Carbon chain elongation characterizations of electrode-biofilm microbes in electro-fermentation.

The higher efficiency of electro-fermentation in synthesizing medium-chain fatty acids (MCFAs) compared to traditional fermentation has been acknowledged. However, the functional mechanisms of electrode-biofilm enhancing MCFAs synthesis remain research gaps. To address this, this study proposed a continuous flow electrode-biofilm reactor for chain elongation (CE). After 225 days of operation, stable electrode-biofilms formed and notably improved caproate yield by more than 38 %. The electrode-biofilm was enriched with more CE microorganisms and electroactive bacteria compared to the suspended sludge microorganisms, including Caproicibacterium, Oscillibacter and Pseudoramibacter. Besides, the upregulated CE pathways were evaluated by metagenomic analysis, and the results indicated that the pathways such as acetyl-CoA and malonyl-[acp] formation, reverse beta-oxidation, and fatty acid biosynthesis pathway were all markedly enhanced in cathodic biofilm, more than anodic biofilm and suspended microorganisms. Moreover, microbial community regulated processes like bacterial chemotaxis, flagellar assembly and quorum sensing, crucial for electrode-biofilm formation. Electron transfer, energy metabolism, and microbial interactions were found to be prominently upregulated in the cathodic biofilm, surpassing levels observed in anodic biofilm and suspended sludge microorganisms, which further enhanced CE efficiency. In addition, the statistical analyses further highlighted key microbial functions and interactions within the cathodic biofilm. Oscillospiraceae_bacterium was identified to be the most active microbe, alongside pivotal roles played by Caproiciproducens_sp._NJN-50, Clostridiales_bacterium, Prevotella_sp. and Pseudoclavibacter_caeni. Eventually, the proposed microbial collaboration mechanisms of cathodic biofilm were ascertained. Overall, this study uncovered the biological effects of the electrode-biofilm on MCFAs electrosynthesis, thereby advancing biochemicals production and filling the knowledge gaps in CE electroactive biofilm reactors.

Outstanding enhancement of caproate production with microwave pyrolyzed highly reductive biochar addition.

The integration of biochar into microbial Chain Elongation (CE) proves to be an effective tool of producing high-value bio-based products. This study innovatively applied biochar fabricated under microwave irradiation with carbon fiber cloth assistance into CE system. Results highlighted that microwave biochar achieved maximal CE efficiency yielding 8 g COD/L, with 3-fold increase to the blank group devoid of any biochar. Microwave biochar also obtained the highest substrate utilization rate of 94 %, while conventional biochar group recorded 90 % and the blank group was of 74 %. Mechanistic insights revealed that the reductive surface properties facilitated CE performance, which is relevant to fostering dominant genera of Parabacteroides, Bacteroides, and Macellibacteroides. By metagenomics, microwave biochar up-regulated functional genes and enzymes involved in CE process including ethanol oxidation, the reverse ß-oxidation pathway, and the fatty acid biosynthesis pathway. This study effectively facilitated caproate production by utilizing a new microwave biochar preparation strategy.

Advances of carbon-based materials for activating peracetic acid in advanced oxidation processes: A review.

In recent years, the peracetic acid (PAA)-based advanced oxidation process (AOPs) has garnered significant attention in the field of water treatment due to rapid response time and environmentally-friendliness. The activation of PAA systems by diverse carbon-based materials plays a crucial role in addressing emerging environmental contaminants, including various types, structures, and modified forms of carbon materials. However, the structural characteristics and structure-activity relationship of carbon-based materials in the activation of PAA are intricate, while the degradation pathways and dominant active species exhibit diversity. Therefore, it is imperative to elucidate the developmental process of the carbon-based materials/PAA system through resource integration and logical categorization, thereby indicating potential avenues for future research. The present paper comprehensively reviews the structural characteristics and action mechanism of carbon-based materials in PAA system, while also analyzing the development, properties, and activation mechanism of heteroatom-doped carbon-based materials in this system. In conclusion, this study has effectively organized the resources pertaining to prominent research direction of comprehensive remediation of environmental water pollution, thereby elucidating the underlying logic and thought process. Consequently, it establishes robust theoretical foundation for future investigations and applications involving carbon-based materials/PAA system.

Simultaneous Oxidation of Bromide and Dissolution of Manganese Oxide Induced by Freezing.

