Fig 3.

Aggregation efficiency is the highest when one bacterium is added for every one to five algal cells present. At ratios above and below these ratios, aggregation efficiency is reduced. The result for the ratio of 5:1 is statistically significantly different from that for the ratio of 1:1 (P = 8.0E−5). The result for the ratio of 1:1 is statistically significantly different from that for the ratio of 1:5 (P = 0.009). Bars and error bars represent the means and standard errors, respectively, of five independent aggregation reactions. A value of 100% is aggregation of all algal cells.