Optimal Phosphate Concentration Research Articles

Transcriptomic analyses reveal the upregulation of the fatty acids metabolism genes in Thalassiosira weissflogii during low optimal phosphate concentration

Fatty acids from microalgae like Thalassiosira weissflogii are valuable for various applications, including aquaculture feed. Maximising the percentage of fatty acids with total lipids relies on several cultivation variables, including the amount of phosphate in the culture media. While it's known that factors like phosphate levels can affect lipid and fatty acid production, the specific impact of low phosphate on T. weissflogii has not been well-studied. Thus, this study aims to determine how different low phosphate concentrations influence biomass, lipid content, and fatty acid production in T. weissflogii. In addition, this study also seeks to determine the potential molecular responses of T. weissflogii in optimum low phosphate concentrations. T. weissflogii were cultured in four different phosphate concentrations—0.064, 0.129, 0.193, and 0.258 μM, and accumulation of biomass, total lipids, and fatty acids were measured. A phosphate concentration of 0.064 μM was recorded to produce the highest biomass (27.47 g/L), total lipids (28.36 %), and eicosapentaenoic (EPA) fatty acid (6.83 mg/g). The transcriptome profiling under the optimal low phosphate concentration of 0.064 μM identified 40,212 differential expressed genes (DEGs), including FabG, FAD2, HSD17B12, and FadD genes in the significant fatty acid metabolism pathways. These findings suggested that 0.064 μM phosphate concentrations should be used in T. weissflogii cultivation. Further work should be undertaken to determine how allelic variation in upregulated genes in combination with phosphate concentration affects biomass, total lipids, and high-value fatty acids in T. weissflogii. In addition, genetic improvement through genetic selection or gene editing experiments in T. weissflogii could be explored to optimise feeds to enhance the growth and health of aquaculture species, including finfish and shellfish.

Effects of phosphorus on the growth and chlorophyll fluorescence of a Dunaliella salina strain isolated from saline soil under nitrate limitation

An isolated <em>Dunaliella salina</em> (<em>D. salina</em>) KU XI from saline soils in northeastern Thailand was cultured in f/2 medium in column photobioreactor. The variations of the growth, chlorophyll and beta-carotene content and the maximum quantum yield of PS II photochemistry (F<sub>v</sub>/F<sub>m</sub>) under different NaH<sub>2</sub>PO<sub>4</sub> concentrations were studied. Based on the results, the growth kinetics of <em>D. salina</em> KU XI was established, which could simulate the algae growth rate under different phosphate concentrations and temperatures. The phosphorus could significantly affect the growth and pigments accumulations of this isolated strain. Increasing NaH<sub>2</sub>PO<sub>4</sub> concentration improved the biomass, the total chlorophyll and beta-carotene content, retarded the decrease of F<sub>v</sub>/F<sub>m</sub> value. The optimal phosphate concentration for the growth of <em>D. salina</em> KU XI was above 72.6 μM. The maximum biomass and beta-carotene were 0.24 g L<sup>-1</sup> and 17.4 mg L<sup>-1</sup> respectively when NaH<sub>2</sub>PO<sub>4</sub> was 290.4 μM. The algae growth was restrained by phosphate or nitrate when NaH<sub>2</sub>PO<sub>4</sub> below 12.1 μM or above 72.6 μM. It indicated that properly supplementing nitrate in the late growth stage with high phosphate concentration was favored for enhancing the growth and biomass production.

A kinetic model of one-pot rapid biotransformation of cellobiose from sucrose catalyzed by three thermophilic enzymes

Cellobiose is a zero-calorie functional sweetener and a potential healthy food/feed additive. Current production methods of cellobiose from high-purity cellulose always suffer from low product yields and high separation costs. Here one-pot biotransformation composed of three thermophilic enzymes sucrose phosphorylase (SP) from Thermoanaerobacterium thermosaccharolyticum, glucose isomerase (GI) from Streptomyces murinus, and cellobiose phosphorylase (CBP) from Clostridium thermocellum was designed to convert sucrose to cellobiose. To reveal the underlying relationship within the three enzymes and optimize reaction conditions, a kinetic model was developed. Model simulation predicted the optimal SP:GI:CBP enzyme loading ratio in terms of enzyme unit was 0.5:1.0:1.5. The enzyme cocktail with the optimal ratio converted 100mM sucrose to 62.3mM cellobiose within 10h. Model simulation also found out that the optimal phosphate concentration was approximately 10.3mM for 100mM sucrose, which was validated by experimental data. This study could assist the sugar industry to diversify the production of new value-added products from sucrose.

