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As current methods of production of phycocyanobilin, a photosynthetic blue pigment derived from phycocyanin of filamentous cyanobacteria, Pseudanabaena sp. ABRG5–3, Limnothrix sp. SK1–2–1, and Spirulina sp., exhibit a low extraction efficiency, a new extraction method using ethanol extraction as a type of solvolysis with an autoclave (130 ℃, 5.7 bar, 10 min) was developed in this study. This method exhibited high efficiency and enabled easy recovery of the three types of phycocyanobilins. The identity of the three types of phycocyanobilins was confirmed by high-performance liquid chromatography and electrospray ionization-tandem mass spectrometry. Phycocyanobilins were stable at high temperatures (80 ℃) and acidic (pH 3) conditions. Phycocyanobilins also possessed a remarkable antioxidant property. This is the first time that a simple phycocyanobilin extraction method with a recovery rate of more than 60 % and approximately 1 % per dry cell weight of filamentous cyanobacteria has been demonstrated. This novel production method is thus convenient and effective for obtaining high-purity phycocyanobilins. • A new efficient method of phycocyanobilin (PCB) extraction was developed. • Structure and MW of three PCBs were confirmed by HPLC and ESI-CID-MS. • PCBs were stable under high temperatures (80 ℃) and acidic (pH 3) conditions. • PCBs show significant antioxidant abilities. [ABSTRACT FROM AUTHOR]

A cyanobacterium producing β-glucosidase was isolated from Lake Pamvotis located in Ioannina in Greece. This microorganism, named Pamv7, was identified as Pseudanabaena sp. using phylogenetic characterization. The high-throughput BiologMicroPlate™ method, used for the rapid assessment of heterotrophic potential, indicates that Pseudanabaena sp. metabolizes a wide range of organic substrates such as amino acids, carbohydrates, and carboxylic acids. When the strain grows in a culture medium containing cellobiose as a carbon source, it produces a significant amount of intracellular β-glucosidase. The effect of cellobiose concentration, nitrogen source, and nitrogen concentration of the growth medium, as well as the temperature of the culture, on biomass and β-glucosidase by Pseudanabaena sp., was studied. Biomass and β-glucosidase production by the strain in a lab-scale bioreactor at optimal conditions (10 g/L cellobiose, 1.5 g/L yeast, and 23 ± 1 °C) reached 2.8 g dry weight/L and 44 U/L, respectively. The protein and lipid content of the produced cyanobacterium biomass were 23% and 43 w/w, respectively. This study is the first report of β-glucosidase production by a cyanobacterial strain and concomitant high production of microalgae biomass, making Pseudanabaena sp. a promising microorganism in the field of enzyme biotechnology.

Freshwater blooms of harmful cyanobacteria in drinking water source-oriented shallow lakes affect public health and ecosystem services worldwide. Therefore, identifying 2-methylisoborneol (2-MIB)-producing cyanobacteria and predicting the risks of 2-MIB are critical for managing 2-MIB–infected water sources. Previous studies on the potential producers and risks of 2-MIB have focused on reservoirs or have been limited by the ecosystems of phytoplankton-dominated areas. We investigated the producers, distribution, and occurrence of 2-MIB in East Taihu Lake—a drinking water source-oriented shallow lake with macrophyte- and phytoplankton-dominated areas—from August 2020 to November 2021. We observed that Pseudanabaena sp. produces 2-MIB in this lake, as determined by the maximum correlation coefficient (R = 0.71, p < 0.001), maximum detection rate, and minimum false positive/negative ratio exhibited by this genus. Extreme odor events occurred in this lake during late summer and early autumn in 2021, with the mean 2-MIB concentration increasing to 727 ± 426 ng/L and 369 ± 176 ng/L in August and September, respectively. Moreover, the macrophyte-dominated area, particularly the wetland area, exhibited a significant decrease (p < 0.01) in bloom intensity and 2-MIB production during these extreme odor events. Pseudanabaena sp. outbreak was likely owing to eutrophication, seasonal gradients, and macrophyte reduction, considering that temporal trends were consistent with high water temperature, high total phosphorus levels, and low-light conditions. Moreover, 2-MIB production was sensitive to short-term hydrometeorological processes, with high water levels and radiant intensity enhancing 2-MIB production. The risk assessment results showed that the probability of 2-MIB concentration exceeding the odor threshold (10 ng/L) is up to 90% when the cell density of Pseudanabaena sp. reaches 1.8 × 107 cell/L; this risk is reduced to 50 and 25% at densities of < 3.8 × 105 cell/L and 5.6 × 104 cell/L, respectively. Our findings support calls for shallow lake management efforts to maintain a macrophyte-dominated state and control odorous cyanobacteria growth. [ABSTRACT FROM AUTHOR]

