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Bacterial ice nucleators (INs) are among the most effective ice nucleators known and are relevant for freezing processes in agriculture, the atmosphere, and the biosphere. Their ability to facilitate ice formation is due to specialized ice-nucleating proteins (INPs) anchored to the outer bacterial cell membrane, enabling the crystallization of water at temperatures up to -2 °C. In this Perspective, we highlight the importance of functional aggregation of INPs for the exceptionally high ice nucleation activity of bacterial ice nucleators. We emphasize that the bacterial cell membrane, as well as environmental conditions, is crucial for a precise functional INP aggregation. Interdisciplinary approaches combining high-throughput droplet freezing assays with advanced physicochemical tools and protein biochemistry are needed to link changes in protein structure or protein-water interactions with changes on the functional level.
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http://dx.doi.org/10.1021/acs.jpcb.1c09342 | DOI Listing |
Carbohydr Polym
November 2025
Institute of Nano and Biopolymeric Materials, School of Materials Science and Engineering, Tongji University, Shanghai 201804, China. Electronic address:
This work reports an ethanol-mediated freeze-drying (EMFD) strategy that enables the scalable production of high-performance bacterial cellulose aerogels (BCAs), effectively addressing key limitations of conventional methods such as supercritical drying and standard freeze-drying, including fragility, low mechanical strength, and high cost. Specifically, by replacing water in bacterial cellulose hydrogels (BCHs) with ethanol-water solution (EWs) prior to freeze-drying, the process limits ice crystal formation and reduces capillary forces and adhesion, thereby preserving structural integrity and enhancing mechanical properties. The effects of EWs concentration on BCA morphology, volume shrinkage, mechanical strength, and pore structure were systematically investigated.
View Article and Find Full Text PDFEnviron Microbiol Rep
October 2025
Department of Biology, Marine Biology Section, University of Copenhagen, Helsingør, Denmark.
Due to climate change, sea ice more commonly retreats over the shelf breaks in the Arctic Ocean, impacting sea ice-pelagic-benthic coupling in the deeper basins. Nitrogen fixation (the reduction of dinitrogen gas to bioavailable ammonia by microorganisms called diazotrophs) is reported from Arctic shelf sediments but is unknown from the Arctic deep sea. We sampled five locations of deep-sea (900-1500 m) surface sediments in the central ice-covered Arctic Ocean to measure potential nitrogen fixation through long-term (> 280 days) stable-isotope (N) incubations and to study diazotroph community composition through amplicon sequencing of the functional marker gene nifH.
View Article and Find Full Text PDFISME J
August 2025
School of Oceanography & Astrobiology Program, University of Washington, Seattle, WA, USA.
Despite growing evidence for the role of DNA methylation in bacterial acclimation to environmental stress, this epigenetic mechanism remains unexplored in sea-ice microbial communities known to tolerate multiple stressors. This study presents a first analysis of DNA methylation patterns in bacterial communities and associated viruses across the vertical thickness of sea ice. Using a novel stepped-sackhole method, we collected sea-ice brines from distinct horizons of an Arctic ice floe, capturing microbial communities that had been exposed to different environmental conditions.
View Article and Find Full Text PDFInt J Mol Sci
August 2025
Laboratory of Materials, Nanotechnologies and Environment, Faculty of Sciences, Mohammed V University in Rabat, BP: 1014, Ibn Battouta Avenue, Rabat 10000, Morocco.
The phytochemical profiles, antioxidant capacities, mineral composition, and antibacterial activities of () and () were explored through aqueous, ethanolic, and methanolic extractions. The extracts were analyzed for polyphenols, flavonoids, and tannins, and their antioxidant potential was assessed using the DPPH assay. UPLC-HRMS identified major bioactive compounds, including 6-gingerol and shogaol in , and piperine and piperlonguminine in .
View Article and Find Full Text PDFNucleic Acids Res
August 2025
Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland.
Integrative conjugative elements (ICEs) are mobile DNA that remain integrated within the host bacterial genome until they activate their excision and transfer. ICE transfer is initiated in a small subpopulation of cells that leads to transfer competence. Here we study the role of the ParB-like protein BisD for ICEclc transfer competence formation in Pseudomonas putida.
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