Preliminary investigation on the conversion of aquaculture solid waste into single cell protein (SCP) from re-circulatory slug for fish feed

Abstract

Conversion of aquaculture solid wastes into single cell protein (SCP) for fish feed through solid state fermentation using three fungi species, Aspergilus niger, Trichodema viride and Rhizopus species were investigated. Solid aquaculture waste was collected from the sedimentation unit of a re-circulating aquaculture farm in Ibadan. Half of it was sun dried at 29ºC for 9 days while the second half was oven dried at 80ºC for 12 hours. The processed waste was then fermented for 0, 7,9,12 and 14 days using the three fungi species in a solid state fermentation method. The performance of the fungi, processing methods and nutrient values of the fermented waste was determined by the proximate analysis of the samples, while the percentage protein increase was calculated. Data obtained were subjected to analysis of variance (ANOVA), Correlation analysis and descriptive statistics. Processing methods influenced the performance of fungi species and the protein content of the SCP from the waste. Sun dried waste fermented with Rhizopus sp gave the highest crude protein of 28.75% which was significantly higher (P<0.05) than SCP from T. viride (22.75%) and A. niger (17.45%). Calculated % protein increase shows that Rhizopus sp performed best with 59.0% increase in protein of aquaculture waste after 7 days of fermentation which was significantly higher (P <0.05) than 42.5% for T. viride after 14 days and (5.0%) for A. niger after 9days of fermentation. There was an inverse correlation (P <0.05) between % C.P and period of fermentation with Rhizopus sp, while T .viride shows direct correlation for oven dried samples.

Key words: Solid waste, Single cell Protein, Aspergilus niger, Trichodema viride, Rhizopus species.