نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری گروه علوم خاک دانشگاه آزاد اسلامی اصفهان واحد خوراسگان
2 دانشیار میکروب شناسی گروه علوم پایه پزشکی دانشگاه آزاد اسلامی اصفهان واحد خوراسگان
3 استاد گروه علوم خاک دانشگاه آزاد اسلامی اصفهان واحد خوراسگان
4 استادیار گروه علوم خاک دانشگاه آزاد اسلامی اصفهان واحد خوراسگان
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Exopolysaccharides secreted by bacteria has an important role in bacterial resistance against stresses such as salinity. This study aimed to isolate and identify halotolerant bacteria with the most exopolysaccharide production potential of the soil and evaluate the production of exopolysaccharides in different salt concentrations. Soil samples were spread on nutrient agar ± %5 NaCl then among the salt tolerant colonies, the most tolerable salt concentration (MTC) of mucoid ones was isolated and the EPS production in the presence of (5%) salt concentrations was assayed. The nature of exopolysaccharide produced by superior strain was identified with FTIR Spectrometer and the exopolysaccharides production in higher concentrations of salt were determined by anthrone-sulfuric acid method. In the infrared spectrum of exopolysaccharide, the absorption peaks were attributed to the presence of carbohydrate compounds such as β-glucans and also to alcohol groups, phenols, carboxylic acids, carbonyl and alkyne. The exopolysaccharide production was significantly (Pvalue < 0.05) increased by increasing salt stress. According to the results, the strain no-7 with growth potential on the 25% salt and producing exopolysaccharides (0.168 g /L) in 24 hours was selected as a superior strain and according to 16S rDNA gene sequencing was identified as Citrobacter freundii ATHM38 and submitted to GenBank under the accession number KX553903.
کلیدواژهها [English]