Plastic waste is a soaring crisis, so much so that islands of plastic have formed in our oceans. Polystyrene, a common plastic used in the form of foam, sheets, or molded into food containers, packaging, and even in lab equipment is a notorious contributor to the plastic waste problem. A recent article from Scientific American Magazine features an unusual solution to polystyrene waste; the beetle larvae Zophobas morio, which can feed on polystyrene foam. The crunching sound of polystyrene foam being chewed by beetle larvae is the first thing one hears upon entering the lab of microbiologist Dr. Chrisitian Rinke from the University of Queensland in Australia. Dr. Rinke’s research group found that the larvae could survive from nothing but polystyrene, highlighting their digestive system’s efficiency in breaking down the compound and using it as a nutritive source. In their recently published work, the research group divided 135 larvae into three dietary cohorts: wheat bran-fed, plastic-fed, and starved. Although the gains of the plastic-fed cohort were less compared to the bran-fed cohort, 2 out of 3 plastic-fed larvae still grew into adult beetles. Performing shotgun metagenomics with samples from the plastic feeders indicated that Pseudomonas, Rhodococcus and Corynebacterium possessed plastic feeding enzymes. Inferring genetic functions enriched in the plastic feeder larvae gut microbiome illustrated that the plastic-fed larvae’s gut microbiome was enriched in transposon movement, membrane restructuring, and oxidative stress response genes. In their study, Rinke and colleagues pointed out several enzymes that played a role in degrading the polystyrene. However, Dr. Bornscheuer, the head of the biotechnology and enzyme catalysis department at the University of Greifswald, underlined that, in using Dr. Rinke’s suggested order of enzymatic action, Dr. Bornscheuer could not break down carbon bonds in plastics. Understanding the correct order of enzymes responsible for breaking down polystyrene in the worm gut may be the key to industrial plastic decomposition, leading to a possible solution to plastic pollution.
Watch the video below to see Z. morio larvae munching on polystyrene.