The soil microbial community research conducted in the field has focused on the genetic diversity of these organisms. In this study, we assessed the proteins expressed in soil microbial communities following the long-term application of mineral fertilizer (NPK) and organic manure (M) to paddy soil, indirect extraction method and separated via two-dimensional (2D) gel electrophoresis and identified using a matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) approach. We found that the number of cells in the primary soil in the M treatment was significantly greater than in the NPK and CK treatments. The numbers of cells extracted were consistent with the total cell numbers and the concentration of extracted proteins (CK < NPK < M). 303 and 306 protein spots being detected in the CK map and NPK map, respectively. Eleven spots of interest were identified in the 2D gels, including 8 different protein spots and 3 unique protein spots. Three common proteins involved in protein hydrolysis and glutamate synthesis and metabolism. Eight differentially expressed proteins involved in DNA replication, transcription, protein folding and energy metabolism, the processes of cofactor and vitamin metabolism, transcriptional regulation, recombination and xenobiotic compound biodegradation and metabolism. The long-term application of fertilization resulted in significant changes in the microbial community structure and function, and the long-term application of pig manure significantly increased the microbial biomass and the functional and structural diversity in the soil. It is very interesting to address the MS identification of intracellular proteins from microbial communities under different fertilizer treatments in a paddy soil.
Evaluation of functional diversity of soil microbial communities – a case study
