Search Results (95)

Against the backdrop of the green circular economy, the exploration of reliable and sustainable applications of lignocellulosic biomass (LCBM) has emerged as a critical research frontier. The utilization of LCBM as a ruminant roughage source offers a promising strategy to address two pressing issues: the “human-animal competition for food” dilemma and the environmental degradation resulting from improper LCBM disposal. However, the high degree of lignification in LCBM significantly restricts its utilization efficiency in ruminant diets. In recent years, microbial pretreatment has gained considerable attention as a viable approach to reduce lignification prior to LCBM application as ruminant feed. White-rot fungi (WRF) have emerged as particularly noteworthy among various microbial agents due to their environmentally benign characteristics and unique lignin degradation selectivity. WRF demonstrates remarkable efficacy in enzymatically breaking down the rigid lignocellulosic matrix (comprising lignin, cellulose, and hemicellulose) within LCBM cell walls, thereby reducing lignin content—a largely indigestible component for ruminants—while simultaneously enhancing the nutritional profile through increased protein availability and improved digestibility. Solid-state fermentation mediated by WRF enhances LCBM utilization rates and optimizes its nutritional value for ruminant consumption, thereby contributing to the advancement of sustainable livestock production, agroforestry systems, and global environmental conservation efforts. This review systematically examines recent technological advancements in WRF-mediated solid-state fermentation of LCBM, evaluates its outcomes of nutritional enhancement and animal utilization efficiency, and critically assesses current limitations and future prospects of this innovative approach within the framework of circular bioeconomy principles. Full article

In view of the growing global need for sustainable protein sources, this study explores the utilization of short-chain fatty acids into single-cell protein using the non-conventional yeast Cyberlindnera jadinii. Short-chain fatty acids can be sustainably produced via anaerobic digestion of organic waste, presenting a promising fermentation substrate for a circular bioeconomy. Cyberlindnera jadinii is demonstrated to be capable of growing on acetate, propionate and butyrate as both a carbon and energy source without strong inhibition. Bioprocess development was conducted in stirred tank bioreactors, where a fed-batch pH-stat bioprocess led to improved efficiency without substrate inhibition. The highest titer of 31.3 ± 1.0 g/L, rate of 0.67 ± 0.02 g/L/h and yield of 0.36 ± 0.01 g/g was achieved with propionate. The resulting biomass contained 41.3% crude protein, and 17.3% crude lipids with 81% unsaturated fatty acids. In contrast to acetate and butyrate, propionate as a substrate led to accumulation of 37% odd-chain fatty acids with titer, rate and yield of 1.74 ± 0.06 g/L, 0.037 ± 0.001 g/L/h and 0.020 ± 0.001 g/g. These findings confirm that short-chain fatty acids are viable fermentation substrates not only for single-cell protein, but also unsaturated and odd-chain fatty acid production with Cyberlindnera jadinii. Full article

The global chemical pigment industry faces environmental challenges despite its economic importance. This study investigates the potential of Kocuria sediminis AS04, an airborne isolate, for sustainable pigment and biomass production. Microbial kinetics were evaluated under Taguchi design conditions with temperature (30, 34, and 38 °C), stirring speed (110, 120, and 130), and pH (6.0, 6.5, and 7.0), measuring biomass through dry weight and viable cells, pigment production, and identification of its pigment using UPLC-MS/MS; structural and chemical characterization of biomass was conducted using SEM and FTIR. Among the tested conditions, the treatment at 30 °C, 130 rpm, and pH 6.5 resulted in the highest CFU count (5.7 × 10⁹ CFU mL⁻¹) and the greatest biomass yield (13.3 g L⁻¹). In contrast, the highest pigment yield (0.0016 mg g⁻¹) was obtained at 38 °C, 130 rpm, and pH 6.0. Cell extracts identified key carotenoid compounds such as β-cryptoxanthin, Rhodovibrin, and other precursors. These findings highlight the potential of Kocuria sediminis AS04 as a sustainable source of pigments and valuable bioproducts, offering promising alternatives for eco-friendly industrial applications. Full article

