C-Phycoerythrin Prevents Chronic Kidney Disease-Induced Systemic Arterial Hypertension, Avoiding Oxidative Stress and Vascular Dysfunction in Remanent Functional Kidney.

Chronic kidney disease (CKD) is a burden in low- and middle-income countries, and a late diagnosis with systemic arterial hypertension (SAH) is the major complication of CKD. C-phycoerythrin (CPE) is a bioactive compound derived from Phormidium persicinum that presents anti-inflammatory and antioxidant effects in vitro and nephroprotective effects in vivo. In the current study, we determine the antihypertensive effect of CPE in a 5/6 nephrectomy-induced CKD model using twenty normotensives male Wistar rats, grouped into four groups (n = 5): sham; sham + CPE; 5/6 nephrectomy (NFx); and NFx + CPE. Treatment started a week post-surgery and continued for five weeks, with weekly hemodynamic evaluations. Following treatment, renal function, oxidative stress, and the expression of vascular dysfunction markers were assessed. The renal function analysis revealed CKD hyperfiltration, and the hemodynamic evaluation showed that SAH developed at the third week. AT1R upregulation and AT2R downregulation together with Mas1/p-Akt/p-eNOS axis were also observed. CPE treatment mitigated renal damage, preserved renal function, and prevented SAH with the modulation of the vasodilative AT1R, AT2R, and Mas1/pAKT/peNOS axis. This result reveals that CPE prevented CKD progression to SAH by avoiding oxidative stress and vascular dysfunction in the kidneys.

Rapid Quantitation of Anatoxins in Benthic Cyanobacterial Mats Using Direct Analysis in Real-Time-High-Resolution Tandem Mass Spectrometry.

Toxic benthic cyanobacterial mats are increasingly reported worldwide as being responsible for animal mortalities due to their production of the potent neurotoxin anatoxin-a (ATX) and its analogues. Improved analytical methods for anatoxins are needed to address public health and watershed management challenges arising from extremely high spatial and temporal variability within impacted systems. We present the development, validation, and application of a direct analysis in real-time-high-resolution tandem mass spectrometry (DART-HRMS/MS) method for analysis of anatoxins in cyanobacterial field samples, including a simplified sample preparation approach. The method showed excellent sensitivity and selectivity for ATX, homoanatoxin-a, and dihydroanatoxin-a. Isotopically labeled ATX was used as an internal standard for all three analogues and successfully corrected for the matrix effects observed (86 ± 16% suppression). The limit of detection and recovery for ATX was estimated as 5 ng/g and 88%, respectively, using spiked samples. The total analysis time was ∼2 min, and excellent agreement was observed with results from a liquid chromatography-HRMS reference method. Finally, the DART-HRMS/MS method was applied to a set of 45 Microcoleus-dominated benthic cyanobacterial mat samples from the Wolastoq near Fredericton, Canada, demonstrating its power and applicability in enabling broad-scale field studies of ATX distribution.

Bioremoval capacity of Co+2 using Phormidium tenue and Chlorella vulgaris as biosorbents.

Microalgae sorbents are microalgae that have the potential to passively bind heavy metals/contaminants to their cellular structures in a process called biosorption. This study investigates the use of two species of microalgae to remove the toxic heavy metal cobalt from aqueous solution. Two microalgae isolates, Phormidium tenue and Chlorella vulgaris, were collected from the Wadi Hanifah Stream in Riyadh, the Kingdom of Saudi Arabia. We determined the capacity of both isolates to bioremove Co+2 ions and the optimum conditions under which this occurs. The two isolates were additionally characterized by microscopic and Fourier transform infrared spectroscopy (FTIR). In the current investigation, Phormidium tenue removed 94% of Co+2 under ideal conditions of pH 6, contact duration (30 min), starting concentration (50 mgL-1) and biosorbent dose (1gL-1); while Chlorella vulgaris removed 87% of Co+2 under the same parameters except pH 5.5 and contact duration (60 min). Fourier transform infrared spectroscopy (FTIR) confirms the binding of Co+2 to the biomass, which comprises many of the functional groups. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed some alterations to the shape of algal cells and cellular components for both microalgae studied. In addition, equilibrium study by both Langmuir and Freundlich models was performed to detect the effect of certain equilibrium factors on the capacity of the biosorption mechanism. Finally, Phormidium tenue and Chlorella vulgaris were discovered to be promising microalgae for effective cobalt biosorption in aquatic conditions.

