Rheological studies on Streptomyces fradiae ScF-5 in submerged fermentation

Studies on the rheology of Streptomyces fradiae ScF-5 in a 10-dm³ submerged fermenter for the production of intracellular glucose isomerase revealed that the apparent viscosity of the broth increased with increase in cell density up to 24 h and then declined while the density of the broth remained constant. The plot of shear stress versus shear rate at various fermentation periods showed the applicability of the Casson model. The yield stress and consistency index were found to increase gradually then decrease subsequently. In contrast, the flow behaviour index was less than unity and remained constant throughout the fermentation. The results contrast with the findings of other workers on the Newtonian and non-Newtonian character of fermentation broths and the applicability of the power law model to such systems.     

Metabolomics Reveals a “Trimeric” γ-Actinorhodin from Streptomyces coelicolor M145

Streptomyces coelicolor is a prolific producer of natural products and serves as a model organism for their study. It produces several pigmented antibiotics, the best-studied of which are the actinorhodins. We used a combination of liquid chromatography-mass spectrometry (LC–MS) and computational tools used for annotating the detected species (e. g., spectral matching, in-silico predictors, molecular networking) to identify putative new actinorhodin analogs. These studies led to the discovery of the first trimeric benzoisochromanequinone, θ-actinorhodin ( 1 ). Further metabolomics analysis revealed that the relative amounts of shunt products produced were similar between the two growth conditions explored. This suggests that, while substantially different products were being produced, the biosynthetic gene clusters were similarly active. Overall, this work describes the discovery of the first trimeric benzoisochromanequinone and explores the biosynthetic processes that might lead to its production by metabolomics analysis of relevant intermediates.     

Production and characterization of glycolipid biosurfactant from Streptomyces enissocaesilis HRB1 and its evaluation for biomedical and bioremediation applications

The aim of this investigation is to produce and characterize biosurfactant from Streptomyces sp. HRB1 and to evaluate its biomedical and bioremediation potential. Biosurfactant producing property of Streptomyces sp. HRB1 isolated from petroleum contaminated soil was confirmed by hemolytic and oil spread assays. Based on the results of FT-IR spectral and GC–MS analysis, the biosurfactant was confirmed as glycolipid type. Biosurfactant from Streptomyces sp. HRB1 exhibited 71% inhibition against Pseudomonas aeruginosa biofilm formation, 77.33% quorum sensing inhibition property against Chromobacterium violeceum MTCC 2656, more than 80% inhibition in antioxidant assays namely, DPPH, ABTS, and metal chelation, promising anti-proliferative activity against leukemia and myeloma cells with low IC₅₀ values, 96% decolorization of malachite green within 48 h of reaction time, and minimal toxicity against normal cell lines in dose-dependent manner. The taxonomic position of the potential strain HRB1 was further confirmed as Streptomyces enissocaesilis HRB1 based on their phenotypic and molecular characteristics. To conclude, Streptomyces enissocaesilis HRB1 isolated from petroleum-contaminated soil is a promising source for low-cost production of glycolipid biosurfactant with potential biomedical and environmental applications such as antiphytofungal, antibiofilm, anti-quorum sensing, antioxidant, anticancer, and dye degradation properties.     

肉桂皮提取残渣生物降解制备肉桂酰胺

筛选到能使肉桂皮提取残渣降解生成肉桂酰胺的菌株CG19,该菌株被鉴定为链霉菌(Streptomyces sp.)。进行了生物降解转化合成研究,用红外光谱仪、气相色谱-质谱联用仪、高效液相色谱仪对产物进行了表征。优化了生物降解条件,优化条件为:ρ(肉桂渣)=8.0 g/L,ρ(湿菌体)=40 g/L,反应体系的初始pH=5.0,30℃反应3 d,在该条件下肉桂酰胺的收率达0.32%。     

