Pressure adaptation is linked to thermal adaptation in salt‐saturated marine habitats

Abstract

SummaryThe present study provides a deeper view of protein functionality as a function of temperature, salt and pressure in deep-sea habitats. A set of eight different enzymes from five distinct deep-sea (3040-4908 m depth), moderately warm (14.0-16.5°C) biotopes, characterized by a wide range of salinities (39-348 practical salinity units), were investigated for this purpose. An enzyme from a 'superficial' marine hydrothermal habitat (65°C) was isolated and characterized for comparative purposes. We report here the first experimental evidence suggesting that in salt-saturated deepsea habitats, the adaptation to high pressure is linked to high thermal resistance (P value = 0.0036). Salinity might therefore increase the temperature window for enzyme activity, and possibly microbial growth, in deep-sea habitats. As an example, Lake Medee, the largest hypersaline deep-sea anoxic lake of the Eastern Mediterranean Sea, where the water temperature is never higher than 16°C, was shown to contain halopiezophilic-like enzymes that are most active at 70°C and with denaturing temperatures of 71.4°C. The determination of the crystal structures of five proteins revealed unknown molecular mechanisms involved in protein adaptation to polyextremes as well as distinct active site architectures and substrate preferences relative to other structurally characterized enzymes.

Identification and Characterization of Carboxyl Esterases of Gill Chamber-Associated Microbiota in the Deep-Sea Shrimp Rimicaris exoculata by Using Functional Metagenomics

“…If not otherwise stated, 1 mM pNP-propionate was used as the standard assay substrate for the determination of the conditions under which each enzyme displayed activity; pH values between 4.5 and 9.0 (at the optimal temperature), temperatures between 4 and 80°C (using 50 mM Tris-HCl buffer, pH 8.0), and NaCl, KCl, and MgCl 2 concentrations of up to 4 M (using 50 mM Tris-HCl buffer, pH 8.0, and optimal temperatures) were tested. The buffers used to determine the optimal pH for each enzyme have been described previously (3,27).…”

“…etagenomics provides a means for the discovery of entirely new enzymes in microorganisms and their communities without the need to culture these microorganisms as individual species, which is technically very difficult (1)(2)(3)(4)(5). Although the discovery of new enzyme activities has progressed considerably (6), it has not managed to go beyond the effective identification of enzymatic activities at a rather limited number of environmental sites.…”

“…Therefore, understanding the characteristics of other deep-sea enzymes, particularly esterases for which multiple biochemical data are available compared to other deep-sea enzymes (3), might help in understanding the phenomenon of protein versatility and adaptability to different polyextremes. Second, esterases were selected because they are ubiquitous enzymes that are widespread in nature (at least one per genome), multiple commercial preparations that are used at industrial scale are available, and biochemical data of such enzymes from a number of marine habitats (3,27,28) have been reported recently, which collectively may assist to perform an extensive comparative analysis. Finally, they are of great interest as biocatalysts for chemical synthesis (29).…”

A Novel Cold Active Esterase from a Deep Sea Sponge Stelletta normani Metagenomic Library

“…With mean depths of 3,800 m and 50% of the oceans being deeper than 3000 m, the "deep sea" constitutes not only a potential large resource from a microbial biodiversity perspective, but also a very unique environment; with temperatures ranging from 2 to 3 • C and a salinity of about 3.5% together with hundreds of bars of hydrostatic pressure (Wirsen and Molyneaux, 1999). Thus, microbial communities which have adapted to these extremes of temperature, salinity, pressure, and low levels of light are likely to possess novel biochemistry; and have enzymes that may be uniquely suited to many industrial processes (Alcaide et al, 2015a). In addition seawater samples are an extremely rich source of potential biocatalytic biodiversity when one considers that with bacteria capable of achieving densities of up to 10 6 per milliliter of seawater (Azam, 1998), and assuming that there are ∼3,000 genes in a single genome and that 40% of these genes have catalytic activity then there may be as many as 3 × 10 9 genes mediating up to 1·2 × 10 9 putative reactions in a milliliter of seawater (Dinsdale et al, 2008;Vieites et al, 2009).…”

Inter-comparison of the potentially active prokaryotic communities in the halocline sediments of Mediterranean deep-sea hypersaline basins

“…While new cell morphologies and ecophysiological traits have been assigned to some of these microorganisms, only recently a more specific picture of the metabolic activities of DHAB microorganisms has started to emerge, e.g. S--oxidizing chemolithotrophy, microaerophilic autotrophy, heterotrophic sulfate reduction, methanogenesis and anaerobic methane oxidation (Borin et al 2009;La Cono et al 2011;Ferrer et al 2012;Pachiadaki et al 2014;Yakimov et al 2013;Alcaide et al 2015). In spite of these recent advances, we still know little about how these microorganisms survive and grow under the prevailing conditions of the DHABs.…”