Search Results (383)

The precipitation of minerals, in particular carbonates, is a widespread phenomenon in all ecosystems, where it assumes a high relevance both from a geological and biogeochemical standpoint. Most carbonate rocks are of biological origin and made in an aquatic environment. In particular, bioprecipitation of carbonates is believed to have started in the Mesoproterozoic Era, thanks to a process often driven by photosynthetic microorganisms. Nevertheless, an important contribution to carbonate precipitation is also due to the metabolic activity of heterotrophic bacteria, which is not restricted to specific taxonomic groups or to specific environments, making this process a ubiquitous phenomenon. In this framework, the relationship between carbonatogenic microorganisms and other living organisms assumes a particular interest. This study aims to isolate and identify the culturable heterotrophic bacterial component associated with the coenosarc of Corallium rubrum in order to evaluate the occurrence of strains able to precipitate carbonates. In particular, the study was focused on the identification and characterisation of bacterial strains isolated from a coral coenosarc showing a high carbonatogenic capacity under laboratory conditions. Samples of C. rubrum were taken in the coastal waters of three Italian regions. The concentration of the aerobic heterotrophic microflora colonising C. rubrum coenosarc samples spanned from 3 to 6∙10⁶ CFU/cm². This variation in microbial populations colonising the C. rubrum coenosarc, spanning over 6 orders of magnitude, is not mirrored by a corresponding variability in the colony morphotypes recorded, with the mean being 5.1 (±2.1 sd). Among these bacteria, the carbonatogenic predominant species was Staphylococcus equorum (93% of the isolates), whereas Staphylococcus xylosus and Shewanella sp. accounted only for 3% of isolates each. All these strains showed a remarkable capacity of precipitating calcium carbonate, in the form of calcite crystals organised radially as well crystalised spherulites (S. equorum) or coalescing spherulites (Shewanella sp.). S. xylosus only produced amorphous precipitates of calcium carbonate. All bacterial strains identified were positive both for the production of urease and carbon anhydrase in vitro at 30 °C. It seems that they potentially possess the major biochemical abilities conducive to Ca²⁺ precipitation, as they showed in vitro. In addition, all our carbonatogenic isolates were able to hydrolyse the phytic acid calcium salt and then were potentially able to induce precipitation of calcium phosphates also through such a mechanism. Full article

Background: The emergence and spread of antimicrobial-resistant bacteria (ARB) has become an urgent global concern as a silent pandemic. When taking measures to reduce the impact of antimicrobial resistance (AMR) on the environment, it is important to consider appropriate treatment of wastewater from medical facilities. Methods: In this study, a continuous-flow wastewater treatment system using ozone and ultraviolet light, which has excellent inactivation effects, was implemented in a hospital in an urban area of Japan. Results: The results showed that 99% (2 log₁₀) of Gram-negative rods and more than 99.99% (>99.99%) of ARB comprising ESBL-producing Enterobacterales were reduced by ozone treatment from the first day after treatment, and ultraviolet light-emitting diode (UV-LED) irradiation after ozone treatment; UV-LED irradiation after ozonation further inactivated the bacteria to below the detection limit. Inactivation effects were maintained throughout the treatment period in this study. Metagenomic analysis showed that the removal of these microorganisms at the DNA level tended to be gradual in ozone treatment; however, the treated water after ozone/UV-LED treatment showed a 2 log₁₀ (>99%) removal rate at the end of the treatment. The residual antimicrobials in the effluent were benzylpenicillin, cefpodoxime, ciprofloxacin, levofloxacin, azithromycin, clarithromycin, doxycycline, minocycline, and vancomycin, which were removed by ozone treatment on day 1. In contrast, the removal of ampicillin and cefdinir ranged from 19% to 64% even when combined with UV-LED treatment. Conclusions: Our findings will help to reduce the discharge of ARB and antimicrobials into rivers and maintain the safety of aquatic environments. Full article

