Search Results (166)

Ornamental fountains in the Alhambra and Generalife (Granada, Spain) constitute complex socio-ecological systems where water, stone, and biological communities interact, making them highly vulnerable to biodeterioration caused by phototrophic microorganisms such as cyanobacteria, green algae, and diatoms. Conventional chemical biocides, although widely applied, present significant drawbacks including toxicity, material degradation, ecological imbalance, and limited long-term effectiveness. In this context, this study evaluated the potential of algicidal bacteria as a sustainable alternative for controlling phototrophic growth in heritage environments. Water samples from eight ornamental fountains were analyzed using 16S ribosomal RNA (16S rRNA) gene sequencing to characterize bacterial communities and identify taxa previously reported with algicidal activity. Statistical analyses were conducted to assess relationships between microbial community structure and biofilm development. In parallel, functional screening assays using filtered fountain waters against Chlorella vulgaris were performed to evaluate intrinsic inhibitory capacity. The most active sample was selected for bacterial isolation and further validation through co-culture assays, cell density measurements, and pulse-amplitude-modulated (PAM) fluorometry. A total of 18 genera with reported algicidal capacity were detected, representing a substantial fraction of the microbiome across all samples. However, no significant association was found between these taxonomic metrics and biofilm development, highlighting a decoupling between taxonomic composition and functional activity. The most active isolate, identified as Stenotrophomonas maltophilia strain LIG25, caused a rapid decline in photosynthetic efficiency and achieved more than 98% inhibition of algal growth. These findings demonstrate that ornamental fountain microbiomes represent a reservoir of native biocontrol agents and support the development of eco-friendly strategies for cultural heritage conservation. Full article

This study systematically compared the structural, functional, pathogenic, and assembly-mechanism characteristics of bacterial communities between urban and rural rivers across China, based on integrated water quality data from 421 sampling sites and 16S rRNA gene sequences from 475 sampling sites. The results revealed that urban rivers had significantly higher nutrient concentrations and bacterial α-diversity, along with lower β-diversity. Urban rivers were enriched with organic matter-degrading phyla such as Chloroflexi and Acidobacteriota and might exhibit more complex co-occurrence networks (average degree: 85.41). In contrast, rural rivers were enriched with phyla including Firmicutes and Cyanobacteria, as well as genera such as Exiguobacterium and Limnohabitans, and might display higher network modularity (modularity: 0.59) and greater spatial heterogeneity in community composition. Functional prediction indicated stronger carbon-cycling potential in urban rivers, whereas nitrogen-cycling functions did not differ between the two river types. Regarding pathogen composition, urban rivers contained a higher number of pathogen species than rural rivers. It was suggested that stochastic processes dominated community assembly in both systems; however, heterogeneous selection contributed more strongly in urban rivers (14.7%). Overall, this work elucidated systematic differences in bacterial community structure, function, pathogen profile, and assembly mechanisms between urban and rural rivers, offering a scientific foundation for differentiated watershed management. Full article

Microplastics (MPs) are emerging pollutants that affect soil–microbe interactions in paddy ecosystems. Periphytic biofilms (PBs) are complex microbial consortia that ubiquitously distribute at the soil–water interface of paddy ecosystems, playing essential roles in nutrient cycling and pollutant migration. However, whether MPs affect the community composition of PBs remains largely unknown. This microcosm study investigated the effects of three types of MPs (polyacrylonitrile, PAN; polyethylene, PE; and polyethylene terephthalate, PET) on the community characteristics of PBs via high-throughput sequencing (16S/18S rRNA) technology. Results showed that the addition of all MPs significantly increased the biomass and chlorophyll-a content of PBs, with PAN inducing the maximum increase (by 331.9% and 128.6%). However, all MPs had no significant effect on the PB α-diversity of bacterial and eukaryotic communities (p > 0.05). As for PB composition, PAN and PET increased the relative abundance of Cyanobacteria, Proteobacteria and Holozoa, PE increased that of Cyanobacteria, Bacteroidota and Blastocladiomycota, and all MPs decreased the relative abundance of Chloroflexi, Actinobacteriota and Basidiomycota. Furthermore, PET decreased the predicted functional potential of natural polymer degradation (cellulolysis, ligninolysis, xylanolysis, ureolysis), nitrogen fixation and nitrate ammonification, while PE increased predicted potential for plastic degradation, nitrate reduction and denitrification. Co-occurrence network analysis suggested that the PE network showed higher connectivity and lower modularity, while the PAN network showed higher modularity. This study advances our understanding of soil MPs–microbe interactions under high-concentration conditions. It also suggests that PB community characteristics may serve as potential bioindicators for soil MP pollution. Full article

