Investigations of microalgae-bacteria relationship are important to studies of microbial ecology, red tide, aquaculture and pollutant degradation, etc. To date, microalgae-bacteria interactions are still not well understood, and purification of eukaryotic microalgae is also rarely mentioned. Here, bacteria-free Dunaliella salina was obtained with optimized antibiotic treatments. Axenic microalgal growth did not differ significantly with non-axenic algae in f/2 medium. However, when the contents of nitrogen and phosphorus were 10-fold higher of f/2, or there were no vitamins or trace elements in f/2 medium, the non-axenic algae grow much faster-increased 6.78%, 10.25% and 10.19% than axenic algal biomass, respectively. Associated bacteria haven’t significant effect on microalgal intracellular gross fat and ash contents, while improved microalgal intracellular protein and intra- and extra-cellular total carbohydrate contents during most growth stages. Associated bacteria didn’t impact algal nitrogen uptake. While under high nutrient concentration conditions, the phosphorus contents decreased more rapidly in non-axenic algal culture (decreased 40.48%) than in axenic algal culture (decreased 5.99%) within the first 4 days, suggesting that non-axenic algal phosphorus uptake was stronger. The study provided a simpler system and effective references to research of microalgae-bacteria relationship.