Microbial production of low molecular weight hyaluronic acid by adding hydrogen peroxide and ascorbate in batch culture of Streptococcus zooepidemicus

Chitosan- and hyaluronic acid-based nanoarchitectures in phototherapy: Combination cancer chemotherapy, immunotherapy and gene therapy

Cancer phototherapy has been introduced as a new potential modality for tumor suppression. However, the efficacy of phototherapy has been limited due to a lack of targeted delivery of photosensitizers. Therefore, the application of biocompatible and multifunctional nanoparticles in phototherapy is appreciated. Chitosan (CS) as a cationic polymer and hyaluronic acid (HA) as a CD44-targeting agent are two widely utilized polymers in nanoparticle synthesis and functionalization. The current review focuses on the application of HA and CS nanostructures in cancer phototherapy. These nanocarriers can be used in phototherapy to induce hyperthermia and singlet oxygen generation for tumor ablation. CS and HA can be used for the synthesis of nanostructures, or they can functionalize other kinds of nanostructures used for phototherapy, such as gold nanorods. The HA and CS nanostructures can combine chemotherapy or immunotherapy with phototherapy to augment tumor suppression. Moreover, the CS nanostructures can be functionalized with HA for specific cancer phototherapy. The CS and HA nanostructures promote the cellular uptake of genes and photosensitizers to facilitate gene therapy and phototherapy. Such nanostructures specifically stimulate phototherapy at the tumor site, with particle toxic impacts on normal cells. Moreover, CS and HA nanostructures demonstrate high biocompatibility for further clinical applications.

Advances in hyaluronic acid production: Biosynthesis and genetic engineering strategies based on Streptococcus - A review

Hyaluronic acid (HA), which is a highly versatile glycosaminoglycan, is widely applied across the fields of food, cosmetics, and pharmaceuticals. It is primary produced through Streptococcus fermentation, but the product presents inherent challenges concerning consistency and potential pathogenicity. However, recent strides in molecular biology have paved the way for genetic engineering, which facilitates the creation of high-yield, nonpathogenic strains adept at synthesizing HA with specific molecular weights. This comprehensive review extensively explores the molecular biology underpinning pivotal HA synthase genes, which elucidates the intricate mechanisms governing HA synthesis. Moreover, it delineates various strategies employed in engineering HA-producing strains.

Comparative whole genome analysis of face-derived Streptococcus infantis CX-4 unravels the functions related to skin barrier

BACKGROUND

The skin microbiome is essential in guarding against harmful pathogens and responding to environmental changes by generating substances useful in the cosmetic and pharmaceutical industries. Among these microorganisms, Streptococcus is a bacterial species identified in various isolation sources. In 2021, a strain of Streptococcus infantis, CX-4, was identified from facial skin and found to be linked to skin structure and elasticity. As the skin-derived strain differs from other S. infantis strains, which are usually of oral origin, it emphasizes the significance of bacterial variation by the environment.

OBJECTIVE

This study aims to explore the unique characteristics of the CX-4 compared to seven oral-derived Streptococcus strains based on the Whole-Genome Sequencing data, focusing on its potential role in skin health and its possible application in cosmetic strategies.

METHODS

The genome of the CX-4 strain was constructed using PacBio Sequencing, with the assembly performed using the SMRT protocol. Comparative whole-genome analysis was then performed with seven closely related strains, utilizing web-based tools like PATRIC, OrthoVenn3, and EggNOG-mapper, for various analyses, including protein association analysis using STRING.

RESULTS

Our analysis unveiled a substantial number of Clusters of Orthologous Groups in diverse functional categories in CX-4, among which sphingosine kinase (SphK) emerged as a unique product, exclusively present in the CX-4 strain. SphK is a critical enzyme in the sphingolipid metabolic pathway, generating sphingosine-1-phosphate. The study also brought potential associations with isoprene formation and retinoic acid synthesis, the latter being a metabolite of vitamin A, renowned for its crucial function in promoting skin cell growth, differentiation, and maintaining of skin barrier integrity. These findings collectively suggest the potential of the CX-4 strain in enhancing of skin barrier functionality.

CONCLUSION

Our research underscores the potential of the skin-derived S. infantis CX-4 strain by revealing unique bacterial compounds and their potential roles on human skin.

