Effects of different nutrient conditions on the growth of Betaphycus gelatinae

Abstract:

In this study, we measured the growth and pigment content of Betaphycus gelatinae under different inorganic nitrogen concentrations (50, 100, 200, 400, and 800 μmol/L), inorganic phosphorus concentrations (2.5, 5, 10, 20, 40, and 80 μmol/L), and different ratios of NH4+-N and NO3–-N (0/100, 25/75, 50/50, 75/25, and 100/0). The best nutrient conditions for the growth of B. gelatinae were thus evaluated. The results showed that the optimum nutrient conditions for the growth of B. gelatinae were an inorganic nitrogen concentration of 0~200 μmol/L, inorganic phosphorus concentration of 2.5~10 μmol/L, and NH4+-N to NO3–-N ratio of 25/75. Within the range of suitable nutrient conditions, B. gelatinae achieved high weight gain. When the inorganic nitrogen concentration exceeded 200 μmol/L, inorganic phosphorus concentration exceeded 10 μmol/L, or the ratio of NH4+-N to NO3–-N was higher than 50/50, the growth of B. gelatinae was slow but tolerance to adverse growth conditions was observed at the beginning of cultivation. However, with the extension of culture time, the growth of B. gelatinae became abnormal; severe white rot of algal bodies and a sharp decrease in weight gain was observed. Overall, our findings indicate that B. gelatinae grows faster under relatively low nutrient conditions and provide a theoretical basis for large-scale multiplication cultivation of B. gelatinae.