Biological Carbon Recovery from Sugar Refinery Washing Water into Microalgal DHA: Medium Optimization and Stress Induction

• Published in: Scientific reports 2019-12, Vol.9 (1), p.19959-11, Article 19959
• Main Authors: Moon, Myounghoon, Park, Won-Kun, Suh, William I., Chang, Yong Keun, Lee, Bongsoo
• Format: Article
• Language: English
• Subjects: 14/63; 631/326/2522; 631/61/168; 82/16; Algae; Aquatic microorganisms; Biomass; Carbon; Carbon - metabolism; Carbon sources; Contaminants; Cultivation; Culture Media - chemistry; Docosahexaenoic acid; Docosahexaenoic Acids - biosynthesis; Docosahexaenoic Acids - metabolism; Heterotrophic Processes; Humanities and Social Sciences; Lipids; Microalgae; Microalgae - metabolism; multidisciplinary; Nitrogen - metabolism; Nutrient concentrations; Organic carbon; Osmotic stress; Phosphorus; Potassium phosphate; Science; Science (multidisciplinary); Stationary phase; Stramenopiles - growth & development; Stramenopiles - metabolism; Sugar; Sugars - metabolism; Total organic carbon; Wastewater; Wastewater - microbiology; Yeasts
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-56406-x

Sugar refinery washing water (SRWW) contains abundant levels of carbon sources and lower levels of contaminants than other types of wastewater, which makes it ideal for heterotrophic cultivation of microalgae. Here, carbon sources in SRWW were utilized for conversion into the form of value-added docosahexaenoic acid (DHA) using Aurantiochytrium sp. KRS101. Since SRWW is not a defined medium, serial optimizations were performed to maximize the biomass, lipid, and DHA yields by adjusting the nutrient (carbon, nitrogen, and phosphorus) concentrations as well as the application of salt stress. Optimum growth performance was achieved with 30% dilution of SRWW containing a total organic carbon of 95,488 mg L −1 . Increasing the nutrient level in the medium by supplementation of 9 g L −1 KH 2 PO 4 and 20 g L −1 yeast extract further improved the biomass yield by an additional 14%, albeit at the expense of a decrease in the lipid content. Maximum biomass, lipid, and DHA yields (22.9, 6.33, and 2.03 g L −1 , respectively) were achieved when 35 g L −1 sea salt was applied on a stationary phase for osmotic stress. These results demonstrate the potential of carbon-rich sugar refinery washing water for DHA production using Aurantiochytrium sp. KRS101 and proper cultivation strategy.