BRAHMAPRAKASH, G.P.SANTHOSH, G. P.2017-02-202017-02-202008-06-22Th-9046http://krishikosh.egranth.ac.in/handle/1/5810001779The present study focussed on isolation, screening and characterization of antimicrobial peptides from invertebrates. Sixteen invertebrates were screened for their antimicrobial activity against six microorganisms. Body fluid extracts of immune activated invertebrates (with overnight grown culture of Escherichia coli) exhibited higher antimicrobial activity compared to unchallenged ones. Higher invertebrates exhibited good antimicrobial activity even without immune activation. Body fluid extracts of selected invertebrates when subjected to 60o C, 100o C (boiling temperature of water) and 121o C (autoclaving temperature) for 15 min, extracts showed thermo-stability by exhibiting antimicrobial activity even with increased temperature levels. Antimicrobial activity of body fluid extracts was reflected on its minimum inhibitory concentration. Body fluid extract of selected invertebrates exhibiting higher antimicrobial activity was found to be active even at lower concentrations. Most active concentration for inhibition of test organism was observed when assayed without dilution. Total protein content of body fluid extracts of invertebrates decreased after being challenged compared to unchallenged ones. However there was variation in carbohydrate contents of challenged and unchallenged body fluid extracts. Protein fractions in both unchallenged and challenged body fluid extracts of invertebrates were similar, except in case of Samia cynthia ricini and Hirudo medicinalis. Minimum inhibitory concentrations of purified fractions of body fluid extracts of selected invertebrates showed that, most effective concentration was, when they were used without dilution. Though activity spectrum of body fluid extracts of invertebrates was wide, purified peptides of selected extracts exhibited activity only against Escherichia coli.ennullThesis