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Pyrite and the Origin of Life Pyrite Crystallites Comprising the Interior of These Framboids Are About 0.1 F.Lill SIR-R

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Pyrite and the Origin of Life Pyrite Crystallites Comprising the Interior of These Framboids Are About 0.1 F.Lill SIR-R SCIENTIFIC CORRESPONDENCE spherical shell of iron sulphide gel. The Pyrite and the origin of life pyrite crystallites comprising the interior of these framboids are about 0.1 f.lill SIR-R. J.P. Williams in his recent News autocatalytic surface metabolism'·•. across, and so are similar in size to those and Views article 1 raises among other Another of his predictions (also possibly found in the magnetotactic bacteria. problems the following: " ... we must supported by Farina et al.' and Mann et In a hydrothermal chimney, the iron search for the functional advantage for the al. ') implies that the surfaces of biogenic sulphide shells would initially have con­ material [such as FeS2] in the biological pyrite are binding, in statu nascendi, mem­ sisted of periodic arrays of iron mono­ niche in which it is synthesized". A branes of lipids and of antonic peptides', a sulphide crystallites, which would have detailed hypothetical answer to this prob­ hypothesis which could explain the grown by the diffusion of iron from an lem, as far as pyrite is concerned, is central otherwise still unexplained asymmetry in aqueous phase into polysulphide droplets. to the recent theories of the origin of life the structure of the membranes. These shells would have provided a site due to G. Wachtershauser. The answer is These hints may, I hope, draw attention for concentration of polar organic species, formulated in the title of the first of his to a new theory - to my knowledge, the by adsorption onto the iron sulphide papers on the origin of life: "Pyrite For­ first radical alternative to Haldane's and surfaces. mation, the First Energy Source for Life: a Oparin's soup theory. A workable alter­ Once a critical concentration of polar Hypothesis"' . native seems to me urgently needed, organics had been adsorbed, further In this paper, Wachtershauser notes especially in view of the low temperature growth of the iron sulphides would have that certain anaerobic bacteria combine of the soup required by the most promi­ been inhibited. Then the organics could archaic features with a chemoautotrophic nent representatives of the theory'. This become inherently ordered to a liquid metabolism. Starting from this observa­ temperature requirement seems to me crystalline structure. The periodic arrays tion, he recommends "the re-examination contradicted by the logic of the geo­ of the iron sulphide crystallites may have of the long neglected view that the origin physical situation as well as by the assisted this ordering, developing an of life and the origin of [chemo-]auto­ empirical findings of Woese: both suggest organic layer with varied degrees of struc­ trophic metabolisms coincide" - in a hot origin of life (with which Wachter­ ture similar to those reported by contrast with the widely adopted hetero­ shauser's theory is compatible). Inciden­ McConnell et al. 5 in phospholipid trophic soup theory, and also with the tally, Weese's hot origin hypothesis membranes. A further concentration of view that the original metabolism is appears to render sterile all those specula­ organics onto the first adsorbed layer photoautotrophic. tions about hot-temperature sterilization, could follow , the whole comprising a cell Wachtershauser suggests that the due perhaps to the impact of meteorites. membrane precursor. neglect of the chemoautotrophic option K. R. POPPER Similarities between the iron sulphide results from the problem of finding a likely 136 Welcomes Road, bearing bacteria and the earliest stages of energy source. He proposes the anaerobic Kenley, framboidal iron sulphides give further biomineralization of pyrite as the first Surrey CR2 5HH, UK support for the view that inorganic and energy source for life, calculating the yield 1. Williams, J.R.P. Nature343. 213-214 (1990). organic evolution to the earliest life forms of free energy from this process. (More 2. Wachtershiiuser, G. System. appl. Microbial. 10, 207- relied on a redox reaction involving carbon 210 (1988). fixation concomitant with the oxidation of recently, upon a suggestion by Ian R. 3. Farina, M. eta!. Nature343, 256-258 (1990). Kaplan, he has also calculated the still 4. Mann, S. eta/. Nature343, 258-261 (1990). iron monosulphide to disulphide. more highly exergonic formation of pyrite 5. Wiichtershauser, G. Microb. Rev. 52, 452-484 (1988). M. J . RUSSELL 6 . Wachtershauser, G. Proc. natn. Acad. Sci. U.S.A . 87, when Fe3S4 intervenes.) 200-204 (1990). A. J. HALL This hypothesis suggested further 7. Miller, S.L. & Bada , J.L. Nature334, 609-611 (1988). Department of Geology and Applied hypotheses of great explanatory and pre­ Geology, dictive power covering precellular life and SIR-Wiichtershauser12 has described University of Glasgow, the formation of cells. These hypotheses how the exergonic formation of pyrite Glasgow G12 BQQ, UK enabled Wachtershauser to predict that (FeS,) could have been the electron­ A. P. GIZE the production of pyrite via carbon fix­ donating energy source for an autotrophic Department of Geology, ation (in competition with hydrogen origin of life. Early Archaean submarine University of Manchester, formation) by some of the extant archaic hot springs of moderate (100-200 oq Manchester M13 9PL, UK 6 bacteria is highly probable'· • Possible temperature may have issued through fine 1. Wachtershiiuser, G. System. appl. Microbial. 10. 207- corroborations of this prediction seem to iron monosulphide tubes comprising 210 (1988). be offered by the two recent letters to natural chemical gardens- catalytic flow 2. Wachtershauser, G. Microbial. Rev. 52, 452- 484 (1988). 1 3. Russell , M.J., Hall, A.J . & Turner, D. Terra Nova 1 , 238- Nature'"' discussed by Williams • reactors in which the first metabolists 241 (1989). Another prediction of central import­ could have been cultured'. Hallet al.' have 4. Hall. D.O., Cammack, R. & Rao , K.K. Nature 233. 136- ance to Wachtershauser's theory is the also argued for an ancient origin of ferre­ 138 (1971). 5. McConnell, H.M. , Tamm. L.K. & Weis, R.M. Proc. natn. evolution of precellular forms of life doxins, the iron-sulphur-proteins that Acad. Sci. U.S.A. 81, 3249- 3253 (1984). (surface metabolists); that is , of mono­ occur in all types of organisms, which are molecular layers of autocatalytic processes involved in a wide range of biochemical of carbon fixation, bound, in statu reactions as agents for electron transfer, Geomorphology nascendi, to positively charged mineral but which originally catalysed anaerobic surfaces such as pyrite crystals that are fermentation' . and mantle plumes biomineralized by the surface metabolists We suggest one more important role for SIR-The recent article by Cox1 is valu­ themselves''·'. This prediction shows a iron sulphide, that of nucleating the mem­ able in highlighting the potential signifi­ striking similarity with Williams's brane of the earliest cell walls. We have cance of geomorphic data in assessing suggestions that the "surfaces of iron demonstrated that iron monosulphide gels models of continental rifting and asso­ sulphide minerals could also have been can form macroscopic spherical shells 1 to ciated surface uplift. In his analysis of the catalysts [for the metabolism]". 20 mm across'. On a microscopic scale, geomorphic evidence for the plume-related Indeed, Wachtershauser points out that spherical aggregates of pyrite about 5 f.tm surface uplift model proposed by White his surface metabolists act as catalysts for in diameter are found within fossil hydro­ and McKenzie' , there are, however, the biomineralization of pyrite, whereas thermal chimneys. These framboids important elements that permit well the pyrite surfaces act as catalysts for the appear to have grown inorganically from a supported alternative interpretations. NATURE · VOL 344 · 29 MARCH 1990 387 .
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