Lysophosphatidylcholines Promote Influenza Virus Reproduction through the MAPK/JNK Pathway in PMA-Differentiated THP-1 Macrophages.

Obesity and metabolic syndrome alter serum lipid profiles. They also increase vulnerability to viral infections and worsen the survival rate and symptoms after infection. How serum lipids affect influenza virus proliferation is unclear. Here, we investigated the effects of lysophosphatidylcholines on influenza A virus (IAV) proliferation. IAV particles in the culture medium were titrated using extraction-free quantitative PCR, and viral RNA and protein levels were assessed using real-time PCR and Western blot, respectively. RNA sequencing data were analyzed using PCA and heatmap analysis, and pathway analysis was performed using the KEGG mapper and PathIN tools. Statistical analysis was conducted using SPSS21.0. LPC treatment of THP-1 cells significantly increased IAV proliferation and IAV RNA and protein levels, and saturated LPC was more active in IAV RNA expression than unsaturated LPC was. The functional analysis of genes affected by LPCs showed that the expression of genes involved in IAV signaling, such as suppressor of cytokine signaling 3 (SOCS3), phosphoinositide-3-kinase regulatory subunit 3 (PI3K) and AKT serine/threonine kinase 3 (AKT3), Toll-like receptor 7 (TKR7), and interferon gamma receptor 1 (IFNGR1), was changed by LPC. Altered influenza A pathways were linked with MAPK and PI3K/AKT signaling. Treatment with inhibitors of MAPK or PI3K attenuated viral gene expression changes induced by LPCs. The present study shows that LPCs stimulated virus reproduction by modifying the cellular environment to one in which viruses proliferated better. This was mediated by the MAPK, JNK, and PI3K/AKT pathways. Further animal studies are needed to confirm the link between LPCs from serum or the respiratory system and IAV proliferation.

Design of a Novel Sericite-Phosphoric Acid Framework for Enhancement of Pb(II) Adsorption.

In this study, phosphoric acid was used to attach anions to the weak interlayer structure of sericite, one of the clay minerals composed of a tetrahedral structure of silicate, to increase the adsorption capacity of cations. Natural sericite beads (NSB) and activated sericite beads with phosphoric acid (PSB) were prepared as beads in order to increase reusability and facilitate the separation of adsorbates and adsorbents. Using this, lead (Pb(II)) removal efficiency from an aqueous solution was comparatively analyzed. The pHpzc was 6.43 in NSB but lowered to 3.96 in PSB, confirming that more acidic functional groups were attached to the PSB surface. According to FT-IR analysis, P=O, P-O-C, P=OOH and P-O-P bonds appeared on the surface of the PSB adsorbent, and the peaks of carboxyl groups and OH-groups were large and broad. The maximum adsorption capacity of Langmuir was 52.08 mg/g for NSB and 163.93 mg/g for PSB. The adsorption process was close to physical adsorption for NSB and chemical adsorption for PSB, and both adsorbents were endothermic reactions in nature in that the higher the temperature, the higher the adsorption efficiency. The adsorption mechanism of Pb(II) to PSB was achieved by ion exchange, electrostatic interaction, hydrogen bonding, and complexation. The adsorption of Pb(II) using PSB was not significantly affected by the adsorption of competing ions and showed a high adsorption efficiency of 94% in reuse up to 6 times. This confirms the favorable feasibility of removing Pb(II) from industrial wastewater using PSB.

Assessment of sludge reduction and biogas production in two-step anaerobic co-digestion using sesame oil cake and sewage sludge.

