Fermentation-Basel
·
2023
·Vol. 9
·期 3
·284
·
IF 3.7
Jinzhi Yang,Di Cai,Xudong Liu,Liqi Zhu,Changwei Zhang,Qing Peng,Yanxia Han,Guozhen Liu,Ming Yang
Microalgae, which accumulate considerable carbohydrates, are a potential source of glucose for biofuel fermentation. In this study, we investigated the enzymatic hydrolysis efficiency of wet microalgal biomass compared with freeze-dried and oven-dried biomasses, both with and without an acidic pretreatment. With the dilute sulfuric acid pretreatment followed by amy (α-amylase and amyloglucosidase) and cellulase hydrolysis, approximately 95.4% of the glucose was recovered; however, 88.5% was released by the pretreatment with 2% (w/v) sulfuric acid, which indicates the potential of the acids for direct saccharification process. There were no considerable differences in the glucose yields among the three kinds of materials. In the direct amy hydrolysis without any pretreatment, a 78.7% glucose yield was obtained, and the addition of cellulase had no significant effect on the hydrolysis to glucose. Compared with the oven-dried biomass, the wet biomass produced a substantially higher glucose yield, which is possibly because the cross-linked cells of the oven-dried biomass prevented the accessibility of the enzymes. According to the results, the fresh microalgal biomass without cell disruption can be directly used for enzymatic hydrolysis to produce glucose. The enzymatic hydrolysate of the wet microalgal biomass was successfully used for acetone–butanol–ethanol (ABE) fermentation, which produced 7.2 g/L of ABE, indicating the application potential of wet microalgae in the bioalcohol fuel fermentation process.Keywords:wet microalgae;pretreatment;enzymatic hydrolysis;glucose
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CHEMOSPHERE
·
2022
·
IF 8.943
Dongyang Liu,Mingxiang Qv,Dian Dai,Xu Wang,Liandong Zhu
Flame retardants , such as Tetrabromobisphenol A (TBBPA), Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and tributyl phosphate (TBP), are frequently detected in surface water. However, the effects of FRs exposure on aquatic organisms especially freshwater microalgae are still unclear. In this study, the toxicities of TBBPA, TDCPP and TBP to microalgae Chlorella sorokiniana , in terms of growth inhibition, photosynthetic activity inhibition and oxidative damage, were investigated, and according ecological risks were assessed. The results showed that TBBPA, TDCPP and TBP had inhibitory effects on C. sorokiniana , with 96 h EC 50 (concentration for 50% of maximal effect) values of 7.606, 41.794 and 49.996 mg/L, respectively. Fv / Fm decreased as the increase of exposure time under 15 mg/L TBBPA. Under 50 mg/L TDCPP and 80 mg/L TBP exposure, Fv / Fm decreased significantly after 24 h. However, Fv / Fm rose after 96 h, indicating that the damaged photosynthetic activity was reversible. The content of chlorophyll a decreased, as the increase of TBBPA concentration from 3 to 15 mg/L. However, chlorophyll a increased first and then decreased, as the increase of TDCPP and TBP concentrations from 0 to 50 mg/L and 0–80 mg/L, respectively. Results indicated that C. sorokiniana could use the phosphorus of TDCPP and TBP to ensure the production of chlorophyll a . The risen content of reactive oxygen species , malondialdehyde as well as superoxide dismutase activity indicated that exposure to FRs induced oxidative stress . Additionally, the risk quotients showed that tested FRs had ecological risks in natural waters or wastewaters. This study provides insights into the toxicological mechanisms of different FRs toward freshwater microalgae for better understanding of according environmental risks.
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BIOTECHNOLOGY AND BIOENGINEERING
·
2025
·
IF 3.6
Dong-Ao Li,Guang-Hui Xu,Jie Shen,Hong Zhang
This study explores the mechanisms of oxidative damage in Chlorella sorokiniana under continuous gas-liquid phase plasma exposure. The oxidative damage mechanism of C. sorokiniana was revealed through multiple analytical techniques, including scanning electron microscopy (SEM), flow cytometry (FCM), and fluorescence excitation-emission matrix (EEM). Plasma-induced damage to algal cell membranes, causing seepage of photosynthetic pigments and dissolved organic matter; chlorophyll fluorescence changes confirmed damage to the photosynthetic system. Alterations in MDA, intracellular ROS/NO, and antioxidant enzyme activities reflect lipid peroxidation and oxidative stress levels. These results show that plasma induces oxidative damage to algal membranes, intracellular components, and photosystems via reactive oxygen and nitrogen species (RONS). C. sorokiniana activates its antioxidant defense system under stress. This gradual, cumulative damage exerts distinct biological effects at different times. The findings support the precise control of low-temperature plasma for beneficial microorganisms and provide a basis for advancing microalgae transformation technologies.
