Production of lipopeptide antibiotic iturin A using soybean curd residue cultivated with Bacillus subtilis in solid-state fermentation

Abstract

Bacillus subtilis RB14-CS, which suppresses the growth of various plant pathogens in vitro by producing the lipopeptide antibiotic iturin A, was cultured using soybean curd residue, okara, a by-product of tofu manufacture in solid-state fermentation. After 4 days incubation, iturin A production reached 3,300 mg/kg wet solid material (14 g/kg dry solid material), which is approximately tenfold higher than that in submerged fermentation. When the okara product cultured with RB14-CS was introduced into soil infested with Rhizoctonia solani, which is a causal agent of damping-off of tomato, the disease occurrence was significantly suppressed. After 14 days, the number of RB14-CS cells remained in soil at the initial level, whereas almost no iturin A was detected in soil. As the okara cultured with RB14-CS exhibited functions of both plant disease suppression and nutritional effect on tomato seedlings, this product is expected to contribute to the recycling of the soybean curd residue.

Characterization of Enzymes Associated with Degradation of Insoluble Fiber of Soybean Curd Residue by Bacillus subtilis

“…The suppressive effect of one of the isolates, B. subtilis RB14, was mainly associated with the cyclolipopeptide antibiotic iturin A, which contains seven -amino acids and one -amino acid. B. subtilis RB14-CS, a derivative of the original strain RB14 and a sole producer of iturin A, produced iturin A in SSF using the soybean curd residue 3-fold higher than in submerged fermentation (SmF) (Mizumoto et al, 2006). This suggests that RB14-CS could degrade some kinds of insoluble fibers in soybean curd residue and utilize them as carbon sources during SSF.…”

“…The detail of SSF was described in the previous paper (Mizumoto et al, 2006). The L medium used for the growth of the bacterium contained 10 g of Polypepton (Nippon Pharmaceutical Co., Tokyo, Japan), 5 g of yeast extract and 5 g of NaCl (per liter).…”

“…Approximately 700,000 tons of the soybean curd residue were produced annually as a byproduct of tofu manufacturing in Japan and most of them is incinerated as an industrial waste. We re-utilized the soybean curd residue as a solid substrate of solidstate fermentation (SSF) using Bacillus subtilis (Mizumoto et al, 2006). The insoluble fibers of soybean consist of cellulose, hemicellulose and lignin.…”

Ocorrência e diversidade estrutural de metabólitos fúngicos com atividade antibiótica

“…A fermentação em estado sólido para a produção de antibióticos tem sido considerada muito vantajosa, com um aumento do rendimento e período fermentativo mais curto em relação a procedimentos paralelos realizados em culturas submersas. 44 Os ascocarpos de Eupenicillium molle Malloch et Chain (Trichocomaceae) foram alvo de estudo por fermentação em substrato sólido (grãos de milho). Ascocarpos são corpos de frutificação especializados, análogos aos esclerótios, adaptados a condições extremas de temperatura e restrição de nutrientes e água.…”

Physiological Active Substance Changes of Soybean Curd Residue Fermented by <i>Preussia aemulans</i> and its Bioactivity

“…Soybean Curd Residue (SCR), a by-product of tofu, soymilk or soy protein processing, is discharged as an agro-industrial waste and has caused severe environmental pollution (Mizumoto et al, 2006). In fact, dried SCR is quite rich in proteins (20-30%), lipids (9-20%), carbohydrates (more than 50%) and fibres (9-20%) (Surel and Couplet, 2005).…”