Carbohydrate Production Research Articles

Co-cultivation of high-value microalgae species with filamentous microalgae for dairy wastewater treatment

The study examined the feasibility of co-culturing high-value microalgae sp. (Chlorella vulgaris (C.), and Scenedesmus (S.)) with filamentous microalgae sp. (Tribonema (T.) and Lyngbya (L.)) to remediate dairy wastewater (DW) and enhance biomass production and harvesting. The results showed that biomass productivity increased by 12‒174% compared to monocultures, and the best consortium was S:T. This consortium achieved the highest biomass productivity of 84.25 mg L−1 d−1 while removing 86.7% of chemical oxygen demand (COD), >88.7% of NO3−-N and >98.5% of PO43–-P. The study also tested the effect of harvesting time on the accumulation of biochemical components and found the optimal harvesting times of day 9 and day 11 to achieve maximum carbohydrate and lipid productivity, respectively. Additionally, the microalgae consortium S:T achieved a high biomass recovery of 78.5%, compared to 32.4% obtained for S. alone, highlighting its potential for efficient DW remediation and resource recovery.

The history of the US Starch Round Table

AbstractBackground and ObjectivesStarch and other carbohydrates are major products of commerce because of their abundant supply and diverse functionalities. They serve as the principal source of dietary energy for humans and animals and perform various functions in many food and nonfood products. Fundamental studies of their composition, structure, and properties led to practical applications and ultimately to their commercial development to serve the food and industrial sectors.FindingsThis paper provides a historical account of the US Starch Round Table, a scientific gathering of international scientists and researchers to discuss “cutting‐edge” research on starch and other carbohydrates. From its early beginning in 1940 to the present time, the Starch Round Table played a crucial role in advancing our knowledge of starch and other carbohydrates.ConclusionsThe concept of the Starch Round Table facilitated discovery, innovation, and progress in the field of carbohydrates with an emphasis on starch. From its genesis in the United States, its popularity has spread to other regions like Japan and Europe, which have been holding a similar event since 1961 and 2010, respectively.Significance and NoveltyNew knowledge was discovered, practical applications were achieved, and successful collaboration among starch and carbohydrate scientists across the globe was made possible through this biennial round table event. Commercial development of starch and other carbohydrate products has benefited immensely from the extraordinary progress made by brilliant and diligent scientists and researchers, past and present.

Exogenous Riboflavin Application at Different Growth Stages Regulates Photosynthetic Accumulation and Grain Yield in Fragrant Rice

Fragrant rice has high market value and is popular among consumers because of its pleasant fragrance. Plant growth regulators and trace elements can influence the yield and physiological indices of fragrant rice. Riboflavin, a vital component of plant vitamins, plays a crucial role in plant growth and development, and it is a water-soluble vitamin that is essential for sustaining normal photosynthesis and metabolic processes. However, the effects of riboflavin on nutrient accumulation and yield formation in fragrant rice have rarely been reported. Therefore, to further increase the yield and quality of fragrant rice, this study investigated the impact of the foliar application of riboflavin at different growth stages on nutrient accumulation and yield formation in two different genotypes of fragrant rice via a pot experiment. The experimental design consisted of three treatment groups, i.e., the T0 treatment group (control), which was sprayed with water; the T1 treatment group, which was sprayed at the booting stage; and the T2 treatment group, which was sprayed at the flowering stage; in all of these groups, 20 mg·L−1 riboflavin solution was used. The results revealed that the yields of the T1 and T2 treatments increased by 6.56–7.25% and 10.52–13.80%, respectively, compared with those of T0, which was attributed mainly to the increase in 1000-grain weight and grain filling. Furthermore, foliar spraying of riboflavin significantly increased the chlorophyll content, which resulted in the increased production of more total starch, soluble sugars, and sucrose and facilitated their transportation to the seeds. Moreover, applying riboflavin directly to the leaves increased the activity levels of the sucrose synthase (SS) and sucrose phosphate synthase (SPS) enzymes. Among the three treatments, the T2 treatment had the most pronounced effect. The results revealed that the foliar application of riboflavin could increase photosynthesis and promote the production of nonstructural carbohydrates, thereby increasing the total aboveground biomass of fragrant rice by 17.00–20.91% and 21.07–72.91% under the T1 and T2 treatments, respectively. Additionally, spraying riboflavin promoted rapid increases in the weight of fragrant rice seeds. In conclusion, foliar spraying of riboflavin during the flowering stage of aromatic rice can effectively enhance photosynthetic accumulation and yield, which is a promising physiological regulation strategy and provides new theoretical guidance for high-yield cultivation practices.

