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The sources of bioavailable vitamin B12 are limited, and most of them are animal-derived. Chlorella vulgaris, a freshwater microalga, is known for immune system boosting, nutraceutical properties and presence of a natural form of vitamin B12. The present study focused on the in vivo evaluation of the Chlorella biomass as a source of bioavailable vitamin B12 to alleviate the vitamin B12 deficiency status of Wistar rats. Experimental animals were evaluated for the vitamin B12 deficiency-related circulatory marker (serum vitamin B12) and functional markers (plasma homocysteine and urinary methylmalonic acid), haematological and histological changes. The results showed that an increase of 2.4-fold in urinary methylmalonic acid (13.01 ± 0.89 µmoles moles of creatinine−1), 2.6-fold in plasma homocysteine (17.18 ± 3.57 µmole L−1), and 48% decrease in serum vitamin B12 levels (252.69 ± 1.46 pg mL−1) in vitamin B12 deficient group compared to control animals. The Chlorella biomass supplementation in the diet led to the restoration of the functional and circulatory markers, hematological parameters, and vitamin B12 content of kidney and liver to control levels. The Chlorella biomass supplementation increased the erythrocyte precursors and MAST cells in the bone marrow and also normalized the histological features of kidney, liver, and lung tissues. The results suggest that the vitamin B12 from the Chlorella biomass was bioavailable and facilitated the improvement of vitamin B12 status in deficient rats. [ABSTRACT FROM AUTHOR]

Abstract: A comparative life cycle assessment of CO2 capture potential of microalgae, Scenedesmus dimorphus, during autotrophic cultivation in closed airlift photobioreactor and open raceway pond under Indian conditions has been carried out. The LCA inventory inputs for the both the systems were entirely based on primary experimental data obtained by algal cultivation in 1000-L pilot-scale raceway pond and 5-L airlift photobioreactor, respectively. The primary energy demand, environmental impacts and Net CO2 capture efficiency of both the systems were evaluated. The results indicated that the primary energy demand and GWP of airlift photobioreactor were 3.7-fold higher than raceway pond. The NERCO2 (defined as net emission ratio of CO2 and estimated as ratio of CO2 sequestered/CO2 emitted) of raceway pond was fourfold higher as compared to airlift photobioreactor; however, both the cultivation systems were observed to be net negative in terms of CO2 sequestration. However, the process can become net CO2 positive, with up to fourfold and 7.5-fold enhancement in biomass productivities (wrt base value) for raceway pond and airlift photobioreactor, respectively. Further, LCA predictions indicated that utilization of energy-efficient motors with lower specific energy consumptions for microalgae cultivation would facilitate algal cultivation systems to achieve net CO2-positive sequestration. [ABSTRACT FROM AUTHOR]

Dunaliella salina is a halotolerant marine microalga, known for the accumulation of β-carotene. The BCH-type β-carotene hydroxylase plays a major role in the conversion of β-carotene to xanthophylls. The β-carotene hydroxylase from the chlorophycean microalga, Chlamydomonas reinhardtii was amplified, and the sequence alignment analysis showed that the amplified gene belongs to the group of BCH-type hydroxylases. The amplified β-carotene hydroxylase gene with rubisco promoter and chloroplast transit peptide was introduced into the genome of the D. salina by Agrobacterium -mediated genetic transformation. The carotenoid analysis showed a 3-fold increase of violaxanthin at growth stage and a 2-fold increase of zeaxanthin under stress conditions in transformed D. salina . [ABSTRACT FROM AUTHOR]

