Simulation of biocrude production from P. tricornutum, S. platensis, and C. vulgaris using Aspenplus®.

Hydrothermal liquefaction (HTL) of biomass is performed at elevated pressure and temperature to avoid the drying process. This process is also suitable for the low grade biomass with higher moisture content. In this article, simulation of three types of microalgae species, such as Phaeodactylum tricornutum, Spirulina platensis, and Chlorella vulgaris, are performed using Aspen Plus®. Simulation conditions, for instance, temperature, proximate and ultimate analyses, feed rate, water content, component names, etc., are taken from the literatures. The results of microalgae are then compared at two different temperature conditions. The values, however, are not the same for all the materials due to the data availability from the literature. The highest calorific value is obtained from C. vulgaris; it is 37.27 MJ/kg at 621K, and the highest energy recovery and energy ratio are obtained from P. tricornutum; they are 88.78 % and 1.86, both at 648K respectively. The difference between experimental and simulated calorific values of different biocrudes are ranging from 2.7 % to 3.62 % at higher temperatures and from 4.68 % to 10.72 % at lower temperatures. Finally, it is found that the simulation results corroborate with the experimental results with minimal errors.

Safety of a change in specifications of the novel food oleoresin from Haematococcus pluvialis containing astaxanthin pursuant to Regulation (EU) 2015/2283.

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on the safety of a change of specifications of the novel food (NF) oleoresin from Haematococcus pluvialis containing astaxanthin (ATX) pursuant to Regulation (EU) 2015/2283. The NF is already authorised as ingredient for the use in food supplements as defined in Directive 2002/46EC in accordance to Regulation (EU) 2017/2470. The NF concerns an oleoresin which contains ~ 10% ATX, obtained by supercritical CO2 extraction of the homogenised and dried biomass of cultivated H. pluvialis. This NF has been assessed by the Panel in 2014. With the present dossier, the applicant proposed to lower the minimum specification limits for protein and ATX monoesters for the NF, and to increase the maximum specification limit for the relative amount of ATX diesters in total ATX. An increase of the maximum specification limit for the 9-cis isomer is also applied for. Although the data are limited regarding bioavailability and distribution in humans of these three naturally occurring ATX isomers, the available in vitro and in vivo data suggest that the 13-cis rather than the 9-cis ATX is selectively absorbed, i.e. has a higher bioavailability and/or possibly emerges from isomerisation of all-trans ATX. The Panel notes that the toxicity of the individual ATX isomers has not been studied individually. However, the ADI of 0.2 mg/kg, which was established for synthetic ATX and ATX from H. pluvialis, applies also for ATX in the oleoresin from H. pluvialis with the proposed changes of specifications. The Panel concludes that the NF, oleoresin from H. pluvialis containing ATX, is safe with the proposed specification limits.

Overexpression of PSR1 in Chlamydomonas reinhardtii induces luxury phosphorus uptake.

Remediation using micro-algae offers an attractive solution to environmental phosphate (PO4 3-) pollution. However, for maximum efficiency, pre-conditioning of algae to induce 'luxury phosphorus (P) uptake' is needed. To replicate this process, we targeted the global regulator PSR1 (Myb transcription factor: Phosphate Starvation Response 1) for over-expression in algae. Manipulating a single gene (PSR1) drove uptake of both PO4 3- and a Mg2+ counter-ion leading to increased PolyP granule size, raising P levels 4-fold to 8% dry cell weight, and accelerated removal of PO4 3- from the medium. Examination of the gene expression profile showed that the P-starvation response was mimicked under P-replete conditions, switching on luxury uptake. Hyper-accumulation of P depended on a feed-forward mechanism, where a small set of 'Class I' P-transporter genes were activated despite abundant external PO4 3- levels. The transporters drove a reduction in external PO4 3- levels, permitting more genes to be expressed (Class II), leading to more P-uptake. Our data pointed toward a PSR1-independent mechanism for detection of external PO4 3- which suppressed Class II genes. This model provided a plausible mechanism for P-overplus where prior P-starvation elevates PSR1 and on P-resupply causes luxury P-uptake. This is because the Class I genes, which include P-transporter genes, are not suppressed by the excess PO4 3-. Taken together, these discoveries facilitate a bio-circular approach of recycling nutrients from wastewater back to agriculture.

