Search Results (632)

We evaluated the algicidal properties of Bacillus Ba3 fermentation broth combined with clay for harmful algae bloom (HAB) control through in situ enclosure experiments in Suao Bay, China. It was indicated by the results that the combination significantly reduced HAB abundance, turbidity and phosphorous in water without affecting zooplankton and small fish. The treatment achieved 99.8% (Phase 1) and 100% (Phase 2, with sediment) removal rates for harmful dinoflagellates, primarily Prorocentrum donghaiense and Karenia mikimotoi, while demonstrating high taxonomic selectivity, allowing beneficial diatom populations such as Chaetoceros spp. to remain resilient. This synergy is attributed to clay acting as a physical carrier that brings adsorbed algicidal metabolites into direct, prolonged contact with algal membranes. This method shows promise for prolonged dinoflagellate control and may offer an economical and environmentally sound approach to HABs. More research is needed to establish its action on a wider scale in marine environments. Full article

To exploit wild mushroom resources in Tibet, a wild strain from Tibet was isolated, identified as Polyporust tuberaster, and domesticated for fruiting. Its growth characteristics were studied, and the antioxidant activities of the intracellular polysaccharides extracts (IPS) extracted from the mycelium and the extracellular polysaccharides extracts (EPS) from the fermentation broth were compared. The optimum carbon source for mycelial growth is fructose; the optimum nitrogen source is ammonium sulfate; the optimum pH is 5; and the optimum temperature is 20 °C. Both extracellular polysaccharide extracts (EPS) and Intracellular polysaccharide extracts (IPS) exhibited antioxidant capacity. The IC₅₀ values of EPS for scavenging OH·, ABTS·⁺, and DPPH· were 1.357, 0.125, and 0.683 mg/mL, respectively, while those of IPS were 0.595, 0.152, and 3.401 mg/mL. At 5 mg/mL, the FRAP values were 0.1582 (EPS) and 0.1708 (IPS). In cultivation, mycelium fully colonized bags after 32 d at 23 °C in darkness. Primordia formed within 12 d under 95% humidity with scattered light, and mature fruiting bodies developed after 24 d at 85–90% humidity and 20–23 °C, yielding an average fresh weight of 41.27 g per bag for the first flush. This study provides a basis for further development of P. tuberaster. Full article

The ability of Rhodotorula toruloides DSM 4444 to metabolize low-cost carbon sources such as fatty acids was comprehensively studied. This organism is shown, for the first time, to simultaneously accumulate microbial oils (biofuel precursors) and carotenoids from acetic acid obtained from CO₂ fermentation. This fatty acid is typically the single end product of acetogenic bioconversion of one-carbon gas pollutants (e.g., CO₂ and CO). In the first set of experiments, different aerobic fermentations were carried out in automated bioreactors, with acetic acid in one case and with glucose, a more conventional carbon source, as a control, in another bioreactor. R. toruloides consumed around 80 g/L substrate under both conditions. Maximum lipid content (27.2% g/g dry weight) was reached from 38 g/L glucose, while carotenoid content was higher with acetic acid (1.4 mg/g cell after 54.1 g/L acetic acid consumed), representing a 40% increase compared to glucose (1.0 mg/g cell after 64.2 g/L glucose consumed). Additionally, in the second set of assays, a fermented broth produced by Acetobacterium woodii from CO₂ fermentation, containing residual nutrients and metabolites, was tested. Despite its complex composition, R. toruloides grew and produced carotenoids (up to 0.141 mg/g), showing potential adaptability. To the best of our knowledge, this is the first report on a greenhouse gas-based biotechnological process as a promising sustainable alternative for the valorization of pollutants, e.g., gas emissions, their bioconversion to VFAs, such as acetic acid, and subsequent fermentation of the carboxylic acid into microbial oils, as a source of renewable energy, as well as carotenoids as a high-value nutraceutical product. Full article