Marine biofouling remains a major challenge for maritime industries, affecting submerged structures and vessels worldwide. The long-standing reliance on biocidal coatings, together with their documented environmental impacts, has led to increasingly restrictive regulations and an urgent demand for environmentally compatible antifouling (AF) solutions. This study evaluates the AF potential and toxicological profile of two nucleoside analogues, hypoxanthine arabinoside (1′) and 2′-deoxyinosine (2′), selected based on the previously reported non-lethal AF activity of the naturally occurring nucleosides adenosine and 2′-deoxyadenosine from cyanobacteria. Both analogues inhibited the growth of Navicula sp. by approximately 60% without inducing mortality and significantly reduced settlement of Mytilus galloprovincialis plantigrades, with EC₅₀ values of 5.50 µM (1′) and 8.54 µM (2′), and no lethality detected (LC₅₀ > 200 µM). At near-EC₅₀ concentrations, both compounds increased acetylcholinesterase and tyrosinase activities, supported by molecular docking results, suggesting involvement of neurotransmission- and byssal formation-related pathways. Proteomic analysis revealed compound-specific molecular responses. No lethal effects were observed in non-target organisms (LC₅₀ > 32 µM for A. amphitrite and LC₅₀ > 50 µM for A. salina), and environmental fate modelling predicted low bioaccumulation and rapid degradation. Overall, substitution of the amino group by a carbonyl group preserved AF efficacy without increasing toxicity, highlighting nucleosides as promising low-toxicity AF agents. Full article

The excessive use of chemical fertilizers in rice cultivation has contributed to soil degradation, creating a need for sustainable biological alternatives. This study examined the functional diversity of three indigenous nostocalean cyanobacterial strains (UP1, UP2, and UP3) isolated from forest and paddy field ecosystems by comparing the effects of their cellular biomass and extracellular polymeric substances (EPS) on rice seedling growth and soil properties. Morphological observations and partial 16S rRNA sequence analysis indicated that strains UP1 and UP2 were affiliated with the genus Ahomia, whereas UP3 was placed within the genus Nostoc. Together, these results placed all three isolates within the heterocystous cyanobacterial order Nostocales. The strains were further characterized based on EPS production and its degree of polymerization. Seed germination and seedling vigor assays were conducted to select the most effective biomass and EPS treatments, which were subsequently evaluated in 21-day pot experiments. Fresh biomass from strain UP2 most effectively enhanced rice growth, whereas EPS from strain UP3 promoted root development. EPS application from strain UP3 significantly increased root elongation to 13.44 cm, while high biomass levels of UP2 increased total sugar and free amino acid contents, indicating distinct plant response patterns. Soil analyses revealed differential responses between biomass- and EPS-based applications, with biomass generally producing stronger effects. Biomass from all strains was associated with higher physical soil function index (PSFI) values (up to 1.35). In contrast, improvements in chemical soil function index (CSFI) were observed across treatments, with variable responses and relatively higher values recorded in biomass from strain UP3 (up to 1.24). These findings suggest strain- and form-dependent response patterns of nostocalean cyanobacteria with potential for enhancing rice growth and improving soil functionality under the controlled conditions. Full article

Lichens represent a fundamental symbiotic association between fungi and photosynthetic organisms, such as algae or cyanobacteria, and are widely regarded as sensitive indicators of environmental change. Lichens’ capacity to colonize a wide range of ecological niches is attributed to their distinctive physiological characteristics, notably, their lack of protective cuticles and ability to uptake water and nutrients directly from the atmosphere. Concurrently, lichens are highly vulnerable to airborne contaminants, making them critical bioindicators of air quality. However, the survival of lichens is increasingly influenced by intensifying global change via agriculture, industrial activities, and vehicular emissions. Organic and inorganic pollutants can adversely affect lichen physiology by inducing pigment degradation, disrupting membranes, and altering lichen diversity. The synergistic stressors associated with global change, such as increasing temperatures and shifts in precipitation regimes, exacerbate the effects of atmospheric deposition and oxidative stress on lichens. Here, we present existing knowledge on lichens’ ecological functions, elucidate the mechanisms underlying their sensitivity to air pollution, and assess their utility for environmental monitoring amid accelerating global change. By recognizing lichens as dynamic ecological indicators, we underscore their dual role in sustaining ecosystem processes amidst rapid global change. Full article

