International Journal of Molecular Sciences Review Chemotaxis Towards Aromatic Compounds: Insights from Comamonas testosteroni Yun-Hao Wang 1,2, Zhou Huang 1 and Shuang-Jiang Liu 1,2,* 1 State Key Laboratory of Microbial Resources and Environmental Microbiology Research Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China;
[email protected] (Y.-H.W.);
[email protected] (Z.H.) 2 University of Chinese Academy of Sciences, Beijing 101408, China * Correspondence:
[email protected]; Tel.: +86-10-64807423 Received: 21 April 2019; Accepted: 30 May 2019; Published: 1 June 2019 Abstract: Chemotaxis is an important physiological adaptation that allows many motile bacteria to orientate themselves for better niche adaptation. Chemotaxis is best understood in Escherichia coli. Other representative bacteria, such as Rhodobacter sphaeroides, Pseudomonas species, Helicobacter pylori, and Bacillus subtilis, also have been deeply studied and systemically summarized. These bacteria belong to α-, γ-, "-Proteobacteria, or Firmicutes. However, β-Proteobacteria, of which many members have been identified as holding chemotactic pathways, lack a summary of chemotaxis. Comamonas testosteroni, belonging to β-Proteobacteria, grows with and chemotactically responds to a range of aromatic compounds. This paper summarizes the latest research on chemotaxis towards aromatic compounds, mainly from investigations of C. testosteroni and other Comamonas species. Keywords: Comamonas testosteroni; chemoreceptor; chemotaxis; aromatic compounds 1. Introduction Aromatic compounds have one or more aromatic rings containing resonance bonds, which make them chemically inert due to charge distribution over the whole skeleton of the aromatic ring. It has been estimated that about 25% of photosynthetic products from plants are deposited as lignin, which is one of the most abundant aromatic compounds on earth [1,2].