Isolation and identification of thermophilic cyanobacterium inhabiting Shiv Kund (Sohna hot spring), India through polyphasic approach: Bioprospecting in varying nitrogen environment for biotechnological interest particularly for biofuel potential

Identifying a potential candidate having optimal growth characteristics and high-value biotechnological attributes, especially biofuel profile in the era of high rising renewable energy demands is necessary for a sustainable algal-biorefinery perspective. Thermophilic cyanobacteria are scarcely investigated for their industrial potential. In this regard, a preliminary study was performed to isolate a thermophilic cyanobacterium from Shiv Kund, Sohna hot spring, Gurugram, India. The polyphasic approach with molecular identification through 16SrRNA and phylogenetic analysis identified the isolated thermophilic cyanobacterium as Fischerella thermalis PCC 7521 based on the 99.15 % similarity in the NCBI-BLASTn results. Further, the phenotypic visualization under light microscopy and Scanning Electron Microscope (SEM) confirms the true-branching filamentous nitrogen fixing cyanobacterium. To examine its potential for a biotechnological perspective, the effect of different nitrogen concentrations in the growth medium on the biochemical profiling was studied. The highest biomass production and biomass productivity per day obtained was 1041.6 mg/L and 42.33 ± 1.52 mg/L/d⁎⁎(p < 0.01) in 0.1875 g/L (N/8) and 1.5 g/L (N) sodium nitrate concentration respectively. The effect of the growth phase on the biochemical profiling was also prominent and studying optimization helps in the cost-effective production of the required product. Surprisingly, nitrogen starvation has resulted in the increased production of pigments (chlorophyll, phycocyanin and carotenoids), proteins and lipids. The maximum carbohydrate production observed was under complete nitrogen availability (N) in the growth medium with 37.4 % more production in N than complete nitrogen starvation (N0) on 15th day of the growth cycle. Interestingly, the total lipid production observed was 457.41 ± 18.3 μg/mg ⁎(p ≤ 0.05) in N0 condition and 519.28 ± 21.3 μg/mg ⁎⁎(p < 0.01) in N/8 condition on 15th and 20th day of the growth cycle respectively. The effect of nitrogen concentrations on the C/N ratio and different functional groups were also examined. Overall, the results indicated F. thermalis PCC 7521 is a promising candidate for different biotechnological fields, especially biofuel production.

Enhanced Production of Microalgal Metabolites Through Aeration Coupled with Stirring

Adequate mixing is a key factor for microalgal cultivation to achieve high biomass production, so it is essential to clarify the comparative effects of different mixing methods on microalgal productivity, which has rarely been studied previously. This work therefore aimed to investigate the effects of different mixing methods (stirring, aeration, and aeration coupled with stirring) on the growth and metabolite composition of Chlorella sorokiniana SDEC-18, a strain with potential for large-scale application. The results showed that mixing was beneficial for carbohydrate accumulation, while dual mixing (aeration coupled with stirring) promoted growth and achieved the highest dry mass and metabolite productivities (including carbohydrates, proteins, and lipids) through enhancement of light energy capture in the entire system. The stirring speed in the dual mixing approach of aeration coupled with stirring was also considered: the optimal condition was found to be 800 rpm. The maximum biomass was 3.56 g L−1, and the carbohydrate productivity was as high as 119.45 mg L−1 d−1, which was the highest metabolite productivity (higher than proteins or lipids), obtained from aeration coupled with stirring at 800 rpm. Our study suggests that aeration coupled with stirring provides a feasible strategy for microalgal production, due to the optimal availability of CO2 and light achieved through effective mixing.