Unprecedented biodesalination rates-Shortcomings of electrical conductivity measurements in determining salt removal by algae and cyanobacteria.

Phormidium keutzingianum performed biodesalination of brackish water (10 g/L). The electrical conductivity (EC) was measured to evaluate the salt concentration over 80 days of cyanobacterial inoculation. Anion concentrations were measured using ion chromatography to estimate salt removal. EC-based measurements showed ∼8-10% removal efficiency in the first 20 days. However, the removal efficiency based on chloride ion concentration showed ∼40% removal in the same time frame. The pH increase was observed with growth of algal biomass. The increasing pH proposes the formation of hydroxyl and carbonate ions. Sulfuric acid was added at day 110 to neutralize them. At pH 4, the EC reduced significantly to about ∼37% confirming the chloride removal. EC should not be used to measure salt reduction as it is an obscure parameter, and therefore, EC is not the best choice to measure salinity removal using algae. Some recently published studies used only EC to estimate biodesalination, and it is anticipated that salt removal is misrepresented in those studies.

C-phycoerythrin from Phormidium persicinum Prevents Acute Kidney Injury by Attenuating Oxidative and Endoplasmic Reticulum Stress.

C-phycoerythrin (C-PE) is a phycobiliprotein that prevents oxidative stress and cell damage. The aim of this study was to evaluate whether C-PE also counteracts endoplasmic reticulum (ER) stress as a mechanism contributing to its nephroprotective activity. After C-PE was purified from Phormidium persicinum by using size exclusion chromatography, it was characterized by spectrometry and fluorometry. A mouse model of HgCl2-induced acute kidney injury (AKI) was used to assess the effect of C-PE treatment (at 25, 50, or 100 mg/kg of body weight) on oxidative stress, the redox environment, and renal damage. ER stress was examined with the same model and C-PE treatment at 100 mg/kg. C-PE diminished oxidative stress and cell damage in a dose-dependent manner by impeding the decrease in expression of nephrin and podocin normally caused by mercury intoxication. It reduced ER stress by preventing the activation of the inositol-requiring enzyme-1α (IRE1α) pathway and avoiding caspase-mediated cell death, while leaving the expression of protein kinase RNA-like ER kinase (PERK) and activating transcription factor 6α (ATF6α) pathways unmodified. Hence, C-PE exhibited a nephroprotective effect on HgCl2-induced AKI by reducing oxidative stress and ER stress.

Bioseparation of phycocyanin from Phormidium tergestinum using an aqueous two-phase system.

This study aimed at purification of phycocyanin (PC) from Phormidium tergestinum using an aqueous two-phase system (ATPS) comprised of polyethylene glycol (PEG) and salts. The partitioning efficiency of PC in ATPS and the effect of phase composition, pH, crude loading, and neutral salts on purification factor and yield were investigated. Results showed that PC was selectively partitioned toward bottom phase of the system containing potassium phosphate. Under optimum conditions of 20% (w/w) PEG 4000, 10% (w/w) potassium phosphate, 20% (v/v) crude load at pH 7, with addition of 0.5% (w/w) NaCl, PC from P. tergestinum was partially purified up to 5.34-fold with a yield of 87.8%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the molecular weight of PC was ∼19 kDa. Results from this study demonstrated ATPS could be used as a potential approach for the purification of PC from P. tergestinum.

Evaluation of phytotherapeutic activities and phytochemical content of Phormidium autumnale Gomont from natural freshwater sources.

The information available on microalgae-sourced compounds, especially antibiotics and other bioactive compounds, and their potential commercial applications is still insufficient. In this study, antibacterial activity, metabolites, and molecular characterization of Phormidium autumnale, which was isolated from samples collected from different natural freshwater sources in Ankara, Turkey, were investigated. Sequencing results of 16s rDNA confirmed the molecular identification of P. autumnale by 99%. It was determined that the peak values of some phenolic compounds and cyclic peptides were consistent with the 1653-1389 cm-1 band regions in the FTIR spectra of the species. The antibacterial activities of P. autumnale cyanobacteria (CBA) extracts that were obtained by using different solvents were tested on Escherichia coli, Staphylococcus epidermidis, methicillin-resistant (MR) Staphylococcus aureus, Streptococcus agalactiae, and Enterococcus faecalis by using a disc diffusion method. Also, the minimum inhibition concentration (MIC) and antimicrobial indexes of all extracts were determined. It was found that P. autumnale methanol extracts showed antibacterial activity on all test bacteria, whereas acetone extracts showed effects only on E. coli. For the inhibition of MR S. aureus, the control methanol extract was found to give very similar results to those exhibited by the control antibiotics, and the antimicrobial index results were determined to be 58.7-67.5%. According to the results of the analysis of methanol extract, gentisic acid, vanillic acid, 4-hydroxybenzoic acid, p-coumaric acid, and catechin (especially phenolic compounds) were determined to be the active compounds. It can be concluded that P. autumnale is an alternative to current commercial applications as an antibacterial agent in phytotherapy.

