Search Results (334)

In oleaginous yeast submerged fermentation, dissolved oxygen (DO) regulates both metabolism and cell morphology. Under oxygen limitation, Trichosporon cutaneum transitions from yeast-form to hyphae-form; the yeast-form morphology is more suitable for lipid production. This study enhanced oxygen transfer via reactor engineering to maintain yeast morphology and improve lipid productivity. Three strategies were assessed: increased agitation/aeration, enriched air supply, and microporous ceramic membrane gas distributor (MCMGD). Fermentation kinetics were analyzed alongside computational fluid dynamics (CFD) simulations of volumetric mass transfer coefficient (k_La), gas holdup, bubble diameter, and flow fields. Conventional strategies only partially alleviated oxygen limitation (maximum 4.47 g/L lipid). Enriched air improved lipid content but induced early myceliation. The MCMGD (1.0 vvm, 150 rpm) shortened fermentation from 150 h to 60 h, achieving 12.06 g/L lipid (49.16% content)—a 2.16-fold lipid concentration increase. Mechanistically, it generated smaller bubbles (1.47 mm vs. 2.54 mm) and higher k_La (0.012 s⁻¹ vs. 0.0055 s⁻¹). CFD revealed improved axial flow, reduced dead zones, and uniform gas holdup, suppressing yeast-to-hyphae shift. By enhancing mass transfer under low shear, the MCMGD ensures adequate oxygenation, maintains productive morphology, and significantly improves lipid production—offering a promising strategy for industrial application. Full article

Thraustochytrids are promising alternatives for the production of docosahexaenoic acid (DHA; C22:6 n-3), a long-chain polyunsaturated fatty acid with health benefits. For practical application of this oleaginous microorganism, an efficient cultivation method to enhance DHA production is required, which relies on several factors that support cell growth, lipid accumulation, and lipid turnover. In this study, the robust submerged fermentation of an acid- and high-temperature-tolerant strain of Aurantiochytrium limacinum was investigated. Under controlled temperature and acidic conditions (pH 4.5 and 30 °C), glucose and peptone were the best carbon and nitrogen sources for enhancing biomass and DHA production, respectively, with a glucose concentration of 60 g/L and a C/N ratio of 24 being optimal for DHA production. Applying an aeration rate of 2 vvm and an agitation speed of 300 rpm using a combination of a ring sparger and pitch-blade impeller in a stirred-tank bioreactor improved DHA production using intermittent fed-batch fermentation. The highest DHA titer was obtained at 3.01 g/L, and the DHA content in biomass was 10.69% (w/w) after intermittent feeding of cassava starch hydrolysate as the substrate. Full article

Carotenoids are natural pigments of high industrial value, with recognized antioxidant properties, and are widely used in the food, cosmetic, and pharmaceutical industries. Oleaginous yeasts, such as Rhodotorula glutinis, represent a promising alternative for the sustainable production of these compounds through submerged fermentation, compared to their extraction from plant sources or chemical synthesis. This study aimed to optimize culture conditions to maximize biomass and carotenoid production in R. glutinis P4M422. To this end, the effects of various culture factors, including light, carbon-to-nitrogen (C/N) ratio, temperature, pH, and glycerol addition, on cell growth and pigment biosynthesis were evaluated. The results showed that agitation speed and C/N ratio are key variables in system performance, significantly influencing both growth and carotenoid accumulation. Under the established optimal conditions (210 rpm, C/N ratio of 50, red light, and 30 °C), a maximum volumetric yield of 343.1 mg/L and a productivity of 4.8 mg/L/h were achieved, representing a substantial improvement in process efficiency. These values position the R. glutinis P4M422 strain as a competitive alternative for the biotechnological production of carotenoids. Taken together, these findings confirm the efficiency of submerged culture as a platform for obtaining high-value-added biopigments and reinforce the potential of microbial fermentation systems as a sustainable, scalable, and controllable strategy for their production. Full article

