Growth kinetic and fuel quality parameters as selective criterion for screening biodiesel producing cyanobacterial strains

The potential of third-generation biodiesel from Tolypothrix sp. CACIAM22 as a feedstock

Renewable energy has been recognized as an alternative to fossil fuels as a step to transform the energy produced and consumed worldwide. Cyanobacteria and microalgae are currently being considered as substitutes to the traditional feedstock used to produce biofuels due to their ability to achieve high amounts of lipids under cellular stress conditions. The aim of this study was to investigate the utilization of Tolypothrix sp. CACIAM 22 cyanobacterial biomass as a feedstock for biodiesel production, specifically by examining the effects of supplementing with hydrolysate of Brazil nutshell (HBNS) on biomass generation, lipid production, fatty acid composition, and quality of synthesized biodiesel. The supplementation of HBNS led to a significant increase of 12g.L-1 in wet biomass production. The lipid content reached 41 % of the biomass produced in HBNS supplemented cultures when nitrate source was deprived. The quality evaluation of cyanobacteria-derived biodiesel was performed using Biodiesel Analyzer ver 2.2 software, revealing superior quality compared to biodiesel produced from plant sources. The biodiesel exhibited values of 23 h for oxidative stability, 65 for cetane number, and an iodine index of 31 (g I2. 100 g-1 fat), indicating promising potential as a renewable source. This study is the first to utilize HBNS as an organic supplement for cyanobacteria culture medium and assess its impact on biomass and lipid production in Tolypothrix sp., supporting the hypothesis of utilizing this biomass as a renewable feedstock for biodiesel production as a viable alternative to plant sources based on biomass production, lipid productivity, and biodiesel quality.

Evaluation of filamentous heterocystous cyanobacteria for integrated pig-farm biogas slurry treatment and bioenergy production

The study evaluates 36 filamentous heterocystous cyanobacteria for the treatment of biogas slurry from pig farm and the accumulation of biomass for bioenergy production. The results showed that only the strains B, J, and L were able to adapt to a 10% biogas slurry. The removal rates of ammonia nitrogen, total nitrogen, and total phosphorus for strains J and L were 92.46%-97.97%, 73.79%-79.90%, and 97.14%-98.46%, respectively, higher than that of strain B. Strain J had the highest biomass productivity and lipid productivity. Based on the biodiesel prediction results, it was concluded that strains J and L are more suitable for biodiesel production. The estimation of theoretical methane potential suggests that the algal biomass of strain J also have the desirable possibility of biogas generation. In summary, algal strain J (Nostoc sp.) offers great potential for biogas slurry treatment and for the production of bioenergy.

Trichormus variabilis (Cyanobacteria) Biomass: From the Nutraceutical Products to Novel EPS-Cell/Protein Carrier Systems

A native strain of the heterocytous cyanobacterium Trichormus variabilis VRUC 168 was mass cultivated in a low-cost photobioreactor for a combined production of Polyunsaturated Fatty Acids (PUFA) and Exopolymeric Substances (EPS) from the same cyanobacterial biomass. A sequential extraction protocol was optimized leading to high yields of Released EPS (REPS) and PUFA, useful for nutraceutical products and biomaterials. REPS were extracted and characterized by chemical staining, Reversed Phase-High-Performance Liquid Chromatography (RP-HPLC), Fourier Transform Infrared Spectroscopy (FT-IR) and other spectroscopic techniques. Due to their gelation property, REPS were used to produce a photo-polymerizable hybrid hydrogel (REPS-Hy) with addition of polyethylene glycol diacrylated (PEGDa). REPS-Hy was stable over time and resistant to dehydration and spontaneous hydrolysis. The rheological and functional properties of REPS-Hy were studied. The enzyme carrier ability of REPS-Hy was assessed using the detoxification enzyme thiosulfate:cyanide sulfur transferase (TST), suggesting the possibility to use REPS-Hy as an enzymatic hydrogel system. Finally, REPS-Hy was used as a scaffold for culturing human mesenchymal stem cells (hMSCs). The cell seeding onto the REPS-Hy and the cell embedding into 3D-REPS-Hy demonstrated a scaffolding property of REPS-Hy with non-cytotoxic effect, suggesting potential applications of cyanobacteria REPS for producing enzyme- and cell-carrier systems.