Porphyridium Cruentum Research Articles

Role of some structural features in EPS from microalgae stimulating collagen production by human dermal fibroblasts

ABSTRACTExopolysaccharides (EPS) from the microalgae Porphyridium cruentum, Chrysotila dentata, Pavlova sp., Diacronema sp., Glossomastix sp., Phaeodactylum tricornutum, and Synechococcus sp. were isolated and depolymerized. First, EPS were submitted to a high pressure pre-treatment step, followed by a solid acid-catalyzed hydrolysis step carried out in a batch or recycle fixed-bed reactor, using a strong acidic cation-exchange resin. Twenty-eight different EPS forms were thus obtained. After characterization of their main structural features (weight- and number-averaged molecular weight, polydispersity index, sulfate and uronic acid contents), we investigated the structure–function relationship of their pro-collagen activity. We found that native microalgae EPS were able to inhibit until 27% of human matrix metalloproteinase-1 (MMP-1) activity while the depolymerized forms were able to enhance collagen production by two different human fibroblast lines, used as cell models due to their major role in dermal collagen biosynthesis. The most active EPS forms, obtained by depolymerization in the recycle fixed-bed reactor of D. ennorea and Glossomastix sp. EPS, led to 390% increase in collagen production. Finally, principal component (PCA) and Pearson analyses indicated that MMP-1 inhibition was strongly correlated to the sulfate group content of EPS whereas collagen production by fibroblasts was mostly related to their proportion of low molecular weight polysaccharides (<10 kDa). Uronic acid content of EPS was also shown essential but only if the size of EPS was reduced in the first place. Altogether, these results gave new insights of the dermo-cosmetic potential of microalgae EPS as well as the key parameters of their activity.

The reproductive potential of Artemia franciscana fed with different concentrations mixed diet with Porphyridium cruentum and Pinnularia sp. in laboratory

The reproductive potential of Artemia franciscana fed with different concentrations mixed diet with Porphyridium cruentum and Pinnularia sp. in laboratory

Effect of Different Concentrations of NaCl on Growth and Biochemical Characteristics of Red Microalga Porphyridium cruentum

The red microalga Porphyridium cruentum is a potential source of valuable biologically active compounds. This microalga is easily cultivated and could change its growth and biochemical composition in response to environmental variations. The effect of growth medium content, especially salinity (15, 20, and 27 gL -1 NaCl) on P. cruentum cell growth, biomass composition, and extracellular polysaccharides production was investigated in this study. The results showed that the highest biomass yield and phycoerythrin content was achieved when NaCl in a concentration of 20 gL -1 was introduced into the culture medium. The measured biomass was equal to 4.3±0.1 gL -1 compared to 3.3±0.1 gL -1 for the control sample at the end of the cultivation process. The amount of chlorophyll „a“ was also 1.33 times greater in the sample with 20 gL -1 NaCl compared to the control sample with 27 gL -1 , where the carotenoid content was higher. The highest amount of extracellular polysaccharide was accumulated by the microalga at 27 gL -1 NaCl. The measured viscosity was 3.35 mPa.sec - 1.4 times more than the sample with 20 gL -1 NaCl. The investigations conveyed lead to the conclusion that with only slight changes in the salt concentration, a targeted biosynthesis could be achieved, nevertheless, all other conditions remained the same. The study provides an opportunity to optimize growth and metabolite production using optimization in the cultivation process of the microalgae.

Alkalicoccobacillus porphyridii sp. nov., isolated from a marine red alga, reclassification of Shouchella plakortidis and Shouchella gibsonii as Alkalicoccobacillus plakortidis comb. nov. and Alkalicoccobacillus gibsonii comb. nov., and emended description of the genus Alkalicoccobacillus Joshi et al. 2022.

