鲐鱼软骨糖胺聚糖的硫酸软骨素的结构及其与生长因子的相互作用

为了开发具有药用价值的硫酸软骨素(chondroitin sulfate,CS)的新资源,从鲐鱼(Pneumatophorus japonicus Houttuyn)软骨蛋白聚糖(proteoglycan,PG)制备了糖胺聚糖(glycosaminoglycan,GAG),用酶降解和阴离子交换HPLC法测定了GAG的CS的组成及其含量,用凝胶层析法测定了GAG的分子量,用表面等离子体谐振(surface plasmon resonance,SPR)法测定了其与多效生长因子(PTN)、中期因子(MK)和肝细胞生长因子(HGF)相互作用的动力学参数结合速率常数(ka)、解离速率常数(kd)和平衡解离常数(KD)。结果显示,鲐鱼软骨GAG含量约为651μg/mgPG或1.09μmol/mgPG(按照二糖单位计算),主要含CS(1.03μmol/mgPG,按照二糖单位计算),CS酶解产生的主要二糖单位是ΔDi-6S(38.8%)和ΔDi-4S(46.3%),有少量的ΔDi-0S(8.4%)和ΔDi-diSD(6.5%)。GAG(CS)的分子量为78kD。GAG(CS)与生长因子的相互作用的动力学参数ka((mol/L)-1.s-1)、kd(s-1)和KD(nmol/L)分别为(2.77±0.17)×105、(7.74±1.56)×10-5和(0.28±0.06)(MK),(1.05±0.22)×104、(4.16±0.80)×10-3和(417±131.3)(PTN),(7.04±0.94)×105、(7.84±2.82)×10-3和(11.1±3.80)(HGF)。该GAG同MK、HGF和PTN有高的或较高的亲和性,暗示鲐鱼软骨GAG的CS有可能通过调节生长因子的信号转导途径而对某些疾病发挥治疗作用,具有潜在进一步药用开发价值。     

Solid-substrate fermentation of corn fiber by Phanerochaete chrysosporium and subsequent fermentation of hydrolysate into ethanol

The goal of this study was to develop a fungal process for ethanol production from corn fiber. Laboratory-scale solid-substrate fermentation was performed using the white-rot fungus Phanerochaete chrysosporium in 1 L polypropylene bottles as reactors via incubation at 37 degrees C for up to 3 days. Extracellular enzymes produced in situ by P. chrysosporium degraded lignin and enhanced saccharification of polysaccharides in corn fiber. The percentage biomass weight loss and Klason lignin reduction were 34 and 41%, respectively. Anaerobic incubation at 37 degrees C following 2 day incubation reduced the fungal sugar consumption and enhanced the in situ cellulolytic enzyme activities. Two days of aerobic solid-substrate fermentation of corn fiber with P. chrysosporium, followed by anaerobic static submerged-culture fermentation resulted in 1.7 g of ethanol/100 g of corn fiber in 6 days, whereas yeast ( Saccharomyces cerevisiae) cocultured with P. chrysosporium demonstrated enhanced ethanol production of 3 g of ethanol/100 g of corn fiber. Specific enzyme activity assays suggested starch and hemi/cellulose contribution of fermentable sugar.     

大庆地区植被和土壤碳氮储量的估算

利用1978年MSS多光谱数据、2008年中国资源卫星数据和全国第二次土壤普查数据,对黑龙江省土壤退化典型地区大庆地区的植被和土壤碳氮储量进行了估算。结果表明:大庆地区的植被平均碳密度1978年为0.58kg/m2,2008年为0.67kg/m3;土壤平均碳氮密度分别为(9.26±1.73)kg/m3和(0.62±0.17)kg/m3,土地覆被平均土壤碳氮密度分别为(8.10±2.34)kg/m3和(0.50±0.11)kg/m3。1978和2001年植被碳储量分别为(9.38×106)t和(10.40×106)t,30年间植被碳储量增加了(1.02×106)t;全区土壤总碳量为(187.18±34.95)×106t,总氮量为(125.84±33.66)×105t;全区土地覆被土壤总碳量为(163.68±47.34)×106t,总氮量为(102.00±22.55)×105t。大庆地区的植被和土壤平均碳密度都低于中国的平均水平。     

