Catalytic Hydrothermal Liquefaction of Penicillin Residue for the Production of Bio-Oil over Different Homogeneous/Heterogeneous Catalysts

In this study, penicillin residue (PR) was used to prepare bio-oil by hydrothermal liquefaction. The effects of homogeneous (organic acid and alkaline catalysts) and heterogeneous catalysts (zeolite molecular sieve) on the yield and properties of bio-oil were investigated. The results show that there are significant differences in the catalytic performance of the catalysts. The effect of homogeneous catalysts on the bio-oil yield was not significant, which only increased from 26.09 (no catalysts) to 31.44 wt.% (Na2CO3, 8 wt.%). In contrast, heterogeneous catalysts had a more obvious effect, and the oil yield reached 36.44 wt.% after adding 5 wt.% MCM-48. Increasing the amount of catalyst enhanced the yield of bio-oil, but excessive amounts of catalyst led to a secondary cracking reaction, resulting in a reduction in bio-oil. Catalytic hydrothermal liquefaction reduced the contents of heteroatoms (oxygen, mainly), slightly increased the contents of C and H in the bio-oil and increased the higher heating value (HHV) and energy recovery (ER) of bio-oil. FTIR and GC-MS analyses showed that the addition of catalysts was beneficial in increasing hydrocarbons and oxygen-containing hydrocarbons in bio-oil and reducing the proportion of nitrogen-containing substances. Comprehensive analyses of the distribution of aromatic, nitrogen-containing and oxygen-containing components in bio-oil were also performed. This work is beneficial for further research on the preparation of bio-oil by hydrothermal liquefaction of antibiotic fermentation residue.

Rapid Contamination Detection in Validamycin A Production by HS-SPME/GC-MS

Background: Validamycin A (Val-A) is one of the most widely used agricultural antibiotics in East Asia especially for controlling rice sheath blight disease. Fermentation contamination of the industrial Val-A producing strain is a common occurrence. Methods: Fermentation culture of S. hygroscopicus 5008 has a special smell that could be distinguished from other tainted samples. The change of the volatiles in untainted and tainted samples was characterized using headspace solid phase microextraction (HS-SPME) combined with gas chromatography- mass spectrometry (GC-MS). Results: Seventy-one volatile compounds (including alkanes, amines, alcohols, esters, aldehydes and others) were identified and there were significant differences in the composition of volatiles among different samples. Principal component analysis (PCA) based on the GC-MS data was used to identify the important volatile compounds that contributed to the differentiation of the fermentation samples under different fermentation stages, as well as among different pollution species and fermentation media. Contamination could be discovered in time irrespective of the stage of fermentation and the contaminating bacteria in broth. Conclusion: It is the first report to detect contamination by volatile compounds in the antibiotic fermentation and it was proved that HS-SPME/GC-MS is an effective contamination detection method in Val-A production.