From Waste to Protein: Optimizing Rice Husk Utilization for Sustainable Single Cell Protein Production

Abstract

The increasing global demand for protein has prompted a search for sustainable and cost-effective alternatives to traditional animal and dairy sources. Single-cell protein (SCP) produced from microorganism’s offers a promising solution due to its high protein content and rapid growth rates. This study addresses the challenge of utilizing rice husk, an abundant yet underutilized agricultural waste in Nigeria, as a substrate for SCP production. Through optimization of the production of SCP using Bacillus sp. AT-b3 and Bacillus sp. CMF 12 as model organisms. Molecular identification through 16S rRNA sequencing confirmed Bacillus sp. AT-b3 and Bacillus sp. CMF 12 as the most potent isolates for SCP production. Optimization studies were conducted using the One-Factor-at-a-Time (OFAT) method to determine the ideal fermentation conditions. The results showed that the optimal temperature for SCP production was 40 °C, with Bacillus sp. AT-b3 demonstrating superior production efficiency. pH optimization revealed that neutral pH (pH 7) was ideal for maximizing SCP production, with Bacillus spp. AT-b3 outperforming Bacillus sp. CMF 12 at this pH. Substrate concentration studies indicated that 2.0% was optimal for SCP production, and incubation time optimization indicated 48 hours as the optimal period for maximum yield. Amino acid profiling of the SCP produced showed significant variations between the two isolates. Bacillus sp. CMF 12 was richer in essential amino acids like Arginine and Methionine, while Bacillus sp. AT-b3 had a higher Glycine content at (p<0.05). The findings of this study suggest that both strains have potential applications in nutritional supplements, with Bacillus sp. AT-b3 being particularly suited for industrial-scale SCP production. This study concludes that Bacillus sp. AT-b3 is an efficient SCP producer under optimal conditions of neutral pH, moderate temperature, and appropriate substrate concentration. Further research is recommended to explore pilot-scale production, alternative substrates, and comprehensive safety assessments.