A Thermodynamic Comparison of Exergy Production from Sugarcane and Photovoltaic Modules in the Context of Brazilian Energy Transition

This article applies the exergy analysis to the production and use of sugarcane, considering a model published in the literature. In this way, we compute incident solar irradiation, carbohydrate production, water consumption, and the production of stalks and straws. Following the production estimate, we analyze a biorefinery production cycle, from solar irradiation to the biorefinery products on an exergy basis, from birth to production of sugar, electrical energy, and ethanol. The calculated sugarcane production values are 80.7 tons per hectare for a 52-week cycle. As a result, the average exergy efficiency of sugarcane is 4.99%, reaching peaks of 8.3%. When considering only the useful exergy generated in the production of stalks and straw, an annual yield of 17.86 kWh/m2 represents an overall exergy efficiency of 1.31%. Considering the energy conversion processes in the biorefinery, the exergy efficiency from the radiation to the products from the biorefinery was 0.38%. The photovoltaic modules already have a well-established application in the country, though they need to increase their insertion over time, whereby the panels exhibit an average exergy efficiency of 31.6%, resulting in an annual electrical energy production of 255.84 kWh/m2. The results show that photovoltaic modules are a more efficient alternative than sugarcane regarding exergy land use. In conclusion, this study briefly discusses the use of sugarcane and photovoltaic modules in the context of Brazil’s energy transition towards a reduced dependence on fossil fuels, based on the fact that sugarcane already has a low carbon footprint for transportation using ethanol, with supply from more than 40,000 stations, and a similar or lower carbon footprint than electrical vehicles used across the country.

Excessive boron fertilization-induced toxicity is related to boron transport in field-grown pomelo trees.

Boron (B) is an essential micronutrient for plant growth and development; however, the process of B toxicity in citrus production is still poorly understood. We proposed a hypothesis that B toxicity in citrus trees is related to the characteristics of B transport from soil to leaf or fruit. For this, a field experiment was conducted for two treatments, control (B free or without B) and B fertilizer treatment (100 g Na2B4O7·10H2O plant-1), to investigate the effects on plant growth, nutrient uptake, fruit yield and quality, and B transport in 10-year-old pomelo trees [Citrus grandis (L.) Osbeck cv. Guanximiyou]. Our results showed that excess B fertilization directly led to B toxicity in pomelo trees by dramatically increasing soil total B and water-soluble B contents. B toxicity induced interveinal chlorosis in leaves and decreased leaf biomass and function, resulting in a decreased 45.3% fruit yield by reducing 30.6% fruit load and 21.4% single fruit weight. Also, B toxicity induced changes in mineral elements between leaf positions and fruit parts, in which the concentrations of B, potassium, and magnesium were increased while those of nitrogen and iron were decreased. Under B toxicity conditions, fruit quality parameters of total soluble solids (TSS), TSS/titratable acidity (TA), total soluble sugar, sucrose, pH, vitamin C, and total phenol contents decreased, which were regulated by the lower carbohydrate production in new leaves and the lower transport capacity in old leaves. Moreover, B toxicity significantly increased the transfer factor and bio-concentration factor of B in pomelo plants, with higher levels in leaf organs than in fruit organs. Taken together, excess B fertilization-induced B toxicity in pomelo trees, with induced growth inhibition and nutrient disorder, results in reduced fruit yield and quality, which are related to B transport from soil to organs. The findings of this study highlight the understanding of B toxicity in citrus plants and strengthen B management in pomelo production for high yield and high quality.

