高山被孢霉生长和产脂的影响因素分析

为探究影响高山被孢霉生长和产脂的因素,分析不同初始葡萄糖质量浓度、活化次数、接种量、装液量、发酵时间、菌球打碎时间等条件下高山被孢霉生长和产脂特点。结果表明,初始葡萄糖质量浓度、装液量和发酵时间对菌株生长和产脂的影响最为显著,且初始葡萄糖质量浓度与花生四烯酸的产量呈负相关性。根据不同条件下菌株生长和产脂情况,得到高山被孢霉最佳培养条件为:菌株活化3次,用高速分散机8 000 r/min打碎20 s至均匀状态,按2%～3%(体积分数)接种量接入初始葡萄糖质量浓度为50 g/L、装液量为20%(体积分数)的发酵培养基中,200 r/min、28℃培养8. 5 d。     

Optimisation of Spirulina platensis convective drying: evaluation of phycocyanin loss and lipid oxidation

The aim of the study was the optimisation of Spirulina platensis drying on convective hot air through the response surface methodology. The responses were thiobarbituric acid (TBA) and phycocyanin loss percentage values in final product. Experiments were carried out in perforated tray drier with parallel air flow, and the wet samples thickness and drying air temperatures were in range of 3–7 mm and 50–70 °C, respectively. The statistical analysis showed significant effect (P < 0.05) for air temperature and samples thickness. In the best drying condition, 55 °C and 3.7 mm, presented the phycocyanin loss percentage and the TBA values of approximately 37% and 1.5 mg_MDA kg^?1, respectively. In this drying condition, the fatty acids composition of the microalgae Spirulina did not show significance difference (P > 0.05) in relation to fresh biomass. The lipid profile of dried product presented high percentage of polyunsaturated fatty acids (34.4%), especially the gamma‐linolenic acid (20.6%).     

10种热带富油微藻生物量、总脂含量 及脂肪酸组成分析

微藻生物柴油是当前生物能源中最具发展潜力的一种新型能源,为更好地开发微藻生物柴油,筛选出适合制备生物柴油的富油微藻,以10种热带富油微藻为研究对象,对其生物量、总脂含量及脂肪酸组成进行分析。通过甲醇-氯仿(体积比为2∶1)称量法测定10种热带富油微藻中的总脂含量,将从微藻提取的油脂经过甲酯化反应后,采用气相色谱-质谱联用(GC-MS)分析油脂中脂肪酸组成及含量。结果表明,10种热带富油微藻中Chlorella vulgaris CJ15和Desmodesmus sp.WC08更适合制备生物柴油。     

气生微藻Heveochlorella sp. Yu作为生物柴油生产原料的特性研究北大核心CSCD

为了拓展生物柴油原料来源,以气生微藻Heveochlorella sp. Yu为研究对象,通过测定其生长曲线、生物量、油脂产率、沉降率等,对其作为生物柴油生产原料的特性进行研究。结果表明,培养后气生微藻Heveochlorella sp. Yu的生物量为4.14 g/L,油脂含量为39.43%,油脂产率为181.38 mg/(L·d),2 h的自然沉降率为65.28%(可大幅浓缩水体,降低微藻的采收成本)。此外,该微藻能够产生γ-氨基丁酸(GABA),含量为9.50 mg/g。气生微藻Heveochlorella sp. Yu具有成为生物柴油原料的潜力,具有微藻油脂的开发价值。     

Characterization of phosphatidic acid phosphatase activity in the oleaginous yeast Yarrowia lipolytica and its role in lipid biosynthesis

