Wahjudi Sekar Mayang W, Engel Dominik, Büchs Jochen
Aachener Verfahrenstechnik - Biochemical Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074, Aachen, Germany.
BMC Biotechnol. 2025 Jan 10;25(1):5. doi: 10.1186/s12896-024-00927-5.
In the fermentation industry, the demand to replace expensive complex media components is increasing for alternative nutrient sources derived from waste or side streams, such as corn steep liquor (CSL). However, the use of CSL is associated with common problems of side products, such as batch-to-batch variations and compositional inconsistencies. In this study, to detect batch-to-batch variations in CSL for Ogataea polymorpha cultivations, a "fingerprinting" system was developed by employing the Respiration Activity Monitoring System designed for shake flasks (RAMOS) and 96-well microtiter plates (µTOM).
At 2.5 g d.s./L CSL and 5 g/L glucose, a limitation by a secondary substrate, other than the carbon source, was observed. For this specific CSL medium, this limitation was caused by ammonium nitrogen and could be removed through targeted supplementation of ammonium sulphate. Under ammonium nitrogen limitation, O. polymorpha showed a change in morphology and developed a different cell size distribution. Increasing CSL storage times impaired O. polymorpha cultivation results. It was speculated that this observation is caused by micronutrient precipitation as sulfide salts. Through targeted nutrient supplementation, these limiting microelements were identified to be copper, iron and zinc.
This study shows the versatility of CSL as an alternative nutrient source for O. polymorpha cultivations. "Fingerprinting" of CSL batches allows for early screening. Fermentation inconsistencies can be eliminated by selecting the better performing CSL batches or by supplementing and improving an inferior CSL prior to large-scale productions.
在发酵工业中，使用源自废物或副产物的替代营养源（如玉米浆（CSL））来替代昂贵的复杂培养基成分的需求日益增加。然而，使用CSL存在一些常见的副产物问题，如批次间差异和成分不一致。在本研究中，为了检测用于多形汉逊酵母培养的CSL批次间差异，通过使用专为摇瓶设计的呼吸活性监测系统（RAMOS）和96孔微量滴定板（µTOM）开发了一种“指纹识别”系统。
在2.5 g d.s./L CSL和5 g/L葡萄糖的条件下，观察到除碳源外的第二种底物的限制。对于这种特定的CSL培养基，这种限制是由铵态氮引起的，可以通过有针对性地添加硫酸铵来消除。在铵态氮限制下，多形汉逊酵母的形态发生变化，细胞大小分布也有所不同。CSL储存时间的增加会损害多形汉逊酵母的培养结果。据推测，这一现象是由微量元素以硫化物盐的形式沉淀所致。通过有针对性的营养补充，确定这些限制生长的微量元素为铜、铁和锌。
本研究表明CSL作为多形汉逊酵母培养的替代营养源具有多功能性。CSL批次的“指纹识别”可实现早期筛选。通过选择性能更好的CSL批次，或在大规模生产前对劣质CSL进行补充和改进，可以消除发酵过程中的不一致性。
