Fermentation

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3 pages, 189 KiB

Open AccessEditorial

Algal Biomass: From Bioproducts to Biofuels

by Florian Delrue

Fermentation 2023, 9(4), 362; https://doi.org/10.3390/fermentation9040362 - 7 Apr 2023

Viewed by 958

Abstract

Microalgae covers an extremely diverse type of unicellular microorganisms that use light and efficiently fix CO₂ through the process of photosynthesis [...] Full article

(This article belongs to the Special Issue Algal Biomass: From Bioproducts to Biofuels)

Research

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15 pages, 5289 KiB

Open AccessArticle

Algal Hydrogen Production and Exopolysaccharide Patterns in Chlorella–Bacillus Inter-Kingdom Co-Cultures

by Bettina Hupp, Gabriella Huszár, Attila Farkas and Gergely Maróti

Fermentation 2023, 9(5), 424; https://doi.org/10.3390/fermentation9050424 - 28 Apr 2023

Cited by 1 | Viewed by 1767

Abstract

Biohydrogen production from wastewater using eukaryotic green algae can be facilitated by appropriately selected bacterial partners and cultivation conditions. Two Chlorella algal species were chosen for these experiments, based on their robust growth ability in synthetic wastewater. The applied three Bacillus bacterial partners [...] Read more.

Biohydrogen production from wastewater using eukaryotic green algae can be facilitated by appropriately selected bacterial partners and cultivation conditions. Two Chlorella algal species were chosen for these experiments, based on their robust growth ability in synthetic wastewater. The applied three Bacillus bacterial partners showed active respiration and efficient biomass production in the same synthetic wastewater. Bacillus amyloliquefaciens, Bacillus mycoides, and Bacillus cereus as bacterial partners were shown to specifically promote algal biomass yield. Various inter-kingdom co-culture combinations were investigated for algal–bacterial biomass generation, for co-culture-specific exopolysaccharide patterns, and, primarily, for algal biohydrogen evolution. Chlorella sp. MACC-38 mono- and co-cultures generated significantly higher biomass compared with that of Chlorella sp. MACC-360 mono- and co-cultures, while in terms of hydrogen production, Chlorella sp. MACC-360 co-cultures clearly surpassed their Chlorella sp. MACC-38 counterparts. Imaging studies revealed tight physical interactions between the algal and bacterial partners and revealed the formation of co-culture-specific exopolysaccharides. Efficient bacterial respiration was in clear correlation with algal hydrogen production. Stable and sustainable algal hydrogen production was observed in synthetic wastewater for Chlorella sp. MACC-360 green algae in co-cultures with either Bacillus amyloliquefaciens or Bacillus cereus. The highest algal hydrogen yields (30 mL H₂ L⁻¹ d⁻¹) were obtained when Chlorella sp. MACC-360 was co-cultured with Bacillus amyloliquefaciens. Further co-culture-specific algal biomolecules such as co-cultivation-specific exopolysaccharides increase the valorization potential of algal–bacterial co-cultures and might contribute to the feasibility of algal biohydrogen production technologies. Full article

(This article belongs to the Special Issue Algal Biomass: From Bioproducts to Biofuels)

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12 pages, 1318 KiB

Open AccessEditor’s ChoiceArticle

Photosynthetic Carbon Uptake Correlates with Cell Protein Content during Lipid Accumulation in the Microalga Chlorella vulgaris NIES 227

by Paul Chambonniere, Adriana Ramírez-Romero, Alexandra Dimitriades-Lemaire, Jean-François Sassi and Florian Delrue

Fermentation 2022, 8(11), 614; https://doi.org/10.3390/fermentation8110614 - 8 Nov 2022

Cited by 8 | Viewed by 2128

Abstract

Large-scale microalgae cultivation for biofuel production is currently limited by the possibility of maintaining high microalgae yield and high lipid content, concomitantly. In this study, the physiological changes of Chlorella vulgaris NIES 227 during lipid accumulation under nutrient limitation was monitored in parallel [...] Read more.

