Isolation, Identification, and Characterization of L-asparaginase-Producing Human Commensal Bacterial Strains: A...

Area of Science:

• Microbiology
• Biochemistry
• Cancer Therapeutics

Background:

• L-asparaginase is an FDA-approved leukemia treatment but causes side effects due to antigenicity and L-glutaminase activity.
• Glutaminase-free L-asparaginase from human commensal bacteria offers a potential alternative to mitigate these adverse effects.

Purpose of the Study:

• To isolate and characterize L-asparaginase-producing bacteria from human commensal sources.
• To evaluate the enzymatic properties and safety profile of the isolated L-asparaginase for potential therapeutic applications.

Main Methods:

• Isolation of L-asparaginase-producing bacterial strains from human stool and saliva samples.
• Enzymatic assays to determine L-asparaginase and L-glutaminase activity.
• Antibiotic sensitivity testing, pH, and bile tolerance assays.
• Biochemical characterization of purified L-asparaginase, including molecular weight determination.

Main Results:

• Fourteen L-asparaginase-producing strains were identified across Acinetobacter, Escherichia, Klebsiella, and Pseudomonas genera.
• Several isolates, including Escherichia coli 3F1, 3F2, and Klebsiella pneumoniae 3S3, produced glutaminase-free L-asparaginase with high specific activity.
• These promising isolates exhibited antibiotic sensitivity and tolerance to low pH and bile, suggesting probiotic potential.
• Purified L-asparaginase from K. pneumoniae 3S3 was a homodimer (110 kDa native, 55 kDa subunit).

Conclusions:

• Human commensal bacteria represent a novel source of therapeutically relevant, glutaminase-free L-asparaginase.
• Selected isolates demonstrate potential for developing safer cancer therapies and next-generation probiotics.
• Further research into the antitumor and immunomodulatory properties of these enzymes is warranted.