Optimization Of Fermentation Conditions Research Articles

Optimization of Fermentation Conditions and Metabolite Profiling of Grape Juice Fermented with Lactic Acid Bacteria for Improved Flavor and Bioactivity.

To enrich the flavor compounds and retain the content of polyphenolics in grape juice (GJ) under long-term storage, Lactiplantibacillus plantarum, Lactobacillus acidophilus, Lacticaseibacillus casei, and Lacticaseibacillus paracasei, were screened and the optimal fermentation conditions were determined as fermentation temperature of 41.2 °C for 24 h with an initial LAB density of 8.5 × 106 CFU/mL. Surprisingly, the retention rates of TPC still remained at 50% after storage for 45 days at 4 °C. Moreover, 251 different metabolites were identified, include 23 polyphenolics, 11 saccharides, and 9 organic acids. Most importantly, the total content of polyphenolics reserved was 92.65% at the end of fermentation. Among them, ephedrannin A content significantly decreased; however, 2',6'-Di-O-acetylononin gradually increased with the fermentation time, which resulted in FGJ maintaining excellent bioactivity. Meanwhile, organic acid content (palmitoylethanolamide, tetraacetylethylenediamine) increased with saccharides (linamarin) decreasing, which leads to FGJ having a unique taste. Furthermore, a total of 85 Volatile organic compounds (VOCs) were identified, mainly including esters, aldehydes, and alcohols. Interestingly, key VOCs could be formed by carboxylic acids and derivatives, and fatty acyls via complex metabolic pathways.

Optimized fermentation conditions for dragon fruit yogurt

Flavored yogurt which includes fruit yogurt is more popular with consumers, the addition of fruit to yogurt improves the flavor making the yogurt product more appealing to consumers. Dragon fruit has been used in yogurt production to enhance the nutritional and physiological characteristics of final product. However, limited information exists on optimizing the processing parameters of dragon fruit yogurt production. This study, therefore, adopted a central composite design to optimize the processing parameters of dragon fruit yogurt production and evaluated the statistical relation between the independent factors (dragon fruit puree, milk powder, corn starch, and fermentation time) and their responses (viscosity, syneresis, pH and titratable acidity). Results indicated that milk powder and fermentation time were the principal factors that affect the various responses. Based on the surface response models, the optimum formulation conditions for dragon fruit yogurt were dragon fruit puree (31.42 g), corn starch (7.0 g), milk powder (49.02 g), and fermentation time (6.0 hr). This produced a measured response of pH (4.77 ± 0.12), viscosity (30.33 ± 9.29 cP), syneresis (25.24 ± 5.36 %), and titratable acidity (1.05 ± 0.03 %). The optimum fermentation conditions had a favorable effect on the response values, suggesting that dragon fruit yogurt production could benefit from the optimized formula.

Effect of sourdough on the quality of whole wheat fresh noodles fermented with exopolysaccharide lactic acid bacteria

In this study, the impact of exopolysaccharides (EPS)-positive strain Weissella cibaria (W. cibaria) fermented sourdough on the quality of whole wheat fresh noodles (WWNs) and its improvement mechanisms were studied. The optimal fermentation conditions were found to be 30% sucrose content, fermented at 25 °C for 12 h, which yielded the highest EPS, 28.06 g/kg, in the W. cibaria fermented sourdough with sucrose (DW+). During storage, the sourdough reduced polyphenol oxidase activities and delayed the browning rate of noodles. The DW+ increased the hardness by 11.98% from 2184.99 to 2446.83 g, and the adhesiveness increased by 19.60%, i.e., from 72.01 to 86.13 g∙s of the noodles. The EPS mitigated acidification of sourdough, prevented the disaggregation of glutenin macropolymers (GMP), and increased sourdough elastic modulus. In addition, scanning electron microscope and confocal laser scanning microscopy of noodles containing EPS sourdough also demonstrated the uniform distribution of gluten proteins. The starch granules were also closely embedded in the gluten network. Thus, the present work indicated that the EPS produced sourdough delayed browning and improved the WWNs texture, indicating its potential to enhance the quality of whole grain noodles.