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Frontiers in Marine Science
·
2022
·
IF 5.247
Xu Haiqing,Yang Jinzhi,Wang Xu,Peng Qing,Han Yanxia,Liu Xudong,Liu Kexin,Dou Shijuan,Li Liyun,Liu Guozhen,Yang Ming
Microalgae can effectively accumulate starch by using nutritional limitation methods in the context of bioalcohol fuel production. However, relatively few studies have focused on starch accumulation in microalgae and its molecular basis, especially under sulfur limitation conditions. In this study, the starch accumulation dynamics and physiological responses of Chlorella sorokiniana under sulfur starvation (SS) and sulfur replenishment (SR) conditions were investigated, and the genes involved in the transcriptional regulation were explored using RNA-seq. The starch content in C. sorokiniana cells significantly increased from 1.6% to 55.0% of dry weight within 24 h under SS conditions, and then, it decreased to 3.4% within 12 h after transition to SR conditions. However, cell growth was inhibited, and pigment content decreased under SS conditions. Using RNA-seq analysis, a total of 9720 differentially expressed genes (DEGs) induced by sulfur status were obtained. These genes were narrowed down to 454 starvation and replenishment cross-validated (SRV)-DEGs, among which 283 SRV-DEGs were significantly up-regulated and 171 SRV-DEGs were down-regulated under SS conditions, and returned to their previous state under SR conditions. The SRV-DEGs enriched in the sulfate metabolism pathway were all up-regulated under SS conditions after 6 h to speed up the sulfur metabolic cycle, and the transcriptional abundance of a sulfate transporter (SULTR4), cysteine synthase[O-acetylserine(thiol)-lyase] (OASTL), serine acetyltransferase (SAT), and methanethiol oxidase (SELENBP1) increased 8.6-fold, 12.6-fold, 8.7-fold, and 12.4-fold, respectively. Protein synthesis was correspondingly inhibited, which resulted in the reallocation of carbon and elevated the starch synthesis pathway, in which the expressions of glycogen branching enzyme (GBE) and starch synthase (SS) were up-regulated 12.0- and 3.0-fold, respectively. The fatty acid desaturase (FAD) and phosphatidic acid phosphatase (PAP) in the lipid synthesis pathway were strongly up-regulated 8.8- and 16.2-fold, respectively, indicating the competitive synthesis of lipids. The down-regulation of SRV-DEGs associated with carbon fixation, such as those in the Calvin cycle, possibly affected cell growth. The time-resolved transcriptional analysis identified the SRV-DEGs, revealing the underlying starch accumulation mechanism, as well as the relationship with cell growth and lipid synthesis.
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MARINE ENVIRONMENTAL RESEARCH
·
2022
·
IF 3.737
Wenjing Wang,Yanqing Sheng
Decabromodiphenyl ethane is a novel brominated flame retardant , that has always been dissolved in organic solvents to explore its activities on aquatic organisms. In this study, the influences of decabromodiphenyl ethane on the microalga Chlorella sorokiniana ( C. sorokiniana ) were studied, and three microalgae treatments, including decabromodiphenyl ethane dissolved in dimethyl sulfoxide solvent (DBDPE treatment), dimethyl sulfoxide alone (control II) or untreated (control I) were used in the experiment, respectively. The results showed that the growth of C. sorokiniana was remarkably enhanced in the DBDPE treatment compared with the control I and II groups. Conjoint analysis of transcriptomics and quantitative proteome displayed that the upregulated differentially expressed genes and proteins of DBDPE:control I were enriched in 6 pathways, and downregulated genes/proteins of DBDPE:control I were enriched in 3 pathways. The upregulated differentially expressed genes and proteins of DBDPE:control II were enriched in 4 pathways, and downregulated genes/proteins of DBDPE:control II were enriched in 6 pathways. In addition, decabromodiphenyl ethane changed the fatty acid concentration in C. sorokiniana cells. The activities of superoxide dismutase were enhanced when C. sorokiniana were treated by decabromodiphenyl ethane. The data highlighted that the mRNA and protein expression relating to the fatty acid production, of C. sorokiniana were significantly affected by decabromodiphenyl ethane, and decabromodiphenyl ethane pollution changed the physiological metabolism of microalgae and had harmful effects on natural environments.