普通青霉D12和罗伊氏乳杆菌发酵产物促进平邑甜茶幼苗生长和连作土壤生物环境改善

[目的]研究普通青霉D12和罗伊氏乳杆菌及其混合发酵产物对苹果幼苗生长及土壤环境的影响,为缓解苹果连作障碍提供绿色生防措施.[方法]以32年苹果园土和平邑甜茶幼苗为试材进行盆栽试验.普通青霉D12?(R1)和罗伊氏乳杆菌(R2)活化后制成活菌数分别≥2×109?CFU/mL和?≥3×109?CFU/mL的发酵产物.盆栽...     

EM保水剂施用对烤烟的影响及其施用制度的优选研究

烤烟是我国重要的叶用经济作物,我国是烟草种植面积和烟叶总产量最高的国家,烤烟生产对我国西南诸省(如云、贵、川)国民经济和财政收入水平的提高有重要作用。但烟区出现的阶段性干旱经常影响烤烟的产量及其正常的成熟。因此,加强烤烟节水抗旱技术研究,合理调控烟田水分供应,是确保干旱地区烟叶优质适产的关键。本文分别以MP3005KM保水剂、秸秆、EM活性钙和EM复壮液为主要材料制作EM保水剂,研究了不同EM保水剂处理对烤烟生长、产量和品质的影响,并引入熵权系数评价模型,建立评价指标体系,优选综合效益最优的EM保水剂施用制度。结果表明:不同EM保水剂处理均增加了烤烟单株叶面积,秸秆为主要材料的EM保水剂(T1和T2)对烤烟生长中后期叶面积的增长促进作用更明显;表征烤烟叶面积指数(LAI)动态变化的作物生长模型显示,T2(40 g×株1EM活性钙+300 g×株-1秸秆)和T6(40 g×株~(-1) EM活性钙+6 g×株~(-1)MP3005KM)处理烤烟LAI具备较大的增长空间;EM保水剂明显提高了烤烟旺长期和成熟期的净光合速率(Pn),同时降低了蒸腾速率(Tr),调节了烤烟叶片的光合作用。主成分分析显示,与不施保水剂相比,EM保水剂的施用显著提高了烤烟的"综合品质",秸秆为主要材料的EM保水剂的"提质"效益最优,T1和T2烤烟品质综合主成分值分别达3.25和2.76。综合考虑"高产"、"优质"、"节水"和"节肥"等因素,本研究推荐40 g×株-1EM活性钙结合4 500 kg×hm-2秸秆段作为EM保水剂的施用制度,在该制度下,烤烟产量、灌溉水利用效率和氮肥偏生产力分别为2 433.5 kg×hm-2、0.608 kg×m-3和27.04 kg×kg~(-1)。     

Glucan and fructan production by sourdough Weissella cibaria and Lactobacillus plantarum

