微波对红法夫酵母的诱变效应的研究

利用微波诱变技术对红法夫酵母(Phaffia rhodozyma TY-Ⅰ)进行了诱变。结果表明,红法夫酵母TY-Ⅰ对微波辐照非常敏感(120s时菌株存活率只有4.67%)。在最佳处理时间100s,加盖冷却的条件下进行微波诱变、二苯胺推理筛选,最终筛选获得1株遗传稳定性良好,虾青素产量高的突变菌株TY-Ⅰ-8,虾青素含量较出发菌株提高了102.51%。     

Fed‐batch cultures of phaffia rhodozyma in xylose‐containing media made from wood hydrolysates

Abstract

Eucalyptus wood samples were treated with 3% aqueous sulphuric acid to obtain xylose‐containing solutions. The liquors from treatments were neutralized, contacted with charcoal and supplemented with nutrients to obtain culture media suitable for proliferating the carotenoid‐producing yeast, Phaffia rhodozyma NRRL Y‐17268. Two fed‐batch strategies (with continuous or intermittent feeding) were assayed as operational procedures for improving the carotenoid production. Biomass concentration of 10.3 g cells/L and volumetric pigment concentration of 8.15 mg total carotenoids/L (with 7.19 mg astaxanthin/L) were reached with continuous feeding, whereas improved results (30.6 g cells/L and 33.5 mg total carotenoids/L with 30.5 mg astaxanthin/L) were obtained with intermittent feeding.     

法夫酵母虾青素对油脂氧化稳定性的影响

为研究法夫酵母虾青素对油脂贮存稳定性的影响,以自制的法夫酵母虾青素为抗氧化剂,以过氧化值(POV)和酸值(AV)为考察指标,通过与叔丁基对苯二酚(TBHQ)、丁基羟基茴香醚(BHA)、二丁基羟基甲苯(BHT)等常用油脂抗氧化剂进行比较,研究其抗氧化活性。Schaal加速氧化实验结果表明,法夫酵母虾青素具有抗油脂氧化的作用,尤其对茶油的作用效果明显,抗氧化能力略高于TBHQ,明显高于BHA和BHT,并呈明显的量效关系,当添加量达到0.015%时,具有较好的抗氧化效果。法夫酵母虾青素是天然抗氧化剂,具有作为高品质茶油抗氧化剂的潜在应用价值。     

Mathematical model for Phaffia rhodozyma growth using peat hydrolysates as substrate

The potential of peat hydrolysates for the production of astaxanthin from Phaffia rhodozyma yeast biomass in continuous fermentation was studied. Chemostat fermentations of the yeast were performed using peat hydrolysates as substrate. Kinetic parameters were calculated for the growth of the yeast and the biomass productivity was determined using mathematical models. A low maximum specific growth rate (μ_max=0·08 h⁻¹) and a high Monod constant (Ks=26·2×10³) were obtained for this substrate. The low maintenance energy requirement found, 0·020 g (gh)⁻¹, confirms the aerobic metabolism of the yeast with this substrate. Under selected conditions, a biomass productivity of 0·108 g (lh)⁻¹ and an astaxanthin productivity of 0·046 mg (lh)⁻¹ were obtained. The biomass produced had a high protein and astaxanthin content (490±8 g kg⁻¹ and 0.43±0.07 g kg⁻¹, respectively), indicating that it can be used as a feed additive. © 1998 SCI.     

不同氮源对红发夫酵母培养的影响

本文研究了不同氮源及浓度对红发夫酵母生长及虾青素积累的影响.结果表明氮源最佳浓度为6.5g/L.在所研究氮源中,酵母膏是最好的单一氮源,虾青素产量达到3688μg/L.以硫酸铵、尿素和硝酸钾为单一氮源时,虾青素产量分别是2003、1718和1181μg/L,远远低于酵母膏.当采用尿素和硝酸钾作为混合氮源(4∶1)时,虾青素产量达到2333μg/L.     

应用HMG-CoA还原酶抑制剂筛选虾青素高产突变株

研究了HMG-CoA还原酶抑制剂辛伐他汀对法夫酵母生长及其虾青素合成的影响,实验结果表明,当辛伐他汀浓度在4·78×10-6mol/L时对酵母细胞的生长的抑制表现不明显,但对虾青素合成具有显著的抑制作用。以此浓度作为筛选浓度,经亚硝基胍(NTG)诱变后,通过辛伐他汀平板初筛与摇瓶复筛,获得较高虾青素产率的突变株。实验结果表明,菌体生物量、类胡萝卜总量和虾青素产量都有明显的提高,其中NPX-3_05突变株类胡萝卜总量与虾青素产量分别达到3·823、2·755mg/L,比出发菌株依次提高了163%、143%(1·453mg/L、1·134mg/L)。菌株NPX-3_05经连续发酵5次的稳定性实验表明其性状稳定。目标产物经HPLC定性分析,确定为反式虾青素。因此,以辛伐他汀等HMG-CoA还原酶抑制剂作为选择压力,对虾青素高产突变株的筛选上具有较好的“筛分”能力。     

红发夫酵母生长和虾青素积累培养参数的优化

在摇瓶中应用二次正交旋转组合设计研究了不同培养时间、接种量、种子液培养时间和装液量对红发夫酵母Phaffia rhodozyma As2.1557生长和细胞虾青素含量的影响,并对培养参数进行了优化.结果表明:接种量、培养时间和装液量对Phaffia rhodozyma As2.1557生长和虾青素积累有显著影响,最佳生长参数为:装液量每瓶30 mL(250 mL摇瓶),摇瓶培养时间96 h,接种量12%,种子培养时间60 h.     

两阶段法培养红法夫酵母生产虾青素

在法夫酵母生长过程中,培养基组成是影响细胞生长和虾青素产量的重要因素。文中通过正交设计和响应面优化方法分别对红法夫酵母生长阶段培养基和虾青素合成阶段的培养基进行了优化研究。结果表明,碳源和氟源浓度对红法夫细胞的生长及虾青素的合成有明显影响,浓度为20 g/L的葡萄糖有利于细胞的生长;而50 g/L左右的葡萄糖和高C/N有利于虾青素的合成。在此基础上提出了两阶段发酵方案。经过两阶段发酵,红法夫酵母生物量和虾青素产量达到16.8 g/L和15.015 mg/L,分别比分批培养提高了56.3%和28.7%。     

碳氮比对Phaffia rhodozyma CS0217 虾青素合成的影响

碳氮比(C/N)对Phaffia rhodozyma CS0217 虾青素的合成有重要影响,摇瓶实验结果表明：随着C/N 的降低,虾青素含量显著降低,当C/N 为4.5:0.1 时,每克干细胞虾青素的最高含量为2.48mg/g;在高C/N 条件下酵母发芽率低,控制酵母发芽率小于0.5,有利于虾青素的合成;进一步通过添加放线菌酮发现,由β - 胡萝卜素向虾青素转化的关键酶可能在细胞培养的对数生长期受到抑制。