Hyaluronic acid production by Klebsiella pneumoniae strain H15 (OP354286) under different fermentation conditions

BACKGROUND

Hyaluronic acid (HA) has gained significant attention due to its unique physical, chemical, and biological properties, making it widely used in various industries. This study aimed to screen bacterial isolates for HA production, characterize favorable fermentation conditions, and evaluate the inhibitory effect of bacterial HA on cancer cell lines.

RESULTS

A total of 108 bacterial isolates from diverse sources were screened for HA production using HPLC, turbidimetric, and carbazole determination methods. Among the HA-producing isolates, Klebsiella pneumoniae H15 isolated from an animal feces sample, was superior in HA production. The strain was characterized based on its morphological, cultural, and biochemical characteristics. Molecular identification using 16S rDNA sequencing and phylogenetic analysis confirmed its identity. Fermentation conditions, including pH, temperature, time, and agitation rate, were optimized to maximize HA production. The basal medium, comprising sucrose (7.0%) as carbon source and combined yeast extract with peptone (1.25% each) as nitrogen substrate, favored the highest HA production at pH 8.0, for 30 h, at 30 °C, under shaking at 180 rpm. The average maximized HA concentration reached 1.5 g L-1. Furthermore, bacterial HA exhibited a significant inhibitory effect on three cancer cell lines (MCF-7, HepG-2 and HCT), with the lowest concentration ranging from 0.98-3.91 µg mL-1.

CONCLUSIONS

K. pneumoniae H15, isolated from animal feces demonstrated promising potential for HA production. The most favorable fermentation conditions led to a high HA production. The inhibitory effect of bacterial HA on cancer cell lines highlights its potential therapeutic applications. These findings contribute to a broader understanding and utilization of HA in various industries and therapeutic applications.

Efficient production of hyaluronic acid by Streptococcus zooepidemicus using two-stage semi-continuous fermentation

Hyaluronic acid is a kind of mucopolysaccharide that has wide applications in cosmetics, health food, and orthopedics. Using Streptococcus zooepidemicus ATCC 39920 as parent, a beneficial mutant SZ07 was obtained by UV mutagenesis, giving 1.42 g/L hyaluronic acid in shake flasks. To enhance the efficiency of hyaluronic acid production, a semi-continuous fermentation process consisted of two-stage 3-L bioreactors was developed, in which 1.01 g/L/h productivity and 14.60 g/L hyaluronic acid were obtained. To further enhance the titer of hyaluronic acid, recombinant hyaluronidase SzHYal was added into 2^nd stage bioreactor at 6 h to reduce the viscosity of broth. The highest hyaluronic acid titer of 29.38 g/L was achieved with a productivity of 1.13 g/L/h at 300 U/L SzHYal after 24 h. This newly developed semi-continuous fermentation process provides a promising strategy for the industrial production of hyaluronic acid and related polysaccharides.

Microbial synthesis of glycosaminoglycans and their oligosaccharides

Compared with chemical synthesis and tissue extraction methods, microbial synthesis of glycosaminoglycans (GAGs) is attractive because of the advantages of eco-friendly processes, production safety, and sustainable development. However, boosting the efficiency of microbial cell factories, precisely regulating GAG molecular weights, and rationally controlling the sulfation degree of GAGs remain challenging. To address these issues, various strategies, including genetic, enzymatic, metabolic, and fermentation engineering, have been developed. In this review, we summarize the recent progress in the construction of efficient GAG-producing microbial cell factories, regulation of the molecular weight of GAGs, and modification of GAG chains. Moreover, future studies, remaining challenges, and potential solutions in this field are discussed.

Hyaluronic acid production and purification techniques: a review

Hyaluronic acid (HA) is an exopolysaccharide extracted from several sources such as rooster combs, umbilical cords and microorganisms. A system that controls temperature, agitation and aeration of bacterial cultures could make the HA production autonomous. Therefore, HA of microbial origin is set to take over alternative methods of production. Furthermore, the use of different nutrient sources in the culture medium and the purification stage applied in the process can cause physicochemical alterations on the bioproduct. For instance, structural modifications that change the molecular weight of HA may alter its elastic and viscoelastic properties. As a result, HA synthesized by microbes has applications in pharmacology, biotechnology, and tissue engineering. Our aim here, is to show the vast range of applications by compiling articles and patents on the culture media or genetic modifications of microorganisms that synthesize HA.

