Abstract
The complex mixtures of antibiotics and heavy metals are commonly existed in livestock and poultry breeding wastewater. Effective and simultaneous removal of these toxic compounds by microorganisms, especially single strains, remains a considerable challenge. In this study, a novel functional strain SDB4, isolated from duck manure and identified as Bacillus sp., has been shown to possess high removal capabilities for both sulfamethoxazole (SMX) and Zn2+. The maximum removal efficiency achieved 73.97% for SMX and 84.06% for Zn2+ within 48 h in the single pollution system. It has great potential for eliminating SMX along with Zn2+, 78.45% of SMX and 52.91% of Zn2+ were removed in the 20 mg·L-1 SMX and 100 mg·L-1 Zn2+ binary system. Furthermore, the SMX-biotransformation capability of SDB4 was enhanced at low concentrations of Zn2+ (below 100 mg·L-1). The SMX biotransformation and Zn2+ adsorption data fitted well with the pseudo-first-order kinetic model, indicating that the two pollutants were in accordance with the same removal rule. N4-acetyl-SMX was identified as the main stable transformation product during SMX removal. FTIR analyses revealed that OH, NH2, C=O, C-N/N-H, and C-O-C played major roles in the adsorption of Zn2+. Our study of the dually functioning strain SDB4 provides a potential application for the simultaneous biological removal of antibiotics and heavy metals.
Highlights
With the dietary evolution of humans, the actual scale of global animal rearing and meat production has increased, resulting in intensification of livestock farming (Tullo et al 2019)
High levels of complex contaminants contribute to the accumulation of antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs) (Chen et al 2018; Christou et al 2017)
Strain SDB4 is an aerobic gram-negative strain, and waxy, circular, non-translucent colonies were formed on LB solid plate
Summary
With the dietary evolution of humans, the actual scale of global animal rearing and meat production has increased, resulting in intensification of livestock farming (Tullo et al 2019). In contrast with traditional feeding methods, livestock diseases are increasingly complex in the intensive and large-scale feeding industry. These diseases spread rapidly and cause huge economic losses once outbreak becomes endemic. Only partial antibiotics/heavy metals can be metabolized/absorbed by livestock, causing a large number of residues in the excreta (Liu et al 2016; Xu et al 2016). These elements are readily accessible to the land and entered the water through leaching and direct runoff, thereby spreading drug and heavy metal contamination (Lillenberg et al 2010; Pan et al 2018; Trenouth and Gharabaghi 2015). It is urgently needed to remove the combined contaminants from aquaculture wastewater
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