Carbohydrate Production Research Articles

Cellular Stress Conditions as a Strategy to Increase Carbohydrate Productivity in Spirulina platensis

Spirulina platensis, when grown under stress, may alter its metabolic pathways, leading to carbohydrate accumulation. Research on the combined effects of stress factors such as UV radiation, photoperiod, and light, and the influence of micronutrients (Ca, Fe, and Mg) on microalgae carbohydrate composition is scarce. The aim of the present study was to evaluate the effects of combined cell stress factors on the microalgal growth and biochemical composition of S. platensis, to apply the biomass in the context of biorefineries. Assays were performed at two cultivation stages: in the first stage, Zarrouk medium (50%) was used until the end of the exponential growth phase (18 days) and, in the second stage, the cells obtained in the first stage were centrifuged and recultivated in 20% Zarrouk’s medium under physical (UV, photoperiod/light, NaCl) and nutritional stress (limitation of Ca, Fe, and Mg concentrations in 20% Zarrouk). The highest carbohydrate yields (27.84 mg L−1 day−1) were obtained in the photoperiod/light intensity-stressed cultures in the medium with nutrient limitation. The study outcomes showed the methods to increase carbohydrate synthesis in cultures under optimized conditions. Our results showed that nutrient limitation by 20% Zarrouk combined with higher light intensity (67.5 μmol photons m−2 s−1) and photoperiod (18-h/6-h light/dark cycles) is an efficient strategy to achieve higher intracellular concentrations (59.71%) and carbohydrate yields (55.85 mg L−1 day−1) in a discontinuous culture method.

Pretreated fucoidan and alginate from a brown seaweed as a substantial carbon source for promoting biomass, lipid, biochemical constituents and biodiesel quality of Dunaliella salina

There is a growing demand for exploiting cost-effective carbon sources for mixotrophic cultivation of microalgae. Fucoidan and alginate were extracted from the brown seaweed Cystoseira trinodis and were subjected to hydrolysis using H2O, HCl, or NaOH for the mixotrophic cultivation of Dunaliella salina. The algal biomass was enhanced to 0.46 g L−1 and biomass productivity reached 41.83 mg L−1 day−1 using alkali hydrolyzed alginate, which was ∼1.6-fold higher than the values under the photoautotrophic conditions. Lipid content was increased to 21.81% w/w using alkali hydrolyzed fucoidan which was 1.78-times higher than the control. Several biodiesel quality parameters were calculated and indicated that mixotrophic cultivation enhanced the biodiesel properties. The biochemical composition showed that amino acid and insoluble and soluble protein productivities were promoted 2-3-folds in relation to the control. Similarly, glycerol and soluble carbohydrate (starch) productivities were increased ∼ 1.4-times, while insoluble carbohydrate productivity was 3.3-times higher than the control. Principal component analysis demonstrated that the starch content of D. salina was reduced in compensatory of lipid accumulation. In addition, the algal growth behavior was statistically fitted using modified logistic model which indicated that lag-phase and maximum growth rate were 0.75–3.89 day and 0.019–0.066 day−1, respectively.

Effects of Sulfur Starvation on Growth Rates, Biomass and Lipid Contents in the Green Microalga Scenedesmus obliquus.

Scenedesmus obliquus, a green unicellular chlorophycean microalga, is well-established as a lipid and biomass production platform. The nutrient starvation strategy is considered as a robust platform for lipid production from different microalgal strains. The study aimed to analyse the influences of sulfur starvation on the growth rates, and also biomass and lipid production and composition in a naturally isolated strain of S. obliquus. The BG-11 culture medium was utilized for preservation and microalgal growth. To monitor the cell growth rates, two different methods, including direct cell counting and also dry cell weight measurement were used. The study was conducted in 28 days composed of two distinct growth modes as 10 days of sulfur-rich and 18 days of sulfur starved media. The studied S. obliquus strain displayed higher lipid and carbohydrate production levels (34.68% and 34.02%) in sulfur starved medium compared with the sulfur-rich medium (25.84% and 29.08%). Nevertheless, a noticeable reduction (51.36%) in biomass contents and also in cell growth rates (63.36%) was observed during sulfur starvation. The investigated strain was composed of some important fatty acids with potential applications as food, feed and biodiesel. The observed results implied the possibility of the sulfur starvation strategy to increase lipid production in S. obliquus strain. Besides, the available data from recently published patents reveals the promising potential of the identified lipids from S. obliquus in this study for bioenergy production and other biotechnological purposes.

