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Numerous studies have indicated that fruits and vegetables are considered as significant sources of bioactive compounds. The generated by-products, which are derived from the food industry, reveal similar or higher antioxidant activity. On the other hand, intense industrialization results in the production of large volumes of by-products, raising serious environmental issues. Therefore, this situation creates the necessity to develop new strategies in order to exploit the generated wastes, securing the ability to develop new high-added-value products. This review aims to summarize the exploitation of fruit wastes, namely, apple and citrus, as well as vegetable by-products which are derived from tomato, potato and carrot cultivation. All the aforementioned by-products have found wide applications in the development of new high-added-value products in the food and feed industry owing to their improved nutritional profiles. Furthermore, these wastes are characterized by a strong antioxidant activity, justifying their valorization in other fields such as cosmetics and pharmaceutical industries.

The study herein concerns the application of the solid-state fermentation (SSF) bioprocess of agro-industrial wastes as a means to improve their nutritional composition, targeting their utilization as proteinaceous animal feed. The fermentation outcome resulted from the mixtures of Olive Mill Stone Waste (OMSW) with Pistachio Shell (PS) and PS with Lathyrus clymenum pericarp (LP) at various proportions via SSF initiated by P. ostreatus. The addition of 20% w/w of LPs to PS recorded the highest crude protein content (%) increase of 33.87% while concerning cellulose content, 50% w/w addition presented the highest value (37.68%). Concerning lignin presence, PS and its additions to OMSW recorded a reduction, the ratio of 100% w/w of PS was found to be decreased by 14.22% whereas, 20% w/w of LP additions to PS displayed an increment of 38.25%. Regarding β-glucans content, the mixture of 50% w/w of LP to PS recorded the highest value (5.19%) while 100% w/w of PS presented a vast increment exceeding 480-folds. The OMSW, PS and LP mixtures revealed their potential as supplements in animals’ diets after their nutritional upgrade through SSF. Such studies highlight the contribution to the confrontation of the unavailability of proteinaceous animal feed in the terms of a circular economy.

The enzyme alkaline phosphatase (ALP) is gaining interest because it exerts bioactive properties and may be a potentially important therapeutic agent for many disorders and diseases. Microalgae are considered an important novel source for the production of diverse bio-compounds and are gaining momentum as functional foods/feeds supplements. So far, studies for the production of ALP are limited to mammalian and partly to some heterotrophic microbial sources after its extraction and/or purification. Methods:&nbsp, Arthrospira was cultivated under P-limitation bioprocess and the effect of the P-limitation degree on the ALP enrichment was studied. The aim of this work was to optimize the cultivation of the edible and generally-recognized-as-safe (GRAS) cyanobacterium Arthrospira platensis for the production of single-cell (SC) biomass enriched in ALP as a potential novel functional diet supplement. Results: The results revealed that the relationship between intracellular-P and single-cell alkaline phosphatase (SC-ALP) activity was inverse, SC-ALP activity was the highest (around 50 U g−1) when intracellular-P was the lowest possible (around 1.7 mg-P g−1) and decreased gradually as P availability increased reaching around 0.5 U g−1 in the control cultures. Under the strongest P-limited conditions, a more than 100-fold increase in SC-ALP activity was obtained, however, protein content of A. platensis decreased significantly (around 22–23% from 58%). Under a moderate P-limitation degree (at intracellular-P of 3.6 mg-P g−1), there was a relatively high SC-ALP activity (&gt, 28 U g−1) while simultaneously, a relative high protein content (46%) was attained, which reflects the possibility to produce A. platensis enriched in ALP retaining though its nutritional value as a protein rich biomass source. The paper presents also results on how several parameters of the ALP activity assay, such as pH, temperature etc., and post-harvest treatment (hydrothermal treatment and biomass drying), influence the SC-ALP activity.

