Fermentation Medium Research Articles

Microbial removal of nutrients from anaerobic digestate: assessing product-coupled and non-product-coupled approaches.

Although anaerobic digestate contains >90% water, the high nutrient content of digestate makes it economically and technically intractable to treatment by existing wastewater treatment technologies. This study separately assessed the feasibility of nutrient removal from digestate by Rhizopus delemar DSM 905 and a culture of phosphate-accumulating organisms (PAOs). With Rhizopus delemar DSM 905, we investigated concomitant nutrient removal from digestate-supplemented medium and fumaric acid production, as a potentially economical strategy for digestate treatment. Following the cultivation of R. delemar DSM 905 in a fermentation medium containing 25% (v/v) digestate, the concentrations of Al, Cr, Cu, Fe, K, Mg, Mn, Pb, and Zn reduced 40, 12, 74, 96, 12, 26, 23%, ~18, and 28%, respectively. Similarly, the concentrations of total phosphorus, total nitrogen, phosphate (PO4-P), ammonium (NH4-N), nitrate (NO3-N), and sulfur decreased 93, 88, 97, 98, 69, and 13%, respectively. Concomitantly, cultures supplemented with 25 and 15% (v/v) digestate produced comparable titers of fumarate (~11 and ~ 17 g/L, respectively) to the digestate un-supplemented control cultures. With PAOs, we assessed the removal of total phosphorus, total nitrogen, PO4-P, and NH4-N, of which the concentrations reduced 86, 90%, ~99, and 100%, respectively in 60% (v/v) digestate. This study provides additional bases for microbial removal of excess nutrients from anaerobic digestate, with the potential to engender future water recovery from this waste stream that is currently largely recalcitrant to treatment.

Mushroom mediated selective bioreduction of S-(+)-carvone to cis-(-)-dihydrocarvone: approach towards a safer biocatalysis

Dihydrocarvone, possessing four stereoisomers is an important flavour and chiral building block in chemical synthesis. Ascomycetes are well known for the selective bioreduction of carvone to dihydrocarvone. Often, these fungi produce mycotoxins which may contaminate the biocatalytic product. Herein, Ganoderma sessile, a polypore mushroom, selectively reduced S-(+)-carvone to cis-(-)-dihydrocarvone (DHC) in its submerged culture. In an optimised condition (0.75 g/L, 18 h, pH 3-5, 30 °C and 150 rpm), 82.7% cis-(-)-DHC was obtained in gas chromatography-mass spectrometry profile of the fermented product. The absolute titre of cis-(-)-DHC in fermentation medium was 0.35 ± 0.01 g/L. However, substrate toxicity (IC50 0.15 g/L) drastically reduced the transformation at higher carvone concentration (≥1.0 g/L). On the other hand, R-(-)-carvone was less selective and efficient in producing the desired isomer i.e. trans-(+)-DHC. G. sessile is the member of a group of non-toxic medicinal mushrooms and may be a safer yet efficient option for producing cis-(-)-DHC biocatalytically.

Sustainable bio-manufacturing of D-arabitol through combinatorial engineering of Zygosaccharomyces rouxii, bioprocess optimization and downstream separation

Biosynthesis of D-arabitol, a high value-added platform chemical, from renewable carbon sources provides a sustainable and eco-friendly alternative to the chemical industry. Here, a robust brewing yeast, Zygosaccharomyces rouxii, capable of naturally producing D-arabitol was rewired through genome sequencing-based metabolic engineering. The recombinant Z. rouxii obtained by reinforcing the native D-xylulose pathway, improving reductive power of the rate-limiting step, and inhibiting the shunt pathway, produced 73.61% higher D-arabitol than the parent strain. Subsequently, optimization of the fermentation medium composition for the engineered strain provided 137.36 g/L D-arabitol, with a productivity of 0.64 g/L/h in a fed-batch experiment. Finally, the downstream separation of D-arabitol from the complex fermentation broth using an ethanol precipitation method provided a purity of 96.53%. This study highlights the importance of D-xylulose pathway modification in D-arabitol biosynthesis, and pave a complete and efficient way for the sustainable manufacturing of this value-added compound from biosynthesis to preparation.

