海洋红酵母产虾青素培养基优化的初步研究

为了提高海洋红酵母发酵虾青素的产量水平,对海洋红酵母的培养基成分进行了初步研究。试验结果表明,海洋红酵母能利用葡萄糖、淀粉水解糖、糖蜜等多种碳源,用淀粉水解糖为碳源培养海洋红酵母所获得的虾青素体积产率最大;用牛肉膏为氮源有利于提高海洋红酵母的生物量,以(NH4)2SO4、NH4Cl和蛋白胨为氮源有利于提高海洋红酵母的虾青素体积产率,用KNO3、草酸铵、蛋白胨、尿素有利于提高海洋红酵母的虾青素细胞产率;在海洋红酵母的培养基中添加Mn2 、Cd2 、Zn2 、Fe2 能增加生物量,添加Zn2 、Fe3 、Mn2 能增加海洋红酵母的虾青素体积产率,添加Fe3 能提高海洋红酵母的虾青素细胞产率。     

一种遗传转化方法在海洋红酵母(Rhodotorula mucilaginosa)中的应用

海洋红酵母作为一种产油微生物富含油脂和类胡萝卜素,但由于没有合适的遗传操作方法,无法对细胞反应器进行理性改进,阻碍了它的进一步发展。首先利用农杆菌介导转化成功构建了海洋红酵母的遗传操作平台。参考完成基因注释的圆红冬孢酵母基因组信息,分离其甘油醛-3-磷酸脱氢酶启动子,以基于圆红冬孢酵母密码子优化的潮霉素作为筛选标记,构建载体转化至农杆菌AGL1中,利用农杆菌介导转化成功得到潮霉素抗性表型正确的转化子,通过表型验证,基因型验证以及Western blot在蛋白水平验证,鉴定了hyg基因的有效表达,证明了外源抗性基因成功导入海洋红酵母菌株中,实现了海洋红酵母新的转化方法的建立。     

海洋红酵母电转化条件的研究

采用电穿孔的方法对海洋红酵母进行外源DNA的转化.通过调整参数,对影响电转化的主要因素进行探索,初步建立了载体pTEF1/Zeo-rDNA对海洋红酵母的高效电转化方法.结果表明,当采用对数生长中期的菌体制备感受态细胞、电压为900V、质粒浓度为20mg/L和0.2cm电转化杯时,转化率达到最大值,为每微克质粒DNA 52个转化子.经抽样鉴定所得到的转化子均为阳性克隆.首次建立了以海洋红酵母为宿主的高效电转化体系,为外源基因在海洋红酵母中的表达奠定了基础.     

用b-紫罗兰酮筛选虾青素高产菌株

用β-紫罗兰酮作为筛选剂选择性分离海洋红酵母虾青素高产突变菌株。实验结果表明, 在β-紫罗兰酮存在的情况下, 由于类胡萝卜素合成受到抑制, 海洋红酵母的生物量和虾青素合成量都减少; 当平板培养基中β-紫罗兰酮浓度达到370 mg/L时, 海洋红酵母的致死率为92.3%; 在这种平板培养基上涂布经甲基磺酸乙酯诱变的海洋红酵母, 随机筛选200个菌落, 结果表明生物量、虾青素体积产率和细胞产率均有所提高的正突变株占18%, 生物量、虾青素体积产率和细胞产率的单项指标有所提高的正突变株分别占22.5%、45%和46%。该实验结果表明在分离培养基中添加β-紫罗兰酮可选择性地分离海洋红酵母虾青素高产菌株, 提高虾青素高产突变株的筛选效率。     

海洋红酵母Y2发酵产类胡萝卜素条件的研究

目的 对海洋红酵母Y2高产类胡萝卜素的发酵条件进行优化.方法 在摇瓶条件下,研究培养基成分和培养条件对海洋红酵母Y2生长和类胡萝卜素合成的影响,同时进行海洋红酵母Y2发酵过程的动态分析.结果 海洋红酵母Y2优化培养基组合为葡萄糖45 g/L,蔗糖15 g/L,酵母粉5 g/L,蛋白胨2.5 g/L,磷酸二氢钾1 g/L,磷酸二氢钠3 g/L,硫酸镁7.5 g/L,氯化钾3 g/L,氯化钠5 g/L.最适培养参数为:温度20℃,培养基初始pH为5,接种量为10％,250 mL摇瓶装液量为10～50 mL.类胡萝卜素的合成主要集中在对数生长期和稳定期.海洋红酵母Y2最适收获时间为72 h.种龄以36 h为宜.结论 利用优化培养基,在最适条件下培养海洋红酵母Y2,类胡萝卜素产量达到4.97 mg/L,比基础培养基提高了60.32％.     

