Release of formaldehyde during the biofiltration of methanol vapors in a peat biofilter inoculated with Pichia pastoris GS115

BackgroundMethanol can be effectively removed from air by biofiltration. However, formaldehyde is one of the first metabolic intermediates in the consumption of methanol in methylotrophic microorganisms, and it can be released out of the cell constituting a secondary emission.ResultsThe total removal of methanol was achieved up to input loads of 263 g m⁻³ h⁻¹ and the maximum elimination capacity of the system was obtained at an empty bed residence times of 90 s and reached 330 g m⁻³ h⁻¹ at an input methanol load of 414 g m⁻³ h⁻¹ and 80% of removal efficiency. Formaldehyde was detected inside the biofilter when the input methanol load was above 212 g m⁻³ h⁻¹. Biomass in the filter bed was able to degrade the formaldehyde generated, but with the increase of the methanol input load, the unconsumed formaldehyde was released outside the biofilter. The maximum concentration registered at the output of the system was 3.98 g m⁻³ when the methanol load was 672 g m⁻³ h⁻¹ in an empty bed residence times of 60 s.ConclusionsFormaldehyde is produced inside a biofilter when methanol is treated in a biofiltration system inoculated with Pichia pastoris. Biomass present in the reactor is capable of degrading the formaldehyde generated as the concentration of methanol decreases. However, high methanol loads can lead to the generation and release of formaldehyde into the environment.How to cite: Guerrero K, Arancibia A, Cáceres M, et al. Release of formaldehyde during the biofiltration of methanol vapors in a peat biofilter inoculated with Pichia pastoris GS115. Electron J Biotechnol 2019;40. https://doi.org/10.1016/j.ejbt.2019.04.003.     

Combined strategies for improving production of a thermo-alkali stable laccase in Pichia pastoris

BackgroundLaccases are copper-containing enzymes which have been used as green biocatalysts for many industrial processes. Although bacterial laccases have high stabilities which facilitate their application under harsh conditions, their activities and production yields are usually very low. In this work, we attempt to use a combinatorial strategy, including site-directed mutagenesis, codon and cultivation optimization, for improving the productivity of a thermo-alkali stable bacterial laccase in Pichia pastoris.ResultsA D500G mutant of Bacillus licheniformis LS04 laccase, which was constructed by site-directed mutagenesis, demonstrated 2.1-fold higher activity when expressed in P. pastoris. The D500G variant retained similar catalytic characteristics to the wild-type laccase, and could efficiently decolorize synthetic dyes at alkaline conditions. Various cultivation factors such as medium components, pH and temperature were investigated for their effects on laccase expression. After cultivation optimization, a laccase activity of 347 ± 7 U/L was finally achieved for D500G after 3 d of induction, which was about 9.3 times higher than that of wild-type enzyme. The protein yield under the optimized conditions was about 59 mg/L for D500G.ConclusionsThe productivity of the thermo-alkali stable laccase from B. licheniformis expressed in P. pastoris was significantly improved through the combination of site-directed mutagenesis and optimization of the cultivation process. The mutant enzyme retains good stability under high temperature and alkaline conditions, and is a good candidate for industrial application in dye decolorization.     

极大螺旋藻藻蓝蛋白基因在巴斯德毕赤酵母X-33中表达的研究

通过PCR技术克隆了极大螺旋藻藻蓝蛋白基因，构建了克隆载体和表达载体，并将该基因导入巴斯德毕赤酵母X-33基因组，筛选了能够有效表达藻蓝蛋白基因的毕赤酵母工程菌株PC8，从而为发酵法生产藻蓝蛋白奠定了基础。     

Comparing the expression of human DNA topoisomerase I in KM71H and X33 strains of Pichia pastoris