This study demonstrates that the oxidation of bromide by birnessite (δ-MnO2) results in the concurrent production of soluble manganese (Mn(II)) and reactive bromine (RBr) species in frozen solutions, a process not observed in aqueous solutions. This enhanced oxidation in ice is attributed to the concentration of protons, birnessite, or bromide in the ice grain boundary region. Furthermore, different types of commercial manganese oxides can also oxidize bromide to RBr and release Mn(II) in ice. The presence of fulvic acid (FA) further increases the simultaneous production of RBr and Mn(II) in ice, accompanying the formation of organobromine compounds (OBCs). In frozen δ-MnO2/Br-/FA system, a significant increase in OBCs, mainly highly unsaturated and phenolic compounds, was detected using Fourier transform ion cyclotron resonance mass spectrometry. A marked contrast was observed in the number of OBCs formed in frozen solutions (853 and 415 OBCs at initial pH 3.0 and 5.8, respectively) compared to their aqueous counterparts (11 and 23 OBCs). These findings introduce a new pathway for the formation of RBr, Mn(II), and OBCs in ice, highlighting the need for further research on the environmental fate of bromide and manganese.

Integrating enhanced biological phosphorus removal in adsorption-stage to treat real domestic sewage.

Wastewater treatment innovation toward resource recovery facilities raises concerns about the adsorption and bio-degradation (A-B) process. This study integrated enhanced biological phosphorus removal (EBPR) into the A-stage for real domestic sewage treatment using the short sludge retention time (S-SRT) approach. The S-SRT approach resulted in outstanding phosphorus (over 90 %) and COD removal (approximately 88 %), increased sludge yield and organic matter content, and a 1.68-fold increase in energy recovery efficiency by sludge anaerobic digestion. The inhibition of nitrification relieved competition for carbon sources between denitrification and phosphorus removal, allowing for the enrichment of phosphorus-accumulating organisms (PAOs) such as Tetrasphaera and Halomonas, leading to enhanced phosphorus removal activities. Biological adsorption also plays a significant role in achieving steady phosphorus removal performance. This study demonstrates the potential of the S-SRT approach as an effective strategy for simultaneous carbon and phosphorus capture in the A-stage, contributing to energy and nutrient recovery from sewage.

Unveiling the fate of metal leaching in bimetal-catalyzed Fenton-like systems: pivotal role of aqueous matrices and machine learning prediction.

Metal-based catalytic materials exhibit exceptional properties in degrading emerging pollutants within Fenton-like systems. However, the potential risk of metal leaching has become pressing environmental concern. This study addressed scientific issues pertaining to the leaching behavior and control strategies for metal-based catalytic materials. Innovative cobalt-aluminum hydrotalcite (CoAl-LDH) triggered peroxymonosulfate (PMS) activation system was constructed and achieved near-complete removal of Ciprofloxacin (CIP) across diverse water quality environments. Notably, it was found that the tunable ion exchange and Al3+ stabilization of CoAl-LDH occurred due to the particularity of neutral water quality, resulting in significantly lower Co2+ leaching levels (0.321 mg/L) compared to acidic conditions (5.103 mg/L). In light of this, machine learning technology was then employed for the first time to simulate the dynamic trend of Co2+ leaching and elucidated the critical regulatory roles and mechanisms of Al3+, aqueous matrix, and reaction rate. Furthermore, degradation systems based on different water quality and metal leaching levels regulated the generation levels of SO4.- and O2∙-, and the unique advantages of free radical attack paths were clarified through CIP degradation products and ecotoxicity analysis. These findings introduced novel insights and approaches for engineering application and pollution control in metal-based Fenton-like water treatment.

Chlormequat chloride induces hepatic steatosis by promoting mTOR/SREBP1 mediated lipogenesis via AMPK inhibition.

