JOURNAL OF ENVIRONMENTAL MANAGEMENT
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2025
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IF 8.4
Zhuocheng Wei,Bin Zhang,Rui Xu,Haoling Li,Acong Chen,Chaohai Wei,Haizhen Wu
Thiocyanate (SCN − ) is a highly toxic reducing inorganic compound commonly found in various nitrogen-rich wastewater and is also a promising electron donor for mixotrophic denitrification. However, its extent of involvement in mixotrophic denitrification under conditions of carbon limitation or excess remains unclear. In this study, five reactors were constructed to investigate the participation and microbial mechanisms of SCN − in mixotrophic denitrification under high C/N and low C/N conditions. The results showed that under low C/N conditions, SCN⁻ synergizes with organic electron donors to enhance denitrification, with mixotrophic systems exhibiting higher electron utilization efficiency and achieving 1.12 times the TN removal rate of autotrophic and heterotrophic systems combined. Under high C/N conditions, an ample supply of electron donors achieve 100% nitrate removal; however, SCN⁻ also participates in denitrification, competing with organic electron donors for NO 3 − -N, which leads to the waste of organic matter. Additionally, high-throughput sequencing revealed that under low C/N mixotrophic conditions, SCN⁻ effectively promoted the growth of SCN⁻-degrading microorganisms such as Thiobacillus , with its abundance increasing from 0% to 8.86%, approximately 1.85 times higher than under autotrophic conditions. This enhancement strengthened the sulfur and nitrogen metabolic capabilities of the microbial community, enabling the system to utilize SCN − more fully for denitrification. This study provides novel insights for reducing the addition of external organic matter to nitrogen-rich wastewater containing SCN − , offering theoretical and technical support for energy-saving and emission reduction in denitrification processes of actual industrial wastewater treatment.
研究领域:
环境科学
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微生物学
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DOI
PubMed
高影响因子
BIORESOURCE TECHNOLOGY
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2019
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IF 6.669
Zhuqiu Sun,Bowen Pang,Jinying Xi,Hong-Ying Hu
Eight species of mixotrophic sulfide oxidizing bacteria (SOB) were isolated from activated sludge and identified using 16S rRNA sequence analysis. The effects of organic substances, dissolved oxygen (DO) and nitrate on sulfide oxidation and bacterial growth were studied in this work. The results showed that Paracoccus sp . (N1), Pseudomonas sp. (N2) and Pseudomonas sp. (S4) have strong adaptability to environments with low DO and high concentrations of organic substance. An SOB additive was optimized in artificial, odorous water. The optimized SOB additive is a blend of 80% N1 and 20% N2 bacteria solution with absorbance equal to 0.5 at a wavelength of 600 nm (OD 600 ), and the optimal dose of the additive is 20 ml/L. Oxidation-reduction potential (ORP), ammonia-nitrogen (NH 3 -N) and released H 2 S in an odorous river were measured with and without SOB additive, and the results indicated that the optimized SOB additive has excellent performance for odorous river bioremediation.
研究领域:
环境微生物学
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水处理工程
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DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
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2023
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IF 9.8
Chuanqi Jian,Yanru Hao,Rentao Liu,Xiaochen Qi,Minmin Chen,Na Liu
Heterotrophic sulfur-based autotrophic denitrification is a promising biological denitrification technology for low COD/TN (C/N) wastewater due to its high efficiency and low cost. Compared to the conventional autotrophic denitrification process driven by elemental sulfur, the presence of polysulfide in the system can promote high-speed nitrogen removal. However, autotrophic denitrification mediated by polysulfide has not been reported. This study investigated the denitrification performance and microbial metabolic mechanism of heterotrophic denitrification, sulfur-based autotrophic denitrification, and mixotrophic denitrification using lime sulfur and butanediol as electron donors. When the influent C/N was 1, the total nitrogen removal efficiency of the mixotrophic denitrification process was 1.67 and 1.14 times higher than that of the heterotrophic and sulfur-based autotrophic denitrification processes, respectively. Microbial community alpha diversity and principal component analysis indicated different electron donors lead to different evolutionary directions in microbial communities. Metagenomic analysis showed the enriched denitrifying bacteria ( Thauera , Pseudomonas , and Pseudoxanthomonas ), dissimilatory nitrate reduction to ammonia bacteria ( Hydrogenophaga ), and sulfur oxidizing bacteria ( Thiobacillus ) can stably support nitrate reduction. Analysis of metabolic pathways revealed that complete denitrification, dissimilatory nitrate reduction to ammonia, and sulfur disproportionation are the main pathways of the N and S cycle. This study demonstrates the feasibility of a mixotrophic denitrification process driven by a combination of lime sulfur and butanediol as a cost-effective solution for treating nitrogen pollution in low C/N wastewater and elucidates the N and S metabolic pathways involved.
