Long-term excessive application of chemical fertilizers (CF) has led to a decline in soil fertility and the deterioration of soil health. Consequently, developing eco-friendly microbial fertilizers as alternatives to chemical inputs has become a global consensus for promoting sustainable agriculture. To explore the underexplored potential and soil-modulating mechanisms of microalgae-based fertilizers, this study investigates their feasibility of microalgae-based fertilizers as CF substitutes for enhancing the yield and quality of peppers (Capsicum annuum L.). We compared the application effects of three types of microalgae-based fertilizers, namely total microalgal biomass (TMB), microalgal extracts (ME), and microalgae-bacteria consortia (MBC, supplemented with Bacillus spp.) under different fertilization regimes (sole- and co-application with reduced compound fertilizer) on plant traits and soil microbial communities. The results indicated that all three microalgal fertilizers significantly promoted seed germination, plant growth, and fruit yield. Notably, sole application of TMB exhibited the most prominent growth-promoting effects with an increase of 13%-37% compared to the CF treatment. The T2 treatment (substituting 40% of CF) achieved the highest pepper yield, representing a 72% increase over the CF control. Regarding soil properties, microalgal fertilizers effectively adjusted soil pH, lowered electrical conductivity and exhibited desirable slow-release fertilizer characteristics. In particular, TMB significantly increased soil organic matter content and maintained a stable supply of available phosphorus during the fruit-harvesting stage. Analysis of microbial community structure and function revealed that the application of microalgal fertilizers enriched various plant growth-promoting microbes, such as Bacillus, Neurospora and Trichoderma, which possess functions in nutrient mineralization or biocontrol. Concurrently, these treatments significantly enhanced the activities of soil enzymes (urease, phosphatase, and sucrase) and functional pathways related to carbon and nitrogen metabolism. Our findings highlight that the microalgal fertilizers represent an optimal strategy for achieving chemical fertilizer reduction and efficiency enhancement while improving soil bio-fertility.

Microalgae have been investigated for the production of different biofuels, and the feedstock is gaining interest in the present day due to their fast growth potential added to relatively high lipid, carbohydrate, and nutrient contents. The purpose of this study is to perform research to grow commercial microalgae and to produce a significant amount of lipid content from microalgae harvested as a viable alternative to renewable energy. The commercial microalga chosen is Chlorella sorokinian. Nitrogen is an essential element for microalgal growth, lipid synthesis, and several physiological processes. Microalgae can utilize several nitrogen sources, including nitrate and ammonium. The growth and lipid content of microalgae cultures and their biochemical structures are influenced by the type of nitrogen utilized, which is contingent upon the specific species of algae and the quantities and sources of nitrogen. This study aims to increase the growth and lipid accumulation of the microalga Chlorella sorokiniana by varying the nitrogen sources NaNO3, KNO3, and NH4Cl concentration inthe culture medium. Results indicate thatthe highest cell density of28.83 x 107cellmL-1 and the maximum 4.1 g L-1 dry biomass were obtained under the treatment of sodium nitrate. Among nitrogen sources, the better pigment contents chl a 17.2 mg L-1 and chl. b contents were recorded in the case of sodium nitrate, followed by potassium nitrate and ammonium chloride. However, carbohydrate production was found to be a maximum of 390.1 mu g mL-1 in ammonium chloride culture. The lipid content was measured using the Bligh and Dyer method and observed the highest 19% in sodium nitrate culture compared to other nitrogen sources. Overall, it can be concluded that sodium nitrate culture produced promising results regarding biomass production and different biochemical attributes.

Biofertilizers derived from microalgae are increasingly used as promising materials for improving crop growth and development, producing fewer catastrophic environmental effects. Hence, the large-scale production of eco-friendly and broad-spectrum microalgae biofertilizers is mandatory. Therefore, this study was designed to examine the potential efficacy of isolated algae strains, such as Spirulina platensis, Spirulina maxima, and Chlorella vulgaris, to improve the growth and development of Pak Choi. A completely randomized design (CRD) was carried out, with five replications and six levels (0, 0.5, 1.0, 1.5, 2.0, and 2.5 g) of each microalga biofertilizer, using Pak Choi as the test plant. Treatment with microalgae biofertilizers was found to increase Pak Choi’s overall growth performance, biochemical development, and nutritional composition. The application of Spirulina platensis and Spirulina maxima microalgae at 2 g as a biofertilizer showed significant (p < 0.05) positive impacts on above- and below-ground biomass, photosynthetic parameters, biochemical composition, and the nutritional attributes of different parts of Pak Choi tissues. With the addition of biofertilizer, incorporating Chlorella vulgaris (2.5 g) showed remarkable (p < 0.05) impacts on the development of above- and below-ground biomass and biochemical and nutritional attributes. Thus, our results highlight that Chlorella vulgaris (2.5 g) outperforms other biofertilizer treatments and could be considered a sustainable approach for producing leafy vegetables.