Polyethylene glycol/soy lecithin-nanosuspensions as carriers of acetogenins: Optimization, characterization, antibacterial and hemolytic activity

Acetogenins (ACGs) are bioactive compounds with high lipophilicity, which limits their pharmaceutical applications. An alternative to increase ACGs solubility is preparing them into suspended nanoparticles in an aqueous solution. The objective of this study was to formulate nanosuspensions (NSps) as ACG carriers by assessing the impact of various soybean lecithin concentrations (SL 5, 10, and 15 mg/mL), polyethylene glycol 6000 (PEG 0.05 %, 0.1 %, and 0.2 %) and dispersion methods (low agitation at 500 rpm, medium agitation at 10,000 rpm and ultrasound) on particle size and polydispersity index (PDI). The experimental data were performed with a response surface analysis to obtain an optimized, validated, and characterized nanosuspension (OPEGSL-ACGs-NSps) and to measure the antibacterial and hemolytic activity. The optimum conditions to get the OPEGSL-ACGs-NSps with spherical-shaped nanoparticles with a size of 100–113.32 nm, a PDI of 0.19, and a zeta potential of −42.14 mV were 15 mg/mL SL and 0.2 % PEG using low agitation (500 rpm) as dispersion method. In addition, the nanoparticles of optimized NSps presented a high entrapment (92.80 %) and encapsulation efficiency (83.33 %); these parameters were confirmed by spectroscopic analysis. Also, 86 % of ACGs were released until 40 h. Moreover, OPEGSL-ACGs-NSps (with 320 μg/mL of ACGs) caused a significant inhibition against E. faecalis (83 %) and L. monocytogenes (86 %); in contrast, they exhibited no hemolytic activity at 250 and 500 μg/mL of ACGs. The new OPEG-ACGs-NSps are an attractive, promising, and cost-effective alternative to improve ACG solubility, and they could also be safe if administered orally or intravenously at low doses.

Screening of a novel and thermostable nicotinate dehydrogenase-producing strain Bacillus paramycoides for efficient synthesis of 6-hydroxynicotinic acid

6-Hydroxynicotinic acid emerged as a pivotal intermediate for fine chemicals. The current study aims to screen novel nicotinate dehydrogenase-producing strains. Based on the high-throughput UV coloration method, a novel nicotinate dehydrogenase-producing strain named Bacillus paramycoides was first and successfully screened from soil and gram staining as 16S rRNA gene sequencing was conducted to further confirm its accuracy. The fermentation medium formula is determined as seignette salt (5 g/L), tryptone (10 g/L), K2HPO4 (2 g/L), and nicotinic acid (4 g/L) after a single factor and orthogonal test. The activity of nicotinate dehydrogenase produced by B. paramycoides after optimization reached 1.23 U/mL, which was the highest ever reported. In addition, the enzyme characterization results revealed that the optimum reaction temperature and pH were 40 °C and 7.0, respectively. Furthermore, B. paramycoides nicotinate dehydrogenase exhibited good thermostability with more than 50% of the highest enzyme activity retained at 50 °C after 8 h incubation, which was better than ever reported. The pH stability results suggested that nicotinate dehydrogenase possessed a narrow pH ranging from 6.0 to 8.0. In addition, shaker speed demonstrated a positive relation with enzyme activity since shaker speed could affect mass transfer and dissolved oxygen concentration. Finally, it could completely transform nicotinic acid to 6-HNA within 3 h when the substrate loading is 15 g/L. In conclusion, these results indicated that B. paramycoides nicotinate dehydrogenase could serve as a potential candidate for bioproduction of 6-HNA.

The possibility of manufacturing a biocidal of Bacillus spp. and their growth on different fermented media

The study was conducted in the Molecular Biology Laboratory - Department of Plant Protection - Faculty of Agriculture - University of Kufa during 2020-2021 to evaluate the possibility of producing a biocide from Bacillus spp. B. firmus, B. cereus. and B. simplex. The results of manufacturing bionematicide from these bacteria showed that the three species did not differ in their growth on the same compost medium (palm fronds, rice residues, wheat residues), while the growth of each Bacillus spp. differed from other species on different culture media. The palm frond medium, regardless of the type of bacteria, was the least favorable and did not support many bacterial populations, and allowed no more than 83*108 CFU. Whereas the bacterial colonies ranged from 219*108 CFU to 254*108 CFU on fermented wheat residues, with a slight difference from rice residues, which led to bacterial colonies of 198*108 CFU to 214*108 CFU. In the case of carriers used for the biocide, preparation using sand was always better than with calcium sulfate. The effect of packing materials (plastic bags, paper bags, or plastic containers) on the efficiency and vitality of bacteria in the biocide content was also evaluated. It is noted that the highest bacterial colonies, which ranged from 267 to 253 *108 CFU, in the case of using plastic containers significantly differed from storing in paper bags (233-230*108 CFU) and plastic bags (235 -216 *108 CFU), after 15 days of storage in laboratory conditions. However, the viability and effectiveness of the prepared biocide decreased with the increase of storage periods to 30, 60, and 90 days, regardless of the type of bacteria.

