Aug 2026· Bioresource Technology· Vol 462, pp.
135635
· 0 citations· 49 references
Medicine
TL;DR
This work identified LexA as a key regulator governing thermotolerance and glycogen accumulation in the methanotroph Methylotuvimicrobium buryatense 5GB1C and demonstrated for the first time that LexA plays a critical regulatory role in thermotolerance of methanotrophs.
Abstract
Systematic mining of heat stress factors is pivotal for constructing robust microbial cell factories. However, the genetic basis underlying thermotolerance remains poorly understood in C1 gas-utilizing chassis. Here, we identified LexA as a key regulator governing thermotolerance and glycogen accumulation in the methanotroph Methylotuvimicrobium buryatense 5GB1C. Through ultraviolet mutagenesis coupled with adaptive laboratory evolution, we developed a thermotolerant evolved strain 5C27. Whole-genome resequencing and transcriptomic analysis revealed global transcriptional reprogramming underlying the heat tolerance phenotype. Notably, LexA was sharply downregulated at 40 °C and identified as a core regulatory factor for thermoadaptation. Transcriptomic analysis indicated that the acquired thermotolerance arises from coordinated regulation of oxidative stress response, energy metabolism, and cellular homeostasis. Subsequent validation experiments demonstrated that lexA deficiency simultaneously conferred enhanced thermotolerance and redirected intracellular carbon flux, resulting in increased glycogen production that exceeded wild-type levels even at the optimal growth temperature of 30 °C. Collectively, our work demonstrated for the first time that LexA plays a critical regulatory role in thermotolerance of methanotrophs. This discovery also provides a foundation for advancing the development of thermotolerant cell factories and promotes the deployment of C1-gas industrial biomanufacturing.
This work resolves the fundamental oxygen contradiction between thermotolerance enhancement and product biosynthesis in high-temperature fermentation, providing a transformative strategy for cost-effective and sustainable industrial biomanufacturing.
Zhongmei Hu, Yanjie Li, Na Dong et al.· Bioresource Technology· 0 citations
Cobetia marina
is a marine bacterium that sustains growth and biofilm formation across a broad thermal range, serving as an ideal model for exploring adaptability in thermally dynamic and warming oceans. In this study, we investigated how growth temperature reshapes transcriptional regulation and biofilm architecture in
C. marina
strain MM1IDA2H-1, as well as its trajectories under thermal stress.
We integrated transcriptomic profiling with confocal and electron microscopy at different growth temperatures. Additionally, we conducted adaptive laboratory evolution (ALE) under progressive heat stress coupled with whole-genome sequencing.
Transcriptomes from cultures grown at 16 °C, 35 °C, 38 °C, and 41 °C were linked to physiology and biofilm structure, whereas ALE revealed strategies under warming stress. Low temperature promoted a biofilm-competent program driving motility and exopolysaccharide production. Conversely, growth at 41 °C induced a stress-survival state with repression of cooperative traits—quorum sensing—and the activation of DNA repair and oxidative stress responses. Exploratory network analyses predicted NarL, NtrC, CysB, and CsgD as putative components of a temperature-responsive control core, with a reduction in regulatory connectivity at 38 °C, representing a transitional stop-and-reprogram state. Finally, ALE selected for recurrent clone-specific mutations in
csgD1
, resolving a phenotypic trade-off by downregulating costly biofilm production to maintain growth capacity.
Overall, our findings show how
C. marina
transitions across a wide temperature range and under thermal stress via state-dependent network rewiring, offering a comprehensive eco-physiological framework that links environmental sensing, multicellular organization, and evolutionary trade-offs in highly dynamic and warming oceans.
C. Ibacache-Quiroga, O. Schmachtenberg, K. González-Pizarro et al.· Frontiers in Microbiology· 0 citations
More frequent short-term episodes of extreme high temperatures caused by global warming seriously threaten plant growth and development around the world. Although heat stress can occur throughout the plant life cycle, exposure during the seedling stage severely impacts subsequent plant growth and productivity. In this study, we found that the
Arabidopsis
metacaspase mutant
atmc1
exhibited a heat-sensitive phenotype at the seedling stage, and restoration of
AtMC1
expression in the
atmc1
substantially rescued the heat-sensitive phenotype, indicating an important role of AtMC1 in thermotolerance. To investigate the underlying molecular responses associated with AtMC1 under heat stress, RNA sequencing was performed to compare the transcriptomic profiles of wild-type and
atmc1
seedlings under normal and heat treatment conditions. Gene set enrichment analysis (GSEA) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses identified key genes related to
heat acclimation
,
protein folding
, and endoplasmic reticulum-associated degradation (ERAD). Genes involved in reactive oxygen species (ROS) homeostasis also displayed differential expression patterns under heat stress. In addition, 45 transcription factors belonging to the ERF, HSF, WRKY, NAC, and MYB families were differentially expressed between wild-type and
atmc1
in response to heat stress. Protein-protein interaction analysis revealed 27 key heat-responsive genes, most of which were heat-induced but exhibited attenuated upregulation in
atmc1
. Collectively, our findings provide transcriptomic insights into the heat stress responses associated with loss of
AtMC1
in
Arabidopsis
seedlings and provide a foundation for future mechanistic studies of AtMC1-mediated thermotolerance.
