不同碳氮组合对小球藻异养培养油脂积累的影响

目的探讨不同碳氮组合对小球藻Chlorella pro tothecoides CS-41异养培养油脂积累的影响。方法以不同浓度葡萄糖为碳源,尿素为氮源,异养培养小球藻,采用干重法测定小球藻生物量,氯仿/甲醇法提取总脂,并采用GC-MS分析脂肪酸含量。结果小球藻最佳生长条件的碳氮组合配比为葡萄糖浓度40g/L,尿素浓度3g/L,此时小球藻生物量达最高,为9.1g/L,脂肪酸产率最大,为1.26g/L;总脂含量最高,为4.38g/L。结论获得了碳氮最佳配比,使小球藻脂肪酸含量提高到1.26g/L,为发酵扩大化培养小球藻制备生物柴油奠定了基础。     

有机碳源对异养小球藻生长、蛋白质和叶绿素含量的影响

研究了分别以葡萄糖、蔗糖和乙酸钠为唯一有机碳源异养养殖小球藻的生长、蛋白质和叶绿素合成。葡萄糖和乙酸钠培养的小球藻都出现了高浓度抑制生长的现象,小球藻在葡萄糖和乙酸钠中的最适生长浓度分别为25 g/L和35g/L,最大OD_(680)为5.45和1.93。但是小球藻的生物量随蔗糖浓度增大而增大,当蔗糖浓度为45g/L时出现了最大OD6_(80) 8.13。乙酸钠、蔗糖、葡萄糖培养42小时的小球藻的蛋白质含量分别为18%、15 %和14%,叶绿素含量分别为:17、10、8 mg/g。综合考虑小球藻生长、蛋白质及叶绿素合成,25 g/L葡萄糖是小球藻异养的最适有机碳源。     

培养基营养调控对小球藻Chlorella protothecoides胞内生化成分积累的影响

目的研究调控异养培养基中碳源和氮源浓度对小球藻Chlorella protothecoides(C.protothecoides)胞内生化成分积累的影响。方法分别以葡萄糖为碳源(尿素初始浓度为3 g/L,葡萄糖浓度分别为10、20、30、40、50 g/L)、尿素为氮源(葡萄糖初始浓度为30 g/L,尿素浓度分别为3.00、0.00、0.15、0.30、0.45、0.60 g/L),避光培养小球藻细胞,收集藻液,制备冻干藻粉。采用傅里叶变换红外光谱法(Fourier transform infrared spectroscgy,FTIR)测定小球藻胞内蛋白质、油脂和碳水化合物的变化。结果当培养基葡萄糖浓度为30 g/L,尿素浓度为3 g/L时,蛋白质吸收峰强度最大,相对含量较高,碳水化合物次之,油脂含量最低;与氮充足(3.00 g/L)条件下相比,氮缺失(0.00 g/L)条件下,蛋白质吸收峰强度骤然降低43.22%,油脂增高1.41倍,碳水化合物提高6.04%。结论培养基中不同碳、氮水平可实现胞内不同大分子组分(油脂、蛋白质和碳水化合物)产量的调控,满足不同层次的工业需求。     

响应面法优化米曲霉发酵豆粕产大豆肽的研究

采用单因素(豆粕、葡萄糖、磷酸氢二钾)实验与Box-Behnken设计相结合的方法对豆粕发酵产大豆肽的发酵培养基进行优化。根据影响因素与响应值之间的回归方程得最佳发酵培养基组分中豆粕浓度48.43 g.L-1、葡萄糖浓度11.89 g.L-1、磷酸氢二钾浓度0.43 g.L-1,预测结果:发酵液中大豆蛋白水解度为30.29%,经过三次平行实验,实验验证平均值为31.46%与预测值较吻合。利用高效液相色谱法对大豆肽的相对分子质量分布进行测定和分析,在最佳培养基条件下进行豆粕发酵,测得发酵液中大豆肽分子量分布集中在5000 Da以下,且所占比例达到90.32%。     

