Corn Steep Liquor Research Articles

Enhancing the volatile organic compound and biomass production by three biocontrol potential bacteria in corn steep liquor growth medium and development of cell freeze-drying process.

This study investigates the traits of three plant growth-promoting (PGP) and antagonistic bacteria, Pseudomonas protegens MP12, Bacillus sp. 3R4, and Bacillus sp. T22, to assess their potential application as biocontrol agents by using the ecofriendly and low-cost substrate Corn Steep Liquor (CSL) medium. Analyses of antagonism through volatile organic compounds (VOCs) production, biofilm formation, and growth performance were carried out. Dual antagonism assay showed that all strains displayed significant antagonistic activity against Botrytis cinerea through VOCs. Gas chromatography demonstrated that strains in the CSL exhibited higher VOCs production than Nutrient medium. Moreover, enhanced biofilm formation analysed by Calgary Biofilm Device, growth and biomass were noted in CSL cultures. Pseudomonas protegens MP12, which showed higher cell concentration and biomass yield, was selected for freeze-drying treatments. Storage cell viability assays evidenced that it can be effectively preserved for nearly 7 months at 4°C. The results here obtained showed that CLS medium enhance VOCs production, biofilm formation, growth and biomass of the antagonistic bacteria of the three strains. Eventually, the more effective strain P. protegens MP12 can be stored for nearly 7 months at 4°C.

Strategies to reduce the culture medium costs for a high‐yield and high‐selectivity bio‐based 2,3‐butanediol production

AbstractBio‐based 2,3‐butanediol (2,3‐BDO) production on a large scale depends on critical factors, such as culture medium, oxygen supply, pH and biosafety. In this study, three strategies for reducing culture medium costs were investigated: carbon/nitrogen (C/N) ratio; low‐cost nitrogen sources (crude yeast extract, brewer's yeast extract, corn steep liquor, urea, sodium nitrate, ammonium chloride, ammonium sulfate and dibasic ammonium phosphate); and microbial pH autoregulation. Batch fermentations were performed in a microaerobic environment using wild‐type and safe Paenibacillus peoriae NRRL BD 62. The yield and selectivity of 2,3‐BDO were used as control variables. A ratio between 2,3‐BDO production and glucose consumption (YP/S) of almost 80% and an optical purity of 87% levo‐2,3‐BDO, with no acetoin accumulation, were achieved in an NH4Cl‐based medium at C/N = 8.5 g/g and without external pH control, considering an initial glucose of 10 g/L. Based on Free on Board prices, a 63% savings in culture medium costs was achieved by replacing commercial yeast extract at pH 5. Validation assays with higher initial glucose concentrations showed a YP/S of 0.40 g/g and an optical levo‐/meso‐2,3‐BDO ratio of 1:0.8, with negligible acetoin accumulation. Therefore, the NH4Cl‐based medium at C/N = 8.5 g/g and without pH control was considered economically promising for high‐yield and high‐selectivity bio‐based 2,3‐BDO production.

Sustainable Production of Shinorine from Agricultural Wastes Using Engineered Saccharomyces cerevisiae Expressing Novel d-Alanine-d-alanine Ligase from Pseudonocardia pini.

Shinorine, a compound known for its protective properties against UV radiation, is widely used in cosmetics and pharmaceuticals. Despite the construction of various recombinant Saccharomyces cerevisiae strains for shinorine production, achieving industrial-scale yields remains a challenge. In this study, genes encoding enzymes (DDGS, O-MT, and ATP-grasp enzyme) from Actinosynnema mirum were introduced into S. cerevisiae DXdT to enable the heterologous conversion of sedoheptulose 7-phosphate to mycosporine-glycine─the direct biosynthetic precursor of shinorine. Subsequently, a novel d-alanine-d-alanine ligase from Pseudonocardia pini was introduced to produce shinorine. The engineered strain (DXdT-MG-mi89-PP.ddl) produced 267.9 mg/L shinorine with a 48.6 mg/g dry cell weight (DCW) content in a medium supplemented with lignocellulosic hydrolysate derived from rice straw. Notably, the recombinant strain produced 1.7 g/L shinorine with a 79.1 mg/g DCW content from a corn steep liquor medium with a mixture of glucose and xylose. These results support the idea that sustainable shinorine production from agricultural wastes holds significant promise for industrial applications.

