Proteomics reveals toxin tolerance and polysaccharide accumulation in Chlorococcum humicola under high CO2 concentration.

Algae have great application prospects in excess sludge reclamation and recovery of high-value biomass. Chlorococcum humicola was cultivated in this research, using sludge extract (mixed with SE medium) with additions of 10%, 20%, and 30% CO2 (v/v). Results showed that under 20% CO2, the dry weight and polysaccharide yield reached 1.389 ± 0.070 g/L and 313.49 ± 10.77 mg/L, respectively. 10% and 20% CO2 promoted the production of cellular antioxidant molecules to resist the toxic stress and the toxicity of 20% CO2 group decreased from 62.16 ± 3.11% to 33.02 ± 3.76%. 10% and 20% CO2 accelerated the electron transfer, enhanced carbon assimilation, and promoted the photosynthetic efficiency, while 30% CO2 led to photosystem damage and disorder of antioxidant system. Proteomic analysis showed that 20% CO2 mainly affected energy metabolism and the oxidative stress level on the early stage (10 d), while affected photosynthesis and organic substance metabolism on the stable stage (30 d). The up-regulation of PSII photosynthetic protein subunit 8 (PsbA, PsbO), A0A383W1S5 and A0A383VRI4 promoted the efficiency of PSII and chlorophyll synthesis, and the up-regulation of A0A383WH74 and A0A2Z4THB7 led to the accumulation of polysaccharides. The up-regulation of A0A383VDH1, A0A383VX37 and A0A383VA86 promoted respiration. Collectively, this work discloses the regulatory mechanism of high-concentration CO2 on Chlorococcum humicola to overcome toxicity and accumulate polysaccharides.

Mining phase separation-related diagnostic biomarkers for endometriosis through WGCNA and multiple machine learning techniques: a retrospective and nomogram study.

OBJECTIVE: The objective of this study was to investigate the role of phase separation-related genes in the development of endometriosis (EMs) and to identify potential characteristic genes associated with the condition. METHODS: We used GEO database data, including 74 non-endometriosis and 74 varying-degree EMs patients. Our approach involved identifying significant gene modules, exploring gene intersections, identifying core genes, and screening for potential EMs biomarkers using weighted gene co-expression network analysis (WGCNA) and various machine learning approaches. We also performed gene set enrichment analysis (GSEA) to understand relevant pathways. This comprehensive approach helps investigate EMs genetics and potential biomarkers. RESULTS: Nine genes were identified at the intersection, suggesting their involvement in EMs. GSEA linked DEGs to pathways like complement and coagulation cascades, DNA replication, chemokines, apical plasma membrane processes, and diseases such as Hepatitis B, Human T-cell leukemia virus 1 infection, and COVID-19. Five feature genes (FOS, CFD, CCNA1, CA4, CST1) were selected by machine learning for an effective EMs diagnostic nomogram. GSEA indicated their roles in mismatch repair, cell cycle regulation, complement and coagulation cascades, and IL-17 inflammation. Notable differences in immune cell proportions (CD4 T cells, CD8 T cells, DCs, macrophages) were observed between normal and disease groups, suggesting immune involvement. CONCLUSIONS: This study suggests the potential involvement of phase separation-related genes in the pathogenesis of endometriosis (EMs) and identifies promising biomarkers for diagnosis. These findings have implications for further research and the development of new therapeutic strategies for EMs.

Improvement of coal gasification reverse osmosis concentrate treatment by Cu-Co-Mn/AC catalytic ozonation.

