Microbial chain elongation integrating innovative bioconversion technologies with organic waste utilization can transition current energy-intensive n-caproic acid production to sustainable circular bioeconomy systems. However, ammonia-rich waste streams, despite their suitability, pose inhibitory challenges to these bioconversion processes. Herein, biochar was employed as an additive to enhance the activity of chain elongating microbes under ammonia inhibition conditions, with an objective to detail underlying mechanisms of improvements. Biochar addition significantly improved chain elongation performance even under severe ammonia stress (exceeding 8 g N/L), increasing n-caproic acid yields by 40 % to 158 % and reducing lag times by 51 % to 90 %, compared with the best-performing group without biochar addition. The material contribution to n-caproic production reached up to 94.3 % (at 4 g N/L). These enhancements were mainly attributed to the new electron syntrophy induced by biochar, which improved electron transfer system activity and electrical conductivity of the fermentation system. This is further substantiated by increased relative abundances of the genus Sporanaerobacter, electroactive bacteria, and up-regulated direct electron transfer-related genes including conductive pili and c-type cytochrome. This study demonstrates that biochar can confer robust resilience to ammonia toxicity in functional microbes, paving a way for efficient and sustainable n-caproic acid production.

中文翻译：

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生物炭在 N-己酸生产中赋予微生物对氨毒性的显着抗性


将创新生物转化技术与有机废物利用相结合的微生物链伸长可以将当前能源密集型己酸生产转变为可持续的循环生物经济系统。然而，尽管富含氨的废物流适用，但对这些生物转化过程构成了抑制性挑战。在此，生物炭被用作添加剂，以增强氨抑制条件下链延长微生物的活性，目的是详细说明改进的潜在机制。即使在严重的氨胁迫（超过 8 g N/L）下，添加生物炭也显着提高了链伸长性能，与未添加生物炭的表现最好的组相比，n-己酸产量提高了 40% 至 158%，并将滞后时间缩短了 51% 至 90%。对正碳生产的材料贡献高达 94.3%（4 克 N/L）。这些增强主要归因于生物炭诱导的新电子同仁，它提高了发酵系统的电子传递系统活性和电导率。孢子菌属、电活性细菌和上调的直接电子转移相关基因（包括导电菌毛和 c 型细胞色素）的相对丰度增加进一步证实了这一点。这项研究表明，生物炭可以赋予功能微生物对氨毒性的强大弹性，为高效和可持续的 n-己酸生产铺平了道路。