Relations between gibberellin hyphae and secondary metabolic product GA3 by resting culture method

针对赤霉菌生长与产次级代谢产物赤霉素的关系进行摇瓶静息培养研究.在不同菌龄及不同底物浓度的条件下,菌丝产素能力有较大不同.实验数据表明:在菌龄96 h,葡萄糖浓度为5g/L时,菌丝静息培养72 h后,培养液中赤霉素含量最高,达1100 μg/mL;同时单位时间单位菌丝产率也最大,为7.1μg/mg·h;在该菌龄条件下,当葡萄糖浓度为1g/L时,赤霉素转化效率最高,为0.8484.该研究有助于进一步优化发酵工艺,降低赤霉素生产成本.     

海藻酸钙固定赤霉菌菌丝产素的研究

将赤霉菌丝固定在海藻酸钙微球中进行连续发酵,考察产赤霉素情况。对海藻酸钠和钙盐浓度固定赤霉菌菌丝的微球稳定性进行初步研究,讨论了固定不同菌龄的赤霉菌微球在不同葡萄糖浓度下的产素能力及菌丝生长能力。实验表明:菌丝微球较稳定的固定条件是菌丝8 g/L、海藻酸钠浓度3 g/L和钙离子浓度3 mol/L;摇瓶发酵72 h,90 h的菌丝微球中菌丝营养生长基本停止,当培养液葡萄糖浓度为2 g/L时,赤霉素终浓度为1 145.5 μg/ml,比生产速率为4.61×10^-3/h;在该条件下固定菌丝球的床层式连续发酵,赤霉素比生产速率为4.82×10^-3/h,是相应分批发酵过程中最大赤霉素生产速率的1.87倍。     

玫烟色拟青霉最适液体培养条件的研究

通过对不同营养和不同培养条件下玫烟色拟青霉菌丝生物量和产孢量的研究,结果表明:葡萄糖为玫烟色拟青霉液体培养的最适碳源,蛋白胨为该菌生长的最适氮源,C/N为10∶1~20∶1最适于玫烟色拟青霉菌丝生长和产孢;25℃2、4 h全光照条件,对该菌生长和产孢均有利。接种后144~168 h时,菌丝生物量和产孢量均达到高峰,分别为31.72 mg/mL、24.62孢子/mL,为黑暗条件下的1.5倍和18.3倍,因此玫烟色拟青霉液体发酵终点应选择在接种后144~168 h为最好。     

产酸丙酸杆菌生长特性及5L罐发酵动力学研究

论文在摇瓶水平对产酸丙酸杆菌基本生长特性（温度、pH、摇床转速、接种量、种龄等）、碳源、氮源利用情况、产物抑制及5 L罐发酵动力学进行了研究。结果表明,该菌在32℃,初始pH 6．5,摇床转速150 r/min,接种24 h的种子液,接种量为5％条件下,产酸丙酸杆菌生长及产酸水平达最高值;该菌可利用碳源十分广泛,但对氮源要求比较高,只可利用有机氮源;在不同初始葡萄糖浓度下,产酸丙酸杆菌生长及产酸水平差异不大,无明显底物抑制现象;在2g/L的初始丙酸盐浓度下,该菌生长受到明显抑制;在5L发酵罐中,初始葡萄糖浓度为58．8 g/L,发酵72 h,葡萄糖消耗完全,丙酸终浓度达22．4 g/L,丙酸得率和产率分别达0．381 g/g和0．295 g/（L·h）,丙酸占总酸比例达72．10％。     

