School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Penang, Malaysia; International Center for Biotechnology, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan.
School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Penang, Malaysia.
Environ Res. 2023 Dec 15;239(Pt 2):117403. doi: 10.1016/j.envres.2023.117403. Epub 2023 Oct 15.
Bio-coating, a recent and promising approach in attached microalgal cultivation systems, has garnered attention due to its efficiency in enhancing immobilized algal growth, particularly in submerged cultivation systems. However, when the cells are cultured on thin solid microporous substrates that physically separate them from the nutrient medium, it remains unclear whether the applied bio-coatings still have a significant impact on algal growth or the subsequent rates of algal organic matter (AOM) release. Therefore, this current work investigated the role of bio-coatings on the microalgal monoculture growth of one freshwater species, Chlorella vulgaris ESP 31, and one marine species, Cylindrotheca fusiformis on a hydrophilic substrate, polyvinylidene fluoride membrane in a permeated cultivation system. Wide range of bio-coating sources were adapted, with the result demonstrating that bacteria-derived coating promoted algal growth by as high as 140% when compared with the control group for both species. Interestingly, two distinct adaptation mechanisms were observed between the species, with only C. fusiformis demonstrating a positive correlation between cell growth and AOM productivity, particularly in its extracellularly bound fractions. It is worth noting that despite this specific fraction exhibiting the lowest content among all; it displayed significant relevance in terms of AOM productivity. High extracellular protein-to-polysaccharide ratio (>5.7 fold) quantified on bacterial intracellular exudate-coated membranes indirectly revealed an underlying symbiotic microalgal-bacterial interaction. This is the first study showing how bio-coating influenced AOM yield without any physical interaction between microalgae and bacteria. It further confirms the practical benefits of bio-coating in attached cultivation systems.
生物涂层是一种新兴且有前景的附着微藻培养系统方法，由于其能够有效促进固定化藻类生长，特别是在浸没式培养系统中，因此备受关注。然而，当细胞在薄的固体微孔基质上培养时，这些基质将细胞与营养介质物理隔开，此时应用的生物涂层是否仍然对藻类生长或随后的藻类有机质（AOM）释放速率有重大影响尚不清楚。因此，本研究调查了生物涂层在淡水物种普通小球藻 ESP 31 和海洋物种旋链角毛藻在亲水基质聚偏氟乙烯膜上的渗透培养系统中的微藻纯培养生长中的作用。本研究适应了广泛的生物涂层来源，结果表明，与对照组相比，细菌来源的涂层可使两种物种的藻类生长分别提高高达 140%。有趣的是，在这两个物种之间观察到了两种截然不同的适应机制，只有旋链角毛藻的细胞生长与 AOM 生产力之间呈正相关，特别是在其细胞外结合的部分。值得注意的是，尽管该特定部分在所有部分中含量最低，但它在 AOM 生产力方面具有重要意义。在细菌细胞内渗出物涂层膜上定量的高胞外蛋白与多糖比（>5.7 倍）间接揭示了潜在的共生微藻-细菌相互作用。这是第一项表明生物涂层如何在微藻和细菌之间没有任何物理相互作用的情况下影响 AOM 产量的研究。它进一步证实了生物涂层在附着培养系统中的实际益处。
