Nitrogen Ion Beam Mutagenesis Boosts Sophorolipid Output in Starmerella bombicola

Researchers have used nitrogen ion beam mutagenesis to improve sophorolipid production in the yeast Starmerella bombicola, yielding a mutant that produced 224.31 grams per liter of total sophorolipids in a 100-liter bioreactor. The study, published as open access research in Applied Microbiology and Biotechnology, addressed a practical bottleneck: sophorolipids are microbial biosurfactants with broad industrial potential, but large-scale application depends on robust high-producing strains with desirable functional properties.

The team subjected Starmerella bombicola CGMCC 1576 to nitrogen ion beam mutagenesis and constructed a mutant library of 124 isolates. High-throughput screening followed by shake-flask validation identified two stable high-producing mutants, designated 2–21 and 3–5. The two mutants differed in product distribution: mutant 2–21 preferentially accumulated acidic sophorolipids and showed the highest total sophorolipid production, while mutant 3–5 produced more lactonic sophorolipids.

HPLC profiling showed that both mutants retained the major sophorolipid components of the parental strain but differed markedly in component abundance and product distribution. Transcriptional analysis revealed upregulation of genes associated with fatty acid utilization, sophorolipid biosynthesis and metabolite transport, particularly in mutant 2–21 at 96 hours, suggesting enhanced precursor conversion and product accumulation.

Functional assays showed composition-dependent differences in surface activity and mildness. Lactonic sophorolipid-rich fractions exhibited stronger surface activity, while acidic sophorolipid-rich fractions showed lower zein solubilization and lower hemolytic activity. These results indicate that mutagenesis can tailor sophorolipid composition for different functional applications, not simply raise total output.

The authors conclude that nitrogen ion beam mutagenesis is an effective strategy for developing high-producing S. bombicola strains and for tailoring sophorolipid composition. The 100-liter fermentation result for mutant 2–21 supports scalability and production robustness, though the findings derive from this engineered yeast system and the reported shake-flask, analytical and bioreactor experiments.

Subject of Research: Nitrogen ion beam mutagenesis of Starmerella bombicola to improve sophorolipid production and composition

Article Title: Nitrogen ion beam mutagenesis improves sophorolipid production and properties in Starmerella bombicola

Article References: Wei, Q., Ren, Y., Jiang, Y., Wang, H., Wang, H., Liu, J., & Ma, X. (2026). Nitrogen ion beam mutagenesis improves sophorolipid production and properties in Starmerella bombicola. Applied Microbiology and Biotechnology. https://doi.org/10.1007/s00253-026-14065-9

Image Credits: AI Generated

DOI: 10.1007/s00253-026-14065-9

Keywords: Starmerella bombicola, nitrogen ion beam, mutagenesis, sophorolipids, biosurfactants, acidic sophorolipids, lactonic sophorolipids, bioreactor fermentation, HPLC, transcriptional analysis, strain development, industrial biotechnology