Partial characterization of a crude cold-active lipase from Rhodococcus cercidiphylli BZ22.
Cold-active lipase production by the psychrophilic strain Rhodococcus cercidiphylli BZ22 isolated from hydrocarbon-contaminated alpine soil was investigated. Depending on the medium composition, high cell densities were observed at a temperature range of 1-10 °C in Luria-Bertani (LB) broth or 1-30 °C in Reasoner's 2A (R2A). Maximum enzyme production was achieved at a cultivation temperature of 1-10 °C in LB medium. About 70-80% of the secreted enzyme was bound to the cell and was highly active as a cell-immobilized lipase which exhibited good reusability; more than 60% of the initial lipase activity was retained after five-fold reuse. The properties of the lipase produced by the investigated strain were compared with those of a mesophilic porcine pancreatic lipase (PPL). The thermal stability of the cell-immobilized bacterial lipase was higher than that of the extracellular enzyme. Highest activity was detected at 30 °C for the cell-immobilized enzyme and for PPL, while the extracellular enzyme displayed highest activity at 10-20 °C. The bacterial lipase hydrolyzed p-nitrophenyl (p-NP) esters with different acyl chain lengths (C2-C18). The highest hydrolytic activity was obtained with p-NP-butyrate (C4) as substrate, while the highest substrate affinity was obtained with p-NP-dodecanoate (C12) as substrate, indicating a clear preference of the enzyme for medium acyl chain lengths.
Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, College of Life Science, Jilin University, 2699 Qianjin Street, Changchun, 130012, People's Republic of China.
Dahai
D
Yu
Rosa
R
Margesin
D003080:Cold Temperature; D003470:Culture Media / Q000737:chemistry; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D008049:Lipase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D050356:Lipid Metabolism; D012240:Rhodococcus / Q000201:enzymology* / Q000254:growth & development / Q000302:isolation & purification; D012988:Soil Microbiology; D013379:Substrate Specificity; D013696:Temperature
D003470:Culture Media; D004800:Enzymes, Immobilized; D008049:Lipase