Observations on the Multiplication of Bacteria in Different Volumes of Stored Sea Water and the Influence of Oxygen Tension and Solid Surfaces

The storage of sea water is accompanied by a great increase in the number of bacteria and a decrease in bacterial species. Appreciably more bacteria per cc. appear in small volumes of sea water than in large volumes of identical water. Although the oxygen content of sea water is a factor which influences the activity of bacteria, it does not account for the denser bacterial populations which appear in the smaller volumes. The favorable influence of small volumes is attributed to the contact of the water with the larger solid surface area in the small receptacles. Between ten and a hundred million bacteria per cc. have been demonstrated in sea water stored in sand which presents an enormous surface area whereas less than three hundred thousand bacteria per cc. appearing similar water stored in 10-liter bottles presenting relatively little surface area. The beneficial effect of small volumes and their large surface areas occurs only in dilute nutrient solutions. Upon the addition of 10 to 100 mgm. of organic matter to sea water, the volume effects disappear. 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 enzymatic activity and the absorption of metabolites.