A simple and rapid precipitation process was successfully employed to prepare silver phosphate (SP, Ag₃PO₄). Two different phosphate sources: diammonium hydrogen phosphate ((NH₄)₂HPO₄) and dipotassium hydrogen phosphate (K₂HPO₄) were applied separately as the precursor, obtaining ((NH₄)₂HPO₄)⁻ and K₂HPO₄⁻ derived SP powders, named SP-A or SP-P, respectively. Fourier transform infrared (FTIR) spectra pointed out the vibrational characteristics of P–O and O–P–O interactions, confirming the presence of the PO43– functional group for SP. X-ray diffraction (XRD) patterns revealed that the SP crystallized in a cubic crystal structure. Whereas the field emission scanning electron microscope (FESEM) exposed spherical SP particles. The potentially antibacterial activity of SP-A and SP-P against bacterial Bacillus stratosphericus, yeast Meyerozyma guilliermondii, and fungal Phanerodontia chrysosporium was subsequently investigated. All studied microorganisms were recovered and isolated from the aquatic plant during the tissue culture process. The preliminary result of the antimicrobial test revealed that SP-A has higher antimicrobial activity than SP-P. The superior antimicrobial efficiency of SP-A compared to SP-P may be attributed to its purity and crystallite size, which provide a higher surface area and more active sites. In addition, the presence of potassium-related impurities in SP-P could have negatively affected its antimicrobial performance. These findings suggest that SP holds potential as an antimicrobial agent for maintaining sterility in tissue cultures, particularly in aquatic plant systems. The growth of both B. stratosphericus and M. guilliermondii was suppressed effectively at 30 ppm SP-A, whereas 10 ppm of SP-A can suppress P. chrysosporium development. This present work also highlights the potential of SP at very low concentrations (10–30 ppm) for utilization as an effective antimicrobial agent in tissue culture, compared to a commercial antimicrobial agent, viz., acetic acid, at the same concentration. Full article

Water environments and sediments are important reservoirs for antibiotic resistance genes (ARGs). Under the pressure of antibiotics, ARGs can transform between microorganisms. Lanthanum-modified bentonite (LMB) is a phosphorus passivation material with good prospects in water environment restoration. After a treatment with LMB, the phosphorus forms in water and sediments will change, which may have an impact on microorganisms and the transmission of ARGs. To investigate the effects of LMB and antibiotics on ARGs and bacterial communities in sediment and aquatic environments, LMB and tetracycline (Tet) were added individually and in combination to mixed samples of sediment and water. The results showed that the addition of either LMB or Tet increased the abundance of intI1 and tetA genes in both the sediment and water, with the Tet addition increasing ARGs to more than 1.5 times the abundance in the control group. However, when LMB and Tet were present simultaneously, the abundance of ARGs showed no significant difference compared to the control group. Tet and LMB also affected the bacterial community structure and function in the samples and had different effects on the sediment and water. A correlation analysis revealed that the potential host bacteria of the intI1 and tetA genes were unclassified_Geobacteraceae, Geothrix, Flavobacterium, Anaeromyxobacter, and Geothermobacter. These findings indicate that Tet or LMB may increase the dissemination of ARGs by affecting microbial communities, while LMB may reduce the impact of Tet through adsorption, providing a reference for the safety of the LMB application in the environment and its other effects (alleviating antibiotic pollution) in addition to phosphorus removal. Full article

Aquatic fungi serve as core ecological engines in freshwater ecosystems, driving organic matter decomposition and energy flow to sustain environmental balance. Wetlands, with their distinct hydrological dynamics and nutrient-rich matrices, serve as critical habitats for these microorganisms. As an internationally designated Ramsar Site, Yunnan Dashanbao Black-Necked Crane National Nature Reserve in China not only sustains endangered black-necked cranes but also harbors a cryptic reservoir of aquatic fungi within its peat marshes and alpine lakes. This study employed high-throughput sequencing to characterize fungal diversity and community structure across 12 understudied wetland sites in the reserve, while analyzing key environmental parameters (dissolved oxygen, pH, total nitrogen, and total phosphorus). A total of 5829 fungal operational taxonomic units (OTUs) spanning 649 genera and 15 phyla were identified, with Tausonia (4.17%) and Cladosporium (1.89%) as dominant genera. Environmental correlations revealed 19 genera significantly linked to abiotic factors. FUNGuild functional profiling highlighted saprotrophs (organic decomposers) and pathogens as predominant trophic guilds. Saprotrophs exhibited strong associations with pH, total nitrogen, and phosphorus, whereas pathogens correlated primarily with pH. These findings unveil the hidden diversity and ecological roles of aquatic fungi in alpine wetlands, emphasizing their sensitivity to environmental gradients. By establishing baseline data on fungal community dynamics, this work advances the understanding of wetland microbial ecology and informs conservation strategies for Ramsar sites. Full article