A Gram-stain-positive alkali-tolerant and strictly aerobic bacterium, designated strain P16T, was isolated from a marine red alga, Porphyridium cruentum, in the Yellow Sea, Republic of Korea. Cells were motile rods with peritrichous flagella and exhibited catalase and oxidase activities. The optimal growth of strain P16T was observed to occur at 30 °C and pH 8.0 and in the presence of 2.0 % (w/v) NaCl. Menaquinone-7 was identified as the sole respiratory quinone. Strain P16T contained anteiso-C15 : 0, iso-C15 : 0, iso-C14 : 0 and iso-C16 : 0, and diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine as major cellular fatty acids and polar lipids, respectively. The G+C content of strain P16T was 40.8 mol%. Strain P16T was most closely related to Shouchella plakortidis P203T, Shouchella gibsonii DSM 8722T and Alkalicoccobacillus murimartini LMG 21005T with 98.1, 98.1 and 98.0 % 16S rRNA gene sequence similarities, respectively. Phylogenetic analyses based on 16S rRNA gene and genome sequences revealed that strain P16T, S, plakortidis, S. gibsonii and A. murimartini formed a single phylogenetic lineage cluster, and genomic relatedness analyses showed that they are different species. Based on phylogenetic, phenotypic, chemotaxonomic and molecular features, strain P16T represents a novel species of the genus Alkalicoccobacillus, for which the name Alkalicoccobacillus porphyridii sp. nov. is proposed. The type strain is P16T (=KACC 19520T=JCM 32931T). In addition, S. plakortidis and S. gibsonii are reclassified as Alkalicoccobacillus plakortidis comb. nov. (type strain P203T=DSM 19153T=NCIMB 14288T) and Alkalicoccobacillus gibsonii comb. nov. (type strain PN-109T=ATCC 700164T=DSM 8722T=KCCM 41407T), respectively.

Effects of citrate-stabilized gold and silver nanoparticles on some safety parameters of Porphyridium cruentum biomass.

Introduction: Our research raises the question of how realistic and safe it is to use gold and silver nanoparticles in biotechnologies to grow microalgae, which will later be used to obtain valuable products. To this purpose, it was necessary to assess the influence of 10 and 20nm Au and Ag nanoparticles stabilized in citrate on the growth of microalga Porphyridium cruentum in a closed cultivation system, as well as some safety parameters of biomass quality obtained under experimental conditions. Methods: Two types of experiments were conducted with the addition of nanoparticles on the first day and the fifth day of the cultivation cycle. Changes in productivity, lipid content, malondialdehyde (MDA), as well as antioxidant activity of microalgae biomass have been monitored in dynamics during the life cycle in a closed culture system. Results: The impact of nanoparticles on the growth curve of microalgae culture was marked by delaying the onset of the exponential growth phase. A significant increase in the content of lipids and MDA in biomass was noted. Excessive accumulation of lipid oxidation products within the first 24h of cultivation resulted in altered antioxidant activity of red algae extracts. Discussion: Citrate-stabilized gold and silver nanoparticles proved to be a stress factor for red microalga Porphyridium cruentum, causing significant changes in both biotechnological and biomass safety parameters. Addition of Au and Ag nanoparticles during the exponential growth phase of porphyridium culture led to an enhanced lipid accumulation and reduced MDA values in biomass.

Spray-drying optimization for Dunaliella salina and Porphyridium cruentum biomass

In this study, Dunaliella salina and Porphyridium cruentum biomass were encapsulated by using a spray-dryer (SD) and combined D-optimal method. The independent variables were SD inlet temperature (170–190 °C), maltodextrin (25–75%, w/w, in dm), and microalgae biomass (25–75%, w/w, in dm). Prior to spray drying, P. cruentum and D. salina were cultivated in a pilot scale tubular photobioreactor and than harvested using a conical plate centrifuge. Significant models were determined for the effects of independent variables on total carotenoids, chlorophyll-a, crude protein, moisture contents and encapsulation yield (EY), water activity, average particle size, wettability, hygroscopicity, L* and C* properties for both microalgae species (p < .05). Due to the low EY (11.1–33.1%), we recommend encapsulation and drying of P. cruentum biomass with alternative methods to SD. The extracellular, as well as the cell wall and storage polysaccharides released into the culture medium of these microalgae are possible reasons for the low EY.