Defatted microalgal biomass (DAB) of a local Scenedesmus dimorphus strain was characterised as animal feed in an experimental Wistar rat model. The DAB contained 21.5 % protein, 28 % dietary fibre and 21 % ash on dry basis. The DAB was rich in calcium (1208 mg 100 g biomass) followed by magnesium (400.6 mg 100 g) among the tested mineral elements. The essential amino acids (EAA) constituted 48 % ( w/ w) of proteins, and the EAA index was similar to casein and soybean. The protein was limiting in sulphur-containing amino acids cysteine and methionine. The algal biomass showed 5-6-fold higher water absorption capacity (3.44 ± 0.06 g g biomass) compared with basal diet (0.67 ± 0.06 g g biomass). The DAB was found to be safe in both short-term (14 days), single-dose feeding (20 % ( w/ w) feed) and long-term (90 days) repeated-dose feeding (at 5 and 10 % ( w/ w) feed). In the short-term feeding trial, faecal output and water intake increased by 2-fold during the initial 4 days, mainly attributed to higher ash and fibre content of biomass. The long-term repeated-dose feeding of DAB did not induce any physiological changes in rats such as feed intake, haematology profile, serum biochemical parameters, histopathology and relative organ weight. The feed conversion ratio and quotient of protein efficiency ratio in DAB-fed groups were similar to control. However, animals required a longer adaptation period to DAB-mixed feed, as indicated by slower body weight gain and feed intake. The study suggests that DAB can be used as animal feed up to 10 % ( w/ w) replacement levels. [ABSTRACT FROM AUTHOR]

The butanol extract of S pirulina was found to have potent α-glucosidase inhibitory activity with an IC50 value of 23.0 ± 0.4 μg/mL. Total phenolic and flavonoid contents were estimated to be 121.0 ± 3.5 mg gallic acid equivalent/100 g and 27.4 ± 1.2 mg rutin equivalent/100 g of S pirulina biomass. The butanol extract also exhibited rat intestinal α-glucosidase inhibitory activity with IC50 value of 37.5 ± 2.8 μg/mL. The butanol extract had showed antioxidant activities with DPPH (1, 1-diphenyl-1-picrylhydrazyl radical), reducing power, hydroxyl radical and nitric oxide scavenging activity and showed antimicrobial activity against gram-positive and gram-negative bacteria. The present results indicate that S pirulina can be used for nutraceutical applications. Practical Application S pirulina has Generally Recognized as Safe ( GRAS) status and FDA approval for dietary supplement; therefore, it can be used as food supplement for health benefits. The therapeutic approach for preventing diabetes mellitus is to retard the absorption of glucose through inhibition of α-glucosidase. [ABSTRACT FROM AUTHOR]

Indigenous freshwater microalgae from natural habitats may have potential for bio-mitigation of atmospheric CO 2 . The present study evaluates the response of three indigenous microalgal isolates viz., Desmodesmus sp., Kirchneriella sp. and Acutodesmus sp., to CO 2 rich environment (10, 20 and 30%) in a closed photobioreactor. In a time course study, levels of CO 2 in culture medium were observed to modulate the activity of carbonic anhydrase (CA), a key enzyme of carbon concentrating mechanism (CCM) of microalgae. The CA activity decreased on availability of free CO 2 and increased on depletion of free CO 2 in the culture medium. Maintenance of algal cultures in CO 2 rich environment for a period of 16 days enhanced the biomass concentration, specific growth rate, chlorophyll and carbon dioxide biofixation rate by 2–4 fold. Overall productivity, carbon, carotenoid and lipid contents also increased. Palmitic and oleic acids were the major fatty acids of the algal lipids. CO 2 rich environment affected the fatty acid profile in Desmodesmus sp. with an increase in unsaturated fatty acids. [ABSTRACT FROM AUTHOR]

Though the potential of micro algal biotechnology for business or industry is widely acknowledged for long, the potential did not get translated much into the benefits for the society. The article discusses the approaches that can be adopted by the universities in making algal technologies reach out to the society. It argues the urgent need to review and assess on what need to be done to deliver the promise that algal biotechnology has for the society. The article identifies four major challenges to universities in making algal technology work in today's knowledge society and knowledge economy. These four challenges are bio-business and knowledge transfer, knowledge and technology integration, human resources development and capacity building, and expanding boundaries of scholarship. There is a need to evolve some innovative and new approaches for addressing these challenges. Many institutes and universities of high repute are modifying their system by introducing certain innovations to avoid compartmentalisation of knowledge or/and different systems of education. Three routes to planning careers in algal biotechnology are identified - developing specialist educationists and researchers in various branches related to algal biotechnology; careers in algal biotechnology to cater to the needs of the industry; and careers in algal biotechnology to cater to the needs of society. It is argued that developing a new 'anatomy' which can serve both basic science and business may be one of the keys for algal technologies to reach out to the society. [ABSTRACT FROM AUTHOR]

