Aluminum (Al) is a major concern in acidic environments as it can lead to the accumulation of reactive oxygen species (ROS), which induce oxidative stress in the host. Assessment of Al-resistant microorganisms can help scientists to discover their mechanisms and improve bioremediation techniques. The present study aimed to characterize Al-resistant microalgae by screening industrial wastewater microorganisms. The microalgae were treated with 0, 10, and 100 mu M Al. Then, H2O2, malondialdehyde (MDA), catalase (CAT), and peroxidase (POX) values were measured. In addition, the effects of time (30-300 min), Al concentration (0-370 mu M), and pH (4.0-6.5) on Al removal were investigated using the design-expert software. The efficiency of various biosorbents in Al removal was also evaluated in the optimal conditions of the final experiment. According to the results, Scenedesmus sp. was the most resistant microalgae and produced more biomass at 100 mu M. Moreover, the POX and CAT activities of Scenedesmus sp. were increased by the high Al concentrations. In optimum conditions (81.60 mu M Al, pH 5.8, 45 minutes), free cells (without modifications) were effective in Al biosorption (93.56%).

Microalgae show great potential to remove heavy metals from aqueous media. The present study aimed to prepare magnetized Chlorella vulgaris and Tetradesmus obliquus and consider their capability for facile removal of Pb(II) and Cd(II) from the aqueous media. The magnetic Fe 3 O 4 nanoparticles (17–26 nm) were first incorporated into the cells. Thereafter, the optimal conditions for bioaccumulation were determined as pH 5.5, initial biomass 1 g L −1 , and temperature 28 ºC. The accumulation kinetics of the ions with both magnetic microalgae were measured and well-fitted to the pseudo-second-order model (R 2 > 0.99) for the media supplemented with Cd 2+ (25–400 mg L −1 ) and Pb 2+ (25–200 mg L −1 ). The accumulation isotherms for both magnetic microalgae were fitted to the Langmuir model with the Cd 2+ and Pb 2+ maximum sorption capacities of 280.8 and 144.0 mg g −1 for C. vulgaris as well as 331.4 and 131.1 mg g −1 for S. obliquus, respectively. Magnetized microalgae are proposed as an efficient tool for the removal of metal ions from water.

Spirulina platensis is abundant biomass of cyanobacteria (blue-green algae) which is applied in the current study as a biosorbent. A statistical Box-Behnken approach was adopted to remove the toxic dye of alizarin red S (ARS) from synthetic solutions. A polynomial equation was developed to predict the dye removal efficiency and elucidate the interaction effects of variables. The maximum removal efficiency of ARS (69.1%) was obtained at pH 6.5, mixing time of 42.5 min, dye concentration of 100 mg. L-1 and S. platensis dose of 1.5 g. L-1. The findings indicated that the biosorption rate of ARS had a direct relationship with the ARS concentration, pH, reaction time, and S. platensis dose. The quadratic model suggested that the ARS concentration is the major variable in ARS removal. The isotherms and kinetics data could be suitably reflected by the Langmuir model and the pseudo-first-order equation. The maximum adsorption capacity of S. cerevisiae was obtained to be 17.15 mg. g(-1) based on the Langmuir model. The results showed that the removal rates of ARS from the first cycle up to the fourth cycle were varied from 55% to 20%, respectively. In conclusion, S. platensis shows suitable adsorptive characteristics and hence could be suggested as a viable option for future studies.

Spirulina platensis is one of the types of blue-green algae that was used as a biosorbent in this study. The aim of this study was to investigate the efficiency of S. platensis in removing MG from aqueous solutions and also to evaluate the biosorbent capacity using different kinetic models and isotherms. To obtain the optimum condition for MG biosorption using BBD, input factors included the initial level of MG 20–200 mg.L −1 ), dose of S. platensis (0.1–1.5 g.L −1 ), pH (4–9), and contaact time (5–80 min). The statistical method of BBD was considered to evaluate the removal rate of MG dye from aqueous solutions. The prediction of MG removal efficiencies and the evaluation of variable interactions were performed using a polynomial equation. The maximum removal efficiency of MG was obtained as 94.12% under MG level of 100.54 mg. L −1 , pH of 7.57, contact time of 52.43 min, and S. platensis dose of 0.98 g. L −1 . The removal MG efficiency enhanced with the increase in pH, reaction time, and S. platensis dose, and reduced with the decrease in MG level. The quadratic model suggested that the pH had a high impact on MG removal. The isotherms and kinetics data could be properly illustrated by the Freundlich model and the pseudo-second-order equation. Thermodynamic factors, including ΔG 0 , ΔH 0 , and ΔS 0 showed the adsorption of MG onto S. platensis was spontaneous and exothermic. The acquired findings also showed that the physisorption mechanism mainly govern the MG sorption process. As a result, S. platensis showed excellent adsorptive properties and hence could be offered as a viable option for eliminating MG from aqueous solutions.