Tetraselmis suecica and Porphyridium cruentum exopolysaccharides show anti-VHSV activity on RTG-2 cells

The use of functional feed additives is an important approach to both, prevent and fight, viral diseases in aquaculture. In this regard, microalgae-derived products, and, more specifically, microalgal exopolysaccharides (EPSs), have attracted attention, since multiple biotechnological applications are being described for these molecules. Furthermore, depending on culture conditions, the composition and, therefore, properties of EPSs can vary. In the present study, the antiviral activity of EPSs from Tetraselmis suecica and Porphyridium cruentum cultured under autotrophic and heterotrophic conditions has been evaluated in vitro against Viral Haemorrhagic Septicaemia Virus (VHSV), an important pathogen in fish farming. Results showed that EPSs from both species have anti-VHSV activity. T. suecica EPSs from autotrophic cultures showed the strongest effect, since both, adsorption and post-adsorption phases of the VHSV multiplication cycle were affected. In contrast, both, autotrophic and heterotrophic P. cruentum EPSs showed anti-VHSV activity only after the adsorption phase. These results pave the way to use these EPSs to fight VHSV infections, and animate to evaluate the EPS antiviral activity against other viral pathogens relevant to the aquaculture industry.

Green synthesis of titanium nanoparticles using a sustainable microalgal metabolite solution for potential biotechnological activities

AbstractIn this study, green synthesis of titanium nanoparticles using liquids metabolites of microalgae, Porphyridium cruentum, was performed to evaluate potential biotechnological activity. The rising rates of multidrug‐resistant bacteria and the number of cancer patients are driving the search for novel antimicrobial and anticancer agents to combat this threat. In recent years, with the increasing number of studies, nanomaterials are starting to be better understood and are emerging as a solution to this problem. Especially, green synthesized nanoparticles with anticancer, antioxidant, and antimicrobial activities have potential in biomedical applications because of their eco‐friendly and biocompatible nature. Scanning electron microscopy (SEM) images revealed that spherical shaped Ti‐NPs' size ranged from 62 to 133 nm. This study aimed to assess the effectiveness of antibacterial activity of Ti‐NPs and chitosan‐coated Ti‐NPs against Escherichia coli and Staphylococcus aureus using disc diffusion assay. It demonstrated the concentration‐dependent cytotoxic effect of Ti‐NPs of human prostate adenocarcinoma (PC‐3), human alveolar adenocarcinoma (A549), and human mammary gland adenocarcinoma (MDA‐MB) cancer cell lines. This present study shows promising outcomes for possible future applications of synthesized Ti‐NPs as a novel antibacterial and cytotoxic agent for biomedical applications such as drug delivery, biosensor, and hyperthermia.

Assessment of the SPF and Anti-Irritating Properties of Sunscreen designed for Retinol users