Microalgae can efficiently remove nutrients and pollutants from wastewater while converting these substances into reusable biomass. This study explores the potential of microalgae for dairy manure wastewater (DMW) treatment via optimizing process conditions, and employing an algal-bacterial biofilm for continuous wastewater treatment coupling with bioproducts production. A pollutant-tolerant microalga Desmodesmus sp. and a bacterium Bacillus megaterium (Ds-Bm), when co-cultured in suspension, demonstrated efficacy in removing COD and ammonia nitrogen of 50 % raw DMW wastewater under an adjusted nitrogen: phosphorous ratio of 16:1. The total lipid content increased by 45.9 % compared to pure algae culture. A continuous algae-bacterial biofilm photobioreactor was then constructed for raw DMW wastewater treatment without dilution, achieving a COD removal efficiency of 85-92.2 % and meeting the emission standards for livestock wastewater. The ammonium nitrogen removal load reached 4.6 g N/m3/d, with a maximum removal efficiency of 46.5 %. Following a 21-day operation, algae biomass notably increased (the yield and productivity were 122.5 g/m(2) and 3.7 g/m2/d), with a 15.8 % lipid content. Cultivation in DMW led to a significant reduction in the C18:3 polyunsaturated fatty acid content (<12 %), ensuring compliance with biodiesel feedstock standards. Hence, this Ds-Bm biofilm photobioreactor offers promise for effective wastewater treatment and cost-efficient biodiesel production.

Microalgal-bacterial consortia can treat biogas slurry and produce high-value products. This study found that co-cultures of Desmodesmus sp. and Bacillus megaterium improved nutrient removal, biomass production, and lipid accumulation in Desmodesmus sp. Dual transcriptomic analyses revealed that B. megaterium upregulated genes associated with glycolysis, the Calvin cycle, tricarboxylic acid cycle, indole acetic acid synthesis, and fatty acid biosynthesis in Desmodesmus sp. Under a high C/N ratio, key genes involved in fatty acid degradation were downregulated, promoting lipid accumulation in co-cultured Desmodesmus sp. Effective NH4+-N removal in the co-culture under a high C/N ratio was attributed to microbial interactions. Desmodesmus sp. downregulated the URE gene in bacteria, inhibiting urea hydrolysis, while B. megaterium upregulated the URE and gdhA genes in microalgae, promoting urea utilization and NH4+-N assimilation. This study provides new insights into the transcriptional regulation in nutrient assimilation and lipid metabolism in microalgal-bacterial consortia.

Global climate change has resulted in alterations in salinity in both marine and freshwater environments, posing severe challenges to the survival of diatoms. Elucidating the physiological responses and adaptive mechanisms of diatoms, particularly those inhabiting estuarine regions, to salinity fluctuations holds significant ecological implications for sustaining primary productivity in estuarine ecosystems and preserving biodiversity in coastal zones. In this study, we investigated the metabolic adaptation of Thalassiosira profunda to salinity over short term (7 days) and long term (2 years) periods at two salinity levels (30 PSU and 15 PSU) by analyzing physiological changes and transcriptomics. The results demonstrated that T. profunda responded to oxidative damage by increasing synthesis of polysaccharides, proteins and enhancing antioxidant enzyme activities when exposed to low salinity. T. profunda upregulated photosynthesis to obtain additional energy for oxidative damage repair. We observed that short-term salinity change resulted in a reprogramming of cellular nitrate metabolism, TCA cycle and fatty acid metabolism. The upregulation of mitogen-activated protein kinase signaling pathway enhanced intrinsic cellular catalase activity levels, which might be crucial for alleviating photosystem damage in long-term low salinity adaptation.