Sustainable production and pharmaceutical applications of ß-glucan from microbial sources.

ß-glucans are a large class of complex polysaccharides found in abundant sources. Our dietary sources of ß-glucans are cereals that include oats and barley, and non-cereal sources can consist of mushrooms, microalgae, bacteria, and seaweeds. There is substantial clinical interest in ß-glucans; as they can be used for a variety of diseases including cancer and cardiovascular conditions. Suitable sources of ß-glucans for biopharmaceutical applications include bacteria, microalgae, mycelium, and yeast. Environmental factors including culture medium can influence the biomass and ultimately ß-glucan content. Therefore, cultivation conditions for the above organisms can be controlled for sustainable enhanced production of ß-glucans. This review discusses the various sources of ß-glucans and their cultivation conditions that may be optimised to exploit sustainable production. Finally, this article discusses the immune-modulatory potential of ß-glucans from these sources.

Comprehensive Analysis of Fatty Acid and Oxylipin Patterns in n3-PUFA Supplements.

Supplementing long-chain omega-3 polyunsaturated fatty acids (n3-PUFA) improves health. We characterized the pattern of total and non-esterified oxylipins and fatty acids in n3 supplements made of fish, krill, or micro-algae oil by LC-MS. All supplements contained the declared amount of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA); however, their content per capsule and the concentration of other fatty acids varied strongly. Krill oil contained the highest total n3 oxylipin concentration (6000 nmol/g) and the highest degree of oxidation (EPA 0.7%; DHA 1.3%), while micro-algae oil (Schizochytrium sp.) showed the lowest oxidation (<0.09%). These oils contain specifically high amounts of the terminal hydroxylation product of EPA (20-HEPE, 300 nmol/g) and DHA (22-HDHA, 200 nmol/g), which can serve as an authenticity marker for micro-algae oil. Refined micro-algae and fish oil were characterized by NEFA levels of ≤0.1%. Overall, the oxylipin and fatty acid pattern allows gaining new insights into the origin and quality of n3-PUFA oils in supplements.

Effect of micro-algae Schizochytrium sp. supplementation in plant diet on reproduction of female rainbow trout (Oncorhynchus mykiss): maternal programming impact of progeny.

BACKGROUND: The broodstock diet, and in particular the lipid and fatty acid composition of the diet, is known to play a key role in reproductive efficiency and survival of the progeny in fish. A major problem when replacing both fish meal and fish oil by plant sources is the lack of n-3 long chain polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). To address this problem, we studied the effect of the plant-based diet supplemented with Schizochytrium sp. microalgae, source of DHA, compared to a conventional commercial diet rich in fish meal and fish oil on reproductive performance and egg quality and the consequences on progeny, in female rainbow trout broodstock. RESULTS: The results demonstrated that DHA-rich microalgae supplementation in a plant-based diet allowed for the maintenance of reproductive performance and egg quality comparable to a conventional commercial feed rich in fish meal and fish oil and led to an increased significant fry survival after resorption. Moreover, when females were fed a plant-based diet supplemented with micro-algae, the 4-month-old progenies showed a significant higher growth when they were challenged with a similar diet as broodstock during 1 month. We provide evidence for metabolic programming in which the maternal dietary induced significant protracted effects on lipid metabolism of progeny. CONCLUSIONS: The present study demonstrates that supplementation of a plant-based diet with DHA-rich microalgae can be an effective alternative to fish meal and fish oil in rainbow trout broodstock aquafeed.

Scope for growth and dietary needs of Mediteranean Pinnids maintained in captivity.

