Effects of rhizosphere remediation and bioaugmentation on carbofuran removal from soil

Abstract

Rhizosphere soil contains important sources of nutrients for microorganisms resulting in high number of microorganisms capable of degrading various types of chemicals in the soil. Thus, this study investigated a carbofuran dissipation in rhizosphere soils of 6 weeds namely, umbrella sedge (Cyperus iria L.), fuzzy flatsedge (C. pilosus V.), small flower umbrella plant (C. difformis L.), tall-fringe-rush hoorah grass (Fimbristylis miliacea V.), cover fern (Marsilea crenata P.), and water primrose (Jussiaea linifolia V.). Rhizosphere soil of fuzzy flatsedge showed the shortest half-life (t 1/2 ) of carbofuran (15 days) among other soils. So, it was selected to be used in the bioaugmentation experiment using carbofuran degrader namely Burkholderia cepacia, PCL3, as inoculum in order to examine whether they would improve carbofuran degradation in soil. The results showed that the addition of PCL3 into rhizosphere soil did not improve carbofuran degradation suggesting that microorganisms in rhizosphere soil might be capable enough to remove carbofuran from soil. The number of carbofuran degraders in the rhizosphere soils was greater than in bulk soil 10-100 times which might be responsible to a rapid degradation of carbofuran in rhizosphere soils without the addition of PCL3. The ability of PCL3 to degrade carbofuran was evident in bulk soil (t 1/2 of 12 days) and autoclaved soils (t 1/2 13-14 days) when compared to soils without an inoculation (t 1/2 of 58 days) indicated that the addition of a degrader was useful in improving carbofuran degradation in soil.

Effects of napropamide on microbiological characteristics of tobacco rhizosphere soil and its dissipation

“…Similar findings were reported previously in other studies by Plangklang and Reungsang (2008), Singh et al (2004), Sun et al (2004), and Yu et al (2003) in which the dissipation rates of pesticides were improved in rhizosphere soil of different plants. Dissipation of aldicarb and oxime, carbamate insecticides, in rhizosphere soil of corn, mung bean and cowpea, was found to be more rapid than in unplanted soil (Sun et al, 2004).…”

“…The incidents of more rapid dissipation of pesticides in planted soils than in unplanted soil might be due to the fact that rhizosphere soil contains important sources of nutrients supporting the growth and reproduction of microorganisms capable of degrading various types of chemicals in soil (Hartmann et al, 2009;Korade and Fulekar, 2009). This leaded to a larger number of microorganisms and more rapid dissipation of pesticides in rhizosphere soil than in non-rhizosphere soil (Anderson et al, 1994;Chaudhry et al, 2005;He et al, 2006;Plangklang and Reungsang, 2008;Sun et al, 2004;Singh et al, 2004;Yang et al, 2011).…”

“…The microbial numbers, microbial activity and soil enzymatic activity in the rhizosphere are typically an order of magnitude higher than in the non-rhizosphere (Hartmann et al, 2009). These phenomena often result in accelerating dissipation of organic chemicals in the root zone compared with the non-rhizosphere region (He et al, 2006;Plangklang and Reungsang, 2008;Singh et al, 2004;Sun et al, 2004;Yang et al, 2011). The variety of plants and chemicals for which this has been observed and the remediation processes associated with the rhizosphere were recently reviewed.…”

“…The variety of plants and chemicals for which this has been observed and the remediation processes associated with the rhizosphere were recently reviewed. In general, the results of these studies have shown that plant rooting systems appear to be most effective in enhancing dissipation rates of organic compounds compared to non-rhizosphere soil (Anderson et al, 1994;Chaudhry et al, 2005;He et al, 2006;Korade and Fulekar, 2009;Plangklang and Reungsang, 2008;Yang et al, 2011). Napropamide [N, N-diethyl-2-(1-naphthalenyloxy) propanamide] is an acetanilide herbicide widely used for pre-emergence control of annual grasses and some broad-leaved weeds in a wide range of crop field since its introduction to China.…”

Biodegradation of carbofuran in soils within Nzoia River Basin, Kenya

“…[13] Therefore, the most important route for its removal from the environment is through microbial degradation. [14] Several native bacteria capable of degrading carbofuran have been isolated and characterized in diverse geographical locations. These include bacterial strains, such as Achromobacter sp., Sphingomonas sp., Paracoccus sp., Novosphingobium sp.…”