Assessing soil biological characteristics: a comparison of bulk soil community DNA-, PLFA-, and Biolog (TM)-analyses

Soil microbiological analyses may serve as a means for assessing soil chara cteristics. Standard microbiological culture-techniques, however, leave ove r 90% of the microorganisms in the environment unaccounted for. Several mor e recently developed analytical techniques such as DNA, phospholipid fatty acid (PLFA), and community level substrate utilization (CLSU) fingerprints allow for more detailed analyses of soil microbial communities. We applied analyses of(l) community DNA with PCR and restriction fragment length polym orphism (RFLP), (2) community PLFAs with gas chromatography and mass spectr ometry, and (3) CLSU with Biolog (TM) gram-negative-plates. to evaluate the biological characteristics of three soils used in pesticide degradation st udies. Each of these methods analyzes a different aspect of soil microbial characteristics. A protocol was developed for the statistical comparison an d combination of the data from all the analyses, thus allowing for a polyph asic approach to biological soil characterization. We found that all three methods yielded highly reproducible results for each soil and allowed to di stinguish the soils based on the structures of specific gene- and PLFA-pool s as well as on CLSU fingerprints. Not all methods, however, revealed the s ame relative similarities of the three soils based on cluster analysis of t he biological characteristics. These results demonstrate the value of compa rative data analyses and indicate that biological soil characterization nee ds to be interpreted with caution if it is performed with one method only. (C) 2001 Elsevier Science Ltd. All rights reserved.