Plasmid Transfer between Spatially Separated Donor and Recipient Bacteria in Earthworm-Containing Soil Microcosms

Daane, L. L.; Molina, J. A. E.; Sadowsky, Michael J.

doi:10.1128/aem.63.2.679-686.1997

Cited by 43 publications

(20 citation statements)

References 47 publications

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“…Earthworm cocoon fluid has been found to elicit an immune response against several bacterial species, which indicates that earthworms may be able to control the cocoon microbiota (30). This is also suggested by Daane et al (7), who reported consistent recovery of Ralstonia eutropha (formerly Alcaligenes eutrophus) from Aporrectodea trapezoides cocoons formed in inoculated soil. In addition, Zachmann and Molina (32) reported that Escherichia coli could not be recovered from cocoons formed in microcosms inoculated with this bacterium.…”

supporting

confidence: 83%

“…R. eutropha JMP222N is a nalidixic acid-resistant mutant of JMP222, a streptomycin-resistant, cured derivative of R. eutropha JMP134(pJP4) (21). R. eutropha JMP222N containing pJP4 was obtained by patch mating as previously described (7). Plasmid pJP4 is an IncP, broad-host-range plasmid containing genes for mercury resistance and 2,4-D and 2,4-DCP degradation (21).…”

Section: Methodsmentioning

confidence: 99%

“…In addition, earthworms directly and indirectly influence soil microbial communities, mainly through the processes of feeding, burrowing, and fecal (cast) deposition. Several studies have shown that earthworms can transport bacteria into the environment (6,7,9,13,16,23,27,28,29). In particular, previous studies have assessed the importance of earthworms for the transport of beneficial bacteria for use in biological control (27).…”

mentioning

confidence: 99%

“…In particular, previous studies have assessed the importance of earthworms for the transport of beneficial bacteria for use in biological control (27). More recently, earthworms have been implicated as vectors and contributors for bacterial gene transfer (6,7). To date, the majority of these studies have focused on adult earthworms, with little attention to how developing cocoons or juvenile earthworms affect microbial communities.…”

mentioning

confidence: 99%

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Earthworm Egg Capsules as Vectors for the Environmental Introduction of Biodegradative Bacteria

Daane

Häggblom

1999

Appl Environ Microbiol

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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 fetidacocoons 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 (102 or 105 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 104 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.

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supporting

confidence: 83%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Earthworm Egg Capsules as Vectors for the Environmental Introduction of Biodegradative Bacteria

Daane

Häggblom

1999

Appl Environ Microbiol

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“…If, however, soil conditions do not sustain signi¢cant cell growth, then conjugation will only occur if the inoculation process itself leads to contact between the two populations, e.g. if cell concentrations are high, unless mechanisms such as bulk £ow, movement of soil and animals, and growth of plant roots and fungal hyphae promote dispersal of cells [26,27]. Previous studies aimed at testing models of gene transfer in the soil have eliminated spatial e¡ects by utilisation of high cell concentrations and high matric potentials that enhanced mobility [28].…”

Section: Discussionmentioning

confidence: 99%

A model for bacterial conjugal gene transfer on solid surfaces

Lagido

Wilson

Glover

et al. 2003

FEMS Microbiology Ecology

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Quantitative models of bacterial conjugation are useful tools in environmental risk assessment and in studies of the ecology and evolution of bacterial communities. We constructed a mathematical model for gene transfer between bacteria growing on a solid surface. The model considers that donor and recipient cells will form separate colonies, which grow exponentially until nutrient exhaustion. Conjugation occurs when donor and recipient colonies meet, all recipient cells becoming transconjugants instantly, after which they act as donors. The model was tested theoretically by computer simulations that followed the histories of individual bacterial colonies and was validated for initial surface coverage of 60% or less, where confluent growth does not occur. Model predictions of final number of donors, recipients and transconjugants were tested experimentally using a filter mating system with two isogenic strains of Pseudomonas fluorescens MON787 acting as donor and recipient of plasmid RP4. Experimental trends resulting from varying donor and recipient inoculum numbers and donor:recipient ratios were well described by the model, although it often overestimated conjugation by 0.5-2 orders of magnitude. Predictions were greatly improved, generally to within half a log unit of experimental values, by consideration of the time for conjugative transfer. The model demonstrates the relationship between spatial separation of cells and nutrient availability on numbers of transconjugants. By providing a mechanistic approach to the study conjugation on surfaces, the model may contribute to the study of gene transfer in natural environments.

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Catabolic Plasmids

Schmidt¹,

Ahmetagic²,

Philip³

et al. 2011

Encyclopedia of Life Sciences

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Catabolic plasmids are large (80→1100 kb) linear or circular, accessory deoxyribonucleic acid elements present in the cytoplasm of bacteria from virtually every ecological niche on Earth. Many have a broad host range and can be transferred by cell‐to‐cell contact to a wide range of bacteria. The large catabolic gene clusters carried by these plasmids play a central role in the Earth's carbon cycle, enabling their hosts to degrade and recycle complex naturally occurring molecules such as lignin, the second most abundant plant biopolymer on Earth after cellulose. More recently catabolic gene clusters have evolved the ability to degrade and recycle most man made molecules, including the most toxic and the most recalcitrant environmental pollutants, providing a biological solution to environmental pollution. Catabolic genes have been used to construct novel strains of bacteria which produce biopharmaceuticals such as antibiotics and anticancer agents, biofuels such as ethanol, industrial dyes such as indigo and biodegradable plastics. The very first patent for a genetically modified organism was for the use of catabolic plasmids to degrade oil. Key Concepts: Catabolic plasmids are giant bacterial plasmids that encode vast arrays of catabolic gene clusters. They play a central and indispensible role in the Earth's carbon cycle. Catabolic plasmids are essential for the degradation and recycling of abundant, naturally occurring yet chemically complex plant materials such as lignin. In addition, there are catabolic plasmids, which enable bacteria to degrade and recycle the most complex, most toxic and the most polluting man‐made molecules including most carcinogens, teratogens and mutagens. Degradation and recycling of such complex molecules at room temperature and pressure, so called ‘green or eco‐friendly’ chemistry, requires many different enzymes encoded in large arrays of gene clusters. To accommodate these genes on catabolic plasmids they must be very large. Some are in excess of 1000 kb. Many catabolic plasmids are transferable from one bacterial cell to another by cell‐to‐cell contact. They have an extraordinarily broad host range being able to rapidly confer their catabolic activities on large populations of soil bacteria. Novel catabolic functions can be produced by rearranging existing pathway genes, combining genes from different pathways to form a new pathway and by fusing segments from a number of pre‐existing catabolic genes into a new catabolic gene. The genes encoded by catabolic plasmids have been harnessed by humans to produce antibiotics and anticancer drugs, to synthesise biofuels such as ethanol from lignin and to degrade and recycle man‐made environmental pollutants. The very first patent to be granted for a genetically modified organism was for catabolic plasmids that encoded the degradation of environmental oil spills.

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Plasmid Transfer between Spatially Separated Donor and Recipient Bacteria in Earthworm-Containing Soil Microcosms

Cited by 43 publications

References 47 publications

Earthworm Egg Capsules as Vectors for the Environmental Introduction of Biodegradative Bacteria

Earthworm Egg Capsules as Vectors for the Environmental Introduction of Biodegradative Bacteria

A model for bacterial conjugal gene transfer on solid surfaces

Catabolic Plasmids

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