Fermentation Broth Research Articles

Energy-efficient optimization design of bio-butanol fermentation broth purification process

To address the downstream processing challenges of the IBE (isopropanol-butanol-ethanol) system and obtain biobutanol products with a mass fraction of 0.9999, as well as obtain a mass fraction of 0.99975 for the IE (isopropanol-Ethanol) mixture product as a gasoline additive, this study proposes a four-column distillation process termed "Dehydration-Butanol-Extractive Four Column Distillation" (DBE-4CD). With the heat load as the optimization target, the DBE-4CD process was optimized to determine the optimal operating parameters. Based on the optimized process and considering the energy-saving potential of the dividing wall column, an “Azeotropic Dividing Wall-Extractive Three Column Distillation” (ADE-3CD) process was subsequently proposed to further enhance energy efficiency and reduce consumption. Compared to both conventional literature process and the DBE-4CD process, the total load of the ADE-3CD process decreased to 7433.5 kW, representing reductions of 20.35% and 10.11%, respectively. Additionally, the mass recovery rates of butanol and the IE mixture reached 99.90% and 99.64%, respectively, exceeding those of the conventional literature process, which were 99.11% and 99.18%.

Isolation and identification of endophytic fungi from Alhagi sparsifolia Shap. and their antibacterial activity

In order to explore the endophytic resources of Alhagi sparsifolia Shap. and identified novel antibacterial substances. Thirty endophytic fungal strains were isolated from the stems and roots of A. sparsifolia Shap. Morphological and molecular biology methods were used to identify ten strains of fungi, including four strains of Aspergillus niger, three strains of Alternaria alternata, two strains of Aspergillus flavus, and one strain of Fusarium incarnatum. All these strains were isolated from A. sparsifolia Shap. for the first time, and of these Aspergillus was the dominant genus. Antibacterial activity of the ten strains against Escherichia coli, Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa were evaluated using the disc diffusion method. The results demonstrated that the metabolites from all the strains had inhibitory effects on at least one indicator bacterium. Notably, the endophytic fungi AFJ3 and AFG6 demonstrated strong broad-spectrum antibacterial activity, particularly against E. coli, with inhibition zones measuring 32.0 ± 0.3 and 31.3 ± 0.3 mm, respectively. The three endophytic fungi (AFG1, AFG2, and AFG3) isolated from the roots demonstrated significant antibacterial activity against P. aeruginosa forming an inhibition zone of diameter 31.3 ± 0.1, 25.6 ± 0.2, and 25.6 ± 0.2 mm, respectively. However, the strains of endophytic fungi demonstrated no significant inhibitory effects on C. albicans. Ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry/mass spectrometry (UPLC-QTOF-MS/MS) analysis depicted that the ethyl acetate phase of AFJ3 and AFG6 fermentation broth predominantly contained organic acids, phenolic acids, flavonoids, and fatty acids. These secondary metabolites often exhibited good antibacterial activity. This study broadens our understanding of endophytic fungi in A. sparsifolia Shap. The antibacterial activity of some strains of endophytic fungi was significant, making it worthy of further research on their active material.

Scalable membrane-assisted ion exchange (MEM-IE) strategy for organic acid purification in biorefinery process

The transition towards a carbon-neutral society necessitates radical approaches in the bio-refinery pipeline, particularly in the production of organic acids. The current downstream process from a dilute fermentation broth is limited by the extensive use of acids and bases, along with heavy reliance on energy-intensive distillation. In this work, we propose an entirely membrane-based process to purify organic acids (e.g., gluconic acid) from a crude solution of catalytic dehydrogenation of glucose. To facilitate downstream purification, we introduce an innovative membrane-assisted ion exchange (MEM-IE) strategy, which is a scalable process that can protonate ionic compounds entirely in the solution phase. Instead of a solid ion exchange resin, a bulky yet soluble acidification agent is used to protonate the target compound, which can be easily separated via a size exclusion membrane. We selected non-toxic poly (4-styrene sulfonic acid) (H-PSS, 75 kDa) as the acidification agent to selectively protonate gluconate ions and to enable facile fractionation. The proposed MEM-IE strategy can overcome the scale-up limitation of traditional solid ion exchange resins and can be applied to many types of ionic compounds. The versatility of the proposed process was also demonstrated on formate and lactate compounds. A techno-economic evaluation using the Verberne cost model showed that the proposed process achieves an 80 % reduction in energy consumption compared to the fermentation-based process, and the return on investment (ROI) of a 330 ton-per-day plant was less than a year. The proposed membrane-based process for the purification of organic acids, particularly the MEM-IE strategy, offers a sustainable and energy-efficient downstream separation platform.

