AME 76:111-116 (2015)  -  DOI: https://doi.org/10.3354/ame01769

ABSTRACT: Using transmission electron microscopy (TEM), a population of giant virus-like particles (VLPs) with a head diameter of ca. 405 nm and a flexible ca. 1100 nm long tail was detected in a lake-type reservoir. These giant VLPs were abundant in situ at the start of a survey period (3.3 × 10⁴ particles ml^-1) and increased by 7-fold within 96 h. This VLP population vanished in dialysis bag incubations of 0.8 µm-filtered reservoir water (free of bacterivorous flagellates) but increased markedly in the enhanced bacterivory treatment, i.e. 5 µm filtered water. In the latter, incubation, heterotrophic nanoflagellate (HNF) abundance increased approximately 15-fold during the study. A multiple regression analysis using microbial abundances and grazing rates as parameters indicated that 78% of the variability in the abundance of giant VLPs was explained by HNF abundance and grazing rates. Our data support the hypothesis that this virus population infects flagellates. Observation of a presumptive lysing flagellate cell suggests a viral burst size of 15. Estimations of decay and net production rates from dialysis bag incubations indicate that lysis due to giant viruses could cause between 10 to 60% of the mortality of the total flagellate community and, thus, viruses are potentially a significant factor shaping the population dynamics of flagellates in freshwater.

KEY WORDS: Viral infection · Mortality · Burst size

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Cite this article as: Weinbauer MG, Dolan JR, Šimek K (2015) A population of giant tailed virus-like particles associated with heterotrophic flagellates in a lake-type reservoir. Aquat Microb Ecol 76:111-116. https://doi.org/10.3354/ame01769 Export citation Share:    Facebook - - linkedIn