In biotechnological processes, value-added products such as 1,3-propanediol (1,3-PD) are obtained in multi-component mixtures consisting of by-products, nutrient medium, bacterial cells and residual substrate. For this reason, separation to obtain the main product with the use of various techniques is economically unprofitable. Contrary, membrane bioreactors (MBRs) ensure several benefits and may play a crucial role in reducing the operating costs. The main objective of this work was to evaluate the feasibility of producing 1,3-PD in an MBR equipped with capillary polypropylene (PP) membranes for the MF (microfiltration) process. This article provides an in-depth examination of: (i) the yield of batch, fed-batch and fermentation in an MBR, (ii) the fouling mechanism during MF of fermentation broths, and (iii) PP membrane stability. It was found that performing the fermentation in an MBR allowed for production of 1,3-PD with the highest maximum yield, in the range of 0.48 g/g (0.58 mol/mol) to 0.59 g/g (0.72 mol/mol). Moreover, it was demonstrated that the significant decline of the MF process was mainly caused by the formation of a cake layer on the membrane surface. Nevertheless, the efficiency of the process was stable and ensured the high quality of the permeate. In addition, membrane cleaning with the use of 1% NaOH solution allowed to remove most of the foulants from the membrane surface. Despite repeated cleaning procedures, the membranes used in this work maintained their performance and efficiency. Hence, it can be concluded that the capillary polypropylene membranes for the MF process can be successfully used in MBR technology intended for the production of 1,3-PD by glycerol fermentation. Full article

Human breast milk harbors commensal lactic acid bacteria with probiotic potential, and microbial fermentation may enhance the bioactivity of plant-derived exosome-like nanovesicles (EVs); this study evaluated whether L. plantarum BMSE-HMP251 isolated from breast milk could safely ferment Hordeum vulgare L. and improve the anti-inflammatory activity of derived EVs. BMSE-HMP251 was identified by 16S rRNA sequencing and characterized by biochemical, safety, and genomic analyses. EVs derived from Hordeum vulgare L. extract and BMSE-HMP251-fermented broth were evaluated for physicochemical properties, antioxidant activity, cytotoxicity, and anti-inflammatory activity in LPS-stimulated HT-29 and RAW 264.7 cells. EVs derived from Hordeum vulgare L. fermentation exhibited a distinct size distribution and significantly enhanced bioactivity, including higher DPPH radical scavenging activity and greater suppression of nitric oxide production and proinflammatory cytokine (TNF-α and IL-1β) mRNA expression, compared with EVs from unfermented extracts. These effects were observed following fermentation with the human breast milk-derived strain L. plantarum BMSE-HMP251, which showed species-consistent phenotypic and genomic characteristics and no safety concerns. Overall, fermentation markedly enhances the anti-inflammatory potential of plant-derived EVs, supporting fermentation as a safe and effective strategy to improve their functional value. Full article

The microbiological safety of whole wheat flour remains a critical issue due to its susceptibility to contamination by spore-forming thermophilic bacteria. In this study, two thermophilic species, Bacillus subtilis and Bacillus mesentericus, were isolated from locally produced wheat grains and used as target microorganisms to evaluate the antibacterial potential of freshly pressed cabbage juices. Juices obtained from five cabbage varieties—red cabbage, white cabbage, napa (Chinese) cabbage, broccoli, and cauliflower—were comparatively assessed using the broth dilution method to determine their minimum inhibitory and bactericidal effects (n = 3). The results revealed pronounced differences in antibacterial efficacy among the tested samples. White cabbage juice exhibited selective inhibitory activity against B. subtilis at a dilution of 1:4, whereas napa cabbage and broccoli juices demonstrated the highest antibacterial activity against both Bacillus species at a dilution of 1:3. Importantly, napa cabbage juice showed no inhibitory effect on Saccharomyces cerevisiae, indicating its compatibility with dough fermentation processes. Spectroscopic analysis of the bioactive fraction obtained from napa cabbage juice revealed characteristic absorption bands at 3422 cm⁻¹ (O–H stretching), 2907–2840 cm⁻¹ (aliphatic C–H stretching), 1740 cm⁻¹ (ester carbonyl group), and 1641 cm⁻¹ (C=C stretching). The predominance of lipophilic compounds, including fatty acid esters, terpenes, and sulfur-containing compounds (734 cm⁻¹), suggests a molecular basis for the observed antibacterial activity against Bacillus spp. Overall, these findings identify napa cabbage as a promising source of selective natural antimicrobial agents capable of enhancing the microbiological safety of whole wheat flour-based bakery products without compromising yeast activity. Full article

