Formation of submicron colloidal particles from marine bacteria by viral infection

LVe tested the hypothesis that viral lytic infection leads to the formation of submicron-sized colloidal particles originating from manne bacteria. Laboratory exper~ments were performed using a marine bacterium, V~brio alginolyticus, and and its infectious phage. A particle counter was used to determine abundance and size distribution of particles We fo'und that the non-living submicron sized particles (size range from 0.38 to 0.7 pm in diameter) increased rapidly along w ~t h r i decrease of bacteria and an increase of phage, indicating that these particles are cell debris originating from bacteria. These particles were stained faintly by acrici~ne orange but were not countable due to the amorphous shape. These results show that amorphous submicron particles are produced by viral l y s ~s of bacteria. T h ~s process may be one ot the major pathways of colloid formation associated with microbial food webs in the sea.