Current projections estimate that in 2050 about 10 billion people will inhabit the earth and food production will need to increase by more than 60%. Food security will therefore represent a matter of global concern not easily tackled with current agriculture practices and curbed by the increasing scarcity of natural resources and climate change. Disrupting technologies are urgently needed to improve the efficiency of the food production system and to reduce the negative externalities of agriculture (soil erosion, desertification, air pollution, water and soil contamination, biodiversity loss, etc.). Among the most innovative technologies, the production of microbial protein (MP) in controlled and intensive systems called “bioreactors” is receiving increasing attention from research and industry. MP has low arable land requirements, does not directly compete with crop-based food commodities, and uses fertilizers with an almost 100% efficiency. This review considers the potential and limitations of four MP sources currently tested at pilot level or sold as food or feed ingredients: hydrogen oxidizing bacteria (HOB), methanotrophs, fungi, and microalgae (cyanobacteria). The environmental impacts (energy, land, water use, and GHG emissions) of these MP sources are compared with those of plant, animal, insect, and cultured meat-based proteins. Prices are reported to address whether MP may compete with traditional protein sources. Microalgae cultivation under artificial light is discussed as a strategy to ensure independence from weather conditions, continuous operation over the year, as well as high-quality biomass. The main challenges to the spreading of MP use are discussed.

The Euganean Thermal District, situated in North-East Italy, is one of Europe’s largest and oldest thermal centres. The topical application of its therapeutic thermal muds is recognised by the Italian Health System as a beneficial treatment for patients suffering from arthro-rheumatic diseases. Polysaccharides produced by the mud microbiota have been recently identified as anti-inflammatory bioactive molecules. In this paper we analysed the efficacy of Microbial-Polysaccharides (M-PS) derived from mature muds obtained at different maturation temperatures, both within and outside the codified traditional mud maturation range. M-PSs were extracted from six mature muds produced by five spas of the Euganean Thermal District and investigated for their chemical properties, monosaccharide composition and in vivo anti-inflammatory potential, using the zebrafish model organism. Additionally, mature muds were characterized for their microbiota composition using Next-Generation Sequencing. The results showed that all M-PSs exhibit similar anti-inflammatory potential, referable to their comparable chemical composition. This consistency was observed despite changes in cyanobacteria populations, suggesting a possible role of the entire microbial community in shaping the properties of these biomolecules. These findings highlight the importance of scientific research in untangling the origins of the therapeutic efficacy of Euganean Thermal muds in the treatment of chronic inflammatory conditions.

This study investigates the potential of released polysaccharides (RPS) from the halophilic cyanobacterium Cyanothece sp. CE4 as biosorbents for heavy metals, specifically copper (Cu), nickel (Ni), and zinc (Zn). By combining ICP-OES, SEM-EDX, FT-IR spectroscopy, and XAS techniques, this work provides a comprehensive chemical and spectroscopic analysis of the biosorption mechanisms driving metal removal. The results revealed a strong binding affinity for Cu, followed by Ni and Zn, with RPS functional groups playing a key role in metal coordination. The RPS efficiently removed metals from both monometallic and multimetallic solutions, emphasizing their adaptability in competitive environments. XAS analysis highlighted unique metal-specific coordination patterns. Ni preferentially binds to oxygen donors and Zn to chlorine, and Cu exhibits non-selective binding. Remarkably, the extracted RPS achieved a maximum Cu removal capacity of 67 mg per gram of RPS dry weight, surpassing previously reported biosorption capacities. This study not only advances the understanding of biosorption mechanisms by cyanobacterial RPS but also emphasizes their dual role in environmental remediation and circular resource management. The insights provided here establish a foundation for the development of sustainable, cyanobacteria-based solutions for heavy-metal recovery and environmental sustainability.

Microalgae-based bioremediation is increasingly recognized as a sustainable, efficient, and straightforward technology. Despite this growing interest, the potential of Parachlorella hussii for metal biosorption remains underexplored. This study is the first report evaluating the metal biosorption activity in Parachlorella hussii ACOI 1508 (N9), highlighting the impact of the culture age on the monosaccharide composition and its correlation to the metal binding capacity. The capsular strain (N9) was isolated from the hypersaline ecosystem—Lake Chott Aïn El-Beida—in southeastern Algeria. Cultivated in Bold’s Basal medium, the strain produced 0.807 ± 0.059 g L⁻¹ of RPSs and 1.975 ± 0.120 g L⁻¹ of CPSs. Biochemical analysis of the extracts revealed a high total sugar content (% w/w) that ranged from 62.98 ± 4.87% to 95.60 ± 87% and a low protein content (% w/w) that ranged from 0.49 ± 0.08% to 1.35 ± 0.69%, with RPS-D7 and RPS-D14 having high molecular weight (≥2 MDa). HPLC-based monosaccharide characterization demonstrated compositional differences between the exponential and stationary phases, with rhamnose dominating (~55%) in RPS-D14 and with the presence of uronic acids comprising 7–11.3%. Metal removal efficiency was evaluated using the whole biomass in two growth phases. Copper uptake exhibited the highest capacity, reaching 18.55 ± 0.61 mg Cu g⁻¹ DW at D14, followed by zinc removal with 6.52 ± 0.61 mg Zn g⁻¹ DW. Interestingly, removal efficiencies increased to about twofold during the stationary phase, reaching 51.15 ± 1.14% for Cu, 51.08 ± 3.35% for Zn, and 36.55 ± 3.09% for Ni. The positive results obtained for copper/zinc removal highlight the biosorption potential of P. hussii, and notably, we found that the metal removal capacity significantly improved with culture age—a parameter that has been poorly investigated in prior studies. Furthermore, we observed a growth phase-dependent modulation in monosaccharide composition, which correlated with enhanced functional properties of the excreted biomolecules involved in biosorption. This metabolic adjustment suggests an adaptive response that may contribute to the species’ effectiveness in heavy metal uptake, underscoring its novelty and biotechnological relevance.

Galvanic electrodeposition is widely used in surface engineering, making the sustainable management of metal‐loaded effluents a future challenge. Although cyanobacteria‐based biosorption has been recognized as an eco‐friendly strategy to remove metals, its application to real wastewater has not been explored. This study investigates cyanobacterial potential in the treatment of different electroplating wastewater originated from Cu, Ni, Au, and Pd‐plating baths. The results revealed that pH, metal concentration, and composition of the plating bath influenced biosorption. Notably, Ni‐specific uptake reached 3 mmol of Ni per gram of biomass dry weight, exceeding values reported in the literature. In contrast, for precious metals, the uptake was lower than 0.1 mmol per gram of biomass dry weight. This study represents a first step in the scaling‐up of this cyanobacteria‐based biotechnology, highlighting that higher biomass concentration and combined approaches are needed to improve removal efficiency while producing clean water.