Article

Rhizopus oryzae fungus cells producing L(+)-lactic acid: kinetic and metabolic parameters of free and PVA-cryogel-entrapped mycelium.

Chemical Enzymology Department, Chemistry Faculty, The M.V. Lomonosov Moscow State University, Lenin's Hills, 1/11, Moscow 119992, Russia.
Applied Microbiology and Biotechnology (Impact Factor: 3.81). 10/2006; 72(3):480-5. DOI: 10.1007/s00253-005-0297-y
Source: PubMed

ABSTRACT Spores of the filamentous fungus Rhizopus oryzae were entrapped in macroporous poly(vinyl alcohol) cryogel (PVA-cryogel). To prepare immobilised biocatalyst capable of producing L(+)-lactic acid (LA), the fungus cells were cultivated inside the carrier beads. The growth parameters and metabolic activity of the suspended (free) and immobilised cells producing LA in a batch process were comparatively investigated. The immobilised cells possessed increased resistance to high concentrations of accumulated product and gave much higher yields of LA in the iterative working cycle than the free cells did. Detailed kinetic analysis of the changes in the intracellular adenosine triphosphate concentration, specific rate of growth, substrate consumption and LA production showed that the fungus cells entrapped in PVA-cryogel are more attractive for biotechnological applications compared to the free cells.

0 Followers
 · 
188 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: It is shown that is possible to obtain up to 15 g/l lactic acid in the organic phase within 25 h using Rhizopus oryzae fungus cells immobilized in a polyvinyl alcohol cryogel with simultaneous product extraction into octane with trioctylmethylammonium chloride as a lactate ion carrier.
    Theoretical Foundations of Chemical Engineering 03/2007; 41(2):150-153. DOI:10.1134/S0040579507020078 · 0.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effect of cell storage at -18 degrees C for 18-24 months on reproductive capacity was investigated for various microorganisms (gram-positive and gram-negative bacteria, yeasts, and filamentous fungi) immobilized in poly(vinyl alcohol) cryogel. To examine the viability of immobilized cells after defrosting, the bioluminescent method of intracellular ATP determination was used. A high level of metabolic activity of immobilized cells after various periods of storage was recorded for Streptomyces anulatus, Rhizopus orvzae, and Escherichia coli, which are producers of the antibiotic aurantin, L(+)-lactic acid, and the recombinant enzyme organophosphate hydrolase, respectively. It was shown that the initial concentration of immobilized cells in cryogel granules plays an important role in the survival of Str. anulatus and Pseudomonas putida after 1.5 years of storage. It was found that, after slow defrosting in the storage medium at 50C for 18 h of immobilized cells of the yeast Saccharomvces cerevisiae that had been stored for nine months, the number of reproductive cells increased due to the formation of ascospores.
    Mikrobiologiia 06/2007; 76(3):383-9. DOI:10.1134/S0026261707030113
  • [Show abstract] [Hide abstract]
    ABSTRACT: Macroporous gels (MGs) with a broad variety of morphologies are prepared using the cryotropic gelation technique, i. e. gelation at subzero temperatures. These highly elastic hydrophilic materials can be produced from practically any gel-forming system with a broad range of porosity extending from elastic and porous gels with pore sizes up to 1.0 microm to elastic and sponge-like gels with pore sizes up to 100 microm. The versatility of the cryogelation technique is demonstrated by use of different chemical reactions (hydrogen bond formation, chemical cross-linking of polymers, free radical polymerization) mainly in an aqueous medium. Appropriate control over solvent crystallization (formation of solvent crystals) and rate of chemical reaction during the cryogelation allows the reproducible preparation of cryogels with tailored properties. Different approaches, such as chemical modification of reactive groups, grafting of the pore surface with an appropriate polymer, or direct copolymerization with functional monomers are used for control of the surface chemistry of MGs. Typically, MGs with pore sizes up to 1.0 microm are produced in the shape of beads and MGs with pore size up to 100 microm are prepared as monoliths, discs, and sheets. The difference in porous structure of MGs defines the main applications of these porous materials. Elastic beaded MGs are mostly used as carriers for cell and enzyme immobilization or for capture of low-molecular weight targets from particulate-containing fluids in expanded-bed mode. However, the elastic and sponge-like MG monoliths with interconnected pores measuring hundreds of mum have been successfully used as monolithic columns for chromatography of particulate-containing fluids (crude cell homogenates, viruses, whole cells, wastewater effluents) and as three-dimensional scaffolds for mammalian cell culture applications.
    Journal of Separation Science 07/2007; 30(11):1657-71. DOI:10.1002/jssc.200700127 · 2.59 Impact Factor
Show more

Preview

Download
9 Downloads
Available from