Iran J Biotechnol. 2026 Apr 1;24(2):e4184. doi: 10.30498/ijb.2025.532876.4184. eCollection 2026 Apr.
ABSTRACT
BACKGROUND: The increasing environmental impact of food waste, especially starch-rich residues, necessitates sustainable biodegradation methods to reduce pollution and resource wastage.
OBJECTIVES: This study aimed to isolate α-amylase-producing bacteria from saline-rich organic soils in Jeddah, Saudi Arabia, and assess their effectiveness in degrading food waste through enzymatic starch hydrolysis.
MATERIALS AND METHODS: Twenty bacterial isolates were screened on starch agar for amylolytic activity. The most productive strain, Bacillus subtilis A16, was identified using biochemical assays (Gram staining, catalase/oxidase tests) and 16S rRNA sequencing. Enzyme production was optimized at different pH levels (4-9) and temperatures (30-60 °C). Purification involved ammonium sulfate precipitation (80% saturation), dialysis, and chromatography (Sephadex G-100, DEAE-Sephadex A-50). The purified enzyme was applied to 10 kg of food waste (bread and fruits) to evaluate degradation efficiency.
RESULTS: B. subtilis A16 exhibited the highest α-amylase activity (1.467 U. mL-1) with optimal performance at pH 8 (0.588 U. mL-1) and 40 °C (1.386 U.mL-1). Purification resulted in a 58 kDa enzyme with a 3.7-fold increase in specific activity (5.448 U.mg-1). Food waste treated with AK16 showed a 50% volume reduction within 25 days, accompanied by rapid starch decomposition.
CONCLUSIONS: The study highlights B. subtilis A16 as a highly effective and environmentally friendly biocatalyst for the degradation of starch-rich waste. Its excellent alkaline and thermal stability, along with its ability to efficiently reduce waste, demonstrate its potential for sustainable use in industrial and environmental settings. These results present a promising bio-based approach to managing organic waste, promoting a circular economy, and minimizing the environmental impact of waste disposal.
PMID:42145979 | PMC:PMC13179439 | DOI:10.30498/ijb.2025.532876.4184