Isolation and characterization of potential bacteria responsible for biodegradation of low-density polyethylene collected from garbage dump sites in Dhaka

Abstract

Being a multifaceted polymer, the recalcitrant Low Density Polyethylene (LDPE) has slowly gained popularity for ease of access while simultaneously becoming a threat to nature. This is why investigating diverse bacteria and exploring their natural capability to biodegrade LDPE has become a pressing matter in environmental biotechnology research. This study explores the LDPE biodegradation potential of bacteria isolated from half-degraded plastics from garbage dump sites. Significant weight loss (20%-30%) was detected from five isolated bacteria from pure cultures. 16sRNA gene sequence of three of them revealed them to be Bacillus sp. (in: Bacteria) strain JDMASP60, Bacillus atrophaeus strain MGB14, and Bacillus pumilus strain KD3 indicating their taxonomic novelty. Additional biodegradation examinations revealed their LDPE metabolization capability. Optical microscope analysis at 1000x magnification showed substantial amount of damage (cracks, grooves, and minor holes) on the polymer surface. FTIR showed a percentage increase in transmittance at the peaks 2918 cm^-1, 2852 cm^-1, 1468 cm^-1, 1373 cm^-1, 718 cm^-1, among many others indicating a decrease in native bonds. Moreover, a new peak corresponding to aromatic C=C bond at 1600cm^cm-1 was also reported. The study highlighted the biodegrading capability of naturally occurring bacteria at garbage dump sites while using LDPE as their sole carbon source.