Rational design of a 500 m3 fermenter for erythromycin production by Saccharopolyspora erythraea / 生物工程学报

Erythromycin is a macrolide antibiotic produced by Saccharopolyspora erythraea. Its yield is greatly affected by the fermentation conditions and the bioreactor configurations. In this study, a novel scale-up method for erythromycin fermentation was developed based on computational fluid dynamics (CFD) and time constant analysis. Firstly, the dissolved oxygen (DO) was determined as a key parameter according to the physiological properties of S. erythraea cultivated in a 50 L bioreactor. It was found that the time constant of oxygen supply (tmt) in a 500 m3 bioreactor should be less than 6.25 s in order to satisfy the organism's oxygen uptake rate (OUR). Subsequently, a 500 m3 bioreactor was designed using the time constant method combined with empirical correlations. The impeller combination with one BDT8 impeller at bottom and two MSX4 impellers at upper part was determined, and then validated by numerical simulation. The results indicated that the tmt of the bioreactor (< 6.25 s) and the fluid properties, including gas hold-up, shear stress and fluid vector, met the requirements of erythromycin fermentation. Finally, the industrial production of erythromycin in the 500 m3 showed the design method was applicable in large scale fermentation.

Effect of fcl gene for butenyl-spinosyn biosynthesis and growth of Saccharopolyspora pogona / 生物工程学报

The fcl gene encodes GDP-fucose synthase, which catalyzes two-step differential isomerase and reductase reactions in the synthesis of GDP-L-fucose from GDP-D-mannose. It also participates in the biosynthesis of amino sugar and ribose sugar, and is one of the key enzymes to regulate the metabolism of sugar and nucleotides in organisms. The presence of fcl gene in Saccharopolyspora pogona was found through sequencing result of genome. The mutant S. pogona-fcl and S. pogona-Δfcl were constructed by gene engineering technology. The results showed that the gene had an effects on growth and development, protein expression and transcriptional level, insecticidal activity, and biosynthesis of butenyl-spinosyn of Saccharopolyspora pogona. The results of HPLC analysis showed that the yield of butenyl-spinosyn in S. pogona-Δfcl was 130% compared with that in S. pogona, which reduced by 25% in S. pogona-fcl. The results of determination of insecticidal activity showed that S. pogona-Δfcl had a stronger insecticidal activity against Helicoverpa armigera than that of S. pogona, while the S. pogona-fcl had a lower insecticidal activity against Helicoverpa armigera compared with S. pogona. Scanning electron microscopy (SEM) was used to observe the morphology of the mycelia. It was found that the surface of the S. pogona-Δfcl was wrinkled, and the mycelium showed a short rod shape. There was no significant difference in mycelial morphology between S. pogona-fcl and S. pogona. Aboved all showed that deletion of fcl gene in S. pogona hindered the growth and development of mycelia, but was beneficial to increase the biosynthesis of butenyl-spinosyn and improve insecticidal activity. Whereas the fcl gene over-expression was not conducive to the biosynthesis of butenyl-spinosyn and reduced their insecticidal activity. SDS-PAGE results showed that the difference of protein expression among the three strains was most obvious at 96 hours, which was identified by real-time fluorescence quantitative polymerase chain reaction, the results showed that there were significant differences of related genes in transcriptional levels among the three strains. Based on the results of the study, a network metabolic control map was constructed to analyze the effect of fcl gene on growth and the regulation pathway of butenyl-spinosyn biosynthesis, which provided an experimental basis for revealing the regulation mechanism of butenyl-spinosyn biosynthesis and related follow-up studies.

