头孢菌素C产生菌的诱变育种及发酵应用的研究

此次研究以头孢菌素 C 产生菌顶头孢霉 B-1822-S-04 为出发菌株,通过紫外线和丙二酸复合诱变,成功筛选出 4 株头孢菌素 C 高产菌株 D-G-017、D-G-083、D-G-096 和 D-G-133。其中,菌株 D-G-096的效价高达 6816mg·L-1,相较于出发菌株提高了 50.80%,且高产特性稳定。进一步在 50L 发酵罐小试中,菌株 D-G-096 的效价达到了 29270mg·L-1,较出发菌株提高了 111.06%,表现出显著的高产优势。这些结果表明,筛选得到的高产菌株具有巨大的应用潜力。本研究筛选出的高产菌株及其在小试中的应用成果,为后期工业化生产提供了优质菌种资源,对发酵工艺优化具有重要的指导意义。

发酵法生产无热量的赤藓糖醇及其特性和应用

本文介绍了赤藓糖醇的特性、应用以及发酵法生产方法.

糖蜜的应用研究进展

阐述了制糖下脚料糖蜜的应用研究进展,主要介绍了糖蜜的直接应用、发酵应用及改性应用研究。展望了改性糖蜜的应用研究前景。

The Nucleosides Contents and Their Variation in Natural Cordyceps sinensis and Cultured Cordyceps Mycelia

Aim: To compare the contents of nucleosides from natural Cordyceps sinensis and cultured Cordyceps mycelia, and to study the effect of humidity and heat on the content of nucleosides. Methods: The contents of nucleosides were determined by using high performance capillary electrophoresis (HPCE). Beckman P/ACE System 5010 apparatus equipped with a UV detector and a Beckman untreated fused-silica capillary (57 cm 75 mm, 50 cm effective length) was used. Before sample injection, the capillary was rinsed with 1 molL-1 sodium hydroxide solution and running buffer for 5 min, respectively. A voltage of 20 kV was applied for the separation. Pressure injection was 586 kPa for 6 seconds, and the wavelength of detector was 254 nm. The running time was 20 min at 20 oC. The effect of humidity and heat on the contents of nucleosides from natural Cordyceps sinensis and cultured Cordyceps mycelia was observed for 1, 3, 5 and 10 days at temperature 40 oC, and relative humidity 75%. Results: The content of nucleosides from natural Cordyceps sinensis was higher than that from cultured Cordyceps mycelia. But the contents of nucleosides from freshly collected natural Cordyceps sinensis were very low, even below the limit of quantitation. The contents of nucleosides from natural Cordyceps sinensis were significantly increased by humidity and heat, but this phenomenon was not observed in cultured Cordyceps mycelia. Conclusion: There are differences between the nucleosides from natural Cordyceps sinensis and cultured Cordyceps mycelia. The nucleosides in natural Cordyceps sinensis may be derived from the degradation of nucleic acids. This implies that adenosine being used for the quality control of natural Cordyceps sinensis may have to be reconsidered.

Isolation and Identification of a Taxol-producing Endophytic Fungus Identified from Taxus media

[Objective] The aim was to isolate and identify a taxol-producing endophytic fungus from Taxus media. [Method] 32 strains of endophytic fungi were identified form the inner bark of T. media,and their fermentation products were detected by high performance liquid chromatography (HPLC). [Result] Through the screening,a strain of taxol-producing endophytic fungi M57 was obtained,which could produce 45-50 μg/L of taxol,and M57 was defined as Rhizopus sp. through morphological observation and 18S rDNA sequence analysis. [Conclusion] The finding of Rhizopus sp. M57 provided a promising strain for producing taxol with taxol-producing fungi fermentation process.

Effective and simple recovery of 1,3-propanediol from a fermented medium by liquid–liquid extraction system with ethanol and K_3PO_4

1,3-Propanediol,traditionally obtained from fossils,has numerous industrial applications,including use in the production of high performance polymers.The microbial production of 1,3-propanediol presents several opportunities,and the final purity grade determines its price and commercial viability.The development of novel separation technology could improve the economic viability of the bioproduction of 1,3-propanediol.Thus,we investigated salting-out extraction as a novel process for 1,3-propanediol recovery from fermentation broth.Initially,a screening for the best salt/solvent combination was conducted and then optimized using the response surface methodology.The solvents studied were methanol,ethanol,isopropanol and acetone,and the salts examined were K_2HPO_4,Na_2CO_3,K_2CO_3,(NH_4)_2SO_4,NaHPO_4,K_3PO_4 and C_6H_5NaO_7.The optimal extraction system consisted of 34 wt%K_3PO_4,28 wt% ethanol,and 38 wt% fermentation broth containing 23.0 g·L^(-1)1,3-propanediol,which gave the highest partition coefficient of 33 and recovery yield of 97%.The results demonstrated that salting-out extraction was a promising method for 1,3-propanediol recovery from fermentation broth.