The dilution effect of media culture on mixing time, Kla O2, and hyaluronic acid production in S. zooepidemicus fed-batch culture

OBJECTIVES

Microbial production of biopolymers is typically associated with high viscosity and suitable mixing plays an important role in their production. Due to the nature of Streptococcus strains in high production of lactic acid and consequently high consumption of NaOH, which is associated with increased viscosity and reduced mixing caused by hyaluronic acid production, the injected NaOH accumulates and causes cells loss, and decreases in quantity and quality of the produced hyaluronic acid.

RESULTS

In this study, the effect of increasing dilution of media culture of Streptococcus zooepidemicus fed-batch culture during pH control by NaOH on mixing time, volumetric oxygen transfer coefficient, and increasing hyaluronic acid production in a 2-L fermenter were studied. The results showed that significant increasing dilution causes reduction mixing time, remarkable improvement volumetric oxygen transfer coefficient, hyaluronic acid production enhancement from 6.6 to 8.4 g/L, and diminution the consumption of NaOH.

CONCLUSION

Dilution of media culture of S. zooepidemicus fed-batch culture by the pH controlling agent achieved one of the highest amounts of hyaluronic acid that was reported recently. This method does not require any automatic control and can be used at a low cost to produce other soluble extracellular biopolymers.

Sucrose-modified iron nanoparticles for highly efficient microbial production of hyaluronic acid by Streptococcus zooepidemicus

Nanoparticles (NPs) were hypothesized to enhance fermentation processes and assist microorganisms in producing valuable biopolymers. Donors of trace iron, i.e., FeSO₄·7H₂O, zero-valence iron nanoparticles (Fe NPs), and ferric oxide nanoparticles (α-Fe₂O₃ NPs), were tested to study the impact on hyaluronic acid (HA) production. The bioprocess with the addition of 30 mg/L Fe NPs produced higher HA than the other groups. However, Fe NPs were limited by the synergistic effect of geomagnetism and high surface energy, resulting in obvious agglomeration behavior. To address this, we developed novel sucrose-modified iron nanoparticles (SM-Fe NPs), which showed effective improvement of dispersion and agglomeration. Concerning the SM-Fe NP additives, an adequate supply of nutrients and trace elements provided sufficient substrates and energy for the reproduction of Streptococcus zooepidemicus. Furthermore, the highest HA production with the addition of 30 mg/L SM-Fe NPs was 0.226 g/L, and the dry weight of the produced HA increased 3.28 times compared with the control group (0.069 g/L). This work significantly improved HA production and presented promising opportunities for industrial production.

Nanomaterials Versus The Microbial Compounds With Wound Healing Property

Age and diabetes related slow-healing or chronic wounds may result in morbidity and mortality through persistent biofilms infections and prolonged inflammatory phase. Nano-materials [metal/metal oxide NPs (39%), lipid vehicles (21%), polymer NPs (19%), ceramic nanoparticles (NPs) (14%), and carbon nanomaterials (NMs) (7%)] can be introduced as a possible next-generation therapy because of either their intrinsic wound healing activity or via carrying bioactive compounds including, antibiotics, antioxidants, growth factor or stem cell. The nanomaterials have been shown to implicate in all four stages of wound healing including hemostasis (polymer NPs, ceramic NPs, nanoceria-6.1%), inflammation (liposome/vesicles/solid lipid NPs/polymer NPs/ceramic NPs/silver NPs/gold NPs/nanoceria/fullerenes/carbon-based NPs-32.7%), proliferation (vesicles/liposome/solid lipid NPs/gold NPs/silver NPs/iron oxide NPs/ceramic NPs/copper NPs/self-assembling elastin-like NPs/nanoceria/micelle/dendrimers/polymer NPs-57.1%), remodeling (iron oxide NPs/nanoceria-4.1%). Natural compounds from alkaloids, flavonoids, retinoids, volatile oil, terpenes, carotenoids, or polyphenolic compounds with proven antioxidant, anti-inflammatory, immunomodulatory, or antimicrobial characteristics are also well known for their potential to accelerate the wound healing process. In the current paper, we survey the potential and properties of nanomaterials and microbial compounds in improving the process of wound and scar healing. Finally, we review the potential biocompounds for incorporation to nano-material in perspective to designate more effective or multivalent wound healing natural or nano-based drugs.

