Wahidatul H. Zuldin1,2, Siti Nurnilam S.N. Nain3 and Nur Azeera Aming3
1Borneo Marine Research Institute, Universiti Malaysia Sabah, Jalan UMS 88400 Kota Kinabalu, Sabah, Malaysia
2 Seaweed Research Unit, Universiti Malaysia Sabah, Jalan UMS 88400 Kota Kinabalu, Sabah, Malaysia
3 Faculty of Science and Natural Resources, Universiti Malaysia Sabah, Jalan UMS 88400 Kota Kinabalu, Sabah, Malaysia
Sea grapes, Caulerpa lentillifera, are a type of green seaweeds that play an important role in aquaculture production and have been used for centuries as human food. Due to high demand, the cultivation of sea grapes has expanded not only in Sabah but also in peninsular Malaysia. The increasing cultivation of C. lentillifera has led to increases in disease, particularly bacterial invasion. Disease can impact quality and production of C. lentillifera. However, little is known about the structure and diversity of the microbial community in C. lentillifera. Furthermore, particularly in Malaysia, there is lack of information and research on bacterial infection and disease in cultivated C. lentillifera. Thus, the purpose of this study is to identify the possible bacterial infection that occurred in tank-cultured sea grapes, C. lentillifera using two types of culture systems (Recirculating Aquaculture System, RAS and static system). For this study, C. lentillifera was bought from the Filipino wet market (transported from Semporna Sabah) in Kota Kinabalu. The possible bacteria were isolated using two types of culture media, Tryptone Soy Agar (TSA) and MRS Agar. Several tests were used to purify and identify the possible bacteria, including gram staining, catalase test, and oxidase test. The result indicated several types of species identified as the possible cause for bacterial infection in C. lentillifera that has been compared with the previous study which were Vibrio sp. and Cytophaga sp., (related to the “ice-ice” disease and “rotten thallus syndrome”) as well as Flavobacterium sp., Psychrobacter sp., Psychromonas sp., Bacillus sp., Pseudoalteromonas sp., Pseudomonas sp., Oceanobacillus sp. Xanthomonas sp., and Achromobacter sp. that also found in the tank-cultured C. lentillifera. Among all the samples, bacterial colony counts of sea grapes samples in RAS, detected in MRS agar was higher (23.033 ± 10.595) compared to static system. Deeper study is required to further identify the bacteria species using molecular techniques, biochemical test, or PCR amplification of 16S rDNA.