提高蛋白激发子产量的培养基及发酵条件的优化

为了进一步提高极细链格孢菌产蛋白激发子的产量,通过单因子和多因子试验与分析,筛选优化了适于极细链格孢菌产生蛋白激发子的培养基和培养条件,并检测了发酵过程中pH、还原糖、氨基氮和菌丝量变化以及与蛋白激发子产量的关系。结果表明,土豆淀粉和黄豆粉对蛋白激发子产量影响最大,其次是蛋白胨和无机盐。优化的发酵培养基主要成分（g／L）：碳源I 15、葡萄糖5、玉米淀粉5、土豆淀粉20、谷氨酸10、氮源I5、黄豆粉10、硫酸铵5。确定了优化的培养条件,调整培养基起始pH为7．0～7．5,将18h菌龄的种子培养液按10％接种量接种到装液量为75mL的500mL摇瓶中,在温度（28±1）℃、摇床转速180r／min下培养可获得理想的蛋白产量。在优化的培养基和培养条件下,发酵12～48h该菌进入对数生长期,48h进入稳定生长期,60h菌丝扣蛋白激发子产量达最高。蛋白产量与菌体生物量呈正相关,当还原糖、总糖量消耗到最低水平时,菌丝产量和蛋白激发子产量达最高。优化的培养基菌丝干重收率迭3．9g／100mL,蛋白激发子产量达到5．17g／L,比普通的土豆液体培养基提高近4倍。     

galU基因在乳酸乳球菌中的克隆及其对胞外多糖产生的影响

从EcoliBL21克隆到UDP-葡萄糖焦磷酸化酶（UGPase）基因galU,与pNZ8048载体连接构建重组表达质粒pNZ8048-galU,进而导入乳酸乳球菌L.lactisL18中,得到重组菌L.lactisL18／pNZS048-galU,研究galU插入对该菌产生胞外多糖的影响。结果显示,在含葡萄糖和乳糖（20：20g／L）的MRS培养基中,重组菌L.lactisL18／pNZ8048-galU在30℃,pH6．5的条件下培养26h,EPS产量最高,为1489．54mg／L;而相同条件下,L．lactisL18培养28h产量最高,为848．93mg／L。二者相比,EPS产量增加了1．75倍。     

纤维素酶高产菌株Trichoderma atroviride HP35-3原生质体制备及转化

旨在优化深绿木霉(Trichoderma atroviride)菌株HP35-3原生质体制备和转化条件,便于对该菌株进行遗传操作以提高其纤维素酶产量。分别对制备深绿木霉原生质体的菌龄、酶解时间、酶组分及比例和转化条件进行优化。结果显示,利用3mg/m L蜗牛酶、3 mg/m L溶菌酶和3 mg/m L裂解酶酶组分酶解菌龄10 h的菌丝2 h,获得的原生质浓度达到3.5×107个/m L以上,原生质体再生率为61%。利用原生质体进行PEG介导转化,当原生质体浓度为1×108个/m L、外源DNA为5μg时,转化率达到35个转化子/μg DNA。建立的高效原生质体制备及转化体系可用于深绿木霉的遗传转化及菌株改造。     

木霉LaTr 01菌株产漆酶发酵的条件

从华南地区采集土样,采用愈创木酚平板筛选产漆酶菌株,获得了一株短周期产漆酶的小型丝状真菌。通过观察菌落特征、生长情况以及显微镜下菌丝和孢子的形态,初步鉴定该菌株为木霉属的一个种（Trichodermaspp、）,命名为木霉LaTr01菌株。通过单因素方法研究该菌产漆酶的发酵条件,结果表明：LaTr01的产酶培养基以麦芽糖为最佳碳源;以酵母提取物为最适氮源;培养24h后加入Cu“比培养开始加入Cu ^2＋LaTr01产酶活高出约1倍。采用麦芽糖、酵母提取物、Cu^2＋浓度L9（3^3）的正交试验优化漆酶发酵条件,结果表明,氮源是影响该菌产漆酶的最重要因素,碳源次之,Cu^＋浓度影响较小;LaTr01菌株产生漆酶的最佳条件为：5g／L酵母提取物、20g/L麦芽糖、1．5mmol／LCu^2＋,Cu^2＋加入时间为培养24h后。在优化的培养条件下,该菌酶活可达480．556U／L。     

