BACTERIAL Cr (VI) REDUCTION AND ITS IMPACT IN BIOREMEDIATION

Abstract

ABSTRACT
Chromium is hazardous pollutant for ecosystem caused chromium especially in
hexavalent form is very toxic, has high solubility and mobility, teratogenicity, mutagenicity and
carcinogenicity to living system related with its oxiding power. Remediation of soil
contaminated of heavy metals was important caused soil as medium for food producing.
Conventional methods for heavy metals remediation consist of physical and chemical process
but these applications were costly and less effective. One of the remediation technologies is the
using living organisms such as microorganisms, because they have ability to reduce Cr(VI) into
non toxic form, Cr(III). The aims of this research were to evaluate the reduction activity of
rhizobacterial isolate and to identify the isolate which take a role in reducing chromium
absorption by plant. The results showed that Isolate 39 was able to grow on LB medium
containing 200 ppm Cr(VI). Isolate 39 reduced Cr(VI) up to 15 ppm concentration level in
minimal medium. Isolate 39 has ability to reduce Cr(VI) both at growing cells and resting cells
conditions up to 100% and 51% within 18 hours, respectively. Isolate 39 increased the
phytostabilization ability of chromium by Zea mays at 30 days after seeding 3.8 times
compared than control. Based on physiological characteristics and partial sequencing of 16S
rRNA gene, Isolate 39 was identified as Agrobacterium sp.
Key words : Agrobacterium sp, hexavalent chromium, reduction, Zea mays