Characteristics of metal-tolerant plant growth-promoting yeast (Cryptococcus sp. NSE1) and its influence on Cd hyperaccumulator Sedum plumbizincicola

Abstract

Plant growth-promoting yeasts are often over looked as a mechanism to improve phytoremediation of heavy metals. In this study, Cryptococcus sp. NSE1, a Cd-tolerant yeast with plant growth capabilities, was isolated from the rhizosphere of the heavy metal hyperaccumulator Sedum plumbizincicola. The yeast exhibited strong tolerance to a range of heavy metals including Cd, Cu, and Zn on plate assays. The adsorption rate Cd, Cu, Zn by NSE1 was 26.1, 13.2, and 25.2 %, respectively. Irregular spines were formed on the surface of NSE1 when grown in MSM medium supplemented with 200 mg L −1 Cd. NSE1 was capable of utilizing 1-aminocyclopropane-1-carboxylate (ACC) as a sole nitrogen source and was capable of solubilization of inorganic phosphate at rates of 195.2 mg L −1 . Field experiments demonstrated that NSE1 increased phytoremediation by increasing the biomass of Cd hyperaccumulator S. plumbizincicola (46 %, p < 0.05) during phytoremediation. Overall, Cd accumulation by S. plumbizincicola was increased from 19.6 to 31.1 mg m −2 though no difference in the concentration of Cd in the shoot biomass was observed between NSE1 and control. A Cd accumulation ratio of 38.0 % for NSE1 and 17.2 % for control was observed. The HCl-extractable Cd and CaCl 2 -extractable Cd concentration in the soil of the NSE1 treatment were reduced by 39.2 and 29.5 %, respectively. Community-level physiology profiling, assessed using Biolog Eco plates, indicated functional changes to the rhizosphere community inoculated with NSE1 by average well color development (AWCD) and measurement of richness (diversity). Values of Shannon-Weiner index, Simpson index, and McIntosh index showed a slight but no significant increases. These results indicate that inoculation of NSE1 could increase the shoot biomass of S. plumbizincicola, enhance the Cd accumulation in S. plumbizincicola, and decrease the available heavy metal content in soils significantly without overall significant changes to the microbial community.

Influence of Bacillus subtilis strain Z-14 on microbial communities of wheat rhizospheric soil infested with Gaeumannomyces graminis var. tritici

“…In other research, community-level physiological profiling of yeast Cryptococcus sp. NSE1 with plant growth-promoting capabilities found it increased the H′, D, and U of the microbial community (Liu et al, 2016). On the contrary, the influence of 1-octyl-3-methylimidazolium hexafluorophosphate on the soil microbial community diversity demonstrated that AWCD and the diversity indexes were significantly reduced (Zhang et al, 2018).…”

Soil properties and microbial ecology of a paddy field after repeated applications of domestic and industrial sewage sludges

“…The plates were scanned every 12 h at 590 nm for 7 days using a Biolog automated plate reader. All wells were blanked to the control wells (Liu et al 2016). The Biolog data were used for calculating average well color development (AWCD) and AWCD was calculated according to Eq.…”