维生素在丙酮酸过量合成中的重要作用

研究了烟酸、硫胺素、吡哆醇、生物素和核黄素对一株光滑球拟酵母(\%Torulopsis glabrata\%) WSH\|IP303以葡萄糖为碳源、以氯化铵为唯一氮源生产丙酮酸的影响。利用正交试验方法,确证了硫胺素是影响WSH\|IP303生产丙酮酸的最重要因素。在硫胺素浓度一定(0.01～0.015mg/L)的前提下,提高烟酸浓度有助于加快耗糖速度。当烟酸、硫胺素、吡哆醇、生物素和核黄素的浓度分别为8、0.015、0.4、0.04和01mg/L时,摇瓶发酵48h,丙酮酸产量和产率可分别达到52.4g/L和0525g/g。采用优化的维生素组合方式,进行2.5L罐分批发酵,在初糖浓度120g/L的条件下发酵57.5h,丙酮酸产量和产率分别达到69.4g/L和0593g/g,分别比摇瓶培养的最好结果提高了32.%和13%。     

不同浓度有机物对雷公藤不定根生长和次生代谢产物含量的影响

以NT为基本培养基,雷公藤(Tripterygium wilfordii)不定根为材料,研究了肌醇、VB1、烟酸、VB6、甘氨酸、叶酸、生物素等有机物质对雷公藤不定根生长及其次生代谢产物雷公藤甲素和总生物碱含量的影响。结果表明:NT培养基中原有浓度的肌醇、VB1含量即可使雷公藤不定根生长量、雷公藤甲素含量、总生物碱含量及产量达到最大值。在添加的其他有机物中,添加1 mg/L烟酸、1 mg/L VB6和5 mg/L甘氨酸适合不定根的生长;添加0.5 mg/L烟酸、0.5 mg/L生物素、1 mg/L VB6、1 mg/L甘氨酸和1 mg/L叶酸适合雷公藤甲素的积累;添加0.5 mg/L甘氨酸、1 mg/L VB6、1 mg/L叶酸和1 mg/L生物素则适合不定根中雷公藤总生物碱的合成。     

河套地区小麦粉营养品质分析及小麦粉营养化发展对策

目的：了解我国河套地区小麦粉营养品质。方法：选取当地2个不同季节生产的特色面粉6种,对其维生素和矿物质进行分析。结果：12个样品维生素E含量为0.061~0.404 mg/100 g,维生素B1、维生素B2、烟酸含量分别为0.139~0.230 mg/100 g、1.380~1.900 mg/100 g、3.425~4.350 mg/100 g,维生素B2和烟酸含量远高于我国小麦粉平均水平。铁、钙、磷、镁含量偏低,但硒含量为0.043~0.250 mg/kg,已达到富硒农产品标准。结论：河套地区小麦粉含有丰富的维生素B2、烟酸、硒,本研究就小麦粉的营养化发展提出对策建议。     

荷叶离褶伞子实体营养成分分析与评价

经测定,荷叶离褶伞Lyophyllum decastes子实体含粗蛋白21.4%,粗脂肪8.2%,粗纤维9.52%,碳水化合物53.03%,灰分13.6%;必需氨基酸6.02g/100g,占氨基酸总量(16.82g/100g)的35.78%;含维生素B10.068mg、维生素B24.26mg、维生素B6590μg、维生素B1255.7μg、烟酸21.2mg;1kg子实体含锌50.0mg、铜19.0mg、硒0.013mg、镉1.85mg、汞0.56mg、铅0.75mg、砷0.29mg。     

响应面法优化嗜热厌氧杆菌X514产乙醇合成培养基

嗜热厌氧杆菌X514(Thermoanaerobactersp.X514)能同时发酵五碳糖、六碳糖并产出乙醇,是纤维素乙醇生产中最具潜力的菌株之一。单因子试验证明,酵母提取物中对X514乙醇发酵起决定性影响的组分为B族维生素,并进一步确定了B族维生素中对乙醇发酵有影响作用的6种维生素。结合培养基中的其他影响因子,应用Plackett-Burman试验设计方法,筛选出X514乙醇发酵的极大影响因子为NH4Cl、烟酸及硫胺素。随后用最陡爬坡试验确定了影响因子最佳取值区域,并利用响应面方法优化合成培养基。优化结果显示,当以5 g/L葡萄糖为底物时,在NH4Cl、烟酸及硫胺素的浓度分别为1.05 g/L、6.4 mg/L及7.0 mg/L的条件下,X514的乙醇产出浓度达到最优理论值34.46 mmol/L。试验验证该条件下乙醇产出浓度为33.78 mmol/L。试验值与理论值接近,原始矿物质培养基中乙醇产出浓度的5.1倍,并与添加5 g/L的酵母提取物培养基的乙醇产出浓度(34.67 mmol/L)相当。     