用β-紫罗兰酮筛选虾青素高产菌株

用β-紫罗兰酮作为筛选剂选择性分离海洋红酵母虾青素高产突变菌株.实验结果表明,在β-紫罗兰酮存在的情况下,由于类胡萝卜素合成受到抑制,海洋红酵母的生物量和虾青素合成量都减少;当平板培养基中β-紫罗兰酮浓度达到370 mg/L时,海洋红酵母的致死率为92.3%:在这种平板培养基上涂布经甲基磺酸乙酯诱变的海洋红酵母,随机筛选200个菌落,结果表明生物量、虾青素体积产率和细胞产率均有所提高的正突变株占18%,生物量、虾青素体积产率和细胞产率的单项指标有所提高的正突变株分别占22.5%、45%和46%.该实验结果表明在分离培养基中添加β-紫罗兰酮可选择性地分离海洋红酵母虾青素高产菌株,提高虾青素高产突变株的筛选效率.     

植物内生酵母研究简况

当前国内、外对植物内生菌的研究主要集中在内生真菌、内生细菌的多样性及其相关应用等方面,而关于植物内生酵母多样性及应用的研究相对较少.目前研究表明,所分离出的植物内生酵母最常见于隐球菌属、德巴利酵母属、孢子酵母属和红酵母属,并且内生酵母在植物中定殖的具体机制尚未确定.概述了现有研究中关于植物内生酵母的研究现状及应用研究进...     

红酵母简介

红酵母细胞内富含类胡萝卜素和油脂等生物活性成分,色泽诱人,具有较高的生长速率和较强的环境适应性。综述了红酵母在天然类胡萝卜素生物合成、微生物油脂生产、全细胞生物催化、果蔬采后生物防治和功能饲料开发等领域的研究和应用。     

海洋红酵母的液体培养

目的探讨提高海洋红酵母的液体高密度培养方法。方法在摇瓶培养条件下,测定温度、pH、装液量、接种量及摇床转速对海洋红酵母BY2菌株生长的影响,进一步放大培养至50L发酵罐,在培养过程流加氨水以控制pH稳定在5.3~5.5的条件下,考察不同葡萄糖浓度对海洋红酵母BY2菌株发酵菌量的影响。结果摇瓶最适培养条件为温度25℃,pH 5.5,接种量8%、装液量40mL/250mL三角瓶、摇床转速200r/min,在此培养条件下,24h时菌量达到8.9×108 CFU/mL;扩大至50L发酵罐,葡萄糖初始浓度为40、60、80、100g/L各罐20~24h时的菌量相应达到26.6×108、29.5×108、47.8×108、66.8×108 CFU/mL。结论提高初始葡萄糖浓度,流加氨水稳定发酵过程的pH,可以显著提高BY2菌株的发酵菌量。     

云南抚仙湖产类胡萝卜素酵母菌的资源调查

【目的】对分离自云南抚仙湖湖水的379株酵母菌进行产类胡萝卜素的筛选,以期获得具有开发应用价值的产类胡萝卜素酵母菌。【方法】采用酸热法提取类胡萝卜素,紫外分光光度计测定类胡萝卜素含量,SPSS软件分析产类胡萝卜素酵母的分布特征。【结果】318株酵母菌(占供试菌株的83.91%)具有产类胡萝卜素的能力,大多数菌株类胡萝卜素产量在10-300μg/g之间,最高达590.83μg/g。产类胡萝卜素酵母集中分布于红冬孢酵母属(Rhodosporidium)和红酵母属(Rhodotorula);担子菌酵母产类胡萝卜素的能力高于子囊菌酵母;筛选到9株产类胡萝卜素活性较强的菌株:双倒卵形红冬孢酵母(Rhodosporidium diobovatum)3株、沼泽生红冬孢酵母(Rhodosporidium paludigenum)2株、粘红酵母(Rhodotorula glutinis)、禾本红酵母(Rhodotorula graminis)、瑞纳锁掷孢酵母(Sporidiobolus ruineniae)及Cystofilobasidium macerans各1株。【结论】高原湖泊抚仙湖生存着大量产类胡萝卜素的酵母菌,"红色酵母"(Red yeasts)具有较强的产类胡萝卜素的能力,红冬孢酵母属(Rhodosporidium)和红酵母属(Rhodotorula)是抚仙湖产类胡萝卜素酵母菌的主要类群。     