The aim of this study was to investigate the sewage sludge reduction and biogas production using two-stage anaerobic co-digestion of sesame oil cake and sewage sludge. In the first stage (acidogenic fermentation), sesame oil cake (SOC) was acidogenic fermented to produce fermented sesame oil cake (FSOC). In the second step (anaerobic co-digestion), sewage sludge and FSOC were mixed in various ratios of (100:0 (R1), 70:30 (R2), 50:50 (R3), and 30:70 (R4)) and observed for 30 days at a mesophilization temperature of 35±2 °C. In the anaerobic co-digestion using FSOC as a co-feedstock, the volatile solids (VS) and total solids (TS) removal were in the range of 53.7-64.9 and 42.6-53.2% for R2 and R3, respectively. The highest cumulative biogas production (389.67 mL/g·VSin) and methane production (0.56 m3·CH4/kg·VS) was achieved with the R3. In addition, R3 had the shortest reaction delay time (λ), and stabilization of the process was the fastest of all samples. The co-digestion performance index (CPI) was determined to be 1.29, 1.39, and 1.10 for R2, R3, and R4, respectively. The highest value for R3 confirmed the highest synergistic effect. This suggests the possibility of biogas production using sesame oil cake.

In vitro anti-melanogenic effects of chimeric compounds, 2-(substituted benzylidene)-1,3-indanedione derivatives with a ß-phenyl-α, ß -unsaturated dicarbonyl scaffold.

Tyrosinase is considered a key contributor to melanogenesis, and safe, potent tyrosinase inhibitors are needed for medical and cosmetic purposes to treat skin hyperpigmentation and prevent fruit and vegetable browning. According to our accumulated SAR data on tyrosinase inhibitors, the ß-phenyl-α,ß-unsaturated carbonyl scaffold in either E or Z configurations, can confer potent tyrosinase inhibitory activity. In this study, twelve indanedione derivatives were synthesized as chimeric compounds with a ß-phenyl-α,ß-unsaturated dicarbonyl scaffold. Two of these derivatives, that is, compounds 2 and 3 (85% and 96% inhibition, respectively), at 50 µM inhibited mushroom tyrosinase markedly more potently than kojic acid (49% inhibition). Docking studies predicted that compounds 2 and 3 both inhibited tyrosinase competitively, and these findings were supported by Lineweaver-Burk plots. In addition, both compounds inhibited tyrosinase activity and reduced melanin contents in B16F10 cells more than kojic acid without perceptible cytotoxicity. These results support the notion that chimeric compounds with the ß-phenyl-α,ß-unsaturated dicarbonyl scaffold represent promising starting points for the development of potent tyrosinase inhibitors.

Urolithin and Reduced Urolithin Derivatives as Potent Inhibitors of Tyrosinase and Melanogenesis: Importance of the 4-Substituted Resorcinol Moiety.

We previously reported (E)-ß-phenyl-α,ß-unsaturated carbonyl scaffold ((E)-PUSC) played an important role in showing high tyrosinase inhibitory activity and that derivatives with a 4-substituted resorcinol moiety as the ß-phenyl group of the scaffold resulted in the greatest tyrosinase inhibitory activity. To examine whether the 4-substituted resorcinol moiety could impart tyrosinase inhibitory activity in the absence of the α,ß-unsaturated carbonyl moiety of the (E)-PUSC scaffold, 10 urolithin derivatives were synthesized. To obtain more candidate samples, the lactone ring in synthesized urolithins was reduced to produce nine reduced urolithins. Compounds 1c (IC50 = 18.09 ± 0.25 µM), 1h (IC50 = 4.14 ± 0.10 µM), and 2a (IC50 = 15.69 ± 0.40 µM) had greater mushroom tyrosinase-inhibitory activities than kojic acid (KA) (IC50 = 48.62 ± 3.38 µM). The SAR results suggest that the 4-substituted resorcinol motif makes an important contribution to tyrosinase inhibition. To investigate whether these compounds bind to human tyrosinase, a human tyrosinase homology model was developed. Docking simulations with mushroom and human tyrosinases showed that 1c, 1h, and 2a bind to the active site of both tyrosinases with higher binding affinities than KA. Pharmacophore analyses showed that two hydroxyl groups of the 4-substituted resorcinol entity act as hydrogen bond donors in both mushroom and human tyrosinases. Kinetic analyses indicated that these compounds were all competitive inhibitors. Compound 2a inhibited cellular tyrosinase activity and melanogenesis in α-MSH plus IBMX-stimulated B16F10 melanoma cells more strongly than KA. These results suggest that 2a is a promising candidate for the treatment of skin pigment disorders, and show the 4-substituted resorcinol entity importantly contributes to tyrosinase inhibition.