Biosurfactant production by Bacillus cereus GX7 utilizing organic waste and its application in the remediation of hydrocarbon-contaminated environments.

The use of biosurfactants represents a promising technology for remediating hydrocarbon pollution in the environment. This study evaluated a highly effective biosurfactant strain-Bacillus cereus GX7's ability to produce biosurfactants from industrial and agriculture organic wastes. Bacillus cereus GX7 showed poor utilization capacity for oil soluble organic waste but effectively utilized of water- soluble organic wastes such as starch hydrolysate and wheat bran juice as carbon sources to enhance biosurfactant production. This led to significant improvements in surface tension and emulsification index. Corn steep liquor was also effective as a nitrogen source for Bacillus cereus GX7 in biosurfactant production. The biosurfactants produced by strain Bacillus cereus GX7 demonstrated a remediation effect on oily beach sand, but are slightly inferior to chemical surfactants. Inoculation with Bacillus cereus GX7 (70.36%) or its fermentation solution (94.38%) effectively enhanced the degradation efficiency of diesel oil in polluted seawater, surpassing that of indigenous degrading bacteria treatments (57.62%). Moreover, inoculation with Bacillus cereus GX7's fermentation solution notably improved the community structure by increasing the abundance of functional bacteria such as Pseudomonas and Stenotrophomonas in seawater. These findings suggest that the Bacillus cereus GX7 as a promising candidate for bioremediation of petroleum hydrocarbons.

Pilot scale production of high-content mycoprotein using Rhizopus microsporus var. oligosporus by submerged fermentation and agro-industrial by-products

While mycoprotein has gained traction as a human food source, its potential as a nutrient for animals remains largely unexplored. The mycoprotein-producing Rhizopus microsporus var. oligosporus, a fungus traditionally used for human food in Indonesia, is promising. It could revolutionise animal nutrition once it is Generally Recognized as Safe (GRAS) and is a biosafety level 1 (BSL1) organism. To enhance sustainably, we propose using sugar cane molasses (SM) and corn steep liquor (CSL) as nutrient sources. Also, we investigated the growth of R. microsporus var. oligosporus in five 14 L external-loop airlift bioreactors using CSL as the sole nutrient source. After 96 h of fermentation, at 25 °C and 0.5 vvm, the mycelium produced had an average biomass yield of 38.34 g L−1, with 70.18 % (m v−1) crude protein (mycoprotein). This bioprocess, which is scalable and economically viable, produces high amounts of mycoprotein for animal feed using CSL, a cost-effective agro-industrial by-product, providing a practical solution to the growing demand for animal protein.

Investigation of Acetoin Biosynthesis by Bacillus subtilis ACA-DC 1176 Growing on Crude Glycerol in Flask and Bioreactor Trials

Acetoin biosynthesis by two Bacillus subtilis strains valorising crude glycerol was thoroughly explored within a pre-defined range of culture conditions and systems. B. subtilis ACA-DC 1176 stood out for its higher efficiency in acetoin production, prompting an investigation into the potential for enhanced productivity through the evaluation of diverse culture conditions and media compositions. The primary by-products of the biodiesel and corn industries, namely crude glycerol and corn steep liquor, respectively, were successfully employed as the principal carbon and nitrogen sources of the newly developed low-cost culture medium. Furthermore, the results of the various feeding strategies that were tested indicated that the conversion of 2,3-butanediol (BDO) to acetoin occurred exclusively when the concentration of glycerol was below approximately 5 g/L. This seemed to be necessary for the production of NADH, which is essential for maintaining cellular processes. Following the complete depletion of glycerol, acetic acid increased and became the predominant metabolite, while both acetoin and BDO decreased, presumably resulting in ATP generation. This is likely a mechanism employed by the cell to generate energy in the absence of a carbon source. In the fed-batch bioreactor culture, the kinetics of metabolites differed, as there was no conversion of BDO to acetoin at the final depletion of glycerol. At volumetric mass transfer coefficient (kLa) levels exceeding approximately 70 1/h, the production of acetoin was favoured over that of BDO, with the highest observed acetoin/BDO ratio reaching 4.29 g/g. Conversely, at kLa values below approximately 60 1/h, the titres of acetoin and BDO were found to be nearly equal. The final concentrations of acetoin and BDO reached 36.0 g/L and 25.5 g/L, respectively, resulting in a total yield of both (acetoin + BDO) per glycerol consumption of 0.40 g/g. To the best of our knowledge, this is the first study to focus on acetoin production from crude glycerol fermentative valorisation. The study presents new findings regarding the parameters influencing the level of BDO conversion to acetoin. However, further research is required in order to gain a comprehensive understanding of the underlying phenomena and metabolic pathways involved.

