关键词: 地衣芽孢杆菌, 发酵, 脱铬皮屑, 条件优化

Abstract: The fermentation conditions for wet blue shavings with Bacillus licheniformis were systematically studied and optimized. The results showed that the optimized fermentation conditions for P4 strain were cell age 24 h, solid-liquid ratio 1∶15, inoculum size 0.5%, fermentation temperature 37 ℃, pH 9.0 and fermentation for 48 h. SDS-PAGE analysis was employed to show the molecular weight distribution of the proteins in the fermentation broth at different fermentation time, and the results indicated that after 12 h of fermentation, the protein bands exhibited a clear continuous distribution, and the molecular weight was relatively large, basically 20.0 kda and above. After fermentation for 48 h, the molecular weight was basically below 14.4 kda, indicating that the dechromed wet blue shavings had been mostly degraded into free amino acids and small molecular peptides which are easily absorbed by plants. Composition analysis of the fermentation broth showed that the free amino acids mainly included proline, cysteine, alanine and histidine, and the total free amino acid content and total peptide content were 1 g/L, and 13.21 g/L, respectively. No mercury, arsenic, cadmium and lead elements were detected in the fermentation broth, and the chromium content was 2.91 mg/kg. The content of heavy metals in the fermentation broth met the national standards of the Ministry of Agriculture. The fermentation broth of dechromed wet blue shavings is expected to be used as a bio-organic slow-release fertilizer to promote the growth of plants.

Key words: bacillus licheniformis, fermentation, dechromed wet blue shavings, condition optimization