Background and Objective: Phycocyanin is a blue pigment extracted from Spirulina platensis algae as an excellent alternative for the comparison of synthetic dyes in various industries, including food industries. The aim of the present study was to assess effects of copigmentation on the stability of phycocyanin pigments using spray drying method. Material and Methods: An aqueous solution of phycocyanin (500 mg l(-1)) was prepared at three pH values of 3, 5 and 7. Then, polyphenolic compounds containing rosmarinic acid, tannic acid and digallic acid (0, 75, 150, 225 and 300 mgl(-1)) were separately added to the solution as copolymers. Pigment solutions were transferred into cylindrical containers with similar sizes under a light source at an intensity of 7000 1 mm(2) and ambient temperature. Color changes of the solutions were assessed for 14 d. Phycocyanin pigment solution was copigmented with tannic acid (the best copolymer) and mixed with a combination of maltodextrin and Arabic gum (100:0, 75:25, 50:50, 25:75 and 0:100). Ratio of the core to the wall was 1:10. Spray dryer was used for drying and stability of the dried coated pigment powder was assessed for 14 d by investigating the absorption reduction ratio at the maximum absorption wavelength of phycocyanin (620 nm) using spectrophotometer. Results and Conclusion: Based on the results, using tannic acid (300 mgl(-1)) as the best copigmenting compound induced higher resistance to phycocyanin In addition, the most stable pigment treatment was seen with maltodextrin and Arabic gum coating (ratio: 100:0). In particle size, findings showed that the powder samples containing maltodextrin were larger than the samples with Arabic gum (350.2 and 40.1 nm, respectively). Moreover, results showed that phycocyanin copigmented with tannic acid included higher resistance to environmental changes and encapsulation using spray dryer was further effective in increasing stability of phycocyanin.

Phycocyanin is a pigment extracted from Spirulina platensis and can be a good alternative to synthetic dyes in various industries, including the food industry. The aim of this study was to stabilize phycocyanin and evaluate the method in pigment stability under different pH conditions. Phycocyanin (500 ppm) in solutions at three pH (3, 5, and 7) with different ratios (0, 75, 150, 225, and 300 ppm) of rosemarinic acid, tannic acid, digallic acid was mixed as a copolymer. These solutions were placed in cylindrical containers of the same size against a light source with an intensity of 7000 lux at ambient temperature. The color changes of the solutions were examined over 14 days. The structure of the microcapsules was examined using a scanning electron microscope. The average particle diameter size and zeta potential measurement of microcapsules were determined using a special particle measuring device. The results of pigment stability study showed that the use of tannic acid as a copigmenting compound has a higher resistance effect on phycocyanin and the concentration of 300 ppm has the highest resistance. The comparison of SEM showed that microcapsules containing maltodextrin were spherical with a smoother surface and had fewer wrinkles than those made with Arabic gum. The most stable pigment treatment is related to maltodextrin coating in the ratio of acid to pigment at pH=7 and the lowest pigment stability in the ratio of 0.4 times acid to pigment at pH=3. The particle size of microcapsules with different ratios in wall compositions varies between 159.2969 to 6006.637 nm. Also, the scattering index in the microcapsule varies between 0.299547 to 3.252826, which indicates the high dispersion of particles and the heterogeneity of particle size.