Crystal structure analysis of C-phycoerythrin from marine cyanobacterium Phormidium sp. A09DM.

The role of unique sequence features of C-phycoerythrin, isolated from Phormidium sp. A09DM, has been investigated by crystallographic studies. Two conserved indels (i.e. inserts or deletions) are found in the ß-subunit of Phormidium phycoerythrin that are distinctive characteristics of large number of cyanobacterial sequences. The identified signatures are a two-residue deletion from position 21 and a nine-residue insertion at position 146. Crystals of Phormidium phycoerythrin were obtained at pH values of 5 and 8.5, and structures have been resolved to high precision at 1.95 and 2.1 Å resolution, respectively. In both the structures, heterodimers of α- and ß- subunits assemble as hexamers. The 7-residue insertion at position 146 significantly reduces solvent exposure of π-conjugated A-C rings of a phycoerythrobilin (PEB) chromophore, and can influence energy absorption and energy transfer characteristics. The structural analyses (with 12-fold redundancy) suggest that protein micro-environment alone dictates the conformation of bound chromophores. The low- and high-energy absorbing chromophores are identified based on A-B ring coplanarity. The spatial distribution of these is found to be similar to that observed in R-phycoerythrin, suggesting the direction of energy transfer from outer-surface of hexamer to inner-hollow cavity in the Phormidium protein. The crystal structures also reveal that a commonly observed Hydrogen-bonding network in phycobiliproteins, involving chromophore bound to α-subunit and amino acid at position 73 of ß-subunit, may not be essential for structural and functional integrity of C-phycoerythrin orthologs. In solution, the protein displays slight red shift and decrease in fluorescence emission at acidic pH. The mechanism for which may be static and correlates with the proximity of +ve electric field of Arg148 to the C-ring of a PEB chromophore.

Annual Cycles of Two Cyanobacterial Mat Communities in Hydro-Terrestrial Habitats of the High Arctic.

Cyanobacteria form extensive macroscopic mats in shallow freshwater environments in the High Arctic and Antarctic. In these habitats, the communities are exposed to seasonal freezing and desiccation as well as to freeze-thawing and drying-rewetting cycles. Here, we characterized the annual cycles of two Phormidium communities in very shallow seepages located in central Svalbard. We observed the structure of the communities and the morphology, ultrastructure, metabolic activity, and viability of filaments and single cells. The communities overwintered as frozen mats, which were formed by long filaments enclosed in thick multilayered polysaccharide sheaths. No morphologically and/or ultrastructurally distinct spore-like cells were produced for surviving the winter, and the winter survival of the communities was not provided by a few resistant cells, which did not undergo visible morphological and ultrastructural transformations. Instead, a high proportion of cells in samples (85%) remained viable after prolonged freezing. The sheaths were the only morphological adaption, which seemed to protect the trichomes from damage due to freezing and freeze-associated dehydration. The cells in the overwintering communities were not dormant, as all viable cells rapidly resumed respiration after thawing, and their nucleoids were not condensed. During the whole vegetative season, defined by the presence of water in a liquid state, the communities were constantly metabolically active and contained <1% of dead and injured cells. The morphology and ultrastructure of the cells remained unaltered during observations throughout the year, except for light-induced changes in thylakoids. The dissemination events are likely to occur in spring as most of the trichomes were split into short fragments (hormogonia), a substantial proportion of which were released into the environment by gliding out of their sheaths, as well as by cracking and dissolving their sheaths. The short fragments subsequently grew longer and gradually produced new polysaccharide sheaths.

Characterization of sorption sites and differential stress response of microalgae isolates against tannery effluents from ranipet industrial area-An application towards phycoremediation.