The valorization of plant biomass is one of the main strategies for sustainable development. However, its use as energy, biofuels, fertilizers, value-added products, or even food is severely affected by the complexity of the plant cell wall. Therefore, the evaluation of fungi with high production of lignocellulolytic enzymes capable of efficiently degrading these substrates constitutes a viable, clean, and eco-friendly solution, allowing, for example, an increase in the digestibility and nutritional quality of alternative animal feed sources. For these reasons, the present study evaluated the ability of the mutant strain Trichodema viride M5-2 to improve the nutritional composition of the forage legumes Lablab purpureus and Mucuna pruriens through solid-state fermentation. Endo- and exoglucanase cellulolytic activity was assessed, as well as the effect of fermentation on the fiber’s physical properties and chemical composition. Molecular changes in the structure of plant fiber were analyzed using infrared spectroscopy. Increased production of the cellulolytic complex of the enzymes endoglucanase (3.29 IU/mL) and exoglucanase (0.64 IU/mL) was achieved in M. pruriens. The chemical composition showed an increase in true protein and a decrease in neutral fiber, hemicellulose, and cellulose, with a consequent improvement in nutritional quality. Fiber degradation was evident in the infrared spectrum with a significant decrease in the signals associated with cellulose and, to a lesser extent, with lignin. It can be concluded that the mutant strain T. viride M5-2 produced chemical, physical, and molecular changes in the fibrous and protein fractions of L. purpureus and M. pruriens through SSF, which improved their nutritional value as an alternative feed for animal nutrition. By promoting the use of this fungus, the nutritional quality of this source is increased through an effective and eco-friendly process, which contributes to mitigating the environmental impact of food production, in accordance with sustainability objectives and the need for more responsible agricultural practices. Full article

The low availability of phosphorus (P) in soil has become a critical factor limiting crop growth and agricultural productivity. This study aimed to isolate and evaluate a bacterial strain with high phosphate-solubilizing capacity to improve soil phosphorus utilization and promote crop growth. A phosphate-solubilizing bacterium, designated as YS-13, was isolated from farmland soil in Henan Province, China, and identified as Brevibacillus laterosporus based on morphological characteristics, physiological and biochemical traits, and 16S rDNA sequence analysis. Qualitative assessment using plate assays showed that strain YS-13 formed a prominent phosphate solubilization zone on organic and inorganic phosphorus media containing lecithin and calcium phosphate, with D/d ratios of 2.28 and 1.57, respectively. Quantitative evaluation using the molybdenum–antimony colorimetric method revealed soluble phosphorus concentrations of 21.24, 6.67, 11.73, and 17.05 mg·L⁻¹ when lecithin, ferric phosphate, calcium phosphate, and calcium phytate were used as phosphorus sources, respectively. The fermentation conditions for YS-13 were optimized through single-factor experiments combined with response surface methodology, using viable cell count as the response variable. The optimal conditions were determined as 34 °C, 8% inoculum volume, initial pH of 7.55, 48 h incubation, 5 g L⁻¹ NaCl, 8.96 g L⁻¹ glucose, and 8.86 g L⁻¹ peptone, under which the viable cell count reached 6.29 × 10⁸ CFU mL⁻¹, consistent with the predicted value (98.33%, p < 0.05). The plant growth-promoting effect of YS-13 was further validated through a pot experiment using Triticum aestivum cv. Jinchun 6. Growth parameters, including plant height, fresh biomass, root length, root surface area, root volume, and phosphorus content in roots and stems, were measured. The results demonstrated that YS-13 significantly enhanced wheat growth, with a positive correlation between bacterial concentration and growth indicators, although the growth-promoting effect plateaued at higher concentrations. This study successfully identified a high-efficiency phosphate-solubilizing strain, YS-13, and established optimal culture conditions and bioassay validation, laying a foundation for its potential application as a microbial inoculant and providing theoretical and technical support for reducing phosphorus fertilizer inputs and advancing sustainable agriculture. Full article

This study demonstrates that Bacillus subtilis GDAAS-A32-derived postbiotics (BSP) enhance yogurt production by optimizing lactic acid bacteria (LAB) viability and functionality. BSP enhanced the growth kinetics and biomass accumulation of Streptococcus thermophilus and Lactobacillus bulgaricus in both an anaerobic and aerobic pure system. The addition of BSP significantly increased the viable cell counts of S. thermophilus and L. bulgaricus, milk-clotting activity, sensory properties, and extracellular polysaccharide content and improved the rheological properties. Moreover, BSP elevated viable counts of S. thermophilus and L. bulgaricus to 6.18 × 10⁸ CFU/g and 1.03 × 10⁸ CFU/g, respectively, by day 7—representing 11.3-fold and 9.3-fold increases versus controls at 20% supplementation. Metabolomic signatures confirmed peptidoglycan reinforcement and flavor enhancement. Mechanistically, BSP supplementation might reduce urate and H₂O₂ toxicity through NH₃-mediated proton neutralization and oxygen scavenging, while establishing a pyrimidine salvage network and redirecting one-carbon metabolism, resulting in enhanced stress tolerance and significant improvements in bacterial viability. Full article

