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Alcaligenes faecalis LJ-3 is highly efficient in degrading various azo dyes (100 mg L-1). Almost 100 % degradation was observed within 16 h at the initial Acid Scarlet 3R concentrations of 1000 mg L-1 under the optimal conditions, which were: 1 g dextrin L-1, 3 g yeast extract L-1, NaCl ≤ 30 g L-1, pH 8.0 and 35-45 ºC. Azoreductase, laccase and NADH-DCIP (nicotinamide adenine dinucleotide-dichlorophenol indophenols) reductase were induced during the degradation of Acid Scarlet 3R. Kinetics study of degradation experiments approximated the first-order reaction. The maximum rate (Vmax) and substrate affinity constant (Ks) were found to be 115.90 mg L-1 h-1 and 1193.23 mg L-1, respectively, using Michaelis-Menten kinetics. This work provides new data characterizing Acid Scarlet 3R degradation by bacteria, as well as practical application potential in biological treatment of industrial effluents containing various azo dyes. [ABSTRACT FROM AUTHOR]

The effects of culture conditions and pH values on the exopolysaccharides (EPS) production by Hypsizygus marmoreus were investigated in this work. The results showed that the optimal carbon and nitrogen sources were glucose and yeast extract at concentrations of 30 g L-1 and 12.5 g L-1, respectively. In constant pH fermentation, high biomass concentration and the specific cell growth rate were achieved at pH 6.5, while high EPS concentration and the specific EPS production rate were obtained at pH 7.5, respectively. Based on kinetics analysis, a two-stage pH strategy was proposed in which pH was controlled at 6.5 to maintain high cell growth and glucose consumption in the first 48 h, and then shifted to 7.5 for increasing EPS production. The maximal EPS concentration reached 2.31 ± 0.07 g L-1 by applying this strategy. The EPS productivity (0.024 g L-1 h-1) increased 58.94 %, 172.7 % and 35.73 %, respectively, compared with that of the natural pH, and controlling pH at 6.5 and 7.5. [ABSTRACT FROM AUTHOR]