Discovery of mannose as an alternative non-nutrient-deficient regulator of lipid accumulation in microalgae,Journal of Advanced Research

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Discovery of mannose as an alternative non-nutrient-deficient regulator of lipid accumulation in microalgae
Journal of Advanced Research ( IF 11.4 ) Pub Date : 2025-03-18 , DOI: 10.1016/j.jare.2025.03.019
Pengyang Liu ₁ , Yuanhang Ai ₁ , Muzi Li ₂ , Jiacheng Shi ₁ , Ning Xiao ₃ , Xiaoyu Zhang ₁ , Hongbo Yu ₁ , Fuying Ma ₁ , Su Sun ₄ , Shangxian Xie ₅

Affiliation

Introduction

Microalgae are considered promising bioenergy producers, but their commercial potential is limited by low lipid yields. Nutrient deprivation, particularly nitrogen starvation, is a primary strategy to enhance lipid synthesis efficiency in microalgae. However, controlling this process flexibly, effectively, and accurately remains challenging. Moreover, nutrient deficiency triggers expression changes of numerous genes, complicating the identification of key lipid biosynthesis regulators.

Objectives

For the first time, we investigated mannose as a novel non-nutrient-deficient regulator of lipid accumulation in microalgae and explored its potential underlying mechanisms.

Methods

We examined how mannose induction affects lipid accumulation in Chlorella sorokiniana W1 under various culture conditions and compared its effects with nitrogen-starvation. Transcriptome analysis and genome-scale metabolic modeling were used to elucidate the regulatory mechanisms underlying mannose-induced lipid synthesis. Additionally, potential transcription factors were identified using weighted gene co-expression network analysis.

Results

Mannose drives rapid and sustained lipid accumulation in C. sorokiniana under various cultivation conditions, independent of nutrient deficiencies. Under autotrophic conditions, mannose increased lipid content of microalgae by 80.1 %. Notably, mannose was not consumed during cultivation, supporting its role as an inducer. Transcriptomic analysis revealed that mannose increased carbon flux by upregulating genes associated with the Calvin cycle, glycolysis, the TCA cycle, and starch degradation. It also redirected carbon towards lipid accumulation by upregulating lipid synthesis pathways and downregulating lipid degradation pathways. Additionally, two SBP1 transcription factors specifically responsive to mannose were identified and may regulate carbon metabolism in microalgae.

Conclusion

Our study introduces mannose as a novel non-nutrient-deficiency regulatory factor for lipid accumulation in C. sorokiniana W1, and explores its metabolic and regulatory mechanisms under various nutrient conditions. The research demonstrates that mannose induction has significant potential for improving microalgal lipid production in practical applications.

中文翻译：

发现甘露糖作为微藻中脂质积累的替代非营养缺陷调节因子

介绍

微藻被认为是有前途的生物能源生产者，但其商业潜力受到低脂质产量的限制。营养剥夺，尤其是氮饥饿，是提高微藻脂质合成效率的主要策略。然而，灵活、有效和准确地控制这一过程仍然具有挑战性。此外，营养缺乏会触发许多基因的表达变化，使关键脂质生物合成调节因子的鉴定复杂化。

目标

我们首次研究了甘露糖作为微藻脂质积累的新型非营养缺陷调节因子，并探讨了其潜在的潜在机制。

方法

我们研究了甘露糖诱导如何影响小球藻 W1 中小球藻 W1 的滑脱积累，并将其与氮饥饿的影响进行了比较。转录组分析和基因组规模代谢建模用于阐明甘露糖诱导脂质合成的调节机制。此外，使用加权基因共表达网络分析鉴定潜在的转录因子。

结果

甘露糖在各种培养条件下驱动 C. sorokiniana 中快速和持续的脂质积累，与营养缺乏无关。在自养条件下，甘露糖使微藻的脂质含量增加了 80.1%。值得注意的是，甘露糖在种植过程中没有被消耗，支持其作为诱导剂的作用。转录组学分析显示，甘露糖通过上调与 Calvin 循环、糖酵解、TCA 循环和淀粉降解相关的基因来增加碳通量。它还通过上调脂质合成途径和下调脂质降解途径，将碳重定向到脂质积累。此外，还鉴定了两种对甘露糖有特异性反应的 SBP1 转录因子，它们可能调节微藻中的碳代谢。