研究领域:
环境工程
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微生物学
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DOI
PubMed
高影响因子
Journal of Water Process Engineering
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2025
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IF 6.7
Ze-Tong Feng,Yan Yu,Ying-Jun Sun,Jia-Min Zhou,Xin Ma,Fei Ding,Yi-Liu Zheng,Ren-Cun Jin,Chun-Qiang Shen,Qian-Qian Zhang
This study systematically evaluated the effects of intermittent versus continuous addition of zero-valent iron (ZVI) as exogenous enhancers on nitrogen removal performance in denitrification systems. Results shown that under carbon-to‑nitrogen ratios (C/N) was 3, 2, and 1, continuous addition of ZVI significantly improved total nitrogen removal efficiency (TNRE) by 8.57 %, 19.34 %, and 11.45 %, respectively, compared to the control system. Concurrently, extracellular polymeric substance (EPS) production increased by 32.43 %, 62.91 %, and 35.93 %, to that of intermittent ZVI addition system at the same phases. The continuous ZVI-added system enriched more mixotrophic denitrification bacteria and increased soluble iron ion concentrations through EPS-mediated electron shuttling and endogenous protection mechanisms. While, under C/N was 0, the TNRE in continuously ZVI-added system reduced to 8.3 ± 3.24 % due to iron mineral crust formation. Specifically, the TNRE of system with intermittent addition of ZVI stabilized at 17.03 ± 3.24 %, enriched more autotrophic denitrification bacteria and avoided excessive accumulation of iron oxides. Therefore, this experiment provided new insights into the stable operation of the ZVI-enhanced denitrification process for treating low C/N wastewater.
研究领域:
环境科学
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微生物学
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产品关联
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
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2023
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IF 9.8
Jiahui Cheng,Jin Jin,Ziyi Deng,Zhou Yang,Lu Zhang
Herbicide pollution is a main form of water pollution. As a result of additional harms to other non-target organisms, it threatens the function and structure of ecosystems. Previous researches mainly focused on the assessment of the toxicity and ecological effect of herbicides on monotrophic organisms. Responses of mixotrophs as an important component of functional groups are rarely understood in contaminated waters, although their metabolic plasticity and unique ecological functions in ecosystem stability are a major concern. This work aimed to investigate the trophic plasticity of mixotrophic organisms in atrazine-contaminated waters, and a primarily heterotrophic Ochromonas was used as the tested organism. Results showed that the herbicide atrazine significantly inhibited the photochemical activity and impaired the photosynthetic machine of Ochromonas , and photosynthesis activated by light was sensitive to atrazine. However, phagotrophy was unaffected by atrazine and closely correlated with growth rate, indicating that heterotrophy helped population maintenance during herbicide exposure. Mixotrophic Ochromonas upregulated the gene expression level involved in photosynthesis, energy synthesis, and antioxidation to adapt to increasing atrazine after long-term exposure. Compared with bacterivory, herbivory increased atrazine tolerance of photosynthesis under mixotrophic status. This study systematically illustrated the mechanism by which mixotrophic Ochromonas respond to the herbicide atrazine at population, photochemical activity, morphology, and gene expression levels and demonstrated the potential effect of atrazine on the metabolic flexibility and ecological niches of mixotrophs. These findings will provide important theoretical reference for governance and management decision-making in contaminated environments.
