Enumeration of Aerobic Heterotrophic Bacteria in Early-Stage of Biofilm Formed on Different Plastic Types

Abstract

In this study, the total number of aerobic hetetotrophic bacteria (AHB) in early-stage of biofilm formed on different plastic types commonly used in daily life, namely polyethylene (PE), polypropylene (PP), polystyrene (PS) was investigated in a water recirculating test system. The Golden Horn Estuary’s water was used as a system water. The test system was operated continuously for 504 h and natural biofilm formation was ensured. The physicochemical properties of system water were measured each sampling time. Bacterial attachment was observed on all plastic surfaces even within the first hours. Also, macroscopic images proved that the biofilm layer formed and flourished on all plastic surfaces over time. After 504 h, the levels of AHB on the plastic coupons were detected as 1.4×105, 1.2×105 and 1.8×105 cells cm−2 for PE, PP and PS, respectively. To investigate the number of bacterial cells in early-stage of biofilm formation on plastic surfaces will create an important basis for future research in terms of evaluating the effects of microplastics on the environment and human health.