微生物制氢技术研究进展

氢气是一种清洁高效的可再生能源.该文比较分析了常用于氢气制取的方法,讨论了生物制氢的微生物种类以及发酵产氢的诸多影响因素,对目前生物制氢的研究进展进行了综述.     

微生物发酵产木聚糖酶研究进展

木聚糖是植物半纤维素的主要成分,是自然界中仅次于纤维素的可再生资源。木聚糖酶是一类重要的木糖苷键水解酶酶系,可将木聚糖逐次降解为低聚木糖及木糖,在饲料、造纸、食品和生物转化等行业应用广泛。目前利用微生物发酵生产木聚糖酶的研究很多,菌种涉及到细菌、真菌等,其发酵生产木聚糖酶的工艺、产量及特性也各有不同,对此进行了综述,并展望了木聚糖酶发酵生产的研究方向。     

微生物发酵生产脂肪酶的研究进展

脂肪酶是一种重要的工业用酶,广泛应用于食品、精细化工、医药和能源等领域.脂肪酶最主要的来源是通过微生物发酵生产.综述了脂肪酶种类、高产脂肪酶菌种选育、发酵工艺优化与调控、高密度发酵和发酵工艺放大等方面的研究进展,并展望了脂肪酶发酵生产的研究方向及前景.     

Microbial Production of Optically Pure l-Iditol by Yeast Strains

Several yeast strains belonging to genus Candida were found to selectively hydrogenate l-sorbose with enantiomeric specificity, yielding optically pure l-iditol in the culture broth. The most active strain, isolated from a commercial lemon, was identified as Candida intermedia, which produced 50 g of l-iditol per liter from 150 g of l-sorbose per liter during a 5-day fermentation period (35% yield).     

微生物法生产L-丝氨酸代谢工程研究进展

L-丝氨酸是生物体内一种重要的中间代谢产物,为甘氨酸等多种氨基酸、核苷酸、胆碱、磷脂的合成前体,现已广泛应用于医药、食品、化妆品等领域。L-丝氨酸的生产方法有蛋白质水解提取法、化学合成法、转化法及微生物发酵法,其中微生物发酵法具有原料廉价、环境污染小、产物纯度高等优点。系统综述了微生物发酵法生产L-丝氨酸所涉及的代谢工程策略,包括微生物合成L-丝氨酸的各种代谢调控机制及相应采取的改造措施和效果,并探讨了L-丝氨酸育种技术未来的发展趋势。     

微生物发酵生产辅酶Q10的研究进展

利用微生物发酵生产辅酶Q1 0 产物活性好 ,并可通过规模放大提高生产能力 ,因而颇受国内外学者的关注。文章综述菌种的选择和遗传改造 ,发酵条件的优化及其分离纯化     

微生物菌种改良筛选新技术研究进展

从自然界筛选出来的微生物菌株往往活性比较低,耐受性比较差,不能满足工业化生产的要求.而采用新颖的诱变技术,如微波、离子注入、原生质体诱变和原生质体融合、基因工程技术等能有效改良菌种,提高菌种的活性,降低生产成本,满足工业化生产的要求.同时,构建一种简单易行的改良路线和快速有效的筛选模式是菌种改良选育的关键.     

微生物合成根皮素及其糖苷研究进展 *

根皮素及其糖苷是二氢查耳酮类天然产物,具有抗氧化、抗炎和抑菌等多种生理活性,可应用于食品、药品、化妆品等行业。目前,根皮素及其糖苷主要从植物中提取,但含量低、组分复杂制约了高效、低成本的分离制备。随着合成生物学的发展,工程微生物生产根皮素及其糖苷将是一种有潜力的方法。综述了微生物合成根皮素及其糖苷的关键基因鉴定、代谢途径重构和优化策略,并针对酶的特异性差、副产物多等问题提出了技术对策。     

微生物酶解法产生阿拉伯糖——菌种筛选与初步鉴定

使用半纤维素平板法从土壤分离菌中筛选到产半纤维素酶活较高的真菌。将这些菌株在含玉米芯半纤维素的培养基中发酵,鉴定发酵液中还原糖产量,从中筛选出3株产还原糖较多的菌。将其发酵产物经柱前衍生,HPLC检测,发现其中DHC菌株的发酵产物以木糖和阿拉伯糖为主,而培养基中的葡萄糖大部分被利用,可用于发酵法联产阿拉伯糖和木糖。对DHC菌株通过菌落形态、孢子形态以及ITS区基因序列测序分析,初步确定该菌为亮白曲霉(Aspergillus candidus)。对于亮白曲霉产生的半纤维素酶国内外尚较少研究报导,可为开发利用新的微生物资源奠定基础。     