BackgroundHuman is an essential cellular enzyme that is found in all human cells. As this enzyme is upregulated in cancer cells exceedingly, it is used as a target for cancer chemotherapeutic drug development. As such, producing the in-house enzyme for the purpose to speed up the search for more cost-effective and target specific hTopoI inhibitors is warranted. This study aims to compare the optimised conditions for the expression of hTopoI in KM71H (Mut^S) and X33 (Mut⁺) strains of Pichia pastoris. P. pastoris transfected with an hTopoI recombinant vector was used for the optimization of a higher level of hTopoI expression.ResultsIn the process, fed-batch cultivation parameters that influence the expression of hTopoI, such as culture temperature, methanol induction and feeding strategy, were optimised in the transfected KM71H and X33 P. pastoris strains in a shake flask system. The cell density and total protein concentration (protein level) of transfected P. pastoris were compared to determine the optimum culture conditions for each transfected P. pastoris strain. A higher hTopoI level was observed in the transfected KM71H culture supernatant (2.26 ng/mL) when the culture was incubated in the optimum conditions.ConclusionsThis study demonstrated that Mut^S strain (KM71H) expressed and secreted a higher level of hTopoI heterologous protein in the presence of methanol compared to the Mut⁺ strain; X33 (0.75 ng/mL). However, other aspects of optimization, such as pH, should also be considered in the future, to obtain the optimum expression level of hTopoI in P. pastoris.     

胃癌患者围术期营养支持的研究进展

大多数胃癌患者由于食欲欠佳和肿瘤的长期消耗,术前存在不同程度的营养不良综合症,加之手术的应激创伤及术后的长期禁食,则更加重患者的营养不良的各种临床表现,导致增加手术风险及并发症的发生率。在临床实践中,随着对胃癌病理生理的探索进步和新认识,结合对肠内营养(EN)和肠外营养(PN)研究成果,使得胃癌患者围术期营养支持的问题得到了较合理的解决。文章综述了目前国内外胃癌患者围术期营养支持的研究进展,希望能给同行们起到一定的参考借鉴作用。     

Stability of a forced system with a single nonlinear element in the feedback path

This paper presents a numerical technique to determine the stability of a nonlinear feedback control system with a single nonlinear element in the feedback path. By expressing the output explicitly in terms of the input the bounded inputand bounded output stability criterion of the nonlinear system is investigated.     

Framing and sources: a study of mass media coverage of climate change in Peru during the V ALCUE

Studies about mass media framing have found divergent levels of influence on public opinion; moreover, the evidence suggests that issue attributes can contribute to this difference. In the case of climate change, studies have focused exclusively on developed countries, suggesting that media influence perceptions about the issue. This study presents one of the first studies of media coverage in a developing country. It examines newspapers' reporting in Peru during the Fifth Latin America, Caribbean and European Union Summit in May 2008. The study focuses on the frames and the sources to provide an initial exploratory assessment of the coverage. The results show that the media relied mostly on government sources, giving limited access to dissenting voices such as environmentalists. Additionally, a prominence of "solutions" and "effects" frames was found, while "policy" and "science" frames were limited. The results could serve as a reference point for more comprehensive studies.     

坚持用科学发展观指导学术交流

科学发展观是我党执政理念的新飞跃。科学发展观的着眼点在于如何认识发展和怎样发展,要求我们考虑问题既要立足于现实,又要谋划长远。学术交流是科协以及所属科技团体的重要任务,科协必须用科学发展观指导学术交流工作,不断以创新和发展的思路,开创学术交流的新局面。甘肃省科协多年来指导所属学会,以促进科学技术的繁荣和发展,促进科学技术的普及和推广,促进科技人才的成长和提高,为社会主义物质文明和精神文明服务,为会员和科技工作者服务为宗旨,开展了一系列的学术交流活动。以1998年为例,举办国内学术会议560次,国际学术会议6次,参加人…     

论高校图书馆人性化服务与大学生阅读素养的提高

阅读素养是大学生学习能力的体现,高校图书馆是大学生学习的重要场所。针对当下高校学生的阅读现状,高校图书馆应当树立"以人为本"的理念,建议以人性化的方式和措施服务于读者,才能引导学生"爱读书、读好书",形成良好的阅读素养。     

On the definition of a tapology in Hilbert spaces with applications to the white noisy theory

In this paper a topology on Hilbert spaces is defined. The continuity of a map with respect to such a topology is equivalent to the uniform S-continuity around the origin, according to the Gross definition. An example of an application, in which the achieved gives a simple tool for providing the existence of stochastic solutions, is reported for a quite general class of non- linear differential equations driven by white noise.     