Phytohormones enhanced carbon fixation and biomass production in CO2 absorption-microalgae conversion system under light stress

CO2 absorption-microalgae conversion (CAMC) system can be a sustainable technology to achieve low-energy carbon capture and resource utilization in response to zero carbon. However, light stress could restrict the carbon utilization efficiency of CAMC system. In this study, melatonin (MT) and indole-propionic acid (IPA) as phytohormones, were used to promote the carbon fixation capacity and biomass yield of CAMC system under light stress, and the potential mechanism was also discussed. Both MT and IPA promoted the growth of Spirulina, and 10 mg-MT group obtained the highest biomass and carbon fixation capacity, which were 27.61 % and 30.62 % higher than control. MT and IPA promoted the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR), enhancing antioxidant activity to avoid oxidative damage. The results of transmission electron microscopy (TEM) and cell apoptosis showed MT and IPA reduced cell membrane damage and apoptosis. Phytohormones induced the carbon flux flow to the synthesis of carbohydrate and protein, and increased carbohydrate and protein productivity. Moreover, the maximum phycocyanin content and yield were 13.74 % and 43.25 % higher than the control. Therefore, adding phytohormones was an effective strategy to achieve high-value bioresources of microalgae in CAMC system under light stress.

Role of cultivation parameters in carbohydrate accretion for production of bioethanol and C-phycocyanin from a marine cyanobacterium Leptolyngbya valderiana BDU 41001: A sustainable approach

The investigation aimed to augment carbohydrate accumulation in the marine cyanobacterium Leptolyngbya valderiana BDU 41001 to facilitate bioethanol production. Under the standardised physiochemical condition (SPC), i.e. 90 µmol photon m−2 s−1 light intensity, initial culture pH 8.5, 35 °C temperature and mixing at 150 rpm increased the carbohydrate productivity ∼70 % than the control, while a 47 % rise in content was obtained under the nitrate (N)-starved condition. Therefore, a two-stage cultivation strategy was implemented, combining SPC at the 1st stage and N starvation at the 2nd stage, resulting in 80 % augmentation of carbohydrate yield, which enhanced the bioethanol yield by ∼86 % as compared to the control employing immobilised yeast fermentation. Moreover, biomass utilisation was maximised by extracting C-phycocyanin, where a ∼77 % rise in productivity was recorded under the SPC. This study highlights the potential of L. valderiana for pilot-scale biorefinery applications, advancing the understanding of sustainable biofuel production.

Membrane Damage and Metabolic Disruption as the Mechanisms of Linalool against Pseudomonas fragi: An Amino Acid Metabolomics Study.

Pseudomonas fragi (P. fragi) is usually detected in low-temperature meat products, and seriously threatens food safety and human health. Therefore, the study investigated the antibacterial mechanism of linalool against P. fragi from membrane damage and metabolic disruption. Results from field-emission transmission electron microscopy (FETEM) and atomic force microscopy (AFM) showed that linalool damage membrane integrity increases surface shrinkage and roughness. According to Fourier transform infrared (FTIR) spectra results, the components in the membrane underwent significant changes, including nucleic acid leakage, carbohydrate production, protein denaturation and modification, and fatty acid content reduction. The data obtained from amino acid metabolomics indicated that linalool caused excessive synthesis and metabolism of specific amino acids, particularly tryptophan metabolism and arginine biosynthesis. The reduced activities of glucose 6-phosphate dehydrogenase (G6PDH), malate dehydrogenase (MDH), and phosphofructokinase (PFK) suggested that linalool impair the respiratory chain and energy metabolism. Meanwhile, genes encoding the above enzymes were differentially expressed, with pfkB overexpression and zwf and mqo downregulation. Furthermore, molecular docking revealed that linalool can interact with the amino acid residues of G6DPH, MDH and PFK through hydrogen bonds. Therefore, it is hypothesized that the mechanism of linalool against P. fragi may involve cell membrane damage (structure and morphology), disturbance of energy metabolism (TCA cycle, EMP and HMP pathway) and amino acid metabolism (cysteine, glutamic acid and citrulline). These findings contribute to the development of linalool as a promising antibacterial agent in response to the food security challenge.

