Showing papers by "Ruma Pal published in 2015"

Microalgae in Aquaculture: A Review with Special References to Nutritional Value and Fish Dietetics

Abstract: Microalgal biotechnology has gained considerable importance in recent decades and its use is extending day by day into several areas like nutraceutical research, renewable energy source, production of essential biomolecules like β-carotene, astaxanthin, PUFA, bio colorant production, wastewater treatment, bioremediation and aquaculture etc. Among all these, microalgae as a source of nutrition have drawn the attention since long back and are widely used in animal nutrition. Fishmeal is the preferred protein ingredient of feed in aquaculture industry, contributing significantly to the variable production cost. However, decreasing fishmeal supply and increasing costs threaten the sustainability and growth of the aquaculture industry. Therefore, complete or partial substitution of fishmeal with alternative proteins is needed to solve the problem. Presently, microalgae are used worldwide as an alternate protein source replacing fishmeal successfully. In feeding trials with fish, many types of microalgae have been found to be used for increasing growth (protein accretion), feed utilization, physiological activity, stress response, starvation tolerance, disease resistance, and carcass quality. In the present communication an attempt has been taken to review the application of different microalgae in rearing of aquaculture animal especially the fishes.

Biosynthesis of monodisperse gold nanoparticles by green alga Rhizoclonium and associated biochemical changes

Abstract: In search for a suitable algal bioreagent for monodisperse (homogenous mixture of same size and shape) gold nanoparticle production, a eukaryotic green alga Rhizoclonium fontinale was found to produce spherical (~16 nm size) nanoparticles, when exposed to 15 mg L−1 auric chloride solution at pH 9 for 72 h. In this connection, the effects of different concentrations of gold ions, amount of biomass, and pH of the exposure medium on nanoparticle synthesis were evaluated. Upregulation of stress-related compounds like, carotenoids and stress enzymes—catalase, ascorbate peroxidase, and super oxide dismutase of gold-exposed biomass, were recorded up to 24 h at the onset of gold nanoparticles synthesis, afterwards enzyme activity ceased but the nanoparticle production continued up to 72 h of exposure. Cell wall thickening, rapid akinete formation, pigment loss, giant cell formation, pyknosis, and purple coloration of the filaments during algae–gold interaction were also evident. The nanoparticles were characterized by UV–Vis spectroscopy, dynamic light scattering, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy. Environmental scanning electron microscopy indicated cell wall distortion of the filaments in Au3+ exposure as well as only intracellular production of gold nanoparticles by Rhizoclonium as no nanoparticles were found on the surface.

Rapid detection of neutral lipid in green microalgae by flow cytometry in combination with Nile red staining—an improved technique

Abstract: A staining protocol for rapid in situ detection of neutral lipid using flow cytometry in combination with Nile red staining was optimized. Staining efficiency was tested in terms of fluorescence intensity (% grandparent) in varied concentrations of Nile red and dimethyl sulfoxide (DMSO), with variable incubation period, temperature and pH level. The improved method was tested using two microalgae: Chlorella ellipsoidea and Chlorococcum infusionum. Maximum staining efficiency was recorded with a concentration of 5 μg mL−1 Nile red and 40 % DMSO in a 15-min incubation at 40 °C for both taxa (pH 6.5). The forward (FSC) and side scatter (SSC) two-dimensional dot plot showed highly scattered cells containing neutral lipid. The coefficient of variation, standard deviation, mean and median values were determined for quantification of neutral lipid. We also applied this modified method to detect the elevated level of neutral lipid in nitrate (NaNO3)-depleted cells; the efficiency of this technique was justified indicating a prominent 3- to 4-fold increase in neutral lipid in treated cells. Confocal images of stained cells also revealed accumulation of high levels of neutral lipid in treated microalgal cells.

