Method Verification and Absorption of Cr6+ Ion by the Bacterium Streptococcus sobrinus

Research has been carried out on the biosorption of hexavalent chromium Cr(VI) metal using Streptococcus sobrinus bacteria. Biosorption is carried out by exposing the growing media, namely Luria Bertani. In this study, the diphenyl carbazide method was used to analyze residual Cr(VI) levels that had been absorbed by the bacteria S. sobrinus. Optical density determination was carried out at a wavelength of 610 nm. Determination of the concentration and optimum time of absorption of Cr(VI) by S. sobrinus bacteria using the spectrophotometer method. The creation of a standard curve of Cr(VI) is carried out with variations in concentration (0.5, 0.75, 1, 1.25, 1.5) ppm. The absorption of Cr(VI) metal is carried out with concentration variations (5, 7.5, 10, 12.5, 15) ppm. Measurement of the remaining Cr(VI) in the growing medium is carried out every 48 hours. The optimum concentration and time of absorption of Cr(VI) by S. sobrinus bacteria occurred on day 4 at a concentration of 5 ppm with a biosorption percent of 80.41%. This suggests that S. sobrinus bacteria function as Cr(VI) metal biosorbents.