Vitamin A and its derivatives, also known as retinoids, when applied topically for anti-ageing benefits, typically cause erythema and dryness on the skin, which are considered significant and common side effects. Furthermore, users of topical retinoids, like everyone else, need a sunscreen that protects the skin from harmful sun exposure while simultaneously countering the erythema and dryness of the skin. Retinoids also enhance the rate of skin cell turnover and expose newly produced skin to solar exposure, increasing the risk of sun damage and hyperpigmentation. Since the skin becomes sensitive with topical retinoids, a sunscreen must possess the further benefit of elevated skin resilience, which is much needed with conventional sun protection. ‘‘EI Pro Retinol Sunscreen’’ came up with a new innovative sunscreen with UV protectants and other active ingredients that have calming and soothing properties that minimize erythema and dryness. EI launched the “EI PRO Retinol series,” which includes the “EI PRO Retinol Sunscreen,” to protect the skin from the detrimental effects of ultraviolet rays as well as further irritation and itching caused by retinoid actions on the skin. In this study, researchers attempted to develop and design a sunscreen using a patented sunscreen agent (a combination of water, ethylhexyl methoxy-cinnamate, butyl methoxy-dibenzoyl-methane, benzophenone-3, phospholipids, and 1,3-butylene glycol) and Porphyridium cruentum (marine algae) for skin resilience, antioxidants like ascorbic acid, vitamin E, and soothing agents like carrot seed oil and sodium hyaluronate. Sunscreens are evaluated based on their sun protection factor (SPF), PA rating, and critical wavelength. Usually, sunscreens with an SPF above 50, a PA rating of ++++, and a critical wavelength over 370 nm would offer higher sun protection and block both UVA and UVB rays. The results showed that “EI PRO Retinol Sunscreen” has a critical wavelength of 376.67 and is considered a broad-spectrum SPF 50 PA++++ sunscreen. Thus, ‘‘EI PRO Retinol Sunscreen’’ is also proven to be safe on the skin without irritation, and it is proven to be non-irritant by a single, blinded patch test method.&#x0D;

Antiviral activity of red algae phycocolloids against herpes simplex virus type 2 in vitro

Herpes simplex virus type 2 (HSV-2) is a human infectious agent with significant impact on public health due to its high prevalence in the population and its ability to elicit a wide range of diseases, from mild to severe. Although several antiviral drugs, such as acyclovir, are currently available to treat HSV-2-related clinical manifestations, their effectiveness is poor. Therefore, the identification and development of new antiviral drugs against HSV-2 is necessary. Seaweeds are attractive candidates for such purposes because they are a vast source of natural products due to their highly diverse compounds, many with demonstrated biological activity. In this study, we evaluated the in vitro antiviral potential of red algae extracts obtained from Agarophyton chilense, Mazzaella laminarioides, Porphyridium cruentum, and Porphyridium purpureum against HSV-2. The phycocolloids agar and carrageenan obtained from the macroalgae dry biomass of A. chilense and M. laminarioides and the exopolysaccharides from P. cruentum and P. purpureum were evaluated. The cytotoxicity of these extracts and the surpluses obtained in the extraction process of the agar and carrageenans were evaluated in human epithelial cells (HeLa cells) in addition to their antiviral activity against HSV-2, which were used to calculate selectivity indexes (SIs). Several compounds displayed antiviral activity against HSV-2, but carrageenans were not considered as a potential antiviral therapeutic agent when compared to the other algae extracts with a SI of 23.3. Future assays in vivo models for HSV-2 infection should reveal the therapeutic potential of these algae compounds as new antivirals against this virus.

Effects of the salinity on the biosynthesis of the polysaccharides of the marine microalgae Porphyridium cruentum

The effects of the cultivation medium salinity on the PolySaccharides (PS) production by the red microalgae Porphyridium cruentum was deeply investigated in this study. An original experimental strategy using a system of mini photobioreactors run in parallel was developed for that purpose. It allowed to study the impact of the medium salinity on the main polysaccharide fractions of Porphyridium cruentum, i.e. the floridean starch, the Bound and Released PolySaccharides (BPS and RPS) (i.e. ExoPolySaccharides or EPS) including also the intracellular Low Weight Carbohydrates (LWC). It was demonstrated that the microalgae can grow in a wide range of salinity levels, with an optimal value of c.a. 25 g·L−1 for a maximal productivity of 0.22 g DW·L−1·d−1. This was associated to a maximum of productivity for the EPS fraction (c.a. 45 mg BPS·L−1·d−1, and c.a. 10 mg RPS·L−1·d−1). The BPS followed the biomass modulation tendency, whereas the RPS remained almost at constant values. The other PS fractions, i.e. the starch and the LWC, with its major identified component the floridoside (a compatible solute) followed opposite modulation scheme with a point of convergence situated at the optimal EPS productivity value. The higher the salinity, the higher the low weight carbohydrates accumulation (18.63 %DW, compared to only 4 %DW for the lowest salinity level), mainly due to the accumulation of the floridoside. The lower the salinity, the higher the starch accumulation (15 %DW). Our results suggested interesting metabolic regulations occurring during the medium salinity modulation. It was hypothesized that the salinity was able to trigger specific biosynthetic pathways for the precursors (with a bascule between starch and floridoside depending of the osmolarity of the medium) of the EPS of Porphyridium cruentum.