Novel Anti-Melanogenic Compounds, (Z)-5-(Substituted Benzylidene)-4-thioxothiazolidin-2-one Derivatives: In Vitro and In Silico Insights.

To confirm that the ß-phenyl-α,ß-unsaturated thiocarbonyl (PUSTC) scaffold, similar to the ß-phenyl-α,ß-unsaturated carbonyl (PUSC) scaffold, acts as a core inhibitory structure for tyrosinase, twelve (Z)-5-(substituted benzylidene)-4-thioxothiazolidin-2-one ((Z)-BTTZ) derivatives were designed and synthesized. Seven of the twelve derivatives showed stronger inhibitory activity than kojic acid against mushroom tyrosinase. Compound 2b (IC50 = 0.47 ± 0.97 µM) exerted a 141-fold higher inhibitory potency than kojic acid. Kinetic studies' results confirmed that compounds 2b and 2f are competitive tyrosinase inhibitors, which was supported by high binding affinities with the active site of tyrosinase by docking simulation. Docking results using a human tyrosinase homology model indicated that 2b and 2f might potently inhibit human tyrosinase. In vitro assays of 2b and 2f were conducted using B16F10 melanoma cells. Compounds 2b and 2f significantly and concentration-dependently inhibited intracellular melanin contents, and the anti-melanogenic effects of 2b at 10 µM and 2f at 25 µM were considerably greater than the inhibitory effect of kojic acid at 25 µM. Compounds 2b and 2f similarly inhibited cellular tyrosinase activity and melanin contents, indicating that the anti-melanogenic effects of both were due to tyrosinase inhibition. A strong binding affinity with the active site of tyrosinase and potent inhibitions of mushroom tyrosinase, cellular tyrosinase activity, and melanin generation in B16F10 cells indicates the PUSTC scaffold offers an attractive platform for the development of novel tyrosinase inhibitors.

Lablab Purpureus Protects HaCaT Cells from Oxidative Stress-Induced Cell Death through Nrf2-Mediated Heme Oxygenase-1 Expression via the Activation of p38 and ERK1/2.

Ultraviolet B (UV-B) radiation induces the extreme production of either reactive oxygen species (ROS) or inflammatory mediators. The aim of this study was to evaluate the antioxidant activities of 70% ethanolic extract of Lablab purpureus (LPE) and the underlying mechanisms using HaCaT cells exposed to UV-B. High-performance liquid chromatography (HPLC) confirmed the presence of gallic acid, catechin, and epicatechin in LPE. LPE was shown to have a very potent capacity to scavenge free radicals. The results showed that LPE prevented DNA damage and inhibited the generation of ROS in HaCaT cells without causing any toxicity. LPE increased the expression of endogenous antioxidant enzymes such as superoxide dismutase-1 and catalase. Furthermore, LPE treatment facilitates the nuclear translocation of nuclear factor (erythroid-derived 2)-like 2 (Nrf-2), boosting the phase II detoxifying enzyme heme oxygenase-1 (HO-1) leading to the combatting of oxidative stress. However, pretreatment of LPE also caused the phosphorylation of mitogen-activated protein kinases (MAPK kinase) (p38 kinase) and extracellular signal-regulated kinase (ERK), whereas treatment with p38 and ERK inhibitors substantially suppressed LPE-induced Nrf2 and heme oxygenase (HO)-1 expression. These findings suggest that LPE exhibits antioxidant activity via Nrf-2-mediated HO-1 signaling through the activation of p38 and ERK, indicating that LPE can potentially be used as a remedy to combat oxidative stress-induced disorder.

Acid-fermented fish by-products broth: An influence to sludge reduction and biogas production in an anaerobic co-digestion.