Stability Evaluation and Degradation Studies of DAC® Hyaluronic-Polylactide Based Hydrogel by DOSY NMR Spectroscopy

The stability and the degradation of polymers in physiological conditions are very important issues in biomedical applications. The copolymer of hyaluronic acid and poly-D,L-lactic acid (made available in a product called DAC®) produces a hydrogel which retains the hydrophobic character of the poly-D,L-lactide sidechains and the hydrophilic character of a hyaluronic acid backbone. This hydrogel is a suitable device for the coating of orthopedic implants with structured surfaces. In fact, this gel creates a temporary barrier to bacterial adhesion by inhibiting colonization, thus preventing the formation of the biofilm and the onset of an infection. Reabsorbed in about 72 h after the implant, this hydrogel does not hinder bone growth processes. In the need to assess stability and degradation of both the hyaluronan backbone and of the polylactic chains along time and temperature, we identified NMR spectroscopy as a privileged technique for the characterization of the released species, and we applied diffusion-ordered NMR spectroscopy (DOSY-NMR) for the investigation of molecular weight dispersion. Our diffusion studies of DAC® in physiological conditions provided a full understanding of the product degradation by overcoming the limitations observed in applying classical chromatography approaches by gel permeation UV.

Deciphering the role of dissolved oxygen and N-acetyl glucosamine in governing higher molecular weight hyaluronic acid synthesis in Streptococcus zooepidemicus cell factory

The present study is focused on systematic process and kinetic investigation of hyaluronic acid (HA) production strategy unraveling the role of dissolved oxygen (DO) and N-acetyl glucosamine (GlcNAc) towards the enhancement of HA titer and its molecular weight. Maintaining excess DO levels (10-40% DO) through DO-stat control and the substitution of GlcNAc at a range (5-20 g/L) with glucose (Glc) critically influenced HA production. DO-stat control strategy yielded a promising HA titer (2.4 g/L) at 40% DO concentration. Controlling DO level at 20% (DO-stat) was observed to be optimum resulting in a significant HA production (2.1 g/L) and its molecular weight ranging 0.98-1.45 MDa with a consistent polydispersity index (PDI) (1.57-1.69). Substitution of GlcNAc with Glc at different proportions explicitly addressed the metabolic trade-off between HA titer and its molecular weight. GlcNAc substitution positively influenced the molecular weight of HA. The highest HA molecular weight (2.53 MDa) of two-fold increase compared with glucose as sole carbon substrate and narrower PDI (1.35 ± 0.18) was achieved for the 10:20 (Glc:GlcNAc) proportion. A novice attempt on modeling the uptake of dual substrates (Glc and GlcNAc) by Streptococcus zooepidemicus for HA production was successfully accomplished using double Andrew's growth model and the kinetic parameters were estimated reliably.

Extracellular Matrix-Based Strategies for Immunomodulatory Biomaterials Engineering

The extracellular matrix (ECM) is a complex and dynamic structural scaffold for cells within tissues and plays an important role in regulating cell function. Recently it has become appreciated that the ECM contains bioactive motifs that can directly modulate immune responses. This review describes strategies for engineering immunomodulatory biomaterials that utilize natural ECM-derived molecules and have the potential to harness the immune system for applications ranging from tissue regeneration to drug delivery. A top-down approach utilizes full-length ECM proteins, including collagen, fibrin, or hyaluronic acid-based materials, as well as matrices derived from decellularized tissue. These materials have the benefit of maintaining natural conformation and structure but are often heterogeneous and encumber precise control. By contrast, a bottom-up approach leverages immunomodulatory domains, such as Arg-Gly-Asp (RGD), matrix metalloproteinase (MMP)-sensitive peptides, or leukocyte-associated immunoglobulin-like receptor-1(LAIR-1) ligands, by incorporating them into synthetic materials. These materials have tunable control over immune cell functions and allow for combinatorial approaches. However, the synthetic approach lacks the full natural context of the original ECM protein. These two approaches provide a broad range of engineering techniques for immunomodulation through material interactions and hold the potential for the development of future therapeutic applications.

