Recombinant production of the lantibiotic nisin using Corynebacterium glutamicum in a two-step process

Background The bacteriocin nisin is naturally produced by Lactococcus lactis as an inactive prepeptide that is modified posttranslationally resulting in five (methyl-)lanthionine rings characteristic for class Ia bacteriocins. Export and proteolytic cleavage of the leader peptide results in release of active nisin. By targeting the universal peptidoglycan precursor lipid II, nisin has a broad target spectrum including important human pathogens such as Listeria monocytogenes and methicillin-resistant Staphylococcus aureus strains. Industrial nisin production is currently performed using natural producer strains resulting in rather low product purity and limiting its application to preservation of dairy food products. Results We established heterologous nisin production using the biotechnological workhorse organism Corynebacterium glutamicum in a two-step process. We demonstrate successful biosynthesis and export of fully modified prenisin and its activation to mature nisin by a purified, soluble variant of the nisin protease NisP (sNisP) produced in Escherichia coli. Active nisin was detected by a L. lactis sensor strain with strictly nisin-dependent expression of the fluorescent protein mCherry. Following activation by sNisP, supernatants of the recombinant C. glutamicum producer strain cultivated in standard batch fermentations contained at least 1.25 mg/l active nisin. Conclusions We demonstrate successful implementation of a two-step process for recombinant production of active nisin with C. glutamicum. This extends the spectrum of bioactive compounds that may be produced using C. glutamicum to a bacteriocin harboring complex posttranslational modifications. Our results provide a basis for further studies to optimize product yields, transfer production to sustainable substrates and purification of pharmaceutical grade nisin.

Selective ligand removal to improve accessibility of active sites in hierarchical MOFs for heterogeneous photocatalysis

Metal-organic frameworks (MOFs) are commended as photocatalysts for H2 evolution and CO2 reduction as they combine light-harvesting and catalytic functions with excellent reactant adsorption capabilities. For dynamic processes in liquid phase, the accessibility of active sites becomes a critical parameter as reactant diffusion is limited by the inherently small micropores. Our strategy is to introduce additional mesopores by selectively removing one ligand in mixed-ligand MOFs via thermolysis. Here we report photoactive MOFs of the MIL-125-Ti family with two distinct mesopore architectures resembling either large cavities or branching fractures. The ligand removal is highly selective and follows a 2-step process tunable by temperature and time. The introduction of mesopores and the associated formation of new active sites have improved the HER rates of the MOFs by up to 500%. We envision that this strategy will allow the purposeful engineering of hierarchical MOFs and advance their applicability in environmental and energy technologies.

The Trouble With Tinder

Although research indicates that almost all emerging adults in the U.S. use the internet, little is known about the online dating experiences of persons with disabilities. Particularly in developed countries, online dating currently accounts for a substantial proportion of the initiation of romantic relationships and promises numerous advantages for persons with disabilities. Online dating includes a way to escape disability stigma, at least initially, access to a wide network of potential partners, and a convenient, private, and efficient method of meeting them. Online daters can be strategic in how they present both themselves and their disabilities, the manner in which they communicate with potential partners, and whether they join a large, popular dating site or a specialized disability-oriented one. The chapter discusses how the nine-step process of online dating might differ for or challenge emerging adults with various types of disabilities, sharing relevant research and media examples when available. The implications of popular mobile dating apps are also considered.

Synthesis and structure of a new bulky bis(alkoxide) ligand on a terphenyl platform

A new sterically bulky chelating bis(alkoxide) ligand 3,3′-([1,1′:4′,1′′-terphenyl]-2,2′′-diyl)bis(2,2,4,4-tetramethylpentan-3-ol), (H2[OO]tBu), was prepared in a two-step process as the dichloromethane monosolvate, C36H50O2·CH2Cl2. The first step is a Suzuki–Miyaura coupling reaction between 2-bromophenylboronic acid and 1,4-diiodobenzene. The resulting 2,2′′-dibromo-1,1′:4′,1′′-terphenyl was reacted with t BuLi and hexamethylacetone to obtain the desired product. The crystal structure of H2[OO]tBu revealed an anti conformation of the [CPh2(OH)] fragments relative to the central phenyl. Furthermore, the hydroxyl groups point away from each other. Likely because of this anti–anti conformation, the attempts to synthesize first-row transition-metal complexes with H2[OO]tBu were not successful.

