Bioprocess Development for Chlorella vulgaris Cultivation and Biosynthesis of Anti-phytopathogens Silver Nanoparticles

Abstract

Bioprocess Development for Chlorella vulgaris Cultivation and Biosynthesis of Anti-phytopathogens Silver Nanoparticles In this study, growth media formulations and environmental conditions were varied to optimize the growth media composition and conditions for maximized algal biomass production. The production both of Chlorella vulgaris in different photobioreactor configurations (250 ml flask, 5L flask and 7.5L stirred tank reactor) was investigated, using different organic and inorganic media formulations. The effect of initial cell concentrations, agitation speed, airflow rate and photoperiodic time were studied using inexpensive poultry manure medium, the results indicate that 0.5 × 107 (n/ml), 200 rpm, 1 bar and 16:8hr respectively which better for biomass productivity at growth periods. The highest overall specific growth rate (μ) and doubling time (td) were found when growing C. vulgaris in batch operation in a 7.5 L stirred tank bioreactor, μ=0.08 d-1 and 3.5 days respectively which also reached the maximum biomass concentration of 0.59 g/L. Biosynthesized silver nanoparticles (AgNPs) are being widely using in the field of agriculture. Biosynthesis of silver nanoparticles was carried out by using the algal cells for the reduction of aqueous silver ions in short period. A Plackett-Burman experimental design was applied to screen seven parameters for biosynthesis of AgNPs, the most important parameters were pH, temperature and container head space; the results indicate that pH 6, 40ºC and 75% container head space which better for biosynthesis of AgNPs which also reached the maximum final product concentration of 5.59 mg/L. The AgNP formation was confirmed with the help of SEM, XRD and UV-Vis spectroscopy. These AgNPs were tested for antibacterial and antifungal activities. The tested strains are; Erwinia carotovora and Alternaria alternata were used. The results indicate that the AgNPs may have an important advantage over conventional antibiotics.