High Lipid Content Research Articles

Revealing the functional potential of microbial community of activated sludge for treating tuna processing wastewater through metagenomic analysis.

Reports regarding the composition and functions of microorganisms in activated sludge from wastewater treatment plants for treating tuna processing wastewater remains scarce, with prevailing studies focusing on municipal and industrial wastewater. This study delves into the efficiency and biological dynamics of activated sludge from tuna processing wastewater, particularly under conditions of high lipid content, for pollutant removal. Through metagenomic analysis, we dissected the structure of microbial community, and its relevant biological functions as well as pathways of nitrogen and lipid metabolism in activated sludge. The findings revealed the presence of 19 phyla, 1,880 genera, and 7,974 species, with Proteobacteria emerging as the predominant phylum. The study assessed the relative abundance of the core microorganisms involved in nitrogen removal, including Thauera sp. MZ1T and Alicycliphilus denitrificans K601, among others. Moreover, the results also suggested that a diverse array of fatty acid-degrading microbes, such as Thauera aminoaromatica and Cupriavidus necator H16, could thrive under lipid-rich conditions. This research can provide some referable information for insights into optimizing the operations of wastewater treatment and identify some potential microbial agents for nitrogen and fatty acid degradation.

Using chlorella vulgaris as a natural-textile dye

The applications of algae are becoming more popular day by day. From biofuels to nutrients, cosmetics, pharmaceuticals, and most recently ink and textile dyes. Due to algae’s high lipid content that works best as a substitute for petroleum-based products, and because it is carbon negative and eco-friendly, algae-based dyes can present a transitional solution to the environmental damages caused by the dyeing phases in the textile industry. Researchers have investigated the types, methods, applications, and efficiency of various algae species and types of dyes to serve in various coloring and printing applications. In this paper, we present the possibility of using microalgae as a natural dye for the textile industry. The microalgae studied were mixed species dominated by Chlorella Vulgaris. Pigments were extracted by acetone to create the natural dye which was used on a 100% cotton fabric using basic dying methods. A light-fastness test was subsequently performed, and the results indicated that the algae-colored fabric gained a value similar to those usually obtained with natural dyes.

Ekstraksi Komponen Lipid dari Mikroalga Nannochloropsis oculata dan Nitzschia sp. dengan Metode Sokletasi dan Bligh Dyer

Dependence on fossil energy sources as non-renewable energy will trigger the threat of an energy crisis in Indonesia in the future. The solution to this issue is through the development of renewable energy and one of them is through the exploration and utilization of biomass such as microalgae. Microalgae have a high lipid content (4-77%) and have potential as raw materials for producing biofuel (biodiesel, bioethanol, and biogas). Lipids can be converted into biodiesel through acid or base-catalyzed esterification and transesterification reactions. The aim of this research was to determine the percentage of lipid components, namely free fatty acids (FFA), monoglycerides (MAG), diglycerides (DAG), and triglycerides (TAG) from microalgae extracts of Nannochloropsis oculata and Nitzschia sp. using Soxhletation and Bligh Dyer extraction methods. This research also aims to determine the comparison of lipid yields from the two extraction methods. Lipid yield percentage was determined through gas chromatography analysis. The research results showed that the percentages of FFA, MAG, DAG, and TAG for N. oculata ranged from 3.34 - 33.79% (soxhletation) and 0 - 17.54% (bligh dyer). Meanwhile, for Nitzschia sp., the percentage ranged from 7.16 - 26.28% (soxhletation) and 0.45 - 13.73% (bligh dyer). Lipid yield for N. oculata was 1.81% (soxhletation) and 2.21% (bligh dyer), while for Nitzschia sp., 0.96% (soxhletation) and 2.10% (bligh dyer). Based on the results of both extraction methods, it was found that the total lipid percentage of the microalgae N. oculata was higher than Nitzschia sp.
 
