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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (5): 103-114.DOI: 10.11686/cyxb2021358

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Screening and identification of low temperature tolerant lactic acid bacterial epiphytes from oats on the Qinghai-Tibetan Plateau

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

  1. College of Pratacultural Science,Gansu Agricultural University,Key Laboratory of Grassland Ecosystem,Ministry of Education,Sino-U. S. Centers for Grazing Land Ecosystem Sustainability,Lanzhou 730070,China
  • Received:2021-09-27 Revised:2021-10-31 Online:2022-05-20 Published:2022-03-30
  • Contact: Gui-qin ZHAO

Abstract:

This research aimed to identify potential lactic acid bacteria (LAB) strains that provide improved fermentation quality of oat (Avena sativa) silage under low temperature. Epiphytic LAB were collected from oat plants at different altitudes on the Qinghai-Tibetan Plateau. Cold tolerant strains were screened by restricted culture, and their acid and salinity tolerance, acid production and growth rate were compared. These strains were identified by means of 16S rDNA sequence analysis. In the initial isolation 232 strains of lactic acid bacteria were isolated, and 56 of these were retained for further screening after Gram’s stain testing, microscopy and a catalase test. Low temperature screening revealed 18 low-temperature tolerant strains. These could grow at temperatures of 5-20 ℃, 3.0% and 6.0% NaCl, and pH 3.0-5.0. Among these 18 strains, 14 were homofermentative and 4 strains were heterofermentative. For the 14 homofermentative LAB strains, strains designated OCPP3, OL3, OL8, OL25, OL36, OL54, OL77 and OL122 had higher acid production and growth rate than others. OCPP3, OL36 and OL77 were identified as Pediococcus pentosaceus, OL3 and OL54 as Lactobacillus pentosus, and OL8, OL25 and OL122 as Lactobacillus plantarum. After culturing for 25 h, the optical density (OD) value of strain OL77 (2.52) was the highest among all cultured strains, followed by OL54 (2.50). Considering the observed low temperature tolerance, acid production and growth rate, and their diversity, these three LAB strains show promise as potential additives for oat silage fermentation at low temperature on the Qinghai-Tibetan Plateau.

Key words: Qinghai-Tibetan Plateau, oats, silage, low temperature tolerant-lactic acid bacteria