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Currently, biomanufacturing technology and industry are receiving worldwide attention. However, there are still great challenges on bioprocess optimization and scale-up, including: lacing the process detection methods, which makes it difficult to meet the requirement of monitoring of key indicators and parameters; poor understanding of cell metabolism, which arouses problems to rationally achieve process optimization and regulation; the reactor environment is very different across the scales, resulting in low efficiency of stepwise scale-up. Considering the above key issues that need to be resolved, here we summarize the key technological innovations of the whole chain of fermentation process, i.e., real-time detection-dynamic regulation-rational scale-up, through case analysis. In the future, bioprocess design will be guided by a full lifecycle in-silico model integrating cellular physiology (spatiotemporal multiscale metabolic models) and fluid dynamics (CFD models). This will promote computer-aided design and development, accelerate the realization of large-scale intelligent production and serve to open a new era of green biomanufacturing.
Subject(s)
Bioreactors , Computer Simulation , Fermentation , HydrodynamicsABSTRACT
PURPOSE@#To assess the usefulness of an ultrasound (US)-guided peritoneal biopsy for the solitary peritoneal thickening visualized as only infiltrated fat on a computed tomography (CT) scan.@*MATERIALS AND METHODS@#This retrospective study included 36 patients (16 males, 20 females; mean age, 51.7 years) who underwent a US-guided biopsy for the solitary peritoneal thickening of unknown cause visualized as only infiltrated fat without an apparent mass formation on a CT scan. The rate of the specific histopathological diagnosis and accuracy for the diagnosis of malignant disease was assessed.@*RESULTS@#The procedure was technically successful with the acquisition of an adequate amount of the specimen for microscopic examination from all patients. A specific histopathological diagnosis was made in 31/36 patients (86.1%): peritoneal carcinomatosis in 15/31 (48.4%), tuberculous peritonitis in 15/31 (48.4%) and panniculitis in 1/31 (3.2%). A non-specific histopathological diagnosis was made in 5/36 (13.9%): chronic inflammation in 4/5 (80%) and mesothelial hyperplasia in 1/5 (20%). The procedure showed sensitivity of 83.3%, with a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 85.7%, and an accuracy rate of 86.1% for the diagnosis of malignant diseases.@*CONCLUSION@#The US-guided peritoneal biopsy is a fairly accurate diagnostic procedure for the peritoneal thickening visualized as only infiltrated fat on a CT scan, and it can be used before performing laparoscopic or an open biopsy.
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A method for measuring 13C isotopic abundance of intracellular metabolites of Saccharopolysporaerythraea by ultra-high performance liquid chromatography (UPLC)-triple quadrupole mass spectrometry was established.First, the chromatographic conditions of UPLC were optimized, and then the MS conditions such as unique tube lens voltage, collision energy, and ion pair were optimized.On the bases of length of the parent and daughter ions carbon chains and whether the daughter ions contain 13C atoms, the one-to-one method, one-to-many method and SIM method were established for measuring 13C isotopic abundance.Then these methods were used to measure naturally labeled intracellular metabolite standards and 13C labeled samples, and according to the gap between the experimental value and the theoretical value, the best method was established for each metabolite of different characteristics.The results showed that one-to-one method was most effective for measuring the metabolites of daughter ions not containing 13C atoms represented by sugar phosphates, one-to-many method was the best for measuring the metabolites of both parent and daughter ions containing 13C short carbon chains represented by carboxylic acids, SIM method could play a role in measuring the metabolites of both parent and daughter ions containing 13C long carbon chains represented by coenzyme A.This method had a good measurement precision and could be applied to the measurement of Saccharopolysporaerythraea intracellular metabolites, which contributed to the consequent study of metabolic mechanism and the efficient expression of erythromycin.