基于微生物同化作用的D-丙氨酸生产工艺研究

以L-丙氨酸为唯一碳氮源,从采集的若干土壤中初筛出能够降解L-丙氨酸的菌株;再以D-丙氨酸为唯一碳氮源,复筛出降解L-丙氨酸而不降解D-丙氨酸的菌株。依据菌种对DL-丙氨酸的不对称降解活性,筛选出具有最高的L-丙氨酸降解活性的菌株,并对菌株同化L-丙氨酸的反应条件进行了研究。结果表明:编号为ALA-D82的菌株具有最高的降解L-丙氨酸的能力,经鉴定为酵母菌属。在30℃,控制pH6.0,通气比1:1(V/V)和转速900 r.min-1的条件下,L-丙氨酸降解的速度最大。在最适条件下,1500 g DL-丙氨酸分两部分添加入7 L的反应液中。反应72 h后溶液中的L-丙氨酸被完全降解,提取得到D-丙氨酸晶体,产率和光学纯度分别达到92.13%和99%。     

菜籽粕制备复合氨基酸螯合铜的工艺优化

发酵工艺已成功开发并用于生产大部分必需氨基酸,但蛋氨酸却是例外.尽管已经尝试利用微生物法生产蛋氨酸,但至今未能实现商业化生产.本文详细讨论了大肠杆菌、棒状杆菌和短杆菌等有潜在产蛋氨酸能力的菌株体内的蛋氨酸生物合成调节机制,阐述了微生物发酵法产蛋氨酸的研究进展,对蛋氨酸发酵生产的发展前景进行了展望.     

微生物发酵琥珀酸的研究进展

琥珀酸是一种重要的C_4平台化合物,生物基琥珀酸可作为合成大宗化学品的起始原料,在食品、医药、表面活性剂、洗涤剂、绿色溶剂、生物可降解塑料和动植物生长刺激物剂领域有广泛的应用前景。从可再生原料出发,发酵过程固定CO_2,使得微生物发酵生产琥珀酸具有良好的环境优势,成为近年研究的热点。围绕微生物发酵法生产琥珀酸迫切需要解决的主要问题,综述了国内外对琥珀酸生产菌的选育、其代谢机理与产酸条件、发酵过程工艺、产品提取等方面的研究现状。     

ATP Modulates the Growth of Specific Microbial Strains

The regulatory function of extracellular ATP (exATP) in bacteria is unknown, but recent studies have demonstrated exATP induced enhanced secondary metabolite production and morphological differentiation in Streptomyces coelicolor. The growth of Streptomyces coelicolor, however, was unaffected by exATP, although changes in growth are common phenotypes. To identify bacteria whose growth is altered by exATP, we measured exATP-induced population changes in fast-growing microbes and actinomycetes in compost. Compared with the water-treated control, the addition of 10 ml 100 μM ATP to 10 g of compost enhanced the actinomycetes population by 30% and decreased fast-growing microbial numbers by 20%. Eight microbes from each group were selected from the most populated colony, based on appearance. Of the eight isolated fast-growing microbes, the 16S rRNA sequences of three isolates were similar to the plant pathogens Serratia proteamaculans and Sphingomonas melonis, and one was close to a human pathogen, Elizabethkingia meningoseptica. The growth of all fast-growing microbes was inhibited by ATP, which was confirmed in Pseudomonas syringae DC3000, a pathogenic plant bacterium. The growth of six of eight isolated actinomycetes strains, all of which were identified as close to Streptomyces neyagawaensis, was enhanced by ATP treatment. This study suggests that exATP regulates bacterial physiology and that the exATP response system is a target for the control of bacterial ecology.     