Aquatic resistomes are important reservoirs of antibiotic resistance genes (ARGs) and their precursors, which can proliferate and dissipate in pathogenic microorganisms that affect humans and animals, especially due to anthropogenic pressures such as the intensive use of antibiotics in aquaculture, often without effective regulation. This review addresses the mechanisms of horizontal gene transfer (HGT) in the dissemination of ARGs through mobile genetic elements (MGEs). In freshwater, genera such as Aeromonas, Pseudomonas and Microcystis stand out as vectors of ARGs. In the context of One Health, it is essential to implement sound public policies and strict regulations on the use of antibiotics in aquaculture, and the use of monitoring tools such as environmental DNA (eDNA) and metagenomics allows for the early detection of ARGs, contributing to the protection of human, animal and environmental health. Full article

Changes in the aquatic ecological environment have a significant impact on aquaculture efficiency. In order to understand the changes in water quality and the dynamics of microalgae and bacteria in the process of aquaculture, 16S rRNA and 18S rRNA high-throughput sequencing technologies were used to determine the microorganisms in a red tilapia (Oreochromis sp.) aquaculture pond. During the breeding period (from 6 July 2023 to 13 November 2023), water samples were collected from three ponds, on average once every 20 days. The results of water quality analysis showed that at the end of culture (13 November 2023), the concentrations of NH₄⁺-N and NO₂⁻-N increased significantly, and both the air temperature (36.00 ± 0.00 to 21 ± 0.00 °C) and water temperature (32.83 ± 0.29 to 22.75 ± 0.42 °C) decreased significantly. The NH₄⁺-N and NO₂⁻-N concentrations increased by 597% (0.67 ± 0.17 to 4.67 ± 0.33 mg/L) and 782% (0.34 ± 0.16 to 3.00 ± 1.15 mg/L), respectively, from T1 to T6. Bacterial diversity decreased to T3 and then increased. The relative abundance of hgcI_clade (from 14.91% to 7.18%) and CL500-29_marine_group (from 3.35% to 1.39%) in aquaculture water generally decreased with the extension of aquaculture time. The abundance of Komma increased from T1 (1.44%) to T3 (13.90%) and decreased from T3 to T6 (4.21%). The pH, dissolved oxygen concentration, and temperature were main factors affecting the dynamics of bacteria, while dissolved oxygen, NH₄⁺-N, and NO₂⁻-N concentrations affected that of microalgae. In conclusion, this study revealed regime shift in the water quality and microalgal–bacterial community with increasing culture time in red tilapia aquaculture ponds. Full article

Microplastics (MP) have recently become an emerging problem with the advent of bountiful and widespread pollutants in the aquatic environment. Owing to their large surface areas, microplastics act as an effective carrier of heavy metals and tend to form complex contamination. This combined pollution created by them poses a new threat to the world. This review summarizes the effects of microplastics and heavy metals on the aquatic fauna, along with their combined adverse effects and potential threats to human health. Furthermore, the adsorption kinetics adopted by microplastics to adsorb the heavy metal is also explained and some future research directions in this field are suggested. Full article

Permian shale gas, a resource-rich energy source, has garnered significant attention in recent years regarding its organic matter enrichment characteristics. This study conducted detailed observations via scanning electron microscopy (SEM) and optical microscopy to clarify the differences in the types and assemblages of hydrocarbon-generating organisms across Permian shale formations in Northwestern Sichuan, as well as to determine the characteristics of organic matter sources. The types and combinations of hydrocarbon-generating organisms in the Gufeng Formation, Wujiaping Formation, and Dalong Formation in Northwestern Sichuan are systematically summarized. Based on this information, the primary sources of organic matter in the Permian shale were analyzed. Hydrocarbon-generating organisms in the Permian shales of the study area are predominantly acritarchs (a type of planktonic algae), followed by higher plants and green algae. In the Gufeng Formation, acritarchs constituted the vast majority of hydrocarbon-generating organisms, with smaller amounts of higher plants and green algae. At the bottom of the Wujiaping Formation, the relative acritarch content decreases significantly, while that of higher plants substantially increases. In the Dalong Formation, acritarchs regain dominance, and higher plants decline, resembling the Gufeng Formation in microorganism composition. The relative content of green algae shows minimal variation across all layers. Overall, the organic matter sources of Permian shale in the study area were mainly acritarchs (derived from planktonic algae), followed by green algae, and terrestrial higher plants. During the Gufeng Formation period, the sea level was relatively high. The Kaijiang–Liangping Trough in Northwestern Sichuan was generally a siliceous deep shelf. The main source of organic matter was aquatic planktonic algae, containing a small amount of terrigenous input. At the bottom of the Wujiaping Formation, the sea level was relatively low, resulting in the overall coastal marsh environment of the Kaijiang–Liangping Trough, which was characterized by mixed organic matter sources, due to an increase in terrigenous organic matter content. The sedimentary environment and organic matter sources of the Dalong Formation were similar to those of the Gufeng Formation. This research can provide a theoretical basis for exploration and development of Permian shale gas. Full article

