Abstract
Isolation and identification of new microbial isolates capable of producing cholesterol oxidase enzyme (CHO) is of great potential in the field of biotechnology of industrial enzymes. Four producing strains of actinomycetes were isolated from Egyptian soils demonstrated high activity in cholesterol degradation compared to the other isolates. Based on different standard morphological, biochemical as well as molecular techniques using 16S rRNA sequencing, these actinomycetes were identified as Streptomyces sp. strain NHIA_CH3 MK680299, Streptomyces sp. strain NHIA_CH5 MK680300, Streptomyces griseus strain NHIA_CH6 MK680301 and Streptomyces drozdowiczii strain NHIA_CH10 MK680302. In order to optimize the CHO enzyme activity, different fermentation media were tested in submerged cultures at shake flask level. Maximum activity (23.7 U/mL) was observed in culture of Streptomyces sp. strain NHIA_CH5 which was scaled up to the 5L volume of the stirred tank bioreactor. Results of the batch fermentation showed an earlier production of CHO enzyme with 4% increase in activity compared to that obtained from shake flask cultures indicated that Streptomyces sp. strain NHIA_CH5 could be a potential source of CHO enzyme for commercial purpose.