Carbohydrate Production Research Articles

Combination of trace elements and salt stress in different cultivation modes improves the lipid productivity of Scenedesmus spp.

The genus Scenedesmus harbors around 120 species, and some strains have been successfully used for mass culture and biotechnological applications. Considering the potential of this genus as a promising feedstock for production of biofuels, mainly biodiesel, it was evaluated the combined effects of trace elements, salinity stress and different cultivation modes (single batch, semi-continuous, and two-stage batch) on lipid productivity of the freshwater strains S. obliquus BR003 and S. bajacalifornicus BR024. Cultivation of BR003 and BR024 applying culture medium supplemented with trace elements and salt stress sustained a higher production of lipids. However, S. obliquus BR003 and S. bajacalifornicus BR024 showed different concentrations of neutral and total lipids when cultivated in batch-based and semi-continuous modes, and the batch-based modes were preferred for the production of lipids and carbohydrates. Consequently, different cultivation strategies coupled with slight salt stress improve the lipid productivity in Scenedesmus strains.

Post-silking Phosphorus Recycling and Carbon Partitioning in Maize Under Low to High Phosphorus Inputs and Their Effects on Grain Yield.

Phosphorus (P) recycling and carbon partitioning are crucial determinants of P-use efficiency and grain yield in maize (Zea mays), while a full understanding of how differences in P availability/plant P status affect these two processes underlying yield formation remains elusive. Field experiments were conducted for 3 years to investigate the maize growth, P remobilization, and carbohydrate accumulation in leaves and developing ears of plants receiving low to high P inputs. In plots that 75 kg P2O5 ha-1 and above was applied (corresponding to 7.5 mg kg-1 and higher Olsen-P concentration in 0–20 cm soil layer), no additional response occurred in leaf area, ear growth, and grain yield. Despite the higher P uptake with P fertilization above this threshold, the lack of additional plant growth and yield resulted in decreased P-use efficiency. Regardless of P application rates, P remobilization to the ear during the first half of the grain filling phase preferentially came from the stem (50–76%) rather than from leaves (30–44%), and with a greater proportion in the inorganic P (Pi) form over organic P fractions. Leaf photosynthesis was maintained under P-limiting conditions due to the greater P investment in organic P pools than Pi. More and larger starch granules were found in the bundle sheath cells at silking or 21 days after silking (DAS) than under P-sufficient conditions. The amount of total carbohydrate production and export was lower in the P-deficient plants than the high-P plants, corresponding to decreased leaf size and lifespan. Nonetheless, similar or significantly greater starch levels were observed in both cob and kernels at silking and 21 DAS, implying there was an adequate carbohydrate supply to the developing ears under the diminished kernel sink of the P starvation. In addition, there was a strong correlation between the accumulation rates of carbon and remobilized P in the developing kernels, as well as between carbon and total P. Overall, the results indicated that diminished sink size and lower capacity of carbon deposition may limit yield formation in P-deficient maize, which in turn imposes a feedback regulation on reducing carbon and P remobilization from source leaves. An integrated framework considering post-silking P recycling and carbon partitioning in maize and their effects on grain yield has been proposed.

Residual sugar from microalgae biomass harvested from phycoremediation of swine wastewater digestate.

The present study assessed the carbohydrate and sugar production from Chlorella spp. biomass harvested from a field scale reactor simulating phycoremediation of swine wastewater. The microalgae biomass was mainly composed by (%): carbohydrates (41 ± 0.4), proteins (50 ± 0.4), and lipids (1.3 ± 0.5). The residual sugar present in the biomass was extracted via acid hydrolysis. Among different concentrations of sulfuric acid tested (i.e., 47, 94, 188, 281 and 563 mM), significantly higher sugar content was obtained with 188 mM (0.496 g-sugar g-1 microalgae-DW). The concentration of sugar present in the microalgae did not differ significantly between the biomasses harvested by either centrifugation or coagulation-flocculation. Two commercially available strains of yeast (i.e., Saccharomyces cerevisiae and S. cerevisiae chardonnay) were tested for their capability to ferment sugar from lyophilized microalgae biomass. S. cerevisiae chardonnay showed a significantly faster consumption of sugar during the exponential growth phase. Both strains of yeast were capable of consuming most of the sugar added ≅ 8 g L-1 within 24 h. Overall, the results suggest that carbohydrate-rich microalgae biomass obtained from the phycoremediation of swine wastewaters can play an important role in green design for industries seeking alternative sources of feedstock rich in sugar.