微生物产生的生物表面活性剂及其应用研究

对生物表面活性剂的类型及其产生微生物,生物表面活性剂的生产和生物表面活性剂在石油开采、食品工业、农业、药品和化妆品以及环境保护等领域的潜在应用价值作了介绍,展现出了生物表面活性剂的广阔应用前景。     

微生物分子生态学研究方法的新进展

环境中微生物的群落结构及多样性和微生物的功能及代谢机理是微生物生态学的研究热点,长期以来,由于受到研究技术的限制,对微生物的群落结构和多样性的认识还不全面,微生物的功能及代谢机理方面了解也很少.随着高通量测序、基因芯片等新技术的不断更新,微生物分子生态学的研究方法和研究途径也在不断变化.高通量测序技术改变了微生物多样性、宏基因组学和宏转录组学的研究方法,GeoChip高密度覆盖海量已知功能的基因探针于单张芯片,能快速确定微生物和已知功能基因的存在与否.总结和比较了目前最新的研究手段,并归纳了这些方法的适用性和优缺点.     

An Enzymatic Assay for High-Throughput Screening of Cytidine-Producing Microbial Strains

Cytidine is an industrially useful precursor for the production of antiviral compounds and a variety of industrial compounds. Interest in the microbial production of cytidine has grown recently and high-throughput screening of cytidine over-producers is an important approach in large-scale industrial production using microorganisms. An enzymatic assay for cytidine was developed combining cytidine deaminase (CDA) and indophenol method. CDA catalyzes the cleavage of cytidine to uridine and NH₃, the latter of which can be accurately determined using the indophenol method. The assay was performed in 96-well plates and had a linear detection range of cytidine of 0.058 - 10 mM. This assay was used to determine the amount of cytidine in fermentation flasks and the results were compared with that of High Perfomance Liquid Chromatography (HPLC) method. The detection range of the CDA method is not as wide as that of the HPLC, furthermore the correlation factor of CDA method is not as high as that of HPLC. However, it was suitable for the detection of large numbers of crude samples and was applied to high-throughput screening for high cytidine-producing strains using 96-well deep-hole culture plates. This assay was proved to be simple, accurate, specific and suitable for cytidine detection and high-throughput screening of cytidine-producing strains in large numbers of samples (96 well or more).     

Development of Genetically Stable Escherichia coli Strains for Poly(3-Hydroxypropionate) Production

Poly(3-hydroxypropionate) (P3HP) is a biodegradable and biocompatible thermoplastic. In our previous study, a pathway for P3HP production was constructed in recombinant Esecherichia coli. Seven exogenous genes in P3HP synthesis pathway were carried by two plasmid vectors. However, the P3HP production was severely suppressed by strain instability due to plasmid loss. In this paper, two strategies, chromosomal gene integration and plasmid addiction system (PAS) based on amino acid anabolism, were applied to construct a genetically stable strain. Finally, a combination of those two methods resulted in the best results. The resultant strain carried a portion of P3HP synthesis genes on chromosome and the others on plasmid, and also brought a tyrosine-auxotrophy based PAS. In aerobic fed-batch fermentation, this strain produced 25.7 g/L P3HP from glycerol, about 2.5-time higher than the previous strain with two plasmids. To the best of our knowledge, this is the highest P3HP production from inexpensive carbon sources.     

微生物法生产丙烯酸的研究进展

目前,丙烯酸工业生产都是利用石油产品丙烯氧化得到,石油的不可再生性迫使人们寻找新的替代方法,利用微生物来生产丙烯酸是个有希望的选择。该文回顾了近期利用微生物法生产丙烯酸的研究和进展,介绍了利用不同原料生产丙烯酸的方法,并对微生物法生产丙烯酸的可行性进行了展望。     

Microbial Consortia for Hydrogen Production Enhancement

Ten efficient hydrogen-producing strains affiliated to the Clostridium genus were used to develop consortia for hydrogen production. In order to determine their saccharolytic and proteolytic activities, glucose and meat extract were tested as fermentation substrates, and the best hydrogen-producing strains were selected. The C. roseum H5 (glucose-consuming) and C. butyricum R4 (protein-degrading) co-culture was the best hydrogen-producing co-culture. The end-fermentation products for the axenic cultures and co-cultures were analyzed. In all cases, organic acids, mainly butyrate and acetate, were produced lowering the pH and thus inhibiting further hydrogen production. In order to replace the need for reducing agents for the anaerobic growth of clostridia, a microbial consortium including Clostridium spp. and an oxygen-consuming microorganism able to form dense granules (Streptomyces sp.) was created. Increased yields of hydrogen were achieved. The effect of adding a butyrate-degrading bacteria and an acetate-consuming archaea to the consortia was also studied.