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Cadmium‐affected synthesis of exopolysaccharides by rhizosphere bacteria
Author(s) -
Kowalkowski T.,
Krakowska A.,
Złoch M.,
Hrynkiewicz K.,
Buszewski B.
Publication year - 2019
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.14354
Subject(s) - rhizosphere , bacteria , arthrobacter , cadmium , phytoremediation , bacterial growth , chemistry , biology , food science , botany , microbiology and biotechnology , environmental chemistry , heavy metals , genetics , organic chemistry
Abstract Aim Study is focused on the influence of cadmium addition to growth media on production yield, their size and molecular mass of exopolysaccharides (EPS) synthesized by three rhizosphere bacteria strains. Inhibition of bacterial growth by increasing concentrations of Cd 2+ was also analysed. Methods and Results The highest impact of Cd 2+ was noticed on the growth of Arthrobacter sp. and Rhizobium metallidurans . Chryseobacterium sp. and Arthrobacter sp. produced significantly lower when compared to R. metallidurans amounts of EPS under the influence of Cd 2+ . In all bacterial strains both size and molecular mass decreased after addition of Cd 2+ to growth media. It causes a change in EPS conformation to more planar, which minimizes the volume of liquid in the interglobular space next to the bacterial wall. Results confirmed strong effect of Cd 2+ on the structure and synthesis of bacterial EPS what can be a key factor in the interactions between rhizosphere bacteria and host plants in heavy metal polluted soils. Conclusion This work proves that due to the presence of cadmium ions, the size and conformation of EPS produced by selected bacterial strains is changed to minimize their impact on cell. We suggest that shifting in EPS conformation from bigger globular particles to the smaller planar ones could be one of the probable mechanisms of Cd resistance in metallotolerant bacteria, and finally explain increased efficiency of heavy metal phytoextraction by EPS‐producing plant growth‐promoting micro‐organisms. Significance and Impact of the Study One of the most promising remediation technique for Cd‐contaminated areas is the phytoremediation in which rhizosphere bacteria play an important role by protecting plants’ roots from toxic condition thus enhancing efficiency of intake. EPS secretion by bacteria is one of the most common mechanisms to protect the cell from impact of unpleasant environmental conditions, for example, toxicity of heavy metals like Cd.