T. Obliquus Cultivation Under Heterotrophic Conditions: Determination of Growth Parameters

Microalgae are a promising feedstock for the future of the industrial chemistry. Among microalgae, Tetradesmus obliquus (generally known as Scenedesmus obliquus) is one of the most studied species due to its robustness and its good performances for production of lipids, proteins and carbohydrates. However, the high production costs still limit large part of the possible applications. The exploitation of the heterotrophic metabolism for microalgae cultivation may potentially improve the biomass production sustainability, especially if organic substrates are obtained from wastewaters. However, this latter strategy has technical limits given by the issue of contamination by bacteria, which have growth rates ~ 10 folds higher than microalgae.The estimation of the microalgae growth parameters could allow optimization of the feeding strategy by which wastewaters are supplied to microalgae culture, and consequently, bacteria contamination minimization.In this work, an axenic culture of T. obliquus was isolated by a sonication pre-treatment followed by an incubation in solid media containing ampicillin (0.1 mg mL-1), penicillin (67 U mL-1) and streptomycin (0.07 mg mL-1). The axenic strain was then cultivated in heterotrophic condition under N-replete and N-starvation. Experimental data of biomass production and nitrogen consumption were well predicted by the Droop model. By means of the model fitting with experimental data, the optimal values for maximum theoretical growth rate ( µ ), maximum nitrogen quota (qmax), minimum nitrogen quota (qmin) and maximum nitrogen uptake rate (?max) were estimated.By estimating, in the future, the growth parameters also for other substrates and for contaminant microorganisms, a more effective wastewater supply strategy can be developed.

Microwave processes: A viable technology for obtaining xylose from walnut shell to produce lactic acid by Bacillus coagulans

Biorefining uses alternative resources (such as biomass) instead of petrochemical sources to produce bioenergy and platform chemicals. Walnut shell is a promising lignocellulosic biomass for the production of fermentable carbohydrates. In this study, the platform chemical L-(+) lactic acid was produced after walnut shell had been treated with physicochemical and biological processes. So biomass waste can be regenerated to the benefit of the circular bio-economy. Autohydrolysis assisted by microwave processes was used to depolymerize hemicellulose and amorphous cellulose in walnut shell to yield 63.5% w/w of xylose in a liquid fraction (hydrolysate) with a minimum yield of glucose. The optimum reaction conditions to obtain a high xylose yield with a low byproduct titer were 190 °C for 25 min. L-(+) lactic acid was produced by thermophilic Bacillus coagulans DSM 2314 with a carbon source of xylose and glucose which were solubilized in hydrolysate from autohydrolyzed walnut shell. A non-sterile and straightforward fermentation medium coupled with a pH adjustment of the crude hydrolysate in an anaerobic environment led to a L- (+) lactic acid yield of 81% w/w with a productivity of 0.2 g/L/h.

A scale-up evaluation of a semicontinuous culture of Scenedesmus sp. in a raceway under greenhouse conditions using a commercial fertilizer as culture medium

In the present work, Scenedesmus sp. was grown under a semicontinuous regime in fertilizer (Bayfolan® Forte, 1 mL L−1) medium, and Bold’s Basal Medium (BBM) as control, in raceways of 200 and 2000 L under greenhouse conditions. The biomass, lipid, protein, carbohydrate and total pigment production was determined. The culture under the semicontinuous regime allowed an increase in the productivities in each consecutive cycle, reaching a lipid productivity of 20.00 ± 6.29 mg L−1 d−1 in Bayfolan medium. The biomass productivity in the medium supplemented with fertilizer was significantly higher than in the BBM. The protein productivity was significantly higher in Bayfolan (1.93 ± 0.28 L−1 d−1). The average carbohydrate productivity of the cycles was 10.10 ± 2.01 mg L−1 d−1. The fertilizer allowed an increase of up to 3-fold in total pigment productivity compared to the BBM. The fatty acids obtained were mainly composed of C16:0, C18:3n3 (α-linolenic) and C18:0. Palmitic acid (C16:0) was the main fatty acids methyl ester accumulated along with stearic (C18:0) and myristic (C14:0) acids. It was shown that the utilization of the liquid fertilizer Bayfolan is a potential alternative to replace conventional media.

