The Effect of Solid Surfaces upon Bacterial Activity.

The bacterial population of water samples from the sea, lakes or other sources usually increases during storage. While several different factors may be operative (Prescott and Winslow, 1931), it is noteworthy that the magnitude of the increase is often related to the size of the receptacle in which the water is stored. For example, Whipple (1901) found that the bacterial population of water, which initially contained an average of 77 bacteria per ml., increased to 300 per ml. in a gallon, 900 per ml. in a quart, 7,020 per ml. in a pint and 41,400 per ml. in 2-ounce bottles after 24 hours' incubation under comparable conditions. He attributed this to the greater availability of oxygen in the small receptacles which were not filled to capacity. However, ZoBell and Stadler (1940) have shown that the multiplication and respiration of aerobic bacteria is independent of the oxygen tension within the examined ranges of 0.30 to 36 mgm./liter. Using oxygen consumption as well as bacterial multiplication in glass-stoppered bottles filled to capacity with sea water as criteria, ZoBell and Anderson (1936) noted that bacteria are generally more active in small than in large receptacles of similar shape. Since the small receptacles present relatively more solid surface per unit volume of stored water than large receptacles, they concluded that solid surfaces are beneficial to bacteria in dilute nutrient solutions. A similar conclusion was reached by Lloyd (1937). The following report is concerned with the ways in which solid or adsorbing surfaces may influence bacterial activity.