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Acta Prataculturae Sinica ›› 2023, Vol. 32 ›› Issue (5): 147-158.DOI: 10.11686/cyxb2022183

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Screening of internal reference genes of Lactobacillus strain OL77 and determination of CspP expression patterns under low-temperature and low-pH stress

Ji-kuan CHAI(), Ze-liang JU, Gui-qin ZHAO()   

  1. College of Pratacultural Science,Gansu Agricultural University,Key Laboratory of Grassland Ecosystem,Ministry of Education,Lanzhou 730070,China
  • Received:2022-04-20 Revised:2022-06-20 Online:2023-05-20 Published:2023-03-20
  • Contact: Gui-qin ZHAO

Abstract:

The aim of this study was to explore aspects of gene expression under low temperature and low pH in the cold-tolerant bacterium Pediococcus pentosaceus OL77, which was selected during low-temperature ensiling. To investigate the cold tolerance mechanism of P. pentosaceus OL77, we obtained its CspP gene by homologous cloning. GeNorm, NormFinder, BestKeeper, and RefFinder procedures were used to select internal reference genes with stable expression in OL77 under low-temperature and low-pH stress as detected using SYBR-Green real-time fluorescence quantitative PCR (RT-qPCR). The selected internal reference genes were then used to analyze the transcriptional profile of CspP under low temperature. It was found that the relatively stably expressed internal reference genes of OL77 under low-temperature and low-pH stress were Ldhtufa, and 6PGDH, while GAPDH and GyrA were not stably expressed. A gene fragment of CspP was obtained by homologous cloning, and its relative transcript levels in OL77 at 0, 1, 3, 6, 12 and 24 h of treatment at 25, 15 and 5 ℃ were analyzed using Ldh and 6PGDH as internal reference genes. The transient expression of CspP increased sharply under low temperature. Its transcript level was increased by 86 times at 5 ℃ compared with that at 25 ℃, suggesting that it plays roles in the cold tolerance of OL77. The cold tolerance of OL77 may result from increased expression of a cold shock protein at low temperature. Our findings suggest that CspP could be used as a cold tolerance indicator gene for OL77.

Key words: low temperature, low pH, internal reference gene, CspP gene, expression pattern