Search

Of the total carotenoids in respective algal samples, β-carotene in Spirulina platensiswas 69.5%, astaxanthin and its esters in Haematococcus pluvialiswas 81.38%, and lutein in Botryococcus brauniiwas 74.6%. The carotenoids were characterized by mass spectrometry. A time−course study of carotenoids in rats after administration of microalgal biomass showed peak levels in plasma, liver, and eyes at 2, 4, and 6 h, respectively. β-Carotene accumulation in Spirulina-fed rats was maximum in eye tissues at 6 h. Similarly, levels of astaxanthin and lutein in Haematococcus- and Botryococcus-fed rats were also maximal in eye tissues. Astaxanthin from H. pluvialisshowed better bioavailability than β-carotene and lutein. The antioxidant enzymes, catalase, superoxide dismutase, peroxidase, and TBARS were significantly high in plasma at 2 h and in liver at 4 h, evidently offering protection from free radicals. This study implies that microalgae can be a good source of carotenoids of high bioavailability and nutraceutical value.

•Indigenous automation system for microalgae cultivation developed.•Equipped with CO2fed pH control and membrane sparger.•Temperature, pH, DO, Light can be recorded automatically.•Pilot scale Spirulina cultivation using automated CO2fed pH control.•Maximum biomass, protein and C-Phycocyanin was obtained at pH 8.5.

The effects of light intensity, inoculum volume, sodium nitrate and carbon dioxide concentrations on the growth of Haematococcus pluvialiswere investigated using response surface methodology (RSM). All the four variables exhibited significant effects on growth and can be related (r≥ 0.926, P≤ 0.01) by a second-order polynomial consisting of linear, quadratic and interaction terms. The total quadratic effect (P≤ 0.01) dominates over the total linear effect (P≤ 0.01) but the role of interaction terms (P≤ 0.10) is marginal. The optimum values of these variables were: carbon dioxide 1.54%, sodium nitrate 1.06 g/l, inoculum volume 24.97% and light intensity 2.42 klux; the predicted maximum value for the yield of biomass was 0.51 g/l (dry weight).

A culture method was developed for photoautotrophic culture of Haematococcus pluvialis, Chlorella vulgaris, Scenedesmus obliquus, Spirulina platensis, Nostocand Stigonema in a two-tier flask consisting of nutrient media in the upper chamber and CO2generating buffer mixture (KHCO3/K2CO3) in the lower chamber. The concentration of buffer mixture was varied to obtain desired levels of CO2. CO2at 2.0% (v/v) level enhanced growth and chlorophyll content over control cultures (without CO2supplementation) in all microalgal species. Haematococcus pluvialisculture in BBM and KM1 media showed 6.71- and 2.07-fold increase in biomass yields with astaxanthin productivity at 7.26 and 7.48 mg l−1level respectively. CO2supplementation to C. vulgarisand S. obliquuscultures resulted in 5.97- and 7.30-folds increase in biomass with 2–3 fold increase in chlorophyll and carotenoid contents over their respective controls. Similarly 2–3 fold increase in chlorophyll and carotenoid contents were observed in Sp. platensis, Nostocand Stigonemaspp. This culture methodology will provide information on CO2requirement for growth of algae and metabolite production and also facilitates studies on the influence of light and temperature conditions.

Cultures of Haematococcus pluvialiswere exposed to mutagens like u.v. and EMS (ethyl methanesulphonate). The results showed that the survival rate decreased with the increase in u.v. exposure time and increase in EMS concentration. These mutants were further screened using inhibitors of the carotenoid biosynthetic pathway viz. diphenylamine (15–90 μM), nicotine (160–320 μM) and compactin (1.5–3.0 μM). The mutants thus obtained showed early enhanced (2.2–3.2-fold) astaxanthin accumulation and also exhibited higher lycopene cyclase activity.

A lipase secreted by the anaerobePropionibacterium acidipropioniciwas 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 Ni2+, Ba2+, Mg2+, Cu2+, ethylenediaminetetraacetic acid, iodoacetamide, N-acetylimidazole and nonidet P-40 but stimulated by Ca2+, Co2+, K+, Fe2+, sodium dodecyl sulfate and N-bromosuccinamide. The enzyme showed substrate inhibition for both tributyrin andp-nitrophenyl acetate.

Callus cultures ofCapsicum frutescenscapable of producing a maximum of 53 μg capsaicin/g FW were exposed to various levels of p-fluorophenyialanine (PFP) at 100, 400, 1000 and 2000 μM to develop a resistant cell line that over produces capsaicin. After 15 days of culturing on media lacking PFP, cell lines resistant to 100, 400 and 1000 μM registered 18%, 34.5% and 45% increase in capsaicin content over normal cell line (cells not exposed to PFP). Capsaicin accumulation was inhibited in 2000 μM PFP resistant cell line. The profile of phenylalanine ammonia lyase (PAL), the key enzyme in pheny1propanoid pathway in resistant cell cultures was studied and compared with normal cell cultures to understand its role in capsaicin formation. Importantly increased production of capsaicin was obtained using PFP resistant cell lines. The activity profile of PAL had no correlation with capsaicin content in both control and PFP resistant cells.

Phycocyanin, a blue colorant from the cyanobacterium (blue green alga) Spirulina platensis was evaluated for its safety as a natural food colour by toxicity evaluation studies in albino rats. Acute and subchronic studies on phycocyanin were conducted on both sexes of albino rats. Phycocyanin at high concentrations- 0.25 to 5.0 g/kg body weight (w/w) did not induce any symptoms of toxicity nor mortality of the animals. Feeding of low concentrations of phycocyanin at 0.5 to 4.0 g/kg in the diet for 14 weeks did not affect food intake or body weight gain of phycocyanin-fed rats compared to control animals. Terminal values on absolute and relative weights of vital organs, hematology and serum enzymes did not reveal any differences between phycocyanin-fed and control groups. Histological examination of vital organs did not show any remarkable differences between treated and control groups. Overall, consumption of phycocyanin, a natural colorant from Spirulina platensis did not result in adverse effects in experimental animals.

Abstract: A lipase secreted by the anaerobePropionibacterium 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 Ni2+, Ba2+, Mg2+, Cu2+, ethylenediaminetetraacetic acid, iodoacetamide, N-acetylimidazole and nonidet P-40 but stimulated by Ca2+, Co2+, K+, Fe2+, sodium dodecyl sulfate and N-bromosuccinamide. The enzyme showed substrate inhibition for both tributyrin andp-nitrophenyl acetate.

Abstract:   Elicitors of both fungal and bacterial origin that is, polysaccharides, proteins and fatty acids, are widely used for enhancement of secondary metabolites in plant cell cultures. In the present study, phycocyanin – a natural blue pigment that is the major light-harvesting biliprotein in the blue-green alga Spirulina platensis– was used as an elicitor to enhance the accumulation of capsaicin and anthocyanin in Capsicum frutescens and Daucus carota cell cultures respectively. Phycocyanin at 0.3, 0.6 and 1.2 mg% in capsicum cell cultures elicited a more than two-fold increase in capsaicin content with maximum productivity of 192 μg/g fresh weight. Similarly in Daucus carota cell cultures a two-fold increase in anthocyanin content was obtained at 0.3 mg% with a maximum productivity of 24.8 mg% on a dry-weight basis. In both the systems, phycocyanin showed an early elicitation of secondary metabolites.