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The moderately halophilic Halomonas sp. strain AAD21, which produces extracellular thermostable alpha-amylase, was isolated from the Camalti Saltern area located in Izmir, Turkey. NaCl, carbon, and nitrogen sources in the growth medium were optimized to enhance alpha-amylase yield. The highest enzyme yield was measured in the presence of 20% NaCl with peptone as the nitrogen and starch as the carbon sources in the fermentation broth. This microorganism was also found to utilize waste potato peel as a carbon source for alpha-amylase production. Concentrations of carbon and nitrogen sources were optimized using a statistical approach, and alpha-amylase activity increased from 4.07 U mL(-1) min(-1) to 26.25 U mL(-1) min(-1). Maximum alpha-amylase production was achieved at the end of 48 h of growth in the presence of 20% NaCl, 4.12% starch, 1.0% peptone, 0.2% KCl, 2% MgSO4 center dot 7H(2)O, and 0.03% trisodium citrate pentahydrate. The optimum pH and temperature of the alpha-amylase were found to be 7.0 and 50 degrees C, respectively. The alpha-amylase synthesized by Halomonas sp. AAD21 was also thermostable. Crude alpha-amylase did not lose its original activity after 2 h of incubation at 50 degrees C and 60 degrees C, and it retained 70% of its original activity after 120 min of incubation at 90 degrees C.

Hepatitis B is a major public health problem worldwide, which may lead to chronic liver diseases such as cirrhosis and hepatocellular carcinoma. The hepatitis B core antigen (HBcAg) is one of the major viral proteins, which forms the inner core of hepatitis B virus (HBV) particles. In this study, filamentous bacteriophage M13 was genetically modified to display the polypeptides of HBcAg in order to develop an alternative carrier system. HBcAg gene was inserted into the minor coat protein (pIII) gene of M13, and HBcAg was expressed on the phage surface as a whole protein. Antigenicity and immunogenicity of HBcAg were tested by immunizing BALB/c mice three times with HBcAg-displaying recombinant phages. After successful immunization, one of the mice with high antibody titer to HBcAg was selected for fusion, and four monoclonal antibodies specific for HBcAg were developed. This result showed that HBcAg-displaying recombinant bacteriophages are immunogenic and can potentially be used for the development of monoclonal antibodies.