Enhancing organic matter productivity in microalgal-bacterial biofilm using novel bio-coating

• Published in: The Science of the total environment Vol. 906; p. 167576
• Main Authors: Tong, C.Y., Honda, Kohsuke, Derek, C.J.C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2024
• Subjects: Algal organic matters; Bacteria; Biocoating; Biofilm; Microalgae; Biocoating; Biofilm; Bacteria; Microalgae; Algal organic matters
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.167576

Research on renewable energy from microalgae has led to a growing interest in porous substrate photobioreactors, but their widespread adoption is currently limited to pure microalgal biofilm cultures. The behavior of microalgal-bacterial biofilms immobilized on microporous substrates remains as a research challenge, particularly in uncovering their mutualistic interactions in environment enriched with dissolved organic matter. Therefore, this study established a novel culture platform by introducing microalgal-derived bio-coating that preconditioned hydrophilic polyvinylidene fluoride membranes for the microalgal-bacterial biofilm growth of freshwater microalgae, Chlorella vulgaris ESP 31 and marine microalgae, Cylindrotheca fusiformis with bacteria, Escherichia coli. In the attached co-culture mode, the bio-coating we proposed demonstrated the ability to enhance microalgal growth for both studied species by a range of 2.5 % to 19 % starting from day 10 onwards. Additionally, when compared to co-culture on uncoated membranes, the bio-coating exhibited a significant bacterial growth promotion effect, increasing bacterial growth by at least 2.35 times for the C. vulgaris-E. coli co-culture after an initial adaptation phase. A significant increase of at least 72 % in intracellular biochemical compounds (including chlorophyll, polysaccharides, proteins, and lipids) was observed within just five days, primarily due to the high concentration of pre-coated organic matter, mainly sourced from the internal organic matter (IOM) of C. fusiformis. Higher accumulation of organic compounds in the bio-coating indirectly triggers a competition between microalgae and bacteria which potentially stimulate the production of additional intra−/extra-organic substances as a defensive response. In short, insight gained from this study may represent a paradigm shift in the ways that symbiotic interactions are promoted to increase the yield of specific bio-compounds with the presence of bio-coating. [Display omitted] •Novel algae-derived biocoating was introduced in porous substrate photobioreactor.•Microalgal-bacterial cocultures on biocoated membranes grew optimally within 5 days.•IOM-coated PVDF membranes promoted higher yield of intracellular bio-compounds.•Biocoating was proposed as a substitute to induce AOM and lipid yield.