Biological fermentation drying is an eco-friendly method for food waste treatment. It reduces waste mass and volume effectively. Microbial interactions drive drying efficiency. Yet these interactions remain unclear. Here we show that the inoculation of thermophilic strain and enrichment improved drying efficiency by 24.58% to 30.09%. The temperature comprehensive index and crude fat degradation rate in food waste were increased. The total nitrogen content was reduced by inoculation of thermophiles. The bacterial community was primarily composed of Proteobacteria, Bacteroidetes, and Firmicutes, with increased abundances of Proteobacteria, Actinobacteria, and Cyanobacteria. The fungal community included Ascomycota, Basidiomycota, Glomeromycota, and Chytridiomycota. Thermophilic Bacillus inoculation enhanced bacterial diversity, stabilized the fungal network, and influenced the dominant species in the bacterial-fungal cross-domain network at different stages of bio-drying. Environmental factors such as moisture content and conductivity significantly affected the size and complexity of the network. The study highlights the potential benefits of microbial inoculation and underscores the importance of understanding microbial dynamics and environmental factors in this process. Full article

Artificial water bodies in post-mining landscapes often remain chemically altered and ecologically degraded, yet their ecological risk is frequently underestimated by conventional water quality assessments. Persistent toxicity in mining-impacted waters is a global challenge, as acidity alone often fails to explain the adverse biological effects observed. This study assessed the ecological condition of three artificial ponds in a former gold–antimony mining area (Midões, northern Portugal), using an integrated framework that combined physicochemical and biological (phytoplankton and macroinvertebrates) elements with ecotoxicological assays. Ecotoxicity was evaluated using Lemna minor (growth inhibition) and Daphnia magna (acute toxicity, survival, and feeding rate) under untreated water and pH-adjusted conditions to disentangle acidity-driven effects from other chemical stressors. According to Water Framework Directive metrics, all ponds were classified as having moderate ecological potential, driven by persistent acidic conditions and elevated heavy metal concentrations (e.g., zinc and cadmium). Biological communities showed marked temporal/spatial variability, reflecting physicochemical differences among ponds. Phytoplankton showed summer blooms of cyanobacteria, while macroinvertebrates were generally dominated by tolerant taxa (exhibiting low taxonomic richness/diversity). Ecotoxicological assays showed consistent toxicity across all sampling periods, with high mortality and reduced feeding rates in D. magna and growth inhibition in L. minor. Notably, toxicity often persisted even after pH adjustment, indicating that the observed biological effects were not driven by acidity but were largely attributable to residual metal contamination. These findings highlight the ecological vulnerability of mining-impacted water bodies and underscore the need for management and remediation strategies that address metal removal in addition to pH correction. Full article

Continuous monocropping of cassava (Manihot esculenta Crantz) often leads to soil degradation and yield decline, commonly referred to as continuous cropping obstacles (CCOs), which are closely linked to changes in soil physicochemical properties and microbial communities. Biochar has been widely used as a soil amendment to improve soil quality and microbial activity and is considered a potential strategy for alleviating CCOs. Understanding the effects of biochar on soil bacteria and metabolites under field conditions is essential, as it provides insights into its practical effectiveness in reducing CCOs and improving soil health in cassava cultivation systems. In this study, a field experiment was conducted in a continuous cassava system to investigate the effects of a single biochar application rate on soil bacterial diversity, community composition, and metabolite profiles in both rhizosphere and bulk soils. High-throughput 16S rRNA gene sequencing and UHPLC–MS/MS-based non-targeted metabolomics were employed to analyze soil bacterial and metabolic patterns. Biochar was associated with increased α-diversity in rhizosphere soil and distinct shifts in β-diversity. Biochar increased the relative abundance of Chloroflexi and Actinobacteriota in the bulk soil, while Cyanobacteria and Nitrospirota were more abundant in the rhizosphere. Network analysis revealed the compartment-specific differences after biochar application, with higher network complexity in the rhizosphere and lower complexity in the bulk soil relative to the control. Metabolomic profiling identified 402 metabolites in positive ion mode and 357 in negative ion mode. In the rhizosphere, biochar-treated soil exhibited higher relative abundances of alkaloids (e.g., trigonelline, berberine, vincristine) and flavonoids (e.g., catechin, naringin, rutin, and taxifolin), which are commonly linked to plant stress responses. In the bulk soil, biochar application resulted in lower levels of several anthropogenic organic compounds (e.g., monobutyl phthalate, terephthalic acid, and p–toluenesulfonic acid). These findings provide preliminary field evidence that biochar application can lead to compartment-specific changes in soil bacterial communities and metabolite profiles. Such changes are closely related to soil quality and nutrient cycling, pointing to a possible role of biochar in mitigating soil degradation under continuous cassava cultivation. Full article