Esterification Process in Supercritical Carbon Dioxide Catalyzed by Geotrichum candidum Lipase Produced with Mozzarella Cheese Whey and Corn Steep Liquor

The valorization of industrial waste in the production of new products is a growing trend, with food waste showing significant promise as a raw material for various industries. Thus, this research aimed to investigate the production of Geotrichum candidum lipase using industrial waste, such as mozzarella cheese whey (MCW) and corn steep liquor (CSL), and to analyze how effectively it catalyzes the esterification of oleic acid with methanol. Lipase production was carried out in medium containing MCW and CSL, with fermentation conditions optimized using a fractional factorial experimental design and central composite experimental design. The highest activities (16.71 U/mL in 24 h and 17.80 U/mL in 48 h) were found in conditions of 13.6% (%w/v) CSL and 37.1% (%w/v) MCW, with corn oil fixed at 1% (%w/v) and pH fixed at 6,00. Esterification conditions were evaluated at atmospheric pressure, both in a solvent-free environment and using hexane, as well as under high pressures with supercritical carbon dioxide (SC-CO2). The produced lipase demonstrated high catalytic activity for the esterification reaction of oleic acid with methanol under SC-CO2 with an increase of 39.41% in the yield. The yields found confirm the feasibility of producing lipase from industrial waste, thus presenting it as a sustainable and efficient alternative for industrial processes, and show that there is no need to use toxic organic solvents in esterification reactions.

Sustainable cultivation of Porphyridium cruentum via agro-industrial by-products: A study on biomass and lipid enhancement

This study explored the cultivation of Porphyridium cruentum using beet molasses and corn steep liquor (CSL) as alternative agri-waste substrates. The objective was to enhance the biomass and lipid production of P. cruentum, known for its potential as an industrial EPA producer. Using a Box-Behnken Design (BBD) as part of the response surface methodology (RSM), we investigated the effects of beet molasses, CSL, and F/2 nutrients on the microalga's cultivation. The results demonstrated a significant influence of these factors on the final cell count and lipid content over an 8-day cultivation period. Specifically, optimal growth conditions were identified at approximately 1.78 g/L of molasses and 1.89 g/L of CSL, yielding a cell count of 12.1 × 106 cells/mL and a lipid content of 24.48%. Validation experiments reaffirmed these findings, with observed results closely aligning with predicted values. Optimized media achieved also a significant higher content of carotenoids and phycobiliproteins compared to the standard media. This research highlights the potential of using agro-industrial by-products for large-scale cultivation of P. cruentum, offering a sustainable approach for enhancing lipid and pigment production.

