Carbohydrate Production Research Articles

Metabolic responses of Euglena gracilis under photoheterotrophic and heterotrophic conditions

The protist Euglena gracilis has various trophic modes including heterotrophy and photoheterotrophy. To investigate how cultivation mode influences metabolic regulation, the chemical composition of cellular metabolites of Euglena gracilis grown under heterotrophic and photoheterotrophic conditions was monitored from the early exponential phase to the mid-stationary phase using two different techniques, i.e, nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry (HRMS). The combined metabolomics approach allowed an in-depth understanding of the mechanism of photoheterotrophic and heterotrophic growth for biomolecule production. Heterotrophic conditions promoted the production of polar amino and oxygenated compounds such as proteins and polyphenol compounds, especially at the end of the exponential phase while photoheterotrophic cells enhanced the production of organoheterocyclic compounds, carbohydrates, and alkaloids.

Influence of salinity, nitrogen and phosphorus concentrations on the physiological and biochemical characteristics of two Chlorophyceae isolated from Fez freshwater, Morocco

Microalgae are widely exploited for numerous biotechnology applications, including biofuels. In this context, Chlamydomonas debaryana and Chlorococcum sp. were isolated from Fez freshwater (Morocco), and their growth and lipid and carbohydrate production were assessed at different concentrations of NaCl, NaNO3, and K2HPO4. The results indicate a small positive variation in growth parameters linked to nutrient enrichment, with no considerable variation in carbohydrate and lipid levels in both algae. Moreover, a negative variation was recorded at increased salinity and nutrient limitation, accompanied by lipid and carbohydrate accumulation. Chlorococcum sp. showed better adaptation to salt stress below 200 mM NaCl. Furthermore, its growth and biomass productivity were strongly reduced by nitrogen depletion, and its lipid production reached 47.64% DW at 3.52 mM NaNO3. As for Chlamydomonas debaryana, a substantial reduction in growth was induced by nutrient depletion, a maximal carbohydrate level was produced at less than 8.82 mM NaNO3 (40.59% DW). The effect of phosphorus was less significant. However, a concentration of 0.115 mM K2HPO4 increased lipid and carbohydrate content without compromising biomass productivity. The results suggest that growing the two Chlorophyceae under these conditions seems interesting for biofuel production, but the loss of biomass requires a more efficient strategy to maximize lipid and carbohydrate accumulation without loss of productivity.

Salt and heat stress enhances hydrogen production in cyanobacteria.

Cyanobacteria are among the most suitable organisms for the capture of excessive amounts of CO2 and can be grown in extreme environments. In our research we use the single-celled freshwater cyanobacteria Synechococcus elongatus PCC7942 PAMCOD strain and Synechocystis sp. PCC6714 for the production of carbohydrates and hydrogen. PAMCOD strain and Synechocystis sp. PCC6714 synthesize sucrose when exposed to salinity stress, as their main compatible osmolyte. We examined the cell proliferation rate and the sucrose accumulation in those two different strains of cyanobacteria under salt (0.4M NaCl) and heat stress (35 0C) conditions. The intracellular sucrose (mol sucrose content per Chl a) was found to increase by 50% and 108% in PAMCOD strain and Synechocystis sp. PCC6714 cells, respectively. As previously reported, PAMCOD strain has the ability to produce hydrogen through the process of dark anaerobic fermentation (Vayenos D, Romanos GE, Papageorgiou GC, Stamatakis K (2020) Photosynth Res 146, 235-245). In the present study, we demonstrate that Synechocystis sp. PCC6714 has also this ability. We further examined the optimal conditions during the dark fermentation of PAMCOD and Synechocystis sp. PCC6714 regarding H2 formation, increasing the PAMCOD H2 productivity from 2 nmol H2 h- 1 mol Chl a- 1 to 23 nmol H2 h- 1 mol Chl a- 1. Moreover, after the dark fermentation, the cells demonstrated proliferation in both double BG-11 and BG-11 medium enriched in NaNO3, thus showing the sustainability of the procedure.

