Ruma Pal

Screening of different algae for green synthesis of gold nanoparticles

The cyanobacteria Phormidium valderianum, P. tenue and Microcoleus chthonoplastes and the green algae Rhizoclonium fontinale, Ulva intestinalis, Chara zeylanica and Pithophora oedogoniana were exposed to hydrogen tetrachloroaurate solution and were screened for their suitability for producing nano‐gold. All three cyanobacteria genera and two of the green algae (Rhizoclonium fontinale and Ulva intestinalis) produced gold nanoparticles intracellularly, confirmed by purple colouration of the thallus within 72 h of treatment at 20°C. Extracted nanoparticle solutions were examined by UV‐vis spectroscopy, transmission electron microscopy (TEM) and X‐ray diffractometry (XRD). XRD confirmed the reduction of Au (III) to Au (0). UV‐vis spectroscopy and TEM studies indicated the production of nanoparticles having different shapes and sizes. Phormidium valderianum synthesized mostly spherical nanoparticles, along with hexagonal and triangular nanoparticles, at basic and neutral pHs (pH 9 and pH 7, respectively). Medicinally important gold nanorods were synthesized (together with gold nanospheres) only by P. valderianum at acidic pH (pH 5); this was initially determined by two surface plasmon bands in UV‐vis spectroscopy and later confirmed by TEM. Spherical to somewhat irregular particles were produced by P. tenue and Ulva intestinalis (TEM studies). The UV‐vis spectroscopy of the supernatant of other algal extracts indicated the formation of mostly spherical particles. Production of gold nanoparticles by algae is more ecofriendly than purely chemical synthesis. However, the choice of algae is important: Chara zeylanica and Pithophora oedogoniana were found to be unable to produce nanoparticles.

Microalgae in aquaculture: a review with special references to nutritional value and fish dietetics.

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.

Accumulation of lead by free and immobilized cyanobacteria with special reference to accumulation factor and recovery

Lead accumulation by free and immobilized cyanobacteria, Lyngbya majuscula and Spirulina subsalsa was studied. Exponentially growing biomass was exposed to 1-20mg L(-1) of Pb(II) solution at pH 6, 7 and 8 for time periods ranging from 10 min to 48 h. L. majuscula accumulated 10 times more Pb (13.5 mg g(-1)) than S. subsalsa (1.32 mg g(-1)) at pH 6 within 3h of exposure to 20mg L(-1) Pb(II) solution and 76% of the Pb could be recovered using 0.1M EDTA. This chelator (2 μM) did not influence Pb accumulation whereas 100 μM citrate increased that of S. subsalsa 6- to 8-fold. L. majuscula filaments enmeshed in a glass wool packed in a column removed 95.8% of the Pb from a 5mg L(-1) Pb solution compared to free and dead biomass which removed 64 and 33.6% Pb respectively. A 92.5% recovery of accumulated Pb from the immobilized biomass suggests that repeated absorption-desorption is possible.

Variations in seasonal phytoplankton assemblages as a response to environmental changes in the surface waters of a hypo saline coastal station along the Bhagirathi-Hooghly estuary.

Due to the close proximity of the Bay of Bengal and the freshwater inflow of Bhagirathi–Hooghly, Diamond Harbour appeared as an important coastal station of the Bhagirathi–Hooghly estuary. The spatial and temporal composition and abundance of microphytoplankton species was examined in relation to physical and chemical surface water variables (i.e., salinity, nutrient, and temperature).The primary objective of the study was to observe the variations in phytoplankton species assemblages as a response to environmental variables. Hierarchical cluster analysis and non-metric multidimensional scaling were used to find out distinct seasonal groups based on the composition of phytoplankton. The results indicate that several key environmental factors like temperature, DIN content, and molar ratio of nutrients like DIN–DIP and DIN–DSi influenced seasonal phytoplankton assemblages within the estuary. The distribution of phytoplankton population showed two main groups where the blue-green and green algal populations favored the warmer conditions of summer and monsoon months, whereas the diatom population primarily flourished in the cooler months of autumn and winter.

Green Synthesis of Gold Nanoparticles Using Cyanobacteria and their Characterization

Two cyanobacteria Lyngbya majuscula and Spirulina subsalsa were used as bioreagent for the green synthesis of gold nanoparticles. Within 72 h of incubation at 15 mg L-1 Au3+ solution, the cyanobacterial biomass turned purple indicating intracellular reduction of Au3+ to Au0 and subsequent formation of gold nanoparticles. Gold nanoparticles were extracted from the gold-loaded biomass using 7.5 mM sodium citrate solution and characterization was done by UVvisible spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR). While Spirulina showed synthesis of spherical nanoparticles of 5 nm -30 nm diameter along with very few nanorods, Lyngbya showed presence of spherical and hexagonal nanoparticles of 2 nm -25 nm diameters. XRD study confirmed the reduction of Au3+ to Au0. FTIR analysis indicated the presence of protein shells around the gold nanoparticles.

