Phycospheric Bacteria Alleviate the Stress of Erythromycin on <i>Auxenochlorella pyrenoidosa</i> by Regulating Nitrogen Metabolism

Macrolide pollution has attracted a great deal of attention because of its ecotoxic effects on microalgae, but the role of phycospheric bacteria under antibiotic stress remains unclear. This study explored the toxic effects of erythromycin (ERY) on the growth and nitrogen metabolism of <i>Auxe...

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Main Authors: Jiping Li, Ying Wang, Yuan Fang, Xingsheng Lyu, Zixin Zhu, Chenyang Wu, Zijie Xu, Wei Li, Naisen Liu, Chenggong Du, Yan Wang
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Plants
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Online Access:https://www.mdpi.com/2223-7747/14/1/121
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author Jiping Li
Ying Wang
Yuan Fang
Xingsheng Lyu
Zixin Zhu
Chenyang Wu
Zijie Xu
Wei Li
Naisen Liu
Chenggong Du
Yan Wang
author_facet Jiping Li
Ying Wang
Yuan Fang
Xingsheng Lyu
Zixin Zhu
Chenyang Wu
Zijie Xu
Wei Li
Naisen Liu
Chenggong Du
Yan Wang
author_sort Jiping Li
collection DOAJ
description Macrolide pollution has attracted a great deal of attention because of its ecotoxic effects on microalgae, but the role of phycospheric bacteria under antibiotic stress remains unclear. This study explored the toxic effects of erythromycin (ERY) on the growth and nitrogen metabolism of <i>Auxenochlorella pyrenoidosa</i>; then, it analyzed and predicted the effects of the composition and ecological function of phycospheric bacteria on microalgae under ERY stress. We found that 0.1, 1.0, and 10 mg/L ERY inhibited the growth and chlorophyll of microalgae, but the microalgae gradually showed enhanced growth abilities over the course of 21 days. As the exposure time progressed, the nitrate reductase activities of the microalgae gradually increased, but remained significantly lower than that of the control group at 21 d. NO<sub>3</sub><sup>−</sup> concentrations in all treatment groups decreased gradually and were consistent with microalgae growth. NO<sub>2</sub><sup>−</sup> concentrations in the three treatment groups were lower than those in the control group during ERY exposure over 21 d. ERY changed the community composition and diversity of phycospheric bacteria. The relative abundance of bacteria, such as <i>unclassified-f-Rhizobiaceae</i>, <i>Mesorhizobium</i>, <i>Sphingopyxis</i>, <i>Aquimonas</i>, and <i>Blastomonas</i>, varied to different degrees. Metabolic functions, such ABC transporters, the microbial metabolism in diverse environments, and the biosynthesis of amino acids, were significantly upregulated in the treatments of higher concentrations (1.0 and 10 mg/L). Higher concentrations of ERY significantly inhibited nitrate denitrification, nitrous oxide denitrification, nitrite denitrification, and nitrite and nitrate respiration. The findings of this study suggest that phycospheric bacteria alleviate antibiotic stress and restore the growth of microalgae by regulating nitrogen metabolism in the exposure system.