This study aimed to identify kiwi kefir-like beverages with high levels of viable probiotic cells and low levels of calories, acids, and alcohol. To achieve this, microbiological and chemical characterizations were conducted on beverages inoculated with varying amounts of kefir grains (GW) and incubated at different agitation speeds (A), following a second-order orthogonal factorial design. For each experimental condition, three 24-h batch cultures were performed using three successive passages of kefir grains. Higher GW levels promoted greater nutrient consumption and metabolite production. However, an intermediate GW (1.80 g) resulted in the highest growth of lactic acid bacteria (LAB), acetic acid bacteria (AAB), yeasts, and free biomass in the fermented medium. Optimal agitation levels also enhanced nutrient consumption, free biomass, and metabolite pro-duction. AAB and yeast counts increased with higher agitation speeds, while LAB counts de-creased. Three beverages, produced during the second (A = 86 rpm, GW = 2.81 g) and third (A = 38 rpm, GW = 2.60 g; A = 86 rpm, GW = 1.80 g) kefir grain passages, exhibited LAB and yeast counts above 10⁶; CFU/mL, along with low total sugar and ethanol concentrations. These beverages may be considered suitable as potentially probiotic, low-alcohol, and low-calorie functional drinks. Full article

Eco-friendly pest management solutions are acknowledged as a crucial element in shaping the future of agriculture through sustainable practices. Achieving the maximum viable cell concentration while being cost-effective is the main goal of the downstream processing for efficient biomass-based microbial biopesticide production. The purpose of this study was to determine the effectiveness of chitosan flocculation in recovering bacterial Bacillus sp. BioSol021 biomass from broth cultivated using fruit juice industrial effluent as a medium, with the hypothesis of the synergistic effect of microbial and biopolymer components in phytopathogen suppression. Second-order polynomial models were used to calculate the influence of chitosan concentration and mixing speed on flocculation efficiency, settling velocity, and antibacterial activity against Aspergillus flavus (i.e., the inhibition zone diameter). The response surface approach, followed by desirability function optimization and the genetic algorithm were applied. The optimal values achieved in this study were 97.18%, 0.0369 mm/s, and 74.00 mm for flocculation efficiency, settling velocity, and inhibition zone diameter, respectively. The obtained results suggest that chitosan can be used as a flocculation agent for effective downstream processing, but also has a positive effect on the final product antimicrobial activity. Full article

Xanthan is a highly relevant commercial microbial biopolymer. Its production occurs in two steps: the bacterium is cultivated in a nitrogen-rich medium for cell multiplication, and the obtained biomass is used as an inoculum for the polymer production phase. Different media compositions for cell growth were investigated, seeking to reduce or replace the peptone used in the standard medium. Peptone (P), yeast extract (YE), and rice parboiling water (RPW) concentration combinations were tested in cultivating Xanthomonas arboricola pv. pruni 101. A CRD 2³ design, performed in a shaker, was used to assess the effects of independent variables on xanthan pruni microbial growth, N consumption, yield, viscosity, pseudoplasticity, and xanthan mineral content. After 24 h an increase in N was observed, without any significant impact on cell growth. Xanthan yield increased as a result of the alternative treatments, with P and YE influencing positively. However, T1, with the lowest levels of P, YE, and RPW increased viscosity and pseudoplasticity of xanthan pruni. RPW increased phosphorus, silicon, calcium, and magnesium, and P and YE increased potassium. These results indicate that partial replacement of P by RPW and YE is an economically viable and sustainable approach for the xanthan pruni production. Full article

