Modification of Spatial Distribution of 2,4-Dichlorophenoxyacetic Acid Degrader Microhabitats during Growth in Soil Columns

Abstract

Bacterial processes in soil, including biodegradation, require contact between bacteria and substrates. Knowledge of the three-dimensional spatial distribution of bacteria at the microscale is necessary to understand and predict such processes. Using a soil microsampling strategy combined with a mathematical spatial analysis, we studied the spatial distribution of 2,4-dichlorophenoxyacetic acid (

Herbicides in the Soil Environment: Linkage between Bioavailability and Microbial Ecology

“…Moreover, the bacterial distribution at the microscale may facilitate spreading of degradative genes located in plasmids or transposons (McGowan et al, 1998;DiGiovanni et al, 1996). Pallud et al (2004) found that for low abundances of 2,4 D degraders, there was strong spatial isolation within the degraders populations, with less than 2 cells per colonized patch. 2,4-D amendment caused an increase in degrader abundance and concurrent spreading of degraders, reducing the distance between colonized patches, although the number of cells per patch remained low (< 28).…”

“…2,4-D amendment caused an increase in degrader abundance and concurrent spreading of degraders, reducing the distance between colonized patches, although the number of cells per patch remained low (< 28). They argued that the spatial spreading of bacteria was an ecological strategy that increased the probability of encountering the substrate (2,4-D), and proposed that this was achieved either through active cell movement (chemotaxis) or degradative plasmids transfer to indigenous microbial populations (Pallud et al, 2004). The zone of soil directly influenced by the presence of plant roots, known as rhizosphere, is of particular importance.…”

“…Most microorganisms are located surrounding the water layer attached to soil particles within micro-aggregates. Pallud et al (2004) estimated that soil bacteria occupy only 0.1 mm 3 of the 500 mm 3 of pores in 1 cm 3 of soil. Moreover, different physiological groups present at the same density in soil might have significantly different microscale spatial distributions (e.g., forming clumps of cells in a few "hot spots" versus evenly spread out across soil particle surfaces).…”

Biogeochemical behaviour of anionic radionuclides in soil: Evidence for biotic interactions

“…In our experimental set-ups, the soil microbial status were strongly constrained by the organization of the solid substrate that differed significantly from homogeneous soil/solution suspensions to well structured porous media. These two types of organization may have a great influence on the microbial development strategy leading to various microbial, solid and liquid interfaces [12]. Thus, combining both static and dynamic experiments allowed to check the accuracy of biotic and abiotic sorption parameters to characterize radionuclide mobility.…”

Impact of the Microscale Distribution of a Pseudomonas Strain Introduced into Soil on Potential Contacts with Indigenous Bacteria

“…Using microscopic techniques, Nunan and coworkers have described the in situ distribution of soil bacteria at multiple scales (31) and with respect to soil porosity (32). The three-dimensional microscale distributions of specific autochthonous functional communities have been characterized as well, by an approach based on soil microsampling for with nitrifiers (14) and 2,4-dichlorophenoxyacetic acid (2,4-D) degraders (34).…”