CHARACTERIZATION OF LOCAL THRAUSTOCHYTRID ISOLATE AND OPTIMIZATION OF LIPID PRODUCTION WITH SUCROSE CARBON SOURCE

• Main Author: Nurul Silmi, Fazanaila
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86942
• Institution: Institut Teknologi Bandung

PUFAs (polyunsaturated fatty acids) such as DHA (docosahexaenoic acid) are known to have various health benefits. Thraustochytrids are marine protists that have the potential to be a source of PUFA. Lipid production by Thraustochytrid can reach up to 30-50% (w/w) with half of it proportionally being PUFA. Five Thraustochytrid isolates (K1, K2, K3, D3, and U2) had been successfully isolated from various mangrove forest regions in Indonesia. The objectives of this study were: (1) To identify Thraustochytrid isolates through molecular identification and (2) To determine the effect of initial sucrose concentrations in the medium on growth patterns, biomass productivity, and lipid productivity of Thraustochytrid isolates. The method of identification was carried out by phylogenetic analysis of the Cytochrome Oxidase I (COI) gene. The growth pattern of Thraustochytrid isolates were determined by creating growth curves of the isolates (including the collection of data from cell concentration, pH, and dried biomass of the isolates). Lipid content in the dried biomass of isolates was extracted using the Bligh & Dyer method. The results of phylogenetic analyses showed the closest kinship of the five isolates with Aurantiochytrium sp.. Isolate K2 was selected based on cell viability and morphological stability. The growth curve was made by cultivating the isolate in a medium (sucrose, yeast extract, monosodium glutamate) with 3% salinity. The growth pattern of the three sucrose variations (35 g/L, 60 g/L, and 125 g/L) showed an exponential growth phase from hour 0 to 12, followed by a stationary phase from hour 12 to 120 (the end of the incubation period). The highest biomass productivity was found at the highest sucrose concentration variation S_125 (125 g/L) at 1.53 ± 0.31 g/L dry biomass. The highest lipid productivity was found at the lowest sucrose concentration variation S_35 (35 g/L) of 0.25 ± 0.02 g/L. No statistically significant differences were found in biomass productivity and lipid productivity between initial sucrose concentration variations (p-value >0.05). Significant differences were found in the resulting lipid fractions. The highest fraction was obtained from the lowest sucrose concentration variation S_35 (35 g/L) of 19.74% ± 0.77% lipid (p-value <0.05). This may be due to limitations of the isolate in utilizing sucrose as a carbon source and/or may also be caused by the inhibition of lipid biosynthesis at high sucrose concentrations. Based on the results of the study, it can be concluded that isolate K2 has the closest kinship to Aurantiochytrium sp.. The initial sucrose concentration of 35-125 g/L did not have a significant effect on biomass productivity and lipid productivity of the K2 isolate, but had a significant effect on lipid fractions.