Production and Application of a New Biosurfactant for Solubilisation and Mobilisation of Residual Oil from Sand and Seawater

Significant research has been conducted to minimise environmental impacts and promote the sustainable use of resources and raw materials. Microbial surfactants are an example of advanced materials obtained from sustainable production processes. In the present study, a biosurfactant was produced by the yeast Starmerella bombicola ATCC 22214 grown in a previously selected low-cost mineral medium containing 10% sucrose, 1.2% canola oil, and 0.5% corn steep liquor. The biosurfactant reduced surface tension from 72 ± 0.1 to 32.76 ± 0.3 mN/m. The yield was 23 g/L, and the critical micelle concentration was 0.6 g/L. The biosurfactant emulsified 96.25 ± 0.08% of used motor oil, was characterised as a sophorolipid, and exhibited stability under extreme conditions with no significant loss of its properties. Toxicity was assessed by exposing the microcrustacean Artemia salina and the zebrafish (Danio rerio) to the biosurfactant. The biosurfactant proved efficient for use in remediation processes, removing 97.8% and 69.2% of the petroleum derivative from sand in kinetic and static tests, respectively, and removed 91.5% of the contaminant from seawater. The results indicate the potential of this new biosurfactant for the mobilisation and solubilisation of hydrocarbons in the marine environment. This green biomolecule is a promising technology for the replacement of chemical dispersants in the remediation of aquatic and soil systems.

Enhancing Protein Content in Wild-Type Saccharomyces cerevisiae via Random Mutagenesis and Optimized Fermentation Conditions.

Single-cell protein (SCP) derived from microorganisms is widely recognized as a viable alternative protein source for the future. Nevertheless, the commercialization of yeast-based SCP is hampered by its relatively low protein content. Therefore, this study aimed to enhance the protein content of Saccharomyces cerevisiae via random mutagenesis. To achieve this, S. cerevisiae KCCM 51811, which exhibited the highest protein concentration among 20 edible S. cerevisiae strains, was selected as a chassis strain. Subsequently, a KCCM 51811 mutant library was constructed (through UV irradiation) and screened to isolate mutants exhibiting high protein content and/or concentration. Among the 174 mutant strains studied, the #126 mutant exhibited a remarkable 43% and 36% higher protein content and concentration, respectively, compared to the parental strain. Finally, the #126 mutant was cultured in a fed-batch system using molasses and corn-steep liquor, resulting in a protein concentration of 21.6 g/l in 100 h, which was 18% higher than that produced by the parental strain. These findings underscore the potential of our approach for the cost-effective production of food-grade SCP.

Evaluation of corn steep liquor on the digestibility and growth performance of juvenile common carp strain Sinyonya

This study aimed to observe the digestibility performance, digestive enzyme activity, and growth performance of the common carp using corn-steep liquor (CSL). The reference diet used commercial feed with 30% protein, and the test diet used CSL at 0% (CSL0), 10% (CSL10), 20% (CSL20), and 30% (CSL30). Common carp (9.38 ± 0.73 g) were stocked at 10 fish per aquarium. Feeding was performed until apparent satiation thrice daily for the 45-day maintenance period. The study used a completely randomized design with four treatments and four replications. The results showed that CSL contained 44.04% protein and an essential amino acid index of 0.80. The additional dose of CSL reduced feed pH and stomach pH compared to the control due to the lactic acid content. In addition, CSL elevated the activity of protease, amylase, and lipase enzymes in the digestive tract of common carp. By applying 20% dose in formulated diet, CSL could increase the total digestibility, ingredient digestibility, protein digestibility, lipid digestibility, and energy digestibility. The high feed digestibility value in the CSL20 treatment was due to the fish ability to utilize carbohydrates and fats as non-protein energy sources, thus producing higher final weight, daily growth rate, and feed conversion ratio. The results of this study indicate that CSL can be used as a source of plant protein for the common carp diet, whereas an administration of CSL at 20% in diet improves the digestibility performance, digestive enzyme activity, and growth performance of common carp. Keywords: common carp, corn steep liquor, digestibility, enzyme, growth ABSTRAK Tujuan penelitian ini untuk melihat kinerja kecernaan, aktivitas enzim pencernaan dan pertumbuhan ikan mas Sinyonya (Cyprinus carpio) menggunakan bahan baku corn steep liquor (CSL) sebagai sumber protein nabati. Pakan acuan menggunakan pakan komersial dengan protein 30% dan pakan uji menggunakan CSL sebanyak 0% (CSL0), 10% (CSL10), 20% (CSL20) dan 30% (CSL30). Pengukuran kecernaan menggunakan indikator Cr2O3 0,5 %. Ikan mas Sinyonya dengan bobot tubuh rata-rata 9,38 ± 0,73 g dipelihara dalam akuarium 60×50×40 cm3 dengan kepadatan 10 ekor per akuarium. Pakan diberikan secara at satiation sebanyak 3 kali sehari selama 45 hari masa pemeliharaan. Penelitian menggunakan desain rancangan acak lengkap dengan empat perlakuan dan masing-masing empat ulangan. Hasil penelitian menunjukkan bahwa CSL mengandung protein sebesar 44,04%, dan indeks asam amino essensial 0,80. Penambahan dosis CSL secara signifikan menurunkan pH pakan dan pH lambung dibandingkan dengan kontrol karena kandungan asam laktat. Sampai dengan dosis CSL 20%, dapat meningkatkan aktivitas enzim protease, amilase dan lipase pada saluran pencernaan ikan mas Sinyonya. Di samping itu, penambahan CSL 20% meningkatkan nilai kecernaan total, kecernaan bahan, kecernaan lemak dan kecernaan energi. Nilai kecernaan pakan yang tinggi pada perlakuan CSL20 disebabkan karena kemampuan ikan dalam memanfaatkan karbohidrat dan lemak sebagai sumber energi non-protein. Disamping itu penambahan CSL sampai dengan dosis 20% meningkatkan bobot akhir, laju pertumbuhan harian dan rasio konversi pakan. Hasil penelitian ini menunjukkan bahwa CSL dapat digunakan sebagai sumber protein nabati untuk pakan ikan mas Sinyonya dan pemberian CSL pada level 20% dapat meningkatkan kinerja kecernaan, aktivitas enzim pencernaan dan pertumbuhan ikan. Kata kunci: corn steep liquor, enzim, ikan mas Sinyonya, kecernaan, pertumbuhan