Evaluation of Functional Components of Lactobacillus plantarum AR495 on Ovariectomy-Induced Osteoporosis in Mice And RAW264.7 Cells

Osteoporosis is a disease characterized by abnormal bone metabolism, where bone resorption outpaces bone formation. In this study, we investigated the key functional components of Lactobacillus plantarum AR495 in mitigating ovariectomy (OVX)-induced osteoporosis in mice. The results indicated that both Lactobacillus plantarum AR495 and its fermentation broth significantly reduced urinary calcium and deoxypyridinoline (DPD) levels in the mice. These interventions inhibited bone resorption and improved trabecular bone architecture by modulating the nuclear factor κB (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) signaling pathway. Additionally, the L. plantarum AR495 and fermentation broth groups inhibited the RANKL/TRAF-6 and TLR4/MYD88 pathways, leading to enhanced bone metabolism, improved intestinal barrier function, and reduced intestinal inflammation. In vitro experiments revealed that AR495 fermentation supernatant fractions larger than 100 kDa and those between 50–100 kDa significantly decreased the activity of the osteoclast marker TRAP, regulated the expression of the TLR4/MYD88 pathway, and inhibited osteoclast formation, thereby alleviating the OVX-induced osteoporosis phenotype. These findings suggest that these components may be primary functional elements of L. plantarum AR495 in the treatment of osteoporosis.

1-Acetyl-β-Carboline from a Jeju Gotjawal Strain Lentzea sp. JNUCC 0626 and Its Melanogenic Stimulating Activity in B16F10 Melanoma Cells.

The genus Lentzea is a prolific source of bioactive and structurally diverse secondary metabolites. We isolated a novel strain, Lentzea sp. JNUCC 0626, from Hwasun Gotjawal on Jeju Island, Korea. Based on 16S rRNA partial gene sequence analysis, strain JNUCC 0626 is closely related to Lentzea isolaginshaensis NX62 (99.41% similarity), Lentzea pudingi DHS C021 (99.31%), and Lentzea cavernae SYSU K10001 (99.26%). From the fermentation broth of JNUCC 0626, we isolated 1-acetyl-β-carboline, whose structure was established using IR, HR-ESI-MS, and 1D- and 2D-NMR techniques. 1-acetyl-β-carboline was found to activate melanogenesis in mouse B16F10 cells without cytotoxicity at concentrations up to 50 μM. At this concentration, the compound increased melanin content by 27.44% and tyrosinase activity by 240.64% compared to the control, by upregulating key melanogenic enzymes, including tyrosinase, TRP-1, TRP-2, and microphthalmia-associated transcription factor (MITF), a central regulator of melanogenesis. In addition, 1-acetyl-β-carboline significantly inhibited ERK phosphorylation, reducing it by 20.79% at a concentration of 12.5 μM and by 25.63% at 25 μM. This inhibition supports the hypothesis that 1-acetyl-β-carboline enhances melanin synthesis by upregulating MITF and melanogenic enzymes via the ERK signaling pathway. This study aimed to isolate and identify 1-acetyl-β-carboline from a novel strain of Lentzea sp. JNUCC 0626, discovered in Gotjawal, Jeju Island, and to evaluate its effect on melanin production in B16F10 melanoma cells. Skin irritation tests on 32 subjects confirmed its safety for topical use, and the findings suggest that 1-acetyl-β-carboline, which enhances melanogenesis without cytotoxicity, holds promise as a therapeutic agent for hypopigmentation-related conditions or as a cosmetic ingredient.

