Published September 7, 2014 | Version v1
Journal article Open

The environment shapes microbial enzymes: five cold-active and salt-resistant carboxylesterases from marine metagenomes

  • 1. . Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, M5S 3E5, Canada
  • 2. Institute of Molecular Enzyme Technology, Heinrich-Heine-University Duesseldorf, Forschungszentrum Juelich, 52426, Juelich, Germany
  • 3. School of Biological Sciences, Bangor University, Gwynedd, LL57 2UW, UK
  • 4. Institute for Coastal Marine Environment, CNR, 98122, Messina, Italy
  • 5. . Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, M5S 3E5, Canada , School of Biological Sciences, Bangor University, Gwynedd, LL57 2UW, UK

Description

Most of the Earth’s biosphere is cold and is populated by cold-adapted microorganisms. To explore the natural enzyme diversity of these environments and identify new carboxylesterases, we have screened three marine metagenome gene libraries for esterase activity. The screens identified 23 unique active clones, from which five highly active esterases were selected for biochemical characterization. The purified metagenomic esterases exhibited high activity against α-naphthyl and p-nitrophenyl esters with different chain lengths. All five esterases retained high activity at 5 °C indicating that they are cold-adapted enzymes. The activity of MGS0010 increased more than two times in the presence of up to 3.5 M NaCl or KCl, whereas the other four metagenomic esterases were inhibited to various degrees by these salts. The purified enzymes showed different sensitivities to inhibition by solvents and detergents, and the activities of MGS0010, MGS0105 and MGS0109 were stimulated three to five times by the addition of glycerol. Screening of purified esterases against 89 monoester substrates revealed broad substrate profiles with a preference for different esters. The metagenomic esterases also hydrolyzed several polyester substrates including polylactic acid suggesting that they can be used for polyester depolymerization. Thus, esterases from marine metagenomes are cold-adapted enzymes exhibiting broad biochemical diversity reflecting the environmental conditions where they evolved.

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Funding

MICRO B3 – Marine Microbial Biodiversity, Bioinformatics and Biotechnology 287589
European Commission