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JOURNAL OF HAZARDOUS MATERIALS
·
2025
·
IF 11.3
Wei Wang,Qirui Wu,Hanzhi Wang,Mingxiang Qv,Dian Dai,Xiaoman He,Ivan P. Pozdnyakov,Li-Zhi Huang,Liandong Zhu
This study investigated the UV 254 irradiation degradation of chloroacetic acids (CAAs), specifically monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), and trichloroacetic acid (TCAA), and evaluated the ecological impact of their degradation products on Chlorella sorokiniana (CS). The degradation followed first-order kinetics, with dechlorination efficiencies of 91.2% for MCAA, 92.9% for DCAA, and 92.4% for TCAA. TCAA was degraded fastest due to its higher chlorine content. Initial pH (3–10) had minimal influence, whereas lower concentrations (0.25 mM) led to slower degradation. Hydroxyl radicals (•OH) were identified as the dominant reactive species via electron paramagnetic resonance analysis. Dechlorination generated Cl⁻ and HCl, resulting in acidification and increased toxicity. Total organic carbon (TOC) analysis indicated nearly complete mineralization. Untreated CAAs significantly inhibited microalgal growth and photosynthesis, while post-degradation pH adjustment (to pH > 4) mitigated toxicity and enabled microalgal assimilation, with CS culture pH further increasing to 9–10, thereby facilitating self-buffered bioremediation. These findings confirm the effectiveness of UV 254 degradation on CAAs and provide valuable guidance for ecological safety in aquatic ecosystem management.
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WATER RESEARCH
·
2025
·
IF 12.4
Di Zhou,Liandong Zhu
Organophosphate esters (OPEs) are typical types of emerging contaminants that are widely presented in wastewater. While they can serve as phosphorus (P) sources for microalgae growth, their toxicity disrupts metabolic processes, posing challenges to microalgae-based bioremediation. This study elucidated the regulatory effects of OPEs on the removal of ammonia (NH 4 + -N) and phosphate (PO 4 3- -P) from synthetic wastewater by Chlorella sorokiniana , as well as the concurrent OPEs degradation, while unveiling the molecular mechanism of these interactions. OPEs exposure (1 and 10 mg/L) initially inhibited nutrient assimilation, reducing NH₄⁺-N and PO₄³⁻-P removal by 21.78 %-46.59 % and 7.46 %-26.07 %, respectively. The suppression was primarily attributed to oxidative stress-induced DNA damage, leading to G2/S cell cycle arrest, and metabolic disruptions particularly in crucial nitrogen assimilation enzymes (GS, GDH) and genes ( IMPL2, IPPK ) related to Pi supply strategy adjustment. Meanwhile, OPEs continuously impaired heterotrophy (NaAc matabolism), restricting energy supply for nutrient uptake. Despite this initial inhibition, microalgae exhibited adaptive recovery through photosynthetic regulation and EPS secretion. Enhanced linear electron transfer (LET) and Calvin cycle facilitated photoautotrophy, while EPS played a crucial role in OPEs adsorption and degradation via photosensitization and biosorption, achieving 41.53 %-54.50 % OPEs removal without additional energy input. Transcriptome analysis, combined with KEGG-based pathway annotation, was performed to elucidate the molecular mechanisms underlying these physiological responses. This study unveils a novel stress adaptation mechanism in microalgae, demonstrating their ability to mitigate OPEs toxicity and restore nutrient removal efficiency. The findings provide new insights into the synergistic bioremediation of emerging and conventional pollutants, offering a sustainable strategy for low-carbon wastewater treatment.