Exploring the Effects of Solid-State Fermentation on Polyphenols in Acanthopanax senticosus Based on Response Surface Methodology and Nontargeted Metabolomics Techniques

In order to optimize the process of solid-state fermentation and understand the changes of active ingredients during fermentation of A.senticosus, we used response surface methodology to optimize the solid-state fermentation process of A.senticosus and analyzed the effect of fermentation on the active components of A.senticosus by nontargeted metabolomics techniques. The effects of fermentation conditions on polyphenol content were studied in terms of fermentation time, fermentation temperature, water content, and the inoculum level through Plackett–Burman design and response surface experiments. The optimized fermentation conditions were a fermentation time of 60 h, a fermentation temperature of 37°C, a water content of 55%, and an inoculum level of 12.5%, and the polyphenol content reached 10.25 ± 0.05 mg·g−1, which was 40% higher than that before fermentation. Furthermore, the metabolites and metabolic pathways of A. senticosus were analyzed before and after fermentation using nontargeted metabolomics techniques, and differences in metabolites were investigated based on the analysis of the principal components. The results showed that A.senticosus contained 57 phenolics, and a total of 12 polyphenolic metabolites were significantly different before and after fermentation (including phenols and isoflavonoids), among which the content of caffeic acid and its derivatives with antioxidant capacity was significantly increased, which may improve the antioxidant capacity of fermented A.senticosus. Therefore, solid-state fermentation opens new avenues for the clinical development and application of A. senticosus.

Mitigation of N2O emissions via enhanced denitrification in a biological landfill leachate treatment using external carbon from fermented sludge

The effects of an external carbon source (C-source) on the mitigation of N2O gas (N2O(g)) emissions from landfill leachate were investigated via enhanced denitrification using anaerobically fermented sewage sludge. Anaerobic fermentation of sewage sludge was conducted under thermophilic conditions with progressively increasing organic loading rates (OLR). Optimal conditions for fermentation were determined based on the efficiency of hydrolysis and the concentrations of sCOD and volatile fatty acids (VFAs) as follows: at an OLR of 40.48 ± 0.77 g COD/L·d with 1.5 days of solid retention time (SRT), 14.68 ± 0.59% of efficiency of hydrolysis, 14.42 ± 0.30 g sCOD/L and 7.85 ± 0.18 g COD/L of VFAs. Analysis of the microbial community in the anaerobic fermentation reactor revealed that degradation of sewage sludge might be potentially affected by proteolytic microorganisms producing VFAs from proteinaceous materials. Sludge-fermentate (SF) retrieved from the anaerobic fermentation reactor was used as the external C-source for denitrification testing. The specific nitrate removal rate (KNR) of the SF-added condition was 7.54 mg NO3−N/g VSS·hr, which was 5.42 and 2.43 times higher than that of raw landfill leachate (LL) and a methanol-added condition, respectively. In the N2O(g) emission test, the liquid phase N2O (N2O–N(l)) of 20.15 mg N/L was emitted as N2O(g) of 19.64 ppmv under only LL-added condition. On the other hand, SF led to the specific N2O(l) reduction rate (KN2O) of 6.70 mg N/g VSS hr, resulting in mitigation of 1.72 times the N2O(g) emission compared to under the only-LL-added condition. The present study revealed that N2O(g) emissions from biological landfill leachate treatment plants can be attenuated by simultaneous reduction of NO3−N and N2O(l) during enhanced denitrification via a stable supply of an external C-source retrieved from anaerobically fermented organic waste.

Optimization of fermentation conditions as a metabolic strategy for the high-yield and high-selectivity bio-based 2,3-butanediol production

Optimization of culture conditions can be used as an alternative metabolic control strategy to genetic engineering to improve bio-based 2,3-butanediol (2,3-BDO) production, especially its yield and optical purity. In this study, a first-order model was determined to predict the 2,3-BDO yield, which reached about 90% in batch cultures at 32° C, pH = 5, and kLa ∼ 5.0 ± 2.7 h−1, using a new and safe Paenibacillus peoriae NRRL BD-62. No acetoin accumulation and an absolute levo-2,3-BDO optical purity were also verified. About 39.4 g/L of 2,3-BDO, with a yield of 0.43 g/g, and a levo-:meso-2,3-BDO ratio of 1.9:1, was obtained at the expense of acetoin, lactic acid, and ethanol in fed-batch fermentation at kLa adjusted within its optimized range (∼7.5 h−1) to overcome operational limitations using high initial glucose concentrations. The low pH contributed to the carbon flux shift toward the levo-isomer synthesis, possibly due to the preferential butanediol dehydrogenase activation, while the highly oxygen-limited environment favored the complete acetoin conversion, enhancing the 2,3-BDO yield. These results provide significant contributions to the high-yield, acetoin-free, and safe bio-based 2,3-BDO production of particular interest in large-scale fermentations.

