Heavy metals mitigation and growth promoting effect of endophytic Agrococcus terreus (MW 979614) in maize plants under zinc and nickel contaminated soil

Asim Shahzad; Anam Siddique; Shazia Ferdous; Muhammad Ahmar Amin; Mingzhou Qin; Uzma Aslam; Muhammad Naeem; Tasmia Bashir; Abdul Shakoor

doi:10.3389/fmicb.2023.1255921

Heavy metals mitigation and growth promoting effect of endophytic Agrococcus terreus (MW 979614) in maize plants under zinc and nickel contaminated soil

Front Microbiol. 2023 Nov 9:14:1255921. doi: 10.3389/fmicb.2023.1255921. eCollection 2023.

Authors

Asim Shahzad^{1

2}, Anam Siddique², Shazia Ferdous², Muhammad Ahmar Amin³, Mingzhou Qin¹, Uzma Aslam², Muhammad Naeem⁴, Tasmia Bashir⁵, Abdul Shakoor¹

Affiliations

¹ The College of Geography and Environment, Henan University, Kaifeng, China.
² Department of Botany, Mohi-Ud-Din Islamic University, AJ&K, Pakistan.
³ Rawalpindi Women University, Rawalpindi, Pakistan.
⁴ Department of Plant Science, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China.
⁵ Department of Botany, Rawalpindi Women University Rawalpindi, Rawalpindi, Pakistan.

Abstract

Introduction: Heavy metals such as iron, copper, manganese, cobalt, silver, zinc, nickel, and arsenic have accumulated in soils for a long time due to the dumping of industrial waste and sewage. Various techniques have been adapted to overcome metal toxicity in agricultural land but utilizing a biological application using potential microorganisms in heavy metals contaminated soil may be a successful approach to decontaminate heavy metals soil. Therefore, the current study aimed to isolate endophytic bacteria from a medicinal plant (Viburnum grandiflorum) and to investigate the growth-promoting and heavy metal detoxification potential of the isolated endophytic bacteria Agrococus tereus (GenBank accession number MW 979614) under nickel and zinc contamination.

Methods: Zinc sulfate and nickel sulfate solutions were prepared at the rate of 100 mg/kg and 50 mg/kg in sterilized distilled water. The experiment was conducted using a completely random design (CRD) with three replicates for each treatment.

Results and discussion: Inoculation of seeds with A. tereus significantly increased the plant growth, nutrient uptake, and defense system. Treatment T4 (inoculated seeds), T5 (inoculated seeds + Zn100 mg/kg), and T6 (inoculated seeds + Ni 100 mg/kg) were effective, but T5 (inoculated seeds + Zn100 mg/kg) was the most pronounced and increased shoot length, root length, leaf width, plant height, fresh weight, moisture content, and proline by 49%, 38%, 89%, 31%, 113%, and 146%, respectively. Moreover the antioxidant enzymes peroxidase and super oxidase dismutase were accelerated by 211 and 68% in contaminated soil when plants were inoculated by A. tereus respectively. Similarly the inoculation of A. tereus also enhanced maize plants' absorption of Cu, Mn, Ni, Na, Cr, Fe, Ca, Mg, and K significantly. Results of the findings concluded that 100 mg/kg of Zn and Ni were toxic to maize growth, but seed inoculation with A. tereus helped the plants significantly in reducing zinc and nickel stress. The A. tereus strain may be employed as a potential strain for the detoxification of heavy metals.

Keywords: Agrococus terreus; Zea mays; antioxidant enzymes; endophytic bacterial; heavy metals stress; zinc contamination nickel contamination.

Grants and funding

The authors would also like to extend sincere appreciation to the Researchers Supporting Project Funding for the Construction of Key Laboratory of Soil Ecology and Environment (grant # 2023HNTRWRFZ-HNDX001). World River Basin Ecological Protection Information Project. Grant # GZS202304 and College of Geography and Environment, Henan University, Kaifeng China for research support.