WATER-FLOW INDUCED TRANSPORT OF PSEUDOMONAS-FLUORESCENS CELLS THROUGHSOIL COLUMNS AS AFFECTED BY INOCULANT TREATMENT

Water flow induced transport of Pseudomonas fluorescens cells through soil columns was measured as affected by the inoculant treatment. Bact erial cells were introduced into the topsoil of columns, either encaps ulated in alginate beads of different types or mixed with bentonite cl ay in concentrations ranging from 0.5 to 5.0% (w/v). Survival of bacte rial cells was improved with the use of alginate or bentonite. Transpo rt, as determined by destructive sampling of the columns, was reduced with the use of alginate encapsulation. Drying of the beads had no inf luence on transport. The presence of bentonite in the topsoil, either pre-mixed through the soil, or applied as a slurry together with the b acteria, also reduced transport, except when 0.5% was pre-mixed throug h the soil. P. fluorescens cells encapsulated in alginate beads prepar ed with water and supplemented with skim milk powder and bentonite sho wed the best survival during the time of the experiment and the most r educed transport compared to the control. Therefore, cells encapsulate d in this way are suitable, due to their optimal survival and reduced spread, for use in a field experiment with genetically manipulated bac teria.