Search Results (103)

The purpose of this study was to investigate the effect of different additives on the microbial composition, fermentation quality, and bacterial community structure of big-bale Leymus chinensis silage. An experiment was set up with four treatment groups: a control (C) group, Lacticaseibacillus rhamnosus (L) group, molasses (M) group, and L. rhamnosus + molasses (LM) group, with three replications per group, and L. chinensis silages were fermented for 20 and 40 days. The lactic acid, acetic acid, 1,2-propanediol, and propionic acid contents increased, and pH, butyric acid, 1-propanol, and ethanol contents decreased in the L, M, and LM groups compared to the C group. In the LM group, the number of lactic acid bacteria was the highest, while the pH was the lowest. Enterobacter and Paucibacter were the main dominant genera in the C group. The addition of L. rhamnosus and molasses increased the relative abundance of Lactobacillus, Weissella, and Enterococcus. Lactobacillus abundance correlated positively (p < 0.01) with Lactococcus, Enterococcus, and Weissella and correlated negatively with Enterobacter and Paucibacter. Conversely, Enterobacter and Paucibacter showed a strong positive correlation (p < 0.01, R = 0.55) during fermentation. Lactobacillus, Enterococcus, and Weissella were positively associated (p < 0.01) with acetic and lactic acid levels, while Enterobacter abundance was correlated positively (p < 0.05, R = 0.43) with 1,2-propanediol content. In summary, the addition of both L. rhamnosus and molasses improved the fermentation quality and bacterial community structure of big-bale L. chinensis silage. In addition to inhibiting harmful microorganisms, this combination improved the fermentation products of big-bale L. chinensis silage through microbial regulation. Full article

Background: Olive pomace, a byproduct of olive oil production, represents approximately 85% of the processed material and poses environmental risks when improperly discarded. Its composition is rich in polyphenols with potential for cosmetic use, especially in skin barrier care. Objective: To develop a natural extract rich in antioxidants from olive pomace using sustainable solvents (water and 1,3-propanediol) for skin barrier support. Methods: The phenolic composition and in vitro biological activities of the extracts were analyzed. Results: The extracts demonstrated a reducing capacity (15 to 33 mg GAE/g) and flavonoid content (4 to 5 mg QE/g). In addition, their antioxidant capacity was proven through the inhibition of the DPPH radical (7% to 91%) and ABTS (7% to 95%) and the reduction in oxidation in the beta-carotene/linoleic acid system (6% to 35%), presenting results superior to those of tocopherol acetate. The hydroxytyrosol and oleuropein compounds, ranging from 28 to 54 and 51 to 85 µg/mL, respectively, were quantified via HPLC. The extract with the highest levels of hydroxytyrosol and oleuropein was analyzed via UHPLC-QqTOF-MS, and 33 compounds were identified. This extract showed antiglycation activity (24% to 40%). The incorporation of this extract into a cosmetic emulsion resulted in sufficient antioxidant capacity to replace tocopherol acetate. Conclusions: The use of effective extraction techniques and nontoxic solvents ensures the sustainability and safety of the extract for application as a natural cosmetic ingredient, aiming to promote the health and integrity of the skin barrier. Full article

Biodiesel is one of the most important biofuels worldwide. Besides glycerol, the residual aqueous phase of the transesterification reaction (RAPTR) from the biodiesel industry contains a high concentration of methanol. Here, we propose using RAPTR as substrate for Clostridium beijerinckii Br21 to produce 1,3-propanediol (1,3-PDO). 1,3-PDO is a valuable chemical compound widely used in the production of polymers, cosmetics, and pharmaceuticals. To diminish the methanol content, we pretreated RAPTR by low-pressure evaporation, which minimized water evaporation and prevented other contaminants from being concentrated. We optimized the evaporation conditions by using a 2² central composite rotational design to establish optimal temperature and time of 55 °C and 51.3 min, respectively. Pretreated RAPTR diluted at 20% (v v⁻¹) with a nutrient solution allowed the bacterium to grow, but no glycerol was consumed. Supplementing the nutrient solution with 0.4 g L⁻¹ MgCl₂, defined in another experimental design, led the bacterium to consume glycerol and to produce 1,3-PDO. In the optimized conditions, pretreated RAPTR supplemented with MgCl₂ gave 2.78 ± 0.01 g L⁻¹ 1,3-PDO in higher yield (Y_{1,3-PDO/glycerol}) compared to the theoretical one, 0.61 and 0.50 g g⁻¹, respectively. This result is relevant for biodiesel biorefineries, which could implement the innovative and customized strategy proposed herein to obtain 1,3-PDO, a high-value-added product, from a glycerol- and methanol-rich residue. Full article