Bioethanol production from dilute acid hydrolysis of cassava peels, sugar beet pulp, and green macroalgae (Ulva lactuca)

This study presents the characterization and application of different pretreatment possibilities to optimize simple carbohydrate production from representative feedstock, followed by ethanol production through optimized saccharification steps using suitable microorganisms. Total soluble carbohydrates and carbohydrate yield were evaluated using dilute acid hydrolysis of biomass and reference materials (starch and cellulose) under different conditions. To explore two-factor interactions, the Plackett-Burman design of experiments was used in the statistical screening of variables and then transformed to a full-factorial design based on the significant variables. According to the experimental findings, dilute acid hydrolysis can yield a considerable amount of soluble carbohydrates. The goodness of fit of the model was evaluated using the coefficient of determination. The optimized carbohydrate yields of the biomass were 0.76 g/g cassava peels, 0.35 g/g sugar beet pulp, and 0.36 g/g green macroalgae. Bioethanol production from optimized hydrolysis conditions using Saccharomyces cerevisiae and Scheffersomyces stipitis DSM 3651, led to a maximum ethanol yield of 0.286 g/g from cassava peels and 0.033 g/g from sugar beet pulp, while using Neurospora intermedia DSM 1265 led to a maximum ethanol yield of 0.076 g/g from green macroalgae. Hence, these biomasses are considered valuable feedstock for bioethanol production with cassava peels having the highest potential.

External aluminium supply regulates photosynthesis and carbon partitioning in the Al-accumulating tropical shrub Melastoma malabathricum.

Aluminium (Al) is toxic to most plants, but recent research has suggested that Al addition may stimulate growth and nutrient uptake in some species capable of accumulating high tissue Al concentrations. The physiological basis of this growth response is unknown, but it may be associated with processes linked to the regulation of carbon assimilation and partitioning by Al supply. To test alternative hypotheses for the physiological mechanism explaining this response, we examined the effects of increasing Al concentrations in the growth medium on tissue nutrient concentrations and carbon assimilation in two populations of the Al-accumulator Melastoma malabathricum. Compared to seedlings grown in a control nutrient solution containing no Al, mean rates of photosynthesis and respiration increased by 46% and 27%, respectively, total non-structural carbohydrate concentrations increased by 45%, and lignin concentration in roots decreased by 26% when seedlings were grown in a nutrient solution containing 2.0 mM Al. The concentrations of P, Ca and Mg in leaves and stems increased by 31%, 22%, and 26%, respectively, in response to an increase in nutrient solution Al concentration from 0 to 2.0 mM. Elemental concentrations in roots increased for P (114%), Mg (61%) and K (5%) in response to this increase in Al concentration in the nutrient solution. Plants derived from an inherently faster-growing population had a greater relative increase in final dry mass, net photosynthetic and respiration rates and total non-structural carbohydrate concentrations in response to higher external Al supply. We conclude that growth stimulation by Al supply is associated with increases in photosynthetic and respiration rates and enhanced production of non-structural carbohydrates that are differentially allocated to roots, as well as stimulation of nutrient uptake. These responses suggest that internal carbon assimilation is up-regulated to provide the necessary resources of non-structural carbohydrates for uptake, transport and storage of Al in Melastoma malabathricum. This physiological mechanism has only been recorded previously in one other plant species, Camellia sinensis, which last shared a common ancestor with M. malabathricum more than 120 million years ago.

Integrated small RNA, transcriptome and physiological approaches provide insight into Taxodium hybrid 'Zhongshanshan' roots in acclimation to prolonged flooding.

