Comparative studies on physiological responses at phosphorus stress of three waterbloom-forming cyanobacteria

Abstract

In this paper, the physiological responses of the three waterbloom-forming cyanobacteria (Microcystis aerugillosa FACHB469, Anabaena flos-aquae FACHB245 and Oscillatoria planctonica FACHB708) at Phosphorus limitation in stationary cultures were studied. The phosphorus uptake rate is hyperbolic correlated to the extracellular nutrient concentration as described by the Michaelis-Menten equation. K for phosphorus of M. aeruginosa, A. flos-aquae and O. planctonica was 8.260, 2.199 and 4.926, respectively, which indicated that the tolerant ability to the phosphorus stress was in the decreasing order of A. flos-aquae, O. planktonica and M. aeruginosa in the phosphorus deficient condition. The capacity to luxuriously uptake phosphorus of M. aeruginosa was higher than that of O. planctonica and A. flos-aquae. This result was consistent with the phosphorus uptake kinetics experiments of the three cyanobacteria. Alkaline phosphatase acitivity (APA) of cyanobacteria were inversely correlated with external phosphorus concentration. The APA was obviously promoted under phosphorus deficiency stress. The capacity of excreting A P in the three cyanobacteria was significantly different under the same phosphorus limited conditions ( A. flos-aquae > O. planctonica > M. aeruginosa). Extracellular APA of A. flos-aquae was 10 and 5 times higher than that of M. aeruginosa and O. planctonica, respectively, when they were cultured in phosphorus deficient condition.The studies compared phosphorus uptake kinetics and capacity of excreting AP in the three cyanobacteria, which would help to understand the population succession of cyanobacteria in the environmental waterbodies