Abstract—Five strains of locally isolated Rhodococcus species from various sources in Peninsular Malaysia were evaluated for their cyanide bioremediation prospective. The partially characterized Rhodococcus UKMP-5M which was used as reference strain failed to propagate exclusively in potassium cyanide (KCN). Therefore, the potential use of resting cells grown in nutrient broth without cyanide was tested to detoxify KCN at various concentrations ranging from 3 mM to 15 mM. The physical characteristics for the cultivation of Rhodococcus UKMP-5M namely temperature, pH and percentage of inoculum were optimized in order to be used as source for cyanide treatment. It was found that the maximum biomass was generated amounting to 8.3222 g/L when the incubation temperature was set to 30 °C at pH 6.6 with an initial inoculum loading of 2 % (v/v). Whole cells with biomass amounting to 1 g/L of the strain were able to rapidly transform almost 50 % of 12 mM cyanide over a period of 10 hours. The biotransformation was carried out at 30 °C, pH 7 and with an agitation at 160 rpm in the absence of added organic and inorganic substances. In addition, by employing the identical amount of biomass and other experimental conditions, the different strains of locally isolated Rhodococcus species were compared for their ability to metabolize cyanide. It was revealed that Rhodococcus UKMP-5M had the highest percentage of cyanide removal efficiency followed by Rhodococcus zopfii, Rhodococcus sp1, Rhodococcus NAM81 and Rhodococcus sp2 which corresponded to 47.78 %, 29.17 %, 23.61 %, 18.33% and 11.67 % respectively.

Index Terms—Bioremediation, Physical characteristics, Cyanide, Rhodococcus.

Maegala Nallapan Maniyam is with the Insititute of BIO-IT Selangor, Universiti Selangor, Jalan Zirkon A7/A, Seksyen 7, 40000 Shah Alam, Selangor, Malaysia (corresponding author to provide phone: 60355223428; fax: 60355223427; e-mail: maegala_81@yahoo.com).
Fridelina Sjahrir is with the Insititute of BIO-IT Selangor, Universiti Selangor, Jalan Zirkon A7/A, Seksyen 7, 40000 Shah Alam, Selangor, Malaysia (e-mail: fridelinasj@yahoo.com).
Abdul Latif Ibrahim is with the Insititute of BIO-IT Selangor, Universiti Selangor, Jalan Zirkon A7/A, Seksyen 7, 40000 Shah Alam, Selangor, Malaysia (e-mail: alatifbio@yahoo.com).

Cite: Maegala Nallapan Maniyam, Fridelina Sjahrir, and Abdul Latif Ibrahim, "Bioremediation of Cyanide by Optimized Resting Cells of Rhodococcus Strains Isolated from Peninsular Malaysia," International Journal of Bioscience, Biochemistry and Bioinformatics vol. 1, no. 2, pp. 98-101, 2011.