Phycoremediation ability of microalgae namely Oscillatoria acuminate and Phormidium irrigum were validated against the heavy metals from tannery effluent of Ranipet industrial area. The microalgae species were cultured in media containing tannery effluent in two different volumes and the parameters like specific growth rate, protein content and antioxidant enzyme activities were estimated. FTIR spectroscopy was carried out to know the sorption sites interaction. The antioxidant enzymes namely superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) contents were increased in microalgae species indicating the free radical scavenging mechanism under heavy metal stress. SOD activity was 0.502 and 0.378 units/gram fresh weight, CAT activity was 1.36 and 0.256 units/gram fresh weight, GSH activity was 1.286 and 1.232 units/gram fresh weight respectively in the effluent treated microalgae species. Bio sorption efficiency for Oscillatoria acuminate and Phormidium irrigum was 90% and 80% respectively. FTIR analysis revealed the interaction of microalgae species with chemical groups present in the tannery effluent. From the results, the microalgae Oscillatoria acuminate possess high antioxidant activity and bio sorption efficiency when compared to Phormidium irrigum and hence considered useful in treating heavy metals contaminated effluents.

Potential of cyanobacterial biofilms in phosphate removal and biomass production.

Four cyanobacterial biofilms, raised from cyanobacterial mats and dominated by Phormidium and Oscillatoria spp., were successfully grown attached to polyester mesh discs, and were tested for their probable application in [Formula: see text] -P removal from domestic sewage and other nutrient enriched wastewaters. Biofilm # 2, dominated by Phormidium fragile, best removed [Formula: see text] -P; nevertheless, some of it also grew outside the substrate making harvesting difficult. Other biofilms also efficiently removed [Formula: see text] -P from the medium in the following order: Biofilm # 1 > Biofilm # 3 > Biofilm # 4. Their growths were restricted to discs and are therefore better candidates as they can be efficiently harvested after [Formula: see text] -P removal. [Formula: see text] -P removal was primarily due to its uptake during growth of the biofilm rather than because of precipitation as pH of the medium remained <8.5. [Formula: see text] -N concentration in the medium determined [Formula: see text] -P removal efficiency of the test biofilms and therefore optimum N:P ratio is necessary for optimizing [Formula: see text] -P removal. The test biofilms could also efficiently remove [Formula: see text] -N from the medium.

Hydrogen Peroxide Stress Induced in the Marine Cyanobacterium Synechococcus aeruginosus and Phormidium valdarianum.

Biochemical markers against hydrogen peroxide-induced oxidative stress were developed in marine cyanobacteria under standard laboratory conditions. To find out the ability to cope with different concentrations of hydrogen peroxide, two species of marine cyanobacteria including unicellular and filamentous forms were exposed for shorter duration. Synechococcus aeruginosus and Phormidium valderianum tolerated hydrogen peroxide by showing the highest growth of Superoxide dismutase in Synechococcus aeruginosus and Phormidium valderianum, catalase in Synechococcus aeruginosus, peroxidase in Synechococcus aeruginosus and Phormidium valderianum, Glutathione S-transferase in Synechococcus aeruginosus and Phormidium valderianum which were identified as biochemical markers of oxidative stress against H2O2 in marine cyanobacteria. Synechococcus aeruginosus showed new isoforms for Superoxide dismutase, catalase, peroxidase, Glutathione peroxidase, and Glutathione S-transferase and Phormidium valderianum for Superoxide dismutase, peroxidase, and Glutathione S-transferase. Synechococcus aeruginosus is suggested as the indicator species for biochemical markers against hydrogen peroxide in marine cyanobacteria. Peroxidase is suggested as biochemical enzyme marker. The present investigated on these new isoenzymes were identified as biochemical markers for oxidative stress.

Corrigendum: The survivor strain: Isolation and characterization of Phormidium yuhuli AB48, a filamentous phototactic cyanobacterium with biotechnological potential.

[This corrects the article DOI: 10.3389/fbioe.2022.932695.].

Stigmasterol- an Acetylcholinesterase Inhibitor from Phormidium retzii with relevance to Alzheimer's disease Therapy.

This study observed in vitro screening, purification and identification of cholinesterase inhibitors from the microalgae Phormidium retzii. Mixed microalgal culture was screened from freshwater samples for Phormidium sp. Single colony was purified and authenticated as P. retzii. Acetylcholinesterase (AChE) enzyme was purified from hRBC ghost. Sequential extraction of P. retzii was performed using organic solvents. Cholinesterase enzyme activity and its inhibition by various extracts were then tested. The active fractions were then subjected to partial purification and characterization. Petroleum ether extract of P. retzii showed maximum inhibition of 68.6 % against AChE while other solvent extracts showed no inhibition. Seven fractions were obtained from the active extract using thin layer chromatography. Among which fraction no. 5 showed maximum inhibition of 86.37 % towards AChE. Fraction no. 5 when subjected to GC-MS led to determination of the active principle as stigmasterol. The maximum inhibition of stigmasterol (0.45µM) was 81.2±0.08% with IC50 value of 0.214. Stigmasterol from P. retzii inhibited AChE projecting itself as safer drug for Alzheimer's disease with minimal side effects.