BACKGROUND: The measurement of the energy available for growth (scope of growth, SFG) can be used in bivalves to make a long-term prediction in a short-term experiment of the condition of the individual. In order to tackle the best conditions for captive maintenance of Mediterranean Pinnids, a SFG study was conducted using Pinna rudis as a model species. Three diets were examined to test the viability of live microalgae and commercial products: i) a control diet using 100% of live microalgae based on the species Isochrysis galbana (t-ISO), ii) a 100% of commercial microalgae diet based on the product Shellfish Diet 1800®, and iii) a 50/50% mix diet of I. galbana (t-ISO) and Shellfish Diet 1800®. RESULTS: SFG results showed significant differences among diets in the physiological functions measured and suggested lower acceptability and digestibility of the commercial product. Negative SFG values were obtained for the commercial diet which indicates that it should be rejected for both Pinnid maintenance. The mixed diet showed improved physiological performance compared to the commercial diet, resulting in a higher SFG that had no significant differences with the control diet. However, in the long-term, the lower digestibility of the mixed diet compared to the control diet could lead to a deterioration of individuals' conditions and should be considered cautiously. CONCLUSIONS: This work represents the first case study of SFG in Pinna spp. and provides fundamental data on dietary needs for the critically endangered species, P. nobilis.

Nutritional Profiling and Preliminary Bioactivity Screening of Five Micro-Algae Strains Cultivated in Northwest Europe.

This study aimed to map the nutritional profile and bioactivities of five microalgae that can be grown in Northwest Europe or areas with similar cultivation conditions. Next to the biochemical composition, the in vitro digestibility of carbohydrates, proteins, and lipids was studied for Chlamydomonas nivalis, Porphyridium purpureum, Chlorella vulgaris, Nannochloropsis gaditana, and Scenedesmus species biomass. These microalgae were also assessed for their ability to inhibit the angiotensin-1-converting enzyme (ACE-1, EC 3.4.15.1), which is known to play a role in the control of blood pressure in mammals. Large differences in organic matter solubility after digestion suggested that a cell disruption step is needed to unlock the majority of the nutrients from N. gaditana and Scenedesmus species biomass. Significant amounts of free glucose (16.4-25.5 g glucose/100 g dry algae) were detected after the digestion of C. nivalis, P. purpureum, and disrupted Scenedesmus. The fatty acid profiles showed major variations, with particularly high Ω-3 fatty acid levels found in N. gaditana (5.5 ± 0.5 g/100 g dry algae), while lipid digestibility ranged from 33.3 ± 6.5% (disrupted N. gaditana) to 67.1 ± 11.2% (P. purpureum). C. vulgaris and disrupted N. gaditana had the highest protein content (45-46% of dry matter), a nitrogen solubility after digestion of 65-71%, and the degree of protein hydrolysis was determined as 31% and 26%, respectively. Microalgae inhibited ACE-1 by 73.4-87.1% at physiologically relevant concentrations compared to a commercial control. These data can assist algae growers and processors in selecting the most suitable algae species for food or feed applications.

Integrating micro-algae into wastewater treatment: A review.

Improving the ecological status of water sources is a growing focus for many developed and developing nations, in particular with reducing nitrogen and phosphorus in wastewater effluent. In recent years, mixotrophic micro-algae have received increased interest in implementing them as part of wastewater treatment. This is based on their ability to utilise organic and inorganic carbon, as well as inorganic nitrogen (N) and phosphorous (P) in wastewater for their growth, with the desired results of a reduction in the concentration of these substances in the water. The aim of this review is to provide a critical account of micro-algae as an important step in wastewater treatment for enhancing the reduction of N, P and the chemical oxygen demand (COD) in wastewater, whilst utilising a fraction of the energy demand of conventional biological treatment systems. Here, we begin with an overview of the various steps in the treatment process, followed by a review of the cellular and metabolic mechanisms that micro-algae use to reduce N, P and COD of wastewater with identification of when the process may potentially be most effective. We also describe the various abiotic and biotic factors influencing micro-algae wastewater treatment, together with a review of bioreactor configuration and design. Furthermore, a detailed overview is provided of the current state-of-the-art in the use of micro-algae in wastewater treatment.

Taxon- and Growth Phase-Specific Antioxidant Production by Chlorophyte, Bacillariophyte, and Haptophyte Strains Isolated From Tropical Waters.