The first successful Agrobacterium-mediated transformation of the green alga Haematococcus pluvialis Flot. using the binary vectors hosting the genes coding for GUS (β-glucuronidase), GFP (green fluorescent protein), and hpt (hygromycin phosphotransferase) is reported here. Colonies resistant to hygromycin at 10 mg · L−1 expressed β-glucuronidase. The greenish yellow fluorescence of GFP was observed when the hygromycin-resistant cells were viewed with a fluorescent microscope. PCR was used to successfully amplify fragments of the hpt (407 bp) and GUS (515 bp) genes from transformed cells, while Southern blots indicated the integration of the hygromycin gene into the genome of H. pluvialis. SEM indicated that the cell wall of H. pluvialis was altered on infection with Agrobacterium. The transformation achieved here by Agrobacterium does not need treatment with acetosyringone or the wounding of cells. A robust transformation method for this alga would pave the way for manipulation of many important pathways relevant to the food, pharmaceutical, and nutraceutical industries. [ABSTRACT FROM AUTHOR]

An economically feasible and sustainable microalgal biorefinery needs to develop culture strategies to maximize biomass productivity and accumulate important metabolites in select microalgae. The present study evaluated the effect of indole-3-acetic acid (IAA) and diethyl amino ethyl hexanoate (DAH) on two marine microalgae of commercial importance, viz., Porphyridium purpureum and Dunaliella salina. The photosynthetic efficiency, biomass productivity, and accumulation of PUFA rich lipids in P. purpureum and D. salina were studied. The microalgal cultures supplemented with both the phytohormones at lower concentrations (10-7 to 10-8M) showed an enhanced biomass production (2 to 3.5 fold increase), lipid content (up to 1.4 fold increase), and PUFA content (1 to 2 fold enhancement) at p < 0.001, compared to control cultures. The maximum photosynthetic efficiency (Fv/Fm) of IAA and DAH supplemented microalgal cultures increased up to 2.2 fold with up to a two-fold reduction in the average antenna size (ABS/RC) and dissipation energy (DI0/RC). The study suggests that supplementing the P. purpureum and D. salina cultures with phytohormone could effectively enhance the biomass production and accumulation of PUFA rich lipids. [Display omitted] • Phytohormones enhanced the biomass production by 2–3.5 fold. • Phytohormones increased the maximum photosynthetic activity by 2.2 fold. • Lipid content of phytohormone supplemented cultures increased upto 1.4 fold. • Phytohormones led to 1.6–2 fold increase in PUFA content of biomass. [ABSTRACT FROM AUTHOR]

The effect of sodium acetate, sodium chloride and Haematococcus pluvialis culture age on biomass yield, astaxanthin content and astaxanthin production was investigated using response surface methodology in a batch mode of cultivation. An orthogonal experimental design, with three variables (at five coded levels of -1.682, -1, 0, 1 and 1.682) and three response functions, was employed to study the effect of the individual variable on the response functions. The response functions correlated well (r≥0.98, p≤0.01) with these variables by second order polynomials consisting of linear, quadratic and interaction terms. The effect of culture age dominated over the sodium acetate and sodium chloride concentrations. Optimum conditions for achieving high astaxanthin content (>1.4%w/w) and astaxanthin production (13 mg/L) were found to be with 31–50 mM sodium acetate and 0.55–0.63% (w/v) of sodium chloride. [ABSTRACT FROM AUTHOR]

A lipase secreted by the anaerobe Propionibacterium acidipropionici was purified 52-fold with 27% recovery by employing a three-step purification protocol. The enzyme has a small molecular mass (Mr = 6000-8000) as determined by gel filtration and ultracentrifugation. It hydrolyzed palm oil, coconut oil, castor oil, olive oil, groundnut oil and tributyrin. Enzyme activity was inhibited by Ni, Ba, Mg, Cu, ethylenediaminetetraacetic acid, iodoacetamide, N-acetylimidazole and nonidet P-40 but stimulated by Ca, Co, K, Fe, sodium dodecyl sulfate and N-bromosuccinamide. The enzyme showed substrate inhibition for both tributyrin and p-nitrophenyl acetate. [ABSTRACT FROM AUTHOR]