Search Results (38)

Cyanobacterial blooms are increasingly becoming more intense and frequent, posing a public health threat globally. Drinking water treatment plants that rely on algal bloom-affected waters may create waste (water treatment residuals, WTRs) that concentrates contaminants. Source waters may contain harmful cyanobacteria, cyanophages (bacteriophages that infect cyanobacteria), and bacteria. Cyanophages are known to affect bloom formation and growth dynamics, so there is a need to understand viral-host dynamics between phage and bacteria in these ecosystems for managing cyanobacteria. This study isolated and characterized lytic cyanophages from WTRs of a HAB-affected lake in Ohio that infect toxic bloom-forming filamentous cyanobacteria Planktothrix agardhii. Phage infections in the Lake Erie cyanobacteria culture were examined visually and via microscopy and fluorometry. Whole genome sequencing and metagenomic analyses were also conducted. Observed changes in Planktothrix included sheared and shriveled filaments, reduced clumping, and buoyancy changes. Photosynthetic pigmentation was unexpectedly more apparent during phage infection. Metagenomic analyses identified nineteen phages and seven other co-existing bacterial genera. Annotated bacterial genomes contained metabolic pathways that may influence phage infection efficiency. Viral genomes were successfully tied to microbial hosts, and annotations identified important viral infection proteins. This study examines cyanobacterial-phage interactions that may have potential for bioremedial applications. Full article

Complex wastewater matrices hinder the efficacy of conventional treatment methods due to the presence of various inorganic and organic pollutants, along with their intricate interactions. Leveraging the synergy between algae and bacteria, algal–bacterial symbiosis (ABS) systems offering an evolutionary and highly effective approach. The ABS system demonstrates 10–30% higher removal efficiency than conventional biological/physicochemical methods under identical conditions, especially at low C/N ratios. Recent advances in biology techniques and big data analytics have deepened our understanding of the synergistic mechanisms involved. Despite the system’s considerable promise, challenges persist concerning complex pollution scenarios and scaling it for industrial applications, particularly regarding system design, environmental adaptability, and stable operation. In this review, we explore the current forms and operational modes of ABS systems, discussing relevant mechanisms in various wastewater treatment contexts. Furthermore, we examine the advantages and limitations of ABS systems in treating complex wastewater matrices, highlighting challenges and proposing future directions. Full article

The enrichment of organic matter in marine shale is a complex process involving tectonic–sedimentary interactions. The tectonic setting exerts critical control over sediment provenance, marine biota, and subaqueous environmental conditions in shale deposition. To unravel the mechanisms and differential controls of organic matter accumulation in marine shales across distinct tectonic regimes, this study systematically examines the Lower Cambrian Niutitang Formation and Lower Silurian Longmaxi Formation shales in the Upper Yangtze Block, SW China. Through comprehensive geochemical analyses encompassing total organic carbon (TOC) contents, as well as major and trace elements conducted on 31 shale samples from the Niutitang Formation and 30 samples from the Longmaxi Formation, we characterized their depositional environmental features and compared the distinctions between them. The results indicate that both the Cambrian Niutitang Formation and Silurian Longmaxi Formation shales exhibit high TOC contents, which range from 1.04% to 8.83% (average 4.73%) and from 0.29% to 6.14% (average 3.35%), respectively. Paleoenvironmental proxies demonstrate that the Cambrian Niutitang shales developed under suboxic–anoxic to even sulfidic conditions, with moderate water restriction and high paleoproductivity levels, while the Silurian Longmaxi Formation was deposited under suboxic–anoxic environments with strong water restriction and low-to-moderate paleoproductivity. Organic matter enrichment in the Cambrian Niutitang Formation followed a “productivity + preservation model”, whereas the Silurian Longmaxi Formation primarily adhered to a “preservation-dominated model”. The differentiation in organic enrichment mechanisms between these two marine sequences is attributed to the distinct tectonic settings during their deposition. During the Early Cambrian, the Upper Yangtze Block was in a rift trough tectonic setting influenced by upwelling currents, which triggered algal blooms and subsequent bacterial sulfate reduction (BSR) coupled with marine anoxia and sulfidation. In contrast, the Early Silurian period featured a semi-restricted marine basin with weaker upwelling activity, where organic matter enrichment was predominantly controlled by a restricted, reducing water column. Our findings demonstrate that tectonic settings exert fundamental controls on nutrient availability for algal communities and water column retention levels, serving as critical determinants for organic enrichment processes in marine shale systems. Full article

