Pub Date : 2026-04-01Epub Date: 2026-01-27DOI: 10.1016/j.biortech.2026.134103
Junhua Di , Yizhen Zhang , Bright Uwase , Paul Arnaud Yao Koffi , Yu-Cai He , Cuiluan Ma
To enhance the application potential of ω-transaminase ATA1012 in the efficient bioamination of biobased aldehydes, this study performed site-directed mutagenesis at key sites in the active center and flexible loop region, resulting in the mutant Q25F with significantly improved thermostability. The half-life of Q25F increased from 4.2 h to 25.1 h at 37 °C and from 0.6 h to 3.3 h at 50 °C. Benefiting from its enhanced stability, Q25F efficiently converted lignin-derived vanillin (260 mM) to vanillylamine within 12 h, achieving a yield of 92.6% and a selectivity >99%. Furthermore, by optimizing the mutagenesis strategy, engineered strains capable of efficiently catalyzing the transamination of biomass-derived furfural (FAL) and 5-hydroxymethylfurfural (HMF) into biobased amines were constructed. This study establishes a site-directed mutagenesis approach for enhancing the thermostability of ω-transaminase, providing an effective route for the high-value bioconversion of carbohydrates and lignin in lignocellulosic biomass.
{"title":"Site-directed mutagenesis to enhance thermostability of Caulobacter sp. D5 ω-transaminase for efficient bioamination of biobased aldehydes","authors":"Junhua Di , Yizhen Zhang , Bright Uwase , Paul Arnaud Yao Koffi , Yu-Cai He , Cuiluan Ma","doi":"10.1016/j.biortech.2026.134103","DOIUrl":"10.1016/j.biortech.2026.134103","url":null,"abstract":"<div><div>To enhance the application potential of ω-transaminase ATA1012 in the efficient bioamination of biobased aldehydes, this study performed site-directed mutagenesis at key sites in the active center and flexible loop region, resulting in the mutant Q25F with significantly improved thermostability. The half-life of Q25F increased from 4.2 h to 25.1 h at 37 °C and from 0.6 h to 3.3 h at 50 °C. Benefiting from its enhanced stability, Q25F efficiently converted lignin-derived vanillin (260 mM) to vanillylamine within 12 h, achieving a yield of 92.6% and a selectivity >99%. Furthermore, by optimizing the mutagenesis strategy, engineered strains capable of efficiently catalyzing the transamination of biomass-derived furfural (FAL) and 5-hydroxymethylfurfural (HMF) into biobased amines were constructed. This study establishes a site-directed mutagenesis approach for enhancing the thermostability of ω-transaminase, providing an effective route for the high-value bioconversion of carbohydrates and lignin in lignocellulosic biomass.</div></div>","PeriodicalId":258,"journal":{"name":"Bioresource Technology","volume":"446 ","pages":"Article 134103"},"PeriodicalIF":9.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-11DOI: 10.1016/j.biortech.2026.134214
Qitong Cai , Zhengpeng Wang , Xinyu Li , Yan Liu , Nanqi Ren , Defeng Xing , Xiaoxue Mei , Yawen Fan
Low temperatures suppress microbial growth and metabolism activity and pollutant removal in wastewater treatment systems. This study systematically compared shaping effect of micro electric fields (MEF) and pulsed electric fields (PEF) on municipal wastewater treatment by a microalgae-bacteria system (MBS) at 5 °C, 10 °C, and 15 °C. Both electric field modes showed significant improvement in cell biomass accumulation, photosynthetic pigment synthesis, and nutrient and COD removals compared to non-electrified controls. Under identical operating conditions, MEF and PEF exhibited distinct electrobiological modulation behaviors, MEF promoted more stable cell biomass-pollutant coupling under cold stress, whereas PEF provided stronger short-term stimulation at moderately low temperatures. Energy analysis showed that PEF reduced volumetric energy consumption by 20–50% compared with MEF. Overall, a coupled process of microalgal-bacterial consortia and PEF offers an energy-efficient, non-thermal complementary strategy to conventional thermal approaches for wastewater management under low-temperature conditions.
