title: Immobilization of Lactococcus lactis to cellulosic material by cellulose-binding domain of Cellvibrio japonicus.
abstract: OBJECTIVE
  Immobilization of whole cells can be used to accumulate cells in a bioreactor and thus increase the cell density and potentially productivity, also. Cellulose is an excellent matrix for immobilization purposes because it does not require chemical modifications and is commercially available in many different forms at low price. The aim of this study was to construct a Lactococcus lactis strain capable of immobilizing to a cellulosic matrix.
  
  
  RESULTS
  In this study, the Usp45 signal sequence fused with the cellulose-binding domain (CBD) (112 amino acids) of XylA enzyme from Cellvibrio japonicus was fused with PrtP or AcmA anchors derived from L. lactis. A successful surface display of L. lactis cells expressing these fusion proteins under the P45 promoter was achieved and detected by whole-cell ELISA. A rapid filter paper assay was developed to study the cellulose-binding capability of these recombinant strains. As a result, an efficient immobilization to filter paper was demonstrated for the L. lactis cells expressing the CBD-fusion protein. The highest immobilization (92%) was measured for the strain expressing the CBD in fusion with the 344 amino acid PrtP anchor.
  
  
  CONCLUSIONS
  The result from the binding tests indicated that a new phenotype for L. lactis with cellulose-binding capability was achieved with both PrtP (LPXTG type anchor) and AcmA (LysM type anchor) fusions with CBD.
  
  
  CONCLUSIONS
  We demonstrated that an efficient immobilization of recombinant L. lactis cells to cellulosic matrix is possible. This is a step forward in developing efficient immobilization systems for lactococcal strains for industrial-scale fermentations.
authors.affiliation: Department of Applied Chemistry and Microbiology, Division of Microbiology, University of Helsinki, Helsinki, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Kylä-Nikkilä
authors.forename: U
authors.initials: U
authors.lastname: Alakuijala
authors.forename: P E J
authors.initials: PE
authors.lastname: Saris
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D019149:Bioreactors; D018914:Cells, Immobilized; D002482:Cellulose / Q000378:metabolism*; D020633:Cellvibrio / Q000201:enzymology*; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000235:genetics; D005285:Fermentation; D007218:Industrial Microbiology; D013294:Lactococcus lactis / Q000235:genetics* / Q000378:metabolism; D009113:Muramidase / Q000235:genetics; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D011993:Recombinant Fusion Proteins; D002482:Cellulose; C092497:AcmA protein, Lactococcus lactis; D009113:Muramidase; D043364:Endo-1,4-beta Xylanases