Phycosphere niches host rich, unique microbial consortia that harbor complex algae–bacteria interactions with fundamental significance in underpinning most functions of aquatic ecological processes. Therefore, harvesting the uncultured phycobacteria is crucial for understanding the intricate mechanisms governing these dynamic interactions. Here, we characterized and compared microbial community composition of the phycosphere microbiota from six harmful algal bloom-forming marine dinoflagellates, Alexandrium spp., and their bacterial associations. Furthermore, based on a combinational enhanced cultivation strategy (CECS) procedure for the selected isolation for cultivable phycobacteria, a new yellow-pigmented bioactive bacterium designated ABI-6-9 was successfully recovered from cultivable phycobacteria of the highly toxic A. minutum strain amtk4. An additional phylogenomic analysis fully identified this new isolate as a potential novel species of the genus Mameliella within the family Roseobacteraceae. The bioactivity evaluation observed that strain ABI-6-9 can significantly promote the cell growth of its algal host and altered the gonyautoxin accumulation profiles in the co-culture circumstance. Additionally, the bacterial production of active bioflocculanting exopolysaccharides (EPSs) by strain ABI-6-9 was also measured after culture optimization. Thus, these findings revealed the potential environmental and biotechnological implications of this new microalgae growth- promoting phycobacterium. Full article

Microorganisms play an essential role in the biogeochemical processes of macroalgal cultivation ecosystems by participating in a complex network of interactions, significantly influencing the growth and development of macroalgae. This study used bibliometric analysis and VOSviewer based on Web of Science data to provide an overview by tracing the developmental footprint of the technology. Countries, institutions, authors, keywords, and key phrases were tracked and mapped accordingly. From 1 January 2003 to 31 December 2023, 619 documents by 2516 authors from 716 institutions in 51 countries were analyzed. Keyword co-occurrence network analysis revealed five main areas of research on microbes in macroalgal cultivation ecosystems: (1) identification of microbial species and functional genes, (2) biogeochemical cycling of carbon in microbial communities, (3) microbial influences on macroalgae growth and development, (4) bioactivities, and (5) studies based on database. Thematic evolution and map research emphasized the centrality of microbial diversity research in this direction. Over time, the research hotspots and the core scientific questions of the microorganisms in the macroalgal cultivation ecosystems have evolved from single-organism interactions to the complex dynamics of microbial communities. The application of high-throughput techniques had become a hotspot, and the adoption of systems biology approaches had further facilitated the integrated analysis of microbial community composition and function. Our results provide valuable guidance and information for future researches on algal–bacterial interactions and microbe-driven carbon cycling in coastal ecosystems. Full article

For marine bacteria, the phycosphere is attractive as a major source of labile nutrients, but it also presents challenges due to the accumulation of stressors, such as reactive oxygen species (ROS) from algal metabolisms. Therefore, successful colonization of bacteria in the phycosphere requires an efficient mechanism to fight against oxidative stress, which is still a missing piece in studying bacteria–algae interactions. Here, we demonstrate that a common metabolite, indole acetic acid (IAA), enables the Roseobacter clade Sulfitobacter mediterraneus SC1-11, an IAA-producer, to resist hydrogen peroxide (H₂O₂) stress and that IAA biosynthesis can be activated by low concentrations of H₂O₂. Proteomics and metabolomics analyses revealed that bacteria consume high amino acid levels when exposed to H₂O₂ stress, while exogenous supplementation with IAA effectively protects bacteria from ROS damage and alleviates amino acid starvation by upregulating several proteins responsible for replication, recombination, and repair, as well as two proteins involved in amino acid transport and metabolism. Furthermore, the supplementation of some amino acids, such as arginine, also showed a significant protective effect on bacteria under H₂O₂ stress. This study highlights an unprecedented role of IAA in regulating amino acid metabolisms for resisting oxidative stress, which may be a specific strategy for adapting to the phycosphere. Full article