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JOURNAL OF HAZARDOUS MATERIALS
·
2024
·
IF 12.2
Zhilin Zhao,Xiaoying Zheng,Zongshuo Han,Yue Li,Haidong He,Tao Lin,Hang Xu
Microplastics (MPs) commonly coexist with other contaminants and alter their toxicity. Perfluorooctanoic acid (PFOA), an emerging pollutant, may interact with MPs but remain largely unknown about the joint toxicity of PFOA and MPs. Hence, this research explored the single and joint effects of PFOA and polystyrene microplastics (PS-MPs) on microalgae ( Chlorella sorokiniana ) at the cellular and molecular levels. Results demonstrated that PS-MPs increased PFOA bioavailability by altering cell membrane permeability, thus aggravating biotoxicity (synergistic effect). Meanwhile, the defense mechanisms (antioxidant system modulation and extracellular polymeric substances secretion) of Chlorella sorokiniana were activated to alleviate toxicity. Additionally, transcriptomic analysis illustrated that co-exposure had more differential expression genes (DEGs; 4379 DEGs) than single-exposure (PFOA: 2533 DEGs; PS-MPs: 492 DEGs), which were mainly distributed in the GO terms associated with the membrane composition and antioxidant system. The molecular regulatory network further revealed that PS-MPs and PFOA primarily regulated the response mechanisms of Chlorella sorokiniana by altering the ribosome biogenesis, photosynthesis, citrate cycle, oxidative stress , and antioxidant system (antioxidant enzyme, glutathione-ascorbate cycle). These findings elucidated that PS-MPs enhanced the effect of PFOA, providing new insights into the influences of MPs and PFOA on algae and the risk assessment of multiple contaminants. Environmental implication MPs and PFAS, emerging contaminants , are difficult to degrade and pose a non-negligible threat to organisms. Co-pollution of MPs and PFAS is ubiquitous in the aquatic environment, while risks of co-existence to organisms remain unknown. The present study revealed the toxicity and defense mechanisms of microalgae exposure to PS-MPs and PFOA from cellular and molecular levels. According to biochemical and transcriptomic analyses, PS-MPs increased PFOA bioavailability and enhanced the effect of PFOA on Chlorella sorokiniana , showing a synergistic effect. This research provides a basis for assessing the eco-environmental risks of MPs and PFAS.
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JOURNAL OF HAZARDOUS MATERIALS
·
2025
·
IF 11.3
Zhilin Zhao,Xiaoying Zheng,Yue Li,Zongshuo Han,Yu Tang,Tianxing Hu,Tao Lin
Microplastics (MPs) and perfluorobutanoic acid (PFBA), emerging contaminants, are ubiquitous in the environment and toxic to organisms. The interaction of MPs with other contaminants can affect their toxicity. However, the impact of MPs on PFBA toxicity remains unknown. This research investigated the individual and combined impacts of polystyrene microplastics (PS) and PFBA to Chlorella sorokiniana based on cellular responses and transcriptome analyses. Results showed that both PS and PFBA induced excessive ROS generation, causing cell membrane damage and photosynthesis inhibition, ultimately inhibiting Chlorella sorokiniana growth. The highest inhibition was observed for small particle size PS, with a maximum inhibition rate of 15.98 ± 1.24 % (3PS group). Notably, the combined toxicity of PFBA and PS exhibited antagonism, which was attributed to PFBA adsorption and PS hetero-aggregation via massive EPS secretion, resulting in decreased PS and PFBA bioavailability. Transcriptomic analysis elucidated that EPS secretion was promoted owing to the up-regulation of carbohydrate, amino acid, and energy metabolism (carbon fixation, oxidative phosphorylation, and TCA cycle). Enhanced EPS secretion, ABC transport, and antioxidant response alleviated PS and PFBA toxicity. Our findings offer valuable data for the joint ecotoxicity of PFASs and MPs, contributing to environmental risk assessment of co-pollution.