Use of physiological information and process optimisation enhances production of extracellular nuclease by a marine strain of Bacillus licheniformis

The extracellular nuclease, NucB, from Bacillus licheniformis, can digest extracellular DNA in biofilms, causing biofilm dispersal, and may therefore be used commercially to remove biofilms. However, producing quantities of this secreted peptide is difficult and our aim was therefore to improve its laboratory scale production. This study builds on our understanding of B. licheniformis physiology to enhance NucB production. The addition of manganese, which triggers sporulation and enhances NucB expression, lead to a 5-fold increase in NucB production. Optimisation via Placket–Burman design of experiments identified 3 significant medium components and a subsequent Central Composite Design, to determine the optimum levels of these components, resulted in a 10-fold increase to 471U/ml. The optimal phosphate concentration was less than 0.3mM as this is known to inhibit nuclease production. The use of physiologically relevant information combined with optimisation represents a promising approach to increased enzyme production, which may also be widely applicable.

Development and implementation of standardized respiratory chain spectrophotometric assays for clinical diagnosis

Diversity of respiratory chain spectrophotometric assays may lead to difficult comparison of results between centers. The French network of mitochondrial diseases diagnostic centers undertook comparison of the results obtained with different protocols in the French diagnostic centers. The diversity of protocols was shown to have striking consequences, which prompted the network to undertake standardization and optimization of the protocols with respect to clinical diagnosis, i.e. high velocity while maintaining linear kinetics relative to time and enzyme concentration. Assays were set up on animal tissues and verified on control human muscle and fibroblasts. Influence of homogenization buffer and narrow range of optimal concentration of phosphate, substrate and tissue were shown. Experimental data and proposed protocols have been posted on a free access website. Their subsequent use in several diagnostic centers has improved consistency for all assays.

Macronutrients requirements of the dinoflagellate Protoceratium reticulatum

The basal L1 medium was found to be unsatisfactory for culturing the red tide dinoflagellate Protoceratium reticulatum at a high growth rate and biomass yield. The L1 medium enhanced with phosphate to a total concentration of 217 μM supported the highest attainable growth rate and biomass yield. Once the phosphate concentration exceeded 6× L1, phosphate inhibited the dinoflagellate growth and negatively affected cell viability. At the optimal phosphate concentration of 217 μM, an increase in nitrate concentration over the range of 882–8824 μM, did not affect cell growth and yield. Nitrate did not inhibit growth at any of the concentrations used. Clearly, the basal nitrate level in L1 is sufficient for effectively culturing P. reticulatum. At the ranges of phosphate and nitrate concentrations tested, cell volume was not sensitive to the concentration of nutrients but the concentration of phosphate affected both the specific cell number and cell volume growth rates. Elevated levels of nutrients supported their intracellular accumulation. Cell-specific production of yessotoxin was not influenced by concentration of phosphate in the culture medium, but elevated (>1764 μM) nitrate concentration did enhance the yessotoxin level. Phosphate concentration that maximized biomass yield also maximized volumetric production of yessotoxin in the culture broth.

Effect of Phosphate on Cell Growth and Polysaccharide Production by Suspension Cultures of Protocorm-like Bodies of Dendrobium huoshanense

The effect of inorganic phosphate on the cell growth and accumulation of polysaccharides together with nutrient utilization was investigated in suspension cultures of protocorm-like bodies of Dendrobium huoshanense. Thirty-day-old cells were transferred into a liquid medium with the inoculum density of 100 g/L cells. The results indicated that the optimal concentration of phosphate in the medium for the growth of protocorm-like bodies of Dendrobium huoshanense was 2.5 mmol/L and the biomass was 496.5 g/L (fresh weight). The phosphate was a limiting factor for the cell growth and there was a relationship between the levels of intracellular phosphate and the cell growth. A total of 2.5 mmol/L of medium phosphate was beneficial to the absorption of carbon and nitrogen source. A total of 0.312 mmol/L of medium phosphate was better for the accumulation of polysaccharides and the production of polysaccharides was 2.22 g/L on day 36.

