Biochar as a Carrier Material for Biodegradation of the Insecticide, Propoxur Nghia K. Nguyen 1 and Warren A. Dick 2 1 Department of Soil Science, College of Agriculture & Applied Biology, Cantho University, Cantho City, Vietnam 2 School of Environment & Natural Resources, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA E-mail: nknghia@ctu.edu.vn and dick.5@osu.edu INTRODUCTION Biochar, a carbon-rich product obtained by heating biomass in a closed system under a limited supply of oxygen (Figure 1A), is often used in agriculture to improve carbon sequestration, soil fertility and plant protection (Woolf et al., 2010; Zhang et al., 2010). Biochar contains crevices and holes (Figure 1B) for adsorption of water, nutrients, and inorganic and organic contaminants. Biochar has been suggested as an inoculant carrier for microorganisms (Chen et al., 2012). Propoxur is an insecticide used against turf, forestry and household pests and fleas. If not properly handled, it can be toxic to humans and aquatic organisms. Propoxur is still widely used in many countries of the world. HYPHOTHESIS Biochar can be used as an inoculant carrier for Propoxur-degrading bacteria to enhance biodegradation of Propoxur. MATERIALS AND METHODS There were 3 experiments with four replicates conducted: Experiment 1. Evaluating the amount of Paracoccus sp. P23-7 that can be carried by biochar. Experiment 2. Evaluating the biochar-containing Paracoccus sp. P23-7 to enhance biodegradation of Propoxur in water. Experiment 3. Evaluating the biochar-containing Paracoccus sp. P23-7 to enhance biodegradation of Propoxur in soil. BIBLIOGRAPHY 1 Zheng, W., Guo, M., Chow, T., Bennett, D.N., Rajagopalan, N. 2010. Sorption properties of greenwaste biochar from two trizaine pesticides. J. Hazard. Mater. 181, 121-126. 2 Woolf, D., Amonette, J.E., Street-Perrott, F.A., Lehmann, J., Joseph, S. 2010. Sustainable biochar to mitigate global climate change. Nat. Commun. 1. DOI 10.1038/ncomms1053. 3 Chen, B., Yuan, M., Qian, L. 2012. Enhanced bioremediation of PAH-contaminated soil by immobilized bacteria with plant residue and biochar as carriers. J Soils Sediments. DOI 10.1007/s11368-012-0554-5. Figure 1. Biochar (A) with numerous pores (B). A B OBJECTIVE To evaluate biochar as a carrier material to improve biodegradation of Propoxur-contaminated soils. RESULTS Different biochars could immobilize more than 10 5 cells of Paracoccus sp. P23-7 bacteria known to be effective biodegraders of Propoxur (Figure 2). Degradation was more efficient when the Propoxur-degrading bacteria were carried on biochar before being applied to contaminated water or soil (Figures 3 and 4). This is because the biochar protects the Paracoccus sp. P23-7 from rapidly dying in soil so that they can biodegrade the Propoxur for longer periods of time. Fingerprinting of bacterial DNA from soils clearly shows the control soil does not contain Paracoccus sp. P23-7 (yellow arrow), whereas soils treated with cells alone or cells carried on biochar remained in soil for up to 14 days (Figure 5). Figure 2. Number of Paracoccus sp. P23-7 in three different biochar s after 1 incubation day in water (mean plus standard deviation around the mean). Figure 3. Biodegradation of Propoxur in water (mean plus standard deviation around the mean). Figure 5. Fingerprinting of bacterial DNA community from soil (Experiment 3) after 14 incubation days. Control (1), P23-7 (2), biochar containing P23-7 (3) and DNA from culture of P23-7 (4). 1 2 3 4 CONCLUSION Biochar can serve as an effective innoculant carrier for Propoxur-degrading bacteria, Paracoccus sp. P23-7, to enhance biodegradation of Propoxur in water and soil environments. Figure 4. Biodegradation of Propoxur in soil (mean plus standard deviation around the mean). ACKNOWLEDGMENT We thank Vietnam Education Foundation, Cantho University and The Ohio State University for the fund and supporting this research. OHIO AGRICULTURAL RESEARCH AND DEVELOPMENT CENTER View publication stats View publication stats