Carotenoids Play a Positive Role in the Degradation of Heterocycles by Sphingobium yanoikuyae

Abstract

BackgroundMicrobial oxidative degradation is a potential way of removing pollutants such as heterocycles from the environment. During this process, reactive oxygen species or other oxidants are inevitably produced, and may cause damage to DNA, proteins, and membranes, thereby decreasing the degradation rate. Carotenoids can serve as membrane-integrated antioxidants, protecting cells from oxidative stress.FindingsSeveral genes involved in the carotenoid biosynthetic pathway were cloned and characterized from a carbazole-degrading bacterium Sphingobium yanoikuyae XLDN2-5. In addition, a yellow-pigmented carotenoid synthesized by strain XLDN2-5 was identified as zeaxanthin that was synthesized from β-carotene through β-cryptoxanthin. The amounts of zeaxanthin and hydrogen peroxide produced were significantly and simultaneously enhanced during the biodegradation of heterocycles (carbazole < carbazole + benzothiophene < carbazole + dibenzothiophene). These higher production levels were consistent with the transcriptional increase of the gene encoding phytoene desaturase, one of the key enzymes for carotenoid biosynthesis.Conclusions/Significance Sphingobium yanoikuyae XLDN2-5 can enhance the synthesis of zeaxanthin, one of the carotenoids, which may modulate membrane fluidity and defense against intracellular oxidative stress. To our knowledge, this is the first report on the positive role of carotenoids in the biodegradation of heterocycles, while elucidating the carotenoid biosynthetic pathway in the Sphingobium genus.

Genomewide characterisation of the genetic diversity of carotenogenesis in bacteria of the order Sphingomonadales

“…strain N81106 (previously Agrobacterium aurantiacum ) [ 33 ], Bradyrhizobium sp. ORS278 [ 34 ] and Sphingobium yanoikuyae XLDN2-5 [ 22 ]. Overlapping of crt ORFs is likely to facilitate coordinated gene expression, and it has been shown that the preceding ORFs (e.g.…”

Production of carotenoids byArthrobacter arilaitensisstrains isolated from smear-ripened cheeses

“…However, light was found to strongly affect carotenoid synthesis by all of these strains. In nonphotosynthetic bacteria, carotenoids play an important role as protectants against photo-oxidative damages (Liu et al, 2012). Carotenogenesis in these microorganisms may occur in three manners including constitutive, light-induced, or cryptic manner.…”

Bacteria belonging to the extremely versatile genus Arthrobacter as novel source of natural pigments with extended hue range

“…Although the role of carotenoids produced by the genus Arthrobacter has not been distinctly revealed, one function of carotenoids in microorganisms is to serve as membrane integrated antioxidants, protecting cells from oxidative stress (Krinsky, 1989;Liu et al, 2012).…”

“…nov., A. agilis, A. hyalinus) (Fong, Burgess, & Barrow, 2001;Kojima et al, 1993;Reddy et al, 2000). The nature of these compounds is still partly unknown, although some literature reported that yellow pigments belonging to the carotenoid family play an important role in physiological and molecular processes of these microorganisms such as: photosynthesis, survival to oxidative damage and resistance to UV-radiations (Dieser, Greenwood, & Foreman, 2010;Fong et al, 2001;Liu, Gai, Tao, Tang, & Xu, 2012).…”