Eukaryotes and prokaryotes in the estuarine euphotic zone, play a pivotal role in maintaining biodiversity and ecosystem stability. However, the mechanisms underlying microbial interactions and community assembly across estuarine environmental gradients, particularly those shaped by brackish water mixing, remain poorly understood. We conducted extensive seasonal sampling of planktonic microbial communities in the Yangtze River Estuary, combining high-throughput sequencing of 16S and 18S rRNA genes with simulated mixing experiments. Our study elucidated the mechanisms driving spatial patterns and community assembly processes of eukaryotes, free-living bacteria, and particle-associated bacteria across a broad salinity gradient (0.2-30.7 PSU). Controlled laboratory simulations of freshwater and seawater mixing were performed to elucidate microbial community responses to salinity gradients under experimentally defined conditions. During the dry season, bacterial community assembly is primarily governed by homogenizing dispersal, whereas homogenizing selection predominates in the wet season. Increased wet season freshwater input reduces heterogeneous selection in eukaryotic microorganisms. Robustness metrics and topological analyses revealed greater stability in estuarine eukaryotic and planktonic bacterial networks during the wet season compared to the dry season. We found an increase in neutral processes significantly enhanced the nestedness of microbial networks. SourceTracker analyses identified particle-associated bacteria as the primary source of swimming and adhering bacteria following mixing experiments. Fresh-seawater mixing increased nestedness via reduced richness of particle-associated bacteria. Our findings offer valuable insights into how microbial communities in transitional estuarine ecosystems respond to hydrological and salinity-driven disturbances, providing a scientific basis for assessing ecological stability and informing environmental management under global change scenarios.

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Estuaries, acting as transitional habitats receiving species introductions from both freshwater and marine sources, undergo significant impacts from global climate changes. Planktonic microorganisms contribute significantly to estuarine biodiversity and ecological stability. These microorganisms primarily fall into three groups: eukaryotic plankton, particle-associated bacteria, and free-living bacteria. Understanding the structural characteristics and interactions within these subcommunities is crucial for comprehending estuarine dynamics. We collected samples from three distinct locations (< 0.1 PSU, 6.6 PSU, and 19 PSU) within the Yangtze River estuary. Samples underwent analysis for physicochemical indicators, while microbial communities were subjected to 16S/18S rRNA amplicon sequencing. Additionally, simulated mixing experiments were conducted using samples of varying salinities. Estuary samples, combined with simulated experiments, were employed to collectively examine the structural characteristics and assembly processes of estuarine microbes. Our research highlights the considerable impact of phylogenetic classification on prokaryotic behavior in these communities. We observed a transition in assembly processes from primarily stochastic for particle-associated bacteria to a predominant influence of homogeneous selection as salinity increased. Particle-associated bacterial communities exhibited a greater influence of stochastic processes compared to free-living bacteria, showcasing higher stability in diversity. The variations in composition and structure of estuarine microbial subcommunities were influenced by diverse environmental factors. Particle-associated bacteria displayed elevated network characterization values and established closer interactions with eukaryotic plankton. Structural equation modeling (SEM) analysis revealed that free-living bacteria displayed a heightened sensitivity to environmental factors and exerted a more significant influence on assembly processes and network characteristics. Simulated mixing in these environments resulted in the loss of species with similar microbial taxonomic relationships. The functioning of bacterioplankton is influenced by salinity and the processes governing their assembly, particularly in relation to different living states. These findings significantly contribute to our understanding of the intricate interplay between prokaryotic and eukaryotic plankton microorganisms in highly dynamic environments, laying a robust foundation for further exploration into the ecological mechanisms governing microbial dynamics in estuaries.

