Effects of temperature on the nitrate reductase activity and growth of Ulva prolifera

Abstract

To better understand the effect of temperature on the growth and nitrate reductase activity (NRA) of Ulva prolifera and their relationships, the effects of five different temperatures (10, 15, 20, 25, and 30°C) were investigated in a laboratory setup. In this study, an optimization in vitro analysis method for Ulva prolifera NRA was developed. Under different treatments, the NRA, nitrate concentration, pH, the intracellular nitrate and nitrite concentrations, and the POC/PON were evaluated. The results of the in vitro analysis method showed it was optimal for the NRA assay when the extraction time was 6 min, enzymatic reaction time 30 min, volume of phenazine methosulfate (PMS) solution 50 μL, NADH concentration 0.36 mM, and KNO3 concentration 10 mM. The maximal NRA (NRAmax) appeared on the 2nd day in the 10, 15, and 20°C (low‐temperature) groups and on the 1st day in the 25 and 30°C (high‐temperature) groups. The algal growth ended earlier at a high temperature, ending after 5 d at 30 and 25°C and 7 d at 20°C and 9 d at 15°C, and the alga at 10°C had been growing during the incubation period. Ulva prolifera cultivated in a range of 10–20°C had a long growth cycle and the NRA decreased with increasing temperature when exceeded 15°C, a positive correlation between algal growth and NRA was observed. This study supports NRA is a suitable proxy of the effects of temperature changes on the ability of Ulva prolifera to uptake and metabolize nitrogen nutrients.

Influence of Temperature on Denitrification and Microbial Community Structure and Diversity: A Laboratory Study on Nitrate Removal from Groundwater

“…As the reaction progressed, DO was consumed by the denitrification, and its concentration became lower than 0.5 mg/L. According to a previous study, DO concentrations below 1mg/L are more conducive to the growth, reproduction, and accumulation of denitrifying bacteria[18]. Considering the change chart of the system's NO 3 − -N concentration (Figure1), NO 3 − -N concentration continuously declined until the end of the test.…”

“…Denitrification usually takes place between 2 • C and 50 • C or even higher, within which bacteria have adapted to a certain special environment, but it is the most effective between 25 • C and 35 • C [18]. However, investigations on the effects of temperature on denitrification are mostly concentrated in soil studies [19][20][21].…”

Weather induced physiological responses on the flowering habits of neem trees (Azadirachta indica)

“…The increase in nitrate reductase during the flowering phase, then a gradual decline was noted by Franco et al, (1979). Further the increased NRASE activity with increasing temperature was reported by Woodin and Lee, (1987) and Lina Feng et al, (2021). The weather induced increase in IAA oxidase activity of the neem tree during flowering also improved the growth, development and activity of root there by increased nitrogen absorption by the plant lead to high NRASE.…”