{"title":"Electrically enhanced microalgae-bacteria systems for wastewater treatment under low-temperature conditions","authors":"Qitong Cai , Zhengpeng Wang , Xinyu Li , Yan Liu , Nanqi Ren , Defeng Xing , Xiaoxue Mei , Yawen Fan","doi":"10.1016/j.biortech.2026.134214","DOIUrl":"10.1016/j.biortech.2026.134214","url":null,"abstract":"<div><div>Low temperatures suppress microbial growth and metabolism activity and pollutant removal in wastewater treatment systems. This study systematically compared shaping effect of micro electric fields (MEF) and pulsed electric fields (PEF) on municipal wastewater treatment by a microalgae-bacteria system (MBS) at 5 °C, 10 °C, and 15 °C. Both electric field modes showed significant improvement in cell biomass accumulation, photosynthetic pigment synthesis, and nutrient and COD removals compared to non-electrified controls. Under identical operating conditions, MEF and PEF exhibited distinct electrobiological modulation behaviors, MEF promoted more stable cell biomass-pollutant coupling under cold stress, whereas PEF provided stronger short-term stimulation at moderately low temperatures. Energy analysis showed that PEF reduced volumetric energy consumption by 20–50% compared with MEF. Overall, a coupled process of microalgal-bacterial consortia and PEF offers an energy-efficient, non-thermal complementary strategy to conventional thermal approaches for wastewater management under low-temperature conditions.</div></div>","PeriodicalId":258,"journal":{"name":"Bioresource Technology","volume":"446 ","pages":"Article 134214"},"PeriodicalIF":9.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146160646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study presented an interpretable multi-objective machine learning (ML) framework to navigate the trade-off between biomass accumulation and β-carotene production in Dunaliella salina. Models were developed from 1,494 data points spanning 637 Latin Hypercube Sampling (LHS)-designed regimes, covering eight input variables: temperature, light intensity, salinity, NaHCO3, NaNO3, K2HPO4, putrescine, and cultivation time, with dry cell weight (DCW) and β-carotene yield as output variables. A systematic evaluation of four algorithms, including random forest (RF), extreme gradient boosting (XGBoost), gradient boosting decision tree (GBDT), and artificial neural network (ANN), identified ANN and GBDT as the optimal single-target predictors for DCW and β-carotene yield, respectively. Building on this, their multi-objective versions were developed. The multi-objective ANN, as a unified framework, demonstrated the best predictive performance, achieving an overall test R2 of 0.9758 and accuracy comparable to the specialized single-objective models. Integrated with particle swarm optimization (PSO), the framework generated tailored cultivation strategies (Pareto-optimal and weight-based solutions), which were experimentally validated with all relative errors below 6.67%. The Pareto-optimized strategy enhanced biomass and β-carotene yield by 63.46% and 63.11%, respectively, compared to a non-ML-optimized control. Shapley Additive Explanations (SHAP) analysis revealed cultivation time, salinity, and light intensity to be the most influential factors for model predictions. This work establishes a robust, data-driven paradigm for the intelligent and sustainable optimization of microalgal bioprocesses.