After a large screening on sourdough lactic acid bacteria, exopolysaccharide (EPS)-forming strains of Weissella cibaria, Lactobacillus plantarum, and Pediococcus pentosaceus were selected. After 6 days of incubation at 30 degrees C, the synthesis of EPS in MRS-based broth ranged from 5.54 to 7.88 mg mL-1. EPS had an apparent molecular mass of ca. 104 Da. As shown by carbohydrate consumption, the synthesis of EPS was found from sucrose only. Two types of homopolysaccharides were synthesized: glucans simultaneously with growth and fructans after 1 day of incubation. Two protein bands of ca. 180-200 kDa were in situ detected on SDS-PAGE gels incubated with sucrose. PCR products of ca. 220 bp were found for L. plantarum PL9 (100% of identity to putative priming glycosyltransferase of L. plantarum WCFS1) and W. cibaria WC4 (80% of identity to putative glycosyltransferase, epsD, of Bacillus cereus G9241) by using hybrid primers for the priming gtf genes. Degenerated primers DexreuR and DexreuV showed a unique PCR product, and the predicted amino acid sequences were identical for W. cibaria WC4 and L. plantarum PL9. The sequence had similarity with polysaccharide biosynthesis glycosyltransferases. W. cibaria WC4 or L. plantarum LP9 synthesized ca. 2.5 g kg-1 EPS during sourdough fermentation with sucrose added. Compared to the sourdough started with an EPS-negative strain, the sourdough started with W. cibaria WC4 or L. plantarum LP9 increased the viscosity, and the resulting bread had higher specific volume and lower firmness. The synthesis of EPS by selected sourdough lactic acid bacteria could be considered as a useful tool to replace the additives for improving the textural properties of baked goods.     

Enzyme production by wood-rot and soft-rot fungi cultivated on corn fiber followed by simultaneous saccharification and fermentation

This research aims at developing a biorefinery platform to convert lignocellulosic corn fiber into fermentable sugars at a moderate temperature (37 °C) with minimal use of chemicals. White-rot (Phanerochaete chrysosporium), brown-rot (Gloeophyllum trabeum), and soft-rot (Trichoderma reesei) fungi were used for in situ enzyme production to hydrolyze cellulosic and hemicellulosic components of corn fiber into fermentable sugars. Solid-substrate fermentation of corn fiber by either white- or brown-rot fungi followed by simultaneous saccharification and fermentation (SSF) with coculture of Saccharomyces cerevisiae has shown a possibility of enhancing wood rot saccharification of corn fiber for ethanol fermentation. The laboratory-scale fungal saccharification and fermentation process incorporated in situ cellulolytic enzyme induction, which enhanced overall enzymatic hydrolysis of hemi/cellulose components of corn fiber into simple sugars (mono-, di-, and trisaccharides). The yeast fermentation of the hydrolyzate yielded 7.8, 8.6, and 4.9 g ethanol per 100 g corn fiber when saccharified with the white-, brown-, and soft-rot fungi, respectively. The highest ethanol yield (8.6 g ethanol per 100 g initial corn fiber) is equivalent to 35% of the theoretical ethanol yield from starch and cellulose in corn fiber. This research has significant commercial potential to increase net ethanol production per bushel of corn through the utilization of corn fiber. There is also a great research opportunity to evaluate the remaining biomass residue (enriched with fungal protein) as animal feed.     

固液气分流式瘤胃模拟系统的设计与测试

针对现有批次培养和连续培养瘤胃模拟装置存在的不足,设计了一种在不影响系统气密性的情况下,由计算机自动控制的固液气分流式连续培养瘤胃模拟系统。并进行了为期10d的培养试验。试验表明:本系统的各发酵参数平行性好,4个发酵罐PH值从第5天开始稳定,变化趋势与牛瘤胃内pH值变化一致;各发酵单元从第3天开始,原虫数量稳定在(0.99±0.32)×104个/mL(p=0.6877),溢流液中氨态氮的浓度维持在(3.91±1.10)mg/100mL;试验全期干物质消失率为62%±2%,总排气次数为(2370±33)次,总挥发性脂肪酸为(41.77±3.78)mmol/L(p=0.488)。因此该固液气分流式连续培养瘤胃模拟系统综合了批次培养和连续培养瘤胃模拟装置的特点,并能有效的模拟瘤胃发酵状况。     

Development of an oat-based biorefinery for the production of L(+)-lactic acid by Rhizopus oryzae and various value-added coproducts