The sharp rise in the worldwide production of biodiesel has created an excess in the crude glycerol market, so it is essential to develop new added-value alternatives for crude glycerol. This paper describes a study on fermenting high concentrations of two types of medium-pure crude glycerol to solvents by Clostridium pasteurianum. The effect of media composition (iron, yeast extract, and vitamins) on solvents production was assessed by a full factorial design with pure glycerol. Granular activated carbon (GAC) adsorption was highly effective in removing impurities from crude glycerol. Following GAC pretreatment, fermentation of glycerol at initial concentration as high as 60 g L⁻¹ was possible, resulting in a butanol production of ~9 g L⁻¹. Based on these results, a batch fermentation with in situ gas stripping and pH controlled at ≥6.5 was shown to be the best alternative to enhance biomass growth, glycerol uptake, and solvent production. The combination of controlling pH in the early stages of fermentation with in situ butanol removal stabilised the metabolism of the strain and showed that the fermentation performance with crude glycerol is very similar to that of pure glycerol. With a notable uptake of glycerol (>83%), solvent production was >11 g L⁻¹ butanol (yield > 0.21 g g⁻¹_{glycerol consumed}) and >6 g L⁻¹ 1,3-propanediol (yield > 0.13 g g⁻¹_{glycerol consumed}). Setting the fermentation conditions to achieve a high uptake of high levels of glycerol with a similar product distribution is of great interest for the viability of the industrial processing of crude glycerol into chemicals via biological conversion. Full article

Propionic acid (PA) is an important organic acid with applications in food preservation, feed additives, and bio-based chemical production. While industrial PA is mostly derived from petrochemical processes, sustainable microbial alternatives are gaining attention. In this study, we explored a co-fermentation strategy using lactic acid bacteria (LAB) with complementary metabolic capabilities to enhance PA biosynthesis via the 1,2-propanediol (PDO) pathway. Genome-based screening identified a metabolic division between strains capable of producing PDO (e.g., Carnobacterium maltaromaticum IBB3447) and those converting PDO to PA (e.g., Levilactobacillus brevis IBB3735). Notably, we discovered that C. maltaromaticum IBB3447 is capable of PDO 24 biosynthesis, a function previously undescribed in this species. Phenotypic assays confirmed glycerol metabolism and acid tolerance among strains. In co-culture fermentation trials, the highest PA concentration (6.87 mM) was achieved using simultaneous fermentation in a fructose–sorbitol–glucose (FRC-SOR-GLC) medium, accompanied by prior PDO accumulation (up to 13.13 mM). No single strain produced PA independently, confirming that metabolic cooperation is required. These findings reveal a novel LAB-based bioprocess for sustainable PA and PDO production, using cross-feeding interactions and the valorization of industrial waste streams. The study supports future optimization and scale-up for circular bioeconomy applications. Full article

