Selected Species Of Microalgae Research Articles

Characterization of Selected Microalgae Species as Potential Sources of Nutrients and Antioxidants.

Microalgae are exceptional organisms from a nutritional perspective, boasting an array of bioactive compounds that have long justified their incorporation into human diets. In this study, we explored the potential of five microalgae species: Nannochloropsis sp., Tetraselmis chuii, Chaetoceros muelleri, Thalassiosira weissflogii, and Tisochrysis lutea. We conducted comprehensive analyses of their nutritional profiles, encompassing protein content, individual amino acid composition, mineral and trace element levels, fatty acid profiles (including saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs)), polyphenol compositions, and vitamin B content. The antioxidant activity of the ethanolic extracts was evaluated using two methods: ABTS and DPPH radical scavenging assay. The total protein content of the microalgae ranged from 34.09 ± 0.39% to 42.45 ± 0.18%, with the highest concentration observed in T. weissflogii. Essential amino acids such as histidine, threonine, lysine, valine, isoleucine, leucine, phenylalanine, and methionine were present in concentrations ranging from 0.53 ± 0.02 to 12.55 ± 2.21 g/16 g N. Glutamic acid emerged as the most abundant amino acid, with concentrations ranging from 6.73 ± 0.82 to 12.55 ± 2.21 g/16 g N. Among the microalgae species, T. chuii exhibited the highest concentrations of calcium (Ca) and manganese (Mn), while C. muelleri showed prominence in magnesium (Mg), sodium (Na), and iron (Fe). T. weissflogii stood out for its potassium (K) content, and T. lutea contained notable amounts of copper (Cu), zinc (Zn), and lead (Pb). Regarding fatty acid profiles, Nannochloropsis sp. and T. chuii were predominantly composed of SFA, while C. muelleri and T. weissflogii were rich in MUFA. PUFAs dominated the fatty acid profile of T. lutea, which also exhibited the most diverse range of polyphenolic substances. We also analyzed the B vitamin content, with T. lutea displaying the highest concentrations of niacin (B3) and riboflavin (B2). Antioxidant activity was confirmed for all microalgae tested using DPPH and ABTS radical IC50 (mg/mL) converted to Trolox equivalent (TEAC). These findings underscore the substantial potential of the examined microalgae species as sources of biologically valuable substances characterized by rapid growth and relatively undemanding cultivation conditions.

Solar bioreactors used for the industrial production of microalgae.

Microalgae are excellent sources of biomass containing several important compounds for human and animal nutrition-proteins, lipids, polysaccharides, pigments and antioxidants as well as bioactive secondary metabolites. In addition, they have a great biotechnological potential for nutraceuticals, and pharmaceuticals as well as for CO2 sequestration, wastewater treatment, and potentially also biofuel and biopolymer production. In this review, the industrial production of the most frequently used microalgae genera-Arthrospira, Chlorella, Dunaliella, Haematococcus, Nannochloropsis, Phaeodactylum, Porphyridium and several other species is discussed as concerns the applicability of the most widely used large-scale systems, solar bioreactors (SBRs)-open ponds, raceways, cascades, sleeves, columns, flat panels, tubular systems and others. Microalgae culturing is a complex process in which bioreactor operating parameters and physiological variables closely interact. The requirements of the biological system-microalgae culture are crucial to select the suitable type of SBR. When designing a cultivation process, the phototrophic production of microalgae biomass, it is necessary to employ SBRs that are adequately designed, built and operated to satisfy the physiological requirements of the selected microalgae species, considering also local climate. Moreover, scaling up microalgae cultures for commercial production requires qualified staff working out a suitable cultivation regime. KEY POINTS: • Large-scale solar bioreactors designed for microalgae culturing. • Most frequently used microalgae genera for commercial production. • Scale-up requires suitable cultivation conditions and well-elaborated protocols.

ALGAE CAROTENOID PIGMENTS AS NEW SOURCES OF HALAL BIOACTIVE INGREDIENTS

Halal Active Pharmaceutical Ingredient (API) is a substance used in a finished pharmaceutical product, intended to furnish pharmacological activity or contribute direct effect in the diagnosis, cure, mitigation, treatment or prevention of disease. It also provides a direct effect in restoring, correcting or modifying physiological functions in human beings. Microalgae, which are single-celled microorganisms, are considered to be a rich source of diverse bioactive molecules. They play a vital role in the aquatic food chain as primary producers and can store complex organic compounds in their bodies, which can be released with the help of sunlight. Microalgae have evolved distinctive metabolic pathways, resulting in the production of remarkable secondary metabolites and unique structures that differ from those found in superior plants. Due to the high structural diversity of pigments, microalgae have the potential to produce pharmacologically valuable compounds, making them a promising source of bioactive molecules. This study aimed to examine the carotenoids pigmentation profiling from selected microalgae species subjected to different culture conditions. The methods involve are microalgae cell culture mass production, carotenoid sample extraction and HPLC analysis. The findings revealed that the composition and amount of carotenoids differ according to the microalgae species. Genetic factors appear to be a crucial factor in categorizing these species based on their individual carotenoids accumulation. In short, selecting the appropriate species with the ability to accumulate carotenoids is important in determining the sources of pigments for halal bioactive ingredients or for commercial purposes, particularly in the halal market.