研究领域:
生态学
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环境科学
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分子生物学
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DOI
PubMed
高影响因子
ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY
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2014
·Vol. 67
·期 4
·593-600
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IF 1.96
Zhang Weiguo,Liu Min,Zhang Peiliang,Yu Fugen,Lu Shan,Li Pengfu,Zhou Junying
Only limited information is available on herbicide toxicity to algae under mixotrophic conditions. In the present study, we studied the effects of the herbicide paraquat on growth, photosynthetic pigments, antioxidant enzymes, and gene expression in Chlorella pyrenoidosa under mixotrophic compared with autotrophic conditions. The mean measured exposure concentrations of paraquat under mixotrophic and autotrophic conditions were in the range of 0.3–3.4 and 0.6–3.6 μM, respectively. Exposure to paraquat for 72 h under both autotrophic and mixotrophic conditions induced decreased growth and chlorophyll (Chl) content, increased superoxide dismutase and peroxidase activities, and decreased transcript abundances of three photosynthesis-related genes (light-independent protochlorophyllide reductase subunit, photosystem II protein D1, and ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit [ rbc L]). Compared with autotrophic conditions, the inhibition percentage of growth rate under mixotrophic conditions was lower at 0.8 μM paraquat, whereas it was greater at 1.8 and 3.4 μM paraquat. With exposure to 0.8–3.4 μM paraquat, the inhibition rates of Chl a and b content under mixotrophic conditions (43.1–52.4 % and 54.6–59.7 %, respectively) were greater compared with autotrophic conditions, whereas the inhibition rate of rbc L gene transcription under mixotrophic conditions (35.7–44.0 %) was lower. These data showed that similar to autotrophic conditions, paraquat affected the activities of antioxidant enzymes and decreased Chl synthesis and transcription of photosynthesis-related genes in C. pyrenoidosa under mixotrophic conditions, but a differential susceptibility to paraquat toxicity occurred between autotrophically versus mixotrophically grown cells.
研究领域:
环境科学
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植物生理学
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DOI
PubMed
高影响因子
WATER RESEARCH
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2020
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IF 9.13
Cong Huang,Qian Liu,Zhi-Ling Li,Xiao-dan Ma,Ya-Nan Hou,Nan-Qi Ren,Ai-Jie Wang
The denitrification desulfurization system can be used to remediate wastewater containing carbon, nitrogen, and sulfur. However, the relationship between autotrophic and heterotrophic bacteria remains poorly understood. To better understand the roles and relations of core bacteria, an expanded granular sludge bed (EGSB) reactor was continuously operated under autotrophic (stage I), heterotrophic (stage II) and mixotrophic (stages III–VII) conditions with a 490-day period. Stage IV represented the excellent S 0 recovery rate (69.5%). The different trophic conditions caused the obvious succession of dominant bacterial genera. Autotrophic environment (stage I) enriched mostly Thiobacillus , and heterotrophic environment (stage II) was dominated with Azoarcus and Pseudomonas. Thauera, Arcobacter and Azoarcus became the predominant genera under mixotrophic conditions (stage III-VII). Strains belonged to these core genera were further isolated, and all seven isolates were confirmed with denitrifying sulfur oxidation capacity. Heterotrophic strain HDD1 (genus of Thauera ) possessed both the highest sulfide degradation and S 0 recovery rates. Expression levels of cbbM and gltA genes were positively related with the autotrophic and heterotrophic conditions, respectively. NirK gene was highly expressed between log 3.7–log 4.3 during the entire run. Expression of both sqr and soxB genes were closely related with sulfur conversion. More than 57.5% of S 0 recovery rate could be obtained as sqr gene expression was greater than log 3.2, and while, sulfate was the primary form as soxB gene expression higher than log 3.9. The correlation between core microbial genera was very low from network, indicating a complex and non-specific mutualistic network between bacterial functional groups under each nutrient condition, and a stable coexistence state was possibly formed through utilizing each the secondary or waste metabolites in the mixotrophic conditions. This relationship was beneficial to the stability of the microbial community structure in the denitrification desulfurization system.
研究领域:
环境微生物学
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废水处理
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生物技术
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DOI
PubMed
高影响因子
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