Showing papers in "Industrial Microbiology in 2007"

Enzymatic synthesis of 6-methylpurine-2'-deoxyriboside by recombinant purine nucleoside phosphorylase

Abstract: 6-Methylpurine-2'-Deoxyriboside(MePdR),an anticancer prodrug,was synthesized using MeP and dU by recombinant purine nucleoside phosphorylase of Escherichia coli.Experiment showed that reaction mixture composed of 15mmol/L MeP,60mmol/L dU,40mmol/L pH7.0 phosphate buffer and 2% wet cells gave a high yield of 83.78% at 55℃ in 2 hours.Separated by preparative TLC,a white needle solid with a yield of 76.4% and purity of 99.3% was provided,which was identified to be MePdR by 1H NMR.

Systemic identification of a paclitaxel-producing endofungus

Abstract: A paclitaxel-producing endofungus was screened from Taxus chinensis var.mairei.It was confirmed to be a new species of Fusarium genus with product,morphological identification including microscope and electron microscope,molecular identification including 18S rDNA,ITS and TB.It was named as Fusarium mairei Cheng L.et Tao WY.

Research advances in L-aspartate decarboxylase

Abstract: According to the catalysis position on L-aspartate,L-aspartate decarboxylase are devided into two forms:L-aspartate-α-decarboxylase and L-aspartate-β-decarboxylase.The advances in research of the structure,characteristics,gene expressing and application on both enzymes were introduced in this review.

Cloning of 1,3-propanediol oxidoreductase gene from Klebsiella pneumoniae and preliminary study on its expression conditions

Abstract: 1,3-propanediol oxidoreductase(PDOR) is one of the two key enzymes responsible for conversion of glycerol to 1,3-propanediol.In this study,its encoding gene dhaT was cloned by PCR from the genome of K.pneumoniae and inserted into pMD18-T.After DNA sequencing,both prokaryotic expression vectors,pET-28adhaT and pET-22b-dhaT were constructed respectively.Subsequently,recombinant plasmids were transformed into E.coli strain BL21(DE3) and the transformed strain was induced with IPTG.The results of SDS-Page analysis and protein localization assay reflected the high expression of PDOR in E.coli BL21(DE3).Of the two recombinant strains,E.coli BL21(DE3)(pET-28a-dhaT) could highly express soluble PDOR,accounting for 45 % of total soluble protein in cytoplasm or 25 % of total protein in the host.In contrast,almost all PDOR expressed by E.coli BL21(DE3)(pET-22b-dhaT) was insoluble inclusion body.Besides,the effect of induction temperature on enzyme activity was also investigated.Although PDOR expressed at normal temperature(30 ℃) showed certain enzyme activity,it displayed 3.7 times activity when induced at lower temperature(20 ℃),suggesting the distinct effect of temperature on protein expression.Furthermore,the advantages and disadvantages of both expression vectors were also discussed in this paper.

Optimization of fermentation medium for 2,3-butanediol production by Serratia marcescens

Abstract: Effects of several carbon sources,nitrogen sources,citric acid and initial concentration of sucrose on cell growth and 2,3-butanediol production by Serratia marcescens were investigated.The concentrations of medium components were optimized by the methods of one factor,orthogonal experiment and Box-Behnken design,and response surface analysis methods.Moreover,results showed that citric acid added in medium could improve cell growth and sugar utilization,reduce fermentation time and stimulate the production of 2,3-butanediol.It could accumulate 2,3-butanediol from 14.03 g/L up to 39.27 g/L.

Studies on antimicrobial substance produced by Lb. paracasei HD1.7

Abstract: A strain producing antimicrobial substance was identified.Its product was separated and its properties were studied.The strain was identified as Lactobacillus paracasei based on the morphologic characteristics,physiologic-biochemical characteristics and the analysis of 16SrDNA gene sequence.The antimicrobial spectrum tests indicated that the antimicrobial substance had strong inhibitory activity against gram-positive bacteria and gram-negative bacteria,and also against various pathogens.Extracted with organic solvent,the crude extract were obtained.The antimicrobial substance could be hydrolyzed by trysin.The molecular weight of the antimicrobial substance was about 14000 determined by the Urea-SDS-Polyacrylamide Gel Electrophoresis technique.