Influence of Water Erosion on Soil Aggregates and Organic Matter in Arable Chernozems: Case Study

Since Chernozems are among the most fertile soils in the world, the study of their degradation is of great interest. However, the microstructure and composition of the soil organic matter (SOM) in eroded Chernozems have not yet been sufficiently studied. We studied the SOM and aggregate states of eroded Chernozems using the example of two catenas with arable Haplic Chernozems in the Kursk region of Russia. In the plow horizons (the part of the soil most susceptible to water erosion), we determined the mean-weighted aggregate diameter (MWD), structure and water stability coefficients (SC and WS; dry and wet sieving, respectively), soil organic carbon (SOC) content, and SOM composition and content (qualitative and quantitative micromorphological analyses, respectively). It was shown that with an increase in the degree of erosion, the content of SOC decreased significantly, according to both chemical and micromorphological methods of evaluation. No significant relationships were found between the degree of erosion and the indicators of the structure (except for WS, which was significantly lower in non-eroded Chernozem than in slightly and moderately eroded soils). With the increasing degree of erosion, the humus state of these soils deteriorates at the microlevel, the intensity of humification decreases, the depth of the appearance of assimilated biogenic aggregates with finely dispersed calcite in the profile increases, the structure is destroyed, lumpy aggregates form, and the proportion of planar voids increases. The downslope transport of the soil solid phase under the impact of erosion is accompanied by the accumulation of the transformation products of carbohydrates, phenolic compounds, and black carbon in the passive pool of SOM in the Chernozems in the lower part of the catena. In the Chernozems located in the transit position of the slope, the composition of SOM is characterized by the predominance of lipids and nitrogen-containing compounds. Our unique results contribute to a deeper understanding of the formation of structure and water resistance in eroded soils.

Responses of Nutritional Status and Productivity of Timor Mango Trees to Foliar Spray of Conventional and/or Nano Zinc

The management of mango orchards is beset with a number of issues, including micronutrient deficits and significant fruit drop, which both contribute to decreases in mango tree output. Among these micronutrients, zinc is vital for increasing agricultural productivity, ensuring crop sustainability, and improving plant nutritional status during the growing season. To overcome zinc (Zn) deficiencies, this study was carried out during two successive seasons in an expected “Off” year (2022) and an expected “On” year (2023) on mature mango trees cv. Timor. To ameliorate this Zn deficiency, the effect of zinc in three forms—zinc oxide nanoparticles (ZnO NPs), sulfate (ZnSO4), and chelated (Zn-chelated)—as a foliar sprayon leaves’ mineral, chlorophyll, total carotenoids, and total carbohydrate contents and productivity were studied. Ten spray treatments were used in this study, including nano zinc (100 ppm), zinc sulfate (0.1%), and chelated zinc (0.2%) on two occasions, 7 January and 4 weeks after the first application, either alone or in combination with each other as compared to the control. In both study seasons, the results showed that all the zinc forms in mineral, chelated, or nano form had a positive effect on the number of flowers per panicle, the percentage of fruit set, the number of fruits per panicle, and the number of fruits per tree, and it decreased the percentage of fruit drop. Furthermore, all zinc forms significantly increased the leaf N, P, K, Ca, Mg, Cu, Fe, Mn, B, and Zn contents (%), and all the treatments improved the chlorophyll, total carotenoid, and total carbohydrate contents compared with the other treatments. The most effective treatment was two applications of nano zinc at 100 ppm in terms of the nutritional status and productivity of Timor mango trees.

Rethinking Aspergillosis in the Era of Microbiota and Mycobiota.

