Sources, properties and suitability of new thermostable enzymes in food processing

Investigations concerning recombinant alpha-amylases from Pyrococcus woesei and thermostable alpha-glucosidase from Thermus thermophilus indicate their suitability for starch processing. Furthermore, lite study of recombinant beta-galactosidase from Pyrococcus woesei suitable for purpose of low lactose milk and whey production are also presented. The activity of this enzyme in a wide pH range of 4.3-6.6 and high thermostability suggests that it call be used for processing of dairy, products at temperatures which restrict microbial growth during a long operating little of continuous-flow reactor with all immobilized enzyme system. Preparation of recombinant alpha-amylase and beta-galactosidase was facilitated by cloning and expression of genes,from Pyrococcus woesei in Escherichia coli host. Satisfactory level of recombinant enzymes purification was achieved by thermal precipitation of native proteins originated from Escherichia coli. The obtained alpha-amylase has maximal activity at pH 5.6 and 93 degrees C. The half-life of this preparation (pH 5.6) at 90 degrees C and 110 degrees C was 11 h and 3.5 h, respectively, and retained 24% of residual activity following incubation for 2 h at 120 degrees C. An advantageous attribute of recombinant cl-amylase is independence of its activity and stability on calcium salt. alpha-Glucosidase from Thermus thermophilus also not require metal ions for stability and retained about 80% of maximal activity at pH range 5.8-6.9. Thus, this enzyme call be used together with recombinant alpha-amylase.