Lead-Tolerant Bacillus Strains Promote Growth and Antioxidant Activities of Spinach (Spinacia oleracea) Treated with Sewage Water

Abstract

Irrigation with sewage-contaminated water poses a serious threat to food security, particularly in developing countries. Heavy metal tolerant bacteria are sustainable alternatives for the removal of wastewater contaminants. In the present study, four lead (Pb)-tolerant strains viz. Bacillus megaterium (N8), Bacillus safensis (N11), Bacillus sp. (N18), and Bacillus megaterium (N29) were inoculated in spinach and grown in sewage water treated earthen pots separately and in combination with canal water. Results showed that Pb-tolerant strains significantly improved plant growth and antioxidant activities in spinach and reduces metal concentration in roots and leaves of spinach plants irrigated with treated wastewater. Strain Bacillus sp. (N18) followed by B. safensis (N11) caused the maximum increase in shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, and leaf area compared to the uninoculated control of sewage water treated plants. These strains also improved antioxidant enzymatic activity including catalase, guaiacol peroxidase dismutase, superoxide dismutase, and peroxidases activities compared to the uninoculated control under sewage water conditions. Strain Bacillus sp. (N18) followed by B. safensis (N11) showed the highest reduction in nickel, cadmium, chromium, and Pb contents in roots and leaves of spinach compared to the uninoculated control plants treated with the sewage water. Such potential Pb-tolerant Bacillus strains could be recommended for the growth promotion of spinach after extensive evaluation under field conditions contaminated with wastewater.

Bioremediation potential of Brevibacillus parabrevis AMB‐CD‐2 in spinach under lead toxicity

“…The present study is in close confirmation with the work performed by Najm‐ul‐Seher et al (2021) where they reported that the inoculation of the strain Bacillus sp. (N18) caused a considerable increase in shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, and leaf area of spinach plants when compared to the uninoculated control of sewage water‐treated plants.…”

Growth Promoting Activity of Lead Resistant Bacillus Subtilis Isolated from Petrochemical Waste Water at Haldia, West Bengal on Indian Mustard Saplings Under Metal Stress

“…Fifty seeds of both species were sown in each pot. Four sets were prepared for both seeds: (i) Control (non-inoculated) (ii) Inoculated with lead resistant bacteria [T 1 ] (10 6 cfu/gm of soil) (iii) Inoculated with resistant bacteria and 1000ppm Pb(NO 3 ) 2 [T 2 ] (iv) Soil with 1000ppm Pb(NO 3 ) 2 [T 3 ] according to the method described 12 and modified to prepare the mentioned sets. All pots were allowed to grow for 4 weeks and were observed periodically for root, shoot and leaf development and results were recorded.…”