Aspergillosis encompasses a wide range of clinical conditions based on the interaction between Aspergillus and the host. It ranges from colonization to invasive aspergillosis. The human lung provides an entry door for Aspergillus. Aspergillus has virulence characteristics such as conidia, rapid growth at body temperature, and the production of specific proteins, carbohydrates, and secondary metabolites that allow A. fumigatus to infiltrate the lung's alveoli and cause invasive aspergillosis. Alveolar epithelial cells play an important role in both fungus clearance and immune cell recruitment via cytokine release. Although the innate immune system quickly clears conidia in immunocompetent hosts, A. fumigatus has evolved multiple virulence factors in order to escape immune response such as ROS detoxifying enzymes, the rodlet layer, DHN-melanin and toxins. Bacterial co-infections or interactions can alter the immune response, impact Aspergillus growth and virulence, enhance biofilm formation, confound diagnosis, and reduce treatment efficacy. The gut microbiome's makeup influences pulmonary immune responses generated by A. fumigatus infection and vice versa. The real-time PCR for Aspergillus DNA detection might be a particularly useful tool to diagnose pulmonary aspergillosis. Metagenomics analyses allow quick and easy detection and identification of a great variety of fungi in different clinical samples, although optimization is still required particularly for the use of NGS techniques. This review will analyze the current state of aspergillosis in light of recent discoveries in the microbiota and mycobiota.

Characterization of Aspergillus fumigatus secretome during sublethal infection of Galleria mellonella larvae.

Introduction. The fungal pathogen Aspergillus fumigatus can induce prolonged colonization of the lungs of susceptible patients, resulting in conditions such as allergic bronchopulmonary aspergillosis and chronic pulmonary aspergillosis.Hypothesis. Analysis of the A. fumigatus secretome released during sub-lethal infection of G. mellonella larvae may give an insight into products released during prolonged human colonisation.Methodology. Galleria mellonella larvae were infected with A. fumigatus, and the metabolism of host carbohydrate and proteins and production of fungal virulence factors were analysed. Label-free qualitative proteomic analysis was performed to identify fungal proteins in larvae at 96 hours post-infection and also to identify changes in the Galleria proteome as a result of infection.Results. Infected larvae demonstrated increasing concentrations of gliotoxin and siderophore and displayed reduced amounts of haemolymph carbohydrate and protein. Fungal proteins (399) were detected by qualitative proteomic analysis in cell-free haemolymph at 96 hours and could be categorized into seven groups, including virulence (n = 25), stress response (n = 34), DNA repair and replication (n = 39), translation (n = 22), metabolism (n = 42), released intracellular (n = 28) and cellular development and cell cycle (n = 53). Analysis of the Gallerial proteome at 96 hours post-infection revealed changes in the abundance of proteins associated with immune function, metabolism, cellular structure, insect development, transcription/translation and detoxification.Conclusion. Characterizing the impact of the fungal secretome on the host may provide an insight into how A. fumigatus damages tissue and suppresses the immune response during long-term pulmonary colonization.

Assessment of Biochemical Changes of Four Aspergillus Species Grown on the Medium from Agricultural Wastes

Hazardous disposal of agricultural wastes (AW) has adverse environmental consequences, including water and air pollution and the potential for disease outbreaks. On the other hand, the utilization of AW represents a missed opportunity to harness a valuable economic resource. This study was conducted with the objective of utilizing a composite medium comprising agricultural waste to cultivate Aspergillus species and assessing its impact on the species' internal chemical composition compared to malt extract media (ME). Our findings demonstrate that the agricultural waste-based medium is abundant in essential nutrients, including soluble proteins and sugars, and is also enriched with a variety of secondary metabolites. Consequently, this Change in the growth medium induces changes in the physical characteristics of fungal biomass, such as color and texture, along with a high content of biomass proteins and secondary metabolites, including phenols, flavonoids, carotenoids, and antioxidants. The A. avenaceous gave the highest biomass (1.1412 ± 0.4 g), while the A. niger gave the highest value of proteins (16.06 ± 0.4 mg/g), phenols (33.37 ± 0.8 mg/g), flavonoids (4.84 ± 0.4 mg/g), carotenoids (1.131 ± 0.09 mg/g). A. carbonarius gave the highest value of antioxidants (IC50 = 0.28 ± 0.06 mg/mL). In contrast, using malt extract as a growth medium results in high carbohydrate and lipid production; A. flavus showed the highest value for fats (56.6 ± 0.9 mg/g), whereas A. carbonarius showed the highest value for sugars (167.1 ± 6.2 mg/g). Additionally, the malt extract medium contributed to low levels of secondary metabolites, which was offset by an increase in the protein bands of the fungal species. This research recommends the use of agricultural wastes to grow fungi species as an environmentally and economically important microbiological application.

