Effects of nitrogen and phosphorus on Microcystis aeruginosa growth and microcystin production

2022 ◽  
Vol 11 (1) ◽  
pp. 64-70
Author(s):  
Benjun Zhou ◽  
Zhen Wang
Keyword(s):  
Growth Rate ◽  
Microcystis Aeruginosa ◽  
Optical Density ◽  
Culture Medium ◽  
Optimal Growth ◽  
N:P Ratio ◽  
Nutrient Stress ◽  
Nitrogen And Phosphorus ◽  
Microcystin Production ◽  
N Starvation

Abstract In the present study, the effects of nitrogen (N) and phosphorus (P) on the growth of Microcystis aeruginosa and the production of microcystins (MCs) were investigated. The results showed that the growth of M. aeruginosa was not merely determined by N or P, but both nutrients were limiting for the species. Moreover, an excess of N and constant P in the culture medium could stimulate the growth of M. aeruginosa, whereas the growth of the species was inhibited in the culture medium containing excess of P and constant N. The optimal growth of M. aeruginosa was at an N:P ratio of 0.1 with the maximal optical density of 1.197 at 680 nm (OD680), whereas the maximal microcystin-LR (MC-LR) content of 228.2 μg·L−1 observed in the culture medium with an N:P ratio of 5. Interestingly, MC-LR production occurred under conditions of N starvation, thereby suggesting that the growth rate of M. aeruginosa was not related to MC-LR production under conditions of nutrient stress.

scholarly journals A critical intracellular concentration of fully reduced non-methylated folate polyglutamates prevents macrocytosis and diminished growth rate of human cell line K562 in culture

1983 ◽  
Vol 214 (2) ◽  
pp. 465-470 ◽  
Author(s):  
D Watkins ◽  
B A Cooper
Keyword(s):  
Growth Rate ◽  
Cell Line ◽  
Culture Medium ◽  
K562 Cells ◽  
Optimal Growth ◽  
Human Cell Line ◽  
Intracellular Concentration ◽  
Folate Concentration ◽  
Rate Of Growth ◽  
Optimal Growth Rate

Growth rate of human leukaemic cell line K562 was independent of intracellular folate concentration when this was greater than 1.5 microM. When intracellular folate concentration was less than 1.5 microM, the rate of growth was proportional to the logarithm of intracellular concentration of non-methylated fully reduced folates, but not to the logarithm of the intracellular concentration of N5-methyltetrahydropteroylglutamate. Intracellular folate concentration sufficient to support an optimal growth rate was maintained by either DL-N5-formyltetrahydropteroylglutamate or DL-N5-methyltetrahydropteroylglutamate at a 100-fold lower concentration than pteroylglutamate. Addition of hypoxanthine to culture medium partially restored growth of folate-depleted cells: thymidine had no effect on growth rate either alone or in combination with thymidine. Folate-depleted cells with diminished growth rate were larger than replete cells, but did not have megaloblastic morphology. The mitotic index was not decreased in cultures with diminished growth rate. The rate of growth and cell size of K562 cells is thus dependent on a critical intracellular concentration of non-methylated tetrahydrofolates, which may be maintained by different concentrations of either reduced folates or pteroylglutamate.

scholarly journals The effects of nutrient stress on marine microalgae for enhancing the biodiesel production

2020 ◽  
Vol 2 (3) ◽  
pp. 27-34
Author(s):  
Marlen Trejo ◽  
Evelyn Zamudio Pérez
Keyword(s):  
Growth Rate ◽  
Green Algae ◽  
Nutrient Stress ◽  
Biodiesel Production ◽  
Hexadecanoic Acid ◽  
Undecanoic Acid ◽  
Nitrogen And Phosphorus ◽  
Chlorella Sp ◽  
Main Factors ◽  
Vital Parameters

This study aimed to investigate the effect of nutrient stress such as nitrogen and phosphorus on the growth rate of green algae, Chlorella sp. and the mechanism secreted to survive during the depletion of nutrients. The sample was tested with several vital parameters, suppressed Total Nitrogen (TN) and Total Phosphorus (TP). A process known as acclimatization was carried out to ensure that the algae can adapt to a new environment which was repeated 2 times, each taking about 2 weeks. The active compounds in the samples were measured using Gas Chromatography-Mass Spectrophotometry. The experiments showed that the control microalgae secreted hexadecanoic acid and methyl stearate while nitrogen suppressed microalgae secreted Undecanoic acid, 10-methyl- and methyl ester. Phosphorus limited microalgae secreted 1,3-Propanediamine, N-(2-aminoethyl)- due to suppress of nutrients. This experiment should be tested in several study areas in Mexico and outside Mexico to compare the productivity of green algae and the main factors that contribute to the eutrophication problem.