Soil degradation is closely related to the core issue of food security, making the assessment and monitoring of paddy soil quality particularly important. To clarify the impact of a rice–red claw crayfish co-culture on paddy soil quality, this research established two experimental groups: a rice monoculture and a rice–red claw crayfish co-culture. Using 16S rRNA and 18S rRNA sequencing technologies, we systematically compared soil characteristics, microbial diversity, and community composition under the two modes. Principal component analysis based on a minimum data set was employed to integrate soil property parameters with bacterial and eukaryotic microbial community indicators for a comprehensive assessment of the paddy soil quality index. The results showed that the rice–red claw crayfish co-culture substantially increased soil total nitrogen, available nitrogen, total phosphorus, available potassium, and cation exchange capacity. Simultaneously, the rice–red claw crayfish co-culture significantly influenced the beta diversity and composition of bacterial and eukaryotic microbial communities, significantly increasing the relative abundances of Bacteroidota, Cyanobacteria, Verrucomicrobiota, Arthropoda, Cryptomycota, and Nematoda. The soil quality index under the rice–red claw crayfish co-culture was markedly higher than that under the rice monoculture. In summary, a rice–red claw crayfish co-culture can enhance soil fertility and improve overall soil quality. By incorporating microbial community parameters into the evaluation index system, this study confirms that the rice–red claw crayfish co-culture system is indeed a sustainable agricultural practice, providing a theoretical basis for refining the soil quality assessment framework for rice–aquatic animal-integrated farming systems. Full article

The progressive degradation of surface waters should become one of the most important problems requiring an urgent solution. One of the methods developed is filtering water through loose, degraded sediments, blooms of cyanobacteria or algae, or a bed of hemp (Cannabis sativa L.) waste or hemp fibers. The conducted tests on the percolation of water samples and/or water with sediment from surface waters at sites with different ecological statuses indicate the possibility of using hemp waste for the reclamation of water reservoirs and rivers. The effect of filtration is a rapid improvement in water quality and, consequently, an improvement in the ecological status. The best result was achieved for a small freshwater reservoir with a large number of algae and loose degraded sediment. The initial turbidity value was at the limit of the device’s measurement capability, reaching 9991 NTU. After filtration through the hemp waste bed, the turbidity dropped to 42.52 NTU, a 99.57% decrease. The remaining parameters, C, TDS, and pH, were not subject to significant variability as a result of filtering. Excessive amounts of organic matter, which create a problem for surface waters, are removed. Due to the carrier (hemp waste), which is organic waste, any possible release of small amounts into the aquatic environment will not pose a threat. After applying filtration, a decision can be made on further actions regarding the water reservoir or river: Self-renewal of the reservoir or further percolation using, for example, mill gauze or cleaning the reservoir with other, non-invasive methods. After the filtering procedure, the hemp waste, enriched with organic matter and water remaining in the waste, can be used for composting or directly for soil mulching (preliminary tests have yielded positive results). A hemp waste filter effectively removes Chronomus aprilinus larvae (Chrinomidae) from water. This result indicates the possibility of removing mosquito larvae in malaria-affected areas. The use of hemp filters would reduce the amount of toxic chemicals used to reduce mosquito larvae. Improving the ecological status of surface waters by filtering contaminants with hemp waste filters can reduce the need for chemical treatment. The use of natural, biological filters enables sustainable surface water management. This is crucial in today’s rapidly increasing chemical pollution of surface waters. Full article

Cyanobacterial blooms are an escalating ecological concern driven by eutrophication and climate warming. Bloom-forming cyanobacteria can produce a broad spectrum of bioactive secondary metabolites. Among these, microcystins (MCs) are the most recognised hepatotoxins; however, natural populations of Planktothrix agardhii also synthesise numerous non-ribosomal peptides (NRPs) with poorly understood ecological roles and combined toxic effects. This review demonstrated the role of mixtures of P. agardhii cyanometabolites (oligopeptides and biogenic compounds) in cyanobacterial proliferation, emphasising the rapid evolution of chemotypes. The role of P. agardhii oligopeptides other than MCs in the cyanobacterial toxicity to duckweeds is also discussed. Laboratory experiments indicated that crude extracts containing complex peptide mixtures may inhibit Spirodela polyrhiza growth more strongly than pure MC-LR, suggesting synergistic effects within natural metabolite assemblages. Particular attention is given to variant-specific degradation pathways of MCs within duckweed-associated microbiota. By integrating biochemical, ecological, and microbiological perspectives, this synthesis outlines emerging directions in the study of mixtures of cyanobacterial peptides and other compounds, microbial degraders, and macrophyte-associated bioremediation strategies aimed at mitigating cyanotoxin risks in aquatic environments. Full article