(1) Background: Arthrospira (commonly known as Spirulina) is an edible cyanobacterium that is produced worldwide as a food supplement owing to its high nutritional value. Arthrospira displays strong potential as an important ingredient in the development of novel functional foods. Polysaccharides from Arthrospira are biologically active compounds and hence there is interest in producing biomass rich in carbohydrates. (2) Methods: A. platensis was cultivated under different degrees of phosphorus limitation in order to trigger the accumulation of carbohydrates. The biomass was then characterized in terms of its content of α- and β-glucans, total dietary fiber and monosaccharide profile. Fourier-transform infrared spectroscopy (FTIR) was used for the rapid analysis of the main biomass components. (3) Results: Phosphorus limitation resulted in an increase in carbohydrates (from 23% up to 65% dry biomass) of which 4–12% (in relation to the dry biomass) was α-glucans and 20–34% was 1.3:1.6 β-glucans, while 1.4:1.6 β-glucans were not detected. Total dietary fibers ranged from 20–32% (of dry biomass), whereas among the carbohydrates, the predominant monosaccharide was glucose (&gt, 95%). FTIR performed well when applied as a prediction tool for the main biomass components. (4) Conclusions: Since β-glucans are of particular interest as biologically active compounds, this study demonstrates that phosphorus-limited A. platensis could be a potential ingredient for the development of novel functional foods.

Brewers’ Spent Grain (BSG) represents the 85% of the total residue produced during the beer brewing process, with a global annual production volume exceeding the 30 Mtons. Study herein concerns the application of solid state fermentation (SSF) process for the efficient transformation of BSG into high nutritional value animal feed. The investigated SSF procedure was initiated by Pleurotus ostreatus, which constitutes a natural source of β-glucans and metabolites (vitamins, nutrients). Thus, it is possible to reduce the environmental impacts caused by BSG production and simultaneously contribute to the tackling of proteinaceous animal feed shortage observed during the last decade. The method developed resulted in a significant increase of protein content by 49.49%, a 10-fold increase of their 1,3 − 1,6 β-glucans content and a respective reduction of cellulose content by 11.42%. The application of this method is expected to provide a solid background for the utilization of BSG as substrate for fungi initiated SSF, a bioprocess allowing the significant reduction of the environmental impact caused by the beer brewing industry and simultaneously produce animal feed with high protein content and nutritional characteristics suitable for fulfilling animals’ nutritional needs and improving their welfare.

This study examined the effects of monochromatic illumination (blue, red, green and yellow) employing light-emitting diodes (LEDs), trophic conditions (photoautotrophic and mixotrophic), and nitrogen availability (high and low peptone concentration) on the growth and biochemical composition of Auxenochlorella protothecoides. The results revealed that mixotrophic conditions did not favor A. protothecoides, giving lower growth rates compared to heterotrophy (dark conditions). However, mixotrophy gave significantly higher growth rates compared to photoautotrophy. The best light wavelengths for mixotrophic cultivation were that of white and red. In all cases investigated in this study, high peptone concentration (4 g/L) resulted in decreased growth rates. Regarding the biochemical composition of A. protothecoides, the strongest effect, irrespective of trophic conditions, was caused by nitrogen availability (peptone concentration). Specifically, at nitrogen replete conditions (4 g/L peptone), biomass was rich in proteins (32–67%), whereas under deplete conditions (0.5 g/L peptone), A. protothecoides accumulated mainly carbohydrates (up to 56%). Mixotrophic conditions generally favored higher carbohydrate content, whereas photoautotrophic conditions favored higher protein content. The different illumination spectra did not have any clear effect on the biochemical composition (metabolites content), except that, in all trophic conditions, the use of the green spectrum resulted in higher chlorophyll b content. Chlorophyll a fluorescence studies revealed that the trophic conditions and the high peptone concentrations impacted the photosystem II (PSII) performance, and also affected plastoquinone re-oxidation kinetics and the heterogeneity of the PSII reaction centers.

