Mechanisms of promotion in the heterotrophic growth of Chlorella vulgaris by the combination of sodium acetate and hydrolysate of broken rice

Yihui Cai; Ligong Zhai; Kangping Wu; Zihan Li; Zhiqiang Gu; Yunpu Wang; Xian Cui; Ting Zhou; Roger Ruan; Tongying Liu; Yuhuan Liu; Qi Zhang

doi:10.1016/j.biortech.2022.127965

Mechanisms of promotion in the heterotrophic growth of Chlorella vulgaris by the combination of sodium acetate and hydrolysate of broken rice

Bioresour Technol. 2022 Nov:364:127965. doi: 10.1016/j.biortech.2022.127965. Epub 2022 Sep 14.

Authors

Yihui Cai¹, Ligong Zhai¹, Kangping Wu², Zihan Li², Zhiqiang Gu², Yunpu Wang², Xian Cui², Ting Zhou³, Roger Ruan⁴, Tongying Liu⁵, Yuhuan Liu⁶, Qi Zhang²

Affiliations

¹ State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China; College of Food Engineering, Anhui Science and Technology University, Fengyang, Anhui 233100, China.
² State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China.
³ Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia.
⁴ Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Ave., St. Paul, MN 55108, USA.
⁵ Jiangxi Maternal and Child Health Hospital, Nanchang, Jiangxi 330006, China.
⁶ State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China. Electronic address: liuyuhuan@ncu.edu.cn.

PMID: 36113821
DOI: 10.1016/j.biortech.2022.127965

Abstract

In order to reduce the culture cost and increase the growth rate of heterotrophic Chlorella vulgaris, the effects of hydrolysate of broken rice (HBR) combined with sodium acetate on its growth were evaluated. Results showed that the addition of 0.4 g/L of sodium acetate could stabilize the pH of the medium via the co-metabolism of acetate, ammonia and nitrate by Chlorella vulgaris. Meanwhile, isocitrate lyase activity increased threefold, which further promoted the glyoxylate cycle and the citric acid cycle, which finally provided more energy and metabolic precursors for cell growth. The biomass production (5.04 g/L), biomass productivity (1.65 g/L/day) and protein content (64.14 %) were 1.56, 1.81 and 1.77 times higher than the glucose group. This study demonstrated that HBR combined with sodium acetate could effectively promote the heterotrophic metabolism of microalgae, which provided scientific basis and guidance for industrial production of high-value products using Chlorella vulgaris as a fermentation platform.

Keywords: Broken rice; Carbon metabolism; Glyoxylate cycle; Microalgal biotransformation; Protein.