Initial Screening of Halophilic Plastic-Degrading Bacteria from Mangrove Water and Sediment in Pekalongan, Indonesia

Abstract

Microplastic pollution in tropical mangrove ecosystems represents an increasing environmental concern, particularly in coastal regions such as Pekalongan, Indonesia, where industrial and residential activities contribute substantially to plastic waste. This study aimed to isolate and preliminarily screen halophilic bacteria from mangrove sediments and seawater collected from a plastic-impacted coastal area. Using mineral salt medium (MSM) supplemented with polyethylene glycol (PEG), six bacterial strains were obtained and evaluated for their potential to interact with polyethylene (PE) and polypropylene (PP) on the basis of gravimetric weight loss measurements. Among the isolates, Halomonas Cupida A1, Marinobacter nauticus A6.3, and Marinobacter nauticus SD5.2 exhibited relatively greater plastic-associated weight loss during the 15-day incubation period. The greatest weight loss was observed for polyethylene with isolate SD5.2 (1.0%), whereas isolate A1 resulted in the greatest amount of polypropylene-associated weight loss (0.301%). Although the observed reductions were modest and derived from preliminary screening, gravimetric weight loss alone does not confirm plastic biodegradation. Therefore, the results indicate that only potential indigenous halophilic bacteria are involved in plastic-associated processes in saline mangrove environments. This study provides baseline data for future investigations incorporating molecular, enzymatic, and surface characterization analyses to further elucidate plastic biodegradation mechanisms and enhance bioremediation applications in coastal ecosystems.