Free Amino Acid Profiles of Fermented Soybean Products Prepared by Bacillus subtilis and Rhizopus oligosporus

Fermented soybean is one of the traditional foods widely consumed in many Asian countries. Most products(i.e., Natto, Jang, Kinema and Thua nao) are produced mainly by the bacterial activity. This study was performed as a part of the program to improve the soybean fermentation, and a use of the co-culture between the bacterium Bacillus subtilis and the fungus Rhizopus oligosporus was selected. For fermentation, the raw soybeans were washed, sterilized by autoclaving, and inoculated with a mixed microbial starter culture of B. subtilis(102 CFU · g~(-1)) and R. oligosporus(102 conidia · g~(-1)). The Free Amino Acid(FAA) contents were then investigated by using High Performance Liquid Chromatography(HPLC). The results showed that the amounts of FAAs and essential amino acids in the fermented soybean samples were found at significantly higher concentration when compared to those of the cooked, non-fermented soybean samples(p0.05). These data indicated that an involvement of microbial fermentation helped to accelerate an increase of FAA. The food compositional data were useful as a reference(and/or guidance) for the nutritional value, when compared to other fermented soybeans and related products.     

Screening of Actinomycetes from Medicinal Plant Rhizosphere Soils for Industrial Enzymes and Antimicrobial Activity

This study aimed to investigate the production of some metabolites(i.e., antibiotics, amylases and cellulases) of terrestrial actinomycetes isolated from medicinal plant rhizosphere soils. Initially, the soil samples were collected from Camellia sinensis(L) Okuntze., Peuraria mirifica Airy Shaw Suvatabandhua., Ananus comosus Merr., Elephantopus scaber Linn., Orthosiphon grandiflorus Bolding., Jatropha multifida Linn. and Senna siamea. To screen and isolate actinomycetes, the soil samples were pretreated by airdrying and subsequent heat incubation. The bacterial isolates exhibiting actinomycetes features were then randomly screened for their production of amylases, cellulases and antibiotics. It was found that 130 isolates(from 136) could produce amylases; 40(from 107) produced cellulases; and seven(from 45) exhibited antimicrobial activity. The data of this study were preliminary, and yet demonstrated a rich diversity of rhizo-actinomycetes from medicinal plants. Besides, these organisms could be an untapped source for discovering of biotechnologically useful metabolites.     

Genetic diversity and population structure of blast resistance genes in Thai upland rice germplasm

European Journal of Plant Pathology - Rice blast is the most devastating disease of rice (Oryza sativa L.) causing yield losses worldwide. It had been shown that partially resistant rice varieties...