{"title":"Machine learning-driven multi-objective optimization of Dunaliella salina cultivation for enhanced biomass and β-carotene production","authors":"Jianxin Tang , Zizhou Zhang , Jinghan Wang, Fantao Kong, Zhanyou Chi","doi":"10.1016/j.biortech.2026.134182","DOIUrl":"10.1016/j.biortech.2026.134182","url":null,"abstract":"<div><div>This study presented an interpretable multi-objective machine learning (ML) framework to navigate the trade-off between biomass accumulation and β-carotene production in <em>Dunaliella salina</em>. Models were developed from 1,494 data points spanning 637 Latin Hypercube Sampling (LHS)-designed regimes, covering eight input variables: temperature, light intensity, salinity, NaHCO<sub>3</sub>, NaNO<sub>3</sub>, K<sub>2</sub>HPO<sub>4</sub>, putrescine, and cultivation time, with dry cell weight (DCW) and β-carotene yield as output variables. A systematic evaluation of four algorithms, including random forest (RF), extreme gradient boosting (XGBoost), gradient boosting decision tree (GBDT), and artificial neural network (ANN), identified ANN and GBDT as the optimal single-target predictors for DCW and β-carotene yield, respectively. Building on this, their multi-objective versions were developed. The multi-objective ANN, as a unified framework, demonstrated the best predictive performance, achieving an overall test R<sup>2</sup> of 0.9758 and accuracy comparable to the specialized single-objective models. Integrated with particle swarm optimization (PSO), the framework generated tailored cultivation strategies (Pareto-optimal and weight-based solutions), which were experimentally validated with all relative errors below 6.67%. The Pareto-optimized strategy enhanced biomass and β-carotene yield by 63.46% and 63.11%, respectively, compared to a non-ML-optimized control. Shapley Additive Explanations (SHAP) analysis revealed cultivation time, salinity, and light intensity to be the most influential factors for model predictions. This work establishes a robust, data-driven paradigm for the intelligent and sustainable optimization of microalgal bioprocesses.</div></div>","PeriodicalId":258,"journal":{"name":"Bioresource Technology","volume":"446 ","pages":"Article 134182"},"PeriodicalIF":9.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-10DOI: 10.1016/j.biortech.2026.134196
Huidan Xue , Yang Zhang , Fei He , Lejie Tian , Benqiang Li , Zhaolong Deng , Tian Tian , Dongsheng Li , Jianxi Liu
In the context of global warming, microalgae not only contribute to carbon neutrality through photosynthesis but also generate economically valuable biomass. However, challenge still remains in nanomaterial regulatory mechanisms regarding microalgal growth and metabolism. This work studies synergistic mechanisms of porphyrin-based metal–organic frameworks (MOFs) in boosting photosynthesis and modulating primary metabolism of Chlorella pyrenoidosa. Experimental results demonstrated that MOFs significantly promoted microalgal growth and accelerated cellular division rates. MOFs enhanced the photochemical efficiency of PSII and photosynthetic pigment content, facilitating electron transfer from QA to QB while improving the electron transport capacity of algal cells. The metabolomics analysis identified that 786 differentially expressed metabolites, primarily enriched in metabolic pathways related to cellular metabolism. By upregulating three key pathways—starch and sucrose metabolism, glycerolipid metabolism, and amino acid biosynthesis—MOFs facilitated starch production, redirected carbohydrate flux toward lipid synthesis (increasing lipid yield), and elevated amino acid levels, thereby increasing the total production of protein. These findings suggest that MOFs exert multifaceted effects on photosynthesis, biomass synthesis, as well as metabolic regulation within microalgae. This study provides evidence for the application of artificial MOFs in modulating metabolic pathways to enhance microalgal bioresource production.
{"title":"Insights into the synergistic mechanisms of metal-organic frameworks in boosting photosynthesis and modulating primary metabolism of Chlorella pyrenoidosa","authors":"Huidan Xue , Yang Zhang , Fei He , Lejie Tian , Benqiang Li , Zhaolong Deng , Tian Tian , Dongsheng Li , Jianxi Liu","doi":"10.1016/j.biortech.2026.134196","DOIUrl":"10.1016/j.biortech.2026.134196","url":null,"abstract":"<div><div>In the context of global warming, microalgae not only contribute to carbon neutrality through photosynthesis but also generate economically valuable biomass. However, challenge still remains in nanomaterial regulatory mechanisms regarding microalgal growth and metabolism. This work studies synergistic mechanisms of porphyrin-based metal–organic frameworks (MOFs) in boosting photosynthesis and modulating primary metabolism of <em>Chlorella pyrenoidosa</em>. Experimental results demonstrated that MOFs significantly promoted microalgal growth and accelerated cellular division rates. MOFs enhanced the photochemical efficiency of PSII and photosynthetic pigment content, facilitating electron transfer from Q<sub>A</sub> to Q<sub>B</sub> while improving the electron transport capacity of algal cells. The metabolomics analysis identified that 786 differentially expressed metabolites, primarily enriched in metabolic pathways related to cellular metabolism. By upregulating three key pathways—starch and sucrose metabolism, glycerolipid metabolism, and amino acid biosynthesis—MOFs facilitated starch production, redirected carbohydrate flux toward lipid synthesis (increasing lipid yield), and elevated amino acid levels, thereby increasing the total production of protein. These findings suggest that MOFs exert multifaceted effects on photosynthesis, biomass synthesis, as well as metabolic regulation within microalgae. This study provides evidence for the application of artificial MOFs in modulating metabolic pathways to enhance microalgal bioresource production.</div></div>","PeriodicalId":258,"journal":{"name":"Bioresource Technology","volume":"446 ","pages":"Article 134196"},"PeriodicalIF":9.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146153149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-10DOI: 10.1016/j.biortech.2026.134195