Litopenaeus vannamei fermentation using selected Lactobacillus spp. to reduce its allergenicity

ABSTRACT Shrimp is a common cause of food allergies in allergic individuals. The management of patients suffering from shrimp allergy relies on avoidance of the specific food, which compromises nutritional requirements. In this study, fermentation was performed using Lactobacillus to reduce the allergenicity of Litopenaeus vannamei. The optimal fermentation conditions using Lactobacillus helveticus TS6024 were 1% glucose, 30% minced shrimp, 2.5% inoculum level, 3% NaCl, and 60 h of incubation at 37°C, whereas those using Lactobacillus acidophilus 6005 were 2% glucose, 20% minced shrimp, 15% inoculum level, 2% NaCl, and 48 h of incubation at 42°C. Under optimal conditions, Lactobacillus helveticus TS6024 and Lactobacillus acidophilus 6005 fermentation reduced the allergenicity of shrimp by 78.97% and 70.09%, respectively. SDS-PAGE analysis showed that the band intensity of tropomyosin (36KDa) reduced evidently after the selected Lactobacillus fermentation. The hypoallergenic shrimp/shrimp products will provide optimal nutrition with reduced risk of adverse reactions in hypersensitive individuals.

Sequentially Pitching Lactic Acid Bacteria and Active Dry Yeasts for Sour Beer Production

Lactic acid bacteria are key constituents in the souring process of traditional acidic beers, resulting from spontaneous or mixed fermentations. The development of such beer styles provides a balanced and complex-flavored beverage but is time-consuming and not easily repeatable. New time-efficient alternatives include successively pitching a souring bacteria and yeast, such that both have optimal fermentation conditions. In this study, each microorganism is assessed to comprehend its individual impact on the fermentation process (acidification and fermentation rates, attenuation, ethanol production) and its influence on physicochemical and organoleptic parameters. Lactic acid bacteria are responsible for the wort’s acidification, reaching a pH of 3.5 within 48 h, by converting up to 5 g/L of simple sugars into organic acids and other by-products. The two-step acidification and fermentation process alters the color and bitterness, the latter decreasing from an initial iso-α-acid concentration of 29 mg/L to an average of 13 mg/L. The sequential method shows that the decarboxylation and subsequent reduction of hydroxycinnamic acid precursors into their vinyl and ethyl derivatives is strain dependent. All tested lactic acid bacteria appear to possess the decarboxylation enzymes. However, only Lactiplantibacillus plantarum can reduce vinylphenols into ethylphenols.

Enhancing precursor supply and modulating metabolism to achieve high-level production of β-farnesene in Yarrowia lipolytica

β-Farnesene is a sesquiterpene commonly found in essential oils of plants, with applications spanning from agricultural pest control and biofuels to industrial chemicals. The use of renewable substrates in microbial cell factories offers a sustainable approach to β-farnesene biosynthesis. In this study, malic enzyme from Mucor circinelloides was examined for NADPH regeneration, concomitant with the augmentation of cytosolic acetyl-CoA supply by expressing ATP-citrate lyase from Mus musculus and manipulating the citrate pathway via AMP deaminase and isocitrate dehydrogenase. Carbon flux was modulated through the elimination of native 6-phosphofructokinase, while the incorporation of an exogenous non-oxidative glycolysis pathway served to bridge the pentose phosphate pathway with the mevalonate pathway. The resulting orthogonal precursor supply pathway facilitated β-farnesene production, reaching 810 mg/L in shake-flask fermentation. Employing optimal fermentation conditions and feeding strategy, a titer of 28.9 g/L of β-farnesene was attained in a 2 L bioreactor.