Chlormequat chloride (CCC), a widely used plant growth regulator, is a choline analogue that has been shown to have endocrine-disrupting effects. Previous studies have shown that maternal exposure to CCC could induce hyperlipidemia and growth disruption in rat offspring. This study aims to further investigate the effects of peripubertal exposure to CCC on pubertal development and lipid homeostasis, as well as the underlying mechanisms. In vivo, male weanling rats were exposed to CCC (0, 20, 75 and 200 mg/kg bw/day) from post-natal day 21-60 via daily oral gavage. The results in rats showed that 75 mg/kg CCC treatment induced hepatic steatosis, predominantly microvesicular steatosis with a small amount of macrovesicular steatosis, in rat livers and 200 mg/kg CCC treatment induced liver damage including inflammatory infiltration, hepatic sinusoidal dilation and necrosis. In vitro, HepG2 cells were treated with CCC (0, 30, 60, 120, 240 and 480 µg/mL) for 24 h. And the results showed that CCC above 120 µg/mL induced an increase in triglyceride and neutral lipid levels of HepG2 cells. Mechanism exploration revealed that CCC treatment promoted the activation of mTOR/SREBP1 signalling pathway and inhibited activation of AMPK in both in vivo rat livers and in vitro HepG2 cells. Treatment with AMPK activator Acadesine (AICAR) could alleviate the lipid accumulation in HepG2 cells induced by CCC. Collectively, the present results indicate that CCC might induce hepatic steatosis by promoting mTOR/SREBP1 mediated lipogenesis via AMPK inhibition.

Feedback of chain elongation microorganisms on iron-based conductive materials: Enhanced microbial functions and biotoxicity adaptation mechanisms.

Despite the increased research efforts aimed at understanding iron-based conductive materials (CMs) for facilitating chain elongation (CE) to produce medium chain fatty acids (MCFAs), the impact of these materials on microbial community functions and the adaptation mechanisms to their biotoxicity remain unclear. This study found that the supply of zero-valent iron (ZVI) and magnetite enhanced the MCFAs carbon-flow distribution by 26 % and 52 %, respectively. Metagenomic analysis revealed the upregulation of fatty acid metabolism, pyruvate metabolism and ABC transporters with ZVI and magnetite. The predominant functional microorganisms were Massilibacterium and Tidjanibacter with ZVI, and were Petrimonas and Candidatus_Microthrix with magnetite. Furthermore, it was demonstrated that CE microorganisms respond and adapt to the biotoxicity of iron-based CMs by adjusting Two-component system and Quorum sensing for the first time. In summary, this study provided a new deep-insight on the feedback mechanisms of CE microorganisms on iron-based CMs.

Upgrading soybean dreg to caproate via intermediate of lactate and mediator of biochar.

To address the environmental hazards posed by high-yield soybean dreg (SD), a high-value strategy is firstly proposed by synthesizing caproate through chain elongation (CE). Optimized conditions for lactate-rich broth as intermediate, utilizing 50 % inoculum ratio, 40 g/L substrate concentration, and pH 5, resulting in 2.05 g/L caproate from direct fermentation. Leveraging lactate-rich broth supplemented with ethanol, caproate was optimized to 2.76 g/L under a refined electron donor to acceptor of 2:1. Furthermore, incorporating 20 g/L biochar elevated caproate production to 3.05 g/L and significantly shortened the lag phase. Mechanistic insights revealed that biochar's surface-existed quinone and hydroquinone groups exhibit potent redox characteristics, thereby facilitating electron transfer. Moreover, biochar up-regulated the abundance of key genes involved in CE process (especially fatty acids biosynthesis pathway), also enriching Lysinibacillus and Pseudomonas as an unrecognized cooperation to CE. This study paves a way for sustainable development of SD by upgrading to caproate.

Sequential bio-treatment of ammonia-rich wastewater from Chinese medicine residue utilization: Regulation of dissolved oxygen.

To effectively treat actual ammonia-rich Chinese medicine residue (CMR) resource utilization wastewater, we optimized an anaerobic-microaerobic two-stage expanded granular sludge bed (EGSB) and moving bed sequencing batch reactor (MBSBR) combined process. By controlling dissolved oxygen (DO) levels, impressive removal efficiencies were achieved. Microaeration, contrasting with anaerobic conditions, bolstered dehydrogenase activity, enhanced electron transfer, and enriched the functional microorganism community. The increased relative abundance of Synergistetes and Proteobacteria facilitated hydrolytic acidification and fostered nitrogen and phosphorus removal. Furthermore, we examined the impact of DO concentration in MBSBR on pollutant removal and microbial metabolic activity, pinpointing 2.5 mg/L as the optimal DO concentration for superior removal performance and energy conservation.

Chlormequat Chloride Inhibits TM3 Leydig Cell Growth via Ferroptosis-Initiated Inflammation.

