S58: Halophilic Archaea and starch: Two compatible objects

The halophilic Archaea live in hypersaline environments from 8 to 30% salt.  Consequently, many of their enzymes are adapted to low water activity levels and high salt concentrations.  Additionally, this group generally grows in oligotrophic environments such as solar salt pans, brine springs, and salt plains.  The excretion of extracellular enzymes is common among this group of bacteria.  This paper will review what is known about the extracellular amylases of the haloarchaea.  It will also describe some of our recent laboratory studies of the amylase(s) from an isolate from the solar salt works in Eilat, Israel.  The amylase was purified  over 100 fold.  It exhibited optimum activity at pH 7.5 with the optimum temperature of 37degree C.  It has an absolute requirement for NaCl with the optimum being 25% NaCl, which is the optimal growth salt concentration for the growth of this isolate.  However, amylase activity was detected in the pH range of 6.5 to 8.0, over the temperature range of 20 degree C to 42 degree C, and NaCl concentration of 12% to 30%.  Studies on the type of starch hydrolysis will also be reported.