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A rapid and accurate determination method of lipids in microalgae plays a significant role in an efficient breeding process for high-lipid production of microalgae. Using low field nuclear magnetic resonance (LF-NMR), we developed a direct quantitative method for cellular lipids in Chlorella protothecoides cells. The LF-NMR signal had a linear relationship with the lipid content in the microalgae cells for both dry cell samples and algal broth samples (R2 > 0.99). These results indicated that we could use this method for accurate determination of microalgal lipids. Although LF-NMR is a rapid and easy lipid determination method in comparison to conventional methods, low efficiency would limit its application in high throughput screening. Therefore, we developed a novel combined high throughput screening method for high-lipid content mutants of C. protothecoides. Namely, we initially applied Nile red staining method for semi-quantification of lipid in the pre-screening process, and following with LF-NMR method for accurate lipid determination in re-screening process. Finally, we adopted this novel screening method in the breeding process of high-lipid content heterotrophic cells of C. protothecoides. From 3 098 mutated strains 108 high-lipid content strains were selected through pre-screening process, and then 9 mutants with high-lipid production were obtained in the re-screening process. In a consequence, with heterotrophical cultivation of 168 h, the lipid concentration could reach 5 g/L, and the highest lipid content exceeded 20% (W/W), which was almost two-fold to that of the wild strain. All these results demonstrated that the novel breeding process was reliable and feasible for improving the screening efficiency.
Subject(s)
Chlorophyta , Chemistry , Heterotrophic Processes , High-Throughput Screening Assays , Lipids , Magnetic Resonance Spectroscopy , Microalgae , Chemistry , Staining and LabelingABSTRACT
Filamentous fungi are widely used in industrial fermentation. Particular fungal morphology acts as a critical index for a successful fermentation. To break the bottleneck of morphological analysis, we have developed a reliable method for fungal morphological analysis. By this method, we can prepare hundreds of pellet samples simultaneously and obtain quantitative morphological information at large scale quickly. This method can largely increase the accuracy and reliability of morphological analysis result. Based on that, the studies of Aspergillus niger morphology under different oxygen supply conditions and shear rate conditions were carried out. As a result, the morphological responding patterns of A. niger morphology to these conditions were quantitatively demonstrated, which laid a solid foundation for the further scale-up.
Subject(s)
Aspergillus niger , Cell Biology , Fermentation , Industrial Microbiology , Reproducibility of ResultsABSTRACT
Carbon-limited continuous culture was used to study the relationship between the growth of Aspergillus niger and the production of glucoamylase. The result showed that when the specific growth rate was lower than 0.068 h(-1), the production of glucoamylase was growth-associated, when the specific growth rate was higher than 0.068 h(-1), the production of glucoamylase was not growth-associated. Based on the result of continuous culture, the Monod dynamics model of glucose consumption of A. niger was constructed, Combining Herbert-Pirt equation of glucose and oxygen consumption with Luedeking-Piret equation of enzyme production, the black-box model of Aspergillus niger for enzyme production was established. The exponential fed-batch culture was designed to control the specific growth rate at 0.05 h(-1) by using this model and the highest yield for glucoamylase production by A. niger reached 0.127 g glucoamylase/g glucose. The black-box model constructed in this study successfully described the glucoamylase production by A. niger and the result of the model fitted the measured value well. The black-box model could guide the design and optimization of glucoamylase production by A. niger.
Subject(s)
Aspergillus niger , Metabolism , Batch Cell Culture Techniques , Carbon , Culture Media , Glucan 1,4-alpha-Glucosidase , Glucose , Industrial Microbiology , Methods , OxygenABSTRACT
The aim of this study is to develop a synthetic medium suitable for 13C metabolic flux analysis (13C-MFA) of Streptomyces rimosus. The cell growth rate and oxytetracycline production by S. rimosus M4018 were compared when M4018 cells were growth on the optimized chemically defined media with organic nitrogen sources or inorganic nitrogen sources. First, a synthetic medium contained KNO3 as the main nitrogen source was screened, then optimized by a response surface method. Using this new medium, the oxytetracycline yield was increased from 75.2 to 145.6 mg/L. Furthermore, based on the 13C-MFA, we identified that Entner-Doudoroff pathway does not exist in S. rimosus cells cultured in a chemically defined medium with feed of 100% 1-13C labeled glucose. This study is helpful for subsequent 13C-MFA application of S. rimosus.
