Syngas (CO/H₂) fermentation provides an alternative method for organics utilization. The hollow-fiber membrane biofilm reactor (HfMBR) offers a potential way to use CO and H₂ effectively. However, studies on syngas utilization by mixed culture fermentation (MCF) in HfMBR were seldom reported. This study is the first to demonstrate and compare the in-situ production of volatile fatty acids via syngas by mesophilic and thermophilic MCF, in which CO and H₂ utilization exceeded 95% and even reached 100%. Acetate (4.22 g/L), butyrate (1.35 g/L), caproate (0.88 g/L), and caprylate (0.52 g/L) were detected at 35 °C, whereas acetate was the main metabolite at 55 °C. The proportion of acetate ranged from 47.5% to 62.7% at 35 °C and exceeded 90% at 55 °C in the batch mode. Notably, the acetate concentration and the production rate could reach 24.6 g/L and 16.4 g/(L^.d), respectively, at pH 6.5 in the continuous mode at 55 °C. Thus, thermophilic conditions are preferable for high-purity and high-concentration acetate production from syngas. As revealed by Illumina high-throughput sequencing, Clostridium (41.6%) and Thermoanaerobacterium (92.8%) were the dominant bacteria under mesophilic and thermophilic conditions, respectively. This study demonstrates a potential technique for syngas (CO/H₂) utilization and biochemicals production by MCF in HfMBR.

合成气（CO / H ₂）发酵为有机物的利用提供了另一种方法。中空纤维膜生物膜反应器（HfMBR）提供了有效利用CO和H ₂的潜在途径。然而，很少有关于在HfMBR中通过混合培养发酵（MCF）利用合成气的研究。这项研究是第一个证明和比较中温和嗜热MCF通过合成气原位产生挥发性脂肪酸的方法，其中CO和H ₂利用率超过95％，甚至达到100％。在35°C时检测到乙酸盐（4.22 g / L），丁酸盐（1.35 g / L），己酸盐（0.88 g / L）和辛酸盐（0.52 g / L），而乙酸盐是55°C时的主要代谢产物。在间歇模式下，乙酸盐的比例在35°C时为47.5％至62.7％，在55°C时超过90％。值得注意的是，乙酸的浓度和产率可达到24.6克/ L和16.4克/（L ^。在55以连续模式分别d），在pH 6.5℃。因此，对于从合成气生产高纯度和高浓度乙酸酯而言，优选嗜热条件。正如Illumina高通量测序所揭示的，梭状芽胞杆菌（41.6％）和嗜热厌氧菌（92.8％）分别是中温和嗜热条件下的优势细菌。这项研究证明了MCf在HfMBR中利用合成气（CO / H ₂）和生产生化药品的潜在技术。