Reduced ghrelin production induced anorexia after rat gastric ischemia and reperfusion

The gastrointestinal (GI) tract is one of the most susceptible organs to ischemia. We previously reported altered gastric motility after gastric ischemia and reperfusion (I/R). However, there have also been few reports of alterations in the eating behavior after gastric I/R. Ghrelin is a GI peptide that stimulates food intake and GI motility. Although ghrelin itself has been demonstrated to attenuate the mucosal injuries induced by gastric I/R, the endogenous ghrelin dynamics after I/R has not yet been elucidated. The present study was designed to investigate the relationship between food intake and the ghrelin dynamics after gastric I/R. Wistar rats were exposed to 80-min gastric ischemia, followed by 12-h or 48-h reperfusion. The food intake, plasma ghrelin levels, gastric preproghrelin mRNA expression levels, and the histological localization of ghrelin-immunoreactive cells were evaluated. The effect of exogenous ghrelin on the food intake after I/R was also examined. Food intake, the plasma ghrelin levels, the count of ghrelin-immunoreactive cells corrected by the percentage areas of the remaining mucosa, and the expression levels of preproghrelin mRNA in the stomach were significantly reduced at 12 h and 48 h after I/R compared with the levels in the sham-operated rats. Intraperitoneal administration of ghrelin significantly reversed the decrease of food intake after I/R. These data show that gastric I/R evoked anorexia with decreased plasma ghrelin levels and ghrelin production, which appears to be attributable to the I/R-induced gastric mucosal injuries. The decrease in the plasma ghrelin levels may have been responsible for the decreased food intake after gastric I/R.     

Role of the melanocortin-4 receptor in metabolic rate and food intake in mice

We evaluated the role of the melanocortin-4 receptor (MC-4R) in the control of metabolic rate and food intake in mice. Intraperitoneal administration of the non-selective MC-R agonist melanotan II (MT-II; a cyclic heptapeptide) increases metabolic rate in wildtype mice, while MC-4R knockout mice are insensitive to the effects of MT-II on metabolic rate. MC-4R knockout mice are also insensitive to the effects of MT-II on reducing food intake. We conclude that MC-4R can mediate control of both metabolic rate and food intake in mice. We infer that a role for MC-3R in mediating the acute effects of MT-II on basal metabolic rate and food intake in wildtype mice seems limited.     

Activation of the GLP-1 Receptors in the Nucleus of the Solitary Tract Reduces Food Reward Behavior and Targets the Mesolimbic System

The gut/brain peptide, glucagon like peptide 1 (GLP-1), suppresses food intake by acting on receptors located in key energy balance regulating CNS areas, the hypothalamus or the hindbrain. Moreover, GLP-1 can reduce reward derived from food and motivation to obtain food by acting on its mesolimbic receptors. Together these data suggest a neuroanatomical segregation between homeostatic and reward effects of GLP-1. Here we aim to challenge this view and hypothesize that GLP-1 can regulate food reward behavior by acting directly on the hindbrain, the nucleus of the solitary tract (NTS), GLP-1 receptors (GLP-1R). Using two models of food reward, sucrose progressive ratio operant conditioning and conditioned place preference for food in rats, we show that intra-NTS microinjections of GLP-1 or Exendin-4, a stable analogue of GLP-1, inhibit food reward behavior. When the rats were given a choice between palatable food and chow, intra-NTS Exendin-4 treatment preferentially reduced intake of palatable food but not chow. However, chow intake and body weight were reduced by the NTS GLP-1R activation if chow was offered alone. The NTS GLP-1 activation did not alter general locomotor activity and did not induce nausea, measured by PICA. We further show that GLP-1 fibers are in close apposition to the NTS noradrenergic neurons, which were previously shown to provide a monosynaptic connection between the NTS and the mesolimbic system. Central GLP-1R activation also increased NTS expression of dopamine-β-hydroxylase, a key enzyme in noradrenaline synthesis, indicating a biological link between these two systems. Moreover, NTS GLP-1R activation altered the expression of dopamine-related genes in the ventral tegmental area. These data reveal a food reward-suppressing role of the NTS GLP-1R and indicate that the neurobiological targets underlying food reward control are not limited to the mesolimbic system, instead they are distributed throughout the CNS.     