Subject(s)
Carbon Isotopes , Culture Media , Chemistry , Metabolic Flux Analysis , Nitrogen , Chemistry , Oxytetracycline , Streptomyces rimosus , MetabolismABSTRACT
13 C isotopic abundance of intracellular free amino acid with a characteristic of fast- turnover can quickly reflect changes in intracellular metabolic state. But the concentration of intracellular free amino acid is low, the existed 13 C isotope detection method based on GC-MS can not satisfy the requirement with full scan mode. In this study, the selected ion monitoring method was used to detect accuracy higher likelihood of analysis of 13 C isotopic abundance of free intracellular amino acid. First, in the full scan mode we analyzed of the fracture law of different amino acids, found the feature corresponding to each amino acid fragments, and established 16 kinds of free intracellular amino acids characteristic fragment library. Then using this characteristic fragment library, only specific m/z signal was detected in sample analysis, which realized the selected ion monitoring and improved the quality of signal. The results of amino acid standards showed that the signal-to-noise ratio, measurement precision and accuracy were improved by 17, 2. 0 and 3. 8 times compared with the full scan mode. In the analysis of coenzyme Q10 producing strains of samples, this method was successfully used to detect isotopic abundance of 8 kinds of free intracellular amino acids. This method plays an important role in the detection of 13 C isotopic abundance of the intracellular free amino acid in cell metabolism research.
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We observed the influence of methanol concentration on purification recovery of recombinant human consensus interferon-a (cIFN) produced by Pichia pastoris. Fermentations controlled at 0.75% (W/V) methanol showed a 24% increase in clFN expression compared to using 0.25% methanol. However, the purification recovery rate of cIFN at 0.25% methanol was 3.75-fold higher than that at 0.75% methanol. To seek the reason, we analyzed the stability of clFN by SDS-PAGE and Native-PAGE as well as Western blotting. The electrophoresis results revealed that cIFN formed a lot of aggregates in media when the induction was controlled at 0.75% methanol, and two different aggregate forms were found: disulfide bond covalent aggregates and non-covalent aggregates. However, these aggregates almost disappeared when the methanol concentration was controlled at 0.25%, at the same time, cIFN bioactivity of supernatant increased almost 4.48-fold. Finally, 0.73g monomer cIFN was obtained after purification from 1 liter supernatant at 0.25% methanol induction, showed a 2.84-fold increase compare to the induction at 0.75% methanol.
Subject(s)
Humans , Antiviral Agents , Fermentation , Interferon-alpha , Genetics , Methanol , Pichia , Genetics , Metabolism , Recombinant Proteins , GeneticsABSTRACT
To investigate the energy utilization efficiency of Synechococcus sp. PCC7942 under mixotrophic conditions, we studied its growth characteristics in mixotrophic cultures with glucose and acetic acid respectively and discussed the carbon metabolism and energy utilization based on metabolic flux analysis. Results showed that both glucose and acetate could better enhance the growth of Synechococcus sp. PCC7942, and the latter was more effective. The metabolic flux through glycolytic pathway in mixotrophic cultures was stimulated by glucose whereas depressed by acetate, while the flux through the tricarboxylic acid cycle increased in both cases. Under mixotrophic conditions, glucose makes more significant impact on the diminishment of photochemical efficiency of Synechococcus sp. PCC7942. Although the contribution of light energy was smaller, the cell yields based on total energy in mixotrophic cultures were higher comparing with photoautotrophic culture. The energy conversion efficiencies based on ATP synthesis in photoautotrophic culture, mixotrophic cultures with glucose and with acetate were evaluated to be 6.81%, 7.43% and 8.77%, respectively.