普通小球藻异养-光自养串联培养的培养基

采用单因素实验和均匀实验获得了适合于普通小球藻异养-光自养串联培养的培养基(HA-SK培养基),其关键是C/N比和保证足够的C, N供应. 采用该培养基在摇瓶中异养-光自养串联培养普通小球藻,异养培养结束时细胞密度达13.17 g/L,经过36 h光自养培养后藻体蛋白质和叶绿素含量分别达49.75%和30.17 mg/g. 用5 L生物反应器和1 L平板光生物反应器串联培养,藻细胞密度最高可达15.36 g/L,藻体蛋白质和叶绿素含量分别达54.78%和31.23 mg/g. 表明采用HA-SK培养基进行异养-光自养串联培养可实现普通小球藻的高密度高品质培养.     

产甘油假丝酵母细胞回用对甘油生产的影响

研究了产甘油假丝酵母细胞回用生产甘油的反复分批发酵。实验结果表明：第一级发酵培养基KH2PO4浓度为0.4 g·L-1，回用培养基的最适KH2PO4浓度为0.1 g·L-1，当上一批次发酵液中葡萄糖浓度降至10 g·L-1以下时，酵母细胞不经洗涤即可回用；经过15个批次的反复分批发酵过程，甘油的平均产量、平均得率和平均生产能力分别达到138.69 g·L-1、60.17%和2.31 g·L-1·h-1，分别比第一级发酵结果增加了15.74%、15.48%和39.16%；但回用至第15次时，菌体出现严重衰退，因此回用周期以12～14次为宜。     

异养条件下双酚基丙烷对小球藻生长特性的影响

在1 g/L葡萄糖和BPA共同异养培养普通小球藻的情况下,考察了BPA对小球藻生长特性影响和小球藻对BPA的去除效果。结果表明,在BPA浓度10 mg/L时,可促进小球藻的异养生长,而BPA浓度大于10 mg/L时,则表现为抑制作用;单位量普通小球藻对BPA的去除速率(比去除率)与BPA浓度呈正相关关系。因此当BPA浓度为50 mg/L、培养时间为24~48 h时,BPA的最大比去除速率为3.51×10~(-7)mg/(cell·h)。普通小球藻在不同浓度BPA与1 g/L葡萄糖混合培养条件下,其生长动力学中最大比生长速率μ_(max)、最大生物量B_f值皆随BPA浓度的增加呈现先增后减的变化趋势。     

神经网络和粒子群算法优化γ-氨基丁酸发酵培养基的研究

通过进行过的预实验,已知葡萄糖、L-谷氨酸钠和四水硫酸锰这三种发酵培养基成分对乳酸菌产GABA有重大影响.今运用神经网络和粒子群算法,对这三种成分进行了摇瓶发酵优化.首先,通过逐一单因素实验,来确定神经网络建模时三个输入参数的合适取值区域:葡萄糖10～30 g·L-1,L-谷氨酸钠50～80 g·L-1,四水硫酸锰2～20 mg·L-1.然后按照Hybrid设计进行实验,选取11组训练样本来建立人工神经网络模型,得到三种培养基成分浓度和GABA产量之间的关系模型.最后依赖于建立好的ANN模型,由PSO进行全局搜索寻优得到使GABA产量最大时的培养基浓度.在优化后的条件下,GABA积累浓度平均达到(33.42±1.35)g·L-1,较优化前提高96.5%.     