Evaluation Nutrient of Larvae Black Soldier Fly (Hermetia Illucens) on Fermented Palm Oil Sludge Culture Media

Livestock business is affected by 50-70% of feed ingredients. Therefore it needs to find alternative feed ingredients either high nutrient or low cost. This study aims to examine the effect of palm oil sludge fermentation media with different types of fungi and dosage for maintan larvae black soldier fly. The method used in this study was an experimental method by Completely Randomized Factorial Design with 3 replications with 2 factors. Factor A is the type of fungi used with the three treatments and factor B is the dose used with the three treatments. Factor A was the type of fungi used: A1 (Pleurotus ostreatus), A2 (Lentinus edodes) and A3 (Phanerochaete chrysosporium). Factor B is the dose of fungi used: B1 (5%), B2 (7%) and B3 (9%). The variables observed consisted of protein content (%), fat content (%), crude fiber content (%). The mathematical model used is analysis of variance and if there are differences between treatments it is continued with the Duncan’s Multiple Range Test. The results showed that there were interactions with respect to the type of fungi used, crude protein, crude fat and crude fiber. The conclusion from this study is that palm oil sludge fermentation using the type of Lentinus edodes fungi at a dose of 7% can increase crude protein, reduce crude fiber and reduce crude fat of black soldier fly (BSF) larvae.

Optimization of Bioethanol Production from <em>Ceratophyllum demersum</em> for hand sanitizers

Hands are the primary way to spread microorganisms, thus hand washing is the primary defence and an essential element of personal hygiene for infection control. Hand sanitizers that contain ethanol as their main constituent are used to kill a broad range of microbes. Bioethanol production has relied heavily on the use of first-generation feedstock. Therefore, the development and utilization of alternative feedstocks such as weed (Ceratophyllum demersum) and other non-food crops have gained more attention in recent times. This study explores the bioethanol production using C. demersum, a weedy species, for its potential use in hand sanitizer production. The substrate, C. demersum was subjected to mechanical pre-treatment and then pre-treated with varying concentrations of sulfuric acid, which was subsequently followed by enzymatic pre-treatment and allowed for fermentation using Saccharomyces cerevisiae. The results showed that a sulfuric acid concentration of 1 M resulted in a significantly higher amount of reducing sugar and alcohol yield compared to other concentrations, and this was selected for further studies. After optimization of fermentation parameters, a significantly higher alcohol yield of 2.6% was achieved using a S. cerevisiae inoculum concentration of 100 g/l and agitation at 150 rpm at 40°C for 36 hours. Subsequent optimization of fermentation media components further increased the alcohol yield to 3.7%, with the use of 6 g/l yeast extract, 6 g/l (NH4)2SO4, 5 g/l MgSO4, and 8 g/l KH2PO4. The resulting alcohol mixture was analyzed and found to contain 84.9% bioethanol. An agar well diffusion assay was conducted against bacteria and fungi. The results showed that all the bacterial and fungal strains were sensitive to the bioethanol extract as evidenced by the presence of an inhibition zone.

