排序方式: 共有123条查询结果,搜索用时 15 毫秒
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为筛选新型高产胞外多糖(exopolysaccharides,EPS)的酵母菌株,满足工业化生产的要求,该研究利用WL选择培养基和产糖基础培养基筛选出高产EPS的酵母菌,通过形态特征观察、生理生化试验和18S rDNA技术对其进行鉴定,并利用响应面方法对菌株产胞外多糖条件进行优化。结果表明,从土壤中筛选得到一株高产EPS的酵母菌,经鉴定,该酵母菌为近粉红锁掷孢酵母(Sporidiobolus pararoseus),命名为S.pararoseus PFY-Z1,当葡萄糖17.34 g/L、硫酸镁1.98 g/L、初始pH值5.3时,EPS的含量为(6.74±0.13)g/L,是优化前的1.63倍。不仅为EPS的生产提供菌种来源,也为今后利用S.pararoseus大规模生产EPS提供理论基础。 相似文献
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Bakhtiyar Islamov Olga Petrova Polina Mikshina Aidar Kadyirov Vladimir Vorobev Yuri Gogolev Vladimir Gorshkov 《International journal of molecular sciences》2021,22(23)
The phytopathogenic bacterium Pectobacterium atrosepticum (Pba), one of the members of the soft rot Pectobacteriaceae, forms biofilm-like structures known as bacterial emboli when colonizing the primary xylem vessels of the host plants. The initial extracellular matrix of the bacterial emboli is composed of the host plant’s pectic polysaccharides, which are gradually substituted by the Pba-produced exopolysaccharides (Pba EPS) as the bacterial emboli “mature”. No information about the properties of Pba EPS and their possible roles in Pba-plant interactions has so far been obtained. We have shown that Pba EPS possess physical properties that can promote the maintenance of the structural integrity of bacterial emboli. These polymers increase the viscosity of liquids and form large supramolecular aggregates. The formation of Pba EPS aggregates is provided (at least partly) by the acetyl groups of the Pba EPS molecules. Besides, Pba EPS scavenge reactive oxygen species (ROS), the accumulation of which is known to be associated with the formation of bacterial emboli. In addition, Pba EPS act as suppressors of the quantitative immunity of plants, repressing PAMP-induced reactions; this property is partly lost in the deacetylated form of Pba EPS. Overall, our study shows that Pba EPS play structural, protective, and immunosuppressive roles during Pba–plant interactions and thus should be considered as virulence factors of these bacteria. 相似文献
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Corinne Cassier-Chauvat Franck Chauvat 《International journal of molecular sciences》2015,16(1):871-886
Cyanobacteria, the only known prokaryotes that perform oxygen-evolving photosynthesis, are receiving strong attention in basic and applied research. In using solar energy, water, CO2 and mineral salts to produce a large amount of biomass for the food chain, cyanobacteria constitute the first biological barrier against the entry of toxics into the food chain. In addition, cyanobacteria have the potential for the solar-driven carbon-neutral production of biofuels. However, cyanobacteria are often challenged by toxic reactive oxygen species generated under intense illumination, i.e., when their production of photosynthetic electrons exceeds what they need for the assimilation of inorganic nutrients. Furthermore, in requiring high amounts of various metals for growth, cyanobacteria are also frequently affected by drastic changes in metal availabilities. They are often challenged by heavy metals, which are increasingly spread out in the environment through human activities, and constitute persistent pollutants because they cannot be degraded. Consequently, it is important to analyze the protection against oxidative and metal stresses in cyanobacteria because these ancient organisms have developed most of these processes, a large number of which have been conserved during evolution. This review summarizes what is known regarding these mechanisms, emphasizing on their crosstalk. 相似文献
