PANGGABEAN, LILY MARIA GORETTI

• HAYATI Journal of Biosciences Vol. 16 No. 4 (2009): December 2009 - Articles
  

  Since the primary storage nutrients in diatoms consist of lipid, they are potential for the industrial fatty acid production. High value fatty acids include arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid. This study aimed to analyze fatty acid synthesis by Chaetoceros gracilis diatom during growth. There was a large increase in lipid yield from 4pg cell-1 mass of lipid per cell at the exponential phase to 283pg cell-1 at stationary phase. The lipid concentrations also increased significantly from the stationary phase to the death phase, but not significantly from the end exponential phase to the stationary phase. The relative percentage of saturated fatty acid (SAFA) of the total fatty acid was higher than that of monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) at all of growth phase. The highest PUFA was found at stationary phase at the same time when SAFA was being the lowest. The majority of SAFA was palmitic acid (24.03-40.35%). MUFA contained significant proportion of oleic acid (19.6-20.9%). Oleic acid, linoleic acid and α-linolenic acid were found at every stage growth. These fatty acids are considered as precursor for production of long chain PUFA-Docosahexaenoic acid (DHA/22:6ω3) through series of desaturation and elongation step with all of desaturase enzyme (Δ8-D, Δ9-D, Δ12-D, Δ15-D, Δ17-D, Δ6-D, Δ5-D, and Δ4-D) and elongase enzyme (E).

   

        Key words: Chaetoceros gracilis, fatty acid, synthesis, saturated fatty acid (SAFA), monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA)

  
  Abstract  PDF
• HAYATI Journal of Biosciences Vol. 18 No. 4 (2011): December 2011 - Articles
  Coral reef communities contain a wide variety of mutualistic associations none more important than the relationship between corals and their symbiotic dinoflagellates of the genus Symbiodinium sp., commonly referred to as zooxanthellae. The function of Zinc (Zn) as cofactor of several enzyme systems such as extracellular carbonic anhydrase (extracellular CA) which catalyzes the interconversion of HCO3- and CO2. Concentrations of dissolved Zn in oligothropic waters are often very low therefore may limit the growth of zooxanthellae and their ability to fix CO2 from seawater via the carbonic anhydrase. The aim of this research is to investigate the effect of various concentrations of Zn on the growth and extracellular CA activity in zooxanthellae. Cell density was monitored daily by enumeration with hemocytometer-type chamber (0.1 mm). Extracellular CA was measured in homogenized intact whole cell by a pH drift assay. Results revealed that Zn status strongly influences the growth rate and extracelullar CA activity in zooxanthellae. The specific growth rate and cell density increased two-fold whilst extracelullar CA activity increased 10.5 times higher than that in control with increasing concentrations of Zn from 0 to 80 nM, but decreased when Zn was over 80 nM. Under a concentration of 80 nM was not Zn limited culture, consequently the growth rate of zooxanthellae not dependent on CO2 concentration yet offset by extracelullar CA activity.
  Abstract  PDF