Welcome to Chinese Agricultural Science Bulletin,

Chinese Agricultural Science Bulletin ›› 2022, Vol. 38 ›› Issue (28): 21-27.doi: 10.11924/j.issn.1000-6850.casb2021-0977

Special Issue: 生物技术

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Straw Degrading Bacterial Strains: Screening and Their Response to pH

ZHANG Yun1(), SA Rula1(), BAO Guirong1, SA Rulaqiqige2, TAI Jicheng1, LI Xiang1   

  1. 1College of Agriculture, Inner Mongolia Minzu University, Tongliao, Inner Mongolia 028000
    2Ordos City Forestry and Grassland Comprehensive Law Enforcement Detachment, Ordos, Inner Mongolia 017000
  • Received:2021-10-14 Revised:2022-06-16 Online:2022-10-05 Published:2022-09-28
  • Contact: SA Rula E-mail:qaqzy1203@163.com;625968785@qq.com

Abstract:

The paper aims to provide bacterial strain resources for straw returning to field in cold and cool areas. Taking the soil in low temperature environment and cellulose-rich decomposing materials as the bacterial source, the straw-degrading bacterial strains were screened by enrichment and subculture, and the straw decomposing agent, which is the main recommendation in production, was used as the test material. Fermentation of straw was conducted at 15℃ and 20℃, and under pH 4.5, 5.5, 6.5, 7.5, 8.5, 9.5, the OD600 value of the fermentation broth was measured every 24 hours, and the filter paper enzyme activity, cellulase and straw degradation rate were measured after 15 days of fermentation, to explore the degradation effect of corn straw. The results showed that the rate of cellulose decomposition was accelerated when the strain was subcultured for 5-6 generations; the fermentation broth of the two test materials with different pH reached the peak on the 6th day at 15℃, and the highest peak was at pH 7.5. The two test materials were different at 20℃. The OD600 value of pH fermentation broth reached the peak value on the 7th day, the highest peak value of straw-degrading bacterial strains No.8 was pH 8.5, and the highest peak value of straw decomposing agent was pH 5.5. The filter paper enzyme activity of straw-degrading bacterial strains No.8 at pH 8.5 and 15℃ was significantly higher than that of straw decomposing agent, so did the cellulose activity at pH 7.5. The cellulase activity of straw decomposing agent was higher than that of straw-degrading bacterial strains No.8 at pH 4.5 and 20℃. Under the conditions of 15℃ and 20℃, straw-degrading bacterial strains No.8 had higher straw degradation rate at pH 7.5, while the straw decomposing agent had higher degradation rate at pH 4.5 and pH 5.5. Under the same fermentation conditions, straw-degrading bacterial strains No.8 had significantly higher degradation rate of straw than straw decomposing agent. The suitable conditions for straw-degrading bacterial strains No.8 to degrade straw are neutral and alkaline under medium and low temperature, while the conditions for the straw decomposing agent are acidic under medium temperature.

Key words: straw-degrading bacterial strains, pH, temperature, straw degradation rate, enzymatic activity

CLC Number: