过表达酰基蛋白硫酯酶促进产油真菌卷枝毛霉脂肪酸合成

本实验以卷枝毛霉为研究对象,探讨了酰基蛋白硫酯酶在其脂质合成与代谢中的作用.通过同源重组的方法在卷枝毛霉中过表达了酰基蛋白硫酯酶TE21,研究了重组菌株在发酵过程中对碳源、氮源的消耗情况以及生物量、脂肪酸含量的变化.结果 表明:过表达酰基蛋白硫酯酶能提高卷枝毛霉的总脂肪酸含量,并使游离脂肪酸的含量提高了1.3倍.     

橘林油脂酵母发酵条件的初步研究

以橘林油脂酵母（Lipomyces kononenkoae CICC1714）为实验材料,通过设计单因素实验,确定了摇瓶发酵培养的最佳产油条件为：氮源为硫酸铵,碳源为葡萄糖,培养温度28℃,接种量10%,初始pH值为7.0,最适碳氮比为99。优化后批次发酵的生物量为7.01g/L,油脂含量15.91%,油脂产量1.12g/L。经半连续发酵后最终的生物量为24.13g/L,油脂产量为3.06g/L。     

裂殖壶藻发酵过程中脂肪酸合成代谢规律及其影响因素探讨

探究裂殖壶藻(Schizochytrium sp.)A3-9在不同发酵条件下生物量和脂肪酸含量的变化规律。结果显示,初始葡萄糖含量90 g/L,碳氮比8时最有利于裂殖壶藻生物量积累,此时生物量可达38.12 g/L,较对照组提高了104.59%;装液量220 m L/500 m L,柠檬酸添加量1.6 g/L,碳氮比23时总脂肪酸的积累可达47.16 g/100 g藻粉,较对照组提高了40.25%。不同发酵条件下裂殖壶藻胞内脂肪酸的代谢流量分布分析显示,初始葡萄糖含量90 g/L,碳氮比8,装液量60 m L/500 m L,柠檬酸和苹果酸添加量1.6 g/L时最有利于乙酰辅酶A(CoA)流入聚酮合酶(PKS)途径合成不饱和脂肪酸,此时不饱和脂肪酸与饱和脂肪酸含量之比可达1.15,相比对照组提高了21.28%;而当碳氮比14.75,装液量220 m L/500 m L时二十二碳六烯酸(DHA)与二十二碳五烯酸(DPA)含量之比可达6.82,较对照组提高了3.02%。     

佐夫色绿藻高产虾青素的诱导条件及发酵工艺优化

本研究了不同诱导条件及光发酵罐培养工艺对混养佐夫色绿藻的影响,通过参数优化提高了藻细胞生物量和虾青素积累量。本研究首先系统地比较了在摇瓶系统中不同混合碳源和过氧化氢浓度对佐夫色绿藻的生长和虾青素积累的影响,并在光发酵罐中研究了恒定高光强、低光强-高光强以及低光强-高光强-补加过氧化氢三种不同发酵工艺对佐夫色绿藻积累虾青素的影响。结果表明:采用20 g/L葡萄糖和2.50 g/L醋酸钠作为混合碳源取代单一碳源,可以获得最高6.50 g/L生物量,并且添加107.50 mg/L过氧化氢可以将虾青素含量提高到3.23 mg/g,产量最高为72.47 mg/L,是空白组虾青素产量的1.80倍,有效促进了佐夫色绿藻细胞生长和虾青素积累。在5 L光发酵罐中,以20 g/L葡萄糖和2.50 g/L醋酸钠作为混合碳源培养佐夫色绿藻,通过低光强-高光强-补加过氧化氢的组合方式,可获得较优的虾青素含量(3.82 mg/g)和产量(41.41 mg/L),相较于恒定高光强培养,分别提高了36.92%和92.96%。本研究通过诱导条件和发酵工艺优化有效提高了混养佐夫色绿藻生物量和虾青素产量,为利用光发酵罐培养色绿藻生产虾青素提供基础。     

裂殖壶菌发酵产DHA油脂的生产工艺优化

采用磷酸香草醛法实时监测裂殖壶菌发酵产DHA油脂的积累情况,对裂殖壶菌的基础发酵工艺进行了优化。得到裂殖壶菌生长和油脂积累的最佳培养基配方为:葡萄糖30 g/L,玉米浆粉6 g/L,蛋白胨4 g/L,硝酸钠3.6~3.9 g/L,海水晶15 g/L;在50 L的发酵罐中采用后期流加一定量的葡萄糖提高碳氮比来提高油脂积累外,通过流加3.0 g/L的大豆油来刺激菌体生长,最终经过72 h的流加培养,菌体湿重达到200 g/L,总油脂含量达到60%以上,油脂脂肪酸组成中的DHA含量占22%左右。     