Feeding a Novel Mannan-Rich Yeast Carbohydrate Product Improves Production Performance and Humoral Immunity of Broiler Chickens.

The current study examined the benefits of a novel mannan-rich yeast carbohydrate product (YM) on broiler chicken growth performance and immune response against sheep red blood cells (SRBCs). A total of 144 newly hatched male Cornish cross broiler chicks were randomly assigned to four treatments with 12 cages per treatment and three birds per cage. The treatments were (1) control, basal diet; (2) YCW, basal diet + 1 g/kg yeast cell wall; (3) YM1, basal diet + 0.5 g/kg of a novel yeast mannan-rich product (YM); and (4) YM2, basal diet + 1 g/kg YM. Growth performance was measured at 14, 28, and 35 days of age (d). At 26 and 27 d, nine birds per treatment were immunized intravenously with SRBCs, and antibody responses against SRBCs were analyzed through a hemagglutination assay 7 days post-inoculation. Supplementing YM tended to improve broiler chicken weight gain from 29 to 35 d (p = 0.053). An improvement in the feed conversion ratio (FCR) was observed in the birds fed YM diets during 29-35 d and over the entire experimental period (0-35 d; p < 0.05). Furthermore, birds fed YM2 diets had more robust antibody responses against SRBCs than the control birds (p = 0.033). In conclusion, dietary supplementation of YM improved broiler chicken growth performance and antibody response against SRBCs.

Enhancement of biomass productivity and biochemical composition of alkaliphilic microalgae by mixotrophic cultivation using cheese whey for biofuel production

The growth of microalgae under alkaline conditions ensures an ample supply of CO2 from the atmosphere, with a low risk of crashing due to contamination and predators. The present study investigated the mixotrophic cultivation of two alkaliphilic microalgae (Tetradesmus obliquus and Cyanothece sp.) using cheese whey as an organic carbon source. The variation in cheese whey concentration (0.5–4.5% (v/v)), culture pH (7–11), and NaNO3 concentrations (0–2 gL−1) was evaluated using central composite design in response to biomass productivity and the contents of lipids, total proteins, and soluble carbohydrates. Both investigated microalgae effectively utilized cheese whey as an organic carbon source. The optimum conditions for simultaneously maximizing biomass and lipid productivity in T. obliquus were 3.5% (v/v) whey, pH 10.0, and 0.5 g L−1 NaNO3. Under these conditions, the biomass, lipid, soluble carbohydrate, and protein productivities were 48.69, 20.64, 7.02, and 10.97 mg L−1 day−1, respectively. Meanwhile, Cyanothece produced 52.78, 11.42, 4.31, and 7.89 mg L−1 day−1 of biomass, lipid, carbohydrate, and protein, respectively, at 4.5% (v/v) whey, pH 9.0, and 1.0 g L−1 NaNO3. The lipids produced under these conditions were rich in saturated fatty acids (FAs) and monounsaturated FAs, with no polyunsaturated FAs in both microalgae. Moreover, several biodiesel characteristics were estimated, and results fell within the ranges specified by international standards. These findings indicate that the mixotrophic cultivation of alkaliphilic microalgae could open new avenues for promoting microalgae productivity through low-cost biofuel production.

Density and Composition of Cohabiting Bacteria in Chlorella vulgaris CCAP 211/21A Is Influenced by Changes in Nutrient Supply