Resilience and bioresponse of two marine algae to petroleum fuel pollution

ABSTRACT Petroleum pollution can upset the ecological stability and health of a marine ecosystem. The physiological, biochemical and morphological responses of Nannochloropsis oculata and Porphyridium cruentum to three different petroleum fuels, kerosene, diesel and gasoline were examined. The effect of water soluble fractions (WSFs) of the three petroleum fuels was investigated at 0%, 25%, 50% and 100%. The growth response of both species was monitored optically every two days for 14 days using a 721 visible spectrophotometer. Chlorophyll a, morphology and antioxidant enzyme activity of the algae were examined using prescribed methods. In both algae, minimum growth was obtained with 100% WSF of the petroleum fuels. In N. oculata, there was growth stimulation and the maximum growth was obtained at different concentrations (25% and 50%) depending on the test fuels. The maximum growth of P. cruentum was obtained at 10% WSF in all the fuels. ANOVA (p < 0.05) showed significant differences in algal growth with changes in concentration of the test fuels. Unpaired t-tests showed that in all the fuels, there was a significant difference (p < 0.05) between the growth of N. oculata and P. cruentum. N. oculata showed more tolerance to petroleum fuel pollution than P. cruentum. Morphological studies showed that petroleum fuel pollution altered the size of N. oculata and caused severe cell clumping in P. cruentum. Antioxidant concentration assessment showed that whereas N. oculata produced high levels of superoxide dismutase, catalase and peroxidase, P. cruentum produced high levels of superoxide dismutase but was less efficient in catalase and peroxidase production. Clumping and inefficiency in antioxidant production affect the physiological and biochemical response of algae. This study showed that the severity of petroleum fuel pollution is reflected in physiological, morphological, and biochemical responses of the test algae. This research provides baseline information that can be used for the evaluation of the effect of petroleum fuel pollution in marine environment and policy making.

Erythroprotective Potential of Phycobiliproteins Extracted from Porphyridium cruentum.

There are multiple associations between the different blood groups (ABO and RhD) and the incidence of oxidative stress-related diseases, such as certain carcinomas and COVID-19. Bioactive compounds represent an alternative to its prevention and treatment. Phycobiliproteins (PBP) are bioactive compounds present in the microalga Porphyridium cruentum and, despite its antioxidant activity, their inhibitory effect on hemolysis has not been reported. The aim of this work was to evaluate the erythroprotective potential of phycobiliproteins from P. cruentum in different blood groups. The microalga was cultured in F/2 medium under controlled laboratory conditions. Day 10 of culture was determined as the harvest point. The microalgal biomass was lyophilized and a methanolic (MetOH), Tris HCl (T-HCl), and a physiological solution (PS) ultrasound-assisted extraction were performed. Extract pigments were quantified by spectrophotometry. The antioxidant activity of the extracts was evaluated with the ABTS+•, DPPH•, and FRAP methods, finding that the main antioxidant mechanism on the aqueous extracts was HAT (hydrogen atom transfer), while for MetOH it was SET (single electron transfer). The results of the AAPH, hypotonicity, and heat-induced hemolysis revealed a probable relationship between the different antigens (ABO and RhD) with the antihemolytic effect, highlighting the importance of bio-directed drugs.