Microalgae as an aquaculture feed produced in a short light-path annular column photobioreactor

In this work, four microalgae species (Chlorella vulgaris, Trachydiscus minutus, Monodopsis sp., and Monoraphidium sp.) were selected and grown in a novel, 30 L short-light path annular-column photobioreactor (AC-PBR). The aim was to test the microalgae growth on a pilot scale and evaluate the potential use as an alternative fish feed in hatcheries based on the content and composition of fatty acids. All microalgae species reached a high biomass density between 3.65 and 5.32 g DW L−1 during a 14-day trial. The highest growth rate of 0.25 ± 0.05 d−1 was calculated for Trachydiscus culture. The highest total content of fatty acids (TFA) was determined for Monodopsis and Trachydiscus biomass as the concentration reached 74.5 ± 6.3 and 72.4 ± 7.6 mg g−1 DW, respectively. These two species contained mostly eicosapentaenoic acid (EPA; C20:5n3), the crucial FA for carnivorous fish whose concentration reached the value of 25.3 ± 0.9% and 31.9 ± 2.0% of TFA for Monodopsis and Trachydiscus, respectively. A high amount of linoleic acid (LA; C18:2n6), another important FA for freshwater aquafeed, was found in Chlorella biomass up to the concentration of 21.9 ± 1.5% of TFA. The present results suggest the feasibility of in-house cultivation of selected microalgae species as a quality live feed source for fish hatcheries.

Chemical composition of selected marine microalgae, with emphasis on lipid and carbohydrate production for potential use as feed resources

Marine microalgae are a promising sustainable source of lipids, omega-3 fatty acids, and carbohydrates. Selected microalgae species belonging to the Bacillariophyceae, Haptophyceae, Eustigmatophyceae, and Prasinophyceae were characterised for cellular content of carbon and nitrogen, and for production yields of lipids, fatty acids, total carbohydrates, and β-glucans. Carbon and nitrogen content showed a hyperbolic decrease with increasing cell numbers for Chaetoceros calcitrans, C. muelleri, Skeletonema costatum, Tetraselmis sp., and Nannochloropsis oculata. Cultures of Pavlova lutheri and Tisochrysis lutea showed an increase in carbon content per cell, but a decrease in nitrogen content. The total lipid content of C. muelleri, C. calcitrans, N. oculata, and T. lutea increased with decreasing relative growth rate; however, the highest productivity of lipids was found in T. lutea grown at 40% of the maximum specific growth rate. The highest content of eicosapentaenoic acid was found in C. muelleri, C. calcitrans, and N. oculata, and the highest content of docosahexaenoic acid was found in T. lutea. The β-glucan fraction of the carbohydrates was highest in C. muelleri and C. calcitrans and was very low in N. oculata. Out of the species investigated, C. muelleri had the highest production yield of β-glucans, obtained when cultivated at a 40% relative growth rate.

Microalgae disruption techniques for product recovery: influence of cell wall composition

Microalgae are one of the most promising feedstocks for the production of commodity and value-added products. However, the use of microalgae as a feedstock is hampered by the process economics and sustainability. Overall sustainability can be improved by employing energy-efficient cell disruption and recovery processes to maximize the extraction of desired compounds from microalgal biomass. Most often, extraction processes are conducted with solvents using untreated, chemically treated, or mechanically treated cells. However, microalgal cell walls are sometimes structurally robust, complex, and chemically diverse and high energy inputs or large quantities of chemicals are required to extract products from within the cell. Various chemical, biological, and physical techniques have been employed to disrupt the cell walls from a variety of microalgae species, and these include the use of surfactants, autoclave, microwave, sonication, bead milling, enzymatic hydrolysis, high-pressure homogenization, and steam treatments. Although the cell wall structure is important for product recovery, it is often not considered when selecting the most appropriate disruption method. In this study, the cell wall structure of selected microalgae species and the effectiveness of various cell wall disruption techniques on product recovery are reviewed. It was concluded that future research must focus on developing an understanding of the relationship between cell wall disruption mechanisms and cell wall composition and structure, as well as optimizing the energy consumption of the disruption technique. This approach would enable the design of innovative cell wall disruption techniques for an enhanced product recovery.

