title: Involvement of Fenton chemistry in rice straw degradation by the lignocellulolytic bacteriumPantoea ananatisSd-1.
abstract: BACKGROUND
  Lignocellulolytic bacteria have revealed to be a promising source for biofuel production, yet the underlying mechanisms are still worth exploring. Our previous study inferred that the highly efficient lignocellulose degradation by bacteriumPantoea ananatisSd-1 might involve Fenton chemistry (Fe2++ H2O2+ H+→ Fe3++ OH· + H2O), similar to that of white-rot and brown-rot fungi. The aim of this work is to investigate the existence of this Fenton-based oxidation mechanism in the rice straw degradation process ofP. ananatisSd-1.
  
  
  RESULTS
  After 3 days incubation of unpretreated rice straw withP. ananatisSd-1, the percentage in weight reduction of rice straw as well as its cellulose, hemicellulose, and lignin components reached 46.7, 43.1, 42.9, and 37.9 %, respectively. The addition of different hydroxyl radical scavengers resulted in a significant decline (P< 0.001) in rice straw degradation. Pyrolysis gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy analysis revealed the consistency of chemical changes of rice straw components that exists betweenP. ananatisSd-1 and Fenton reagent treatment. In addition to the increased total iron ion concentration throughout the rice straw decomposition process, the Fe3+-reducing capacity ofP. ananatisSd-1 was induced by rice straw and predominantly contributed by aromatic compounds metabolites. The transcript levels of the glucose-methanol-choline oxidoreductase gene related to hydrogen peroxide production were significantly up-regulated (at leastP< 0.01) in rice straw cultures. Higher activities of GMC oxidoreductase and less hydrogen peroxide concentration in rice straw cultures relative to glucose cultures may be responsible for increasing rice straw degradation, which includes Fenton-like reactions.
  
  
  CONCLUSIONS
  Our results confirmed the Fenton chemistry-assisted degradation model inP. ananatisSd-1. We are among the first to show that a Fenton-based oxidation mechanism exists in a bacteria degradation system, which provides a new perspective for how natural plant biomass is decomposed by bacteria. This degradative system may offer an alternative approach to the fungi system for lignocellulosic biofuels production.
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People's Republic of China.
authors.forename: Jiangshan
authors.initials: J
authors.lastname: Ma
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People's Republic of China.
authors.forename: Keke
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People's Republic of China.
authors.forename: Mei
authors.initials: M
authors.lastname: Huang
authors.affiliation: Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Private Bag X1, Matieland, 7602 South Africa ; DNA Sequencing Unit, Central Analytical Facility, Stellenbosch University, Private Bag X1, Matieland, 7602 South Africa.
authors.forename: Stanton B
authors.initials: SB
authors.lastname: Hector
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People's Republic of China.
authors.forename: Chunyi
authors.initials: C
authors.lastname: Tong
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People's Republic of China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People's Republic of China.
authors.forename: Jiarui
authors.initials: J
authors.lastname: Zeng
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People's Republic of China.
authors.forename: Ting
authors.initials: T
authors.lastname: Xu
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People's Republic of China.
authors.forename: Xuanming
authors.initials: X
authors.lastname: Liu
authors.affiliation: Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People's Republic of China.
authors.forename: Yonghua
authors.identifier: 0000-0002-0252-9464
authors.initials: Y
authors.lastname: Zhu
keywords: Bacteria degradation system; Fenton chemistry; Lignocellulose degradation; Pantoea ananatis Sd-1; Rice straw