Proteases are key biocatalysts widely applied in the food, pharmaceutical, detergent, and environmental industries. One of the most costly steps in large-scale enzyme production is the preparation of the culture medium, making agro-industrial wastes attractive as low-cost nutrient sources and potential inducers. The non-conventional yeast Yarrowia lipolytica stands out in bioprocess engineering due to its high secretion capacity, GRAS status, and ability to metabolize diverse industrial residues. In this study, Brazilian agro-industrial by-products, namely Corn steep liquor (CSL), brewer’s yeast residue (BYR), and okara, were evaluated as alternative nitrogen sources for protease production by Y. lipolytica IMUFRJ 50678. Enzyme activity was quantified by the azocasein method at optimized conditions (40 °C, 40 min, pH 5 and 8). After an initial exploratory screening (n = 1), brewer’s yeast residue (BYR) and okara were identified as promising candidates for protease production. These preliminary findings guided subsequent experiments performed in biological triplicate (n = 3), which confirmed the reproducibility and comparative performance of these substrates, showing higher acid protease (AXP) activity in the BYR medium ((5.4 ± 0.3) U/mL), whereas alkaline protease (AEP) activities were comparable between the BYR ((8.4 ± 0.6) U/mL) and okara ((7.5 ± 0.9) U/mL) media. CSL was associated with higher lipase activity ((11.7 ± 0.9) × 10³ U/L), while esterase activity was higher in the BYR medium. These findings indicate that agro-industrial residues, particularly BYR and okara, can serve as effective nitrogen sources for protease production by Y. lipolytica IMUFRJ 50678, supporting their use in waste valorization and sustainable bioprocesses. Full article

Given the therapeutic potential of bioactive cordycepin in medical and healthcare products, precision fermentation using an engineered strain of Aspergillus oryzae was performed to enhance cordycepin production. To understand and predict the dynamics of cell growth and cordycepin production in this fungal strain, mathematical modeling of submerged fermentation was applied. The effects of different nitrogen sources (yeast extract, peptone, (NH₄)₂SO₄, NH₄Cl, NaNO₃, and KNO₃) and carbon sources (glucose and cassava starch hydrolysate, CSH) on cell growth and cordycepin production were evaluated under submerged fermentation conditions. The results showed that organic nitrogen sources significantly enhanced biomass formation and cordycepin production compared with inorganic nitrogen sources. Among them, yeast extract provided the best performance, yielding the highest biomass (13.63–15.99 g/L) and cordycepin titer (1.24–1.72 g/L). In contrast, nitrate-based nitrogen sources supported cell growth but resulted in negligible cordycepin production. Under optimized conditions in a bioreactor, both glucose and CSH supported fungal growth, although CSH promoted higher biomass formation while glucose favored cordycepin biosynthesis. The kinetic model demonstrated that the growth of engineered A. oryzae was well described by the logistic growth model (R² > 0.88). The cordycepin production profiles were well fitted by the Luedeking–Piret model (R² > 0.99), indicating a mixed growth-associated product with kinetic constants α and β representing growth-associated and non-growth-associated production, respectively. Overall, the developed kinetic model provides a quantitative framework for describing cell growth, substrate utilization, and cordycepin formation, offering guidance for process optimization and scale-up of cordycepin production in engineered fungal systems. Full article

The global functional food market continues to expand, and edible mushrooms are emerging as high-value ingredients due to their rich nutritional profile, particularly their high protein content, balanced amino acid composition, and dietary fiber. This growing industrial interest is reflected in the registration of more than 322 patents in the past five years according to the Derwent Innovation patent database. Recent advances include the integration of precision mycology (PM) and omics-based approaches, such as CRISPR-Cas9, into solid-state fermentation and submerged fermentation, enabling improvements in natural umami flavor and bioactive composition. Innovative products, including meat analogues with fibrous textures, functional beverages such as kombucha and juices, and fermented dairy products such as yogurts and cheeses, have been formulated to deliver prebiotic, antioxidant, and immunomodulatory properties. Future trends indicate a shift towards the production of high-value nutraceutical peptides and biomass, together with the adoption of artificial intelligence (AI) and the Internet of Things (IoT) to enhance bioreactor automation and scalability. Nevertheless, significant challenges remain, including regulatory constraints, the scarcity of clinical validation in humans, and the need for strict control over the bioaccumulation of heavy metals in mushroom-derived raw materials. Addressing these gaps will be critical for advancing regulatory frameworks, improving industrial standardization, and supporting the translational development of mushroom-based functional foods. Full article

