Browsing by Author "Prayad Pokethitiyook"

Now showing 1 - 2 of 2
  • Default Image
    Item
    Isolation and characterization of lead-tolerant Ochrobactrum intermedium and its role in enhancing lead accumulation by Eucalyptus camaldulensis
    (Elsevier Ltd, 2011) Piyaporn Waranusantigul; Hung Lee; Maleeya Kruatrachue; Prayad Pokethitiyook; Choowong Auesukaree; C. Auesukaree; Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400, Rama VI Road, Thailand; email: sccar@mahidol.ac.th
    In this study, the potential of rhizospheric bacteria in promoting the growth and Pb accumulation by the woody plant Eucalyptus camaldulensis under hydroponic conditions was investigated for the first time. Three Pb-tolerant bacteria were isolated from the rhizosphere of E. camaldulensis grown in Pb-contaminated soils in the Bo Ngam Pb mine, Thailand. Based on analysis of partial 16S rRNA gene sequence, the three isolates were identified as Microbacterium paraoxydans BN-2, Ochrobactrum intermedium BN-3, and Bacillus fusiformis BN-4. Among these strains, O. intermedium BN-3 showed the highest tolerance to not only Pb but also Cd and Zn. After growth in the presence of Pb, the membranes of O. intermedium BN-3 cells exhibited an increase in unsaturated fatty acid levels but a decrease in fluidity. In hydroponic studies, inoculation of O. intermedium BN-3 significantly increased the biomass and Pb accumulation by E. camaldulensis compared to the uninoculated control. The results suggested the role of the natural rhizospheric bacteria localized to the root surface of E. camaldulensis in promoting Pb accumulation and plant growth. Our results indicate that O. intermedium BN-3 and other indigenous rhizospheric bacteria have the potential to improve the efficiency of phytoremediation of Pb-contaminated sites. © 2011 Elsevier Ltd.
  • Default Image
    Item
    Ultrastructural alterations in the liver and kidney of white sea bass, Lates calcarifer, in acute and subchronic cadmium exposure
    (2004) Suchada Thophon; Prayad Pokethitiyook; Kashane Chalermwat; E. Suchart Upatham; Somphong Sahaphong; P. Pokethitiyook; Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand; email: grpph@mahidol.ac.th
    Ultrastructural alterations in the liver and kidney of 3-month-old white sea bass, Lates calcarifer, after cadmium exposure were studied by transmission electron microscopy (TEM). One group of fish was exposed to a cadmium concentration of 10 mg/L (acute) for 96 h in a static system, and another group was exposed to cadmium concentrations of 0.8 and 3 mg/L cadmium (subchronic) for 3 months in a recirculation closed system. Ultrastructural alterations observed in the hepatocytes included mitochondrial condensation, swelling, and lysis. The rough endoplasmic reticulum (RER) showed dilation, fragmentation, and vesiculation. After subchronic exposure there were numerous large lipid droplets and abundant stored glycogen. Ultrastructural alterations observed in the proximal tubules of the kidney included nuclear degeneration, condensation, and massive swelling of the mitochondria; RER fragmentation and vesiculation. Disorganized brush borders and increased numbers of large hydropic vacuoles and lysosomes were also observed. © 2004 Wiley Periodicals, Inc.