 

Salinity Induced the Growth and Proximate Composition of Euglena sp., Local Strain from Dieng, Indonesia

AbstractHigh salinity is a challenging environmental stress for organisms to overcome. This study studied the effect of NaCl and KCl with various concentrations (0, 100 mM and 200 mM) for 13 days to explore the physiological, morphological and proximate composition of Euglena sp. Euglena sp. exhibited a significant decrease in growth rate, photosynthetic pigment, and increasing salinity. Meanwhile, the highest biomass, protein and carbohydrate content were found in KCl 100 mM with values; of 0.586 mg/mL, 0.050 μg/mL and 904.589 mg/mL, respectively. The highest lipid content was found in treatment with 200 mM NaCl with 0.42 mg/mL. Euglena sp. treated with salt type NaCl and KCl with a concentration of 200 mM showed an increase in SFA content but a decrease in PUFA content. PUFA content shows many variations of fatty acids. Still, the number of fatty acids like methyl linoleate and methyl linolenate does not exceed the limit of 12% (wt) of the European B100 biodiesel standard. It shows that the salt stress approach with salt type NaCl and KCl effectively increases biofuel production in Euglena sp. Therefore, Euglena sp. is suitable for high-salinity cultivation and biofuel production.

ADVANTAGES AND CHALLENGES OF BIODIESEL PRODUCING MICROALGAE

Microalgae are a promising source of biodiesel because they have several advantages over traditional feed stocks, such as corn and soybeans. These advantages include high growth rate and lipid content, can be grown in non-arable land, removes CO2 from the atmosphere, and produces other valuable products. However, there are also some challenges to producing biodiesel from microalgae, including high cost of production, technical challenges, and public acceptance. Despite these challenges, microalgae still have the potential to be a major source of biodiesel in the future. As the technology continues to develop and the cost of production decreases, microalgae are likely to become a more economically viable option for producing biodiesel. Additionally, the environmental benefits of microalgae cultivation, such as CO2 removal and the production of other valuable products, make them a more sustainable option than traditional feedstock.

Effect of Nitrate on the Growth and Lipid Accumulation in Microalgae Picochlorum sp.

Picochlorum sp. algae are known for their rich bioactive compounds, including valuable substances such as astaxanthin, carotenoids, fatty acids, and lutein. However, the high potential total lipid content within Picochlorum sp. algae opens up possibilities for various applications in the fields of bioenergy, food, and pharmaceuticals. Therefore, it is essential to investigate the lipid content, chlorophyll, and growth rates of Picochlorum sp. algae by examining the influence of nutrient sources, namely nitrate MD4 0.5M medium. Adapting method SPSS, determing chlorophyll, carotenoids and lipid content. Picochlorum sp. algae were cultivated in MD4 0.5M medium with concentrations of nitrate-supplemented 5 g/L with high level of the specific growth rate, chlorophyll and carotenoid. It clearly to evaluate that important of nitrate by the death of Picochlorum sp. In control group on 6th day cultivation. Through the statistics, it can be observed that the chlorophyll and carotenoid levels increase significantly on day 12 and gradually decrease on subsequent days. This indicates that nutrient- depleted conditions, specifically the lack of nitrate-supplemented, lead to the accelerated growth decline of Picochlorum sp. However, when the nitrient-depleted conditions are reversed, it is evident that the lipid content in Picoclorum sp. Microalgae gradually accumlates and does not reach a plateau until 24 of cultivation. Additionally, it is also noticeable that nitrate accumulation in lipids is higher at nitrate supplementation levels ranging from 0.5 g/L to 2.5g/L compared to levels exceeding 5g/L.

The potential of microalgae for the development of innovative technologies for the protection and preservation of the environment

Microalgae are mainly known for their high nutritional value, protein and lipid content. They are used to enrich animal feeds and are recommended as food supplements in the human diet. Nowadays, it is possible to design the cultivation conditions of microalgae in order to produce them with the specific characteristics desired. Since this is so important, the aim of this work is to present the progress made by different research groups on the best cultivation conditions to optimize the intensive production of microalgae. It also presents the most recent lines of research on the use of microalgae for the care of the environment, their potential application in the remediation of air pollution, as well as their use in the removal of various toxic substances in water. The methodology used was to make an exhaustive bibliographic review of books, journals, theses and articles on the subject, showing in a simple, clear and summarized way that microalgae are an option of 100% natural use of multiple benefits in the protection and restoration of ecosystems, in addition to being a sustainable alternative to other technological options for the remediation of water and air pollution.

