In vitro degradation of low-density polyethylene by new bacteria from larvae of the greater wax moth, <i>Galleria</i> <i>mellonella</i>

Abstract

Three bacterial species isolated from whole body extracts of the greater wax moth larvae, <i>Galleria mellonella</i>, were evaluated for their ability to utilize low-density polyethylene (LDPE) as a sole carbon source in vitro. These bacteria were identified as <i>Lysinibacillus</i> <i>fusiformis</i>, <i>Bacillus aryabhattai</i>, and <i>Microbacterium oxydans</i>. Their ability to biodegrade LDPE was assessed by growth curves, cell biomass production, polyethylene (PE) weight loss, and the presence of LDPE hydrolysis products in the growth media. Consortia of these bacteria with three other bacteria previously shown to degrade LDPE (<i>Cupriavidus necator</i> H16, <i>Pseudomonas putida</i> LS46, and <i>Pseudomonas putida</i> IRN22) were also tested. Growth curves of the bacteria utilizing LDPE as a sole carbon source revealed a peak in cell density after 24 h. Cell densities declined by 48 h but slowly increased again to different extents, depending on the bacteria. Incubation of LDPE with bacteria isolated from greater wax moth larvae had significant effects on bacterial cell mass production and weight loss of LDPE in PE-containing media. The bacterial consortia were better able to degrade LDPE than were the individual species alone. Gas chromatographic analyses revealed the presence of linear alkanes and other unknown putative LDPE hydrolysis products in some of bacterial culture media.