Study on the capability of a bacterial strain for aniline degradation under some specific circumstances

Abstract

The purpose of the study is to explore the characteristics of a laboratory cultured bacterial strain Delftia sp. named AD1 for aniline degradation. Several degradation conditions were studied to provide information for biological treatment of aniline-containing wastewater. The bacterial strain AD1 is salt-tolerant, and the most suitable salt concentration for the growth of AD1 and the biodegradation of aniline is 5% (NaCl w/v), but when the salinity surpasses 5%, the growth of AD1 and the biodegradation of aniline could be restricted. The copper ion (Cu2+) had the most significant restriction impact on the growth of AD1, but up to 99.9% of aniline (initial concentration: 600mg/L) can be degraded under the effect of heavy metal ion. Both the single bacterial strain AD1 and mixed bacterial strains (AD1 and nitrifying bacteria) can efficiently degrade aniline, and the degradation rate of aniline for both groups reached 99.9%. However, the mixed bacterial strains did not show palpable advantage of the speed of aniline degradation over single bacterial strain AD1. Though nitrifying bacteria in the mixed bacterial strains was expected to degrade the ammonia nitrogen produced in aniline biodegradation process, there was no conspicuous difference in the concentration of ammonia nitrogen and total nitrogen between the samples of single bacterial strain AD1 and mixed bacterial strains.