Integration of genetic engineering and multi-factor fermentation optimization for co-production of carotenoid and DHA in Schizochytrium sp

Schizochytrium sp., a microalga with high lipid content, holds the potential for co-producing docosahexaenoic acid (DHA) and carotenoids. In this study, the ability of Schizochytrium sp. to naturally produce carotenoids was systematically explored. Further, by enhancing the precursor supply of geranylgeranyl diphosphate, regulating carbon source through sugar limitation fermentation and employing a combination of response surface methodology and artificial neural networks to precisely optimize nitrogen sources, a new record of 43-fold increase in β-carotene titer was achieved in the 5L bioreactor (653.2 mg/L). Meanwhile, a high DHA content was maintained (13.4 g/L). Furthermore, the use of corn stover hydrolysate has effectively lowered the production costs of carotenoid and DHA while sustaining elevated production levels (with total carotenoid titer and DHA titer reached 502.0 mg/L and 13.2 g/L, respectively). This study offers an efficient and cost-effective method for the co-production of carotenoid and DHA in Schizochytrium sp..

Micro-algae: Revolutionizing food production for a healthy and sustainable future

The concept of developing innovative functional food products has attracted the attention of many researchers to meet global demands as well as keep into account the well-being of people and environmental sustainability. Microalgae can be an essential raw material to fulfill such an objective. They can potentially provide a long-term solution to feed the expanding global population. This is evident by the presence of characteristics possessed by microalgae such as high biomass productivity, remarkable nutritional qualities, appealing organoleptic features, and tolerance to biotic and abiotic stress. When compared to traditional crop species, algae have a higher concentration of lipids and proteins and are more environmentally friendly because they lack cellulose, which is an inedible material. Moreover, despite the existing obstacles such as poor technology preparedness and restricted economies of scale, micro-algae holds promise for a future where healthier and more sustainable food items can contribute to better dietary habits, lifestyles, and overall health. This review attempts to emphasize the potential of microalgae as a healthy and sustainable dietary alternative. Moreover, the significance of bioactive metabolites obtained from microalgae in reducing greenhouse gases, sewage treatment, bioremediation, photocatalytic degradation, production of nanoparticles, nutraceuticals, and abiotic stress resilience. The selection of suitable and cost-efficient cultivation and harvesting techniques required for growing microalgae and manufacturing its products will be a boon to many food industries.

Recycling Ophthalmic Lens Wastewater in a Circular Economy Context: A Case Study with Microalgae Integration.

Water pollution poses a global threat to ecosystems and human health and is driven by the presence of various contaminants in wastewater, including nano- and microplastics. Despite the magnitude of this problem, the majority of global wastewater is released untreated into water bodies. To combat this issue, a multi-strategy approach is needed. This study explores a circular economy-based solution for treating emerging pollutants, particularly wastewater from ophthalmic spectacle lens production. Our approach integrates solid waste materials into polymeric and cement matrices while also utilising wastewater for microalgae cultivation. This innovative strategy focuses on biomass generation and economic valorisation. By adopting a circular economy model, we aim to transform environmental pollutants from wastewater into valuable organic products. A key component of our approach is the utilisation of microalgae, specifically Nannochloropsis sp., known for its high lipid content and resilience. This microalgae species serves as a promising biobased feedstock, supporting the production of innovative biobased products, such as biopolymers, for ophthalmic lens manufacturing. Our interdisciplinary approach combines microalgae technology, analytical chemistry, cement production, and polymer processing to develop a sustainable circular economy model that not only addresses environmental concerns, but also offers economic benefits. This study underscores the potential of harnessing high-value products from waste streams and underscores the importance of circular economy principles in tackling pollution and resource challenges.

Evaluation of Technical and Economic Indicators for the Production Process of Microalgae Lipids Considering CO2 Capture of a Thermoelectric Plant and Use of Piggery Wastewater

Microalgae are highly studied microorganisms for the production of high-value products due to their high content of proteins, lipids, carbohydrates, and chlorophyll. These compounds are refined to obtain profitable industrial products. This article analyzes the lipid production of Chlorella sp. biomass, considering 18 scenarios for its production, with 9 of these being partially supplemented with swine wastewater. A 1 ha area was considered for biomass cultivation, primary and secondary biomass harvesting, and lipid extraction. Using simulation in the software SuperPro Designer v10, parameters such as CO2 capture (from a thermoelectric power plant), freshwater consumption, wastewater consumption, energy consumption, and unit production cost were evaluated. The results show that the production cost is high, ranging from 836.9 US $/kg to 1131.5 US $/kg of produced lipids, with a maximum CO2 capture of 454 kg of CO2/kg of lipids. The use of wastewater reduces the production cost by approximately 10%. The evaluation of technical and economic parameters allows us to identify bottlenecks and implement strategies to reduce production costs.