Corn Steep Liquor as an Auto-Induction Medium for the Production of rhIFN-β-1b Protein in Escherichia coli

Corn Steep Liquor as an Auto-Induction Medium for the Production of rhIFN-β-1b Protein in Escherichia coli

Enrichment of Fruit Peels' Nutritional Value by Solid-State Fermentation with Aspergillus ibericus and Rhizopus oryzae.

The fruit processing industry is responsible for disposing of huge amounts of byproducts, especially fruit peels (FPs), which are often discarded in landfills. Using FPs in biotechnological processes contributes to a circular economy, reducing the environmental burden of FPs and increasing the revenue of the fruit processing industry. This study was focused on upgrading the nutritional value of orange (OPs) and banana (BPs) peels by solid-state fermentation (SSF) with filamentous fungi. SSF factors (moisture, fermentation time, inoculum size, ammonium sulfate (AS), and corn steep liquor (CSL)) and fungi species (Aspergillus ibericus and Rhizopus oryzae) were studied by a variable screening Plackett-Burman design. Both fungi grew on untreated FPs, increasing their protein content and antioxidant activity. Moisture, AS, and CSL were further studied by a Box-Behnken design with A. ibericus. Fermented OPs at 70% moisture and 0.005 g/g AS increased their protein content by 200%, whereas BPs at 70% moisture and 0.005 g/g CSL increased by 123%. Fermented peels were enriched in protein, fiber, and minerals, with a low content of carbohydrates and soluble sugars. Fermented OPs and BPs showed higher antioxidant activity than unfermented peels. The SSF of these FPs is an innovative approach that contributes to obtaining rich nutrient-fermented peels for food.