The interactive effects of light intensity, NaCl, nitrogen, and phosphorus on intracellular biomass content and extracellular polymeric substance production were assessed for Arthrospira sp. (Spirulina) in a two-phase culture process using principal component analysis and central composite face design. Under high light intensity (120 μmol photons m−2 s−1) and low NaCl (1 gL−1), NaNO3, and K2HPO4 (0.5 g L−1), the carbohydrate content was maximized to 26.61%. Interaction of both K2HPO4 (1.6 gL−1) and NaCl (1.19 gL−1) with low NaNO3 (0.5 gL−1) achieved the maximum content of lipids (15.62%), while high NaCl (40 gL−1), K2HPO4, and NaNO3 (4.5 gL−1) enhanced mainly total carotenoids (0.85%). Conversely, under low light intensity of 10 μmol photons m−2 s−1 combined with 11.76 gL−1 of NaCl, 0.5 gL−1 of NaNO3, and 2.68 gL−1 of K2HPO4, the phycobiliprotein content reached its highest level (16.09%). The maximum extracellular polymeric substance (EPS) production (0.902 gg−1 DW) was triggered under moderate light of 57.25 μmol photons m−2 s−1 and interaction of high NaCl (40 gL−1) and K2HPO4 (4.5 gL−1) with low NaNO3 (0.5 gL−1). The maximization ratios of intracellular biomass content in terms of carbohydrate, lipid, total carotenoid, phycobiliprotein, and EPS production were 3.55-, 1.73-, 9.55-, 2.92-, and 1.46-fold, respectively, greater than those obtained at optimal growth conditions. This study demonstrated that the multiple stress factors applied to the adopted two-phase culture process could be a promising strategy to produce biomass enriched in various high-value compound.

In this study, Arthrospira platensis was grown in the presence of different glycerol concentrations (0.5&ndash, 9 g/L) under three light intensities (5, 10 and 15 Klux) in semi-continuous mode and under non-axenic conditions. The aim of this study was to investigate the growth performance, the biomass biochemical composition and any interactions between A. platensis and bacteria that would potentially grow as well on glycerol. The results here show that glycerol did not have any positive effect on biomass production of A. platensis. In contrast, it was observed that by increasing glycerol concentration the growth performance of A. platensis was restricted, while a gradual increase of bacteria population was observed, which apparently outcompeted and repressed A. platensis growth. Chlorophyll fluorescence measurements (Quantum Yields) revealed that glycerol was not an inhibiting factor per se of photosynthesis. On the other hand, cyanobacterial biomass grown on glycerol displayed a higher content in proteins and lipids. Especially, protein productivity was enhanced around 15&ndash, 35% with the addition of glycerol compared to the control. In distinction, carbohydrate and photosynthetic pigments (phycocyanin and chlorophyll-&alpha, ) content decreased with the increase of glycerol concentration. The results here suggest that A. platensis did not utilize glycerol for biomass production but most probably as metabolic energy carrier towards synthesis of proteins and lipids, which are more energy consuming metabolites compared to carbohydrates. The study revealed that the addition of glycerol at amounts of 0.5&ndash, 1.5 g/L could be a strategy to improve protein productivity by A. platensis.

In the present paper, the use of raw poultry litter (PL) as a nutrient source for the cultivation of Arthrospira platensis and Chlorella vulgaris was investigated. PL was added to acid solution (62.5 mM H 2 SO 4 ) for the extraction of nutrients contained in PL. After settling, the supernatant, called PL leachate (PLL) was diluted 25 ×, 20 ×, 15 ×, and 10 × and used as a medium for the cultivation of A. platensis and C. vulgaris . A. platensis could not survive in 15 × and 10 × diluted leachate and while in 20 × and 25 × dilutions the biomass production was only half of that in a control medium (Zarrouk). The biomass composition had a high carbohydrate content (37–44%), which suggests that A. platensis was stressed due to nutrient limitation. C. vulgaris grew well in PLL-based media and the biomass production was higher than in the control medium (BG-11). Biomass composition of C. vulgaris in PLL-based media had lower protein content and higher carbohydrate and lipid content than in the control medium. The overall process for producing microalgal biomass from PL that we propose includes: (i) acid extraction of nutrients through the generation of PL leachate (PLL), (ii) indoor PL composting and recovery of stripped ammonia and CO 2 , and (iii) use of recovered ammonia and CO 2 along with the PLL for the cultivation of microalgae and cyanobacteria for the production of biomass.

Herein a new approach of exploiting poultry litter (PL) is demonstrated. The suggested method includes drying of PL with simultaneously striping and recovery of ammonia, followed by the direct combustion of dried PL. The generated ash after the combustion, and the striped ammonia consequently, could be used as nutrient source for the cultivation of microalgae or cyanobacteria to produce feed additives. The present study explored the application of PL ash and recovered ammonia for the cultivation of Arthrospira platensis and Chlorella vulgaris. For a simultaneously 90% dissolution of ash potassium and phosphorus, a ratio of acid to ash of 0.02mol-H(+)/g was required. The optimum mass of ash required was 0.07-0.08g/g dry biomass, while the addition of ammoniac nitrogen of 8-9mgN per g of dry biomass per day was adequate for a satisfactory production of A. platensis and C. vulgaris.

