MARINE ACTINOMYCETES AS BIOREMEDIATORS IN SHRIMP CULTURE SYSTEM
Actinomycetes are potential source of bioactive compounds and highly versatile agents of biodegradation. Eventhough considerable work has been carried out on terrestrial actinomycetes, their marine counterparts remain less explored. The present study was focused on testing the potential of actinomycete isolates for bioremediation in shrimp culture systems. Actinomycetes were isolated from the marine environment (Arabian Sea) and culture ponds (Cochin, Kerala, India) and they were screened for hydrolytic enzyme production (protease, amylase, lipase, pectinase, ligninase and chitinase), antibacterial potential (against aquaculture pathogens), denitrification and biogranulation property. Of the 270 actinomycete isolates 99.1% were proteolytic ,74.2% amylolytic, 92.9% lipolytic, 12.3% pectinolytic, 15.5% ligninolytic and 47.1% chitinolytic. Isolates with notable hydrolytic potential (58 Nos) were tested for organic matter degradation property and a significant reduction in organic matter could be observed on application of these actinomycete biogranules in shrimp culture system. Significant reduction in vibrios also could be observed in penaeid prawn culture systems and therefore these isolates were segregated for application as biocontrol agents in aquaculture. Sea water was found to be the best storage medium for the actinomycete biogranules, stability being estimated in terms of ATP as proxy to microbial biomass. When stored in sea water, the biogranules were found to be stable at both room temperature (28 ±20C) and at 40C for a period of 3 months.