A novel oat-based biorefinery producing L(+)-lactic acid and various value-added coproducts (e.g., beta-glucan, anti-irritant solution) is proposed. Pearling is employed for sequential separation of bran-rich fractions for the extraction of value-added coproducts. Lactic acid production is achieved via fungal fermentation of Rhizopus oryzae on pearled oat flour. Maximum lactic acid concentration (51.7 g/L) and starch conversion yield (0.68 g/g) were achieved when an oat flour concentration of 116.5 g/L was used. Oxygen transfer played a significant role with respect to lactic acid production and starch conversion yield. Rhizopus oryzae produced a range of enzymes (glucoamylase, protease, phosphatase) for the hydrolysis of cereal flour macromolecules. Enzyme production during fungal fermentation has been reported. The proposed biorefining strategy could lead to significant operating cost reduction as compared to current industrial practices for lactic acid production from pure glucose achieved by bacterial fermentations.     

Optimizing the molecular weight of oat β-glucan for in vitro bile acid binding and fermentation

A previous study showed β-glucan with low molecular weight (MW, 1.56×10(5) g/mol) bound more bile acid and produced greater amounts of short-chain fatty acids (SCFA) than did β-glucan with high MW (Mn=6.87×10(5) g/mol). In the current study, β-glucan extracted from oat flour was fractionated into six different MW levels (high MW, 7.09×10(5); low level 1 (L1), 3.48×10(5); L2, 2.42×10(5); L3, 1.61×10(5); L4, 0.87×10(5); and L5, 0.46×10(5) g/mol) and evaluated to find the optimum MW affecting in vitro bile acid binding and fermentation. The β-glucan fractions with 2.42×10(5)-1.61×10(5) g/mol (L2 and L3) bound the greatest amounts of bile acid. After 24 h of fermentation, no differences were found in total SCFA formation among L1, L2, L3, and L4 fractions; however, the high MW and L5 MW fractions produced lower amounts of total SCFA. Thus, the optimum MW of β-glucan to affect both hypocholesterolemic and antitumorigenic in vitro effects was in the range of 2.42×10(5)-1.61×10(5) g/mol. This MW range also was the most water-soluble among the MWs evaluated.     

离子注入诱变植物乳杆菌选育CLA高产突变株的研究

以A6-1为出发菌株,采用N+离子注入的方法进行诱变处理,注入能量为50keV,注入剂量为1×1013、3×1013、5×1013、8×1013、10×1013、30×1013、50×1013、80×1013、100×1013ion/cm2,真空度为10-3Pa。结果显示,菌体的存活率随离子注入剂量的增加呈"马鞍型"曲线,"鞍脊"出现在30×1013ions/cm2～50×1013ions/cm2之间,此时菌体的存活率在20%～35%之间。综合考虑存活率、总突变率、正突变率和突变幅度等因素,推荐30×1013ions/cm2作为离子注入植物乳杆菌的适宜诱变剂量。从所有的注入处理中挑选CLA转化能力提高了50%以上的突变株进行传代稳定性试验,发现F菌株经8次传代后产CLA的稳定性最好。该突变株各代的产量平均为162.5μg/ml,比出发菌株提高了69.87%,将此突变菌株命名为A6-1F。     

PAM特性对花岗岩崩岗崩积体径流及产沙的影响

研究利用人工模拟降雨,研究不同分子量（800万、1 200万和1 500万）,不同水解度（10%,20%,30%）聚丙烯酰胺（PAM）对崩岗崩积体土壤侵蚀和径流的影响。结果表明:3种分子量和水解度的PAM都能够减少土壤侵蚀量,1 200万分子量PAM处理土壤侵蚀的效果最好,PAM的水解度对抗侵蚀影响差异不明显;各种PAM处理均使径流量增加,随着分子量的变大,径流量也在增加,而同一分子量的PAM,其水解度对径流量和侵蚀量的影响大致成反比关系;PAM处理下侵蚀土壤中不同粒径颗粒的含量会发生变化,砂粒的含量会有所增加,粉粒和黏粒的含量会减少。综合价格和抗侵蚀效果来看,1 200万10%水解度的PAM更适合于崩岗崩积体侵蚀治理。     