This study investigates the effects of anaerobic co-digestion of a fishery by-products broth (FFB) mixed with sewage sludge on biogas production and sludge reduction. A 5:5 mixing ratio of sewage sludge and FFB generated the highest removal efficiency of volatile solids (VS) (51.3%), total solids (TS) (48.7%) and chemical oxygen demand (COD) (51.3%). In addition, the highest biogas production (0.585 L/g·VSin·d) was also achieved with a mixing ratio of 5:5, followed 0.305 L/g·VSin·d for 7:3. The methane content in produced biogas was associated more than 70% with ratios of 7:3 and 5:5. Moreover, the 5:5 ratio produced the greatest amount of the energy recovered at 4.1 kWh, followed by the 7:3 mixing ratio at 3.4 kWh. Therefore, the mixing ratio from 7:3 to 5:5 for anaerobic co-digestion of sewage sludge and FFB may be suitable for biogas production and organic matter removal. However, a 5:5 mixing ratio is recommended for anaerobic digestion of sewage sludge and FFB because it has the highest digestion efficiency, can treat larger quantities of fish by-products, and can recover the most energy. Biogas produced by mixing FFB with sewage sludge opens up the possibility of biogas production using organic waste because of the higher methane content.

Assessment of the adsorption kinetics, equilibrium and thermodynamic for Pb(II) removal using a hybrid adsorbent, eggshell and sericite, in aqueous solution.

Hybrid adsorbents (ES) were prepared with mixing of eggshell and sericite as binders, and Pb(II) was removed from aqueous solutions. Sericite has the advantage of not only serving as a binder for hybrid adsorbent but also having a negative charge on the surface to improve the removal efficiency of heavy metals. Various parameters affecting the removal of Pb(II) from aqueous solutions were investigated using the optimal conditions derived. In addition, adsorption kinetics, adsorption isotherms and thermodynamic analyses were performed using the experimental results of each parameter. The ES had a more specific surface area and porosity than sericite or eggshell and contained a large number of OH groups favoring heavy metal adsorption. As a result of the adsorption of Pb(II) using the ES, the adsorption process was physical and suitable for the Freundlich isotherm. In addition, the adsorption process of Pb(II) by the ES was a spontaneous endothermic reaction. The ES can quickly reach the adsorption equilibrium and strong adsorption strength. In addition, the CaOH contained in the ES can neutralize the pH of wastewater, and it is possible to treat heavy metal ions in industrial wastewater and acid mine wastewater without controlling the pH. ES adsorbents using waste eggshells are very economic because they recycle what would otherwise be waste and have great significance in terms of resource reuse.

Cytotoxic properties of the anthraquinone derivatives isolated from the roots of Rubia philippinensis.

BACKGROUND: Cancer is one of the most frequently occurring diseases and is the second leading cause of death worldwide. In this study, anthraquinone derivatives (Compounds 1-5) were evaluated for their anti-cancer potential against various skin and breast cancer cell lines to assess whether these anthraquinone derivatives may serve as a lead for the augmentation of anti-cancer drug. METHODS: Anthraquinone derivatives, 2-methyl-1,3,6-trihydroxy-9,10-anthraquinone-3-O-(6'-O-acetyl)-α-rhamnosyl(1 → 2)-ß-glucoside (Comp 1), 2-methyl-1,3,6-trihydroxy-9,10-anthraquinone (Comp 2), and alizarin (Comp 3) were isolated from the dichloromethane fraction of the roots of Rubia philippinensis., whereas ethyl acetate fraction yielded xanthopurpurin (Comp 4) and lucidin-ω-methyl ether (Comp 5). Structures of all the isolated compounds were determined by spectral data analysis. All isolated compounds (Comp 1-5) were assessed for cytotoxicity by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against four different cancer cell lines, i.e. human melanoma (SK-MEL-5), murine melanoma (B16F10), and human breast adenocarcinoma (MCF7 and MDA-MB-231). RESULTS: Significant activity of the compounds 4 and 5 was observed against the breast cancer cell line MDA-MB-231 with IC50 values of 14.65 ± 1.45 and 13.03 ± 0.33 µM, respectively. Encouragingly, IC50 values of 67.89 ± 1.02 and 79.01 ± 0.03 µM against normal kidney epithelial cells (MDCK) were also obtained for compounds 4 and 5, respectively, which indicated very low toxicity and favorable selectivity indices for compounds 4 and 5 in the range of 1.85 to 3.95 and 2.11 to 6.06 against skin cancer cell lines (SK-MEL-5, and B16F10), and breast cancer cell lines (MCF7 and MDA-MB-231), respectively. CONCLUSION: Our results suggested that the compounds 4 (xanthopurpurin) and 5 (lucidin-ω-methyl ether) showed high selective toxicity towards breast cancer cells at lower concentrations without showing toxicity towards normal cells, thus could be of potential as new lead molecules in cancer treatment.