Although Taxodium hybrid 'Zhongshanshan' 406 (Taxodium mucronatum Tenore×Taxodium distichum; Taxodium 406) is an extremely flooding-tolerant woody plant, the physiological and molecular mechanisms underlying acclimation of its roots to long-term flooding remain largely unknown. Thus, we exposed saplings of Taxodium 406 to either non-flooding (control) or flooding for 2months. Flooding resulted in reduced root biomass, which is in line with lower concentrations of citrate, α-ketoglutaric acid, fumaric acid, malic acid and adenosine triphosphate (ATP) in Taxodium 406 roots. Flooding led to elevated activities of pyruvate decarboxylase, alcohol dehydrogenase and lactate dehydrogenase, which is consistent with higher lactate concentration in the roots of Taxodium 406. Flooding brought about stimulated activities of superoxide dismutase and catalase and elevated reduced glutathione (GSH) concentration and GSH/oxidized glutathione, which is in agreement with reduced concentrations of O2- and H2O2 in Taxodium 406 roots. The levels of starch, soluble protein, indole-3-acetic acid, gibberellin A4 and jasmonate were decreased, whereas the concentrations of glucose, total non-structural carbohydrates, most amino acids and 1-aminocyclopropane-1-carboxylate (ACC) were improved in the roots of flooding-treated Taxodium 406. Underlying these changes in growth and physiological characteristics, 12,420 mRNAs and 42 miRNAs were significantly differentially expressed, and 886 miRNA-mRNA pairs were identified in the roots of flooding-exposed Taxodium 406. For instance, 1-aminocyclopropane-1-carboxylate synthase 8 (ACS8) was a target of Th-miR162-3p and 1-aminocyclopropane-1-carboxylate oxidase 4 (ACO4) was a target of Th-miR166i, and the downregulation of Th-miR162-3p and Th-miR166i results in the upregulation of ACS8 and ACO4, probably bringing about higher ACC content in flooding-treated roots. Overall, these results indicate that differentially expressed mRNA and miRNAs are involved in regulating tricarboxylic acid cycle, ATP production, fermentation, and metabolism of carbohydrates, amino acids and phytohormones, as well as reactive oxygen species detoxification of Taxodium 406 roots. These processes play pivotal roles in acclimation to flooding stress. These results will improve our understanding of the molecular and physiological bases underlying woody plant flooding acclimation and provide valuable insights into breeding-flooding tolerant trees.

Optimation of the cell density, biomass production, lipid, and carbohydrate content of Nannochloropsis oculata with fluorescein and pH manipulation

Nannochloropsis oculata is a potential marine microalga. However, the mass production of N. oculata encounters several challenges, such as the high costs of resources, contamination, and light absorption optimization. These problems can be solved by pH manipulation and fluorescein induction on culture media. Various studies have shown that pH values manipulation can cause fluctuations in cell density, dry biomass, and carbohydrate and lipid production of microalgae. On the other hand, fluorescein can act as a molecular antenna that improves light absorption. This research is novel because of its focus on its unique attempt to utilize pH manipulation combined with fluorescein induction to enhance the growth and metabolite production of N. oculata. The implications of this research may provide cost-effective, viable, and sustainable development of the algal industry in general. In this research, cultivation was carried out for seven days with four levels of pH (7 – 10) combined with three variations of fluorescein addition (0, 0.15, and 0.3 mL). Every treatment combination had three replications. Cell density and biomass as growth analysis parameters were calculated during the cultivation using the Haemocytometer and gravimetric methods. Bligh & Dyer and phenol sulfate methods were used to analyze lipid and carbohydrate content. Based on the result, the best treatment combination, pH 9 with 0.15 mL of fluorescein, increases cell density and carbohydrate content of N. oculata by 31.45 and 4.4%, albeit not statistically significant.

The long-term expansion and recession of human populations

Over the last 12,000 y, human populations have expanded and transformed critical earth systems. Yet, a key unresolved question in the environmental and social sciences remains: Why did human populations grow and, sometimes, decline in the first place? Our research builds on 20 y of archaeological research studying the deep time dynamics of human populations to propose an explanation for the long-term growth and stability of human populations. Innovations in the productive capacity of populations fuels exponential-like growth over thousands of years; however, innovations saturate over time and, often, may leave populations vulnerable to large recessions in their well-being and population density. Empirically, we find a trade-off between changes in land use that increase the production and consumption of carbohydrates, driving repeated waves of population growth over thousands of years, and the susceptibility of populations to large recessions due to a lag in the impact of humans on resources. These results shed light on the long-term drivers of human population growth and decline.

