Isolation of a siderophore-producing and cadmium-resistant bacteria and its effect on seed germination of ryegrass

Abstract:

[Background] Siderophore-producing bacteria (SPB) is a kind of growth-promoting microorganism with high heavy metal resistance, and its application in soil remediation of heavy metal contaminated soil has attracted increasingly attentions. [Objective] To provide organism resources for remediation of heavy metal cadmium contaminated soil; To investigate the effect of SPB on seed germination of ryegrass under cadmium stress. [Methods] the soil that isolated the bacteria was collected from Hongxin Mining Area, Linze county, Gansu province, a bacteria is capable of both producing siderophore and cadmium-resistant was obtained by isolating and purificating of microorganisms technology, and the identifying of this strain was used 16s rRNA gene sequence, and the structure type of chelating groups of siderophore, the growth curve and siderophore production curve of the strain were measured, the fluorescence intensity and ultraviolet spectrum of the siderophore were determinated after separating and purificating from the culture of this bacterium. Finally, the effects of siderophore and its producing bacteria on the germination of ryegrass under cadmium stress were investigated. [Results] The bacteria was identified as Pseudomonas sp. W-STS-8 and it could secrete a yellow-green siderophore—pyoverdine, which has two types chelating groups structures, hydroxamates type and catecholates type. The yield of siderophore reached its maximum value (68%) at the late of the stationary phase, and the yield of siderophore was positively correlated with the biomass of the strain. After separating and purificating of siderophore, the fluorescence could be observed under UV light (254 nm), and the characteristic absorption peak of ultraviolet spectrum was at 400 nm. By studying the effects of siderophore and its producing bacteria on the germination of ryegrass under cadmium stress, the result showed that compared with the control group, the strain culture and its siderophore showed remarkable effect, the seed germination rate of ryegrass increased by 73.14% and 150.92%, respectively. [Conclusion] This strain is expected to provide microbes resources and scientific basis for ecological remediation project by further study, which related to microbial-plant combined remediation of soil contaminated by cadmium.