Glutamine Modulates mVOC Biosynthesis in Streptomyces alboflavus Through a gluR-Dependent Signaling Pathway and
Wangqiang Li1,2, Mingguan Yang1,3, Zehua Dong1
1State Key Laboratory of Food Nutrition and Safety, School of Food Science and Engineering, Tianjin University of Science & Technology, Tianjin 300457, China.
Abstract:
Aspergillus flavus and its aflatoxins pose serious threats to human and animal health, negatively affecting agricultural productivity and the global economy. Although chemical preservatives are widely used, their effectiveness remains limited by increased fungal resistance and environmental concerns, highlighting the need for sustainable alternatives. Microbial volatile organic compounds (mVOCs) represent a promising biocontrol strategy. Here, we investigate how glutamine regulates mVOC biosynthesis in Streptomyces alboflavus TD-1 and enhances its antifungal activity against A. flavus. Antifungal assays showed that supplementation with 40 mM glutamine significantly enhanced inhibitory activity, leading to 69.0% inhibition of conidial germination and 64.5% inhibition of mycelial biomass. Transcriptome profiling identified 283 differentially expressed genes, including the two-component system regulator gluR, which was strongly upregulated. CRISPR/Cas9-mediated disruption of gluR confirmed its regulatory role. Specifically, the mutant strain produced reduced levels of antifungal mVOCs, such as dimethyl trisulfide and o-anisidine, and exhibited diminished inhibition of A. flavus. Collectively, these findings demonstrate that exogenous glutamine enhances the mVOC-mediated suppression of A. flavus by S. alboflavus TD-1 through nutrient-sensing and transcriptional regulation of volatile biosynthesis. Although aflatoxin levels were not quantified in this study, the enhanced growth inhibition and the identified mVOC shifts provide a mechanistic basis for future studies that directly quantify aflatoxin production under storage-relevant conditions.
Insights
Glutamine supplementation boosts the antifungal power of Streptomyces alboflavus TD-1 by increasing microbial volatile organic compounds (mVOCs). This enhances the inhibition of Aspergillus flavus growth, offering a sustainable biocontrol alternative.
Area of Science:
- Microbiology
- Biotechnology
- Agricultural Science
Background:
- Aspergillus flavus and its aflatoxins present significant risks to human and animal health, impacting agriculture and the global economy.
- Chemical preservatives face limitations due to increasing fungal resistance and environmental concerns, necessitating sustainable alternatives.
- Microbial volatile organic compounds (mVOCs) offer a promising biocontrol strategy against fungal pathogens.
Purpose of the Study:
- To investigate the role of glutamine in regulating mVOC biosynthesis in Streptomyces alboflavus TD-1.
- To determine how glutamine enhances the antifungal activity of S. alboflavus TD-1 against Aspergillus flavus.
- To elucidate the molecular mechanisms underlying glutamine-mediated enhancement of antifungal activity.
Main Methods:
- Antifungal assays were performed to evaluate the inhibitory effects of S. alboflavus TD-1 supplemented with glutamine.
- Transcriptome profiling was employed to identify differentially expressed genes in response to glutamine.
- CRISPR/Cas9 gene editing was used to disrupt the identified regulator gene, gluR, to confirm its function.
Main Results:
- Supplementation with 40 mM glutamine significantly enhanced the antifungal activity of S. alboflavus TD-1, inhibiting conidial germination by 69.0% and mycelial biomass by 64.5%.
- Transcriptome analysis revealed 283 differentially expressed genes, including the two-component system regulator gluR, which was significantly upregulated by glutamine.
- Disruption of gluR resulted in reduced production of antifungal mVOCs and diminished inhibition of A. flavus, confirming its regulatory role in volatile biosynthesis.
Conclusions:
- Exogenous glutamine enhances the mVOC-mediated suppression of Aspergillus flavus by Streptomyces alboflavus TD-1.
- This enhancement is mediated through nutrient-sensing pathways and transcriptional regulation of volatile biosynthesis.
- The findings provide a mechanistic basis for utilizing glutamine as a strategy to improve biocontrol efficacy against A. flavus.
Related Concept Videos
02:26NF-κB-dependent Signaling Pathway
NF-κB-dependent Signaling Mechanism
The...
01:19Contact-dependent Signaling
Gap Junctions
In animal cells, gap junctions are formed...
03:14Notch Signaling Pathway
The Notch gene came into the limelight in 1914 after the discovery that its mutation in Drosophila melanogaster leads to a serrated (or "notched") wing margin phenotype. It was not...
02:33Hedgehog Signaling Pathway
01:19Interactions Between Signaling Pathways
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
01:16Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...