基于高遗传转化率及低幼苗玻璃化率的黑果枸杞叶片组合培养体系

【目的】建立高效稳定的黑果枸杞遗传转化体系,有效降低其再生幼苗玻璃化率,促进其基因功能研究和提高遗传改良效率。【方法】以黑果枸杞叶片作为外植体,利用农杆菌(LBA4404、EHA105)介导的遗传转化法,通过调整基础培养基类型并添加相应浓度的植物激素,筛选出最适愈伤组织诱导培养基、分化和选择培养基、生根诱导培养基,将黑果枸杞遗传转化率提高到65%以上,同时降低幼苗玻璃化率至10%以下。【结果】(1)黑果枸杞叶片高效组合培养体系中最佳农杆菌侵染浓度(OD₆₀₀)为0.6,侵染时间为25 min,在此条件下侵染叶片抗性愈伤诱导率达78.2%～96%;(2)黑果枸杞遗传转化中最适分化和选择培养基为：MS+肌醇50 mg/L+烟酸0.25 mg/L+维生素B₆ 0.25 mg/L+铁盐母液1 mL/L+甘氨酸1.0 mg/L+维生素B₁ 0.05 mg/L+6-BA 0.25 mg/L+蔗糖30 g/L+琼脂6 g/L+卡那霉素30 mg/L+特美汀300 mg/L (pH=6.0);最适生根诱导培养基为：WPM+IBA 0.2...     

植物资源开发利用新信息——国外有关植物的专利摘要(十一)

301.诱导巴豆发生不定芽的培养基 据日本1990年专利记载,诱导巴豆(Croton su-blyratus或C.joufra)产生不定芽的培养基,应含有植物激素(0.2—10ppm细胞分裂素及0.001—4ppm8-羟基喹啉(oxine)或0.1—10ppm细胞分裂素及0.005—0.5ppm赤霉素)。 302.繁殖大豆不定芽的培养基 据日本1990年专利记载,含有0.25—1.5倍无机盐、维生素(如Gamborg B_50.1—10mg/L,盐酸硫胺素及0.5—10mg/L烟酸),植物激素(如0.5—3mg/L 2,4-D)和糖的MS培养基,特别适用于大豆未成熟芽。     

矿质营养与其他生长物质对荷叶离褶伞菌丝生长的影响

1mg/mLKCl促进荷叶离褶伞菌丝生长;5或10mg/mLNaCl、5或10mg/mLMgSO4、5或10mg/mLKCl、10mg/mLH2PO4和1mg/mLCaSO4抑制菌丝生长;0.8mg/mL的MnSO4和CuSO4以及0.5mg/mLFeSO4、0.2或0.5mg/mLCoCl2和0.2、0.5或0.8mg/mLZnSO4促进菌丝生长;0.5或0.2mg/mLCuSO4、0.2或0.5mg/mLMnSO4及0.8或0.2mg/mLFeSO4对菌丝生长的影响不显著;维生素B6、维生素C、维生素PP和维生素B1可促进菌丝生长,在含有10μg/L维生素B6的培养基上菌丝生长速度最快,但维生素C试用浓度较低(50μg/L)时对菌丝生长的影响不显著;吲哚丁酸、吲哚乙酸、奈乙酸对菌丝生长具有促进作用,但0.1、0.5或1.0μg/L赤霉素对菌丝生长的影响不显著。     