Optimization of hyaluronic acid production and its cytotoxicity and degradability characteristics

In the present study, culture conditions of Streptococcus equi was optimized through Box-Behnken experimental design for hyaluronic acid production. About 0.87 gL^-1 of hyaluronic acid was produced under the determined conditions and optimal conditions were found as 38.42 °C, 24 hr and 250 rpm. The validity and practicability of this statistical optimization strategy were confirmed relation between predicted and experimental values. The hyaluronic acid obtained under optimal conditions was characterized. The effects of different conditions such as ultraviolet light, temperature and enzymatic degradation on hyaluronic acid produced under optimal conditions were determined. 118 °C for 32 min of autoclaved HA sample included 63.09 µg mL^-1 of d-glucuronic acid, which is about two-fold of enzymatic effect. Cytotoxicity of hyaluronic acid on human dermal cells (HUVEC, HaCaT), L929 and THP-1 cells was studied. In vitro effect on pro or anti-inflammatory cytokine release of THP-1 cells was determined. Although it varies depending on the concentration, cytotoxicity of hyaluronic acid is between 5 and 30%. However, it varies depending on the concentration of hyaluronic acid, TNF-α release was not much increased compared to control study. Consequently, purification procedure is necessary to develop and it is worth developing the bacterial hyaluronic acid.

H2O2-Depleting and O2-Generating Selenium Nanoparticles for Fluorescence Imaging and Photodynamic Treatment of Proinflammatory-Activated Macrophages

Macrophages have a pivotal role in chronic inflammatory diseases (CIDs), so imaging and controlling activated macrophage is critical for detecting and reducing chronic inflammation. In this study, photodynamic selenium nanoparticles (SeNPs) with photosensitive and macrophage-targeting bilayers were developed. The first layer of the photosensitive macromolecule was composed of a conjugate of a photosensitizer (rose bengal, RB) and a thiolated chitosan (chitosan-glutathione), resulting in a plasmonic coupling-induced red shift and broadening of RB absorption bands with increased absorption intensity. Electron paramagnetic resonance (EPR) and diphenylanthracene (DPA) quenching studies revealed that the SeNPs that were coated with the photosensitive layer were more effective than RB alone in producing singlet oxygen (¹O₂) under photoirradiation. The second layer of the activated macrophage-targetable macromolecule was synthesized by conjugation of hyaluronic acid with folic acid using an ethylenediamine linker. Proinflammatory-activated macrophages rapidly internalized the SeNPs that were covered with the targeting ligand, exhibiting a much stronger fluorescence signal of the SeNPs than did the nonactivated macrophages. Since proinflammatory-activated macrophage was known to generate a substantial amount of H₂O₂ while the inflamed site generally caused inflammation-associated tissue hypoxia, the SeNPs were further modified with O₂ self-sufficient function for photodynamic therapy. Catalase was immobilized on the SeNPs by the formation of disulfide bonds. Intracellular reduction of disulfide bonds induced the subsequent release of catalase, which catalyzed the decomposition of H₂O₂. The H₂O₂-depleting and O₂-generating photodynamic SeNPs efficiently killed activated macrophages and quenched the intracellular H₂O₂ and NO that are associated with inflammation. The SeNPs may have potential as a theranostic nanomaterial to image and control the activation of macrophages.

Green synthesis, characterization, and anticancer activity of hyaluronan/zinc oxide nanocomposite

The study describes an in situ green biosynthesis of zinc oxide nanocomposite using the seaweed Sargassum muticum water extract and hyaluronan biopolymer. The morphology and optical properties of the hyaluronan/zinc oxide (HA/ZnO) nanocomposite were determined by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and ultraviolet-vis analysis. Electron microscopy and X-ray diffraction analysis showed that the zinc oxide nanoparticles were polydispersed with a mean size of 10.2±1.5 nm. The nanoparticles were mostly hexagonal in crystalline form. The HA/ZnO nanocomposite showed the absorption properties in the ultraviolet zone that is ascribed to the band gap of zinc oxide nanocomposite. In the cytotoxicity study, cancer cells, pancreatic adenocarcinoma (PANC-1), ovarian adenocarcinoma (CaOV-3), colonic adenocarcinoma (COLO205), and acute promyelocytic leukemia (HL-60) cells were treated with HA/ZnO nanocomposite. At 72 hours of treatment, the half maximal inhibitory concentration (IC50) value via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was 10.8±0.3 μg/mL, 15.4±1.2 μg/mL, 12.1±0.9 μg/mL, and 6.25±0.5 μg/mL for the PANC-1, CaOV-3, COLO-205, and HL-60 cells, respectively, showing that the composite is most toxic to the HL-60 cells. On the other hand, HA/ZnO nanocomposite treatment for 72 hours did not cause toxicity to the normal human lung fibroblast (MRC-5) cell line. Using fluorescent dyes and flow cytometry analysis, HA/ZnO nanocomposite caused G2/M cell cycle arrest and stimulated apoptosis-related increase in caspase-3 and -7 activities of the HL-60 cells. Thus, the study shows that the HA/ZnO nanocomposite produced through green synthesis has great potential to be developed into an efficacious therapeutic agent for cancers.

