Microbial Stabilization and Kinetic Enhancement of Marine Methane Hydrates

Magnetic-Field Manipulation of Naturally Occurring Microbial Chiral Peptides to Regulate Gas-Hydrate Formation

“…Although it has been known for some time that some proteins (e.g., surfactin 4 ) can interact with methane hydrate, and affect its formation kinetics, it has not been clear if such proteins play a role naturally in marine-sediment environments; moreover, in marine sediments, particular materials (e.g., sand) are known to act as hydrate-formation heterogeneousnucleation sites, which may play a greater role in hydrate formation than microbial activity. Recent studies have shown that microorganism-produced proteins and polypeptides (such as an exported, extra-cytoplasmic porin-like protein from a marine methylotroph, GHP1), can accelerate methane-hydrate formation under seafloor-mimicking conditions 5,6 Independently, it was shown that magnetic-field effects can influence both the formation and stability of gas hydrates 7 . Bearing this in mind, this may well provoke the question of how applied magnetic fields might affect chiral systems, i.e., how magneto-chiral effects may dictate hydrate-formation mechanisms, and other important transitions and reactions in (bio-) physical chemistry in general?…”

“…The methylotroph-derived porin-like protein, GHP1, can be used to accelerate the rate of formation of gas hydrates using a possible approximation-catalysis mechanism 5 . This protein incorporates, in an exposed loop, an S-phenylalanine (PHE) moiety that we therefore speculate will interact sterically with an applied magnetic field.…”

“…Prior to testing our central hypothesis, we established the effect of an applied magnetic field on the rate of hydrate formation in the absence of peptides/proteins in a model system, shown previously to mimic the temperature and pressure of seafloor conditions in a case of substrate-limited catalytic turnover 5 . Here, we found that there was a measurable decline in the hydrate-formation rate in ~40 and ~95 mT fields (>90% H1-confidence on a singletailed Student's t-test)cf.…”

“…Table 1 in 'Methods'equivalent in molar concentration to the full protein in ref. 5) for its ability to catalyse methane-hydrate formation in variable applied magnetic-field configurations (see Fig. 1).…”

“…While a number of hypotheses have been presented to explain the origin of chirality in proteins [27][28][29][30][31][32] , through our findings we can suggest a site for the first appearance of pre-cellular life occurring at the energy-rich methane-hydrate boundarythat would certainly have been present in the methane-rich pre-biotic Earth 33,34 . Indeed, in terms of abiogenesis per se, using the 'chemical-reactor' concept, 35 it may be the case that "Cold(er)-Life" hypotheses, e.g., from carbon sources trapped in sea-ice molecular milieux (eutectic freezing) 36 or in the ocean's hydrothermal vents 37 may account for hydrate's possible involvement in terms of facilitating water-methane contact, quite possibly under biological regulation of hydrates (with GHP1 found in the TARA marine-metagenomic database 5 ).…”