Effects of Eucalyptus Essential Oil on Growth, Immunological Indicators, Disease Resistance, Intestinal Morphology and Gut Microbiota in <i>Trachinotus ovatus</i>

Essential oils serve as potential additives that can enhance immune respons and disease resistance and regulate the gut microbiota of fish. Here, this research aims to identify the impacts of eucalyptus essential oil (EEO) on growth, liver antioxidative and immune parameters, resistance to <i>...

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Main Authors: Ziyang Lin, Shengzhe An, Chuanpeng Zhou, Yaqi Chen, Zhenchuang Gao, Juan Feng, Heizhao Lin, Pengwei Xun, Wei Yu
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Microorganisms
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Online Access:https://www.mdpi.com/2076-2607/13/3/537
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author Ziyang Lin
Shengzhe An
Chuanpeng Zhou
Yaqi Chen
Zhenchuang Gao
Juan Feng
Heizhao Lin
Pengwei Xun
Wei Yu
author_facet Ziyang Lin
Shengzhe An
Chuanpeng Zhou
Yaqi Chen
Zhenchuang Gao
Juan Feng
Heizhao Lin
Pengwei Xun
Wei Yu
author_sort Ziyang Lin
collection DOAJ
description Essential oils serve as potential additives that can enhance immune respons and disease resistance and regulate the gut microbiota of fish. Here, this research aims to identify the impacts of eucalyptus essential oil (EEO) on growth, liver antioxidative and immune parameters, resistance to <i>Streptococcus iniae</i>, intestinal morphology and gut microbiota in <i>Trachinotus ovatus</i>. All fish (initial weight: 26.87 ± 0.30 g) were randomly allocated to 12 floating cages (2.0 × 2.0 × 2.0 m<sup>3</sup>) with each cage containing 100 fish and fed for 30 days. Four diets were manufactured with the supplementation of varying levels of EEO (control and 5.0, 10.0, and 15.0 mL/kg) and were named CG, EEO1, EEO2 and EEO3, respectively. The results showed that EEO1 and EEO2 diets significantly increased WGR, thickness of the intestinal muscle layer, and the ratio of villus height to crypt depth (V/C), while decreasing the intestinal crypt depth of <i>T. ovatus</i> (<i>p</i> < 0.05). Significantly increased activities of SOD and CAT and significantly reduced MDA levels were present in the EEO1 and/or EEO2 groups (<i>p</i> < 0.05). Moreover, the mRNA levels of <i>nrf2</i>, <i>HO-1</i>, <i>GSH-Px</i>, <i>SOD</i>, <i>C4</i> and <i>GR</i> genes were significantly upregulated and the expression of <i>keap1</i> and <i>HSP70</i> genes were significantly downregulated within the EEO1 and EEO2 groups (<i>p</i> < 0.05). After challenge with <i>S. iniae B240703</i> for 24 h, the bacterial load for five organs in the EEO2 group was less than that in the CG group (<i>p</i> < 0.05). In addition, the fish fed EEO1 and/or EEO2 diets had significantly lower abundances of pathogenic bacteria (<i>Proteobacteria</i>, <i>Planctomycetota</i>, <i>Burkholderia-Caballeronia-Paraburkholderia</i>, <i>Pseudomonas</i> and <i>Blastopirellula</i>) and a higher beneficial bacteria proportion (<i>Firmicutes</i>) than those fed the CG diets (<i>p</i> < 0.05). In conclusion, a moderate dietary m EO level (5.0~10.0 mL/kg) improved the growth and gut morphology, promoted liver immune response, enhanced resistance to <i>S. iniae</i> and modulated the gut microbiota of <i>T. ovatus</i>.
