Binding of DNA from Bacillus subtilis on Montmorillonite–Humic Acids–Aluminum or Iron Hydroxypolymers

Abstract

The equilibrium adsorption and binding of DNA from Bacillus subtilis on complexes of montmorillonite–humic acids Al or Fe hydroxypolymers (Al–M–HA or Fe–M–HA) at different M/HA ratios, the desorption of DNA, the capacity of bound DNA to transform competent cells of B. subtilis in vitro, and the protection of bound DNA from degradation by free and organomineral‐bound DNase I are reported. Adsorption was rapid (maximal after 2 h), occurred from pH 3 to 10, and was higher on Al–M–HA than on Fe–M–HA. Saturation of the sites on the surface or between the layers of Al– or Fe–M–HA occurred with only some complexes, depending on how the complexes were prepared. Essentially no desorption under stringent conditions was observed. Bound DNA transformed auxotrophic competent cells of B. subtilis, although at a lower frequency than free DNA. Bound DNA was protected more than free DNA against degradation by DNase I, and differences in resistance to degradation between free and bound DNA were more evident when DNase was also bound on the organomineral complexes.

Preservation and Significance of Extracellular DNA in Ferruginous Sediments from Lake Towuti, Indonesia

“…Incubations of ferruginous sediments from Lake Matano showed that hydrous ferric oxides (i.e., ferrihydrite) are rapidly reduced by dissimilatory metal-reducing bacteria, resulting in the dissolution of Fe–Mn oxyhydroxides with persistence of mainly goethite (Crowe et al, 2007a,b). The affinity of DNA for goethite is substantially lower than that of common phyllosilicates (Cai et al, 2006), and because goethite traps organic molecules indifferently, its sorption capacity also decreases with increasing organic matter content and degradation (Crecchio et al, 2005). Complete reduction of ferrihydrite occurs within the first cm of sediment at the shallow site, whereas it is even absent at the deep site due to its prior reduction in the water column (data not shown).…”

“…It includes nucleic acids from damaged dead cells, released upon lysis or actively excreted into the surrounding water and sediment (Torti et al, 2015). This fraction is partitioned between sorption onto mineral matrices (Crecchio et al, 2005; Cleaves et al, 2011) and degradation via microbial metabolism (Corinaldesi et al, 2007). Adsorption promotes its persistence, and deposition and burial in sediments, whereas free DNA is readily available for microbial uptake as a nutrient source, resulting in variable turnover rates of this fraction (Dell’Anno and Corinaldesi, 2004; Corinaldesi et al, 2008).…”

Investigation on gene transfer from genetically modified corn (Zea maysL.) plants to soil bacteria

“…[6][7][8][9] Although most plant-derived DNA in soil can be rapidly degraded by biotic and abiotic factors, [10] long-term persistence of plant DNA in soil was frequently reported, especially when DNA was adsorbed to soil particles. [6,[11][12][13][14] Further, DNA adsorbed to mineral surfaces can be protected from degradation, and thus maintains its integrity. [6,13] Recent studies showed that plant DNA including transgene DNA can be detected in soil samples collected from field trials all year-round when GM plants were grown under continuous cultivation.…”

Role of bacteria in the adsorption and binding of DNA on soil colloids and minerals

“…A number of investigations have been devoted to the adsorption and binding of DNA on various soil components such as sand, clay minerals, humic substances and soils. It was found that this process is affected by the ionic strength, pH of the medium, type and content of clay as well as the characteristics and configurations of DNA molecules [12][13][14][15][16][17]. An increase in the concentration of cations and/or a decrease in the pH favored DNA adsorption on soil colloids and clay minerals [12][13][14].…”