Microbial reduction is a sustainable approach for both environmental remediation and recycling of precious metals from waste. Bacteria-mediated reduction of palladium ions (Pd²⁺) in wastewater under mild conditions is such a strategy. However, external electron donors are usually required for palladium bioreduction. Herein, a novel gram-positive bacterium, Bacillus thuringiensis Y9 (B. thuringiensis Y9), was found to reduce Pd²⁺ to palladium nanoparticles (Pd-NPs) with endogenous electron donors. Transcriptomic analyses revealed 443 and 439 differentially expressed genes response to palladium treatment under anaerobic and aerobic conditions, respectively. It was found the genes encoding NADH-quinone oxidoreductase, dehydrogenases, cytochrome c reductase, cytochrome c oxidase, quinone cycle and ribE in B. thuringiensis Y9 have strong positive relationship to palladium reduction. The removal efficiencies of palladium by B. thuringiensis Y9 are as high as 93 mg g⁻¹ under anaerobic conditions and 60 mg g⁻¹ under aerobic conditions. Hydrogenase also plays vital role in the bioreduction process. The maximum Pd removal ratio of 99.18% was obtained with the primary influencing factors using response surface methodology (RSM). Our study provides a novel and sustainable strategy for Pd recovery from wastewater. The transcriptome data are valuable for understanding the global bioreduction mechanism of the microbial conversion of palladium.

微生物减少是环境修复和从废物中回收贵金属的可持续方法。在温和条件下细菌介导的废水中钯离子 (Pd ^{2+ ) 的还原就是这样一种策略。}然而，钯的生物还原通常需要外部电子供体。在此，发现一种新型革兰氏阳性细菌苏云金芽孢杆菌Y9 ( B. thuringiensis Y9) 可将 Pd ²⁺还原为钯纳米颗粒(Pd-NPs) 与内源电子供体。转录组学分析显示，分别有 443 和 439 个差异表达的基因在厌氧和需氧条件下对钯处理有反应。发现编码苏云金芽孢杆菌Y9中NADH-醌氧化还原酶、脱氢酶、细胞色素c还原酶、细胞色素c氧化酶、醌循环和ribE与钯还原具有强正相关关系。B. thuringiensis对钯的去除效率在厌氧条件下高达 93 mg g^-1-1在有氧条件下。氢化酶在生物还原过程中也起着至关重要的作用。使用响应面法 (RSM)获得主要影响因素的最大 Pd 去除率为 99.18% 。我们的研究为从废水中回收 Pd 提供了一种新颖且可持续的策略。转录组数据对于理解钯的微生物转化的全球生物还原机制很有价值。