Role of cultural variables in augmenting carbohydrate accumulation in the green microalga Scenedesmus acuminatus for bioethanol production

Microalgal biomass is regarded as quintessential feedstock for bioethanol production owing to its rapid growth and high carbohydrate content. The present study investigates the effects of nitrate and phosphate starvation, magnesium and lysine supplementation, and initial pH of culture medium on the growth and carbohydrate accumulation in the green microalga, Scenedesmus acuminatus. Under nitrate- and phosphate-starved conditions, the biomass and carbohydrate yield registered a negative trend, whereas magnesium and lysine supplementations showed significant stimulation in both the parameters. Moreover, for lysine-supplemented cultures, the time-period required for maximum carbohydrate accumulation was reduced profoundly. In the test microalga, initial culture pH showed strong effects on biomass and carbohydrate accumulation. The carbohydrate productivity increased from 13.4 ± 1.8 mg L−1d−1 (control) to 38.4 ± 2.4 mg L−1d−1 for pH 9.0+lysine (0.5 g L−1)-supplemented cultures, registering a ~3-fold rise. Correspondingly, bioethanol productivity boosted ~4.3-fold, i.e., from 4.1 ± 0.3 mg L−1d−1 (control) to 17.2 ± 1.2 mg L−1d−1. Conclusively, initial culture pH 9.0 with lysine supplementation was evident as a suitable condition for enhancing the carbohydrate accumulation vis-a-vis bioethanol production in test microalgae. This study thus opened up new avenues towards the exploration of potato-peel waste and soya-meal as low-cost lysine sources to enhance carbohydrate productivity in microalgae for cost-effective bioethanol production.

Utilization of microalgae for self-regulation of extracellular polymeric substance production

Extracellular Polymeric Substance (EPS) production in relation to carbohydrate and protein compositions is an important key in wastewater bio-treatment and microalgal harvesting. The influence of microalgal cultivation conditions on EPS production is well-documented in previous studies, but there continues to be a research gap that involves the effect of the initial concentration of microalgae added in media culture. This study aimed at investigating the impact of various initial microalgae concentrations on the behavior of carbohydrate and protein compositions constituting EPS. This study is important as it helps to enhance EPS production that associate with its applications. The total carbohydrate on average obtained was 31.1 mg L−1 and protein 25.6 mg L−11. Results revealed that the compositions of carbohydrates and proteins were not regulated by initial concentrations of microalgae. However, the difference in the behaviour of the EPS is noticed in the loosely bound-EPS (LB-EPS) and tightly bound-EPS (TB-EPS). The dominant production of carbohydrates in LB-EPS was approximately 2.2 times higher than in TB-EPS. As a conclusion, it was found the effect of monosaccharide fraction was primarily derived by glucose and arabinose components in both layers. The contents of monosaccharide components were analytically stable around 21.70 mg. L−1 after their self-regulation except for glucose in LB-EPS.

Examination of Carbohydrate Products in Feces Reveals Potential Biomarkers Distinguishing Exclusive and Nonexclusive Breastfeeding Practices in Infants

ABSTRACTBackgroundThe stable isotope deuterium dose-to-mother (DTM) technique to estimate nonbreast milk water intake demonstrates that maternal self-report methods of infant feeding overestimate the true prevalence of exclusively breastfeeding practices.ObjectiveWe aimed to determine potential monosaccharide and oligosaccharide markers that distinguish between exclusively breastfed (EBF) versus nonexclusively breastfed (non-EBF) infants utilizing LC-MS-based methods.MethodsData for the analysis were collected as part of a larger, longitudinal study of 192 breastfed Indonesian infants aged 2 mo and followed up at 5 mo. Feces samples were collected from infants aged 2 mo (n = 188) and 5 mo (n = 184). EBF and non-EBF strata at each time point were determined via the DTM technique. Feces samples were analyzed to determine monosaccharide content using ultra-high-performance LC-triple quadrupole MS (UHPLC-QqQ MS). Relative abundances of fecal oligosaccharides were determined using nano-LC-Chip-quadrupole time-of-flight MS (nano-LC-Chip-Q-ToF MS).ResultsAt age 2 mo, monosaccharide analysis showed the abundance of fructose and mannose were significantly higher (+377% and +388%, respectively) in non-EBF compared with EBF infants (P <0.0001). Fructose and mannose also showed good discrimination with areas under the curve (AUC) of 0.86 and 0.82, respectively. Oligosaccharide analysis showed that a 6-hexose (Hex6) isomer had good discrimination (AUC = 0.80) between EBF and non-EBF groups at 5 mo.ConclusionCarbohydrate products, particularly fecal mono- and oligosaccharides, differed between EBF and non-EBF infants aged under 6 mo and can be used as potential biomarkers to distinguish EBF versus non-EBF feeding practices.