As emerging contaminants increasingly detected in aquatic and terrestrial ecosystems, environmental estrogens (EEs) pose significant ecological risks to marine ecosystems, particularly affecting photosynthetic microorganisms occupying fundamental roles in marine food webs. This review summarizes the current knowledge on the toxicological effects of EEs in marine microalgae through a systematic analysis of dose-dependent physiological, biochemical, and molecular responses. Experimental evidence reveals a biphasic response pattern characterized by growth promotion and photosynthetic enhancement in microalgae under low-concentration EE exposure (0.1–10 μg/L), while marked inhibition of both growth and photosynthetic activity was observed at elevated EE concentrations (>50 μg/L). Notably, sustained EE exposure induces metabolic reprogramming, manifested through reduced protein and polysaccharide biosynthesis concurrent with accelerated lipid accumulation. Cellular stress responses include significant ultrastructural alterations such as chloroplast membrane disruption, cell wall thickening, and the formation of multicellular aggregates. The study further elucidates the concentration-dependent modulation of toxin metabolism, with sublethal doses stimulating intracellular microcystin synthesis (1.5–2.3-fold increase), while acute exposure triggers toxin release through membrane permeabilization. At molecular levels, transcriptomic analyses identify the up-regulation of heat shock proteins (HSP70/90) and the differential expression of genes governing cell cycle progression (cyclin-D), apoptotic pathways (caspase-3), photosynthetic electron transport (psbA), and oxidative stress responses (SOD, CAT). These findings demonstrate that EEs exert multilevel impacts on microalgal physiology through interference with fundamental metabolic processes, potentially disrupting marine primary productivity and biogeochemical cycles. The identified response mechanisms provide critical insights for environmental risk assessment and establish a conceptual framework for investigating estrogenic pollutant effects in aquatic ecosystems. Full article

Human development has led to increased production of oil and gas, mainly as energy sources, which, however, are responsible for contamination and metal corrosion in industrial, marine, and terrestrial environments. Lubricating oil, in particular, is widely used in generators and industrial machines in the electric sector and is responsible for contamination not only in industrial environments but also in many terrestrial and aquatic ecosystems. In this context, this study aimed to apply the Starmerella bombicola ATCC 222214 biosurfactant to inhibit metal corrosion in seawater and in an Accelerated Corrosion Chamber (ACC). For this purpose, its toxicity against the microcrustacean Artemia salina, its dispersion capacity, and its ability to promote oil biodegradation in a saline environment were investigated. The biosurfactant, when applied at twice its Critical Micellar Concentration (CMC), caused low mortality (30.0%) of microcrustaceans in a saline environment, and, in its crude form, the biosurfactant ensured the dispersion of no less than 77.56% of residual engine oil in seawater. Oil biodegradation by autochthonous microorganisms reached 94.39% in the presence of the biosurfactant in seawater. Furthermore, the biosurfactant, when used at twice its CMC, acted satisfactorily as a corrosion inhibitor by reducing the mass loss of galvanized iron specimens (plates) in seawater in a static system to only 0.36%. On the other hand, when the biosurfactant was added at the CMC as an atmospheric corrosion inhibitor, the reduction in mass loss of carbon steel plates treated in the ACC was 17.38% compared to the control containing only a biodegradable matrix based on vegetable resin. When the biosurfactant was incorporated into different paints applied to galvanized iron plates placed in contact with the salt spray produced in the ACC, the best result was obtained using the biomolecule at a concentration of 3% in the satin paint, ensuring a plate mass loss (29.236 g/m²) that was almost half that obtained without surfactant (52.967 g/m²). The study indicated the use of yeast biosurfactant as a sustainable alternative in combating the contamination of marine environments and metal corrosion, with the aim of preserving the environment and improving the quality of life in aquatic and terrestrial ecosystems. Full article