Residual phosphate concentration under nitrogen-limiting conditions regulates curdlan production in Agrobacterium species

We investigated the influence of inorganic phosphate concentration on the production of curdlan by Agrobacterium species. A two-step culture method was employed where cells were first cultured, followed by curdlan production under nitrogen-limiting conditions. In the curdlan production step, cells did not grow but metabolized sugar into curdlan. Shake-flask experiments showed that the optimal phosphate concentration for curdlan production was in the range of 0.1–0.3 g l−1. As the cell concentration increased from 0.42 to 1.68 g l−1 in shake-flask cultures, curdlan production increased from 0.44 to 2.80 g l−1. However, the optimal phosphate concentration range was not dependent upon cell concentration. The specific production rate was about 70 mg curdlan g-cell−1 h−1 irrespective of cell concentration. When the phosphate concentration was maintained at 0.5 g l−1 under nitrogen-limiting conditions, as high as 65 g l−1 of curdlan was obtained in 120 h. Journal of Industrial Microbiology & Biotechnology (2000) 25, 180–183.

Slow-Release Fertilizer for Rehabilitating Oligotrophic Streams: a Physical Characterization

Abstract A combination of habitat degradation and overharvesting of anadromous salmonids in many of B.C.’s oligotrophic watersheds has prompted the addition of inorganic nutrients to streams, which increases autotrophic production and aids in the restoration of salmonid production. A new slow-release fertilizer (7-40-0, N-P2O5-K2O, percent by weight) was examined to determine its phosphate (PO43-) release rates using laboratory and field trough experiments. A series of indoor trough experiments indicated that the fertilizer pellet dissolution rate (0.393 g ? days-0.401) was independent of the experimental range of water velocity (0.03-0.30 m . s-1), fertilizer pellet size (2–9 g) and water temperature (8–14.5°C). Resulting phosphate additions (0.5-5 µg P . L-1) in outdoor trough experiments increased periphyton biomass and altered the dominance pattern of periphytic diatoms. An optimal phosphate concentration for periphyton biomass was achieved with calculated 3.0 µg P . L-1 phosphate additions from May to June. In June to July, periphyton biomass increased proportionately to fertilizer additions. Saturation of the relative specific growth rate of the diatom community occurred with 1.0 µg P . L-1 phosphate additions. Nitrogen analysis was not conducted since inorganic nitrogen is typically available in non-limiting concentrations (i.e., >50 µg . L-1 dissolved inorganic nitrogen) in the majority of B.C.’s oligotrophic salmonid streams. These studies indicated that slow-release fertilizer may be effective in stimulating autotrophic production and restoring salmonid production in nutrient deficient streams.

Phosphate effect on production of ginseng saponin and polysaccharide by cell suspension cultures of Panax ginseng and Panax quinquefolium

The effects of inorganic phosphate on cell growth, accumulation of ginseng saponin (secondary metabolite) and ginseng polysaccharide (primary metabolite), together with nutrient utilisation, were investigated in suspension cultures of Panax ginseng (PG) and Panax quinquefolium strain Q91625 (PQ). The results indicate that the crucial concentration of phosphate for cell growth of PG and PQ was 1·04 and 0·65 m m, respectively. Bound phosphorus content for PG and PQ cells was determined to be 4 and 7 mg P/g DW, respectively, which suggested a more urgent demand of phosphate during cell cultivation of PQ. For simultaneous production of ginseng saponin and polysaccharide, the optimal concentration of phosphate in PG cell cultures was 0·42 m m, and saponin and polysaccharide accumulation was 643 mg litre −1 and 2·18 g litre −1, respectively; 1·25 m m of medium phosphate was the best for biosyntheses of saponin (960 mg litre −1) and polysaccharide (1·8 g litre −1) by PQ cell cultures.

