RESUMEN
The aim of this work was to compare three methods to determinate low concentrations of Paracoccus denitrificans encapsulated in polyvinyl alcohol pellets, which is important for evaluation and optimization of pellet production as well as for monitoring of biomass growth. Pellets with different and well-defined biomass concentrations were used for experiments. The following fast and simple methods were tested: (1) dissolution of polyvinyl alcohol in hot water followed by dry weight estimation, (2) dissolution of polyvinyl alcohol in hot water followed by optical density measurement, (3) and extraction and quantification of proteins. Dry weight estimation proved to be problematic as it was difficult to separate biomass from polymeric carrier. Optical density measurement showed good linearity of dependence of optical density on biomass content, but determined limits of detection and limits of quantification were not within the range necessary for intended application. The only tested method meeting the requirements for sensitivity was determination of protein concentration after protein extraction.
Asunto(s)
Carga Bacteriana/métodos , Células Inmovilizadas , Paracoccus denitrificans/aislamiento & purificación , Alcohol Polivinílico/químicaRESUMEN
The aim of this work was to compare denitrification activity of three types of encapsulated biomass containing pure culture of Paracoccus denitrificans or Pseudomonas fluorescens or mixed culture of psychrophilic denitrifiers cultivated at 5 °C from activated sludge. The experiments were held with synthetic wastewater containing 50 mg L(-1) N-NO(3)(-) under the temperature 15, 10, 8 and 5 °C. Specific denitrification rates related to the weight of pellets and to the protein content were calculated and the temperature coefficients describing the dependence of denitrification rate on the temperature were determined. Although the mixed culture showed the highest denitrification rate at the temperatures below 10 °C, using of pellets containing pure culture is recommended as the mixed culture has slow growth rate and its activity at temperatures above 10 °C is very low.