Karakteristik nutrisi dalam yoghurt pada susu sapi, kambing dan oat

Background: Yogurt is a dairy product produced by fermenting milk using starter cultures such as Lactobacillus bulgaricus and Streptococcus thermophilus bacteria. The use of these bacteria is due to their role in producing lactic acid. With the involvement of these bacteria, the liquid milk coagulates and develops a distinctive acidic taste. Methods: The research method employed in this article is qualitative research using a literature review approach. Finding: Based on the study results, it was found that cow's milk undergoes an increase in protein and carbohydrate levels after being transformed into yogurt. Goat's milk experiences an increase in carbohydrate and calcium levels post-yogurt production. Meanwhile, oat milk shows an increase in ash concentration and protein levels. Conclusion: The comparative results indicate that each yogurt from different sources offers distinct nutritional advantages. Therefore, it is important to consider the body's nutritional needs before consumption.

Increased light intensity enhances photosynthesis and biochemical components of red macroalga of commercial importance, Kappaphycus alvarezii, in response to ocean acidification

The concentration of atmospheric carbon dioxide (CO2) has increased drastically over the past several decades, resulting in the pH of the ocean decreasing by 0.44 ± 0.005 units, known as ocean acidification (OA). The Kappaphycus alvarezii (Rhodophyta, Solieriaceae), is a commercially and ecologically important red macroalga with significant CO2 absorption potential from seawater. The K. alvarezii also experienced light variations from self-shading and varied cultivation depths. Thus, the aim of present study was to investigate the effects of two pCO2 levels (450 and 1200 ppmv) and three light intensities (50, 100, and 150 μmol photons·m−2·s−1) on photosynthesis and the biochemical components in K. alvarezii. The results of the present study showed that a light intensity of 50 μmol photons·m−2·s−1 was optimal for K. alvarezii photosynthesis with 0.663 ± 0.030 of Fv/Fm and 0.672 ± 0.025 of Fv’/Fm’. Phycoerythrin contents at two pCO2 levels decreased significantly with an increase in light intensity by 57.14–87.76%, while phycocyanin contents only decreased from 0.0069 ± 0.001 mg g−1 FW to 0.0047 ± 0.001 mg g−1 FW with an increase in light intensity at 1200 ppmv of pCO2. Moreover, moderate increases in light intensity and pCO2 had certain positive effects on the physiological performance of K. alvarezii, specifically in terms of increasing soluble carbohydrate production. Although OA and high light levels promoted total organic carbon accumulation (21.730 ± 0.205% DW) in K. alvarezii, they had a negative impact on total nitrogen accumulation (0.600 ± 0.017% DW).

The regulation of light quality on the substance production and photosynthetic activity of Dunaliella bardawil

To study the influence and regulation of light quality on the microalgal photosynthetic activity and production of biomass and substances, green alga Dunaliella bardawil was cultured in this study under the monochromatic red light (7R0B), blue light (0R7B), and their combinations with different ratios (xRyB, x + y = 7), as well as a control of white light (W). The results demonstrated that the only advantage for control W was its chlorophyll-a (Chl-a) and Chl-b contents. All substance production at 7R0B were much lower than at control W, except of glycerol. Compared to control W, protein production at 1R6B (259.22 mg/L) was 1.10 times greater, carbohydrate production at 0R7B (306.49 mg/L) was 1.34 times higher, lipid production at 3R4B (133.60 mg/L) was 1.36 times higher, and glycerol production at 4R3B (53.58 mg/L) was 1.13 times greater. In comparison to control W, there was the significant improvements of at least 19%, 20%, and 5%, respectively, in the values of potential maximal relative electron transport efficiency (rETRmax), light intensity with saturated rETR (IK), and actual photochemical efficiency of PSII (QYss) in treatments. The correlation analysis revealed that the content of carotenoids was closely related to non-photochemical quenching (NPQ). The test using Chl-a fluorescence transients (JIP-test) proved that red light inhibited electron transport from reduced Quinone A (QA−) to QB and resulted in a sharp increase in RC/CSm, and that the blue-dominated light enhanced electron transport from QA− to QB and from plastoquinone (PQ) to PSI receptor side. The photosynthetic parameters including Ψo, φEO, φRO, δRO, PIABS, PItotal, DFABS, and DFtotal, which were positively correlated with growth and substance production, were improved by blue-dominated light. The variations in the electron transport chain might provide the signals for metabolic regulation. The results of this study will be helpful to promote the production of Dunaliella bardawil under artificial illumination and to clarify the regulating mechanism of light quality on microalgal photosynthesis.

