Culture ofStaphylococcus xylosusin fish processing by-product-based media for lipase production

AIMS: The objective of this study was to demonstrate that fish-processing by-products could be used as sole raw material to sustain the growth of Staphylococcus xylosus for lipase production. METHODS AND RESULTS: Bacterial growth was tested on supernatants generated by boiling (100 degrees C for 20 min) of tuna, sardine, cuttlefish and shrimp by-products from fish processing industries. Among all samples tested, only supernatants generated from shrimp and cuttlefish by-products sustained the growth of S. xylosus. Shrimp-based medium gave the highest growth (A(600) = 22) after 22 h of culture and exhibited the maximum lipase activity (28 U ml(-1)). This effect may be explained by better availability of nutrients, especially, in shrimp by-products. Standard medium (SM) amendments to sardine and tuna by-product-based media stimulated the growth of S. xylosus and the highest A(600) values were obtained with 75% SM. Lipase activity, however, remained below 4 U ml(-1) for both sardine and tuna by-product-based media. CONCLUSIONS: Fish by-products could be used for the production of highly valuable enzymes. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of fish by-products in producing S. xylosus-growth media can reduce environmental problems associated with waste disposal and, simultaneously, lower the cost of biomass and enzyme production.