• 中文核心期刊
  • CSCD来源期刊
  • 中国科技核心期刊
  • CA、CABI、ZR收录期刊

纤维素降解菌产酶条件优化及其堆肥效果研究

Optimization of enzyme production conditions of cellulolytic bacteria and the effect of compost

  • 摘要:
    目的 筛选出适用于青海地区纤维素类物质降解的菌株,提高堆肥效果。
    方法 以青海省海北州森林土壤为样品,采用刚果红染色法和3,5-二硝基水杨酸(3,5-dinitrosalicylic acid, DNS)法筛选高效纤维素降解菌株,利用生理生化试验和16S rDNA序列分析对菌株进行鉴定,并优化其发酵产纤维素酶条件,制成菌剂后按1%的接种量接种于堆肥试验中,测定堆肥各项腐熟指标。
    结果 筛选出的高活性降解菌MX-1-1为蕈状芽胞杆菌(Bacillus mycoides),该菌株羧甲基纤维素酶活、滤纸酶活和外切-β-葡聚糖酶活分别为24.95、11.36、16.15 U·mL−1。最适产羧甲基纤维素酶发酵条件:氮源牛肉膏、碳源CMC-Na、培养基初始pH 5.0、发酵温度20 ℃、培养时间3 d,优化后羧甲基纤维素酶活力提高了51.5%。堆肥过程中,添加MX-1-1菌剂的堆体升温快,高温期持续时间长,pH波动幅度小。堆肥结束时,堆体电导率为0.96 ms·cm−1,含水量最低,硝态氮和铵态氮含量均达到腐熟标准,全氮和有机质含量优于对照和D50菌剂堆体。
    结论 菌株MX-1-1具有较强的纤维素降解能力,能够促进堆体微生物代谢,加快堆体腐熟,并提高堆肥品质。

     

    Abstract:
    Objective To screen out the strains suitable for cellulose degradation on the Qinghai-Tibet Plateau and enhance the composting effect.
    Method Forest soil samples from Haibei Prefecture of Qinghai Province were selected using Congo red staining and the 3, 5- Dinitrosalicylic acid (DNS) method. Physiological and biochemical tests as well as 16S rDNA sequence analysis were employed to identify the high-efficiency cellulose-degrading strains. The conditions for cellulase production through fermentation were optimized, and the bactericide was inoculated in the compost experiment with an inoculation amount of 1%, and the maturation indexes of the compost were determined.
    Result The highly active degrading bacterium MX-1-1 was identified as a strain of Bacillus mycoides. The activities of carboxymethyl cellulase, filter paper enzyme, and exo-β-glucanase were 24.95, 11.36, and 16.15 U·mL−1, respectively. The optimal fermentation conditions for carboxymethyl cellulase production were as follows: beef paste as the nitrogen source, CMC-Na as the carbon source, an initial pH of 5.0 of the medium, a fermentation temperature of 20 ℃, a culture time of 3 days, and the activity of carboxymethyl cellulase increased by 51.5% after optimization. During the composting process, the pile with the MX-1-1 bactericide rose in temperature rapidly, the high-temperature period lasted for a long time, and the pH volatility is small. At the end of composting, the conductivity of the pile was 0.96 ms·cm−1, the water content was the lowest, the contents of nitrate nitrogen and ammonium nitrogen reached the decomposition standard, and the contents of total nitrogen and organic matter were superior to those of the control and D50 bacteria agent piles.
    Conclusion The screened strain MX-1-1 possesses high cellulose degradation ability, which can boost microbial metabolic activity, accelerate decomposition, and improve the quality of compost.

     

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