Identification and Feeding Characterization of <i>Sterkiella histriomuscorum</i> (Protozoa, Ciliophora, Hypotrichia) Isolated from Outdoor Mass Culture of <i>Scenedesmus dimorphus</i>
Herbivorous protistan grazers are ubiquitous and abundant in marine and temperate freshwater environments. However, little is known about the algivorous ciliates and their feeding habits in outdoor mass algal cultures. In this study, we report on one hypotrich ciliate, identified as <i>Sterkie...
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| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-04-01
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| Series: | Microorganisms |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-2607/13/5/1016 |
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| Summary: | Herbivorous protistan grazers are ubiquitous and abundant in marine and temperate freshwater environments. However, little is known about the algivorous ciliates and their feeding habits in outdoor mass algal cultures. In this study, we report on one hypotrich ciliate, identified as <i>Sterkiella histriomuscorum</i>, from the outdoor mass culture of <i>Scenedesmus</i> in Arizona, USA. A long-term field survey revealed that this species often occurs in <i>Scenedesmus</i> culture in spring and summer, and can graze very heavily on <i>Scenedesmus</i> cells. By isolating <i>Sterkiella</i> cells and then observing them via light microscopy and electron microscopy, detailed information about the morphology, ultrastructure, excystment process, and feeding characteristics of the ciliate was obtained. Specifically, it seems that <i>S. histriomuscorum</i> has a range of different strategies for excystment, and the sharp change in the ion concentration in the environment around the cyst results in osmotic shock, which likely facilitates the excystment. Feeding experiments revealed that <i>S. histriomuscorum</i> preferred to graze on chlorophytes as well as the diatom <i>Phaeodactylum tricornutum</i> and had no interaction with chrysophytes or cyanobacteria. Molecular phylogenetic analysis based on the SSU rRNA gene sequence indicated that both the genus <i>Sterkiella</i> and the species <i>S. histriomuscorum</i> are non-monophyletic. The information obtained from this study will help advance our understanding of the biodiversity and ecological function of <i>S. histriomuscorum</i>, and will also be very useful in the development of early warning systems and control measures for preventing or treating this contaminant in microalgal mass cultures. |
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| ISSN: | 2076-2607 |