{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,4]],"date-time":"2026-05-04T10:25:17Z","timestamp":1777890317366,"version":"3.51.4"},"reference-count":32,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T00:00:00Z","timestamp":1777593600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Microbiol."],"abstract":"<jats:p>\n                    <jats:italic>Paramecium bursaria<\/jats:italic>\n                    is widely cultured using undefined plant-based infusions such as lettuce extract, yet the variable composition of these media remains a major obstacle to experimental reproducibility and microbiome research. Here, we tested whether a chemically defined synthetic algal medium (AF-6) can replace conventional lettuce infusion while maintaining host physiology and associated microbial communities. An unfed clonal strain of\n                    <jats:italic>P. bursaria<\/jats:italic>\n                    , established in 2023 and capable of growth without external nutrient supplementation, proliferated comparably in AF-6 and lettuce media. To confirm that these results were not specific to unfed conditions, we additionally examined a publicly maintained algae-fed strain (NIES-2891), which exhibited similar growth patterns across both media. Cell size, compression-induced extension, and symbiotic algal abundance showed no significant differences between culture conditions.\n                    <jats:italic>rbc<\/jats:italic>\n                    L metataxonomic analysis revealed that\n                    <jats:italic>Chlorella variabilis<\/jats:italic>\n                    was the sole algal endosymbiont detected in all samples. Furthermore, 16S rRNA gene sequencing demonstrated that host-associated bacterial community composition remained largely conserved after replacement of lettuce infusion with AF-6 within each strain, although clear differences were observed between strains. Together, these findings establish an \u201cunfed strain + defined algal medium\u201d framework as a reproducible experimental platform for investigating tripartite interactions among ciliate hosts, symbiotic algae, and associated bacteria.\n                  <\/jats:p>","DOI":"10.3389\/fmicb.2026.1821058","type":"journal-article","created":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T05:35:23Z","timestamp":1777613723000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["A defined synthetic algal medium enables lettuce-free culturing of unfed Paramecium bursaria while preserving host-associated microbiome composition"],"prefix":"10.3389","volume":"17","author":[{"given":"Yuri","family":"Matsushima","sequence":"first","affiliation":[{"name":"Graduate School of Science, Kanagawa University, Yokohama","place":["Kanagawa, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eiko","family":"Himi","sequence":"additional","affiliation":[{"name":"Faculty of Agriculture, Kibi International University, Minamiawaji","place":["Hyogo, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Masaharu","family":"Kitashima","sequence":"additional","affiliation":[{"name":"Faculty of Chemistry and Biochemistry, Kanagawa University, Yokohama","place":["Kanagawa, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kohei","family":"Ogura","sequence":"additional","affiliation":[{"name":"Graduate School of Agriculture, Kyoto University, Uji","place":["Kyoto, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Susumu","family":"Kotani","sequence":"additional","affiliation":[{"name":"Graduate School of Science, Kanagawa University, Yokohama","place":["Kanagawa, Japan"]},{"name":"Research Institute for Integrated Science, Kanagawa University, Yokohama","place":["Kanagawa, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Akiya","family":"Hino","sequence":"additional","affiliation":[{"name":"Research Institute for Integrated Science, Kanagawa University, Yokohama","place":["Kanagawa, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kazuhito","family":"Inoue","sequence":"additional","affiliation":[{"name":"Graduate School of Science, Kanagawa University, Yokohama","place":["Kanagawa, Japan"]},{"name":"Faculty of Chemistry and Biochemistry, Kanagawa University, Yokohama","place":["Kanagawa, Japan"]},{"name":"Research Institute for Integrated Science, Kanagawa University, Yokohama","place":["Kanagawa, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hiroshi","family":"Hosoya","sequence":"additional","affiliation":[{"name":"Faculty of Chemistry and Biochemistry, Kanagawa University, Yokohama","place":["Kanagawa, Japan"]},{"name":"Tokyo Bunkyo Study Center, The Open University of Japan, Bunkyo","place":["Tokyo, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2026,5,1]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"403","DOI":"10.1016\/S0022-2836(05)80360-2","article-title":"Basic local alignment search tool.","volume":"215","author":"Altschul","year":"1990","journal-title":"J. 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