Development of Bio-floc with a Lead Metal Reduction Approach from Liquid Medium In Vitro

Considering the high environmental stability of lead and its easy transmission through food chains as well as its well-documented destructive impacts on living cells, the present study was aimed at investigating the applicability of effective bacteria for elimination or reduction of lead through the development of microbial flocculation. In order to isolation of lead-resistant bacteria, the sample of activated sludge was cultivated on BHI Agar medium with 1000ppm lead standard solution, incubated at 30°C for 24 hours. Resistance and reduction of lead was investigated by Atomic Absorption analysis. MIC and MBC of the samples were determined and the most lead-resistant bacterial strain was evaluated. The ability of the selected strain in development of bio-floc and lead reduction by fish food (fish color) as the bacterial nutrition source and bed was studied. 16S rRNA sequencing was used to identify and confirm of selected strain. from 25 isolated strains, the most lead-resistant bacterium was demonstrated the MIC and MBC of 8280 and 12420ppm, respectively. Atomic Absorption analysis showed this strain was reduced 98% of lead. The ability of bacterium to produce bio-floc and lead reduction was evaluated 120g/L and 84%, respectively. Biochemical and molecular analysis of the selected strain was confirmed 99% as Bacillus subtilis. Bacillus subtilis isolated in this research can be a good alternative to production of biological sludge for treatment of wastewater and ponds of fish and shrimp farming pools contaminated with this metal.