AUTHOR=Xu Mengfan , Hu Shanhu , Wang Yiwen , Wang Tao , Dziugan Piotr , Zhang Bolin , Zhao Hongfei 

TITLE=Integrated Transcriptome and Proteome Analyses Reveal Protein Metabolism in Lactobacillus helveticus CICC22171

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.635685

DOI=10.3389/fmicb.2021.635685

ISSN=1664-302X

ABSTRACT=<p><italic>Lactobacillus helveticus</italic> is a homofermentative lactic acid bacterium. It is widely used in the fabrication of Swiss cheese and other dairy products. The aim of this study was to elucidate the mechanism by which <italic>L. helveticus</italic> utilizes protein. <italic>Lactobacillus helveticus</italic> CICC22171 were cultured in two different media with various nitrogen sources. The control contained 20 basic amino acids, while the experimental medium contained casein. <italic>De novo</italic> transcriptome and isobaric tags for relative and absolute quantification (iTRAQ) proteome analyses were applied to determine how <italic>L. helveticus</italic> utilizes protein. The casein underwent extracellular hydrolysis <italic>via</italic> ATP-binding cassette (ABC) transporter upregulation and Mn<sup>2+</sup>-associated cell envelope proteinase (CEP) downregulation. Sigma factors and EF-Tu were upregulated and Mg<sup>2+</sup> was reduced in bacteria to accommodate DNA transcription and protein translation in preparation for proteolysis. Hydrolase activity was upregulated to digest intracellular polypeptides and control endopeptidase genes. In these bacteria, casein utilization affected glycolysis, trehalose phosphotransferase system (PTS), and key factors associated with aerobic respiration and reduced glucose consumption.</p>