Ferroptosis hallmarked by lipid peroxidation and iron homeostasis imbalance is involved in the occurrence and development of various diseases. The plant growth regulator chlormequat chloride (CCC) can contribute to the causality and exacerbation of reproductive disorders. However, the mechanism by which CCC may cause Leydig cell attenuation remains poorly understood. In this study, TM3 Leydig cells were used to investigate the inhibitory effect of CCC on cell growth and its possible mechanism. The results showed that CCC caused apoptosis, pyroptosis, ferroptosis and necroinflammation in TM3 cells. By comparing the effects of ferroptosis inhibitor Ferrostatin-1 (Fer-1) and pan-Caspase inhibitor Z-VAD-FMK (ZVF) on lipid peroxidation and Caspase-mediated regulated cell death (RCD), we found that Fer-1 was better at rescuing the growth of TM3 cells than ZVF. Although ZVF reduced mitochondrial ROS level and inhibited the activation of Caspase3 and Caspase1, it could not significantly ameliorate lipid peroxidation and the levels of IL-1ß and HMGB1 like Fer-1. Therefore, ferroptosis might be a key non apoptotic RCD mode responsible for CCC-driven inflammation, leading to weakened viability and proliferation of TM3 cells. In addition, overexpression of ferritin light chain (FTL) promoted the resistance of TM3 cells to CCC-induced ferroptosis-mediated inflammation and to some extent improved the inhibition of viability and proliferation. Altogether, ferroptosis-initiated inflammation might play a key role in CCC-impaired TM3 cell growth.

How denitrifiers defense ciprofloxacin: Insights from intracellular and extracellular stress response.

Overuse of antibiotics has led to their existence in nitrogen-containing water. The impacts of antibiotics on bio-denitrification and the metabolic response of denitrifiers to antibiotics are unclear. We systematically analyzed the effect of ciprofloxacin (CIP) on bio-denitrification and found that 5 mg/L CIP greatly inhibited denitrification with a model denitrifier (Paracoccus denitrificans). Nitrate reduction decreased by 32.89 % and nitrous oxide emission increased by 75.53 %. The balance analysis of carbon and nitrogen metabolism during denitrification showed that CIP exposure blocked electron transfer and reduced the flow of substrate metabolism used for denitrification. Proteomics results showed that CIP exposure induced denitrifiers to use the pentose phosphate pathway more for substrate metabolism. This caused a substrate preference to generate NADPH to prevent cellular damage rather than NADH for denitrification. Notably, despite denitrifiers having antioxidant defenses, they could not completely prevent oxidative damage caused by CIP exposure. The effect of CIP exposure on denitrifiers after removal of extracellular polymeric substances (EPS) demonstrated that EPS around denitrifiers formed a barrier against CIP. Fluorescence and infrared spectroscopy revealed that the binding effect of proteins in EPS to CIP prevented damage. This study shows that denitrifiers resist antibiotic stress through different intracellular and extracellular defense strategies.

Enhancing simultaneous nitrogen and phosphorus availability through biochar addition during Chinese medicinal herbal residues composting: Synergism of microbes and humus.

The disposal of Chinese medicinal herbal residues (CMHRs) derived from Chinese medicine extraction poses a significant environmental challenge. Aerobic composting presents a sustainable treatment method, yet optimizing nutrient conversion remains a critical concern. This study investigated the effect and mechanism of biochar addition on nitrogen and phosphorus transformation to enhance the efficacy and quality of compost products. The findings reveal that incorporating biochar considerably enhanced the process of nutrient conversion. Specifically, biochar addition promoted the retention of bioavailable organic nitrogen and reduced nitrogen loss by 28.1 %. Meanwhile, adding biochar inhibited the conversion of available phosphorus to non-available phosphorus while enhancing its conversion to moderately available phosphorus, thereby preserving phosphorus availability post-composting. Furthermore, the inclusion of biochar altered microbial community structure and fostered organic matter retention and humus formation, ultimately affecting the modification of nitrogen and phosphorus forms. Structural equation modeling revealed that microbial community had a more pronounced impact on bioavailable organic nitrogen, while humic acid exerted a more significant effect on phosphorus availability. This research provides a viable approach and foundation for regulating the levels of nitrogen and phosphorus nutrients during composting, serving as a valuable reference for the development of sustainable utilization technologies pertaining to CMHRs.

How hetero-single-atom dispersion reconstructed electronic structure of carbon materials and regulated Fenton-like oxidation pathways.

