Showing papers on "Chlorococcum published in 2020"

Role of C/N ratio on microalgae growth in mixotrophy and incorporation of titanium nanoparticles for cell flocculation and lipid enhancement in economical biodiesel application

Abstract: Present study aimed to evaluate the influence of carbon/nitrogen ratio (C/N) on mixotrophic growth of microalgae and role of nanomaterial in cell recovery and lipid improvement. In this study, three microalgae species were isolated, screened from local freshwater body for lipid assimilation. The microalgae were identified as Chlorococcum sp., Scenedesmus sp., and Euglena sp. Mixotrophic cultivation of each microalgae strain using various organic carbon sources was preferred in contrast with photoautotrophic mode. Sucrose represented as the preeminent source for enhancing the microalgae biomass of 3.5 g/L and lipid content of 58.35%, which was a significant improvement as compared to control. Later, response surface methodology–central composite design (RSM–CCD), tool was employed to optimize the C/N ratio and demonstrated the maximum biomass production of 5.02 g/L along with the increased lipid content of 60.34%. Ti nanoparticles (Ti nps) were added to the culture for lipid enhancement in the stationary phase and biomass removal was performed by nanoparticle (np)-mediated flocculation technique. Optimized concentration of 15 ppm Ti nps determined the cell harvesting efficacy of 82.46% during 45 min of sedimentation time and 1.23-fold lipid enhancement was reported. Extracted lipid was converted to fatty acid methyl esters (FAME) by the process of transesterification and analyzed by gas chromatography–mass spectrometry (GC–MS). Characterization of FAME revealed the presence of 56.31% of saturated fatty acid (SFA) and 29.06% unsaturated fatty acids (UFA) that could be processed towards sustainable biodiesel production. Hence, our results suggested that integration of mixotrophic cultivation and Ti nps emerged as a new cost-effective approach for biomass and lipid enhancement in microalgae Chlorococcum sp.

Evaluation of Freshwater Microalgal Isolates for Growth and Oil Production in Seawater Medium

Abstract: Microalgal cells have the potential to rapidly accumulate lipids which find applications as biodiesel production and nutraceuticals (e.g., EPA and DHA). Seawater is considered as an attractive medium for cultivation of microalgae since it contains most of the mineral nutrients. Besides, it offers the advantage of lesser bacterial and fungal contamination which is the main cause of decreased biomass productivity in open pond cultivation of freshwater microalgae. The present work describes the screening of freshwater microalgal isolates for production of biomass and lipids in a seawater based medium against freshwater medium under phototrophic cultivation. Isolate RAP-13, RI67-1 and R167-3 had maximum biomass production, whereas lipid yield was highest in the isolate RAP-13(67 mg/l). The potent isolate RAP-13 identified as Chlorococcum sp., was able to grow under a wide range of pH (4–10) in the seawater medium. Freshwater microalgae adapted well and yielded more lipids in seawater medium indicating the potential to cultivate them in marine water reducing the freshwater footprint.

Bioprospecting and LED-based spectral enhancement of antimicrobial activity of microalgae isolated from the west of Ireland

Abstract: Antimicrobial screening programmes have shown that microalgae constitute a rich source of secondary metabolites exhibiting antimicrobial activity against human and aquaculture pathogens. In this study, extracts from 80 newly isolated marine and freshwater microalgae strains were tested for antimicrobial activity against 6 pathogens (Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus and Candida albicans). Principal Component Analysis and Hierarchical Clustering analyses (PCA-HC) of 4320 disc diffusion inhibition zones defined three main groups comprising strains with polar fractions inhibiting gram-positive bacteria, strains which exhibited broad spectrum activity and strains with non-polar fractions inhibiting gram-positive bacteria and C. albicans. Minimum Inhibitory Concentration (MIC) values were determined for 23 promising strains, which returned an activity threshold ≥15 mm inhibition zone diameter by disc diffusion method for at least one pathogen. The relationship between spectral quality and antimicrobial activity was further investigated for 5 promising strains (diatom Stauroneis sp. LACW_24, haptophyte Prymnesium sp. DMGCW_41, and chlorophytes cf. Chlorococcum sp. DMGCW_43, cf. Micractinium sp. LACW_01 and Tetraselmis sp. LACW_06), indicating a significantly higher bioactivity under blue light for the chlorophytes and red light for the diatom Stauroneis sp. LACW_24. Polar fractions from cf. Chlorococcum sp. DMGCW_43 and Stauroneis sp. LACW_24 possessed broad spectrum antibacterial activity with MIC values of 157 μg/mL and 875 μg/mL against P. aeruginosa, 157 μg/mL and 1000 μg/mL against E. coli, 438 μg/mL and 875 μg/mL against B. subtilis and E. faecalis, 110 μg/mL and 219 μg/mL, against S. aureus, respectively. This screening programme has led to the identification of several strains with promising antimicrobial activity. In addition, the manipulation of LED-based spectral quality to enhance the bioactivity of antimicrobial components within several candidate strains is described for the first time.

