生淀粉高浓度酒精发酵的研究

本研究利用国内常用的糖化酶制剂糖化生玉米面中的淀粉,同时接种酵母菌,在30℃下,探讨了玉米淀粉的高浓度酒精发酵工艺。选择到了一株产高浓度酒精酵母菌,H0菌株。发酵温度为30℃、pH4一s、加糖化酶量为每克原料300单位、酵母接种量3％(v／v)和原料加量为33．0％(w／v)时,这株酵母菌在70小时内可产生17．5％(v／v)的乙醇。如果原料加量为36．0％(w／v)时,该菌株在96小时内可以产生18．O％(v／v)的乙醇。在前一种加料情况下,成熟发酵醪中的pH为5、残还原糖为O．19％、残总糖为3．5“。在后一种加料情况下,成熟发酵醪中的pH为5、残还原糖为0．81％、残总糖为5．1％。     

从老抽酱醪中分离耐盐性酵母的研究

以老抽酱醪为实验材料进行耐盐性酵母菌种分离,并做菌种鉴定。分析了在不同盐度条件下耐盐性酵母菌的生长情况和生长过程中培养基总糖的消耗,可以发现实验得到的酵母在22％（质量与体积}E）盐度下依然能够良好生长。结果表明,实验分离出的No．2菌在同级盐度的条件下的生长量要明显高于No．1菌,但在乙醇产率方面,两株菌在相同的含盐量为16％（质量与体积比）的麦芽汁培养基中发酵8d,No．1菌的乙醇产率为3．1％（体积比）,No．2菌的乙醇产率2．9％（体积比）。     

用原生质体融合构建高产酒精酵母株

用单孢子分离、单倍体诱变、原生质体融合等手段,获得了酵母菌株——科生９０６４。用该菌的固定化细胞进行发酵玉米糖化醪生产酒精的扩大试验。经８个月的吨级生物反应器运转试验结果证明,该酵母凝胶粒子活性稳定,在玉米糖化醪液初糖浓度为１８％～２０％,ｐＨ值４.０～５.０,温度为３８～４０℃的条件下,发酵时间约为２０ｈ,终酒精含量达９％～１１％（Ｖ／Ｖ）,残糖含量为１.０％以下,理论转化率达９０％以上。并对新菌株的培养形态及生理生化特征等进行了研究,证明它是一株新型的酿酒酵母菌     

常压甘油自催化预处理麦草浓醪发酵纤维素乙醇

目前纤维素乙醇成本偏高的根本原因在于没有达到淀粉质乙醇发酵水平的"三高"(高浓度、高转化率和高效率)指标,提高水解糖液浓度和避免发酵抑制物来实现浓醪发酵,是解决问题的关键。文中以常压甘油自催化预处理麦草为底物,尝试采用不同发酵策略,探讨其浓醪发酵产纤维素乙醇的可行性。在优化培养条件(15%底物浓度,加酶量30 FPU/g干底物,温度37℃,接种量10%)下同步糖化发酵72 h,纤维素乙醇产量为31.2 g/L,转化率为73%,发酵效率0.43 g/(L·h);采用半同步(预酶解24 h)糖化发酵72 h,纤维素乙醇浓度达到33.7 g/L,转化率为79%,发酵效率为0.47 g/(L·h),其中(半)同步糖化发酵中90%以上纤维素已被糖化水解用于发酵;采用分批补料式半同步糖化发酵,补料到基质浓度相当于30%,发酵72 h时纤维素乙醇产量达到51.2 g/L,转化率为62%,发酵效率为0.71 g/(L·h)。在所有浓醪发酵中乙酸不足3 g/L,无糠醛和羟甲基糠醛等发酵抑制物。以上结果表明,常压甘油自催化预处理木质纤维素基质适用于纤维素乙醇发酵;分批补料式半同步糖化发酵策略可用来进行浓醪纤维素乙醇发酵;未来工作中提高基质纯度和强化酶解产糖是浓醪纤维素乙醇达到"三高"指标的关键。     

Logistic模型在不同还原糖初始浓度乙醇发酵中的应用

酿酒酵母(Saccharomyces cerevisiae)利用可发酵性糖生成乙醇的过程与效率受多种环境因素的影响。研究乙醇形成的动力学有利于理性认识乙醇形成机理,为放大与优化工艺条件提供理论指导。对Logistic模型方程重新参数化,将酵母生长动力学方程类比乙醇生成动力学,拟合性很好,对不同初始浓度还原糖的乙醇同步糖化发酵过程进行Logistic模型方程模拟,给出了乙醇浓度的显式函数模型,用310g/L玉米粉物料浓度的同步糖化发酵工艺,首次揭示在酿酒酵母工业菌株能够承受的一定的糖化醪还原糖浓度范围内,尽可能提高还原糖浓度至上限,可以缩短发酵周期,提高可发酵性糖转化为乙醇的转化率。这对于优化乙醇工业生产工艺条件、提高生产效率具有较重要的实践指导意义与应用价值。     