Saccharomyces cerevisiae var. boulardii is a probiotic yeast widely recognized for its ability to enhance gut health and modulate a host’s microbiome. However, there are limited data on its large-scale cultivation in stirred tank bioreactors and subsequent downstream processing into a functional probiotic product. Different recipe formulations were evaluated and the recipe with the highest biomass yield and lowest process time was selected. Once the optimised batch was validated in the replicate batches, the statistical analysis indicated a high level of reproducibility, with low variability across key performance indicators such as biomass concentration (unit), CFU production (CFU.mL⁻¹), and substrate utilization efficiency (g.g⁻¹). The mean growth age in the bioreactor was 25.33 ± 1.16 h, with a CV of 4.56%, indicating minimal deviation between batches. Similarly, the final viable concentration exhibited a mean of 1.46 × 10⁸ CFU.mL⁻¹ with a CV of 11.68%, remaining within an acceptable range for biological processes, while the final biomass concentration had the lowest variability (CV of 3.94%) and a 95% CI of 12.134–13.266 g.L⁻¹, highlighting the accuracy and consistency of the process. Productivity indicators, including cell productivity (growth time—biomass) and YPP (biomass), maintained low CV values (3.933% and 3.389%, respectively), reinforcing process efficiency and stability. The overlapping 95% confidence intervals across batches further confirmed that no statistically significant deviations existed, ensuring minimal batch-to-batch variability, and validating the scalability and robustness of the fermentation process. These findings provide strong evidence for the feasibility of large-scale probiotic yeast production that meets industrial production standards. The final freeze-dried product retained an 81% viability post-exposure to simulated gastrointestinal conditions, meeting WHO probiotic viability standards. These findings establish a scalable, optimized process for probiotic yeast production, with potential applications in biopharmaceutical manufacturing and functional food development, as confirmed by the techno-economic evaluations performed using SuperPro Designer^®. Full article

Spirulina, a cyanobacterial biomass, is renowned for its high protein content and bioactive compounds, making it a promising candidate for health-promoting applications. This study explores the ultrasound-assisted deep eutectic solvent (DES) extraction technique for isolating antioxidants and anticancer proteins from Spirulina biomass, aiming to enhance extraction efficiency and preserve protein bioactivity. The extraction process was optimized using response surface methodology (RSM), varying parameters such as biomass concentration, sonication amplitude, and extraction duration. The optimized extraction conditions—5% biomass concentration, 40% sonication amplitude, and 22-minute extraction—achieved a high protein yield of 80.62%, with a protein concentration of 442.88 mg/g extract and an essential amino acid content of 39.91%. The extracted proteins exhibited remarkable bioactivity, including strong antioxidant properties, with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of 0.25 mg GAE/g, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging activity of 0.58 mg TE/g, and ferric reducing antioxidant power (PFRAP) of 9.63 mg gallic acid equivalent (GAE)/g. Additionally, the protein extract displayed selective cytotoxicity against colorectal cancer cell lines, with half-maximal inhibitory concentration (IC₅₀) values of 10.25 mg/mL for Caco-2 and 15.40 mg/mL for HT-29 cells, while maintaining low toxicity towards normal Vero cells. Apoptosis rates of 70.43% in Caco-2 and 51.33% in HT-29 cells further confirm the anticancer potential of the extract. The functional properties of the extracted protein, including high foaming capacity (100%), emulsifying capacity (94.05%), and digestibility (85.77%), underscore its potential for diverse applications in food, pharmaceutical, and nutraceutical industries. This eco-friendly and efficient extraction approach aligns with sustainable development goals and offers a viable strategy for harnessing Spirulina’s bioactive potential. Full article

The use of agro-industrial by-products and processing residues, which are rich in carbohydrates, proteins, and lipids, in the production of lipases allows the sustainable use of these residues, reducing environmental impacts. In this study, the immersion water of lentils, soybeans, and textured soy protein was evaluated as carbon and nitrogen sources in the production of whole-cell lipases, and the resulting biomass was used in the hydrolysis of residual soybean oil with conventional heating and ultrasound. The results showed that the best culture medium was the one with 50% textured soybean protein, reaching values of 149.04 U/g of hydrolytic activity, 12.92 g/L of biomass concentration, 144.17 U of total biomass activity, and specific and volumetric productivities of 2.07 U/g·h and 20.02 U/L·h, respectively. The positive effect of adding soybean frying oil to the crop was observed, which increased cell production and hydrolytic activity. The biomass obtained showed potential for the ultrasound-assisted hydrolysis of vegetable oils, reaching approximately 43.36% hydrolysis in 7 h of reaction, with an initial rate of 31.03 mmol/h. It is concluded that soybean protein processing water is a viable candidate to replace traditional nitrogen sources, being an economically attractive alternative due to its wide generation in restaurants. Full article