We report on the isolation and comprehensive genomic and biochemical characterization of Aspergillus fumigatus VP2T, a thermophilic filamentous fungus recovered from Himalayan Forest soil with exceptional lignocellulolytic capacity. Whole-genome sequencing revealed a 32.1 Mb genome encoding 12,675 predicted genes, including an extensive repertoire of >300 carbohydrate-active enzymes (CAZymes). Notably, the genome harbors multiple auxiliary activity enzymes, including AA9-family lytic polysaccharide monooxygenases and several cellobiose dehydrogenases (CDHs), supporting oxidative–hydrolytic synergism during biomass degradation. Submerged fermentation using a cellulose–wheat bran–rice straw substrate induced high enzyme titers, including 33 U/mL endoglucanase and 131 U/mL CDH, exceeding activities commonly reported for both native and engineered fungal strains. Although exoglucanase (0.02 U/mL) and xylanase (14.22 U/mL) activities were comparatively modest, the strain VP2T demonstrated superior hydrolysis of untreated rice straw, achieving a 1.89-fold increase in saccharification efficiency relative to the commercial enzyme cocktail Cellic^® CTec2. Scanning electron microscopy confirmed extensive disruption of lignocellulosic architecture, consistent with enhanced enzyme accessibility and oxidative fiber loosening. Collectively, genomic evidence and functional assays identify A. fumigatus VP2T as a redox-optimized, moderately thermophilic biocatalyst suited for low-pH lignocellulose conversion. This study highlights the value of exploring thermophilic fungal biodiversity to discover native strains with inherent oxidative capacity, offering promising alternatives to pretreatment-intensive biorefinery processes and informing the rational development of tailored enzyme systems. Full article

Industries seek microorganisms capable of producing all types of cellulases, using low-cost substrate and under adequate process conditions, especially through submerged fermentation. Pleurotus ostreatus “L123” was evaluated as a potential microorganism for cellulase production, assaying total cellulolytic activity (FPase). Fermentation was carried out using a 14L bioreactor, inoculated with 10% (v/v) grown on potato dextrose broth for 4 days. Fermentation media was composed of defatted rice bran (50 g/L), glucose (5 g/L), corn steep liquor (5 g/L) and chloramphenicol (0.25 g/L). Aeration and agitation effects on enzymatic activity were evaluated using a central composite design (CCD) for FPase after 5 days of fermentation. The obtained model was statistically significant, with the interaction of both parameters also being significant and presenting a negative effect. Membrane ultrafiltration (150 kDa MWCO) led to an approximately 3-fold increase in specific activity of permeate (0.6441 vs. 0.2043 FPU/mg of protein), with retention of around 80% of protein content while maintaining enzymatic activity of permeate similar to unfiltered broth (0.0932 vs. 0.0923 FPU/mL). The maximum value obtained experimentally was 0.1444 FPU/mL, which is significantly lower in comparison to commercially used strains and consequently unfeasible for industrial use at current state. However, after further improvements and optimization, Pleurotus ostreatus “L123” can become an alternative for in situ cellulase production through submerged fermentation. Full article

Hypocrellin A (HA) represents a pharmaceutically important perylenequinone photosensitizer produced by Shiraia bambusicola. However, submerged fermentation remains constrained by filamentous morphological characteristics and inherent mass transfer limitations. Although microparticle-enhanced cultivation (MPEC) has demonstrated efficacy in filamentous fungal systems, the molecular mechanisms by which physical cues, such as microparticle-induced shear stress, reprogram fungal metabolism remain largely unexplored. This work systematically optimizes SiO₂-based MPEC parameters for S. bambusicola GDMCC 60438, including particle dimensions, temporal addition protocols, and solid loading. Mechanistic investigations integrated pellet morphology analysis, membrane lipid composition, intracellular redox status, energy/precursor markers, and RNA-seq transcriptomic profiling with qRT-PCR validation. Under optimized conditions (10% w/v SiO₂, 30 mesh, added at 6 h), HA yield reached 41.76 ± 5.02 mg/L, representing a 3.65-fold increase over controls. MPEC shifted morphology toward smaller, more porous pellets with denser internal structure, accompanied by increased membrane fluidity (unsaturated/saturated fatty acid ratio from 1.54 to 2.63), elevated ROS levels with antioxidant enzyme activation, and enhanced acetyl-CoA and ATP accumulation. Transcriptomic analysis identified 206 differentially expressed genes enriched in oxidative phosphorylation, carbon metabolism, and stress responses, with upregulation of PKS-related biosynthetic genes and major facilitator superfamily transporters. This work establishes an integrated mechanistic framework linking particle-induced morphological changes to metabolic reprogramming through oxidative stress and subsequent transcriptional activation of the HA biosynthetic pathway, providing rational design principles for MPEC strategies in filamentous fungi. Full article

