Cross-Effects of Nitrogen and Sulphur Starvation in <i>Chlorella sorokiniana</i> 211/8K

Abstract

Nitrogen (N) and sulphur (S), being essential macronutrients, have important roles in microalgae metabolism. Effects of N-or S-shortage were investigated in the green microalgae Chlorella sorokiniana subjected to 24 h of starvation, by measuring the glutamine synthetase (GS) and O-acetylserine(thiol)lyase (OASTL) activities, proteins and amino acids levels. To test possible metabolic impact related to carbon (C) metabolism in response to N-or S-deprivation, starch and total C, N and S contents were also determined. The growth of C. sorokiniana cells was affected by N or S availability. The algae cultured for 24 h in a medium deprived of nitrogen or sulphur showed a decrease in the growth rate and changes in the average volume cell. Nitrogen starvation affected proteins level in the algae cells more than S-deprivation did. The decline in the protein levels observed under S-deficient conditions was coupled with the accumulation of the amide glutamine and with OASTL activity increase; additionally, N-deficiency promoted a decrease in cysteine (Cys) levels (50%) and an increase in GS activity. Nevertheless, S-deprivation had negligible effects on GS activity, while N-deprivation significantly affected OASTL activity. Total C was also estimated in cells N-or S-deprived; nitrogen deprivation strongly affected total C content more than S-deprivation, which in addition reduced the content of C and N, but leaves intact their ratios. Our results support the hypothesis that in Chlorella sorokiniana cells a reciprocal influence of N, S and C assimilation occurs.

Influence of Sulphate Nutrition on Growth Performance and Antioxidant Enzymes Activities of Spirulina platensis

“…The lower number of filaments, biomass, cell productivity and maximum specific growth rate at lower concentration of K 2 SO 4 (0.16 g/L) are in agreement with those reported by Wagih El-Shouny et al (2015) which showed that the reduction of sulphur in the culture medium involved non significant reduction in the growth of the biomass and productivity of S. platensis. Moreover low yield of growth recorded in media in with low potassium sulphate concentrations could be because sulphur deficiency could cause a reduction in the cell multiplication while influencing on metabolism of carbon in photosynthetic activity as reported by Carfagna et al (2015) to Chlorella sorokiniana. Therefore, in media supplemented with different concentrations of sulphate salts, the best number of filaments, biomass, cell productivity and maximum specific growth rate were recorded on medium supplemented with MgSO 4 /K 2 SO 4 (0.02/0.14 g/L).…”

Enhancement of active ingredients and biological activities of Nostoc linckia biomass cultivated under modified BG-110 medium composition

“…The obtained results coincided with the results reported by Zalutskaya et al [ 48 ] on Chlamydomonas reinhardtii , where any stimulus (as sulfur starvation) causes the cytochrome-pathway complex dysfunction in mitochondrial electron transport chains, which led to the induction and expression of alternative oxidase 1 and 2 genes. Moreover, under sulfur starvation condition, photosynthetic activity and metabolism are affected [ 49 ].…”

Extraction and Activity of O-acetylserine(thiol)lyase (OASTL) from Microalga Chlorella sorokiniana

“…Copyright © 2017 The Authors; exclusive licensee Bio-protocol LLC. 6 3. OASTL activity was expressed in units that correspond to the formation of 1 µmol of cysteine min -1 .…”