Affiliation:
1. Biotechnology Center for Agriculture and the Environment, Cook College, Rutgers University, New Brunswick, New Jersey 08901-8520
Abstract
ABSTRACT
Earthworm egg capsules (cocoons) may acquire bacteria from the environment in which they are produced. We found that
Ralstonia eutropha
(pJP4) can be recovered from
Eisenia fetida
cocoons formed in soil inoculated with this bacterium. Plasmid pJP4 contains the genes necessary for 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) degradation. In this study we determined that the presence of
R. eutropha
(pJP4) within the developing earthworm cocoon can influence the degradation and toxicity of 2,4-D and 2,4-DCP, respectively. The addition of cocoons containing
R. eutropha
(pJP4) at either low or high densities (10
2
or 10
5
CFU per cocoon, respectively) initiated degradation of 2,4-D in nonsterile soil microcosms. Loss of 2,4-D was observed within the first week of incubation, and respiking the soil with 2,4-D showed depletion within 24 h. Microbial analysis of the soil revealed the presence of approximately 10
4
CFU
R. eutropha
(pJP4) g
−1
of soil. The toxicity of 2,4-DCP to developing earthworms was tested by using cocoons with or without
R. eutropha
(pJP4). Results showed that cocoons containing
R. eutropha
(pJP4) were able to tolerate higher levels of 2,4-DCP. Our results indicate that the biodegradation of 2,4-DCP by
R. eutropha
(pJP4) within the cocoons may be the mechanism contributing to toxicity reduction. These results suggest that the microbiota may influence the survival of developing earthworms exposed to toxic chemicals. In addition, cocoons can be used as inoculants for the introduction into the environment of beneficial bacteria, such as strains with biodegradative capabilities.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
30 articles.
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