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A Cross-Trophic Amoebozoan Predator Consumes Trophozoites and Cysts of Naegleria and Acanthamoeba

bioRxiv (Cold Spring Harbor Laboratory) 2026
Yonas I. Tekle, Leila N. Plunkett, Angelicia A. Greer, Michael McGinnis

Summary

Scientists discovered that a tiny predator called Mayorella can eat an unusually wide range of prey—including the tough, protective cysts of Naegleria and Acanthamoeba, two amoebas known to cause dangerous brain and eye infections in humans. This suggests Mayorella might act as a natural check on these harmful organisms in water and soil, potentially helping limit our exposure to them. On a less reassuring note, the study also found this predator can swallow microplastic particles but doesn't seem able to break them down, meaning plastics could simply pass up the food chain instead of being neutralized.

Study Type Environmental

Abstract Protistan predators are key regulators of microbial food webs, yet most are considered to occupy relatively narrow trophic niches. Here, we demonstrate that Mayorella spp. (Amoebozoa), isolated from marine and freshwater environments, exhibits exceptional trophic breadth spanning multiple trophic levels. Live-cell imaging revealed predation on bacteria, algae, dinoflagellates, diatoms, flagellates, ciliates, and multicellular prey including rotifers. Large or filamentous prey were engulfed whole or mechanically fragmented during ingestion. Notably, Mayorella consumed both trophozoites and cysts of free-living amoebae ( Naegleria and Acanthamoeba ), with clear digestion of cyst contents. Dense cultures showed aggregation around large prey and facultative cannibalism. Ingestion of microplastic-like particles occurred without evidence of digestion. Predator cell size and population density increased markedly when feeding on protist or mixed prey relative to bacterial diets, indicating pronounced trophic plasticity. These findings establish Mayorella as a broad-spectrum, cross-trophic predator with the capacity to exert top-down effects across microbial food webs and suggest a previously underappreciated role in the suppression of pathogenic free-living amoebae.

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