小球藻在蔗渣酶解液中的异养生长及其脂肪酸生成

在高温液态水处理的甘蔗渣酶解过程中添加Tween80可使聚糖转化率提高11.4%。根据蔗渣酶解液中糖的种类及含量,用葡萄糖、木糖和纤维二糖标准品模拟蔗渣酶解液组成配制成相应的混合糖培养基,同时配制仅含葡萄糖的培养基,在有、无Tween80和BG11(Blue-Green 11)的条件下,考察小球藻在不同培养基中的异养生长及脂肪酸生成。结果显示Tween80对小球藻的生长具有抑制作用,纤维二糖也会影响小球藻的生长;小球藻在添加BG11的葡萄糖培养基中的生物量最高,为1.97 g·L^-1,在添加BG11的蔗渣酶解液中的生物量高出未添加BG11的2倍,在含有Tween80和BG11的蔗渣酶解液中的总脂肪酸含量最高,达到6.90%,在所有培养基中产生的脂肪酸以C_16:0、C_18:1、C_18:3、C_20:1和C_20:4为主;培养基组成优化可进一步提高微藻生物量和油脂产量。     

大规模异养发酵培养小球藻USTB-01研究

采用异养小球藻USTB-01,分别在50、500 L和5 000 L发酵罐逐级放大进行异养发酵培养的优化控制研究.结果表明,随着小球藻异养培养过程中生物量的增大,按照3个不同阶段逐渐加大葡萄糖和硝酸钾(C/N质量比为20:1)分别作为碳源和氮源的流加量.可以大幅度提高小球藻USTB-O1的生长速度.72 h内,分别在50、500 L和5 000 L发酵罐进行异养发酵培养小球藻USTB-01过程中,都获得了质量浓度40 g/L以上的藻细胞干重,在培养物中保持低浓度的葡萄糖和硝酸钾在支持小球藻快速生长方面发挥了重要作用.无论在培养规模,还是在最终培养获得的藻生物量上,均取得了非常重要的研究进展.     

Enhanced lipid and biodiesel production from glucose‐fed activated sludge: Kinetics and microbial community analysis

An innovative approach to increase biofuel feedstock lipid yields from municipal sewage sludge via manipulation of carbon‐to‐nitrogen (C:N) ratio and glucose loading in activated sludge bioreactors was investigated. Sludge lipid and fatty acid methyl ester (biodiesel) yields (% cell dry weight, CDW) were enhanced via cultivation in activated sludge bioreactors operated at high initial C:N ratio (≥40:1) and glucose loading (≥40 g L^?1). Under C:N 70, 60 g L^?1 glucose loading, a maximum of 17.5 ± 3.9 and 10.2 ± 2.0% CDW lipid and biodiesel yields, respectively, were achieved after 7 d of cultivation. The cultured sludge lipids contained mostly C₁₆? C₁₈ fatty acids, with oleic acid consistently accounting for 40–50% of the total fatty acids. Microbial composition in activated sludge exposed to C:N 70 shifted toward specific gammaproteobacteria, suggesting their relevance in lipid production in wastewater microbiota and potential value in biofuel synthesis applications. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

A combo technology of autotrophic and heterotrophic denitrification processes for groundwater treatment

In this study,a sequential process (heterotrophic up-flow column and completely mixed membrane bioreactors) was proposed combining advantages of the both processes.The system was operated for 249 days with simulated and real groundwater for nitrate removal at concentrations varying from 25 to 145 mg·L-1 NO3-N.The contribution of heterotrophic process to total nitrate removal in the system was controlled by dozing the ethanol considering the nitrate concentration.By this way,sulfur based autotrophic denitrification rate was decreased and the effluent sulfate concentrations were controlled.The alkalinity requirement in the autotrophic process was produced in the heterotrophic reactor,and the system was operated without alkalinity supplementation.Throughout the study,the chemical oxygen demand in the heterotrophic reactor effluent was (23.7 ± 22) mg·L-1 and it was further decreased to(7.5 ± 7.2) mg·L-1 in the system effluent,corresponding to a 70％ reduction.In the last period of the study,the real groundwater containing 145 mg·L-1 NO3-N was completely removed.Membrane was operated without chemical washing in the first 114 days.Between days 115-249 weekly chemical washing was required.     

