Search Results (188)

Microalage are broadly recognized as promising agents for sustainable wastewater treatment and biomass generation. However, industrial effluents such as petroleum refinery wastewater (WW) present challenges due to toxic growth inhibiting substances. Three marine microalgae species: Pseudochloris wilhelmii, Nannochloropsis gaditana and Synechococcus sp. MK568070 were examined for cultivation potential in oil refinery WW. Their performance was evaluated in terms of growth dynamics, lipid productivity, and toxicity reduction, with a focus on their suitability for largescale industrial use. N. gaditana demonstrated the highest growth rate and lipid content (37% d.w.) as well as lipid productivity (29.45 mg/(Lday)) with the N-uptake rate of 0.698 mmol/(gday). The highest specific DIN uptake rate was observed inn P. wilhelmii (0.895 mmol/(gday) along with the highest volumetric productivity (93.9 mg/L/day) and WW toxicity removal (76.5%), while Synechococcus sp. MK568070 demonstrated lower performance metrics. A simple numerical model was applied to calculate continuous operation based on empirical results of batch experiments. Sustainability of the microalgae-based WW remediation under the conditions of optimized lipid biomass production was estimated, regarding 2019–2022–2025 cost dynamics. Parameters for optimum open raceway pond cultivation were calculated, and the biomass production accumulation was estimated, with the highest biomass production noted in P. wilhelmii (171.38 t/year). Comparison of treatment costs, production costs and revenue showed that the best candidate for WW remediation is N. gaditana. Full article

This study investigates the efficient and enantioselective hydrolysis of ester bonds through a series of biotransformations employing various photobiocatalysts. A racemic mixture of 1-phenylethyl acetate served as the model substrate. The described research identified three strains exhibiting the highest biocatalytic activity: Nostoc cf-muscorum (CCALA 129), Leptolyngbya foveolarum (CCALA 76), and Synechococcus bigranulatus (CCALA 187). Their application led to the complete hydrolysis of the starting reagent, yielding both the unreacted ester and its corresponding alcohol in an enantioselective manner. Notably, the selectivity, expressed as S, reached an impressive value of 283 in certain outcomes. The photobiotransformations were conducted under varying conditions, with particular focus on two essential parameters: the duration of the process, crucial for kinetically controlled reactions, and light exposure, critical for light-dependent organisms. The representative results highlight the efficacy of these biocatalysts. For instance, using Leptolyngbya foveolarum (CCALA 76), Nostoc cf-muscorum (CCALA 129), and Synechococcus bigranulatus (CCALA 187) facilitated the production of 1-(R)-phenylethanol with enantiomeric excesses (ee) of 89%, 88%, and 86%, respectively, at a conversion degree of approximately 50%. These processes also yielded an optically enriched mixture of the unreacted substrate, 1-(S)-phenylethyl acetate. Specifically, in the case of Leptolyngbya foveolarum (CCALA 76), the ee of the unreacted ester reached up to 98%. Light exposure emerged as a key factor influencing selectivity factor (S). Adjusting this parameter allowed us to achieve an E value of up to 283 for the formation of 1-(R)-phenylethanol with an ee > 99% when utilizing the Nostoc cf-muscorum (CCALA 129) strain. Furthermore, light intensity proved crucial for scaling up these processes. Significant results were obtained with Synechococcus bigranulatus, particularly at substrate concentrations ranging from 1 to 10 mM under limited exposure. Here, the conversion degree was 55%, the ee of the (R)-alcohol was 86%, and the selectivity factor (S) value was 21. Full article

Concrete production contributes nearly 8% of the global CO₂ emissions, making carbon capture in construction materials a critical environmental priority. While microbial self-healing concrete has shown promise in repairing structural cracks, its potential to serve as a carbon-negative material through atmospheric CO₂ sequestration remains underutilized. This interdisciplinary review—designed for materials scientists, civil engineers, and environmental technologists—systematically evaluates bacterial candidates for their application in self-healing, carbon-capturing concrete. Bacteria are ranked according to their efficiency in capturing CO₂ through both direct mechanisms (e.g., photosynthetic fixation by cyanobacteria) and indirect pathways (e.g., ureolysis-driven calcium carbonate precipitation). The assessment also considers microbial survivability in high-alkalinity concrete environments, the effectiveness of encapsulation strategies in enhancing bacterial viability and function over time, and sustainability metrics such as those derived from life cycle assessment (LCA) analyses. The findings highlight Bacillus sphaericus and Sporosarcina pasteurii as high-performing species in terms of rapid mineralization and durability, while encapsulation significantly improves the long-term viability for species like Paenibacillus mucilaginosus and Synechococcus. Notably, Bacillus sphaericus and Sporosarcina pasteurii exhibit carbonate precipitation rates of 75–100 mg CaCO₃/g biomass and enable crack closure of up to 0.97 mm within 8 weeks. The proposed bacterial ranking framework, paired with performance data and environmental modeling, provides a foundation for the advancement of scalable, carbon-negative concrete solutions. Full article