Characterizing ocean surface contamination: Composition, film thickness, and rheology.

Contamination of the air-sea interface contributes to wave dissipation, which in turn affects the exchange of momentum and energy between the fluids. In this work, the interfacial region between ocean and atmosphere is investigated to determine its composition, vertical extent, and rhelogical behavior. It is found that average thicknesses of interfacial layers on the ocean, such as those resulting from oil spills, could vary from a few hundreds of nanometers to a few millimeters. In addition to oil, interfacial layers also consist of emulsions, plankton, and chemical compounds, and are expected to be non-Newtonian due to their complex composition. To confirm this, fluid samples (mixtures of water-oil emulsions and skimmed off top layer of a month-old Phormidium sp. strain introduced in artificial seawater nutrient medium) that loosely model an interfacial layer are prepared in the laboratory, and their rheological characteristics are investigated using a rheometer. All the samples exhibit shear thinning behavior within the considered ranges for temperature and shear rate. It is recommended that models for wave dissipation account for both the finite thickness of an interfacial fluid layer and its non-Newtonian behavior, for consistency with the ocean-atmosphere system.

Algae impacted drinking water: Does switching to chloramination produce safer drinking water?

Harmful algal (cyanobacterial) blooms (HABs) are increasing throughout the world. HABs can be a direct source of toxins in freshwater sources, and associated algal organic matter (AOM) can act as precursors for the formation of disinfection by-products (DBPs) in drinking water. This study investigated the impacts of algae on DBP formation using treatment with chloramine, which has become a popular disinfectant in the U.S. and in several other countries because it can significantly lower the levels of regulated DBPs formed. Controlled laboratory chloraminations were conducted using live field-collected algal biomass dominated by either Phormidium sp. or Microseira wollei (formerly known as Lyngbya wollei) collected from Lake Wateree and Lake Marion, SC. Sixty-six priority, unregulated or regulated DBPs were quantified using gas chromatography (GC)-mass spectrometry (MS). The presence of HAB-dominated microbial communities in source waters led to significant increases in more toxic nitrogen-containing DBPs (1.5-5 fold) relative to lake waters collected in HAB-free waters. Compared to chlorinated Phormidium-impacted waters, chloraminated waters yielded lower total DBP levels (up to 123 µg/L vs. 586 µg/L for low Br-/I- waters), but produced a greater number of brominated, iodinated, and mixed halogenated DBPs in high Br-/I- waters. Among the DBPs formed in Phormidium-impacted chloraminated waters, dichloroacetic acid, trichloromethane, chloroacetic acid, chloropropanone, and dichloroacetamide were dominant. For Microseira wollei-impacted chloraminated waters, total DBP concentrations ranged from 33 to 145 µg/L (approximately 3-5 times lower than chlorination), with dichloroacetic acid, dichloroacetamide, and trichloromethane dominant. Overall, chloramination significantly reduced calculated cytotoxicity and genotoxicity in low Br- and I- waters, but produced 1.3 fold higher calculated cytotoxicity (compared to chlorine) with high Br-/I- waters due to increased formation of more toxic iodo- and mixed halogenated DBPs.

Microcystins and Cyanobacterial Contaminants in the French Small-Scale Productions of Spirulina (Limnospira sp.).

Spirulina is consumed worldwide, in the form of food or dietary supplements, for its nutritional value and health potential. However, these products may contain cyanotoxins, including hepatotoxic microcystins (MCs), produced by cyanobacterial contaminants. The French spirulina market has the particularity of being supplied half-locally by approximately 180 small-scale spirulina production farms. Data about this particular production and possible contaminations with other cyanobacteria and MCs are scarce. Thus, we collected the results of MC analyses and total cyanobacteria counts, carried out between 2013 and 2021, from 95 French spirulina producers who agreed to share their data. These data consisted of MC concentrations determined with an enzyme-linked immunosorbent assay (ELISA) using 623 dry spirulina samples and 105 samples of spirulina cultures. In addition, potentially unsafe samples of dry spirulina were further investigated through mass spectrometry, as duplicate analysis. We confirmed that the situation of the French spirulina production stayed within the safe regulatory level in terms of MC levels. On the other hand, the inventory of cyanobacterial contaminants, based on 539 count results, included 14 taxa. We present their prevalence, interannual evolution and geographical distribution. We also suggested improvements in cultivation practices to limit their propagation.

