SUMMARY: Lipolysis by is due to the production of two major extracellular esterases. These were investigated using a turbidimetric assay with Tween 20 as the substrate. One esterase is cell-associated and found in the particulate fraction of cell-free extracts, the other esterase is secreted into the culture medium. In batch culture with 0.8% yeast extract as the medium the particulate esterase was produced mainly during the exponential growth phase and its yield was increased about twofold by the addition of olive oil and other substrates. The supernatant esterase was produced mainly after the exponetial growth phase and was induced six- to tenfold by olive oil. PAGE, combined with activity staining using Tween 20 as the substrate, indicated that the two enzymes have different electrophoretic mobilities. Intact cells expressed 87% of the particulate cell-associated esterase activity. The enzyme was released from cells or from the particulate fraction by incubation with 0.2% Zwittergent 3-14. Tween 20 (2%, v/v) or 1 mM-EDTA released little of the enzyme from whole cells. Separation of the inner and outer membranes of showed that the particulate esterase was localized in the outer membrane. Both esterases were very active with Tween 20 as the substrate, but they hydrolysed other compounds at very different rates. The relative activities with Tween 20, p-nitrophenyl palmitate, tributyrin and olive oil were 100, 3, 11 and 0 for the particulate esterase and 100, 73, 0 and 28 for the secreted esterase. In addition to these two extracellular esterases, contains a hydrolase in the cytoplasm which is most active with tributyrin.


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