Potential L-asparaginase producing E.coli sources among River water and cafeteria sewage: The case of Wabe River and Wolkite University students' cafeteria in Wolkite, Ethiopia.

L-asparaginase is a promising enzyme for cancer treatment and is found in plants, animals and microbes. This enzyme is of great medical and industrial importance. It is used with inside the remedy of acute lymphoblastic leukemia and helps in reducing the acryl amide substances found in fried and baked foods. Its source varies from bacteria to yeast and fungi. This study aimed to screen the potential L-asparaginase producing E. coli isolates among river water and cafeteria sewage samples near the Gubryie area, SNNPR-Ethiopia. In this study, E. coli isolates were isolated from sewage from the Wabe River and Wolkite University student cafeteria. During the study, 14 isolates, 11 from cafeteria sewage and 3 from Wabe River, were confirmed to be E. coli using IMViC, TSI, SCA, and Gram tests. For the E. coli-positive samples, screening of L-asparaginase was performed using the phenol red indicator. The change in color from yellow to pink in M9 media due to the acidic environment created when L-asparagine was degraded to urea indicates the presence of L-asparginase in the potent E. coli cells. The production of L-asparaginase was carried out using submerged fermentation method. Mechanical cell disruption method, high speed centrifugation, was used to separate the secreted enzyme from cells. The potential of the E. coli cells to produce L-asparginase was also checked using a rapid plate assay method with the indicator dye phenol red. The zone of inhibition for the intracellular enzyme activity ranges from 16.5 mm up to 22.25 mm while that of extracellular enzyme ranged from 7.5 mm up to 9 mm. The commonly used software system is SPSS version 23. The PCR result depicted that the ansA gene presence was confirmed in 50% of the isolates. The result confirmed that the E.coli isolates from sewage showed better L-asparaginase production potency than the Wabe River isolates. This study indicated that E. coli strains are promising sources of L-Asparginase for food and pharmacological companies if the scale-up of this work has been completed in the future.