Biochar for urban agriculture: Impacts on soil chemical characteristics and on Brassica rapa growth, nutrient content and metabolism over multiple growth cycles

With possible food crises looming in the near future, urban farming, including small-scale community and home gardens for home consumption, presents a promising option to improve food security in cities. These small-scale farms and gardens often use planter boxes and raised beds filled with lightweight soil or potting mixes. While previous studies on biochar focused on its application on large-scale contiguous farmlands, this study aimed to evaluate the suitability of biochar as a partial soil substitute to produce a durable and lightweight soil-biochar mix for small-scale urban farms. The effects of biochar on the chemical properties of the soil-biochar mix, crop yield and, particularly, crop nutrients and metabolic content were assessed. A germination test using pak choi seeds (Brassica rapa L. cultivar group Pak choi, Green-Petioled Form) showed that the biochar contained phytostimulants. Through a nursery pot experiment over four growth cycles, biochar treatments performed better than pure soil at retaining water-soluble NO3− and K+ ions, but were worse at retaining PO43− ions. Nonetheless, despite its positive effect on soil NO3− retention, biochar application did not improve crop yield significantly when the application rate varied from 0% to 60% (v/v). Untargeted metabolomic analyses showed that biochar application may increase the production of carbohydrates and certain flavonoids and glucosinolates. The results of this study showed that biochar can potentially be used to improve pak choi nutritional values and applied in large quantity to obtain a lightweight soil mix for urban farming.

Leaf Structural Carbohydrate Decreased for Pinus thunbergii along Coast–Inland Gradients

Although photosynthesis (carbohydrate production) decreases under wind load, it is unclear how carbohydrate categories allocation changes. We determined the leaf morphology (specific leaf area (SLA), needle thickness), anatomy (cuticle thickness, epidermal thickness), photosynthesis (effective quantum yield of Photosystem II (Y(II)), carbohydrate (structure carbohydrate (SC) and non-structure carbohydrate (NSC)), and environmental variables in Pinus thunbergii plantations from coast to inland, with wind speed decreasing. As expected, wind, accounting for 19–69% of the total variation, was the most dominant environmental variable determining the leaf traits. Y(II) and NSC increased, while SC and SC/NSC decreased along the coast-inland gradients (p &lt; 0.01). These results confirmed that, although carbohydrate production decreased, SC allocation increased with increasing wind load. SLA and needle thickness decreased, while cuticle thickness and epidermal thickness increased from coast to inland. Needle thickness and cuticle thickness showed strong correlations to SC/NSC. These variations indicated that carbohydrate categories allocation related to variations of needle morphology and anatomy for P. thunbergii under wind, because of more SC allocation in leaf to support tensile strength and hardness of the cell wall under wind. Therefore, allocation between SC and NSC may be helpful for understanding the long-term adaptation of plants to wind load.

Assessment of Halamphora coffeaeformis Growth and Biochemical Composition for Aquaculture Purposes

The vast majority of the world’s fishery by-products are utilized in the fish farming industry. However, due to the high cost and unsustainability of these by-products, alternative sources must be found. Marine diatoms produce important amounts of fatty acids, sterols, proteins and carbohydrates. In this work, we assessed the nutritional value of Halamphora coffeaeformis at the exponential growth phase, to determine its suitability for aquafeed. The strain was grown in a photobioreactor at 20 °C for 6 days. The production of proteins, lipids and carbohydrates was determined, and essential fatty acid, sterol and amino acid composition was assessed. The highest values of triacylglycerides (TAG), free and esterified sterols, proteins and carbohydrates were found after 6 days of growth in the photobioreactor. Fatty acid analysis by gas chromatography showed the presence of eicosapentaenoic (EPA) and arachidonic (ARA) in amounts similar to those for fish oils. In terms of sterols, a predominance of stigmasterol was observed, followed by cholesterol. The amino acid composition revealed 50% of them to be among those essential for fish and other aquatic animals. Finally, a suitable amount of carbohydrates was found in H. coffeaeformis cultures. Together, these findings support the use of H. coffeaeformis as an alternative and sustainable source for aquafeed to partially replace the use of fishery by-products.