Antioxidants found in microalgae play an essential role in both animals and humans, against various diseases and aging processes by protecting cells from oxidative damage. In this study, 26 indigenous tropical marine microalgae were screened. Out of the 26 screened strains, 10 were selected and were further investigated for their natural antioxidant compounds which include carotenoids, phenolics, and fatty acids collected in their exponential and stationary phases. The antioxidant capacity was also evaluated by a total of four assays, which include ABTS, DPPH, superoxide radical (O2 •-) scavenging capacity, and nitric oxide (•NO-) scavenging capacity. This study revealed that the antioxidant capacity of the microalgae varied between divisions, strains, and growth phase and was also related to the content of antioxidant compounds present in the cells. Carotenoids and phenolics were found to be the major contributors to the antioxidant capacity, followed by polyunsaturated fatty acids linoleic acid (LA), eicosapentaenoic acid (EPA), arachidonic acid (ARA), and docosahexaenoic acid (DHA) compared to other fatty acids. The antioxidant capacity of the selected bacillariophytes and haptophytes was found to be positively correlated to phenolic (R 2-value = 0.623, 0.714, and 0.786 with ABTS, DPPH, and •NO-) under exponential phase, and to carotenoid fucoxanthin and ß-carotene (R2 value = 0.530, 0.581 with ABTS, and 0.710, 0.795 with O2 •-) under stationary phase. Meanwhile, antioxidant capacity of chlorophyte strains was positively correlated with lutein, ß-carotene and zeaxanthin under the exponential phase (R2 value = 0.615, 0.615, 0.507 with ABTS, and R2 value = 0.794, 0.659, and 0.509 with •NO-). In the stationary phase, chlorophyte strains were positively correlated with violaxanthin (0.755 with •NO-), neoxanthin (0.623 with DPPH, 0.610 with •NO-), and lutein (0.582 with •NO-). This study showed that antioxidant capacity and related antioxidant compound production of tropical microalgae strains are growth phase-dependent. The results can be used to improve the microalgal antioxidant compound production for application in pharmaceutical, nutraceutical, food, and feed industry.

Hydrocarbon-Degrading Bacteria Found Tightly Associated with the 50-70 µm Cell-Size Population of Eukaryotic Phytoplankton in Surface Waters of a Northeast Atlantic Region.

The surface of marine eukaryotic phytoplankton can harbour communities of hydrocarbon-degrading bacteria; however, this algal-bacterial association has, hitherto, been only examined with non-axenic laboratory cultures of micro-algae. In this study, we isolated an operationally-defined community of phytoplankton, of cell size 50-70 µm, from a natural community in sea surface waters of a subarctic region in the northeast Atlantic. Using MiSeq 16S rRNA sequencing, we identified several recognized (Alcanivorax, Marinobacter, Oleispira, Porticoccus, Thalassospira) and putative hydrocarbon degraders (Colwelliaceae, Vibrionaceae) tightly associated with the phytoplankton population. We combined fluorescence in situ hybridisation with flow-cytometry (FISH-Flow) to examine the association of Marinobacter with this natural eukaryotic phytoplankton population. About 1.5% of the phytoplankton population contained tightly associated Marinobacter. The remaining Marinobacter population were loosely associated with either eukaryotic phytoplankton cells or non-chlorophyll particulate material. This work is the first to show the presence of obligate, generalist and putative hydrocarbonoclastic bacteria associated with natural populations of eukaryotic phytoplankton directly from sea surface water samples. It also highlights the suitability of FISH-Flow for future studies to examine the spatial and temporal structure and dynamics of these and other algal-bacterial associations in natural seawater samples.

Iron Uptake Mechanisms in Marine Phytoplankton.