Immobilized microalgae are a promising approach to incorporate microalgae in recirculating aquaculture system (RAS) for water purification. In the present study, two types of biosorbents including sodium alginate–immobilized Scenedesmus spp. and Chlorella spp. beads (algal beads) and sodium alginate beads without microalgae (alginate beads) were prepared. In the first experiment (static test), the potential of two biosorbents to remove different concentrations of total ammonia nitrogen (TAN) and total phosphorus (TP) from water was investigated. In the second experiment, two prepared biosorbents were used as biofilter in a RAS for rearing African cichlid (Labidochromis lividus) for 30 days. The survival rate and growth indices of fingerling fish and removal efficiency of two biosorbents for TAN, NO3—N, and TP were determined. The results of static test showed that the removal efficiency and uptake capacity of the two biosorbents for TAN and TP increased during 30 days of the experiment, and these values for the algal beads were higher than the alginate beads. The TAN removal efficiency of the two biosorbents increased with increasing TAN concentration from 0.5 to 5 mg L−1. The application of algal beads in the RAS improved the survival rate, final weight, final length, weight gain, and daily growth index (DGI%) indices of fish compared to those cultured in the RAS containing the alginate beads and the control (P<0.05). The algal and alginate beads decreased the TAN concentration by 42.85% and 28.57% compared to the control after 30 days of cultivation period, respectively. The uptake of nitrate was not observed by the two biosorbents during cultivation period. The TP removal efficiency of algal beads reached 44.90% after 30 days. The findings of this study indicated that the sodium alginate–immobilized microalgae could be considered as a suitable biofilter to be incorporated into a RAS to improve water quality and consequently enhance the growth and health of fish.

Algae are an enormous biological group, forming 50% of photosynthetic organisms. In addition to having chlorophyll for the absorption of light photons, algae are rich in red, orange, and yellow carotenoids, which mainly protect cells against harmful radiation and free radicals. Moreover, these organisms have phycobiliproteins (red and blue pigments), which are involved in capturing and passing light energy to chlorophylls during photosynthesis and have a wide range of antioxidant properties. Algae also play a key role in substituting artificial colorants with natural colorants due to the adverse side-effects of chemical colorants, especially since natural colors are commonly used by individuals and various industries. Recently, algal pigments have been widely used in medical, nutraceutical, cosmeceutical, and pharmaceutical industries owing to their antioxidant, antidiabetic, anti-obesity, anti-inflammatory, antiaging, antimalarial, and neuroprotective properties. The growing demand for algal bioproducts highlights the importance of evaluating the trends influential factors in their production. The current review study provided an introduction to algal pigment classification, distribution, function, application, and biological production. In addition, we have discussed crucial biochemical pathways, enzymes, and gene/biotechnological modifications, such as transformation and expression regulation, which noticeably affect the metabolism of their sink and source.

Using bio-absorbents for treating industrial and domestic wastewater research have been recently increased. The dual application of microalgae for wastewater treatment and biomass production is a feasible way to reduce environmental problem. In this regard, the use of local microalgae in free and immobilized forms in native and diluted industrial wastewater was investigated. Immobilization was studied in alginate matrix, together with barium or calcium chloride cross link agents with other polymers and salts (chitosan, methyl cellulose, PVP, and CaCO3). Algae in both forms showed capability of absorption of nutrients and metal ions according to ICP and COD measurement. The results showed that using the immobilized form is superior due to the ease of harvest and possibility of alginate in metal ions' chelation in a short time in comparison with free form.

Aluminium (Al) water pollution is an increasing environmental problem and comprehensive analysis of toxic responses of aquatic primary producer organisms is imperative. We characterized the antioxidant response of Scenedesmus sp. microalga to Al-induced oxidative stress. After 72 h of exposure to Al (0, 10, and 100 mu M) in a modified Bold Basal Medium (pH 5.0), we observed cell aggregation and alterations in the subcellular structure, strong lipid peroxidation and oxidative stress induction (detected with the fluorescent probe 2',7'-dichlorodihydrofluorescein diacetate) in parallel with Al accumulation in cells. At the same time, Al toxicity caused depletion of important macronutrients like Ca, which is important for cell-wall structure. Analysis of antioxidant enzymatic activities in Al-treated Scenedesmus cells revealed that catalase, ascorbate peroxidase, as well as different isoforms of superoxide dismutase were inhibited especially at the highest Al dose (100 mu M), cells that accumulated the highest concentration of Al. On the other hand, glutathione reductase activity increased at that Al concentration. Immunodetection after Western-blotting confirmed that only ascorbate peroxidase inhibition was apparently due to a decrease in enzyme levels. However, the inhibition of catalase and activation of glutathione reductase activities seemed related with post-translational modifications in protein function as protein expression decreased or increased, respectively under Al stress. Our results may help to understand toxic mechanisms triggered by Al in freshwater microalgae, which in turn could aid to select suitable biomarkers of Al contamination in aquatic ecosystems.

