State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.
Appl Microbiol Biotechnol. 2018 Apr;102(7):3133-3143. doi: 10.1007/s00253-018-8799-6. Epub 2018 Feb 27.
The feast-to-famine ratio (F/F) represents the extent of selective pressure during polyhydroxyalkanoate (PHA) culture selection. This study evaluated the effects of F/F on a new PHA production system by an enriched culture with valerate-dominant sludge hydrolysate and selected the optimal F/F. After the original F/F 1/3 was modified to 1/1, 1/2, 1/4, and 1/5, F/F did not affect their lengths of feast phase, but affected their biomass growth behaviors during the famine phase and PHA-producing abilities. The optimal F/F was 1/2, and compared with 1/3, it increased the maximal PHA content and the fraction of 3-hydroxyvalerate (3HV) and 3-hydroxy-2-methylvalerate (3H2MV) monomers, with higher productivity and better polymer properties. Although F/F 1/2 impaired the advantage of the dominant genus Delftia, it improved the PHA production rate while decreased biomass growth rate, meanwhile enhancing the utilization and conversion of valerate. These findings indicate that in contrast to previous studies using acetate-dominant substrate for PHA production, the new system fed by valerate-dominant substrate can adopt a higher F/F.
食料-饥饿比（F/F）代表聚羟基烷酸酯（PHA）培养选择过程中的选择压力程度。本研究通过用戊酸盐占主导的污泥水解物富集培养来评估 F/F 对新 PHA 生产系统的影响，并选择最佳的 F/F。在将初始 F/F 1/3 改为 1/1、1/2、1/4 和 1/5 后，F/F 并不影响它们的饱食阶段的长度，但影响它们在饥饿阶段的生物量生长行为和 PHA 产生能力。最佳 F/F 为 1/2，与 1/3 相比，它提高了最大 PHA 含量和 3-羟基戊酸（3HV）和 3-羟基-2-甲基戊酸（3H2MV）单体的比例，具有更高的生产力和更好的聚合物性能。虽然 F/F 1/2 削弱了优势属 Delftia 的优势，但它提高了 PHA 的生产速率，同时降低了生物量的生长速率，同时增强了戊酸盐的利用和转化。这些发现表明，与以前使用以乙酸盐为主的底物生产 PHA 的研究相比，以戊酸盐为主的底物喂养的新系统可以采用更高的 F/F。