Production of Nattokinase from Hemp Seed Meal by Solid-State Fermentation and Improvement of Its Nutritional Quality

Fermented foods have gained immense popularity in recent years due to their distinct flavor profile. Given the increasing demand, there is a growing focus on optimizing their nutritional quality while also reducing their costs. In this study, using a novel approach, hemp seed meal was utilized as a solid fermentation substrate to produce nattokinase (NK). Using a combination of one-factor-at-a-time experiments, Plackett–Burman design, and Box–Behnken design, the optimal fermentation conditions of Bacillus subtilis 13932 (NK-producing strain) were determined. The initial ratio of HSM (hemp seed meal) to water was 1:2.0 (v:w), the thickness of the substrate was 2.9 cm, the bacterial inoculum volume was 10% (v:w), the relative humidity was 75.2%, the temperature was set at 35 °C, and the fermentation time was 20 h. The NK activity under these conditions was measured to be 7067.12 IU/g. During fermentation, 15.15% of soluble peptides were produced, which exhibited hydroxyl radical removal ability and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical removal ability of 14.85%, down from 32.96%. Furthermore, trypsin inhibitor and urease in HSM decreased by 42.6% and 73.6%, respectively, improving the nutritional quality of HSM. Sensory evaluations indicated that HSM is expected to be a popular food, highlighting the potential of using HSM as a solid fermentation substrate for NK production.

Antimicrobial activity and optimization of Aureobasidin A production by Aureobasidium pullulans PA-2 against Escherichia coli and Staphylococcus aureus

This work aims to separate antimicrobial lipopeptides from fermentation by Aureobasidium pullulans PA-2, and verify its antimicrobial activity and the optimum condition of lipopeptide production. Using high performance liquid chromatography (HPLC) analysis, the lipopeptides with antimicrobial activity was evaluated with the agar well diffusion test. Response surface methodology (RSM) was used to determine optimum conditions for lipopeptides from A. pullulans PA-2. The lipopeptides with antimicrobial activity in the fermentation supernatant of the PA-2 strain was found to be the Aureobasidin A (AbA). In vitro antagonistic tests showed that the minimal inhibitory concentration (MIC) of AbA against Staphylococcus aureus and Escherichia coli was 0.5 and 1.0 mg/mL, respectively. The optimal fermentation conditions were: inoculum size 6.8 % (v/v)(OD600=0.25), rotation speed 216 rpm, culture temperature 26 ℃, liquid volume 125 mL and initial pH7. Under this condition, predicting yield of the antimicrobial lipopeptides by the model was 940 mg/L, observed yield 920 mg/L, which was 51 % more than that of before optimization (610 mg/L).

Optimization of the medium and fermentation condition for the Penicillium aurantiocandidum Z12 strain with molluscicidal actions against Oncomelania hupensis

To optimize the culture and fermentation conditions of the Penicillium aurantiocandidum Z12 strain, a fungal strain with molluscicidal actions against Oncomelania hupensis, so as to provide the basis for the research and development of molluscicidal active substances from the P. aurantiocandidum Z12 strain and its fermentation broth and large-scale fermentation. The carbon source, nitrogen source and mineral salts were identified in the optimal culture medium for the P. aurantiocandidum Z12 strain with a single-factor experiment to determine the best fermentation condition for the P. aurantiocandidum Z12 strain. Factors that significantly affected the growth of the P. aurantiocandidum Z12 strain were identified using the Plackett-Burman design, and the best range of each factor was determined using the steepest climb test. Response surface analyses of temperature, pH value, seeding amount and liquid-filling quantity were performed using the Box-Behnken design to create a regression model for fermentation of the P. aurantiocandidum Z12 strain to identify the optimal culture medium. Single-factor experiment preliminarily identified the best culture medium and conditions for the P. aurantiocandidum Z12 strain as follows: sucrose as the carbon source at approximately 20 g/L, tryptone as the nitrogen source at approximately 5 g/L, K2HPO4 as the mineral salt at approximately 5 g/L, initial pH at approximately 8, temperature at approximately 28 °C, seeding amount at approximately 6%, and liquid-filling quantity at approximately 50 mL/100 mL. Plackett-Burman design showed that factors that significantly affected the growth of the P. aurantiocandidum Z12 strain included temperature (t = -5.28, P < 0.05), seeding amount (t = 5.22, P < 0.05), pH (t = -4.30, P < 0.05) and liquid-filling quantity (t = -4.39, P < 0.05). Steepest climb test showed the highest mycelial growth at pH of 7.5, seeding amount of 8%, and liquid-filling quantity of 40 mL/100 mL, and this condition was selected as the central point of response surface analysis for the subsequent optimization of fermentation conditions. Response surface analyses using the Box-Behnken design showed that the optimal conditions for fermentation of the P. aurantiocandidum Z12 strain included sucrose at 15 g/L, tryptone at 5 g/L, K2HPO4 at 5 g/L, temperature at 28.2 °C, pH at 7.5, seeding amount at 10%, and liquid-filling quantity at 35.8 mL/100.0 mL, resulting in 0.132 g yield of the P. aurantiocandidum Z12 strain. The optimal culture condition for the P. aurantiocandidum Z12 strain has been identified, and the optimized culture medium and fermentation condition may effectively improve the fermentation yield of the P. aurantiocandidum Z12 strain.