Effect of the melanocortin receptor stimulation or inhibition on ethanol intake in alcohol-preferring rats

It has been recently reported that acute intracerebroventricular injection of 1 nmol/rat of the non-selective melanocortin 3 and 4 receptor (MC3/4) agonist MTII reduces ethanol intake in female AA alcohol-preferring rats and alters opioid peptide levels in the ventral tegmental area of rats. To better understand the role of the MC system in the control of ethanol intake, we tested the acute and chronic effects of lateral ventricular (LV) injections of 0.01-1 nmol MTII, of 0.1-1 nmol of the MC3/4R receptor antagonist agouti related peptide (AgRP), and 0.1-0.5 nmol of the MC3/4R receptor antagonist SHU9119 on food, water, and 10% ethanol intake in Marchigian-Sardinian alcohol-preferring (msP) rats, which spontaneously ingest pharmacologically relevant quantities of ethanol both under short and long term access conditions. The data showed that with 2h/day ethanol access, LV MTII injections reduced intake of food and ethanol intakes. When food, water, and ethanol were available ad libitum and 0.01 nmol MTII was given by daily LV injection, however, ethanol intake was reduced for only the first 2 days, whereas food intake was reduced for all 5 days of treatment. Finally, acute LV injection of neither AgRP nor SHU9119 affected ethanol intake under ad libitum conditions, although both antagonists significantly increased food and water intake. In conclusion, these data fail to support a role for endogenous MC3/4R in the control of spontaneous ethanol intake in the msP rat. MC3/4R agonism, however, reduced ethanol intake in association with reduced food intake, suggesting that MTII might reduce nutrient-related controls of ethanol intake rather than, or in addition to, reward-related controls of ethanol intake.     

Taxonomic studies of extremely barophilic bacteria isolated from the Mariana Trench and description of Moritella yayanosii sp. nov., a new barophilic bacterial isolate

We have isolated two strains of extremely barophilic bacteria from sediment collected from the world's deepest ocean floor in the Mariana Trench, Challenger Deep, at a depth of 10898m [Kato C, Li L, Nogi Y, Nakamura Y, Tamaoka J, Horikoshi K (1998) Appl Environ Microbiol 64:1510-1513]. One strain, DB21MT-2, was identified as a strain of Shewanella benthica, and the other strain, DB21MT-5, is closely affiliated with members of the genus Moritella on the basis of 16S rDNA sequence analysis. The hybridization values for DNA-DNA relatedness between DB21MT-5 and the Moritella reference strains were significantly lower than that accepted as the phylogenetic definition of a species. Based on this and other taxonomic differences, strain DB21MT-5 appears to represent a novel obligately barophilic deep-sea Moritella species. The name Moritella yaynanosii (JCM 10263) is proposed. This is the first proposed species of obligately barophilic bacteria of the genus Moritella.     

Up-regulation of neuropeptide Y Y4 receptor mRNA expression in the brainstem of refed rats following 48 h of food deprivation: effect of leptin

Neuropeptide Y (NPY) Y4 receptor (Y4R) in rat brainstem has been implicated in the signaling of satiety. In this study, we investigated the effects of leptin, and refeeding-induced satiety on Y4R mRNA expression in rat brainstem. Y4R receptor-specific primers were used to amplify the mRNA obtained from hypothalamus and brainstem utilizing conventional RT-PCR and quantitative real-time RT-PCR. No PCR product for Y4R was obtained from entire hypothalamic mRNA. Real-time RT-PCR showed a significant two-fold increase in the relative quantity of Y4R mRNA in brainstem of refed rats in comparison to food deprived or ad lib fed rats. Consistently, plasma leptin level was elevated in refed rats in comparison to food deprived rats. Similarly, leptin-treated rats exhibited a significant increase in Y4R mRNA in brainstem as compared to saline-injected rats. Plasma leptin was significantly elevated in leptin-treated rats. These results suggest that refeeding stimulates the expression of Y4R gene in the brainstem and that leptin may be one of the peripheral factors involved in this anorectic signaling mechanism.     

The different dissipation behavior of chiral pesticide paclobutrazol in the brine during Chinese cabbage pickling process

Paclobutrazol (PBZ) is a kind of chiral pesticide, which is a plant growth regulator and has fungicidal activity. Because of the steric‐hindrance effect, there are two enantiomers (2S, 3S; 2R, 3R) in the production. This research studied on the dissipation behavior of chiral pesticide PBZ in the brine during the Chinese cabbage pickled process by phase column‐high performance liquid chromatography (HPLC). The result demonstrated the PBZ enantiomers had the different dissipation in the brine. The study on the behavior of chiral pesticide PBZ in food may provide more sufficient data and information for understanding the potential risk in food and evaluating the environmental pollution at the enantiomer level.     

