Isolation and identification of bacteria from solid waste deposit sites for the degradation of heavy metals

Abstract

Heavy metals from solid waste deposits that are toxic, mutagenic, and carcinogenic contaminate natural water supplies and agricultural environments. The purpose of this project is to separate and characterize naturally occurring bacteria that can reduce and detoxify heavy metals (lead, cadmium, nickel, zinc, manganese, iron, copper, chromium, and mercury) from solid waste dumping sites. Ten strains in total were isolated from the samples; the two best-performing isolates, Shewanella oneidensis strain AGB 4 (Isolate 5) and Bacillus pumilus strain AGB 11 (Isolate 6) were recognized up to the genus level based on their 16S rRNA identification studies. These isolates demonstrated resistance to every heavy metal that was examined in the solid waste. The MICs for the two isolates varied in relation to the amounts of the heavy metals listed above. The solid waste isolates grew best at pH 7.0, 30°C and an incubation period of 24 hours. Utilizing an atomic absorption spectrophotometer to measure degradation potential, Shewanella oneidensis demonstrated the most removable capability for copper (60%) and the lowest removable capability for lead, arsenic and mercury (45%) and Bacillus pumilus demonstrated a reduction of 48% in mercury and arsenic and 65% in copper. Bacillus pumilus and Shewanella oneidensis may be able to break down heavy metals through plasmids, which could be used to change plasmids so they can carry the ability to accumulate heavy metals. Thus, determining the resistance to heavy metals and biodegradation potential of two bacteria could serve as a foundational investigation for the development of viable local biological remediation agents in solid waste deposit sites.