Secondary metabolites (SMs) from environmental bacteria offer viable solutions for various health and environmental challenges. Researchers are employing advanced bioinformatic tools to investigate less-explored microorganisms and unearth novel bioactive compounds. In this research area, our understanding of SMs from environmental Gram-negative bacteria lags behind that of its Gram-positive counterparts. In this regard, Pedobacter spp. have recently gained attention, not only for their role as plant growth promoters but also for their potential in producing antimicrobials. This study focuses on the genomic analysis of Pedobacter spp. to unveil the diversity of the SMs encoded in their genomes. Among the 41 genomes analyzed, a total of 233 biosynthetic gene clusters (BGCs) were identified, revealing the potential for the production of diverse SMs, including RiPPs (27%), terpenes (22%), hybrid SMs (17%), PKs (12%), NRPs (9%) and siderophores (6%). Overall, BGC distribution did not correlate with phylogenetic lineage and most of the BGCs showed no significant hits in the MIBiG database, emphasizing the uniqueness of the compounds that Pedobacter spp. can produce. Of all the species examined, P. cryoconitis and P. lusitanus stood out for having the highest number and diversity of BGCs. Focusing on their applicability and ecological functions, we investigated in greater detail the BGCs responsible for siderophore and terpenoid production in these species and their relatives. Our findings suggest that P. cryoconitis and P. lusitanus have the potential to produce novel mixtures of siderophores, involving bifunctional IucAC/AcD NIS synthetases, as well as carotenoids and squalene. This study highlights the biotechnological potential of Pedobacter spp. in medicine, agriculture and other industries, emphasizing the need for a continued exploration of its SMs and their applications.

Microbial metabolomics allows understanding and to comprehensively analyse metabolites, and their related cellular and metabolic processes, that are produced and released to the extracellular environment under specific conditions. In that regard, the main objective of this research is to understand the impact of culture media changes in the metabolic profile of Pedobacter lusitanus NL19 (NL19) and Pedobacter himalayensis MTCC 6384 (MTCC6384) and respective influence on the production of biotechnologically relevant compounds. Solid-phase microextraction combined with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry with time-of-flight analyser (GC × GC-ToFMS) was applied to comprehensively study the metabolites produced by NL19 and MTCC6384 both in tryptic soy broth 100% (TSB100) and tryptic soy broth with 25% casein peptone (PC25). A total of 320 metabolites were putatively identified, which belong to different chemical families: alcohols, aldehydes, esters, ethers, hydrocarbons, ketones, nitrogen compounds, sulphur compounds, monoterpenes, and sesquiterpenes. Metabolites that were statistically different from the control (sterile medium) were selected allowing for the construction of the metabolic profile of both strains. A set of 80 metabolites was tentatively associated to the metabolic pathways such as the metabolism of fatty acids, branched-chain aminoacids, phenylalanine, methionine, aromatic compounds, and monoterpene and sesquiterpene biosynthesis. This study allowed to better understand how slight changes of the culture media and thus the composition of nutrients impair the metabolic profile of bacteria, which may be further explored for metabolomics pipeline construction or biotechnological applications.

The shift towards a circular economy, where waste generation is minimized through waste re-use and the development of valorization strategies, is crucial for the establishment of a low carbon, sustainable, and resource-efficient economy. However, there is a lack of strategies for re-using and valorizing specific types of waste, particularly those containing naturally occurring radioactive materials (NORM), despite the prevalence of industrial activities that produce such waste due to their chemical and radiological hazards. Living organisms, including fungi, are valuable sources of bioactive compounds with various industrial applications. In this study, we assessed the growth and metabolic profile changes of three white rot fungi species in response to low concentrations of a uranium mine effluent containing NORM and metals to explore their potential for producing biotechnologically relevant bioactive compounds. The growth rate was assessed in three different culture media, with and without the uranium mine effluent (1% V/V)), and the metabolic profile was analyzed using FTIR-ATR spectroscopy. Results suggested an improvement in growth rates in media containing the uranium mine effluent, although not statistically significant. T. versicolor showed promise in terms of bioactive compound production. The production of droplets during growth experiments and significant metabolic changes, associated with the production of bioactive compounds like laccase, melanin, and oxalic acid, were observed in T. versicolor grown in mYEPDA with the uranium mine effluent. These findings present new research opportunities for utilizing waste to enhance the biotechnological production of industrially relevant bioactive compounds and promote the development of circular economy strategies for re-using and valorizing NORM-containing waste.