Abstract
Changes in the soil microbial community for studies of different novel communities can be promoted by different methodologies, among which soil autoclaving stands out as a quick and readily available tool. However, this procedure may also directly or indirectly alter nitrogen (N) and phosphorus (P) dynamics. The purposes of this study were as follows: (i) to characterize microbial activity after soil autoclaving through microbial (14)CO(2)-respiration; and (ii) to evaluate the effect of microbial manipulation and autoclaving on soil N and (33)P dynamics. For this, two sets of soil samples from two areas (forest and cultivated area) were used in the laboratory. Firstly, (14)C-glucose was added to the soils and after 24 h five soil microbiomes were generated: AS (autoclaved soil), and AS re-inoculated with serial dilutions (w/v) prepared by successive mixing of soil suspensions in sterile deionized water obtaining 10(-1), 10(-3), and 10(-6), which generated the treatments AS + 10(-1), AS + 10(-3), and AS + 10(-6); and the treatment NS (non-autoclaved control), all incubated for 28 d. (14)CO(2) emission was used to characterize microbial activity; additionally, N dynamics were assessed at the end of incubation. In a second assay, (33)P was applied to the soil before autoclaving and re-inoculation. Following further incubation (14 d), a (33)P chemical fractionation was performed. The following are based on the results: (i) (14)CO(2) emission: microbial activity in the autoclaved soil is null, but after a reinoculation of AS + 10(-1) and AS + 10(-3) soil dilution suspension, the (14)CO(2)-respiration is higher than in an NS. (ii) regarding the N dynamics, in autoclaved soils, the microbial levels increased N-NH(4)(+) concentration, with an evident increase in the AS + 10(-3) and AS + 10(-1), and a reduction in the N-NO(3)(-) concentration in comparison to the NS. For (33)P, the autoclaving procedure itself reduced the (33)P lability, regardless of the levels of microbial community reinoculated.