Approximately 20% of concentrate will be produced from coal gasification wastewater after reverse osmosis treatment. The organic matter contained in the concentrate affects its evaporation crystallisation; therefore, the refractory organics must be removed. In this study, Cu-Co-Mn/AC catalytic ozonation was used to treat reverse osmosis concentrate (ROC). With the addition of the Cu-Co-Mn/AC catalyst, the production of ·OH increased by 82 µmol/L, thereby enhancing the ozonation performance. The pH, ozone dosage, and catalyst dosage all affected the catalytic ozonation performance. By constructing a response surface model, it was found that the catalyst dosage had the most significant effect on the catalytic ozonation performance. The predicted optimal reaction conditions were pH = 9.02, ozone dosage = 1.08 g/L, and catalyst dosage = 1.33 g/L, under which the chemical oxygen demand (COD) removal reached a maximum of 81.49%.

Self-regulation mechanism difference of Chlorella vulgaris and Scenedesmus obliquus in toxic sludge extract caused by hydroquinone biodegradation.

Chlorella vulgaris (C. vulgaris) and Scenedesmus obliquus (S. obliquus) were compared to remove toxicity under conditions of sludge extract cultivation for 30 days. The toxicity of sludge extract, the growth characteristics, photosynthetic pigment, superoxide dismutase (SOD) enzyme and catalase (CAT) enzyme activities of the two microalgae were studied by contrast. The results showed that small molecular organic matter (<500 Da) was more easily utilized by microalgae. The toxicity in the toxic group of C. vulgaris and S. obliquus on the 30th day decreased to 56.8 ± 1.2% and 60.7 ± 2.8%, respectively. In the toxic group, the maximal SOD enzyme activity of C. vulgaris and S. obliquus were 2.02 U/mg proteins and 8.21 U/mg proteins, respectively, demonstrating that toxicity caused more oxidative damage to S. obliquus than to C. vulgaris. Proteomics analysis revealed that C. vulgaris mainly regulates energy synthesis and distribution primarily through sugar metabolism, and biomass synthesis primarily through carbon metabolism, whereas S. obliquus mainly regulates energy synthesis and distribution primarily through sugar metabolism and oxidative phosphorylation, resulting in sludge toxicity stress regulation.

Study on the differences in sludge toxicity and microbial community structure caused by catechol, resorcinol and hydroquinone with metagenomic analysis.

The aerobic biodegradation rate, organic toxicity and microbial community structure of activated sludge acclimated by catechol, resorcinol and hydroquinone were investigated, to study the relationship between microbial structure and sludge organic toxicity caused by phenolic compounds. At the stable operation stage, the degradation rates of the dihydroxy benzenes in a single sequencing batch reactor (SBR) cycle were followed the order: resorcinol (89.71%) > hydroquinone (85.64%) > catechol (59.62%). Sludge toxicity bioassay indicated that the toxicity of sludge was catechol (45.63%) > hydroquinone (40.28%) > resorcinol (38.15%). The accumulation of secondary metabolites such as 5-10 kDa tryptophan and tyrosine protein substances caused the differential sludge toxicity. Microbial metagenomic analysis showed that the toxicity of sludge was significantly related to the microbial community structure. Thauera, Azoarcus, Pseudomonas and other Proteobacteria formed in the sludge during acclimation. Catechol group had the least dominant bacteria and loop ring opening enzyme genes (catA, dmpB, dxnF, hapD) numbers. Therefore, the degradation of catechol was the most difficult than resorcinol and hydroquinone, resulting the highest sludge toxicity.

Cultivation of energy microalga Chlorella vulgaris with low-toxic sludge extract.