普那霉素发酵与吸附分离耦合过程动力学

根据S.pristinaespiralis E-71普那霉素发酵过程的代谢特性提出了一个针对产物合成期的普那霉素合成动力学方程,结合液膜-孔扩散理论,建立了描述2.5L通气搅拌发酵罐中JD-1大孔吸附树脂吸附分离原位耦合发酵过程的动力学模型,并获得产物生成速率常数、产物抑制常数及液膜传质和孔内扩散系数。结果表明该发酵-吸附耦合过程动力学模型能较好地描述这一原位分离耦合发酵生产普纳霉素过程。在此基础上,考察了树脂添加量及树脂半径对原位分离耦合发酵过程的影响,结果表明添加JD-1树脂能有效移走发酵液主体相中高达90%的普那霉素,且原位分离效果随树脂粒径减小而增强,在一定范围内随树脂添加量的增加而增强,当添加70g.L-1半径为0.195mm的树脂时,普纳霉素产量达到1.01g.L-1,其中被树脂吸附的高于95%。     

氮源对利迪链菌素生产及相关次级代谢物分布的影响

The effects of nitrogen sources on streptolydigin production and distribution of secondary metabolites were investigated for flask cultured S.lydicus AS 4.2501.When peptone,asparamide,and glutamic acid were ex- amined as the nitrogen source,respectively,liquid chromatography-mass spectrometry（LC-MS）and photodiode array（PDA）analyses revealed the formation of two analogues of streptolydigin in the fermentation broth.When soybean meal was used as the source of nitrogen,three analogues of streptolydigin were detected.The use of am- monium sulfate as a source of nitrogen resulted in a lower pH value of the fermentation system,thus inhibiting streptolydigin biosynthesis and changing the metabolic profiling.Among the nitrogen sources that were made use of,glutamic acid was most favorable to the formation of streptolydigin.Simultaneously,this study also showed that the changing nitrogen sources resulted in altering the production and relative ratios of streptolydigin and its analogues.     

Enhancing the sporulation of <Emphasis Type="Italic">Streptomyces kasugaensis</Emphasis> by culture optimization

To be an effective microbial biocide, Streptomyces kasugaensis should be converted into spore during cultivation process for successful long-term storage. By statistical design methods, culture conditions including medium components and operating parameters were optimized and more than 100 times increase in spore yield was achieved. Addition of spent culture fluid (100 ppm), EDTA (30 ppm), mycophenolic acid (32 ppm) with combination of pH up-shock (5.5 to 8.5) increased total viable cell and spore conversion rate, resulting in 1.6×10⁷ (spore/mL) in 5 days of culture in a fermenter. This result provides a practical method for obtaining high spore number for commercial production of Streptomyces kasugaensis as a microbial pesticide.     

New Angucycline Glycosides from a Marine-Derived Bacterium Streptomyces ardesiacus

Chemical investigation of the ethyl acetate extract from the culture broth of the marine-derived actinobacterium Streptomyces ardesiacus 156VN-095 led to the isolation of three hitherto undescribed angucycline glycosides, including urdamycins W and X (1 and 2) and grincamycin U (9), as well as their seven known congeners. The structures of the new compounds were elucidated by means of spectroscopic methods (HRESIMS, 1D and 2 D NMR) and comparison of their experimental data with literature values. Compounds 1–3 and 9 were evaluated for their anti-Gram-positive bacterial effect and cytotoxicity against six cancer cell lines. Compound 1 displayed significant cytotoxicity against all the tested cell lines with GI₅₀ values of 0.019–0.104 µM. Collectively, these findings highlight the potential of angucycline glycosides as leading structures for the development of new anti-cancer drugs.     

含新农抗702的HP-10树脂解吸及再生工艺

为探索含新农抗702的HP-10大孔树脂的解吸及树脂再生的适宜条件,采用静态、动态方式对树脂进行洗脱;采用生物学法(管碟法)对树脂洗脱液中的残留物进行检测。结果表明,静态解吸时乙醇能够使含新农抗702的大孔HP-10树脂一次性解吸率达到90%;动态解吸时洗脱峰比较集中便于后续浓缩;通过比较再生前后树脂吸附的吸附性能发现,树脂基本再生完全,且再生方法简便,可使树脂重新获得吸附性能,故可反复使用,达到节约原料的目的。