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To produce a thermostable and neutral phytase (phy) of Bacillus subtilis E20 in Escherichia coli HMS174 and evaluate its efficiency in improving growth performance. The phy C of B. subtilis E20 was expressed in E. coli HMS 174, and then the 42‐kDa recombinant phy C was purified by Ni‐NAT and analysed by SDS–PAGE. The recombinant phy C had optimal ranges of pH of 6 ~ 7 and temperature of 50 ~ 60 °C. A thermostability analysis showed that the enzyme is a thermostable phytase, and around 33% of residual activity was detected after being incubated at 90 ~ 100 °C for 10 min. The recombinant phy C‐pretreated soybean meal for feed preparation improved white shrimp, Litopenaeus vannamei, growth and feed efficiency. Overall, the neutral and thermostable phy C is suitable for aquafeed, and it is able to improve the nutritional utilization, resulting in enhanced shrimp growth and reduced feed costs.

Application of nanofiltration membranes to processing sweet whey and skim milk ultrafiltration permeate increased lactose crystal yield by about 10 and 8 %, respectively, at a concentration factor of 3.0. These increases were attributed to depletion of minerals, especially monovalent cations such as sodium and potassium, by the partial demineralization effect of the nanofiltration membrane. These membranes may be incorporated into current industrial processes for producing lactose from whey and milk permeates.