Antimelanogenic Effect of an Oroxylum indicum Seed Extract by Suppression of MITF Expression through Activation of MAPK Signaling Protein.

In this study, the antimelanogenic effect of an ethyl acetate fraction of Oroxylum indicum Vent. seeds (OISEA) and its underlying mechanisms in melan-a cells were investigated. Antimelanogenesis activity was confirmed by assessing inhibition of tyrosinase activity and melanin content in the cells. Both transcriptional and translational expression of microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase related protein-1 and 2 (TYRP-1 and TYRP-2), were also examined. The results depicted that pretreatment of OISEA significantly inhibits not only tyrosinase activity, but melanin production and intracellular tyrosinase activity. By repressing the expression of tyrosinase, TYRP-1, TYRP-2, and MITF, OISEA interrupted melanin production. Additionally, OISEA interfered with the phosphorylation of p38, extracellular signal-regulated kinase 1/2 (ERK1/2), and c-Jun N-terminal kinase (JNK), with the reversal of OISEA-induced melanogenesis inhibition after treatment with the specific inhibitors SB239063, U0126, and SP600125. Overall, these results suggest that OISEA can stimulate p38, ERK1/2, JNK phosphorylation, and subsequent suppression of melanin, leading to the inhibition of melanogenic enzymes and melanin production, possibly owing to the presence of polyphenolic compounds.

Persimmon leaf bio-waste for adsorptive removal of heavy metals from aqueous solution.

The aim of this study was to investigate heavy metal removal using waste biomass adsorbent, persimmon leaves, in an aqueous solution. Persimmon leaves, which are biomaterials, have a large number of hydroxyl groups and are highly suitable for removal of heavy metals. Therefore, in this study, we investigated the possibility of removal of Cu, Pb, and Cd in aqueous solution by using raw persimmon leaves (RPL) and dried persimmon leaves (DPL). Removal of heavy metals by RPL and DPL showed that DPL had a 10%-15% higher removal than RPL, and the order of removal efficiency was found to be Pb > Cu > Cd. The pseudo-second order model was a better fit to the heavy metal adsorption experiments using RPL and DPL than the pseudo-first order model. The adsorption of Cu, Pb, and Cd by DPL was more suitable with the Freundlich isothermal adsorption and showed an ion exchange reaction which occurred in the uneven adsorption surface layer. The maximum adsorption capacity of Cu, Pb, and Cd was determined to be 19.42 mg/g, 22.59 mg/g, and 18.26 mg/g, respectively. The result of the adsorption experiments showed that the n value was higher than 2 regardless of the dose, indicating that the heavy metal adsorption on DPL was easy. In the thermodynamic experiment, ΔG° was a negative value, and ΔH° and ΔS° were positive values. It can be seen that the heavy metal adsorption process using DPL was spontaneous in nature and was an endothermic process. Moreover, as the temperature increased, the adsorption increased, and the affinity of heavy metal adsorption to DPL was very good. This experiment, in which heavy metals are removed using the waste biomass of persimmon leaves is an eco-friendly new bioadsorbent method because it can remove heavy metals without using chemicals while utilizing waste recycling.

Application of hybrid bead, persimmon leaf and chitosan for the treatment of aqueous solution contaminated with toxic heavy metal ions.

