UNLABELLED: Glacier-fed streams are permanently cold, ultra-oligotrophic, and physically unstable environments, yet microbial life thrives in benthic biofilm communities. Within biofilms, microorganisms rely on secondary metabolites for communication and competition. However, the diversity and genetic potential of secondary metabolites in glacier-fed stream biofilms remain poorly understood. In this study, we present the first large-scale exploration of biosynthetic gene clusters (BGCs) from benthic glacier-fed stream biofilms sampled by the Vanishing Glaciers project from the world's major mountain ranges. We found a remarkable diversity of BGCs, with more than 8,000 of them identified within 2,868 prokaryotic metagenome-assembled genomes, some of them potentially conferring ecological advantages, such as UV protection and quorum sensing. The BGCs were distinct from those sourced from other aquatic microbiomes, with over 40% of them being novel. The glacier-fed stream BGCs exhibited the highest similarity to BGCs from glacier microbiomes. BGC composition displayed geographic patterns and correlated with prokaryotic alpha diversity. We also found that BGC diversity was positively associated with benthic chlorophyll a and prokaryotic diversity, indicative of more biotic interactions in more extensive biofilms. Our study provides new insights into a hitherto poorly explored microbial ecosystem, which is now changing at a rapid pace as glaciers are shrinking due to climate change. IMPORTANCE: Glacier-fed streams are characterized by low temperatures, high turbidity, and high flow. They host a unique microbiome within biofilms, which form the foundation of the food web and contribute significantly to biogeochemical cycles. Our investigation into secondary metabolites, which likely play an important role in these complex ecosystems, found a unique genetic potential distinct from other aquatic environments. We found the potential to synthesize several secondary metabolites, which may confer ecological advantages, such as UV protection and quorum sensing. This biosynthetic diversity was positively associated with the abundance and complexity of the microbial community, as well as concentrations of chlorophyll a. In the face of climate change, our study offers new insights into a vanishing ecosystem.

• Klíčová slova
• biofilms, glacier-fed streams, microbiomes, secondary metabolites,
• MeSH
• Bacteria * genetika   metabolismus   klasifikace   MeSH
• biofilmy * růst a vývoj   MeSH
• ledový příkrov * mikrobiologie   MeSH
• metagenom MeSH
• mikrobiota * genetika   MeSH
• multigenová rodina MeSH
• řeky * mikrobiologie   MeSH
• Publikační typ
• časopisecké články MeSH

Microorganisms are a repository of interesting metabolites and functions. Therefore, accessing them is an important exercise for advancing not only basic questions about their physiology but also to advance technological applications. In this sense, increasing the culturability of environmental microorganisms remains an important endeavor for modern microbiology. Because microorganisms do not live in isolation in their environments, molecules can be added to the cultivation strategies to "inform them" that they are present in growth-permissive environmental conditions. Signaling molecules such as acyl-homoserine lactones and 3',5'-cyclic adenosine monophosphate belong to the plethora of molecules used by bacteria to communicate with each other in a phenomenon called quorum sensing. Therefore, including quorum sensing molecules can be an incentive for microorganisms, specifically soil bacteria, to increase their numbers on solid media.

• Klíčová slova
• acyl-homoserine lactones, cAMP, increased culturability, non-culturable bacteria, oligotrophic medium, signaling molecules,
• MeSH
• acylbutyrolaktony * metabolismus   MeSH
• Bacteria * metabolismus   MeSH
• quorum sensing fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acylbutyrolaktony * MeSH

Bacterial pathogenesis-associated characteristics such as biofilm formation, synthesis of hydrolyzing enzymes, and toxins are regulated by Acyl Homoserine Lactones (AHLs), small peptides and diffusing signal factors (DSF). Lelliottia amnigena is gram negative bacteria and its pathogenicity is regulated by the luxR and luxI class of quorum sensing. The signaling molecules and their concentrations are essential for the virulence of the pathogenic bacterium. To suppresses the pathogenicity; the concentration of signalling molecules must be controlled or degraded. The lactonase have the ability to hydrolyze lactones of different chain length. The present study deals with a newer approach to control the pathogenesis of Lelliottia amnigena through isolation and characterization of Aiia lactonase from Bacillus cereus RC1. Aiia lactonase specific primers were used to amplify the gene, and the sequence thus obtained was submitted to the Genbank database under accession # OK643884.1. The gene was cloned in pBE-S shuttle vector and transformed in the recombinant host. The expressed and purified protein had a molecular weight of 28.00 KDa and exhibited its optimum activity at 37℃ by inhibiting the violacein pigment of the monitor strain Chromobacterium violaceum MTCC 2656. The proteinaceous nature of the purified molecule was confirmed by incubating it in the presence of proteinase K for 1 h. The activity of the pathogenesis-related protein, polygalacturonase was drastically reduced in the presence of the purified Aiia protein. The purified protein also showed a zone of inhibition when plated together with Lelliottia amnigena RCE (MZ712952.1). Searches of the Conserved Domain Database suggested that this protein belonged to the Metallo-beta-lactamase superfamily and is closely related to Aiia from B. thuringiensis serovar kurstaki. Modeling of the protein structure was done using I-TASSER; a C-score of 0.55 suggested that the model was of good quality. To be used commercially, this recombinant protein needs to be purified at an industrial scale; it can then be used to repress the growth of soft rot causing bacteria in horticultural crops during their storage period.

• Klíčová slova
• Aiia gene, Bacillus Cereus RC1, Bacterial soft rot, Chromobacterium violaceum, Lelliottia amnigena RCE, Quorum quenching,
• MeSH
• acylbutyrolaktony * metabolismus   MeSH
• Bacillus cereus * genetika   metabolismus   MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• beta-laktamasy MeSH
• endopeptidasa K MeSH
• Enterobacteriaceae MeSH
• karboxylesterhydrolasy genetika   metabolismus   MeSH
• klonování DNA MeSH
• polygalakturonasa MeSH
• quorum sensing genetika   MeSH
• rekombinantní proteiny genetika   MeSH
• trans-aktivátory genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acylbutyrolaktony * MeSH
• bakteriální proteiny MeSH
• beta-laktamasy MeSH
• endopeptidasa K MeSH
• karboxylesterhydrolasy MeSH
• polygalakturonasa MeSH
• rekombinantní proteiny MeSH
• trans-aktivátory MeSH