Genomic and secretomic insight into lignocellulolytic system of an endophytic bacterium Pantoea ananatis Sd-1
Date
2016
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central
Abstract
Background: Exploring microorganisms especially bacteria associated with the degradation of lignocellulosic biomass
shows great potentials in biofuels production. The rice endophytic bacterium Pantoea ananatis Sd-1 with strong
lignocellulose degradation capacity has been reported in our previous study. However, a comprehensive analysis of
its corresponding degradative system has not yet been conducted. The aim of this work is to identify and characterize
the lignocellulolytic enzymes of the bacterium to understand its mechanism of lignocellulose degradation and
facilitate its application in sustainable energy production.
Results: The genomic analysis revealed that there are 154 genes encoding putative carbohydrate-active enzymes
(CAZy) in P. ananatis Sd-1. This number is higher than that of compared cellulolytic and ligninolytic bacteria as well as
other eight P. ananatis strains. The CAZy in P. ananatis Sd-1 contains a complete repertoire of enzymes required for cellulose
and hemicellulose degradation. In addition, P. ananatis Sd-1 also possesses plenty of genes encoding potential
ligninolytic relevant enzymes, such as multicopper oxidase, catalase/hydroperoxidase, glutathione S-transferase, and
quinone oxidoreductase. Quantitative real-time PCR analysis of parts of genes encoding lignocellulolytic enzymes
revealed that they were significantly up-regulated (at least P < 0.05) in presence of rice straw. Further identification
of secretome of P. ananatis Sd-1 by nano liquid chromatography–tandem mass spectrometry confirmed that considerable
amounts of proteins involved in lignocellulose degradation were only detected in rice straw cultures. Rice
straw saccharification levels by the secretome of P. ananatis Sd-1 reached 129.11 ± 2.7 mg/gds. Correspondingly,
the assay of several lignocellulolytic enzymes including endoglucanase, exoglucanase, β-glucosidase, xylanase-like,
lignin peroxidase-like, and laccase-like activities showed that these enzymes were more active in rice straw relative to
glucose substrates. The high enzymes activities were not attributed to bacterial cell densities but to the difference of
secreted protein contents.
Conclusion: Our results indicate that P. ananatis Sd-1 can produce considerable lignocellulolytic enzymes including
cellulases, hemicellulases, and ligninolytic relevant enzymes. The high activities of those enzymes could be efficiently
induced by lignocellulosic biomass. This identified degradative system is valuable for the lignocellulosic bioenergy
industry.
Description
CITATION: Ma, J., et al. 2016. Genomic and secretomic insight into lignocellulolytic system of an endophytic bacterium Pantoea ananatis Sd-1. Biotechnol Biofuels, 9:25, doi:10.1186/s13068-016-0439-8.
The original publication is available at http://biotechnologyforbiofuels.biomedcentral.com
The original publication is available at http://biotechnologyforbiofuels.biomedcentral.com
Keywords
Endophytic bacterium, Pantoea ananatis, Lignocellulolytic system enzyme -- Characterisation
Citation
Ma, J., et al. 2016. Genomic and secretomic insight into lignocellulolytic system of an endophytic bacterium Pantoea ananatis Sd-1. Biotechnol Biofuels, 9:25, doi:10.1186/s13068-016-0439-8