Effect of ribosome engineering on butenyl-spinosyns synthesis of Saccharopolyspora pogona / 生物工程学报

Through introducing mutations into ribosomes by obtaining spontaneous drug resistance of microorganisms, ribosome engineering technology is an effective approach to develop mutant strains that overproduce secondary metabolites. In this study, ribosome engineering was used to improve the yield of butenyl-spinosyns produced by Saccharopolyspora pogona by screening streptomycin resistant mutants. The yields of butenyl-spinosyns were then analyzed and compared with the parent strain. Among the mutants, S13 displayed the greatest increase in the yield of butenyl-spinosyns, which was 1.79 fold higher than that in the parent strain. Further analysis of the metabolite profile of S13 by mass spectrometry lead to the discovery of Spinosyn α1, which was absent from the parent strain. DNA sequencing showed that there existed two point mutations in the conserved regions of rpsL gene which encodes ribosomal protein S12 in S13. The mutations occurred a C to A and a C to T transversion mutations occurred at nucleotide pair 314 and 320 respectively, which resulted in the mutations of Proline (105) to Gultamine and Alanine (107) to Valine. It also demonstrated that S13 exhibited genetic stability even after five passages.

Promoter detection and transcriptional analysis of the spinosad biosynthetic gene cluster / 生物工程学报

Spinosad represents a new class of insecticides produced by Saccharopolyspora spinosa. To understand the transcription of the spinosad biosynthetic gene cluster, two promoter detection plasmids based on different reporter genes were constructed and used to detect 9 promoters in the spinosad biosynthetic gene cluster. In addition, the temporal transcriptional profiles of the corresponding genes controlled by the 9 promoters, together with 4 genes outside of the spinosad cluster but are required for the synthesis of sugars in spinosad, were examined by real-time PCR. The results indicate that the 9 spinosad biosynthetic genes were highly expressed at the stationary phase, which coincides with the accumulation of spinosad in the fermentation broth. Of particular note is that the transcription of the 4 sugar synthetic genes showed higher level at the exponential phase, suggesting the expression of sugar synthetic genes is not correlated with the spinosad synthetic genes. The data suggest that spinosad biosynthesis could be improved by engineering the expression pattern of the sugar synthetic genes that lie outside the spinosad gene cluster.

Glycosyl isomerization based on the biosynthesis of natural-product sugar from microorganism / 药学学报

Glycosylation, one of the most common and important reactions in biological systems, results in diverse functions and is often found in biologically active small-molecule natural products produced by microorganisms. Furthermore, sugar moieties are generally critical for their activities. Alternating the sugar structures thus provides the potentials for enhancing the biological activities of natural products, which evokes researchers to study the sugar biosynthetic machinery and its application in the modification of sugar moieties with an aim of generating unnaturally glycosylated natural product drugs with better activities. This review will briefly outline current studies on sugar biosynthesis and glycosyltransferase, with a few selected experiments designed to alter natural-product sugar structures.

Larvicidal and pupicidal activity of spinosad against the malarial vector Anopheles stephensi

OBJECTIVE@#To investigate the larvicidal and pupicidal activity of spinosad against Anopheles stephensi Listen.@*METHODS@#Spinosad from the actinomycete, Saccharopolyspora spinosa was tested against Anopheles stephensi at different concentrations (0.01, 0.02, 0.04, 0.06 and 0.08 ppm.), and against first to fourth instar larvae and pupae.@*RESULTS@#The larval mortality ranged from 36.1±1.7 in (0.01 ppm) to 79.3±1.8 (0.08 ppm) the first instar larva. The LC(50) and LC(90) values of first, second, third and fourth instar larva were 0.001, 0.031, 0.034, 0.036 and 0.0113, 0.102, 0.111, 0.113, respectively. The pupal mortality ranged from 33.0±2.0 (0.01 ppm) to 80.0±0.9 (0.08 ppm). The LC(50) and LC(90) values were 0.028 and 0.1020, respectively. The reduction percentage of Anopheles larvae was 82.7%, 91.4% and 96.0% after 24, 48, 72 hours, respectively, while more than 80% reduction was observed after 3 weeks.@*CONCLUSIONS@#In the present study spinosad effectively caused mortality of mosquito larvae in both the laboratory and field trial. It is predicted that spinosad is likely to be an effective larvicide for treatment of mosquito breeding sites.

