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Fungal endophyte associations have been suggested as a possible strategy of Antarctic vascular plants for surviving the extreme environmental conditions of Antarctica. However, the mechanisms by which this occurs are still poorly understood. The role of root fungal endophytes in nitrogen mineralization and nutrient uptake, as well as their impact on the performance of Antarctic plants, were studied. We tested root endophytes, isolated from Colobanthus quitensis and Deschampsia antarctica, for lignocellulolytic enzyme production, nitrogen mineralization, and growth enhancement of their host plants. Penicillium chrysogenum and Penicillium brevicompactum were identified using a molecular approach as the main root endophytes inhabiting C. quitensis and D. antarctica, respectively. Both root endophytes were characterized as psychrophilic fungi displaying amylase, esterase, protease, cellulase, hemicellulase, phosphatase and urease enzymatic activities, mainly at 4 °C. Moreover, the rates and percentages of nitrogen mineralization, as well as the final total biomass, were significantly higher in symbiotic C. quitensis and D. antarctica individuals. Our findings suggest that root endophytes exert a pivotal ecological role based not only to breakdown different nutrient sources but also on accelerating nitrogen mineralization, improving nutrient acquisition, and therefore promoting plant growth in Antarctic terrestrial ecosystems.

Despite the unique physiology and metabolic pathways of microbiomes from cold environments providing key evolutionary insights and promising leads for discovering new bioactive compounds, cultivable bacteria entrapped in perennial ice from caves remained a largely unexplored life system. In this context, we obtained and characterized bacterial strains from 13,000-years old ice core of Scarisoara Ice Cave, providing first isolates from perennial ice accumulated in caves since Late Glacial, and first culture-based evidences of bacterial resistome and antimicrobial compounds production. The 68 bacterial isolates belonged to 4 phyla, 34 genera and 56 species, with 17 strains representing putative new taxa. The Gram-negative cave bacteria (Proteobacteria and Bacteroidetes) were more resistant to the great majority of antibiotic classes than the Gram-positive ones (Actinobacteria, Firmicutes). More than 50% of the strains exhibited high resistance to 17 classes of antibiotics. Some of the isolates inhibited the growth of clinically important Gram-positive and Gram-negative resistant strains and revealed metabolic features with applicative potential. The current report on bacterial strains from millennia-old cave ice revealed promising candidates for studying the evolution of environmental resistome and for obtaining new active biomolecules for fighting the antibiotics crisis, and valuable cold-active biocatalysts.

Antarctica is a stressful ecosystem with few vascular plants, an ideal system to test positive interactions. Here, plants such as Deschampsia antarctica could generate more suitable micro-environmental conditions for the establishment of other plants (facilitation). We examined the co-occurrence of vascular plant species in the Antarctic Peninsula and assessed the potential nurse effect by D. antarctica on the native Colobanthus quitensis and the invasive Poa annua. We also measured the ecophysiological performance and survival of C. quitensis within and outside the canopy of D. antarctica in two study sites differing in stress levels. In addition, a survival experiment was conducted with the invasive Poa annua individuals within and outside D. antarctica individuals. In sites where present, target species co-occurred with D. antarctica in both Shetland Islands and Antarctic Peninsula. In agreement with the stress gradient hypothesis, we found evidence of facilitation between vascular Antarctic plant species. Specifically, we found that D. antarctica facilitates the native C. quitensis and the invasive P. annua and that the effect is stronger in more stressful sites. Additionally, C. quitensis distribution is compatible with an influence of either direct or indirect facilitation from D. antarctica. Facilitation between vascular plants may play a role structuring Antarctic plant communities. Thus, distribution of native species should be considered when assessing the introduction and spread of invasive species. Also, our results together with those from previous studies showed that the type and magnitude of biotic interactions may change with time and can depend on the plant traits considered.