Crow Search Algorithm for Modelling an Anaerobic Digestion Process: Algorithm Parameter Influence

Corn steep liquor is a waste product from the process of treating corn grain for starch extraction. It is used as a substrate in anaerobic digestion with simultaneous hydrogen and methane production in a cascade of two anaerobic bioreactors. For process research and optimisation, adequate mathematical models are required. So, the authors aim to present a high-quality model of the corn steep liquor process for the sequential production of H2 and CH4. This paper proposes a technique for identifying the best mathematical model of the process using the metaheuristics crow search algorithm (CSA). The CSA was applied for the first time to mathematical modelling of the considered two-stage anaerobic digestion process, using real experimental data. Based on the analysis of the numerical data from the model parameter identification procedures, the influence of the main CSA parameters—the flight length, fl, and the awareness probability, AP—was investigated. Applying classical statistical tests and an innovative approach, InterCriteria Analysis, recommendations about the optimal CSA parameter tuning were proposed. The best CSA algorithm performance was achieved for the AP = 0.05, fl = 3.0, followed by AP = 0.10, fl = 2.5, and AP = 0.15, fl = 3.0. The optimal tuning of the CSA parameters resulted in a 29% improvement in solution accuracy. As a result, a mathematical model of the considered two-stage anaerobic digestion process with a high degree of accuracy was developed.

Assessing the impact of corn steep liquor as an inducer on enhancing laccase production and laccase gene (Lac1) transcription in Pleurotus pulmonarius during solid-state fermentation

Laccases are crucial for agro-waste delignification in sustainable practices. Considering the necessity for cost-effective laccase pretreatments in industrial applications, numerous efforts have been directed towards identifying potential enzyme inducers for increasing laccase production. This study explored corn steep liquor as a cost-effective laccase inducer in Pleurotus pulmonarius solid substrate fermentation of tender coconut fiber. Utilizing tender coconut fiber for laccase production offers dual benefits of fiber valorisation and enzyme synthesis sustainably. We investigated the impact of corn steep liquor on transcription of Lac1 gene in P. pulmonarius and on extracellular laccase activity. Adding 2 % CSL notably boosted laccase production (314.62 + 5.93 IU/mL) and increased Lac1 transcript levels by 5.6-fold compared to non-induced cultures. SEM analysis revealed improved delignification as a result of increased laccase production. Our findings suggest that corn steep liquor serves as an inducer for regulating laccase gene expression in P. pulmonarius, leading to increased extracellular laccase production.

Biosynthesis of propionic acid from whey permeate and corn steep liquor by Propionibacterium freudenreichii subsp ATCC 6207 and partial purification using ion exchange cryogels

Biosynthesis of propionic acid from whey permeate and corn steep liquor by Propionibacterium freudenreichii subsp ATCC 6207 and partial purification using ion exchange cryogels

The Formulation of a Natural Detergent with a Biosurfactant Cultivated in a Low-Cost Medium for Use in Coastal Environmental Remediation

Green surfactants have significant potential for improving environmental remediation methods. The aim of the present study was to formulate a green natural detergent containing the biosurfactant produced by Starmerella bombicola ATCC 22214 grown in 1.2% canola oil, 10% sucrose, and 0.5% corn steep liquor. The biosurfactant reduced surface tension to 31.84 mN/m and was produced at a yield of 22 g/L. Twelve formulations were proposed using cottonseed oil as the natural solvent and different stabilisers (vegetable wax, hydroxyethyl cellulose, and sodium alginate). The detergent was evaluated for its emulsifying capacity and stability over a 10-day period. Ecotoxicity was investigated using the marine recruitment test on metal plates covered with paint into which the biosurfactant was incorporated as well as tests with a microcrustacean and vegetable seeds. The formulation designated H, consisting of 1% biosurfactant, 40% cottonseed oil, and 2% hydroxyethyl cellulose, achieved the best results. The formulation exhibited both stability and emulsifying capacity (100% of petroleum). The ecotoxicity tests revealed the safety of the natural detergent. The detergent achieved satisfactory oil dispersion and solubilised 98% of the oil impregnated on the rock. The results indicate that the natural detergent holds promise for efficiently cleaning up environmental areas contaminated with oil and petroleum products.

Efficient Fermentative Production of β-Alanine from Glucose through Multidimensional Engineering of Escherichia coli.