耐高温、耐酸产酒精酵母的筛选与鉴定

以白酒厂窖泥和生产用酒曲为材料,富集、分离得到32株酵母菌,从中筛选到1株产乙醇能力强,耐高温、耐强酸、起酵速度快的菌株Y30。该菌株能在45℃正常发酵,且致死温度达到59℃,比文献中报道高5℃;能在pH2．5的条件下正常发酵;能耐14％的酒精度;起酵速度快,接种4h后即开始发酵。对菌株进行形态分析、生理生化实验、Biolog鉴定和分子鉴定,确定该菌株为Saccharomyces cerevisia。该菌株的成功选育为后续高效生产乙醇提高了很好的菌种来源。     

乳酸菌D—80葡萄糖异构酶的研究

采用乳酸菌D-80为试验用菌种,经试验找出了适合产葡萄糖异构酶的培养条件。培养基含有：玉米芯水解液还原物1．2—1．4％,米糠饼2一4％,麸皮0.2～0.4％(二者经1398蛋白酶水解)及MnSO．0.05％。微量通风,开罐发酵,35—37℃培养。培养前期6—7小时,用NaoH调节发酵液pH为4．9—5．1。总的发酵时间为10一14小时。成熟醪中的菌体,经分离后,加入30—40％的葡萄糖浆,pH 6．4—6．7,MnSO4的含量10-4M,60—65℃的条件下转化,果糖的转化率为40％左右。经扩大试验后,进行技术鉴定,认为工艺路线基本上是合理的,经济上也是合算的,可进一步扩大试生产。     

酵母菌耐酒精机制的研究进展

乙醇是酵母菌发酵糖的重要产物之一．但是当乙醇在培养基中用积到一定浓度时,对酵母菌细胞产生有毒效应．然而,不同的酵母菌菌株对一定浓度的乙醇有不同的抗性,而且在不同培养条件下和生长在不同的培养基中同一株酵母菌对一定浓度的乙醇也有不同的抗性．最近几年来,有的学者从自然界中分离到了或通过遗传工程手段构建了一些能在短时间内产生高浓度酒精（发酵液中的乙醇浓度达到１７．５％ｖ／ｖ以上,而普通酵母菌只能产生９％一！！％ＶＩＶ乙醇）的酵母菌Ｉ‘］．因此酵母苗耐酒精的生化机制引起了许多研究者的浓厚兴趣,因为研究酵母…     

戊糖和己糖共发酵生产燃料乙醇条件研究

利用嗜鞣管囊酵母P-01对木糖和葡萄糖共发酵生产燃料乙醇的条件进行了试验研究,结果表明,木糖和葡萄糖混合液生产燃料乙醇的最佳条件为发酵液的pH值5.5、30℃、摇床转速120 r/min、接种量10%、发酵液初始糖浓度6%、葡萄糖与木糖之比为2、发酵周期为84h。在最佳发酵条件下,发酵醪液中的燃料乙醇浓度为2.101%,糖醇转化率为35%。     

自絮凝颗粒酵母乙醇连续发酵耦合酵母回用工艺的研究

模拟现有酒精发酵行业普遍采用的多级发酵罐串联系统,建立了一套由三级串联操作的搅拌式发酵罐和两个沉降罐组成的反应器系统,以脱胚脱皮玉米粉双酶法制备的糖化液为发酵底物,培养基初始还原糖浓度为220g/L,添加(NH4)2HPO41.5g/L和KH2PO42.5g/L,以0.057h-1的恒定稀释速率流加,将自沉降浓缩后的酵母乳先后经活化和不活化两种方式处理并循环至第一级发酵罐,系统在两种操作条件下分别达到了拟稳态。实验结果表明活化处理对改善发酵工艺技术指标方面发挥了显著的作用,发酵终点乙醇浓度达到101g/L,还原糖和残总糖分别在3.2和7.7g/L左右,发酵系统的设备生产强度指标为5.77g/(L.h),与无酵母回用的搅拌式反应器系统中自絮凝颗粒酵母乙醇发酵工艺相比,提高了70%。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.