Large-scale microalgae cultivation for biofuel production is currently limited by the possibility of maintaining high microalgae yield and high lipid content, concomitantly. In this study, the physiological changes of Chlorella vulgaris NIES 227 during lipid accumulation under nutrient limitation was monitored in parallel with the photosynthetic capacity of the microalgae to fix carbon from the proxy of oxygen productivity. In the exponential growth phase, as the biomass composition did not vary significantly (approx. 53.6 ± 7.8% protein, 6.64 ± 3.73% total lipids, and 26.0 ± 9.2% total carbohydrates of the total biomass dry-weight), the growth capacity of the microalgae was preserved (with net O₂ productivity remaining above (4.44 ± 0.93) × 10⁻⁷ g O₂·µmol PAR⁻¹). Under nutrient limitation, protein content decreased (minimum of approx. 18.6 ± 6.0%), and lipid content increased (lipid content up to 56.0 ± 0.8%). The physiological change of the microalgae was associated with a loss of photosynthetic activity, down to a minimum (1.27 ± 0.26) × 10⁻⁷ g O₂·µmol PAR⁻¹. The decrease in photosynthetic O₂ productivity was evidenced to correlate to the cell internal-protein content (R² = 0.632, p = 2.04 × 10⁻⁶, N = 25). This approach could serve to develop productivity models, with the aim of optimizing industrial processes. Full article

(This article belongs to the Special Issue Algal Biomass: From Bioproducts to Biofuels)

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15 pages, 1588 KiB

Open AccessArticle

Chlorellaceae Feedstock Selection under Balanced Nutrient Limitation

by Adriana Ramírez-Romero, Bruno Da Costa Magalhães, Alexandra Dimitriades-Lemaire, Jean-François Sassi, Florian Delrue and Jean-Philippe Steyer

Fermentation 2022, 8(10), 554; https://doi.org/10.3390/fermentation8100554 - 18 Oct 2022

Cited by 9 | Viewed by 1922

Abstract

Microalgae are an attractive source of biomass for fossil fuel alternatives and renewable energy sources. Regardless of their potential, the development of microalgal biofuels has been limited due to the associated economic and environmental costs. We followed and compared the biomass properties of [...] Read more.

Microalgae are an attractive source of biomass for fossil fuel alternatives and renewable energy sources. Regardless of their potential, the development of microalgal biofuels has been limited due to the associated economic and environmental costs. We followed and compared the biomass properties of six Chlorellaceae strains with a specific interest in lipid-based biofuels. The strains were cultivated under balanced nutrient limitation inducing a gradual limitation of nutrients that triggered reserve accumulation. The final biomass of each strain was characterized by its elemental and biochemical composition. Due to its high lipid content and overall composition, Chlorella vulgaris NIES 227 was identified as an ideal feedstock for biofuels with the best energy-content biomass. Its fatty acid profile also showed superior qualities for biodiesel production. Balanced nutrient limitation promoted not only the accumulation of storage compounds in all strains, but also resulted in a low content of heteroatom precursors and ashes for biofuel applications. Full article

(This article belongs to the Special Issue Algal Biomass: From Bioproducts to Biofuels)

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19 pages, 3250 KiB

Open AccessArticle

Technoeconomic Evaluation of Microalgae Oil Production: Effect of Cell Disruption Method

by Esveidi Montserrat Valdovinos-García, Micael Gerardo Bravo-Sánchez, María de los Ángeles Olán-Acosta, Juan Barajas-Fernández, Adriana Guzmán-López and Moisés Abraham Petriz-Prieto

Fermentation 2022, 8(7), 301; https://doi.org/10.3390/fermentation8070301 - 26 Jun 2022

Cited by 7 | Viewed by 2460

Abstract

Microalgae have a high capacity to capture CO₂. Additionally, biomass contains lipids that can be used to produce biofuels, biolubricants, and other compounds of commercial interest. This study analyzed various scenarios for microalgae lipid production by simulation. These scenarios include cultivation [...] Read more.

Microalgae have a high capacity to capture CO₂. Additionally, biomass contains lipids that can be used to produce biofuels, biolubricants, and other compounds of commercial interest. This study analyzed various scenarios for microalgae lipid production by simulation. These scenarios include cultivation in raceway ponds, primary harvest with three flocculants, secondary harvest with pressure filter (and drying if necessary), and three different technologies for the cell disruption step, which facilitates lipid extraction. The impact on energy consumption and production cost was analyzed. Both energy consumption and operating cost are higher in the scenarios that consider bead milling (8.79–8.88 kWh/kg and USD 41.06–41.41/kg), followed by those that consider high-pressure homogenization (HPH, 5.39–5.46 kWh/kg and USD 34.26–34.71/kg). For the scenarios that consider pressing, the energy consumption is 5.80–5.88 kWh/kg and the operating cost is USD 27.27–27.88/kg. The consumption of CO₂ in scenarios that consider pressing have a greater capture (11.23 kg of CO₂/kg of lipids). Meanwhile, scenarios that consider HPH are the lowest consumers of fresh water (5.3 m³ of water/kg of lipids). This study allowed us to develop a base of multiple comparative scenarios, evaluate different aspects involved in Chlorella vulgaris lipid production, and determine the impact of various technologies in the cell disruption stage. Full article