Production and structural characterization of a new type of polysaccharide from nitrogen-limited Arthrospira platensis cultivated in outdoor industrial-scale open raceway ponds

BackgroundCarbohydrates are major biomass source in fuel-targeted biorefinery. Arthrospira platensis is the largest commercialized microalgae with good environmental tolerance and high biomass production. However, the traditional target of A. platensis cultivation is the protein, which is the downstream product of carbohydrates. Aiming to provide the alternative non-food carbohydrates source, the feasible manipulation technology on the cultivation is needed, as well as new separation methodology to achieve maximum utilization of overall biomass.ResultsThe present study aimed to demonstrate the feasibility of industrially producing carbohydrate-enriched A. platensis and characterize the structure of the polysaccharide involved. Cultivated in industrial-scale outdoor open raceway ponds under nitrogen limitation, A. platensis accumulated maximally 64.3%DW of carbohydrate. The maximum biomass and carbohydrate productivity reached 27.5 g m−2 day−1 and 26.2 g m−2 day−1, respectively. The efficient extraction and purification of the polysaccharides include a high-pressure homogenization-assisted hot water extraction followed by flocculation with a non-toxic flocculant ZTC1 + 1, with the polysaccharide purity and total recovery reaching 81% and 75%, respectively. The purified polysaccharide was mainly composed of (1→3)(1→4)- or (1→3)(1→2)-α-glucan with a molecular weight of 300–700 kDa, which differed from the commonly acknowledged glycogen.ConclusionsBy the way of controlled nitrogen limitation, the high carbohydrate production of A. platensis in the industrial scale was achieved. The α-glucan from A. platensis could be a potential glucose source for industrial applications. A non-toxic separation method of carbohydrate was applied to maintain the possibility of utilization of residue in high-value field.

Diel oscillations in cell wall components and soluble sugars as a response to short-day in sugarcane (Saccharum sp.)

BackgroundSugarcane is a tropical crop that can accumulate high concentration of sucrose in the stem as a storage carbohydrate. For that reason, sugarcane accounts for approximately 75% of all the sugar produced in the world and has become the main sugar source to produce first-generation bioethanol in Brazil. Daily rhythms cause plants to adapt and coordinate their metabolism to achieve maximum photosynthesis and carbohydrate production throughout the day. Circadian rhythms arise from the interaction of an internal oscillator and external stimuli, whereas diel rhythms occur in response to a light-dark cycle. Diel signalling contributes to synchronizing circadian rhythms to photoperiods, and levels of carbohydrates oscillate in a diel fashion. Under regular photoperiods, they are synthesized during the daytime and consumed throughout the night as an energy reserve. However, short days can induce higher rates of synthesis during daytime and lower rates of consumption in the dark. Cell wall carbohydrates are also diurnally regulated, and it has been shown that celluloses, hemicelluloses and pectin are deposited/degraded at different times of the day. To assess the diel carbohydrate profile in young sugarcane plants, we measured soluble sugars and cell wall components along a time course in plants subjected either to a regular day or short day.ResultsShort-day influenced sucrose synthesis and cell wall components. In short-day a 44% increase in sucrose concentration was detected in the dark, but was stable during the day. Cellulose, hemicellulose and pectin also fluctuate within a 24 h interval when subjected to a short day. A 38% increase in leaf sheath cellulose was observed from the middle of the day to the first hour of the night. Leaf sheath pectin and hemicellulose also increased from the day to the night, while it decreased in leaves.ConclusionsThe presented data show diurnal patterns of soluble sugar metabolism together with temporal regulation of cell wall metabolism for a short day, suggesting that diel signalling has a role in how sugarcane manages sugar accumulation and partitioning. Understanding cell wall synthesis/degradation dynamics may help to improve the yield of sugarcane.