Phosphatidic acid phosphatase (PAP) catalyses the committed step of triacylglycerol (TAG) biosynthesis and thus regulates the amounts of TAG produced by the cell. TAG is the target of biotechnological processes developed for the production of food lipids or biofuels. These processes are using oleaginous microorganisms like the yeast Yarrowia lipolytica as the TAG producers. Thus manipulating key enzymatic activities like PAP in Y. lipolytica could drive lipid biosynthesis towards TAG production and increase TAG yields. In this study, PAP activity in Y. lipolytica was characterized in detail and its role in lipid biosynthesis was addressed. PAP activity increased 2.5‐fold with the addition of Mg²⁺ (1 mm ) in the assay mixture, which means that most of the PAP activity was due to Mg²⁺‐dependent PAP enzymes (e.g. Pah1, App1). In contrast, N‐ethylmaleimide (NEM) potently inhibited PAP activity, indicating the presence of NEM‐sensitive PAP enzymes (e.g. App1, Lpp1). Localization studies revealed that the majority of PAP activity resides in the membrane fraction, while the cytosolic fraction harbours only a small amount of activity. PAP activity was regulated in a growth‐dependent manner, being induced at the early exponential phase and declining thereafter. PAP activity did not correlate with TAG synthesis, which increased as cells progressed from the exponential phase to the early stationary phase. In stationary phase, TAG was mobilized with the concomitant synthesis of sterols and sterol esters. These results provide the first insights into the role of PAP in lipid biosynthesis by Y. lipolytica. Copyright © 2016 John Wiley & Sons, Ltd.     

蛋黄油脂质组分的提取分离与脂肪酸组成分析

为将蛋黄油分为不同性质的脂质组分,并建立一种从蛋黄粉中提取分离蛋黄油的方法,利用溶剂萃取法从蛋黄粉中提取蛋黄油,以出油率、碘值和皂化值为指标筛选蛋黄油提取萃取剂、去磷脂蛋黄油提取萃取剂以及去磷脂蛋黄油分离萃取剂;对除磷脂外的3种蛋黄油组分进行脂肪酸组成分析。结果表明：以无水乙醇作为一次提取萃取剂从蛋黄粉中得到醇提蛋黄油与醇提蛋黄粉,用石油醚对醇提蛋黄粉进行二次提取得到石油醚蛋黄油,采用丙酮以料液比1∶12分离醇提蛋黄油中磷脂并得到去磷脂醇提蛋黄油,以乙腈-乙醇(体积比1∶1)分离去磷脂醇提蛋黄油得到上层蛋黄油与下层蛋黄油;蛋黄粉中的脂质被分为4个组分,其中上层蛋黄油占18.43%,下层蛋黄油占40.62%,石油醚蛋黄油占9.78%,磷脂占31.16%;3种液态蛋黄油中,上层蛋黄油不饱和度最高,多不饱和脂肪酸占比最大(20.52%),还含有较多ω-3多不饱和脂肪酸等具有保健功效的脂肪酸。该方法可分离出蛋黄油中高多不饱和脂肪酸和较高保健功效脂肪酸占比的液态脂质。     

禾本红酵母M124产脂能力及其油脂脂肪酸组成分析

采用索氏提取法提取禾本红酵母M124(Rhodotorula graminis M124)的菌体油脂,测定了其产脂能力,并采用气相色谱-质谱联用法(GC-MS)测定了其脂肪酸组成.结果表明,禾本红酵母M124的产脂能力较强,油脂含量达菌体干重的53.64%,脂肪酸组成较为特殊,10-十八碳烯酸占脂肪酸总量的80.08%.     