Hyaluronic acid for anticancer drug and nucleic acid delivery

Hyaluronic acid (HA) is widely used in anticancer drug delivery, since it is biocompatible, biodegradable, non-toxic, and non-immunogenic; moreover, HA receptors are overexpressed on many tumor cells. Exploiting this ligand-receptor interaction, the use of HA is now a rapidly-growing platform for targeting CD44-overexpressing cells, to improve anticancer therapies. The rationale underlying approaches, chemical strategies, and recent advances in the use of HA to design drug carriers for delivering anticancer agents, are reviewed. Comprehensive descriptions are given of HA-based drug conjugates, particulate carriers (micelles, liposomes, nanoparticles, microparticles), inorganic nanostructures, and hydrogels, with particular emphasis on reports of preclinical/clinical results.

Glycosaminoglycan degradation by selected reactive oxygen species

SIGNIFICANCE

Inflammatory diseases (such as arthritis) of the extracellular matrix (ECM) are of considerable socioeconomic significance. There is clear evidence that reactive oxygen species (ROS) and nitrogen species released by, for instance, neutrophils contribute to the degradation of the ECM. Here we will focus on the ROS-induced degradation of the glycosaminoglycans, one important component of the ECM.

RECENT ADVANCES

The recently developed "anti-TNF-α" therapy is primarily directed against neutrophilic granulocytes that are powerful sources of ROS. Therefore, a more detailed look into the mechanisms of the reactions of these ROS is reasonable.

CRITICAL ISSUES

Since both enzymes and ROS contribute to the pathogenesis of inflammatory diseases, it is very difficult to estimate the contributions of the individual species in a complex biological environment. This particularly applies as many products are not stable but only transient products that decompose in a time-dependent manner. Thus, the development of suitable analytical methods as well as the establishment of useful biomarkers is a challenging aspect.

FUTURE DIRECTIONS

If the mechanisms of ECM destruction are understood in more detail, then the development of suitable drugs to treat inflammatory diseases will be hopefully much more successful.

Determination of the presence of hyaluronic acid in preparations containing amino acids: the molecular weight characterization

Several pharmaceutical preparations contain hyaluronic acid in the presence of a large variety of low molecular weight charged molecules like amino acids. In these mixtures, it is particularly difficult to determine the concentration and the molecular weight of the hyaluronic acid fragments. In fact zwitterionic compounds in high concentration behave by masking the hyaluronic acid due to the electrostatic interactions between amino acids and hyaluronic acid. In such conditions the common colorimetric test of the hyaluronic acid determination appears ineffective and in the (1)H NMR spectra the peaks of the polymer disappear completely. By a simple separation procedure the presence of hyaluronic acid was revealed by the DMAB test and (1)H NMR while its average molecular weight in the final product was determined by DOSY NMR spectroscopy alone. The latter determination is very important due to the healthy effects of some sizes of this polymer's fragments.

Metabolic engineering of Pichia pastoris for production of hyaluronic acid with high molecular weight