Influence of increased nutrient supply on Microcystis aeruginosa at cellular and proteomic levels

2020 ◽  
Vol 85 ◽  
pp. 47-58
Author(s):  
Y Jiang ◽  
Y Liu
Keyword(s):  
Microcystis Aeruginosa ◽  
Regulatory Protein ◽  
Acid Synthesis ◽  
Nutrient Supply ◽  
Nitrogen Supply ◽  
Nitrogen And Phosphorus ◽  
Comprehensive Description ◽  
Amino Acid Synthesis ◽  
High Nutrient ◽  
Proteomic Responses

Various studies have observed that increased nutrient supply promotes the growth of bloom-forming cyanobacteria, but only a limited number of studies have investigated the influence of increased nutrient supply on bloom-forming cyanobacteria at the proteomic level. We investigated the cellular and proteomic responses of Microcystis aeruginosa to elevated nitrogen and phosphorus supply. Increased supply of both nutrients significantly promoted the growth of M. aeruginosa and the synthesis of chlorophyll a, protein, and microcystins. The release of microcystins and the synthesis of polysaccharides negatively correlated with the growth of M. aeruginosa under high nutrient levels. Overexpressed proteins related to photosynthesis, and amino acid synthesis, were responsible for the stimulatory effects of increased nutrient supply in M. aeruginosa. Increased nitrogen supply directly promoted cyanobacterial growth by inducing the overexpression of the cell division regulatory protein FtsZ. NtcA, that regulates gene transcription related to both nitrogen assimilation and microcystin synthesis, was overexpressed under the high nitrogen condition, which consequently induced overexpression of 2 microcystin synthetases (McyC and McyF) and promoted microcystin synthesis. Elevated nitrogen supply induced the overexpression of proteins involved in gas vesicle organization (GvpC and GvpW), which may increase the buoyancy of M. aeruginosa. Increased phosphorus level indirectly affected growth and the synthesis of cellular substances in M. aeruginosa through the mediation of differentially expressed proteins related to carbon and phosphorus metabolism. This study provides a comprehensive description of changes in the proteome of M. aeruginosa in response to an increased supply of 2 key nutrients.

The inverse correlation between growth rate and cell carbohydrate content of Microcystis aeruginosa

2009 ◽  
Vol 22 (1) ◽  
pp. 105-107 ◽  
Author(s):  
Chong Wang ◽  
Hai-nan Kong ◽  
Sheng-bing He ◽  
Xiang-yong Zheng ◽  
Chun-jie Li
Keyword(s):  
Growth Rate ◽  
Microcystis Aeruginosa ◽  
Inverse Correlation ◽  
Carbohydrate Content

scholarly journals 261 Increasing dietary amylose reduces rate of starch digestion and increases microbial fermentation in weaned pigs

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 86-86
Author(s):  
F P Y Tan ◽  
L F Wang ◽  
E Beltranena ◽  
R T Zijlstra
Keyword(s):  
Growth Rate ◽  
Block Design ◽  
Optimal Growth ◽  
Metabolite Profile ◽  
Proximal Colon ◽  
Starch Digestion ◽  
Gut Health ◽  
Weaned Pigs ◽  
Ileal Digestibility ◽  
Beneficial Effects

Abstract Beneficial effects of SCFA in modulating gut health stimulated interest on dietary strategies to increase intestinal microbial activity and digesta SCFA. Amylose has lower apparent ileal digestibility (AID) than amylopectin. In the large intestine, undigested starch is fermented by microbes producing SCFA. The objective was to determine effects of increasing dietary amylose on starch flow and metabolite profile along the intestinal tract in weaned pigs. Weaned pigs (n=32; initial BW, 8.4 kg) were randomly allocated to 4 diets containing 67% starch with 0, 20, 35, or 70% amylose in a randomized complete block design. On day 21, pigs were euthanized to collect digesta and feces for evaluating starch digestion and metabolite profiles. Apparent hindgut fermentation (AHF) was calculated as apparent total tract digestibility minus AID. Feed intake was 12% lower (P < 0.05) and growth rate was 18% lower (P < 0.05) for pigs fed 70% amylose than pigs fed 0, 20, or 35% amylose. Feed efficiency was greatest (P < 0.05) for pigs fed with 35% amylose. The AID of starch was 44% lower (P < 0.05) in pigs fed 70% amylose. Starch was completely digested by the proximal colon in pigs fed 0, 20, or 35% amylose, but AHF of starch was 14% greater (P < 0.05) in pigs fed 70% amylose. Increasing dietary amylose did not alter digesta SCFA in the small intestine, but increased (P < 0.05) digesta SCFA in the cecum, specifically acetate and total SCFA, and increased (P < 0.05) propionate and valerate in all sections of the colon. In conclusion, increasing dietary amylose in weaned pigs stimulated hindgut fermentation of starch with a corresponding increase in digesta total SCFA in the cecum and colon. Optimizing dietary amylose may exert its effect as dietary prebiotic while promoting an optimal growth rate in young pigs.

