Gordonia sp. JDZX13 (source: industrial petroleum soil) shows good potential for dibenzothiophene (DBT) biodesulfurization. With the GC/MS analysis of metabolites and PCR-sequencing verification of the key desulfurization operon (dszA/dszB/dszC), the valuable “4S” pathway of DBT biodesulfurization in Gordonia sp. is identified. The key rate-limiting factors (2-hydroxybiphenyl/sulfate ions) suggest significant feedback inhibition effects on cell growth (μ_x) and biodesulfurization efficiency. Moreover, the qRT-PCR analysis of the dszA/dszB/dszC operon transcriptions also indicates the prominent negative effects on the key desulfurization enzyme activity, particularly under sulfate ion stress. Based on the abovementioned analysis, the oil/aqueous ratio in the two-phase system was optimized as 1 : 2 for better weakening of the inhibition effect, and a higher DBT removal efficiency (improved by 100.7%) was achieved. In addition, the DBT biodesulfurization mechanism is proposed. Related methods and mechanisms would be useful to further guide similar biocatalysis processes in the near future.

Research on copper resistance among various species has attracted considerable interest. However, due to the lack of effective and reproducible genetic tools, few studies regarding copper resistance have been reported for A. caldus .