The excess of phosphorus in soil reduces physiological performances over time but enhances prompt recovery of salt-stressed Arundo donax plants

Arundo donax L. is an invasive grass species with high tolerance to a wide range of environmental stresses. The response of potted A. donax plants to soil stress characterized by prolonged exposure (43 days) to salinity (+Na), to high concentration of phosphorus (+P), and to the combination of high Na and P (+NaP) followed by 14 days of recovery under optimal nutrient solution, was investigated along the entire time-course of the experiment. After an exposure of 43 days, salinity induced a progressive decline in stomatal conductance that hampered A. donax growth through diffusional limitations to photosynthesis and, when combined with high P, reduced the electron transport rate. Isoprene emission from A. donax leaves was stimulated as Na+ concentration raised in leaves. Prolonged growth in P-enriched substrate did not significantly affect A. donax performance, but decreased isoprene emission from leaves. Prolonged exposure of A. donax to + NaP increased the leaf level of H2O2, stimulated the production of carbohydrates, phenylpropanoids, zeaxanthin and increased the de-epoxidation state of the xanthophylls. This might have resulted in a higher stress tolerance that allowed a fast and full recovery following stress relief. Moreover, the high amount of ABA-glucose ester accumulated in leaves of A. donax exposed to + NaP might have favored stomata re-opening further sustaining the observed prompt recovery of photosynthesis. Therefore, prolonged exposure to high P exacerbated the negative effects of salt stress in A. donax plants photosynthetic performances, but enhanced activation of physiological mechanisms that allowed a prompt and full recovery after stress.

FUT2 deficiency may influence the pathogenesis of inflammatory bowel diseases through gut microbiome

Background &amp; AimsNon‐functional fucosyltransferase 2 (FUT2) polymorphisms are associated with inflammatory bowel diseases (IBDs). FUT2 is required for the proper production of oligosaccharides and glycoproteins. These free or attached oligosaccharides have a large impact on the gut microbiota. In this study, we investigated the role of the gut microbiota in IBD pathogenesis with FUT2 deficiency.MethodWe recruited 56 Crohn’s disease (CD) and 25 ulcerative colitis (UC) patients with endoscopically confirmed disease from the IBD clinic in 6th Affiliated Hospital of Sun Yat‐sen University in Guangzhou, China between March 2016 and July 2018. Individuals were asked to provided stool and blood samples respectively. To determine the genotypes of the patients at rs1047781 (A418T) and rs601338 (G461A) of the FUT2 gene, blood DNA was extracted and FUT2 coding sequence was sequenced. For microbiome study, fecal DNA was collected and the V5–V6 region of the 16S rDNA was sequenced with a MiSeq platform.ResultThe incidence of wild‐type, heterozygous and homozygous non‐functional mutations of FUT2, were found to be 32% (26), 49% (40) and 18% (15), respectively, in IBD patients. Significant structural and functional difference were observed at every taxonomic levels among these three groups. Interestingly, the abundance of butyrate producing Dorea, Coprococcus and Ruminococcus was significantly higher in the group carrying homozygous non‐functional FUT2 than those of the other groups (wild‐type and heterozygous non‐functional FUT2, P&lt;0.05). The PICRUSt functional analysis based on the 16S data showed that several carbohydrate synthesis pathways including UDP‐2,3‐diacetamido‐2,3‐dideoxy‐α‐D‐mannuronate biosynthesis and sucrose biosynthesis pathways were enriched in IBD patients with homozygous non‐functional mutation of FUT2 (P&lt;0.05).DiscussionOur results indicated that FUT2 non‐functional mutation was associated with elevated butyrate producing microbiota, which is in concert with elevated gut microbial capacity for carbohydrate production. FUT2 homozygous mutations may lead to the compensatory increase of carbohydrate production, providing fermentation substrate for the production of short‐chain fatty acids by intestinal flora. Our results may provide a theoretical basis for IBD treatment based on microbiome intervention.Support or Funding Information1.National Natural Science Foundation of China 81774152, 31200986, 41530105, 81770571,81970452. 2.Guangzhou laboratory clinical innovation project 2018GZR0201005. 3.National Postdoctoral Program for Innovative Talents of China BX20190393. 4.Natural Science Foundation of Shanghai 16ZR1449800. 5.the University at Buffalo Community of Excellence in Genome, Environment and Microbiome (GEM).