雅致放射毛霉产孢培养基及产孢条件研究初报

雅致放射毛霉作为一种重要的发酵真菌,广泛应用在霉豆渣发酵和腐乳酿造中,研究其产孢条件对制作直投式菌种具有重要意义。初步筛选了雅致放射毛霉产孢的6种合成培养基和8种天然培养基,同时对碳源、氮源以及碳氮比对雅致放射毛霉产孢的影响进行了研究。实验表明,MEA培养基、小麦麸皮培养基上其孢子产量较高,分别为第9天的1.664×107cfu/mL和第6天的2.04×107cfu/cm2(成活率为51.67%)。以麦芽糖、淀粉、葡萄糖和硝酸钾、硫酸铵分别为碳氮源有利于其产孢。在0.05水平上碳氮比对雅致放射毛霉产孢影响显著,碳源对其产孢影响不显著,碳源为1.92g/L,碳氮比为10:1条件下雅致放射毛霉孢子产量最高。     

马铃薯淀粉水解条件优化及油脂酵母培养研究

以马铃薯淀粉为底物,葡萄糖含量为评价指标,通过响应面法优化淀粉酶解工艺,将水解液用于发酵生产微生物油脂。最佳酶解条件为马铃薯淀粉质量浓度20 mg/mL,加酶量为干淀粉质量3.2%,α-淀粉酶、葡萄糖淀粉酶的质量比2.2∶1,pH 4.1,酶解时间4.1 h,得到最高葡萄糖含量为15.06 mg/mL。向此水解液中添加一定氮源和无机盐用于油脂酵母菌株Y004-2培养,在250 mL三角瓶中其生物量为14.43 g/L,油脂产量5.16 g/L,在5.0 L发酵罐中生物量为14.27 g/L,油脂产量5.10 g/L,其生物量和油脂产量均略高于以葡萄糖为碳源;且菌株Y004-2在以马铃薯淀粉水解液为碳源的培养基中所得油脂的组成与以葡萄糖为碳源的培养基中所得油脂的脂肪酸组成相同。     

不同碳源对粘性红酵母WP3生长及类胡萝卜素产量的影响

研究了不同碳源及含量对粘性红酵母（Rhodotorula mucilaginosa）WP3生长及类胡萝卜素积累的影响。结果表明,在所研究的碳源中,葡萄糖有利于生长,而果糖有利于类胡萝卜素积累。在碳源含量为40 g/L,果糖和葡萄糖比例为7∶1,果糖含量为35 g/L,葡萄糖含量为5 g/L时,粘性红酵母WP3的生物量为7.94,类胡萝卜素产量达到556.84 μg/L,对粘性红酵母生长及类胡萝卜素合成有利。     

深黄被孢霉产脂的研究

深黄被孢霉在限制氮源的情况下培养,其生物量得到了显著提高,达到35.9 g/L,葡萄糖利用率也大大增加,甚至培养基中葡萄糖起始浓度可以达到100 g/L。氮源耗尽后,菌体中重要的脂肪酸得到积累,其油脂含量为50%~55%,微生物油脂产量为18.0 g/L产脂培养基。每消耗1 g葡萄糖,总的生物量增加0.34 g,干菌体中的油脂含量增加0.17 g。油脂中的γ-亚麻酸含量为3.5%左右,即16~19 mg/g干菌体,最多的甚至可以达到0.801 g/L发酵培养基。     

利用Crypthecodinium cohnii高密度发酵生产DHA的流加策略研究

利用流加策略实现了隐甲藻(Crypthecodinium cohnii)生产DHA的高密度发酵。根据隐甲藻间歇式发酵的特性,探讨最佳补料时间及流加液中最佳碳氮比,结果表明,在葡萄糖浓度降至4g/L左右时流加碳氮比为30∶1的营养液对隐甲藻的生长和脂肪酸积累最有利。根据以上结果,初始葡萄糖浓度25g/L,采用5d连续发酵多次流加策略,细胞干重达6.37%,DHA产量为4.08g/L。     

混合糖发酵产油脂酵母菌的筛选

对6株产油脂酵母利用葡萄糖、木糖及不同比例混合糖(葡萄糖与木糖)发酵的菌体生长和产油特性进行研究,筛选到一株能够转化混合糖的高产油脂酵母JM-D.该菌株在混合糖比例为3∶1的条件下发酵120h,菌体油脂含量可达23.38％,油脂产量可达2.7g/L;菌体油脂中饱和脂肪酸含量占脂肪酸总量的49.2％;混合糖比葡萄糖更容易被转化生成饱和脂肪酸含量较多的油脂.     