An oceanographic cruise with 34 stations was conducted in the central-southwestern region of the Gulf of Mexico from February 19 to 10 March 2013. This study included the measurement of hydrographic and phytoplankton bio-optical parameters, and pigment samples were collected at two depth levels (10 and 50 m). Our results showed a warm and nutrient-depleted water column associated with low chlorophyll a (<1 mg Chla m⁻³) and average values of a_ph440 (0.01 ± 0.008, m⁻¹) and a_d350 (0.04 ± 0.02, m⁻¹). In addition, nano-microphytoplankton abundance and pigments were analyzed using a light microscope and HPLC, respectively. Overall, the Gulf of Mexico exhibited oligotrophic characteristics, with Chla (0.17 ± 0.11 mg m⁻³) and NO₃⁻ (0.03 ± 0.001 µM), except at 50 m depth in some stations north of Yucatán and in Campeche Bay and at surface level off the Tamaulipas shelf. In these three regions, values of a_ph(440), a_d(350), (Chla) and phytoplankton abundance (>12 × 10³ cells L⁻¹) were observed near river mouths and under seasonal oceanographic forcings, which increased the growth and diversity of phytoplankton. The most relevant pigments found were DVchla (0.06 ± 0.13 mg m⁻³), Chlb (0.16 ± 0.21 mg m⁻³), Zea (0.06 ± 0.03 mg m⁻³), and Hex-fuco (0.02 ± 0.02 mg m⁻³); these are associated with the presence of Prochlorococcus, chlorophytes, Synechococcus, prymnesiophytes, and diatoms. Through the bio-optical variability, we determined the ecological geography of phytoplankton in four different spectral shapes, where M1 and M2 represent the group of cyanobacteria (Prochlorococcus and Synechococcus) and M3 and M4 represent a mixture of diatoms, dinoflagellates, and chlorophytes. In conclusion, we consider that oceanographic processes such as cyclonic and anticyclonic structures and permanent rivers determine the favorable changes in phytoplankton (>nutrients, Chla, a_ph440) and an increment in the number of phytoplankton spectral shapes). Full article

Seagrass meadows are recognized for their ecological importance, yet their influence on microbial community structure remains insufficiently characterized. This study examined the effects of seagrass presence on microbial assemblages in a subtropical coastal environment by comparing seagrass habitats to adjacent unvegetated sediments. Microbial abundances, including viruses, bacteria, picophytoplankton (Synechococcus spp. and picoeukaryotes), and heterotrophic nanoflagellates, were quantified using flow cytometry. Viral concentrations were significantly higher in seagrass treatments (2.4–9.2 × 10⁶ viruses mL⁻¹) than in controls (0.6–2.0 × 10⁶ viruses mL⁻¹), while bacterial abundances were slightly lower in seagrass treatments (5.1–16.0 × 10⁵ cells mL⁻¹) than in controls (7.9–16.6 × 10⁵ cells mL⁻¹). As a result, the virus-to-bacteria ratio (VBR) was significantly elevated in seagrass habitats, suggesting enhanced viral regulation of bacterial populations. Additionally, picophytoplankton and heterotrophic nanoflagellates increased in seagrass incubations, with strong correlations indicating that nanoflagellates are likely major grazers of picophytoplankton. These results highlight the role of seagrass habitats in modulating microbial interactions and emphasize the need to consider habitat-specific characteristics when evaluating microbial dynamics and biogeochemical processes in coastal systems. Full article

Effective wastewater management is critical for mitigating environmental and health impacts in ecologically sensitive regions like the Peruvian Amazon, where rapid urbanization has led to increased discharge of nutrient-rich effluents into freshwater systems. Conventional treatment methods often fail to address nutrient imbalances while generating secondary pollutants. This study aims to evaluate the bioremediation potential of a non-axenic cyanobacterium, Synechococcus sp., isolated from the Amazon Basin, for municipal wastewater treatment within a circular bioeconomy framework. The strain was cultivated in different concentrations of municipal wastewater (25%, 50%, 75%, 100%) from Moronacocha Lake in the Peruvian Amazon to assess growth kinetics, ammonium removal efficiency, and biochemical composition. The cyanobacterium exhibited optimal performance in 25% wastewater, achieving the highest specific growth rate (22.8 × 10⁻² μ·day⁻¹) and biomass increase (393.2%), exceeding even the standard BG-11 medium. This treatment also demonstrated exceptional ammonium removal efficiency (95.4%) and enhanced phycocyanin production (33.6 μg/mg, 56% higher than the control). As wastewater concentration increased, both growth parameters and removal efficiency progressively declined. Biochemical analysis revealed that higher wastewater concentrations resulted in decreased protein content and increased lipid accumulation in the biomass. These findings demonstrate the dual potential of Synechococcus sp. for effective wastewater remediation and production of valuable biomass with modifiable biochemical characteristics, offering a sustainable approach for wastewater management in the Peruvian Amazon region. Full article

