African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12487

Full Length Research Paper

Characterization of rhodanese produced by Pseudomonas aeruginosa and Bacillus brevis isolated

Olaoluwa Oyedeji1*, Kehinde O. Awojobi1, Raphael E. Okonji2 and Olufemi O. Olusola1
  1Department of Microbiology, Obafemi Awolowo University, Ile-Ife, Nigeria. 2Department of Biochemistry, Obafemi Awolowo University, Ile-Ife, Nigeria.
Email: [email protected].

  •  Accepted: 26 November 2012
  •  Published: 31 March 2013

Abstract

 

Wastewater from numerous cassava processing industries contains cyanide which is toxic to several forms of life. This effluent constitutes serious hazards to the environment and aquatic life in receiving water bodies. Enzymatic remediation of polluted environment presents advantages over traditional technologies and also over microbial remediation. Extracellular rhodanese of strains of Pseudomonas aerugionosa and Bacillus brevis isolated from soil of cassava processing site were studied. Biochemical characteristics of the purified enzymes, including pH and temperature profiles were also determined. Production of rhodanese correlated with the rate of bacterial growth at the exponential phase for both strains. Optimum incubation time for maximum enzyme production was 20 h in both cases. The enzyme was purified 9.72-fold with a yield of 37.8% and specific activity of 6.32 mg-1protein in the case of P. aeruginosa. The enzyme from B. brevis was purified 7.44-fold with a yield of 22.6% and specific activity of 5.21 mg-1 protein.  The enzyme generally demonstrated a broad pH range but optimum pH was 6.0 and 7.0 for P. aeruginosaand B. brevis rhodanese activity respectively. Optimum temperatures for P. aeruginosa and B. brevis rhodanese were 50 and 40°C, respectively, with both enzymes retaining activity up to 70°C. The Km values for KCN and Na2S2O3 as substrates for P. aeruginosa rhodanese were 12.5 and 0.0066 mM, respectively, while the Km values for the same substrates for B. brevis rhodanese were 3.12 and 11.1 mM, respectively. Cations, Hg2+, Ba2+, and Co2+ all inhibited the enzyme activities of both bacteria. The bacteria rhodaneses have potential for effective remediation of cyanide-polluted environments, ultimately leading to improvement of fish and other aquatic organisms in receiving water bodies.  

 

Key words: Cyanide, cyanogenic glycosides, cassava mill wastewater, rhodanese,Pseudomonas aeruginosaBacillus brevis.