AUTHOR=Huang Haiyan , Shang Jinmeng , Wang Shuning 

TITLE=Physiology of a Hybrid Pathway for Nicotine Catabolism in Bacteria

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 11 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.598207

DOI=10.3389/fmicb.2020.598207

ISSN=1664-302X

ABSTRACT=Nicotine is a major N-heterocyclic aromatic alkaloid produced in tobacco plants and the main toxic chemical in tobacco waste. Due to its complex physiological effects and toxicity, it has become a concern for the health and environment. A number of bacteria belonging to the genus Arthrobacter and Pseudomonas can degrade nicotine via the pyridine and pyrrollidine pathways. Recently, a novel hybrid of the pyridine and pyrrolidine pathways (also known as the VPP pathway) was found in the Rhizobiale group bacteria Agrobacterium tumefaciens S33, Shinella sp. HZN7, and Ochrobactrum sp. SJY1, and other group bacteria. The special mosaic pathway has drawn much attention from microbiologists to study their molecular and biochemical mechanisms. This will benefit the development of new biotechnologies to utilize nicotine, the enzymes involved in its catabolism, and the microorganisms capable of degrading the alkaloid. In this pathway, some metabolites are hydroxylated in the pyridine ring or modified in the side chain with active groups, which can be used as precursors for the synthesis of some important compounds in the pharmaceutical and agricultural industries. Moreover, some enzymes may be used for industrial biocatalysis to transform pyridine derivatives into desired chemicals. Here, we review the molecular and biochemical basis of the hybrid nicotine-degrading pathway and discuss the electron transport in its oxidative degradation for energy conservation and bacterial growth.