Despite the potential of film dressings for wound healing, many formulations lack an optimized design in order to ensure that the ingredients were carefully chosen to increase the product’s efficacy and stability, while also ensuring the patient’s comfort during the treatment. Moreover, commercially available film dressings do not contain herbal extracts or other active substances with wound healing properties, highlighting a gap in the market and the need for further research in this direction. The aim of this work was the development and optimization of a bio-inspired formulation of a complex herbal extract-loaded film-dressing to be used in wound care, using the quality by design approach. After setting the quality target product profile with the critical quality attributes and undergoing the risk assessment, the design of experiments was implemented. All the selected ingredients were biodegradable, aligning with the current need for a natural approach, based on their biocompatibility and reduced environmental impact. A D-optimal experimental plan was used, in which the types and concentrations of film-forming agents and plasticizers were varied: xanthan gum, acacia gum, sodium carboxymethylcellulose and glycerol, 1,3-propanediol, and xylitol, respectively. All formulations contained polyvinyl alcohol and a previously studied complex herbal extract. The films were characterized in terms of uniformity of mass, film thickness, swelling degree, folding endurance, adhesive, and mechanical properties. The optimized formulation was achieved by maximizing the swelling degree, adhesive properties, hardness, deformation at target, and elongation at break. The optimized film was characterized, and the in vitro total polyphenolic content release from the film was evaluated. Following the understanding of the influences of the formulation factors on the film characteristics, the composition of the optimized film-dressing was determined as follows: 5% polyvinyl alcohol, 0.25% xanthan gum, 10% glycerol, and 20% complex herbal extract. The optimized film exhibited high swelling degree (627.28%), high adhesive properties (adhesive force of 28.00 g and adhesiveness of 0.20 mJ), high elasticity (deformation at target of 29.80%, and elongation at break of 106.90%), as well as good mechanical properties (hardness of 2616.00 g), which are suitable characteristics for use on wounds. Moreover, the optimized film-dressing exhibited a sustained release, with a maximum release of polyphenols of 88.00% after 8 h. Full article

Due to limited fossil resources and climate change, biotechnological processes converting renewable resources into industrial raw materials are increasingly important. Many of these processes require yeast extract for microorganism growth, a high-cost factor. Therefore, the use of inexpensive, protein-rich agricultural raw materials as a source of nutrients is desirable. However, their usage usually results in lower product concentrations and productivity in the fermentation process. This work investigates the nutritional requirements for the production of L-lactic acid using Lactobacillus casei ATCC 393 and 1,3-propanediol using Clostridium butyricum DSM 25047, aiming to replace complex nutrient sources with hydrolyzed protein-rich agricultural raw materials. In the production of 1,3-propanediol, yeast extract was largely (80%) replaced by rapeseed meal hydrolyzate, achieving the same final product concentration and maximum productivity. In the production of L-lactic acid, rapeseed meal hydrolyzate supplemented with B vitamins, mineral salts, cysteine, and tryptophan replaced yeast and meat extracts, achieving the same final product concentration with comparable maximum productivity. Full article

In this study, we optimized the initial concentrations of glycerol and (NH₄)₂SO₄ to enhance 1,3-propanediol (1,3-PDO) production by Clostridium beijerinckii strain Br21. A central composite rotational design (CCRD) was employed, varying glycerol concentrations between 158 and 441 mmol L⁻¹, and (NH₄)₂SO₄ concentrations between 4.4 and 25.8 mmol L⁻¹. The CCRD identified optimal conditions at 441.42 mmol L⁻¹ for glycerol and 25.8 mmol L⁻¹ for (NH₄)₂SO₄. The optimized medium resulted in a 112% increase in 1,3-PDO production compared to the original medium. Analysis of NH₄⁺ and SO₄²⁻ ions under optimal conditions revealed a higher consumption of NH₄⁺ than SO₄²⁻. Furthermore, a quantitative gene expression analysis revealed that while the expression of genes responsible for glycerol uptake and ATP sulfurylase remained unchanged, the expression of the dhaM gene, which encodes the oxidative phosphoenolpyruvate:dihydroxyacetone phosphotransferase, increased approximately 6-fold. In the reductive pathway, the expression of the dhaB1 gene, encoding glycerol dehydratase, and the dhaT gene, encoding 1,3-propanediol dehydrogenase, increased 2.5- and 5-fold, respectively. The upregulation of these genes supports the hypothesis that the optimal concentrations of glycerol and (NH₄)₂SO₄ enhance the 1,3-PDO production by C. beijerinckii Br21. Full article