Background/Objectives: The viral pandemic caused by the SARS-CoV-2 virus has affected millions of people. However, it was noticed that high mortality was often a result of bacterial co-infections. One of the main pathogens responsible for secondary infections in patients with viral respiratory tract infections, including COVID-19, is Staphylococcus aureus. In recent years, the number of infections caused by drug-resistant strains of S. aureus has been growing rapidly, often exceeding the number of infections caused by antibiotic-sensitive strains. In addition, biofilm-related infections are more difficult to treat due to the lower sensitivity of biofilm structure to antibiotics. Bacteriophages are seen as alternative treatment of bacterial infections. Therefore, in our work, we have analyzed the efficacy of three Kayviruses against S. aureus strains isolated from COVID-19 patients. Methods: We analyzed the ability of tested phages to remove S. aureus biofilm both from polystyrene plates as well as from the surface of pulmonary epithelial cells. Results: We have observed that tested Kayviruses had a broad host range. Furthermore, phages were able to effectively reduce biofilm biomass and number of viable cells in pure culture. During our research, none of the tested phages was shown to have a negative effect on cell viability and were able to inhibit the negative effect S. aureus had on cell condition. Conclusions: Our results show tested phages were effective in reducing the biofilm of S. aureus strains isolated from COVID-19 patients, had no adverse effect on lung epithelial cell viability. Therefore, it should be recognized that the properties of three studied Kayviruses give them an advantage in the selection of phages for treatment of staphylococcal infections. Full article

A national energy crisis has emerged in South Africa due to the country’s increasing energy needs in recent years. The reliance on fossil fuels, especially oil and gas, is unsustainable due to scarcity, emissions, and environmental repercussions. Researchers from all over the world have recently concentrated their efforts on finding carbon-free, renewable, and alternative energy sources and have investigated microbiology and biotechnology as a potential remedy. The usage of microbial electrolytic cells (MECs) and microbial fuel cells (MFCs) is one method for resolving the problem. These technologies are evolving as viable options for hydrogen and bioenergy production. The renewable energy technologies initiative in South Africa, which is regarded as a model for other African countries, has developed in the allocation of over 6000 MW of generation capacity to bidders across several technologies, primarily wind and solar. With a total investment value of R33.7 billion, the Eastern Cape’s renewable energy initiatives have created 18,132 jobs, with the province awarded 16 wind farms and one solar energy farm. Utilizing wastewater as a source of energy in MFCs has been recommended as most treatments, such as activated sludge processes and trickling filter plants, require roughly 1322 kWh per million gallons, whereas MFCs only require a small amount of external power to operate. The cost of wastewater treatment using MFCs for an influent flow of 318 m³ h⁻¹ has been estimated to be only 9% (USD 6.4 million) of the total cost of treatment by a conventional wastewater treatment plant (USD 68.2 million). Currently, approximately 500 billion cubic meters of hydrogen (H₂) are generated worldwide each year, exhibiting a growth rate of 10%. This production primarily comes from natural gas (40%), heavy oils and naphtha (30%), coal (18%), electrolysis (4%), and biomass (1%). The hydrogen produced is utilized in the manufacturing of ammonia (49%), the refining of petroleum (37%), the production of methanol (8%), and in a variety of smaller applications (6%). Considering South Africa’s energy issue, this review article examines the production of wastewater and its impacts on society as a critical issue in the global scenario and as a source of green energy. Full article

The production of biodiesel from single-cell oils (SCOs) utilizing industrial wastes as feedstock presents an economically viable approach. To date, studies have rarely reported the utilization of vinasse combined with industrial glycerol for the production of SCO. This study aimed to assess the performance of a Rhodotorula toruloides strain in vinasse from ethanol distilleries supplemented with pure/raw glycerol as an affordable carbon feedstock for SCO production. Several critical factors, including the C/N ratio, the impact of impurities in the crude glycerol, the proper nitrogen source, and the effects of the vinasse compositions, were evaluated. The results showed that the incorporation of urea and raw glycerol increased the lipid content to 51.8 ± 1.6% and the lipid productivity to 0.034 ± 0.001 g L⁻¹h⁻¹. Elevated biomass (42.5 g L⁻¹) and lipid (11.0 g L⁻¹) concentrations indicated that impurities in the raw glycerol positively affected the growth and lipid accumulation of this strain. Notably, supplementing raw glycerol to the vinasse led to a 16.1% increase in biomass concentration and a 25.7% rise in lipid content, significantly enhancing lipid productivity by 59.6%. The fatty acid profile predominantly featured unsaturated fatty acids (96.8%), including high percentages of stearic acid (41.8 ± 2.6%), palmitic acid (21.8 ± 1.5%), and oleic acid (18.3 ± 1.4%), aligning with the standards for vegetable-oil-based biodiesel manufacture. Fed-batch strategies using pulse-feeding turned out to be less effective than the constant-flow feeding strategy with vinasse supplemented with raw glycerol, which achieved a higher lipid productivity of 0.30 g L⁻¹h⁻¹. Full article