Ease of Access to An Alternative Food Source Enables Wallabies to Strip Bark in Tasmanian Pinus radiata Plantations

Bark stripping by the Bennett’s wallaby (Macropus rufogriseus (Desmarest) subsp. rufogriseus) from the lower stems of 3–6-year-old radiata pine (Pinus radiata D. Don) causes significant damage in Tasmanian plantations. The usual diet of this generalist herbivore is mainly grasses and broadleaved forbs. As the factors that attract a wallaby to supplement its diet by eating the bark of plantation pine trees are currently not elucidated, the present study aimed to determine how the incidence and severity of bark damage in 12 Tasmanian radiata pine plantations was influenced by various inter-site factors such as the floristic composition of the surrounding forest, and by various intra-site factors such as the height and circumference of individual trees, the number of branches in the first two whorls at the base of the tree, and their internode lengths. It was found that the greater the percentages of bare ground, bracken, and moss present in the five plots at each site, and the greater the percentage of grass, the wallaby’s main food source, the greater the likelihood of bark stripping. The difference between the mean minimum soil and air temperatures in spring, a driving force for carbohydrate production that occurs with tree growth in spring or early summer, was the only meteorological observation at the sites that was found to be significantly related to the extent of bark stripping.

Spirulina sp. LEB 18 cultivation in outdoor pilot scale using aquaculture wastewater: High biomass, carotenoid, lipid and carbohydrate production

The objective of this study was to integrate the treatment of aquaculture effluent with the biomass and macronutrients production by Spirulina sp. LEB 18. The first experiment was carried out in a photobioreactor (1 L) and the best biomass production condition was reproduced on a pilot scale in a raceway type bioreactor (5 L). The best treatment was T25 (100% of wastewater supplemented with 25% of Zarrouk nutrients). The biomass production in the raceway system (T25) was higher (3.33 g L−1) than the control (2.32 g L−1) and the carbohydrate (69.77%) and lipid (12.77%) were also higher. The content of carotenoids in T25 was significant (9.68 μg mL−1). Spirulina sp. LEB 18 removed phosphate (99.97%); COD (89.34%) and nitrate (81.10%) from aquaculture effluent. The effluent showed absence of heavy metals and concentration of Al; Fe; Ca and Mg higher than the control culture with Zarrouk nutrients. The Spirulina sp. LEB 18 can be applied as a bioremediation agent of aquaculture wastewater with high production of biomass, carbohydrate, lipid and carotenoid.

Increasing growth and yield by altering carbon metabolism in a transgenic leaf oil crop.

SummaryEngineering high biomass plants that produce oil (triacylglycerol or TAG) in vegetative rather than seed‐related tissues could help meet our growing demand for plant oil. Several studies have already demonstrated the potential of this approach by creating transgenic crop and model plants that accumulate TAG in their leaves and stems. However, TAG synthesis may compete with other important carbon and energy reserves, including carbohydrate production, and thereby limit plant growth. The aims of this study were thus: first, to investigate the effect of TAG accumulation on growth and development of previously generated high leaf oil tobacco plants; and second, to increase plant growth and/or oil yields by further altering carbon fixation and partitioning. This study showed that TAG accumulation varied with leaf and plant developmental stage, affected leaf carbon and nitrogen partitioning and reduced the relative growth rate and final biomass of high leaf oil plants. To overcome these growth limitations, four genes related to carbon fixation (encoding CBB cycle enzymes SBPase and chloroplast‐targeted FBPase) or carbon partitioning (encoding sucrose biosynthetic enzyme cytosolic FBPase and lipid‐related transcription factor DOF4) were overexpressed in high leaf oil plants. In glasshouse conditions, all four constructs increased early growth without affecting TAG accumulation while chloroplast‐targeted FBPase and DOF4 also increased final biomass and oil yields. These results highlight the reliance of plant growth on carbon partitioning, in addition to carbon supply, and will guide future attempts to improve biomass and TAG accumulation in transgenic leaf oil crops.

