High cell density culture of Paracoccus sp. LL1 in membrane bioreactor for enhanced co-production of polyhydroxyalkanoates and astaxanthin

• Published in: International journal of biological macromolecules 2021-12, Vol.192, p.289-297
• Main Authors: Khomlaem, Chanin, Aloui, Hajer, Oh, Won-Gyun, Kim, Beom Soo
• Format: Article
• Language: English
• Subjects: Astaxanthin; Batch Cell Culture Techniques - methods; Bioreactors; Fermentation; High cell density culture; Nuclear Magnetic Resonance, Biomolecular; Paracoccus - metabolism; Polyhydroxyalkanoates; Polyhydroxyalkanoates - analysis; Polyhydroxyalkanoates - biosynthesis; Spectroscopy, Fourier Transform Infrared; Thermogravimetry; Xanthophylls - analysis; Xanthophylls - metabolism
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2021.09.180

A cell retention culture of Paracoccus sp. LL1 was performed in a membrane bioreactor equipped with an internal ceramic filter module to reach high cell density and thus enhance the co-production of polyhydroxyalkanoates (PHA) and astaxanthin as growth-associated products. Cell retention culture results showed that PHA accumulation increased with increasing dry cell weight (DCW), giving rise to a maximum of 113 ± 0.92 g/L of DCW with 43.9 ± 0.91 g/L of PHA (38.8% of DCW) at 48 h. A significant increase in both intracellular and extracellular astaxanthin concentrations was also recorded during fermentation process achieving a maximum of 8.51 ± 0.20 and 10.2 ± 0.24 mg/L, respectively. Amounts of PHA and total astaxanthin produced by cell retention culture were 6.29 and 19.7-folds higher, respectively, than those recorded under batch cultivation. PHA and total astaxanthin productivities by cell retention culture also increased up to 0.914 g/L/h and 0.781 mg/L/h, respectively, which were 3.54 and 11.1-folds higher than those of batch culture. Based on gas chromatography, Fourier transform infrared spectroscopy, and 1H nuclear magnetic resonance spectroscopy, the extracted PHA was identified as a copolymer of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with a 3-hydroxyvalerate content of 3.78 mol%. [Display omitted] •Cell retention culture of Paracoccus sp. LL1 in membrane bioreactor•Maximum dry cell weight of 113 g/L and PHA productivity of 0.914 g/L/h•Total astaxanthin productivity of 0.781 mg/L/h at 48 h•Enhancement of 6.29 and 19.7-folds in PHA and astaxanthin production•Production of P(3HB-co-3HV) copolymer from glucose as carbon source