Chlorella vulgaris was cultivated in different proportions of activated sludge extracts, which was from the treatment of synthetic wastewater containing tetrachlorophenol. The growth period of C. vulgaris could be shortened for about 10 days when sludge extract was mixed into BG11 culture substrate, and the growth of C. vulgaris was promoted during the period of adaptation and logarithmic period. In the stable and decay period, when the proportion of sludge extract increased to 50%, cell proliferation was inhibited. There was an evident positive correlation between the total and average amount of starch polysaccharide with sludge concentration. When C. vulgaris was cultivated with pure sludge extracts, the total amount of starch and polysaccharide was up to 103 and 125 mg/L. Therefore, the low-toxic sludge extracts were more beneficial to the accumulation of carbohydrates. In the 100% sludge extracts culture medium, chlorophyll-a in C. vulgaris was accumulated to 30.2 mg/L on the 25th day. Through the analysis of algal cells' ultrastructures, it was shown that the photosynthesis was strengthened greatly with low-toxic sludge extracts. The results show that the rich heterotrophic carbon source in the sludge extract can be used as an excellent medium for Chlorella. It provides new ideas for the harmless utilization of surplus sludge as a resource. At the same time, the use of nutrients in the sludge extract to cultivate Chlorella is of great significance to low-cost algae cultivation.

Comparison of nitrogen removal efficiency and microbial characteristics of modified two-stage A/O, A2/O and SBR processes.

The low temperature of sewage in north China results in low performance of biological treatment at municipal wastewater treatment plants (MWTPs), especially in biological nitrogen removal. A modified two-stage A/O process with an embedded biofilm was proposed to enhance nitrogen removal. The operation performance of a pilot test was compared with an A2/O and SBR process at existing MWTPs to investigate the resistance to low temperature. The microbial communities for the three processes were compared based on the metagenomics results of 16sDNA high-throughput sequencing from activated sludge. The modified A/O resulted in a higher average removal of COD (90.12%) than A2/O (85.23%) and SBR (83.03%), especially of small-molecule organic compounds (< 500 Da) and macromolecular refractory organics (> 5 k Da); the TN removal rate of A2/O, SBR and the modified A/O was also increased from 74.47%, 70.63% and 78.46%, respectively. High-throughput sequencing revealed increased microbial diversity and an abundance of denitrifying functional bacteria was observed in the modified A/O process at low temperatures. The abundance of nitrite oxidation bacteria (NOB) including Nitrosomonas and Nitrospira, the amount was 1.76% and 2.34% in modified A/O, respectively, whereas NOB only accounted for 1.82% in A2/O and 1.35% in SBR.

Deciphering and Suppressing Over-Oxidized Nitrogen in Nickel-Catalyzed Urea Electrolysis.

Urea electrolysis is a prospective technology for simultaneous H2 production and nitrogen suppression in the process of water being used for energy production. Its sustainability is currently founded on innocuous N2 products; however, we discovered that prevalent nickel-based catalysts could generally over-oxidize urea into NO2 - products with ≈80 % Faradaic efficiencies, posing potential secondary hazards to the environment. Trace amounts of over-oxidized NO3 - and N2 O were also detected. Using 15 N isotopes and urea analogues, we derived a nitrogen-fate network involving a NO2 - -formation pathway via OH- -assisted C-N cleavage and two N2 -formation pathways via intra- and intermolecular coupling. DFT calculations confirmed that C-N cleavage is energetically more favorable. Inspired by the mechanism, a polyaniline-coating strategy was developed to locally enrich urea for increasing N2 production by a factor of two. These findings provide complementary insights into the nitrogen fate in water-energy nexus systems.

Correlation between the uncoupling metabolism induced by 2,4,6-trichlorophenol and sludge toxicity in sequence batch reactors.

The correlation between sludge reduction induced by 2,4,6-trichlorophenol (2,4,6-TCP) as an uncoupler and sludge toxicity was investigated in sequence batch reactors over a 100-d operation period. The influent concentrations of 2,4,6-TCP tested were 10 mg/L, 30 mg/L, and 50 mg/L. Sludge reduction, chemical oxygen demand (COD) removal rate, and sludge toxicity were measured. The results showed that from 30 to 80 d, when the COD removal rate was at an acceptable level, the sludge reduction levels for the 10 mg/L, 30 mg/L, and 50 mg/L groups were 9.7%, 31.6%, and 41.5%, respectively, and the average sludge toxicity values were 24.2%, 38.0%, and 53.0%, respectively. Sludge reduction was positively correlated with sludge toxicity. The two-dimensional polyacrylamide gel electrophoresis/results showed that extracellular and intracellular proteins secreted by the activated sludge during uncoupling metabolism were positively correlated with sludge toxicity. Taking the COD removal rate, sludge reduction, and sludge toxicity into consideration, the optimal influent concentration of the uncoupler 2,4,6-TCP was 30 mg/L when the initial mixed liquid suspended solids of sludge was 2,500 mg/L.