Application of live Chlorococcum aquaticum biomass for the removal of Pb(II) from aqueous solutions

Abstract: Microalgae readily develop tolerance against environmental pollutants and are also capable of utilizing heavy metals in their metabolic activities. Microalgae-based heavy metal removal provides an eco-friendly, cost-effective technology to treat wastewater. In this study, a strain of the green alga Chlorococcum aquaticum, isolated from water polluted with Pb2+, was selected for bioremediation of Pb2+ in aqueous solutions. Chlorococcus aquaticum showed a high level of tolerance toward Pb2+ with an LC50 of 100 mg L−1. To assess the efficacy and practicality of the bioremediation process, adsorption isotherms and kinetic models were developed. The best-fitted adsorption model was Freundlich isotherm with the adsorption constant (KF) = 2.18 mg g−1 and n = 1.01, suggesting a multilayer adsorption to heterogeneous surfaces. The kinetic studies revealed that the interaction of Pb2+ with C. aquaticum obeys pseudo second-order kinetics with the rate constant (k′) = 1.21 × 10−5 g mg−1 min−1 and the amounts of Pb2+ adsorbed per gram of adsorbent at equilibrium (qe) = 500 mg g−1, indicating that the rate determining step involves a chemical reaction mechanism. Chlorococcum aquaticum showed a high tolerance toward Pb2+, high adsorption capacity and a moderate adsorption rate. Thus, growing C. aquaticum can be identified as a potential environmentally friendly and low-cost sorbent to remove a wide range of Pb2+concentrations from wastewater.

Isolation, Identification and Biotechnological Applications of a Novel, Robust, Free-living Chlorococcum (Oophila) amblystomatis Strain Isolated from a Local Pond

Abstract: Bioprospection of novel autochthonous strains is key to the successful industrial-scale production of microalgal biomass. A novel Chlorococcum strain was recently isolated from a pond inside the industrial production facility of Allmicroalgae (Leiria, Portugal). Phylogenetic analysis based on 18S ribosomal ribonucleic acid (rRNA) gene sequences suggests that this isolate is a novel, free-living Oophila amblystomatis strain. However, as our phylogenetic data strongly suggests that the aforementioned taxon belongs to the genus Chlorococcum, it is here proposed to rename this species as Chlorococcum amblystomatis. In order to characterize the biotechnological potential of this novel isolate, growth performance and biochemical composition were evaluated from the pilot (2.5-m3) to industrial (10-m3) scale. The highest maximum areal productivity (36.56 g·m−2·day−1) was reached in a 10-m3 tubular photobioreactor (PBR), as compared to that obtained in a 2.5-m3 PBR (26.75 g·m−2·day−1). Chlorococcum amblystomatis displayed high protein content (48%–56% dry weight (DW)) and moderate levels of total lipids (18%–31% DW), carbohydrates (6%–18% DW) and ashes (9%–16% DW). Furthermore, the lipid profile was dominated by polyunsaturated fatty acids (PUFAs). The highest pigment contents were obtained in the 2.5-m3 PBR, where total chlorophylls accounted for 40.24 mg·g−1 DW, followed by lutein with 5.37 mg·g−1 DW. Overall, this free-living Chlorococcum amblystomatis strain shows great potential for nutritional applications, coupling a promising growth performance with a high protein content as well as relevant amounts of PUFAs, chlorophyll, and carotenoids.

Upgrading Microalgal Biocrude Using NiMo/Al-SBA-15 as a Catalyst

Abstract: Biocrude from Chlorococcum sp. algae was hydrotreated in batch autoclaves in the presence and absence of Al-SBA-15 supports and NiMo/Al-SBA-15 catalysts with different Si/Al ratios and hence differ...