Structural characterization of exopolysaccharides obtained from Porphyridium cruentum exhausted culture medium

Microalgae produce and secrete large quantities of polysaccharides into the culture medium that is discarded when biomass is separated. The main objective of this study was to add value to the exhausted culture medium (ECM) of Porphyridium cruentum through the recovery of extracellular polysaccharides (EPS) by different extracting and purifying methods for the future biotechnological applications. The ECM was submitted to precipitation with cold absolute ethanol, using ultrasound, dialysis, and trichloroacetic acid (TCA) as purification methods. The purification provided a lower yield, with higher carbohydrate content. The TCA purified sample presented up to twice as much total carbohydrates as the non-purified samples, mainly composed of xylose, galactose, and glucose. Scanning Electron Microscopy (SEM) images showed the smooth structure of P. cruentum EPS, in which TCA post-treatment and dialysis allowed obtaining larger and purest particles, being a good candidate for film making. Microalgal polymeric by-products are a sustainable source to recover valuable compounds, and the purification treatment proved to be an important step to valorize this material.

DISCOVR strain pipeline screening – Part I: Maximum specific growth rate as a function of temperature and salinity for 38 candidate microalgae for biofuels production

To identify high productivity strains for microalgal biofuels generation, the maximum specific growth rate of 38 strains was measured as a function of salinity (i.e., 5, 15, and 35 PSU) and temperature (i.e., at 8 temperatures along a linear gradient from ca. 5 to 45 °C) to determine the most suitable growth medium salinity and best growing season, respectively, for outdoor raceway pond cultivation. The following strains were evaluated: Agmenellum quadruplicatum UTEX 2268, Anabaena sp. ATCC 33081, Arthrospira fusiformis UTEX 2721, Arthrospira platensis UTEX 3086, Chlorella vulgaris NREL 4-C12, Chlorella autotrophica CCMP 243, Chlorella sorokiniana DOE1044, Chlorella sorokiniana DOE 1116, Chlorella sorokiniana DOE 1412 (UTEXB3016), Chlorella vulgaris LRB AZ-1201, Chlorococcum littorale UTEX 117, Chlorococcum sp. UTEX-B P7, Chloromonas reticulata CCALA 870, Coelastrella sp. DOE 0202, Cyanobacterium sp. AB1, Micractinium reisseri NREL 14-F2, Microchloropsis gaditana CCMP1894, Microchloropsis salina CCMP 1776, Monoraphidium sp. MONOR1, Monoraphidium minutum 26B-AM, Nannochloropsis oceanica CCAP 849/10, Oscillatoria cf. priestleyi CCMEE 5020.1-1, Picochlorum celeri TG2-WT-CSM/EMRE, Picochlorum oklahomensis CCMP 2329, Picochlorum renovo NREL 39-A8, Picochlorum soloecismus DOE 101, Porphyridium cruentum CCMP 675, Scenedesmus acutus LRB-AP-0401, Scenedesmus obliquus DOE 0152.z, Scenedesmus obliquus UTEX393,Scenedesmus rubescens NREL 46B-D3, Scenedesmus sp. IITRIND2, Stichococcus minor CCMP 819, Stichococcus minutus CCALA 727, Synechococcus elongatus UTEX2973.1, Tetraselmis striata LANL 1001, Tisochrysis lutea CCMP 1324, and Tribonema minus UTEXB3156. For each strain, the identity and the presence of bacterial cohorts was determined using 18S and 16S rDNA sequencing, respectively. The maximum specific growth rate versus temperature data were also used to determine the activation energies (Arrhenius equation) for most strains. For all strains, the measured salinity and temperature tolerance data were compared to those reported in the literature. The fastest growing strains were down-selected for subsequent biomass productivity measurements in climate-simulation photobioreactors, as reported in the next paper in the issue.