Subject(s)
Acetic Acid , Pharmacology , Adenosine Triphosphate , Carbon , Metabolism , Culture Media , Culture Techniques , Methods , Energy Metabolism , Glucose , Pharmacology , Synechococcus , Classification , MetabolismABSTRACT
Objective To investigate the status of genotype of the KPC(Klebsiella pneumoniae carbapenemase)-encoding genes in Pan-resistant K. Pneumoniae, isolated from the 98th Hospital of People' s Liberation Army, Huzhou district, Zhejiang province, China. Methods 19 strains of Pan-resistant K. Pneumoniae were isolated from the inpatients between November, 2008 and July,2009. Phenotypic confirmatory test for suspected carbapenemases production were carried out by Modified Hodge test. Carbapenemase gene of blaKPC was analyzed by PCR and verified by DNA sequencing. Results In 19 strains of K. Pneumoniae, the positive rates of Modified Hodge test and gene of blaKPC were both 100.0%. These genes all belonged to blaKPC-2 subtype confirmed by nucleotide sequence analysis. Among them, the blaKPC-2 gene sequence of the HZ001 strain (its original serial number was HZ9871 ) had been registered in GenBank (GenBank Accession Number: GU086225).Conclusion All of the Pan-resistant K. Pneumoniae isolated from the inpatients harbored blaKPC-2 type carbapenemases gene and causing an outbreak in a hospital. Carbapenemases that producing type KPC-2 might be the major reason which causing the resistance to Carbapenems antibiotics.
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Metabolic flux analysis is a very powerful tool to understand CO2 fixation and light energy utilization of microalgae during photoautotrophic cultivation. A comprehensive network structure for the autotrophic growth of Synechococcus sp. PCC7942 was proposed, and the carbon and energetic metabolism under different incident light intensity was investigated based on metabolic flux analysis in this paper. These results showed that CO2 fixation was the main energy and reducing potential trap which accounted for 85% and 70% of the total energy and reducing potential consumption respectively. We also found that the cell yield and the maximum cell yield based on ATP synthesis were maintained 2.80 g/mol and 2.97 g/mol respectively under the appointed incident intensity. But the cell yield on absorbed light energy their corresponding energy conversion efficiency were descended with the increasing of incident intensity.
Subject(s)
Carbon , Metabolism , Carbon Cycle , Carbon Dioxide , Metabolism , Cell Culture Techniques , Energy Metabolism , Light , Photochemical Processes , Synechococcus , MetabolismABSTRACT
Objective To investigate the presence and genetic background of 16S rRNA methylase gene and Aminoglycoside modifying enzymes(AMEs) genes in Klebsiella pneumoniae isolated from the People's Liberation Army 98th HospitaI,Huzhou district,Zhejiang province,China.Methods 25 strains of Klebsiella pneumoniae were isolated from the inpatienta between September,2005 and April,2006.6 kinds of 16S rRNA methylase gene (including armA,rmtA,rmtB,rmtC,rmtD and npmA ),6 kinds of AMEs genes [ including aac (3)-Ⅰ,sac (3)-Ⅱ,sac (6')-Ⅰ,aac (6')-Ⅱ,ant (3")-Ⅰand ant(2")-Ⅰ],intI1,intI2,intI3,mercuric reductase gene merA (merA gene were the collective genetic markers of transposona of Tn21 and Tn501 ) and tnpA ( tnpA gene were the collective genetic markers of transposons of Tn1,Tn2,Tn3 and Tn1000) were analyzed by PCR and verificated by DNA sequencing.Results In 25 strains of Klebsiella pneumoniae,the positive rate of genes of rmtB,sac (3)-Ⅱ,sac (6')-Ⅰ,ant(3")-Ⅰ and intI1 were 60.0%(15/25),4.0%(1/25),48.0%(12/25),60.0%(15/25) and 96.0%(24/25),respectively.The rest 12 kinds of genes were all tested negative.The total positive rate of 6 kinds of AMEs gene was 84.0%(21/25).Conclusion There were very high positive rate on both genes of rmtB and AMEs genotypes in Klebsiella pneumoniae isolated from inpatients,and this was the first report of the emergence of 16S rRNA methylase gene rmtB in Klebsiella pneumoniae identified in Zhejiang province,China.