The oxidation of 1,2-propanediol (1,2-PDO) under alkaline heterogeneous catalysis can be optimized to produce lactic acid, a valuable commodity chemical. In this study, Pd nanoparticles supported on various metal oxides (CeO₂, CuO, ZrO₂, ZnO, SnO₂) were synthesized via a wet-chemistry method. Furthermore, CeO₂-supported Pd nanoparticle catalysts were prepared using different reduction methods. The catalytic performance for the selective oxidation of 1,2-PDO was evaluated using a range of characterization techniques. Under optimal conditions (120 °C, 1.0 MPa O₂ pressure, 2 h reaction time, and a NaOH/1,2-PDO molar ratio of 3.0), a high lactic acid yield of 62.7% was achieved. Single-factor experiments revealed that lactic acid selectivity decreased with prolonged reaction time. Conversely, increasing temperature, NaOH concentration, and O₂ pressure initially enhanced lactic acid selectivity, but further increases resulted in a decline. Physicochemical characterization revealed that different supports and reduction methods affect the basicity of the catalyst, which subsequently influences the selectivity of the target product, lactic acid. Full article

This study evaluates the efficiency of 20 Natural Deep Eutectic Solvents (NADES) formulations for extracting curcuminoids and other bioactive compounds from turmeric and emphasize their ability to preserve and enhance antioxidant, antimicrobial, antidiabetic, and skin depigmentation effects. The NADES formulations, prepared using choline chloride (ChCl) combined with sugars, carboxylic acids, glycerol, amino acids, urea, polyols, and betaine, were assessed for their extraction efficiency based on the total phenolic content and curcumin concentration. Fourier transform infrared spectroscopy was employed to characterize the synthesized NADES and confirm their chemical composition. Bioactivity evaluations included antioxidant assays (ABTS and DPPH), antidiabetic tests (α-amylase inhibition), antimicrobial assays, and skin depigmentation (tyrosinase inhibition). The results demonstrated that NADES significantly enhanced the extraction efficiency and bioactive properties of turmeric extracts compared to water as a conventional green solvent. NADES 18 (ChCl/1,2-propanediol/water 1:1:1) and NADES 19 (glycerol/betaine/water 1:1:3) exhibited the highest extraction yields, with curcumin concentrations of 30.73 ± 1.96 mg/g and 31.70 ± 2.02 mg/g, respectively, outperforming water (26.91 ± 1.72 mg/g), while NADES 17 (ChCl/1,2-propanediol/water 0.5:3:0.5:5) and NADES 20 (glycerol/lysine/water 1:1:3) exhibited the most potent antioxidant activity. Furthermore, NADES 14 (ChCl/lactic acid/water 1:2:5) demonstrated the strongest tyrosinase inhibition (98.7%), supporting its potential for skin-brightening applications, including notable α-amylase inhibition exceeding 90%. This study aligns with the principles of green chemistry, as NADES are effective and sustainable solvents for natural product extraction. The presenting benefits of improved extraction efficiency and enhanced bioactivities position NADES as a promising and eco-friendly approach for developing efficient bioactive compound extraction methodologies. Full article

Due to the growth of biodiesel production, utilization of the glycerol formed as a by-product is still of considerable importance. This study is devoted to a novel approach for glycerol hydrogenolysis with use of in situ generated Cu-ZnO catalysts. The main product formed is 1,2-propanediol, with the by-products being lactic acid and ethylene glycol. The Cu-ZnO catalysts are characterized by AAS, XRD, XPS, SEM, TEM, EDX, BET, and chemisorption N₂O. The proportion of ZnO turns out to have a significant effect on the activity and selectivity of the catalyst formed. Increasing the ZnO content enables one to obtain more dispersed, active, selective, and agglomeration-resistant catalysts. The transition from monometallic Cu catalysts to Cu-ZnO with a ZnO content of 65 wt% allows one to increase selectivity from 74 to 86%, TOF from 0.136 to 0.511 s⁻¹, and S_Cu from 1.9 to 7.1 m²/g-Cu. The morphology of the synthesized Cu-ZnO catalysts resembles the structure of oxide/metal inverse catalysts. Full article