Isolation,identification and hexavalent chromium reduction studies of Bacillus cereus S5.4

Abstract: Hexavalent chromium,regarded as one of the most dangerous pollutants among heavy metals in the environment for its toxicity to living organisms,is being widely studied for its bioremediation.More and more microorganisms showing steady resistance and reduction ability of hexavalent chromium were identified,but few of them were applied to industrial fields.A series of bacteria with high resistance of hexavalent chromium were isolated from the electroplating sludge of Baosteel Corporation,Shanghai.A strain named S5.4,which showed high reduction ability of hexavalent chromium,was identified as Bacillus cereus by morphological,physiological and biochemical characteristics and its 16s rDNA sequence.Under the aerobic conditions,this strain was able to grow on LB plates with 40mmol/L Cr6+ after 48h,and also showed high endurance on Mn2+,Ba2+ and Mo6+.At the same time,this strain was able to completely reduce 2 mmol/L Cr6+ in LB liquid after 72 h,and work continuously with supplement of cultural medium and hexavalent chromium.For reducing hexavalent chromium,the optimal concentration,temperature range and pH range were 2mmol/L Cr6+,30～37℃ and pH 7～9,respectively.

Preliminary optimization of the culture conditions for lipase producing strain Aspergillus sp. FS132 and comparative analysis of its 18S rRNA gene

Abstract: A lipase-producing strain FS132 was isolated from the volcanic vent soil in Xinjiang Uygur Autonomous RegionIt was a mildew based on its colony morphologyThe optimal culture conditions for the FS132 producing lipase obtained were as follows: the optimal culture temperature of 36℃,initiation pH of 70 for the culture medium,oxygen-consumption of 25mL medium for each 250mL flask and culture time of 45 hoursThe strain was further identified on the molecular level,the 18S rRNA gene of FS132 was cloned and sequencedAccording to the phylogenetic analysis,the 18S rRNA marker of FS132 was showed highly homology to that of Aspergillus tamarii

Mutation breeding of Termitomyces albuminosus producing anti-coagulation protein TA-P

Abstract: The fungus,Termitomyces albuminosus TA-SD could produce anti-coagulation protein TA-P.In order to screening the mutants with higher activities,the mutation breeding of the strain TA-SD was carried out by ultraviolet mutagenesis.When the time of ultraviolet radiation was 40 seconds,the most positive mutation rate and anti-coagulation activity were reached,and it was 33.3% and 104.7% respectively.Both the positive mutation rate and anti-coagulation activity in the N-type mutants and cycloheximide-resistant mutants were higher than it in the S-type mutants and non-cycloheximide-resistant mutants.After screening the mutant SD-A-8 was obtained and its anti-coagulation activity was 2.3 times higher than the initial strain.The mutant was stable after the transfer of culture.

Decolorization and degradation of acid violet 43 by immobilized laccase

Abstract: Research on the decolorization and degradation of acid violet 43 by laccase immobilized on a new kind of acrylic copolymer were studied.The effects of dosage of immobilized laccase,concentration of acid violet 43,reaction temperature and pH value on the catalytical degradation were discussed in detail.The results indicated that the optimum conditions for decolorizing and degrading acid violet 43 by immobilized laccase were as follows: the dosage of immobilized laccase was 12.5 U/mL,the concentration of acid violet 43 was 150 mg/L,the reaction temperature was between 45℃ and 55℃,and the pH value was between 4.5 and 5.0.Under the above optimum condition,the decolorization rate of acid violet could reach 98.5%.The repeated batch decolorization of acid violet 43,carried out by immobilized laccase,showed that the decolorization rate still remained over 90% after 8 cycles of operation.Thus the catalytic efficiency of laccase was greatly improved by immobilization.

