Bacillus licheniformis enhances Chlorella vulgaris’s biomass and biodiesel production in wastewater treatment

Chlorella -based wastewater treatment presents a sustainable alternative to conventional methods. While previous studies highlighted Chlorella-bacteria synergy in wastewater remediation, bacterial effects on Chlorella biomass and biodiesel production remain unclear. This study investigates the impact of Bacillus licheniformis on Chlorella vulgaris growth, biomass yield, and biodiesel production. Results demonstrated that B. licheniformis significantly enhanced pollutant removal, achieving equal to or greater than 84.30 ± 2.61 % reduction in all wastewater contaminants, which was markedly superior to C. vulgaris alone. Furthermore, B. licheniformis treatment increased C. vulgaris biomass and biodiesel yield by 28.63 ± 2.88 % and 48.03 ± 3.42 %, respectively. The presence of B. licheniformis enriched the wastewater with bioavailable nutrients by producing hydrolytic enzymes such as N-protease (69.76 ± 8.60 U/mL) and α-amylase (25.78 ± 6.29 U/mL), as well as phytohormones, including auxins (554.98 ± 92.03 ng/mL) and gibberellins (30.08 ± 3.93 ng/mL). Additionally, the combined treatment stabilized pH fluctuations, creating an optimal environment for algal growth. These findings underscore the potential of integrating B. licheniformis with C. vulgaris to enhance wastewater treatment efficiency while simultaneously boosting biofuel production. This synergistic approach offers a strategy for sustainable wastewater management and bioenergy generation. • Bacillus licheniformis improve Chlorella vulgaris’ biomass. • B. licheniformis boosts biodiesel production from C. vulgaris. • Bacteria-algae synergy provides sustainable production of biodiesel and biomass. • Phytohormones from B. licheniformis enhance C. vulgaris growth and lipids.