Effects of Application of Cassava Alcohol Anaerobic Fermentation Liquid and Mulching of Film on Overwintering and Next Year's Growth and Yield of Banana

The effects of application of cassava alcohol anaerobic fermentation liquid and mulching of film on overwintering and next year's growth and yield of banana were investigated in this study.The results showed that the application of cassava alcohol anaerobic fermentation liquid with COD concentration of 1 200-2 000 mg/L(900 m^3/hm^2) and mulching of film significantly increased the soil organic matter and available potassium contents in banana orchard,improved the cold resistance of banana seedlings,increased the pseudostem height,pseudostem circumference,green leaf number and chlorophyll content of next year's banana seedlings,brought the flower bud emergence period and harvest period forward,and significantly increased the yield per plant.

Characterization of promoters in Escherichia coli and application for xylitol synthesis

Promoters are the most important tools to control and regulate the gene expression in synthetic biology and metabolic engineering. The expression of target genes in Escherichia coli is usually controlled by the high-strength inducible promoter with the result that the abnormally high transcription of these genes creates excessive metabolic load on the host, which decreases product formation. The constitutive expression systems are capable of avoiding these defects. In this study, to enrich the application of constitutive promoters in metabolic engineering, four promoters from the glycolytic pathway of E. coli were cloned and characterized using the enhanced green fluorescent protein as reporter. Among these promoters, Pgap Awas determined as the strongest one, the strength of which was about 8.92% of that of the widely used inducible promoter PT7. This promoter was used to control the expression of heterologous xylose reductase in E. coli for xylitol synthesis so as to verify its function in pathway engineering. The maximum xylitol titer(40.6 g·L-1) produced by engineered E. coli under the control of the constitutive promoter Pgap Awas obviously higher than that under the control of the inducible promoter PT7,indicating the feasibility and superiority of promoter Pgap Ain the metabolic engineering of E. coli.

A new improved Alopex-based evolutionary algorithm and its application to parameter estimation

In this work, focusing on the demerit of AEA (Alopex-based evolutionary algorithm) algorithm, an improved AEA algorithm (AEA-C) which was fused AEA with clonal selection algorithm was proposed. Considering the irrationality of the method that generated candidate solutions at each iteration of AEA, clonal selection algorithm could be applied to improve the method. The performance of the proposed new algorithm was studied by using 22 benchmark functions and was compared with original AEA given the same conditions. The experimental results show that the AEA-C clearly outperforms the original AEA for almost all the 22 benchmark functions with 10, 30, 50 dimensions in success rates, solution quality and stability. Furthermore, AEA-C was applied to estimate 6 kinetics parameters of the fermentation dynamics models. The standard deviation of the objective function calculated by the AEA-C is 41.46 and is far less than that of other literatures' results, and the fitting curves obtained by AEA-C are more in line with the actual fermentation process curves.

Unscented Transformation Based Robust Kalman Filter and Its Applications in Fermentation Process

State estimation is the precondition and foundation of a bioprocess monitoring and optimal control. However,there are many difficulties in dealing with a non-linear system,such as the instability of process, un-modeled dynamics,parameter sensitivity,etc.This paper discusses the principles and characteristics of three different approaches,extended Kalman filters,strong tracking filters and unscented transformation based Kalman filters.By introducing the unscented transformation method and a sub-optimal fading factor to correct the prediction error covariance,an improved Kalman filter,unscented transformation based robust Kalman filter,is proposed. The performance of the algorithm is compared with the strong tracking filter and unscented transformation based Kalman filter and illustrated in a typical case study for glutathione fermentation process.The results show that the proposed algorithm presents better accuracy and stability on the state estimation in numerical calculations.

Application Prospects for the Innovation of Defined Fungal Starter in Rice Wine Fermentation

The feasibility of pilot-scale manufacture of defined fungal starter and its application in rice wine production from different local starchy materials were investigated. Starter consisting of Arnylomyces rouxii and Saccharomyces cerevisiae gave high performance in winemaking when prepared in conditions of rice flour 80% and cassava flour 20% with 4 incubation days. The starter level at 20% was favourably employed for manufacture with the initial amount of I0 kg mixed-flours, Dry starter granules which were vacuum packed could adapt ambient temperature （approx. 28-32℃） during 8 months of storage. The defined starter performed as superior inoculum for winemaking from different agricultural starchy resources. The undesirable bacteria were found at approx. 2 Log CFU/g of dry starter. By morphology, biochemical and physiological growth and the genetic partial 16S analyses, three bacterial isolates were characterized as Bacillus subtilis/amvloliquefaciens which may contaminate tbod but not cause food poisoning and not considered as a human pathogen.

高效降解OTA的发酵工业用菌株筛选及鉴定

赭曲霉毒素A(OTA)是粮食类食品中常见的一种真菌毒素,生物方式降解OTA是目前最具前景的研究方向,而高效降解OTA的菌种筛选仍是生物降解的重要研究内容.研究用缺陷型培养基从土壤中采用TLC法、HPLC法经初筛和复筛获得高效降解OTA的菌株.最终得到4株菌M00120、M30011、M10012及M40011,其降解率分别为99%、81%、76%及71%.随后对其进行鉴定,并根据降解效率及应用安全性,发掘得到具有较大应用价值的黑曲霉M00120及米曲霉M30011,为其进一步在发酵上的应用提供研究依据.