First Confirmed Case of Canine Mortality Due to Dihydroanatoxin-a in Central Texas, USA.

The frequency of dogs becoming ill or dying from accidental exposure to cyanotoxins, produced by cyanobacteria, is increasing throughout the United States. In January and February of 2021, two dogs died and five dogs became ill after swimming in Lake Travis, central Texas, USA; one deceased dog (C1) was subjected to pathological testing. Algal materials, sediment samples, zebra mussel viscera, periphyton from shells, as well as fluids and tissues from the digestive tract of C1 were investigated for the following cyanotoxins: anatoxin-a, homoanatoxin-a, dihydroanatoxin-a (dhATX), cylindrospermopsin, saxitoxin, and microcystins. Necropsy results of C1 indicated neurotoxicosis with significant levels of dhATX in the duodenum tissues (10.51 ng/g dry weight (DW)), jejunum tissue (6.076 ng/g DW), and stomach contents (974.88 ng/g DW). Algae collected near the site of C1's death contained levels of dhATX, ranging from 13 to 33 µg/g. By comparison, dhATX was detected at much lower concentrations in sediment samples (310.23 ng/g DW) and the periphyton on zebra mussel shells (38.45 ng/g DW). While dhATX was suspected in the deaths of canines from an event in Texas in 2019, this is the first report linking dhATX neurotoxicosis through pathological findings in Texas and potentially in the United States.

Physiological and Biochemical Responses in Microalgae Dunaliella salina, Cylindrotheca closterium and Phormidium versicolor NCC466 Exposed to High Salinity and Irradiation.

Dunaliella salina (Chlorophyceae), Phormidium versicolor (Cyanophyceae), and Cylindrotheca closterium (Bacillariophyceae) were isolated from three ponds in the solar saltern of Sfax (Tunisia). Growth, pigment contents, and photosynthetic and antioxidant enzyme activities were measured under controlled conditions of three light levels (300, 500, and 1000 µmol photons m-2 s-1) and three NaCl concentrations (40, 80, and 140 g L-1). The highest salinity reduced the growth of D. salina and P. versicolor NCC466 and strongly inhibited that of C. closterium. According to ΦPSII values, the photosynthetic apparatus of P. versicolor was stimulated by increasing salinity, whereas that of D. salina and C. closterium was decreased by irradiance rise. The production of carotenoids in D. salina and P. versicolor was stimulated when salinity and irradiance increased, whereas it decreased in the diatom. Catalase (CAT), Superoxide dismutase (SOD), and Ascorbate peroxidase (APX) activities were only detected when the three species were cultivated under E1000. The antioxidant activity of carotenoids could compensate for the low antioxidant enzyme activity measured in D. salina. Salinity and irradiation levels interact with the physiology of three species that have mechanisms of more or less effective stress resistance, hence different resistance to environmental stresses according to the species. Under these stress-controlled conditions, P. versicolor and C. closterium strains could provide promising sources of extremolyte for several purposes.

A novel actinomycete Streptomyces enissocaesilis exhibiting algicidal activity against the toxic cyanobacterium Phormidium angustissimum.

Harmful cyanobacterial blooms that occur in freshwater can produce hazardous cyanotoxins as contaminants that threaten ecosystems, aquatic organisms, and human health. In the present study, the actinobacterium Streptomyces enissocaesilis, strain M35, isolated from soils, exhibited the strongest algicidal activity against the toxic cyanobacterium Phormidium angustissimum TISTR 8247. To improve the P. angustissimum removal efficiency of strain M35, the optimum carbon and nitrogen sources were determined as starch and yeast extract, respectively. Response surface methodology (RSM) using the Box-Behnken design (BBD) revealed that the optimal independent parameters among the culture medium conditions for enhancing the algicidal activity of strain M35 were 21.5 g/L starch, 0.57 g/L yeast extract, and a pH value of 8.00. The Phormidium sp. removal efficiency increased notably from 80.8 to 94.4% under the optimum conditions. In a batch experiment, the removal of P. angustissimum in an internal airlift loop (IAL) bioreactor containing immobilized strain M35 on a plastic medium indicated a high anti-Phormidium activity of 94.8%, whereas in a continuous system, strain M35 exhibited a removal efficiency of 85.5%. This study revealed that this actinobacterium could potentially be utilized to remove the toxic cyanobacterium Phormidium from water.