Now showing items 1-3 of 3

    • Article

      Biodegradition of monochloroacetic acid by a presumptive Pseudomonas sp. strain R1 bacterium isolated from Malaysian paddy (rice) field 

      SN Ismail, AM Taha, NH Jing, RA Wahab, AA Hamid, RV Pakingking Jr. & F Huyop - Biotechnology, 2008 - Asian Network for Scientific Information
      A bacterial strain tentatively identified as Pseudomonas sp. R1 was isolated from a paddy (rice) field that could degrade monochloroacetic acid (MCA) for concentrations ranging from 5 to 40 mM. Quantitative agreement between the amount of MCA introduced and chloride released was also found. MCA dehalogenase activity in this strain was found to be inducible. Cell-free extracts displayed dehalogenating activity with specific halogenated organic compound with no activity on dichloropropionic acid or monochloropropionic acid. The estimated Km values for MCA was 0.14 mM. The optimal pH range for MCA dehalogenase activity (between pH 6.5 and 8.0), whereas the thermal stability profile stable up to 50 °C. The results of our current study demonstrated the potential use of Pseudomonas sp. R1 as suitable biological agent for biodegradation of MCA in contaminated agricultural area.
    • Article

      Dehalogenase from Methylobacterium sp. HJ1 induced by the herbicide 2, 2-dichloropropionate (Dalapon) 

      NH Jing, AM Taha, RV Pakingking Jr., RAB Wahab & F Huyop - African Journal of Microbiology Research, 2008 - Academic Journals
      Heavy industrial activities and agricultural processes require consumption of many halogenated compounds, and release them continuously as pollutants into the environment. These xenobiotics show high toxicity and persistence and cause many problems to the society, soils and ground water. Microbial dehalogenases are involved in the biodegradation of many important chlorinated compounds. A bacterial strain identified as Methylobacterium sp. HJ1 is able to degrade the herbicide 2,2-dichloropropionic acid by removal of the halogen and subsequent metabolism of the product for energy. D,L-2-chloropropionate also supported good growth of the organism but 3-chloropropionate, monochloroacetate and dichloroacetate were not utilized. Cell-free extracts of the 2,2-dichloropropionate-grown bacteria converted 2,2-dichloropropionate into pyruvate with the release of two chloride ions for each molecule of pyruvate formed. This indicates the presence of dehalogenase activity in the cell-free extracts. Only 2,2-dichloropropionate and D,L-2-chloropropionate were inducers and substrates for the dehalogenase. Monochloroacetate and dichloroacetate did not serve as an inducer, whereas 3-chloropropionate was a non-substrate inducer.
    • Article

      Purification and properties of a non-stereospecific dehalogenase enzyme E (DehE) from Methylobacterium sp. HJ1 

      NH Jing, FH Sulaiman, RA Wahab, RV Pakingking Jr., NAA Rashid & F Huyop - African Journal of Microbiology Research, 2008 - Academic Journals
      The bacterial isolate HJ1, which was identified as a Methylobacterium sp., grew on 2, 2-dichloropropionic acid as the sole carbon source and produced a 2-haloalkanoic acid hydrolytic dehalogenase. This non-stereospecific dehalogenase E (DehE) catalysed the hydrolytic dechlorination of 2, 2-dichloropropionic acid and D, L-2-chloropropionic acid to produce pyruvate and lactate, respectively. The enzyme was purified to homogeneity and characterized. The molecular weight was 36 kDa by SDS-polyacrylamide gel electrophoresis and 72 kDa by gel filtration, suggesting that the enzyme is a protein dimer. The purified enzyme was only inhibited by HgSO4 and was non-stereospecific to haloalkanoic acids. The Km value for the hydrolysis of 2, 2-dichloropropionic acid was 0.25 mM. The enzyme removes chloride present on the α-position, but not on the β-position, of a number 2-carbon alkanoic acids.