Microalgae have considerable potential as a renewable feedstock for biochemical and bioethanol production that can be employed in processes associated with carbon capture. Large-scale microalgae cultivations are often non-axenic and are often cohabited by bacteria. A better understanding of the influence of cohabiting bacteria on microalgae productivity is required to develop sustainable synthetic co-culture processes at scale. Nutrient limitation is a frequently employed strategy in algal cultivations to accumulate energy reserves, such as lipids and carbohydrates. Here, a non-axenic culture of an estuarine green microalga, Chlorella vulgaris CCAP 211/21A, was studied under nutrient replete and deplete conditions to assess how changes in nutrient supply influenced the cohabiting bacterial population and its association with intracellular carbohydrate accumulations in the alga. Nutrient limitation resulted in a maximum carbohydrate yield of 47%, which was 74% higher than that in nutrient replete conditions. However, the latter condition elicited a 2-fold higher carbohydrate productivity. Three cohabiting bacterial isolates were cultivable from the three culture conditions tested. These isolates were identified using the 16S rRNA gene sequence to belong to Halomonas sp. and Muricauda sp. The composition of the bacterial population varied significantly between the growth conditions and time points. In all cases and at all time points, the dominant species was Halomonas isolates. Nutrient depletion resulted in an apparent loss of Muricauda sp. This finding demonstrates that nutrient supply can be used to control cohabiting bacterial populations in algal cultures, which will enable the development of synthetic co-culture strategies for improving algae productivity.

Accumulation of Hydrogen Peroxide in Flag Leaves Induces Effective Regeneration of Triticale During Rehydration After Water Stress

A key element in the effective recovery of plants after drought is slowing down of their senescence accelerated during the drought. Therefore, in this paper the relationships between hydrogen peroxide content and effective recovery during rehydration after water stress were analyzed. The study focused on two DH lines of winter triticale with different regeneration potential, as shown by different numbers of lateral stems with ears, grown during rehydration after water stress. During rehydration, the GZDH27 line grows two to three lateral stems with ears, whereas the GZDH88 line grows a single lateral stem with ear. The two DH lines of winter triticale showed comparable responses to the drought stress but their responses to rehydration after the drought stress were clearly different. Results revealed, that the increased accumulation of hydrogen peroxide, which was induced during the drought, can be maintained during rehydration, thus stimulating plant senescence. In the line GZDH88, rehydration did not slow down drought-induced senescence. This was manifested by higher levels of hydrogen peroxide, accompanied by lower levels of chlorophyll in the flag leaves of GZDH88 plants, as the result of which only one lateral stem was formed during rehydration. However, development of one lateral stems during rehydration in the GZDH88 line allowed for smaller yield loss than in the GZDH77 line, that developed of three lateral stems during rehydration. The efficient production of carbohydrates and their effective allocation into the ears of the lateral stems required considerable energy expenditure in the GZDH27 line. Our results indicate that growing three lateral stems with ears during rehydration does not guarantee limitation of grain yield loss. However, to reach the final conclusion, it is important to evaluate a greater number of triticale genotypes under drought stress and rehydration during various stages of a plants development.

Semi-continuous cultivation of EPS-producing marine cyanobacteria: A green biotechnology to remove dissolved metals obtaining metal-organic materials

Given the necessity for bioprocesses scaling-up, the present study aims to explore the potential of three marine cyanobacteria and a consortium, cultivated in semi-continuous mode, as a green approach for i) continuous exopolysaccharide-rich biomass production and ii) removal of positively charged metals (Cu, Ni, Zn) from mono and multi-metallic solutions. To ensure the effectiveness of both cellular and released exopolysaccharides, weekly harvested whole cultures were confined in dialysis tubings. The results revealed that all the tested cyanobacteria have a stronger affinity towards Cu in mono and three-metal systems. Despite the amount of metals removed per gram of biomass decreased with higher biosorbent dosage, the more soluble carbohydrates were produced, the greater was the metal uptake, underscoring the pivotal role of released exopolysaccharides in metal biosorption. According to this, Dactylococcopsis salina 16Som2 showed the highest carbohydrate productivity (142 mg L−1 d−1) and metal uptake (84 mg Cu g−1 biomass) representing a promising candidate for further studies. The semi-continuous cultivation of marine cyanobacteria here reported assures a schedulable production of exopolysaccharide-rich biosorbents with high metal removal and recovery potential, even from multi-metallic solutions, as a step forward in the industrial application of cyanobacteria.