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spelling doaj-art-36785fec34ac4ae498cb990f60fb5ccd2025-01-10T13:19:49ZengMDPI AGPlants2223-77472025-01-0114112110.3390/plants14010121Phycospheric Bacteria Alleviate the Stress of Erythromycin on <i>Auxenochlorella pyrenoidosa</i> by Regulating Nitrogen MetabolismJiping Li0Ying Wang1Yuan Fang2Xingsheng Lyu3Zixin Zhu4Chenyang Wu5Zijie Xu6Wei Li7Naisen Liu8Chenggong Du9Yan Wang10Jiangsu Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection, Huaiyin Normal University, Huaian 223300, ChinaJiangsu Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection, Huaiyin Normal University, Huaian 223300, ChinaJiangsu Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection, Huaiyin Normal University, Huaian 223300, ChinaSchool of Life Sciences, Huaiyin Normal University, Huaian 223300, ChinaSchool of Life Sciences, Huaiyin Normal University, Huaian 223300, ChinaSchool of Life Sciences, Huaiyin Normal University, Huaian 223300, ChinaSchool of Life Sciences, Huaiyin Normal University, Huaian 223300, ChinaCollege of Ecology and Environment, Nanjing Forestry University, Longpan Road 159, Nanjing 210037, ChinaJiangsu Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection, Huaiyin Normal University, Huaian 223300, ChinaJiangsu Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection, Huaiyin Normal University, Huaian 223300, ChinaJiangsu Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection, Huaiyin Normal University, Huaian 223300, ChinaMacrolide pollution has attracted a great deal of attention because of its ecotoxic effects on microalgae, but the role of phycospheric bacteria under antibiotic stress remains unclear. This study explored the toxic effects of erythromycin (ERY) on the growth and nitrogen metabolism of <i>Auxenochlorella pyrenoidosa</i>; then, it analyzed and predicted the effects of the composition and ecological function of phycospheric bacteria on microalgae under ERY stress. We found that 0.1, 1.0, and 10 mg/L ERY inhibited the growth and chlorophyll of microalgae, but the microalgae gradually showed enhanced growth abilities over the course of 21 days. As the exposure time progressed, the nitrate reductase activities of the microalgae gradually increased, but remained significantly lower than that of the control group at 21 d. NO<sub>3</sub><sup>−</sup> concentrations in all treatment groups decreased gradually and were consistent with microalgae growth. NO<sub>2</sub><sup>−</sup> concentrations in the three treatment groups were lower than those in the control group during ERY exposure over 21 d. ERY changed the community composition and diversity of phycospheric bacteria. The relative abundance of bacteria, such as <i>unclassified-f-Rhizobiaceae</i>, <i>Mesorhizobium</i>, <i>Sphingopyxis</i>, <i>Aquimonas</i>, and <i>Blastomonas</i>, varied to different degrees. Metabolic functions, such ABC transporters, the microbial metabolism in diverse environments, and the biosynthesis of amino acids, were significantly upregulated in the treatments of higher concentrations (1.0 and 10 mg/L). Higher concentrations of ERY significantly inhibited nitrate denitrification, nitrous oxide denitrification, nitrite denitrification, and nitrite and nitrate respiration. The findings of this study suggest that phycospheric bacteria alleviate antibiotic stress and restore the growth of microalgae by regulating nitrogen metabolism in the exposure system.https://www.mdpi.com/2223-7747/14/1/121antibioticsmicroalgaenitrate reductionmicroalgae–bacteria consortium
spellingShingle Jiping Li
Ying Wang
Yuan Fang
Xingsheng Lyu
Zixin Zhu
Chenyang Wu
Zijie Xu
Wei Li
Naisen Liu
Chenggong Du
Yan Wang
Phycospheric Bacteria Alleviate the Stress of Erythromycin on <i>Auxenochlorella pyrenoidosa</i> by Regulating Nitrogen Metabolism
Plants
antibiotics
microalgae
nitrate reduction
microalgae–bacteria consortium
title Phycospheric Bacteria Alleviate the Stress of Erythromycin on <i>Auxenochlorella pyrenoidosa</i> by Regulating Nitrogen Metabolism
title_full Phycospheric Bacteria Alleviate the Stress of Erythromycin on <i>Auxenochlorella pyrenoidosa</i> by Regulating Nitrogen Metabolism
title_fullStr Phycospheric Bacteria Alleviate the Stress of Erythromycin on <i>Auxenochlorella pyrenoidosa</i> by Regulating Nitrogen Metabolism
title_full_unstemmed Phycospheric Bacteria Alleviate the Stress of Erythromycin on <i>Auxenochlorella pyrenoidosa</i> by Regulating Nitrogen Metabolism
title_short Phycospheric Bacteria Alleviate the Stress of Erythromycin on <i>Auxenochlorella pyrenoidosa</i> by Regulating Nitrogen Metabolism
title_sort phycospheric bacteria alleviate the stress of erythromycin on i auxenochlorella pyrenoidosa i by regulating nitrogen metabolism
topic antibiotics
microalgae
nitrate reduction
microalgae–bacteria consortium
url https://www.mdpi.com/2223-7747/14/1/121
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