School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia.
Lett Appl Microbiol. 2014 Jun;58(6):617-23. doi: 10.1111/lam.12236. Epub 2014 Mar 14.
A fed-batch strategy was established based on the maximum substrate uptake rate (MSUR) of Pseudomonas aeruginosa USM-AR2 grown in diesel to produce rhamnolipid. This strategy matches the substrate feed rates with the substrate demand based on the real-time measurements of dissolved oxygen (DO). The MSUR was estimated by determining the time required for consumption of a known amount of diesel. The MSUR trend paralleled the biomass profile of Ps. aeruginosa USM-AR2, where the MSUR increased throughout the exponential phase indicating active substrate utilization and then decreased when cells entered stationary phase. Rhamnolipid yield on diesel was enhanced from 0·047 (g/g) in batch to 0·110 (g/g) in pulse-pause fed-batch and 0·123 (g/g) in MSUR fed-batch. Rhamnolipid yield on biomass was also improved from 0·421 (g/g) in batch, 3·098 (g/g) in pulse-pause fed-batch to 3·471 (g/g) using MSUR-based strategy. Volumetric productivity increased from 0·029 g l(-1) h(-1) in batch, 0·054 g l(-1) h(-1) in pulse-pause fed-batch to 0·076 g l(-1) h(-1) in MSUR fed-batch.
This study highlights the significance of an effective fed-batch strategy for rhamnolipid production in a submerged fermentation using a water-immiscible substrate, based on maximum substrate uptake rate. The impact of this strategy ensured that the substrate was supplied at the rate matching the maximum substrate utilization by the cells without excess feeding, leading to increased rhamnolipid production, yield and productivity.
基于在柴油中生长的铜绿假单胞菌 USM-AR2 的最大基质摄取率 (MSUR) 建立了补料分批策略，以生产鼠李糖脂。该策略根据溶解氧 (DO) 的实时测量结果，将基质进料速率与基质需求相匹配。MSUR 通过测定消耗已知量柴油所需的时间来估算。MSUR 趋势与铜绿假单胞菌 USM-AR2 的生物量分布平行，其中 MSUR 在整个指数期内增加，表明活性基质利用，然后当细胞进入静止期时降低。与分批相比，柴油上的鼠李糖脂产量从 0.047（g/g）提高到脉冲暂停补料分批中的 0.110（g/g）和 MSUR 补料分批中的 0.123（g/g）。与分批相比，生物质上的鼠李糖脂产量也从 0.421（g/g）提高到脉冲暂停补料分批中的 3.098（g/g），再提高到基于 MSUR 的策略中的 3.471（g/g）。比生产率从分批中的 0.029 g/l h 提高到脉冲暂停补料分批中的 0.054 g/l h，再提高到 MSUR 补料分批中的 0.076 g/l h。
本研究强调了基于最大基质摄取率的有效补料分批策略在水不混溶基质的浸没发酵中生产鼠李糖脂的重要性。该策略的影响确保了以与细胞最大基质利用相匹配的速率供应基质，而不会过度喂养，从而提高了鼠李糖脂的产量、产率和生产率。
