Characterization of Bacillus subtilis strains in Thua nao, a traditional fermented soybean food in northern Thailand

Abstract

Aims: To clarify the diversity of Bacillus subtilis strains in Thua nao that produce high concentrations of products useful in food manufacturing and in health‐promoting compounds. Method and Results: Production of amylase, protease, subtilisin NAT (nattokinase), and gamma‐polyglutamic acid (PGA) by the Bacillus subtilis strains in Thua nao was measured. Productivity of protease NAT by these strains tended to be higher than by Japanese commercial natto‐producing strains. Molecular diversity of isolated strains was analysed via randomly amplified polymorphic DNA‐PCR fingerprinting. The strains were divided into 19 types, including a type with the same pattern as a Japanese natto‐producing strain. Conclusion: B. subtilis strains that could be a resource for effective production of protease, amylase, subtilisin NAT, or PGA were evident in Thua nao produced in various regions in northern Thailand. Significance and Impact of the Study: This study clearly demonstrated the value of Thua nao as a potential resource of food‐processing enzymes and health‐promoting compounds.

A novel probiotic <i>Bacillus siamensis</i> B44v isolated from Thai pickled vegetables (<i>Phak-dong</i>) for potential use as a feed supplement in aquaculture

“…from fermented pork, fermented fish, fermented tea leaves and pickled garlic (Klayraung et al, 2008) and Bacillus sp. from fermented soybean (Thua nao) (Inatsu et al, 2006). Lactic acid bacteria, especially in the genus Lactobacillus, have been well-studied probiotics for a long time.…”

Ecology and genomics of Bacillus subtilis

“…In fact, B. subtilis has been touted as a probiotic that when ingested has "beneficial" effects, likely by helping to maintain or restore "healthy" bacterial communities in the body 18 . B. subtilis is also found in several commercially available fermented food products, including soy beans fermented with B. subtilis natto which is popular in Japan and which has been long thought to confer health benefits 19 . But as its role in plant growth promotion, just how B. subtilis imparts its probiotic effects is not clear.…”

Microbiota of Tayohounta, a fermented baobab flavour food of Benin

“…It was also the case for Asian fermented foods product of soybean fermentation for example, Kinema (Sarkar et al, 2002); Thua-nao (Inatsu et al, 2006). Heat resistance of B. subtilis spores has been investigated by Fox and Eder (1969) and Warth (1978), who found that the decimal reduction time at 100°C (D 100 ) was in the order of magnitude of 10 min.…”