Oxidization and biodegradation of sulfur black by a newly isolated strain Acinetobacter sp. DS-9

Sulfur black is a high-sulfur polymeric compound, mainly used for dyeing cotton textiles. It is part of the most widely used sulfur dyes in China. Wastewater containing sulfur dyes is sometimes difficult to treat, due to its high Chroma, many suspended solids and poor biodegradability. The aim of this study was to screen microorganisms with high-efficiency sulfur-oxidizing and sulfur black degrading capabilities. The DS-9 strain, with effective sulfur black degrading capability, was isolated from agricultural soil. Physio-biochemical identification and sequence alignments of 16S rRNA illustrated that this strain belongs to the genus of Acinetobacter. Under the initial degradation conditions, the SO 42- content in the culture medium containing Acinetobacter sp. DS-9 was 15.22% higher than that of the control test on the fifth day. Single-factor optimization and orthogonal design were used to improve the desulfurization efficiency of DS-9 in a medium containing 100 mg L-1 sulfur black. The optimal degradation system was as follows: soluble starch 500 mg L-1, 400 mg L-1 NH4Cl, 7 g L-1 Tween 80, 28 degrees C, 200 rpm, 5% inoculum volume, and pH 7.2. Under the optimal degradation conditions, the content of SO42- in the culture medium increased by 52.06% over 4 d compared with the CK.