Structural characterization, antioxidant activity, and fermentation characteristics of Flammulina velutipes residue polysaccharide degraded by ultrasonic assisted H2O2-Vc technique

Adhere to the concept of low-carbon environmental protection and turning waste into treasure, polysaccharides from Flammulina velutipes residue polysaccharide (FVRP) has been developed and possesses diverse bioactivities, comprising antioxidant, hypoglycemic, and relieving heavy metal damage, which still has the disadvantages of high molecular weight and low bioavailability. The current work is the first to prepare a degraded polysaccharide (FVRPV) from FVRP by ultrasonic assisted H2O2-Vc technique in order to reduce its molecular weight, thereby improving its activity and bioavailability. Our results found that the molecular weight and average particle size were declined, but the monosaccharide composition and characteristic functional group types of FVRPV had no impact. The structural changes of polysaccharides analyzed by XRD, Congo Red test, I2-KI, SEM, and methylation analysis indicated that the surface morphology and glycosidic bond composition of FVRPV possessed longer side chains and a greater number of branches with an amorphous crystal structure devoid of a triple helix configuration, and had experienced notable alterations after ultrasonic assisted H2O2-Vc treatment. Meanwhile, the in vitro antioxidant capacity of FVRPV had significantly increased compared to FVRP, implying ultrasonic assisted H2O2-Vc technique maybe a effective method to enhance the bioactivity of polysaccharides. In addition, the content of polysaccharide, reducing sugar, and uronic acid in FVRPV was significantly decreased, but antioxidant capacity of fermentation broth was stronger by in vitro human fecal fermentation. The 16S rDNA sequencing data displayed that FVRPV can enrich probiotics and reduce the abundance of pathogenic bacteria through different metabolic pathways mediated by gut microbiota, thereby exerting its potential probiotic effects. The interesting work provides a novel degraded polysaccharide by ultrasonic assisted H2O2-Vc technique, laying a foundation for developing FVRPV as a new antioxidant and prebiotic.

Screening and engineering of a protocatechuic acid decarboxylase for efficient biosynthesis of catechol

Catechol (CA) is an important chemical and pharmaceutical intermediate with wide applications. At present, CA is produced by phenol hydroxylation with non-renewable petrochemical resources, which causes serious environmental pollution. Hence, the biosynthesis of CA attracts much attention recently. However, due to the low activities of protocatechuic acid (PCA) decarboxylases, the production efficiency of biosynthetic catechol is too low to meet the requirements of large-scale industrial production. To improve the yield of CA, we screened 21 PCA decarboxylases from different species. RbAroY originated from Rikenellaceae had the best catalytic performance. The whole-cell biocatalyst ER11 with RbAroY was able to produce CA at a titer of 13.54 g/L. Then, the online tool HotSpot Wizard was employed to measure the enzyme stability, which revealed 10 potential mutation sites causing significant decreases in Gibbs free energy. The whole-cell biocatalyst ERT01 with the mutated RbAroYG99A could produce CA at a titer of 15.16 g/L, which increased by 12% compared with that of the wild-type whole-cell biocatalyst. After optimization of the biocatalytic conditions, the whole-cell biocatalyst ERT01 was able to produce CA at a titer of 25.70 g/L with PCA as the substrate. Finally, with the fermentation broth of 3-dehydroshikimate as the substrate, the whole-cell biocatalyst DER03 expressing both 3-dehydroshikimate dehydratase and PCA decarboxylase realized the production CA at a titer of 29.55 g/L, which is currently the highest biosynthetic titer reported. This study provides a reference for the industrial production of CA by biosynthesis.

Concentration and crystallization of Microbial Xylitol from oil palm empty fruit bunch (OPEFB) using submerged direct contact membrane distillation (DCMD)

Xylitol possess high solubility in water and increase viscosity at high temperature, making the concentration process become challenging. This study demonstrated the applicability of Membrane Distillation (MD) in concentrating xylitol solutions and evaluates its performance at different conditions and feed compositions. MD was capable of concentrating pure xylitol solution to reach the supersaturated condition. However, when Oil Palm Empty Fruit Bunch (OPEFB) hydrolysate fermentation broth was used, fouling was observed due to the presence of impurities, despite the application of feed agitation. The batch crystallization of xylitol were conducted at 5 °C with a seed addition of 0.5–0.8%-wt. Higher seed concentrations were required to induce crystallization in OPEFB hydrolysate due to lower xylitol concentrations and impurity presence. Furthermore, impurities influenced the quality of the crystals, resulting in crystal purities of 98.98% and 94.56% in the synthetic solution and OPEFB hydrolysate, respectively. These findings indicated notable impact of crystallization temperature, seed addition, and impurity on xylitol crystallization.

Separation of 2,3-Butanediol from Fermentation Broth via Cyclic and Simulated Moving Bed Adsorption Over Nano-MFI Zeolites.

