Vu Danh H, Mahboubi Amir, Root Andrew, Heinmaa Ivo, Taherzadeh Mohammad J, Åkesson Dan
Swedish Centre for Resource Recovery, University of Borås, 501 90 Borås, Sweden.
MagSol, Tuhkanummenkuja 2, 00970 Helsinki, Finland.
Membranes (Basel). 2023 May 31;13(6):569. doi: 10.3390/membranes13060569.
Volatile fatty acids (VFAs) appear to be an economical carbon feedstock for the cost-effective production of polyhydroxyalkanoates (PHAs). The use of VFAs, however, could impose a drawback of substrate inhibition at high concentrations, resulting in low microbial PHA productivity in batch cultivations. In this regard, retaining high cell density using immersed membrane bioreactor (iMBR) in a (semi-) continuous process could enhance production yields. In this study, an iMBR with a flat-sheet membrane was applied for semi-continuous cultivation and recovery of in a bench-scale bioreactor using VFAs as the sole carbon source. The cultivation was prolonged up to 128 h under an interval feed of 5 g/L VFAs at a dilution rate of 0.15 (d), yielding a maximum biomass and PHA production of 6.6 and 2.8 g/L, respectively. Potato liquor and apple pomace-based VFAs with a total concentration of 8.8 g/L were also successfully used in the iMBR, rendering the highest PHA content of 1.3 g/L after 128 h of cultivation. The PHAs obtained from both synthetic and real VFA effluents were affirmed to be poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with a crystallinity degree of 23.8 and 9.6%, respectively. The application of iMBR could open an opportunity for semi-continuous production of PHA, increasing the feasibility of upscaling PHA production using waste-based VFAs.
挥发性脂肪酸（VFAs）似乎是用于经济高效生产聚羟基脂肪酸酯（PHA）的一种经济的碳原料。然而，使用VFAs可能会在高浓度时带来底物抑制的缺点，导致分批培养中微生物PHA的生产率较低。在这方面，在（半）连续过程中使用浸没式膜生物反应器（iMBR）保持高细胞密度可以提高产量。在本研究中，使用平板膜的iMBR被应用于在实验室规模的生物反应器中以VFAs作为唯一碳源进行半连续培养和回收 。在以0.15（d）的稀释率间歇进料5 g/L VFAs的条件下，培养时间延长至128小时，最大生物量和PHA产量分别为6.6 g/L和2.8 g/L。总浓度为8.8 g/L的基于马铃薯汁和苹果渣的VFAs也成功用于iMBR，培养128小时后获得的最高PHA含量为1.3 g/L。从合成和实际VFA流出物中获得的PHA均被确认为聚（3-羟基丁酸酯-co-3-羟基戊酸酯），结晶度分别为23.8%和9.6%。iMBR的应用可为PHA的半连续生产提供机会，提高使用基于废物的VFAs扩大PHA生产的可行性。
