RELATIONSHIP BETWEEN THE INTRACELLULAR INTEGRITY AND THE MORPHOLOGY OF THE CAPSULAR ENVELOPE IN ATTACHED AND FREE-LIVING MARINE-BACTERIA

The integrity of the intracellular structures and the presence and dim ension of the capsular envelope were investigated in marine snow-assoc iated and marine free-living bacteria by transmission electron microsc opy and special fixation techniques, Three categories depending on the presence of internal structures were differentiated, In marine snow, 51% of the marine snow-associated bacterial community was considered i ntact, 26% had a partly degraded internal structure, and 23% were empt y with only the cell wall remaining, For the free-living bacterial com munity, 34% were intact cells, 42% exhibited damage, and 24% of the ce lls were lacking any internal structure, We also investigated the morp hology and the extent of the bacterial capsular envelope. More than 95 % of all intact marine snow-associated bacteria were surrounded by a c apsule while approximate to 55% of empty marine snow-associated bacter ia had no capsule, For free-living bacteria, approximate to 65% of the intact cells had a capsule while approximate to 80% of the empty free -living bacteria lacked a capsule. Thus there is a clear trend from in tact cells which are commonly surrounded by a capsular envelope to emp ty bacteria for which only the cell wall is remaining, Since bacteriop lankton represent the largest living surface in the ocean, it is concl uded that the release of intracellular material from bacteria into the environment as well as the release of extracellular capsular material might fuel the dissolved organic matter pool of the ocean.