Bio-Oil Production from Fish Processing Waste Residues Using Oleaginous Rhodotorula sp. R1 After Conventional Oil Extraction

Fish waste is a major environmental pollution problem and requires costly treatment prior to disposal. Conversion of fish waste to economically important and eco-friendly products will make fishing and fish processing more valuable and sustainable. This study evaluated waste residues from fish processing waste subjected to conventional physical extraction of fish oil for single-cell oil production using oleaginous yeast. Potential application of the single-cell oil to produce biodiesel was evaluated. The treatment containing fish waste residue (5%, w/v) and glucose (20 g/L, w/v) displayed the highest rate (14%) of total lipid generation. The fish waste residue proved to be a good nitrogen source for the oleaginous yeast, Rhodotorula sp. R1. At 15% (w/v) fish waste residue and 20% (w/v) glucose amendment of the medium, the highest biomass production was observed. The yeast bio-oil has a lipid profile like vegetable oils and consists of mainly long-chain fatty acids (between C14 and C24) which are suitable for biodiesel production. The most abundant fatty acids were palmitic acid (C16:0), elaidic acid (C18:1n-9t), and stearic acid (C18:0). FTIR analysis of the transesterification reaction product using the yeast oil confirmed its conversion to biodiesel. Although glucose amendment of medium supported lipid accumulation, it can be replaced with wastes rich in sugars to decrease the cost of single-cell bio-oil production. Results indicate the potential secondary value of fish processing waste in the cultivation of oleaginous yeast for bio-oil and biodiesel production.