Two-stage coagulation process for enhanced oil removal from coal chemical wastewater.

As a common pretreatment process for coal chemical wastewater, the conventional one-stage coagulation process has the problem of poor removal of small size oil, which will inhibit the subsequent biological treatment. Measures to improve oil removal efficiency based on the development of new coagulants and the addition of composite processes are common in the literature, but two-stage coagulation to improve coagulation efficiency has not been reported to date. Here, we optimized coagulation parameters and compared the oil removal efficiency of two-stage coagulation and one-stage coagulation. Under the same total dosage of coagulant (PAC), the optimum removal of oil in two-stage coagulation was achieved 90% which increased by 11% compared to one-stage process. P10 and P 1 µm were proposed to evaluate the oil removing effect of two-stage coagulation. In addition, SEM scanning was used to conduct flocs analysis and two-stage coagulation process simulation, revealing the principle of the excellent oil removal performance of two-stage coagulation. Finally, coagulant in filter residue was recovered by acidification method and the recovered coagulant was used again in the two-stage coagulation process of coal chemical wastewater. These results suggest that two-stage coagulation is a cost-effective alternative oil removal technique with high energy efficiency and environmental benign. This research may offer helpful insights to develop an advanced oil removal process.

Two-stage air stripping combined with hydrolysis acidification process for coal gasification wastewater pretreatment.

Coal gasification wastewater is mainly from gas washing, condensation and purification processes in the gas furnace with high NH3-N (nitrogen in water in the form of free ammonia (NH3) and ammonium ion (NH4 +)), TN (total nitrogen) and refractory organics content, which will inhibit the subsequent biological treatment. The 'air stripping - hydrolysis acidification - air stripping' process was proposed as the pretreatment for coal gasification wastewater to improve the biodegradability and nitrogen removal, which could reduce the subsequent biological treatment load. The first-stage air stripping process before hydrolysis acidification could achieve a significant removal of NH3-N (97.0%) and volatile phenol (70.0%), reducing the corresponding toxicity on hydrolysis acidification. The group with air stripping had more abundant microbial communities and a more effective organic degradation performance in hydrolysis acidification than that without air stripping. The second-stage air stripping removed NH3-N released from hydrolysis acidification, and significantly reduced the TN concentration in effluent. The whole process achieved a TN removal from 2,000 ± 100 mg/L to 160 ± 80 mg/L, and a total phenols removal from 700 ± 50 mg/L to 80 ±20 mg/L.

Chlorella vulgaris cultivation in sludge extracts from 2,4,6-TCP wastewater treatment for toxicity removal and utilization.

Chlorella vulgaris was cultivated in different proportions of activated sludge extracts, which was from the treatment of the synthetic wastewater containing 2,4,6-trichlorophenol (2,4,6-TCP). The nutrients, total nitrogen (TN) and total phosphorus (TP), were removed over 45% and 90%, respectively. The maximum reduction amount of ecotoxicity and total organic carbon (TOC) occurred in the 100% sludge group on the 8th day (68%; 86.2 mg L-1). The variations of Excitation-emission matrix spectra (EEMs) and TOC indicated that extracellular organic matters (EOM) produced by algae led to TOC increase in the medium. The cell density was close to each other for groups with sludge extract proportion below 50%; sludge extracts (below 75% addition) had a stimulating effect on the accumulation of chlorophyll-a in per unit algal cell. Superoxide dismutase (SOD) variation demonstrated that C. vulgaris response positively to sludge extracts addition. Lipid content in C. vulgaris was up to its maximum value on the 8th day. Considering the performance on nutrients removal, toxicity reduction and algal growth, the optimal cultivation period for C. vulgaris before harvesting was around 8 days with sludge extracts proportion below 50%.

