Superior performance and mechanism of chlorobenzene degradation by a novel bacterium

Abstract

A newly isolated strain was identified as Ochrobactrum sp. by 16S rRNA sequence analysis and named as ZJUTCB-1. The strain was able to degrade mono-chlorobenzene (CB) as the sole carbon and energy source under aerobic conditions. This study is the first to report the degradation of CB by the genus Ochrobactrum. The degradation rate of CB reached 170.9 μmol L⁻¹ h⁻¹, which is at least 6 times higher than the previously reported data. The strain can efficiently degrade CB under a rang of temperatures (30–40 °C) and pH (6.0–7.0) with optimum at 40 °C and pH 7.0. Salt concentration higher than 0.05 mol L⁻¹ remarkably reduced the biodegradation capability. Moreover, true oxic condition was not an essential element for biodegradation given that the CB degradation rate of 210.4 μmol L⁻¹ h⁻¹ was obtained under microaerobic condition. Based on the Haldane kinetic model, the maximum specific growth rate was 0.895 h⁻¹, which is the highest in ever described CB-degrading strains. According to GC-MS analysis and enzymatic assay, CB was degraded via the meta-cleavage pathway by using 2,3-dioxygenase and 2-chlorophenol as the main intermediates, producing CO₂ and Cl⁻ as the final products. The great performance of CB degradation by Ochrobactrum sp. ZJUTCB-1 provided an alternative for development of more effective and reliable biotreatment process.