Salinity stress in estuarine environments poses a significant challenge for microalgal survival and proliferation. The interaction between microalgae and bacteria shows promise in alleviating the detrimental impacts of salinity stress on microalgae. Our study investigates this interaction by co-cultivating Chlorella sorokiniana, a freshwater microalga, with a marine growth-promoting bacterium Pseudomonas gessardii, both of which were isolated from estuary. In this study, bacteria were encapsulated using sodium alginate microspheres to establish an isolated co-culture system, preventing direct exposure between microalgae and bacteria. We evaluated microalgal responses to different salinities (5 PSU, 15 PSU) and interaction modes (free-living, gel-encapsulated), focusing on growth, photosynthesis, cellular metabolism, and extracellular polymeric substances (EPS) properties. High salinity inhibited microalgal proliferation, while gel-fixed interaction boosted Chlorella growth rate by 50.7 %. Both attached and free-living bacteria restored Chlorella's NPQ to normal levels under salt stress. Microalgae in the free-living interaction group exhibited a significantly lower respiratory rate compared to the pure algae group (-17.2 %). Increased salinity led to enhanced EPS polysaccharide secretion by microalgae, particularly in interaction groups (19.7 %). Both salt stress and interaction increased the proportion of aromatic proteins in microalgae's EPS, enhancing its stability by modulating EPS glycosidic bond C-O-C and protein vibrations. This alteration caused microalgal cells to aggregate, free-living bacteria co-culture group, and fixed co-culture group increasing by 427.5 %, 567.1 %, and 704.1 %, respectively. In gel-fixed bacteria groups, reduced neutral lipids don't accumulate starch instead, carbon redirects to cellular growth, aiding salt stress mitigation. These synergistic activities between salinity and bacterial interactions are vital in mitigating salinity stress, improving the resilience and growth of microalgae in saline conditions. Our research sheds light on the mechanisms of microalgal-bacterial interactions in coping with salt stress, offering insights into the response of estuarine microorganisms to global environmental changes and their ecological stability.

Microplastics (MPs) are emerging pollutants, causing potential threats to aquatic ecosystems and serious concern in aggregating with microalgae (critical primary producers). When entering water bodies, MPs are expected to sink below the water surface and disperse into varying water compartments with different light intensities. However, how light influences the aggregation processes of algal cells onto MPs and the associated molecular coupling mechanisms and derivative risks remain poorly understood. Herein, we investigated the aggregation behavior between polystyrene microplastics (mPS, 10 µm) and Chlorella pyrenoidosa under low (LL, 15 μmol·m-2·s-1), normal (NL, 55 μmol·m-2·s-1), and high light (HL, 150 μmol·m-2·s-1) conditions from integrated in vivo and in silico assays. The results indicated that under LL, the mPS particles primarily existed independently, whereas under NL and HL, C. pyrenoidosa tightly bounded to mPS by secreting more protein-rich extracellular polymeric substances. Infrared spectroscopy analysis and density functional theory calculation revealed that the aggregation formation was driven by non-covalent interaction involving van der Waals force and hydrogen bond. These processes subsequently enhanced the deposition and adherence capacity of mPS and relieved its phytotoxicity. Overall, our findings advance the practical and theoretical understanding of the ecological impacts of MPs in complex aquatic environments.

Polar microalgae, renowned for their exceptional adaptability in extreme environments, are vital for carbon fixation and nutrient cycling. To understand their metabolic resilience under low temperature and high light stress, we conducted an extensive biochemical and full-length transcriptome analysis of Arctic Chlorella (Chlorella-Arc) and temperate Chlorella (Chlorella-Temp). This research aimed to comprehensively assess Chlorella's adaptability to the interactive effects of temperature and light stress. Under low-temperature stress, intense light inhibited Chlorella-Temp growth by 14.8 %, while it significantly promoted Chlorella-Arc growth by 88.8 %. The cold-adapted Chlorella-Arc demonstrates higher tolerance to high light stress. Elevated temperature (+0.80) and light (+0.47) directly increased cell density, revealing direct and indirect effects of temperature and light on Chlorella-Arc bioproducts via structural equation modeling. We then analyzed key molecules involved in lipid metabolism using orthogonal projections to latent structures discriminant analysis, confirmed that Chlorella-Arc maintained a relatively constant fatty acids composition under low temperature and high light stress. Compared to its temperate counterpart, Chlorella-Arc exhibits unique adaptability by modulating polysaccharide composition, downregulating carbon fixation, reducing nitrogen absorption, and maintaining stable unsaturated fatty acid levels with a higher unsaturated to saturated fatty acid ratio. Chlorella-Arc, a prime example of polar microalgae adaptability, exhibits unique metabolic responses. Compared to the low-temperature normal-light group, the high-light Chlorella demonstrates precise regulation of nitrogen uptake and carbon allocation, while activating multiple antioxidant pathways to mitigate the increase in ROS levels under light stress. Acclimated Chlorella-Arc tends to increase triacylglycerol accumulation, suggesting a shift in carbon flow towards lipid production. Our analyses reveal specialized adjustments, enabling survival in harsh conditions of low temperature and intense light. This research enhances our understanding of microalgal resilience in extreme environments, offers valuable insights into the utilization of polar microalgal bioproduct resources.