Oceanic phytoplankton species have highly efficient mechanisms of iron acquisition, as they can take up iron from environments in which it is present at subnanomolar concentrations. In eukaryotes, three main models were proposed for iron transport into the cells by first studying the kinetics of iron uptake in different algal species and then, more recently, by using modern biological techniques on the model diatom Phaeodactylum tricornutum. In the first model, the rate of uptake is dependent on the concentration of unchelated Fe species, and is thus limited thermodynamically. Iron is transported by endocytosis after carbonate-dependent binding of Fe(III)' (inorganic soluble ferric species) to phytotransferrin at the cell surface. In this strategy the cells are able to take up iron from very low iron concentration. In an alternative model, kinetically limited for iron acquisition, the extracellular reduction of all iron species (including Fe') is a prerequisite for iron acquisition. This strategy allows the cells to take up iron from a great variety of ferric species. In a third model, hydroxamate siderophores can be transported by endocytosis (dependent on ISIP1) after binding to the FBP1 protein, and iron is released from the siderophores by FRE2-dependent reduction. In prokaryotes, one mechanism of iron uptake is based on the use of siderophores excreted by the cells. Iron-loaded siderophores are transported across the cell outer membrane via a TonB-dependent transporter (TBDT), and are then transported into the cells by an ABC transporter. Open ocean cyanobacteria do not excrete siderophores but can probably use siderophores produced by other organisms. In an alternative model, inorganic ferric species are transported through the outer membrane by TBDT or by porins, and are taken up by the ABC transporter system FutABC. Alternatively, ferric iron of the periplasmic space can be reduced by the alternative respiratory terminal oxidase (ARTO) and the ferrous ions can be transported by divalent metal transporters (FeoB or ZIP). After reoxidation, iron can be taken up by the high-affinity permease Ftr1.

Microphytobenthos diversity and community structure across different micro-estuaries and micro-outlets: Effects of environmental variables on community structure.

This study forms the first basic assessment of microphytobenthos (MPB) dynamics in micro-estuaries and micro-outlets in southern Africa. It examines MPB community responses to environmental variables and further investigates MPB composition qualitatively across different micro-estuaries and micro-outlets over four seasons in a warm temperate region of the subcontinent. Combinations of multivariate analyses were used to explore similarities and differences in MPB communities between systems. Human-induced catchment changes between microsystems ranged from no alteration (rating 0; mostly micro-outlets) to extreme modification (rating 5; mostly micro-estuaries). Two hundred and sixty-seven MPB taxa were identified within all the microsystems, with 247 and 230 MPB taxa being observed in the micro-estuaries and micro-outlets, respectively. The MPB communities differed slightly in terms of microsystem types and seasons, but no significant differences were observed. Multivariate analyses (i.e. Boosted Regression Trees, Canonical Correspondence Analysis) showed that water column variables were significant and important in structuring MPB communities, with soluble reactive phosphorus, sediment pH, turbidity, ammonium and temperature being documented as key drivers. The MPB community composition clearly reflected the influence of catchment anthropogenic activities on species composition and structure. Moderately modified catchments resulted in MPB community structure variation among water bodies in relationship to land use and salinity gradients. The study found that; (i) by virtue of their size, microsystems and their catchments are likely to be particularly vulnerable to anthropogenic pressures when compared to systems of larger size; (ii) a typical impacted state may reflect reduced environmental heterogeneity which, compared to larger systems, may be achieved over much shorter time periods (following a particular event) or under much less intensive impacts; and (iii) the response in terms of MPB structure may predictably reflect a concomitant change from a complex community dynamic (structure and spatio-temporal attributes) to one that approaches a homogeneous structure (poor spatial zonation, strong taxonomic dominance, low species diversity).

Soybean dreg pre-digested by enzymes can effectively replace part of the fishmeal included in feed pellets for rearing gold-lined seabream.

The present study aimed to formulate diets using soybean dreg to replace part of fish meal (30% and 60%) and to incorporate dietary supplement to the diets with papain to promote fish growth and decrease total cost of feed formulations for gold-lined seabream (Rhabdosargus sarba). In Experiment 1, papain was used to supplement feeds containing soybean dreg to replace part of the fish meal. In Experiment 2, bromelain and a microalgae supplement were used to supplement feeds containing soybean substitutes as a replacement of the fish meal. Results from Experiment 1 indicated that the growth performance of fish fed diets with up to 60% replacement of fishmeal with soybean residues predigested with papain were not significantly different (p > 0.05) from the control (a formula developed by Agriculture, Fisheries and Conservation Department (AFCD), which contained 49.4% fishmeal, 45.2% raw trashfish, 4.9% alpha starch and 0.5% vitamin premix). It indicated that plant protein predigested with a small amount of enzyme supplement (e.g. papain) can be used to replace fish meal in traditional fish diets, and the cost could subsequebtly be reduced. In Experiment 2, the diets containing bromelain, soybean dreg pre-digested with bromelain and supplemented with microalgae resulted in significantly better growth performance than other diet groups. Results from the present study suggested that predigesting soybean dreg with enzymes could replace up to 60% fishmeal in the moist pellets while achieving economic benefits.

