The Santorini Volcanic Complex as a Valuable Source of Enzymes for Bioenergy

Paraskevi N Polymenakou,Antoniοs Magoulas,Paraskevi Nomikou,Thekla I Anastasiou,Haris Zafeiropoulos,Stephanos Kilias,Manolis Mandalakis,Nikos C Kyrpides,Georgios Kotoulas

doi:10.3390/en14051414

Abstract

Marine microbial communities are an untapped reservoir of genetic and metabolic diversity and a valuable source for the discovery of new natural products of biotechnological interest. The newly discovered hydrothermal vent field of Santorini volcanic complex located in the Aegean Sea is gaining increasing interest for potential biotechnological exploitation. The conditions in these environments, i.e., high temperatures, low pH values and high concentration of heavy metals, often resemble harsh industrial settings. Thus, these environments may serve as pools of enzymes of enhanced catalytic properties that may provide benefits to biotechnology. Here, we screened 11 metagenomic libraries previously constructed from microbial mat samples covering the seafloor and the polymetallic chimneys of Kolumbo volcano as well as mat samples from Santorini caldera, to mine, in silico, genes associated with bioenergy applications. We particularly focused on genes encoding biomass hydrolysis enzymes such as cellulases, hemicellulases and lignin-degrading enzymes. A total of 10,417 genes were found for three specific groups of enzymes—i.e., the endoglucanases, the three different beta-glucosidases BGL, bglX and bglB, and the alpha-galactosidases melA, and rafA. Overall, we concluded that the Santorini–Kolumbo volcanic ecosystems constitute a significant resource of novel genes with potential applications in bioenergy that deserve further investigation.

Highlights

Among all different extreme habitats that can be found on Earth, marine hydrothermal vents (HVs) represent the very promising targets for the discovery of some of the Earth’s oddest and toughest microbes
Through the enormous amount of metagenomic data being produced from a wide range of different environments, we can develop a better understanding of how to effectively harness various renewable energy sources [34]
We explored the genetic content of 11 large metagenomic libraries previously developed from the extreme environments of the Santorini–Kolumbo volcanic complex in the context of bioenergy

Summary

Introduction

Among all different extreme habitats that can be found on Earth, marine hydrothermal vents (HVs) represent the very promising targets for the discovery of some of the Earth’s oddest and toughest microbes. These microbes have an enormous potential in the so called “blue biotechnology”—i.e., the area of biotechnology which exploits the diversity of marine organisms [1,2]. Despite the vital role of microorganisms in HV ecosystems, and their exploitation potential in biotechnology, key questions about their ecology, diversity and metabolic capabilities remain understudied because many HV environments remain largely unexplored [5]. Due to the challenges in accessing samples, they are among the least understood ecosystems on

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