Supplementary file 1_Harnessing cosmic carbon: anaerobic microbial responses to fullerenes under early Earth conditions.docx

Fullerenes of extra-terrestrial origin may have been accessible as carbon sources for anaerobic microorganisms on the early Earth. Very little is known about how anaerobic microorganisms respond to and use fullerenes and their soluble derivatives. We present an investigation into the effects of fullerenes C60 and C70 and their hydroxylated fullerol derivatives on an environmentally relevant anaerobic community and a microbial isolate. Fullerenes and fullerols irradiated with 254 nm UV radiation for 2 weeks in the absence of oxygen to simulate UV irradiation under anoxia on early Earth were also assessed. The anaerobic community could grow using glucose in the presence of C60 up to 500 mg/mL without inhibitory effects on growth. Concentrations of C70 of 500 mg/ml were inhibitory. We attribute these results to the different chemical reactivity and photophysical properties of the fullerenes. The experiments suggest the potential for the use of C60 as a sole carbon source. Both C60 and C70 fullerols were inhibitory to growth in the presence of glucose, especially when exposed to light. When we exposed C60 fullerol suspensions to 254 nm UV radiation under an anoxic atmosphere, they become significantly more inhibitory to both the community and the isolate, but only if the cultures are grown under ambient light exposure. The anaerobic isolate was unable to grow on C60 alone, but after UV radiation exposure, the C60 photodegradation products served as a potentially accessible carbon source. Our data show that fullerenes and their derivatives are biologically active and capable of influencing growth in anoxic environments such as those that would have been prevalent on early Earth or in modern-day anoxic soils. Our results show that carbon sources such as these can be both beneficial or deleterious to life depending on their concentrations and environmental processing.

地外起源的富勒烯（fullerenes）或许可作为早期地球厌氧微生物可利用的碳源。目前学界对厌氧微生物如何响应并利用富勒烯及其可溶性衍生物的认知仍十分有限。本研究针对富勒烯C60、C70及其羟基化富勒醇（hydroxylated fullerol）衍生物对环境相关厌氧菌群及微生物分离株的影响展开调查，同时评估了在无氧条件下经254 nm紫外辐射2周、以模拟早期地球缺氧环境下紫外照射的富勒烯与富勒醇样品。该厌氧菌群可在葡萄糖存在且C60浓度高达500 mg/mL的条件下生长，未出现生长抑制现象；而当C70浓度达到500 mg/mL时则会产生抑制作用，我们将这一结果归因于两种富勒烯不同的化学反应活性与光物理性质。实验结果表明，C60具备作为唯一碳源的潜在应用价值。无论是C60还是C70富勒醇，在葡萄糖存在时均会抑制微生物生长，经光照处理后抑制效果尤为显著。当我们在无氧气氛下将C60富勒醇悬浮液暴露于254 nm紫外辐射后，其对厌氧菌群与微生物分离株的抑制作用显著增强，但该效应仅在培养物于常光条件下培养时才会显现。该厌氧微生物分离株无法仅以C60作为碳源生长，但经紫外辐射后的C60光降解产物可作为潜在可利用的碳源。本研究数据表明，富勒烯及其衍生物具有生物活性，能够影响缺氧环境中的微生物生长——这类环境曾广泛存在于早期地球，或对应现代无氧土壤的特征。研究结果显示，此类碳源对生命的影响兼具利弊，具体取决于其浓度与环境处理过程。