Synthesis and Characterization of Nanosilver-A blue green approach

In our thorough investigation of suitability of cyanobacterial strains, commonly known as blue green algae, for cheap ecofriendly nanometal formation, Leptolyngbya valderianum was found to be an effective bioreagent for nanosilver production. The nanosilver synthesis at intracellular level was indicated by the brown biomass of Leptolyngbya after 72 hrs of dark exposure in 9 mM AgNO3 solution. Intracellular silver particles were extracted from the silver loaded biomass and nanosilver production was determined by UV-vis spectroscopy showing absorption peak at ~411 nm. Extracted nanoparticles were further characterized by dynamic light scattering (DLS), zeta potential and X-ray diffraction (XRD) studies. Transmission electron microscopy (TEM) revealed the spherical shape of AgNPs with 2 to 20 nm in diameter. The XRD indicated the 2θ values at 38.20, 44.50, 65.60 and 78.60 which confirmed again the reduction of Ag (I) to Ag (0). Antibiotic property of the AgNP was tested by Agar well diffusion method. Introduction Silver nanoparticles commonly used for nanomedicine production , are reported to be nontoxic to human but most effective against bacteria, viruses, and other eukaryotic microorganisms at very low concentration (Jeong et al. 2005). They are also effective against tumors with anti-proliferative activity (Sriram et al. 2010). The antimicrobial property allows them to be suitably employed in numerous products such as textiles, food storage containers, home appliances and especially in medical devices (Marambio-Jones et al. 2010). Use of AgNP is in medicine industry as tropical ointments to prevent infection against burn and open wounds is quite effective (Ip et al. 2006). Silver nanoparticles (AgNPs) play important role as pesticide filter also (Pradeep and Anshup 2009). Silver nanoparticles are synthesized by different physical and chemical methods like sol-gel technique, solvo-thermal synthesis, chemical reduction, laser ablation, inert gas condensation etc (Huy et al. 2013). The time consuming physical methods are often difficult to achieve and in chemical methods different toxic reagents are used as capping agent like, cetyl trimethyl ammonium bromide (CTAB) leading to undesirable functional aberrations in target cells. Both physical and chemical procedures are very expensive also. Therefore biosynthesis of AgNPs are becoming popular day by day using microorganisms like bacteria (Klaus et al. 1999, Sweeney et al. 2004, Nair and Pradeep 2002); fungi (Ahmad et al. 2003, Ingle et al. 2009, Mukherjee et al. 2001, Gade et al. 2008, Sanghi et al. 2009) and algae (Govindaraju et al. 2009, Mohseniazar et al. 2011). Only sporadic reports are available regarding filamentous cyanobacteria based AgNP production like, Plectonema boryanum(Lengke et al. 2007), Oscillatoria willei (Ali et al. 2011) and Spirulina platensis (Govindraju et al. 2008). In search for a very suitable bio-reagent for AgNP production, we recorded Leptolyngbya valderianum as more effective strain, as it is widespread in distribution than the studied taxa. They flourish from freshwater to marine region, moreover very cheap production of biomass is possible within very short time reducing the production cost of the nano-metal. Size determination was done in the present investigation employing TEM study and complete characterizations of AgNP were made by XRD, DLS, and Zeta potential studies. Rate of AgNP production per gm biomass was determined and pure nanometal was extracted from the biomass. Antibiotic property was determined by agar well diffusion methods. All these studies would analyze the structure and stability of AgNP in pure form and can be used for further exploitation. Materials and methods The experimental strain, L. valderianum was collected from eastern part of India (Suderbans, West Bengal) and pure strain was obtained from Phycology Laboratory, CU. A small portion of healthy growing biomass (10 mg FW) was exposed to 100 ml of 9 mM Ag (I) solution (pH 3.86), (AgNO3, MW 169.86, Merck, India) and was kept in dark condition at room temperature. After 72 h yellowish brown biomass was removed from the silver nitrate solution and washed with double distilled water. To extract the particles, algal biomass was sonicated for 30 min at 60% amplitude with 7.5 mM sodium citrate solution by a Hielscher UP100H ultrasonic processor (Teltow, Germany) and was centrifuged at 3000 rpm for 5 min in a C-24 BL Remi cooling centrifuge (Maharashtra, India). The supernatant was collected for further analysis. A UV-vis spectrum of the extract was recorded in the wavelength range of 200nm-1100nm with a Thermo Evolution 300 UV-visible spectrophotometer (Waltham, USA). DLS measurement was done with 1 mL of suspension using Nano ZS (Malvern) to study the hydrodynamic size of the particles distributed in citrate solution. Zeta potential of the suspension was determined using the same instrument to determine the stability of the nanoparticles. Silver loaded brown colored biomass was air-dried, made it into powder using mortar and pestle and used for powder XRD analysis. The XRD spectra were recorded from 5° to 100° 2θ angles with a Panalytical PW 3040/60, DY 2501 X-ray diffractometer (Netherland) using Cu Kα radiation operated at 40 kV and 30 mA to confirm the presence of Ag (0). A drop of nanoparticle extract was dried on a carbon coated copper grid and the morphology and size analysis of biosynthesized AgNPs was carried out by JEOL JEM 2100 HR-TEM. The extracted golden brown suspension was lyophilized and nano silver production rate was determined in relation to biomass weight (mg/gm biomass). Antibacterial activity of the synthesized silver nanoparticles was determined using the agar well diffusion method against gram negative bacteria Pseudomonas aeruginosa (MTCC 424). The bacterial strain was obtained from Microbial type culture collection and gene bank (MTCC, Chandigarh, India). The inoculums suspensions were spread uniformly in different nutrient agar plates. Cavities were made in each plate using a well-cutter and it was filled with silver nanoparticle solution (100 ml) with different concentions, 1 mg/ml, 0.5 mg/ml, and 0.1 mg/ml and then incubated at 37 °C. Sodium citrate was used as negative control because AGNPs were suspended in citrate solution. The diameter of clear zone was measured.

