Marcia Mikolajczak

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Glycosyl transferases which recognize identical substrates (nucleotide-sugars and lipid-linked carbohydrates) can substitute for one another in bacterial polysaccharide biosynthesis, even if the enzymes originate in different genera of bacteria. This substitution can be used to identify the substrate specificities of uncharacterized transferase genes. The(More)
Several structurally related capsular polysaccharides that are secreted by members of the genus Sphingomonas are being developed as aqueous rheological control agents for diverse industrial and food applications. They include gellan (S-60), welan (S-130), rhamsan (S-194), S-657, S-88, S-198, S-7, and NW-11. We refer to these polysaccharides as sphingans,(More)
Certain bacteria of the Sphingomonas genus secrete structurally related capsular polysaccharides. Due to their unique properties, three (gellan, welan and rhamsan) are produced commercially by submerged fermentation and are used as modifiers of aqueous rheology and as gelling agents. However, conversion of glucose into these polysaccharides is relatively(More)
Four representative species from three genera of gram-negative bacteria that secrete exopolysaccharides acquired resistance to the antibiotic bacitracin by stopping synthesis of the exopolysaccharide. Xanthomonas campestris, Sphingomonas strains S-88 and NW11, and Escherichia coli K-12 secrete xanthan gum, sphingans S-88 and NW11, and colanic acid,(More)
Twelve genes coding for assembly, acetylation, pyruvylation, polymerization, and secretion of the polysaccharide xanthan gum are clustered together on the chromosome of the bacterium Xanthomonas campestris. These genes (gumBCDEFGHIJKLM) are sufficient for synthesis of xanthan gum when placed in bacteria from a different genus, Sphingomonas. The(More)
A sporeforming gram-positive aerobic bacterium was isolated from soil and shown to secrete an endoglycanase that cleaves the tetrasaccharide backbone structure of specific members within the gellan family of related bacterial exopolysaccharides. We refer to these polysaccharides as sphingans. The structures of the sphingans differ by the type and position(More)
Two classes of mutants ofXanthomonas campestris B1459 were isolated that accumulate more xanthan gum than the parental wild-type in culture broths of shake flask cultures and both batch and fed-batch fermentations. The first mutant class was resistant to the antibiotic rifampicin and accumulated, on average, about 20% more xanthan gum than wild-type. The(More)
The binding of naphthyridinomycin (NAP) to deoxyribonucleic acid was investigated using radioisotope labeled antibiotic. Dithiothreitol (DTT) enhances complex formation in a concentration dependent fashion but was found to be slightly inhibitory at concentrations above 10 mM. [C3H3]-NAP-DNA complexes, formed in the presence or absence of reducing reagents,(More)
The characteristics of the in vitro interaction of cyanonaphthyridinomycin (CYANO) with DNA are described. Unlike naphthyridinomycin (NAP), CYANO is extremely dependent on reductive activation with dithiothreitol (DTT) to bind DNA. The reaction of CYANO with DNA is kinetically slower than that observed for NAP and is still linear after six hours incubation(More)
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