Additions of esterase and rhamnolipid promote the degradation of Inner Mongolia coal by Pseudomonas japonica

The biodegradation of Inner Mongolia coal by Pseudomonas japonica (P. japonica) was investigated, showing that the biodegradability of P. japonica was related to its secretions: esterase (Es) and rhamnolipid (Rh). Therefore, the efficiencies of coal biodegradation were explored through additions of Es, Rh and the mixture of Es and Rh (Es-Rh) to the biodegradation system, respectively. It was found that the coal biodegradation rate all increased in the presence of Es-Rh, Es or Rh, among which Es-Rh significantly increased the coal biodegradation rate. When the ratio of Es-Rh was 150 mg/mL:1200 mg/mL, the coal biodegradation rate reached a maximum of 65.3% higher than the control group 18.8%, it was because the optical density and esterase activity of P. japonica were the highest, while the electronegativity and adsorption rate of coal samples were the optima. GC-MS of the degradation liquid products showed that the compositions of degradation liquid products in the presence of Es -Rh mainly contained long-chain alkanes, alcohols and ethers, of which the highest content of long-chain alkanes was 81.13%. FTIR analysis confirmed that the C-H, C-C and-COOR groups in Inner Mongolia coal were degraded in the presence of Es-Rh. XRD analysis demonstrated that the Lc and Nave decreased in the presence of Es-Rh, indicating that the crystallization degree of Inner Mongolia coal decreased. This study indicated that the addition of mixture of Es and Rh could significantly promote the degradation of Inner Mongolia coal by P. japonica.

Automated summary

This study investigated the biodegradation of Inner Mongolia coal by Pseudomonas japonica and found that the addition of esterase and rhamnolipid significantly increased the biodegradation rate. The highest degradation rate was achieved when the ratio of esterase to rhamnolipid was 150 mg/mL:1200 mg/mL, resulting in a 65.3% increase compared to the control group.