解淀粉芽孢杆菌生物膜异质性表型转化的环境驱动与sRNA调控

Genetically identical bacteria can change into different daughter cells, according to the extracellular environment, which presented as biofilm phenotype switching in the Bacillus. Bacillus amyloliquefaciens is an excellent agent for biological control with typical biofilm. We found that, in response to environmental factors, the bacteria showed phenotype heterogeneity in the bacteria biofilm, accompany with the change of antibacterial activity; implying that the directive control of biofilm phenotype can regulate the antibacterial activity. However, the mechanism of bacterial biofilm phenotype switching is not clear. In the study, we determined the bacterial biofilm phenotype switching characteristic under selection environmental stress, analyses the drive affection of environment signals on the biofilm phenotype switching. Using of gene mutation construction, RNA-seq, qRT-PCR, and Northern blot analysis, we try to determine the small noncoding small RNAs involved in biofilm phenotype switching and its regulation mechanism, as well as the coordinated regulation of environmental signs and sRNA. The study could provide new strategies for directional control of antibacterial activity in B. amyloliquefaciens.

遗传因子完全相同的细菌能够根据环境变化分化为功能不同的子代细胞，在芽孢杆菌中表现为生物膜异质性表型转化。解淀粉芽孢杆菌是具有典型生物膜特征的优秀生防细菌，前期研究发现，该菌存在异质性变异的生物膜表型转化特征，并伴随抗菌活性的改变；提示着定向调控生物膜表型转化，从而调控抗菌活性的可能。然而，其生物膜异质性表型转化机制尚不清楚。本研究将设置环境压力体系，分析环境信号对解淀粉芽孢杆菌生物膜表型转化的诱导和驱动及其特异性；采用RNA-seq组学分析、突变株构建、qRT-PCR测定、Northern杂交等，分析细菌关键sRNA对环境信号的识别与传递、对生物膜表型转化的转录后调控和全局性作用机制；进而解析环境驱动、sRNA调控对生物膜表型转化的协同作用机制和生物膜表型定向转化作用，以及对抗菌活性的on/off调控特征。为通过“环境驱动、基因修饰”实现解淀粉芽孢杆菌抗菌活性的定向调控提供新的策略与路径。

解淀粉芽孢杆菌是重要的生防细菌，其生防机制的研究是永恒的主题和重要的研究内容。本研究围绕生物膜异质性表型转化，探讨不同环境要素下解淀粉芽孢杆菌PEBA20生物膜表型转化的表型特征，揭示解淀粉芽孢杆菌对环境胁迫的响应和适应机制，聚焦细菌非编码sRNA，揭示其对环境信号的识别和传递、对生物膜表型转化的转录后调控和全局性作用机制。通过设置营养胁迫和盐胁迫的环境要素，揭示了营养胁迫环境和盐胁迫环境信号对生物膜异质性表型转化的诱导和驱动及其特异性关联；创造性发现了解淀粉芽孢杆菌对氮饥饿适应的“记忆特征”和“氮资源节约”的适应机制，发现解淀粉芽孢杆菌存在对盐胁迫响应与适应的“高成本维持渗透压策略”；分析了解淀粉芽孢杆菌sRNAs基因组特征，关键基因和sRNA对环境信号的识别与传递，对生物膜异质性表型转化的转录后水平调控和全局性作用机制；揭示了运动性、抗菌活性及其相关基因在解淀粉芽孢杆菌环境适应响应中的特征；阐述了解淀粉芽孢杆菌对营养胁迫和盐胁迫环境信号响应和适应的全局性调控机制和关键生物活动特征。研究结果为通过“环境驱动、基因修饰”实现解淀粉芽孢杆菌抗菌活性的定向调控奠定理论基础。