膜反应器固定化米根霉发酵产富马酸的工艺研究

以膜反应器固定化米根霉发酵产富马酸为研究对象,以Na2CO3为中和剂,考察固定化米根霉在5L搅拌式发酵罐中的发酵特征,采用智能可视化软件(IVOS)优化发酵工艺条件。结果表明,在80g/L初始糖浓及最优工艺下,富马酸产量、生产速率及转化率分别为21.1g/L、0.25g/(L·h)和28%;采用40g/L初始糖浓及连续批次发酵工艺时,富马酸产量、生产速率及转化率最高分别为10.8 g/L、0.36g/(L·h)和27%。搅拌式反应器中,固定化米根霉的膜反应器比表面积有限,以及菌膜的空间阻隔效应对传质传氧的限制作用,显著影响了富马酸的生产强度和转化率。因此,亟需发掘新的固定化方法及反应器形式,达到既解决米根霉形态控制问题,又有助于生产性状提升的目标。     

固定化米根霉发酵制L-乳酸

采用海藻酸钙包埋法固定化米根霉（Ｒｈｉｚｏｐｕｓｏｒｙｚａｅ）,菌体在颗粒表面形成一层菌丝膜,有利于氧气和其它营养物质的传递;三相流化床生物反应器结构简单、动力消耗低、反应器内物质混合均匀、氧传递量大于固定化米根霉的需氧量,非常适合好氧的固定化米根霉发酵。利用它进行重复使用固定化米根霉的间歇发酵或连续发酵制备Ｌ 乳酸,整个过程一般可持续两周以上。固定化米根霉的产酸速率达１６～１８ｇ／Ｌ ｂｅａｄ．ｈｒ,得率为７０～８０％,反应器生产能力约为传统搅拌罐的３倍。采用海藻酸钙包埋法固定化米根霉在三相流化床生物反应器中进行发酵可以有效地提高Ｌ 乳酸的生产效率,具有良好的工业应用前景。     

固定化米根霉发酵制L—乳酸

采用海藻酸钙包埋法固定化米根霉,菌体在颗粒表面形成一层菌丝膜,有利于氧气和其它营养物质的传递;三相流化床生物反应器结构简单,动力消耗低,反应器内物质混合均匀、氧传递量大于固定化米根霉的需氧量,非常适合好氧的固定化米根霉发酵。     

米根霉ME—F12发酵产富马酸的菌体形态控制

丝状真菌发酵体系中菌体形态对产量有着重要影响。考察富马酸产生菌Rhizopus oryzae ME—F12种子培养过程中不同pH条件、孢子悬浮液密度以及CaCl2添加量对其形态的影响。结果表明,当控制种子培养液pH2．3～2．7、接种孢子的终密度为1．5×10^8～3．0×10^8／L和添加0．5g／LCaCl2时,培养可获得直径约为0．65mm光滑规整茵球,后继的产酸发酵中富马酸量高达58．9g／L。正交实验表明,pH是影响菌球形成的最主要因素,孢子液密度主要影响菌体生物量,而CaCl2则是菌球表面光滑度的主要影响因素。     

米根霉发酵产富马酸的最适替代中和剂及pH调控策略研究

针对米根霉发酵产富马酸使用的不同中和剂(CaCO3,Na2CO3,NH3·H2O,NaOH)进行了研究,结果表明发酵过程中使用Na2CO3作为中和剂时富马酸产率和生产强度最接近传统中和剂CaCO3.此后考察了不同pH值(3.5,4.5,5.5和6.5)对Na2CO3作为中和剂的富马酸发酵过程的影响.基于对3个动力学参数的分析,提出了一个旨在同时获得富马酸高产物浓度、高产率和高生产强度的双阶段pH调控策略,在初始的24 h内pH控制在5.5,然后将pH调到4.5直至发酵结束.最终富马酸的终浓度达到40.5 g/L,产率为0.55 g/g,生产强度为0.61 g/L/h,比恒定pH时的最优结果分别提高了8.3％,10.0％和17.3％,其中生产强度甚至比使用CaCO3时还高了3.4％.故以Na2CO3作为中和剂,采用双阶段pH调控策略具有降低能耗和简化下游步骤的优势,可以成功取代CaCO3.     