The rapid expansion of the global population has intensified the demand for protein-rich food sources, positioning aquaculture as a crucial sector in the endeavor to alleviate global hunger through the provision of high-quality aquatic protein. Traditional protein sources such as fishmeal have historically served as the foundation of aquafeeds; however, their elevated costs and limited availability have catalyzed the search for sustainable alternatives. These alternatives encompass plant-based proteins, insect meals, and, more recently, single-cell proteins (SCPs), which are derived from microorganisms including bacteria, yeast, fungi, and microalgae. Nonetheless, SCP remains in its nascent stages and currently accounts for only a minor fraction of aquafeed formulations relative to other established alternatives. The production of SCP utilizes low-cost substrates, such as agricultural and dairy wastes, thereby supporting waste mitigation and principles of the circular economy. This review elucidates the nutritional value of SCPs, their potential for biofortification, and their emerging roles as functional feeds with immunomodulatory and nutrigenomic effects. Additionally, the review underscores the potential of endophytes as a novel SCP source, highlighting their underutilized capacity to foster sustainable innovations in aquafeeds. Full article

Cyanobacteria are gram-negative prokaryotic microorganisms composed of both broad morphological and phylogenetic diversity inherited from diverse ecosystems like aquatic, terrestrial, or extremophilic environments. In this study, three cyanobacteria strains from the Blue Biotechnology and Ecotoxicology Culture Collection (LEGE-CC) were obtained from different environments in Portugal. Polyphasic analysis was applied for taxonomic identification. The proximate composition analysis indicated the lipid content (6.2% to 9.1% dry weight (DW)), protein content (28.2% to 62.9% DW), and carbohydrate content (19.5% to 46.1% DW). The fatty acid (FA) profiles of the strains revealed the presence of 19 different FAs, with FA 16:0 found in the highest abundance. The lipidomic analysis revealed 230 lipid species, with Laspinema sp. LEGE 06078 displaying the highest diversity (125 lipid species). These included species-specific and common lipids species that denote biochemical uniqueness that are also carriers of omega-3 FA (n−3). Biological assays exhibited strong antioxidant activity against ABTS^•+ and DPPH^• in Laspinema sp. LEGE 06078, while Sphaerospermopsis sp. LEGE 00249 was renowned for reducing lipids in zebrafish larvae. The findings are of immense significance on the lipidomics diversity of cyanobacteria in terms of nutrition, health, and biotechnology, such as addressing obesity and sustainable resource production. Full article

Microecological preparations (MPs), encompassing probiotics, prebiotics, synbiotics, and postbiotics, are microbial feed supplements that enhance host health through gut microbiota modulation. Unlike the narrow definition of probiotics (viable microorganisms), MPs constitute a broader category including non-viable microbial derivatives and selectively fermented substrates. Their application in aquaculture significantly reduces antibiotic dependence. Given the industry’s intensification challenges, while meeting global protein demands, high-density aquaculture elevates disease risks, driving prophylactic antibiotic overuse. This practice accelerates antimicrobial resistance (AMR) development, compromising treatment efficacy and causing residual antibiotics in aquatic products. Such residues violate international food safety standards, triggering trade disputes. As sustainable alternatives, MPs operate through multiple mechanisms: the competitive exclusion of pathogens, immune stimulation, and nutrient absorption enhancement. This review examines the patterns of antibiotic abuse and the emergence of AMR in carp aquaculture, evaluates MP-based mitigation strategies from the perspective of antibiotic alternatives, and analyzes the advantages, disadvantages, and application progress of MPs. Based on existing evidence, we propose targeted research priorities for MP optimization, advocating for scientifically guided implementation in commercial cyprinid aquaculture. Full article

To enhance the resistance of stainless steel (SS) against biofouling and biocorrosion, hyperbranched poly(viologen) brushes were covalently immobilized onto SS substrates. This study systematically evaluated the efficacy of the functionalized SS substrates in inhibiting microorganism adhesion, biofouling and biocorrosion. Enhanced antifouling and antimicrobial properties were evidenced through assays involving the attachment of Amphora coffeaeformis, the settlement of Pseudomonas sp. bacteria and barnacle cyprids. Furthermore, the functionalized SS substrates demonstrated superior antifouling performance alongside excellent biocorrosion–inhibition properties. These findings suggest that the functionalized SS substrates, with their robust antimicrobial, antifouling and anticorrosion capabilities, hold significant potential for applications in aquatic environments Full article