Esterases catalyze the hydrolysis and transesterification of short-chain fatty acid esters, and microbial esterases are used in the production of biofuels, cosmetics, food, and pharmaceuticals. The soil strain Bacillus paralicheniformis T7 secretes enzymes with esterase activity; however, many bacterial enzymes remain insufficiently studied. Therefore, this study aimed to identify and characterize novel GDSL esterases produced by B. paralicheniformis. Protein mass spectrometry, combined with proteomics and genomics, identified genes encoding two GDSL esterases, which were cloned into the pET-28c(+) vector. The resulting proteins were obtained in Escherichia coli BL21(DE3) as the recombinant esterases rEST-24 and rEST-28. These recombinant GDSL esterases showed maximum activity at 40 °C and pH 7.0. Moreover, Ca²⁺, Zn²⁺, Cu²⁺, and Fe²⁺ ions inhibited their activity, and rEST-28 was resistant to the detergents Tween-20, Tween-80, and Triton X-100. High-yield esterase activity was detected in bacteria cultured on feather medium and nutrient broth, and submerged fermentation of the B. paralicheniformis T7 strain on feather medium enabled the production of an esterase extract exhibiting activity of 17,618 ± 610 U/g. These results suggest that the B. paralicheniformis T7 strain can produce esterases and shows promising potential for application in technologies that degrade fatty acid esters using hydrolytic enzymes. Full article

Calcareous soils are typically deficient in essential nutrients such as iron, phosphorus, and potassium, which frequently results in nutrient deficiency in fruit trees. Bacillus licheniformis LCDD6 markedly enhanced Malus hupehensis seedling growth and plant iron nutrition in calcareous soil. This study aimed to elucidate the mechanism underlying these beneficial effects of strain LCDD6 under iron deficiency. Transcriptomic analysis revealed that iron deficiency induced metabolic reprogramming in strain LCDD6, characterized by a significant upregulation of genes involved in the biosynthesis of the siderophore bacillibactin and plant growth hormone indoleacetic acid (IAA). Consistently, metabolomic profiling identified bacillibactin and IAA as the dominant metabolites produced under iron-deficient conditions. A 60-day pot experiment further demonstrated that the cell-free fermentation broth of strain LCDD6 significantly enhanced plant growth and rhizosphere soil enzyme activities. The crude bacillibactin extract derived from the fermentation exerted the strongest effects on plant growth and iron accumulation, whereas IAA preferentially stimulated root development and promoted plant phosphorus accumulation. Additionally, different metabolites exerted distinct and selective effects on the rhizosphere microbial community, with fungi showing stronger and more metabolite-specific responses than bacteria. The crude bacillibactin extract enriched fungal taxa, particularly Coprinellus, which showed strong positive correlations with plant growth traits and iron accumulation, while Stachybotrys, enriched under IAA treatment, was positively correlated with plant phosphorus content. Overall, strain LCDD6 promotes plant growth under iron-deficient conditions through the coordinated action of multiple metabolites, with bacillibactin as the primary contributor and IAA providing complementary effects. These findings offer mechanistic insight and a scientific basis for developing Bacillus-based biofertilizers to improve nutrient acquisition in calcareous soils. Full article

To investigate the dynamic changes during millet bran fermentation by Bacillus natto, we systematically monitored microbial growth, key enzyme activities, and the contents of major bioactive components over time. The changes in viable bacterial count, spore count, and the activities of protease, amylase, cellulase, and nattokinase (NK) fibrinolytic activity were measured throughout the 0–84 h fermentation process. Concurrently, variations in the contents of total sugars, reducing sugars, soluble dietary fiber (SDF), β-glucan, arabinoxylan, peptides, and polyphenols were analyzed. The results indicated that the viable bacterial count in the fermentation broth peaked at 48 h (9.3 log CFU/mL) and subsequently declined, while the spore count significantly increased to 7.6 log CFU/mL by 84 h. The activities of protease, amylase, cellulase, and NK fibrinolytic activity all exhibited a trend of initial increase followed by a decrease, reaching their respective maximum levels at 48 h. The contents of SDF, peptides, and polyphenols attained their highest values at 60 h, corresponding to 2.4 times, 2.17 times, and 1.5 times those of the unfermented control, respectively. The β-glucan content peaked at 24 h (31.31 mg/g millet bran), whereas the arabinoxylan content reached its maximum at 60 h, which was 19.4 times higher than that of the unfermented sample. Based on a comprehensive evaluation of all indicators, 48–60 h was determined to be the optimal fermentation duration for millet bran using B. natto. This research elucidates the relationship between enzyme activities and the accumulation of active components during fermentation, providing a theoretical foundation for the high-value utilization of millet bran and the development of functional products. Full article

