Dataset Information

Complete Genome Sequence of Geobacillus thermodenitrificans T12, A Potential Host for Biotechnological Applications.

ABSTRACT: In attempt to obtain a thermophilic host for the conversion of lignocellulose derived substrates into lactic acid, Geobacillus thermodenitrificans T12 was isolated from a compost heap. It was selected from over 500 isolates as a genetically tractable hemicellulolytic lactic acid producer, requiring little nutrients. The strain is able to ferment glucose and xylose simultaneously and can produce lactic acid from xylan, making it a potential host for biotechnological applications. The genome of strain T12 consists of a 3.64 Mb chromosome and two plasmids of 59 and 56 kb. It has a total of 3.676 genes with an average genomic GC content of 48.7%. The T12 genome encodes a denitrification pathway, allowing for anaerobic respiration. The identity and localization of the responsible genes are similar to those of the denitrification pathways found in strain NG80-2. The hemicellulose utilization (HUS) locus was identified based on sequence homology against G. stearothermophilus T-6. It appeared that T12 has all the genes that are present in strain T-6 except for the arabinan degradation cluster. Instead, the HUS locus of strain T12 contains genes for both an inositol and a pectate degradation pathway. Strain T12 has complete pathways for the synthesis of purine and pyrimidine, all 20 amino acids and several vitamins except D-biotin. The host-defense systems present comprise a Type II and a Type III restriction-modification system, as well as a CRISPR-Cas Type II system. It is concluded that G. thermodenitrificans T12 is a potentially interesting candidate for industrial applications.

SUBMITTER: Daas MJA

PROVIDER: S-EPMC5765199 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Complete Genome Sequence of Geobacillus thermodenitrificans T12, A Potential Host for Biotechnological Applications.

Daas Martinus J A MJA Vriesendorp Bastienne B van de Weijer Antonius H P AHP van der Oost John J van Kranenburg Richard R

Current microbiology 20170912 1

In attempt to obtain a thermophilic host for the conversion of lignocellulose derived substrates into lactic acid, Geobacillus thermodenitrificans T12 was isolated from a compost heap. It was selected from over 500 isolates as a genetically tractable hemicellulolytic lactic acid producer, requiring little nutrients. The strain is able to ferment glucose and xylose simultaneously and can produce lactic acid from xylan, making it a potential host for biotechnological applications. The genome of st ...[more]

PMID: 28900693

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Project description:BACKGROUND:Endo-xylanases are essential in degrading hemicellulose of various lignocellulosic substrates. Hemicellulose degradation by Geobacillus spp. is facilitated by the hemicellulose utilization (HUS) locus that is present in most strains belonging to this genus. As part of the HUS locus, the xynA gene encoding an extracellular endo-xylanase is one of the few secreted enzymes and considered to be the key enzyme to initiate hemicellulose degradation. Several Geobacillus endo-xylanases have been characterized for their optimum temperature, optimum pH and generation of degradation products. However, these analyses provide limited details on the mode of action of the enzymes towards various substrates resulting in a lack of understanding about their hydrolytic potential. RESULTS:A HUS-locus associated gene (GtxynA1) from the thermophile Geobacillus thermodenitrificans T12 encodes an extracellular endo-xylanase that belongs to the family 10 glycoside hydrolases (GH10). The GtxynA1 gene was cloned and expressed in Escherichia coli. The resulting endo-xylanase (termed GtXynA1) was purified to homogeneity and showed activity between 40 °C and 80 °C, with an optimum activity at 60 °C, while being active between pH 3.0 to 9.0 with an optimum at pH 6.0. Its thermal stability was high and GtXynA1 showed 85% residual activity after 1 h of incubation at 60 °C. Highest activity was towards wheat arabinoxylan (WAX), beechwood xylan (BeWX) and birchwood xylan (BiWX). GtXynA1 is able to degrade WAX and BeWX producing mainly xylobiose and xylotriose. To determine its mode of action, we compared the hydrolysis products generated by GtXynA1 with those from the well-characterized GH10 endo-xylanase produced from Aspergillus awamori (AaXynA). The main difference in the mode of action between GtXynA1 and AaXynA on WAX is that GtXynA1 is less hindered by arabinosyl substituents and can therefore release shorter oligosaccharides. CONCLUSIONS:The G. thermodenitrificans T12 endo-xylanase, GtXynA1, shows temperature tolerance up to 80 °C and high activity to a variety of xylans. The mode of action of GtXynA1 reveals that arabinose substituents do not hamper substrate degradation by GtXynA1. The extensive hydrolysis of branched xylans makes this enzyme particularly suited for the conversion of a broad range of lignocellulosic substrates.

Dataset Information

Complete Genome Sequence of Geobacillus thermodenitrificans T12, A Potential Host for Biotechnological Applications.

Publications

Complete Genome Sequence of Geobacillus thermodenitrificans T12, A Potential Host for Biotechnological Applications.

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