Potential of Linear Low-Density Polyethlene (LLDPE) Plastic Degradation by Mixed-Cultured Bacteria in Controlled Environment

Abstract

This preliminary study was aimed to determine the ability of mixed-cultured
Pseudomonas aeruginosa and Brevibacterium sp. in degrading Linear Low-Density
Polyethylene (LLDPE). This study was started by preparing the plastics into 1x1 cm2 cut
mechanically. The plastics were placed in a petri dish containing Nutrient Broth (NB)
media and mixed-cultured bacteria. The variations of bacterial composition (%) were 10,
50, and 75; variations of temperature (oC) were 25, 30, 35; variations of acidity (pH)
were 5, 7, 9; and variations of contact time (Td; days) were 10, 30, 60, and 90. LLDPE
plastic degradation was analyzed using gravimetry, Fourier Transform Infra-red (FTIR)
and Scanning Electron Microscope (SEM). Both bacteria were resistance or non-sensitive
to LLDPE substance as xenobiotic substrate. According to gravimetry and FTIR analysis,
the highest removal was at 30oC, pH 7, with bacterial composition of 75% (v/v) incubated
for 30 days. Gravimetry analysis result showed a loss of LLDPE plastic weight from
0.1548 gram to 0.1464 gram, or 70.67%. The result was reconfirmed using SEM analysis,
which showed morphological changes of LLDPE plastic sample surface. Although the
degradation occurred very slow, mixed-cultured bacteria has a potential for capacity
increase in degrading LLDPE in further studies, including the addition of co-substrate in
continuous culture.