Evaluating the antibacterial and antibiofilm potential of sulphated polysaccharides extracted from green algaeChlamydomonas reinhardtii

Abstract

In this study, antibacterial and antibiofilm potential of sulphated polysaccharides (SPs) extracted from Chlamydomonas reinhardtii (Cr) was evaluated against Neisseria mucosa, Escherichia coli, Streptococcus sp. and Bacillus subtilis. Antibacterial potential of Cr-SPs was evaluated by agar-cup diffusion, time-kill and colony-forming ability (CFU), minimum inhibitory and bactericidal concentration assays. Antibiofilm potential was evaluated by biofilm inhibition, eradication, extracellular-DNA, metabolic activity and microscopy assays. Cr-SPs at 0·5mgml-1 showed 34·52, 48·6, 66·1 and 55·6% reduced CFU in B. subtilis, Streptococcus, N. mucosa and E. coli respectively. Minimum inhibitory concentration of Cr-SPs was as low as 480μgml-1 for Streptococcus, N. mucosa and 420μgml-1 for B. subtilis and E. coli. At 1mgml-1 , Cr-SPs showed 50% biofilm inhibition, whereas 4-8mgml-1 showed 100% inhibition. Cr-SPs also effectively dissolved preformed biofilms. Dose-dependent reduction in extracellular DNA revealed that Cr-SPs interacts with the extra polymeric substance of the biofilm and destroys them. Light microscopy reconfirmed the above results. Cr-SPs not only inhibited biofilm formation but also effectively dissolved preformed-biofilms. The current study showed the promising potential of Cr-SPs as antibiofilm agents. Further validation will help in developing Cr-SPs as natural antibiotics against biofilm-causing bacteria.