全营养流加对谷氨酸棒杆菌发酵产L-异亮氨酸的影响

在谷氨酸棒杆菌发酵产L-异亮氨酸的过程中,发酵后期菌体活力变弱,副产物增多,是限制L-异亮氨酸产业化的主要因素。研究通过3个阶段全营养流加策略探究最适发酵条件。首先,为解决L-异亮氨酸发酵中后期菌种活力下降的问题,实验通过利用发酵中后期全营养培养基流加策略,使得L-异亮氨酸达到了33.0 g/L。其次,为了解决初始发酵培养基高营养抑制问题,采用低浓度初始发酵培养基偶联发酵过程流加全营养控制策略,L-异亮氨酸达到了36.8 g/L。最后,由于玉米浆的高用量造成发酵染菌、起泡过多及后提取困难等产生的问题,通过清洁氮源丝肽粉等比例替换玉米浆全营养流加实验,使得副产物缬氨酸(valine,Val),亮氨酸(leucine,Leu),丙氨酸(alanine,Ala)分别降低到1.4、0.8、0.5 g/L,比初始降低了82.5%、86.7%和88.9%。通过上述3个阶段全营养流加策略,使得L-异亮氨酸产量提升的同时,副产物生成也得到有效的抑制。     

桑葚酒用非酿酒酵母的筛选及特性研究

为筛选出适合桑葚酒发酵的非酿酒酵母,改善桑葚酒的口感及香味,以桑葚及桑园土壤样品中筛选得到的72株酵母菌为出发菌株,经杜氏管发酵、酒精发酵与感官品评进行初筛。将初筛得到的酵母分别与酿酒酵母（Saccharomyces cerevisiae）BO213按1∶1的比例接种到桑葚汁中发酵,通过感官品评与理化分析优选出一株非酿酒酵母JM-7,经鉴定该酵母为异常威克汉逊酵母（Wickerhamomyces anmalus）。其与菌株BO213混酿的桑葚酒感官评分为90.2分,总酯含量为3.21 g/L,还原糖含量为3.9 g/L,酒精度、总酸、挥发酸含量分别为11.7%vol、7.97 g/L、0.51 g/L。研究菌株JM-7生长曲线及耐受性发现,该酵母生长速率快,5 h即进入对数期,36 h达到稳定期,最高菌体浓度为4.5×108 CFU/mL,对温度、pH、SO2都有较好的耐受性,在16～36 ℃、pH 2～10、SO2质量浓度0～100 mg/L均能正常生长,但对酒精的耐受性较差,在酒精度为8%vol时生长受到抑制,在12%vol时不能生长。     

蚕丝织物的天然染料染色

文章介绍了天然染料的分类以及几种天然染料对蚕丝织物的染色性能。提出了采用新型媒染剂、蛋白酶预处理、分散染料颗粒和固色工艺等改善天然染料染色性能的方法。     

HBP-QAC改性蚕丝织物活性染料无盐染色

采用环氧氯丙烷与三乙胺对端氨基超支化聚合物进行改性,制备部分端基为季铵盐的超支化聚合物(HBP-QAC)改性剂,并对蚕丝织物进行阳离子改性。讨论HBP-QAC用量、Na2CO3用量、温度及时间对改性蚕丝织物活性染料无盐染色性能的影响。得到较佳的改性工艺:改性剂HBP-QAC用量5g/L,Na2CO3用量1g/L,温度50℃,时间40min,浴比1∶50。测试结果表明:改性蚕丝织物采用活性染料无盐染色,可获得与未改性蚕丝织物常规染色相当的K/S值和染色牢度。     

Modification and Dyeing of Silk Fabric Treated with Tetrabutyl Titanate by Hydrothermal Method

Nano-structured TiO₂ particles prepared by hydrothermal method are first immobilized on the surface of silk fiber using tetrabutyl titanate, which is dyed with C.I. Reactive Blue 19. The morphology, crystalline phase, chemical structure, thermal, and optical properties of silk fabric before and after treatment are determined by means of scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, thermal gravimetric, and diffuse reflectance spectrum techniques. The UV protection, percentage of exhaustion, percentage of fixation, K/S value, and color fastness are investigated. The results indicate that when silk fabric is treated with tetrabutyl titanate aqueous solution at 110 °C for 2 h, pure anatase phase TiO₂ nanoparticles of size less than 10 nm are synthesized, and then simultaneously grafted onto fiber surface. Compared with the original fabric, the thermal stability of the TiO₂-coated fabric changes little. The protection against ultraviolet radiation is distinctly improved. The yellowness and whiteness values change a little. The percentage of exhaustion, fixation and K/S value are reduced to some extent due to the existence of TiO₂ film. The color fastness to wet rubbing decreases slightly. The K/S value of the TiO₂-coated fabric increases after being scrubbed. The color fastness to light of silk fabric after treatment is enhanced.     