Effect of Culture Variables on Mycelial Arachidonic acid Production by Mortierella alpina

Effect of culture conditions on biomass, lipid, and arachidonic acid production was investigated in the oleaginous fungus Mortierella alpina CBS 528.72 under shake flask conditions. Several factors have been found to affect the biomass buildup and lipogenesis in this fungus, complicated by the fact that different strains demonstrate varying optimization conditions. Growth, lipid accumulation, and arachidonic acid production in the strain investigated were influenced by media, pH, temperature, carbon source, nitrogen source, etc. The results indicated that the most effective medium for growth and arachidonic acid production was glucose yeast extract medium. The optimum pH and temperature were found to be 6.5 and 28°C, respectively. On the same weight basis, glucose was the most efficient carbon source for biomass and lipid production in this fungal strain which yielded 6.8 g/L dry biomass and 40.2% (w/w) total lipid after 7 days of cultivation. Maximum arachidonic acid (ARA) production of 40.41% achieved in rhamnose-containing media was not concomitant with higher biomass and lipid yields. Efficacy of organic carbon sources, viz, yeast extract and peptone over inorganic sources like sodium nitrate, ammonium sulfate, ammonium chloride, etc, was established in the present study. M. alpina CBS 528.72 grown in peptone acquired the highest lipid content (42.0% (w/w)). However, the ARA content (28.74%) proved to be significantly less than that grown in yeast extract (35.28%). Furthermore, it was found that the biomass and ARA production declined drastically in a medium with vegetable oils as the sole carbon source but triggered the lipogenic pathway leading to higher accumulation of total lipids. Under the ideal conditions mentioned above, the maximum biomass, total lipid, and arachidonic acid production were 6.8 g/L, 41.6%, and 35.28% total fatty acid, respectively, in shake flask system.     

利用廉价原料生产聚谷氨酸的研究

目的 降低聚谷氨酸的生产成本.方法 从聚谷氨酸发酵所需的氮源和碳源出发,分别研究了小麦水解蛋白、豆饼粉、豆粕粉、玉米蛋白、玉米浆等有机氮源和甘蔗糖蜜、甜菜糖蜜、葡萄糖蜜、玉米糖蜜等碳源对聚谷氨酸发酵产量的影响,在此基础上通过单因素实验优化了玉米浆、硫酸铵、甜菜蜜、谷氨酸钠的添加量,最后通过发酵罐发酵比较了优化后的工艺与...     

发酵条件对发酵性丝孢酵母脂肪酸组成的影响

通过摇瓶发酵，研究了温度、摇瓶转速、碳源种类和浓度对发酵性丝孢酵母（Trichosporom fermentans）脂肪酸组成的影响。气相色谱法分析结果表明，较高发酵温度能提高菌体油脂的脂肪酸饱和程度，此条件下饱和脂肪酸含量占脂肪酸总量的49．1％：摇瓶转速高有利于菌体油脂不饱和脂肪酸的生成；木糖浓度为100g／L时菌体油脂中饱和脂肪酸含量最高，占脂肪酸总量的50．4％；木糖比葡萄糖更容易被转化生成饱和脂肪酸含量较多的油脂。菌体脂肪酸组成包括肉豆蔻酸、棕榈酸、棕榈油酸、硬脂酸、油酸和亚油酸，其中棕榈酸和油酸含量较高。     

溶氧对耶氏解脂酵母油脂积累和柠檬酸分泌的影响

产油耶氏解脂酵母能将培养基中过量的碳源转化为油脂储存于细胞内并分泌大量的柠檬酸。在耶氏解脂酵母发酵过程中通过关联搅拌转速和通气量调控培养基中的溶氧含量处于5%、10%、20%、30%和不控制5种水平,来研究溶氧对其油脂积累和柠檬酸分泌的影响。结果表明,随着发酵培养基中溶氧的增加,耶氏解脂酵母细胞内油脂含量和柠檬酸分泌量均有所增加,且不控制培养基中溶氧时,细胞内油脂含量和柠檬酸产量均最高,油脂含量达到细胞干重的11.62%(w/w),柠檬酸产量达到21.0 g/L。培养基中不同的溶氧含量还会影响油脂的脂肪酸组成,高溶氧能够促进油酸含量的增加,溶氧不控制时油酸的含量最高,达到48.62%。本研究为耶氏解脂酵母产脂发酵培养过程中溶氧的控制提供了重要的实验依据。     

培养条件对蛋白核小球藻生长及油脂合成的影响

以富油蛋白核小球藻为出发藻株,研究自养、异养和混养培养模式对小球藻生物量和油脂含量的影响,以及异养发酵培养基葡萄糖质量浓度、氮源种类及质量浓度对小球藻生长的影响。结果表明,与自养和混养培养模式相比,采用异养发酵方式培养蛋白核小球藻可获得最大的生物量和油脂含量。通过气相色谱法测得异养蛋白核小球藻油主要脂肪酸为棕榈酸(36.07%)、油酸(34.26%)、亚油酸(20.17%)和亚麻酸(6.12%)。经单因素试验优化得到最适蛋白核小球藻生长异养发酵培养基的葡萄糖质量浓度为60 g/L,最适的氮源为酵母粉,质量浓度为4 g/L,在此条件下经192 h发酵,蛋白核小球藻生物量可达12.43 g/L,油脂产量为5.45 g/L。研究结果表明,异养发酵培养获得的蛋白核小球藻油是一种潜在且可再生的新油源。     