Li Li , Yasen Wang , Buqing Wang , Liqun Shen , Yahui Gao , Wei Lin , Zijie Li
Numerous organisms have evolved the ability to utilize light through photoreceptor proteins that mediate diverse biological processes. Currently, several optogenetic sensor systems are widely used in yeast. However, when these systems are applied for gene repression to regulate endogenous yeast gene expression, they typically require the insertion of corresponding target sites near the native promoter of the gene of interest to achieve precise modulation. To address these constraints, a novel blue light-inducible optogenetic tool designated iLight9 was developed, a single-component optogenetic biosensor integrated with the CRISPR-dCas9 platform. The stability of the iLight9 system was further enhanced by employing a strategy involving the addition of a protein degradation tag. The resulting system was designated as iLight9O, which facilitated programmable regulation of distinct genes through the introduction of specific sgRNAs. Subsequently, systematic metabolic engineering strategies were employed to construct an efficient patchoulol-producing cell factory in Saccharomyces cerevisiae. Moreover, a two-step isoprenol utilization (IU) pathway was introduced into the recombinant strain to enhance its capacity for patchoulol biosynthesis. Crucially, the iLight9O system was adopted to dynamically downregulate squalene synthase, a key enzyme in the competing squalene biosynthetic pathway. This optogenetic flux control strategy increased patchoulol titers by 66 % in the IU-optimized strain and 24 % in the MVAIU2 strain, demonstrating significant improvements over static engineering approaches.
{"title":"A dCas9-integrated iLight9O system enables dynamic regulation for enhanced patchoulol biosynthesis in Saccharomyces cerevisiae","authors":"Li Li , Yasen Wang , Buqing Wang , Liqun Shen , Yahui Gao , Wei Lin , Zijie Li","doi":"10.1016/j.biortech.2026.134195","DOIUrl":"10.1016/j.biortech.2026.134195","url":null,"abstract":"<div><div>Numerous organisms have evolved the ability to utilize light through photoreceptor proteins that mediate diverse biological processes. Currently, several optogenetic sensor systems are widely used in yeast. However, when these systems are applied for gene repression to regulate endogenous yeast gene expression, they typically require the insertion of corresponding target sites near the native promoter of the gene of interest to achieve precise modulation. To address these constraints, a novel blue light-inducible optogenetic tool designated iLight9 was developed, a single-component optogenetic biosensor integrated with the CRISPR-dCas9 platform. The stability of the iLight9 system was further enhanced by employing a strategy involving the addition of a protein degradation tag. The resulting system was designated as iLight9O, which facilitated programmable regulation of distinct genes through the introduction of specific sgRNAs. Subsequently, systematic metabolic engineering strategies were employed to construct an efficient patchoulol-producing cell factory in <em>Saccharomyces cerevisiae</em>. Moreover, a two-step isoprenol utilization (IU) pathway was introduced into the recombinant strain to enhance its capacity for patchoulol biosynthesis. Crucially, the iLight9O system was adopted to dynamically downregulate squalene synthase, a key enzyme in the competing squalene biosynthetic pathway. This optogenetic flux control strategy increased patchoulol titers by 66 % in the IU-optimized strain and 24 % in the MVAIU2 strain, demonstrating significant improvements over static engineering approaches.</div></div>","PeriodicalId":258,"journal":{"name":"Bioresource Technology","volume":"446 ","pages":"Article 134195"},"PeriodicalIF":9.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146153150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-02DOI: 10.1016/j.biortech.2026.134147
Long Huang , Lin Liu , Guangyi Zhang , Guoqiang Li , Yingke Fang , Yuan Li , Huiying Yang , Hongbin Xu
Polyhydroxyalkanoates (PHAs) are promising substitutes for petroleum-based plastics, but their production is constrained by the high energy demand and CO2 emissions of mechanical aeration. We developed a membrane-mediated, photosynthetically coupled system in which a hydrophobic polytetrafluoroethylene (PTFE) membrane enables gas exchange between spatially separated microalgal and PHA-storing mixed-culture chambers, establishing an internal O2–CO2 cycle. The effects of microbial-to-algal biomass ratio (Mp/Ma), substrate-to-microbe ratio (F/M), membrane area-to-volume ratio (θ) and initial inorganic carbon concentration (IC_ini) were evaluated. Optimal performance was achieved at Mp/Ma = 3:1 and F/M = 1:1; increasing θ to 0.012 m2 L−1 allowed microalgal oxygen to sustain a PHA content of 51% (VSS), comparable to mechanical aeration. Under these conditions, specific energy consumption and process-related CO2 emissions per unit PHA were reduced by 90% and 38%, respectively, with microalgal CO2 fixation contributing 11%, rising to 16.7% at 30 mmol L−1 inorganic carbon. This configuration offers a promising route toward low-energy, low-carbon PHA production.