Single-atom catalysts (SACs) have emerged as competitive candidates for Fenton-like oxidation of micro-pollutants in water. However, the impact of metal insertion on the intrinsic catalytic activity of carrier materials has been commonly overlooked, and the environmental risk due to metal leaching still requires attention. In contrast to previous reports, where metal sites were conventionally considered as catalytic centers, our study investigates, for the first time, the crucial catalytic role of the carbon carrier modulated through hetero-single-atom dispersion and the regulation of Fenton-like oxidation pathways. The inherent differences in electronic properties between Fe and Co can effectively trigger long-range electron rearrangement in the sp2-carbon-conjugated structure, creating more electron-rich regions for peroxymonosulfate (PMS) complexation and initiating the electron transfer process (ETP) for pollutant degradation, which imparts the synthesized catalyst (FeCo-NCB) with exceptional catalytic efficiency despite its relatively low metal content. Moreover, the FeCo-NCB/PMS system exhibits enduring decontamination efficiency in complex water matrices, satisfactory catalytic stability, and low metal leaching, signifying promising practical applications. More impressively, the spatial relationship between metal sites and electron density clouds is revealed to determine whether high-valent metal-oxo species (HVMO) are involved during the decomposition of surface complexes. Unlike single-type single-atom dispersion, where metal sites are situated within electron-rich regions, hetero-single-atom dispersion can cause the deviation of electron density clouds from the metal sites, thus hindering the in-situ oxidation of metal within the complexes and minimizing the contribution of HVMO. These findings provide new insights into the development of carbon-based SACs and advance the understanding of nonradical mechanisms underpinning Fenton-like treatments.

Chlorocholine chloride exposure induced spermatogenic dysfunction via iron overload caused by AhR/PERK axis-dependent ferritinophagy activation.

Chlorocholine chloride (CCC) is a plant growth regulator used worldwide that is detectable in cereals, fruits and animal products. The health effects of CCC exposure have raised public concern. Our previous research showed that CCC exposure decreased testosterone synthesis in pubertal rats. However, little is known about whether and how pubertal CCC exposure impacts spermatogenesis. In this study, we used BALB/c mice and spermatogonia-derived GC-1 cells to examine CCC-induced spermatogenic dysfunction. In vivo, pubertal CCC exposure led to decreased testicular weight, decreased testicular germ cells and poor sperm quality. This effect worsened after cessation of CCC exposure for the next 30 days. RNA-seq and western blot analysis revealed that CCC induced aryl hydrocarbon receptor (AhR) signaling, endoplasmic reticulum stress (ERS) and ferritinophagy. Increased iron content and lipid peroxidation levels were also observed in CCC-treated testes. In vitro, it was identified that iron overload mediated by enhanced ferritinophagy occurred in CCC-treated GC-1 cells, which might be attributed to the PERK pathway in ERS. Further, for the first time, our study elucidated the involvement of AhR in CCC-induced iron overload, which aggravated testicular oxidative damage via lipid peroxidation. Considering the adverse impact of CCC exposure on rodents, supportive evidence from GC-1 cells, and the critical importance of spermatogenesis on male development, the effects of CCC on the male reproduction warrant increased attention.

Chlormequat chloride induced activation of calmodulin mediated PI3K/AKT signaling pathway led to impaired sperm quality in pubertal mice.

Chlormequat chloride (CCC), as a widely used plant growth regulator, can cause impaired sperm quality and decreased testosterone synthesis in pubertal rats, but the underlying mechanism remains unclear. The purpose of this study was to elucidate the toxicokinetics and tissue distribution of CCC, as well as the possible mechanism of CCC-induced impairment in sperm quality. The concentration of CCC reached its peak 1 h after a single dose (200 mg/kg·bw) administration in mice plasma, and a bimodal phenomenon appeared in the testes, liver, and epididymis. In vivo, 200 mg/kg CCC caused testicular damage and impaired sperm quality in pubertal mice, and the expression of p-tyrosine and GSK3α decreased in cauda epididymidis, sperm and testes. CCC also caused the down-regulation of AKAP4 and the up-regulation of calmodulin (CaM), and activated the PI3K/AKT signaling pathway in the testes. In vitro, CCC reduced the levels of p-tyrosine, AKAP4 and GSK3α, increased the level of CaM and activated the PI3K/AKT signaling pathway in GC-1 cells. CaM antagonist (W-7 hydrochloride) and PI3K inhibitor (LY294002) can effectively improve the expression of GSK3α and AKAP4 by suppressing the PI3K/AKT signaling pathway in GC-1 cells treated with CCC. It was indicated that CCC induced impairment in sperm quality might be partially related to the activation of PI3K/AKT signaling pathway mediated by CaM.

