Biotechnology Bulletin ›› 2025, Vol. 41 ›› Issue (10): 110-120.doi: 10.13560/j.cnki.biotech.bull.1985.2025-0776

Previous Articles     Next Articles

Effect of Photorespiration on Astaxanthin Accumulation in Haematococcus pluvialis Induced by Carbon Sources

ZHANG Chun-hui1(), JI Jing-fang1, CAO Jia-min1, MA Xi-xi1, LIU Wen-zhong1, JI Chun-li1, ZHANG Li-tao2(), LI Run-zhi1()   

  1. 1.College of Agriculture, Shanxi Agricultural University, Shanxi Engineering Research Center for Genetics and Metabolism of Special Crops, Taigu 030801
    2.Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071
  • Received:2025-07-20 Online:2025-10-26 Published:2025-10-28
  • Contact: ZHANG Li-tao, LI Run-zhi E-mail:chunhuizhang90@163.com;zhanglitao666@163.com;rli2001@126.com

Abstract:

Objective Haematococcus pluvialis is the most promising natural source of the potent antioxidant astaxanthin. Carbon source supplementation is an effective strategy to enhance astaxanthin yield. Investigating the effect of endogenous photorespiration on astaxanthin accumulation induced by carbon sources would provide novel insights for optimizing production of H. pluvialis. Method Three different culture media were designed: Group CK: Normal control group, basic BG-11 medium. Group A: Supplemented with sodium acetate. Group H: Supplemented with sodium bicarbonate. The effects of photorespiration pathway on carbon source induced accumulation of astaxanthin in H. pluvialis were investigated by analyzing pigment accumulation, biomass, total photosynthetic rate, OJIP fluorescence induction curve, and chlorophyll fluorescence parameters, in the absence or presence of CM (photorespiration inhibitor) during the incubation, respectively. Result Supplementing with carbon sources such as sodium acetate or sodium bicarbonate enhanced algal dry weight and astaxanthin/chlorophyll ratio, with sodium acetate significantly increased astaxanthin accumulation. However, CM-mediated photorespiration inhibition markedly reduced the dry weight, astaxanthin content, and astaxanthin/chlorophyll ratio. Moreover, carbon supplementation (Group A and H) reduced total photosynthetic rate, further exacerbated by photorespiration inhibition induced by CM. Both carbon sources supplementation and CM altered OJIP curve profiles and fluorescence intensity. Under CK/A conditions, photorespiration inhibition unaffected maximum photochemical efficiency (ΦP0) or electron transport efficiency (ΦE0), but significantly decreased the amount of active PSII reaction centers (RC/CS0), specific energy fluxes for absorption (ABS/RC), trapping flux of excitation energy (TR0/RC), and electron transport flux (ET0/RC) of per active reaction center. Compared with group A, Group A+CM presented notably higher relative variable fluorescence at J-step (VJ). Conclusion Under high-light stress, the addition of sodium acetate followed by inhibition of photorespiration first reduced the number of PSII active reaction centers, which then damaged the PSII receptor side, leading to obstruction of photosynthetic light energy absorption and utilization, and further damaging algal cells of H. pluvialis, resulting in reduced dry weight, astaxanthin content, and astaxanthin/chlorophyll ratio. This confirms that photorespiration plays an important role in the accumulation of astaxanthin in H. pluvialis induced by organic carbon source sodium acetate.

Key words: Haematococcus pluvialis, astaxanthin, photorespiration, sodium acetate, chlorophyll fluorescence