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<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" article-type="research-article" dtd-version="1.2" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">Ecological genetics</journal-id><journal-title-group><journal-title xml:lang="en">Ecological genetics</journal-title><trans-title-group xml:lang="ru"><trans-title>Экологическая генетика</trans-title></trans-title-group></journal-title-group><issn publication-format="print">1811-0932</issn><issn publication-format="electronic">2411-9202</issn><publisher><publisher-name xml:lang="en">Eco-Vector</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">679052</article-id><article-id pub-id-type="doi">10.17816/ecogen679052</article-id><article-id pub-id-type="edn">PWKCXL</article-id><article-categories><subj-group subj-group-type="toc-heading" xml:lang="en"><subject>Ecosystems metagenomics</subject></subj-group><subj-group subj-group-type="toc-heading" xml:lang="ru"><subject>Метагеномика экосистем</subject></subj-group><subj-group subj-group-type="article-type"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title xml:lang="en">Gut microbiota of healthy and saprolegniosis-affected whitefish (<italic>Coregonus nasus</italic>) producers in aquaculture</article-title><trans-title-group xml:lang="ru"><trans-title>Микробиота кишечника производителей сиговых на примере <italic>Coregonus nasus</italic> в аквакультуре в нерестовый период</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0001-7583-864X</contrib-id><contrib-id contrib-id-type="spin">5468-2834</contrib-id><name-alternatives><name xml:lang="en"><surname>Vylka</surname><given-names>Maxim M.</given-names></name><name xml:lang="ru"><surname>Вылка</surname><given-names>Максим Михайлович</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Saint Petersburg branch</p></bio><bio xml:lang="ru"><p>Санкт-Петербургский филиал («ГосНИОРХ» им. Л.С. Берга)</p></bio><email>vylka.maxim@yandex.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0003-0418-8218</contrib-id><contrib-id contrib-id-type="spin">9187-6075</contrib-id><name-alternatives><name xml:lang="en"><surname>Lyutikov</surname><given-names>Anatoliy A.</given-names></name><name xml:lang="ru"><surname>Лютиков</surname><given-names>Анатолий Анатольевич</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Cand. Sci. (Biology), Saint Petersburg branch</p></bio><bio xml:lang="ru"><p>канд. биол. наук, Санкт-Петербургский филиал («ГосНИОРХ» им. Л.С. Берга)</p></bio><email>tokmo@mail.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0001-9970-403X</contrib-id><contrib-id contrib-id-type="spin">4202-4471</contrib-id><name-alternatives><name xml:lang="en"><surname>Dyakova</surname><given-names>Svetlana A.</given-names></name><name xml:lang="ru"><surname>Дьякова</surname><given-names>Светлана Александровна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Cand. Sci. (Biology), Saint Petersburg branch</p></bio><bio xml:lang="ru"><p>канд. биол. наук, Санкт-Петербургский филиал («ГосНИОРХ» им. Л.С. Берга)</p></bio><email>dyakova@niorh.vniro.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-9030-8820</contrib-id><contrib-id contrib-id-type="spin">8355-8091</contrib-id><name-alternatives><name xml:lang="en"><surname>Karlov</surname><given-names>Denis S.</given-names></name><name xml:lang="ru"><surname>Карлов</surname><given-names>Денис Сергеевич</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Cand. Sci. (Biology)</p></bio><bio xml:lang="ru"><p>канд. биол. наук</p></bio><email>ds.karlov@arriam.ru</email><xref ref-type="aff" rid="aff2"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="spin">6849-0483</contrib-id><name-alternatives><name xml:lang="en"><surname>Zhukova</surname><given-names>Alina A.</given-names></name><name xml:lang="ru"><surname>Жукова</surname><given-names>Алина Александровна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Cand. Sci. (Biology), Saint Petersburg branch</p></bio><bio xml:lang="ru"><p>канд. биол. наук, Санкт-Петербургский филиал («ГосНИОРХ» им. Л.С. Берга)</p></bio><email>gatteriyagreen@gmail.com</email><xref ref-type="aff" rid="aff1"/><xref ref-type="aff" rid="aff3"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0003-0385-2463</contrib-id><contrib-id contrib-id-type="spin">7198-3170</contrib-id><name-alternatives><name xml:lang="en"><surname>Golotin</surname><given-names>Vasily A.</given-names></name><name xml:lang="ru"><surname>Голотин</surname><given-names>Василий Александрович</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Cand. Sci. (Biology), Saint Petersburg branch</p></bio><bio xml:lang="ru"><p>канд. биол. наук, Санкт-Петербургский филиал («ГосНИОРХ» им. Л.С. Берга)</p></bio><email>golotin@bk.ru</email><xref ref-type="aff" rid="aff1"/></contrib></contrib-group><aff-alternatives id="aff1"><aff><institution xml:lang="en">Russian Federal Research Institute of Fisheries and Oceanography</institution></aff><aff><institution xml:lang="ru">Всероссийский научно-исследовательский институт рыбного хозяйства и океанографии</institution></aff></aff-alternatives><aff-alternatives id="aff2"><aff><institution xml:lang="en">All-Russian Research Institute of Agricultural Microbiology</institution></aff><aff><institution xml:lang="ru">Всероссийский научно-исследовательский институт сельскохозяйственной микробиологии</institution></aff></aff-alternatives><aff-alternatives id="aff3"><aff><institution xml:lang="en">Herzen State Pedagogical University of Russia</institution></aff><aff><institution xml:lang="ru">Российский государственный педагогический университет им. А.