Effects of Sodium Bicarbonate Supplements on Growth Performance and Quality of Marine Microalgal Inoculum Production

The effects of sodium bicarbonate (NaHCO 3 ) supplements (0.05, 0.25, 0.50, 1.0 g ∙ L -1 ) in the culture medium were examined on six marine microalgae inocula cultured under laboratory conditions (25±1 °C, 28 psu, 12L:12D, 3,000 Lux light intensity, Conway medium) for 10 days and compared to a control without NaHCO 3 . The parameters assessed included cell density (CD), specific growth rate (µ), division rate (K), and doubling time (D). The results indicated a positive effect on CD, µ, K, and D for the production of Chaetoceros calcitrans, Thalassiosira weissflogii, Chlorella spp., and Nannochloropsis oculata strains with NaHCO 3 additions of 0.25, 1.0, 1.0, and 0.50 g ∙ L -1 , respectively. Conversely, NaHCO 3 concentrations of 0.25–1.0 g ∙ L -1 negatively impacted the CD, µ, K, and D for Tetraselmis suecica and Isochrysis galbana culture. Regarding inoculum quality after refrigerated storage at 4±1 °C, NaHCO 3 supplements did not sustain the growth rates of C. calcitrans, T. weissflogii, and Chlorella spp. inocula cultured after storage for 7, 15, and 30 days. However, 0.5 g ∙ L -1 NaHCO 3 maintained the growth rate of N. oculata cultured after storage for 7 days. This study provides comprehensive insights into the optimal NaHCO 3 supplementation for maintaining each microalgal strain in a stable state for inoculum production applications.