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Hydrogen (H2) is a highly efficient and clean energy source with the potential for renewable energy. The production of H2 from biological routes such as biophotolysis, photofermentation, dark fermentation, and bioelectrochemical production is characterized as a renewable alternative to current production, which is mainly based on energy-intensive electrochemical and thermochemical processes and responsible for the emission of high amounts of environmentally harmful compounds. Dark fermentation is the most efficient and cost-effective method for producing biohydrogen, making it a key research focus. This article offers a comprehensive overview of the dark fermentation process with the aim of enhancing hydrogen productivity and yields. Aspects related to the main substrates used, the inoculum sources and their pretreatment, and physical-chemical parameters of the process are covered. Furthermore, this manuscript addresses topics such as process integration, genetic and metabolic engineering of fermentative microorganisms, and the main types of bioreactors aimed at greater yields and productivity of biohydrogen to enable its production through dark fermentation on a larger scale.

Abstract The market for microbial gums such as xanthan, gellan, dextran, and curdlan is continuously expanding, driven by their increasing application in various industries including petroleum, pharmaceuticals, cosmetics, and food, with the latter accounting for approximately 50% of global usage. To meet the growing demand and improve sustainability, there is a need to enhance production efficiency and reduce costs. This article addresses these issues by examining recent advancements and emerging trends in microbial gum production and application. By highlighting patented technologies and innovative approaches, the article aims to provide a comprehensive understanding of how the industry can achieve higher yields and economic viability. Despite being produced by different microorganisms, these gums are synthesized under similar conditions, such as pH, temperature, and medium composition. The purification or downstream processes for these gums are also comparable, primarily involving solvent precipitation, centrifugation for separation, and drying. Significant advances in gum production include genetic improvement of microbial strains to improve biopolymer performance. Additionally, alternative media are being explored, either by optimizing nutrient availability or deprivation, or by using agroindustrial by-products to reduce production costs. Engineering improvements are another strategy: bioreactor characteristics, fermentation conditions and modes of operation, and advances in downstream process are highlighted. Furthermore, the text explores emerging trends in the application of microbial gums in the food sector. Microbial gums applications are not limited to their traditional action as emulsifiers and stabilizers, but expands to new uses in biodegradable packaging films and as antioxidant and prebiotic food ingredient.

Palm oil, the main vegetable oil produced globally, serves diverse purposes, ranging from cooking to the production of processed foods, cosmetics, and biodiesel. Despite contributing significantly to the economies of major producing nations, the escalating production of palm oil raises serious environmental concerns, including deforestation, biodiversity loss, and various forms of pollution. Palm oil mill effluent (POME), a byproduct of palm oil extraction, poses a severe environmental threat when left untreated. As an eco-friendly alternative, anaerobic digestion in controlled bioreactors has emerged, offering simultaneous POME treatment and biofuel generation, particularly hydrogen, with high energy efficiency. This review explores the challenges and opportunities associated with biohydrogen production from POME. Key considerations involve optimizing parameters through pretreatments, nanoparticle incorporation, defining optimal bioreactor conditions, determining hydraulic retention times, and integrating multi-stage processes like dark fermentation followed by photofermentation. This review also emphasizes the significance of sustainable practices and economic analyses in shaping the future of hydrogen production from POME, positioning it as a pivotal player in the palm oil industry’s circular economy and the global energy transition.

Sugarcane ethanol production generates about 360 billion liters of vinasse, a liquid effluent with an average chemical oxygen demand of 46,000 mg/L. Vinasse still contains about 11% of the original energy from sugarcane juice, but this chemical energy is diluted. This residue, usually discarded or applied in fertigation, is a suitable substrate for anaerobic digestion (AD). Although the technology is not yet widespread—only 3% of bioethanol plants used it in Brazil in the past, most discontinuing the process—the research continues. With a biomethane potential ranging from 215 to 324 L of methane produced by kilogram of organic matter in vinasse, AD could improve the energy output of sugarcane biorefineries. At the same time, the residual digestate could still be used as an agricultural amendment or for microalgal production for further stream valorization. This review presents the current technology for ethanol production from sugarcane and describes the state of the art in vinasse AD, including technological trends, through a recent patent evaluation. It also appraises the integration of vinasse AD in an ideal sugarcane biorefinery approach. It finally discusses bottlenecks and presents possible directions for technology development and widespread adoption of this simple yet powerful approach for bioresource recovery.

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.

Abstract We present an improved method of direct transesterification suitable for the quantitative analysis of multiple dry samples for its fatty acid content, using a minimal amount of biomass and reactants. The method features an acid-catalyzed direct alcoholysis of microgram samples of dry biomass; the rationale behind the solvent and reagent proportions chosen is discussed. The method was validated using seven microbial strains with diverse lipid content (Saccharomyces cerevisiae, Saccharomyces boulardii, Candida tropicalis, Haematococcus pluvialis, Chlorella vulgaris, Spirulina platensis and Schizochytrium limacinum), and compared with a macroscale direct transesterification method, and with gravimetric analysis of lipids extracted with solvents. The microscale method showed a conversion of 98.06 ± 0.87% of the lipids, using approximately 3 mg of dry biomass, 1mL of 0.2M H2SO4 dissolved in anhydrous ethanol (the acid is the catalyzer and ethanol the reactant)). The mixture was maintained at 70 °C for 20 h with periodic mixing, and then extracted with 2mL n-heptane and analyzed by GC-FID. The lipid content was then calculated considering dilution and sample mass. This method is effective, reliable, and technically attractive for analytical and comparative purposes.

