Abstract

Extremophiles provide a one-of-a-kind source of enzymes with properties that allow them to endure the rigorous industrial conversion of lignocellulose biomass into fermentable sugars. However, the fact that most of these organisms fail to grow under typical culture conditions limits the accessibility to these enzymes. In this study, we employed a functional metagenomics approach to identify carbohydrate-degrading enzymes from Ethiopian soda lakes, which are extreme environments harboring a high microbial diversity. Out of 21,000 clones screened for the five carbohydrate hydrolyzing enzymes, 408 clones were found positive. Cellulase and amylase, gave high hit ratio of 1:75 and 1:280, respectively. A total of 378 genes involved in the degradation of complex carbohydrates were identified by combining high-throughput sequencing of 22 selected clones and bioinformatics analysis using a customized workflow. Around 41% of the annotated genes belonged to the Glycoside Hydrolases (GH). Multiple GHs were identified, indicating the potential to discover novel CAZymes useful for the enzymatic degradation of lignocellulose biomass from the Ethiopian soda Lakes. More than 73% of the annotated GH genes were linked to bacterial origins, with Halomonas as the most likely source. Biochemical characterization of the three enzymes from the selected clones (amylase, cellulase, and pectinase) showed that they are active in elevated temperatures, high pH, and high salt concentrations. These properties strongly indicate that the evaluated enzymes have the potential to be used for applications in various industrial processes, particularly in biorefinery for lignocellulose biomass conversion.

Keywords

extremophiles; glycoside hydrolases; lignocellulose biomass; halophiles; soda lakes; CAZymes; functional metagenomics

Published in

Frontiers in Microbiology
2022, Volume: 13, article number: 1059061
Publisher: FRONTIERS MEDIA SA

SLU Authors

• Oumer, Oliyad Jeilu

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    
  • Addis Ababa University

• Alexandersson, Erik

  • Department of Plant Protection Biology, Swedish University of Agricultural Sciences
    

• Johansson, Eva

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Microbiology
Biocatalysis and Enzyme Technology


Publication identifier

DOI: https://doi.org/10.3389/fmicb.2022.1059061

Permanent link to this page (URI)

https://res.slu.se/id/publ/120571