Pulmonary surfactant lipid synthesis from ketone bodies,lactate and glucose in newborn rats

The contribution of acetoacetate (AcAc), β-hydroxybutyrate (βOHB), lactate and glucose to pulmonary surfactant lipid synthesis in three-to five-day-old rats was measured. Minced lung tissue was incubated with³H₂O and [3-¹⁴C]AcAc, [3-¹⁴C]βOHB, [U-¹⁴C]lactate or [U-¹⁴C]glucose, and the radioactivity incorporated into surfactant lipids was measured. When expressed as nmol of substrate incorporated/g lung tissue per four hr, lactate was incorporated more rapidly than other substrates into total surfactant lipids and phosphatidylcholine (PC). There was no difference in the rates of incorporation of lactate, AcAc or glucose into disaturated PC (DSPC). Substrates other than glucose were incorporated almost exclusively into fatty acids, whereas 60–80% of glucose incorporated into surfactant phospholipids was found in fatty acids, with the remaining in glyceride-glycerol. When expressed as nmol acetyl units incorporated/g lung tissue per four hr, the rates of AcAc, lactate and glucose incorporation into total surfactant fatty acids were comparable. Glucose incorporation into DSPC and PC was greater than that of AcAc and lactate. When glucose was the only exogenous substrate added to the incubation medium, it contributed 37% of total surfactant fatty acids synthesized de novo. In the presence of other substrates, the contribution of glucose to de novo fatty acid synthesis dropped to 14–20%. In the presence of unlabeled glucose,¹⁴C-labeled AcAc, lactate and βOHB contributed 52%, 40% and 19%, respectively, of the total fatty acids synthesized de novo. The rate of βOHB incorporation into surfactant lipids was only about 50% that of other substrates and was accompanied by low activity of β-hydroxybutyrate dehydrogenase measured for newborn lung. These results demonstrate that AcAc and lactate are important precursors for surfactant lipids in neonatal rat lung.     

可溶型非融合血管生长抑制因子Kringle 5基因工程菌发酵培养和诱导表达条件的优化

在实验室试管培养条件下优化了基因工程菌E.coli BL21（DE3）pET15b/K5发酵产可溶型非融合血管生长抑制因子Kringle 5的培养基和诱导表达条件。经菌体干重测定和SDS-PAGE检测,确定最佳培养基（g.L-1）为：胰蛋白胨10.0,酵母提取物5.0,NaCl 10.0,葡萄糖6.0,NH4Cl 2.6,NaH2PO45.0,Na2HPO46.0;优化的诱导表达条件为：诱导剂浓度0.01mmol.L-1,诱导时间6h,诱导温度37℃,摇床转速220r.min-1。在优化的培养基和诱导表达条件下,菌体干重为1.8g.L-1,Kringle 5表达量为360mg.L-1,占总蛋白含量的20%,与基础LB培养基相比,Krin-gle 5表达量提高了1.18倍。     

利用肺炎克雷伯氏菌以葡萄糖和磷酸铵盐为底物生产2,3-丁二醇

1 INTRODUCTION Interest in microbial production of 2,3-butanediol has been increasing recently due to the extensive indus-trial application of this product. This colorless and odorless liquid with a high boiling point and a low freezing point is a potential valuable fuel additive. Its heating value is 27.198kJ·g-1, which is quite near the value of ethanol (29.055kJ·g-1). Besides, condensation of diol to methyl ethyl ketone (MEK) coupled with subsequent hydrogenation yields octane isom…     

