Abstract:
An extracellular lipase with a molecular weight of 99 KDa from a
Thermoactinomycete sp. isolated from an olive oil contaminated soil (Al
Koura, Lebanon) was purified using ammonium sulphate, Sephadex G-25 and ion exchange chromatography (DEAE cellulose). The enzyme had more affinity to p- nitrophenyllaurate than to 0- nitrophenyllaurate and it was stable after boiling for 1 hour while the purified fraction showed activity only at 60°C. Enzyme activity was measured in the presence of different substrates and a high affinity to p- nitrophenyl palmitate and p- nitrophenyl laurate, was detected. However, the enzyme didn't react at all with tripalmitin, trierucin,
trielaidin, 1,3 diolein and triolein. The presence of metal ions like Ca2+ and
Fe3+ activated the enzyme, while Co2+, Mg2+, Zn2+, and Fe2+ totally inhibited the lipase activity. Finally, the lipase had a short shelf life, even in the presence of Ca2+.
