Effect of phosphorus stress on Microcystis aeruginosa growth and phosphorus uptake

Abstract

This study was designed to advance understanding of phosphorus regulation of Microcystis aeruginosa growth, phosphorus uptake and storage in changing phosphorus (P) conditions as would occur in lakes. We hypothesized that Microcystis growth and nutrient uptake would fit classic models by Monod, Droop, and Michaelis-Menten in these changing conditions. Microcystis grown in luxury nutrient concentrations was transferred to treatments with phosphorus concentrations ranging from 0–256 μg P∙L-1 and luxury nitrogen. Dissolved phosphorus concentration, cell phosphorus quota, P uptake rate and cell densities were measured at day 3 and 6. Results showed little relationship to predicted models. Microcystis growth was asymptotically related to P treatment from day 0–3, fitting Monod model well, but negatively related to P treatment and cell quota from day 3–6. From day 0–3, cell quota was negatively related to P treatments at <2 μg∙L-1, but increased slightly at higher P. Cell quota decreased greatly in low P treatments from day 3–6, which may have enabled high growths in low P treatments. P uptake was positively and linearly related to P treatment during both periods. Negative uptake rates and increases in measured culture phosphorus concentrations to 5 μg∙L-1 in the lowest P treatments indicated P leaked from cells into culture medium. This leakage during early stages of the experiment may have been sufficient to stimulate metabolism and use of intracellular P stores in low P treatments for rapid growth. Our study shows P regulation of Microcystis growth can be complex as a result of changing P concentrations, and this complexity may be important for modeling Microcystis for nutrient and ecosystem management.

Genotypic Variation in Cotton Genotypes for Phosphorus-Use Efficiency

“…Therefore, chemical P fertilizers are used to overcome this deficiency, but immobilization and runoff make it unavailable for successful crop production [12]. Besides, this injudicious use of P fertilizers leads to environmental pollution and increases the cost of production [13]. Moreover, the naturally available reservoirs of rock phosphate are depleting day by day due to its overuse and prices are rising as the resource becomes scarcer [14].…”

Categorization of wheat genotypes for phosphorus efficiency

“…High pH and higher concentration of CaCO 3 are responsible for P unavailability in alkaline calcareous soils [ 2 – 4 ] while in acidic soils, higher concentration of Al and Fe declines P availability to plants [ 5 , 6 ]. Moreover, continuously increasing prices, injudicious use of N fertilizers and increased environmental issues of phosphoric fertilizers [ 7 ] aggravate the situation manifold and are among the major reasons of low P application in crop production system [ 1 , 8 ]. Rock phosphate ores may get depleted in the near future.…”

Changes of Extracellular Polymeric Substance (EPS) during Microcystis Aeruginosa Blooms at Different Levels of Nutrients in a Eutrophic Microcosmic Simulation Device

“…Microcystis aeruginosa grows slowly when the chlorophyll-a content has basically no change in the initial stage of culture (about one week), this stage can be considered as lag phase. Some studies have suggested that the growth rate of Microcystis mainly depends on the intracellular phosphorus [24], not extracellular phosphorus, which can be confirmed from the lag phase. Microcystis aeruginosa did not quickly enter the logarithmic phase despite the high phosphorus content of water from phosphorus-deficient state that has come into the phosphorus-rich medium, which can indicate that Microcystis was quickly uptaking the extracellular phosphorus in this phase in preparation for its massive proliferation.…”