This study investigated the monthly variations of bacterial communities in the surface seawater of the Wenzhou coastal area and their influencing factors, while exploring the ecological functions of microbial communities. The results indicated that the surface seawater bacterial communities in this region exhibited high diversity, with significantly higher diversity observed in the winter half-year compared to the summer half-year. The bacterial community structures showed distinct monthly variations, with high similarity between adjacent months, particularly from June to September. The dominant bacterial taxa primarily included Proteobacteria represented by the SAR86 clade, OM43 clade, and Rhodobacteraceae; Bacteroidota represented by Flavobacteriaceae; and Cyanobacteria mainly composed of Cyanobium PCC-6307 and Synechococcus CC9902. Temperature and nitrate ions were identified as the environmental factors most strongly correlated with monthly bacterial community variations, while dissolved oxygen, nitrite ions, and total organic carbon also showed significant correlations with relative abundances of certain taxa. Predictions of the bacterial community’s ecological functions revealed that chemoheterotrophic functions were most abundant throughout the year, whereas photoautotrophic functions were primarily enriched in summer. Denitrification and other nitrogen cycling-related functions also displayed obvious monthly variations. Collectively, this study provides valuable insights into the temporal changes in coastal microbial communities and their interactions with different environments. Full article

The enrichment of trace metals and other life-essential elements, like phosphorus, in carbonates may be a signature of microbial life. Enrichments of such elements in microbial carbonate facies in the rock record have been attributed to life in previous studies, but the biologic origin of these enrichments is contentious. We experimentally tested the hypothesis that enrichments of life-important trace elements occur in both cells and carbonate minerals that form as a result of cellular photosynthesis for the cyanobacteria Synechococcus PCC 8806. We grew Synechococcus PCC 8806 and measured the trace element concentrations of the cells and the minerals that precipitate with the cells, and we compared the results to abiotically precipitated mineral material from the same growth medium conditions. We found that for all the tested trace elements (B, P, K, Mn, Fe, Co, Cu, and Zn, chosen for their requirements in the growth medium of Synechococcus PCC 8806 and known uses in cellular machinery), nearly all the sample types were enriched relative to the medium concentrations. The dominant pattern for most elements was that cells were the most enriched, followed by biotic minerals, and then abiotic minerals. However, this pattern was complicated by varying concentrations of Mg in the mineral samples because the data were normalized to Mg (Mg was the dominant cation in the solution next to Na). Nonetheless, however the data are normalized, Fe was the most enriched element in the cells and both the biotic and abiotic minerals relative to the medium concentrations. Fe had the largest enrichment factor (E.F.) for all the sample types, with an E.F. of approximately 2800 in the biotic minerals, 1620 in the cells, and 230 in the abiotic minerals. Fe was followed by Zn (E.F. of ~329 in cells, 198 in biotic minerals, and 78 in abiotic minerals), Cu (E.F. of ~424 in cells, 171 in biotic minerals, and 50 in abiotic minerals), Mn (E.F. of ~200 in cells, 95 in biotic minerals, and 53 in abiotic minerals), and P (E.F. of ~149 in cells, 37 in biotic minerals, and 6 in abiotic minerals), suggesting that these elements can be useful as biosignatures when used in combination with other evidence. Full article

Cyanobacteria negatively affect zooplankton through several mechanisms including mechanical interference, toxicity, and poor food quality due to a shortage of essential lipids. To understand the nature of each of these mechanisms, they should be examined independently. The goal of our study was to assess the influence of cyanobacteria food quality on the competitive outcomes between the small-bodied Daphnia longispina and the large-bodied Daphnia magna. We conducted life-table experiments to assess R* (population threshold food concentration), competition experiments to determine the outcome of competition, and computer simulation experiments at high levels of food supply, which are difficult to realize in laboratory conditions. We used two types of food: the high-quality green algae Chlamydomonas klinobasis (GREEN) and the cyanobacterium Synechococcus elongatus (CYANO), which contains low levels of essential lipids, but is non-toxic and unicellular. We found that the small-bodied D. longispina was a superior competitor in GREEN, while the large-bodied D. magna was more abundant in CYANO. We established that the species ratio in GREEN was dependent on competitive interaction, while abundances of daphnids in CYANO were controlled by poor food quality. Since cyanobacteria act as a powerful force for structuring cladoceran communities, the role of competition for food between these two Daphnia species greatly declined under their effects. Full article