利用固定化米根霉在三相流化床中发酵生成L-乳酸

用聚氨酯泡沫吸附固定米根霉菌丝,在三相流化床中对葡萄糖、木糖以及木糖渣的纤维素酶解液等不同碳源进行Ｌ－乳酸发酵研究,并对游离菌丝和固定化菌丝发酵Ｌ－乳酸进行了比较。结果表明,聚氨酯泡沫是米根霉的良好载体,具有经济、高效等特点。实验条件下,不同碳源的乳酸转化率分别为：葡萄糖,８２．５％;木糖,５３．８％;木糖渣酶水解液,７１．９％。三相流化床中固定化米根霉产酸速率（对葡萄糖）为１９．１ｇ．ｈ＾－１．     

无载体固定化米根霉重复间歇发酵生产L-乳酸

通过研究影响米根霉菌丝体形态的培养基因素,初步构建了无载体固定化米根霉重复间歇发酵生产L-乳酸的工艺条件.研究结果表明,首批次发酵培养基采用120 g/L葡萄糖,3 g/L硝酸铵,K 和Na 浓度比为1:1,发酵72 h后,米根霉菌体形态为均匀的茵丝体小球,直径为1.0 mm～2.0 mm,此时L-乳酸产量可达100.8 g/L,葡萄糖转化率为84%.在此基础上,利用米根霉菌丝体小球重复间歇发酵16批次,每批次发酵24h,此时葡萄糖转化率均高于75%,L-乳酸产量保持在60.0 g/L以上,米根霉菌丝体小球形态保持稳定.     

固定化米根霉生产L－乳酸的研究

开发了利用聚氨酯泡沫为载体固定化米根霉生产Ｌ－乳酸的新工艺。确定了固定化细胞发酵条件：葡萄糖浓度为５０ｇ／ｌ,载体立方体边长为４～８ｍｍ,载体量为２０ｃｍ３／７０ｍｌ培养基,固定化细胞制备培养时间为２４ｈ．利用固定化细胞发酵产酸速率是游离菌的３倍以上,对糖转化率达７７．７０％,与理论转化率相近。该固定化细胞应用在反复间歇发酵中可稳定１０批次以上。     

利用固定化米根霉在三相流化床中发酵生成L-乳酸

用聚氨酯泡沫吸附固定米根霉菌丝,在三相流化床中对葡萄糖、木糖以及木糖渣的纤维素酶解液等不同碳源进行L乳酸发酵研究,并对游离菌丝和固定化菌丝发酵L乳酸进行了比较。结果表明,聚氨酯泡沫是米根霉的良好载体,具有经济、高效等特点。实验条件下,不同碳源的乳酸转化率分别为：葡萄糖,82.5%;木糖,53.8%;木糖渣酶水解液,71.9%。三相流化床中固定化米根霉产酸速率(对葡萄糖)为191g.h-１.L(bead)-1。     

三相流化床中固定化米根霉萃取发酵生产L-乳酸

以TRPO／磺化煤油为萃取剂,在2L三相流床反应器中进行了固定化米根霉原位萃取和异位萃取发酵生产L-乳酸的实验,结果表明,发酵液中的pH值能被控制在3．5左右．产酸速率高达每小时．每1L固定化颗粒产生11gL-乳酸。提出了一个数学模型用以描述萃取发酵中L-乳酸的积累及在各相的分配情况。模型计算曲线与实验值符合良好。     

Fumaric acid fermentation with immobilised Rhizopus oryzae: Quantifying time-dependent variations in catabolic flux

A novel fermenter system utilising immobilised Rhizopus oryzae is presented. The impact of dissolved oxygen (20%, 60% and 80%) and pH (4 and 5) was investigated. All fermentations exhibited three distinct phases. Phase A, at the start, was associated with no fumarate production, minimal respiration and ethanol as the major product. Phase B was characterised by the onset of fumarate production and significant ethanol and respiration fluxes. Phase C was associated with zero ethanol flux. Inhibition of fumarate production was more severe at low pH. The DO 20% fermentation (pH 5) had a low respiration flux which resulted in excessive ethanol production. Higher DO levels resulted in less inhibition of fumarate production during phase C. Instantaneous fumarate yields on glucose were at a maximum at the start of phase C, with values in excess of 0.75 g g⁻¹ achieved for the DO 60% and 80% fermentations.     

离子注入选育高产L-乳酸的米根霉突变株及其发酵特性研究

通过氮离子注入获得米根霉突变株RQ4012,其利用木糖的能力比出发菌株提高了1.6倍;通过多次传代,证明其具有良好的遗传稳定性。试验测定菌株RQ4012发酵木糖生产L-乳酸的最佳发酵条件:木糖10%,生理盐水浸泡孢子9 h,(NH4)2SO43 g/L,接种量4%,CaCO3添加量6%,装液量20%,温度37℃,转速200 r/min,在此条件下,乳酸产量达到79.51 g/L。对混合糖的发酵进行了探索,结果表明该菌能高效利用混合糖生产L-乳酸,在利用植物纤维素水解液生产L-乳酸上有良好的应用前景。     

Simultaneous Production and Recovery of Fumaric Acid from Immobilized Rhizopus oryzae with a Rotary Biofilm Contactor and an Adsorption Column

