earticle

영어

Palm kernel cake (PKC), a by-product of palm oil industry, is a potential feed source for poultry. However, its use as poultry feed is limited due to its high fiber (mannan) content. Therefore, we have developed bioconversion process to improve the nutritive value of PKC as poultry feed. Previously, we showed successful bioconversion of PKC by solid-state fermentation with novel manannase producing strains, such as Bacillus subtilis MBS1 and Aspergillus oryzae MFO1. In this study, to reduce energy cost for sterilization of substrate, attempts have been made to develop novel fermentation process, which use non-sterilized PKC substrate. We have been
investigated organic acid treatment of PKC substrate to control microbial contamination during fermentation of non-sterilized PKC substrate. Treatment of raw PKC with acetic acid showed reduced level of contaminants, especially Gramnegative bacteria, indicating possible use of organic acid treatment as a cost effect method for semi-aseptic fermentation. As another alternative method to steam sterilization, the use of lactic acid bacteria as adjunct culture for bioconversion of nonsterilized PKC was studied. Addition of Lactobacillus spp. during fermentation of non-autoclaved PKC significantly reduced the growth of contaminant without any
effect on the growth of Aspergillus oryzae MFO1. The level of mannanase production during fermentation of non-sterilized PKC with lactic adjunct culture was comparable to that of autoclaved PKC substrate. These results suggested the possible use of organic acid and lactic strain as adjunct culture to reduce energy cost for the bioconversion of PKC as poultry feed.