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Immobilized penicillin acylase was used for bioconversion of penicillin PG into 6-APA in aqueous two-phase systems consisting of a light-sensitive polymer PNBC and a pH-sensitive polymer PADB. Partition coefficients of 6-APA was found to be about 5.78 in the presence of 1% NaCl. Enzyme kinetics showed that the reaction reached equilibrium at roughly 7 h. The 6-APA mole yields were 85.3% (pH 7.8, 20 degrees C), with about 20% increment as compared with the reaction of single aqueous phase buffer. The partition coefficient of PG (Na) varied scarcely, while that of the product, 6-APA and phenylacetic acid (PA) significantly varied due to Donnan effect of the phase systems and hydrophobicity of the products. The variation of the partition coefficients of the products also affected the bioconversion yield of the products. In the aqueous two-phase systems, the substrate, PG, the products of 6-APA and PA were biased in the top phase, while immobilized penicillin acylase at completely partitioned at the bottom. The substrate and PG entered the bottom phase, where it was catalyzed into 6-APA and PA and entered the top phase. Inhibition of the substrate and products was removed to result in improvement of the product yield, and the immobilized enzyme showed higher efficiency than the immobilized cells and occupied smaller volume. Compared with the free enzyme, immobilized enzyme had greater stability, longer life-time, and was completely partitioned in the bottom phase and recycle. Bioconversion in two-phase systems using immobilized penicillin acylase showed outstanding advantage. The light-sensitive copolymer forming aqueous two-phase systems could be recovered by laser radiation at 488 nm or filtered 450 nm light, while pH-sensitive polymer PADB could be recovered at the isoelectric point (pH 4.1). The recovery of the two copolymers was between 95% and 99%.
Subject(s)
Catalysis , Enzymes, Immobilized , Metabolism , Hydrogen-Ion Concentration , Kinetics , Penicillanic Acid , Chemistry , Metabolism , Penicillin Amidase , Metabolism , Penicillin G , Chemistry , Metabolism , Phase Transition , Polymers , Chemistry , Substrate SpecificityABSTRACT
<p><b>OBJECTIVE</b>To study the activities of the key enzymes in reteplase production by Pichia pastoris.</p><p><b>METHODS</b>In shaking flasks, a series of samples were maintained after methanol induction. The cells were sonicated to prepare cell-free suspensions, in which the activities of AOX, FAD, PDC, G-6-PD, ID, alpha-KGD and SD were measured.</p><p><b>RESULTS</b>The specific activity of AOX increased during the initial 6 h, reaching the maximum of 44.5 U/mg protein. The activity decreased quickly between 6 and 24 h, followed by increment in the following 24 h and decreased afterwards. The specific activity of FAD increased gradually in the initial 48 h and then decreased, with the peak level of 6.72 U/mg protein occurred at 48 h. The specific activity of G-6-PD increased at in 2-6 h and 24-48 h, but decreased in 6-24 h and after 48 h. The specific activity of PDC decreased during the initial 6 h and increased slowed afterwards. The specific activities of ID, alpha-KGD and SD all showed a rapid decrease in the initial 6 h and a slow decrease in 6-24 h. After 24 h, the activity of ID continued to decrease, but the other two increased in the following 24 h and then decreased, reaching the maximum at 48 h.</p><p><b>CONCLUSIONS</b>According to the changes of these enzyme activities, the whole induction phase can be divided into 4 stages: the methanol-adaptive period in the initial 6 h, the fast growth period between 6 and 24 h, the product accumulation period in 24-48 h and the metabolism lag period in 48-72 h. In the methanol-adaptive period, complete oxidation of methanol is the dominant pathway. But in the following two stages, the metabolic pathway shifts towards glycolysis and TCA cycle.</p>