Comparison of Sensitivity of Tropical Freshwater Microalgae to Environmentally Relevant Concentrations of Cadmium and Hexavalent Chromium in Three Types of Growth Media

Abstract: Sensitivity of tropical freshwater microalgae (Mesotaenium sp., Chlorococcum sp. and Scenedesmus sp.) to environmentally relevant concentrations of hexavalent chromium (Cr6+) and cadmium (Cd2+) was compared individually in three growth media viz. Bold’s Basal Medium (BBM), Test Medium 1 (TM1) and Test Medium 2 (TM2) based on fluorescence reduction. Free metal content of growth media was determined by Visual MINTEQ (version 3.1). After 24 h, relative fluorescence of microalgae in the three media decreased with increased metal concentration showing a concentration dependent graded toxicity response. All microalgae were more sensitive to the metals when grown in TM1, when compared, more sensitive to Cr6+ than Cd2+. Metal speciation indicated that TM1 and TM2 media have higher percentage of bioavailable Cd2+ than BBM, and chromium was present mainly as CrO42− and HCrO4−. The results suggest that the TM1 medium is more suitable under short term exposure of microalgae to metals in environmental monitoring.

Bioaccumulation and Toxicity of As in the Alga Chlorococcum sp.: Prospects for As Bioremediation.

Abstract: Ubiquitous distribution, fast growth rate and manifold relevance has credited algae a potential bioresource in current state of affairs of environmental degradation. In the present study, green alga Chlorococcum sp. has been collected from waste water, isolated and cultured to assess their accumulation and toxicity responses at different As(III) concentration. Results revealed that Chlorococcum sp. treated with 10 µM As(III) showed a minimal reduction (21%) in chlorophyll concentration with high proline and carotenoids content indicating its adaptive tolerance potential against As(III). The EC50 of As(III) for inhibiting growth of the microalgae after 10 days of experiment was 9.4 µM. Further, Chlorococcum sp. accumulated 239.09 µg g− 1 dw As at the concentration of 10 µM of As(III) after 10 days of treatment. Concentration dependent accumulation pattern and antioxidant responses in Chlorococcum sp. could be a used as a potential bioindicator and bioremediator of As from waste water.

In vitro optimization for enhanced cellulose degrading enzyme from Bacillus licheniformis KY962963 associated with a microalgae Chlorococcum sp. using OVAT and statistical modeling

Abstract: Cellulase has gained interest in researchers due to its great applicability in the field of biotechnology. The Bacillus licheniformis KY962963 used in the study was isolated from Chlorococcum sp. Optimization of various physical parameters like pH, temperature, salinity and effect of co-inducers on the cellulase production (FPase and CMCase) was carried out. In crude enzyme extracts, the selected bacterial strain exhibited higher endoglucanase (CMCase) activity as compared to total cellulase activity (FPase). The highest production of cellulase was obtained with Bacillus licheniformis KY962963 when 1% (w/v) cellulose and 0.5% (w/v) peptone as co-inducers was used at 37 °C, pH 7.0, 72 h of production time where CMCase activity was found to be of 7.72 IU/ml and FPase 6.19 IU/ml. The conditions were optimized using OVAT approach which were further validated through statistical modeling. The methods used in this study has established its suitability to optimize cellulase production for its industrial applicability.

Population density and reproductive potential comparison of Simocephalus vetulus (Müller, 1776) cultured with a mixed diet with chlorophytes (Scenedesmus sp + Chlorococcum sp.) and diatoms (Pinnularia sp.) at different concentrations

Abstract: This study was focused to know the population density growth of Simocephalus vetulus fed with four experimental diets using chlorophytes and diatoms during 60 days of culture, in 12 L plastic beakers filled with 10 L of water, with an initial density of 20 organisms. Diets were: 1) Chlorophyte 100%, 2) Diatoms 100%; 3) Chlorophytes 25% and Diatoms 75%, and 4) Chlorophytes 75% and Diatoms 25%. Organisms fed with Chlorophytes 75% and Diatoms 25% obtained the highest density with 6,041±18 org 10L-1, while the lowest density value was for Chlorophytes 100% with 1,109±10 org 10 L-1. Highest value of Ro was obtained with diet Chlorophytes 75% and Diatoms 25% with 1,287 org female-1, Tc = 16.15 days, and r = 0.43. Lowest reproductive potential values were shown in Chlorophyte diet with 148 org female-1), Tc = 21.98 days, and r = 0.23. ANOVA and Tukey test shown significant differences (P