Decolorization of Reactive Brilliant Blue KN-R by Immobilized Cells of Rhodocyclus gelatinosus

Reactive Brilliant Blue KN-R is a typical kind of anthraquinone dye and in common use in textile, dyeing, and printing industries in China, which is difficult to degrade because of its conjugated structure. The decolorization of KN-R was investigated using Ca-alginate immobilized cells of Rhodocyclus gelatinosus XL-1 under anaerobic conditions. For KN-R decolorization by immobilized cells, the suitable pH is 5-8 and the suitable temperature is 25-40 °C. Immobilized cells could decolorize KN-R by co-metabolism in the presence of peptone, and the enhancement of peptone concentration was beneficial for anaerobic decolorization. Metal ions affected the metabolic activity of immobilized cells of R. gelatinosus XL-1. The activity of KN-R decolorization was appreciably increased by Mg2+ and Cr3+, but severely inhibited by Cu2+ and Ag+. The maximum absorption peak in visible spectrum shifted from 595 to 453 nm during KN-R decolorization, indicating the formation of the intermediate product.

Chemical composition of Rhodocyclus gelatinosus biomass produced in poultry slaughterhouse wastewater

Rhodocyclus gelatinosus R1 grew photoautotrophically in poultry slaughterhouse wastewater inside glass columns (90x670 mm) during 7 days at 31 ± 4ºC, under anaerobiosis and lightness supplied by daylight plus 3 (100W) incandescent and 4 (40W) fluorescent lamps. The culture was centrifuged (4,500xg/20 min) and lyophilized to originate a bacterial biomass with 7.1% moisture content. Chemical composition investigation showed 67.6% crude protein, 27.6% total carbohydrate, 0.6% lipids and 4.2% ash (dry weight). Amino acid composition of the biomass was similar to others described in the literature for Rhodocyclus gelatinosus and for other photosynthetic bacteria. Effluent COD removal after cultivation and elimination of the biomass was around 90%. The valuable chemical composition of Rhodocyclus gelatinosus R1 biomass and the high content in essential amino acids signs for the potential use of the product in poultry feed.

Isolation of Rhodocyclus gelatinosus from poultry slaughterhouse wastewater

Four cultures of photosynthetic bacteria isolated from poultry slaughterhouse wastewater were identified as Rhodocyclus gelatinosus based on the following properties: reddish color of cultures in synthetic medium, presence of motility, slightly curved Gram-negative rods morphology, gelatin liquefying activity, utilization of citrate as carbon source and production of bacteriochlorophyl a and carotenoids of the spirilloxanthin alternative series. R. gelatinosus may represent a source of nutrients and pigments with application in poultry feed.