In this work, a membrane photobioreactor integrating with a flashing light (MFLPBR) has been developed for dense culture of a fast growing and oil -rich benthic diatom mutant Nitzschia sp. L8. Under 45 mu mol/m2/s light intensity, 0.5 Hz flashing light (FL) could obviously improve the photosynthetic activity, specific growth rate and biomass yield of L8, with the increments by 18.5 %, 32.2 % and 137.6 % comparing to the continuous illumination culture. The total lipid content of L8 reached up to 53.5 % of dry weight, indicating a diversion of carbon flow from carbohydrates to lipids, resulting in increased biomass and lipid accumulation under FL. When L8 was subject to attached growth on the membrane surface in MFLPBR, cell growth was further improved, reaching the biomass yield and lipid productivity of 0.423 g/L and 30.35 mg/L/d in MFLPBR. The MFLPBR was proved to be a feasible strategy to promote the growth of benthic diatom for biomass and lipid production.

Rapana venosa , a well-known and economic species mainly distributed in the Asian region, has three distinct color patterns in the peristome: pure orange, pure dark stripes, and part stripes. The present study combined microsatellite, DNA methylation, and transcriptome to assess the genetic basis of three color patterns of R. venosa in the peristome. The different color patterns of R. venosa showed no significant genetic differentiation, and each color group was relatively independent with respect to gene flow. Each color pattern showed a high methylation rate of more than 60%. The full-methylation rates for the three color patterns were 34.47%, 35.67%, and 32.54%, respectively. The Gene Ontology (GO) classification and functional enrichment revealed three ontologies: molecular function, cellular components, and biological processes. The function of translation, ribosomal structure, and biogenesis accounted for the top classification, followed by general function prediction. This study also revealed some functional genes related to color and shell formation, including Scavenger receptor cysteine-rich protein (SRCR), beta-carotene ketolase, tyrosinase proteins, and Lustrin A. These findings suggest that the color polymorphism of R. venosa is possibly attributed to environmental effects. The research is also essential for selecting better germplasm for the breeding of Rapana venosa .

To elucidate the impacts of culture temperature on nutrient removal efficiency of Pyropia-processing wastewater (PPW) and microalgal biomass production, Chlorella sp. C2 was employed and cultivated in raw PPW under different temperatures. Results showed that, after incubating for 7 days, higher biomass (0.50 g/L) and total lipids (21.84 %) were attained at 35 °C. The maximal chemical oxygen demand (COD), phycobiliprotein, total nitrogen and total phosphorus removal rates were observed at 30-35 °C and separately reached 62.41 %, 92.61 %, 92.19 % and 98.33 %. Interestingly, COD removal efficiencies of Chlorella cells, cultivated for 3, 5 and 7 days at 30-35 °C, 15-25 °C and 10 °C respectively, could reach >75 % with assistance from 60-80 mg/L chitosan. Meanwhile, the clarification efficiency of chitosan on algal cells reached >95 %. It suggests that Chlorella strain cultured at altered temperatures could efficiently remove PPW nutrients assisted by moderate chitosan, simultaneously achieving the rapid harvest of microalgae.

The discharge of massive nutrient-rich Pyropia-processing wastewater (PPW) will result in severe environmental pollution. To explore an efficient strategy to purify PPW, the nutrient removal efficiency and growth perfor-mance of Scenedemus obliquus on PPW were investigated under the conditions of different culture substrates, and the impacts of chitosan-based flocculation on the nutrient elimination rates were analyzed under various pH values. Results showed that, after cultivating S. obliquus in PPW for 7 days, the removal rates of chemical oxygen demand (COD), phycobiliprotein (PP), total nitrogen (TN) and total phosphorus (TP) reached 53.87 %, 89.36 %, 85.75 % and 93.61 %, respectively. Interestingly, the maximal COD removal efficiency could increase to 82.82 % by adding 40 mg/L chitosan to flocculate the cultures under a pH level of 9, where the aggregation rate on algal cells reached similar to 100 %. Besides, the increments in biomass and lipid productivity of S. obliquus cultured in PPW were 1.25 and 1.53 times higher than that of BG11, and intracellular protein content and productivity separately increased by 29.79 % and 1.92-fold. These results demonstrate S. obliquus could efficiently decrease various nutrients in PPW, which was markedly further improved by combining with chitosan, simultaneously achieving the rapid harvest of microalgal biomass.