Characterization of the invasive macroalgae Rugulopteryx Okamurae for potential biomass valorisation

This study aimed to examine the composition and properties of the invasive macroalgae R. okamurae and explore potential applications. The results showed that the seaweed biomass is mainly composed of structural carbohydrates, with alginate being the main constituent, accounting for 32 % of its total composition and with a mannuronic and guluronic acid ratio (M/G) ratio of 0.93. It also has a relatively high concentration of fucose, related to the presence of fucoidans that have important biological functions. Among the mineral contents, a high magnesium and calcium (7107 and 5504 mg/kg) concentration, and the presence of heavy metals above legislated thresholds, were notable. R. okamurae also contained a high lipid content of 17 %, mainly composed of saturated fatty acids, but with a significant fraction of n3 polyunsaturated fatty acids (18 %) resulting in a low n6/n3 ratio (0.31), that has health benefits. The protein content of R. okamurae was 12 %, with high-quality proteins, as essential amino acids (mainly leucine, phenylalanine and valine) constitute 32 % of the total amino acids. It also showed a high polyphenol content and outstanding antioxidant properties (106.88 mg TE/g). Based on these findings, R. okamurae has significant potential as a sustainable source of bioactive compounds that can add value to different sectors, including food, feed, pharmaceuticals and cosmetics.

Effect of High Cell Density to Lipid Content Microalgae Chlorella vulgaris on Photoautotrophic Cultivation

Chlorella vulgaris is one of microalgae types that has essential ingredients beneficial tohumans, such as being a source of good lipid. Chlorella sp. have high lipid content, up to30%, under autotrophic conditions considered as a promising candidate for commercial lipidproduction due to its fast growth and easy cultivation. High cell density sedimentation can beinvestigated as a starving method in cultivation to make microalgae conditions less favorablein obtaining nutrient to lipid accumulation. Starving is one of the stress conditions carried outwith the aim of reducing nutrients in the microalgae cultivation process. The aim of this studywas to determine the effect of high cell density on increasing lipid content in Chlorellavulgaris. The results of this study showed that high cell density method affected theproductivity of Chlorella vulgaris biomass. The data obtained were analyzed using ANOVAα=0.05. The highest productivity and lipid content was obtained from the control sample witha biomass value of 0.36±0.03 g/l and a lipid content of 56.2±4.6% (P<0.05). The conclusionof this study is high cell density may not increase the production of lipid content fromChlorella vulgaris

Introducing of high rich lysine, arginine, and unsaturated fatty acids microalga as a food supplement.

Microalgae are powerful source for nutritionally valuable components as proteins, carbohydrates and especially unsaturated fatty acids. Microalgae may be employed in pharmaceutical, food, cosmetic, health industries, and biofuels. In this study for looking at high-level unsaturated fatty acids species, from 31 strains, by comparing growth curves, the best strain with a high growth rate and lipid content was selected by red Nile staining. It was determined by molecular identification that this strain belongs to the genus Chlorella sp. and is deposited into the Agricultural Biotechnology Research Institute of Iran Culture collection with culture collection number ABRIICC 30,041. Biomass analysis after growth optimization by response surface methodology showed that the selected strain had a specific growth rate of 0.216 ± 0.008 d-1, biomass productivity of 142.58 ± 4.41mg/Ld, and lipid content of 13.9 ± 0.26% with a high level of unsaturated fatty acids of 53.15%. It also included 51.3 ± 0.53% protein with a very high quality essential amino acids of 40.36%, the most lysine (8.77%) and arginine (13.31%) has been reported until now, and 26.9 ± 0.23% carbohydrates in photoautotroph condition. By MTT assay, there is no effect of cytotoxicity. This research introduces a potent native strain comparable with commercial strains that can be a hopeful source for food supplements and valuable bioactive ingredients in functional foods.

