Characterization of salt-tolerant glutaminase from Stenotrophomonas maltophilia NYW-81 and its application in Japanese soy sauce fermentation

Abstract

Glutaminase from Stenotrophomonas maltophilia NYW-81 was purified to homogeneity with a final specific activity of 325 U/mg. The molecular mass of the native enzyme was estimated to be 41 kDa by gel filtration. A subunit molecular mass of 36 kDa was measured with SDS-PAGE, thus indicating that the native enzyme is a monomer. The N-terminal amino acid sequence of the enzyme was determined to be KEAETQQKLANVVILATGGTIA. Besides L: -glutamine, which was hydrolyzed with the highest specific activity (100%), L: -asparagine (74%), D: -glutamine (75%), and D: -asparagine (67%) were also hydrolyzed. The pH and temperature optima were 9.0 and approximately 60 degrees C, respectively. The enzyme was most stable at pH 8.0 and was highly stable (relative activities from 60 to 80%) over a wide pH range (5.0-10.0). About 70 and 50% of enzyme activity was retained even after treatment at 60 and 70 degrees C, respectively, for 10 min. The enzyme showed high activity (86% of the original activity) in the presence of 16% NaCl. These results indicate that this enzyme has a higher salt tolerance and thermal stability than bacterial glutaminases that have been reported so far. In a model reaction of Japanese soy sauce fermentation, glutaminase from S. maltophilia exhibited high ability in the production of glutamic acid compared with glutaminases from Aspergillus oryzae, Escherichia coli, Pseudomonas citronellolis, and Micrococcus luteus, indicating that this enzyme is suitable for application in Japanese soy sauce fermentation.

Optimization and purification of anticancer enzyme L-glutaminase from Alcaligenes faecalis KLU102

“…The molecular weight of the enzyme determined in the present study is in agreement with that of Wakayama et al (2005), who reported a 36 kDa glutaminase from Stenotrophomonas maltophilia. The purified Lglutaminase also exhibited salt tolerance up to a concentration of 16% (w/v) and had a residual activity of 93.04% after incubation for two hours at 40…”

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“…17 . Contradicting report on glucose -mediated suppression of the LGlutaminase production in Achromobacteraceae 43 , S. maltophilia NYW-81 45 was also reported. Sucrose (Z. rouxii) and sorbital (B. bassiana BTMF S10) also supported L-Glutaminase production in addition to glucose.…”

“…It was noticed that addition of yeast extract enhanced the LGlutaminase secretion by C. nodaensis 38 , B. bassiana BTMF S10 36 and Z. rouxii 48,49 .While Siva kumar et al 45 observed that S. rimosus prefers the malt extract for higher L-Glutaminase production. Apart from complex nitrogen sources, inorganic nitrogen compounds such as ammonium sulphate and urea enhanced the enzyme production in Achromobacteraceae and Providencia sp.…”

Microbial Amidases and their Industrial Applications: A Review

“…Treatment of raw products with asparaginase before thermal treatment resulted in a 96-99 % drop of acrylamide formation [71,72]. Therefore, it is not surprising that L-glutaminase is researched as a catalyst for the production of fermented condiments such as Japanese soy sauce [73].…”