Galleria Mellonella: a living source of plastic biodegrading microorganisms

Abstract

[eng] Plastic polymers have become a cornerstone in modern society due to their advantageous properties and numerous applications in a plethora of industries and manufacturing sectors. However, it was soon discovered how these novel materials were a double-edged innovation: their high inherent durability alongside a poor management of plastic waste have led to an impending environmental threat that is rapidly escalating, despite most recent governmental policies and budding alternatives. One of the most promising approaches comes from the microbiological research field and relies on the commendable isolation efforts that are being conducted to discover potential plasticbiodegrading microorganisms. These isolates, each one with its peculiar biodegradation efficiency, are being found in a wide array of natural and man-made environments. Nonetheless, some insects have recently become the centre of attention in the scientific community as promising living sources for the isolation of new plastic-biodegrading microorganisms. Following this line of reasoning and considering the latest studies on this subject, this works investigates the suitability of Galleria mellonella larvae (a common beehive pest) as a living source of polyethylene-biodegrading microorganisms, owing to the structural similarity between polyethylene and beeswax, an essential component found in natural beehives. In order to do so, a culture-dependent approach was followed to assess the effect of different dietary regimens on G. mellonella’s microbiota and its putative PE-biodegrading capability. The results revealed that, despite common bias associated with the techniques used, specific diets are key in shaping the larva’s microbiota and, hence, could be exploited to facilitate the isolation of microorganisms able to metabolise PE-derived metabolites.