Simultaneous Growth of Chaetoceros muelleri and Bacteria in Batch Cultures

Abstract

The relationship between bacterial load and the microalga Chaetoceros muelleri was analyzed in a scale-up experiment. The microalga was grown during five days in a 0.4-L Erlenmeyer flask, 2-L Fernbach flask, 18-L Carboy and 400-L column, during which the cell density of C. muelleri, the abundance of heterotrophic bacteria, Vibrio spp., and total bacteria were determined. The highest specific growth rates (μ) of C. muelleri occurred during the first days of culture (0.88 to 2.29 d−1). Highest cell density was recorded on the fifth day at the 2-L (7.62 × 106 cells mL−1) and 18-L (6.32 × 106 cells mL−1), coinciding with the maximum counts of heterotrophic bacteria (16.55 × 105 and >30 × 105 CFU mL−1, respectively). There was a high correlation (0.80, 0.75, 0.85; p ˂ 0.05) between microalgal cell density and total bacteria in the first three culture volumes and a low correlation (0.27, p = 0.34) at 400-L column.