BIOSORPTION OF CATIONIC DYES, METHYLENE BLUE AND RHODAMINE B BY GRAM-NEGATIVE BACILLI DURING GROWTH

Abstract

Cationic dyes Methylene Blue (MB) and Rhodamine B (RB) were used to evaluate the Biosorption capacity of isolated Gram-negative bacilli during growth. The bacteria had an absorption capacity on MB, but not on RB. MB sorption not coincided with exponential growth, it started approximately at 12 hours of culture and reached a removal capacity of 53% at 24 h; to remain constant the next 26 hours and increased to 73 % at 60 h. Cellular counts in MB culture presented 25, 20 and 22% fewer at 12, 24 and 30 h, respectively compared to that of the control culture. RB had no effect on bacterial growth; however at 3 h was observed a 23% increment on concentration; thereafter such concentration diminished to original values along the experiment.