The biomass-based platform molecule 2,3-butanediol (2,3-BDO) has a wide range of applications in production of sustainable fuels, chemicals, synthetic rubber, and others. However, the selective separation of 2,3-BDO from multicomponent fermentation broths presents challenges due to its low concentration, high solubility in water, high boiling point, and presence of many other species. Here, we demonstrate remarkably selective enrichment and recovery of 2,3-BDO from a corn stover hydrolysate fermentation broth by a pure-silica nano-MFI-type zeolite adsorbent. By means of cyclic and simulated moving bed adsorption processes, we obtained concentrated aqueous 2,3-BDO streams from the fermentation process stream with ∼93% purity and 3-fold enrichment, and >98% purity and 8-fold enrichment, respectively. These findings provide strong support for large-scale adsorptive separation for biobased 2,3-BDO production.

Dietary nucleotides drive changes in infant fecal microbiota in vitro and gut microbiota-gut-brain development in neonatal rats: A potential “nitrogen source” for early microbiota growth

Various dietary factors in human milk are important nutrients for the formation of the infant gut microbiota (GM). While promoting the growth of the GM, some human milk components that are difficult to absorb and utilize will be broken down by the GM, and converted into nutrients that the baby can use, such as breast milk oligosaccharides—the ‘carbon source’ for infant GM. This study reveals that nucleotides (NTs), significant non-protein nitrogen sources in human milk, can enhance the abundance of beneficial microbial genera such as g_Bifidobacterium, g_Bacteroides, and g_Blautia in in vitro fecal fermentation fluids of infants at low doses (2 mg/mL). Conversely, high doses of NTs (20 mg/mL) increased the abundance of g_Escherichia-Shigella. Furthermore, low-dose NTs fermentation broth significantly enhanced the expression of neurodevelopmental marker genes such as Tuj1, Sox2, Dcx, and NeuN in NE-4C neural stem cells, whereas a single NTs digestion broth did not exhibit significant activity. However, in vivo studies using neonatal rats as a model demonstrated that both low-dose NTs fermentation broth and NTs digestive juices promoted behavioral development in neonatal rats (PND 20) and neuron maturation in the prefrontal cortex and hippocampus. Non-targeted metabolomics results indicate that low-dose dietary NTs promote the production of certain neuroregulatory metabolites in infant fecal fermentation, such as uridine, L-tyrosine, L-glutamic acid, and succinic acid. These findings suggest that NTs may serve as an important “nitrogen source” during GM formation in early life and have a dose effect in driving the development of the microbiota-gut-brain axis in early life.

Multi-steps microfiltration of micelles from fermentation of Streptomyces tsukubaensis and its impact on proteins retention and tacrolimus yield

This study reports the application of microfiltration Streptomyces tsukubaensis micelles from fermentation broths, for tacrolimus recovery, investigating the use of a new multi-step microfiltration approach. Equal volumes of acetone were added to the fermented broth, and the resultant mixture was processed through multi-step microfiltration at 26 °C in a pressurized chamber, with operational pressures of 1 bar and 2 bar, using membranes with pore sizes of 0.22 μm and 3.0 μm. The permeate was recirculated, configuring ten steps of operation using the same membrane. The analysis of micelles microfiltration focused on the influence of multi-step processes on permeate flow and time steps, allowing exploration of pore blocking models. The cake filtration mechanism was identified as predominant for global filtration. The study achieved a 97 % micelles rejection rate in ten steps with a 3.0 μm pore membrane at 1 bar. Protein retention was also studied, showing a final retention rate of 60 %, with 40 % of proteins in the final permeate. This multi-step filtration process acts as microfiltration for micelles and ultrafiltration for proteins, improving tacrolimus purity. However, the tacrolimus yield was reduced by 9 %, attributed to increased tacrolimus adsorption on the gel/cake layer surface rather than steric factors.

