There is some really amazing biochemistry going on here. The essential enzymes involved (and understanding their exact mechanism) would be of inestimable value for several reasons; a very large one you (jobu) suggest right here.
https://en.wikipedia.org/wiki/Polystyrene#Biodegradation
"... rates of styrene degradation ranged from 0.14 to 0.4 a−1. This is an order of magnitude faster than the most rapid rate of polystyrene degradation identified... Pseudomonas putida is capable of converting styrene oil into the biodegradable plastic PHA. This may be of use in the effective recycling of Polystyrene foam, otherwise thought to be non-biodegradable."
https://en.wikipedia.org/wiki/Polystyrene#Biodegradation "... rates of styrene degradation ranged from 0.14 to 0.4 a−1. This is an order of magnitude faster than the most rapid rate of polystyrene degradation identified... Pseudomonas putida is capable of converting styrene oil into the biodegradable plastic PHA. This may be of use in the effective recycling of Polystyrene foam, otherwise thought to be non-biodegradable."