Emerging compost extract for heavy metal bioremediation and preserving the antioxidant activity of celery cabbage: A sustainable approach

The study examined the efficiency of a combined bioadditive containing molasses with Bacillus firmus and Pseudomonas aeruginosa in the production of compost extract and their impact on the physiochemical, heavy metals bioremediation, and antioxidant activity in the plant. The methods involved aeration and a compost-to-water ratio of 1:10, following the CRD. The extract physiochemical parameters were measured. The extract heavy metals were determined according to ICP-MS (inductively coupled plasma-mass spectrometry). The activities of catalase, peroxidase, ascorbate peroxidase, and superoxide dismutase were determined using the methods of liquid portion. The results showed significant improvements in the pH from 5.5 to 8, Ec from 7.1 to 8.2, and O.M from 27.5% to 50%. The TN increased from 0.14 to 0.203 mg/kg, TP from 0.46 to 1.24 mg/kg, TK from 0.25 to 0.58 mg/kg, Ca from 20.3 to 25.11 mg/kg, and Mg from 10.75 to 7.75 mg/kg. Besides, the heavy metal bioremediation; Fe was lightly reduced from 8.3 to 7.4 mg/kg, Zn from 1.0 to 0.1 mg/kg, Cu from 0.1 to 0.01 mg/kg, and Cd from 0.1 to 0.02 mg/kg. CE significantly improved plant shoot and dry weight. The antioxidant activity of SOD and POD was significantly higher than APX and CAT. A positive correlation between physiochemical properties and heavy metals, while a negative correlation with antioxidant activity, specifically APX and POD. Beneficially, the application of CE enhances antioxidant enzyme activities, reduces heavy metal uptake in plants, and adopts healthier growth, thereby supporting sustainable agricultural practices. • The combining molasses with Bacillus firmus and Pseudomonas aeruginosa significantly improved key compost extract properties over 7–21 days. • The Molasses with both bacterial strains reduced heavy metals in compost extracts more effectively than using single strain. • Combined treatment significantly increased the activities of antioxidant enzymes and had higher shoot weight. • The combination of bacteria and molasses improved plant growth and bioremediation.