Shaikh Sultan, McKay Gordon, Mackey Hamish Robert
Division of Sustainable Development, College of Science and Engineering, Hamad bin Khalifa University, Qatar Foundation, Doha, Qatar.
Department of Civil and Natural Resources Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.
Biotechnol Rep (Amst). 2024 Nov 6;44:e00863. doi: 10.1016/j.btre.2024.e00863. eCollection 2024 Dec.
This research looked at how three different light intensities (1600, 4300, and 7200 lx) affect the biomass development, treatment of fuel synthesis wastewater and the recovery of valuable bioproducts between biofilm and suspended growth in a purple-bacteria enriched photobioreactor. Each condition was run in duplicate using an agricultural shade cloth as the biofilm support media in a continuously mixed batch reactor. The results showed that the highest chemical oxygen demand (COD) removal rate (56.8 ± 0.9 %) was found under the highest light intensity (7200 lx), which also led to the most biofilm formation and highest biofilm biomass production (1225 ± 95.7 mg). The maximum carotenoids (Crts) and bacteriochlorophylls (BChls) content occurred in the suspended growth of the 7200 lx reactor. BChls decreased with light intensity in suspended growth, while in biofilm both Crts and BChls were relatively stable between light conditions, likely due to an averaging effect as biofilm thickened at higher light intensity. Light intensity did not affect protein content of the biomass, however, biofilm showed a lower average (41.2 % to 43.7 %) than suspended biomass (45.4 % to 47.7 %). For polyhydroxybutyrate (PHB) the highest cell concentration in biofilm occurred at 1600 lx (11.4 ± 2.4 %), while for suspended growth it occurred at 7200 lx (22.7 ± 0.3 %), though total PHB productivity remained similar between reactors. Shading effects from the externally located biofilm could explain most variations in bioproduct distribution. Overall, these findings suggest that controlling light intensity can effectively influence the treatment of fuel synthesis wastewater and the recovery of valuable bioproducts in a biofilm photobioreactor.
本研究考察了三种不同光照强度（1600、4300和7200勒克斯）对富含紫色细菌的光生物反应器中生物量发展、燃料合成废水处理以及生物膜和悬浮生长之间有价值生物产品回收的影响。在连续混合分批反应器中，以农用遮阳网作为生物膜支撑介质，每种条件重复运行两次。结果表明，在最高光照强度（7200勒克斯）下，化学需氧量（COD）去除率最高（56.8±0.9%），这也导致了最多的生物膜形成和最高的生物膜生物量产量（1225±95.7毫克）。类胡萝卜素（Crts）和细菌叶绿素（BChls）的最大含量出现在7200勒克斯反应器的悬浮生长中。在悬浮生长中，BChls随光照强度降低，而在生物膜中，Crts和BChls在不同光照条件下相对稳定，这可能是由于在较高光照强度下生物膜增厚产生的平均效应。光照强度不影响生物量的蛋白质含量，然而，生物膜的平均含量（41.2%至43.7%）低于悬浮生物量（45.4%至47.7%）。对于聚羟基丁酸酯（PHB），生物膜中最高细胞浓度出现在1600勒克斯（11.4±2.4%），而悬浮生长中出现在7200勒克斯（22.7±0.3%），尽管各反应器之间总PHB生产率保持相似。外部生物膜的遮光效应可以解释生物产品分布的大部分变化。总体而言，这些发现表明，控制光照强度可以有效地影响生物膜光生物反应器中燃料合成废水的处理和有价值生物产品的回收。