Nutrient removal from hydroponic wastewater by a microbial consortium and a culture of Paracercomonas saepenatans

The potential of microbial processes for removal of major nutrients (e.g., N, P) and inorganic cations (e.g., Ca2+, Mg2+, and Fe2+) from hydroponic systems was investigated. Microbial consortium- and axenic culture-based experiments were conducted in a waste nutrient solution (WNS). A microbial consortium grown in the WNS and selected microalgae species of Paracercomonas saepenatans were inoculated in two different synthetic media (Bold’s Basal Medium (BBM) and synthetic WNS) in batch systems, and the microbial growth characteristics and the rate and extent of nutrient removal were determined for each system. No toxicity or growth inhibition was observed during microbial growth in either media. Both the waste-nutrient-grown microbial consortium and Paracercomonas saepenatans can be grown effectively in BBM and WNS, and both remove most ions from both media (e.g.,>99% removal of NO3− and 41–100% removal of PO43−) within 16days. Significant nutrient removal was observed during the growth phase of the microbial communities (4–10days period), indicating major nutrient utilization for microbial growth as well as chemical mineral precipitation. Furthermore, MINEQL+4.6 modeling showed higher PO43− removal in WNS during microbial growth (compared to BBM) due to precipitation of phosphate minerals (e.g., hydroxyapatite, vivianite). The dominant microbial species in both systems were also identified. DNA sequencing showed that Vorticella (58%) and Scenedesmus (33%) in WNS and Scenedesmus (89%) in BBM were the predominant species. This study demonstrates the potential application of microbial consortium (predominantly algae and protozoan)-based treatment techniques for hydroponic systems.

Oil Algae Extraction of Selected Microalgae Species Grown in Monoculture and Mixed Cultures for Biodiesel Production

Abstract The idea of using microalgae as a bio-source of biodiesel is being taken seriously because of the escalating price of fossil fuel. As the tropical country, which gets the sun a year round, Indonesia has big potential for cultivating microalgae in large scale, as biodiesel feedstock. This study examines the algal oil extraction of selected monoculture microalgae species of Botryococcus braunii , Nannochloropsis sp. , Arthrospira platensis and mixed cultures microalgae from South Coast of Yogyakarta, Indonesia. Among all species of microalgae studied, Nannochloropsis sp. was found to have the highest algal oil yield (0.0346 g dry algal oil/g dry microalgae) and theoretical calorific value (187.69 kcal/kg dry microalgae).

Dry weight, carbon, c/n ratio, hydrogen, and chlorophyll variation during exponential growth of selected microalgae species used in aquaculture.

Microalgae are commonly used as food source in aquaculture, mainly for shellfish and larvae ofcrustacean and fish. All hatcheries need an excellent inoculum to produce high-quality microalgae when cultured outdoor in extensive systems, and this depends largely on the health of the microalgae cultured under laboratory conditions as a primary step. Therefore, the aim of this work was to assess variations of dry weight, carbon, C/N ratio, hydrogen and chlorophylls as physiological indicators of nutrients uptake and growth rate during exponential growth of Isochrysis galbana, Chaetoceros calcitrans and Dunaliella tertiolecta, using f/2 as culture medium.Chaetoceros calcitrans and D. tertiolecta had higher carbon content (~30 pg cell-1). The C/N ratio varied widely, gradually decreasing on I. galbana. Chlorophyll a varied among the three microalgae tested, ranging from <0.05 to >0.25 pg cell-1. Growth rate was higher in I. galbana (K’ 0.83) followed by D. tertiolecta and C. calcitrans. Results showed that nutrient incorporation by cell change when cell density increases; this information providesnew insights in the physiology of marine microalgae and confirms that nutrient uptake dynamics is different in each microalga species. Finally, this study indicates that using one culture medium is not equally efficient for all microalgae used in aquaculture since each species has specific nutritional requirements.

Emission of iodine-containing volatiles by selected microalgae species

Abstract. In this study we present the results of an emission study of different phytoplankton samples in aqueous media treated with elevated ozone levels. Halocarbon measurements show that the samples tested released bromoform and different iodocarbons, including iodomethane, iodochloromethane and diiodomethane. Iodide and iodate levels in the liquid phase were representative of concentrations of surface water in a natural environment. Measurement of volatile iodine (I2) emissions from two diatom samples (Mediopyxis helysia and Porosira glacialis) and the background sample (F/2 medium from filtered natural seawater) showed that the quantity of evolved I2 depends on the ozone concentration in the air. This behaviour was assumed to be caused by the oxidation reaction mechanism of iodide with ozone. The I2 emission flux agrees with model calculations at different iodide concentrations. The I2 emission of a natural plankton concentrate sample was, however, very low compared to other samples and showed no dependence on ozone. The reason for this was shown to be the low iodide concentration in the algal suspension, which seems to be the limiting factor in the oxidative formation of I2.

Protein and Amino Acid Content of Selected Microalgae Species

Lysed cells of seven species of microalgae were analysed for amino acid composition and total protein content. The samples ranged from 15 to 67 g/100 g protein on a dry weight basis, measured by the micro-Kjeldahl method. Variability of amino acid composition among the species was significant. Nutritional ramifications are discussed.