Two-stage cultivation of the marine microalga Chlorella salina for starch and carbohydrate production

Growing concern and awareness towards environmental issues, such as plastic pollution, have encouraged scientific focus on microalgae as a potential feedstock for thermoplastic starch production. Given their unique ability to utilize wastewater nutrients, microalgae are suitable to be used in wastewater treatment. In first-stage cultivation, Chlorella salina was grown in a Conway medium at 30 °C and exposed to red light under a photoperiod of 24:0 h light–dark cycle to maximize biomass production. The microalgal biomass harvested from the first stage was used as the inoculum for second-stage cultivation. The effects of photoperiod, CO2 concentration, and nutrient limitation were investigated. Cultivation using wastewater was compared with the synthetic medium for starch and carbohydrate accumulation. C. salina cultivated under 12:12 h light–dark cycle significantly accumulated the highest starch and carbohydrate with respective concentrations of 16.769 and 70.850 mg L−1. Under 5% (v/v) CO2, C. salina significantly accumulated starch and carbohydrate with respective concentrations of 13.699 and 58.910 mg L−1. The combination of nitrogen and sulfur limitation significantly triggered the highest starch (30.505 mg L−1) and carbohydrate (145.994 mg L−1) accumulation. Under optimized 5% v/v CO2 supply, the concentrations of starch and carbohydrate accumulated by C. salina using wastewater were 24.971 and 110.756 mg L−1, respectively, which were approximately twice higher compared with the synthetic medium. The usage of wastewater aerated with 5% v/v CO2 would be a more sustainable and economical strategy for high starch and carbohydrate accumulation in C. salina compared with the combination of nitrogen with sulfur limitation.

Potential of two-stage cultivation in microalgae biofuel production

Microalgae are a group of microorganisms considered to be a potential source of next-generation biofuel owing to high photosynthetic rate. However, biofuel compounds including lipid, carbohydrate, and hydrogen are not sufficiently produced by microalgae under normal conditions; therefore economical viability of microalgal biofuel production has not reached the ultimate stage of commercial viability. In order to overcome the above limitation, various stress conditions have been applied on microalgae to boost lipid, carbohydrate and hydrogen production. Even though stress conditions increases the production of biofuel compounds, microalgae growth is severely affected. In this regard, a two-stage cultivation mode wherein first stage involving high biomass production under media optimized heterotrophic condition and second stage involving lipid, carbohydrate and hydrogen accumulation under stress integrated phototrophic mode is considered as a potential route for biofuel production in microalgae. The present review critically evaluates various two-stage strategies adopted in microalgal biofuel production by comparing lipid, carbohydrate and hydrogen productivities with that of single stage cultivation. In addition, advantages of two-stage cultivation including co-product generation, less bacterial contamination, improved biodiesel quality, auto-flocculation, and bioremediation potential are also discussed. Finally, the paper summarizes the two-stage cultivation modes by identifying the bottlenecks and suggesting the future potentialities of the process.

Green alga cultivation with nanofibers as physical adsorbents of carbon dioxide: Evaluation of gas biofixation and macromolecule production

The objective of this study was to evaluate the biofixation and production of biocompounds by Chlorella fusca LEB 111 cultivated with different concentrations of carbon dioxide (CO2) adsorbent nanofibers in their free form or retained. Cultures were grown in 15% (v v−1) CO2 with 0.1, 0.3 and 0.5 g L−1 nanofibers developed with 10% (w v−1) polyacrylonitrile (PAN)/dimethylformamide (DMF), with or without nanoparticles; retained or not. The addition of 0.1 g L−1 nanofibers with nanoparticles in their free form to the cultures promoted the accumulation of approximately 3 times more carbon in the medium (46.6 mg L−1), a 45% higher biofixation rate (89.2 mg L−1 d−1) and increased carbohydrate production by approximately 2.3% (w w−1) of that observed in cultures grown without nanofibers. Therefore, nanofibers showed promising potential as physical adsorbents of CO2 in the cultivation to increase gas fixation and promote the synthesis of macromolecules.