(This article belongs to the Special Issue Algal Biomass: From Bioproducts to Biofuels)

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14 pages, 2465 KiB

Open AccessArticle

Development of a Microalgae-Based Continuous Starch-to-Hydrogen Conversion Approach

by Bettina Hupp, Bernadett Pap, Attila Farkas and Gergely Maróti

Fermentation 2022, 8(7), 294; https://doi.org/10.3390/fermentation8070294 - 23 Jun 2022

Cited by 11 | Viewed by 2576

Abstract

Eukaryotic algae represent a highly heterogeneous group in terms of organization, lifestyle, and metabolic capabilities. Unicellular green microalgae are capable of biohydrogen production through direct and indirect photolysis as well as dark fermentation. Most algae hydrogen studies focus on axenic algal cultures, although [...] Read more.

Eukaryotic algae represent a highly heterogeneous group in terms of organization, lifestyle, and metabolic capabilities. Unicellular green microalgae are capable of biohydrogen production through direct and indirect photolysis as well as dark fermentation. Most algae hydrogen studies focus on axenic algal cultures, although these are difficult and expensive to maintain for continuous operation. Moreover, the complex interplays and metabolic fluxes between algae and bacteria in natural ecosystems provide a number of clear biological and technological benefits to large-scale functional algae-based systems. Two green algae species from the Chlamydomonas and Chlorella genera were used to engineer stable synthetic communities by incorporating a starch-degrading bacterium from the Bacillus genus into the inter-kingdom consortium. Continuous photoheterotrophic biohydrogen production was achieved by elaborating an appropriate algal–bacterial ratio and fine-tuning the culture conditions for the synthetic consortia. Medium with starch as only carbon source served as a simple model of cheap substrate for algal hydrogen generation. The engineered pairwise algal–bacterial associations showed increased biomass and biohydrogen yield compared to the axenic control conditions. Chlorella sp. MACC-360 produced a significantly higher amount of hydrogen when both the bacterium partner and starch were added to the media compared to the axenic algae. Continuous, elevated algal hydrogen production was achieved in media supplemented with 8 g L⁻¹ starch as sole carbon source when carefully selected initial cell number values were used for the Chlorella sp. MACC-360–B. amlyloliquefaciens co-cultures. Full article

(This article belongs to the Special Issue Algal Biomass: From Bioproducts to Biofuels)

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12 pages, 648 KiB

Open AccessArticle

Effects of Inoculation with Lactic Acid Bacteria on the Preservation of Nannochloropsis gaditana Biomass in Wet Anaerobic Storage and Its Impact on Biomass Quality

by Oluwatosin Oginni, Bradley Wahlen, Lynn Wendt, Michelle Walton, Thomas Dempster and Henri Gerken

Fermentation 2022, 8(4), 159; https://doi.org/10.3390/fermentation8040159 - 2 Apr 2022

Cited by 5 | Viewed by 2070

Abstract

Wet anaerobic storage of algal biomass is a promising preservation approach that can ensure a continuous supply of these feedstocks to biorefineries year-round. An effective solution to preservation must ensure minimal dry matter loss and a change in biochemical composition during storage. Therefore, [...] Read more.

Wet anaerobic storage of algal biomass is a promising preservation approach that can ensure a continuous supply of these feedstocks to biorefineries year-round. An effective solution to preservation must ensure minimal dry matter loss and a change in biochemical composition during storage. Therefore, the objective of this study is to investigate the preservation of Nannochloropsis gaditana biomass through wet anaerobic storage and its impact on biomass quality. Prior to storage, the algae sample is inoculated with two different strains of lactic acid bacteria and thereafter stored for 30 and 180 days. Each inoculant limited the dry matter loss to <10% (dry basis) after the storage duration. Final pH values (4.3–4.8) indicate that the biomass samples are properly ensiled, achieving the acidic conditions necessary for preservation. Compositional analysis of the biomass after storage shows a reduction in carbohydrate content, a relative increase in lipid content, and no significant change in the protein fraction. Glucose and galactose were the most prevalent sugar monomers. The low dry matter loss and minimal compositional change indicate that wet anaerobic storage is an effective means of preserving algal biomass and ensuring a constant supply of algal biomass feedstock to a biorefinery. Full article

(This article belongs to the Special Issue Algal Biomass: From Bioproducts to Biofuels)