The objective of the present work was to isolate and select strains with potential to perform the biotransformation of terpenic substrates. Microorganisms obtained from a collection culture and also isolated from a natural source of terpene substrate were tested. Seventeen strains were selected by their resistance to terpenes in potato dextrose agar containing up to 1% of limonene or α-pinene and β-pinene (1:1). Subsequently, 10 strains were selected by their capacity of using these terpenes as sole carbon source in a mineral medium. The biotransformation capacity of these strains was tested and the products obtained were identified by GC-MS.

Grifola frondosa is an edible Basidiomycete and produces exopolysaccharides (EPS) known for their antitumour activity. The objectives of this study are to produce exopolysaccharides in submerged fermentation using alternative carbon sources (sugar cane and soy molasses), and to evaluate their anti-proliferative activity against tumour cells. Exopolysaccharides were extracted by ethanol and tested against mice tumour cells, then characterized by gas chromatography. Carbon sources represent the major cost of the bioprocess, so a search for new alternatives such as agro-industrial residues is important to establish the viability on an industrial scale. Moreover, the data about the kinetics of the EPS production allow studying the optimization of the process.

Probiotics, live cells with different beneficiary characteristics, have been extensivelly studied and explored commercially in many different products in the world. Their benefits to human and animal health have been proven in hundreds of scientific research. Lactobacillus and Bifidobacterium are the main probiotic groups; however, there are reports on the probiotic potential of Pediococcus, Lactococcus, Bacillus and yeasts. Some of the identified probiotic strains exhibit powerful anti-inflammatory, antiallergic and other important properties. Apart from that, the consumption of dairy and non-dairy products stimulates the immunity in different ways. Various food matrices have been used with probiotics, which are briefly documented. In this review, the history of probiotics, their application in the health and food areas and new trends in probiotic products and processes are presented.

Banana is one of the most important fruits in the Brazilian diet and is mainly consumed naturally. Losses from crop to final consumer are high and estimated in about 30%. The aim of this work was to elaborate a distilled alcoholic beverage from discarded banana and to compare with commercial trademarks. Initially, yeast strains were isolated from banana fruit and characterized by their production of volatile aroma compounds. The highest aroma-producing yeast isolate was identified by ITS-rRNA gene sequencing as Pichia kluyveri. Pasteurized banana pulp and peel was fermented by the selected P. kluyveri at approximately 107 cells/mL. The sugars were converted quickly, and a high ethanol concentration (413 mg/L) was achieved after 24 h of fermentation. The fermented banana must was distilled in a Femel Alambic, and the head, heart and tail fractions were collected. The banana brandy produced had highest concentration of volatile compounds compared to trademarks, such as isoamyl acetate (13.5 mg/L), ethyl hexanoate (0.8 mg/L) and others. The results showed that whole banana must could be a good substrate for fermentation and distillation, and the sensory analysis performed revealed that the produced beverage had good acceptance by the tasters. This study demonstrates the potential of banana as a possible alternative to reduce waste and increase income to farmers.

Studies were conducted to evaluate Bacillus atrophaeus spores' production by solid-state fermentation (SSF) using sugarcane bagasse as support and soybean molasses as substrate at lab-scale in column bioreactors (forced aeration), plastic bags and Erlenmeyer flasks (aeration by diffusion). Different moisture contents (84%, 86% and 88%; 89%, 91% and 93%) and aeration rates (30mL/min, 45mL/min, 60mL/min and 90mL/min) were studied. The best condition for spore production (3.3x10(10) CFU.g-¹dry matter) in column bioreactor was 80% of initial humidity and no aeration. In Erlenmeyer flasks and plastic bags the best sporulation production reached 1.7 up to 4.7x10(10) CFU.g-1dry matter with 88-93% of initial moisture. The aeration rate had no significant effect on the spore yield. The initial moisture had a significant effect depending on the bioreactor type. Sporulation kinetic's assay was carried out and it showed the possibility to reduce the time of spore formation in two days.Estudos foram conduzidos para avaliar a produção de esporos de Bacillus atrophaeus, em escala laboratorial, por fermentação em estado sólido (FES) em biorreatores de coluna (aeração forçada), sacos plásticos e frascos tipo Erlenmeyer (aeração por difusão), usando bagaço de cana como suporte e melaço de soja como substrato. Diferentes teores de umidade (84%, 86% e 88%, 89%, 91% e 93%) e taxas de aeração (30mL/min, 45mL/min, 60mL/min e 90mL/min) foram estudados. A melhor condição para a produção de esporos no biorreator de coluna (3.3 x 10(10) CFU.g-1 matéria seca) foi 80% de umidade inicial, sem aeração. Em frascos Erlenmeyer e sacos de plástico a melhor esporulação foi na faixa de 1.7 a 4.7 x 10(10) CFU.g-1 matéria seca, com 88-93% de umidade inicial. A taxa de aeração não teve efeito significativo sobre o rendimento da esporulação. A umidade inicial apresentou efeito significativo relacionado ao tipo do biorreator. O estudo da cinética da esporulação demonstrou a possibilidade de reduzir o tempo de incubação para esporulação em dois dias.

Aroma and fragrance compounds have broad applications in the food, cosmetic and pharmaceutical industries. However, these compounds are mainly produced by chemical synthesis. An alternative, sustainable and promising route for the natural production of flavour compounds is microbial transformation processes. In this work, we obtained the production of different aroma compounds in significant concentrations, such as isoamyl acetate, isoamyl alcohol, ethyl acetate and acetaldehyde, among others, from agribusiness by-products (sugarcane molasses) and using Pichia fermentans. These were subsequently concentrated by pervaporation and microencapsulation by spray drying using different encapsulating agents. The results showed that when these techniques were applied to two iced beverages, they produced an odour of fruity notes, especially those of banana. In addition, woody and alcoholic notes were identified by the panellists. Finally, the best encapsulating agents were dextrin (73.49 ppm) and the dextrin and maltodextrin mixture (72.58 ppm