Agronomic Characteristics, Chemical Composition and In vitro Gas Production of Sugarcane Cultivars (Saccharum spp.) for Feeding Ruminants

The aim of this work was to evaluate the agronomic characteristics, chemical composition and in vitro gas production of sugarcane (Saccharum spp.) cultivars used in ruminant feed. The experimental design was a randomized block containing seven treatments and three replications totaling 21 plots. The cultivars RB835436, RB925211, RB925345, RB937570, RB945961, RB955970 e SP91-1049 was evaluated for dry matter, dry matter yield, stalk percentage, stalk tons per hectare, plant height, stalk diameter, number of tillers per linear meter, mass per stem, soluble solids content (BRIX), NDF/BRIX ratio and tons of sucrose/ha, total digestible nutrients, digestible energy, metabolizable energy, net energy and in vitro digestibility of organic matter, crude protein, neutral detergent fiber (NDF) and acid detergent, of digestion and In vitro gas production of non-fibrous carbohydrates, latency time, digestion rate and gas production of fibrous carbohydrates, and in vitro digestibility of organic matter. There was a significant difference between the cultivars regarding the neutral detergent fiber content, in vitro digestibility of organic matter, total digestible nutrients, digestible energy, net energy, degradation rates of fibrous and non-fibrous carbohydrates and latency period. There was a negative correlation between stem percentage and NDF/BRIX and positive correlation between in vitro digestibility of organic matter and total digestible nutrients. The results were submitted to analysis of variance and mean test by Scott-Knott and Pearson's correlation analysis. The statistical program used was SAEG 2000. The RB835486 variety was superior to the other cultivars, as it presented 93.28% of stem, 57.5% of in vitro digestibility of organic matter, NDF / BRIX ratio of 2.68, 43.78% NDF, latency period 2.86h and fibrous carbohydrate degradation rate of 2.26% per hour. Therefore, this cultivar was better indicated for animal feeding between May and July in the State of Mato Grosso, Brazil.

High-Throughput Biochemical Fingerprinting of Oleaginous Aurantiochytrium sp. Strains by Fourier Transform Infrared Spectroscopy (FT-IR) for Lipid and Carbohydrate Productions.

The traditional biochemical methods for analyzing cellular composition of oleaginous microorganisms are time-consuming, polluting, and expensive. In the present study, an FT-IR method was used to analyze the cellular composition of the marine oleaginous protist Aurantiochytrium sp. during various research processes, such as strains screening, medium optimization, and fermentation, and was evaluated as a green, low-cost, high throughput, and accurate method compared with the traditional methods. A total of 109 Aurantiochytrium sp. strains were screened for lipid and carbohydrate production and the best results were found for the strains No. 6 and No. 32. The yields and productivities could reach up to 47.2 g/L and 0.72 g/L/h for lipid, 21.6 g/L and 0.33 g/L/h for docosahexaenoic acid (DHA) in the strain No. 6, and 15.4 g/L and 0.18 g/L/h for carbohydrate in the strain No. 32, under the optimal conditions, respectively. These results confirmed potentials of the two Aurantiochytrium sp. strains for lipid, DHA, and carbohydrate productions at industrial scales. The FT-IR method in this study will facilitate research on the oleaginous Aurantiochytrium sp., and the obtained two strains for lipid and carbohydrate productions will provide the foundations for their applications in medical, food, and feed industries.

Xanthobacter-dominated biofilm as a novel source for high-value rhamnose.

Rhamnose is a high-value carbohydrate used in flavorings, aromatics, and pharmaceuticals. Current demand for rhamnose is filled through plant-based sources; however, microbially originated rhamnolipids have been proposed as an alternative source. A mixed microbial biofilm, cultured from a wastewater sludge, was found to comprise > 8 dry weight% rhamnose when provided volatile fatty acids as carbon source, and 24 dry weight% when given glucose. The latter rhamnose concentration is a fourfold higher production mass than the current plant-based origin and is competitive with yields from pure microbial cultures. The biofilm was characterized based on total carbohydrate production at varying nutrient levels, individual carbohydrate monomer production from varying organic acid substrates, and microbial community composition-based on 16s rRNA. Biofilm carbohydrate production was maximized at a C:N ratio of 28 (mol:mol). The production of rhamnose varied significantly based on carbon substrate; glucose had the greatest yield of rhamnose, followed by propionic acid, lactic acid, acetic acid, valeric acid, and butyric acid. Microbial community analysis indicated an abundance of organisms within the Xanthobacter genus, which is known to produce rhamnose as zeaxanthin rhamnoside. Rhamnose production was heavily correlated with ribose production (R2 = 0.96). Results suggest that mixed microbial biofilms could be a competitive source of monomeric rhamnose that may be produced from mixed organic waste streams of variable composition via volatile fatty acids and glucose.

