ConclusionsIt is clear from this study and other published works that lowspecific growth rate control feeding consistently helped to enhancethe production of extracellular microbial lipase in HCDF. This is irre-spective of the nature of the immiscible substrate used for growthand lipase production i.e., either a pure fatty acid such as oleic acidor whole plant oil such as palm oil. The exact reason behind theincreased lipase production when this specific feeding mode wasused in HCDF is unclear at this stage. It is suggested that a moredetailed study using tools such as proteomics analysis may providebetter explanation for the observed effect.In addition to the substrate feeding mode being relatively sim-pler to implement, the use of refined palm oil as an alternativecarbon substrate to oleic acid proved effective for microbial lipaseproduction. Moreover, using palm oil as the sole substrate obvi-ated the need for chemical antifoams in the production of lipase.Overhead costs of producing lipase could be made to be very com-petitive when the fermentation facilities are in close proximity ofthe oil palm plantation in addition to leveraging on the existingpalm oil mill infrastructure.