Diet and activity budget of <Emphasis Type="Italic">Rhinopithecus roxellana</Emphasis> in the Qinling Mountains,China

We collected data on diet and daytime activity budget, and investigated the phenology of food trees and food abundance for a group of Rhinopithecus roxellana on the East Ridge of Yuhuangmiao in the Qinling Mountains from November 2001 to December 2003. We calculated the seasonal activity budget using data collected by scan sampling from 84 full-day observations (winter 16, spring 18, summer 28, autumn 22 days). During scan sampling we recorded behavioral states, and the food items and species consumed. The subjects consumed 84 plant species, including trees and shrubs of 29 families, and lichens. Food species varied seasonally. The overall diet of R. roxellana consisted of 29.4% fruit/seeds, 29.0% lichens, 24.0% leaves, 11.1% bark, 4.2% buds, 1.3% twigs and 1.0% unidentified items. Because the abundance of different food items varied seasonally, the monkeys had to shift their major food items seasonally. The annual activity budget of R. roxellana was 36.2% time spent resting, 35.8% feeding, 22.9% moving, and 5.1% other behavior. Seasonal changes in activity budget were observed. R. roxellana spent more time moving in autumn, when the quality of the food might be highest, and least time moving in winter when the food quality might be lowest. Thus, this type of monkey has a passive foraging strategy.     

PYY(3-36) into the arcuate nucleus inhibits food deprivation-induced increases in food hoarding and intake

Central administration of neuropeptide Y (NPY) increases food intake in laboratory rats and mice, as well as food foraging and hoarding in Siberian hamsters. The NPY-Y1 and Y5 receptors (Rs) within the hypothalamus appear sufficient to account for these increases in ingestive behaviors. Stimulation of NPY-Y2Rs in the Arcuate nucleus (Arc) has an anorexigenic effect as shown by central or peripheral administration of its natural ligand peptide YY (3-36) and pharmacological NPY-Y2R antagonism by BIIE0246 increases food intake. Both effects on food intake by NPY-Y2R agonism and antagonism are relatively short-lived lasting ∼4 h. The role of NPY-Y2Rs in appetitive ingestive behaviors (food foraging/hoarding) is untested, however. Therefore, Siberians hamsters, a natural food hoarder, were housed in a semi-natural burrow/foraging system that had (a) foraging requirement (10 revolutions/pellet), no free food (true foraging group), (b) no running wheel access, free food (general malaise control) or (c) running wheel access, free food (exercise control). We microinjected BIIE0246 (antagonist) and PYY_(3-36) (agonist) into the Arc to test the role of NPY-Y2Rs there on ingestive behaviors. Food foraging, hoarding, and intake were not affected by Arc BIIE0246 microinjection in fed hamsters 1, 2, 4, and 24 h post injection. Stimulation of NPY-Y2Rs by PYY_(3-36) inhibited food intake at 0–1 and 1–2 h and food hoarding at 1–2 h without causing general malaise or affecting foraging. Collectively, these results implicate a sufficiency, but not necessity, of the Arc NPY-Y2R in the inhibition of food intake and food hoarding by Siberian hamsters.     

Pressure response in deep-sea piezophilic bacteria

Several piezophilic bacteria have been isolated from deep-sea environments under high hydrostatic pressure. Taxonomic studies of the isolates showed that the piezophilic bacteria are not widely distributed in terms of taxonomic positions, and all were assigned to particular branches of the Proteobacteria gamma-subgroup. A pressure-regulated operon from piezophilic bacteria of the genus Shewanella, S. benthica and S. violacea, was cloned and sequenced, and downstream of this operon another pressure regulated operon, cydD-C, was found. The cydD gene was found to be essential for the bacterial growth under high-pressure conditions, and the product of this gene was found to play a role in their respiratory system. Results obtained later indicated that the respiratory system in piezophilic bacteria may be important for survival in a high-pressure environment, and more studies focusing on other components of the respiratory chain have been conducted. These studies suggested that piezophilic bacteria are capable of changing their respiratory system in response to pressure conditions, and a proposed respiratory chain model has been suggested in this regard.