Carmen Rizzo ¹ Syed G. Dastager ² Hilal Ay ^3*

• ¹ Anton Dohrn Zoological Station Naples, Naples, Campania, Italy
• ² NCIM Resource Center, Biochemical Sciences Division, National Chemical Laboratory (CSIR), Pune, India
• ³ Yildiz Technical University, Faculty of Arts and Science, Department of Molecular Biology and Genetics, Istanbul, Türkiye

Microorganisms are the most diverse and abundant organisms essential for biogeochemical cycles and the functioning of ecosystems. They have also been considered the most profitable sources of bioactive natural products for over a century. Therefore, microbial diversity is crucial for the sustainability of ecosystem function and biotechnological applications of microbial natural resources, particularly for health-related advances. In this regard, polar and subpolar habitats, including microbial symbioses, are paramount for maintaining biodiversity and community composition, as global climate change can dramatically affect these extreme and unique environments (Bhat et al., 2022). In recent decades, the emergence of genomic technologies has provided insights into understanding the diversity, function, adaptation and evolution of microorganisms and microbial communities in diverse global environments (Ramasamy et al., 2023). Genome-resolved metagenomic studies have significantly expanded the family tree of life by providing a clear representation of the phylogenetic diversity of microorganisms (Royo-Llonch et al., 2021; Pessi et al., 2023;Greco et al., 2024). Therefore, more comprehensive studies of microbial biodiversity in polar habitats could help model the impacts of global climate change on these vulnerable ecosystems and provide new sources for bioprospecting.Due to the extreme physicochemical conditions of polar environments, bioactive secondary metabolites produced by polar microorganisms can exhibit enormous scaffold diversity and structural complexity (De Pascale et al., 2012). In addition, cold-active genes from Arctic and Antarctic microorganisms are considered valuable sources of antifreeze proteins, extracellular polymeric substances and polyunsaturated fatty acids with potential applications in medicine, agriculture, food and textile industries (Ramasamy et al., 2023). Although several natural products with bioactivity and cold-active enzymes have been isolated from polar and subpolar environments (Prasad et al., 2014), there is an urgent need to uncover the microbial biodiversity and bioprospecting potential of these environments by using culture-dependent and cultureindependent genomics approaches, including the construction of metagenomic assembled genomes. Understanding the microbial and chemical diversity of Arctic and Antarctic habitats also offers the opportunity to relate this diversity to ecosystem and evolutionary parameters.The articles published in the "Research Topic" collection addressed various aspects of polar microbial ecology and bioprospecting, highlighting the importance of exploring extremophilic microorganisms from cryosphere environments as untapped reservoirs of chemical diversity based on their specialized adaptive strategies necessary for survival in harsh environmental conditions. The study provided by Jaarsma and coauthors aimed to investigate the bacterial biosynthetic potential of glaciers and ice sheets, which are considered microbially controlled