Sustainable bioconversion of glycerine pitch into the novel Wickerhamomyces anomalus bio-preservative

Abstract

Yeasts with high protein content are used as single-cell proteins due to their nutritional values and rare pathogenicity. However, the nucleic acid of the yeasts must be removed before consumption to avoid hazards to health. Wickerhamomyces anomalus is an authorized bio-preservative with promising antifungal activity and safety. However, its high protein content associated with high nucleic acid content results in high nitrogen content that imposes additional downstream processing costs due to the nucleic acid removal step required to prevent uric acid precipitation which leads to various health concerns. The objectives were to (i) isolate a novel Wickerhamomyces anomalus strain with low nitrogen content and (ii) to optimize the production of W. anomalus biomass through response surface methodology (RSM). The novel Wickerhamomyces sp. USMAST-TP1 with low nitrogen content was isolated from fermented food and its biomass was optimized through RSM. Wickerhamomyces sp. USMAST-TP1 showed promising tolerance to glycerine pitch with a higher composition of growth-inhibiting impurities where its biomass was not negatively affected by excessive glycerine pitch supply. Upon optimization through RSM, 11.4 g/L biomass harboring protein content of 13% was achieved. The >17-fold lower nitrogen content of 2% indicated low nucleic acid content compared to common W. anomalus strains, thus the costly nucleic acid purification steps can be excluded, easing applications in agro-food industries.