Expression of proteases by Rhizopus species during Tempeh fermentation of soybeans
1998
Heskamp, M.-L. | Barz, W.
Expression of proteolytic activities by nine Rhizopus strains during soybean fermentation to produce Tempeh has been determined. All strains showed activity at acidic, neutral, and alkaline pH values. In protein solubilizates prepared from Tempeh pronounced differences in the time course and intensity of maximum protease activities were observed between the isolates when measured at pH 7, the approximate pH of Tempeh during ripening. Proteases expressed by fungi during growthon Tempeh were solubilized and the enzymes were enriched by acetone precipitation and chromatographies with Phenylsuperose, Mono S, and Mono P, respectively. They were identified as one aspartic- and one serine protease, each existing in different isoforms. Proteases isolated from Tempeh were identical to those expressed during fungal growth in a soyprotein-raffinose-phytate liquid medium. Proteases isolated from Tempeh, cell walls and liquid media exhibit differences in the number of alkaline isoforms.
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