堆肥隧道式后发酵技术及效果

该文采用发酵隧道对堆肥进行后发酵处理,并测定发酵过程中的温度、pH值、含氮量、微生物的变化,旨在为集约化生产双孢蘑菇培养料提供理论依据。该技术可以对堆肥进行10 h以上的巴氏灭菌（温度在57～62℃之间）处理和5 d的腐熟处理（温度在45～53℃之间）。处理后发酵堆肥中氮质量分数从1.58%增加至1.85%;pH值从8.7下降到7.5。嗜热细菌的菌落数从5.2×108 cfu/g上升到7.3×108 cfu/g（第3天）,发酵结束时降低为2.88×108 cfu/g;放线菌和嗜热真菌菌落数发酵开始时分别为2.4×105 cfu/g 和3.2×104 cfu/g,发酵结束时分别为19.6×105 cfu/g和10.1×104 cfu/g。试验结果表明,经过隧道式后发酵的堆肥适合于双孢蘑菇生长需要,隧道式后发酵技术可以用于规模化生产优质双孢蘑菇培养料。     

Sucrose metabolism and exopolysaccharide production in wheat and rye sourdoughs by Lactobacillus sanfranciscensis.

The exopolysaccharide (EPS) produced from sucrose by Lactobacillus sanfranciscensis LTH2590 is predominantly composed of fructose. EPS production during sourdough fermentation has the potential to affect rheological properties of the dough as well as the volume, texture, and keepability of bread. Its in situ production by L. sanfranciscensis LTH2590 was demonstrated during sourdough fermentation after the hydrolysis of water soluble polysaccharides. In wheat and rye doughs with sucrose addition the concentration of fructose in the hydrolysate of polysaccharides was significantly higher than that in the hydrolysate of control doughs or doughs without sucrose addition. EPS production by L. sanfranciscensis in wheat doughs was confirmed by the determination of delta (13)C values of water soluble polysaccharides after the addition of naturally labeled sucrose, originating from C(3)- and C(4)-plants. In rye doughs, evidence for EPS production with the isotope technique could be demonstrated only by the determination of delta (13)C values of fructose from water soluble polysaccharides. In addition to EPS formation from sucrose, sucrose hydrolysis by L. sanfranciscensis in wheat and rye sourdoughs resulted in an increase of mannitol and acetate concentrations and in accumulation of glucose. It was furthermore observed that flour arabinoxylans were solublized during the fermentation.     

多轮次筛选选育高酚酸耐受性丁醇生产菌

纤维原料预处理过程中会产生酚酸等抑制菌株生长的物质,为选育出高丁醇产量及高耐受酚酸胁迫丁醇生产菌株,该研究利用多因子复合筛选策略筛选出一株能够合成足够还原力与对丁醇耐受性较好的菌株Clostridium beijerinckii W6。通过丁醇胁迫适应性进化获得丁醇耐受菌W6-1,其丁醇和总溶剂产量相较于菌株W6分别提高了14.01%和16.85%。通过紫外诱变处理菌株W6-1并结合理性筛选模型最终获得丁醇产量较高菌株W6-2,其丁醇及总溶剂产量分别可达到（9.51±0.06）和（15.32±0.11）g/L。最后将菌株W6-2通过酚酸胁迫适应性进化得到突变菌W6-3,其能耐受1.0 g/L酚酸胁迫环境,且丁醇和总溶剂产量相较于菌株W6-2分别提高了18.17%和17.49%。当以葛渣水解液为底物进行丙酮丁醇发酵时,突变菌W6-3的丁醇产量达（8.54±0.31）g/L,相较于菌株W6-2提高了26.71%。经多轮次诱变及适应性进化处理获得的突变菌的酚酸耐受性及发酵性能均有较大提高,该文所采用的多轮次筛选方法可以为其他快速筛选优良生产菌提供可靠的理论参考。     

