THE POTENTIAL INHIBITORY EFFECTS OF MICROALGAE AND MACROALGAE ON PROTEASE ACTIVITIES OF ARGYROSOMUS REGIUS (PISCES, SCIANIDAE) LARVAE USING IN VITRO ASSAYS

The aim of this research was to gather preliminary data about the potential inhibitory effects of microalgae and macroalgae on protease activities of meagre larvae using in vitro techniques. Three microalgae (Chlorella sp., Spirulina sp., Schizochytrium sp.) and two macroalgae (Ulva sp. and Sargassum sp.) were tested in the present study. Pooled samples of meagre larvae fed on commercial feeding procedure were collected thirteen times from 3 to 32 days after hatching (DAH). All tests were carried out in triplicates. The differences observed in the total length and weight values were statistically significant (p < 0.05). The lowest and highest weights were 0.54±0.02 mg (3 DAH) and 89.21±0.91 mg (32 DAH), respectively. The lowest and highest total length values were 3.22±0.02 mm (3 DAH) and 20.95±0.3 mm (32 DAH). The differences in protease activities of meagre larvae during the sampling period were statistically significant (p< 0.05). The highest and lowest protease activities of meagre larvae were 393.97±7.9 U/mg protein (7 DAH) and 9.64±1.25 U/mg protein (20 DAH), respectively. The greatest sensitivity to protease inhibitors present in the assayed algae was observed in Chlorella sp. with more inhibitions than 45%. The highest inhibitions of Schizochytrium sp., Spirulina sp. and Chlorella sp. were observed at 3, 5 and 10 DAH, respectively. The lowest inhibitions of Chlorella sp., Schizochytrium sp. and Spirulina sp. were found at 5, 10 and 12 DAH, respectively. The highest and lowest inhibitions of Ulva sp. and Sargassum sp. were determined at 5 and 20 DAH, respectively. Spirulina sp., Schizochytrium sp. and Ulva sp. had lower inhibitions than 45% except for 3, 5, 7 and 17 DAH. However, the inhibition values of Chlorela sp. were more than 45% from 3 to 32 DAH. The inhibitions of Sargassum sp. were determined as more than 45% except for 15,20,22,25 and 27 DAH. In conclusion Spirulina sp., Schizochytrium sp. and Ulva sp. can be used as feed ingredient in commercial diets of meagre larvae from 10 to 32 DAH except for 17 DAH. Chlorella sp. doesn’t seem to be suitable. Sargassum sp. can be used as feed ingredient from 15 to 32 DAH except for more inhibitions than 45%. Future researches must be conducted on feed ingredients exhibiting lower inhibitions on protease activities of marine fish larvae.