In the present work the cyanobacterium Arthrospira platensis and the microalga Chlorella vulgaris were fed-batch cultivated in ammonia-rich wastewater derived from the anaerobic digestion of poultry litter. Aim of the study was to maximize the biomass production along with the nutrient removal aiming to wastewater treatment. Ammonia and phosphorus removals were very high (>95%) for all cultures investigated. Both microorganisms were able to remove volatile fatty acids to an extent of >90%, indicating that they were capable of mixotrophic growth. Chemical oxygen demand and proteins were also removed in various degrees. In contrast, in all cultures carbohydrate concentration was increased. The biochemical composition of the microorganisms varied greatly and was influenced by the indicate that the nutrient availability. A. platensis accumulated carbohydrates (≈ 40%), while C. vulgaris accumulated lipids (≈ 50%), rendering them interesting for biofuel production.

In this study, the cyanobacterium Arthrospira platensis, commonly known as Spirulina, was cultivated utilizing phosphorus in the form of struvite recovered from effluents of a biogas plant treating municipal and agro-industrial wastes. Under the specific experimental conditions, providing sterilized struvite at about 120 mg/L (or 15 mg-P/L) gave the same results in terms of biomass production and biochemical composition as the control cultures (with KH2PO4 as a P source). Struvite sterilization was found to be an important step because its original microbial load had a negative effect on the biomass production and resulted in biomass with lower value (lower protein and phycocyanin content). P from struvite was almost complete released upon adding it in the cultivation medium after 90 min, where parameters, such as medium pH, struvite particle size and medium reusing cycles had no effect on the kinetics of P release, indicating that P is almost immediately available for cell uptake. Since struvite was generated from effluents of a biogas plant treating municipal and agro-industrial wastes, the potential of its contamination with hazardous compounds was examined in order to assess the safety of the produced biomass. Unwanted compounds like heavy metals, bisphenol A (BPA), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) were calculated to be at levels significantly lower than those of the maximum levels allowed in the European Union regulation for feedstuff safety, while neither veterinary drugs nor Escherichia coli were detected in the struvite. Results suggest that struvite recovered from biogas plants could be used as P source for the cultivation of A. platensis for feed or food quality.

The anaerobic digestion performance using carbohydrate-enriched biomass of Arthrospira platensis was studied. The carbohydrate enrichment was achieved after the cultivation of A. platensis under phosphorus limitation conditions. Three biomass compositions (60%, 40% and 20% carbohydrates content) were used. The overall observation as the biomass carbohydrates increased was that bio-methane yield increased. The highest bio-methane yield in bioreactors with 60% carbohydrates was 203 ± 10 ml CH 4 gCOD infl - 1 , while the lowest bio-methane yield in bioreactors with 20% carbohydrates was 123 ± 10 ml CH 4 gCOD infl - 1 . The trend of increasing bio-methane yield as carbohydrates content of the biomass increased was observed almost in all three HRT (15, 20 and 30 days) studied and after thermal pre-treatment. However, thermal pre-treatment did not improve the bio-methane yield. Ammonia concentration had an overall trend to decrease as the biomass carbohydrates content increased. This study concludes that the increase of biomass carbohydrates through phosphorus limitation process is an attractive technique to improve the bio-methane yield.

In the present study the potential of bioethanol production using carbohydrate-enriched biomass of the cyanobacterium Arthrospira platensis was studied. For the saccharification of the carbohydrate-enriched biomass, four acids (H2SO4, HNO3, HCl and H3PO4) were investigated. Each acid were used at four concentrations, 2.5 N, 1 N, 0.5 N and 0.25 N, and for each acid concentration the saccharification was conducted under four temperatures (40 °C, 60 °C, 80 °C and 100 °C). Higher acid concentrations gave in general higher reducing sugars (RS) yields (%, gRS/gTotal sugars) with higher rates, while the increase in temperature lead to higher rates at lower acid concentration. The hydrolysates then were used as substrate for ethanolic fermentation by a salt stress-adapted Saccharomyces cerevisiae strain. The bioethanol yield (%, gEtOH/gBiomass) was significantly affected by the acid concentration used for the saccharification of the carbohydrates. The highest bioethanol yields of 16.32% ± 0.90% (gEtOH/gBiomass) and 16.27% ± 0.97% (gEtOH/gBiomass) were obtained in hydrolysates produced with HNO3 0.5 N and H2SO4 0.5 N, respectively.

