Biofilm formation on different surfaces in aquatic environments and antibiofilm effect of lactobacillus plantarum

In this study, the isolation and identification of bacteria forming biofilms on different surfaces in seawater and lake water were carried out, and the effect of the cell-free supernatant of Lactobacillus plantarum ATCC 8014 on inhibiting biofilm formation was investigated. Microscope slides, galvanized steel, and aluminum coupons were prepared to allow biofilm formation, and the biofilms formed on these surfaces were analyzed to determine total bacterial count and extracellular polymeric substances (EPS), including total carbohydrate and protein content. Bacteria isolated from the biofilm were identified using MALDI-TOF/MS. Metagenomic analysis was conducted to compare bacteria present in seawater and lake water with those in the biofilm. Scanning electron microscopy (SEM) was used to examine the biofilm formation on the coupons. The biofilm-forming ability of identified bacteria was assessed, and the cell-free supernatant of L. plantarum ATCC 8014 was evaluated for its antibiofilm and biofilm-disrupting effects. The results showed no significant differences in bacterial counts across different surfaces. The total protein content of EPS was found to be higher than the carbohydrate content, and both components were observed to be utilized by bacteria under starvation conditions. Among the bacteria isolated and identified by MALDI-TOF/MS, strains such as Micrococcus luteus, Bacillus amyloliquefaciens spp. plantarum, and Sphingobium yanoikuyae demonstrated strong biofilm-forming abilities. Strains like Bacillus amyloliquefaciens and Bacillus cereus exhibited moderate biofilm-forming capacities, while Bacillus endophyticus and Brevibacillus parabrevis showed weak biofilm formation. Bacillus mojavensis, Acinetobacter schindleri, and Chryseobacterium shandongense strains were found to have no biofilm-forming ability. Metagenomic analysis revealed that biofilms are dynamic structures with temporal changes in bacterial populations. The cell-free supernatant of L. plantarum ATCC 8014 demonstrated antibiofilm and biofilm-disrupting effects on biofilm-forming strains. Based on these findings, it is suggested that rather than focusing on different surface materials, identifying the bacteria forming the biofilm and targeting them specifically would be more effective for biofilm prevention. Additionally, applying the cell-free supernatant used in this study as a coating on different surface materials or as an alternative to biocides could facilitate the development of environmentally friendly products.