Fcgamma Receptors Modulate Pulmonary Inflammation by Activating Innate Immune Cells in Murine Hypersensitivity Pneumonitis

BACKGROUND: Hypersensitivity pneumonitis (HP) is an interstitial lung disease that develops following repeated exposure to inhaled particulate antigens. The family of Fcgamma receptors (FcgammaRs) has emerged as central regulators for modulating both pro-and anti-inflammatory responses. However, the role of FcgammaRs in the development of HP has not been investigated yet. METHODS: To explore the functional roles of FcgammaRs in HP, FcgammaR-/- and B6 mice were challenged with Saccharopolyspora rectivirgula (SR) antigen intranasally, and compared these mice in terms of the histological change, infiltrated immune cells in BALF and in vitro immune responses. RESULTS: FcgammaR-/- mice exhibited attenuation of HP in terms of histological alterations, and reduced numbers of neutrophils and macrophages in and the increased CD4:CD8 ratio of bronchoalveolar lavage fluid. The lungs of FcgammaR-/- mice showed high production of Th2 cytokine such as IL-4 and slightly low production of Th1 cytokine, INF-gamma compared to those of B6 mice. However, SR-specific adaptive immune responses of FcgammaR-/- mice were similar to those of B6 mice. CONCLUSION: These results demonstrate that activating Fcgamma receptors play an important role in activating neutrophils and macrophages in pulmonary inflammation and inducing Th1 differentiation by regulating cytokine expression in SR-induced HP.

Conditions for protoplast preparation of spinosyn-producing strain and the physiological properties of protoplast-regenerated strains / 生物工程学报

To improve spinosyn-producing strain and enhance spinosyns yield, we studied the effects of glycin concentration and the operational time, temperature and lysozyme concentration on protoplast preparation of Saccharopolyspora spinosa SP06081. We also studied different regeneration media and osmotic stabilizing agents. In addition, we compared the change of morphology and spinosyns yield of the regenerated strains. The results showed that the Saccharopolyspora spinosa SP06081 protoplast yield was the highest under these conditions: the collected mycelium from SP06081 grown in Tryptic Soy Broth (TSB) medium with 0.2% glycin for 48 h was treated by 0.1 mg/mL lysozyme at 28 degrees C for 20 min, then plated on the R2YE medium with sucrose as osmotic stabilizer, the number of regeneration protoplast was up to 10(8)/mL. The protoplast-regenerated strains exhibited changes in morphology and antibiotic production, 29.3% protoplast-regenerated strains was characterized by loose mycelium and abundant broken branches as did their parent. Among them, 58.2% strains presented the trend to positive variation in spinosad yield, with the highest spinosad yield of up to 582.0 mg/L, 85.6% higher than that of their parent. There is significant correlation between the morphological differentiation and antibiotic yield of the protoplast-regenerated strains from spinosyn-producing strain.

IL-4-deficient Mice Aggravate Hypersensitivity Pneumonitis

BACKGROUND: Hypersensitivity pneumonitis (HP) comprises a group of lung diseases resulting from repeated inhalation of various antigens such as Saccharopolyspora rectivirgula (SR). HP is categorized as a Th1 disease. Therefore, it has been suggested that IL-4, Th2 type cytokine, plays a protective role in the development of HP. However, the functional role of IL-4 in HP has not been extensively investigated in vivo. Therefore, we investigated the functional role of IL-4 in HP using IL-4 knockout (KO) mice. METHODS: HP was induced by repeated exposure to SR in C57BL/6 (B6) and IL-4 KO (C57BL/6 background) mice. RESULTS: IL-4 KO mice aggravated HP in terms of histological alteration, SR-specific immune responses, and inflammatory cell infiltration in the lungs compared with B6 mice. IL-4 KO mice produced high levels of IFN-gamma, TGF-beta and TNF-alpha in the lungs, whereas B6 mice showed the enhanced production of IL-4. Moreover, chemokines such as MIP-1alpha, MCP-1, and RANTES were highly expressed in IL-4 KO mice. IFN-gamma-secreting CD4, CD8 T cells, and neutrophils were enhanced in the bronchoalveolar lavage fluid (BALF) of IL-4 KO mice than those of B6 mice. The administration of recombinant(r) IL-4 restored these immunologic parameters in IL-4 KO mice. CONCLUSION: These results indicate that IL-4 plays a suppressive role in SR-induced HP by attenuating Th1-dominant immune responses.