比较转录组解析氮限制对微藻Ankistrodesmus sp.HJ12油脂和淀粉积累的分子调控机制

为明确微藻油脂与淀粉代谢过程中是否存在相互竞争与转化关系,以微藻Ankistrodesmus sp.HJ12为实验材料,对不同氮浓度培养条件下的微藻Ankistrodesmus sp.HJ12生物量、油脂含量和淀粉含量进行测定,并进行比较转录组研究,探讨其油脂和淀粉积累相关影响及分子调控机制。结果表明：氮浓度对该藻株油脂和淀粉积累具有显著影响,且油脂与淀粉积累呈显著负相关关系;培养基中添加氮源时,微藻Ankistrodesmus sp.HJ12油脂含量显著高于无氮源条件,油脂含量最高时的氮浓度为7.6 mmol/L;无氮源时,其淀粉含量最高;比较转录组研究发现,促进微藻Ankistrodesmus sp.HJ12油脂积累的主要因素可能是脂肪酸合成途径、糖酵解途径与淀粉分解代谢途径的增强,为脂肪酸的合成提供了更多的乙酰-CoA和碳源,从而促进了脂肪酸的合成;挖掘得到4个调控脂质合成代谢的关键基因ACACA、α-AMY、PDC和adh,采用实时荧光定量PCR(RT-qPCR)验证基因表达差异变化,结果与转录组分析差异一致。研究结果可为进一步了解微藻脂质合成代谢的分子机制提供一定的参考,同时...     

Optimisation of the medium composition for production of protease and soybean peptides by Bacillus subtilis SHZ using response surface methodology

Responses surface methodology was employed to enhance the production of protease and soybean peptides by Bacillus subtilis SHZ. For screening of medium composition significantly influencing protease and soybean peptides yield, the two-level Plackett–Burman design was used. Among thirteen variables tested; KH₂PO₄, glucose and defatted soybean flour (DSF) were selected based on their high significant effect on both protease activity and soybean peptides yield. Then, a three-level Box–Behnken design was employed to optimise the medium composition for the production of the protease and soybean peptides in submerged fermentation. Mathematical models were then developed to show the effect of each medium composition and their interactions on the production of protease and soybean peptides. The model estimated that, the maximal protease activity (320 ± 1 U mL⁻¹) could be obtained when the concentrations of glucose, KH₂PO₄, DSF were set at 8–9 g L⁻¹, 2–3 g L⁻¹, 55–65 g L⁻¹, respectively; while a maximal yield of soybean peptides (8.5 ± 0.1 g L⁻¹) could be achieved when the concentrations of glucose, KH₂PO₄, DSF were set at 7–9 g L⁻¹, 3–4 g L⁻¹ and 55–58 g L⁻¹, respectively. These predicted values were also verified by validation experiments.     

Optimisation of growth parameters for the production of carotenoids by Rhodotorula gracilis

 Response surface methodological studies of growth parameters for carotenoid production by Rhodotorula gracilis (ATCC 90950) have been carried out for three parameters employed, namely glucose concentration (%), incubation period (days) and volume of inoculum (ml/100 ml). The results indicated maximum carotenogenesis (0.054%) at a 10% glucose level with a 2 ml/100 ml volume of inoculum for an incubation period of 9 days, which was also verified by experimental data. Received: 25 May 1998     

面向工业化的裂殖壶菌DHA油脂提取方法研究

研究液氮法、均质法、微波法、酶法等9种细胞破碎方法对裂殖壶菌单细胞油脂提取的影响,分别考察了各种细胞破碎方法提取得到的单细胞油脂含量、DHA含量、油脂中的脂肪酸分布以及耗时、耗能等情况,结果表明酶法和酸热法效果最好,其中酶法由于投入低、能耗少、操作简单等优点更具工业化潜力。将酶法与传统的均质法进一步放大对比,验证了酶法的优良性能。     

抗氧化剂耦合非生物胁迫调控微藻油脂和类胡萝卜素合成的研究进展北大核心CSCD

微藻代谢物产率低的问题制约了微藻的产业化发展,近年来利用抗氧化剂耦合非生物胁迫成为有效解决微藻代谢物产率低的方法之一。为了对微藻在非生物胁迫条件下高效合成油脂和类胡萝卜素提供新的思路,综述了抗氧化剂耦合非生物胁迫调控微藻合成油脂和类胡萝卜素的研究进展,并进一步分析了抗氧化剂调控次级代谢产物合成和微藻细胞抗性的作用机制。抗氧化剂可通过调控微藻细胞内氧化还原平衡、信号转导和相关基因的转录水平,维持微藻生长,促进代谢产物的积累,并缓解氧化损伤。     

产DHA破囊壶菌Aurantiochytrium sp.HX2019010的筛选及其脂肪酸组成分析

为筛选产二十二碳六烯酸(Docosahexaenoic acid,DHA)菌株,从厦门市红树林的海水腐木中分离到一株球状真菌HX2019010,通过扫描电镜观察,测定ITS序列,与Genbank数据库比对,该菌株与破囊壶菌相似性较高.选取ITS序列相似性较高的相近菌株构建的进化树表明,菌株HX2019010与Auran...     

