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991.
Xiaoru Wang Xiaorong Tian Yuanjie Wu Xiaofang Shen Songbai Yang 《Preparative biochemistry & biotechnology》2013,43(6):514-521
AbstractDoxorubicin (DXR), which is produced by Streptomyces peucetius, is an important anthracycline-type antibiotic used for the treatment of various cancers. However, due to the low DXR productivity of wild-type S. peucetius, it is difficult to produce DXR by one-step fermentation. In this study, a DXR-resistance screening method was developed to screen for DXR high-producing mutants. Then, S. peucetius SIPI-11 was treated several times with UV and ARTP (atmospheric and room temperature plasma) to induce mutations. Treated strains were screened by spreading on a DXR-containing plate, isolating a mutant (S. peucetius 33-24) with enhanced DXR yield (570?mg/L vs. 119?mg/L for the original strain). The components of the fermentation medium, including the carbon and nitrogen sources, were optimized to further enhance DXR yield (to 850?mg/L). The pH of the fermentation medium and culture temperature were also optimized for effective DXR production. Finally, DXR production by S. peucetius 33-24 was investigated in flask culture and a fermenter. The yield of DXR was as high as 1100?mg/L in a 5-L fermenter, which is the highest DXR productivity reported thus far, suggesting that S. peucetius 33-24 has the potential to produce DXR by direct fermentation. 相似文献
992.
Veneta Ivanova Dimitrinka Lyutskanova Margarita Stoilova-Disheva Mariana Kolarova Krasja Aleksieva Vesela Raykovska 《Preparative biochemistry & biotechnology》2013,43(1):46-56
Abstract Streptomyces sp. strain SB9 was isolated from perm frost soil samples in Spitsbergen, Arctic Ocean; it grows in a temperature range between 4°C and 28°C. During the survey of biologically active metabolites biosynthesized by this strain, significant amounts of α,α-trehalose (1) and glycerol (2) were detected. The compounds were isolated from the mycelium, were chromatographically separated, and the structures were elucidated on the basis of MS and NMR measurements. A possible role of trehalose in cold adaptation of the strain was examined. It was determined that the mycelium of the strain cultivated at 4°C accumulated 5-fold higher amounts of trehalose in comparison with the cells cultivated at 28°C. The mesofilic reference strains, Streptomyces spectabilis NRRL 2494 and Streptomyces lividans TK64, accumulated 100-fold less trahalose than the psychrotolerant Streptomyces sp. SB9. High amounts of trehalose in the cells could be a reason for adaptation of the strain to life at Arctic conditions. 相似文献
993.
Peng Geng Ting Sun Qiping Zhong Xiaoxia Li Liying Shi Fang Bai Gang Bai 《化学与生物多样性》2013,10(3):452-459
Two novel aminooligosaccharides were separated from the culture filtrate of Streptomyces coelicoflavus ZG0656. Their chemical structures were determined by acidic hydrolysis, electrospray‐ionization tandem mass spectrometry (ESI‐MS/MS), and NMR spectroscopy. The compounds were named acarviostatins III0(?1) and III23 according to the nomenclature of this group of metabolites. The two novel acarviostatins were both mixed noncompetitive inhibitors of porcine pancreatic α‐amylase (PPA). The inhibition constants (Ki) for acarviostatins III0(?1) and III23 were 0.009 and 0.026 μM , respectively, 151 and 52 times more potent than acarbose. 相似文献
994.
目的:考察不同细胞培养方式对Streptomyces sp. M-Z18转化前体L-赖氨酸合成ε-聚赖氨酸过程的影响。方法:利用两阶段细胞培养和发酵过程流加方式,建立了两阶段细胞培养转化前体L-赖氨酸合成ε-聚赖氨酸以及转化前体L-赖氨酸耦合甘油发酵生产ε-聚赖氨酸的策略。结果:(1)两阶段细胞培养转化前体L-赖氨酸合成ε-聚赖氨酸策略实现ε-PL积累15 g/L, 转化L-赖氨酸3 g/L;(2)转化前体L-赖氨酸耦合甘油发酵生产ε-聚赖氨酸策略使得ε-PL产量达到33.76 g/L,单位菌体的合成能力提高37.8%,转化L-赖氨酸4 g/L。这表明,上述两种方式下前体L-赖氨酸都能够被Streptomyces sp. M-Z18转化合成ε-聚赖氨酸,但转化效率还有待进一步提高。意义:揭示了Streptomyces sp. M-Z18合成ε-聚赖氨酸的限速步骤在于初级代谢产物L-赖氨酸的合成,这为后续利用代谢工程手段改造菌株提供了方向。 相似文献
995.