{"title":"A membrane-mediated algal–bacterial coupling strategy for energy – efficient and low-carbon PHA production","authors":"Long Huang , Lin Liu , Guangyi Zhang , Guoqiang Li , Yingke Fang , Yuan Li , Huiying Yang , Hongbin Xu","doi":"10.1016/j.biortech.2026.134147","DOIUrl":"10.1016/j.biortech.2026.134147","url":null,"abstract":"<div><div>Polyhydroxyalkanoates (PHAs) are promising substitutes for petroleum-based plastics, but their production is constrained by the high energy demand and CO<sub>2</sub> emissions of mechanical aeration. We developed a membrane-mediated, photosynthetically coupled system in which a hydrophobic polytetrafluoroethylene (PTFE) membrane enables gas exchange between spatially separated microalgal and PHA-storing mixed-culture chambers, establishing an internal O<sub>2</sub>–CO<sub>2</sub> cycle. The effects of microbial-to-algal biomass ratio (Mp/Ma), substrate-to-microbe ratio (F/M), membrane area-to-volume ratio (θ) and initial inorganic carbon concentration (IC_ini) were evaluated. Optimal performance was achieved at Mp/Ma = 3:1 and F/M = 1:1; increasing θ to 0.012 m<sup>2</sup> L<sup>−1</sup> allowed microalgal oxygen to sustain a PHA content of 51% (VSS), comparable to mechanical aeration. Under these conditions, specific energy consumption and process-related CO<sub>2</sub> emissions per unit PHA were reduced by 90% and 38%, respectively, with microalgal CO<sub>2</sub> fixation contributing 11%, rising to 16.7% at 30 mmol L<sup>−1</sup> inorganic carbon. This configuration offers a promising route toward low-energy, low-carbon PHA production.</div></div>","PeriodicalId":258,"journal":{"name":"Bioresource Technology","volume":"446 ","pages":"Article 134147"},"PeriodicalIF":9.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146109830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-27DOI: 10.1016/j.biortech.2026.134074
Weichao Li , Jingyu Li , Yun Wu , Meixuan Chen , Yangfan Fu , Wei Li , Shuang Liu , Jie Wang , Yingbo Chen
Artificial regulation of aerobic and anaerobic biofilm thickness is crucial for enhancing nitrogen removal efficiency of the membrane aerated biofilm reactor (MABR). In this study, conductive aeration membrane modules were fabricated by physical weaving technology to couple MABR with microbial electrochemistry for efficient nitrogen removal. Insulating grids of different thickness and conductive carbon fibers were woven onto the aeration membrane to form aerobic and anaerobic layers. When the total biofilm thickness reached 254 μm (150 μm aerobic layer and 104 μm anaerobic layer), the TN removal efficiency (89.49 ± 2.89 %) was optimal. 16S rRNA gene sequencing and metagenomics analysis confirmed that the aerobic and anaerobic layers in the biofilm were completely separated, but there was a synergistic effect in nitrogen removal. The composite cathode structure provides a mechanism for efficient spatial coupling between the aerobic and anaerobic layers, establishing a basis for regulating biofilm stratification.
