Plant growth-promoting bacteria that decrease heavy metal toxicity in plants

Abstract

Kluyvera ascorbata SUD165 and a siderophore-overproducing mutant of this bacterium, K. ascorbata SUD165/26, were used to inoculate tomato, canola, and Indian mustard seeds which were then grown in soil for 25-42 days in the presence of either nickel, lead, or zinc. The parameters that were monitored included plant wet and dry weight, protein and chlorophyll content in the plant leaves, and concentration of heavy metal in the plant roots and shoots. As indicated by a decrease in the measured values of these parameters, in all instances, plant growth was inhibited by the presence of the added metal. Both bacterial strains were effective, although not always to a statistically significant extent, at relieving a portion of the growth inhibition caused by the metals. In most cases, the siderophore overproducing mutant K. ascorbata 165/26 exerted a more pronounced effect on plant growth than did the wild-type bacterium K. ascorbata SUD165. The data suggest that the ability of these bacteria to protect plants against the inhibitory effects of high concentrations of nickel, lead, and zinc is related to the bacteria providing the plants with sufficient iron.

Survey of Plant Drought-Resistance Promoting Bacteria from Populus euphratica Tree Living in Arid Area

“…Siderophore producing bacteria were well known to increase the resistance of plant to pathogens [8] by providing the plants with additional iron. As for the abiotic stress, the role of siderophore production was demonstrated by the siderophore-over-producing mutant Kluyvera ascorbata SUD165/26 which was more efficient than wild type bacterium in protecting the plants against heavy metal stress [26].…”

New advances in plant growth-promoting rhizobacteria for bioremediation

“…Just like the character of PGPR in the remediation of organic compounds, they can also prompt plant growth by the synthesis of ACC deaminase (Belimov et al, 2005;Burd et al, 1998;Reed et al, 2005;Safronova et al, 2006). PGPR with ACC deaminase were isolated from rhizosphere of various plants (Belimov et al, 2001).…”

“…PGPR with ACC deaminase were isolated from rhizosphere of various plants (Belimov et al, 2001). What's more, some rhizobacteria can promote plant growth by the synthesis of other compounds, such as siderophores, indole-3-acetic acid (IAA) and antibiotics with heavy metal contaminants, which is different from organic pollutants (Burd et al, 2000;Glick, 2001;Pattern and Glick, 1996) or though stimulation of certain metabolic pathways such as nitrogen fixation and the uptake of nitrogen, phosphorus, S, Mg, Ca and other nutrients (Bashan and Levanony, 1990;Belimov and Dietz, 2000;Okon and Labandera-Gonzalez, (2003) 1994). Leong (1986) reported that heavy metals in soils could stimulate the production of siderophores.…”

“…Soil microorganisms are known to affect the metal mobility and availability to the plant, through acidification, and redox changes or by producing iron chelators and siderophores for ensuring the iron availability, and/or mobilizing the metal phosphates (Abou-Shanab et al, 2003;Burd et al, 2000;Guan et al, 2001). For example, EDTA and EDGA were considered as good chelators to enhance the metal availability to plants, whereas these chelators may lead to side-effects such as metal leaching and low microbial activity (Ernst, 1996;Römkens et al, 2002).…”

Rhizoremediation of metals: harnessing microbial communities

“…Addition of this bacterial strain signifi cantly decreased the toxicity of the added nickel [39]. Addition of a bacterial strain P. maltophila was shown to reduce the mobile and toxic Cr(VI) to immobile and nontoxic Cr(III) thereby minimizing the mobility of metal ions [20].…”