家蚕体内维生素B6的存在形态和转换代谢

采用不含桑叶粉末、以去维生素牛乳酪蛋白为蛋白源的准合成饲料饲育家蚕Bombyx mori幼虫,探讨了家蚕体内维生素B（VB₆）化合物的存在形态和转换代谢途经。随饲料中盐酸吡哆醇（PN-HCl）添加量的增加,幼虫体内吡哆醇(PN)含量相应变化,其次是吡哆醛(PL);而辅酶型磷酸吡哆醛(PLP)和磷酸吡哆胺(PMP)含量存在稳定性。饲料中的吡哆醇以单纯扩散的形式进入体液;体液中的吡哆醇被各种组织吸收后,在各自的吡哆醛激酶和PNP/磷酸吡哆胺氧化酶的作用下,转变成辅酶型磷酸吡哆醛。家蚕不同于哺乳动物,没有特定的辅酶型磷酸吡哆醛形成组织和辅酶型磷酸吡哆醛的转送机制。同时家蚕体内缺乏具储存VB₆功能的辅酶型磷酸吡哆醛结合蛋白,推测这是用缺乏VB₆的饲料饲育各龄起蚕,幼虫当龄死亡的主要原因。     

重组大肠杆菌高效催化合成γ-氨基丁酸

[目的]实现重组大肠杆菌高效合成γ-氨基丁酸(γ-aminobutyric acid,GABA)。[方法]构建表达谷氨酸脱羧酶的基因工程菌Escherichia coli p ET-GAD,对催化工艺进行初步优化,实现高效催化L-谷氨酸脱羧反应合成GABA。[结果]在谷氨酸脱羧酶的表达过程中,维生素B6盐酸吡哆醇(PN)可以替代5-磷酸吡哆醛(PLP)作为辅酶补给,提高工程菌E. coli p ET-GAD的催化活力。在50 m L反应体系中,重组细胞浓度为8 mg/m L,底物浓度为200 mmol/L,在35℃、p H 4. 4条件下反应2 h,L-谷氨酸的转化率 98%。为了提高GABA的生产效率,采用谷氨酸/谷氨酸钠分批补料方式控制反应过程中的p H值,GABA的最终浓度达到247 g/L。[结论]重组大肠杆菌可以高效催化合成γ-氨基丁酸,为基因工程菌工业化制备GABA提供实验依据。     

Metabolic profile of ginkgo kernel juice fermented with lactic aicd bacteria: A potential way to degrade ginkgolic acids and enrich terpene lactones and phenolics

In this paper, the influence of lactic acid fermentation on the metabolic profile of ginkgo kernel juice was studied. For this purpose, three lactic acid bacteria (LAB), Lactobacillus acidophilus, Lactobacillus plantarum and Lactobacillus casei, were selected. The results showed that all the lactobacilli grew well in ginkgo kernel juice with viable cell counts exceeding 8.0 Log CFU/mL. The organic acid contents underwent dynamic changes, and the lactic acid production reached more than 3 g/L. The consumption of sugars and free amino acids by LAB was evident. Meanwhile, more than 70% of the ginkgolic acids were degraded by LAB, and the final concentrations in ginkgo kernel juice were below 1 mg/L after 48 h of fermentation. In contrast, the terpene lactones contents in fermented ginkgo kernel juice exceed 20 mg/L, which was 1.6-fold higher than that in the unfermented juice. Certain phenolics were significantly enriched, and the total phenolic content increased by approximately 9% through fermentation. In addition, lactic acid fermentation significantly enhanced the antioxidant and antimicrobial activities of ginkgo kernel juice. Overall, the results indicated that lactic acid fermentation can effectively improve the nutritional value and safety of ginkgo kernel juice.     

Joint effect of nitrogen sources and B vitamin supplementation of date juice on lactic acid production by Lactobacillus casei subsp. rhamnosus

The use of date juice as a substrate for lactic acid production was investigated. Various nitrogen sources were compared with yeast extract for efficient lactic acid production by Lactobacillus casei subsp. rhamnosus. Among different nitrogen sources added to date juice (yeast extract, ammonium sulfate, tryptic soy, urea, peptone, and casein hydrolysate), yeast extract was the most efficient. The effect of yeast extract could have been due to its B vitamin content. The addition of five B vitamins at less than 25 mg/l to date juice with any nitrogen source enhanced lactic acid production to some extent, except for date juice with yeast extract or urea or peptone. The most significant increase was obtained with ammonium sulfate. Half of the yeast extract content (10 g/l) in a supplemented date juice could be replaced by a mixture of B vitamins at less than 25 mg/l, and ammonium sulfate at 2.6 g/l with no significant decrease in lactic acid production.     

