Antimicrobial activity of peptides isolated from the haemolymph of Antheraea assamensis larvae

Development of multidrug resistance in infectious microbes is a common phenomenon and hence the search for alternatives with better activity continues. Silkworm antimicrobial peptides have been quite resourceful in this aspect as they are known to be potent against various bacteria, viruses and fungi. This study assesses the antimicrobial potentials of the peptides isolated from Bacillus thuringiensis immunised 5th instar lava of the Muga silkworm (Antheraea assamensis). The proteins produced as a result of immunization were isolated from the haemolymph and purified partially by acid-methanolic extraction which was then subjected for separation and purification by semi preparative RP-HPLC. The collected fractions were analysed for purity by SDS-PAGE following which, antimicrobial activity assay was performed against Gram-positive (Bacillus thuringiensis) and Gram-negative bacteria (Escherichia coli). Among the obtained eight purified fractions, seven fractions showed different ranges of antimicrobial activity. Amongst them, two fractions were seen to show antimicrobial activity against both Gram positive as well as Gram negative bacteria.