Lin Chen, Xiao-Chun Ge· Frontiers in Plant Science· 0 citations
ABSTRACT Thermotolerance is fundamental to fungal ecology and survival. Although heat stress triggers extensive metabolic reprogramming, the function of these changes for thermotolerance has remained poorly understood. Here, we identify glutamine synthetase (GS), a central nitrogen metabolism enzyme, as a critical determinant of thermotolerance in Ganoderma lucidum. Silencing of gs significantly enhanced fungal tolerance under heat stress and reduced the relative inhibition rate of mycelial growth to 9.71%, compared with 20.7% in the wild-type (WT) strain. Heat stress also increased reactive oxygen species and H₂O₂ levels by 1.49- and 1.38-fold in the WT strain, whereas the increments were markedly lower in gs-silenced strains. Subsequently, under heat stress, α-ketoglutarate contents in WT increased by 1.49-fold. Inhibition of GS further increased the accumulation, which was achieved by upregulating glutamate dehydrogenase to promote the conversion of glutamate to α-ketoglutarate. This metabolic response was correlated with the generation of adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide (NADH). Moreover, under heat stress, the level of GS protein in WT strains decreased by 29.0%, compared with that under normal conditions, due to accelerated degradation via the 26S proteasome. Our findings reveal that a ubiquitin-dependent signal instantaneously rebalances central carbon-nitrogen metabolism, offering a direct and rapid link between central metabolism and thermotolerance in fungi. IMPORTANCE Understanding how organisms adapt to heat stress is of increasing urgency in the context of global warming. While the roles of heat-shock proteins and antioxidant systems are well established, how microbes actively reprogram central metabolism to survive thermal challenge remains a fundamental, unanswered question. This study reveals that the central nitrogen metabolism enzyme glutamine synthetase (GS) is degraded by the ubiquitin-proteasome system and that this degradation acts as a metabolic switch to enhance thermotolerance in Ganoderma lucidum. We discovered that heat stress induces ubiquitin-proteasome system-dependent GS degradation, leading to redirected central nitrogen flux that elevates α-ketoglutarate content. This metabolic shift boosts ATP and NADH production. In summary, our findings represent a significant advance beyond classical protein chaperone systems and reactive oxygen species-scavenging systems, highlighting a direct and rapid link between metabolic flux and thermotolerance. Understanding how organisms adapt to heat stress is of increasing urgency in the context of global warming. While the roles of heat-shock proteins and antioxidant systems are well established, how microbes actively reprogram central metabolism to survive thermal challenge remains a fundamental, unanswered question. This study reveals that the central nitrogen metabolism enzyme glutamine synthetase (GS) is degraded by the ubiquitin-proteasome system and that this degradation acts as a metabolic switch to enhance thermotolerance in Ganoderma lucidum. We discovered that heat stress induces ubiquitin-proteasome system-dependent GS degradation, leading to redirected central nitrogen flux that elevates α-ketoglutarate content. This metabolic shift boosts ATP and NADH production. In summary, our findings represent a significant advance beyond classical protein chaperone systems and reactive oxygen species-scavenging systems, highlighting a direct and rapid link between metabolic flux and thermotolerance.
Jinjin Qiao, Huajun Li, Yuzhen Yang et al.· Applied and Environmental Mi...· 0 citations
Systems-level mechanistic insight is provided into microbial selenite tolerance with implications for bioremediation of selenium-contaminated environments and the view that microbial selenium tolerance is controlled by regulated physiological responses and not solely by passive detoxification is supported.
Maryam Anayat, Shiza Nawaz, Zheng-Rong Tao et al.· World Journal of Microbiolog...· 0 citations
Heterologous expression of CsAlaDC establishes a functional ethylamine-theanine metabolic branch in tomato and enhances thermotolerance through coordination with the GABA metabolic network, offering a promising strategy to improve both stress resilience and nutritional quality in crops.
Qianying Wang, Jingbo Yu, Peng Mao et al.· Plant Physiology· 0 citations
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