Huiling Wu Dan Dong Jinjin Li Ting Liu Taotao Zhang 《Biocontrol Science and Technology》2014,24(1):90-102
Streptomyces have been used extensively as the biocontrol agents due to their ability to produce various antimicrobial compounds, such as antibiotics and hydrolytic enzymes. Streptomyces lydicus strain A02, which was isolated from the soil of suburban forest field in Beijing (China), is capable of producing natamycin and has proved to be a potential biocontrol agent to several plant fungal diseases, including wilts caused by Fusarium oxysporum f. spp. However, hydrolytic enzymes like glucanase have not been detected in S. lydicus A02 on CMC-Na plates by congo red staining. Glucanase, a pathogenesis-related (PR) protein, degrades fungal cell walls and has been widely used as antifungal agent in plant protection. Therefore, a recombinant S. lydicus expressing a glucanase gene, which was cloned from the biocontrol strain Bacillus megaterium L103 and driven by the Streptomyces erythraea ermE* promoter, was constructed in this study. The engineered S. lydicus AG02 shared a similar yield of natamycin with the wild-type A02 strain. Compared to the wild-type strain A02, the engineered S. lydicus AG02 had a remarkably higher glucanase activity, as well as antifungal activity to F. oxysporum f. sp. conglutinans, F. oxysporum f. sp. niveum and Rhizoctonia cerealis. This demonstrated the improved biocontrol effect of S. lydicus AG02 attributed to transforming the exogenous glucanase from B. megaterium, which acted synergistically with natamycin to increase the antifungal activity of the strain. 相似文献
996.
Organization of biosynthetic gene cluster for avermectin in Streptomyces avermitilis: analysis of enzymatic domains in four polyketide synthases 总被引:4,自引:0,他引:4
The analysis of the incorporation of 13C-labeled precursors into avermectins indicates that the avermectin aglycons are synthesized by head-to-tail condensation
of various acyl groups, which is similar to the biosynthesis of other polyketides. Polyketide synthases (PKS) use the appropriate
CoA ester as a primer and add acetate units from malonyl-CoA and propionate units from methylmalonyl-CoA to assemble the polyketides.
Avermectin aglycons are formed by addition to the starter unit (2-methylbutyrate or isobutyrate) of 12 acyl condensations
in the order P–A–A–A–A–P–P–A–P–A–P–A (P, propionyl; A, acetyl). Within the 90-kb gene cluster for avermectin biosynthesis,
the central 65-kb segment was found to be required for aglycon biosynthesis by phenotypic analysis of strains containing deletion
or insertion mutations in this region. A complete sequence analysis of the 65-kb segment indicated that this segment encodes
avermectin PKS. The avermectin PKS genes are organized into two converging blocks of ORFs. From the results of sequencing
analysis, a feature of the two regions, aveA1/aveA2 and avea3/aveA4, is that they encode four kinds of large multifunctional polypeptides containing 55 domains which possess putative fatty
acid synthase-like activities. The avermectin PKS (AVES 1–4) appear to contain two, three, or four modules. AVES 1 and 2 contain
two and four modules, respectively, whereas AVES 3 and AVES 4 each contains three modules. The 12 modules correspond to the
12 cycles required for synthesis of the avermectin aglycon. Journal of Industrial Microbiology & Biotechnology (2001) 27, 170–176.
Received 21 September 1999/ Accepted in revised form 14 September 2000 相似文献
997.
Streptomyces linear plasmids start replication at centrally located loci, usually consisting of iterons and adjacent rep genes. Here, we identified four new replication loci from Streptomyces linear plasmids. A discontinuous locus, consisting of two genes and iterons separated by two nonessential genes, was required for replication of pRL2 in both linear and circular modes. A temperature-sensitive plasmid, pRL4, contained a replication locus, a noncoding sequence and a SAP1.35 -like gene. A telomere-adjacent locus, another noncoding sequence and SAP1.1 -like gene, was identified for replication of the large plasmid pFRL2. The replication locus of pSHK1 consisted of SCP1- rep -like genes and iterons. These results indicate an unexpected variety of components, positions and combinations of replication loci among Streptomyces linear plasmids. 相似文献
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