In this study, hybrid beads, which are made by mixing persimmon leaf and chitosan, was used to remove Pb(II) and Cd(II) from aqueous solution. According to the Fourier transform infrared spectrometry (FT-IR) analysis, the hybrid bead has a structure that enables the easy adsorption of heavy metals because it has carboxylic, carbonyl groups, O-H carboxylic acid, and bonded -OH groups. The adsorption of Pb(II) and Cd(II) by hybrid beads was more suitable with the Langmuir isothermal adsorption and showed an ion exchange reaction which occurred in the uneven adsorption surface layer. The maximum adsorption capacity of Pb(II) and Cd(II) was determined to be 278.68 mg/g and 87.91 mg/g, respectively. Furthermore, the adsorption removal process of Pb(II) and Cd(II) using hybrid beads is a spontaneous exothermic reaction and the affinity of the adsorbed material for the adsorbent is excellent. Hybrid beads are inexpensive, have a high removal efficiency of heavy metals, and are environmentally friendly.

Use of methyl esterified eggshell membrane for treatment of aqueous solutions contaminated with anionic sulfur dye.

The present study assessed the adsorption of an anionic dye (sulfur blue) by methyl-esterified eggshell membrane (MESM), a low-cost and abundant material from waste. Adsorption kinetics were investigated using parameters such as pH, contact time, initial dye concentration, solution temperature, dosage of adsorbent, and particle size of adsorbent. After methyl esterification, the specific surface area significantly increased and the negative surface charge of the eggshell membrane changed to positive for all pH values, which increased the sulfur dye sorption capacity. The optimal conditions for sorption of sulfur dye onto MESM resulted in >98% removal and were as follows: <35 µm particle size, pH 8, 20 min contact time and 313 K temperature. In this respect, 0.68-0.73 dry weight mg/L sulfur dye was adsorbed per 1 mg/L MESM. The Langmuir adsorption capacity for sulfur dye was 187.6 mg/g. In addition, sulfur removal was spontaneous and uptake was endothermic. MESM is an inexpensive and effective adsorbent.

Enhanced biomass production through optimization of carbon source and utilization of wastewater as a nutrient source.

The study aimed to utilize the domestic wastewater as nutrient feedstock for mixotrophic cultivation of microalgae by evaluating appropriate carbon source. The microalgae Chlorella vulgaris was cultivated in municipal wastewater under various carbon sources (glucose, glycerol, and acetate), followed by optimization of appropriate carbon source concentration to augment the biomass, lipid, and carbohydrate contents. Under optimized conditions, namely of 5 g/L glucose, C. vulgaris showed higher increments of biomass with 1.39 g/L dry cell weight achieving biomass productivity of 0.13 g/L/d. The biomass accumulated 19.29 ± 1.83% total lipid, 41.4 ± 1.46% carbohydrate, and 33.06 ± 1.87% proteins. Moreover, the cultivation of Chlorella sp. in glucose-supplemented wastewater removed 96.9% chemical oxygen demand, 65.3% total nitrogen, and 71.2% total phosphate. The fatty acid methyl ester obtained showed higher amount (61.94%) of saturated fatty acid methyl esters associated with the improved fuel properties. These results suggest that mixotrophic cultivation using glucose offers great potential in the production of renewable biomass, wastewater treatment, and consequent production of high-value microalgal oil.

Integration of microalgal cultivation system for wastewater remediation and sustainable biomass production.

Untreated wastewaters have been a great concern and can cause major pollution problems for environment. Conventional approaches for treating wastewater involve tremendous capital cost, have major short comings and are not sustainable. Microalgae culture offers an interesting step for wastewater treatment. Microalgae serve the dual purpose of phycoremediation along with the production of potentially valuable biomass, which can be used for several purposes. The ability of microalgae to accumulate nitrogen, phosphorus, heavy metals and other toxic compounds can be integrated with wastewater treatment system to offer an elegant solution towards tertiary and quaternary treatment. The current review explores possible role of microalgal based wastewater treatment and explores the current progress, key challenges, limitations and future prospects with special emphasis on strategies involved in harvesting, boosting biomass and lipid yield.

Harvesting of microalgae species using Mg-sericite flocculant.