In this work, a food-compatible bioprocess was evaluated for the production of yeast single-cell protein from mezcal agave bagasse. Bagasse was enzymatically hydrolyzed at 10% (w/v) solids (pH 4.8, 50 °C, 24 h) using commercial enzymes. The resulting liquid was clarified by activated charcoal adsorption and filtration to obtain a hydrolysate suitable for submerged fermentation. Enzymatic hydrolysis released reducing sugars in the range of 11–17 g/L. Saccharomyces cerevisiae was cultivated on the clarified hydrolysate under submerged conditions using both flask-scale and 2 L stirred-tank bioreactor experiments. Trials were performed at flask scale with initial sugars at 8, 17, and 50 g/L, and at 2 L stirred-tank bioreactor scale with initial sugars at 20.68 g/L (R1) and 16.30 (R2) g/L. At the flask scale, final biomass concentrations increased with initial sugar level. Values reached 6.18 ± 0.27, 8.02 ± 0.55, and 9.28 ± 0.10 g/L, while crude protein remained below 10% (3.40 ± 0.15 to 8.69 ± 0.09 g/100 g dry weight). In contrast, bioreactor cultivation resulted in higher protein enrichment, with protein contents over 40% under both oxygen regimes (41.71 ± 0.47 to 45.80 ± 0.43 g/100 g dry weight). Overall, the findings support enzymatic hydrolysis coupled with controlled submerged fermentation as a scalable approach for valorizing agave bagasse into protein-enriched yeast biomass. Full article

Widespread release of cyanide from industrial activities represents a significant environmental challenge due to its acute toxicity and adverse effects on biological systems. In response to this concern, this study focused on the production of rhodanese from Kocuria rhizophila under submerged fermentation conditions and the assessment of its relevance for cyanide detoxification applications. A soil-derived Gram-positive bacterium was isolated and identified as Kocuria rhizophila based on morphological traits, biochemical profile-based VITEK 2 analysis, and 16S rRNA gene sequencing. Preliminary screening confirmed rhodanese production with an activity of 0.968 RU/mL. Under cyanide-induced submerged fermentation, enzyme production followed a growth-associated pattern and reached maximal activity at 40 h under optimized conditions (35 °C, pH 8.0). Partial purification using sequential precipitation and chromatographic steps enhanced enzyme purity, and SDS–PAGE analysis of the final fraction revealed protein bands at approximately 40, 140, and 260 kDa. Biochemical characterization showed Km values of 33.9 mM for KCN and 19.7 mM for sodium thiosulfate, with a Vmax of ~5.6 µmol min⁻¹ mL⁻¹ for KCN and optimal activity at pH 7–8 and 35 °C. Functional assays demonstrated efficient cyanide detoxification, achieving >85% conversion of KCN, ~92% of NaCN, and 65–77% of Ca (CN)₂ within 60 min in vitro. Collectively, these findings demonstrate that Kocuria rhizophila represents a promising microbial source of rhodanese with efficient cyanide-detoxifying activity, highlighting its potential for biotechnological and environmental remediation applications. Full article

This study investigated the effect of low-cost carbon and nitrogen sources on fructosyltransferase (FTase) production by Aspergillus oryzae IPT-301, aiming to optimize the enzymatic synthesis of fructooligosaccharides (FOS), prebiotic compounds valued for their bifidogenic effects. FTase is a key enzyme in transfructosylation, the central step in FOS production. To reduce production costs, Very High Polarization (VHP) and Demerara (DM) sugars were evaluated as carbon sources, while sodium nitrate (NaNO₃), ammonium sulfate (NH₄)₂SO₄, and urea were tested as nitrogen sources. FTase production, both extracellular and intracellular, was conducted under submerged fermentation at 30 °C and 200 rpm for 72 h. DM sugar outperformed VHP, increasing extracellular and intracellular transfructosylation activity (A_T) by 2.3-fold and 2.1-fold, respectively. Among nitrogen sources, NaNO₃ was most effective in DM-containing media, yielding 1.6–2.0 times higher extracellular A_T and up to 4.7 times greater intracellular activity compared to other nitrogen sources. These findings suggest that the combination of DM sugar and NaNO₃ significantly enhances FTase yield, providing a cost-effective strategy for industrial-scale FOS production. Full article

