Biofilm-mediated biodeterioration of LDPE strips by an Adriatic sea Vibrio parahaemolyticus strain

The natural degradation of macroplastics (MAPs), particularly polyethylene (PE), takes a long time and can lead to the persistence of microplastics (MPs) in the marine environment. In recent years, research has focused on alternative methods to traditional ones for plastic degradation, particularly biodegradation through microbial activity. This study aims to investigate the biofilm formation dynamics of a V. parahaemolyticus strain on low-density polyethylene (LDPE) strips and the resulting physicochemical alterations induced in the polymer over an 80-day laboratory incubation period. This strain named VPDOP1 was isolated through a targeted in situ colonization experiment on PE macroplastics in the Adriatic Sea. VPDOP1 strain was identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and whole-genome sequencing (WGS). Its biodegradation potential was preliminarily assessed using the clear-zone method in a culture medium containing LDPE powder as the sole carbon source. Subsequently, VPDOP1’s ability to form biofilms and the morphological changes on the LDPE strips were analyzed using scanning electron microscopy (SEM) after 40 and 80 days of incubation, while simultaneously assessing weight loss and chemical changes via Fourier-transform infrared spectroscopy (FTIR). Finally, VPDOP1’s ability to produce hydrolytic enzymes such as amylase, gelatinase, and lipase was determined using a plate assay. The VPDOP1 strain produced lysis halos using the clear-zone method. After 40 and 80 days of incubation at 25 °C, a weight loss of 5.5 and 7.6%, respectively, was observed in the LDPE strips compared to the control. At the same time, SEM and FTIR analyses revealed morphological and chemical changes. VPDOP1 exhibited amylase, gelatinase, and lipase activity. This study provides timely and relevant evidence that a marine-derived V. parahaemolyticus strain can form biofilms on LDPE strips and induce measurable surface biodeterioration under laboratory conditions highlighting its promise for future studies on its potential to fully biodegrade marine plastic debris.