Preference and willingness to pay for meat substitutes based on micro-algae.

Current meat consumption and production patterns are far from sustainable and place a heavy burden on the environment. Excessive meat consumption is also considered detrimental to consumer health. Hence, more consumers are willing to opt for meat substitutes to counteract these downsides of excessive meat consumption. However, in many Western countries, market shares for meat substitutes still have to increase significantly if they are to support responsible consumption and production. Consequently, more research is needed to take a closer look at consumer preferences for meat substitutes. This study aims to fill this research gap by analyzing consumer preferences for meat substitutes based on micro-algae. First, a choice-based conjoint analysis was conducted in three Western European countries (Germany, Netherlands, France) to reveal consumer preferences and willingness to pay for meat substitutes based on micro-algae. Second, a multi-item scale was developed to measure consumer attitudes toward meat and meat substitutes. Third, these results were combined to obtain novel insights about attitudinal drivers of consumer preference and willingness to pay for meat substitutes based on micro-algae. In summary, findings from this study provide important insights for food engineers, food marketers, and policy makers when it comes to product development and increasing market shares for meat substitutes based on micro-algae.

Transcriptional response of cultured porcine intestinal epithelial cells to micro algae extracts in the presence and absence of enterotoxigenic Escherichia coli.

BACKGROUND: Micro algae's are worldwide considered as an alternative source of proteins in diets for animals and humans. Micro algae also produce an array of biological active substances with potential to induce beneficial and health promoting effects. To better understand the mode of action of micro algae's when applied as additive in diets, porcine intestinal epithelial cells (IPEC-J2), stressed by enterotoxigenic Escherichia coli (ETEC) or under non-stressed conditions, were exposed to micro algae extracts and changes in gene expression were recorded. METHODS: IPEC-J2 cells were exposed for 2 and 6 h to extracts prepared from the biomass of the microalgae Chlorella vulgaris (C), Haematococcus pluvialis (H), Spirulina platensis (S), or a mixture of Scenedesmus obliques and Chlorella sorokiniana (AM), in the absence and presence of ETEC. Gene expression in cells was measured using porcine "whole genome" microarrays. RESULTS: The micro algae extracts alone enhanced the expression of a set of genes coding for proteins with biological activity that are secreted from cells. These secreted proteins (hereafter denoted as effector proteins; EPs) may regulate processes like remodelling of the extracellular matrix, activation of an antiviral/bacterial response and oxygen homeostasis in the intestine and periphery. Elevated gene expression of immunostimulatory proteins CCL17, CXCL2, CXCL8 (alias IL8), IFNA, IFNL1, HMOX1, ITGB3, and THBS1 was observed in response to all four extracts in the absence or presence of ETEC. For several of these immunostimulatory proteins no elevated expression was observed when cells were exposed to ETEC alone. Furthermore, all extracts highly stimulated expression of an antisense RNA of the mitochondrial/peroxisome symporter SLC25A21 gene in ETEC-challenged cells. Inhibition of SLC25A21 translation by this antisense RNA may impose a concentration gradient of 2-oxoadipic and 2-oxoglutarate, both metabolites of fatty acid ß-oxidation, between the cytoplasm and the interior of these organelles. CONCLUSIONS: Exposure of by ETEC stressed intestinal epithelium cells to micro algae extracts affected "fatty acid ß-oxidation", ATP and reactive oxygen species production and (de) hydroxylation of lysine residues in procollagen chains in these cells. Elevated gene expression of specific EPs and immunostimulatory proteins indicated that micro algae extracts, when used as feed/food additive, can steer an array of metabolic and immunological processes in the intestines of humans and monogastric animals stressed by an enteric bacterial pathogen.

Microalgae in modern cancer therapy: Current knowledge.

