ABSTRACT
Sixty one thermoalkalophilic bacteria were isolated from soil samples in Saudi Arabia’s southern region. Isolate
TA-38, obtained from the Tanomah region, showed the best performance for enzyme production and was
submitted for further study. It was identified as Bacillus axarquiensis based on 16S rRNA gene sequencing
studies. The feasibility of using potato waste water as a simple and cheap medium for the production of α-
amylase was evaluated compared with starch broth medium. The production of α-amylase in the potato waste
water medium was only 13.8% less than that of the starch medium. Maximum enzyme production was achieved
after 48 hours of cultivation at the beginning of the stationary phase at pH 10.0 and 50 0C. The appropriate
addition of starch; nitrogen; phosphate; and calcium to potato waste water significantly enhanced the production
of α-amylase. The enzyme production reached a maximum of 64.5 Uml-1 with the potato wastewater adding
with 0.5 % starch; 0.4 % yeast extract; 0.04% CaCl2-2H2O and 0.05 % KH2PO4. The optimization of the potato
waste water medium led to an approximately 4.02 fold increase in the production of α-amylase compared to
starch broth medium. Data indicated that the potato waste water contained substrates which could be used by
bacterial isolate for the production of α-amylase production and the developed procedure was cost effective since
it requires only a slightly addition of nutrients to the medium.