Optimization of critical medium components using response surface methodology for phenazine-1-carboxylic acid production by Pseudomonas sp. M-18Q

The optimal flask-shaking batch fermentation medium for phenazine-1-carboxylic acid (PCA) production by Pseudomonas sp. M-18Q, a qscR chromosomal inactivated mutant of the strain M18 was studied using statistical experimental design and analysis. The Plackett-Burman design (PBD) was used to evaluate the effects of eight medium components on the production of PCA, which showed that glucose and soytone were the most significant ingredients (P<0.05). The steepest ascent experiment was adopted to determine the optimal region of the medium composition. The optimum composition of the fermentation medium for maximum PCA yield, as determined on the basis of a five-level two-factor central composite design (CCD), was obtained by response surface methodology (RSM). The high correlation between the predicted and observed values indicated the validity of the model. A maximum PCA yield of 1240 mg/l was obtained at 17.81 g/l glucose and 11.47 g/l soytone, and the production was increased by 65.3% compared with that using the original medium, which was at 750 mg/l.     

豉香型白酒肥肉浸制产脂肪油及脂质氧化研究

以黑米、黑豆、黑木耳为原料,以木糖醇代替蔗糖,将黑米黑豆黑木耳混合液与牛乳共同发酵,研制一种低糖复合发酵乳,并采用单因素及正交试验优化其发酵工艺条件。结果表明,通过高温烘焙香气试验确定黑米、黑豆烘烤条件分别为160 ℃烘烤8 min、180 ℃烘烤10 min。低糖复合发酵乳的最佳工艺条件为黑米∶黑豆∶黑木耳=3∶2∶1（g∶g）,黑米黑豆黑木耳混合液∶牛乳=6∶4（V/V）,混合菌种（保加利亚乳杆菌∶嗜热链球菌=1∶2）接种量4.0%,木糖醇添加量8%。在此优化工艺条件下,低糖复合发酵乳的感官评分为94.2分,脂肪含量为3.6%,蛋白质含量为5.9%,酸度为79 °T,还原糖含量为5.2%,全乳固体为16.1%;乳酸菌数为1.91×106 CFU/g;未检出致病菌,符合相关国家标准。     

Comparison of grass and legume silages for milk production. 1. Production responses with different levels of concentrate

Silages prepared from pure stands of ryegrass, alfalfa, white clover, and red clover over two successive year were offered to lactating dairy cows in two feeding experiments. Proportional mixtures of all cuts prepared in a yr were used to ensure that the forage treatments were representative of the crop. Additional treatments involved mixtures of grass silage with either white clover silage or red clover silage (50/50, on a DM basis). Silages were prepared in round bales, using a biological inoculant additive, and wilting for up to 48 h. Although the legumes were less suited to silage-making than grass, because of their higher buffering capacity and lower water-soluble carbohydrate content, all silages were well-fermented. A standard concentrate was offered at a flat-rate (8 kg/d in yr 1, and 4 or 8 kg/d in yr 2). All of the legume silages led to higher DM intake and milk yields than for the grass silage, with little effect on milk composition. Intake and production responses to legumes were similar at the two levels of concentrate feeding and with forage mixtures they were intermediate to those for the separate forages. An additional benefit of the clover silages, particularly red clover silage, was the increase in levels of polyunsaturated fatty acids, particularly alpha-linolenic acid, in milk. Legume silages also led to a lower palmitic acid percentage in milk. The efficiency of conversion of feed N into milk N declined with increasing levels of legume silage. White clover silage led to a higher N-use efficiency when the effect of N intake level is taken into account.     

