Browsing by Author "Willard, Kyle"
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- ItemDiverse exopolysaccharide producing bacteria isolated from milled sugarcane : implications for cane spoilage and sucrose yield(Public Library of Science, 2015) Hector, Stanton; Willard, Kyle; Bauer, Rolene; Mulako, Inonge; Slabbert, Etienne; Kossmann, Jens; George, Gavin M.Bacterial deterioration of sugarcane during harvesting and processing is correlated with significant loss of sucrose yield and the accumulation of bacterial polysaccharides. Dextran, a homoglucan produced by Leuconostoc mesenteroides, has been cited as the primary polysaccharide associated with sugarcane deterioration. A culture-based approach was used to isolate extracellular polysaccharide (EPS) producing bacterial strains from milled sugarcane stalks. Ribosomal RNA sequencing analysis grouped 25 isolates into 4 genera. This study identified 2 bacterial genera not previously associated with EPS production or sucrose degradation. All isolates produced polysaccharide when grown in the presence of sucrose. Monosaccharide analysis of purified polymers by Gas Chromatography revealed 17 EPSs consisting solely of glucose (homoglucans), while the remainder contained traces of mannose or fructose. Dextranase treatment of polysaccharides yielded full digestion profiles for only 11 extracts. Incomplete hydrolysis profiles of the remaining polysaccharides suggest the release of longer oligosaccharides which may interfere with sucrose crystal formation.
- ItemInvestigation of exopolysaccharide producing bacteria isolated(Stellenbosch : Stellenbosch University, 2012-12) Willard, Kyle; Kossmann, Jens; George, G. M.; Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics.ENGLISH ABSTRACT: The deterioration of harvested sugarcane as a result of bacterial growth causes major losses of sucrose and a build-up of exopolysaccharides (EPS). Polysaccharides present during production increase the massecuite viscosity, which negatively influences evaporation and crystallisation. In this study 38 culturable EPSproducing bacteria were isolated from milled sugarcane. Analysis of the EPS showed the ubiquitous presence of glucose, however, 14 polysaccharides also contained mannose, fructose or galactose. In vitro treatment using Chaetomium erraticum dextranase to evaluate is effectiveness indicated that 37 of the EPS were hydrolysed to some extent. There were 21 polysaccharides that were only partially digested. The capacity of the isolates to produce EPS on different sugars indicated a correlation between sucrose and polysaccharide formation in 37 isolates. The results indicate there are more species involved in EPS production than previously thought as well as the presence of non-dextran polysaccharides.