Dear colleagues,
Recently I anlayzed soil microbial C utilization pattern in two soils using BIOLOG Ecoplate. One soil is a climax forest soil in southern China with high substrate content (C, N, P etc) and soil microbial biomass and activity and a agricultural soil with relatively, and the other is a agricultural soil with relatively low substrate content and microbial biomass and activity. They were analyzed in the same procedure and the microplates have been incubated at 25 oC for 14 days. However, we found the results are very strange because AWCD of the foreset soil is very low (less than 0.3) while that of the agricultural soil is around 1.1. As I know, high AWCD indicates high microbial C utilization capacity but it seems wrong from our results. Is anybody familiar with the BIOLOG technique and could provide helps? Thank you very much.
Hui
Dear Hui,
The development of colour in Biolog microplates depend on inoculation density. Also, your forest soil may be dominated by fungi?
Regards,
Naoise
@Naoise Thank you for your reply, Naoise. According to our investigations, this forest soil is actually dominated by bacteria over fungi. The initial amount of bacterial should be more in this forest soil than in the agricultural soil, but we do not know whether there are more culturable bacteria in this forest soil. I feel something depressed color development of BIOLOG plates for this soil but I don't know what it was. I read some published BIOLOG papers and found the AWCD of our forest soil seems too low relative to previous reports for forest soils.
@Karolina Yes it is longer for recommended investigation duration of BIOLOG analysis. We can just use the results obtained in the first 7-10 days as previous studies did, but it is not bad to see the results for a longer incubation. For each sample, we mixed 1 gram of fresh soils with 1000 mL of 0.85% NaCl solution, left the vial standing and then 150 uL of the supernants were pipetted into a BIOLOG ECO plate for incubation.
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