MORF9-dependent specific plastid RNA editing inhibits root growth under sugar starvation in Arabidopsis.

Multiple organellar RNA editing factor (MORF) complex was shown to be highly associated with C-to-U RNA editing of vascular plant editosome. However, mechanisms by which MORF9-dependent plastid RNA editing controls plant development and responses to environmental alteration remain obscure. In this study, we found that loss of MORF9 function impaired PSII efficiency, NDH activity, and carbohydrate production, rapidly promoted nuclear gene expression including sucrose transporter and sugar/energy responsive genes, and attenuated root growth under sugar starvation conditions. Sugar repletion increased MORF9 and MORF2 expression in wild-type seedlings and reduced RNA editing of matK-706, accD-794, ndhD-383 and ndhF-290 in the morf9 mutant. RNA editing efficiency of ndhD-383 and ndhF-290 sites was diminished in the gin2/morf9 double mutants, and that of matK-706, accD-794, ndhD-383 and ndhF-290 sites were significantly diminished in the snrk1/morf9 double mutants. In contrast, overexpressing HXK1 or SnRK1 promoted RNA editing rate of matK-706, accD-794, ndhD-383and ndhF-290 in leaves of morf9 mutants, suggesting that HXK1 partially impacts MORF9 mediated ndhD-383 and ndhF-290 editing, while SnRK1 may only affect MORF9-mediated ndhF-290 site editing. Collectively, these findings suggest that sugar and/or its intermediary metabolites impair MORF9-dependent plastid RNA editing resulting in derangements of plant root development.

Insight into the roles of hematite iron oxide nanoparticles on microalgae growth, urban wastewater treatment and bioproducts generation: Gompertz simulation, nutrient mass balance and gene expression

In this study, the effect of α-Fe2O3 nanoparticles spiking in urban wastewater (UWW) on growth rate, wastewater treatment ability and bioproducts generation of C. vulgaris and Spirulina was investigated and compared with pure cultivation system. The biomass concentration of C. vulgaris and Spirulina improved by 20 % and 39 % at 10 and 15 mg/L α-Fe2O3, respectively while the both microalgae growth pattern fitted better with Gompertz simulation after treatment with α-Fe2O3. The nutrients mass balance revealed that 1 g of treated C. vulgaris and Spirulina could uptake more COD, TN and TP in comparison to the untreated cells. The lipid generation increased remarkably (C. vulgaris: 45 % and Spirulina: 72 %) after α-Fe2O3 treatment. While, the addition of α-Fe2O3 showed no significant impact on the protein and carbohydrate productivity. Overall, this study evangelize the role of nanoparticles on promoting microalgae applications as a sustainable approach for UWW treatment and promising feedstock for biofuel production.

Recycling air conditioner-generated condensate water for microalgal biomass production and carbon dioxide sequestration

Air conditioners alleviate the discomfort of human beings from heat waves that are consequences of climate change caused by anthropogenic activities. With each passing year, the effects of global warming worsen, increasing the growth of air conditioning industry. Air conditioning units produce substantial amounts of non-nutritive and (generally) neglected condensate water and greenhouse gases. Considering this, the study explored the potential of using air conditioner condensate water (ACW) to cultivate Chlorella sorokiniana, producing biomass, and sequestering carbon dioxide (CO2). The maximum biomass production was obtained in the BG11 medium (1.45 g L−1), followed by ACW-50 (1.3 g L−1). Similarly, the highest chlorophyll-a content was observed in the BG11 medium (11 μg mL−1), followed by ACW-50 (9.11 μg mL−1). The ACW-50 cultures proved to be better adapted to physiological stress (Fv/Fm > 0.5) and can be suitable for achieving maximum biomass with adequate lipid, protein, and carbohydrate production. Moreover, C. sorokiniana demonstrated higher lipid and carbohydrate yields in the ACW-50 medium, while biomass production and protein yields were comparable to the BG11 medium. The lipid, protein, and carbohydrate productivity were 23.43, 32.9, and 23.19 mg L−1 d−1, respectively for ACW-50. Estimation of carbon capture potential through this approach equals to 9.5% of the total emissions which is an added advantage The results indicated that ACW could be effectively utilized for microalgae cultivation, reducing the reliance on freshwater for large-scale microalgal biomass production and reduce the carbon footprints of the air conditioning industry.