The high molecular weight (>1 MDa) of hyaluronic acid (HA) is important for its biological functions. The reported limiting factors for the production of HA with high molecular weight (MW) by microbial fermentation are the insufficient HA precursor pool and cell growth inhibition. To overcome these issues, the Xenopus laevis xhasA2 and xhasB genes encoding hyaluronan synthase 2 (xhasA2) and UDP-glucose dehydrogenase (xhasB), were expressed in Pichia pastoris widely used for production of heterologous proteins. In this study, expression vectors containing various combination cassettes of HA pathway genes including xhasA2 and xhasB from X. laevis as well as UDP-glucose pyrophosphorylase (hasC), UDP-N-acetylglucosamine pyrophosphorylase (hasD) and phosphoglucose isomerase (hasE) from P. pastoris were constructed and tested. First, HA pathway genes were overexpressed using pAO815 and pGAPZB vectors, resulting in the production of 1.2 MDa HA polymers. Second, in order to decrease hyaluronan synthase expression a strong AOX1 promoter in the xhasA2 gene was replaced by a weak AOX2 promoter which increased the mean MW of HA to 2.1 MDa. Finally, the MW of HA polymer was further increased to 2.5 MDa by low-temperature cultivation (26 °C) which reduced cell growth inhibition. The yield of HA production by the P. pastoris recombinant strains in 1L of fermentation culture was 0.8-1.7 g/L.

Cashew apple juice as microbial cultivation medium for non-immunogenic hyaluronic acid production

In this work, natural cashew apple juice was used as cultivation medium as an alternative to substitute brain heart infusion medium. The effect of aeration and juice supplementation with yeast extract on the production of hyaluronic acid in batch fermentation was also investigated. Similar levels of cell mass were obtained in inoculum using cashew apple juice supplemented with yeast extract or the conventional brain heart infusion medium. Fermentation in Erlenmeyer flasks produced low biomass and hyaluronic acid concentrations. The hyaluronic acid concentration and viscosity increased from 0.15 g/L and 3.87 cP (no aeration or medium supplementation) to 1.76 g/L and 107 cP, when aeration (2 vvm) and 60 g/L of yeast extract were used. The results suggest the production of low-molecular weight hyaluronic acid oligomers instead of the high molecular weight polymer.

The solid-state cultivation of Streptococcus zooepidemicus in polyurethane foam as a strategy for the production of hyaluronic acid

Hyaluronic acid (HA) is a biopolymer with important applications in the pharmaceutical, medical, and cosmetic fields. This work explores the potentialities of a cylindrical polyurethane foam dowel with central aeration as a novel packed bed bioreactor for the production of HA. The goals were to provide a large surface area for oxygen transfer through the patches of liquid film that form in the pores of the foam in which cell proliferation and HA production occur and to easily recover the HA produced. The resulting yields of HA/cell were higher than 1, and the produced HA was completely recovered by pressing the foam. The external conditions that inhibit catabolism, the deviation of energetic metabolism toward the production of HA, were modulated by aeration and the initial glucose concentration. The production of HA was reproducible in 12 successive fermentation cycles. These findings contribute to the development of efficient strategies for the controlled production and recovery of HA.

Bioactives from probiotics for dermal health: functions and benefits

Probiotics have been extensively reviewed for decades, emphasizing on improving general gut health. Recently, more studies showed that probiotics may exert other health-promoting effects beyond gut well-being, attributed to the rise of the gut-brain axis correlations. Some of these new benefits include skin health such as improving atopic eczema, atopic dermatitis, healing of burn and scars, skin-rejuvenating properties and improving skin innate immunity. Increasing evidence has also showed that bacterial compounds such as cell wall fragments, their metabolites and dead bacteria can elicit certain immune responses on the skin and improve skin barrier functions. This review aimed to underline the mechanisms or the exact compounds underlying the benefits of bacterial extract on the skin based on evidences from in vivo and in vitro studies. This review could be of help in screening of probiotic strains with potential dermal enhancing properties for topical applications.

Microbial production of hyaluronic acid from agricultural resource derivatives

Agricultural resource derivatives (ARDs) such as hydrolysate soy protein concentrate (HSPC), whey protein concentrate (WPC), and cashew apple juice (CAJ) were studied with focus on the production of hyaluronic acid (HA) by Streptococcus zooepidemicus. Supplementation of the media with corn steep liquor (CSL) was also evaluated. Synthetic medium containing glucose and yeast extract was used as control. CAJ was a promising medium for the production of HA. It produced the highest amount of HA (0.89 g L(-1)), similar to that of the control (0.86 g L(-1)). WPC and HSPC media were the most effective for the production of biomass. CSL did not influence the production of HA when HSPC and WPC were used. However, in the synthetic medium it doubled the yield of HA from glucose. The average molecular weight of HA ranged from 10(3) to 10(4)Da for the ARDs and 10(7)Da for the synthetic medium.