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Temperature is the most critical factor that directly affects the physiological functioning and metabolic activities of any organism. With rising global temperature, understanding the heat stress response of an organism is critically important. In the present study, we investigated differences in the early changes occurring upon heat stress in the green microalga Acutodesmus dimorphus, a potential strain for biofuel production. The cells were heat‐stressed at 45 and 50°C for 24 h and the temporal response of cells in terms of growth, pigments content, levels of oxidative stress biomarkers i.e., reactive oxygen species (ROS) and the response of enzymatic and non‐enzymatic antioxidant scavengers were evaluated. The results revealed that after 24 h of heat stress at 45°C, the accumulations of chlorophyll a and carotenoids remained stable; all three ROS increased with the higher activities of various enzymatic and non‐enzymatic antioxidants. On the contrary, at a higher temperature of 50°C, the accumulations of chlorophyll a, carotenoids and non‐enzymatic antioxidants reduced drastically while the accumulations of all three ROS and the response of enzymatic antioxidants were significantly higher than those at 45°C. These results suggest that the cells utilize several stress acclimatization mechanisms to cope up the heat stress. There was a dramatic difference in the physiological changes and cellular antioxidant mechanism upon heat stress at 45 and 50°C. The cellular defense response of A. dimorphus gets impaired after heat stress at 50°C but remains active at 45°C, exhibiting the heat resistance and, thus, the thermotolerance. [ABSTRACT FROM AUTHOR]

There are more than 600 different carotenoids which perform a range of functions in various organisms including microalgae. In the present study, chemosystematics approach was followed to segregate 57 microalgal strains based on their carotenoid composition using principal component analysis (PCA) and hierarchical clustering. The present findings suggest that lutein and violaxanthin can be effective chemotaxonomic markers for Chlorophyta members with an average content of 1.26 mg g − 1 and 0.14 mg g − 1 dry cell weight (DCW), respectively. Similarly, myxoxanthophyll and echinenone can be used as markers for Cyanophyta members with average contents of 0.23 mg g − 1 and 0.32 mg g − 1 DCW, respectively. The total carotenoid content ranged from 0.23 to 7.2 mg g − 1 DCW. Our method combining PCA and artificial hierarchical clustering has been proposed as an alternative method for identification of carotenoids as biomarkers for classifying unknown microalgal strains based on their pigment profiles. [ABSTRACT FROM AUTHOR]

Microalgae are the potential third generation energy feedstock with environmental benefits. In order to reduce the overall cost of production, a saline tolerant isolate CSIR-CSMCRI's Chlorella variabilis (ATCC PTA 12198) was grown in open solar salt pans using sea water during the summer season at a temperature of 45 ± 3 °C. In the present case with an ability to proliferate in hypersaline environment (3–8 °Be′), C. variabilis was cultivated in a vast area of 772 m 2 with a total cultivation volume of 360 m 3 with an average biomass productivity of 34.59 g/m 2 /d. The cultivated C. variabilis was harvested by auto-settling and had an average calorific value of 3885 kCal/kg. The lipid extraction using Chloroform:Methanol (1:2) yielded a total lipid content of 22.59% (w/w) with a calorific value of 9288 kCal/kg. The total lipid extract in hexane yielded 10.58% (w/w) of lipid. The fatty acid methyl ester (FAME) profile of hexane extracted lipid of C. variabilis showed its suitability for biodiesel production. Application of solar energy in energy intensive extraction process improved the energy output to input ratio minimizing the energy input of 33.12 MJ/kg biomass without affecting its lipid profile. Furthermore, an unmodified diesel motor vehicle was run successfully using the neat biodiesel. The entire process is cost effective and energy efficient leading to the sustainable development of microalgae-based biofuel for future commercialization. [ABSTRACT FROM AUTHOR]

High volumes of lipid extracted microalgal biomass residues (LMBRs) are expected to be produced upon commencement of biodiesel production on a large scale, thus necessitating its value addition for sustainable development. LMBRs of Chlorella variabilis and Lyngbya majuscula were employed to substitute the nitrogen content of recommended rate of fertilizer (RRF) for Zea mays L. The pot experiment comprised of 10 treatments, i.e., T1 (No fertilizer); T2 (RRF-120 N: 60 P2O5: 40 K2O kg ha-1); T3 to T6--100, 75, 50, and 25% N through LMBR of the Chlorella sp., respectively; T7 to T10--100, 75, 50, and 25% N through LMBR of Lyngbya sp., respectively. It was found that all LMBR substitution treatments were at par to RRF with respect to grain yield production. T10 gave the highest grain yield (65.16 g plant-1), which was closely followed by that (63.48 g plant-1) under T5. T10 also recorded the highest phosphorus and potassium contents in grains. T4 was markedly superior over control in terms of dry matter accumulation (DMA) as well as carbohydrate content, which was ascribed to higher pigment content and photosynthetic activity in leaves. Even though considerably lower DMA was obtained in Lyngbya treatments, which might have been due to the presence of some toxic factors, no reduction in grain yield was apparent. The length of the tassel was significantly higher in either of the LMBRs at any substitution rates over RRF, except T6 and T7. The ascorbate peroxidase activity decreased with decreasing dose of Chlorella LMBR, while all the Lyngbya LMBR treatments recorded lower activity, which were at par with each other. Among the Chlorella treatments, only T5 recorded significantly higher values of glutathione reductase activity over RRF, while the rest were at par. There were significant increases in carbohydrate and crude fat, respectively, only in T4 and T3 over RRF, while no change was observed in crude protein due to LMBR treatments. Apparently, there was no detrimental effect on soil properties, suggesting that both the LMBRs can be employed to reduce the usage of chemical fertilizers, thus promoting maize crop production in a sustainable manner. [ABSTRACT FROM AUTHOR]

