| The unique and hostile ecological environment of Qinghai-Tibet plateau affects the herbage production. Elymus nutans is a kind of high quality forage which is widely planted and used to be hayed and ensilinged as supplementary feeding in winter in Qinghai-Tibet plateau. However, there has no scientific measure to process and utilize.Besides,the microbial community and forage nutrients vary with the altitude of Qinghai-Tibet plateau. In order to select the LAB which can tolerate low temperature, we studied the fermentation quality(silage quality and nutrition) of Elymus nutans from different altitudes(Tianzhu2965m, Golok 3763 m, Damxung 4228 m and Nagchu 4752m), and inoculated the selected strains on Elymus nutans silage to evaluate the fermentation quality. The main results are as follows:The concentration of crude protein, crude fiber and counts of epiphytic lactic acid bacteria and fungus on the Elymus nutans increased with the increasing altitude, whereas the amount of the yeast was stable and the water soluble carbohydrates content decreased.One hundred and eight straits of lactic acid bacteria were isolated from Elymus nutans,forty from Avena sativa and Kobresia tibetica. These strains were assigned to 2 genera and7 species based on 16 S r DNA sequence analysis. The 2 genera included Lactobacillus and Pediococcus, the 7 species included Lactobacillus plantarum, Pediococcus pentosaceus,Lactobacillus casei, Lactobacillus coryniformis,Lactobacillus sakei,Lactobacillus brevis and Lactobacillus curvatus from Elymus nytans. 4 strains belonged to Lactobacillus plantarum and 16 strains belonged to Pediococcus pentosaceus from Avena sativa L. silage juice. 6 strains pertained to Lactobacillus plantarum and 14 strains pertained to Pediococcus pentosaceus from Kobresia tibetica silage juice.Selecting Lactobacillus plantarum numbered 31, Lactobacillus casei numbered Q5,Pediococcus pentosaceus Numbered Q6 and Lactobacillus coryniformis numbered Q7 aslow temperature resistance LAB by means of culture medium under 10℃ and green juice at10℃,15℃ and 25℃.The physiological and biochemical characteristics results showed that No. 31 could not ferment raffinose and melibiose but the reference strain; No. 31 could use Arginine produce ammonia, but the reference strain could not. No. Q5 could ferment more kinds of carbohydrate sources such as sorbitol, amygdalin, esculoside and arginine. PP-Q6 could reduce nitrate. Q7 could suffer from lower temperature and meta-acid environment contrasting with the reference LAB. The results of CGMCC showed that the No. Q5 and No.Q6 could not ferment lactose, but the reference LAB. could.Inoculating the selected strains into Elymus nutans silages under 10℃,15℃ and 25℃for 30 d, 60 d and 90 d, respectively. The results showed that the quality of the silage inoculated LAB was better than the control under 10℃ and 15℃. Adding Pediococcus pentosaceus Q6 into the silages showed more significant advantage than the control and APP inoculation samples for 60 d.All of the above, inoculating Pediococcus pentosaceus Q6 into the silage is an excellent LAB. for the low temperature ensiling. |
