Proteomic profiling of Bacillus licheniformis reveals a stress response mechanism in the synthesis of extracellular polymeric flocculants

• Published in: Biotechnology and bioengineering 2016-04, Vol.113 (4), p.797-806
• Main Authors: Yu, Wencheng, Chen, Zhen, Shen, Liang, Wang, Yuanpeng, Li, Qingbiao, Yan, Shan, Zhong, Chuan-Jian, He, Ning
• Format: Article
• Language: English
• Subjects: Amino acid starvation; Amino acids; Amino Acids - analysis; amino acids starvation; B. licheniformis; Bacillus - chemistry; Bacillus - metabolism; Bacillus - physiology; Bacillus licheniformis; Bacteria; Bacterial Proteins - analysis; Biodegradation; Bioengineering; Biosynthesis; Cell culture; Cellular biology; Chemical synthesis; Culture; Cytosol - chemistry; Degradation; EPS; extracellular polymeric substance; Flocculants; Gene Expression Profiling; Genes; Glutamic acid; Macromolecules; Polyglutamic Acid - analogs & derivatives; Polyglutamic Acid - metabolism; Polymers; Polysaccharides; Polysaccharides, Bacterial - metabolism; Proteins; Proteome - analysis; Proteomics; Real-Time Polymerase Chain Reaction; Saccharides; Stress; Stress response; Stress, Physiological; Stresses; SWATH acquisition; Transcription
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.25838

ABSTRACT Some bioflocculants composed of extracellular polymeric substances are produced under peculiar conditions. Bacillus licheniformis CGMCC2876 is a microorganism that secretes both extracellular polysaccharides (EPS) and poly‐gamma‐glutamic acid (γ‐PGA) under stress conditions. In this work, SWATH acquisition LC‐MS/MS method was adopted for differential proteomic analysis of B. licheniformis, aiming at determining the bacterial stress mechanism. Compared with LB culture, 190 differentially expressed proteins were identified in B. licheniformis CGMCC2876 cultivated in EPS culture, including 117 up‐regulated and 73 down‐regulated proteins. In γ‐PGA culture, 151 differentially expressed proteins, 89 up‐regulated and 62 down‐regulated, were found in the cells. Up‐regulated proteins involved in amino acid biosynthesis were found to account for 43% and 41% of the proteomes in EPS and γ‐PGA cultivated cells, respectively. Additionally, a series of proteins associated with amino acid degradation were found to be repressed under EPS and γ‐PGA culture conditions. Transcriptional profiling via the qPCR detection of selected genes verified the proteomic analysis. Analysis of free amino acids in the bacterial cells further suggested the presence of amino acid starvation conditions. EPS or γ‐PGA was synthesized to alleviate the effect of amino acid limitation in B. licheniformis. This study identified a stress response mechanism in the synthesis of macromolecules in B. licheniformis, providing potential culture strategies to improve the production of two promising bioflocculants. Biotechnol. Bioeng. 2016;113: 797–806. © 2015 Wiley Periodicals, Inc. SWATH acquisition LC‐MS/MS method was adopted for differential proteomic analysis and a stress response mechanism was revealed in Bacillus licheniformis. Polymeric flocculant was synthesized to alleviate the effect of amino acid limitation on the metabolism of bacteria cells.