Anaerobic conversion of lactic acid to acetic acid and 1, 2-propanediol by Lactobacillus buchneri

The degradation of lactic acid under anoxic conditions was studied in several strains of Lactobacillus buchneri and in close relatives such as Lactobacillus parabuchneri, Lactobacillus kefir, and Lactobacillus hilgardii. Of these lactobacilli, L. buchneri and L. parabuchneri were able to degrade lactic acid under anoxic conditions, without requiring an external electron acceptor. Each mole of lactic acid was converted into approximately 0.5 mol of acetic acid, 0.5 mol of 1,2-propanediol, and traces of ethanol. Based on stoichiometry studies and the high levels of NAD-linked 1, 2-propanediol-dependent oxidoreductase (530 to 790 nmol min(-1) mg of protein(-1)), a novel pathway for anaerobic lactic acid degradation is proposed. The anaerobic degradation of lactic acid by L. buchneri does not support cell growth and is pH dependent. Acidic conditions are needed to induce the lactic-acid-degrading capacity of the cells and to maintain the lactic-acid-degrading activity. At a pH above 5.8 hardly any lactic acid degradation was observed. The exact function of anaerobic lactic acid degradation by L. buchneri is not certain, but some results indicate that it plays a role in maintaining cell viability.     

Selection of medium components by Plackett-Burman design for production of L(+) lactic acid by Lactobacillus amylophilus GV6 in SSF using wheat bran

Plackett-Burman design was employed for screening 15 parameters for production of L(+) lactic acid from wheat bran, an inexpensive substrate and solid support, by Lactobacillus amylophilus GV6 in solid state fermentation (SSF). Eleven nutrients belonging to two categories viz.; nitrogen sources and salt sources along with three physical parameters and a buffer were screened. This design screens n variables in n + 1 number of experiments. Coefficients and sum of squares ratio in percentage (SS%) of these variables were calculated by subjecting the experimental data to statistical analysis. The nitrogen sources peptone, yeast extract and tri-ammonium citrate, along with NaH2PO4.2H2O and Tween 80, were found to influence productivity, which can be further optimized for increased lactic acid production. Use of this design is scarce in solid state fermentation and has not been attempted previously for single step conversion of starch to L(+) lactic acid using a bacterial system.     

利用SAS软件优化L-乳酸发酵培养基

利用SAS软件中二水平设计和响应面分析法较系统地研究了乳酸菌(Lactobacillussp.)M7发酵培养基,得到了在一定条件下乳酸产量随牛肉膏、柠檬酸二铵、吐温80含量的变化规律,并根据分析结果优化了发酵培养基,简化了基本配方,产量可提高15％。     

Marc-145细胞无血清培养液组分的优化筛选

目的：对Marc-145细胞无血清培养液组分及浓度进行优化筛选。方法：采用Plackett-Burman设计和中心组合旋转设计对不同的营养成分进行优化筛选。结果：经Plackett-Burman设计,利用20组实验对14种不同营养成分进行考察,发现孕酮、抗氧化试剂、乙醇胺、维生素B12、维生素B12和脂肪酸复合剂对Marc-145细胞无血清悬浮生长的比生长速率有显著影响;针对该6种因素进行中心组合旋转实验设计,利用53组实验筛选出它们的最优使用浓度分别为孕酮5．5mg／L、抗氧化试剂250μL/L、乙醇胺2．1mL／L、维生素B12 2．86mg／L、维生素B6 44μg/L和脂肪酸复合剂215μL/L。结论：经2种实验设计方法优化,确定了Marc-145细胞无血清培养液组分及最适浓度,为无血清悬浮培养Marc-145细胞及增殖猪繁殖及呼吸综合征病毒提供了实验基础。     

Purification and characterization of novel antifungal compounds from the sourdough Lactobacillus plantarum strain 21B