Au nanoparticle-decorated TiO2 hollow fibers with enhanced visible-light photocatalytic activity toward dye degradation

Plasmonic Au nanoparticles-decorated TiO2 hollow fibers with enhanced visible-light photocatalytic activity have been successfully prepared by a two-step process: (i) template method using kapok and (ii) solution plasma process.

Amelioration of Big Data Analytics by Employing Big Data Tools and Techniques

This chapter describes how in the digital data era, a large volume of data became accessible to data science engineers. With the reckless growth in networking, communication, storage, and data collection capability, the Big Data science is quickly growing in each engineering and science domain. This paper aims to study many numbers of the various analytics ways and tools which might be practiced to Big Data. The important deportment in this paper is step by step process to handle the large volume and variety of data expeditiously. The rapidly evolving big data tools and Platforms have given rise to numerous technologies to influence completely different Big Data portfolio.In this paper, we debate in an elaborate manner about analyzing tools, processing tools and querying tools for Big datahese tools used for data analysis Big Data tools utilize numerous tasks, like Data capture, storage, classification, sharing, analysis, transfer, search, image, and deciding which might also apply to Big data.

Particle Characterisation of Traditional Homeopathically Manufactured Medicine Cuprum metallicum and Controls

Background: Homeopathy is highly controversial. The main reason for this is its use of very highly dilute medicines (high homeopathic potencies, HHP), diluted beyond the Avogadro/Loschmidt limit. Research using several different methods has demonstrated the presence of particles, including nanoparticles of source material, in HHPs. This study aims to verify the results of a previous publication that detected the presence of particles in all dilutions. Methods: We used the Nano Tracking Analyzer (NTA) to examine dilutions of a commonly used homeopathic medicine, an insoluble metal, Cuprum metallicum, for the presence of particles. The homeopathic medicines tested were specially prepared according to the European pharmacopoeia standards. We compared the homeopathic dilutions/dynamizations with simple dilutions and controls including a soluble medicine. Results: We observed the presence of solid material in all preparations including HHPs (except for pure water). The measurements showed significant differences in particle sizes distribution between homeopathic manufacturing lines and controls. Conclusion: Homeopathic medicines do contain material with a specific size distribution even in HHPs diluted beyond the Avogadro/Loschmidt limit. This specificity can be attributed to the manufacturing and potentization process. This material demonstrates that the step-by-step process (dynamized or not) does not match the theoretical expectations in a dilution process. The starting material and dilution/dynamization method influences the nature and concentration of these NPs.

Preparation of nanocellulose by hydrolysis with ionic liquids and two-step hydrolysis with ionic liquids and enzymes

The aim of this study was to compare parameters of nanocellulose obtained by two different procedures: hydrolysis with ionic liquids (1-allyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium acetate) and hydrolysis with ionic liquids in combination with hydrolysis using a cellulolytic enzyme from Trichoderma reesei. Avicel cellulose was treated with two ionic liquids: 1-allyl-3-methylimidazolium chloride (AmimCl) and 1-ethyl 3-methylimidazolium acetate (EmimOAc). In the two-step hydrolysis cellulose after treatment with ionic liquids was additionally hydrolyzed with a solution of enzymes. In order to characterize the obtained material, the following analyses were used: infrared spectroscopy, X-ray diffraction and dynamic light scattering. The results indicated that cellulose obtained by two-step nanocellulose production methods (first hydrolysis with ionic liquids and then with enzymes) showed similar parameters (particle size, XRD patterns and degree of crystallinity) as the material after the one-step process, i.e. hydrolysis with ionic liquids.