Valorisation of chewing gum production waste in bioethanol production: a response surface methodology study

ABSTRACT Interest in fast-moving consumer goods (FMCG) is constantly growing all over the world. Chewing gum, which is in the group of pleasant and entertaining snacks preferred by people of all ages, especially children and young people, is one of the most consumed products in the food sector. Due to its remarkable production and the major components, chewing gum waste has the potential as an alternative sugar source for bioethanol production. To evaluate bioethanol production from chewing gum wastes, the sugar was first extracted, and directly fermented into ethanol under different conditions. Saccharomyces cerevisiae (fresh and dry) and Saccharomyces bayanus were used as the yeast. To determine the optimal fermentation medium, the response surface methodology (RSM) study was employed and the fermentation medium variables were tested such as agar, pepton and glucose (APG medium) concentrations. The APG medium in which the maximum bioethanol yield obtained was determined as 5 g/L agar, 10 g/L peptone and 5 g/L glucose. The highest ethanol yield under optimal APG medium was obtained as 9.1-4 g ethanol/L sugar after 72 h by using Saccharomyces cerevisiae (fresh). The obtained results showed that chewing gum wastes can be utilised a potential source for the bioethanol production.

Optimization of a Bacterial Cultivation Medium via a Design-of-Experiment Approach in a Sartorius Ambr® 15 Fermentation Microbioreactor System

In the evolving landscape of sustainable biopharmaceutical process development, the utilization of bacteria in the production of various compounds via fermentation has attracted extensive attention from scientists. A successful fermentation process and the release of its associated products hinge on the synergy between an efficient bacterial strain and the formulation of a suitable growth medium. Balancing all nutrient levels of a growth medium to maximize microbial growth and the product quality is quite an intricate task. In this context, significant advancements have been achieved via the strategic implementation of design-of-experiment (DOE) methodologies and the utilization of parallel microbioreactor systems. This work presents a case study of the fermentation growth medium optimization of a Gram-negative bacterium of the Neisseriaceae family that releases outer membrane vesicles (OMVs), which represent a potential vaccine platform. To achieve this, the ability of Sartorius MODDE®13 DOE software to explore multiple variables and their interactions was combined with the functionality of a Sartorius Ambr® 15F parallel microbioreactor system. The findings reported in this study have led to the design of a well-suited fermentation medium for a Gram-negative bacterium and an improvement in the quality of the OMVs produced from it.

Expression of β-xylosidase An-xyl from Aspergillus niger and characterization of its xylose tolerance

The hydrolysis of xylo-oligosaccharides catalyzed by β-xylosidase plays an important role in the degradation of lignocellulose. However, the enzyme is easily inhibited by its catalytic product xylose, which severely limits its application. Based on molecular docking, this paper studied the xylose affinity of Aspergillus niger β-xylosidase An-xyl, which was significantly differentially expressed in the fermentation medium of tea stalks, through cloning, expression and characterization. The synergistic degradation effect of this enzyme and cellulase on lignocellulose in tea stems was investigated. Molecular docking showed that the affinity of An-xyl to xylose was lower than that of Aspergillus oryzae β-xylosidase with poor xylose tolerance. The Ki value of xylose inhibition constant of recombinant-expressed An-xyl was 433.2 mmol/L, higher than that of most β-xylosidases of the GH3 family. The Km and Vmax towards pNPX were 3.6 mmol/L and 10 000 μmol/(min·mL), respectively. The optimum temperature of An-xyl was 65 ℃, the optimum pH was 4.0, 61% of the An-xyl activity could be retained upon treatment at 65 ℃ for 300 min, and 80% of the An-xyl activity could be retained upon treatment at pH 2.0-8.0 for 24 h. The hydrolysis of tea stem by An-xyl and cellulase produced 19.3% and 38.6% higher reducing sugar content at 2 h and 4 h, respectively, than that of using cellulase alone. This study showed that the An-xyl mined from differential expression exhibited high xylose tolerance and higher catalytic activity and stability, and could hydrolyze tea stem lignocellulose synergistically, which enriched the resource of β-xylosidase with high xylose tolerance, thus may facilitate the advanced experimental research and its application.

Improved production of Bacillus subtilis cholesterol oxidase by optimization of process parameters using response surface methodology