Phycobiliprotein-containing water and carotenoid-containing methanolic extracts of three different cyanobacteria, Pseudanabaena sp., Spirulina sp. and Lyngbya sp., were studied for their DPPH scavenging, iso-bolographic studies, and anti-nephrolithe activities. The best EC50 values for DPPH scavenging were in Lyngbya water (LW, 18.78 ± 1.57 mg·mg-1 DPPH) and Lyngbya methanol (LM, 59.56 ± 37.38 mg·mg-1 DPPH) extracts. Iso-bolographic analysis revealed most of the combinations of extracts were antagonistic to each other, although LM--Spirulina methanol (SM) 1:1 had the highest synergistic rate of 86.65%. In vitro digestion studies showed that DPPH scavenging activity was considerably decreased in all extracts except for Pseudanabaena methanol (PM) and LM after the simulated digestion. All of the extracts were effective in reducing the calcium oxalate crystal size by nearly 60%-65% compared to negative control, while PM and Spirulina water (SW) extracts could inhibit both nucleation and aggregation of calcium oxalate by nearly 60%-80%. [ABSTRACT FROM AUTHOR]

The main objective of the present study is to effectively utilize the de-oiled algal biomass (DAB) to minimize the waste streams from algal biofuel by using it as an adsorbent. Methylene blue (MB) was used as a sorbate for evaluating the potential of DAB as a biosorbent. The DAB was characterized by SEM, FTIR, pHPZC, particle size, pore volume and pore diameter to understand the biosorption mechanism. The equilibrium studies were carried out by variation in different parameters, i.e., pH (2–9), temperature (293.16–323.16 K), biosorbent dosage (1–10 g L−1), contact time (0–1,440 min), agitation speed (0–150 rpm) and dye concentration (25–2,500 mg L−1). MB removal was greater than 90% in both acidic and basic pH. The optimum result of MB removal was found at 5–7 g L−1 DAB concentration. DAB removes 86% dye in 5 minutes under static conditions and nearly 100% in 24 hours when agitated at 150 rpm. The highest adsorption capacity was found 139.11 mg g−1 at 2,000 mg L−1 initial MB concentration. The process attained equilibrium in 24 hours. It is an endothermic process whose spontaneity increases with temperature. MB biosorption by DAB follows pseudo-second order kinetics. Artificial neural network (ANN) model also validates the experimental dye removal efficiency (R2 = 0.97) corresponding with theoretically predicted values. Sensitivity analysis suggests that temperature and agitation speed affect the process most with 23.62% and 21.08% influence on MB biosorption, respectively. Dye adsorption capacity of DAB in fixed bed column was 107.57 mg g−1 in preliminary study while it went up to 139.11 mg g−1 in batch studies. The probable mechanism for biosorption in this study is chemisorptions via surface active charges in the initial phase followed by physical sorption by occupying pores of DAB. [ABSTRACT FROM AUTHOR]

Abstract: The isolated cyanobacterium containing biopigments like chlorophyll-a, phycoerythrin, phycocyanin, and carotenoid was cultured under different quality of light modes to ascertain biomass and pigment productivity. On the basis of 16S rRNA gene sequence, the isolate was identified as Pseudanabaena sp. Maximum biomass concentration obtained in white-, blue-, and green-light was 0.82, 0.94, and 0.89g/L, respectively. It was observed that maximum phycoerythrin production was in green light (39.2mg/L), ensued by blue light (32.2mg/L), while phycocyanin production was maximum in red light (10.9mg/L). In yellow light, pigment production as well as the growth rate gradually declined after 12days. Carotenoid production decreased in blue-, white-, and red-light after 15days, while in green light it had increased gradually. The present communication suggests that Pseudanabaena sp. can be used for commercial production of phycoerythrin when grown under green light. [Copyright &y& Elsevier]

We announce here the draft genome sequence of Halomonas hydrothermalis MTCC 5445, a halophilic bacterium of the class Gammaproteobacteria. It was isolated from the sea coast of Aadri, Veraval, Gujarat, India. Its genome contains genes for polyhydroxybutyrate (PHB), a biodegradable polymer that can be used as a substitute for petroleum plastics., (Copyright © 2015 Bharadwaj SV et al.)