World Aquaculture Singapore 2022

November 29 - December 2, 2022

Singapore

IN VITRO ACTIVITIES OF ORGANIC ACIDS AGAINST Tenacibaculum maritimum AND Streptococcus iniae BACTERIAL PATHOGENS OF FISH SPECIES

Low Wen Jie *, Miyata Masato and Musthaq S Khader

 

School of Applied Science, Temasek Polytechnic

21, Tampines Avenue 1

Singapore 529757

lowwenjie09@gmail.com

 



In aquaculture industry, antibiotic growth promoters have used as feed additives to treat fish diseases and improve their growth. However, the continued use of antibiotics for treatment will eventually cause the development of antibiotic resistance in fishes, as well as humans when they consume the fishes. This has led the aquaculture industry to search for alternatives towards antibiotics for the treatment and growth performance of fishes. The combinations of organic acids (OAs)/salts are becoming popular for usage in the feeds of animals, poultry and aquaculture as an alternative toward antibiotics. In addition, they have shown to have antimicrobial and growth-improving properties with any known adverse effect on poultry species. Hence, this study aims to develop the effects of various food grade OAs/salts on two economically important disease-causing bacteria found in food fishes, Tenacibaculum maritimum and Streptococcus iniae. Doubling dilutions of OAs/salts or combinations of OAs/salts from sodium acetate (SA), citric acid (CA), ascorbic acid (AA), and benzoic acid (BA) were chosen to determine their efficiency in inhibiting the growth of bacteria by microtitre broth dilution method. The results revealed that AA and CA were observed to have the higher inhibitory effect at final concentrations of 50mg/ml and 25mg/ml against 106 cfu/ml of T.mar and S.iniae respectively, compared to various concentration of SA and BA at 20 hpi. Further, the bacterial growth curve analysis of T.mar or S.iniae inhibited by AA+CA blends with final concentration of 25mg/ml showed bacterial growth reduced significantly at 10 hpi. Therefore, the results concluded that the CA+AA blend had potentially effect and can be used to alternatives to antibiotics in the treatment of S.iniae and T.mar bacterial infections. However, further study is required to conclude OAs/salts activities in vivo efficacy test with OAs/salts incorporated feed for fish.