A novel nutritional induction strategy flexibly switching the biosynthesis of food-like products from methane by a methanotrophic bacterium

By fine-tuning key nutrients in methanotrophic cultures, the production of cell proteins and carbohydrates can be artificially manipulated in association with central metabolisms, enabling a flexible and efficient biosynthesis of CH4-derived products.

Growth inhibition and toxic effects of microplastics on Chlorella vulgaris

Microplastics (MPs) are new pollutants that severely threaten the water environment. This study investigated the effects of three microplastics, namely polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), and polystyrene (PS), on the growth, photosynthesis, biochemical composition, and antioxidant enzyme activity of Chlorella vulgaris. The results show that the average growth inhibition rate of PVC (1000 mg/l) is the highest (29.34 %), followed by PMMA (17.86 %), and PS (13.79 %). The small particle size and high concentration of microplastics are benefited to the inhibitory effect. The increase in soluble proteins within microalgae cells can enhance their water retention capacity and protect cell membranes from mechanical damage and lipid peroxidation caused by microplastics. The decrease in carbohydrate production can be attributed to a decrease in photosynthetic rate and overall physiological activity. The changes in superoxide dismutase and catalase activity can be seen as a defense mechanism for algae cells to maintain antioxidant system balance while removing excess reactive oxygen species.

The effect of photoperiodism on nutritional potency of Euglena sp. Indonesian strains

Introduction: Biomass microalgae functional materials, such as drugs and food supplements, have recently received much attention. Euglena sp. is a particularly appealing microalgae because of its simplicity of culture and capacity to produce a wide range of bioactive compounds. Moreover, it is one of the few microorganisms that produces carbohydrate, lipid, protein, ß-1,3-glucans, antioxidants, phytotoxins, wax esters, and polyunsaturated fatty acids that can be used to make nutraceuticals, pharmaceuticals, and cosmeceuticals. However, the potential utilisation of Euglena sp. for production of food supplements has been exploited only on a limited basis. Methods: This study was modified by adding protocatechuic acid and photoperiodism for 12:12; 14:10; 16:8; and full dark to affect the metabolite content of Euglena sp. Results: Results showed that the photoperiod had significant effect on lipid, chlorophyll-a, and carotenoid levels in the control treatment, with the highest levels as follows: 0.52±0.03 g/L, 1.20±0.01 x10-2 g/L, 0.30±0.02 x10-2 g/L; while the others were not significantly affected by the treatment, with the highest protein content at full dark 3.10±0.2 x10-2 g/L; chlorophyll-b at photoperiod 14:10 0.70±0.03 x10-2 g/L; paramylon at photoperiod 12:12 1.90±0.02 x10-1 g/L. The highest carbohydrates were found in control, with a level of 1.20±0.02 g/L. Conclusion: Photoperiodism is recommended to enhance productivity of protein, paramylon, and chlorophyll-b, while full light is recommended to enhance carbohydrate, lipid, chlorophyll-a, and carotenoid production in Euglena sp. to improve the quality of food nutrition.

Culture media influences Candida parapsilosis growth, susceptibility, and virulence.

Candida parapsilosis, a pathogenic yeast associated with systemic infections, exhibits metabolic adaptability in response to nutrient availability. We investigated the impact of RPMI glucose supplemented (RPMId), TSB, BHI and YPD media on C. parapsilosis growth, morphology, susceptibility (caspofungin and amphotericin B), and in vivo virulence (Galleria mellonella) in planktonic and biofilm states. High-glucose media favors growth but hinders metabolic activity and filamentation. Media promoting carbohydrate production reduces biofilm susceptibility. Virulence differences between planktonic cells and biofilm suspensions from the same media shows that biofilm-related factors influence infection outcome depending on nutrient availability. Pseudohyphal growth occurred in biofilms under low oxygen and shear stress, but its presence is not exclusively correlated with virulence. This study provides valuable insights into the intricate interplay between nutrient availability and C. parapsilosis pathogenicity. It emphasizes the importance of considering pathogen behavior in diverse conditions when designing research protocols and therapeutic strategies.

