the aqueous/n-octane system was 30.69% higher than that in the aqueous system, and 32.31 g/L PLA was obtained with the use of a stirred reactor (2-L scale). Taken together, our findings indicated that PLA biosynthesis was more efficient in an aqueous/n-octane biphasic system than in a monophasic aqueous system. The proposed biphasic system is an effective strategy for enhancing PLA yield and the biosynthesis of its analogues.     

油炸食品中影响丙烯酰胺含量的因素分析

通过高效液相色谱法检测油炸食品中丙烯酰胺的浓度,探讨不同温度、不同油炸时间、及不同厂家生产的面粉对丙烯酰胺含量的影响,从而选择最佳油炸食品的生产工艺条件。结果表明:油温200℃,油炸时间80秒,利用山东广饶XX面粉生产厂生产的面粉制成的油炸食品中丙烯酰胺含量低,且食品颜色、香味及脆度俱佳。     

Effects of medium composition on the production of plasmid DNA vector potentially for human gene therapy

INTRODUCTION The difficulties associated with large-scaleproduction of biotherapeutics provide a constantchallenge to the biotechnology industry. FDA hadadded “therapeutic DNA plasmid vectors” to the listof well-characterized biotechnology product (DoHHs,1996), and gene therapy has moved rapidly fromlaboratory scale to clinical trials. It is urgent to de-velop new protocols to obtain high-quality plasmidswith high yields and minimal or no contamination ofRNA and chromosomal D…     

高产乙醇酿酒酵母的筛选鉴定及发酵条件优化

从酵母浸粉中分离筛选出一株高产乙醇的菌株DL5168,经形态学观察、生理生化学及分子生物学鉴定,确定该菌株为酵母属的酿酒酵母(Saccharomyces cerevisiae)。通过优化实验,确定菌株DL5168发酵的最适条件为:初始葡萄糖浓度180 g/L;发酵温度30℃。在此条件下,菌株发酵的最终乙醇浓度为113.9 g/L,比对照菌株的乙醇浓度提高36%;乙醇转化率为0.64 g/g,比对照提高39%。     

产油脂酵母菌株的筛选及发酵条件的初步研究

对14份土样和7株实验室保藏菌株经初筛、摇瓶复筛,得到1株油脂产量较高的酵母菌,其油脂含量为7.34%。对影响该菌体产油脂的条件进行了单因素和正交实验,得出摇瓶发酵培养的最佳产油脂条件:发酵周期为4d,酵母膏和硫酸铵混合物为氮源,接种量为12%。在该条件下测得的菌体生物量为12.211g/L,油脂产量为1.524g/L,油脂含量为12.48%。