Incidence of retinopathy of prematurity in southwestern China and analysis of risk factors.

BACKGROUND: The aim of this study was to screen for retinopathy of prematurity (ROP) in southwestern China and understand the prevalence and risk factors of ROP, which may provide evidence useful in the prevention and treatment of ROP. MATERIAL/METHODS: 1864 preterm infants (gestational age of <37 weeks and birth weight of ≤2500 g) underwent ROP screening from January 2009 to November 2012 in Southwest China. The medical information of infants during perinatal period was reviewed, and risk factors of ROP were determined. A total of 1614 infants were recruited for final analysis. RESULTS: Incidence of ROP was 12.8%. The first, second, third, and fourth stage of ROP was found in 64.6%, 29.6%, 3.4%, and 0.5% of infants, respectively. No fifth stage of ROP was observed. In addition, 7.7% of infants required surgical intervention. In our Department of Neonatology, the incidence of ROP was 20.0%, which was significantly higher than in non-hospitalized patients (9.9%). The incidence of ROP remained unchanged over the years. Independent risk factors of ROP included low birth weight (p=0.049), low gestational age (p=0.008), days of oxygen supplementation (p=0.008), and myocardial injury after birth (p=0.001). CONCLUSIONS: The prevalence of ROP in preterm infants is relatively high in Southwest China, and low birth weight, low gestational age, days of oxygen supplementation, and myocardial injury after birth are independent risk factors for ROP.

Successful startup of a full-scale acrylonitrile wastewater biological treatment plant (ACN-WWTP) by eliminating the inhibitory effects of toxic compounds on nitrification.

During the startup of a full-scale anoxic/aerobic (A/O) biological treatment plant for acrylonitrile wastewater, the removal efficiencies of NH(3)-N and total Kjeldahl nitrogen (TKN) were 1.29 and 0.83% on day 30, respectively. The nitrification process was almost totally inhibited, which was mainly caused by the inhibitory effects of toxic compounds. To eliminate the inhibition, cultivating the bacteria that degrade toxic compounds with patience was applied into the second startup of the biological treatment plant. After 75 days of startup, the inhibitory effects of the toxic compounds on nitrification were eliminated. The treatment plant has been operated stably for more than 3 years. During the last 100 days, the influent concentrations of chemical oxygen demand (COD), NH(3)-N, TKN and total cyanide (TCN) were 831-2,164, 188-516, 306-542 and 1.17-9.57 mg L(-1) respectively, and the effluent concentrations were 257 ± 30.9, 3.30 ± 1.10, 31.6 ± 4.49 and 0.40 ± 0.10 mg L(-1) (n = 100), respectively. Four strains of cyanide-degrading bacteria which were able to grow with cyanide as the sole carbon and nitrogen source were isolated from the full-scale biological treatment plant. They were short and rod-shaped under scanning electron microscopy (SEM) and were identified as Brevundimonas sp., Rhizobium sp., Dietzia natronolimnaea and Microbacterium sp., respectively.

A control strategy for promoting the stability of denitrifying granular sludge in upflow sludge blankets.

The nitrate removal rate of denitrifying granular sludge in an upflow sludge blanket reactor is very high and reaches up to 3.6 gNO3-N-gVSS-1 d-1 at a nitrate loading rate (NLR) of 32.0 gNO3-N L-1 d-1. However, the granular sludge exhibits flotation under high NLR conditions, where the granules become large in size (of approximately 3-5 mm), light, and easily adhere to gas bubbles. In order to decrease the flotation potentiality of granular sludge, three measures were taken as follows: reducing the size of the granules, increasing the density of the granules, and weakening the adhesion effect of sludge to bubbles. While, these measures did not completely eliminate the granular sludge flotation. The way to solve sludge flotation namely instability was to slow down the biomass growth rate. The main factors to reduce denitrifying bacteria growth rate were verified as relatively low operating temperature, carbon source with comparatively slow degradation rate, and low NLR. Therefore, controlling denitrifying biomass growth rate via reducing temperature, replacing methanol with glucose as carbon source, and decreasing NLR was able to improve the stability of the granular sludge.