Microbial proteases are fundamental towards the eco-sustainability of proteolysis at the industrial scale. A proteolytic broth was obtained from a bioreactor fermentation of a proteolytic Bacillus strain isolated from an industrial alkaline bath. Broth proteolytic activity was applied to leather tanning and to the removal of protein stains. The hide tanned with the microbial proteolytic fermentation broth showed better physical properties than the one tanned with commercial pancreatic proteases of the same activity (780 LVU). Proteinaceous stains on cotton fabric were removed more efficiently using the Bacillus proteolytic broth than water or a commercial detergent. Blood and egg yolk disappeared in less than 30 min. The removal of soya and English sauce stains was even faster. Broth proteolytic activity was characterised by caseinolytic (5200 LVU), collagenolytic (10.0 U mg⁻¹), elastolytic (3.7 U mg⁻¹), and keratinolytic (0.7 U mg⁻¹) activities, which were compared with those of a commonly used commercial protease. Alkaline protease activity in the broth was demonstrated by a 20% increase in caseinolytic activity from pH 5 to 8. Besides the demonstrated applications in the leather and detergent industries, the produced alkaline microbial proteases can also be used in the treatment of proteinaceous wastes and effluents, offering potential environmental benefits reinforcing and impacting the bioeconomy. Full article

Species of Sanghuangporus produce abundant bioactive compounds, including flavonoids, polysaccharides, and triterpenoids, among which flavonoids exhibit prominent antioxidant activity and great development potential. Taking the peak extracellular flavonoid (EF) concentration in fermentation broth as the index, we optimized the liquid fermentation media and conditions for three Sanghuangporus strains (wild S. vaninii Z-0090, cultivar S. vaninii Z-0119, and cultivar S. baumii Z-0118) via single-factor experiments and the Box–Behnken response surface methodology. We further evaluated the antioxidant activity of the fermentation broth and analyzed its correlation with EF concentration using Pearson correlation analysis. After optimization, the EF concentrations of strains Z-0090, Z-0119 and Z-0118 were increased by 22.82%, 13.47% and 16.66%, respectively, compared with the control group. Antioxidant assays showed that strain Z-0090 had the highest hydroxyl radical scavenging rate (88.63%), strain Z-0119 presented balanced performance across all antioxidant indicators, and strain Z-0118 exhibited the strongest ABTS radical scavenging capacity (184.96 μg Trolox equivalents/mL), which was highly correlated with its EF concentration. This study provides a theoretical basis for the application of Sanghuangporus EFs in food, medicine, and industrial flavonoid production. Full article

Endophytic FoRo54 was isolated from the roots of Oryza rufipogon (Dongxiang wild rice) collected in China. Based on morphological characteristics and phylogenetic analysis of the 16S rRNA gene sequence, strain FoRo54 was identified as closely related to Micromonospora rosaria. The complete genome of FoRo54 consists of a linear chromosome of 7,057,852 bp with a GC content of 73.8 mol%. Genome mining using antiSMASH revealed 27 biosynthetic gene clusters (BGCs) potentially involved in secondary metabolite biosynthesis, including those associated with kanamycin, rosamicin, and asukamycin, consistent with the antibacterial activities of the strain. Application of a combined genome mining strategy enabled further exploration of the strain’s metabolic potential. One new rosamicin derivative, N-demethyl rosamicin (1), together with three known compounds, rosamicin (2), SCH 23831 (3), and tylactone (4), were isolated from fermentation broth. Antibacterial evaluation revealed that compounds 1-4 exhibited potent inhibitory activity against Staphylococcus aureus. Furthermore, based on genomic analysis, the biosynthetic pathway and putative gene functions responsible for these metabolites were proposed. Collectively, these findings highlight the metabolic versatility of the endophytic Micromonospora rosaria FoRo54, underscoring its potential as a valuable source of novel bioactive metabolites and providing a genomic framework for future heterologous expression and functional genetic characterization. Full article

