Identifikasi Isolat Bakteri Tahan Krom(VI) dan Pengujian Aktivitas Enzim Krom(VI) Reduktase

Abstract

Cr(VI) (chromate) is a toxic, soluble environmental contaminant. A Gram-negative, Cr(VI)-resistant bacterium, has been isolated from effluent of electroplating wastewater treatment reactor. This strain had maximum identity value as high as 96% to Ralstonia pickettii and Ralstonia sp. M2S3. This value indicated that the strain was a species of Ralstonia genera. Because of this reason, the strain was designated as Ralstonia sp. Cr6NS. Ralstonia sp. Cr6NS was able to grow aerobically in 250 ppm Cr(VI) and had Cr(VI) reducing-capacity as high as 4,11 x 10-8μg Cr(VI)/hour/cell. From the study of enzymatic activity, Ralstonia sp. Cr6NS showed the activity of Cr(VI)-reductase both in periplasmic and sitoplasmic content. The highest activity was found in periplasmic matrix. However, the strain seemed not secreting this enzyme to the external medium.