Cancer is an everyday medical concern which requires an appropriate treatment strategy. The malfunction of cell cycle is a well-established cause for cancer induction. Chemotherapy and radiation are the standard available therapeutic approach for cancer treatment; however severe side effects were reported in association to such treatments, for instance, the efficacy of patients' immune system is adversely affected in apart by radiation. These side effects may be minimized by providing novel remedial preparations. Complementary and alternative medicinal compounds, which were obtained from fresh or marine flora particularly micro and macro algae, were reported to its anti-cancerous activities. Several types of bioactive molecules are also present in microalgae, such as carotenoids, various forms of polysaccharides, vitamins, sterol, fibres, minerals…ect; the great unused biomass of microalgae and their excellent diversity of chemical constituents may introduce a major step in developing of anti-malignant drugs. Previously, such characteristic of microalgal bio-diversity was commercially exploited to make food supplements and gelling substances. However, recently, several investigations were designed to study the potential anti-carcinogenic effect of microalgal extracts, where they mostly concluded their ability to induce apoptotic cancer cell death via caspase dependent or independent pathways. In this review paper, we reported the various species of microalgae that possessed anti-tumor activity, the tumor cell lines altered through using microalgal extracts along with the levels of such extracts that reported to its inhibitor effect against cell cycle and proliferation.

Visualisation of the obligate hydrocarbonoclastic bacteria Polycyclovorans algicola and Algiphilus aromaticivorans in co-cultures with micro-algae by CARD-FISH.

Some studies have described the isolation and 16S rRNA gene sequence-based identification of hydrocarbon-degrading bacteria living associated with marine eukaryotic phytoplankton, and thus far the direct visual observation of these bacteria on micro-algal cell surfaces ('phycosphere') has not yet been reported. Here, we developed two new 16S rRNA-targeted oligonucleotide probes, PCY223 and ALGAR209, to respectively detect and enumerate the obligate hydrocarbonoclastic bacteria Polycyclovorans algicola and Algiphilus aromaticivorans by Catalyzed Reporter Deposition Fluorescence in situ Hybridization (CARD-FISH). To enhance the hybridization specificity with the ALGAR209 probe, a competitor probe was developed. These probes were tested and optimized using pure cultures, and then used in enrichment experiments with laboratory cultures of micro-algae exposed to phenanthrene, and with coastal water enriched with crude oil. Microscopic analysis revealed these bacteria are found in culture with the micro-algal cells, some of which were found attached to algal cells, and whose abundance increased after phenanthrene or crude oil enrichment. These new probes are a valuable tool for identifying and studying the ecology of P. algicola and A. aromaticivorans in laboratory and field samples of micro-algae, as well as opening new fields of research that could harness their ability to enhance the bioremediation of contaminated sites.

Potential of diatom consortium developed by nutrient enrichment for biodiesel production and simultaneous nutrient removal from waste water.

Because of the decreasing fossil fuel supply and increasing greenhouse gas (GHG) emissions, microalgae have been identified as a viable and sustainable feedstock for biofuel production. The major effect of the release of wastewater rich in organic compounds has led to the eutrophication of freshwater ecosystems. A combined approach of freshwater diatom cultivation with urban sewage water treatment is a promising solution for nutrient removal and biofuel production. In this study, urban wastewater from eutrophic Hussain Sagar Lake was used to cultivate a diatom algae consortium, and the effects of silica and trace metal enrichment on growth, nutrient removal, and lipid production were evaluated. The nano-silica-based micronutrient mixture Nualgi containing Si, Fe, and metal ions was used to optimize diatom growth. Respectively, N and P reductions of 95.1% and 88.9%, COD and BOD reductions of 91% and 51% with a biomass yield of 122.5 mg L-1 day-1 and lipid productivity of 37 mg L-1 day-1 were observed for cultures grown in waste water using Nualgi. Fatty acid profiles revealed 13 different fatty acids with slight differences in their percentage of dry cell weight (DCW) depending on enrichment level. These results demonstrate the potential of diatom algae grown in wastewater to produce feedstock for renewable biodiesel production. Enhanced carbon and excess nutrient utilization makes diatoms ideal candidates for co-processes such as CO2 sequestration, biodiesel production, and wastewater phycoremediation.