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 Carb...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 day 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?5 cells·mL-1) during the five days occurred at 18-L Carboy. The concentration of total bacteria at all levels was always higher than that of heterotrophic bacteria. The average ratio of heterotrophic to total bacteria was higher in the 2-L (0.0108) and 18-L (0.0172) cultures. The high biomass of C. muelleri and the presence of Vibrio spp. at the 18-L and 400-L levels indicate that it is necessary to establish programs to prevent diseases and economic losses caused by pathogenic bacteria in penaeid shrimp farming.展开更多
文摘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 day 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?5 cells·mL-1) during the five days occurred at 18-L Carboy. The concentration of total bacteria at all levels was always higher than that of heterotrophic bacteria. The average ratio of heterotrophic to total bacteria was higher in the 2-L (0.0108) and 18-L (0.0172) cultures. The high biomass of C. muelleri and the presence of Vibrio spp. at the 18-L and 400-L levels indicate that it is necessary to establish programs to prevent diseases and economic losses caused by pathogenic bacteria in penaeid shrimp farming.