Exogenous application of 6-BA and GA3 collaboratively improves cottonseed yield and seed quality via altering production of carbohydrates in the embryo

ABSTRACT Cottonseed produces oil for human consumption and protein meals for ruminant feed, and carbohydrate metabolism takes responsibility for seed oil and protein biosynthesis. Here, 6-BA and GA3 were evaluated by seed or foliar application for its effect on physiological and productive parameters of cottonseed in two-year field experiment. Results showed that 6-BA and GA3 significantly enhanced cottonseed yield because of increased boll number and seed index. Boll number was the dominant driver of yield increment for seed priming with 6-BA, and the increase was greater than GA3, resulting in higher yield for seed priming with 6-BA (18.8–20.1%) than with GA3 (10.7–14.5%) while the increase in yield was statistically at par between spraying of 6-BA and GA3. Although seed coat weight was not affected by 6-BA and GA3, embryo weight, oil and carbohydrate content were significantly increased by any given treatments. Higher carbohydrate content was attributed to increased sucrose, hexose and starch contents, which were closely associated with higher sucrose synthase, acid invertase, and sucrose phosphate synthase activities. Moreover, increases in the activities of these sucrose metabolism enzymes were larger for seed priming with 6-BA than GA3, accounting for the difference observed in sucrose content between 6-BA and GA3 seed application.

Photosynthetic Phosphoribulokinase Structures: Enzymatic Mechanisms and the Redox Regulation of the Calvin-Benson-Bassham Cycle.

The Calvin-Benson-Bassham (CBB) cycle is responsible for CO2 assimilation and carbohydrate production in oxyphototrophs. Phosphoribulokinase (PRK) is an essential enzyme of the CBB cycle in photosynthesis, catalyzing ATP-dependent conversion of ribulose-5-phosphate (Ru5P) to ribulose-1,5-bisphosphate. The oxyphototrophic PRK is redox-regulated and can be further regulated by reversible association with both glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and oxidized chloroplast protein CP12. The resulting GAPDH/CP12/PRK complex is central in the regulation of the CBB cycle; however, the PRK-CP12 interface in the recently reported cyanobacterial GAPDH/CP12/PRK structure was not well resolved, and the detailed binding mode of PRK with ATP and Ru5P remains undetermined, as only apo-form structures of PRK are currently available. Here, we report the crystal structures of cyanobacterial (Synechococcus elongatus) PRK in complex with ADP and glucose-6-phosphate and of the Arabidopsis (Arabidopsis thaliana) GAPDH/CP12/PRK complex, providing detailed information regarding the active site of PRK and the key elements essential for PRK-CP12 interaction. Our structural and biochemical results together reveal that the ATP binding site is disrupted in the oxidized PRK, whereas the Ru5P binding site is occupied by oxidized CP12 in the GAPDH/CP12/PRK complex. This structure-function study greatly advances the understanding of the reaction mechanism of PRK and the subtle regulations of redox signaling for the CBB cycle.

Optimizing real swine wastewater treatment efficiency and carbohydrate productivity of newly microalga Chlamydomonas sp. QWY37 used for cell-displayed bioethanol production

This work aimed to study an newly isolated microalgal strain, Chlamydomonas sp. QWY37, that can achieve a maximum carbohydrate production of 944 mg/L·d, along with high pollutant removal efficiencies (chemical oxygen demand: 81%, total nitrogen: 96%, total phosphate: nearly 100%) by optimizing culture conditions and using an appropriate operation strategy. Through a cell-displayed technology that utilizes combined engineered system, a maximum microalgal bioethanol yield of 61 g/L was achieved. This is the first report demonstrating the highest microalgal carbohydrate productivity using swine wastewater without any pretreatments associated with direct high-density bioethanol production from the subsequent microalgal biomass. This work may represent a breakthrough in achieving feasible microalgal bioethanol conversion from real swine wastewater.

