Li Xiao-Ju, Wang Tian-Qi, Qi Lu, Li Feng-Wei, Xia Yong-Zhen, Zhang Cheng-Jia, Chen Lin-Xu, Lin Jian-Qun
State Key Laboratory of Microbial Technology, Shandong University Qingdao 266237 China
Science Center for Material Creation and Energy Conversion, Institute of Frontier and Interdisciplinary Science, Shandong University Qingdao 266237 China.
RSC Chem Biol. 2024 Dec 20;6(2):281-294. doi: 10.1039/d4cb00195h. eCollection 2025 Feb 5.
Microorganisms serve as biological factories for the synthesis of nanomaterials such as CdS quantum dots. Based on the uniqueness of sp., a one-step route was explored to directly convert cadmium waste into CdS QDs using these bacteria. First, an exhaustive study was conducted to reveal the specific pathways involved in the biosynthesis of CdS QDs. The widely known homologous enzyme, cysteine desulfhydrase, which catalyzes the synthesis of CdS QDs from a cysteine substrate, is also present in sp. and is referred to as the OSH enzyme. The structure of the OSH enzyme was determined through X-ray crystallography. Moreover, we identified two new pathways. One involved the SQR enzyme in sp., which catalyzed the formation of sulfur globules and subsequently catalyzed further reactions with GSH to release HS; subsequently, a CdS QD biosynthesis pathway was successfully constructed. The other pathway involved extracellular polyphosphate, a bacterial metabolic product, which with the addition of GSH and Cd, resulted in the formation of water-soluble fluorescent CdS QDs in the supernatant. Based on the above-described mechanism, after the bioleaching of Cd from cadmium waste by sp., CdS QDs were directly obtained from the bacterial culture supernatants. This work provides important insights into cleaner production and cadmium bioremediation with potential industrial applications.
微生物可作为合成硫化镉量子点等纳米材料的生物工厂。基于特定菌种的独特性，探索了一种一步法路线，利用这些细菌将镉废料直接转化为硫化镉量子点。首先，进行了详尽研究以揭示参与硫化镉量子点生物合成的具体途径。广为人知的同源酶——半胱氨酸脱硫酶，可催化由半胱氨酸底物合成硫化镉量子点，在特定菌种中也存在，被称为OSH酶。通过X射线晶体学确定了OSH酶的结构。此外，我们还发现了两条新途径。一条途径涉及特定菌种中的SQR酶，它催化硫球的形成，随后催化与谷胱甘肽的进一步反应以释放HS；随后成功构建了一条硫化镉量子点生物合成途径。另一条途径涉及细菌代谢产物细胞外多聚磷酸盐，其与谷胱甘肽和镉一起，导致在上清液中形成水溶性荧光硫化镉量子点。基于上述机制，特定菌种对镉废料进行生物浸出后，可直接从细菌培养上清液中获得硫化镉量子点。这项工作为清洁生产和镉生物修复提供了重要见解，具有潜在的工业应用价值。