BackgroundCholesterol oxidase has numerous biomedical and industrial applications. In the current study, a new bacterial strain was isolated from sewage and was selected for its high potency for cholesterol degradation (%) and production of high cholesterol oxidase activity (U/OD600). ResultsBased on the sequence of 16S rRNA gene, the bacterium was identified as Bacillus subtilis. The fermentation conditions affecting cholesterol degradation (%) and the activity of cholesterol oxidase (U/OD600) of B. subtilis were optimized through fractional factorial design (FFD) and response surface methodology (RSM). According to this sequential optimization approach, 80.152% cholesterol degradation was achieved by setting the concentrations of cholesterol, inoculum size, and magnesium sulphate at 0.05 g/l, 6%, and 0.05 g/l, respectively. Moreover, 85.461 U of cholesterol oxidase/OD600 were attained by adjusting the fermentation conditions at initial pH, 6; volume of the fermentation medium, 15 ml/flask; and concentration of cholesterol, 0.05 g/l. The optimization process improved cholesterol degradation (%) and the activity of cholesterol oxidase (U/OD600) by 139% and 154%, respectively. No cholesterol was detected in the spectroscopic analysis of the optimized fermented medium via gas chromatography-mass spectroscopy (GC–MS). ConclusionThe current study provides principal information for the development of efficient production of cholesterol oxidase by B. subtilis that could be used in various applications.

Denovo production of resveratrol by engineered Saccharomyces cerevisiae W303-1a using pretreated Gracilaria corticata extracts.

Assembly and construction of resveratrol production pathway in Saccharomyces cerevisiae for denovo production of resveratrol using seaweed extract as fermentation medium. Genes involved in the production of resveratrol from tyrosine pathway, tyrosine ammonia lyase (FTAL) gene from Flavobacterium johnsoniae (FjTAL), the 4-coumarate:CoA ligase gene from Arabidopsis thaliana (4CL1) and the stilbene synthase gene from Vitis vinifera (VvSTS) were introduced into low copy, high copy and integrative vector and transformed into S. cerevisiae W303-1a. The resulting strains W303-1a/pARS-res5, W303-1a/2µ-res1 and W303-1a/IntUra-res9 produced a level of 2.39 ± 0.01, 3.33 ± 0.03 and 8.34 ± 0.03mg resveratrol l-1 respectively. CRISPR mediated integration at the δ locus resulted in 17.13 ± 1.1mg resveratrol l-1. Gracilaria corticata extract was tested as a substrate for the growth of transformant to produce resveratrol. The strain produced a comparable level, 13.6 ± 0.54mg resveratrol l-1 when grown in seaweed extract medium. The strain W303-1a/IntδC-res1 utilized Gracillaria hydrolysate and produced 13.6 ± 0.54mg resveratrol l-1 and further investigations are being carried out focusing on pathway engineering and optimization of process parameters to enhance resveratrol yield.

Statistical Experimental Design as a New Approach to Optimize a Solid-State Fermentation Substrate for the Production of Spores and Bioactive Compounds from Trichoderma asperellum.

Managing organic agricultural wastes is a challenge in today's modern agriculture, where the production of different agricultural goods leads to the generation of large amounts of waste, for example, olive pomace and vine shoot in Mediterranean Europe. The discovery of a cost-effective and environment-friendly way to valorize such types of waste in Mediterranean Europe is encouraged by the European Union regulation. As an opportunity, organic agricultural waste could be used as culture media for solid-state fermentation (SSF) for fungal strains. This methodology represents a great opportunity to produce secondary metabolites like 6-pentyl-alpha-pyrone (6-PP), a lactone compound with antifungal properties against phytopathogens, produced by Trichoderma spp. Therefore, to reach adequate yields of 6-PP, lytic enzymes, and spores, optimization using specific agricultural cheap local wastes from Southeastern France is in order. The present study was designed to show the applicability of an experimental admixture design to find the optimal formulation that favors the production of 6-PP. To conclude, the optimized formulation of 6-PP production by Trichoderma under SSF contains 18% wheat bran, 23% potato flakes, 20% olive pomace, 14% olive oil, 24% oatmeal, and 40% vine shoots.

Bioethanol Production from Non-Conventional Yeasts Wickerhamomyces anomalus (Pichia anomala) and Detection of ADH1 Gene