Development of a novel Fe@urea nanocomposite for effective harvesting of high lutein-producing microalgae biomass

An Innovative microalgae biomass harvesting is addressed through a newly developed Fe@urea nanocomposite (NC) with high lutein and lipid content. The persistent challenge of scaling up microalgae harvesting for large-scale commercial production is undertaken by coating Fe3O4 nanoparticles (NPs) with urea, significantly enhancing biomass harvesting efficiency. This improvement aligns with increased NH2+ groups on the NC's surface, demonstrating superior performance compared to conventional Fe3O4 NPs, especially at pH 4. Characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and zeta potential analysis validate the efficacy of the Fe@urea NC. The elemental composition was analyzed through energy-dispersive X-ray spectroscopy (EDX) to confirm effective urea coating on the NC surface. Remarkably, enhanced Fe@urea-mediated harvesting within one minute is achieved through NH2+-assisted interactions. Optimization experiments varying NC concentrations and culture pH, guided by the Langmuir model, showcase the NC's multifaceted solution, excelling under a magnetic field and also via self-flocculation. Cell viability tests confirm lutein-enriched microalgae cell integrity during harvesting at pH 4, preventing product leaching. This synthesized Fe@urea NC presents an efficient and viable method for microalgae harvesting, holding promising implications for large-scale microalgae biorefinery applications.

Lipid Enhancement in Oleaginous Nannochloropsis sp. under Nitrate Limitation for Future Bioenergy Production

Microalgae possess high oil content, exhibit rapid growth rates and biomass productivity, and leave a minimal environmental footprint, making them highly attractive for biofuel applications. Consequently, this present study is aimed at evaluating the impact of nitrogen starvation on the marine microalgae Nannochloropsis sp. to enhance lipid accumulation. The microalga culture was grown under an irradiance of 120 μmol photon m-2 s-1, temperature 25 ± 1 °C, continuous air-CO2, and with different concentrations of sodium nitrites over a 14-day cultivation period. From the results, it was found that the growth of the strain decreased under limited nitrogen conditions. After harvesting, the cells in the supernatant were regenerated by cultivating in double concentration of media. The results showed that on the 12th day, the highest lipid content was achieved, reaching 68.0 ± 2.3 wt.% of the dry weight under nitrogen limitation. The composition of the obtained lipid consisted of 18.0 wt.% saturated fatty acids, 72.38 wt.% monounsaturated fatty acids, and 8.95 wt.% polyunsaturated fatty acids. The lipid composition was dominated by monounsaturated oleic acid ( 70.97 ± 4.6 wt.%), saturated palmitic acid ( 13.68 ± 1.0 wt.%), and polyunsaturated linoleic acid ( 8.41 ± 0.4 wt.%). The findings of this study demonstrated that limiting nitrogen availability enhanced lipid accumulation in Nannochloropsis sp. Despite experiencing inhibited growth, this microalga species shows great potential for the large-scale cultivation of lipids and essential fatty acids. These results contribute to understanding the relationship between nitrogen availability and lipid metabolism in microalgae, providing valuable insights for optimizing lipid production in the context of biofuel and biotechnology applications.

Biomolecular Corona of Gold Nanoparticles: The Urgent Need for Strong Roots to Grow Strong Branches.

Gold nanoparticles (GNPs) are largely employed in diagnostics/biosensors and are among the most investigated nanomaterials in biology/medicine. However, few GNP-based nanoformulations have received FDA approval to date, and promising in vitro studies have failed to translate to in vivo efficacy. One key factor is that biological fluids contain high concentrations of proteins, lipids, sugars, and metabolites, which can adsorb/interact with the GNP's surface, forming a layer called biomolecular corona (BMC). The BMC can mask prepared functionalities and target moieties, creating new surface chemistry and determining GNPs' biological fate. Here, the current knowledge is summarized on GNP-BMCs, analyzing the factors driving these interactions and the biological consequences. A partial fingerprint of GNP-BMC analyzing common patterns of composition in the literature is extrapolated. However, a red flag is also risen concerning the current lack of data availability and regulated form of knowledge on BMC. Nanomedicine is still in its infancy, and relying on recently developed analytical and informatic tools offers an unprecedented opportunity to make a leap forward. However, a restart through robust shared protocols and data sharing is necessary to obtain "stronger roots". This will create a path to exploiting BMC for human benefit, promoting the clinical translation of biomedical nanotools.

Growth strategies of Chlorella vulgaris in seawater for a high production of biomass and lipids suitable for biodiesel

Chlorella vulgaris is a freshwater microalga that synthesises large amounts of saturated lipids, which makes it suitable for production of bioenergy and biofuels. Since its cultivation usually requires freshwater, it competes with agriculture, economic development and ecological conservation for this limited natural resource. This study investigated the possibility of the partial replacement of freshwater by seawater (50 %) in the growth medium for a more sustainable biomass and lipid production. Chlorella vulgaris 211-11b was cultivated as shake-flask cultures in Bold's Basal Medium (BBM) formulated with 50 % freshwater and 50 % seawater under photoautotrophic, mixotrophic and heterotrophic conditions for eight days with glucose as organic carbon source in the latter two cases. The alga's best growth performance and highest lipid contents (49 % DW−1), dominated by palmitioleic and oleic acid, occurred under mixotrophic rather than photoautotrophic and heterotrophic conditions. This study demonstrates a more economic and ecologically sustainable biomass and lipid production of C. vulgaris by saving 50 % freshwater, which is available for other purposes.

