Yang Leyun, Zheng Cheng, Chen Yong, Shi Xinchi, Ying Zhuojun, Ying Hanjie
1National Engineering Research Center for Biotechnology, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China.
2State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China.
Biotechnol Biofuels. 2019 Feb 14;12:30. doi: 10.1186/s13068-019-1359-1. eCollection 2019.
Biofilms with immobilized cells encased in extracellular polymeric substance are beneficial for industrial fermentation. Their formation is regulated by various factors, including nitric oxide (NO), which is recognized as a quorum-sensing and signal molecule. The mechanisms by which NO regulates bacterial biofilms have been studied extensively and deeply, but were rarely studied in fungi. In this study, we observed the effects of low concentrations of NO on biofilm formation in Transcriptional and proteomic analyses were applied to study the mechanism of this regulation.
Adding low concentrations of NO donors (SNP and NOC-18) enhanced biofilm formation of in immobilized carriers and plastics. Transcriptional and proteomic analyses revealed that expression levels of genes regulated by the transcription factor Mac1p was upregulated in biofilm cells under NO treatment. promoted yeast biofilm formation which was independent of flocculation gene . Increased copper and iron contents, both of which were controlled by Mac1p in the NO-treated and -overexpressing cells, were not responsible for the increased biofilm formation. , one out of six genes regulated by , plays an important role in biofilm formation. Moreover, and contributed to the cells' resistance to ethanol by enhanced biofilm formation.
These findings suggest that a mechanism for NO-mediated biofilm formation, which involves the regulation of expression levels by activating its transcription factor Mac1p, leads to enhanced biofilm formation. The role of protein in yeast biofilm formation may be due to the hydrophobic residues in its N-terminal extracellular domain, and further research is needed. This work offers a possible explanation for yeast biofilm formation regulated by NO and provides approaches controlling biofilm formation in industrial immobilized fermentation by manipulating expression of genes involved in biofilm formation.
被包裹在胞外聚合物中的固定化细胞形成的生物膜有利于工业发酵。其形成受多种因素调控，包括一氧化氮（NO），它被认为是一种群体感应和信号分子。NO调节细菌生物膜的机制已得到广泛深入研究，但在真菌中却鲜有研究。在本研究中，我们观察了低浓度NO对酿酒酵母生物膜形成的影响，并应用转录组和蛋白质组分析来研究这种调控机制。
添加低浓度的NO供体（SNP和NOC - 18）可增强酿酒酵母在固定化载体和塑料制品上的生物膜形成。转录组和蛋白质组分析表明，在NO处理下，转录因子Mac1p调控的基因在生物膜细胞中的表达水平上调。促进了酵母生物膜形成，且该过程与絮凝基因无关。在NO处理和过表达的细胞中，由Mac1p控制的铜和铁含量增加，但这并非生物膜形成增加的原因。在Mac1p调控的六个基因中，有一个在生物膜形成中起重要作用。此外，和通过增强生物膜形成促进细胞对乙醇的抗性。
这些发现表明，一种由NO介导的生物膜形成机制，即通过激活其转录因子Mac1p来调节的表达水平，导致生物膜形成增强。蛋白质在酵母生物膜形成中的作用可能归因于其N端胞外结构域中的疏水残基，这需要进一步研究。这项工作为NO调控酵母生物膜形成提供了一种可能的解释，并通过操纵参与生物膜形成的基因表达，为控制工业固定化发酵中的生物膜形成提供了方法途径。
