The B. subtilis LS 1-2 grown on CB was used as starter to produce probiotic product by solid substrate fermentation (SSF). Citrus juice waste was used as substrate and water was added to maintain a 30% moisture level followed by pasteurization. Then the substrate (13 kg) was inoculated with 2 L of starter and fermented for 7 d at 32 C and pH 7.0. After 7 d of fermentation the microbial biomass was dried in a forced-air drying oven at 40 C for 72 h. The B. subtilis count in SSF product was 1.0 104 cfu/g.