This paper presents the effects of various phosphorus concentrations (10, 50, 250 and 500 mg l(-1) K(2)HPO(4)) on the biomass production and composition of Arthrospira (Spirulina) platensis in relation to light intensity (24, 42 and 60 μE m(-2) s(-1)). The maximum biomass production was 3,592 ± 392 mg l(-1) and this was observed in 250 mg l(-1) K(2)HPO(4) at 60 μE m(-2) s(-1) light intensity after 32 days of cultivation. A maximum specific growth rate (μ(max)) of 0.55 d(-1) was obtained in 500 mg l(-1) K(2)HPO(4) at 60 μE m(-2) s(-1). The protein, lipid and chlorophyll contents of the biomass varied from 33.59 to 60.57 %, 5.34 to 13.33 % and 0.78 to 2.00 %, respectively. The most significant finding was that phosphorus limitation (10 mg l(-1) K(2)HPO(4)) caused a drastic increase of the carbohydrate content (59.64 %). The effect of phosphorus limitation on the carbohydrate content was independent of the light intensity. The accumulated carbohydrates are proposed to be used as substrate for biofuel generation via one of the appropriate biomass energy conversion technologies. Also, it was observed that phosphorus removal is a function of biomass density, phosphorus concentration and light intensity.

Carbohydrates are a desirable biomass compound for the generation of several biofuels. Phosphorus nutrient limitation causes a significant increase in the carbohydrate content of the cyanobacterium Arthrospira (Spirulina) platensis. Carbohydrates accumulated up to a content of 63.09 ± 3.43 % (±SD) in both batch and semi-continuous cultures. In order the production of carbohydrate-rich biomass through nutrient limitation to be maximized, it is suggested that the limited nutrients have to be supplied in amounts that they on one hand can support the biomass production while on the other hand they alter the composition of the biomass. In this study, phosphorus of 1.82 ± 0.16 mg g−1 of dry biomass was the optimized amount for the maximization of carbohydrates production by A. platensis. Regarding the need to decrease the application amounts of nutrients for biomass production, this study demonstrates that the phosphorus supply could be decreased an order of magnitude with no significant decrease in biomass production. In addition, it was observed that biomass rich in carbohydrates bio-flocculates, during settling without the addition of any flocculation agent or any other intervention. The bio-flocculation efficiency appears to be related with the carbohydrate content of the biomass. In maximum carbohydrate content (60 %), the biomass bio-flocculated at 68.49 ± 7.73 % the first 15 min and reached 80.25 ± 5.58 % 60 min after settling. The produced carbohydrates might be used as feedstock for biofuel generation, while the bio-flocculation and the overall settling characteristics of the carbohydrate-rich biomass could make its harvesting process much easier.

A study was conducted to investigate the effect of light intensity (21, 42, and 63 μmol photons m(-2) s(-1)) and photoperiod (8:16, 12:12, and 16:8 h light/dark) on the biomass production and its biochemical composition (total carotenoids, chlorophyll a, phycoerythrin (PE), phycocyanin (PC) and allophycocyanin (APC), total protein, and carbohydrates) of a local isolate of Nostoc calcicola. The results revealed that N. calcicola prefers dim light; however, the most of the levels of light intensity and photoperiod investigated did not have a significant impact on biomass production. Increasing light intensity biomass content of chlorophyll a, PE, PC, APC, and total protein decreased, while total carotenoids and carbohydrate increased. The same behavior was observed also when light duration (photoperiod) increased. The interaction effect of increasing light intensity and photoperiod resulted in an increase of carbohydrate and total carotenoids, and to the decrease of chlorophyll a, PE, PC, APC, and total protein content. The results indicate that varying the light regime, it is capable to manipulate the biochemical composition of the local isolate of N. calcicola, producing either valuable phycobiliproteins or proteins under low light intensity and shorter photoperiods, or producing carbohydrates and carotenoids under higher light intensities and longer photoperiods.