In this study, Mg-sericite was used as a flocculant to harvest freshwater microalgae Chlorella vulgaris. Mg-sericite separated successfully >99% of the C. vulgaris at the following optimal parameters: sericite and MgCl2 ratio (S/M ratio) of 45 to 15, mixing time of 5 min, mixing rate 100 to 150 rpm and settling time of 5 min. The harvesting efficiency was pH dependent. The highest harvesting efficiency (99 ± 0.3%) was obtained at S/M ratio 40 and pH 9-11. These results indicated that a biopolymer, Mg-sericite, can be a promising flocculant due to its high efficiency, low-dose requirements, and short mixing and settling times. In addition, Mg-sericite does not contaminate the growth medium, which can be recycled to reduce not only the cost and the demand for water, but also the extra operational costs for reusing the growth medium. This harvesting method is helpful to lower the production cost of algae for biodiesel.

A mini review: photobioreactors for large scale algal cultivation.

Microalgae cultivation has gained much interest in terms of the production of foods, biofuels, and bioactive compounds and offers a great potential option for cleaning the environment through CO2 sequestration and wastewater treatment. Although open pond cultivation is most affordable option, there tends to be insufficient control on growth conditions and the risk of contamination. In contrast, while providing minimal risk of contamination, closed photobioreactors offer better control on culture conditions, such as: CO2 supply, water supply, optimal temperatures, efficient exposure to light, culture density, pH levels, and mixing rates. For a large scale production of biomass, efficient photobioreactors are required. This review paper describes general design considerations pertaining to photobioreactor systems, in order to cultivate microalgae for biomass production. It also discusses the current challenges in designing of photobioreactors for the production of low-cost biomass.

Effect of optical panel thickness for nutrient removal and cultivation of microalgae in the photobioreactor.

The aim of this study was to quantitatively evaluate the effect of the illumination area and the thickness of the optical panel (OP) on the biomass growth of Chlorella vulgaris (C. vulgaris) algae with simultaneous removal of nutrients. For this purpose, three different thicknesses of OPs were used and designated as follows: 4 mm v-cut OP (Run 1), 6 mm v-cut OP (Run 2) and 8 mm v-cut OP (Run 3). The results indicated that the Run 2 and Run 3 samples possessed higher chlorophyll content, as calculated per cell and per unit area of the cell volume, and a shorter doubling time compared to the Run 1 samples. The growth of the biomass using Run 2 and Run 3 was approximately 11.18 %, and this growth was higher than that of Run 1. Furthermore, higher nutrient removal was observed with Run 2 than Run 1. The nutrient removal, biomass growth and specific growth rate for the Run 2 and Run 3 fractions were found to be almost identical. However, in terms of economic consideration, Run 2 with simultaneous nutrient removal was more effective than Run 1 and Run 3 in cultivating the microalgae C. vulgaris.

Effect of optical panel distance in a photobioreactor for nutrient removal and cultivation of microalgae.

The aim of present investigation is to assess the effect of illumination area and distance of an optical panel (OP) on the growth of microalgae with simultaneous removal of nutrients. Four different distances of OPs were used i.e. 225 mm OP (Run 1), 150 mm OP (Run 2), 112.5 mm OP (Run 3) and 90 mm distance OP (Run 4) in the photobioreactor (PBR) operations. The PBR was equipped with an OP and operated with a total volume of 37-l. A batch culture was prepared using an initial cell concentration of 1.12 ± 0.05 g l(-1). The experiments were conducted at neutral pH (7.2 ± 0.3) under dark and light cycles of 8 and 16 h, respectively. The diffuse light intensity was recorded as 91, 93, 95 and 98% for Run 1, Run 2, Run 3 and Run 4, respectively, at a 300 mm depth level in the PBR. The chlorophyll content per cell was found to be an average of 701, 721, 785 and 808 fg for Run 1, Run 2, Run 3 and Run 4, respectively. High chlorophyll content per cell and diffuse light intensity was observed for Run 4 compared to other fractions. However, Run 3 sample possessed approximately 10.51% higher biomass growth along with 15.22% chemical oxygen demand, 18.15% total nitrogen 2.37% NH4-N, 15.1% total phosphorus and 15.05% PO4-P more removal than the Run 1. These findings suggest that in terms of economic consideration and efficiency of nutrients removal, Run 3 is found to be more effective than other samples. Moreover, an enhanced growth of Chlorella vulgaris could further be utilized as a potential biodiesel source.