The atmosphere plays a pivotal role in modulating the interactions between microorganisms and their surrounding environments, influencing ecological cycles, heritage conservation, and providing opportunities for novel applications. Recent studies have highlighted the role of microbial responses to atmospheric conditions as indicators of environmental change. This study highlights the role of climate change, particularly rising temperatures, on the growth of cyanobacteria and, consequently, the impact of this on the conservation of cultural heritage, as in the case study of the rock paintings of the Majella Massif (Lama dei Peligni—Abruzzo Region, central Italy). The region’s rock art, characterized by red and black schematic motifs, is increasingly impacted by microbial colonization, driven by climate-induced temperature variations. These impacts are consistent with broader research demonstrating the link between microbial growth patterns and climatic factors. Laboratory analyses were carried out on cyanobacteria samples collected near the rock paintings at the study site in the Majella National Park. Results revealed a significant increase in growth rates at the higher temperature, demonstrating their sensitivity to climatic shifts. These findings underscore the dynamic role of atmospheric factors in shaping microbial survival and propagation. Consequently, certain atmospheric parameters appear to play a crucial role in the deterioration of fragile cultural assets. Indeed, the enhanced growth of cyanobacteria due to rising temperatures also poses a challenge: their proliferation can degrade cultural heritage sites, threatening their preservation. This research advocates for interdisciplinary approaches that integrate atmospheric sciences, microbial ecology, and heritage studies to explore the role of temperature in affecting cyanobacteria growth and the conservation of a peculiar cultural heritage in the Majella Massif. By leveraging their biological traits, cyanobacteria can provide valuable insights into climate dynamics while emphasizing the urgency for proactive strategies to mitigate environmental impacts on vulnerable ecosystems and heritage sites. Full article

Many cyanobacteria synthesize cyanophycin, a nitrogen-rich amino acid polymer with metabolic engineering and biomanufacturing potential. In non-diazotrophic cyanobacteria, cyanophycin serves as a source of nitrogen under nitrogen stress conditions. However, the role of these storage granules in diazotrophic cyanobacteria, which fix nitrogen on demand, is yet to be understood. The enzyme cyanophycin synthetase, encoded by cphA, synthesizes cyanophycin from the amino acids aspartate and arginine. We probed the consequences of the inability to synthesize cyanophycin on the physiology of a nitrogen-fixing unicellular cyanobacterium, Cyanothece sp. ATCC 51142, by generating a markerless cphA deletion strain (∆cphA) using CRISPR/Cpf1. Under continuous high light and N₂-fixing conditions, the ∆cphA strain exhibited a growth defect and phycobilisome degradation, implying nitrogen starvation. Interestingly, under low light conditions, the nitrogen starvation phenotype was not observed. This suggests a critical role for the nitrogen storage bodies in maintaining an optimal cellular carbon/nitrogen balance, especially when the cellular nitrogen fixing machinery cannot match high levels of carbon fixation. Thus, when photosynthetic efficiency is high, the cyanophycin storage granules act as a readily available nitrogen source that ensures optimal metabolism and growth. This study illustrates the essential role of cyanophycin when engineering unicellular nitrogen-fixing cyanobacteria for use as production chassis. Full article

In this study, gut microorganisms of herbivorous grass carp, omnivorous carp, crucian carp, and aquatic microorganisms were collected from natural salt–alkali lakes and ponds in Xinjiang in winter to analyze their community structures. We sequenced 16S rRNA amplicons to investigate the composition and function of the microorganisms in the gut. PCoA analysis revealed that the gut microbiota of herbivorous and omnivorous fish formed two distinct clusters. Proteobacteria, Actinobacteria, Desulfobacterota, Firmicutes, and Chloroflexia are the dominant bacteria in the gut of fish. Proteobacteria, Bacteroidetes, Actinobacteria, Cyanobacteria, and Gram-negative bacteria are the dominant bacteria in the water. Carbohydrate- and protein-degrading bacteria, such as Desulfofustis, Lactiplantibacillus, and Vibrio, were predominant in omnivorous fish (CC and GRC), while cold-resistant bacteria, such as Shewanella and Psychromonas, were colonized in grass carp. This suggests that the same environment does not lead to similar gut bacteria, and that specific endogenous factors play a far more important role in shaping the microbiota composition than environmental factors. Full article