Abstract
Crystals, rocks and mineral ores of different origins contain viable microbial life that appears actively swimming under the microscope when the sample is properly fragmented and suspended in a nutrient medium. This form of life in rocks is unaffected by time, since microbes have been found in samples of all geological ages, from about 2.8 Ga to recent rocks, and by pressure and temperature, since it is present in metamorphic and in igneous rocks. From the tests performed, among which those to secure from sample pollution, it emerges that this form of life is not destroyed, as indeed expected, when the rock is heated above 500 °C in a kiln. However, all cloned microbes are sensitive to growth inhibition by specific antibiotics. A similar search, for the presence of microbes in meteorites, shows that also these materials are rich in microorganisms, indicating that these already existed in early Earth formation stages. Some different microbial species, derived from different samples of rocks and meteorites, have been cultured, cloned and classified by 16S rDNA typing and found to be not essentially different from present day organisms. An interesting consequence of these findings, among others, is the support to the hypothesis that life came from outside Earth with the additional indication that it was already present in those materials that accreted to form the solar planetary system.
Riassunto
Cristalli, rocce e minerali di diversa origine contengono microrganismi vitali che si osservano nuotare attivamente al microscopio quando il campione solido è frammentato in modo appropriato, raccolto su un vetrino portaoggetti e sospeso in un mezzo nutriente. Questa forma di vita, quando è all’interno della roccia, non è influenzata dal tempo, perché sono stati trovati microrganismi vitali e coltivabili in campioni di diverse età, a partire da circa 2.8 Ga a rocce recenti, e dalla temperatura e pressione, perché è presente in rocce metamorfiche e in rocce ignee. In alcune prove, fra le molte fatte per assicurarsi da possibili contaminazioni, è risultato che questa forma di vita non è distrutta, come ci si sarebbe effettivamente aspettato, quando la roccia è riscaldata al di sopra di 500 °C in un forno per ceramica, mentre tutte le specie clonate non crescono in presenza di antibiotici specifici. La ricerca con lo stesso approccio di forme microbiche in meteoriti ha mostrato che esse sono ricche in microrganismi, indicando che questi già esistevano durante i primi stadi di formazione della Terra. Alcune specie microbiche, derivate da campioni di rocce e di meteoriti, sono state ottenute in coltura, clonate e classificate con il metodo della tipizzazione del 16S rDNA e sono risultate non dissimili dai microrganismi attuali. Questi risultati avvalorano l’ipotesi che la vita sia venuta dall’esterno della Terra e suggeriscono che fosse già presente nei materiali che, condensandosi, hanno generato i pianeti del sistema solare.
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Nella seduta dell’11 maggio 2001.
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D’Argenio, B., Geraci, G. & del Gaudio, R. Microbes in rocks and meteorites: a new form of life unaffected by time, temperature, pressure. Rend. Fis. Acc. Lincei 12, 51–68 (2001). https://doi.org/10.1007/BF02904521
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DOI: https://doi.org/10.1007/BF02904521