Biodegradation of low-density polyethylene microplastic by new halotolerant bacteria isolated from saline mud in Bledug Kuwu, Indonesia

Abstract

Biodegradation of low-density polyethylene (LDPE) microplastics by newly halotolerant bacteria from saline mud in Bledug Kuwu, Indonesia was investigated. Of the eight bacteria, S. maltophilia BK1 and Enterococcus sp. BK3 showed a clear zone in agar containing LDPE and degraded 5 % and 6 % (w/w) of LDPE in artificial seawater after 90 d. During the biodegradation, the bacterial growth rate, biofilm formation, and hydrophobicity significantly increased after 40 d when the glucose concentration in the media was limited. Scanning electron microscopy (SEM) analysis displayed the destruction of the LDPE surface after treatment. Fourier transform infrared (FTIR) analysis showed the removal of the CC group at 861 cm−1, the addition of alkyl at 1019–1058 cm−1, and hydroxyl groups at 3000–3500 cm−1, indicating biodegradation. X-ray diffraction (XRD) analysis corroborated the degradation by decreasing the crystallinity index from 36 % (control) to 23 % (BK1) and 24 % (BK3), respectively.