{"title":"Artificial regulation of aerobic and anaerobic layers interface enhanced efficient nitrogen removal by weaving insulating grid and conductive carbon fiber in membrane aerated biofilm reactor","authors":"Weichao Li , Jingyu Li , Yun Wu , Meixuan Chen , Yangfan Fu , Wei Li , Shuang Liu , Jie Wang , Yingbo Chen","doi":"10.1016/j.biortech.2026.134074","DOIUrl":"10.1016/j.biortech.2026.134074","url":null,"abstract":"<div><div>Artificial regulation of aerobic and anaerobic biofilm thickness is crucial for enhancing nitrogen removal efficiency of the membrane aerated biofilm reactor (MABR). In this study, conductive aeration membrane modules were fabricated by physical weaving technology to couple MABR with microbial electrochemistry for efficient nitrogen removal. Insulating grids of different thickness and conductive carbon fibers were woven onto the aeration membrane to form aerobic and anaerobic layers. When the total biofilm thickness reached 254 μm (150 μm aerobic layer and 104 μm anaerobic layer), the TN removal efficiency (89.49 ± 2.89 %) was optimal. 16S rRNA gene sequencing and metagenomics analysis confirmed that the aerobic and anaerobic layers in the biofilm were completely separated, but there was a synergistic effect in nitrogen removal. The composite cathode structure provides a mechanism for efficient spatial coupling between the aerobic and anaerobic layers, establishing a basis for regulating biofilm stratification.</div></div>","PeriodicalId":258,"journal":{"name":"Bioresource Technology","volume":"445 ","pages":"Article 134074"},"PeriodicalIF":9.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146048103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-27DOI: 10.1016/j.biortech.2026.134104
Sofia Antic Gorrazzi, Sebastian Bonanni, Alejandro Javier Robledo, Diego Ariel Massazza
Biocathode performance is often constrained by low biomass accumulation on the electrode surface due to electrostatic repulsion between negatively charged cells and negatively polarized electrodes. A strategy known as polarity reversal is typically applied to overcome this limitation, initially growing bacteria under anodic conditions and subsequently switching the electrode polarity to cathodic. This approach requires substantial time and requires bacteria capable of bidirectional extracellular electron transfer. In this work, biocathode enhancement is achieved by suppressing electrostatic repulsion between bacteria and the electrode during adhesion stage, via the generation of a positive charge on the electrode through polarization above the potential of zero charge (PZC). Bacterial adhesion kinetics to electrodes polarized at different potentials and subsequent current generation were systematically investigated using a real-time, in situ approach. A fivefold increase in the number of irreversibly adhered bacteria during the first 90 min of polarization was observed on positively charged electrodes compared with negatively charged ones. Kinetic analysis revealed a 63% higher attachment rate in the former case. Subsequent biofilm formation was also enhanced, resulting in cathodic current densities higher than those typically reported for pure cultures. The effectiveness of this strategy was confirmed on gold and carbon-based graphite electrodes, indicating that the underlying mechanism is not material-specific. These findings demonstrate that biocathode development can be improved by a strategy termed here as Surface Charge-Induced Microbial Adhesion (SCIMA), providing a mechanistic framework for optimizing its performance in microbial electrochemical technologies.