A cyanobacterium producing β-glucosidase was isolated from Lake Pamvotis located in Ioannina in Greece. This microorganism, named Pamv7, was identified as Pseudanabaena sp. using phylogenetic characterization. The high-throughput BiologMicroPlate™ method, used for the rapid assessment of heterotrophic potential, indicates that Pseudanabaena sp. metabolizes a wide range of organic substrates such as amino acids, carbohydrates, and carboxylic acids. When the strain grows in a culture medium containing cellobiose as a carbon source, it produces a significant amount of intracellular β-glucosidase. The effect of cellobiose concentration, nitrogen source, and nitrogen concentration of the growth medium, as well as the temperature of the culture, on biomass and β-glucosidase by Pseudanabaena sp., was studied. Biomass and β-glucosidase production by the strain in a lab-scale bioreactor at optimal conditions (10 g/L cellobiose, 1.5 g/L yeast, and 23 ± 1 °C) reached 2.8 g dry weight/L and 44 U/L, respectively. The protein and lipid content of the produced cyanobacterium biomass were 23% and 43 w/w, respectively. This study is the first report of β-glucosidase production by a cyanobacterial strain and concomitant high production of microalgae biomass, making Pseudanabaena sp. a promising microorganism in the field of enzyme biotechnology. [ABSTRACT FROM AUTHOR]

Environmental pollution, greenhouse gas emissions, depletion of fossil fuels, and a growing population have sparked a search for new and renewable energy sources such as biodiesel. The use of waste or residues as substrates for microbial growth can favor the implementation of a biorefinery concept with reduced environmental footprint. Cyanobacteria constitute microorganisms with enhanced ability to use industrial effluents, wastewaters, forest residues for growth, and concomitant production of added-value compounds. In this study, a recently isolated cyanobacterium strain of Pseudanabaena sp. was cultivated on hydrolysates from pretreated forest biomass (silver birch and Norway spruce), and the production of biodiesel-grade lipids was assessed. Optimizing carbon source concentration and the (C/N) carbon-to-nitrogen ratio resulted in 66.45% w/w lipid content when microalgae were grown on glucose, compared to 62.95% and 63.79% w/w when grown on spruce and birch hydrolysate, respectively. Importantly, the lipid profile was suitable for the production of high-quality biodiesel. The present study demonstrates how this new cyanobacterial strain could be used as a biofactory, converting residual resources into green biofuel. [ABSTRACT FROM AUTHOR]

Phycocyanin is a precious, natural, blue coloured pigment-protein complex that has commercial value and wide application in cosmetics, food, and pharmaceutical industries. In the present study, we performed various cell disruption methods (ultrasonication, homogenization, freeze/thaw and CaCl2 extraction) for phycocyanin extraction from different forms of biomass of a thermophilic Pseudanabaena sp. that has a high potential to produce high-quality phycocyanin. Using potassium phosphate buffer and ultrasonic bath method, we achieved the highest phycocyanin yield (345 mgPC.g-biomass) from freeze-dried biomass and we obtained increased yield as the duration of application increases. Phycocyanin yields were calculated as 345 mgPC.g-biomass, 255 mgPC.g-biomass and 220 mgPC.g-biomass for 5, 10 and 15 min, respectively. In this study, cell disruption methods have determined significantly more effective on freeze-dried biomass rather than frozen biomass. Phycocyanin content of freeze-dried biomass was analysed after six months of storage and dramatic decrement was observed in the phycocyanin content of the cells. [ABSTRACT FROM AUTHOR]

Environmental pollution, greenhouse gas emissions, depletion of fossil fuels, and a growing population have sparked a search for new and renewable energy sources such as biodiesel. The use of waste or residues as substrates for microbial growth can favor the implementation of a biorefinery concept with reduced environmental footprint. Cyanobacteria constitute microorganisms with enhanced ability to use industrial effluents, wastewaters, forest residues for growth, and concomitant production of added-value compounds. In this study, a recently isolated cyanobacterium strain of Pseudanabaena sp. was cultivated on hydrolysates from pretreated forest biomass (silver birch and Norway spruce), and the production of biodiesel-grade lipids was assessed. Optimizing carbon source concentration and the (C/N) carbon-to-nitrogen ratio resulted in 66.45% w/w lipid content when microalgae were grown on glucose, compared to 62.95% and 63.79% w/w when grown on spruce and birch hydrolysate, respectively. Importantly, the lipid profile was suitable for the production of high-quality biodiesel. The present study demonstrates how this new cyanobacterial strain could be used as a biofactory, converting residual resources into green biofuel.