Climate change-informed dietary modeling in Pacific cod: Experimentally-derived effects of temperature and dietary quality on carbon and nitrogen stable isotope trophic discrimination factors

Stable isotope analysis is a powerful tool for dietary modeling and trophic ecology research. A crucial piece of information for isotopic dietary modeling is the accurate estimation of trophic discrimination factors (TDFs), or the isotopic offset between a consumer’s tissue and its diet. In order to parameterize stable isotope dietary models for future climate scenarios, we investigated the effect of water temperature and dietary protein and lipid content on TDFs in juvenile Pacific cod (Gadus macrocephalus). Pacific cod are a commercially and ecologically important species, with stock numbers in the northeast Pacific recently having dropped by more than 70%. We tested four water temperatures (6, 8, 10, and 12°C) and two dietary regimens (low and high lipid content), representing a range of potential ocean temperature and prey quality scenarios, in order to determine carbon and nitrogen TDFs in juvenile Pacific cod. Additionally, we assessed dietary intake and proximate composition of the experimental fish in order to estimate consumption, assimilation, and retention of dietary nutrients. The results of this study suggest that dietary protein catabolism is a primary driver of nitrogen TDF variability in juvenile Pacific cod. Across all temperature treatments from 6 to 12°C, fish reared on the lower quality, lower lipid content diet had higher nitrogen TDFs. The mean TDFs for fish raised on the higher lipid, lower protein diet were +3.40 ‰ for nitrogen (Δ15N) and +0.36 ‰ for lipid-corrected carbon (Δ LC 13C). The mean TDFs for fish raised on the lower lipid, higher protein diet were +4.09 ‰ for nitrogen (Δ15N) and 0.00 ‰ for lipid-corrected carbon (Δ LC 13C). Lipid-corrected carbon isotope data showed that, regardless of temperature, fish consuming the lower lipid diet had essentially no trophic discrimination between diet and bulk tissues. We found no ecologically meaningful differences in TDFs due to water temperature across the 6°experimental range. The results of this experiment demonstrate that dietary quality, and more specifically the use of dietary protein for energetic needs, is a primary driver of trophic discrimination factors. The TDFs determined in this study can be applied to understanding trophic ecology in Pacific cod and closely related species under rapidly changing prey availability and ocean temperature conditions.

Insight into the mechanism of nitrogen sufficiency conversion strategy for microalgae-based ammonium-rich wastewater treatment

The strategy of nitrogen sufficiency conversion can improve ammonium nitrogen (NH4+-N) removal with microalgal cells from ammonium-rich wastewater. We selected and identified one promising isolated algal strain, NCU-7, Chlorella sorokiniana, which showed a high algal yield and tolerance to ammonium in wastewater, as well as strong adaptability to N deprivation. The transition from N deprivation through mixotrophy (DN, M) to N sufficiency through autotrophy (SN, P) achieved the highest algal yields (optical density = 1.18 and 1.59) and NH4+-N removal rates (2.5 and 4.2 mg L−1 d−1) from synthetic wastewaters at two NH4+-N concentrations (160 and 320 mg L−1, respectively). Algal cells in DN, M culture obtained the lowest protein content (20.6%) but the highest lipid content (34.0%) among all cultures at the end of the stage 2. After transferring to stage 3, the lowest protein content gradually recovered to almost the same level as SN, P culture on the final day. Transmission electron microscopy and proteomics analysis demonstrated that algal cells had reduced intracellular protein content but accumulated lipids under N deprivation by regulating the reduction in synthesis of protein, carbohydrate, and chloroplast, while enhancing lipid synthesis. After transferring to N sufficiency, algal cells accelerated their growth by recovering protein synthesis, leading to excessive uptake of NH4+-N from wastewater. This study provides specific insights into a nitrogen sufficiency conversion strategy to enhance algal growth and NH4+-N removal/uptake during microalgae-based ammonium-rich wastewater treatment.