Isolation of Candida maltosa strains able to achieve a high lipid productivity from malt bagasse hemicellulosic hydrolysate

The rising demand for renewable and sustainable oleochemicals underscores the necessity of producing yeast oil from lignocellulosic hydrolysates. We isolated two oleaginous yeast strains of Candida maltosa (UFV-1 and UFV-2) able to assimilate xylose and tolerate hemicellulosic hydrolysate inhibitors (acetic acid, furfural, hydroxymethylfurfural and formic acid). To optimize growth and lipid production by C. maltosa in malt bagasse hemicellulosic hydrolysate, we applied a central composite rotational design with response surface methodology, evaluating initial pH and yeast extract:peptone ratio (P:YE). The maximum lipid responses were recorded in: (P:YE = 1.0:0.0 g/L, pH = 6.0) for UFV-1 and (P:YE = 0.58:0.42 g/L, pH = 6.5) for UFV-2. Biomass and lipid production were higher in the detoxified hydrolysate than in the non-detoxified hydrolysate. Biomass titers increased from 9.12 to 17.0 g/L and from 10.5 to 12.9 g/L for UFV-1 and UFV-2, respectively; whilst the lipid titers increased from 0.84 to 3.14 g/L and 0.91 to 1.58 g/L for UFV-1 and UFV-2, respectively. Importantly, the levels of 16:0, 18:0, 10:0 fatty acids increased in the detoxified medium. Cultivation of the UFV-1 strain from detoxified hydrolysate in a benchtop bioreactor improved biomass formation, achieving a lipid productivity of 0.29 ± 0.02 g/L h, highlighting its potential to produce oil from hemicellulosic hydrolysates in biorefineries.