Synechococcus plays a pivotal role in the marine biogeochemical cycle. Advances in isolation techniques and high-throughput sequencing have expanded our understanding of the diversity of the Synechococcus community. However, their genomic diversity, functional dynamics and seasonal variations in the coastal waters are still not well known. Here, seawater samples were collected seasonally (March, June, August, December) from three stations in the coastal waters of Xiamen. Using fluorescence-activated cell sorting (FACS), we isolated 1000 Synechococcus cells per sample and performed ITS amplicon sequencing and metagenomic sequencing to analyze the seasonal variations in community structure and functional genes of Synechococcus. Firstly, we conducted a comparative analysis of in situ data and FACS data from three sampling sites in August. FACS samples revealed low-abundance Synechococcus strains underdetected by in situ samples. In addition, 24 clades representing Synechococcus subclusters S5.1, S5.2, and S5.3 were detected from three in situ samples and twelve FACS samples, suggesting the high diversity of Synechococcus in the coastal waters of Xiamen. Furthermore, the Synechococcus community displayed pronounced seasonal variations, and temperature significantly influenced the variations in Synechococcus community composition. Additionally, Synechococcus populations exhibit seasonal functional dynamics, with enhanced metabolic activity in summer characterized by higher numbers of functional genes associated with metabolic pathways compared to winter samples. Altogether, this study underscored the significance of FACS and high-throughput sequencing to reveal the diversity and functional dynamics of Synechococcus. Full article

Solar photovoltaic technology has consistently been regarded as a crucial direction for the development of clean energy systems in the future. Bio-photovoltaics (BPV), an emerging solar energy utilization technology, is mainly based on the photosynthesis process of photoautotrophic organisms to convert solar energy into electrical energy and output a photocurrent via extracellular electron transfer. As the fundamental unit of the bio-photovoltaic system, the stability of photosynthetic microorganisms under fluctuating and stressful light and heat conditions is likely to have a significant influence on the efficiency of bio-photovoltaic devices. However, this aspect has often been overlooked in previous bio-photovoltaics research. This study took an important cyanobacteria chassis strain, Synechococ elongatus PCC 7942, as the model organism and explored the impact of physiological robustness optimization on its performance as a bio-photovoltaic functional unit. In this work, two types of BPV systems, namely the suspension mode and the biofilm attachment mode, were assembled to evaluate the electricity-generating activity of Synechococcus cells. Overall, the latter demonstrated a remarkable photoelectric output performance. When its light and temperature tolerance was enhanced through FoF1-ATP synthase engineering, the optimized Synechococcus strain exhibited stronger photosynthetic physiology and photoelectric output activity. Under the condition of a light intensity of 2400 μmol photons/m²/s, the maximum photocurrent output of the Synechococcus-based BPV device was increased significantly by 41% over the system based on the wild-type control strain. The results of this study provided a new perspective for the future development and optimization of bio-photovoltaics. Full article

Thermomineral springs are unique aquatic habitats characterized by high temperatures or mineral-rich water and often host specialized microbial communities. In Serbia, these springs represent an important but under-researched ecological resource whose diverse physicochemical properties are shaped by their geological context. In this study, the physical and chemical properties of Serbian thermomineral springs and their relationship with phototrophic communities in different substrates are investigated. Phototrophic biofilms were categorized into fully submerged and splash zone biofilms, with the former showing higher primary production. Cyanobacteria, Chlorophyta, and Bacillariophyta were recorded, with Bacillariophyta being the predominant division in terms of diversity, followed by Cyanobacteria. Among Cyanobacteria, coccoid forms like Aphanocapsa, Chroococcus, Gloeocapsa and Synechococcus dominated splash zones, while trichal forms such as Leptolyngbya, Oscillatoria and Pseudanabaena were abundant in submerged biofilms, forming thick mats. Unique cyanobacterial taxa, including Desertifilum, Elainella, Geitlerinema, Nodosilinea and Wilmottia, were identified through molecular analysis, underscoring the springs’ potential as habitats for specialized phototrophs. Diatom communities, dominated by Nitzschia and Navicula, exhibited site-specific species influenced by microenvironmental parameters. Statistical analysis revealed ammonia, total nitrogen, and organic carbon as key factors shaping community composition. This study enhances the understanding of these ecosystems, emphasizing their conservation importance and potential for biotechnological applications. Full article

