Improvement of Zea mays L. growth parameters under chromium and arsenic stress by the heavy metal-resistant Streptomyces sp. NRC21696
2022
AL-Huqail, A. A. | El-Bondkly, A. M. A.
El-Rahawy drain passes through many governorates, uses to irrigate soil and plants in neighboring villages and causes pollution to the Nile River. Although Zea mays L. is one of the major strategic crops being cultivated in Egypt, metal stress especially arsenic and chromium is serious threats to its productivity. We aim to isolated plant growth promoting actinobacterial isolates from the microbiome present in the contaminated water, soil and plants from El-Rahawy drain have the ability to remove chromium and arsenic from the wastewater and then improve maize productivity under stressed conditions. Among 153 actinobacterial isolates obtained, endophytic Streptomyces sp. NRC21696 isolated from Morus alba L. proved to be the hyper-active plant growth promoting isolate, it gave the highest amounts of twenty two plant growth regulators metabolites along with biocontrol activity against phytopathogenic fungi and bacteria. Moreover , Streptomyces sp. NRC21696 showed extremely heavy metal resistant and removal against Ni²⁺, Zn²⁺, Fe³⁺, Cu²⁺, Cd²⁺, Ag⁺, Al³⁺, Hg²⁺, Mn²⁺, As³⁺, As⁵⁺, Cr⁶⁺, Co²⁺ and Pb²⁺ from wastewater. It also proved to be an efficient inoculant for healthier maize in normal and stressed conditions of As³⁺ and Cr⁶⁺, significant increases in the germination percentage; rate and index, shoot and root tolerant indexes, fresh and dry weights, lengths of leaf; root and cob and photosynthetic pigments. Based on PGPE Streptomyces sp. NRC21696 ability to remove 14 heavy metals from wastewater along with enhancing corn yield, it can be used as ecofriendly remediation technology of multi-metals contaminated areas and as a protector of plants under metal stress to guard the environment and community health.
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