A potent fish pathogenic bacterial killer Streptomyces sp.isolated from the soils of east coast region,South India

Objective:To investigate the potentiality of the marine actinobacteria isolated from marine soil against fish pathogenic bacteria.Methods:east coast region(ECR)of Tamilnadu,South India.Then they were used for the isolation of actinobacteria by using conventional serial dilution technique on starch casein agar medium.The antibacterial activities of the actinobacteria were screened primarily by using cross streak plate method against fish pathogenic bacteria namely Vibrio alginolyticus,Vibrio parahaemolyticus,Vibrio cholera,Aeromonas sp.and Pseudomonas sp.The antimicrobial efficacy of the selected isolates was carried out with various organic solvents,and finally the active compound was subjected to chromatographic techniques including TLC and GC-MS.Results:In the present study,a total of 33 soil samples were collected from the Bay of Bengal,against fish pathogenic bacteria.Out of 21 antibacterial isolates,the isolate ECR77 was selected for further study based on its potential activity against fish pathogenic bacteria.Of the various solvents tested,the ethyl acetate extract had good antibacterial activity against the tested bacterial pathogens.The isolate ECR77 grew well on oat meal agar medium with 2%salt level at 35°C.GC-MS study found that the presence of bioactive compounds namely tetradecanoic acid,n-hexadecanoic acid and octadecanoic acid.The morphological,physiological,biochemical and cultural characteristics of the potential isolate were supported the identity up to generic level asStreptomyces sp.ECR77.Conclusions:The results obtained from this study concludes that the ECR soils of South India is a hot spot of novel bioactive compound producing marine actinobacteria with great pharmaceutical values.Of the 82 actinobacteria isolated,21(26%)isolates were possessed antibacterial activity.