Chloroplast thioredoxin systems dynamically regulate photosynthesis in plants.

Photosynthesis is a highly regulated process in photoautotrophic cells. The main goal of the regulation is to keep the basic photosynthetic reactions, i.e. capturing light energy, conversion into chemical energy and production of carbohydrates, in balance. The rationale behind the evolution of strong regulation mechanisms is to keep photosynthesis functional under all conditions encountered by sessile plants during their lifetimes. The regulatory mechanisms may, however, also impair photosynthetic efficiency by overriding the photosynthetic reactions in controlled environments like crop fields or bioreactors, where light energy could be used for production of sugars instead of dissipation as heat and down-regulation of carbon fixation. The plant chloroplast has a high number of regulatory proteins called thioredoxins (TRX), which control the function of chloroplasts from biogenesis and assembly of chloroplast machinery to light and carbon fixation reactions as well as photoprotective mechanisms. Here, we review the current knowledge of regulation of photosynthesis by chloroplast TRXs and assess the prospect of improving plant photosynthetic efficiency by modification of chloroplast thioredoxin systems.

Growth medium and nitrogen stress sparked biochemical and carotenogenic alterations in Scenedesmus sp. CCNM 1028

Microalgae are a spring of valuable compounds finding its wide applicability as cosmo-nutraceuticals, a renewable substitute for bioenergy and bioremediation. The present study utilizes Scenedesmus sp. CCNM 1028, freshwater microalgae, to understand the influence of various microalgal growth media, like BG-11, Chu's 10, Bold's basal medium (BBM) and Zarrouk's media (ZM), on the growth and lutein production. Furthermore, two-stage nitrogen starvation studies were carried out using the selected BG-11 media and its effect on the lutein and biochemical parameters of Scenedesmus sp. CCNM 1028 after 0, 6, 9, 15 and 21 days (d) of nitrogen starvation were recorded. Lutein was accumulated till 6d of nitrogen starvation. Additionally, ~3-fold increase of carbohydrate content (%w/w) was observed after 21d of nitrogen starvation with respect to the control. Thus, this study proposes two-stage nitrogen starvation as a capable strategy to cultivate Scenedesmus sp. CCNM 1028 for lutein (6d) and carbohydrate production (21d).

Relationship between the dietary glycemic load of the adult Polish population and socio-demographic and lifestyle factors - results of the WOBASZ II study.

Cardiovascular disease (CVD) occurs more often among people with a low sociodemographic status, so it is worth knowing if any sociodemographic factor also has an impact on diet quality, defined by glycemic load (GL). Assessment of the relationship between the sociodemographic and lifestyle factors, health status self-assessment and dietary GL of the adult Polish population based on WOBASZ II study results. The study included a representative group of the Polish population aged ≥20 years (2,554 men and 3,136 women). A 24-hour dietary recall was collected to assess the dietary intake. The total GL was calculated by summing the GL values of the consumed food. The average GL/1,000 kcal was significantly higher in women's than in men's diets (74.0 ±15.9 vs 71.2 ±15.7). Dietary GL/1,000 kcal increased with age (men: aged <35 - 70.3 and aged ≥65 - 73.9, women: 73.5 and 76.5, respectively). The lowest dietary GL/1,000 kcal was found among people living in large population centers. Dietary GL/1,000 kcal decreased with education level (men with primary, secondary and higher education: 73.4, 69.5 and 68.9, respectively, and women: 76.7, 73.4 and 70.9, respectively). Dietary GL decreased as an income increased. The highest GL/1,000 kcal was observed in the diets of participants who performed less physical activity. The highest GL/1,000 kcal was observed in the participants who defined their health status as very poor/poor and the lowest among those who defined their health status as good/very good. Nutritional education about the proper selection of products that are sources of carbohydrates in the diet should be addressed mainly to people with low sociodemographic status, such as: people in the older age group, living in small population centers, and with lower levels of education and lower income. It should also be directed to people with a lower level of physical activity. Greater awareness of the choices of carbohydrate products is recommended to improve diet quality in these groups of people.