Subject(s)
Alcohol Oxidoreductases , Metabolism , Fermentation , Genetic Vectors , Glucosephosphate Dehydrogenase , Metabolism , Methanol , Pharmacology , Pichia , Genetics , Metabolism , Recombinant Proteins , Genetics , Metabolism , Tissue Plasminogen Activator , Genetics , MetabolismABSTRACT
Objective To investigate the 16S rRNA methylase genes and Aminoglycoside modifying enzymes(AMEs)genes in Enterobacter cloacae isolated from the People's Liberation Army 98th Hospital,Huzhou district,Zhejiang province,China.Methods 40 strains of Enterobacter cloacae were isolated from the inpatients between September,2003 and November,2004.5 kinds of 16S rRNA methylase gene (including armA,rmtA,rmtB,rmtC and rmtD)and 9 kinds of AMEs gene[including aac(3)-Ⅰ,aac(3)-Ⅱ,aac(3)-Ⅲ,aac(3)-Ⅳ,aac(6')-Ⅰ b,aac(6')-Ⅱ,ant(3'')-Ⅰ,ant(2'')-Ⅰ and aph(3')-Ⅵ]were analyzed by PCR and verificated by DNA sequencing.Results In 40 strains of Enterobacter cloacae,the positive rates of genes of rmtB,aac(3)-Ⅱ,aac(6')-Ⅰ b,ant(3'')-Ⅰ,ant(2'')-Ⅰ and aph(3')-Ⅵ were 12.5%(5/40),27.5%(11/40),72.5%(29/40),32.5%(13/40),5.0%(2/40)and 5.0%(2/40),respectively.8 kinds of the rest of genes were all tested negative.The total positive rate of AMEs gene was 85.0%(34/40).Among 29 strains of Enterobacter cloacae that the aac(6')-Ⅰ b gene was positive,through PCR and verification by DNA sequencing,7 strains(24.1%)were confirmed to take the aac(6')-Ⅰ b-cr(the GenBank register number:EF375620,EU159121)alone,18 strains(62.1%)were confirmed to take the aac(6')-Ⅰ b-Suzhou(EU085533)alone,3 strains(10.3%)were confirmed to take both aac (6')-Ⅰ b-Suzhou and aac(6')-Ⅰ b-cr while only 1(3.4%)was aac(6')-Ⅰ b(the classical type).Conclusion There was lower positive rate of 16S rRNA methylase gene but very high AMEs genotypes in Enterobacter cloacae isolated from inpatients and the finding of rmtB gene was reported for the first time in the world.At least 5 kinds of AMEs gene existed in Enterobacter cloacae were isolated and they were the new host of both gene of aac(6')-Ⅰ b-cr and aac(6')-Ⅰ b-Suzhou,with aac(6')-Ⅰ b-Suzhou gene was the predominance subtype in aac(6')-Ⅰ b.
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Redox electrode was used to control redox potential at four different levels (-50 mV, -100 mV, -150 mV, - 230mV) for the study of ethanol fermentation. The result showed that there was notably influence on the yield of ethanol, the formation of glycerol, the secretion of organic acid, biomass and the death of cell by controlling redox potential at different levels. For example: the biomass of ORP at -50 mV was 1.26, 1.86, 2.59 times higher than ORP at -100 mV, -150 mV, -230 mV respectively, the final glycerol concentration was 1.2, 1.1, 1.7 times higher but final ethanol concentration was 0.87, 0.49, 0.51 times lower compared to the latest three ORP control level. And take biomass, ethanol yield, glycerol concentration, and unconsumed glucose into consider, we get the conclusion that it is very favorable for ethanol fermentation by control ORP at 150 mV. So it give us a apocalypse that we can use redox electrode to control the ethanol fermentation exactly on bioreactor scale.