Shedding Light on the Hidden Benefit of Porphyridium cruentum Culture

Microalgae can represent a reliable source of natural compounds with different activities. Here, we evaluated the antioxidant and anti-inflammatory activity of sulfated exopolysaccharides (s-EPSs) and phycoerythrin (PE), two molecules naturally produced by the red marine microalga Porphyridium cruentum (CCALA415). In vitro and cell-based assays were performed to assess the biological activities of these compounds. The s-EPSs, owing to the presence of sulfate groups, showed biocompatibility on immortalized eukaryotic cell lines and a high antioxidant activity on cell-based systems. PE showed powerful antioxidant activity both in vitro and on cell-based systems, but purification is mandatory for its safe use. Finally, both molecules showed anti-inflammatory activity comparable to that of ibuprofen and helped tissue regeneration. Thus, the isolated molecules from microalgae represent an excellent source of antioxidants to be used in different fields.

DISCOVR strain screening pipeline – Part III: Strain evaluation in outdoor raceway ponds

In our previous studies, as described in the corresponding Part I and II manuscripts in this Special issue, we selected 12 promising microalgae strains from 38 strains for high biomass productivity based on their salinity preferences, temperature profiles, and biomass growth under simulated outdoor conditions. The 12 strains include 6 cold season strains (Micractium reisseri NREL14-F2, Monoraphidium minutum 26B-AM, Monoraphidium sp. MONOR1, Chlorella vulgaris LRB-AZ-1201, Tetraselmis striata LANL1001, Phaeodactylum tricornutum UTEX646) and 6 warm seasons strains (Scenedesmus obliquus DOE0152.z, Scenedesmus obliquus UTEX393, Chlorella sorokiniana DOE1116, Picochlorum renovo NREL39-A8, Picochlorum celeri TG2-WT-CSM/EMRE, Porphyridium cruentum CCMP7765). Because the preceding screening efforts were completed in indoor systems, this study focuses on quantitatively assessing these strains in outdoor raceway ponds to further eliminate those perform poorly under outdoor conditions. The trials presented in this study, categorized as either cold or warm season experiments based on water temperature, were carried out between February and June in 2018, 2019 and 2020. For each season, a benchmark strain, M. minutum 26B-AM for the cold season and S. obliquus UTEX393 for the warm season, was grown side-by-side with the new strains to provide a baseline for comparing strains cultivated under different weather conditions. The results showed that the cold season benchmark, M. minutum 26B-AM, remained the most productive cold season strain, but two new strains, P. triconutum UTEX646 and T. striata LANL1001, demonstrated robust growth in the presence of weather changes and biological contaminants. For the warm season trials, P. celeri TG2-WT-CSM/EMRE and P. cruentum CCMP675 were 39 % and 11 % more productive than the benchmark with substantially improved culture stability. Biomass compositional analyses of the strains showed that the carbohydrate, lipid (measured as fatty acid methyl esters) and protein account for 5.2–20.6 %, 7.2–11.9 %, and 21.7–53 %, of the ash-free dry matter, respectively.

Microalgae with immunomodulatory effects on fish

AbstractIn recent decades, microalgal biotechnology has become one of the most valuable sources of functional feed additives. Many microalgae, such as Chlorella sp., Tetraselmis sp., Navicula sp., Phaeodactylum tricornutum, Porphyridium cruentum, Nannochloropsis gaditana, Dunaliella salina, Lobosphaera sp. and Schizochytrium sp., have been considered valuable in fish species as they enhance immunostimulant abilities, resistance against infectious diseases and tolerance to environmental stress. For instance, immunological parameters (i.e., respiratory burst activity, phagocytic capacity and IgM production) and immune‐related gene expression (i.e., proinflammatory cytokines) in fish have been manly analysed, demonstrating modulation upon microalgal administration. Moreover, disease resistance to microbial pathogen challenges has also been evidenced in several studies. In this context, the present literature review aims to assemble and reveal published research about the immunostimulant properties of some microalgae and their compounds in the immune systems of farmed fish species, whether model or new, with a high potential for aquaculture. Overall, it remains unclear how microalgae or their bioactive compounds may induce or modulate signals in the immune systems of fish species; however, the inclusion of different microalgal species in fish feed has improved the immune response and increased survival to stress conditions and infectious challenges.

