Detection of mRNA of nprM in Bacillus megaterium ATCC 14581 grown in soil by whole-cell hybridization

Transcripts of nprM, the gene encoding the major extracellular protease of Bacillus megaterium ATCC 14581, were detected by both Northern blot analysis and whole-cell hybridization with digoxigenin-labeled in vitro ranscripts throughout the exponential growth phase and the early stationary phase. In cells of the late stationary phase, only low amounts of transcripts were observed with the two techniques. No transcripts could be detected in spores. In soil the presence of mRNA of nprM could be demonstrated by whole-cell hybridization in growing cells germinated from heat-activated spores until they reached the late transition state. No transcripts of nprM were detected in cells containing forespores. Both cells grown in pure culture and in soil had to be permeabilized with lysozyme to allow hybridization with digoxigeninlabeled probes. These results demonstrate the applicability of nucleic-acid probing techniques to localize microbial processes in soil. The approach described of detecting mRNA in fixed bacterial cells should facilitate in situ studies of gene transcription and specific activities in individual cells in heterogeneous environmental systems. © 1995 Springer-Verlag.