Purification, characterization and functional analysis of the immune molecule lectin from the haemolymph of blue swimmer crab Portunus pelagicus and their antibiofilm properties

The present study reveals purification and characterization of immune molecule lectin from the haemolymph of blue swimmer crab Portunus pelagicus (Pp-Lec). The Pp-Lec was purified by affinity chromatography with mannose coupled sepharose CL-4B column and it exhibits single band with a molecular weight of 155 kDa in SDS-PAGE. The surface morphology of purified Pp-Lec displays the homogeneous nature of protein. A distinct peak with a retention time of 3.3 min was appeared in high performance liquid chromatography (HPLC) and X-ray diffraction (XRD) analysis expresses a single peak at 31.5° which shows the purity and crystalline nature of the protein respectively. Functional analysis of purified Pp-Lec exhibits encapsulation activity against sepharose beads and yeast agglutination activity against Saccharomyces cerevisiae. Moreover, the purified Pp-Lec has the ability to agglutinates with the human erythrocytes among tested and which was observed by light microscopy. In addition, purified Pp-Lec showed the broad spectrum of antibacterial activity against Gram-positive Bacillus pumulis, Bacillus thuringiensis, Enterococcus faecalis and Gram negative Citrobacter amalonaticus, Vibrio parahaemolyticus, Pseudomonas aeruginosa, Proteus vulgaris, Citrobacter murliniae, Citrobacter freundii, Morganella morganii. Antibiofilm potential of purified Pp-Lec against selective Gram-negative bacteria showed the disruption of biofilm architecture at the concentration of 50 μg ml−1.