Isolation and identification of lipolytic bacterial from the digestive tract of ricefield eel (Monopterus albus)

Abstract

Abstract. Berlian IN, Susilowati A, Pangastuti A. 2020. Isolation and identification of lipolytic bacterial from the digestive tract of ricefield eel (Monopterus albus). Bioteknologi 17: 27-36. Lipolytic bacteria are bacteria that produce lipase enzymes. These bacteria can be isolated from various sources containing fat. Lipid is one of the nutrients needed by rice field eel (Monopterus albus Zuiew, 1973) to live and grow. In the digestive system of fish, typhoid bacteria are used to hydrolyze lipids and oils into fatty acids and glycerol, which are needed in metabolic processes. This study aims to obtain isolates of lipolytic bacteria from the digestive tract of rice field eels and to determine the identity of lipolytic bacteria that can be isolated from the digestive tract of rice field eels. The obtained rice field eels were rested and fasted for 8 hours. Then, the eels were dissected. The digestive tracts were cleaned and used. Isolation of bacteria used minimal media enriched with olive oil. Lipolytic bacteria screening used Rhodamine B Agar. Macroscopic morphological characterizations are colony shape, edge, color, and elevation. Microscopic morphology is cell shape, cell size, and gram of bacteria. The hemolysis test aimed to determine hemolysis activity using Blood Agar (BA). Molecular characterization was based on the sequence of genes encoding 16S rRNA. The results of lipolytic bacterial DNA sequences were analyzed using the NCBI BLAST Nucleotide Website (www.blast.ncbi.nlm.nih.gov/blast.cgi). Based on the isolation results, 63 isolates were obtained with 11 isolates of positive lipolytic bacteria. Positive lipolytic bacteria were orange glow on the colony when exposed to UV light at 350 nm. Based on morphological characterization, 4 isolates were cocci cells, and 7 isolates were bacilli cells. In addition, 8 gram-negative isolates and 3 gram-positive isolates were identified. The identified isolates were Staphylococcus saprophyticus strain L29 98%, Stenotrophomonas maltophilia 99%, Acinetobacter junii F-27 100%, Paenibacillus lactis PF4J 1-2 96%, Aeromonas dhakensis WWi303 99%, S. saprophyticus P0081Karwar 99%, Aeromonas caviae strain R25 - 6 98%, Acinetobacter pittii strain BJ6 99%.