Screening of antifreeze-thawed lactic acid bacteria and their effects on oat silage fermentation quality and aerobic stability北大核心CSCD

The effects of freeze-thaw conditions on the fermentation quality and aerobic stability of oat silage were investigated. Four strains of freeze-thaw-resistant lactic acid bacteria（LAB）with rapid growth and efficient acid production were screened from 437 strains，which had been isolated from the Qinghai-Tibetan Plateau. Based on physiological and biochemical characteristics and 16S rRNA gene sequence alignment，the four strains were identified as Lactobacillus plantarum 157（LP157），L. plantarum 160（LP160），Lactobacillus brevis 248（LB248），and Lactobacillus pentosus 260（LPE260）. In order to investigate their effects on the fermentation quality，nutrient composition，microbial counts and aerobic stability of oat silage under freeze-thaw conditions，seven treatments were tested as follows：1）LP157；2）LP160；3）LB248；4）LPE260；5）LP160+Lactobacillus rhamnosus 753 mixture （MIX）；6）A commercial bacterial silage additive（COM）；7）The same amount of sterilized distilled water（CK）. All treatments were ensiled for 60 days at a constant temperature of 20 ℃ and under a 20 ℃/-5 ℃ regime alternating every 12 h（freeze-thaw）. LP inoculation improved silage quality：The pH and dry matter loss in silages inoculated with LP157，LP160，LB248 and LPE260 were significantly lower than CK（P<0. 05）and lactic acid and acetic acid contents were significantly higher than CK（P<0. 05），and the growth of spoilage micro-organisms such as coliform bacteria，yeast and mold were inhibited，both with fermentation at constant 20 ℃ and under freeze-thaw conditions. After aerobic exposure for 5 days，the pH and NH3-N of silages treated with LP157，LP160，LB248 and LPE260 were significantly（P<0. 05） lower than CK，MIX and COM. The aerobic stability of oat silage was improved，especially when inoculated with LP160（70 h vs. CK 11 h）. The results show that the four screened strains can be used as effective LAB inoculants for silage preparation in the freeze-thaw environment of the Qinghai-Tibetan Plateau. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.

Screening of antifreeze-thawed lactic acid bacteria and their effects on oat silage fermentation quality and aerobic stability

The effects of freeze-thaw conditions on the fermentation quality and aerobic stability of oat silage were investigated. Four strains of freeze-thaw-resistant lactic acid bacteria （LAB） with rapid growth and efficient acid production were screened from 437 strains， which had been isolated from the Qinghai-Tibetan Plateau. Based on physiological and biochemical characteristics and 16S rRNA gene sequence alignment， the four strains were identified as Lactobacillus plantarum 157 （LP157）， L. plantarum 160 （LP160）， Lactobacillus brevis 248 （LB248）， and Lactobacillus pentosus 260 （LPE260）. In order to investigate their effects on the fermentation quality， nutrient composition， microbial counts and aerobic stability of oat silage under freeze-thaw conditions， seven treatments were tested as follows： 1） LP157； 2） LP160； 3） LB248； 4） LPE260； 5） LP160+Lactobacillusrhamnosus 753 mixture （MIX）； 6） A commercial bacterial silage additive （COM）； 7） The same amount of sterilized distilled water （CK）. All treatments were ensiled for 60 days at a constant temperature of 20 ℃ and under a 20 ℃/-5 ℃ regime alternating every 12 h （freeze-thaw）. LP inoculation improved silage quality： The pH and dry matter loss in silages inoculated with LP157， LP160， LB248 and LPE260 were significantly lower than CK （P<0.05） and lactic acid and acetic acid contents were significantly higher than CK （P<0.05）， and the growth of spoilage micro-organisms such as coliform bacteria， yeast and mold were inhibited， both with fermentation at constant 20 ℃ and under freeze-thaw conditions. After aerobic exposure for 5 days， the pH and NH₃-N of silages treated with LP157， LP160， LB248 and LPE260 were significantly （P<0.05） lower than CK， MIX and COM. The aerobic stability of oat silage was improved， especially when inoculated with LP160 （70 h vs. CK 11 h）. The results show that the four screened strains can be used as effective LAB inoculants for silage preparation in the freeze-thaw environment of the Qinghai-Tibetan Plateau.