Quantitative Determination of the Spatial Distribution of Nitrosomonas europaea and Nitrobacter agilis Cells Immobilized in κ-Carrageenan Gel Beads by a Specific Fluorescent-Antibody Labelling Technique

Abstract

A novel technique, combining labelling and stereological methods, for the determination of spatial distribution of two microorganisms in a biofilm is presented. Cells ofNitrosomonas europaea (ATCC 19718) and Nitrobacter agilis (ATCC 14123) were homogeneously distributed in a k-carrageenan gel during immobilization and allowed to grow out to colonies. The gel beads were sliced in thin cross sections after fixation and embedding. A two-step labelling method resulted in green fluorescent colonies of either N. europaea or N. agilis in the respective cross sections. The positions and surface areas of the colonies of each species were determined, and from that a biomass volume distribution for N. europaea and N. agilis in K-carrageenan gel beads was estimated. This technique will be useful for the validation of biofilm models, which predict such biomass distributions.

Modelling the effect of oxygen concentration on nitrite accumulation in a biofilm airlift suspension reactor

“…It appears that the proposed model fits very well the measured data, despite the assumptions made. A better validation of the model would be possible if the spatial distribution of two microorganisms were determined with available techniques (Hunik et al, 1993).…”

Agar-entrapped bacteria as an in vitro model of biofilms and their susceptibility to antibiotics

“…These models vary in complexity from growth on solid nutrient media to culture in complex biofermentors. Among them, the artificial entrapment of microorganisms in polysaccharide gel provides a suitable model system which has been up to now essentially used in the environmental field [6,7].…”

Nitrogen removal by tubular gel containing Nitrosomonas europaea and Paracoccus denitrificans

“…The tubular gel was sampled at the start, the fourth day, and the seventh day of treatment. These gels were fixed, dehydrated, and embedded in polyethylene glycol by the procedure described by Hunik et al (6). The sections were labeled with rabbit anti-N. europaeafluorescein isothiocyanate and rabbit anti-P. denitrificansfluorescein isothiocyanate for 45 min at 52ЊC in the dark.…”