Co-biodegradation of cyanide and phenol by Alcaligenes faecalis JF101: Investigating interaction effects

Abstract

Cyanide and phenol are highly toxic chemicals that exert severe inhibitory effects on microorganisms, posing significant challenges for their removal by biological methods in coexistent systems. In this study, we successfully isolated a bacterial strain named JF101, identified as Alcaligenes faecalis, which was capable of degrading both cyanide and phenol. The interactions between cyanide and phenol during biodegradation were investigated. It was found that the presence of 100 mg/L cyanide significantly enhanced the degradation of phenol, leading to the complete degradation of 1000 mg/L phenol within 86 h. In contrast, only 21.9% of phenol was degraded in the absence of cyanide. Additionally, the presence of phenol had minimal impact on cyanide degradation; a concentration of 100 mg/L cyanide could be rapidly and completely degraded within 40 min even in the presence of up to 1000 mg/L phenol. Five empirical kinetic models of Haldane, Aiba, Edward, Yano, and Webb were employed to describe the degradation processes of phenol and cyanide in both single-substrate and dual-substrate systems. The putative degrading enzymes, degradation products, and pathways associated with the co-degradation of cyanide and phenol were systematically analyzed. The formamide and NH₄⁺-N produced from the rapid degradation of cyanide served as nitrogen sources, facilitating the resumed growth of strain JF101 and enhancing phenol degradation.