Nutrient additions resulting in phage release and formation of non-nucleoid-containing bacteria

Abstract

The responses of aquatic bacteriophages to (1) P additions in P-limited batch cultures and (2) separate P and N additions in batch cultures that were both P- and N-limited were monitored. Possible connections between the abundance of non-nucleoid-containing cells (non-Nu CC) and viral abundance were also examined. The water used in the experiments was collected from the mesotrophic Lake Erken (Sweden) in late autumn. In both experiments, nutrient addition resulted in increases in viral abundance and non-nucleoid-containing bacterial cells. However, in the P- and N-limited cultures, P addition resulted in increases in viral abundance and non-nucleoid-containing bacterial cells, but no increase in bacterial abundance. In contrast, in the cultures to which N was added, increases in viral abundance were accompanied by increases in the abundance of both bacteria and non-nucleoid-containing cells. The results show that there is a connection between changes in the abundance of viruses and non-nucleoid-containing cells. However, there are indications that viral abundance can change in response to changes in the P status of the environment without any increase in bacterial abundance. © Inter-Research 2006.