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Review

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36 pages, 1345 KiB

Open AccessReview

Agro-Industrial Wastewaters for Algal Biomass Production, Bio-Based Products, and Biofuels in a Circular Bioeconomy

by Júlio Cesar de Carvalho, Denisse Tatiana Molina-Aulestia, Walter José Martinez-Burgos, Susan Grace Karp, Maria Clara Manzoki, Adriane Bianchi Pedroni Medeiros, Cristine Rodrigues, Thamarys Scapini, Luciana Porto de Souza Vandenberghe, Sabrina Vieira, Adenise Lorenci Woiciechowski, Vanete Thomaz Soccol and Carlos Ricardo Soccol

Fermentation 2022, 8(12), 728; https://doi.org/10.3390/fermentation8120728 - 12 Dec 2022

Cited by 10 | Viewed by 4837

Abstract

Recycling bioresources is the only way to sustainably meet a growing world population’s food and energy needs. One of the ways to do so is by using agro-industry wastewater to cultivate microalgae. While the industrial production of microalgae requires large volumes of water, [...] Read more.

Recycling bioresources is the only way to sustainably meet a growing world population’s food and energy needs. One of the ways to do so is by using agro-industry wastewater to cultivate microalgae. While the industrial production of microalgae requires large volumes of water, existing agro-industry processes generate large volumes of wastewater with eutrophicating nutrients and organic carbon that must be removed before recycling the water back into the environment. Coupling these two processes can benefit the flourishing microalgal industry, which requires water, and the agro-industry, which could gain extra revenue by converting a waste stream into a bioproduct. Microalgal biomass can be used to produce energy, nutritional biomass, and specialty products. However, there are challenges to establishing stable and circular processes, from microalgae selection and adaptation to pretreating and reclaiming energy from residues. This review discusses the potential of agro-industry residues for microalgal production, with a particular interest in the composition and the use of important primary (raw) and secondary (digestate) effluents generated in large volumes: sugarcane vinasse, palm oil mill effluent, cassava processing waster, abattoir wastewater, dairy processing wastewater, and aquaculture wastewater. It also overviews recent examples of microalgae production in residues and aspects of process integration and possible products, avoiding xenobiotics and heavy metal recycling. As virtually all agro-industries have boilers emitting CO₂ that microalgae can use, and many industries could benefit from anaerobic digestion to reclaim energy from the effluents before microalgal cultivation, the use of gaseous effluents is also discussed in the text. Full article

(This article belongs to the Special Issue Algal Biomass: From Bioproducts to Biofuels)

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32 pages, 1336 KiB

Open AccessReview

Microalgae and Cyanobacteria Biomass Pretreatment Methods: A Comparative Analysis of Chemical and Thermochemical Pretreatment Methods Aimed at Methane Production

by Maria C. de Oliveira, Isabelli D. Bassin and Magali C. Cammarota

Fermentation 2022, 8(10), 497; https://doi.org/10.3390/fermentation8100497 - 29 Sep 2022

Cited by 21 | Viewed by 3572

Abstract

Anaerobic digestion of microalgae and cyanobacteria was first proposed as a destination for algal biomass accumulated on stabilization ponds since it could not be disposed of directly in the environment. Now, the versatility of algal biomass makes them a suitable candidate to produce [...] Read more.

Anaerobic digestion of microalgae and cyanobacteria was first proposed as a destination for algal biomass accumulated on stabilization ponds since it could not be disposed of directly in the environment. Now, the versatility of algal biomass makes them a suitable candidate to produce biofuels and other biomolecules in biorefineries. Anaerobic digestion of biomass is advantageous because it does not require the extraction of specific cellular constituents or drying of the biomass. Nevertheless, challenges remain regarding biomass concentration and their resistant cell walls, which are factors that could hamper methane yield. Many pretreatment methods, including chemical and thermochemical, have been proposed to break down the complex polymers present on the cell wall into smaller molecules. Unfortunately, the relationship between biomass solubilization and methane yield is not well defined. This article intends to review the anaerobic digestion of algal biomass and the role of chemical and thermochemical pretreatments in enhancing methane production. Several pretreatment conditions selected from the scientific literature were compared to verify which conditions actually improve methane yield. The severity of the selected pretreatments was also assessed using the combined severity factor. Results suggest that thermochemical pretreatment in less severe conditions is the most efficient, leading to a greater increase in methane yield. Only enzymatic pretreatments and some thermal pretreatments result in a positive energy balance. The large-scale implementation of pretreatment methods requires technological innovations to reduce energy consumption and its integration with other processes in wastewater treatment plants. Full article

(This article belongs to the Special Issue Algal Biomass: From Bioproducts to Biofuels)

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