不同碳、氮源质量浓度对高山被孢霉脂质积累及SNF1复合体转录调控的影响研究

高山被孢霉(M.alpina)是一株具有较强脂质合成能力的产油微生物,其脂质积累受培养基中碳、氮源调控。探究了不同葡萄糖和酒石酸铵质量浓度对M.alpina生长及脂质积累的影响,并进一步研究不同碳、氮源质量浓度下M.alpina SNF1复合体各亚基的转录水平。结果表明:初始酒石酸铵质量浓度一定时,M.alpina脂肪酸含量随碳氮比(C/N)的增加而提高,C/N为24.6时其脂肪酸含量比C/N为4.6时提高42.6%,初始葡萄糖质量浓度一定时,氮源限制下(C/N=76.7)M.alpina脂肪酸产率达到2.6 g/L,是氮源存在时的1.5~3.2倍,与葡萄糖相比氮源水平对M.alpina脂质积累影响更为显著。氮源一定时高葡萄糖质量浓度(C/N=24.6)下SNF1复合体各亚基转录水平比对照组提高13.9~20.5倍;而氮限制导致的高C/N同样可促进其转录水平的提高。高C/N和氮限制均属于营养失衡信号,说明M.alpina SNF1转录水平的变化是其对胞外营养水平的响应方式,并与脂质积累水平具有相关性。     

Enhancement of microbial oil production by alpha-linolenic acid producing Yarrowia lipolytica strains QU22 and QU137

Microbial oils enriched in essential polyunsaturated fatty acids can be used as nutritional complements. In order to improve the lipid yields and lipid profiles of 2 Yarrowia lipolytica strains, the effects of medium components and culture conditions were investigated using shake flasks. Under optimized conditions (cultivation for 3 days at 25oC and 150 rpm, using peptone as a nitrogen source and glucose as a carbon source), the biomass, lipid yield, and lipid content reached 6.75 g/L, 3.48 g/L, and 51.55% for Y. lipolytica QU22, and 6.85 g/L, 3.52 g/L, and 51.38% for Y. lipolytica QU137, respectively. Using a shaking speed of 150 rpm, unsaturated fatty acids constituted 87.96% (QU22) and 87.08% (QU137) of the total lipids produced by these strains, with 9.52 and 7.86% of alpha-linolenic acid, respectively. The strains are suitable candidates for fermentation processes involving essential polyunsaturated fatty acid (PUFA) production.     

EFFECTS OF STRUCTURED LIPID CONTAINING OMEGA-3 AND MEDIUM CHAIN FATTY ACIDS ON SERUM LIPIDS AND IMMUNOLOGICAL VARIABLES IN MICE

Diets supplemented with enzymatically produced structured lipid (SL) containing n-3 polyunsaturated fatty acids (eicosapentaenoic and docosahexaenoic) and caprylic acid or soybean oil (16.7 g/100 g) were fed to 4 to 6 week old female mice for 21 days. The effect of the diets on serum lipids (HDL-cholesterol, LDL-cholesteol. total cholesterol, triacylglycerol) and glucose concentrations were determined. The concentration of total cholesterol (49%), LDL cholesterol (35.4%) and triacylglycerol (53.2%) were significantly lowered in SL-fed group. The body weight gain in mice fed the soybean oil diet (control group) was significantly (p<0.05) greater than that in mice fed the SL diet after 21 days. The proportion of total T-cells (Thy 1.2⁺), T helper cells (CD⁴⁺), and T cytotoxic-suppressor cells (CD8⁺) in spleen were not significantly different between the two dietary groups as determined by flow cytometry.     

响应面法优化顶头孢霉发酵稻草秸秆产头孢菌素C的培养基

该研究用稻草秸秆代替标准发酵培养基中的碳源,利用顶头孢霉（Cephalosporium acremonium）发酵产头孢菌素C,并通过响应面法优化培养基组分。结果表明,头孢霉发酵产头孢菌素C的最佳发酵培养基成分为水解葡萄糖35 g/L、棕纤维素46 g/L、玉米浆38 g/L、纤维素酶0.8%、豆油25 g/L、硫酸铵10 g/L。在此优化培养基下,头孢霉发酵所产头孢菌素C的效价达298.34 U/mL,为标准发酵培养基效价的96.69%。由此可知,秸秆棕纤维素作为原料丰富且廉价的碳源替代物,可完全应用于头孢菌素C的发酵生产。