Sourdough lactic acid bacteria were selected for antifungal activity by a conidial germination assay. The 10-fold-concentrated culture filtrate of Lactobacillus plantarum 21B grown in wheat flour hydrolysate almost completely inhibited Eurotium repens IBT18000, Eurotium rubrum FTDC3228, Penicillium corylophilum IBT6978, Penicillium roqueforti IBT18687, Penicillium expansum IDM/FS2, Endomyces fibuliger IBT605 and IDM3812, Aspergillus niger FTDC3227 and IDM1, Aspergillus flavus FTDC3226, Monilia sitophila IDM/FS5, and Fusarium graminearum IDM623. The nonconcentrated culture filtrate of L. plantarum 21B grown in whole wheat flour hydrolysate had similar inhibitory activity. The activity was fungicidal. Calcium propionate at 3 mg ml(-1) was not effective under the same assay conditions, while sodium benzoate caused inhibition similar to L. plantarum 21B. After extraction with ethyl acetate, preparative silica gel thin-layer chromatography, and chromatographic and spectroscopic analyses, novel antifungal compounds such as phenyllactic and 4-hydroxy-phenyllactic acids were identified in the culture filtrate of L. plantarum 21B. Phenyllactic acid was contained at the highest concentration in the bacterial culture filtrate and had the highest activity. It inhibited all the fungi tested at a concentration of 50 mg ml(-1) except for P. roqueforti IBT18687 and P. corylophilum IBT6978 (inhibitory concentration, 166 mg ml(-1)). L. plantarum 20B, which showed high antimold activity, was also selected. Preliminary studies showed that phenyllactic and 4-hydroxy-phenyllactic acids were also contained in the bacterial culture filtrate of strain 20B. Growth of A. niger FTDC3227 occurred after 2 days in breads started with Saccharomyces cerevisiae 141 alone or with S. cerevisiae and Lactobacillus brevis 1D, an unselected but acidifying lactic acid bacterium, while the onset of fungal growth was delayed for 7 days in bread started with S. cerevisiae and selected L. plantarum 21B.     

Characterization of Lactobacillus sakei by the type of stereoisomers of lactic acid produced

Lactobacillus sakei strains were characterized by the shift of the type of stereoisomers of lactic acid produced in the presence of 50 mM sodium acetate in a medium. Of 27 Lactobacillus sakei strains studied, 20 strains showed high levels of DNA-DNA similarity with L. sakei NRIC 1071(T), and were confirmed as L. sakei. The three remaining strains were identified as Lactobacillus curvatus by DNA-DNA similarity, and three other strains were included in the cluster of Lactobacillus plantarum/Lactobacillus pentosus/Lactobacillus paraplantarum and one strain in the cluster of Lactobacillus paracasei on the basis of 16S rRNA gene sequences. Of the 20 L. sakei strains, 19 strains shifted the type of stereoisomers of lactic acid produced from the DL-type to the L-type in the presence of 50 mM sodium acetate. L. curvatus strains and strains included in the cluster of L. plantarum/L. pentosus/L. paraplantarum and in the cluster of L. paracasei did not shift the type of stereoisomers of lactic acid produced. The change of the type of stereoisomers of lactic acid from the DL-type to the L-type in the presence of sodium acetate was concluded to be species-specific for L. sakei and useful for identification of strains in this species.     

Biological ensiling of sugarcane tops

The following lactic acid bacteria were isolated from sugarcane tops silage:Lactobacillus plantarum, Lactobacillus buchneri, Lactobacillus brevis, Lactobacillus delbrueckii, Pediococcus cerevisiae, Leuconostoc mesenteroides andStreptococcus lactis. The isolates were grown in a synthetic medium and the final pH, sugar uptake and the effect of adding CaCO₃ and L1, L2 and L3 factors was observed. The importance of the buffering capacity of the ensiled material for the silage process with a view to the occurrence of lactic acid bacteria is discussed.     

Anaerobic Conversion of Lactic Acid to Acetic Acid and 1,2-Propanediol by Lactobacillus buchneri

The degradation of lactic acid under anoxic conditions was studied in several strains of Lactobacillus buchneri and in close relatives such as Lactobacillus parabuchneri, Lactobacillus kefir, and Lactobacillus hilgardii. Of these lactobacilli, L. buchneri and L. parabuchneri were able to degrade lactic acid under anoxic conditions, without requiring an external electron acceptor. Each mole of lactic acid was converted into approximately 0.5 mol of acetic acid, 0.5 mol of 1,2-propanediol, and traces of ethanol. Based on stoichiometry studies and the high levels of NAD-linked 1,2-propanediol-dependent oxidoreductase (530 to 790 nmol min⁻¹ mg of protein⁻¹), a novel pathway for anaerobic lactic acid degradation is proposed. The anaerobic degradation of lactic acid by L. buchneri does not support cell growth and is pH dependent. Acidic conditions are needed to induce the lactic-acid-degrading capacity of the cells and to maintain the lactic-acid-degrading activity. At a pH above 5.8 hardly any lactic acid degradation was observed. The exact function of anaerobic lactic acid degradation by L. buchneri is not certain, but some results indicate that it plays a role in maintaining cell viability.