Application of Biotechnology and Chiral Technology Methods in the Production of Ectoine Enantiomers

Natural ectoine, (+)-(4S)-2-methyl-1,4,5,6-tetrahydropyrimidine-4-carboxylic acid, is an extremely important small biomolecule belonging to the class of osmolytic/osmoprotective compounds. It stabilizes biomacromolecules such as DNA and proteins and protects them from denaturation by heat, dehydration, and UV radiation. The rapidly growing interest in this compound resulted in currently exclusive biotechnological production, while a chemical process along with enantioseparation as an alternative has not yet been established. An improved chemical synthesis of racemic ectoine starting from γ-butyrolactone in very good yield is described. Regioselective monoacetylation is achieved by the complexation of a copper(II)-ion with two molecules of 2,4-diamonobutyric acid in the key synthetic step. The racemic ectoine was synthesized with the aim of being successfully enantioseparated for the first time by high-performance liquid chromatography (HPLC) using a teicoplanin-based Chiral-T column in different solvent systems. The presence of (+)-ectoine was determined and quantified using an HPLC protocol on the Synergy Polar-RP column in fermentation broths inoculated with different strains of Streptomyces sp. bacteria isolated from the Adriatic Sea and grown on different NaCl concentrations.

The antagonistic activity of Streptomyces spiroverticillatus (No. HS1) against of poplar canker pathogen Botryosphaeria dothidea

BackgroundPoplar canker caused by Botryosphaeria dothidea is one of the most severe plant disease of poplars worldwide. In our study, we aimed to investigate the modes of antagonism by fermentation broth supernatant (FBS) of Streptomyces spiroverticillatus HS1 against B. dothidea.ResultsIn vitro, the strain and FBS of S. spiroverticillatus HS1 significantly inhibited mycelial growth and biomass accumulation, and also disrupted the mycelium morphology of B. dothidea. On the 3rd day after treatment, the inhibition rates of colony growth and dry weight were 80.72% and 52.53%, respectively. In addition, FBS treatment damaged the plasma membrane of B. dothidea based on increased electrical conductivity in the culture medium, and malondialdehyde content of B. dothidea mycelia. Notably, the analysis of key enzymes in glycolysis pathway showed that the activity of hexokinase (HK), phosphofructokinase (PFK), and pyruvate kinase (PK), Ca2+Mg2+-ATPase were significantly increased after FBS treatment. But the glucose contents were significantly reduced, and pyruvate contents were significantly increased in B. dothidea after treatment with FBS.ConclusionsThe inhibitory mechanism of S. spiroverticillatus HS1 against B. dothidea was a complex process, which was associated with multiple levels of mycelial growth, cell membrane structure, material and energy metabolism. The FBS of S. spiroverticillatus HS1 could provide an alternative approach to biological control strategies against B. dothidea.

Sulfonated polybenzimidazole membrane with graphene oxide additive for 2,3-butanediol/water separation: A molecular simulation

Membrane separation for 2,3-butanediol (2,3-BDO) recovery from fermentation broth is highly valued for sustainable and renewable processes, but it requires efficient membrane materials. This work evaluates the sulfonated polybenzimidazole (sPBI) and its graphene oxide (GO) doped composite membrane for separating 2,3-BDO and water via atomistic simulations. Density functional theory calculations are applied to identify various forms of sPBI structures and quantify their binding interactions with 2,3-BDO and water. Classical molecular dynamic simulations are used to evaluate the structural changes, diffusivity, and selectivity of 2,3-BDO and water in different sPBI models, GO surfaces, and GO-doped sPBI composite models. Our results suggest that sPBI slightly increases the crystallinity of the membrane structures, enhances the adsorption strength for both 2,3-BDO and water, and improves the water/2,3-BDO selectivity by 2–3 times. The GO surfaces display a maximum selectivity at a surface coverage of 0.1–0.15 for both hydroxyl and epoxy surface groups. The addition of GO flakes to sPBI creates new interaction sites for 2,3-BDO and water at the interface of sPBI and GO, and the water/2,3-BDO selectivity of GO-doped sPBI models is further increased up to 3 times. This work illustrates how the integrated addition of sPBI and GO flakes offers a promising approach to selective separation of 2,3-BDO and water, providing theoretical guidance for polybenzimidazole-based membranes in the potential application of 2,3-BDO recovery.

