College of Civil Engineering, Fuzhou University, Fuzhou 350116, China.
Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
Sci Total Environ. 2022 Apr 20;818:151672. doi: 10.1016/j.scitotenv.2021.151672. Epub 2021 Nov 15.
Azo dyes in wastewater have great threats to environment and human health. White-rot fungi (WRF) have broad-spectrum potential for such refractory organics bioremediation; however, their applications are largely restrained by the poor viability owning to microbial invasion under non-sterile conditions. In this study, short-term pre-exposure to silver ion (Ag) was demonstrated to be a practical, economic, and green method to enhance the perdurability of azo dyes decoloration by WRF Phanerochaete chrysosporium under non-sterile conditions. In control (without Ag pre-exposure), decoloration deactivated since cycle 7 (<10%), whereas in Ag pre-exposure groups, the decoloration ratios remained 91.5%-94.7% after 7 cycles. Variations in decoloration-related extracellular lignin enzyme activities were consistent with the decoloration effectiveness. The enhanced decoloration capability in Ag pre-exposure groups under non-sterile conditions could be ascribed to the selectively antimicrobial action by Ag. The released Ag from the self-assembled silver nanoparticles (AgNPs) could selectively "stimulate" the proliferation and viability of P. chrysosporium, and simultaneously inhibit the growths of invasive microorganisms. The pyrosequencing results indicated that genus Sphingomonas (24.1%-31.3%) was the main invasive bacteria in Ag pre-exposure groups after long-term operation owing to the AgNPs passivation. As control, the invasive fungi (Asterotremella humicola) and bacteria (Burkholderia spp.) occurred in control after short-term operation, and genus Burkholderia (74.9%) dominated after long-term operation, leading to decoloration deactivation. Overall, these findings offer a new insight into the bio-nano interactions between WRF and invasive microorganisms in response to Ag or biogenic AgNPs, and could extend WRF application perspective under non-sterile conditions in future.
偶氮染料在废水中对环境和人类健康有很大的威胁。白腐真菌（WRF）具有广谱的潜在能力，可以对这种难处理的有机污染物进行生物修复；然而，由于在非无菌条件下微生物的入侵，它们的应用受到很大限制。在这项研究中，证明了短期预暴露于银离子（Ag）是一种实用、经济和绿色的方法，可以增强白腐真菌糙皮侧耳在非无菌条件下对偶氮染料脱色的耐久性。在对照（无 Ag 预暴露）中，脱色活性在第 7 个周期后就下降到<10%，而在 Ag 预暴露组中，经过 7 个周期后，脱色率仍保持在 91.5%-94.7%。与脱色效果相关的胞外木质素酶活性的变化与脱色效果一致。在非无菌条件下，Ag 预暴露组增强的脱色能力可以归因于 Ag 的选择性抗菌作用。自组装的银纳米粒子（AgNPs）中释放的 Ag 可以选择性地“刺激”糙皮侧耳的增殖和活力，同时抑制入侵微生物的生长。焦磷酸测序结果表明，由于 AgNPs 的钝化作用，属 Sphingomonas（24.1%-31.3%）在长期运行后成为 Ag 预暴露组中的主要入侵细菌。作为对照，在短期运行后，入侵真菌（Asterotremella humicola）和细菌（伯克霍尔德菌属）在对照中出现，而属伯克霍尔德菌（74.9%）在长期运行后占主导地位，导致脱色失活。总的来说，这些发现为白腐真菌与入侵微生物在应对 Ag 或生物源 AgNPs 时的生物-纳米相互作用提供了新的见解，并为未来在非无菌条件下扩展白腐真菌的应用前景提供了参考。
