Evidence for fungi and gold redox interaction under Earth surface conditions

Tsing Bohu,Ravi Anand,Yuan Mei,Mike Verrall,Matthew Power,Ryan Noble,Mel Lintern,Xiao Deng,Jean-Pierre Veder,Anna H Kaksonen,Michael Bunce,Ka Yu Cheng

doi:10.1038/s41467-019-10006-5

Abstract

Microbial contribution to gold biogeochemical cycling has been proposed. However, studies have focused primarily on the influence of prokaryotes on gold reduction and precipitation through a detoxification-oriented mechanism. Here we show, fungi, a major driver of mineral bioweathering, can initiate gold oxidation under Earth surface conditions, which is of significance for dissolved gold species formation and distribution. Presence of the gold-oxidizing fungus TA_pink1, an isolate of Fusarium oxysporum, suggests fungi have the potential to substantially impact gold biogeochemical cycling. Our data further reveal that indigenous fungal diversity positively correlates with in situ gold concentrations. Hypocreales, the order of the gold-oxidizing fungus, show the highest centrality in the fungal microbiome of the auriferous environment. Therefore, we argue that the redox interaction between fungi and gold is critical and should be considered in gold biogeochemical cycling.

Highlights

Microbial contribution to gold biogeochemical cycling has been proposed
In the Golden Triangle Gold Prospect, a 300 m by 100 m secondary gold deposit occurs in the lower part of the aluminum-rich zone and above primary mineralization hosted in volcanic rocks
In the fungal microcosm GA6F+cs containing the gold anomalous soil spiked with metallic gold (Fig. 2a), the maximum Au(III) concentration occurred at 119 h and corresponded to about 33.6% of the total gold weight in the microcosm, whereas the sterilized control GA6I showed no increase in Au(III) after the initial period (Fig. 2c)

Summary

Introduction

Microbial contribution to gold biogeochemical cycling has been proposed. studies have focused primarily on the influence of prokaryotes on gold reduction and precipitation through a detoxification-oriented mechanism. Fungi, a major driver of mineral bioweathering, can initiate gold oxidation under Earth surface conditions, which is of significance for dissolved gold species formation and distribution. Prokaryotic gold biogeochemical cycling has been proposed and suggests that through bioweathering and oxidative complexation, bacteria and archaea can liberate gold from minerals to form dissolved gold species[8]. Fungi are ideal to simultaneously produce oxidants, e.g., reactive oxygen species[18], and ligands, e.g., organic acids[19], thiosulfate[20], and cyanide[21]. These coordinating molecules serve as exogenous electron donors to active fungal extracellular oxidation-reduction systems[22], thereby potentially facilitating colloidal gold redox transformation

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Results

Conclusion