PRODUCTION, CHARACTERIZATION, AND SELECTIVE ANTI-PROLIFERATIVE ACTIVITY OF A NOVEL L GLUTAMINASE FROM STREPTOMYCES SP. ISOLATED FROM VOLCANIC SOIL OF MOUNT UHUD, SAUDI ARABIA

Abstract

Extreme environments such as volcanic soils represent valuable yet underexplored reservoirs of microbial diversity, particularly actinomycetes capable of producing valuable important enzymes. In this study, a potent L glutaminase-producing actinomycete was isolated from volcanic soil collected from Mount Uhud. Isolates were screened for enzyme production on minimal glutamine agar using phenol red as a pH indicator. The most efficient strain (A6) was identified as Streptomyces sp. based on morphological characteristics and 16S rRNA gene sequencing. Optimization of cultural conditions revealed that maximum L-glutaminase production (6.895 U/mL) occurred at 5°C, indicating that the isolate is a psychrophilic or psychrotolerant producer. Biochemical characterization of the partially purified enzyme demonstrated broad catalytic activity across a wide temperature range (5–60°C), with maximum activity observed at both 37°C and 60°C, as well as optimal activity at pH 7.0 suggesting thermophilic catalytic potential. This thermal versatility in catalytic function, coupled with the cold active production optimum, highlights the enzyme's adaptability for diverse biotechnological applications. Enzyme activity was inhibited by Fe²⁺, Cu²⁺, and Hg²⁺ ions but remained unaffected by EDTA, suggesting that the enzyme is not a metalloenzyme and may involve sulfhydryl groups in catalysis. Biological evaluation using the MTT assay revealed selective anti-proliferative activity against colon cancer cells (HCT116) with an IC₅₀ value of 34.27 ± 0.3 µg/mL after 72 hours, while no significant cytotoxicity was observed against breast (MCF-7) or lung (A549) cancer cell lines. These findings highlight volcanic soil actinomycetes as sources of thermally versatile L-glutaminase with potential applications in environmental biotechnology and anticancer strategies.