In this study the biomass composition alteration of the cyanobacterium Arthrospira (Spirulina) platensis under various amounts of limited phosphorus is studied. It was observed that the alteration of the compounds of the biomass occurred gradually as the phosphorus became limited. Carbohydrates and lipids increased from about 9% up to 65% and from about 4.9% up to 7.5%, respectively, while proteins decreased from about 46.5% to 25% as the phosphorus became limited. The increasing of carbohydrates and lipids in addition to the decrease of proteins resulted to an increase of the carbon to nitrogen (C/N) ratio from about 4.6 to 12.2.

In this study, zeolite was employed for the separation and recovery of P from synthetic wastewater and its use as phosphorus (P) source for the cultivation of the green microalga Chlorella vulgaris and the cyanobacterium Arthrospira (Spirulina) platensis. At P-loaded zeolite concentration of 0.15–1 g/L, in which P was limited, the two species displayed quite different behavior regarding their growth and biomass composition. C. vulgaris preferred to increase the intracellular P and did not synthesize biomass, while A. platensis synthesized biomass keeping the intracellular P as low as possible. In addition under P limitation, C. vulgaris did display some little alteration of the biomass composition, while A. platensis did it significantly, accumulating carbohydrates around 70% from about 15%–20% (control). Both species could desorb P from zeolite biologically. A. platensis could recover over 65% and C. vulgaris 25% of the P bounded onto zeolite. When P-loaded zeolite concentration increased to 5 g/L, P was adequate to support growth for both species. Especially in the case of C. vulgaris, growth was stimulated from the presence of P-loaded zeolite and produced more biomass compared to the control. ispartof: International Journal of Molecular Sciences vol:16 issue:2 pages:4250-4264 ispartof: location:Switzerland status: published

The filamentous cyanobacterium Arthrospira platensis is an attractive feedstock for carbohydrate-based biofuels because it accumulated up to 74% of carbohydrates when nitrogen stressed. Nitrogen stressed A. platensis also settled spontaneously, and this occurred simultaneously with carbohydrates accumulation, suggesting a link between both phenomena. The increased settling velocity was neither due to production of extracellular carbohydrates, nor due to degradation of gas vacuoles, but was caused by an increase in the specific density of the filaments as a result of accumulation of carbohydrates under the form of glycogen. Settling velocities of carbohydrate-rich A. platensis reached 0.64mh(-1), which allowed the biomass to be harvested using a lamella separator. The biomass could be concentrated at least 15 times, allowing removal of 94% of the water using gravity settling, thus offering a potential application as a low-cost and high-throughput method for primary dewatering of carbohydrate-rich A. platensis. publisher: Elsevier articletitle: Harvesting carbohydrate-rich Arthrospira platensis by spontaneous settling journaltitle: Bioresource Technology articlelink: http://dx.doi.org/10.1016/j.biortech.2014.12.084 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved. ispartof: Bioresource Technology vol:180 pages:16-21 ispartof: location:England status: published

In the present study, semi-continuous cultivation of Arthrospira platensis using various colors of light-emitting diodes (LEDs) as artificial lighting was performed in order to study their effects on the biomass composition of A. platensis. The lowest biomass productivity was obtained with blue LED (4.68 mg l(-1) day(-1)), while the highest was obtained with pink and red LEDs (30.89 and 30.69 mg l(-1) day(-1), respectively). All biomass compound contents were affected by the different colors studied, except that of total carotenoids. The lowest phycocyanin content was observed in pink LED (8.2%) while the maximum in blue LED (17.6 ± 2.4%). Chlorophyll content was lowest in red LED (1.04%) and highest in blue LED (1.42%). The highest protein content was obtained with white and green LEDs (50.1 and 49.8%, respectively), while the lowest was obtained with blue LED (42.1%). Carbohydrate content was contrarily affected as that of proteins. The highest carbohydrate content was obtained in blue LED (11.3%) and the lowest under white and pink LEDs (8.8 and 8.8%, respectively). Lipid content seems to follow the same trend as that of carbohydrates; the highest lipid content was obtained in blue LED (6.0%), and the lowest was obtained under pink LED (3.8%).