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Author: search.filters.author.Thongtha, Sitthichai

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    Light-Emitting Diode Illumination Enhances Biomass, Pigment, and Lipid Production in Halotolerant Cyanobacterium Aphanothece halophytica
    (2025-06-01)
    Thongtha, Sitthichai
    ;
    Kittiwongwattana, Chokchai
    ;
    Incharoensakdi, Aran
    ;
    Phunpruch, Saranya
    Light characteristics, including spectrum and intensity, significantly impact cyanobacterial biomass production, pigment biosynthesis, and cellular metabolism, influencing the composition of various biochemical compounds. This study aimed to investigate the effects of light-emitting diode (LED) illumination on biomass, pigment, and lipid production in the unicellular halotolerant cyanobacterium Aphanothece halophytica, cultivated in a suitable natural seawater (SNSW) medium. The results revealed that LED light outperformed fluorescent light, with blue LED light, particularly at an intensity of 60 μmol photons m<sup>−2</sup> s<sup>−1</sup>, significantly enhancing growth, pigment synthesis, and lipid accumulation. This resulted in a maximum cell density of 68.96 ± 1.52 × 10<sup>6</sup> cells mL<sup>−1</sup>, a specific growth rate of 0.302 ± 0.002 day<sup>−1</sup>, and a lipid productivity of 56.81 ± 0.75 mg L<sup>−1</sup> day<sup>−1</sup>. White LED light produced lipids suitable for biodiesel, whereas blue, green, and red LEDs promoted the accumulation of polyunsaturated fatty acids (PUFAs), beneficial for food supplements. These findings highlight the potential of LED-based cultivation strategies for optimizing biomass and biochemical compound production in A. halophytica.
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    Modified natural seawater as growth medium for the halotolerant cyanobacterium Aphanothece halophytica to increase lipid content for biodiesel production
    (2025-02-01)
    Thongtha, Sitthichai
    ;
    Aryusuk, Kornkanok
    ;
    Kittiwongwattana, Chokchai
    ;
    Incharoensakdi, Aran
    ;
    Phunpruch, Saranya
    Biodiesel derived from cyanobacterial oils becomes attractive as an efficient renewable energy. The present study aims to optimize growth and lipid production of the halotolerant unicellular cyanobacterium Aphanothece halophytica cultivated in natural seawater. In this study A. halophytica was able to grow in natural seawater when supplemented with low concentration of NaNO<inf>3</inf>, whereas no growth occurred without supplementation. The specific growth rate of 0.230 day<sup>-1</sup> and cell concentration of 25.17 x 10<sup>6</sup> cells mL<sup>-1</sup> were achieved in A. halophytica cultivated in natural seawater supplemented with 17.6 mM NaNO<inf>3</inf> and Turk Island salt solution (suitable natural seawater; SNSW) for 14 days. This growth rate was comparable to that of cells grown in normal BG11 plus Turk Island salt solution. The lipid content and fatty acid profiles of A. halophytica varied with changes in NaCl concentrations. The highest lipid content of 50.47 % and lipid productivity of 48.33 mg L<sup>-1</sup> day<sup>-1</sup> were obtained in cultures supplemented with 1.89 mmol C-atom L<sup>-1</sup> glucose and 0.75 M NaCl. The optimal medium pH and cultivation temperature for lipid production was 7.5 and 25-35 <sup>°</sup>C, respectively. When cultivating A. halophytica in optimized SNSW with various NaCl concentrations, the highest contents of linoleic and linolenic acids, and the lowest contents of palmitic, stearic, and oleic acids were observed with 0.75 M NaCl. In contrast, cultures grown in optimized SNSW with 0.5 M NaCl showed fatty acid methyl ester profiles rich in monounsaturated fatty acids, which are favorable for high-quality biodiesel production.
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