Isolation, structural elucidation and biosynthetic pathway of bioactive prenyl quinone compounds from Panus lecomtei based on untargeted metabolomics combined with molecular networking

Panus lecomtei is a relatively unfamiliar and undeveloped mushroom. This study generated ethyl acetate extracts of P. lecomtei intracellular (I), extracellular (E) and total fermentation broth (T). Both E and T extracts demonstrated antioxidant and antibacterial activities at 100 to 200 μg/mL. The composition differences of metabolites of these extracts were further studied based on comparative metabolomics by LS/MS and molecular network analysis. The results revealed that there were over 2000 significantly distinct metabolites among the three extracts, with abundant prenyl quinone compounds. Furthermore, the molecular network clarified the conversion relationship of P. lecomtei metabolites. Seven known prenyl quinone derivatives (1–7) were isolated from the E extract. Among them, compound 3 displayed excellent antioxidant activity and modest antibacterial activity. Compound 5 was discovered in fungi for the first time. Finally, a potential biosynthetic route for prenyl quinone in P. lecomtei was suggested.

Multi-omics study on the mixed culture of Trichoderma reesei and Aspergillus niger with improved lignocellulase production

The mixed culture of Trichoderma reesei and Aspergillus niger were found to improve lignocellulase production and ameliorate the composition (Fang et al., 2010; Fang et al., 2013; Zhao et al., 2018) [1-3]. However, the mechanism behind remained unclear. Here we conducted multi-omics study of the mixed culture to elucidate the mechanism comprehensively, including proteomics of the secretomes, metabolomics of the fermentation broths and transcriptomics. The mechanisms at transcriptional, proteomic and metabolomic levels were clarified. Proteomics show many proteins in the secretomes were up-regulated by the mix culture of T. reesei and A. niger, and lignocellulase production and the composition were improved, but the protein numbers and abundances of the lignocellulases were reduced. Transcriptomics demonstrate that lignocellulase gene expressions, stress responses and anti-stress were co-regulated in T. reesei, and that most lignocellulase genes in T. reesei were up-regulated and most A. niger lignocellulase genes were down-regulated. Metabolomics reveal the chemicals and the mechanism of the communication between T. reesei and A. niger in the mixed culture for improved lignocellulase production. The secondary metabolites such as p-cresol, nodularin and tolazoline could play important roles. Integrative analyses indicate that the secondary metabolites, stress-response, anti-stress, starch and sucrose metabolism and lignocellulase gene expressions were orchestrated. As a result, the roles of T. reesei and A. niger in the mixed culture were defined. The mechanism of the mixed culture for improved lignocellulase production was obtained, in short T. reesei was the major role and A. niger the minor. This work provides theory and targets as basis to obtain complete understanding of the mechanism and guide engineering of the microbial consortium of T. reesei and A. niger for further improvements.

Fermentation broth of a novel endophytic fungus enhanced maize salt tolerance by regulating sugar metabolism and phytohormone biosynthesis or signaling

Soil salinization is a major environmental factor that severely affects global agriculture. Root endophytes can enter root cells, and offer various ecological benefits, such as promoting plant growth, improving soil conditions, and enhancing plant resistance. Su100 is a novel strain of endophytic fungus that was characterized from blueberry roots. In this study, we focused on evaluating the effects of Su100 secretion on maize growth. The results demonstrated that maize treated with Su100 fermentation broth (SFB) exhibited significantly stronger salt tolerance than the control. It is worth mentioning that the treated root system not only had an advantage in terms of biomass but also a change in root structure with a significant increase in lateral roots (LRs) compared to the control. Transcriptome analysis combined with hormone content measurements indicated that SFB upregulated the auxin signaling pathway, and also caused alterations in brassinosteroids (BR) and jasmonic acid (JA) biosynthesis and signaling pathways. Transcriptome analyses also indicated that SFB caused significant changes in the sugar metabolism of maize roots. The major changes included: enhancing the conversion and utilization of sucrose in roots; increasing carbon flow to uridine diphosphate glucose (UDPG), which acted as a precursor for producing more cell wall polysaccharides, mainly pectin and lignin; accelerating the tricarboxylic acid cycle, which were further supported by sugar content determinations. Taken together, our results indicated that the enhanced salt tolerance of maize treated with SFB was due to the modulation of sugar metabolism and phytohormone biosynthesis or signaling pathways. This study provided new insights into the mechanisms of action of endophytic fungi and highlighted the potential application of fungal preparations in agriculture.

Genome Analysis of a Potential Novel Vibrio Species Secreting pH- and Thermo-Stable Alginate Lyase and Its Application in Producing Alginate Oligosaccharides.