Microalgae in Biotechnological Application: A Commercial Approach

Abstract: Microalgae are used as food, feed, and fodder and also used to produce a wide range of metabolites such as, proteins, carbohydrates, lipids, carotenoids, vitamins, fatty acids, sterols, etc. They are able to enhance the nutritional content of conventional food and feed preparations and hence positively affect humans and animal health including aquaculture animals. They also provide a key tool for phycoremediation of toxic metals and nanometal production. The use of microalgae in nanotechnology is a promising field of research with a green approach. The use of genetically modified algae for better production of different biotechnological compounds of interests is popular nowadays. Microalgal biomass production for sustainable biofuel production together with other high-value compounds in a cost-effective way is the major challenge of algal biotechnologists. Microalgal biotechnology is similar to conventional agriculture but has received quite a lot of attention over the last decades, because they can reach substantially higher productivities than traditional crops and can use the wastelands and the large marine ecosystem. As history has shown, research studies on microalgae have been numerous and varied, but they have not always resulted in commercial applications. The aim of this review is to summarize the commercial applications of microalgae.

An alternative high-throughput staining method for detection of neutral lipids in green microalgae for biodiesel applications

Abstract: A simple and high-throughput method for determining in situ intracellular neutral lipid accumulation in Chlorella ellipsoidea and Chlorococcum infusionum with flow cytometry and confocal microscopy was established by employing different solvents and a lipophilic dye, Nile red. Seven different organic solvents, acetic acid, dimethyl sulfoxide (DMSO), acetone, methanol, ethanol, n-hexane, and chloroform at different concentrations ranging from 0 to 80% (v/v) were tested. The fluorescence signal for neutral lipids was collected with a 586/42 emission filter (PE-A) and the maximum fluorescence intensity (% grandparent) was measured as 74.01 ± 4.82% for Chlorella and 70.1 ± 5.52% for Chlorococcum at 30% acetic acid (v/v). The statistical analysis of Nile red-stained cells showed a high coefficient of variation (CV), standard deviation (SD), mean, and median values in the acetic acid-based staining method, followed by DMSO, n-hexane and chloroform. Confocal microscopy revealed a high rate of accumulation of cytosolic neutral lipids when stained with Nile red and other organic solvents. Higher lipid accumulation in Fesupplemented conditions was also detected and a maximum lipid content of 57.36 ± 0.41% (4-fold) in Chlorella and 48.20 ± 0.43% (4-fold) in Chlorococcum were measured at 0.001 g/L of ferrous sulfate (FeSO4). High fluorescence intensity (75.16 ± 0.24% in Chlorella and 72.24 ± 1.07% in Chlorococcum) in Fe-treated cells confirmed the efficiency of the staining procedure.

Rapid Accumulation of Total Lipid in Rhizoclonium africanum Kutzing as Biodiesel Feedstock under Nutrient Limitations and the Associated Changes at Cellular Level.

Abstract: Increase of total lipid and the proportion of the favorable fatty acids in marine green filamentous macroalga Rhizoclonium africanum (Chlorophyceae) was studied under nitrate and phosphate limitations. These stresses were given by both eliminating and doubling the required amounts of nitrate and phosphate salts in the growth media. A significant twofold increase in total lipid (193.03 mg/g) was achieved in cells in absence of nitrate in the culture medium, followed by phosphate limitation (142.65 mg/g). The intracellular accumulation of neutral lipids was observed by fluorescence microscopy. The scanning electron microscopic study showed the major structural changes under nutrient starvation. Fourier transform infrared spectroscopy (FTIR) revealed the presence of ester (C-O-C stretching), ketone (C-C stretching), carboxylic acid (O-H bending), phosphine (P-H stretching), aromatic (C-H stretching and bending), and alcohol (O-H stretching and bending) groups in the treated cells indicating the high accumulation of lipid hydrocarbons in the treated cells. Elevated levels of fatty acids favorable for biodiesel production, that is, C16:0, C16:1, C18:1, and C20:1, were identified under nitrate- and phosphate-deficient conditions. This study shows that the manipulation of cultural conditions could affect the biosynthetic pathways leading to increased lipid production while increasing the proportion of fatty acids suitable for biodiesel production.

