A PARTIAL CHLOROFORM-FUMIGATION TECHNIQUE TO CHARACTERIZE THE SPATIALLOCATION OF BACTERIA INTRODUCED INTO SOIL

Bioluminescence-marked cells of Pseudomonas fluorescens were inoculate d into soil by introduction into pores of two different size classes ( <6 and 30-60 mum neck diameter). Partial chloroform fumigation resulte d in a differential killing of cells depending on the placement of the inoculum within the soil pore network and on the period of fumigation . Reduced survival was associated with increasing periods (30 - 120 mi n) of fumigation, and with inoculum placement into larger rather than smaller pores. Comparison of the effects of partial fumigation on cell s introduced into four soils of contrasting pore-size distribution hig hlighted the need to calibrate the method on the basis of air/water-fi lled pore space and chloroform diffusion dynamics for different soil t ypes. It is proposed that partial fumigation facilitates spatial chara cterisation of the distribution of bacterial cells introduced into soi ls.