粘红酵母H810产油脂培养基、发酵条件优化及其油脂组分的分析

以粘红酵母（Rhodotorula glutinis）H810为实验菌种,探讨了不同碳源、氮源、碳氮比（C／N）、培养温度、培养pH值和接种量等因素对粘红酵母菌体生物量和油脂含量的影响,在此基础上优化了粘红酵母H810产油脂发酵条件。结果表明,产油脂培养基的最佳工艺条件为：碳氮比C／N 40,接种量5％,培养温度28℃和培养初始pH值6．8,在此条件下粘红酵母油脂含量达N56．88％。利用气相色谱分析菌株H810在该条件下的油脂组分,主要包括油酸47．95％、亚油酸12．96％、棕榈酸12．34％、α-亚麻酸11．76％和γ-亚麻酸7．30％。采用该工艺发酵粘红酵母生产微生物油脂具有一定的应用价值,也为进一步大规模生产微生物油脂和研究油脂的不饱和性能提供了研究基础。     

氮对纤维藻生长、油脂积累及营养吸收的影响

为研究氮源及氮浓度对一株淡水富油纤维藻（Ankistrodsemus sp.）生长、油脂积累及营养吸收的影响。以3N-BBM为基础培养基,采用单因素实验分别考察了尿素、氯化铵、硝酸钠及亚硝酸钠以及硝酸钠浓度对纤维藻生长、油脂积累及营养吸收的影响。结果表明:四种氮源对纤维藻生长和生物量影响较小,但对油脂积累影响较大。该藻在尿素中的生物量浓度最高（2.87g/L）,在硝酸钠中的油脂含量（30.17%）和油脂产量（0.81g/L）最高。硝酸钠浓度为0.3mmol/L时,该藻较难存活,浓度为3.0mmol/L时其生长较差,但油脂含量（37.37%）和油脂产量（0.89g/L）最高;浓度在9.0³0.0mmol/L时,纤维藻生物量较高,但油脂含量和油脂产量较低。综合生物量和油脂含量考虑,该纤维藻最适生长和油脂积累的氮源为硝酸钠且最适浓度为3.0mmol/L。      

改性脂质的阴离子交换树脂脱酸工艺研究

以高酸值改性脂质为目标油脂,研究了2种阴离子交换树脂对高酸值改性脂质进行脱酸精制的可行性,并将其与液-液萃取脱酸法联合,以简化液-液萃取脱酸的工艺流程及减少溶剂消耗量。通过单因素实验初步优化了改性脂质的阴离子交换树脂脱酸工艺参数:脱酸温度30℃;反应时间5h;树脂/改性脂质的质量比为2:1;改性脂质/正己烷溶液的浓度为0.2g/mL。改性脂质经液-液萃取联合阴离子交换树脂脱酸后,其罗维朋色度及脂肪酸组成较之未脱酸前没有显著的变化。      

有机碳源对单针藻细胞生长、油脂积累和光合作用的影响

研究不同有机碳源对单针藻(Monoraphidium sp.)细胞生长,油脂积累和光合作用的影响,探讨其细胞生长和油脂积累的最佳碳源浓度。结果表明单针藻具有利用有机碳源进行混合营养生长的能力,葡萄糖、蔗糖对其细胞生长、总脂含量和光合放氧速率具有明显的促进作用,甘氨酸能够促进细胞生长,但总脂含量下降,乙酸钠则表现为抑制作用;在BG-11培养基中加入5g/L葡萄糖后,细胞生物量、总脂产量和光合放氧速率分别为7.8、3.2g/L和240.3μmolO2·(mg·chla)-1·h-1,是同等光合自养条件下的5.6、8.0和1.3倍;单针藻细胞生长、总脂积累的最佳葡萄糖添加浓度为10g/L。