Occurrence of multiple metal-resistance in bacterial isolates associated with transgenic white poplars (Populus alba L.)

Abstract

The occurrence of multiple metal-resistance was assessed in two bacterial collections, named Herbicide Resistant Bacteria (HRB) and Nuclease-Producing Bacteria (NPB) respectively, consisting of 15 and 11 isolates obtained from a loamy sand cultivated with transgenic white poplars (Populus alba L., cv 'Villafranca') engineered for herbicide resistance. A third collection of 11 bacterial isolates, named Leaf-Associated Bacteria (LAB), obtained from the leaves of transgenic white poplars expressing the StSy gene for resveratrol production and from untransformed plants was evaluated. Resistance to Cd, Co, Cu, Pb and Zn was tested. As for the HRB collection, nine different phenotypes were monitored, which included tetra-, tri-and double-resistance. Tri-and double-metal resistance occurred also within the NPB and LAB collections. In both cases five different phenotypes were recovered. An additional investigation was carried out on the HRB-1c isolate, resistant to Cd, Co, Pb and Zn, which was previously demonstrated to produce indoleacetic acid, a plantgrowth-promoting trait. Colorimetric assays, performed on the cell-depleted medium of HRB-1c liquid cultures grown in presence of heavy metals, confirmed that this trait was not affected. A 19-kb plasmid, possibly involved in the maintenance of the multiple metalresistant phenotype, was detected in the HRB-1c cells.

DNA extraction from soil: comparison of different methods using spore-forming bacteria and theswrAA gene as indicators

“…Aim of this study was to develop an improved protocol for DNA extraction and purification from a humic acid-rich soil used to establish two extensive greenhouse trials with transgenic white poplars (Balestrazzi et al, 2007(Balestrazzi et al, , 2008(Balestrazzi et al, , 2009a(Balestrazzi et al, , 2009bBonadei et al, 2009).…”

“…This soil has been used for the cultivation of transgenic white poplars engineered with the StSy gene from Vitis vinifera and with the bar gene from Streptomyces hygroscopicus, respectively, in greenhouse trials (Balestrazzi et al, 2007(Balestrazzi et al, , 2008(Balestrazzi et al, , 2009a(Balestrazzi et al, , 2009bBonadei et al, 2009). In the GM poplars expressing the StSy gene encoding stilbene synthase, responsible for resveratrol biosynthesis, the amount of resveratrol-like compounds was in the range 180-210 mg kg -1 fresh leaf tissue (Balestrazzi et al, 2009b).…”

Co-contamination of water with chlorinated hydrocarbons and heavy metals: challenges and current bioremediation strategies

“…Examples of such alterations include; prevention of entry of heavy metals by diminishing production of membrane channel proteins (Rouch et al 1995), possible saturation of metal-binding sites in the membrane and periplasm with non-toxic metals (Mergeay 1991), prevention of metals from reaching the surface of the cell by the formation and binding of an extracellular polysaccharide coat (Scott and Palmer 1990). Gram-negative bacteria possess a cell wall that is a more effective barrier to heavy metals than Gram-positive bacteria, as demonstrated by Balestrazzi et al (2009) that tetra-resistant bacterial isolates were more frequent among the Gram-negative bacteria belonging to the genus Pseudomonas.…”

Rotational Isomerization about C−C Single Bond in a Novel ICT Probe Facilitates Naked‐Eye, Colorimetric and Ratiometric Detection of Cobalt in Aqueous Samples**

“…Surplus demand for raw material and subsequent mining leads to excessive accumulation of cobalt in the environment [8] . Soil and water in the urban environments are highly contaminated by mining and smelting not only on plants [6,9,10] and animals, [1] but also on humans [1,11] . As a result of the wide‐ranging applications of cobalt, mostly in power industries, petrochemical and aviation, [12] the volume of cobalt‐contaminated waste‐water released in the environment affects ground waters adversely [13] .…”