In the present study, the optimization of immobilization structures along with Scenedesmus sp. and the determination of heavy metals (Ni, Cr) absorption rate have been investigated. Polymers in combination with salts were performed in alginate in order to study the stability of formed structures in cross linking agents. Beads with stable structure in synthesized heavy metal solution inoculated and the adsorption percentage has been recorded. Results showed that the most stable beads were formed in 2 and 3% alginate along with CaCO3 application beside BaCl2 as solidified solution. Reduction of heavy metal in these structures had the most percentage and it was observed that if the incubation time of beads in solidified solution decreased, the percentage of heavy metal reduction would increase to 86%. Although alginate beads showed the highest absorption rate of heavy metal, the presence of S. sp. in all treatments occasionally increased heavy metal absorption up to 15%.

The Cyanobacteria Spirulina is an attractivetarget for its pigments, proteins, vitaminsand other high-value cell components. Also, itcan be easily and cheaply harvested by filtrationfrom the cultivation medium. In this studya simple protocol was developed for Spirulinaproduction by using different types of nitrogenin ammonium (Urea and (NH4)2SO4) andnitrate (KNO3, NaNO3) forms in combinationwith NPK fertilizer. Results demonstratedhigh amount of nitrogen in both forms inhibitedSpirulina growth. Ammonium showed astronger inhibitory role than nitrate in biomassproduction while increased phycocyanin content.Best phycocyanin content occurred inhigh ammonium or low nitrate concentration.In media based on 1% Urmia lake salt and 1g/LNPK, a combination of low concentration (0.1-0.5g/L) of Urea and (NH4)2SO4 obtained bestresults in biomass production. 1.2g/L biomassduring 14 days without any carbon source canbe compared with Zarrouk/2 medium. Thiscomposition can be used economically forSpirulina production since little amount ofcheap material make the possibility of Spirulinaproduction.

Recently, biological methods are used for remediation of various pollutants especially heavy metals. Algae are organisms which can accumulate and transform these pollutants with different mechanisms. In this regard immobilization of these microorganisms is a technique that is used for different purpose. So after primary screening of microalgae (Spirulina, Tetraselmis, Chlorella, Scenedesmus, Microchaete and Calothrix), selected microalgae treated with chrome in a domain of environmental factors [pHs (2-5), concentration (10-150 mg/L) and time (20-200 min)] and absorption of chrome was determined with atomic absorption. The condition of maximum absorption was selected for evaluation of the effect of immobilization on it. Also physiological responses of selected microalga in these treatments were determined. The results indicated that maximum of absorption was 16% in 110 minutes by free green alga Scenedesmus. The alga Scenedesmus cannot accumulate chrome by itself and absorbed chrome returned to medium. Also the potential of alga reduced with increasing concentration and the maximum rate of absorption was seen in lower concentrations. Higher Absorption was seen in higher pHs (pH 5). Also immobilization had positive effect on absorption of chrome and can use in other purposes.

30Nov 2016 Indirect regeneration from cotyledonary explants of watermelon (Citrullus lanatus) at in vitro culture Maryam Ameri , Mehrdad Lahouti , Abdolreza Bagheri , Ahmad Sharifi and Fatemeh Keykha. Biology Department, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran. Industrial Microorganism Biotechnology Department, Iranian Academic Center for Education, Culture and Research, Branch of Mashhad, Mashhad, Iran. Biotechnology and Plant Breeding Department, College of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran. Ornamental Plant Biotechnology Department, Iranian Academic Center for Education, Culture and Research, Branch of Mashhad, Mashhad, Iran. Biotechnology Department, College of Agriculture, Jahrom University, Jahrom, Iran.

Various parts of a seed have different responses to same condition, because of dissimilar hormone concentration and enzyme activity. Indirect regeneration of watermelon seed was tested with different parts: hypocotyl, basal, central, distal and peripheral zone (parts 1, 2, 3, 4 and 5, respectively). The different parts were cultured in MS medium containing 3.5 mg/l BA and 0.5 mg/l IAA. Photoperiod (16h light/8h dark) or dark condition were used as light treatment. Every 2 weeks the callogenesis and regeneration percentages and number of regenerated leaves were assessed until 6 weeks. Best callogenesis and regeneration percent observed in dark and light condition, respectively. A regular pattern of regeneration find in seed segments. The rate of regeneration was faster for second and third part of seed in compare to fourth and fifth parts (p<0.01). The peripheral parts show low density of regenerated plantlets. Regenerated branches were rooted in MS medium containing 0.1 mg/l IBA, and obtained plantlets with appropriate root system, were cultivated in hydroponic and sand pots to acclimatize. The best acclimatization (90 %) were gained in hydroponic culture

Abstract not availablePlant Tissue Cult. & Biotech. 24(2): 279-285, 2014 (December)