The role of trace p-hydroxybenzoic acid to Chlorella for advanced wastewater treatment: Mitigating bacterial contamination and boosting biomass recovery

• Published in: Resources, conservation and recycling conservation and recycling, 2023-12, Vol.199, p.107229, Article 107229
• Main Authors: Zhao, Zhenhao, Xue, Wenqi, Wang, Jinfeng, Zhang, Chongjun, Zhou, Dandan
• Format: Article
• Language: English
• Subjects: Bacterial contamination; Microalgae; P-hydroxybenzoic acid; Phytohormone; Wastewater treatment
• ISSN: 0921-3449; 1879-0658
• DOI: 10.1016/j.resconrec.2023.107229

•Trace p-HBA enables chlorella to triumph dramatically over bacterial contamination.•p-HBA boosted microalgal growth by 32.2 % while inhibiting bacteria by 80 %.•p-HBA upregulated microalgae photosynthesis, MAPK, and oxidative phosphorylation.•p-HBA decreased bacterial glucose absorption and its associated downstream metabolic.•p-HBA increased intracellular products and promoted biomass harvesting. Microalgae represent promising organisms for applications in wastewater resource recovery. Nonetheless, bacterial contamination disrupts the ecological niche dominated by microalgae cells. By modulating plant-pathogen interactions, phytohormones have a positive regulatory role in enhancing plant immunity. In a bioreactor containing 1.0 M p-hydroxybenzoic acid (p-HBA), we tested the hypothesis that phytohormone-like could inhibit bacteria growth while simultaneously promoting microalgal growth. p-HBA increased Chlorella biomass by 32.2 % and upregulated photosynthesis, mitogen-activated protein kinase, and oxidative phosphorylation genes. Simultaneously, bacterial gene copy number decreased ∼80 % and genes involved in flagellum movement, cell wall formation, and DNA replication were found to be silenced. Meanwhile, the increase in the microalgae biomass and the presence of extracellular polymeric substances (EPS) increased bacteria-microalgae floc sedimentation. Microalgae produced 26–82 % more intracellular products. This study establishes a strategy for using a trace amount of p-HBA to assist Chlorella in establishing survival dominance under bacterial contamination. [Display omitted]