The French Society of Toxinology (SFET) held its 30th Annual Meeting (RT30) on 2–3 December 2024 at Hôtel Le Saint Paul in Nice, France, on the beautiful French Riviera. It was the first time that the event was organized outside of Paris. The meeting brought together 74 participants and focused on the main theme, “Unlocking the Deep Secrets of Toxins”, which delved into cutting-edge research in the field of animal venoms and toxins from animal, plant, fungal, algal, mold and bacterial sources. The event emphasized the dynamic and ever-evolving nature of toxins, often influenced by environmental factors, their interactions with molecular or cellular ligands, their mechanisms of action and their potential applications in therapy. These key topics were explored in depth during oral communications and poster sessions across three main thematic areas, each dedicated to a specific aspect of toxinology. A fourth, more general session provided an opportunity for participants to present recent work that fell outside the main themes but still contributed valuable insights to the broader field. This report presents the abstracts of seven of the invited lectures, fifteen of the selected lectures and sixteen of the posters, following the authors’ agreement to publish them. Additionally, the names of the “Best Oral Communication” and “Best Poster” awardees are highlighted, recognizing the outstanding contributions made by early-career researchers and their innovative work in toxinology. Full article

Surface modification of various polymer foils was achieved by UV activation and chemical grafting with cysteamine to improve surface properties and antimicrobial efficacy. UVC activation at 254 nm led to changes in surface wettability and charge density, which allowed the introduction of amino and thiol functional groups by cysteamine grafting. X-ray photoelectron spectroscopy (XPS) confirmed increased nitrogen and sulfur content on the modified surfaces. SEM analysis revealed that UV activation and cysteamine grafting resulted in distinct surface roughness and texturing, which are expected to enhance microbial interactions. Antimicrobial tests showed increased resistance to algal growth (inhibition test) and bacterial colonization (drop plate method), with significant improvement observed for polyethylene terephthalate (PET) and polyetheretherketone (PEEK) foils. The important factors influencing the efficacy included UV exposure time and cysteamine concentration, with longer exposure and higher concentrations leading to bacterial reduction of up to 45.7% for Escherichia coli and 55.6% for Staphylococcus epidermidis. These findings highlight the potential of combining UV activation and cysteamine grafting as an effective method for developing polymeric materials with enhanced antimicrobial function, offering applications in industries such as healthcare and packaging. Full article

Climate change and nutrient enrichment are increasing the frequency of algal blooms, with sometimes significant impacts on coastal ecosystems. Haslea ostrearia blooms have been documented in oyster ponds and are not harmful, yet their effects in open environments remain underexplored. Marennine, a blue pigment produced by H. ostrearia, can display a range of biological properties in laboratory conditions, including antibacterial and allelopathic properties. Other blue Haslea species, forming blooms, synthesize bioactive marennine-like pigments. This study aims to understand if and how these blooms could affect the underlying community of microorganisms living in the biofilms. Morphological and molecular techniques were used to assess community dynamics during bloom events. Our findings indicate that blue Haslea blooms do not significantly alter the diatom or bacterial populations. However, they are paired with enhanced alpha diversity in the microbial communities. These observations suggest a complex interaction between bloom events and microbial dynamics. Additionally, this study expands our understanding of the bioactive properties of marennine-like pigments and their ecological roles, suggesting new avenues for biotechnological applications. This work underscores the importance of further research into the environmental and biological implications of blue Haslea blooms. Full article