Transgenic analysis of maize endosperm metabolism

Maize seeds provide a major component of the calories in the human diet, are critical as a feed source in animal agriculture, and are an important source of biorenewable raw materials. Endosperm tissue accounts for approximately 80% of seed weight, and is the site where carbohydrate and protein storage end products are produced in this net anabolic system. Sucrose supplied from photosynthetic tissues of the maternal plant is transported to growing seeds where it is divided between catabolic pathways that generate ATP and anabolic biosynthetic processes that utilize ATP to generate starch and storage proteins. Considering the high degree of ATP requirement, the fact that maize endosperm is an extremely hypoxic environment raises questions about how energy is generated, and the net efficiency of the system for product formation. This project tested the hypothesis that fully oxidative metabolism is not required for normal kernel development, and accordingly that ATP is generated exclusively or substantially through fermentative processes. To do so, RNAi technology was utilized to inactivate the 2‐oxoglutarate dehydrogenase (ODH) step of the citric acid cycle. T‐DNA vectors were constructed that expressed a double stranded RNA structure containing sequences homologous to both of the maize mRNAs encoding the E2 subunit of this enzyme. Highly active, tissue specific promoters were used to restrict the effects of the transgene exclusively to endosperm tissue. Plants were generated containing the anti‐ODH transgene, and subsequent crosses have established segregating populations of sibling kernels that either contain or lack that element. ODH activity and protein abundance in endosperm tissue will be measured to verify that the transgene is effective in inactivating the targeted enzyme activity. Subsequently, segregating kernel populations will be compared regarding growth rate over the course of development, mature kernel weight and composition, and global metabolite profiles. These studies will reveal the extent to which ODH is required for starch and storage protein synthesis to proceed in developing maize endosperm. This will reveal whether normal ATP generation in this tissue requires oxidative processes or, alternatively, whether fermentative processes can be sufficient to provide the energy required for the massive amount of starch and protein synthesis that makes maize such an important agronomic resource. Answering this question will enable future efforts to improve maize yields and grain quality.Support or Funding InformationThis research was supported by NSF award 1517256 to A.M.M. and T.A.H.‐B.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Advance in metabolic engineering of microalgae for biofuels and high-value compounds

Algal biofuel is considered as an alternative to fossil fuels. Due to the structure simplicity and genetic tractability of many microalgae, they are also gradually recognized as an ideal factory for the production of various metabolites of high commercial values. In this mini-review, we attempt to summarize recent development on metabolic engineering of microalgae to explore their metabolic versatility for the production of hydrogen, carbohydrates, terpenes, fatty acids, alcohols, aliphatic alkanes and alkenes. In addition, we also present key challenges facing algal engineering, and propose a few strategies that could leverage the advancement in systems biology and genomics. We foresee a bright future for microalgae studies to advance both research and technology development.

Microbiome-metabolomic analysis of the impact of Zizyphus jujuba cv. Muzao polysaccharides consumption on colorectal cancer mice fecal microbiota and metabolites.

It is still uncertain whether the consumption of Zizyphus jujuba cv. Muzao polysaccharides (ZMP) alleviates colorectal cancer (CRC) through the gut microbiota. In this study, we investigated the mortality, colon length, inflammatory factors and cecal microbiota, metabolites of healthy and azoxymethane (AOM) and dextran sodium sulfate (DSS) in induced CRC mice, consuming ZMP. Fecal-microbiota composition was examined using 16S rDNA sequencing and fecal-metabolome profiles were evaluated by ultra-high performance liquid chromatograph mass spectrometry (UHPLC-MS). The results showed ZMP consumption prevented CRC mouse colon shortening, decreased their mortality, reduced pro-inflammatory cytokines, increased the concentration of total short-chain fatty acids (SCFAs) and modulated gut microbiota in their feces. ZMP also increased the richness of Bifidobacterium, Bacteroides and Lactobacillus. In addition, among 39 perturbed metabolites, carbohydrate and amino acid production were noticeably altered. Moreover, higher correlations were found between fluctuant gut microbiota and metabolites. These findings provide mechanistic insights into the impact of dietary Zizyphus jujuba cv. Muzao polysaccharides on host health.