Optimal Fermentation of Artemisia annua Residues and Its Effects on Production Performance of Laying Hens

Artemisia annua residue (ARR) is a pharmaceutical by-product produced after the extraction of artemisinin; it is rich in protein, crude fat, vitamins, trace elements, and bioactive compounds and contains negligible anti-nutritional factors. The present study aimed to optimize the fermentation conditions of ARR, evaluate the compound and microbial compositions of fermented AAR, and explore its effects on the production performance of laying hens. A total of 288 Xinyang black-feather laying hens were randomly allocated into four treatments for 30 days, including a control group (basal diet) and a basal diet supplemented with 1%, 2%, and 4% fermented AAR, respectively. The results showed that the optimized fermentation conditions of AAR were 80% moisture content, 3% inoculation quantity, 34 °C fermentation for 6 days, initial pH at 8, and 60 mesh (sieving). The compounds of 2-furyl-5-methyl furan, deoxyartemisinin, phytol, n-hexadecanoic acid, aromandendrene, and calarene had higher contents (average 6.86%) in the fermented AAR. The bacteria of Proteobacteria and Firmicutes (average 45.18%) were the most abundant phyla, and Acinetobacter, Bacillus, and Brevundimonas (average 15.87%) were the most abundant genera in the fermented AAR. The fungi of Phragmoplastophyta, Vertebrata, and Ascomycota (average 30.13%) were the most abundant phyla, and Magnoliophyta, Mammalia, Wickerhamomyces-Candida_clade, and Aspergillus were the most abundant genera (average 21.12%) in the fermented AAR. Furthermore, dietary supplementation of fermented AAR increased the average daily feed intake (ADFI), egg weight, and albumen height. Dietary supplementation of 2% and 4% fermented AAR increased the laying rate, while 2% fermented AAR increased the Haugh unit and decreased the feed-to-egg ratio. Collectively, it is concluded that fermented AAR has the potential to become a phytogenic feed additive, and dietary supplementation of 2% fermented AAR had better effects on the production performance of laying hens.

Optimization Conditions for Ethanol Production from Sweet Sorghum Juice by Thermotolerant Yeast Saccharomyces cerevisiae: Using a Statistical Experimental Design

The optimum fermentation conditions for ethanol production from sweet sorghum juice (SSJ) by the thermotolerant yeast Saccharomyces cerevisiae DBKKUY-53 were determined using a statistical experimental design. Based on the Plackett–Burman design (PBD), yeast cell concentration, sugar concentration, and yeast extract were the significant independent fermentation factors affecting the ethanol production from SSJ at 37 °C by S. cerevisiae DBKKUY-53. These significant factors were optimized using response surface methodology (RSM) based on a central composite design (CCD). The result revealed that the optimum conditions for ethanol fermentation were 7.85 × 107 cells/mL yeast cell concentration, 247 g/L sugar concentration, and 9.99 g/L yeast extract. Verification of the ethanol production using the optimum conditions revealed that the maximum ethanol concentration of 99.75 g/L and the productivity of 2.77 g/L/h were achieved. When the ethanol production was carried out in a 2 L fermentor under optimum conditions, the ethanol concentration was 101.81 g/L and the productivity was 2.83 g/L/h. This finding suggested that the thermotolerant yeast S. cerevisiae DBKKUY-53 has excellent potential for commercial ethanol production at high temperatures.

