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.