Marine bacterioplankton perform a very important role in the cycles of carbon, nitrogen, phosphorus, and other elements in coastal waters. The impacts of environmental factors on bacterial community structure are dynamic and ongoing. This study investigated the spatiotemporal distributions of elements and their influences on bacterioplankton communities in the coastal waters around the Changli Gold Coast National Nature Reserve in northern China. The results demonstrate the significant temporal variability of phosphorus, nitrogen, and carbon in spring and summer, influenced by natural environmental factors and anthropogenic activities. In spring, increased biological activity, particularly phytoplankton growth, may elevate TOC and POC levels near the river estuaries, while in summer, microbial decomposition likely stabilized carbon concentrations. The seasonal variation in the bacterioplankton community was obvious. Bacteroidetes were enriched in spring samples and Cyanobacteriota proliferated in summer. The dominated genera in the spring, including Planktomarina, an unclassified NS5_marine_group (belonging to Flavobacteriaceae), and the OM43_clade (Methylophilaceae), showed significant positive correlation with salinity, TDP, TOC, POP, and DO levels, while Synechococcus_CC9902 (Synechococcus), PeM15_unclassified (Actinobacteria), and HIMB11 (Rhodobacteraceae), which all dominate in summer samples, are significantly positively correlated with TN, TDN, temperature, and ammonium levels. In summer in particular, the increase in human activities and river inputs greatly improves nutrient levels and promotes the propagation of photosynthetic microorganisms. These results indicate that the nutrient elements and environmental physical conditions are affected by seasonal changes and human activities, which have significant effects on the community structure of bacterioplankton. This study highlights the importance of ongoing monitoring in estuarine coastal areas, especially in protected areas like the Changli Reserve, to manage eutrophication risks and maintain ecological balance. Full article

Cyanobacterial cytochrome c6 (Cyt c6) is crucial for electron transfer between the cytochrome b6f complex and photosystem I (PSI), playing a key role in photosynthesis and enhancing adaptation to extreme environments. This study investigates the high-resolution crystal structures of Cyt c6 from Synechococcus elongatus PCC 7942 and Synechocystis PCC 6803, focusing on its dimerization mechanisms and functional implications for photosynthesis. Cyt c6 was expressed in Escherichia coli using a dual-plasmid co-expression system and characterized in both oxidized and reduced states. X-ray crystallography revealed three distinct crystal forms, with asymmetric units containing 2, 4, or 12 molecules, all of which consist of repeating dimeric structures. Structural comparisons across species indicated that dimerization predominantly occurs through hydrophobic interactions within a conserved motif around the heme crevice, despite notable variations in dimer positioning. We propose that the dimerization of Cyt c6 enhances structural stability, optimizes electron transfer kinetics, and protects the protein from oxidative damage. Furthermore, we used AlphaFold3 to predict the structure of the PSI-Cyt c6 complex, revealing specific interactions that may facilitate efficient electron transfer. These findings provide new insights into the functional role of Cyt c6 dimerization and its contribution to improving cyanobacterial photosynthetic electron transport. Full article

The shallow-sea hydrothermal vent at Guishan Islet, located off the coast of Taiwan, serves as a remarkable natural site for studying microbial ecology in extreme environments. In April 2019, we investigated the composition of prokaryotic picoplankton communities, their gene expression profiles, and the dissolved inorganic carbon uptake efficiency. Our results revealed that the chemolithotrophs Thiomicrorhabdus spp. contributed to the majority of primary production in the waters affected by the hydrothermal vent plume. The metatranscriptomic analysis aligned with the primary productivity measurements, indicating the significant gene upregulations associated with carboxysome-mediated carbon fixation in Thiomicrorhabdus. Synechococcus and Prochlorococcus served as the prokaryotic photoautotrophs for primary productivity in the waters with lower influence from hydrothermal vent emissions. Thiomicrorhabdus and picocyanobacteria jointly provided organic carbon for sustaining the shallow-sea hydrothermal vent ecosystem. In addition to the carbon fixation, the upregulation of genes involved in the SOX (sulfur-oxidizing) pathway, and the dissimilatory sulfate reduction indicated that energy generation and detoxification co-occurred in Thiomicrorhabdus. This study improved our understanding of the impacts of shallow-sea hydrothermal vents on the operation of marine ecosystems and biogeochemical cycles. Full article