Laurinda Steyn

Laurinda Steyn

Lecturer / Researcher

steynl@ufs.ac.za
+27 51 401 7468

Bioreactors are used to carry out one or more biochemical reaction to convert raw materials to products through the action of a biocatalyst, enzyme, microorganisms, or the cells of animals or plants.

If you are planning to cultivate microorganisms, this might be a great place to start.

Several services related to microbial cultivation are offered.

  • Experimental Planning and Design
  • Medium formulation
  • Growth kinetics
  • Bioprocess Engineering
  • Bioreactor Operational Training
  • Bioreactor Maintenance and Support
  • Bioreactor operation

    A bioreactor is a vessel in which organisms are cultivated to form desired products

    • Biomass
    • Metabolic products (e.g. acids, alcohols, enzymes etc.)

    It is designed to give the right environment for optimal growth and metabolic activity of organism

    • Temperature
    • pH
    • Nutritional requirements
    • Aerobic, microaerophilic or anaerobic

    There are several bioreactors available in the Department that can be used for:

    • Process development
    • Vaccine, recombinant protein and monoclonal antibody production
    • Production of biofuels and secondary metabolites
    • Process strategy development in batch, fed-batch, continuous or perfusion operation
    • Scale-up and scale-down experiments
    • High cell density fermentation
    • Suspension cultures and adherent cell culture with micro carriers
    • Cultivation of filamentous organisms
    They range in volumes (300 mL to 15 L) and mode of operation

    Batch Cultivation

    Closed system. Growth is allowed to proceed at a suitable temperature and gaseous environment for a suitable period of time. In the course of the entire fermentation nothing is added, except oxygen (in case of aerobic microorganisms), an antifoam agent, acid or base to control pH. The composition of the medium, the biomass concentration and the metabolite concentration generally change constantly as a result of metabolism of the cells.

    Applications
    • Products that must be produced with minimal risk of contamination or organism mutation
    • Operations in which only small amounts of product are produced
    • Processes using one reactor to make various products
    • Processes in which batch or semi-continuous product separation is adequate

     Batch cultivation 1Batch cultivation 2

    Continuous cultivation

    In continuous fermentation an open system is set up. Sterile nutrient solution is added to the bioreactor continuously and an equivalent amount of converted nutrient solution with microorganisms is simultaneously taken out of the system.

    Applications
    • Continuous reactions offer increased opportunities for system investigation and analysis. As the variables remain unchanged, a benchmark can be determined for the process results, and then the effects of even minor changes to physical or chemical variables can be evaluated.

    Continuous cultivation 1Continuous cultivation 2

    Fed-batch Cultivation

    The fed batch method is characterized by the addition of small concentrations at the beginning of the fermentation and these substances continue to be added in small doses during the fermentation process. Despite the apparent similarity between the fed batch reactor model and the continuous culture model, they are very different. Whereas the continuous culture for biomass accumulation is composed of a growth and removal process, the fed batch procedure is composed of a growth and dilution process.

    Applications
    • Can be operated in a variety of ways, e.g., the reactor can be operated in the following sequence: Batch » Fed batch » Batch
    • The feed can also be manipulated to maximize product formation
    • Maintenance of low nutrient and substrate concentrations, thus well suited for producing product or cells when the substrate is inhibitory by allowing the maintenance of low levels of substrate so that cells are not inhibited
    • Useful when the product or biomass yield is highest at low substrate concentrations as in the case of mammalian cell systems for recombinant protein, baker’s yeast products and antibiotic production
    • Another suitable application is when the product formation is dependent on a specific nutrient composition, e.g., specific carbon to nitrogen ratio

    Fed-batch cultivation 1Fed-batch cultivation 2

    Airlift cultivation

    Airlift bioreactors can provide an attractive alternative to stirred tanks, particularly for bioprocesses with gaseous reactants or products. 

    Applications
    • Can be used to culture highly shear-sensitive cells
    • Cultivation of filamentous fungi in liquid media - pellet

    Airlift cultivation

    Recent publications


    Oosthuizen L, Charimba G, Hitzeroth A, Nde AL, Steyn L, Newman J, Hugo C (2019) Chryseobacterium pennipullorum sp. nov., isolated from poultry feather waste. Int J Syst Evol Microbiol DOI: 10.1099/ijsem.0.003491. Impact Factor: 2.166

    Jiru TM, Steyn L, Pohl C, Abate D (2018) Production of single cell oil from cane molasses by Rhodotorula kratochvilovae (syn, Rhodosporidium kratochvilovae) SY89 as a biodiesel feedstock. Chem Cent J 12(1)91. DOI: 10.1186/s13065-018-0457-7. Impact factor 1.22

    Jiru TM, Groenewald M, Pohl C, Steyn L, Kiggundu N, Abate D (2017): Optimization of cultivation conditions for biotechnological production of lipid by Rhodotorula kratochvilovae (syn, Rhodosporidium kratochvilovae) SY89 for biodiesel preparation. 3 Biotech; 2/145. DOI: 10.1007/s13205-017-0769-7. Impact Factor: 1.361

    Schabort DWP, Letebele PK, Steyn L, Kilian SG, du Preez JC (2016) Differential RNA-seq, Multi-Network Analysis and Metabolic Regulation Analysis of Kluyveromyces marxianus reveals a Compartmentalised Response to Xylose. PLoS ONE, 11(6). DOI:10.1371/journal.pone.0156242 Impact Factor: 2.806

    Bekker A, Steyn L, Charimba G, Jooste P, Hugo C (2015) Comparison of the growth kinetics and proteolytic activities of Chryseobacterium species and Pseudomonas fluorescens. Can J Microbiol DOI: 10.1139/cjm-2015-0236 Impact Factor: 1.335

    Bekker A, Jooste P, Steyn L, Bothma C, Hugo A, Hugo C (2015) Lipid breakdown and sensory analysis of milk inoculated with Chryseobacterium joostei or Pseudomonas fluorescens. Int Dairy J; 52. DOI:10.1016/j.idairyj.2015.09.003. Impact Factor: 2.067

    Akanni GB, du Preez JC, Steyn L, Kilian SG (2014): Protein enrichment of an Opuntia ficus-indica cladode hydrolysate by cultivation of Candida utilis and Kluyveromyces marxianus. J Sci Food Agric; 95(5). DOI:10.1002/jsfa.6985. Impact Factor: 1.714

    Kuloyo OO, du Preez JC, Del Prado García-Aparicio M, Kilian SG, Steyn L, Görgens J (2014) Opuntia ficus-indica cladodes as feedstock for ethanol production by Kluyveromyces marxianus and Saccharomyces cerevisiae. World J Microbiol Biotech; 30(12). DOI: 10.1007/s11274-014-1745-6. Impact Factor: 1.658



    FACULTY CONTACT

    Elfrieda Lötter: Marketing Manager
    T: +27 51 401 2531
    E:lottere@ufs.ac.za


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