Elucidating the Role of a Putative Monooxygenase in the Catabolism of Nicotinic Acid and Nicotine by Bacillus niacini

Abstract

N‐Heteroaromatic compounds (NHACs) comprise a class of molecules that are commonly found in pharmaceuticals, personal care products, and pesticides and are known to have toxic effects on the environment. Intriguingly, certain species of soil‐dwelling bacteria have the innate ability to degrade particular NHACs. A better understanding of how these soil bacteria degrade NHACs has important implications in the development of bioremediation techniques to remove toxic compounds from the environment. This investigation focuses on developing preexisting hypotheses in regards to how Bacillus niacini, a ubiquitous species of soil bacteria, degrades nicotinic acid (NA) and nicotine, both of which are NHACs. It has been hypothesized that the non‐canonical NA degradation pathway in B. niacini involves a reaction in which 2,6‐dihydroxynicotinic acid undergoes oxidative decarboxylation to form 2,3,6‐trihydroxypyridine by a enzyme termed NicC‐like. The identity of the nicC‐like gene has yet to be established. A novel transformation technique was developed to generate a B. niacini knock out variant lacking the putative nicC gene. Though there are hypotheses regarding the identity of the nicC‐like gene and its involvement in NA catabolism, sequence analysis indicates that the nicC‐like gene is only 21% similar to the nicC gene involved in NA degradation in Pseudomonas putida. In contrast, the nicC‐like gene is 24% similar to HspB, which encodes an enzyme involved in nicotine degradation. Additionally, the structure and the associated catabolic processes of nicotine and NA are similar, suggesting that the novel nicC‐like gene in B. niacini might play a role in either nicotine or NA degradation. Preliminary HPLC evidence indicates that B. niacini does not degrade nicotine. Thus, the genes currently hypothesized to encode the genes necessary for NA catabolism do not code for nicotine degradation enzymes. Characterizing the reaction catalyzed by the putative NicC‐like enzyme and determining whether or not B. niacini catabolizes nicotine has led to an improved understanding about the genes necessary for NA degradation by this particular species of pervasive soil bacteria. Continued contributions to this field may eventually lead to the development of techniques to remove NHACs from the environment.Support or Funding InformationHenry J. Copeland Fund for Independent Study at the College of WoosterThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.