The Isolation, Screening, and Characterization of Polyhydroxyalkanoate-Producing Bacteria from Hypersaline Lakes in Kenya

Extremophilic microorganisms such as those that thrive in high-salt and high-alkaline environments are promising candidates for the recovery of useful biomaterials including polyhydroxyalkanoates (PHAs). PHAs are ideal alternatives to synthetic plastics because they are biodegradable, biocompatible, and environmentally friendly. This work was aimed at conducting a bioprospection of bacteria isolated from hypersaline-alkaliphilic lakes in Kenya for the potential production of PHAs. In the present study, 218 isolates were screened by Sudan Black B and Nile Red A staining. Of these isolates, 31 were positive for PHA production and were characterized using morphological, biochemical, and molecular methods. Through 16S rRNA sequencing, we found that the isolates belonged to the genera Arthrobacter spp., Bacillus spp., Exiguobacterium spp., Halomonas spp., Paracoccus spp., and Rhodobaca spp. Preliminary experiments revealed that Bacillus sp. JSM-1684023 isolated from Lake Magadi had the highest PHA accumulation ability, with an initial biomass-to-PHA conversion rate of 19.14% on a 2% glucose substrate. Under optimized fermentation conditions, MO22 had a maximum PHA concentration of 0.516 g/L from 1.99 g/L of cell dry weight and 25.9% PHA conversion, equivalent to a PHA yield of 0.02 g/g of biomass. The optimal PHA production media had an initial pH of 9.0, temperature of 35 °C, salinity of 3%, and an incubation period of 48 h with 2.5% sucrose and 0.1% peptone as carbon and nitrogen sources, respectively. This study suggests that bacteria isolated from hypersaline and alkaliphilic tropical lakes are promising candidates for the production of polyhydroxyalkanoates.

Carboxyl-containing components delineation via feature-based molecular networking: A key to processing conditions of fermented soybean

Carboxyl-containing components (CCCs) was the key chemical markers for fermented soybean, whose composition and content would be dramatically changed during the fermentation processes. To select the optimal fermented conditions, a rapid and sensitive 5-(diisopropylamino)amylamine derivatization, ultra-high performance liquid chromatography-quadrupole-time-of-flight/mass spectrometry and feature-based molecular networking method was established for determination CCCs and the developed method was successfully applied to compare the dynamic changes of CCCs under different processing conditions. A total of 120 components were identified, the optimum fermentation conditions were the temperature at 30 °C, 50% humidity, with a 2-hour steaming time. Sixteen chemical markers with significant differences were screened. Furthermore, molecular docking technology was used to verify the antiperoxidative effect of these chemical markers. Accordingly, we focused on the high-content, little-studied active CCCs rather than the low-content and well-studied flavonoids. This study was helpful for the nutraceutical development and contributed scientific basis to further exploring quality evaluation of fermented food.

Fermented Gynochthodes officinalis (F.C.How) Razafim. & B.Bremer alleviates diabetic erectile dysfunction by attenuating oxidative stress and regulating PI3K/Akt/eNOS pathway.

As a traditional Chinese medicine, Gynochthodes officinalis (F.C.How) Razafim. & B.Bremer (G. officinalis) has been historically as tonics to treat impotence. Fermentation is an ancient processing method for traditional Chinese medicine. Whether fermentation affects the therapeutic effects of G. officinalis on diabetic erectile dysfunction has so far remained unknown. In this research, we aim to determine the effect of fermented or unfermented G. officinalis root extract on diabetes mellitus-induced erectile dysfunction (DMED) and the potential mechanisms. Candida sp. B5, Lactobacillus sp. Y5 and Lactobacillus sp. R2 are applied for the fermentation of G. officinalis. The optimum fermentation conditions of G. officinalis are investigated. Sprague-Dawley rats were used to establish a diabetic erectile dysfunction model, treated with different concentrations of fermented or unfermented G. officinalis, to compare the effect of fermented or unfermented G. officinalis on DMED and explore underlying mechanisms by assessment of intracavernous pressure, ELISA, Western blot, Masson's trichrome staining, and immunofluorescence. The corpus cavernosum smooth muscle cells (CCSMCs) and Schwann cells were isolated and used to investigate the effect of fermented or unfermented G. officinalis on hydrogen peroxide (H2O2)-induced apoptosis. The results reveal the optimum fermentation conditions of G. officinalis using Lactobacillus sp. Y5 were determined to be 35°C, the ratio of solid to liquid 1:10, and six days of fermentation. The fermentation increases the abundance of major active ingredients within G. officinalis. After fermented or unfermented G. officinalis treatment for eight weeks by oral gavage at a dose of 100mgkg-1 or 300mgkg-1, the results show that the fermentation enhances the effect of G. officinalis on diabetic erectile dysfunction detected by intracavernous pressure. The protein expressions of the PI3K/Akt/eNOS pathway were upregulated in diabetic rats after fermented or unfermented G. officinalis treatment, while the level of oxidative stress was significantly reduced. Meanwhile, Masson's trichrome staining also displayed an improvement in the ratio of smooth muscle to collagen. In vitro experiments confirmed that fermented or unfermented G. officinalis protected CCSMCs and Schwann cells from apoptosis. In contrast, fermented G. officinalis showed a fortified protective effect over unfermented G. officinalis. Our findings suggest that fermentation can increase the composition of main active ingredients in G. officinalis and enhance its role in diabetic erectile dysfunction. It augurs the potential therapeutic application of fermented G. officinalis well for treating diabetic erectile dysfunction.