We investigated the impacts of spherical and triangular-plate-shaped lipid-coated silver nanoparticles (AgNPs) designed to prevent surface oxidation and silver ion (Ag⁺) dissolution in a small-scale microcosm to examine the role of shape and surface functionalization on biological interactions. Exposures were conducted in microcosms consisting of algae, bacteria, crustaceans, and fish embryos. Each microcosm was exposed to one of five surface chemistries within each shape profile (at 0, 0.1, or 0.5 mg Ag/L) to investigate the role of shape and surface composition on organismal uptake and toxicity. The hybrid lipid-coated AgNPs did not result in any significant release of Ag⁺ and had the most significant toxicity to D. magna, the most sensitive species, although the bacterial population growth rate was reduced in all exposures. Despite AgNPs resulting in increasing algal growth over the experiment, we found no correlation between algal growth and the survival of D. magna, suggesting that the impacts of the AgNPs on bacterial survival influenced algal growth rates. No significant impacts on zebrafish embryos were noted in any exposure. Our results demonstrate that the size, shape, and surface chemistry of AgNPs can be engineered to achieve specific goals while mitigating nanoparticle risks. Full article

Algae and bacteria have co-occurred and coevolved in common habitats for hundreds of millions of years, fostering specific associations and interactions such as mutualism or antagonism. These interactions are shaped through exchanges of primary and secondary metabolites provided by one of the partners. Metabolites, such as N-sources or vitamins, can be beneficial to the partner and they may be assimilated through chemotaxis towards the partner producing these metabolites. Other metabolites, especially many natural products synthesized by bacteria, can act as toxins and damage or kill the partner. For instance, the green microalga Chlamydomonas reinhardtii establishes a mutualistic partnership with a Methylobacterium, in stark contrast to its antagonistic relationship with the toxin producing Pseudomonas protegens. In other cases, as with a coccolithophore haptophyte alga and a Phaeobacter bacterium, the same alga and bacterium can even be subject to both processes, depending on the secreted bacterial and algal metabolites. Some bacteria also influence algal morphology by producing specific metabolites and micronutrients, as is observed in some macroalgae. This review focuses on algal-bacterial interactions with micro- and macroalgal models from marine, freshwater, and terrestrial environments and summarizes the advances in the field. It also highlights the effects of temperature on these interactions as it is presently known. Full article

Currently, the water ecological environment is severely polluted and traditional bioreactors have issues with high energy consumption and greenhouse gas emissions. However, a promising solution is the bacterial–algal reactor, which is a green bioreactor that can simultaneously treat sewage and fix CO₂. The main configurations of bacterial–algal reactors, including several types, activated sludge, biofilm, batch biofilm–sludge reactor coupled with activated sludge method, and bacterial–algal open reactor, have been reviewed. The performance of these reactors in reducing pollutants and carbon emissions during wastewater treatment has been investigated. Additionally, the technical advantages of coupling a bacterial–algal symbiosis system with a conventional bioreactor have been analyzed. The interaction mechanism of the bacterial–algal system in various reactors has also been elaborated. The bacterial–algal reactor improves pollutant removal efficiency through assimilation and absorption of pollutants by microalgae, and reduces aeration by releasing oxygen through photosynthesis of microalgae. Finally, the existing problems in the practical application of bacterial–algal reactors have been summarized, and future research directions have been suggested, providing theoretical support for the future application of bacterial–algal reactors and directions for optimal design and development of bacterial–algal symbiotic reactors. Full article