An integrated system of simultaneous fermentation-adsorption for the production and recovery of fumaric acid from glucose by Rhizopus oryzae was investigated. The system was constructed such that growing Rhizopus mycelia were self-immobilized on the plastic discs of a rotary biofilm contactor during the nitrogen-rich growth phase. During the nongrowth, production phase, the biofilm was alternately exposed to liquid medium and air upon rotation of the discs in the horizontal fermentation vessel. The product of fermentation, fumaric acid, was removed simultaneously and continuously by a coupled adsorption column, thereby moderating inhibition, enhancing the fermentation rate, and sustaining cell viability. Another beneficial effect of the removal of fumaric acid is release of hydroxyl ions from a polyvinyl pyridine adsorbent into the circulating fermentation broth. This moderates the decrease in pH that would otherwise occur. Polyvinyl pyridine and IRA-900 gave the highest loading for this type of fermentation. This fermentation system is capable of producing fumaric acid with an average yield of 85 g/liter from 100 g of glucose per liter within 20 h under repetitive fed-batch cycles. On a weight yield basis, 91% of the theoretical maximum was obtained with a productivity of 4.25 g/liter/h. This is in contrast to stirred-tank fermentation supplemented with calcium carbonate, whose average weight yield was 65% after 72 h with a productivity of 0.9 g/liter/h. The immobilized reactor was operated repetitively for 2 weeks without loss of biological activity.     

米根霉发酵生产L-乳酸

报道了Ｌ－乳酸菌株的分离与筛选,探讨了不同碳源、氮源、通气量、温度等发酵条件对产Ｌ－乳酸的影响,从７８株米根霉中筛选出１３株产Ｌ－乳酸较高的菌株,其中米根霉（Ｒｈｉｚｏｐｕｓ ｏｒｙｚａｅ）Ｒｓ９２８产Ｌ－乳酸最高,产酸最稳定。试验结果表明,该菌株最适发酵培养组成（％）：淀粉水解糖１６,ＭｇＳＯ４ ０．０８,ＫＨ２ＰＯ４ ０．０５,ＺｎＳＯ４ ０．０１,ＣａＣＯ３ ７,ｐＨ自然。在６０ｔ发酵罐中,     

Co-production of fumaric acid and chitin from a nitrogen-rich lignocellulosic material - dairy manure - using a pelletized filamentous fungus Rhizopus oryzae ATCC 20344

Fumaric acid is widely used as a food additive for flavor and preservation. Rhizopus oryzae ATCC 20344 is a fungus known for good fumaric acid production. It also has been reported that the fungal biomass has high chitin content. This study investigated the possibility of producing both fumaric acid and chitin via R. oryzae fermentation of dairy manure. Co-production of valuable bio-based chemicals such as fumaric acid and chitin could make the utilization of manure more efficient and more profitable. A three step fermentation process was developed which effectively utilized the nitrogen as well as the carbohydrate sources within the manure. These steps were: the culturing of pellet seed; biomass cultivation on liquid manure to produce both biomass and chitin; and fumaric acid production on the hydrolysate from the manure fiber. Under the identified optimal conditions, the fermentation system had a fumaric acid yield of 31%, and a biomass concentration of 11.5 g/L that contained 0.21 g chitin/g biomass.     

Anaerobic Immobilized Yeast Cell Fermentation and Anaerobic Remediation in Hybrid Reactor for Mineralization of Dicarboxylic Acid Solid Waste

Summary The solid resinous product (SRP) containing unsaturated/saturated dicarboxylic acid residues, phthalic acid and maleic acid is discharged as a solid waste during cracking of benzene over vanadium at temperatures above 500°C in the dicarboxylic acid manufacturing industry. In the present study the solid waste was diluted with water to a concentration of 0.5% w/v for microbial degradation. The waste was fermented in a reactor containing mesoporous activated carbon on which was immobilized Saccharomyces cerevisiae at an optimum residence time of 24 h at pH 6.5. The immobilized-yeast-treated samples were further treated in an upflow anaerobic reactor at an hydraulic retention time (HRT) of 0.1038 days at a hydraulic flow rate of 7.34 × 10⁻³ m³/day and chemical oxygen demand (COD) loading rate of 2.19 kg/m³/day. The pathway followed in the degradation of dicarboxylic acid into end products by anaerobic metabolism in the yeast cell fermentor and in the upflow anaerobic reactor was confirmed through HPLC, Fourier transform infra red spectroscopy and proton and ¹³C NMR spectroscopy.     

固定化细胞的混合糖连续发酵动力学模型

利用固定化啤酒酵母和固定化毕赤酵母在两个串联的固定床内连续发酵由葡萄糖和木糖组成的混合糖制取酒精的过程,建立了连续发酵的非结构动力学模型。该模型以带抑制项的米氏动力学方程为酶动力学基础,考虑了抑制物抑制、底物抑制、轴向弥散及膜传质等因素。成功地引入了一个综合考虑颗粒相内外传质的总有效因子简化模型的计算,并取得了较为满意的仿真结果。