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副干酪乳杆菌及其胞外多糖的抗氧化性研究 总被引:1,自引:0,他引:1
以具有抗氧化性的嗜酸乳杆菌ATCC4356为对照,研究了1株副干酪乳杆菌H9的抗氧化性。分析了2株菌不同浓度下菌悬液和无细胞提取液的DPPH自由基清除能力、金属离子螯合能力和抑制脂质过氧化能力。并对H9菌株菌悬液煮沸灭活前后的抗氧化能力进行了比较。同时,对H9菌株自产的胞外多糖的抗氧化性进行了研究,测定了其在不同浓度下DPPH自由基清除能力、超氧自由基清除能力、羟自由基清除能力。结果表明:H9菌株的菌悬液和无细胞提取液抗氧化能力均随着浓度的升高呈上升趋势,浓度达到109cfu/mL时抗氧化能力最强,此时DPPH的清除能力分别达到(55.0±1.7)%和(47.5±1.8)%,螯合金属离子的能力分别为(15.2±1.2)%和(15.1±1.3)%,抑制脂质过氧化的能力分别为(76.2±1.1)%和(70.0±0.4)%。煮沸后菌悬液抗氧化能力趋势与未煮沸前一致,但同等浓度下煮沸处理会降低其抗氧化能力。H9菌株自产胞外多糖也具有较强的抗氧化能力,并随着多糖浓度的升高抗氧化能力增强。结果表明H9菌株的抗氧化性可能与活细胞和菌体代谢产物密切相关。 相似文献
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Susanne B. Kaditzky Jürgen Behr Andreas Stocker Peter Kaden Michael G. Gänzle 《Food Biotechnology》2013,27(4):398-418
Lactobacillus reuteri TMW 1.106, a dominant type II sourdough bacterium, produces glucan from sucrose in vitro and in situ. Exopolysaccharides positively affect the texture and mouth feel of foods and their in situ production in fermented foods could be an alternative to the addition of hydrocolloids from plants or non-GRAS microorganisms. The aim of this study was to elucidate a probable function of the EPS for the bacterium. Lb. reuteri TMW 1.106 harbors two glucosyltransferases, Gtf106A and Gtf106B and produces a dextran. Gtf106B exhibited hydrolysis but no transferase activity. Enzymatic production of dextran with the heterologously expressed, N-terminally truncated ΔN Gtf106A was highest at a pH of 4.0, whereas dextran formation in pH static fermentations was optimal between pH 4.7 and 5.4. The dextran synthesised at these pH values had the highest molecular mass (1.2 × 107) and 15% α–(1–4) linkages. A protective effect of this EPS on Lb. reuteri TMW 1.106 against low pH, explaining the low pH-production maximum, could be demonstrated through the delay of cell death. 相似文献
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主要介绍了豆科植物根瘤菌产生的胞外多糖(EPS)的结构、合成与调控,结合以上知识综述了EPS的信号、免疫调节和抗肿瘤的功能。 相似文献
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DITTE MARIE FOLKENBERG PETR DEJMEK ANNE SKRIVER RICHARD IPSEN 《Journal of texture studies》2005,36(2):174-189
Set yoghurts produced with seven different exopolysaccharide‐producing starter cultures were subjected to sensory texture profiling including texture evaluation before and after a stirring procedure carried out by trained assessors. The microstructure of four selected yoghurts was investigated by confocal laser scanning microscopy with special focus on the distribution of exopolysaccharides (EPS) in the protein network. Two different types of microstructures were observed, one in which EPS were associated with the protein network and another where EPS appeared to be incompatible with the protein; as a consequence, the EPS were situated in the void spaces in the protein network. The latter yoghurts were less ropy and had higher serum separation than the yoghurts where EPS were associated with the protein, and they exhibited a significant increase in mouth thickness as a result of stirring. Yoghurts in which the EPS were associated with protein had high ropiness, low serum separation and appeared more resistant to stirring. The nature of EPS‐protein interactions is extremely important for the textural effects of EPS in fermented milk products, and such interactions depend on the specific starter culture used. 相似文献
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