Study on relationship between length of homologous sequences and chromosomic recombination rate in Saccharopolyspora erythraea / 生物工程学报

In order to study the relationship between lengths of homologous fragments and chromsomic recombination rate in Saccharopolyspora erythraea, three homologous sequences, with mutant loci and different flanking sequences, (26bp + 27bp), (500bp + 576bp) and (1908bp + 1749bp), were synthesized by chemical reaction or PCR amplification, and cloned into pWHM3 to construct homologous recombination plasmids, pWHM1113, pWHM1116 and pWHM1119. When the plasmids were transformed into protoplast of Saccharopolyspora erythraea A226 under PEG mediated, on an average 30, 69 and 170 transformants grew on each plate for the three plasmids respectively, but chromosomic integration frequency were 0, 2% and 19% among corresponding transformants. Both pWHM1116 and pWHM1119 could take double crossover recombination, and exchange the mutant loci in the chromosome. It was concluded that when the flanking sequences were equal or more than (500bp + 576bp), they could take effective single and double recombination with Saccharopolyspora erythraea chromosome.

Construction of Saccharopolyspora erythraea M synthesizing a novel ketolide 3-deoxy-3-oxo-erythronolide B / 生物工程学报

Genetic engineering on macrolide antibiotics was a new field in recent years and more than 100 novel polyketides had been produced until then. Using genomic DNA of S. erythraea A226 as a template, about 3.2 kb DNA fragment without KR6 domain was amplified by overlapping PCR technique and cloned into pWHM3 carrier, which resulted in the construction of homologous recombinant plasmid pWHM2201. Plasmid pWHM2201 was introduced into protoplasts of S. erythraea A226 by PEG-mediated transformation and integrated into the gene locus for erythromycin biosynthesis. After integrants grew for two generations on R3M media without Tsr, they were protoplasted and grown on R3M plates. By PCR identification, 8 mutants without KR6 domain were selected out and named S. erythraea M(1-8). With the identification of mass spectrometry, it was proved that S. erythraea M1 synthesized a novel ketolide compound 3-deoxy-3-oxo-erythronolide B.

A chemically defined medium for production of actinomycin D by Streptomyces parvulus / A chemically defined medium for production of actinomycin D by Streptomyces parvulus

Um meio quimicamente definido composto de D (+) FRUTOSE, L (-) treonina, K2HPO4, MgSO4.7H2O, ZnSO47H2O, CaCl2.2H2o, FeSO4.7H2O e água deionizada, foi desenvolvido para maximizar a síntese de actinomicina D pelo Streptomyces parvulus DAUFPE3124. o meio proposto resultou numa concentraçäo antibiótica máxima de 133mg/L enquanto que no meio inicial a produçäo antibiótica foi baixa, näo ultrapassando 43mg/L

Isolation and identification of galactosyl glucosyl diglyceride from saccharopolyspora hirsuta

The major glycolipid component from saccharopolyspora hirsute [N626] was isolated and investigated. Acid hydrolysis of the isolated lipid yielded, glucose, galactose, glycerol and a mixture of fatty acids. Analysis of the latter by gaschromatography showed that they consisted largely of palmitic, stearic and oleic acids