• Genetic Manipulation of Microbial Strains for Enhanced Production of Hyaluronic Acid: Advances and Applications in Tissue Engineering
  • Rouzbeh Almasi Ghale,1 Marjan Talebi,2 Seyed Mahdi Mousavi Bafrouei,3 Fatemeh Tabandeh,4,*
    1. Department of Energy and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB).
    2. Student Research Committee, Department of Pharmacognosy, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
    3. Department of Energy and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB).
    4. Department of Energy and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB).


  • Introduction: Hyaluronic acid (HA), a non-branched glycosaminoglycan, is essential in maintaining tissue hydration, wound healing, and tissue engineering due to its exceptional hydrating properties and role in structural integrity. Traditionally sourced from animal tissues, HA production has faced issues such as high costs and contamination risks. Recent advances in microbial biotechnology offer a safer and more scalable alternative. By genetically engineering non-pathogenic bacteria, such as Bacillus subtilis, Escherichia coli, and Lactococcus lactis, the production of HA has been significantly enhanced. This review examines these advancements, with a focus on the incorporation of biosynthetic genes, such as hasA from Streptococcus species, which have enabled HA production in safe bacterial strains.
  • Methods: This review synthesizes recent advancements in microbial HA production by investigating peer-reviewed studies from databases including PubMed, Scopus, and Web of Science focusing on research from the past decade. The review includes trends in bacterial strains, genetic modifications, fermentation techniques, and optimization strategies.
  • Results: Recent advancements in microbial production of hyaluronic acid have significantly enhanced both yield and quality. The synthesis of HA involves the conversion of glucose-6-phosphate and fructose-6-phosphate into UDP-glucuronic acid and UDP-N-Acetyl glucosamine through enzymatic pathways respectively. Notably, the incorporation of the hasA gene, particularly when used alongside other related biosynthetic genes, has resulted in substantial improvements. This multi-gene approach in non-pathogenic strains enhances the biosynthetic process, improving HA production efficiency. In the field of genetic engineering, non-pathogenic strains such as Bacillus subtilis, Corynebacterium glutamicum, and Bacillus amyloliquefaciens have been engineered to enhance HA yields and address the limitations associated with traditional strains. These genetic modifications contribute to more efficient and reliable HA production. Various fermentation strategies, including batch, fed-batch, and continuous methods, have been explored to improve HA production. Continuous and fed-batch processes enhance metabolite production and reduce molecular weight polydispersity. Additionally, a dual-phase fermentation approach with conditions of 31°C at pH 8.0 and 37°C at pH 7.0 optimizes HA yield and molecular weight. HA's biocompatibility and its ubiquitous presence in vertebrate tissues render it an invaluable material in tissue engineering. In skin tissue engineering, HA-based scaffolds have been shown to improve the survival and maintenance of adipose tissue in skin substitutes. HA's capacity to provide a moist environment accelerates wound healing and offers protection against infections. Recent innovations, such as HA combined with solubilized amnion membrane, have further demonstrated enhanced wound closure and skin regeneration. For bone and cartilage tissue engineering, HA-modified hydrogels support cartilage regeneration and bone repair. These hydrogels maintain cell phenotype, promote vascularization, and facilitate the delivery of growth factors, showing promise in repairing bone and cartilage defects. Furthermore, innovations in scaffolds, including HA-based hydrogels such as methacrylated HA and composite materials, offer enhanced cell proliferation and tissue regeneration. The development of 3D-printed scaffolds and hydrogel systems aims to provide more effective and biocompatible solutions in tissue engineering. Looking ahead, several novel applications and future directions are emerging. In stem cell therapy, HA-containing scaffolds offer a supportive environment for stem cells to repair and regenerate tissues. Ongoing research is focused on optimizing scaffold design and material properties to improve clinical outcomes. Additionally, combining HA scaffolds with gene therapy and immunotherapy is expected to yield more effective treatments for complex diseases. The development of smart HA scaffolds, which respond to environmental stimuli and incorporate nanoscale features, holds promise for enhancing therapeutic efficacy. Recent innovations in hydrogel technology include the creation of injectable hydrogels that combine HA with gelatin and alginate. These hydrogels offer customizable swelling properties and cytocompatibility, making them advantageous for tissue engineering. The use of photoreactive methacrylates and cell-laden microgels further extends HA’s applications, enabling the creation of functional microstructures for regenerative medicine.
  • Conclusion: This review underscores the revolutionary potential of genetically engineered bacterial systems for HA production. Advances in fermentation techniques, genetic engineering, and scaffold design have notably improved HA yield and application in tissue engineering. The integration of HA with other therapeutic approaches and innovations in hydrogel technology highlight its versatility and promise. Future research should continue to explore and refine these advancements, focusing on optimizing scaffold designs, enhancing therapeutic efficacy, and expanding applications in regenerative medicine and drug delivery systems.
  • Keywords: Hyaluronic Acid, Genetic Engineering, Non-Pathogenic Bacteria, hasA Gene, Tissue Engineering