Modeling biomass production during progressive nitrogen starvation by North Swedish green microalgae

Five newly isolated green algal species from Northern Sweden and one culture collection strain were tested for their ability to remove nitrogen and accumulate carbohydrates and neutral lipids (TAGs) under progressive nitrogen starvation. All six microalgal species increased biomass during N starvation, the amount of proteins decreased, and species dependent either TAGs and/or carbohydrates accumulated. Biomass of the algal strains Coelastrella sp. 3-4, Scenedesmus sp. B2-2 and S. obliquus RISE (UTEX 417) had very low final TAG content (≤3.4%) and high carbohydrate content (>41%) at the end of the starvation period. C. astroideum RW10 accumulated 9.2% TAGs and 53.9% carbohydrates during N-starvation; due to its modest growth rate (1.60 g/L and 1.06 1/day) resulting in low final biomass concentration, its cumulativeTAG and carbohydrate productivity were poor (175 mgTAG/system and 1.03 gCARBS/system). C. vulgaris 13-1 preferentially accumulated TAGs (10.3%) over carbohydrates (35%), with low minimal and maximal N quotas (2.27 and 11.6 mM/gDW) in its biomass and a very high growth rate (1.86 1/day) and cumulative TAGs productivity (278 mgTAG/system). Desmodesmus sp. RUC2 had the highest final biomass concentration (3.48 g/L) as well as cumulative TAG and carbohydrate productivity (269 mgTAG/system and 1.79 gCARBS/system). This species had the lowest minimal and maximal N quotas (1.58 and 8.50 mM/gDW) of all tested species, it can produce high amounts of biomass even when the available nitrogen concentration is low.A Droop's mathematical model with four basic parameters was applied to interpret the experimental data on N assimilation and biomass production under N starvation. The model corresponded well to the experimental data and therefore can successfully be applied to predict biomass production and N assimilation in Nordic algal species.

Comparative Proteomics of Extended-Spectrum Cephalosporin-Resistant Neisseria gonorrhoeae Isolates Demonstrates Altered Protein Synthesis, Metabolism, Substance Transport, and Membrane Permeability.

Neisseria gonorrhoeae isolates exhibit resistance to extended-spectrum cephalosporins (ESCs), the last remaining option for first-line empirical monotherapy. Here, we investigated the proteomic profiles of N. gonorrhoeae clinical isolates with ESC-resistance to support exploration of the antimicrobial resistance mechanisms for N. gonorrhoeae. We used comparative iTRAQ quantitative proteomics to investigate differential protein expression of three ESC-resistant N. gonorrhoeae clinical isolates using N. gonorrhoeae ATCC49226 as a reference strain. The expression of 40 proteins was downregulated and expression of 56 proteins was upregulated in all three ESC-resistant N. gonorrhoeae isolates. Proteins with predicted function of translation, ribosomal structure and biogenesis, as well as components of the Type IV secretory systems, were significantly upregulated. Two differentially expressed proteins of ABC transporters were also reported by other teams in proteomics studies of N. gonorrhoeae isolates under antimicrobial stress conditions. Differentially expressed proteins are involved in energy production and metabolism of carbohydrates and amino acids. Our results indicated that amino acid and carbohydrate metabolism, cell membrane structure, interbacterial DNA transfer, and ribosome components might be involved in mediating ESC-resistance in N. gonorrhoeae. These findings facilitate a better understanding of the mechanisms of ESC-resistance in N. gonorrhoeae and provide useful information for identifying novel targets in the development of antimicrobials against N. gonorrhoeae.

Enhancing carbohydrate productivity from Nannochloropsis gaditana for bio-butanol production

It presents an effective bio-butanol production with various acid hydrolysis treatment strategies H2SO4, HCI and H3PO4 (1, 2, 3, 4 and 5%) from Nannochloropsis gaditana grown under different light intensities (40, 80, 120 and 160μmolm−2 s−1). Microalgae were cultivated at 24 ± 2 with f/2 medium for control. According to our results, HCI 3% yielded the highest carbohydrate productivity with (21.3 ± 0.9 %) and bio-butanol production (2.9 ± 0.24 g/L). In addition, we obtained the highest carbohydrate content at 160μmolm−2 s−1 of light intensity. These findings suggest that Nannochloropsis gaditana can be used for effective carbohydrate content and large scale bio-butanol production in the future.