title: Lipase localization in Rhizopus oryzae cells immobilized within biomass support particles for use as whole-cell biocatalysts in biodiesel-fuel production.
abstract: To identify the lipase responsible for the methanolysis activity of fungus whole-cell biocatalysts, the lipase localization of Rhizopus oryzae cells was determined. Western blot analysis showed that R. oryzae cells produce two types of lipase with different molecular masses of 34 and 31 kDa; the former (ROL34) was bound to the cell wall, whereas the latter (ROL31) was mainly bound to the cell membrane. It was found that cell immobilization within reticulated polyurethane foam biomass support particles strongly inhibits the secretion of membrane-bound lipase into the culture medium. An investigation of the relationship between ROL34 and ROL31 suggested that ROL31 originates from the cleavage of a 28-amino-acid residue at the N-terminus of ROL34. The addition of olive oil to the culture medium led to the retention of increased amounts of lipase within the cell. This phenomenon was further confirmed by an immunofluorescence labeling of hyphal cells. When cells were cultivated with various substrate-related compounds, such as olive oil and oleic acid, the intracellular methanolysis activity strongly correlated with the relative amounts of the membrane-bound lipase, which suggests that ROL31 localized in the membrane plays a crucial role in the methanolysis activity of R. oryzae cells.
authors.affiliation: Department of Molecular Science and Material Engineering, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Hama
authors.forename: Sriappareddy
authors.initials: S
authors.lastname: Tamalampudi
authors.forename: Takahiro
authors.initials: T
authors.lastname: Fukumizu
authors.forename: Kazunori
authors.initials: K
authors.lastname: Miura
authors.forename: Hideki
authors.initials: H
authors.lastname: Yamaji
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
authors.forename: Hideki
authors.initials: H
authors.lastname: Fukuda
mesh_terms: D000595:Amino Acid Sequence; D018533:Biomass; D001709:Biotechnology / Q000379:methods*; D002384:Catalysis; D002462:Cell Membrane / Q000378:metabolism; D004736:Energy-Generating Resources; D004951:Esterification; D005658:Fungi / Q000201:enzymology; D008049:Lipase / Q000737:chemistry*; D008969:Molecular Sequence Data; D000069463:Olive Oil; D010938:Plant Oils / Q000737:chemistry; D017434:Protein Structure, Tertiary; D012233:Rhizopus / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D000069463:Olive Oil; D010938:Plant Oils; D008049:Lipase