Polysaccharide production by an Agrobacterium sp. curdlan overproducer mutant on a grain fermentation coproduct

Abstract

The aim of this study was to determine if a curdlan overproducer Agrobacterium sp. mutant strain was able to produce higher levels of the polysaccharide than its parent strain from the grain processing coproduct condensed corn distillers solubles. The curdlan overproducer mutant was grown in a medium containing 400 g L-1 solubles for 120 h with curdlan and biomass levels being determined daily. The results with significant value were that curdlan could be produced at a higher level by the mutant strain on condensed corn distillers solubles as a source of carbon and nitrogen alone or supplemented with 3% corn syrup in less fermentation time than its parent strain. Other results with significant value was that the highest curdlan concentration was produced by the mutant strain (5.39 g L-1) or parent strain (4.97 g L-1) on condensed corn distillers solubles alone at 120 h. When the solubles were supplemented with corn syrup, the highest curdlan concentration was also produced by the mutant strain (12.34 g L-1) or parent strain (10.51 g L-1) at 120 h. Biomass production by ATCC 31749 (2.67 g L-1) was slightly higher than the mutant strain (2.50 g L-1) at 120 h of growth on condensed corn distillers solubles alone. When the solubles were supplemented with corn syrup, biomass production by the parent strain (4.25 g L-1) was much higher than the mutant strain (2.43 g L-1) at 120 h. The conclusion of this study with beneficial value is that the commercially valuable gum curdlan could be produced from a low value coproduct corn distillers solubles. © 2012 Academic Journals Inc.