Effect of lanthanum nitrate on adipogenesis in mice.

Lanthanum (La) is widely used in modern industry and agriculture because of its unique physicochemical properties and is broadly exposed in the population. Some studies have shown that La may have some effects on adipogenesis, but there is a lack of related in vivo evidence. In this study, the effects of La(NO3 )3 on adipogenesis and its associated mechanism were studied using C57BL/6J mouse model. The results showed that La(NO3 )3 exposure caused a decrease in body weight and the percentage of fat content in mice. In addition, the adipose marker molecules and specific adipogenic transcription factors decreased in both white adipose tissue (WAT) and brown adipose tissue (BAT). Detection of signaling pathway-related molecules revealed that canonical wnt/ß-catenin pathway-related molecules were upregulated in both adipose tissues. In summary, in vivo exposure to La(NO3 )3 might inhibited adipogenesis in mice, possibly through upregulation of the canonical Wnt/ß-catenin signaling pathway.

Enhanced Oxidation of Organic Compounds by the Ferrihydrite-Ferrate System: The Role of Intramolecular Electron Transfer and Intermediate Iron Species.

Previous studies mostly held that the oxidation capacity of ferrate depends on the involvement of intermediate iron species (i.e., FeIV/FeV), however, the potential role of the metastable complex was disregarded in ferrate-based heterogeneous catalytic oxidation processes. Herein, we reported a complexation-mediated electron transfer mechanism in the ferrihydrite-ferrate system toward sulfamethoxazole (SMX) degradation. A synergy between intermediate FeIV/FeV oxidation and the intramolecular electron transfer step was proposed. Specifically, the conversion of phenyl methyl sulfoxide (PMSO) to methyl phenyl sulfone (PMSO2) suggested that FeIV/FeV was involved in the oxidation of SMX. Moreover, based on the in situ Raman test and chronopotentiometry analysis, the formation of the metastable complex of ferrihydrite/ferrate was found, which possesses higher oxidation potential than free ferrate and could achieve the preliminary oxidation of organics via the electron transfer step. In addition, the amino group of SMX could complex with ferrate, and the resulting metastable complex of ferrihydrite/ferrate would combine further with SMX molecules, leading to intramolecular electron transfer and SMX degradation. The ferrate loss experiments suggested that ferrihydrite could accelerate the decomposition of ferrate. Finally, the effects of pH value, anions, humic acid, and actual water on the degradation of SMX by ferrihydrite-ferrate were also revealed. Overall, ferrihydrite demonstrated high catalytic capacity, good reusability, and nontoxic performance for ferrate activation. The ferrihydrite-ferrate process may be a green and promising method for organic removal in wastewater treatment.

Metabonomics analysis of microalga Scenedesmus obliquus under ciprofloxacin stress.

The wide use of antibiotics in aquaculture has triggered global ecological security issue. Microalgal bioremediation is a promising strategy for antibiotics elimination due to carbon recovery, detoxification and various ecological advantages. However, a lack of understanding with respect to the corresponding regulation mechanism towards antibiotic stress may limit its practical applicability. The microalga Scenedesmus obliquus was shown to be capable of effectively eliminating ciprofloxacin (CIP), which is a common antibiotic used in aquaculture. However, the corresponding transcriptional alterations require further investigation and verification at the metabolomic level. Thus, this study uncovered the metabolomic profiles and detailed toxic and defense mechanisms towards CIP in S. obliquus using untargeted metabolomics. The enhanced oligosaccharide/polyol/lipid transport, up-regulation of carbohydrate and arachidonic acid metabolic pathways and increased energy production via EMP metabolism were observed as defense mechanisms of microalgal cells to xenobiotic CIP. The toxic metabolic responses included: (1) down-regulation of parts of mineral and organic transporters; (2) electrons competition between antibiotic and NAD during intracellular CIP degradation; and (3) suppressed expression of the hem gene in chlorophyll biosynthesis. This study describes the metabolic profile of microalgae during CIP elimination and reveals the key pathways from the perspective of metabolism, thereby providing information on the precise regulation of antibiotic bioremediation via microalgae.