利用小麦秸秆生产木霉分生孢子及其生物有机肥对黄瓜的促生效果

【目的】木霉是重要的植物根际促生功能菌,然而木霉类生物肥料生产的应用基础研究很薄弱。本研究以小麦秸秆为发酵基质,探究哈茨木霉T-E5产分生孢子的固体发酵工艺条件,并验证发酵物作为生物有机肥的促生效果。【方法】在实验室条件下,以小麦秸秆为固体发酵基质,研究固体发酵的不同发酵方式,温度、酸浓度、酸种类、接种量、含水量、外加碳源和氮源等单因子条件下的产孢量;再利用正交试验设计,研究温度、酸浓度、含水量、接种量、外加氮源和碳源的发酵条件优化。利用两季温室盆栽试验测定包括施用化肥、有机肥、发酵物和不同肥料组合的5个不同施肥处理的黄瓜地上部生物量、株高和叶面积。采用稀释涂布法测定黄瓜盆栽根际土中总真菌数量和木霉菌数量。【结果】单因素条件优化:基质用稀硝酸 (0.1 mol/L) 调节酸度值后接种3%(v/w) 的1 × 107个/mL的T-E5孢子液,调节水分使初始含水量达到75%;在此条件下,添加尿素和玉米粉,在28℃下发酵培养8天,最大产孢量可达到8.87 × 109个/g。通过正交优化,每10 g小麦秸秆,加入调节酸度值的0.05 mol/L硝酸18.3 mL,含水量70%(湿基),接种量9%,添加尿素的量为1%,30℃浅盘培养8天,产孢量达到1.1 × 1010个/g。第1季盆栽试验结果表明,与单施化肥处理 (CCK) 相比,发酵产物与化肥配施 (CT) 使黄瓜的地上部分生物量、株高和叶面积分别提高14.97%、16.75%和14.64%;与单施有机肥处理 (OCK) 相比,发酵产物与有机肥配施 (OT) 使黄瓜的地上部分生物量、株高和叶面积分别提高10.62%、26.06%和9.53%。第2季盆栽也有类似的促生效果,与CCK相比,CT使上述指标分别提高12.83%、11.49%和26.93%;与OCK相比,OT使上述指标分别提高5.96%、34.29%和18.01%。两季盆栽添加木霉发酵物的处理中根际土总真菌数和木霉菌数量相比CCK、OCK和不施肥照 (CK) 均增加1个数量级以上。【结论】以小麦秸秆为主要原料,采用固体发酵工艺可生产高分生孢子含量的哈茨木霉菌剂及其生物有机肥,表明利用农业废弃物生产高附加值的木霉菌剂及其生物有机肥具有可行性。但木霉孢子数量主要受发酵条件影响,今后应在中试和工厂化生产水平进一步研究木霉孢子固体发酵的工艺参数。     

Assessment of selected antioxidants in tomato pomace subsequent to treatment with the edible oyster mushroom, Pleurotus ostreatus, under solid-state fermentation

Tomato pomace, delignified by the edible oyster mushroom, Pleurotus ostreatus, could be used as a poultry feed ingredient to provide alpha-tocopherol for retardation of lipid oxidation in postmortem meat if the antioxidant were retained in pomace after fungal fermentation. Experiments were conducted to investigate changes in the content of alpha-tocopherol, lycopene, and beta-carotene in tomato pomace after sterilization and treatment with P. ostreatus from 0 to 104 days. alpha-Tocopherol (39.26 to 31.15 microg/g) and lycopene (17.42 to 11.19 microg/g) significantly decreased during sterilization while beta-carotene (42.56 to 35.44 microg/g) did not. The content of carotenoids decreased by day 26 as compared to 0 day for the control and for treated samples. alpha-Tocopherol decreased during fungal fermentation at day 26 as compared to 0 day for the control and increased during the same period for treated samples. By 104 days, only alpha-tocopherol in control pomace was present in a significant amount. The alpha-tocopherol content of mushroom fruit grown in pomace (74.10 microg/g) and in wheat straw (51.36 microg/g) was not significantly different. Tomato pomace could be used as a substrate to successfully grow edible mushrooms; however, the initial level of selected antioxidants and their reduction during fungal fermentation must be considered when delignified pomace is utilized for selected nutrient content in animal feed or products for human consumption.     

