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<p><i>Aedes aegypti</i> shows increasing resistance to chemical larvicides, underscoring the need for scalable biological alternatives. Single-cell oils (SCOs) from oleaginous yeasts, enriched in unsaturated fatty acids, were evaluated as larvicides. Yeasts from soils and decaying fruits were screened for lipid accumulation under nitrogen limitation, identified by molecular methods, optimized in shake flasks across pH, carbon source, and carbon-to-nitrogen (C/N) ratios, and the top strain was scaled in a 7-L bioreactor. SCOs were extracted and characterized by FTIR, GC–MS, and NMR. Larvicidal activity against third-instar <i>A. aegypti</i> was assessed by mortality, pupation delay, and inhibition of adult emergence, and IC<sup>50</sup>/IC<sup>90</sup> values were estimated by probit analysis. Four oleaginous yeasts were confirmed: <i>Moesziomyces aphidis</i> KHL-99, <i>Rhodosporidium toruloides</i> KHL-101, <i>R. toruloides</i> KHL-103, and <i>Rhodotorula sinensis</i> KHL-108. SCOs from KHL-99 and KHL-108 were most active (IC50 ≈ 75 ppm), and sublethal doses reduced adult emergence by ~35–40%. Optimization showed that nitrogen limitation, pH 5.0–5.5, glycerol as carbon source, and higher C/N ratios increased lipid accumulation. In bioreactor, KHL-99 reached 8.1 ± 0.4 g/L biomass and 4.75 ± 0.2 g/L lipids (41% dry cell weight). SCOs were enriched in oleic (C18:1) and linoleic (C18:2) acids, supporting a biochemical basis for larvicidal effects. These findings indicate that yeast-derived SCOs function as active larvicides and can be produced at scale, positioning them as practical additions to integrated vector management. Because these SCOs consist of naturally occurring fatty acids rather than synthetic neurotoxins, they are expected to pose minimal risk to non-target organisms and offer an environmentally safe alternative for field application.</p> Graphical abstract <p></p>

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Single-Cell oils from oleaginous yeasts: a scalable biotechnological source of novel larvicides against Aedes aegypti

  • 期刊论文

  • 发表日期：

    2025年11月8日

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  • Ahmed M. Elazzazy,
  • Khalid M. Alasmi,
  • Shatha I. Alqurashi,
  • Wafa A. Aljohani,
  • Soha A. Alsolmy,
  • Mohammed N. Baeshen,
  • Jazem A. Mahyoub,
  • Tamer S. Saleh,
  • Mohammed Y. Haroun,
  • Sadat M.R. Khattab,
  • Said E. Desouky

摘要

Aedes aegypti shows increasing resistance to chemical larvicides, underscoring the need for scalable biological alternatives. Single-cell oils (SCOs) from oleaginous yeasts, enriched in unsaturated fatty acids, were evaluated as larvicides. Yeasts from soils and decaying fruits were screened for lipid accumulation under nitrogen limitation, identified by molecular methods, optimized in shake flasks across pH, carbon source, and carbon-to-nitrogen (C/N) ratios, and the top strain was scaled in a 7-L bioreactor. SCOs were extracted and characterized by FTIR, GC–MS, and NMR. Larvicidal activity against third-instar A. aegypti was assessed by mortality, pupation delay, and inhibition of adult emergence, and IC50/IC90 values were estimated by probit analysis. Four oleaginous yeasts were confirmed: Moesziomyces aphidis KHL-99, Rhodosporidium toruloides KHL-101, R. toruloides KHL-103, and Rhodotorula sinensis KHL-108. SCOs from KHL-99 and KHL-108 were most active (IC50 ≈ 75 ppm), and sublethal doses reduced adult emergence by ~35–40%. Optimization showed that nitrogen limitation, pH 5.0–5.5, glycerol as carbon source, and higher C/N ratios increased lipid accumulation. In bioreactor, KHL-99 reached 8.1 ± 0.4 g/L biomass and 4.75 ± 0.2 g/L lipids (41% dry cell weight). SCOs were enriched in oleic (C18:1) and linoleic (C18:2) acids, supporting a biochemical basis for larvicidal effects. These findings indicate that yeast-derived SCOs function as active larvicides and can be produced at scale, positioning them as practical additions to integrated vector management. Because these SCOs consist of naturally occurring fatty acids rather than synthetic neurotoxins, they are expected to pose minimal risk to non-target organisms and offer an environmentally safe alternative for field application.

Graphical abstract