牛肝菌液体发酵及产多糖的影响因素研究

牛肝菌(Boletused)属外生菌根菌,美味牛肝菌多糖有明显的抗肿瘤效果。采用液体培养方法对牛肝菌菌丝体的发酵及产多糖特性进行了研究,实验考察了培养基中葡萄糖浓度和培养基的初始pH对牛肝菌菌丝量及产多糖的影响。结果表明,实验条件下,该株牛肝菌在pH值5．5—6．0,葡萄糖含量为60mg/mL时,多糖产量为6．7mg/mL。实验考察了从发酵菌丝体中提取多糖的几种方法,其中研磨法效果较好,与对照相比,多糖提取量增加了20％。     

发酵产氢菌株的筛选及影响因素研究

采用双层平板法从污泥池中筛选出一株产氢较高的发酵菌株,经生理生化鉴定表明,分离菌株初步鉴定为消化链球菌属(Peptostreptococcus).研究静态培养条件下葡萄糖、pH、温度及和酵母膏对菌株产氢的影响及不同发酵时间段的产氢情况.结果表明,在葡萄糖浓度20.0 g/L,pH 7.0,温度37 ℃和酵母膏2.0 g/L时,产氢量达21.07 mmol/L,为初始培养条件下的4.14倍.同时,在24～36 h时间段产氢率达到最高,为0.44 mmol/(L·h),并且在60 h时产氢量达到最大累计产氢量的89.2%.     

Production of poly(3-hydroxybutyric acid) by fed-batch culture of Alcaligenes eutrophus with glucose concentration control

Alcaligenes eutrophus NCIMB 11599 was cultivated to produce poly(3-hydroxybutyric acid) (PHB) from glucose by the automatic fed-batch culture technique. The glucose concentration of the culture broth was controlled at 10 to 20 g/L by two methods: using exit gas data obtained from a mass spectrometer and using an on-line glucose analyzer. The effect of ammonium limitation on PHB synthesis at different culture phases was studied. The final cell concentration, PHB concentration, and PHB productivity increased as ammonia feeding was stopped at a higher cell concentration. High concentrations of PHB (121 g/L) and total cells (164 g/L) were obtained in 50 h when ammonia feeding was stopped at the cell concentration of 70 g/L. The maximum PHB content reached 76% of dry cell weight and the productivity was 2.42 g/L h with the yield of 0.3 g PHB/g glucose.     

Enhancement of ribitol production during fermentation of <Emphasis Type="Italic">Trichosporonoides oedocephalis</Emphasis> ATCC 16958 by optimizing the medium and altering agitation strategies

To maximize the productivity of ribitol, which is an important starting material for the production of one expensive rare sugar, L-ribose, the effects of culture medium and agitation speed on cell growth as well as on the productivity of ribitol were thoroughly investigated in a 7 L fermentor. The maximum volumetric productivity, 0.322 g/L/h of ribitol, were obtained at an initial glucose concentration of 200 g/L in a batch culture. Based on the optimum glucose concentration, the ribitol yield conversed from glucose was up to 0.193 g/g when 1% yeast extract was used as a nitrogen source. When the agitation speed was maintained at 200 rpm, the ribitol concentration of 38.60 g/L was collected after 120 h of cultivation time. Additionally, the scheme of two-phase agitation and glucose infusion was employed. To begin, in the first 24 h of fermentation, a high agitation rate at 350 rpm and the initial glucose concentration of 50 g/L were applied, and the biomass concentration of 25.50 g/L was achieved at 36 h of incubation; whereas this value was observed until 60 h in the former batch fermentation methods. Then, in the second phase, with the agitation speed reduced to 150 rpm and the infusion amount of glucose controlled at 150 g/L, the yield of ribitol reached to 65.00 g/L in two-phase agitation fermentation and was 1.68 fold of that obtained in one-stage batch fermentation. To our knowledge, this study first demonstrates its significant effectiveness in improving ribitol production with the application of Trichosporonoides oedocephalis ATCC 16958.     