{"title":"Enhanced biocathode performance through surface charge induced microbial adhesion","authors":"Sofia Antic Gorrazzi, Sebastian Bonanni, Alejandro Javier Robledo, Diego Ariel Massazza","doi":"10.1016/j.biortech.2026.134104","DOIUrl":"10.1016/j.biortech.2026.134104","url":null,"abstract":"<div><div>Biocathode performance is often constrained by low biomass accumulation on the electrode surface due to electrostatic repulsion between negatively charged cells and negatively polarized electrodes. A strategy known as polarity reversal is typically applied to overcome this limitation, initially growing bacteria under anodic conditions and subsequently switching the electrode polarity to cathodic. This approach requires substantial time and requires bacteria capable of bidirectional extracellular electron transfer. In this work, biocathode enhancement is achieved by suppressing electrostatic repulsion between bacteria and the electrode during adhesion stage, via the generation of a positive charge on the electrode through polarization above the potential of zero charge (PZC). Bacterial adhesion kinetics to electrodes polarized at different potentials and subsequent current generation were systematically investigated using a real-time, <em>in situ</em> approach. A fivefold increase in the number of irreversibly adhered bacteria during the first 90 min of polarization was observed on positively charged electrodes compared with negatively charged ones. Kinetic analysis revealed a 63% higher attachment rate in the former case. Subsequent biofilm formation was also enhanced, resulting in cathodic current densities higher than those typically reported for pure cultures. The effectiveness of this strategy was confirmed on gold and carbon-based graphite electrodes, indicating that the underlying mechanism is not material-specific. These findings demonstrate that biocathode development can be improved by a strategy termed here as Surface Charge-Induced Microbial Adhesion (SCIMA), providing a mechanistic framework for optimizing its performance in microbial electrochemical technologies.</div></div>","PeriodicalId":258,"journal":{"name":"Bioresource Technology","volume":"445 ","pages":"Article 134104"},"PeriodicalIF":9.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146048104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-26DOI: 10.1016/j.biortech.2026.134096
Yanfang Nie , Peng Huang , Yuxuan Li , Dingkang Hu , Kaixin Dong , Xuehong Zhang , Shengjie Yue , Hongbo Hu
The take-all disease of wheat poses a significant threat to global food security, underscoring the need for effective biocontrol agents. 2-Hydroxyphenazine (2-OH-PHZ) shows superior antifungal activity against the take-all disease of wheat pathogen over the commercial biopesticide phenazine-1-carboxylic acid (PCA). However, the biosynthetic production of 2-OH-PHZ is constrained by three critical limitations: the low hydroxylation efficiency of the flavin-dependent monooxygenase PhzO, inadequate intracellular supply of the precursor PCA, and the long fermentation process. To systematically address these interconnected challenges, we developed and implemented a Cofactor-Pathway-Process (CPP) engineering strategy in Pseudomonas chlororaphis LX24. First, cofactor engineering was employed to enhance PhzO activity by improving the supply of FADH2 and NADPH, which increased the hydroxylation efficiency from 22% to over 85%. Subsequently, pathway optimization was applied to overcome the precursor limitation by enhancing phenazine biosynthesis, which resulted in a 2.18-fold increase in 2-OH-PHZ accumulation to 988.25 mg/L. Combined with medium optimization and phzO overexpression, the titer of 2-OH-PHZ reached 2,291.56 mg/L in shake flasks and 2,663.12 mg/L in a 5-L bioreactor within 144 h, which is the highest production reported to date. Finally, a two-stage temperature-shift fermentation process was introduced to accelerate the decarboxylation of the intermediate 2-hydroxyphenazine-1-carboxylic acid, reducing the total fermentation time by 39 h and significantly improving process efficiency and sustainability. In summary, the integrated CPP strategy successfully overcomes multiple bottlenecks in 2-OH-PHZ biosynthesis, culminating in record-high productivity and underscoring its value as a versatile blueprint for the sustainable bioproduction of phenazine derivatives and other high-value natural products.