Zwitterionic polymer coatings facilitate the formation of hydration layers via electrostatic interactions on their surfaces and have demonstrated efficacy in preventing biofouling. They have emerged as a promising class of marine antifouling materials. However, designing multifunctional, environmentally friendly, and natural products-derived zwitterionic polymer coatings that simultaneously resist biofouling, inhibit protein adhesion, exhibit strong antibacterial properties, and reduce algal adhesion is a significant challenge. This study employed two diisocyanates as crosslinkers and natural urushiol and ethanolamine as raw materials. The coupling reaction of diisocyanates with hydroxyl groups was employed to synthesize urushiol-based precursors. Subsequently, sulfobetaine moieties were introduced into the urushiol-based precursors, developing two environmentally friendly and high-performance zwitterionic-functionalized polyurushiol antifouling coatings, denoted as HUDM-SB and IPUDM-SB. The sulfobetaine-functionalized polyurushiol coating exhibited significantly enhanced hydrophilicity, with the static water contact angle reduced to less than 60°, and demonstrated excellent resistance to protein adhesion. IPUDM-SB exhibited antibacterial efficacy up to 99.9% against common Gram-negative bacteria (E. coli and V. alginolyticus) and Gram-positive bacteria (S. aureus and Bacillus. sp.). HUDM-SB achieved antibacterial efficacy exceeding 95.0% against four bacterial species. Furthermore, the sulfobetaine moieties on the surfaces of the IPUDM-SB and HUDM-SB coatings effectively inhibited the growth and reproduction of algal cells by preventing microalgae adhesion. This zwitterionic-functionalized polyurushiol coating does not contain antifouling agents, making it a green, environmentally friendly, and high-performance biomaterial-based solution for marine antifouling. Full article

Several species of microalgae can convert light energy into molecular hydrogen (H₂) by employing enzymes of early phylogenetic origin, [FeFe]-hydrogenases, coupled to the photosynthetic electron transport chain. Bacterial [FeFe]-hydrogenases consist of a conserved domain that harbors the active site cofactor, the H-domain, and an additional domain that binds electron-conducting FeS clusters, the F-domain. In contrast, most algal hydrogenases characterized so far have a structurally reduced, so-termed M1-type architecture, which consists only of the H-domain that interacts directly with photosynthetic ferredoxin PetF as an electron donor. To date, only a few algal species are known to contain bacterial-type [FeFe]-hydrogenases, and no M1-type enzymes have been identified in these species. Here, we show that the chlorophycean alga Uronema belkae possesses both bacterial-type and algal-type [FeFe]-hydrogenases. Both hydrogenase genes are transcribed, and the cells produce H₂ under hypoxic conditions. The biochemical analyses show that the two enzymes show features typical for each of the two [FeFe]-hydrogenase types. Most notable in the physiological context is that the bacterial-type hydrogenase does not interact with PetF proteins, suggesting that the two enzymes are integrated differently into the alga’s metabolism. Full article

The utilization of nanoparticles derived from algae has generated increasing attention owing to their environmentally sustainable characteristics and their capacity to interact harmoniously with biologically active metabolites. The present study utilized P. boergesenii for the purpose of synthesizing copper oxide nanoparticles (CuONPs), which were subsequently subjected to in vitro assessment against various bacterial pathogens and cancer cells A375. The biosynthesized CuONPs were subjected to various analytical techniques including FTIR, XRD, HRSEM, TEM, and Zeta sizer analyses in order to characterize their stability and assess their size distribution. The utilization of Fourier Transform Infrared (FTIR) analysis has provided confirmation that the algal metabolites serve to stabilize the CuONPs and function as capping agents. The X-ray diffraction (XRD) analysis revealed a distinct peak associated with the (103) plane, characterized by its sharpness and high intensity, indicating its crystalline properties. The size of the CuONPs in the tetragonal crystalline structure was measured to be 76 nm, and they exhibited a negative zeta potential. The biological assay demonstrated that the CuONPs exhibited significant antibacterial activity when tested against both Bacillus subtilis and Escherichia coli. The cytotoxic effects of CuONPs and cisplatin, when tested at a concentration of 100 µg/mL on the A375 malignant melanoma cell line, were approximately 70% and 95%, respectively. The CuONPs that were synthesized demonstrated significant potential in terms of their antibacterial properties and their ability to inhibit the growth of malignant melanoma cells. Full article