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Efficiency of modified skimmed milk base media to achieve high exopolysaccharide/cell ratios by Lactobacillus delbrueckii subsp. bulgaricus SZ2 in optimised conditions defined by the response surface methodology
Author(s) -
Abdi Reihaneh,
SheikhZeinoddin Mahmoud,
SoleimanianZad Sabihe
Publication year - 2012
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.2011.02906.x
Subject(s) - skimmed milk , food science , response surface methodology , sucrose , yeast extract , lactobacillus , chemistry , lactobacillus delbrueckii subsp. bulgaricus , fermentation , lactobacillaceae , chromatography
Summary Exopolysaccharide (EPS) production by Lactobacillus delbrueckii subsp. bulgaricus SZ2 was optimised in modified MRS (M‐MRS) using the response surface methodology (RSM). Maximum EPS production was 74.3 ± 2 mg/L, and the optimised values of the three variables predicted for maximum EPS production included a temperature of 38.7 °C, Bacto‐casitone and glucose concentrations of 24.5 and 29.6 g/L, respectively. To compare EPS production in MRS and skimmed milk (SM), the kinetics of EPS formation and growth were monitored in M‐MRS, SM, skimmed milk plus 2% additional sucrose (Suc‐SM) and skimmed milk containing Bacto‐casitone (20 g/L) and yeast nitrogen base (5 g/L) (BY‐SM). EPS production in all the media tested seemed to be growth‐related. The EPS/cell ratios were determined to be 3.12 × 10 −10 , 1.43 × 10 −10 , 4.42 × 10 −11 and 3.16 × 10 −11 mg/cell, in Suc‐SM, SM, M‐MRS and BY‐SM, respectively, clearly indicating the greater effect of C/N ratio when cell behaviour in EPS production is considered.