Isolation and characterization of two lytic bacteriophages against Staphylococcus aureus from India: newer therapeutic agents against Bovine mastitis.

Bovine mastitis causes severe economic losses to dairy farmers. Staphylococcus aureus, is one of the most important pathogen implicated in etiology of clinical and subclinical mastitis in bovines. In view of increasing antimicrobial resistance alternatives to antibiotic therapy are much needed. The present decade has witnessed a renewed interest in phage based therapeutics and diagnostics. The present study, describes isolation and characterization of two lytic phages SAJK-IND and MSP against Staphylococcus aureus having a potential to be used in therapy against mastitis. SAJK-IND and MSP phages belonged to Myoviridae and Podoviridae families, respectively. TEM imaging of the two phages revealed an iscosahedral head. MSP phage has a short non contractile tail. SAJK-IND and MSP have a burst size of 44 ± 3 and 25 ± 5 PFU/ infected cell, respectively. SAJK-IND and MSP phages revealed ̴ 12 and ̴16 proteins, respectively on SDS-PAGE analysis. The lytic activity of the phages was specific for Staphylococcus aureus. SAJK-IND revealed 100% lytic activity against several strains of Staphylococcus aureus isolated from mastitis milk samples whereas, MSP had only 40% lytic activity. SAJK-IND phage genome was sequenced, assembled and deposited in Genbank under accession no MG010123.