High-yield production of lutein by the green microalga Chlorella protothecoides in heterotrophic fed-batch culture

The green microalga Chlorella protothecoides was grown heterotrophically in batch mode in a 3.7-L fermenter containing 40 g/L glucose and 3.6 g/L urea. In the late exponential phase, concentrated nutrients containing glucose and urea were fed into the culture, in which the nitrogen source was sufficient compared to carbon source. As a result, a maximum cell dry weight concentration of 48 g/L was achieved. This cell dry weight concentration was 28.4 g/L higher than that obtained in batch culture under the same growth conditions. In another cultivation run, the culture was provided with the same initial concentrations of glucose (40 g/L) and urea (3.6 g/L) as in the batch mode, followed by a relatively reduced supply of nitrogen source in the fed-batch mode to establish a nitrogen-limited culture. Such a modification resulted in an enhanced lutein production without significantly lowering biomass production. The cellular lutein content was 0.27 mg/g higher than that obtained in the N-sufficient culture. The improvements were also reflected by higher maximum lutein yield, lutein productivity, and lutein yield coefficient on glucose. This N-limited fed-batch culture was successfully scaled up from 3.7 L to 30 L, and a three-step cultivation process was developed for the high-yield production of lutein. The maximum cell dry weight concentration (45.8 g/L) achieved in the large fermenter (30 L) was comparable to that in the small one (3.7 L). The maintenance of the culture at a higher temperature (i.e., 32 degrees C) for 84 h resulted in a 19.9% increase in lutein content but a 13.6% decrease in cell dry weight concentration as compared to the fed-batch culture (30 L) without such a treatment. The enhancement of lutein production resulted from the combination of nitrogen limitation and high-temperature stress.     

Evaluation of Arthrospira platensis extracellular polymeric substances production in photoautotrophic, heterotrophic and mixotrophic conditions

The kinetic study of Arthrospira platensis extracellular polymeric substances (EPS) production under different trophic modes??photoautotrophy (100???mol photons m^?2?s^?1), heterotrophy (1.5?g/L glucose), and mixotrophy (100???mol photons m^?2?s^?1 and 1.5?g/L glucose)??was investigated. Under photoautotrophic and heterotrophic conditions, the maximum EPS production 219.61?±?4.73 and 30.30?±?1.97?mg/L, respectively, occurred during the stationary phase. Under a mixotrophic condition, the maximum EPS production (290.50?±?2.21?mg/L) was observed during the early stationary phase. The highest specific EPS productivity (433.62?mg/g per day) was obtained under a photoautotrophic culture. The lowest specific EPS productivity (38.33?mg/g per day) was observed for the heterotrophic culture. The effects of glucose concentration, light intensity, and their interaction in mixotrophic culture on A. platensis EPS production were evaluated by means of 32 factorial design and response surface methodology. This design was carried out with a glucose concentration of 0.5, 1.5, and 2.5?g/L and at light levels of 50, 100, and 150???mol photons m^?2?s^?1. Statistical analysis of the model demonstrated that EPS concentration and EPS yield were mainly influenced by glucose concentration and that conditions optimizing EPS concentration were dissimilar from those optimizing EPS yield. The highest maximum predicted EPS concentration (369.3?mg/L) was found at 150???mol photons m^?2?s^?1 light intensity and 2.4?g/L glucose concentration, while the highest maximum predicted EPS yield (364.3?mg/g) was recorded at 115???mol photons m^?2?s^?1 light intensity and 1.8?g/L glucose concentration.     

维生素在丙酮酸过量合成中的重要作用

研究了烟酸、硫胺素、吡哆醇、生物素和核黄素对一株光滑球拟酵母(\%Torulopsis glabrata\%) WSH\|IP303以葡萄糖为碳源、以氯化铵为唯一氮源生产丙酮酸的影响。利用正交试验方法,确证了硫胺素是影响WSH\|IP303生产丙酮酸的最重要因素。在硫胺素浓度一定(0.01～0.015mg/L)的前提下,提高烟酸浓度有助于加快耗糖速度。当烟酸、硫胺素、吡哆醇、生物素和核黄素的浓度分别为8、0.015、0.4、0.04和01mg/L时,摇瓶发酵48h,丙酮酸产量和产率可分别达到52.4g/L和0525g/g。采用优化的维生素组合方式,进行2.5L罐分批发酵,在初糖浓度120g/L的条件下发酵57.5h,丙酮酸产量和产率分别达到69.4g/L和0593g/g,分别比摇瓶培养的最好结果提高了32.%和13%。     

