Search

Extensive use of carbofuran insecticide harms the environment and human health. Carbofuran is an endocrine disruptor and has the highest acute toxicity to humans than all groups of carbamate pesticides used. Carbofuran is highly mobile in soil and soluble in water with a lengthy half-life (50 days). Therefore, it has the potential to contaminate groundwater and nearby water bodies after rainfall events. A bacterial strain BRC05 was isolated from agricultural soil characterized and presumptively identified as Enterobacter sp. The strain was immobilized using gellan gum as an entrapment material. The effect of different heavy metals and the ability of the immobilized cells to degrade carbofuran were compared with their free cell counterparts. The results showed a significant increase in the degradation of carbofuran by immobilized cells compared with freely suspended cells. Carbofuran was completely degraded within 9 h by immobilized cells at 50 mg/L, while it took 12 h for free cells to degrade carbofuran at the same concentration. Besides, the immobilized cells completely degraded carbofuran within 38 h at 100 mg/L. On the other hand, free cells degraded the compound in 68 h. The viability of the freely suspended cell and degradation efficiency was inhibited at a concentration greater than 100 mg/L. Whereas, the immobilized cells almost completely degraded carbofuran at 100 mg/L. At 250 mg/L concentration, the rate of degradation decreased significantly in free cells. The immobilized cells could also be reused for about nine cycles without losing their degradation activity. Hence, the gellan gum-immobilized cells of Enterobacter sp. could be potentially used in the bioremediation of carbofuran in contaminated soil.

Copyright of African Journal of Biological Sciences is the property of African Journal of Biological Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Response surface methodology and Plackett-Burman experiments were applied to optimize the biodegradation of carbofuran by using Enterobacter sp. stain BRC05 isolated from selected agricultural areas in peninsular Malaysia. The significant factors influencing the degradation of carbofuran were assessed using two-level Plackett–Burman Design (PBD) with five variables. Plakett Burman experiment showed that the following four variables were significant for carbofuran degradation including, carbofuran concentration, temperature, pH and nitrogen sources. Significant variables obtained in Plackett-Burman Design were further optimize using Central Composite Design (CCD). The outcome of the design for carbofuran degradation for each runs of the PBD experiment base on the design matrix, showed that the minimum and the maximum carbofuran degradation percentage were found to be 6.7% and 79.77% as presented in runs 4 and 1, respectively. Results obtained using Central Composite Design showed that the relations between the factors affect carbofuran degradation with significant response. The predicted results in CCD indicated that highest carbofuran degradation of 95.40% could be realized with carbofuran concentration of 92.50 mg/L, pH of 6.0, temperature 27.50 °C, nitrogen sources of 0.45 g/L and reaction period of 6 days. The predicted values were in agreement with the actual values with coefficient of determination with R2 0.9719. Partial 16S rRNA sequence analysis showed that the carbofuran degrading isolate was closely related to members of the genera Enterobacter sp. The morphological and biochemical characteristics of the isolate also confirmed the phylogenetic signature. This study would provide an effective approach that could be beneficial for the bioremediation of carbofuran insecticide in polluted environment. [ABSTRACT FROM AUTHOR]

Carbamates are poisonous pesticides which have been used widely in agriculture production for decades. Unlike other pesticides such as organophosphate, carbamate pesticides are not persistent in the environment however, their degradation is crucial due to their toxicity to living system. The World Health Organization, categorized carbamate pesticide as toxic, hazardous and restricted for use. Example of carbamates pesticides include Carbaryl, Aldicarb, Methomyl, Carbofuran, and Propoxur. They are extensively used to control many insect and pests of crops. Presently, there is signifcant awareness regarding the negative effects of pesticides due to their ability to pollute soil and water bodies. Most pesticides are readily degraded or metabolized by microbes. Carbamate pesticide degradation by microorganisms relies not only on the availability of microbes with suitable biodegradative enzymes, but also on the various ecological factors. This review- article outlines the present development in biodegradation of carbamate pesticides, their toxicity and enzymatic degradation as well as their degradative pathways. [ABSTRACT FROM AUTHOR]