Viruses in bottom sediments in a eutrophic reservoir (Ivankovo Reservoir, Upper Volga)
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The total number of viruses, morphological and size composition of viriobenthos, number of bacterial cells infected by viruses, number of mature phages inside bacterial cells, and virus-induced mortality of bacteriobenthos have been estimated in bottom sediments of the Ivankovo Reservoir. The total number of viriobenthos in the reservoir range from 10.3 to 83.2 (31.5 ± 6.2 on average) billion particles/cm3. The total number of virus-to-bacteria ratio in the Ivan’kovo reservoir varies between 0.3 and 1.7 (0.7 ± 0.1 on average). A positive correlation between viral and bacterial abundance is found (R = 0.61, p = 0.05). In different parts of the reservoir, viral infection of bacteria is not observed or is very low. The number of infected bacteria ranges from 1.0 to 3.5% (1.7 ± 0.2% on average) of the total viriobenthos abundance and mortality due to viral lysis accounts for 1.0–3.7% (1.8 ± 0.2% on average) of the total bacterial mortality. The number of phages found inside bacterial cells average 8 ± 1 phages/cell. Thus, a phenomenon known as “infection paradox” is observed in the Ivankovo Reservoir when, at a very high viral abundance, no viral infection of bacteria is recorded or it was very low.
Keywordsviriobenthos bacteria infected by viruses virus-induced mortality of bacteriobenthos reservoir
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