{"title":"A cofactor-pathway-process engineering strategy enables ultra-high 2-hydroxyphenazine production in Pseudomonas chlororaphis","authors":"Yanfang Nie , Peng Huang , Yuxuan Li , Dingkang Hu , Kaixin Dong , Xuehong Zhang , Shengjie Yue , Hongbo Hu","doi":"10.1016/j.biortech.2026.134096","DOIUrl":"10.1016/j.biortech.2026.134096","url":null,"abstract":"<div><div>The take-all disease of wheat poses a significant threat to global food security, underscoring the need for effective biocontrol agents. 2-Hydroxyphenazine (2-OH-PHZ) shows superior antifungal activity against the take-all disease of wheat pathogen over the commercial biopesticide phenazine-1-carboxylic acid (PCA). However, the biosynthetic production of 2-OH-PHZ is constrained by three critical limitations: the low hydroxylation efficiency of the flavin-dependent monooxygenase PhzO, inadequate intracellular supply of the precursor PCA, and the long fermentation process. To systematically address these interconnected challenges, we developed and implemented a Cofactor-Pathway-Process (CPP) engineering strategy in <em>Pseudomonas chlororaphis</em> LX24. First, cofactor engineering was employed to enhance PhzO activity by improving the supply of FADH<sub>2</sub> and NADPH, which increased the hydroxylation efficiency from 22% to over 85%. Subsequently, pathway optimization was applied to overcome the precursor limitation by enhancing phenazine biosynthesis, which resulted in a 2.18-fold increase in 2-OH-PHZ accumulation to 988.25 mg/L. Combined with medium optimization and <em>phzO</em> overexpression, the titer of 2-OH-PHZ reached 2,291.56 mg/L in shake flasks and 2,663.12 mg/L in a 5-L bioreactor within 144 h, which is the highest production reported to date. Finally, a two-stage temperature-shift fermentation process was introduced to accelerate the decarboxylation of the intermediate 2-hydroxyphenazine-1-carboxylic acid, reducing the total fermentation time by 39 h and significantly improving process efficiency and sustainability. In summary, the integrated CPP strategy successfully overcomes multiple bottlenecks in 2-OH-PHZ biosynthesis, culminating in record-high productivity and underscoring its value as a versatile blueprint for the sustainable bioproduction of phenazine derivatives and other high-value natural products.</div></div>","PeriodicalId":258,"journal":{"name":"Bioresource Technology","volume":"445 ","pages":"Article 134096"},"PeriodicalIF":9.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146048110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The siphon downflow hanging sponge (siphon DHS) was developed by integrating a siphon tube to create anoxic and anaerobic zones for enhanced denitrification. However, limited aerobic volume resulted in low nitrification rates. In this study, the siphon DHS reactor volume was modified (50:25:25 = aerobic: anoxic: anaerobic zones), and an influent bypass system (20 % to the anoxic zone) was integrated to enhance simultaneous nitrification–denitrification. The integrated design achieved 76 % nitrification and 20 % total nitrogen (TN) removal, representing a threefold improvement over conventional DHS while maintaining 86 % soluble chemical oxygen demand removal. The bypass system enhanced denitrification by providing sufficient organic matter to the anaerobic zone, while modified volume ratios enhanced nitrification. Microbial analysis revealed increased denitrifier abundance (Comamonadaceae: 14 %) and reduced nitrite accumulation. The integrated design achieved 44 % cost reduction for nitrogen removal while maintaining high treatment efficiency, providing a sustainable decentralized wastewater treatment solution.
{"title":"Siphon downflow hanging sponge reactor with influent bypass system for improved simultaneous nitrification–denitrification efficiency","authors":"Shehani Sharadha Maheepala , Masashi Hatamoto , Takahiro Watari , Takashi Yamaguchi","doi":"10.1016/j.biortech.2026.134051","DOIUrl":"10.1016/j.biortech.2026.134051","url":null,"abstract":"<div><div>The siphon downflow hanging sponge (siphon DHS) was developed by integrating a siphon tube to create anoxic and anaerobic zones for enhanced denitrification. However, limited aerobic volume resulted in low nitrification rates. In this study, the siphon DHS reactor volume was modified (50:25:25 = aerobic: anoxic: anaerobic zones), and an influent bypass system (20 % to the anoxic zone) was integrated to enhance simultaneous nitrification–denitrification. The integrated design achieved 76 % nitrification and 20 % total nitrogen (TN) removal, representing a threefold improvement over conventional DHS while maintaining 86 % soluble chemical oxygen demand removal. The bypass system enhanced denitrification by providing sufficient organic matter to the anaerobic zone, while modified volume ratios enhanced nitrification. Microbial analysis revealed increased denitrifier abundance (<em>Comamonadaceae</em>: 14 %) and reduced nitrite accumulation. The integrated design achieved 44 % cost reduction for nitrogen removal while maintaining high treatment efficiency, providing a sustainable decentralized wastewater treatment solution.</div></div>","PeriodicalId":258,"journal":{"name":"Bioresource Technology","volume":"445 ","pages":"Article 134051"},"PeriodicalIF":9.0,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146006544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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