Optimization of Fermentation Conditions for Elevating Limonene Production with Engineered Rhodosporidium toruloides

Limonene is a valuable monoterpenoid with diverse applications in food, medicine, agriculture, etc. Currently, the commercial production of limonene from citrus pomace cannot meet the evergrowing market demand. With the development of synthetic biology, microbial biosynthesis is offering a sustainable alternative to plant-based extraction. However, the performance of engineered strains can be affected by many factors including the microbial host, the cultivation conditions, etc. Therefore, in the present study, potential factors that influence the limonene production of the engineered strains were investigated through single-factor and orthogonal experiments. The optimized medium was MM, with a working volume of 50 mL, inoculum OD600 = 0.6, 22 °C, pH 6, and a dodecane coverage (v/v) of 20%. The final limonene titer was improved from 52.5 to 358.1 mg/L, a 586% net increase in titer and 34.8-fold improvement in production efficiency (mg/OD600) on 250-mL flasks. The results here demonstrated that R. toruloides could be explored as an efficient limonene producer and could facilitate the study of the biosynthesis of other terpenes using R. toruloides.

Adding Metal Ions to the Bacillus mojavensis D50 Promotes Biofilm Formation and Improves Ability of Biocontrol

Bacillus mojavensis D50, a biocontrol strain, is used to prevent and treat the fungal plant pathogen Botrytis cinerea. Bacillus mojavensis D50's biofilms can affect its colonization; thus, the effects of different metal ions and culture conditions on biofilm formation were determined in this study. The results of medium optimization showed that Ca2+ had the best ability to promote biofilm formation. The optimal medium composition for the formation of biofilms contained tryptone (10 g/L), CaCl2 (5.14 g/L), and yeast extract (5.0 g/L), and the optimal fermentation conditions included pH 7, a temperature of 31.4 °C, and a culture time of 51.8 h. We found that the antifungal activity and abilities to form biofilms and colonize roots were improved after optimization. In addition, the levels of expression of the genes luxS, SinR, FlhA, and tasA were up-regulated by 37.56-, 2.87-, 12.46-, and 6.22-fold, respectively. The soil enzymatic activities which related biocontrol-related enzymes were the highest when the soil was treated by strain D50 after optimization. In vivo biocontrol assays indicated that the biocontrol effect of strain D50 after optimization was improved.

Optimization parameters for the production of dimer of epicatechin from an endophytic fungus Curvularia australiensis FC2AP using response surface methodology (RSM)

The search for natural therapeutic agents has intensified due to their potential to treat various diseases. Bioactive secondary metabolites from endophytes offer high therapeutic profiles and can be mass-produced after optimizing medium parameters and purification. This investigation aimed to maximize crude pigmented secondary metabolite (CPSM) production from Curvularia australiensis FC2AP by optimizing fermentation conditions statistically. The endophytic fungus produced a maximum yield of 8.81 UL/g from biomass using Sabouraud's Dextrose Broth. After screening essential factors, the Plackett-Burman design was used for factorial optimization, and the Box Behnken design was employed to investigate three significant factors. The final CPSM yield was 12.3 UL/g, approximately 4-fold higher than the preliminary growth medium. Chromatographic purification using a gradient solvent system resulted in six fractions, with the fourth fraction demonstrating the highest bioactivity profile. Structural characterization confirmed this fraction to be a dimer of epicatechin, which has anti-cancer properties, as confirmed through in vivo studies on Sprague Dawley rats. This is the first report of a epicatechin dimer produced from C. australiensis.