β-Alanine, a valuable β-type amino acid, is experiencing increased demand due to its multifaceted applications in food flavoring, nutritional supplements, pharmaceuticals, and the chemical industry. Nevertheless, the sustainable biosynthesis of β-alanine currently faces challenges due to the scarcity of robust strains, attributed to the complexities of modulating multiple genes and the inherent physiological constraints. Here, systems metabolic engineering was implemented in Escherichia coli to overcome these limitations. First, an efficient l-aspartate-α-decarboxylase (ADC) was recruited for β-alanine biosynthesis. To conserve phosphoenolpyruvate flux, we subsequently modified the endogenous glucose assimilation system by inactivating the phosphotransferase system (PTS) and introducing an alternative non-PTS system, which increased β-alanine production to 1.70 g/L. The supply of key precursors, oxaloacetate and l-aspartate, was synergistically improved through comprehensive modulation, including strengthening main flux and blocking bypass metabolism, which significantly increased the β-alanine titer to 3.43 g/L. Next, the expression of ADC was optimized by promoter and untranslated region (UTR) engineering. Further transport engineering, which involved disrupting β-alanine importer CycA and heterologously expressing β-alanine exporter NCgI0580, improved β-alanine production to 8.48 g/L. Additionally, corn steep liquor was used to develop a cost-effective medium. The final strain produced 74.03 g/L β-alanine with a yield of 0.57 mol/mol glucose during fed-batch fermentation.

Fermentative Production of Ergothioneine by Exploring Novel Biosynthetic Pathway and Remodulating Precursor Synthesis Pathways.

Ergothioneine (EGT) is a naturally occurring derivative of histidine with diverse applications in the medicine, cosmetic, and food industries. Nevertheless, its sustainable biosynthesis faces hurdles due to the limited biosynthetic pathways, complex metabolic network of precursors, and high cost associated with fermentation. Herein, efforts were made to address these limitations first by reconstructing a novel EGT biosynthetic pathway from Methylobacterium aquaticum in Escherichia coli and optimizing it through plasmid copy number. Subsequently, the supply of precursor amino acids was promoted by engineering the global regulator, recruiting mutant resistant to feedback inhibition, and blocking competitive pathways. These metabolic modifications resulted in a significant improvement in EGT production, increasing from 35 to 130 mg/L, representing a remarkable increase of 271.4%. Furthermore, an economical medium was developed by replacing yeast extract with corn steep liquor, a byproduct of wet milling of corn. Finally, the production of EGT reached 595 mg/L with a productivity of 8.2 mg/L/h by exploiting fed-batch fermentation in a 10 L bioreactor. This study paves the way for exploring and modulating a de novo biosynthetic pathway for efficient and low-cost fermentative production of EGT.

Evaluation of hydrolyzed cheese whey medium for enhanced bacterial cellulose production by Komagataeibacter rhaeticus MSCL 1463.

Industrial production of bacterial cellulose (BC) remains challenging due to significant production costs, including the choice of appropriate growth media. This research focuses on optimization of cheese whey (CW) based media for enhanced production of BC. Two modifications were made for CW medium for BC production with Komagataeibacter rhaeticus MSCL 1463. BC production in a medium of enzymatically hydrolyzed CW (final concentration of monosaccharides: glucose 0.13g L-1, galactose 1.24g L-1) was significantly enhanced, achieving a yield of 4.95±0.25g L-1, which markedly surpasses the yields obtained with the standard Hestrin-Schramm (HS) medium containing 20g L-1 glucose and acid-hydrolyzed CW (final concentration of monosaccharides: glucose 1.15g L-1, galactose 2.01g L-1), which yielded 3.29±0.12g L-1 and 1.01±0.14g L-1, respectively. We explored the synergistic effects of combining CW with various agricultural by-products (corn steep liquor (CSL), apple juice, and sugar beet molasses). Notably, the supplementation with 15% corn steep liquor significantly enhanced BC productivity, achieving 6.97±0.17g L-1. A comprehensive analysis of the BC's physical and mechanical properties indicated significant alterations in fiber diameter (62-167nm), crystallinity index (71.1-85.9%), and specific strength (35-82MPa × cm3 g-1), as well as changes in the density (1.1-1.4g cm-3). Hydrolyzed CW medium supplemented by CSL could be used for effective production of BC.