DISCOVR strain pipeline screening – Part II: Winter and summer season areal productivities and biomass compositional shifts in climate-simulation photobioreactor cultures

Assessing the seasonal biomass productivity and compositional shift dynamics under simulated outdoor culture conditions of the top 21 algae strains selected during Tier I flask screening is an important step in the further prioritization of strains with regard to outdoor pond cultivation.These top 21 strains were subjected to Tier II testing in the PNNL Laboratory Environmental Algae Pond Simulator (LEAPS) photobioreactors, simulating light and temperature conditions of 20 cm deep outdoor ponds during the Arizona winter and summer season. All strains were grown in two consecutive nutrient-replete batch culture experiments at their particular optimal medium salinity to quantify their respective seasonal linear-phase areal biomass productivities. To determine biomass compositional shifts in response to nutrient-depletion, the LEAPS cultures were allowed to enter a 9-day nutrient depletion phase at the end of the second batch run. The following strains were evaluated in winter-season climate-simulated cultures and are listed in the order from highest (7.9 g m−2 day−1) to lowest (2.3 g m−2 day−1) areal N-replete biomass productivity: Monoraphidium minutum 26B-AM, Tetraselmis striata LANL1001, Chlorella vulgaris LRB AZ-1201, Micractinium reisseri NREL14-F2, Monoraphidium sp. MONOR1, Chlorella vulgaris NREL4-C12, Scenedesmus obliquus UTEX393, Scenedesmus acutus LRB-AP-0401, Nannochloropsis oceanica CCAP849/10, and Stichococcus minutus CCALA727. The following strains were evaluated in summer-season climate-simulated cultures and are listed in the order from highest (31.8 g m−2 day−1) to lowest (14.2 g m−2 day−1) areal N-replete biomass productivity: Picochlorum renovo NREL39-A8, Scenedesmus obliquus UTEX393, Porphyridium cruentum CCMP675, Picochlorum celeri TG2-WT-CSM/EMRE, Chlorella sorokiniana DOE1116, Stichococcus minor CCMP819, Picochlorum oklahomensis CCMP2329, Chlorella sorokiniana DOE1412 (UTEXB3016), Scenedesmus rubescens NREL46B-D3, Picochlorum soloecismus DOE101, Tetraselmis striata LANL1001, Scenedesmus obliquus DOE 0152.z, and Agmenellum quadruplicatum UTEX2268. All LEAPS cultures experienced a significant reduction in areal biomass productivity in response to nutrient-depletion, from 7 to 16 % in the winter season simulation and from 1 to 60 % in the summer season simulation. For 10 of the strains tested, the carbohydrate content more than doubled upon nutrient depletion, and for 9 strains, the lipid content increased by over 50 % of the initial content.

Algal Biomass Accumulation in Waste Digestate after Anaerobic Digestion of Wheat Straw

Cultivation of microalgae in waste digestate is a promising cost-effective and environmentally friendly strategy for algal biomass accumulation and valuable product production. Two different digestates obtained as by-products of the anaerobic fermentation at 35 °C and 55 °C of wheat straw as a renewable source for biogas production in laboratory-scale bioreactors were tested as cultivation media for microalgae after pretreatment with active carbon for clarification. The strains of microalgae involved were the red marine microalga Porphyridium cruentum, which reached 4.7 mg/mL dry matter when grown in thermophilic digestate and green freshwater microalga-Scenedesmus acutus, whose growth was the highest—7.3 mg/mL in the mesophilic digestate. During cultivation, algae reduced the available nutrient components in the liquid digestate at the expense of increasing their biomass. This biomass can find further applications in cosmetics, pharmacy, and feed. The nitrogen and phosphorus uptake from both digestates during algae cultivation was monitored and modeled. The results led to the idea of nonlinear dynamic approximations with an exponential character. The purpose was to develop relatively simple nonlinear dynamic models based on available experimental data, as knowing the mechanisms of the considered processes can permit creating protocols for industrial-scale algal production toward obtaining economically valuable products from microalgae grown in organic waste digestate.