Production of eicosapentaenoic acid byMortierella fungi

Mycelia of arachidonic acid-producing fungi belonging to the genusMortierella were found to be rich sources of 5,8,11,14,17-cis-eicosapentaenoic acid (EPA). Production of EPA by these fungi was observed only when they were grown at low temperature (6–16 C). EPA comprised 5–20% of the total extractable mycelial fatty acids in most strains tested. No significant accumulation of EPA was observed on incubation at high temperature (20–28 C), at which the other major mycelial C-20 fatty acid, arachidonic acid, was still efficiently produced. In a study on the optimization of the culture conditions for EPA production by a selected fungiM. alpina 20–17, a medium containing glucose and yeast extract as major carbon and nitrogen sources, respectively, was found to be suitable. Periodic feeding of glucose during growth of the fungus and cultivation at high temperature (20 C) during the early growth phase followed by temperature shift to 12 C were found to be effective at increasing mycelial yield and reducing cultural period, respectively. Under the optimal culture conditions, the EPA production reached 0.49 mg/ml of culture broth (29 mg/g dry mycelia). This value accounted for 13.5% of the total fatty acids in the extracted lipids. Other major fatty acids in the lipids were palmitic acid (6.0%, by weight), stearic acid (5.3), oleic acid (6.2), linoleic acid (3.0), γ-linolenic acid (3.5) and arachidonic acid (60.0). On leave from Suntory Ltd.     

利用响应面法优化出芽短梗霉As3．933产普鲁兰多糖发酵培养基

采用响应面分析法对出芽短梗霉As3．933产普鲁兰多糖的发酵培养基进行优化。首先利用Plackett-Bur-man实验筛选出影响普鲁兰多糖产量的主要因素为酵母膏、（NH4）zSO4和K2HPO4,再利用最陡爬坡实验逼近最大响应区域,最后通过Box-Behnken实验并运用Design-Expert8．0软件优化发酵培养基。确定优化培养基组成为：蔗糖62．5g·L-1,（NH4）2S040．67g·L-1,酵母膏2．84g·L-1,K2HPO47．12g·L-1,NaCl1．25g·L-1,MgS04·7H200．25g·L-1,pH值6．5,优化后的普鲁兰多糖产量达到22．29g·L-1,较初始液体发酵培养基（17．32g·L-1）提高了28．70％。     

Lipid body formation by <Emphasis Type="Italic">Thraustochytrium aureum</Emphasis> (ATCC 34304) in response to cell age

The heterotrophic marine protist, Thraustochytrium aureum produces substantial amounts of polyunsaturated fatty acids (PUFAs). In the present investigation, changes in the lipid and fatty acid profiles of T. aureum were studied according to the culture age. T. aureum was grown in artificial sea water medium for 10 days at 25 °C in shake culture condition. One to 10 day old cell samples were analyzed for cell biomass production, total lipid content, fatty acid profile and lipid body formation. In all the samples tested, total lipid production was found to be directly proportional to the dry cell weight of T. aureum. In the early phase of cell growth, cell biomass production, lipid content and glucose consumption were found to be higher. Thin layer chromatographic analysis (TLC) of lipids showed the presence of triacylglycerol (TAG; 169 mg/g, 90%), phospholipids (PL; 83 mg/g, 66%) and sterol (ST; 6 mg/g, 5%), which were recorded at maximum levels in the early growth phase of the cells. The composition of PUFAs and saturated fatty acids (SFAs) of the cell biomass and lipid class components (TAG and PL) was identified by gas chromatographic analysis (GC). In the early phase of cell growth, production of PUFAs in the total fatty acids was found to have attained maximum levels (61.3%) in which docosahexaenoic acid alone showed higher content of occurrence (99.0 mg/g in total lipid; 65.2 mg/g in TAG and 41.0 mg/g in PL). In the middle phase of cell growth, palmitic acid production was found to be higher (36.7 mg/g in total lipid; 31.3 mg/g in TAG and 12.6 mg/g in PL). Transmission electron microscopic studies of the cells showed the presence of a membrane around the lipid bodies in the early phase of cell growth. TAG and PL were actively involved in the formation of lipid bodies in the cells of T. aureum. Large-sized lipid bodies accumulated in 3 day old cells which were then fragmented into smaller bodies in the late growth phase.