Isolation and Characterization of Soil Degrading Matter Bacteria from Mediterranean Area as Potential Biocontrol and Bioindicator Agents

Background: Bacteria are major components of soil environments with many of the enzymes needed to degrade organic matter and in particular plant cell walls. Besides the cell wall of fungal or any pathogen are mainly composed of chitin, glucans, mannans, and glycoproteins, this study aims to isolate organic matter degrading bacteria from soil and to evaluate their biocontrol potential against phytopathogenic microorganisms. Methods: The study area was in the Mediterranean area. Soil microorganisms were isolated on selective lignocellulosic medium and characterized by microbiological and enzymatic analyses (iodin solution test, beta-glucosidase and acetyl-N-glucosaminidase assay). Preliminary analyses were carried out to test their resistance to heavy metals and toluene. A set of bacteria was subjected to taxonomic analysis. Results: 150 strains were isolated from soil, 75 from Pollino massif and 75 from Sila plateau. In order to verify and compare the cellulolytic activity of the strains, a semi-quantitative analysis was obtained by culturing the microorganisms in medium containing carboxymethyl cellulose (CMC) and stained with iodine solution. Furthermore, isolated bacteria were tested for their resistance to heavy metals and toluene. From these 150, a set of 21 strains (6 belonging to Sila and 15 to Pollino), showed a high cellulolytic activity measured by iodin solution test. Quantitative beta-glucosidase and the acetyl-N-glucosaminidase enzyme activity were determined by spectrophotometric analyses. 21 strains were subjected to taxonomic analysis by sequencing of 16S rDNA gene and sequence homology were identified by Ribosomal Database. Conclusions: Within the OnFoods project (www.onfoods.it), 150 soil bacterial strains were isolated and characterized. A set of 21 strains, having high beta-glucosidase and chitinolytic activity, were identified and compared with literature data, suggesting they could be considered potential biocontrol agents against pathogenic microorganisms and ecological bioindicators.