Trabajo presentado en el XIII International Scientific Agriculture Symposium AGROSYM 2022, celebrado en Sarajevo (Bosnia y Herzegovina), del 6 al 9 de octubre de 2022Exopolysaccharides are high molecular weight polymers composed of sugar subunits. Produced
exopolysaccharides by lactic acid bacteria (LAB) play a significant role in improvement of
organoleptic properties of fermented dairy products such as yogurt. Diversely, the probiotic
function of these bacteria and the prebiotic properties of their produced biopolymers promote
consumer¿s health. For this purpose, a traditional dairy product known as ¿Kishk¿ was selected.
143 strains of lactic acid bacteria were isolated from Iranian Kishk in Khorasan Province and
cultured in formulated MRS mediums with different sugars such as glucose, fructose, sucrose
and, lactose (40 g/L) and incubated in anaerobic conditions at 30 and 37°C for 48 hours. The
microscopic features of the isolates were assessed and the production of exopolysaccharide in the
culture medium was evaluated by disk and ruthenium red methods. The phenol-sulfuric and
weight method were used to quantify exopolysaccharide production. Results showed pH of
Kishk samples ranged from 3.60 to 4.08 and the average of total mesophilic count and LAB
count of samples were 6.50 and 5.89 log CFU/g, respectively. Analysis of data exhibited 79 out
of 143 lactic acid bacteria isolates were exopolysaccharide producer and 70% of them were
cocci. The average of maximum and minimum production by weight method were 2.61 g/L and
0.08 g/L, respectively. The average of highest and the lowest amount of exopolysaccharide by
phenol sulfuric method were measured 1.87 g/L and 0.06 g/L, respectively. This study indicates
the potential of exopolysaccharide production by Iranian native species from dairy products