Optimization of high cell density cultivation conditions of Saccharomyces cerevisiae

Abstract: The effects of medium compositions and culture conditions on the growth of Saccharomyces cerevisiae were investigated.Based on the TB medium,medium components were optimized by means of orthogonal experiments,and the results showed that the most important component influencing the cell density was glucose, and the optimized medium per liter containing 15 g casein peptone,25 g yeast extract,30 g glucose,2.4 g KH2PO4,and 16.34 g K2HPO4·3H2O.Cultured at 30 ℃,150 r/min,the maximum optical density at 600 nm(OD600) and the cell density could reach 15.82 and 2.023×108/mL,which were increased by 24.2%and 22.0% compared with that of the control,respectively.

Biosynthesis of 5'-nucleosides triphosphate by immobilized beer yeast cells

Abstract: Immobilized beer yeast cells entrapped in κ-carrageenan-konjak polysaccharide were used to synthesize 5'-nucleosides triphosphate(NTPs) from 5'-nucleosides monphosphate(NMPs).In this experiment 20g immobilized beer yeast cells and 20mL reaction mixture(NMP 40mmol/L,glucose 150mmol/L,K2HPO4-KH2PO4 buffer 250mmol/L,MgSO4 10mmol/L,pH7.0) were added into 250mL-Erlenmeyer flask.After incubated at 35℃ for 2.5h the yields of NTP reached over 80%.If NAD+ was added into the mixture,the immobilized beer yeast cells can be reused 10 times with yield over 70%.

Reseach progress of petroleum biodesulfurization

Abstract: As more and more people are continuously aware of the importance of environmental protection and the standard of petroleum sulfur content is increasingly strict,researchers are paying more attention to the biodesulfurization of petroleum desulfurizing field.This review mainly introduces recent research progress on molecular biology of biodesulfurization and thermophilic desulfurizing bacteria.

Selection of a high-yield strain of tylosin after space piggyback experiment

Abstract: Using Streptomyces fradiae 9904S+-86 as the original strain,a mutant T1-156-84-23-s67 was obtained by space piggyback experiment of the 18th recoverable scientific experimenal satellite.Experienced the special and complicated space environment(high vacuum,microgravity,strong radiation,hand over change magnetic field etc.),the strain was mutagenized,and screened in lab.T1-156-84-23-s67 was finally selected for the tylosin production.The tylosin titre of selected strain was 15266u/mL,which was improved 74.6% more than that the original strain 9904S+-86(8742u/mL).The colony appearance and culture feature of the screened cells was investigated.Using protein SDS-PAGE analysis,both the screened strain and the original strain showed obvious difference.By the experiment of genetics stability,it showed that genetic variation of the strain had already taken place.It was the highest strain of the tylosin of selective breeding after space mutagenesis.

Optimization of lipase production conditions for Aspergillus sp. F044 by response surface methodology

Abstract: Lipase production condition of Aspergillus sp.F044 was fleetly optimized by seriatim-factorial experiment,Plackett-Burrman design,response surface methodology and monofactorial experiment.The optimum carbon and nitrogen for Aspergillus sp.F044 were obtained through seriatim-factorial experiment,which were maltose and beaf extract respectively.Through Plackett-Burrman design some process factors of lipase production were evaluated and three factors had prominent effect on lipase production were picked out,which were olive,bovine extract and bitter salt respectively.Then first-order model about the three factors was made to direct steepset ascent experiment.The central-composite design and response surface analysis were used to estimate optimum culture medium composition.The optimum fermentation temperature and agitation speed of rotary shaker were found by monofactorial experiment.The optimum culture medium was composed of 1.5%(w/v)maltose,7‰(w/v) ammonium sulfate,1‰(w/v) K2HPO4,1.25%(w/v) beaf extract,2.11‰(w/v) bitter salt,1.41%(v/v)olive,nature pH.After 72h incubation with the medium under the condition of 250r/min and 30℃,a maximum yield of 32.15U/mL was obtained.As a result,the Aspergillus sp.F044 lipase yield was improved 2.88-fold.

