Objective: We identified a new isolated naringinase-producing yeast strain named as Jmudeb008, and analyzed its naringinase-producing ability cultured with different composition and concentration of carbon sources.
Methods: The strain was identified based on conventional phenotypic methods and sequences of the D1/D2 region of 26S rDNA and 5.8S-ITS. Media with different composition and concentration of carbon sources were used in shaking culture of Jmudeb008. The activity of naringinase was evaluated by analyzing the concentration of naringin, naringenin and glucose during 48 h culture.
Results: The Jmudeb008's sequences of the D1/D2 region of 26S rDNA and 5.8S-ITS were 99% identical with Cryptococcus laurentii. Further glucose fermentation test, urease test, DBB (diazotization based blue) test and nitrate reduction test were coincided with results of DNA sequencing. Therefore, Jmudeb008 was identified as Cryptococcus laurentii. When Jmudeb008 was cultured in the medium with naringin as the only carbon source, it could synthesize naringinase. However, when glucose was available, the synthesis of naringinase was repressed.
Conclusion: The new isolated naringinase-producing yeast strain JmudebO08 was identified as Cryptococcus laurentii. The glucose in medium repressed naringinase expression.