Curdlan biopolymer production by Agrobacterium radiobacter in a medium containing grape syrup

Subject Areas : Food Microbial Contamination

Anna Abdolshahi ¹ , Marzieh Mousavinasab ² , Leila Monjazebmarvdashti ³

1 - Food Safety Research Center (salt), Semnan University of Medical Sciences, Semnan, Iran
2 - Department of Food Science and Technology, College of Agriculture, Shiraz University, Shiraz, Iran
3 - Department of Food Science and Technology, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran

Received: 2017-10-10 Accepted : 2017-12-09 Published : 2018-10-23

Keywords: grape syrup, biopolymer, Agrobacterium radiobacter PTCC 1654, Curdlan,

Abstract :

Curdlan is water-insoluble and expensive polysaccharide that is made up of D-glucan monomers with b- (1→3) bonds. The properties of the gel created by the heat make Curdlan very important in the food industry. One of the main limiting factors for using Curdlan is its production cost. Agricultural waste can be used as a cheap substrate for its production. In this research, Curdlan production of was evaluated by Agrobacterium radiobacter PTCC 1654 in a culture medium different concentrations (5, 7.5 and 10%) of grape syrup and neat sucrose as carbon source. Based on the yield of Curdlan production, the optimum carbon source was determined. Moreover, the amount of produced Curdlan and biomass was measured. The polysaccharide sugar composition was evaluated by thin-layer chromatography technique. The pH change of the medium was also evaluated during the fermentation process. The results showed that the highest amount of polysaccharide was obtained in fermentation medium containing grape syrup with 7.5 Brix and after 144 hours. The pH of the fermentation medium decreased from about 7 to about 5.5 during the fermentation process. The results of thin-layer chromatography of polysaccharide showed that the glucose was the only monomer in the polymer's structure. In grape syrup medium Curdlan production in grape syrup was significantly higher than sucrose medium (p<0.05). Grape syrup is a cheap substrate widely available in Iran and has potential for Curdlan production.