多层搅拌式生物反应器内冷模和热模的传质特性
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摘要
采用不同浓度的羧甲基纤维素钠(CMC)溶液替代菌丝发酵液进行两种桨型组合(三层平直叶圆盘涡轮,3PY和底层半圆管圆盘涡轮HY及上面两层三宽叶翼型轴流桨KCXu,HY+2KCXu)的功率消耗和体积氧传质系数研究。结果表明:相同功率下,低浓度CMC溶液中上翻操作的HY+2KCXu组合的传质能力更好,但是随着黏度的增加,两种组合的传质能力趋于相同。同时采用两种桨型组合进行黑曲霉产糖化酶的发酵实验,通过调节转速实现两种桨型下发酵罐内菌体的氧摄取速率相近,通过对产酶量、菌形、发酵液流变特性以及反应器内的传质能力对比研究发现:发酵过程中装有HY+2KCXu组合的罐内发酵液的表观黏度低于装有3PY组合的罐,HY+2KCXu罐内似乎更容易形成菌球,菌球的形成降低了发酵液的黏度,传质系数增大,从而提高了产酶效率。
Carboxyl methyl cellulose(CMC)solutions with different concentrations simulating different mycelial fermentation broth were used for the study of mass transfer characteristics in bioreactor.Two impeller combinations(triple Rushton turbines,3PY and bottom hollow blade turbine combined with upper two up-pumping hydrofoils(3 blades), HY + 2KCXu) were employed.Under low CMC concentration condition,impeller combination of HY+2KCXu showed better mass transfer capacity.Fermentation of Aspergillus niger with production of glucoamylase was conducted under the two impeller combinations.In order to keep the similar oxygen uptake rate(OUR)among the two combinations,impeller rotation speed of the two configurations was adjusted respectively.Ultimately,based on the investigation of enzyme production,biomass amount,broth rheology and also mass transfer capacity ofimpellers,conclusions were gotten:apparent viscosity of broth in fermentation with HY+2KCXu was lower than that with 3PY.It seemed that in fermenter equipped with HY+2KCXu pellet prevailed than mycelia,thus lower viscosity was resulted,which in turn increased the mass transfer capacity of the system,that may be the reason why this impeller combination can gave higher product titer.
Carboxyl methyl cellulose(CMC)solutions with different concentrations simulating different mycelial fermentation broth were used for the study of mass transfer characteristics in bioreactor.Two impeller combinations(triple Rushton turbines,3PY and bottom hollow blade turbine combined with upper two up-pumping hydrofoils(3 blades), HY + 2KCXu) were employed.Under low CMC concentration condition,impeller combination of HY+2KCXu showed better mass transfer capacity.Fermentation of Aspergillus niger with production of glucoamylase was conducted under the two impeller combinations.In order to keep the similar oxygen uptake rate(OUR)among the two combinations,impeller rotation speed of the two configurations was adjusted respectively.Ultimately,based on the investigation of enzyme production,biomass amount,broth rheology and also mass transfer capacity ofimpellers,conclusions were gotten:apparent viscosity of broth in fermentation with HY+2KCXu was lower than that with 3PY.It seemed that in fermenter equipped with HY+2KCXu pellet prevailed than mycelia,thus lower viscosity was resulted,which in turn increased the mass transfer capacity of the system,that may be the reason why this impeller combination can gave higher product titer.
引文
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[2]PAPAGIANNI M.Fungal morphology and metabolite production in submerged mycelial processes[J].Biotechnol.Adv.,2004,22(3):189-259.
[3]OLSVIK E,KRISTIANSEN B.Rheology of filamentous fermentations[J].Biotechnol.Adv.,1994,12(1):1-39.
[4]LI Z J,SHUKLA V,WENGER K S,et al.Effects of increased impeller power in a production-scale aspergillusoryzae fermentation[J].Biotechnol.Prog.,2002,18(3):437-444.
[5]MCNEIL B,HARVEY L M.Viscous fermentation products[J].Crit.Rev.Biotechnol.,1993,13(4):275-304.
[6]GARCIA-OCHOA F,GOMEZ E.Bioreactor scale-up and oxygen transfer rate in microbial processes:an overview[J].Biotechnol.Adv.,2009,27(2):153-176.
[7]GIBBS P A,SEVIOUR R J,SCHMID F.Growth of filamentous fungi in submerged culture:problems and possible solutions[J].Crit.Rev.Biotechnol.,2000,20(1):17-48.
[8]ALBAEK M O,GERNAEY K V,HANSEN M S,et al.Modeling enzyme production with Aspergillus oryzae in pilot scale vessels with different agitation,aeration,and agitator types[J].Biotechnol.Bioeng.,2011,108(8):1828-1840.
[9]ZHOU X,HU Z,NIENOW A W,et al.Rheological characteristics,power consumption,mass and heat transfer during xanthan fermentation[J].Chin.J.Chem.Eng.,1994,4(4):15-27.
[10]GABELLE J C,JOURDIER E,LICHT R B,et al.Impact of rheology on the mass transfer coefficient during the growth phase of Trichoderma reesei in stirred bioreactors[J].Chem.Eng.Sci.,2012,75(0):408-417.
[11]GABELLE J C,AUGIER F,CARVALHO A,et al.Effect of tank size on kLaand mixing time in aerated stirred reactors with non-newtonian fluids[J].Can.J.Chem.Eng.,2011,89(5):1139-1153.
[12]XIE M H,XIA J Y,ZHOU Z,et al.Power consumption,local and average volumetric mass transfer coefficient in multiple-impeller stirred bioreactors for xanthan gum solutions[J].Chem.Eng.Sci.,2014,106:144-156.
[13]LPEZ J L C,PREZ J A S,SEVILLA J M F,et al.Pellet morphology,culture rheology and lovastatin production in cultures of Aspergillus terreus[J].J.Biotechnol.,2005,116(1):61-77.
[14]O′CONNOR C T,RANDALL E W,GOODALL C M.Measurement of the effects of physical and chemical variables on bubble size[J].Int.J.Miner.Process.,1990,28(1/2):139-149.
[15]CLARKE K G,CORREIA L D C.Oxygen transfer in hydrocarbon-aqueous dispersions and its applicability to alkane bioprocesses:a review[J].Biochem.Eng.J.,2008,39(3):405-429.
[16]KAWSE Y,MOO-YONG M.Volumetric mass transfer coefficients in aerated stirred tank reactors with Newtonian and non-Newtonian media[J].Chem.Eng.Res.Des.,1988,66(3):284-288.
[17]NOCENTINI M,FAJNER D,PASQUALI G,et al.Gasliquid mass transfer and holdup in vessels stirred with multiple Rushton turbines:water and water-glycerol solutions[J].Ind.Eng.Chem.Res.,1993,32(1):19-26.
[18]GOGATE P R,BEENACKERS A A C M,PANDIT A B.Multiple-impeller systems with a special emphasis on bioreactors:a critical review[J].Biochem.Eng.J.,2000,6(2):109-144.
[19]LEMOINE R,MORSI B I.An algorithm for predicting the hydrodynamic and mass transfer parameters in agitated reactors[J].Chem.Eng.J.,2005,114(1/2/3):9-31.
[20]ALBAEK M O,GERNAEY K V,HANSEN M S,et al.Evaluation of the energy efficiency of enzyme fermentation by mechanistic modeling[J].Biotechnol.Bioeng.,2012,109(4):950-961.