Enhanced microalgal growth and metabolites through co-cultivation with Escherichia coli in algal organic matter solution

Studies of how symbiotic bacteria interact with microalgae have been an area of interest for some time. However, there is still a knowledge gap on the role of algal organic matters in algal growth promotion and adaptive mechanisms of the co-cultures in medium containing high abundancy of dissolved algal organic matters. It remains unclear if high extra- and intra-cellular organic substances concentration influences algal development or subsequent algal organic matter productivity in the presence of bacteria. Therefore, this study aims to co-cultivate Escherichia coli NEB 5-alpha with broad range of marine and freshwater microalgae in fresh medium (T), soluble EPS (sEPS) and internal organic matter solution (IOM). Among screened species, only the growth of Cylindrotheca fusiformis and Chlorella vulgaris was promoted by E. coli at 1.15×106±2.08×104 cells mL−1 and 7.79×106±1.27×105 cells mL−1after 96 h. Xenic algal growth was further enhanced about 10 % more utilizing sEPS and IOM. However, the net EPS accumulation of the cells cultivated in sEPS and IOM was comparatively lower than that of the cells in T medium due to metabolite consumption. Elevation in the transparent exopolymer particles, total chlorophyll, total carbohydrate, total protein and lipid productivity up to 3.54-fold by cultivating the co-cultures in sEPS and IOM indicated an alteration of the microalgae's physiology. This is a new paradigm on how algal extracts promote xenic algal growth and metabolite production which pave a way for cost-effective biotechnological applications by reusing the algae medium with abundant organic matters.

Effects of mepiquat chloride and plant population density on leaf photosynthesis and carbohydrate metabolism in upland cotton

BackgroundMepiquat chloride (MC) application and plant population density (PPD) increasing are required for modern cotton production. However, their interactive effects on leaf physiology and carbohydrate metabolism remain obscure. This study aimed to examine whether and how MC and PPD affect the leaf morpho-physiological characteristics, and thus final cotton yield. PPD of three levels (D1: 2.25 plants·m−2, D2: 4.5 plants·m−2, and D3: 6.75 plants·m−2) and MC dosage of two levels (MC0: 0 g·ha−2, MC1: 82.5 g·ha−2) were combined to create six treatments. The dynamics of nonstructual carbohydrate concentration, carbon metabolism-related enzyme activity, and photosynthetic attributes in cotton leaves were examined during reproductive growth in 2019 and 2020.ResultsAmong six treatments, the high PPD of 6.75 plants·m−2 combined with MC application (MC1D3) exhibited the greatest seed cotton yield and biological yield. The sucrose, hexose, starch, and total nonstructural carbohydrate (TNC) concentrations peaked at the first flowering (FF) stage and then declined to a minimum at the first boll opening (FBO) stage. Compared with other treatments, MC1D3 improved starch and TNC concentration by 5.4% ~ 88.4%, 7.8% ~ 52.0% in 2019, and by 14.6% ~ 55.9%, 13.5% ~ 39.7% in 2020 at the FF stage, respectively. Additionally, MC1D3 produced higher transformation rates of starch and TNC from the FF to FBO stages, indicating greater carbon production and utilization efficiency. MC1D3 displayed the maximal specific leaf weight (SLW) at the FBO stage, and the highest chlorophyll a (Chl a), Chl b, and Chl a + b concentration at the mid-late growth phase in both years. The Rubisco activity with MC1D3 was 2.6% ~ 53.2% higher at the flowering and boll setting stages in both years, and 2.4% ~ 52.7% higher at the FBO stage in 2020 than those in other treatments. These results provided a explanation of higher leaf senescence-resistant ability in MC1D3.ConclusionIncreasing PPD coupled with MC application improves cotton yield by enhancing leaf carbohydrate production and utilization efficiency and delaying leaf senescence.