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spelling doaj-art-b9ba0a05d4524ced972fc4df5b06cb8e2025-08-20T02:42:27ZengMDPI AGMicroorganisms2076-26072025-02-0113353710.3390/microorganisms13030537Effects of Eucalyptus Essential Oil on Growth, Immunological Indicators, Disease Resistance, Intestinal Morphology and Gut Microbiota in <i>Trachinotus ovatus</i>Ziyang Lin0Shengzhe An1Chuanpeng Zhou2Yaqi Chen3Zhenchuang Gao4Juan Feng5Heizhao Lin6Pengwei Xun7Wei Yu8School of Fisheries, Xinyang Agriculture and Forestry University, Xinyang 464000, ChinaKey Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, ChinaKey Laboratory of Efficient Utilization and Processing of Marine Fishery Resources of Hainan Province, Sanya Tropical Fisheries Research Institute, Sanya 572426, ChinaSchool of Fisheries, Xinyang Agriculture and Forestry University, Xinyang 464000, ChinaSchool of Fisheries, Xinyang Agriculture and Forestry University, Xinyang 464000, ChinaKey Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, ChinaKey Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, ChinaSchool of Fisheries, Xinyang Agriculture and Forestry University, Xinyang 464000, ChinaKey Laboratory of Efficient Utilization and Processing of Marine Fishery Resources of Hainan Province, Sanya Tropical Fisheries Research Institute, Sanya 572426, ChinaEssential oils serve as potential additives that can enhance immune respons and disease resistance and regulate the gut microbiota of fish. Here, this research aims to identify the impacts of eucalyptus essential oil (EEO) on growth, liver antioxidative and immune parameters, resistance to <i>Streptococcus iniae</i>, intestinal morphology and gut microbiota in <i>Trachinotus ovatus</i>. All fish (initial weight: 26.87 ± 0.30 g) were randomly allocated to 12 floating cages (2.0 × 2.0 × 2.0 m<sup>3</sup>) with each cage containing 100 fish and fed for 30 days. Four diets were manufactured with the supplementation of varying levels of EEO (control and 5.0, 10.0, and 15.0 mL/kg) and were named CG, EEO1, EEO2 and EEO3, respectively. The results showed that EEO1 and EEO2 diets significantly increased WGR, thickness of the intestinal muscle layer, and the ratio of villus height to crypt depth (V/C), while decreasing the intestinal crypt depth of <i>T. ovatus</i> (<i>p</i> < 0.05). Significantly increased activities of SOD and CAT and significantly reduced MDA levels were present in the EEO1 and/or EEO2 groups (<i>p</i> < 0.05). Moreover, the mRNA levels of <i>nrf2</i>, <i>HO-1</i>, <i>GSH-Px</i>, <i>SOD</i>, <i>C4</i> and <i>GR</i> genes were significantly upregulated and the expression of <i>keap1</i> and <i>HSP70</i> genes were significantly downregulated within the EEO1 and EEO2 groups (<i>p</i> < 0.05). After challenge with <i>S. iniae B240703</i> for 24 h, the bacterial load for five organs in the EEO2 group was less than that in the CG group (<i>p</i> < 0.05). In addition, the fish fed EEO1 and/or EEO2 diets had significantly lower abundances of pathogenic bacteria (<i>Proteobacteria</i>, <i>Planctomycetota</i>, <i>Burkholderia-Caballeronia-Paraburkholderia</i>, <i>Pseudomonas</i> and <i>Blastopirellula</i>) and a higher beneficial bacteria proportion (<i>Firmicutes</i>) than those fed the CG diets (<i>p</i> < 0.05). In conclusion, a moderate dietary m EO level (5.0~10.0 mL/kg) improved the growth and gut morphology, promoted liver immune response, enhanced resistance to <i>S. iniae</i> and modulated the gut microbiota of <i>T. ovatus</i>.https://www.mdpi.com/2076-2607/13/3/537eucalyptus essential oilimmunological parametersintestinal microfloradisease resistance<i>Trachinotus ovatus</i>
spellingShingle Ziyang Lin
Shengzhe An
Chuanpeng Zhou
Yaqi Chen
Zhenchuang Gao
Juan Feng
Heizhao Lin
Pengwei Xun
Wei Yu
Effects of Eucalyptus Essential Oil on Growth, Immunological Indicators, Disease Resistance, Intestinal Morphology and Gut Microbiota in <i>Trachinotus ovatus</i>
Microorganisms
eucalyptus essential oil
immunological parameters
intestinal microflora
disease resistance
<i>Trachinotus ovatus</i>
title Effects of Eucalyptus Essential Oil on Growth, Immunological Indicators, Disease Resistance, Intestinal Morphology and Gut Microbiota in <i>Trachinotus ovatus</i>
title_full Effects of Eucalyptus Essential Oil on Growth, Immunological Indicators, Disease Resistance, Intestinal Morphology and Gut Microbiota in <i>Trachinotus ovatus</i>
title_fullStr Effects of Eucalyptus Essential Oil on Growth, Immunological Indicators, Disease Resistance, Intestinal Morphology and Gut Microbiota in <i>Trachinotus ovatus</i>
title_full_unstemmed Effects of Eucalyptus Essential Oil on Growth, Immunological Indicators, Disease Resistance, Intestinal Morphology and Gut Microbiota in <i>Trachinotus ovatus</i>
title_short Effects of Eucalyptus Essential Oil on Growth, Immunological Indicators, Disease Resistance, Intestinal Morphology and Gut Microbiota in <i>Trachinotus ovatus</i>
title_sort effects of eucalyptus essential oil on growth immunological indicators disease resistance intestinal morphology and gut microbiota in i trachinotus ovatus i
topic eucalyptus essential oil
immunological parameters
intestinal microflora
disease resistance
<i>Trachinotus ovatus</i>
url https://www.mdpi.com/2076-2607/13/3/537
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