Sensitivity of Fusarium oxysporum f. sp. cubense to phosphonate

Phosphonate (0.1 mM) significantly reduced growth of Fusarium oxysporum f. sp. cubense (Foc) race 4 grown at an optimal phosphate concentration of 0.3 mM in vitro. At higher phosphate concentrations, closer to physiological conditions within the plant, the sensitivity of Foc race 4 to phosphonate was greatly reduced, with 25 mM phosphonate required to reduce growth by 50% at 1 mM phosphate. Two isolates of Fusarium oxysporum f. sp. dianthi and another race of Foc, race 1, were shown to be similar to Foc race 4 in their sensitivity to phosphonate, while another species of Fusarium, F. avenaceum, was more sensitive to phosphonate in vitro.

The Effects of Phosphorus and Magnesium on Sclerotium Formation in Rhizoctonia solani Kuehn.

None or very few sclerotia of Rhizoctonia solani (AG-1, IA) were formed on Hopkins agar medium without KH2PO4, though hyphae developed in some extent. While, the number and weight of sclerotia were decreased when MgSO4 was absent. As KH2PO4 in the basal medium was replaced with other phosphates different in cation, sclerotia were well formed. The optimal concentration of phosphate as KH2PO4 for the sclerotium formation, in number and weight, and hyphal development was in the region of 100ppm. The addition of magnesium resulted in the increase of the number and weight of sclerotia proportionally with the amount of the magnesium compound. The results indicate that phosphorus ion is indispensable to the sclerotium formation, whereas magnesium ion is promotive. The absence of phosphorus at the maturing stage resulted in the formation of few sclerotia, even though phosphorus was presented at the hyphal and initial phases. While defficiency of phosphorus in the early stage of sclerotium development showed no effect on the number and weight of sclerotia formed, if the phosphorus was supplied in subsequent periods. The branching internodes of hyphae grown on the phos-phorus free medium were longer than those of on the medium containing phosphorus. This decrease of the hyphal branching will lead to the decrease of interweaving hyphae and will result in the scarce sclerotium formation. A large accumulation of 32P to sclerotia was strikingly observed in this experiment.

Inhibitory effects of 2,3-dpg on enzymes of purine nucleotide metabolism

The effect of 2,3-diphosphoglycerate (2,3-DPG) upon three partially purified enzymes from human erythrocytes, 5-phosphoribosyl-l-pyrophosphate synthetase (PRibPP synthetase, E.C.2.7.6.1), IMP:pyrophosphate phosphoribosyltransferase (E.C.2.4.2.8 HPRibTase) and AMP:pyrophosphate phosphoribosyltransferase (E.C.2.4.2.7 APRibTase) has been studied kinetically. PRibPP synthetase was not greatly inhibited at physiologic concentrations of 2,3-DPG at optimal phosphate concentration, but it was inhibited appreciably by 2,3-DPG at physiologic phosphate levels. Both HPRibTase and APRibTase were inhibited by 2,3-DPG at its normal intracellular concentration. 2,3-DPG is a competitive inhibitor with respect to the substrates, ribose-5-phosphate and 5-phosphoribosyl-l-pyrophosphate. The Ki values for these inhibitions are given and the possible physiologic significance of these findings are discussed.

Inhibitors of nitrogen fixation in extracts from Clostridium pasteurianum

The gases H 2, CO, N 2O, and NO specifically inhibited the “nitrogenase” system in extracts from Clostridium pasteurianum. Concentrations of inhibitor effective against N 2 fixation did not substantially inhibit pyruvate metabolism. All the inhibitors acted competitively, although H 2 inhibition was uncompetitive at a higher than optimal phosphate concentration. Evacuation, following preincubation with the gaseous inhibitors, relieved all inhibitions. Cyanide and azide were weak inhibitors of N 2 fixation. These results are discussed with respect to the nature of the N 2-binding site and the mechanism of N 2 fixation.