Microbial lipid production from renewable carbon sources, particularly lignocellulosic hydrolysates, is a promising alternative to plant-derived oils and fats for food applications, as it can minimize the land use by utilizing agricultural wastes and byproducts from food production. In this context, a standard approach to prevent oxygen limitation at reduced air gassing rates during long-term aerobic microbial processes is to operate bioreactors at increased pressure for elevating the gas solubility in the fermentation broth. This study investigates the effect of absolute pressures of up to 2.5 bar on the conversion of the carbon sources (glucose, xylose, and acetate), growth, and lipid biosynthesis by Cutaneotrichosporon oleaginosus converting a synthetic nutrient-rich lignocellulosic hydrolysate at low air gassing rates of 0.1 vessel volume per minute (vvm). Increasing pressure delayed xylose uptake, reduced acetic acid consumption, and reduced biomass formation. Lipid accumulation decreased with increasing pressure, except for fermentations at 1.5 bar, which achieved a maximum lipid content of 83.6% (±1.6, w/w) (weight per weight in %). At an absolute pressure of 1.5 bar, a lipid yield from glucose, xylose, and acetic acid of 38% (w/w) was reached after 6 days of fermentation. The pressure sensitivity of C. oleaginosus may pose challenges on an industrial scale due to the dynamic changes in pressure when the yeast cells pass through the bioreactor. Increasing liquid heights in full-scale bioreactors will result in increased hydrostatic pressures at the bottom, substantially reducing lipid yields, e.g., to only 23% (w/w) at 2.0–2.5 bar, as shown in this study. However, further scale-up studies with dynamic pressure regimes (1–2.5 bar) may help to evaluate scale-up feasibility. Full article

Anthracnose caused by Colletotrichum graminicola (Ces.) G.W.Wils is a significant disease of maize (Zea mays) worldwide. To obtain an efficient biocontrol strain and elucidate its mechanisms, 103 bacterial isolates were obtained from soil samples collected in the Tianshan Mountains, Xinjiang, China. Among these, Bacillus atrophaeus F4’s fermentation broth had the highest efficacy in controlling maize anthracnose, reaching 79.78%. To further investigate biocontrol mechanisms of F4 strain, its complete genome was sequenced, assembled, and annotated. Lipopeptides extracted from the fermentation broth of F4 were found to strongly inhibit the growth of hyphae and the germination of conidia in the pathogen. Microscopic and biochemical analyses indicated that the lipopeptide extract inhibited chitin synthesis and disrupted the integrity of the cell wall and membrane, thereby exerting antifungal effects. Further MALDI-TOF MS analysis identified antimicrobial compounds, including surfactin, iturin, and fengycin B, in the lipopeptide extract. Furthermore, plate antagonistic test showed that F4 strain exhibited broad-spectrum antagonistic activity against multiple plant pathogenic fungi. F4 strain also displayed motility, biofilm-forming capacity, and the ability to produce extracellular enzymes such as proteases and amylases, which are associated with biocontrol activity. These findings suggest the significant potential of B. atrophaeus F4 as a biocontrol agent against maize anthracnose. Full article

Companilactobacillus farciminis KUJ 25-S was isolated from fermented fish and identified using 16S rRNA gene sequencing with 30.0 g/L of L-LA (L-lactic acid), with 97% LA per sum of DL-LA. The characteristics of LA and its stereoisomers were confirmed using TLC, chiral-HPLC, and enzymatic techniques. Based on various conditions using liquid MRS broth (static condition, glucose 10%, NaCl 5%, 37 °C for 48 h), the highest growth and LA formation of the culture were at a low temperature (25 °C) and decreased at 37, 45, and 55 °C, respectively. The broth could grow and produce acid at an initial pH in the range 4–11, with a low initial pH of 4 promoting the highest LA formation. LA formation and growth were inversely proportional to the NaCl concentration in the 0.5–30% range. High glucose concentrations suppressed LA formation. The growth-promotion effect varied with glucose concentration (5–40%), with the optimum concentration for LA production being 20% glucose. On the other hand, if used in microoxic conditions, the absence of NaCl was more favorable to acidification than the addition of NaCl (5% NaCl). C. farciminis KUJ 25-S was proposed as a suitable method to produce L-LA based on using the appropriate line for further industrial use. Full article