Hydrolysate of lipid extracted microalgal biomass residue: An algal growth promoter and enhancer.

The present study demonstrates the utilization of the algal hydrolysate (AH) prepared from lipid extracted residual harmful bloom-forming cyanobacteria Lyngbya majuscula biomass, as a growth supplement for the cultivation of green microalgae Chlorella vulgaris. BG-11 replacements with AH in different proportions significantly affects the cell count, dry cell weight (DCW), biomass productivity (BP) and pigments concentration. Among all, 25% AH substitution in BG11 media was found to be optimum which enhanced DCW, BP and pigments content by 39.13%, 40.81% and 129.47%, respectively, compared to control. The lipid content (31.95%) was also significantly higher in the 25% AH replacement. The volumetric productivity of neutral lipids (ideal for biodiesel) and total protein content of the cells significantly increased in all AH substitutions. Thus, lipid extracted microalgal biomass residue (LMBR) hydrolysate can be a potential growth stimulating supplement for oleaginous microalgae C. vulgaris.

An introduction to phytoplanktons : diversity and ecology

1. A Brief Introduction to Phytoplanktons.- 2. Physico- Chemical Environment of Aquatic Ecosystem.- 3. Phytoplanktons and Primary Productivity.- 4. Community Pattern Analysis.- 5. Case Study.- 6. Glossary.- 7. Bibliography.

Evaluation of algae based feed in Goldfish (Carassius auratus) nutrition

A short term laboratory feeding trial was conducted to evaluate the importance of algae based value added feed for the popular ornamental fish Carassius auratus (Gold fish). The feed was tested against Daphnia — the conventional feed used for Goldfish. Fresh algal biomass of Nostoc ellipsosporum and Navicula minima were mixed with daphnia to formulate the value added feed and proximate composition of feeds were analyzed. The experimental feed showed significantly higher protein (71.24% ±0.3), lipid (33.47%±0.2), and carotenoid (6.41%±0.13) (Pd″0.05), and increased level of amino acids (4.2%±0.1) and carbohydrate (14.72%±0.2) content than the control feed. Similarly the fishes fed with experimental feed showed 2 fold increase in protein, glycogen and carotenoid level as compared to the control fishes. Morphometric study also showed significant Body weight Gain (3.52%±1.2) and Specific growth rate (0.87±0.41) together with high Protein Productive value (0.051±0.14), Protein effficiency ratio (0.074±0.05) and low Feed conversion ratio (0.024±0.03) in experimental fishes which signifies better utilization of feed by the fishes. The VAF (Value added feed) fed fishes showed positive results in both morphometry and carcass proximate composition. Differences in body weight gain and Feed conversion ratio together with increased protein, glycogen and carotenoid levels were significant than the control fishes. The colouration of the gold fishes induced by algal carotenoids was more bright and vibrant indicating high market value.

An eco-friendly novel separation of carrier-free thallium radionuclide from mercury and lead radionuclides using algae as bio-reagent

Here we report a novel separation technique for the clinically important 199Tl radionuclide from its precursor lead and daughter product mercury. Two algal genera, Lyngbya major, from cyanophyceae and Rhizoclonium hieroglyphicum from chlorophyceae have been used as natural bioreagents in the separation of thallium radionuclides in ultra-trace scale. 24 h algal treatment of an aqueous solution at pH 8 containing a mixture of radionuclides shows that Rhizoclonium accumulates 100% Hg, >80% Pb and a small fraction of thallium (15%). Thus a large fraction of thallium remains in the solution not accumulated by algae. Thus the selectivity of various algae towards different metals in sorption and desorption processes may be exploited in the separation of these metals from a mixture of them.