Bioremediation of Toxic Metals Using Algae

Abstract: The rapidly growing population and expanding technological activities have accelerated the rate of addition of numerous poisonous pollutants especially the metal ions to the surrounding environment. These pollutants become deleterious due to their mobilization, transport and deposition in the various aquatic as well as terrestrial ecosystems. The cyanobacteria and algae (commonly called together ‘Algae’) constitute the most ancient groups of autotrophic microorganisms and are invariably affected by the presence of metal ions in the environment (Whitton, Arch Mikrobiol 72:353–360, 1970). Algae are the organisms which can resist the metal toxicity by biochemical, chemical and physical mechanisms resulting in cell surface adsorption, metabolism dependent accumulation and precipitation (Gadd GM (1988) Accumulation of metals by microorganisms and algae. In: Rehm HJ (Ed) VCH, Weinheim, pp. 401–434). They instantly interact with metal pollutants differently at cellular level showing different responses and tolerance mechanisms, termed as ‘algae-metal interactions’—which is the basis of phytoremediation process.

Trentepohlia sundarbanensis sp. nov. (Trentepohliaceae, Ulvophyceae, Chlorophyta), a new chlorophyte species from Indian Sundarbans

Abstract: Trentepohlia sundarbanensis is proposed new to science and is characterized by its cell dimensions, sporangial structure and branching pattern. The species was collected from the brackish water zone of Cheramatla Island (N 22°00.117’, E 088°42.608’), located in the Indian Sundarbans. The species grows on the bark of a halophytic mangrove plant, Avicennia alba. In this study the new species’ morphology and relationship with morphologically close species are discussed.

An investigation on Morphotaxonomy and Diversity of Planktonic Chlorophytes from fresh water Eutrophic Wetland of Indian Ramsar Site

Abstract: In first inter-governmental conservation convention at Ramsar, it was decided to designate the important ecosystem throughout the world as ‘Ramsar Site’. Presently in India 26 such sites have been identified. One of which is East Calcutta Wetland (88°27’ E and 22°27’ N), principally used for sewage stabilization and fish production. This wetland had been found to harbor planktonic chlorophytes as the dominating flora controlling the productivity of the ecosystem (more than 90% of total population). Floristic pattern is an important indicator of an ecosystem as any change in plankton flora indicates the altered environmental condition. In the present investigation a thorough survey was carried out for 2 years (January 2012 to January 2014) for documentation and taxonomic identification of cholorophyte population of this important site. A total number of 61 taxa belonging to 17 different genera had been recorded. Among these 13 taxa belonging to 7 different genera such as, Scenedesmus (2 spp.), Desmodesmus (3 spp.) Tetraedron (3 spp.), Pediastrum (1 sp.), Stauridium (2 spp.), Chlorococcum and Kirchneriella, (1 spp. each) were designated as major taxa showing maximum variation in species diversity. Detail morphological studies of dominant taxa were also done with the help of Scanning Electron Microscopy (SEM).

Biochemical modulation of stress related compounds in lead resistant cyanobacteria in short and long term duration

Abstract: Two Lead resistant cyanobacterial taxa, Lyngbya majuscula and Spirulina subsalsa isolated from Lead contaminated area, were exposed to sub-lethal dose of lead (5 mg L-1) for short and long term duration to understand the biochemical modulation in stress related compounds in metal exposure. Both the taxa showed gradual increase in Pb (II) accumulation with time (5-30 mg/g), where Spirulina showed 6 times more accumulation compared to that of Lyngbya. The growth in terms of chlorophyll content at this particular concentration remained almost unchanged in Lyngbya up to 7 days of exposure followed by growth suppression, but Spirulina showed no significant variation in metal exposure during the experimental tenure. The toxicity level, as indicated by total ROS content was determined in terms of malondialdehyde production and maximum value was obtained after long term exposure for both the strains. Upregulation with variation in stress enzyme activities like catalase, ascorbate peroxidase and super oxide dismutase along with proline level were observed within 1 to 24 h of metal exposure giving protection to the metal exposed cell against oxidative stress. But in long term exposure, high rate of carotene accumulation and reduction in cellular glutathione pool may provide protection to oxidative damage of metal treated cyanobacteria.