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The Nord Stream pipeline leaks on 26 September 2022 released 465 ± 20 kt of methane into the atmosphere, which is the largest recorded transient anthropogenic methane emission event. While most of the gas escaped directly to the atmosphere, a fraction dissolved in the water. So far, studies on the fate of this dissolved methane rely on pipeline volumetric estimates or spatially sparse concentration measurements and ocean models. Here, we use atmospheric measurements with broad spatial coverage obtained from an airborne platform to estimate outgassing of 19-48 t h -1 on 5 October 2022. Our results broadly agree with ocean models but reveal uncertainties such as inaccuracies in their spatial emission distribution. Thus, we provide a data-driven constraint on the fate of the methane from the Nord Stream pipelines in the Baltic Sea. These results demonstrate the benefit of a fast-response airborne mission to track a dynamic methane emission event., Competing Interests: Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

The quickly developing drone technology can be used efficiently in the field of pipeline leak detection. The aim of this article is to provide drone mission concepts for detecting releases from pipelines. It provides an overview of the current applications of natural gas pipeline surveys, it considers environmental conditions by plume modelling, it discusses suitable commercially available sensors, and develops concepts for routine monitoring of pipelines and short term missions for localising and identifying a known leakage. Suitable platforms depend on the particular mission and requirements concerning sensors and legislation. As an illustration, a feasibility study during a release experiment is introduced. The main challenge of this study was the variability of wind direction on a time scale of minutes, which produces considerable differences to the plume simulations. Nevertheless, the leakage rates derived from the observations are in the same order of magnitude as the emission rates. Finally the results from the modeling, the release experiment and possible drone scenarios are combined and requirements for future application derived., Competing Interests: Author DH-A was employed by Air Liquide. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Bretschneider, Bollmann, Houssin-Agbomson, Shaw, Howes, Nguyen, Robinson, Helmore, Lichtenstern, Nwaboh, Pogany, Ebert and Lampert.)

Microbial bioprocessing based on orthologous pathways constitutes a promising approach to replace traditional greenhouse gas- and energy-intensive production processes, e.g., for adipic acid (AA). We report the construction of a Pseudomonas taiwanensis strain able to efficiently convert cyclohexane to AA. For this purpose, a recently developed 6-hydroxyhexanoic acid (6HA) synthesis pathway was amended with alcohol and aldehyde dehydrogenases, for which different expression systems were tested. Thereby, genes originating from Acidovorax sp. CHX100 and the XylS/Pm regulatory system proved most efficient for the conversion of 6HA to AA as well as the overall cascade enabling an AA formation activity of up to 48.6 ± 0.2 U g CDW . The optimization of biotransformation conditions enabled 96% conversion of 10 mM cyclohexane with 100% AA yield. During recombinant gene expression, the avoidance of glucose limitation was found to be crucial to enable stable AA formation. The biotransformation was then scaled from shaking flask to a 1 L bioreactor scale, at which a maximal activity of 22.6 ± 0.2 U g -1 and an AA titer of 10.2 g L CDW -1 and an AA titer of 10.2 g L -1 were achieved. The principal feasibility of product isolation was shown by the purification of 3.4 g AA to a purity of 96.1%. This study presents the efficient bioconversion of cyclohexane to AA by means of a single strain and thereby sets the basis for an environmentally benign production of AA and related polymers such as nylon 6,6., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Cyclohexanone monooxygenase (CHMO), a member of the Baeyer-Villiger monooxygenase family, is a versatile biocatalyst that efficiently catalyzes the conversion of cyclic ketones to lactones. In this study, an Acidovorax-derived CHMO gene was expressed in Pseudomonas taiwanensis VLB120. Upon purification, the enzyme was characterized in vitro and shown to feature a broad substrate spectrum and up to 100% conversion in 6 h. Furthermore, we determined and compared the cyclohexanone conversion kinetics for different CHMO-biocatalyst formats, that is, isolated enzyme, suspended whole cells, and biofilms, the latter two based on recombinant CHMO-containing P. taiwanensis VLB120. Biofilms showed less favorable values for K S (9.3-fold higher) and k cat (4.8-fold lower) compared with corresponding K M and k cat values of isolated CHMO, but a favorable K I for cyclohexanone (5.3-fold higher). The unfavorable K S and k cat values are related to mass transfer- and possibly heterogeneity issues and deserve further investigation and engineering, to exploit the high potential of biofilms regarding process stability. Suspended cells showed only 1.8-fold higher K S , but 1.3- and 4.2-fold higher k cat and K I values than isolated CHMO. This together with the efficient NADPH regeneration via glucose metabolism makes this format highly promising from a kinetics perspective., (© 2021 The Authors. Biotechnology and Bioengineering published by Wiley Periodicals LLC.)

6-Aminohexanoic acid (6AHA) is a vital polymer building block for Nylon 6 production and an FDA-approved orphan drug. However, its production from cyclohexane is associated with several challenges, including low conversion and yield, and severe environmental issues. We aimed at overcoming these challenges by developing a bioprocess for 6AHA synthesis. A mixed-species approach turned out to be most promising. Thereby, Pseudomonas taiwanensis VLB120 strains harbouring an upstream cascade converting cyclohexane to either є-caprolactone (є-CL) or 6-hydroxyhexanoic acid (6HA) were combined with Escherichia coli JM101 strains containing the corresponding downstream cascade for the further conversion to 6AHA. ε-CL was found to be a better 'shuttle molecule' than 6HA enabling higher 6AHA formation rates and yields. Mixed-species reaction performance with 4 g l -1 biomass, 10 mM cyclohexane, and an air-to-aqueous phase ratio of 23 combined with a repetitive oxygen feeding strategy led to complete substrate conversion with 86% 6AHA yield and an initial specific 6AHA formation rate of 7.7 ± 0.1 U g CDW -1 . The same cascade enabled 49% 7-aminoheptanoic acid yield from cycloheptane. This combination of rationally engineered strains allowed direct 6AHA production from cyclohexane in one pot with high conversion and yield under environmentally benign conditions., (© 2020 The Authors. Microbial Biotechnology published by Society for Applied Microbiology and John Wiley & Sons Ltd.)

Cellulose fibres have poor reactivity and limited potential for surface engineering with advanced chemical functionalization in water. In this work, cellulose fibres were decorated with azide functions by charge-directed self-assembly of a novel water-soluble multifunctional cellulose derivative yielding reactive fibres. Propargylamine and 1-ethynylpyrene were utilized as a proof of concept that alkyne molecules may react with the azide functions of the reactive fibres via copper(I)-catalyzed azide-alkyne Huisgen cycloaddition (CuAAc) reaction in mild conditions. Chemical characterization of the fibres was carried out using classical techniques such as Raman-, fluorescence-, and UV-vis spectroscopy. Among other techniques, time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray spectroscopy (XPS), two-photon microscopy (TPM), and inductively coupled plasma mass spectrometry (ICP-MS) were useful tools for additional characterization of the fibres decorated with amino- or photoactive groups. The information gathered in this work might contribute to the basis for the preparation of reactive cellulose-based interfaces with potential application in CuAAc reactions., (Copyright © 2015 Elsevier Ltd. All rights reserved.)