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Folia Microbiol (2014) 59:916 DOI 10.1007/s12223-013-0258-2
Trissucrose buffer system: a new specially designed medium for extracellular invertase production by immobilizedcells of isolated yeast Cryptococcus laurentii MT-61
Mehmet Nuri Aydogan & Mesut Taskin & Ozden Canli &
Nazli Pinar Arslan & Serkan Ortucu
Received: 3 January 2012 /Accepted: 12 May 2013 /Published online: 31 May 2013 # Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i. 2013
Abstract The aims of the present study were to isolate new yeasts with high extracellular (exo) invertase activity and to investigate the usability of buffer systems as invertase production media by immobilized yeast cells. Among 70 yeast isolates, Cryptococcus laurentii MT-61 had the highest exoinvertase activity. Immobilization of yeast cells was performed using sodium alginate. Higher exo-invertase activity for immobilized cells was achieved in trissucrose buffer system (TSBS) compared to sodium acetate buffer system and potassium phosphate buffer system. TSBS was prepared by dissolving 30 g of sucrose in 1 L of tris buffer solution. The optimum pH, temperature, and incubation time for invertase production with immobilized cells were determined as 8.0, 35 C and 36 h in TSBS, respectively. Under optimized conditions, maximum exo-invertase activity was found to be 28.4 U/mL in sterile and nonsterile TSBS. Immobilized cells could be reused in 14 and 12 successive cycles in sterile and nonsterile TSBS without any loss in the maximum invertase activity, respectively.
This is the first report which showed that immobilized microbial cells could be used as a biocatalyst for exoinvertase production in buffer system. As an additional contribution, a new yeast strain with high invertase activity was isolated.
Introduction
Invertase is an enzyme (-D-fructofuranoside fructohydrolase, -fructofuranosidase, sucrase, invertin, saccharase; EC3.2.1.26) used to produce noncrystallisable sugar syrup from sucrose. The hydrolysis of sucrose, which yields glucose and fructose at equimolar concentrations known as invert syrup, is catalyzed by invertase enzyme. The invert syrup is widely used in food and beverage industries as a humectant in the manufacture of soft-centered candies and fondants, noncrystallizing creams, jams, artificial honey, and in confectionery industry to a lesser extent in the industrial production of liquid sugar (Kotwal and Shankar 2009; Safarik et al. 2009). Fermentative production of invertase has been performed with free or immobilized cells of fungi (yeasts and molds)...