Biodegradation of plasticizer benzyl butyl phthalate by Paenarthrobacter sp. strain M76 in liquid culture and soil microcosms.

Phthalate esters, a plasticizer widely used in various plastic-based consumer products, readily leach into the environment and later on, significantly threaten human health and ecosystems. Among them, benzyl butyl phthalate (BBP), a significant environmental contaminant, is classified as a hazardous chemical due to its toxic effects on aquatic and terrestrial life forms. In this study, we evaluated the biodegradation of BBP in batch culture and in soil microcosms using a Gram-positive bacterium, Paenarthrobacter sp. strain M76, isolated from a plastic waste dump yard in Puducherry, India. HPLC analysis confirmed that BBP (0.5 g/L) was completely degraded by M76 within 13 days at 28 °C, under shake culture conditions. To evaluate its applicability in real soil samples, a soil microcosm experiment was conducted using BBP and M76, which showed significant degradation of 60.00% and 64.21% of BBP within 20 days in sterilized and unsterilized soil, respectively. An intracellular esterase enzyme was responsible for initiating BBP biodegradation. Pathway metabolites were identified using different chromatographic and spectrophotometric assays, and degradation mechanisms were established. To the best of our knowledge, this is the first report of BBP biodegradation by a single Paenarthrobacter strain in soil microcosms and in liquid media. The outcomes underscore the adaptability and capacity of strain M76 to efficiently eradicate BBP from contaminated soils, positioning it as a promising candidate for BBP degradation in terrestrial environments.