title: Glutaminase-producing Meyerozyma (Pichia) guilliermondii isolated from Thai soy sauce fermentation.
abstract: In this study, 34 yeast isolates were obtained from koji and moromi samples of Thai soy sauce fermentation. However, the most interesting yeast strain was isolated from the enriched 2 month-old (M2) moromi sample and identified as Meyerozyma (Pichia) guilliermondii EM2Y61. This strain is a salt-tolerant yeast that could tolerate up to 20% (w/v) NaCl and produce extracellular and cell-bound glutaminases. Interestingly, its glutaminases were more active in 18% (w/v) NaCl which is a salt concentration in moromi. The extracellular glutaminase's activity was found to be much higher than that of cell-bound glutaminase. The highest specific activity and stability of the extracellular glutaminase were found in 18% (w/v) NaCl at pH4.5 and 37°C. A challenge test by adding partially-purified extracellular glutaminase from M. guilliermondii EM2Y61 into 1 month-old (M1) moromi sample showed an increased conversion of L-glutamine to L-glutamic acid. This is the first report of glutaminase producing M. guilliermondii isolated from the moromi of Thai soy sauce fermentation. The results suggested the potential application of M. guilliermondii EM2Y61 as starter yeast culture to increase l-glutamic acid during soy sauce fermentation.
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand.
authors.forename: Phichayaphorn
authors.initials: P
authors.lastname: Aryuman
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand.
authors.forename: Sittiwat
authors.initials: S
authors.lastname: Lertsiri
authors.affiliation: National Center for Genetic Engineering and Biotechnology (BIOTEC), Thailand Science Park, Phaholyothin Rd., Khlong Nueng, Khlong Luang, Pathumthani 12120, Thailand.
authors.forename: Wonnop
authors.initials: W
authors.lastname: Visessanguan
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand.
authors.forename: Nuttawee
authors.initials: N
authors.lastname: Niamsiri
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand.
authors.forename: Amaret
authors.initials: A
authors.lastname: Bhumiratana
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand. Electronic address: apinya.ass@mahidol.ac.th.
authors.forename: Apinya
authors.initials: A
authors.lastname: Assavanig
mesh_terms: D004789:Enzyme Activation / Q000187:drug effects; D005285:Fermentation; D018698:Glutamic Acid / Q000378:metabolism; D005972:Glutaminase / Q000378:metabolism; D010843:Pichia / Q000187:drug effects / Q000201:enzymology* / Q000302:isolation & purification*; D012965:Sodium Chloride / Q000494:pharmacology; D045730:Soy Foods / Q000382:microbiology*
chemical_list: D018698:Glutamic Acid; D012965:Sodium Chloride; D005972:Glutaminase
keywords: Glutaminase; Meyerozyma (Pichia) guilliermondii; Moromi; Salt-tolerant yeast; Soy sauce