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Welan gum is a microbial polysaccharide produced by Alcaligenes sp. CGMCC2428 that has d-glucose, d-glucuronic acid, d-glucose, and l-rhamnose as the main structural unit. The biosynthetic pathway of sugar nucleotides essential for producing welan gum in this strain was established in the following ways: (1) the detection of the presence of several intermediates and key enzymes; (2) the analysis of the response upon addition of precursors to the culture medium; (3) the correlation of the activities between several key enzymes with the yields of welan gum. With addition of 200-μM glucose-6-phosphate and fructose-6-phosphate, the production of welan gum was improved by 18%. The activities of phosphoglucomutase, phosphomannose isomerase, UDP-glucose pyrophosphorylase, and dTDP-glucose pyrophosphorylase, correlated well with the yields of welan gum. According to these findings, the biosynthetic pathway was proposed to involve the metabolism of glucose via two discrete systems. The first involves conversion of glucose to glucose-6-phosphate, with further reactions producing glucose-1-phosphate and fructose-6-phosphate, which are metabolized to the nucleotide sugar precursors of welan gum. The second system involves metabolism of glucose to synthesize the basic structural skeleton of the cell via central metabolic pathways, including the Entner–Doudoroff pathway, the pentose phosphate pathway, and the tricarboxylic acid cycle. [ABSTRACT FROM AUTHOR]

The strain Aspergillus fumigatus XC6 isolated from mildewing rice straw was evaluated for its ability to decolorize a dye industry effluent. The strain was capable of decolorizing dyes effluent over a pH range 3.0–8.0 with the dyes as sole carbon and nitrogen sources. The optimum pH was 3.0; however, supplemented with either appropriate nitrogen sources (0.2% NH4Cl or (NH4)2SO4 ) or carbon sources (1.0% sucrose or potato starch), the strain decolorized the effluent completely at the original pH of the dyes effluent. Therefore, A. fumigatus XC6 is an efficient strain for the decolorization of reactive textile dyes effluents, and it might be a practical alternative in dyeing wastewater treatment. [ABSTRACT FROM AUTHOR]