Single-cell oil production by Rhodotorula mucilaginosa CCT 7688 employing soybean hull hydrolysate as a carbon and nutrient source

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发表日期：

2025年5月28日

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Keslei Rosendo da Rocha,
Belkis Chalup Silveira Roesler,
Carlos André Veiga Burkert

摘要

Soybean hull hydrolysate (SBHH), used without any detoxification process, was evaluated as a potential substrate for lipid production by R. mucilaginosa CCT 7688. Preliminary cultures with SBHH yielded the following results for biomass, lipid content, and total lipid production: 9.11 g ∙ L⁻¹, 5.30%, and 0.48 g ∙ L⁻¹, respectively. To maximize total lipid production, a central composite design was employed to assess the C/N ratio, the concentration of MgSO₄ ∙ 7 H₂O, and the initial pH. This optimization led to a 63.9% increase in total lipid production, rising from 0.48 g ∙ L⁻¹ to 1.33 g ∙ L⁻¹. The C/N ratio was determined to be the only significant factor affecting lipid accumulation. Several fed-batch strategies were proposed to further optimize lipid production. The strategy labeled FB4, which involved using SBHH at a concentration of 20 g ∙ L⁻¹ and adding glucose (10 g ∙ L⁻¹) after 72 h, achieved the best outcomes: 11.92 ± 0.02 g ∙ L⁻¹ of biomass, 29.28 ± 0.13% lipid content, and 3.49 ± 0.01 g ∙ L⁻¹ of total lipids after 144 h of cultivation. This represented improvements of 62% and 86.24% compared to the maximized and preliminary cultures, respectively. The lipids produced using the FB4 strategy were characterized using ¹H NMR and GC/MS techniques, revealing a composition of oleic acid (66.92%) and palmitic acid (24.62%), along with several smaller fractions. These results highlight the potential of utilizing soybean hull hydrolysate as a source of carbon and nutrients for lipid biosynthesis by R. mucilaginosa CCT 7688.