Subject(s)
Electrodes , Ethanol , Metabolism , Fermentation , Industrial Microbiology , Methods , Oxidation-Reduction , Saccharomyces cerevisiae , MetabolismABSTRACT
The effect of induction temperature on aggregation of consensus interferon-alpha expressed by Pichia pastoris was investigated. The cell growth and cIFN level were analyzed and compared when Pichia pastoris was grown at 30,25,20 degrees C during induction phase, using 5.0L fermentor. The result suggested that the cell growth was not affected much under the different induction temperature, but the protein level declined markedly with the decrease of the induction temperature. The total protein ammount induced at 20 degrees C was 67.8 percent of that at 30 degrees C. SDS-PAGE and native-PAGE as well as Western blotting analysis were further conducted. The electrophoresis results revealed that cIFN formed aggregates after secreted into media when protein was induced at 30 degrees C but this problem can be restored by decreasing the induction temperature to 20 degrees C. cIFN monomer in supernatant arrived at 570mg/L and bioactivity of fermentation broth reached 1.05 x 10(9) IU/mL at 20 degrees C of induction temperature. The amount of cIFN monomer and bioactivity in supernatant elevated 7.2 and 38.7 times, respectively, when the induction temperature was controlled at 20 degrees C instead of conventional 30 degrees C.
Subject(s)
Humans , Fermentation , Interferon Type I , Genetics , Interferon-alpha , Pichia , Genetics , Metabolism , Recombinant Proteins , Genetics , TemperatureABSTRACT
13C metabolic flux analysis(13CMFA)have been the research hotspots of metabolic engineering internationally due to its accuracy and applicability.It is vital that the measurement of 13C labelling pattern of proteinogenic amino acids for 13C metabolic flux analysis.To acquire 13C-labelling proteinogenic amino acids,Pseudomonas denitrifican which products Vitamin B12 was firstly fed with mimimal culture medium contained 20% U-13C and 80% natural glucose,after the culture reached a steady state,then about 20 mg biomass was hydrolyzed by 1 ml of 6 mol/L hydrochloric acid for 24h at 110℃.Then amino acids was separated,concentrated,evaporated in a vacuum,and derivatized with MBDSTFA,TBDMS-derivatized amino acids can be observed by GC-MS last we get 13C labelling pattern of fifteen aminio acids through mass spectrum.The experimental methods and sample preparation offers referential value for the development of 13C metabolic flux analysis in our courtry.
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Immobilized penicillin acylase was used for bioconversion of penicillin G into 6-APA in aqueous two-phase systems consisted of a light-sensitive polymer PNBC and a pH-sensitive polymer PADB.Partition coefficients of 6-APA was found to be:about 5.78,in the presence of 1% NaCl.Enzyme kinetic showed that reaction reached equilibrium at 7h or so.The 6-APA mole yields were 85.3%(pH 7.8,and 20 ℃) and this value was about 20%higher than control in reaction of single aqueous phase buffer.Partition coefficient of penicillin G(Na) washardly changeable,while partition coefficient of product,6-APA and phenylacetate acid was significantly changeable.Reason is due to Donnan effect of phase systems andhydrophobicity of products.The change of partition coefficients of products also affects bioconversion yield of products.In the aqueous two-phase systems,substrate,penicillin G,products 6-APA and phenylacetate acid are biased in top phase,while immobilized penicillin acylase is completely partitioned in bottom.Substrate,penicillin G enters into bottom phase,and it is catalyzed into 6-APA and phenylacetate acid,then the products enter into top phase.Finally,inhibition of substrate and products is removed to result in improvement of products yield.Moreover,immobilized enzymehashigher efficiency than immobilized cells and occupy smaller volume.Comparing with free enzyme,immobilized enzymehashigher stability,longer use life,completely partitioned in bottom phase and recycle.Bioconversion in two-phase systems using immobilized penicillin acylase showed outstanding advantage.The light-sensitive copolymer forming aqueous two-phase systems could be recovered by laser radiation at 488 nm or filtrated 450 nm light,while pH-sensitive polymer PADB could be recovered by isoelectric point(pH 4.1).The recovery of the two copolymers was 95%~99%.