Go with the flow—a conceptual framework for supply relations in the era of the extended enterprise

The paper analyses the changes that an extended enterprise model of firms introduces into supply relations. After outlining the nature and characteristics of extended enterprises and the evolving nature of supply relations, the paper suggests a tool for supply network policy makers and a practical benchmarking tool for sectoral supply network management. It introduces the idea of value streams and flows and illustrates with empirical evidence from West Lothian, Scotland how and why supply networks are conduits of value and knowledge. The paper suggests how the value flow benchmarking tool may be used to approach decisions on the use of e-procurement and concludes with suggestions for further research.     

以合理的学术评价制度促进高校科研诚信建设

科研诚信是科研活动中必须遵循的基本伦理道德和行为规范。目前我国高校的科研活动存在着种种问题,论文剽窃、经费弄虚作假、成果评选潜规则等学术不端行为时有发生,而导致这些现象出现的一个原因就是现行学术评价制度的不完善。该文分析了现行学术评价制度的特点,认为它在一定程度上引发了科研人员急功近利的心态,催生了学术不端行为,并此基础上提出了应健全学术评价的评价机构和制度体系,淡化科研评价激励约束功能,从而促进高校科研诚信建设。     

Report of a trial with lyophilised QC sera in the CMCH/ACBI EQAS programmes in India

2000 vials of lyophilized QC of two different levels (low and high) were donated by Roche Diagnostics GmbH, through the IFCC and received by CMCH in June 2001. A total of 240 la boratories were enrolled for this 6 month pilot study. In addition to the 12 analytes in the liquid QC programme, six additional analytes, LDH, triglyceride, urate, total bilirubin, phosphate and amylase were included. It was also possible to measure sodium and potassium by ion selective electrode (ISE) methods in the QC for the first time. The performance of the laboratories for the existing 12 analytes using liquid stabilized QC was compared to the performance using lyophilized QC. Using a statistical comparison of the methodwise mean variance index score (MVIS) values, five assays viz glucose, albumin, cholesterol, and SGOT and SGPT performance was the same in liquid QC and lyophilized QC. Three assays viz urea, calcium and creatinine were significantly better, and 4 assays total protein, sodium, potassium and ALP were significantly worse. However the overall VIS (OMVIS) for the laboratories was the same and the ranking pattern of this 6 month OMVIS was also unaltered. The lyophilized QC scheme highlighted a negative bias between flame and ISE methods for sodium and potassium, and a definite standardization problem in reporting LDH and amylase results, but triglyceride, urate and total bilirubin assays were performing well. It was concluded that the introduction of lyophilized QCs will not cause any deterioration of performance to participating laboratories. Stability of the material seems to be good and the laboratories are generally using a good reconstitution technique.     

学会在建设资源节约型环境友好型社会中的作用

<正>资源节约型社会,是指在生产、流通、消费等领域,通过采取法律、经济和政策综合性措施,提高资源利用效率,以最少的资源消耗获得最大的经济和社会收益,保障经济社会全面协调可持续发展。环境友好型社会,是指人与自然和谐发展的社会,通过人与自然和谐发展来促进人与人、人与社会的和     

谈谈我馆过刊回溯性建库方法

探讨了过刊回溯性建库的方法及应注意的几个问题。     

个案管理在大学生学业困难帮扶中的应用研究--一个大学生学业困难帮扶的辅导案例

高校中,学业困难的学生越来越多,其表现也越来越具有多样性和复杂性。社会工作中的个案管理的方法值得借鉴和引入到学业困难学生的帮扶工作中。本文结合一例学业困难个案,探讨运用个案管理的方法,整合学生内外资源,开展全方位帮扶工作,增强大学生学业困难帮扶工作的专业性和实效性。     

煤炭企业环境管理的利益相关者协调机制构建

为了提升煤炭企业环境管理的有效性,运用利益相关者理论,对煤炭企业环境管理中的利益相关者进行了分析和梳理,进而提出了多方参与的利益相关者协调机制的构建路径。