Cellulases catalyze the hydrolysis of cellulose and can be produced through fermentation processes, such as sequential fermentation (SeqF), which combines submerged and solid-state fermentation. The objective of this study was to evaluate the production of cellulases (endoglucanase and β-glycosidase) by fungi of the genus Aspergillus using coffee husks as substrate. Three Aspergillus strains were evaluated, with A. japonicus URM5620 showing the highest endoglucanase (0.368 U mL⁻¹) and β-glucosidase (0.652 U mL⁻¹) activities by SeqF. Based on the complete factorial design 2², a 9-fold and 3-fold increase in the production of endoglucanase (3.44 U mL⁻¹) and β-glucosidase (2.12 U mL⁻¹), respectively, was observed. Both enzymes showed maximum activity at 60 °C and pH 5.0. The kinetic/thermodynamic parameters indicated a high affinity of the enzymes for their respective substrates and a high catalytic potential. In addition, the half-life and decimal reduction values demonstrate the good thermal stability of endoglucanase (t_1/2 = 8.82 ± 0.34 and D = 29.32 ± 1.13 h) and β-glucosidase (t_1/2 = 26.61 ± 0.74 and D = 88.38 ± 2.47 h) at 60 °C. The thermostability results indicate potential for use in the pretreatment of raw materials. Full article

The rare edible and medicinal mushroom Floccularia luteovirens faces challenges from limited wild resources and low triterpenoid yield in submerged fermentation. To address this, we systematically optimized the fermentation medium using one-factor-at-a-time experiments combined with Response Surface Methodology (RSM). Wheat flour, peptone, and KH₂PO₄ were identified as the optimal carbon, nitrogen, and inorganic salt sources, respectively. Subsequently, we developed and validated distinct, highly predictive mathematical models for intracellular (R² = 0.9989) and extracellular (R² = 0.9984) triterpenoid production. This yielded two optimized media: one designed to maximize intracellular accumulation (29.71 g/L wheat flour, 2.03 g/L peptone, 1.02 g/L KH₂PO₄), achieving a yield of 18.83 mg/g, and another tailored for high extracellular secretion (30.28 g/L wheat flour, 2.08 g/L peptone, 1.05 g/L KH₂PO₄), achieving a titer of 0.63 g/L. The experimental results for both targets closely matched the model predictions. Thus, this study not only significantly enhanced overall triterpenoid production but also delineated nutrient-specific strategies for targeting different product locales. The findings provide a reliable technical and theoretical foundation for the scalable and sustainable production of these bioactive compounds. Full article

The present study investigates the potential of olive mill wastewater (OMW), supplemented with expired commercial glucose syrup, as a sustainable substrate for the submerged cultivation of Tuber spp. wild mushrooms. OMW contains considerable quantities of phenolic compounds, making it both a challenging pollutant and a promising nutrient source. To assess fungal performance under increasing phenolic stress, culture media were prepared with varying OMW concentrations (0–75% v/v on agar; 0–50% v/v in liquid media), while glucose was adjusted to ~30 g/L using expired glucose syrup. A sequential experimental approach was followed, beginning with Petri dish screenings on substrate/strain selection (measuring the mycelial growth rate; Kr, mm/day), progressing to 25-day shake flask fermentations and subsequently scaling up the most promising strain (Tuber mesentericum) in a controlled stirred-tank bioreactor. Throughout cultivation, substrate consumption (glucose, phenolics), pH evolution and decolorization were evaluated, while the resulting biomass was analyzed for polysaccharides, β-glucans, proteins, lipids, fatty acids, antioxidants, phenolic acids and triterpenoids content. Results showed that increasing OMW concentration enhanced tolerance and metabolic activity in selected Tuber species, with T. mesentericum exhibiting the highest resilience and achieving comparable or higher biomass yields in OMW-based media than in glucose (control). Phenolic removal exceeded 60% in flasks and 50% in the bioreactor, confirming simultaneous bioremediation capacity. Bioreactor cultivation demonstrated efficient substrate utilization and biomass production, while OMW-grown biomass presented high lipid content, enriched with unsaturated fatty acids, high β-glucan levels and increased antioxidant and phenolic profiles. Overall, this study demonstrates that OMW (supplemented with expired glucose syrup) can serve as a cost-effective and environmentally beneficial substrate for Tuber biomass production with dietary and antioxidant properties, offering an alternative source to mushroom carposomes, as well as supporting the circular bioeconomy strategies within olive oil processing industries. Full article