Bioethanol is an organic compound resulted from the fermentation of sugar substrates by microorganisms which is used as alternative energy sources. During bioethanol fermentation yeast are exposed to various fermentation stresses, including temperature, osmotic, and oxidative stresess. Such conditions may decrease ethanol production. We previously isolated fermentation-stress tolerance yeast isolates from traditional Balinese beverages, identified as Wickerhamomyces anomalus BT2, BT5, and BT6. However no data available regarding the bioethanol production of those isolates. Our study indicates that these strains could utilize various sugar substrates (glucose, xylose, maltose, sucrose) in oxidative fermentative media. The highest value of substrate utilization efficiency following 48 hours fermentation was shown by BT6 on glucose (61.02%), BT 2 on xylose (55.44%) and maltose (60.90%). Measurement of ethanol production by Gas Chromatography showed that the strains were able to produce higher ethanol on the glucose substrate than other substrates. For instance, BT6 could produce the highest ethanol production (5.00 g/L) amongst strains tested by using glucose as substrate. Yet, the particular strains could only produce 0.30 g/L and 0.65 g/L by using xylose and maltose, respectively. For further genetic engineering purposes, we detected ADH1 gene from all three isolates, with high homology to the alcohol dehydrogenase from Saccharomyces cerevisiae, Geobacillus stearothermophilus and Pseudomonas aeruginosa. Further strain development can be carried out targeting the ADH1 gene, important for ethanol fermentation.

Analysis of surfactant production by Bacillus cereus GX7 and optimization of fermentation conditions

Although biosurfactants have many advantages compared to chemical surfactants, biosurfactants are still limited by problems such as low yields and high production costs. In the present study, a strain of Bacillus Cereus (GX7) isolated from an oil tank bottom sludge of Shengli Oil Field (China) was selected as a highly effective surfactant producer. The biosurfactant produced by GX7 was extracted, purified, and analyzed by TLC, FT-IR, and LC-MS/MS. The results showed that the biosurfactant was surfactin of lipopeptide surfactant. Single-factor experiments were used to optimize the fermentation process of the strain from two aspects: the composition of the fermentation medium (carbon source, nitrogen source) and the fermentation conditions (temperature, pH, inoculation amount, rotation speed, and fermentation time). The surface tension and emulsification index of the fermentation broth were used to evaluate the optimal fermentation conditions. The results showed that the best carbon and nitrogen sources were glucose and peptone, and the optimum temperature, inoculum amount, pH, rotation speed, and fermentation time were 30 ℃, 1%, 7.5, 150 rpm, and 48 h, respectively. After optimization, the surface tension and emulsification index of fermentation broth were 26.84 mN/m and 57.84%, respectively. Moreover, the results also prove that the biosurfactant produced by this strain has good stability in a wide range of temperature, pH, and salt concentration.

Bioprocess development for fructooligosaccharides and carotenoids production using Agave mead

Fructooligosaccharides (FOS) and carotenoids are bioactive compounds of interest to the food industry due to the multiple benefits associated with their daily intake. One of the strategies that can be used to obtain said products of interest is successive fermentation, in which a compound of interest is produced in an initial fermentation, and the same resulting medium can be used to be fermented by another microorganism to generate another metabolite of interest. The successive fermentation strategy was used to produce FOS (first fermentation) and carotenoids (successive fermentation) using Agave mead as fermentation media. First, fermentation was evaluated for 120 h to determine the best fermentation time in terms of FOS productivity (g FOS/L*h) and carotenoids (mg/L*h). Once the best fermentation time was selected, the effect of different variables was evaluated. A Box Hunter & Hunter experimental design was used, considering five independent variables (pH, inoculum concentration, agitation, temperature, and light) at two levels (−1, +1) that influence total FOS (g/L) and total carotenoids (mg/L). Selected variables were later evaluated in a third-order experimental design (Box Behnken) to optimize total FOS (g/L) and total carotenoids (mg/L) in successive fermentation. As a result, it was possible to take advantage of the sugars present in the Agave mead to produce FOS and successively carotenoids in the same fermentation medium. In addition, through the experimental design, it was possible to obtain a concentration of 33.33 ± 1.39 g/L of total FOS and 5.11 ± 0.25 mg/L of total carotenoids in 48 h of fermentation.

