Antibiofilm potential of Lactobacillus plantarum spp. cell free supernatant (CFS) against multidrug resistant bacterial pathogens

Introduction Traditional dairy products have been considered as good sources of lactic acid bacteria (LAB) and ideal vehicles to deliver beneficial bacteria to human gastrointestinal tract. LAB are good candidates to be used as probiotics due to their non-pathogenic nature, good antimicrobial activity and resistance to gastrointestinal condition (1). Multi-drug resistant bacteria are involved with several community acquired and nosocomial infections as well as foodborne diseases. Biofilm formation is regarded as a major determinant factor in development of infection by pathogenic bacteria (2). Biofilm is a community of microorganisms adhering to each other on a surface which is surrounded by a matrix of extracellular polymers. Bacteria embedded in a biofilm are more resistant to antimicrobials due to the reduction of antimicrobial penetration, slower bacterial metabolic state as well as easier exchange of resistance genes among cells (3). The resistant nature of biofilm is a matter of great concern for global health care system and many studies have been conducted to explore novel, natural and effective antibiofilm agents. Fermented milk products contain different types of LAB which could be able to inhibit many pathogenic and spoilage microorganisms. Antagonism is attributed to the release of a variety of functionally active compounds including organic acids, exopolycacharides and bacteriocins which are naturally released into the bacterial growth medium. These compounds have antibacterial and antibiofilm potentials which are able to inhibit bacterial infectivity. Several studies have reported antibiofilm potential of bacteriocines produced by LAB bacteria (4-5). Moreover, some studies reported that a number of exopolysacharides isolated from commercial fermented milk were capable of interfering with the adhesion of several enteric pathogens (6-7). The LAB from traditional cheese may produce bioactive compounds with antibiofilm activity and could be used for prevention of bacterial infections and food spoilage (4). However, the stability of these bioactive compounds under unfavorable conditions needs to be characterized. Thus, the current work was conducted to investigate and characterize antibiofilm potential of the cell free supernatant (CFS) of Lactobacillus plantarum spp, isolated from Siahmazgi cheese, a traditional cheese from province Abstract Biofilm formation is a major determinant factor in development of bacterial infections. In addition, bacteria embedded in a biofilm are more resistant to antimicrobials and thus the ability of bacteria to persist and grow in a biofilm seems to be the major factor for pathogenesis and therapeutic failure. In the current study, a Lactobacillus plantarum spp was isolated from Siahmazgi cheese, traditional cheese of Guilan province, Iran, and was identified using morphological, biochemical and molecular identification assays. Antibiofilm potential of the Lactobacillus plantarum spp cell free supernatant (CFS) against multidrug resistance Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli was characterized. According to the results, the CFS not only reduced biofilm formation by pathogenic bacteria, but also disrupted preformed biofilms. The CFS remained unaffected by chemicals including EDTA, SDS and Tween 80, and showed stability at high temperatures (80 and 100 ̊C), as well as a wide range of pH. However, the antibiofilm activity was inhibited after treating with proteinase K. According to these results, L. plantarum spp could be regarded as a suitable strain to produce antibiofilm agents which could be used for preventive and therapeutic approaches.