Photovoltaic technology has proven to be a reliable, economical, and clean energy source that is capable of adapting to diverse geographical conditions. However, factors such as soiling overshadow these qualities, thus leading to production losses and affecting the profitability of this technology. For these reasons, soiling is a highly studied topic, which involves considering the physicochemical characterization of the deposited material, mitigation strategies, effect predictions, and cleaning mechanisms. However, there is a relatively unexplored area related to the microbiological contribution to soiling. The surface of photovoltaic modules, along with the deposited material and local atmospheric factors, fosters favorable conditions for the colonization of microorganisms. These microorganisms influence the soiling mechanisms and optical properties of photovoltaic modules. This work presents a detailed characterization of the microbial diversity present in the soiling deposited on photovoltaic modules installed in the Atacama Desert. Two study sites were defined: Antofagasta and the Solar Platform of the Atacama Desert, which have warm and cold desert climates, respectively. Mineralogical characterization tests, heavy metal analyses, TOC, and inorganic element analyses were conducted on the deposited material. Additionally, the culturable isolates and the metagenomic DNA of the soiling samples and biofilms grown on standard PV glass were characterized using next-generation sequencing. The results show that the deposited soiling contained a microbiological component that had adapted to extreme desert conditions. The presence of the genera Arthrobacter, Kocuria, and Dietzia were identified in the culturable isolates from Antofagasta, while Arthrobacter and Dietzia were obtained from the Solar Platform of the Atacama Desert. The metagenomic DNA was mainly represented by the genera Pontibacter, Noviherbaspirillum, Massilia, Arthrobacter, Hymenobacter, and Deinococcus at Antofagasta. However, at the Solar Platform of the Atacama Desert, the analyzed samples presented DNA concentrations below 0.5 ng/µL, which made their preparation unviable. At the PSDA, the biofilms formed by the genera Peribacillus and Kocuria were identified, whereas the UA showed a greater abundance of bacteria that favored biofilm formation, including those that belonged to the genera Bacillus, Sporosarcina, Bhargavaea, Mesaobacillus, Cytobacillus, Caldakalibacillus, and Planococcus. Based on these results, we propose a soiling mechanism that considers the microbiological contribution to material cementation.

This study is the first investigation of tree–insect–bacteria interactions in southern Romania, documenting the distribution of 19 insect species across various fruit trees and their insect-associated bacterial diversity. Insect species were identified through DNA barcoding, while bacterial communities in Anthomyia, Botanophila, Drosophila, and Scaptomyza insects were analyzed via 16S rRNA gene sequencing. Insect diversity varied across apple, cherry, plum, peach, and quince trees, with most species showing tree-specific distribution, except for Drosophila melanogaster, which was found on all tree species. Its presence was primarily influenced by fruit development stages rather than temperature changes. Insect bacterial communities comprised 51 genera across four phyla, predominantly Pseudomonadota and Bacillota, that varied by tree species rather than insect species, suggesting the potential role of these flies as bacterial vectors. Several potential pathogenic bacterial genera were identified as biomarkers within insect microbiomes, suggesting their involvement in disease transmission, particularly affecting apple and cherry trees. This study also provides the first report of seven insect species in Romania, being the first microbiome characterization of four dipteran species associated with regional fruit trees.

The two native Antarctic vascular plants, Deschampsia antarctica and Colobanthus quitensis, are mostly restricted to coastal habitats where they are often exposed to sea spray with high levels of salinity. Most of the studies regarding the ability of C. quitensis and D. antarctica to cope with abiotic stress have been focused on their physiological adaptations to tolerate cold stress, but little is known about their tolerance to salinity. We investigated whether rhizospheric bacteria associated to D. antarctica and C. quitensis improve the ability of Antarctic plants to tolerate salt stress. Salt tolerance was assayed in rhizospheric bacteria, and also their effects on the ecophysiological performance (photochemical efficiency of PSII, growth, and survival) of both plants were assessed under salt stress. A total of eight bacterial rhizospheric strains capable of growing at 4 °C were isolated. The strains isolated from D. antarctica showed higher levels of salt tolerance than those strains isolated from C. quitensis. The ecophysiological performance of C. quitensis and D. antarctica was significantly increased when plants were inoculated with rhizospheric bacteria. Our results suggest that rhizospheric bacteria improve the ability of both plants to tolerate salinity stress with positive effects on the adaptation and survival of vascular plants to current conditions in Antarctic ecosystem.

The microbial diversity and quantitative dynamics during the insect’s development stages constitute recently developed putative tools in forensic and medical studies. Meanwhile, little is known on the role of insects in spreading foodborne pathogenic bacteria and on the impact of these pathogens on the overall insects and feeding substrate microbiome composition. Here, we provide the first characterization of the bacterial communities harbored in adult and immature stages of Lucilia sericata , one of the first colonizers of decomposed human remains, in the presence of the foodborne pathogen Salmonella enterica using 16S rRNA Illumina sequencing and qPCR. The pathogen transmission from the wild adults to the second generation was observed, with a 10 1.25 × quantitative increase. The microbial patterns from both insect and liver samples were not influenced by the artificial introduction of this pathogenic foodborne bacteria, being dominated by Firmicutes and Proteobacteria. Overall, our results provided a first detailed overview of the insect and decomposed substrate microbiome in the presence of a human pathogen, advancing the knowledge on the role of microbes as postmortem interval estimators and the transmission of pathogenic bacteria.

