Isolation, Purification and Characterization of a Lipase from Thermophilic Bacteria

Abstract

Fifty one bacterial isolates were isolated from Egyptian soil. These isolates were purified, and were examined for their ability to produce extracellular enzymes such as lipases, amylases, proteases and uricases. Four promising isolates were chosen based on their ability to produce lipolytic enzymes with significant level. These four isolates were abbreviated as 5, Ao, A72 and B72. After several rounds of screening, isolate 5 was selected as the promising lipase producing bacteria. Bacterial isolates were identified using biochemical tests as thermophilic Geobacillus. Further confirmation of biochemical characterization was carried out for isolate 5 utilizing 16S rRNA technique. Data were submitted to the GeneBank sequence database with a given accession number DQ923400. The bacterial isolate was identified as Geobacil/us stearothermophilus.

Growth and extracellular lipase production were monitored for the above four isolates and it was found that, production of lipase started at late log phase and increased gradually till reached its maximal rate of production at the stationary phase. The level of extracellular lipase production from isolate 5 started at late log phase of the bacterial f,>rowth, about 6 hours after inoculation when the bacterial isolate was f,>rown on PY or PY supplemented with olive oil. This level increased grad ally with bacterial grQwth till reached its maximal level (48.51 U/ml) after 3Q ho rs of inoculation on PY meqil)m and (47.04 U/ml) on PY medium supplementeq by 1% olive oil after 24 hours.