scholarly journals Feedback Regulation between Aquatic Microorganisms and the Bloom-Forming Cyanobacterium Microcystis aeruginosa

2019 ◽  
Vol 85 (21) ◽  
Author(s):  
Meng Zhang ◽  
Tao Lu ◽  
Hans W. Paerl ◽  
Yiling Chen ◽  
Zhenyan Zhang ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Microcystis Aeruginosa ◽  
Lake Taihu ◽  
Inorganic Nitrogen ◽  
Microbial Community Composition ◽  
Nitrogen And Phosphorus ◽  
Content Type ◽  
Coculture System ◽  
Eukaryotic Microorganisms ◽  
Aquatic Microorganisms

ABSTRACT The frequency and intensity of cyanobacterial blooms are increasing worldwide. Interactions between toxic cyanobacteria and aquatic microorganisms need to be critically evaluated to understand microbial drivers and modulators of the blooms. In this study, we applied 16S/18S rRNA gene sequencing and metabolomics analyses to measure the microbial community composition and metabolic responses of the cyanobacterium Microcystis aeruginosa in a coculture system receiving dissolved inorganic nitrogen and phosphorus (DIP) close to representative concentrations in Lake Taihu, China. M. aeruginosa secreted alkaline phosphatase using a DIP source produced by moribund and decaying microorganisms when the P source was insufficient. During this process, M. aeruginosa accumulated several intermediates in energy metabolism pathways to provide energy for sustained high growth rates and increased intracellular sugars to enhance its competitive capacity and ability to defend itself against microbial attack. It also produced a variety of toxic substances, including microcystins, to inhibit metabolite formation via energy metabolism pathways of aquatic microorganisms, leading to a negative effect on bacterial and eukaryotic microbial richness and diversity. Overall, compared with the monoculture system, the growth of M. aeruginosa was accelerated in coculture, while the growth of some cooccurring microorganisms was inhibited, with the diversity and richness of eukaryotic microorganisms being more negatively impacted than those of prokaryotic microorganisms. These findings provide valuable information for clarifying how M. aeruginosa can potentially modulate its associations with other microorganisms, with ramifications for its dominance in aquatic ecosystems. IMPORTANCE We measured the microbial community composition and metabolic responses of Microcystis aeruginosa in a microcosm coculture system receiving dissolved inorganic nitrogen and phosphorus (DIP) close to the average concentrations in Lake Taihu. In the coculture system, DIP is depleted and the growth and production of aquatic microorganisms can be stressed by a lack of DIP availability. M. aeruginosa could accelerate its growth via interactions with specific cooccurring microorganisms and the accumulation of several intermediates in energy metabolism-related pathways. Furthermore, M. aeruginosa can decrease the carbohydrate metabolism of cooccurring aquatic microorganisms and thus disrupt microbial activities in the coculture. This also had a negative effect on bacterial and eukaryotic microbial richness and diversity. Microcystin was capable of decreasing the biomass of total phytoplankton in aquatic microcosms. Overall, compared to the monoculture, the growth of total aquatic microorganisms is inhibited, with the diversity and richness of eukaryotic microorganisms being more negatively impacted than those of prokaryotic microorganisms. The only exception is M. aeruginosa in the coculture system, whose growth was accelerated.

scholarly journals UTILITY MAXIMIZATION IN A BINOMIAL MODEL WITH TRANSACTION COSTS: A DUALITY APPROACH BASED ON THE SHADOW PRICE PROCESS

2014 ◽  
Vol 17 (04) ◽  
pp. 1450022 ◽  
Author(s):  
CHRISTIAN BAYER ◽  
BEZIRGEN VELIYEV
Keyword(s):  
Growth Rate ◽  
Asymptotic Expansion ◽  
Transaction Costs ◽  
Continuous Time ◽  
Shadow Price ◽  
Optimal Growth ◽  
Order Effect ◽  
Explicit Construction ◽  
Binomial Model ◽  
Price Process

We consider the problem of optimizing the expected logarithmic utility of the value of a portfolio in a binomial model with proportional transaction costs with a long time horizon. By duality methods, we can find expressions for the boundaries of the no-trade-region and the asymptotic optimal growth rate, which can be made explicit for small transaction costs (in the sense of an asymptotic expansion). Here we find that, contrary to the classical results in continuous time, see Janeček and Shreve (2004), Finance and Stochastics8, 181–206, the size of the no-trade-region as well as the asymptotic growth rate depend analytically on the level λ of transaction costs, implying a linear first-order effect of perturbations of (small) transaction costs, in contrast to effects of orders λ1/3 and λ2/3, respectively, as in continuous time models. Following the recent study by Gerhold et al. (2013), Finance and Stochastics17, 325–354, we obtain the asymptotic expansion by an almost explicit construction of the shadow price process.

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