И. Герцена</institution></aff></aff-alternatives><pub-date date-type="preprint" iso-8601-date="2025-06-26" publication-format="electronic"><day>26</day><month>06</month><year>2025</year></pub-date><pub-date date-type="pub" iso-8601-date="2025-12-15" publication-format="electronic"><day>15</day><month>12</month><year>2025</year></pub-date><volume>23</volume><issue>3</issue><issue-title xml:lang="en"/><issue-title xml:lang="ru"/><fpage>225</fpage><lpage>234</lpage><history><date date-type="received" iso-8601-date="2025-05-01"><day>01</day><month>05</month><year>2025</year></date><date date-type="accepted" iso-8601-date="2025-05-29"><day>29</day><month>05</month><year>2025</year></date></history><permissions><copyright-statement xml:lang="en">Copyright ©; 2025, Eco-Vector</copyright-statement><copyright-statement xml:lang="ru">Copyright ©; 2025, Эко-Вектор</copyright-statement><copyright-year>2025</copyright-year><copyright-holder xml:lang="en">Eco-Vector</copyright-holder><copyright-holder xml:lang="ru">Эко-Вектор</copyright-holder><license><ali:license_ref xmlns:ali="http://www.niso.org/schemas/ali/1.0/">https://creativecommons.org/licenses/by-nc-nd/4.0/</ali:license_ref></license></permissions><self-uri xlink:href="https://journals.eco-vector.com/ecolgenet/article/view/679052">https://journals.eco-vector.com/ecolgenet/article/view/679052</self-uri><abstract xml:lang="en"><p><bold>Background:</bold> The gut microbiota is one of the main factor influencing the immunity of animals, including fish. Understanding the taxonomic and quantitative composition of the microbiota may hold the key to enhance fish immunity against bacterial and fungal infections in aquaculture that potentially could optimize fish farm management.</p> <p><bold>Aim:</bold> The aim of this work is to determine the taxonomic composition differences of the gut microbiome between healthy and Saprolegnia-affected breeders of broad whitefish (Coregonus nasus, Pallas, 1776) under industrial farming conditions using high-throughput sequencing.</p> <p><bold>Methods:</bold> The gut microbiota composition was analyzed using NGS sequencing and the methods of bioinformatics. Hematological profiling was performed using standard microscopy-based techniques.</p> <p><bold>Results:</bold> Preliminary data from high-throughput molecular genetic screening of the gut microbiota diversity in healthy and Saprolegnia-affected C. nasus individuals during the spawning period are presented. The hematological profile reliably distinguishes clinical differences between healthy fish and those infected with Saprolegnia. Differences in the taxonomic and quantitative composition of the gut microbiomes in C. nasus has been shown.</p> <p><bold>Conclusion:</bold> Fish with the clinical signs of saprolegniosis showed a dominance of the phylum Proteobacteria (on average of 45.3%). There were comparable propotions (26.67–30.27%) of Proteobacteria, Firmicutes, and Actinobacteriota observed in healthy fish.</p></abstract><trans-abstract xml:lang="ru"><p><bold>Обоснование.</bold> Кишечная микробиота — один из главных факторов иммунитета животных, в том числе рыб. Понимание таксономического и количественного состава микробиоты может являться ключом к усилению иммунитета рыб к бактериальным и грибковым инфекциям в аквакультуре и в перспективе позволит оптимизировать процессы управления рыбным хозяйством.</p> <p><bold>Цель исследования.</bold> Определить различия таксономического состава кишечного микробиома здоровых и пораженных сапролегниозом производителей чира (Coregonus nasus, Pallas, 1776) в условиях индустриального выращивания с помощью высокопроизводительного секвенирования.</p> <p><bold>Методы.</bold> Состав микробиоты кишечника определяли методами секвенирования нового поколения (NGS) и биоинформатики. Гематологический анализ проводили стандартными методами с использованием микроскопии.</p> <p><bold>Результаты.</bold> Представлены предварительные данные высокопроизводительного молекулярно-генетического скрининга видового разнообразия кишечной микробиоты здоровых и пораженных сапролегниозом особей чира C. nasus в период нереста. Показан гематологический профиль, позволяющий достоверно установить клинические индивидуальные различия здоровых рыб и рыб с поражениями сапролегнией. Определены различия в таксономическом и количественном составе кишечного микробиома чира.</p> <p><bold>Заключение. </bold>Для рыб с клиническими признаками сапролегниоза определено доминирование бактерий филы Proteobacteria (в среднем 45,3%). У здоровых рыб доли представителей филы Proteobacteria, Firmicutes и Actinobacteriota были близки (26,67–30,27%).</p></trans-abstract><kwd-group xml:lang="en"><kwd>saprolegniosis</kwd><kwd>hematology</kwd><kwd>Coregonus nasus</kwd><kwd>NGS sequencing</kwd><kwd>gut microbiota</kwd></kwd-group><kwd-group xml:lang="ru"><kwd>сапролегниоз</kwd><kwd>гематология</kwd><kwd>Coregonus nasus</kwd><kwd>NGS-секвенирование</kwd><kwd>микробиота кишечника</kwd></kwd-group><funding-group/></article-meta></front><body></body><back><ref-list><ref id="B1"><label>1.</label><mixed-citation>Bene C, Arthur R, Norbury H, et al. Contribution of fisheries and aquaculture to food security and poverty reduction: Assessing the current evidence. World Dev. 2016;79:177–196. doi: 10.1016/j.worlddev.2015.11.007</mixed-citation></ref><ref id="B2"><label>2.</label><mixed-citation>Campbell JH, Dixon B, Whitehouse LM. The intersection of stress, sex and immunity in fishes. 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