Alginate lyase is an attractive biocatalyst that can specifically degrade alginate to produce oligosaccharides, showing great potential for industrial and medicinal applications. Herein, an alginate-degrading strain HB236076 was isolated from Sargassum sp. in Qionghai, Hainan, China. The low 16S rRNA gene sequence identity (<98.4%), ANI value (<71.9%), and dDDH value (<23.9%) clearly indicated that the isolate represented a potential novel species of the genus Vibrio. The genome contained two chromosomes with lengths of 3,007,948 bp and 874,895 bp, respectively, totaling 3,882,843 bp with a G+C content of 46.5%. Among 3482 genes, 3332 protein-coding genes, 116 tRNA, and 34 rRNA sequences were predicted. Analysis of the amino acid sequences showed that the strain encoded 73 carbohydrate-active enzymes (CAZymes), predicting seven PL7 (Alg1-7) and two PL17 family (Alg8, 9) alginate lyases. The extracellular alginate lyase from strain HB236076 showed the maximum activity at 50 °C and pH 7.0, with over 90% activity measured in the range of 30-60 °C and pH 6.0-10.0, exhibiting a wide range of temperature and pH activities. The enzyme also remained at more than 90% of the original activity at a wide pH range (3.0-9.0) and temperature below 50 °C for more than 2 h, demonstrating significant thermal and pH stabilities. Fe2+ had a good promoting effect on the alginate lyase activity at 10 mM, increasing by 3.5 times. Thin layer chromatography (TLC) and electrospray ionization mass spectrometry (ESI-MS) analyses suggested that alginate lyase in fermentation broth could catalyze sodium alginate to produce disaccharides and trisaccharides, which showed antimicrobial activity against Shigella dysenteriae, Aeromonas hydrophila, Staphylococcus aureus, Streptococcus agalactiae, and Escherichia coli. This research provided extended insights into the production mechanism of alginate lyase from Vibrio sp. HB236076, which was beneficial for further application in the preparation of pH-stable and thermo-stable alginate lyase and alginate oligosaccharides.

The potency of Monascus purpureus to achieve the transformation from inorganic selenium into organic selenium during the fermentation process

Selenium (Se), as an essential element for the human body, cannot be produced by itself, making Se-rich products research a current hotspot. Microorganisms are common Se-rich carriers and previous experiments mainly focused on yeast and lactic acid bacteria, lacking mold. In this study, the total Se and organic Se content in Monascus purpureus (M. purpureus) were determined by a liquid chromatography-atomic fluorescence spectrometry after fermentation, applying inorganic sodium selenite as exogenous Se. The research results indicated that M. purpureus successfully converted inorganic Se into organic Se, with an organic Se to total Se ratio of 30.50%, 36.14%, 39.94%, 46.18%, and 53.00% at 2, 4, 6, 8, and 10 mg/L sodium selenite, respectively. The proportion of Se-protein (28.04%–47.33%) was highest in organic Se, especially water-soluble Se-protein, followed by Se-polysaccharide (3.80%–5.07%) and Se-nucleic acid (1.84%–3.07%). Furthermore, Se-enriched treatment did not significantly alter the morphology or structure of M. purpureus, while enriching the types and content of volatile components in the fermentation broth. Thus, this study was expected to lay the foundation for the development and utilization of Se-rich M. purpureus products.

Highly efficient bio-production of putrescine from L-arginine with arginase and L-ornithine decarboxylase in engineered Escherichia coli

To achieve industrial-scale putrescine production, a high efficient bio-synthesis of putrescine involving arginase (ARG, EC 3.5.3.1) and L-ornithine decarboxylase was evaluated here. Among the four arginases tested, ARGBT from Bos Taurus showed the highest activity (1966 U/mg). Compared to the L-arginine decarboxylase (ADC) pathway, the strain expressing ARGBT and L-ornithine decarboxylase (SpeC) produced 28.7 g/L putrescine, a 38.6 % increase. Two pyridoxal phosphate (PLP) salvage pathways were evaluated, and the strain BL-PTac-PdxK co-expressed pyridoxal kinase (PdxK) performed better. D-Glucose was used as the co-substrate to improve the putrescine titer further. Under optimal conditions, 43.6 g/L putrescine was produced from 87.1 g/L L-arginine, and 76 g/L putrescine was synthesized on a 0.5 L scale. Using L-arginine fermentation broth (60 g/L) as the substrate, a titer of 30 g/L putrescine was achieved. This efficient biotransformation process presented here enables feasible industrial-scale putrescine production.