Summary Members of the genus Pseudomonas inhabit diverse environments, such as soil, water, plants and humans. The variability of habitats is reflected in the diversity of the structure and composition of their genomes. This cosmopolitan bacterial genus includes species of biotechnological, medical and environmental importance. In this study, we report on the most relevant genomic characteristics of Pseudomonas sp. strain ABC1, a siderophore‐producing fluorescent strain recently isolated from soil. Phylogenomic analyses revealed that this strain corresponds to a novel species forming a sister clade of the recently proposed Pseudomonas kirkiae. The genomic information reveals an overrepresented repertoire of mechanisms to hoard iron when compared to related strains, including a high representation of fecI‐fecR family genes related to iron regulation and acquisition. The genome of the Pseudomonas sp. ABC1 contains the genes for non‐ribosomal peptide synthetases (NRPSs) of a novel putative Azotobacter‐related pyoverdine‐type siderophore, a yersiniabactin‐type siderophore and an antimicrobial betalactone; the last two are found only in a limited number of Pseudomonas genomes. Strain ABC1 can produce siderophores in a low‐cost medium, and the supernatants from cultures of this strain promote plant growth, highlighting their biotechnological potential as a sustainable industrial microorganism. ‘Pseudomonas chilensis’ strain ABC1 was fully sequenced. About 5% of the ABC1 genome is devoted to iron acquisition, including 37 ECF sigma factors. Strain ABC1 produces pyoverdine and has the genes for the production of yersiniabactin.

Thraustochytrids are unicellular protists belonging to the Labyrinthulomycetes class, which are characterized by the presence of a high lipid content that could replace conventional fatty acids. They show a wide geographic distribution, however their diversity in the Antarctic Region is rather scarce. The analysis based on the complete sequence of 18S rRNA gene showed that strain 34-2 belongs to the species Thraustochytrium kinnei, with 99% identity. The total lipid profile shows a wide range of saturated fatty acids with abundance of palmitic acid (16:0), showing a range of 16.1–19.7%. On the other hand, long-chain polyunsaturated fatty acids, mainly docosahexaenoic acid and eicosapentaenoic acid are present in a range of 24–48% and 6.1–9.3%, respectively. All factors analyzed in cells (biomass, carbon consumption and lipid content) changed with variations of culture temperature (10°C and 25°C). The growth in glucose at a temperature of 10°C presented the most favorable conditions to produce omega-3fatty acid. This research provides the identification and characterization of a Thraustochytrids strain, with a total lipid content that presents potential applications in the production of nutritional supplements and as well biofuels.

Bacteria colonizing bivalves play a critical role in host health by supporting digestion, nutrient cycling, and immune defense. While the microbiomes of marine bivalves have been studied globally, their diversity and functional roles across specific organs remain underexplored. This study investigates the structural and predicted functional diversity of bacterial communities associated with different organs (siphon, gills, and stomach) of the marine bivalve Mya arenaria Linnaeus, 1758, along with the surrounding sediments from the Romanian Black Sea coast, using 16S rRNA gene sequencing with Illumina technology. Bacterial communities within the bivalve differed markedly from those in the sediments and varied across organs. Sediment samples exhibited greater taxonomic diversity (19 phyla) than bivalve organs (14–15 phyla). Verrucomicrobiota dominated the siphon and gills, Spirochaetota were most abundant in the stomach, and Desulfobacterota predominated in sediments. Nitrate-reducing bacteria, particularly those from the genus Persicirhabdus , were prevalent in all organs and may contribute to host resilience under hypoxic conditions. The presence of Sulfurimonas in the stomach suggests a possible nutritional association, while halotolerant Woeseia species identified in sediments likely play a role in environmental nutrient cycling. Predictive functional profiling indicated potential bacterial involvement in various metabolic processes, including carbohydrate, amino acid, and energy metabolism. Additionally, pathways related to xenobiotic degradation and antibiotic biosynthesis were inferred across all sample types, indicating a potential capacity for broader ecological and possibly biotechnological roles. However, these functions were inferred from 16S rRNA data and require further validation through metagenomic or transcriptomic approaches. To our knowledge, this is the first detailed analysis of microbiome variability across different organs of M. arenaria , offering new insights into host–microbe interactions in this species.