汽爆预处理青玉米秸秆厌氧发酵特性

为了研究青玉米秸秆未汽爆和汽爆预处理后厌氧发酵产沼气特性,该文采用汽爆压力为2.5MPa,保压时间为90s,加入质量分数为30%的沼液,未气爆青玉米秸秆的TS(总固体物)质量分数为6%,汽爆预处理青玉米秸秆厌氧发酵的TS质量分数分别为1%、2%、3%、4%、6%、8%、10%和15%,考察了厌氧发酵过程中pH值和产气量随时间和TS质量分数的变化。结果表明:未汽爆秸秆在TS质量分数为6%时能够顺利厌氧发酵,但汽爆秸秆厌氧发酵液极易酸化,且无法调节,适宜的TS质量分数最大为4%;未汽爆秸秆挥发性固体产气率为214.6mL/g,汽爆秸秆在TS质量分数为3%时产气率最大,为334.8mL/g,比未处理秸秆提高了56%;未汽爆秸秆的产气速率为3.3mL/(g·d),汽爆秸秆产气速率随TS质量分数增大而减小,在TS质量分数为1%时最大,为14.8mL/(g·d)。青玉米秸秆经汽爆预处理后其厌氧发酵产沼气的产气率和产气速率大大提高,可以节约发酵时间,缩短发酵周期,有利于秸秆能源化利用的工业化生产。     

Kinetic study of the thermal hydrolysis of Agave salmiana for mezcal production

The kinetics of the thermal hydrolysis of the fructans of Agave salmiana were determined during the cooking step of mezcal production in a pilot autoclave. Thermal hydrolysis was achieved at different temperatures and cooking times, ranging from 96 to 116 °C and from 20 to 80 h. A simple kinetic model of the depolymerization of fructans to monomers and other reducing sugars and of the degradation of reducing sugars to furans [principally 5-(hydroxymethyl)furfural, HMF] was developed. From this model, the rate constants of the reactions were calculated, as well as the pre-exponential factors and activation energies of the Arrhenius equation. The model was found to fit the experimental data well. The tradeoff between a maximum fructan hydrolysis and a critical furan concentration in allowing for the best ethanol yield during fermentation was investigated. The results indicated that the thermal hydrolysis of agave was optimal, from the point of view of ethanol yield in the ensuing fermentation, in the temperature range of 106-116 °C and the cooking range time of 6-14 h. The optimal conditions corresponded to a fructan hydrolysis of 80%, producing syrups with furan and reducing sugar concentrations of 1 ± 0.1 and 110 ± 10 g/L, respectively.     

卷枝毛霉重组菌株Mc-MT-2培养条件优化及产油特性

前期工作构建了苹果酸转运蛋白基因过表达的卷枝毛霉重组菌株Mc-MT-2,该菌株的脂质含量大幅度提高。该研究从培养基成分筛选、微生物生长控制以及发酵模式等方面深入探讨Mc-MT-2菌株发酵产油脂的调控策略。结果表明,Mc-MT-2菌株最佳生长及产孢培养条件是以葡萄糖与苹果酸为复合碳源且复合配比为9∶1,氮源为胰蛋白胨,其他成分同Kendrick培养基,初始pH值为5。经分批培养获得生物量、脂质含量和脂质产量分别为11.2 g/L,24%和2.6 g/L。在3 L发酵罐扩大培养中,补料培养Mc-MT-2菌株获得生物量、脂质含量和脂质产量最大值为15.4 g/L、28.6%和4.4 g/L,比分批培养分别提高1.38、1.19和1.69倍。该研究为卷枝毛霉重组菌株Mc-MT-2在脂质生产中的进一步应用奠定理论基础。