Bisphenols in Aquatic Products from South China: Implications for Human Exposure.

In this study, 245 representative samples of aquatic products were selected from local markets in Shenzhen by stochastic sampling. The samples comprised eight species and fell into three aquatic product categories: fish, crustaceans, and bivalves. A total of eight BPs were determined by liquid chromatography coupled with mass spectrometry, namely, bisphenol A (BPA), bisphenol AF (BPAF), bisphenol AP (BPAP), bisphenol B (BPB), bisphenol S (BPS), bisphenol P (BPP), bisphenol Z (BPZ), and bisphenol F (BPF). All BPs were detected in aquatic products, except for BPAF, indicating pervasive contamination by BPs in aquatic products. BPS demonstrated the highest detection rate both before and after enzymatic hydrolysis, whereas BPAP exhibited the lowest detection rate before enzymatic hydrolysis and BPB displayed the lowest detection rate after enzymatic hydrolysis. The concentration difference before and after enzymatic hydrolysis proved to be statistically significant. Moreover, 49-96% of BPs in aquatic products were found in the combined state, underscoring the essentiality of conducting detections on aquatic product samples following enzymatic hydrolysis. While the health risks associated with ingesting BPs residues through aquatic product consumption were found to be minimal for residents at risk of exposure, the results suggest the necessity for more stringent regulations governing the consumption of aquatic products.

Excessive composite pollution carbon sources enhance the bio-fertilizer efficiency of Tetradesmus obliquus: focused on cultivation period.

Microalgae can use carbon sources in sludge extract prepared from sludge. Moreover, the high concentration of CO2 and the large number of carbon sources in the liquid phase will promote microalgae growth and metabolism. In this experiment, Tetradesmus obliquus was cultivated with sludge extract at 30% CO2. Algae liquid (the name used to describe the fertilizer made in this research) was further prepared as lettuce fertilizer. The effect of different times of microalgae culture (10, 15, 20, 25, and 30 days) on the fertilizer efficiency of the algae liquid was evaluated by lettuce hydroponic experiments. The findings indicate that lettuce cultivated in algae liquid collected on the 15th and 30th days exhibited superior performance in terms of growth, antioxidant capacity, and nutritional quality. We analyzed the experimental results in the context of microalgae metabolic mechanisms, aiming to contribute experience and data essential for the development of industrial microalgae fertilizer production.

Discovering and Validating Cuproptosis-Associated Marker Genes for Accurate Keloid Diagnosis Through Multiple Machine Learning Models.

Background: Keloid is a common condition characterized by abnormal scarring of the skin, affecting a significant number of individuals worldwide. Objective: The occurrence of keloids may be related to the reduction of cell death. Recently, a new cell death mode that relies on copper ions has been discovered. This study aimed to identify novel cuproptosis-related genes that are associated with keloid diagnosis. Methods: We utilized several gene expression datasets, including GSE44270 and GSE145725 as the training group, and GSE7890, GSE92566, and GSE121618 as the testing group. We integrated machine learning models (SVM, RF, GLM, and XGB) to identify 10 cuproptosis-related genes (CRGs) for keloid diagnosis in the training group. The diagnostic capability of the identified CRGs was validated using independent datasets, RT-qPCR, Western blotting, and IHC analysis. Results: Our study successfully categorized keloid samples into two clusters based on the expression of cuproptosis-related genes. Utilizing WGCNA analysis, we identified 110 candidate genes associated with cuproptosis. Subsequent functional enrichment analysis results revealed that these genes may play a regulatory role in cell growth within keloid tissue through the MAPK pathway. By integrating machine learning models, we identified CRGs that can be used for diagnosing keloid. The diagnostic efficacy of CRGs was confirmed using independent datasets, RT-qPCR, Western blotting, and IHC analysis. GSVA analysis indicated that high expression of CRGs influenced the gene set related to ECM receptor interaction. Conclusion: This study identified 10 cuproptosis-related genes that provide insights into the molecular mechanisms underlying keloid development and may have implications for the development of targeted therapies.

