OBSERVATIONS ON THE MULTIPLICATION OF BACTERIA IN DIFFERENT VOLUMES OF STORED SEA WATER AND THE INFLUENCE OF OXYGEN TENSION AND SOLID SURFACES

Abstract

During the storage in glass bottles of filtered sea water which initially contains only a few hundred or less bacteria per cc, the bacterial population increases to thousands or even millions per cc. and there is a great decrease in the number of species. The densest bacterial populations appear in the smallest volumes of stored sea water. Other bacterial activities including oxygen consumption and nitrite reduction also occur more rapidly in small volumes of sea water. The favorable influence of small volumes is attributed to the larger solid surface area offered by small receptacles. Addition of silica sand or small glass beads to increase the solid surface has a beneficial effect. Solid surfaces may serve as a resting place for periphytes, they may help concentrate the nutrients by adsorption or otherwise, or they may favor bacterial enzymic activity and the adsorption of metabolites by retarding their diffusion away from the bacterial cells. Solid surfaces are most beneficial in dilute nutrient solutions such as sea water which contains less than 10 mgm. organic matter per liter. In the presence of higher concentrations of nutrients the volume effects disappear. The absence of solid surfaces in the sea below the photosynthetic zone is believed to account for the paucity of bacteria in this water which when stored in silica sand will support between ten and a hundred million bacteria per cc.[long dash].