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Water
·
2026
·Vol. 18
·期 11
·1334
·
IF 3.5
Taowei Qian,Longfei Wang
Microalgal biotransformation plays an important role in determining the environmental fate of trace antibiotics. However, the role of polystyrene microplastics (PS-MPs) in regulating algal stress responses and antibiotic biotransformation remains poorly understood. In this study, PS-MPs and sulfamethoxazole (SMX) were selected as representative pollutants to investigate the toxic effects, defense responses, and SMX degradation mechanism of typical microalgae, i.e.,Chlorella sorokiniana, under single- and combined exposure conditions (PS-MPs: 10 mg/L; SMX: 0.5 and 5 mg/L) over 8 days. The results showed that co-exposure significantly alleviated growth inhibition, photosynthesis inhibition, and reactive oxygen species (ROS) accumulation. Meanwhile, antioxidant enzyme activities decreased, whereas extracellular polymeric substance (EPS) secretion increased markedly, with the highest exopolysaccharide content reaching 83.22 ± 0.13 mg/L in the PS-MPs + 5 mg/L SMX group. Compared with the 5 mg/L SMX group, the biodegradation ratio and total removal ratio of SMX in the PS-MPs + 5 mg/L SMX group increased from 28.90% to 39.50% and from 40.90% to 50.50%, respectively. The relevant research proved that high EPS secretions facilitated SMX degradation and consequently reduced biotoxicity. Moreover, eleven degradation products and three potential transformation pathways were identified during the incubation. During the co-exposure of SMX and PS-MPs, most metabolites exhibited lower toxicity and bioaccumulation potential than SMX, indicating reduced ecological risk in the presence of PS-MPs. These findings provide new insight into the fate of antibiotics in microplastic-contaminated aquatic systems.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Yuhao Chu,Xi Chen,Shengnan Li,Xue Li,Nanqi Ren,Shih-Hsin Ho
Microalgae-mediated biodegradation of antibiotics has attracted increasing interest. However, the exact degradation mechanism behind it remains elusive, which is crucial for improving its efficiency and large-scale implementation. Therefore, this study aims to thoroughly investigate how Chlorella sorokiniana ( C.sorokiniana ) degrades ciprofloxacin (CIP) from the molecular level to elucidate its complicated degradation mechanism. Results show that C.sorokiniana exhibited an impressive removal rate of 38.05–74.29 % for CIP, the synergistic effect of biosorption and biodegradation was the main removal mechanism of CIP. The content of EPS increased by 11.84–103.31 %, acting as a carrier to increase the bioavailability of CIP. Enzyme activity analysis identified POD, CYP450, and GST as the major catalytic enzymes responsible for the biotransformation process of CIP with increases of 6–41.2 %, 18.78–102.1 % and 3.53–58.15 %, respectively. Molecular docking further revealed that the binding affinity of 146.24 μM, 27.71 μM and 16.33 μM was observed for POD,CYP450, and GST, respectively, indicating the high metabolic efficiency of CIP by CYP450. Finally, DFT calculations elucidated the enzyme-mediated biodegradation pathway of CIP, including hydroxylation, decarboxylation, and ring opening. These findings are expected to further fill the knowledge gap on the catalysis mechanism of CIP degradation by enzymes and improve the practical application of microalgae to antibiotic wastewater.
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Dongyang Liu,Wenfeng Yang,Yuanfei Lv,Shuangxi Li,Mingxiang Qv,Dian Dai,Liandong Zhu
With the continuous increase of e-waste, more and more pollutants such as tetrabromobisphenol A (TBBPA) and bivalent cadmium ions (Cd(Ⅱ)) are often detected in the surface water. However, their combined toxicity to microalgae is still unclear. Therefore, this study comprehensively explored effects of TBBPA and Cd(Ⅱ) on freshwater microalgae Chlorella sorokiniana , in terms of growth, photosynthetic activity, biochemical characteristics and molecular level. Results showed that Cd(Ⅱ) below 1 mg/L could promote the growth of microalgae, while TBBPA with various dosages showed inhibitory effects. The coexistence of TBBPA and Cd(Ⅱ) had a significant effect on photosynthetic activity, enzyme activity and chlorophylls content. Simultaneously, the release of dissolved organic matters reduced the damage of pollutants to algae. Moreover, C. sorokiniana had a good removal effect on Cd(Ⅱ), and the removal efficiency could reach 72.83%. Interestingly, addition of Cd(Ⅱ) could enhance the removal effect of C. sorokiniana on TBBPA, and the highest removal reached 44.16%. Transcriptome analysis showed that C. sorokiniana had different responses to Cd(Ⅱ) and TBBPA stress, while both caused the regulation of protein synthesis-related genes. Additionally, exposure to Cd(II) upregulated DNA replication-related genes in microalgae, thereby promoting cell proliferation. This study provides insights into toxic mechanisms of TBBPA and Cd(Ⅱ) to microalgae together with their removal patterns, which offers a theoretical basis for further assessment of the actual risk of Cd(II) and TBBPA to aquatic organisms.
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