AUTHOR=Bu Xialian , Li Zhongyang , Zhao Weishan , Zeng Qingwen , Chen Yushun , Li Wenxiang , Zou Hong , Li Ming , Wang Guitang 

TITLE=Alterations of gut microbiota and short-chain fatty acids induced by Balantidium polyvacuolum in the hindgut of Xenocyprinae fishes providing new insights into the relationship among protozoa, gut microbiota and host

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1295456

DOI=10.3389/fmicb.2023.1295456

ISSN=1664-302X

ABSTRACT=<sec><title>Introduction</title><p>Parasitic ciliates are protozoans with a global distribution. Along with the gut microbiota, they have formed a micro-ecosystem that affects the host’s nutrition, metabolism, and immunity. The interactions and relationships among the three components of this microecosystem (protozoa, gut microbiota, and host) remain only partially understood. Xenocypris fish and the unique ciliate <italic>Balantidium polyvacuolum</italic> in its hindgut are good materials to study the interplay.</p></sec><sec><title>Methods</title><p>In this study, 16S rRNA gene amplicon sequencing and short-chain fatty acids (SCFAs) identification were used. Network was also constructed to understand their relationships.</p></sec><sec><title>Results</title><p>We found that the gut microbiota of <italic>B. polyvacuolum</italic>-infected <italic>X. davidi</italic> and <italic>X. argentea</italic> had higher diversity, richness, and evenness than uninfected ones. <italic>B. polyvacuolum</italic> could lead to an increase of <italic>Fusobacterium</italic> and Chloroflexi in both <italic>X. davidi</italic> and <italic>X. argentea</italic>, while significantly increase the abundance of genera <italic>Romboutsia</italic> and <italic>Clostridium</italic> in <italic>X. argentea</italic>. Besides, <italic>B. polyvacuolum</italic> could significantly increase the content of total SCFAs and acetic acid in <italic>X. davidi</italic> and increase the concentrations of propionic, isobutyric and butanoic acids in <italic>X. argentea</italic>. Furthermore, correlation analyses showed that <italic>B. polyvacuolum</italic> may alter SCFAs by affecting key SCFAs-producing bacteria such as <italic>Clostridium</italic> and <italic>Cetobacterium</italic>.</p></sec><sec><title>Discussion</title><p>This study greatly expands our understanding of relationships among <italic>B. polyvacuolum</italic>, gut microbiota and host Xenocypris fish, which sheds new insights into the mechanism of interaction among protozoa, gut microbiota and host.</p></sec>