玉米须活性成分提取及其保健机理研究进展

玉米须是一味常用的中药,药用历史源远流长。玉米须中含有多糖、黄酮、甾醇、有机酸、皂苷等多种活性成分,具有抗癌、降血糖血脂、干预糖尿病、保护肝肾、抗氧化、抗菌消炎等保健功效。但当前玉米须资源利用效率较低且相关高附加值产品的开发缺乏深度,而深入解析玉米须中活性成分的作用机制有助于玉米须资源的利用及相关产品的开发。本文对玉米须中已报道的活性物质其成分、分离方法及作用机理研究进展进行论述,并对玉米须活性成分的基础研究及应用研究方向进行展望,以期为该领域后续深入研究及相关产品开发提供参考。     

一株胶红酵母Rhodotorula mucilaginosa YG14的筛选及混菌发酵提高梗丝品质

基于产香及促进漆酶合成的特性,从烟梗中筛选获得一株产类胡萝卜素物质的胶红酵母YG14(Rhodotorula mucilaginosa YG14)。通过灵芝菌、胶红酵母YG14单菌和共培养混菌固态发酵梗丝,进行了细胞壁物质成分分析、梗丝中性致香成分检测及品吸质量评价。结果表明,筛选获得的胶红酵母YG14与灵芝菌共培养后,混菌固态发酵梗丝在细胞壁物质降解、中性致香成分质量分数和感官品吸等方面的改善比两株菌单独固态发酵梗丝效果显著增强。共培养混菌固态发酵结束后梗丝总细胞壁物质降解率达到37.20%;中性致香成分质量分数提升20.44%;感官品吸评价为甜感提升明显,木质气息改善明显,香气量有一定提升,灼烧刺激感改善明显,香气更显圆润。胶红酵母YG14与灵芝菌共培养后固态发酵梗丝能够显著改善梗丝的品质,增加梗丝在卷烟中的利用率。     

Optimization of ultrasound-assisted extraction of anthocyanins from mulberry, using response surface methodology

Mulberry is one of the most widely used traditional Chinese medicines. Anthocyanins are the main bioactive components of mulberry, and possess important biological activities, such as antimicrobial, anti-inflammatory and antioxidant activities. This study investigated the ultrasound-assisted extraction (UAE) of anthocyanins from mulberry by using response surface methodology (RSM). The extraction conditions associated with anthocyanin yield, including extraction solvent, liquid-to-solid rate, temperature and extraction time, are discussed. The optimal conditions obtained by RSM for UAE from mulberry include 63.8% methanol contains 1% (v/v) trifluoroacetic acid (TFA), 43.2 °C temperature, 23.8 (v/w) liquid-to-solid ratio, and 40 min time for the maximum yield (64.70 ± 0.45 mg/g). The results indicated that the UAE can be an effective method for the extraction of some active components from plant materials.     

Understanding the Mechanical Properties of Antheraea Pernyi Silk—From Primary Structure to Condensed Structure of the Protein

Antheraea pernyi (A. pernyi) silk is produced and used by “wild” silkworms to construct a cocoon, but the primary structure of its protein is rather similar to that of spider major ampullate silk used to build web and dragline. Studies on this specific silk may provide valuable knowledge about the structure‐property relationship for the whole animal silk family. In this work, A. pernyi silk fibers with few macroscale defects are obtained by forcibly reeling, and are investigated in detail. It is found that such silk fibers display breaking stress and toughness of the same magnitude as spider major ampullate silks and forcibly reeled mulberry silk. The other mechanical properties, such as elasticity, supercontraction, and the effect of water on modulus are between those of spider major ampullate silks and mulberry silk. Therefore, an interpretation of the connection between the primary structures of silk proteins and the mechanical properties of silks is proposed here based on the ordered fraction, which in turn is determined by both the protein sequence and spinning process of the silk.