Screening and breeding of strains for producing succinic acid

Abstract: A strain of Actinobacillus succinogenes CGMCC 1593,producing succinic acid was isolated from bovin rumen by a media containing disodium fumarate as the only carbon source.Mutants from A.succinogenes CGMCC 1593 which were able to grow in medium containing concentrations of about 50～100 mmol/L of sodium monofluoroacetate,were obtained after NTG treatment.Among them,a mutant SF-9 could produce more succinic acid and less acetic acid.When fermentations were conducted in anaerobic bottles,the final succinic acid concentration of SF-9(35.09 g/L) increased 21.4%,and the mass ratio of succinic acid/acetic acid increased from 3.3 to 7.5 compared with those of the parent strain.Succinic acid concentration and yield reached 40.51 g/L and 0.81(w/w) in a 5 liter stirred bioreactor after 36 h,respectively,the mass ratio of succinic acid/acetic acid reached 9∶1.

Screening and identification of silicon-removal strain Enterobacter aerogenes

Abstract: 生物选矿以能耗低、污染少、适用于贫矿等优点而日益受到人们的关注.选矿菌种的分离和鉴定是进行生物选矿的首要环节.从菜园土中筛选到菌株S2-1,用该菌对伊利石矿粉进行了浸矿脱硅的实验,测得接种S2-1的溶液中的硅的浓度是对照液中的167.07%,说明S2-1对伊利石有脱硅作用.通过形态特征的观察,生理生化特性的测试,以及16S rRNA序列的比对分析,对菌株S2-1进行了鉴定.结果显示S2-1呈两端钝圆的短杆状,大小约1.3～1.5 μm×0.4～0.6 μm,革兰氏染色阴性,有端生鞭毛;生理生化特性的多项测试中大多数与产气肠杆菌(E.aerogenes)相同;16S rRNA序列的比对分析与产气肠杆菌(E.aerogenes) AF395913的同源性最高.实验结果表明S2-1属于产气肠杆菌(E.aerogenes).本文还对产气肠杆菌的脱硅条件进行实验,结果表明,S2-1脱硅的最适条件是温度30℃,起始pH值7.0,装液量60 mL和转速200 r/min.

Effects of temperature on expression of reteplase in Pichia pastoris

Abstract: The effects of temperature on the production of recombinant reteplase(rPA) in Pichia pastoris were investigated.The results demonstrated that in BMMY shake-flask culture,the expression of rPA at lower temperatures(20℃,25℃) was 1.4 and 1.34 times higher than that at 30℃,respectively.This was verified in high cell density cultures.The yield of rPA at lower temperatures(20℃,25℃) were 207.9mg/L and 199.5mg/L,respectively,both much higher than that cultured at high temperature(30℃,153.2 mg/L).The analysis of protease,cell viability and AOX activity showed that cultures at lower temperature not only led to a reduced cell death ratio and hence a lower amount of host cell proteases in the supernatant,but also significant increase of AOX activity.Those might be benefit for rPA production.

Medium optimization for kefiran synthesis by Lactobacillus kefiranofaciens

Abstract: The effects of medium composition on the cell growth and kefiran synthesis were studiedBased on the comparison of several saccharides and malt extract,the malt extract was the best for the cell growth and kefiran synthesis Nitrogen sources had influence on the Lkefiranofaciens fermentation and the yeast powder with 10% concentration was selectedThree inorganic salts,such as MnSO4·4H2O,MgSO4·7H2O and KH2PO4,were found to play an important role by using orthogonal design and RSA methodThe production of 26g/L kefiran could be obtained after 96h fermentation by adding 02g/L MnSO4 ·4H2O,1g/L MgSO4 ·7H2O and 4g/L KH2PO4 into the culture medium