Polyethylene terephthalate-based glitters (PET glitters) are a potential source of primary microplastics in the environment. However, the bioeffects of PET glitters and the associated leachates remain largely unknown. In this study, we investigated the individual and combined toxicity of five colors (silver, black, red, green, and blue) of PET glitters and their corresponding leachates on the cellular responses of Desmodesmus sp. The results indicated that the photosynthesis of Desmodesmus sp. could be partly affected by PET glitters through the shading effect, but not that of growth. Conversely, the leachates of red and green PET glitters significantly inhibited the growth of the microalga, suggesting a higher risk associated with additives leached from these colors of PET glitters. Furthermore, the adverse effects of the co-occurrence of PET glitters and leachates were closely related to oxidative stress responses in the microalgal cells, along with a color effect, which could be mainly attributed to variations in the composition and abundance of toxic additives in different colors of PET glitters. Overall, our findings provide insights into the ecological risks posed by glitters in aquatic environments and emphasize the importance of considering color factors in assessing microplastics toxicity.

The coexistence of nanoplastics and antibiotics in the aquatic environment has raised a complicated risk for ecosystems and human health. How the environmental factors e.g., light, regulate the interaction between nanoplastics and antibiotics and the resulting combined toxicity is poorly understood. Here, we investigated the individual and combined toxicity of polystyrene nanoplastics (nPS, 100 mg L1) and sulfamethoxazole (SMX, 2.5 and 10 mg L-1) toward the microalgae Chlamydomonas reinhardtii under low (LL, 16 mu mol m(-2)center dot s(-1)), normal (NL, 40 mu mol m(- 2)center dot s(-) 1), and high light (HL, 150 mu mol m(-2)center dot s(-1)) in terms of cellular responses. Results indicated that the joint toxicity of nPS and SMX commonly exhibited a strong antagonistic/mitigative effect under LL/NL at 24 h, and under NL at 72 h. nPS could adsorb more SMX under LL/NL at 24 h (1.90/1.33 mg g(-1)) and under NL at 72 h (1.01 mg g(-1)), thereby alleviating SMX toxicity to C. reinhardtii. However, the self-toxicity of nPS had a negative influence on the degree of antagonism between nPS and SMX. The experimental results coupled with computational chemistry further revealed that the adsorption capacity of SMX on nPS was stimulated by low pH under LL/NL at 24 h (similar to 7.5), while by less co-existing saline ions (0.83 ppt) and algae-derived dissolved organic matter (9.04 mg L-1) under NL at 72 h. nPS toxicity that was responsible for the toxic action modes was mainly attributed to the shading effect induced by hetero-aggregation and hindrance of light transmittance (>60%), as well as being regulated by additives leaching (0.49-1.07 mg L-1) and oxidative stress. Overall, these findings provided a critical basis for the risk assessment and management of multiple pollutants in the complex natural environment.

There has been a growing demand for efficient disposal of kelp waste. Microbial degradation is a win–win bio-solution for seaweeds waste disposal and acquisition of nutritious byproducts. In this study, the cooperation of an alginate lyase producing bacteria (Paenibacillus sp. QBH) and cellulase producing bacteria (Enterococcus sp. N1) was applied for its high degrading efficiency of kelp waste. Serial single factor experiments revealed that temperature, shaking speed and degradation time were the key factors impacting the alginate lyase and filter paper assay activities upon hydrolyzing kelp waste by N1 + QBH combination. Via response surface method optimization, predicted models for the alginate lyase and filter paper assay activities asserted the highest values could be attained at the temperature 34 °C, shaking speed 180 rpm and degradation time 4.5 days. This prediction was verified by a triplicate experiment giving an average alginate lyase activity of 61.2 U mL−1 and filter paper assay activity of 6.12 U mL−1. Biodegradation of kelp waste by N1 + QBH combination under optimizing conditions remarkably promoted the release of sugars, total phenolic compounds, various minerals and amino acids, generating a nutritious hydrolysate with a total organic matters yield of 56.3 g L−1, total phenolic compounds yield of 18.3 mg g−1 dry weight and total amino acids concentration of 247.3 mg L−1. This study highlights that N1 + QBH combination could be a feasible solution for bioconversion of kelp waste to sustainable production of biostimulant.