The efficient capture of polysaccharides in Tetradesmus obliquus of indole-3-acetic acid coupling sludge extraction.

Polysaccharide is an important biomass of algae. The sludge extract is rich in organic substances, which can be used by algae for biomass growth and high-value biomass synthesis, but its organic toxicity has an inhibitory effect on algae. To overcome inhibition and improve polysaccharide enrichment, Tetradesmus obliquus was cultured with sludge extract with different indole-3-acetic acid (IAA) concentrations. Within 30 days of the culture cycle, T. obliquus showed in good condition at the IAA dosage content of 10-6 M, the maximum cell density and dry weight were respectively (106.78 ± 2.20) × 106 cell/mL and 2.941 ± 0.067 g/L while the contents of chlorophyll-a, chlorophyll-b, and carotenoid were 1.79, 1.91 and 2.80 times that of the blank group, respectively. The highest polysaccharide accumulation was obtained under this culture condition, reaching 533.15 ± 21.11 mg/L on the 30th day, which was 2.49 times that in the blank group. By FT-IR and NMR analysis, it was found that the polysaccharides of T. obliquus were sulfated polysaccharide with glucose and rhamnose as the main monosaccharides. Proteomic showed that the up-regulation of A0A383WL26 and A0A383WLM8 enhanced the light trapping ability, and A0A383WMJ2 enhanced the accumulation of NADPH. The up-regulation of A0A383WHD5 and A0A383WAY6 indicated that IAA culture could repair the damage caused by sludge toxicity, thus promoting the accumulation of biomass. The above findings provided new insights into the mechanism of sludge toxicity removal of T. obliquus and the enhancement of the polysaccharide accumulation effect under different concentrations of IAA.

Analysis of the regulatory mechanism of exogenous IAA-mediated tryptophan accumulation and synthesis of endogenous IAA in Chlorococcum humicola.

The activated sludge method is widely used for the treatment of phenol-containing wastewater, which gives rise to the problem of toxic residual sludge accumulation. Indole-3-acetic acid (IAA), a typical phytohormone, facilitates the microalgal resistance to toxic inhibition while promoting biomass accumulation. In this study, Chlorococcum humicola (C. humicola) was cultured in toxic sludge extract and different concentrations of IAA were used to regulate its physiological properties and enrichment of high value-added products. Ultimately, proteomics analysis was used to reveal the response mechanism of C. humicola to exogenous IAA. The results showed that the IAA concentration of 5 × 10-6 mol/L (M) was most beneficial for C. humicola to cope with the toxic stress in the sludge extract medium, to promote the activity of rubisco enzyme, to enhance the efficiency of photosynthesis, and, finally, to accumulate protein as a percentage of specific dry weight 1.57 times more than that of the control group. Exogenous IAA altered the relative abundance of various amino acids in C. humicola cells, and proteomic analyses showed that exogenous IAA stimulated the algal cells to produce more indole-3-glycerol phosphate (IGP), indole, and serine by up-regulating the enzymes. These precursors are converted to tryptophan under the regulation of tryptophan synthase (A0A383V983), and tryptophan can be metabolized to endogenous IAA to promote the growth of C. humicola. These findings have important implications for the treatment of toxic residual sludge while enriching for high-value amino acids.