Biotemplating technique allows the synthesis of catalysts, recreating the sophisticated structure of nature templates. In this work, some biotemplated TiO₂ semiconductors were synthesized using Olea europaea leaves as templates. Then, g-C₃N₄ was coupled to materials to later incorporate Pt on the surface or as dopant in the structure to evaluate the efficiency of the solids in two photocatalytic applications to valorize biomass: hydrogen production through glycerol photoreforming, and photoacetalization of cinnamaldehyde with 1,2-propanediol. In glycerol photoreforming, the presence of Pt (superficial or dopant) enhanced hydrogen production, being Pt@AOLCN (a heterojunction containing biotemplated TiO₂, g-C₃N₄, and Pt) the system that exhibited the highest efficiency (3053.4 µmol·g_cat⁻¹·h⁻¹). For photoacetalization, while Pt reduced cinnamaldehyde conversion, it improved selectivity when incorporated on TiO₂. Notably, carbon nitride (CN) exhibited the highest yield after 16 h of testing. The study emphasizes the importance of tailoring catalyst selection to specific reactions, as efficiency is closely tied to the structural and chemical properties of the materials. These findings contribute to the development of efficient photocatalysts for sustainable biomass valorization processes. Full article

The selective hydrogenolysis of glycerol to 1,3-Propanediol (1,3-PDO) presents a sustainable approach, leveraging a bio-renewable feedstock and significantly enhancing the economic viability of biodiesel production. However, the limited selectivity toward 1,3-PDO in glycerol hydrogenolysis has hindered its widespread adoption on an industrial scale. In this work, we synthesized a series of Pt/WO₃–Al₂O₃ catalysts using a simple wetness sequential impregnation method. Comprehensive characterization and kinetic studies revealed that the surface tungsten content of the catalyst exerted a critical and multifaceted influence on the catalytic performances. Under optimal conditions, glycerol could be selectively converted to 1,3-PDO with a yield of 43% in a fixed-bed continuous flow reactor. Furthermore, a plausible reaction mechanism for glycerol hydrogenolysis was proposed based on the correlations between catalyst structure and catalytic performance. Full article

Despite efforts to prevent atypical ensiling conditions, such as delayed ensiling or sealing, these issues frequently occur in practice. This study aimed to investigate the effects of delayed ensiling (forage held for 24 h) and sealing, along with inoculation using a blend of Lentilactobacillus buchneri and Lactococcus lactis, on the characteristics of the resulting silages. Whole-plant maize (Zea mays L.) was treated with or without a commercial inoculant and ensiled (36% dry matter) for 60 days in 3.0 L glass containers. The forage was either ensiled immediately or subjected to a 24 h delay before ensiling. During the delay, the forage was either covered or left uncovered. Each treatment was replicated five times. All data were analyzed using the MIXED procedure of SAS statistical software (version 9.4; SAS Institute Inc., Cary, NC, USA). Delaying the ensiling process by 24 h worsens fermentation parameters, significantly increases dry matter (DM) losses (p < 0.01), and significantly reduces aerobic stability and the hygienic quality of the silage (p < 0.01), as evidenced by higher concentrations of undesirable fermentation products and elevated yeast and mold counts. The inoculation has a significant impact on both forage before ensiling and the characteristics of the resulting silage. Maize forage treated with inoculant showed a lower temperature increase by 8.2–8.1 °C (p < 0.01) when delayed for 24 h before ensiling. In silages, it also resulted in a reduced pH (p < 0.01); increased concentrations of lactic acid; acetic acid; and 1,2-propanediol (p < 0.01); and decreased levels of negative fermentation indicators such as ammonia-N, alcohols, and butyric acid (p < 0.01) During both the fermentation and aerobic exposure periods, inoculated silages exhibited up to 36% and 2.6 times lower (p < 0.01) dry matter loss, while suppressing the growth of yeasts and molds by up to 2.6 and 3.1 times (p < 0.01), respectively, compared to non-inoculated silages. The results of this study support the recommendation to minimize the duration of aerobic exposure of fresh forage during silo filling and to use LAB-based inoculants. Full article