高浓度糖发酵制备乙醇

以树干毕赤酵母为发酵菌株,混合糖（木糖、葡萄糖）为发酵底物,通过培养基和培养条件的改变来确定树干毕赤酵母高糖浓度发酵时所需的条件。研究结果表明：在24h发酵周期内初始木糖质量浓度为63．0g／L较适宜;在36h发酵周期内初始木糖质量浓度为72．0g/L较适宜。24h发酵周期内,在36．0g／L木糖中添加的葡萄糖质量浓度以54．0g/L为最佳,发酵结束乙醇质量浓度达32．9g／L;36h发酵周期内,添加的葡萄糖质量浓度以72．0g／L为最佳,发酵结束乙醇质量浓度为36．9g／L。以（NH4）2SO4为N源时较适合戊糖发酵制备乙醇,（NH2）2SO4的最佳质量浓度为1．1g／L。发酵前8h摇床转速为90r／min,后16h为150r／min,乙醇质量浓度较高,可达17．5g/L。     

Continuous hydrogen and butyric acid fermentation by immobilized Clostridium tyrobutyricum ATCC 25755: Effects of the glucose concentration and hydraulic retention time

The effects of the hydraulic retention time (HRT = 8, 10, 12 or 16.7 h) and glucose concentration (30, 40 or 50 g/L) on the production of hydrogen and butyrate by an immobilized Clostridium tyrobutyricum culture, grown under continuous culturing conditions, were evaluated. With 30 g/L glucose, the higher HRTs tested led to greater butyrate concentrations in the culture, i.e., 9.3 g/L versus 12.9 g/L with HRTs of 8 h and 16.7 h, respectively. In contrast, higher biogas and hydrogen production rates were generally seen when the HRT was lower. Experiments with different glucose concentrations saw a significant amount of glucose washed out when 50 g/L was used, the highest being 22.7 g/L when the HRT was 16.7 h. This study found the best conditions for the continuous production of hydrogen and butyric acid by C. tyrobutyricum to be with an HRT of 12 h and a glucose concentration of 50 g/L, respectively.     

Kalman filter based glucose control at small set points during fed-batch cultivation of Saccharomyces cerevisiae

A glucose control system is presented, which is able to control cultivations of Saccharomyces cerevisiae even at low glucose concentrations. Glucose concentrations are determined using a special flow injection analysis (FIA) system, which does not require a sampling module. An extended Kalman filter is employed for smoothing the glucose measurements as well as for the prediction of glucose and biomass concentration, the maximum specific growth rate, and the volume of the culture broth. The predicted values are utilized for feedforward/feedback control of the glucose concentration at set points of 0.08 and 0.05 g/L. The controller established well-defined conditions over several hours up to biomass concentrations of 13.5 and 20.7 g/L, respectively. The specific glucose uptake rates at both set points were 1.04 and 0.68 g/g/h, respectively. It is demonstrated that during fed-batch cultivation an overall pure oxidative metabolism of glucose is maintained at the lower set point and a specific ethanol production rate of 0.18 g/g/h at the higher set point.     

优化益生菌Lactobacillus casei Zhang高密度培养条件

为实现L. casei Zhang的高密度培养,在之前优化增殖培养基的基础上进一步寻求适宜该菌的培养条件。研究了不同中和剂、缓冲盐浓度、葡萄糖浓度、pH值控制、通气条件和补料分批培养对菌体在恒pH条件下发酵的影响,根据不同条件下菌体的比生长速率、菌体密度和活菌数情况,确定L. casei Zhang较适宜的高密度培养条件为：培养基葡萄糖浓度为80 g/L~100 g/L,以氨水为中和剂使pH保持5.9,采用间歇通氮气的方法保持环境厌氧,分批培养方式下37°C保温发酵10 h~12 h后,L. casei Zhang细胞干重达到7 g/L,活菌数3.5×1010 CFU/mL,比优化前提高7倍以上,能够满足益生菌制品生产要求的高菌体密度。