Trifluoroethylacrylate-Substituted Polymethylsiloxane—Promising Membrane Material for Separating an Abe Fermentation Mixture

This work is aimed at obtaining a membrane material that is resistant to the formation of a precipitate on the surface upon contact with an ABE fermentation mixture and has a good separating ability during the pervaporation isolation of n-butanol from a water–alcohol mixture. In this regard, in this work, for the first time, the creation of pervaporation membranes based on polymethyltrifluoroethylacrylatesiloxane (F3-Acr), as well as a copolymer of polydecylmethylsiloxane and polymethyltrifluoroethylacrylatesiloxane (C10-F3-Acr) is proposed. In comparison with polydecylmethylsiloxane (C10), the structure and sorption properties of the developed membrane materials for n-butanol, ethanol and acetone were studied. It should be noted that the highest sorption of n-butanol is characteristic of C10-F3-Acr (0.46 g/g). Changes in surface properties were assessed by the contact angle and elemental composition of the surface before and after exposure for 1 month in a fermentation medium. The transport and separating properties of the synthesized membrane materials were studied in the vacuum pervaporation mode during the separation of a model ABE fermentation mixture. It was shown that the introduction of a fluorine-containing substituent into the side chain of polysiloxane made it possible to increase the hydrophilicity of the polymer: the water flow for F3-Acr was 0.7 × 10–6 kg m m–2 h–1, which is almost 3 times higher than for C10. It is worth noting the positive effect of the combination of C10 and F3-Acr groups in polysiloxane. Thus, with an increase in the total flow by 60% compared to the C10 membrane, the values of the separation factor for n-butanol, acetone, and ethanol were 40.5, 32.7, and 4.3 and increased by 6, 15, and 12%, respectively, compared to the C10 membrane. For the C10-F3-Acr membrane, the pervaporation separation index for n-butanol, acetone, and ethanol was 136, 109, and 11. Therefore, this membrane is twice as efficient as C10. Taking into account the absence of detectable contamination of the surface of the membrane material with fermentation products, one can note the high potential of the C10-F3-Acr membrane for the task of isolating alcohols from the ABE fermentation mixture.

High synthetic mechanisms and concentration improvement of menaquinone-7 from Bacillus subtilis subsp.natto

A strain MMH-56 of Bacillus subtilis subsp. natto with a high productivity of menaquinone-7 (MK-7) was obtained by physico-chemical mutagenesis. Transcriptomic analysis demonstrated that the efficient synthesis of MK-7 in strain MMH-56 was correlated to the enhanced central carbon metabolic and shikimate pathways, along with the activated fatty acid metabolic pathway in the MK-7 synthesis process. Especially, the expressions of menA, menB, menD, and menE in the shikimate pathway were upregulated; while, AroA, AroC, AroH, AroK, and TyrA were down-regulated, compared to the wild-type. Such ingenious regulations released the feedback-inhibition of MK-7 synthesis from aromatic amino acids, and promoted the biosynthesis of MK-7. Additionally, fermentation medium for MK-7 production were further optimized by response surface methodology. A final concentration of 161.74 mg/L MK-7 was acquired, which was 62.93-fold higher than the wild-type. Such productivity was sufficient for the industrial production of MK-7.

Valorization of spent Brewers yeast in the integrated production of the fungal exopolysaccharide (1 → 6)-β-D-glucan (lasiodiplodan) and single-cell protein

Spent Brewers yeast was studied as a low-cost alternative feedstock for sustainably producing a high value-added microbial β-D-glucan (lasiodiplodan). The potential of using the mycelial biomass (single-cell protein, SCP) generated in the production of β-glucan was also evaluated as a strategy of an integrated biorefining. Five cell lysis protocols were studied to obtain a yeast cell lysate rich in nutrients. Mineral supplementation of the fermentation medium was assessed, and the SCP produced was characterized by the nutritional composition, amino acid, and lipid profiles. Lasiodiplodia theobromae MMPI was effective in the co-production of lasiodiplodan ((1 → 6)-β-D-glucan)) and SCP in a cell lyzate-based medium. Enzymatic lysis with Alcalase promoted more significant cell rupture and release of soluble intracellular components. Highest production of lasiodiplodan (2.12 gL-1) and mycelial biomass (9.95 gL-1) resulted from Alcalase-treated cell lysate-based medium (7 gproteinL−1) supplemented with sucrose (60 gL-1). Under these conditions, volumetric productivities of lasiodiplodan and mycelial biomass: 0.029 gL−1h−1 and 0.138 gL−1h−1, respectively, were obtained. Mycelial biomass generated in this cultivation was rich in protein and contained all essential amino acids, especially high concentrations of leucine (69 mgg−1protein), lysine (62.2 mgg−1protein), valine (44.2 mgg−1protein), threonine (43.2 mgg−1protein). Co-production of lasiodiplodan and SCP could be an economically promising bioprospecting alternative.