The objective of this study was to evaluate the effects of mineral fertilizer (NP) and thirty-five N2-fixing and/or P-solubilizing and different carbon sources utilizing-bacterial strains (7 isolates each of Bacillıs megaterium, Bacillus subtilis, Paenibacillus polymyxa, Pseudomonas putida and Pseudomonas fluorescens) isolated from the acidic rhizospheric soil of native tea, grapevine and wild red raspberries, as bio-fertilizers on growth, yield and quality characteristics of the plant, on chlorophyll content, on macroand micronutrient concentrations, on essential oil content and on major component of the essential of Turkish oregano (Origanum onites L.). The isolates were identified based on whole-cell fatty acid methyl ester (FAMEs) analysis using the MIDI system and BIOLOG assays. The study contains both applications NP-fertilizer and a control application without inoculation of bacteria and fertilizer application. This study was carried out in Greenhouse at Atatürk University, Faculty of Agriculture and Department of Agronomy in 2011-2012 growing season. As an average of years the treatments showed that the plant has 35.3-48.5 cm of length, 34.29-48.30 cm of canopy diameter, 36.56-47.19 SPAD units of chlorophyll concentration, 41.88-74.64 g/plant of green herb yield, 11.52-15.52 g/plant of drug herb yield, 6.53-12.18 g/plant of drug leaf yield and 1.85-2.78% of essential oil content rate. Increasing carbon source utilization rates significantly increased plant height, canopy diameter, green herb, drug herb and drug leaf yield. The main components of the oil were carvacrol (58.19-70.08%), followed by thymol (17.85-26.27%), linalool (1.64-8.13%), borneol (1.36-2.39%) and p-cymene (0.37-3.21%) which were the most abundant components. In addition, with PGPR inoculation, macronutrient concentrations (N, P and K,) of oregano leaves increased, main component of the essential oil also changed. In terms of growth, yield and quality criteria of Turkish oregano, in particular, the most effective N2-fixing and P-solubilizing strains P. fluorescens (8/2, 58/3, 9/7, 53/6 and 51/2), B. subtilis (52/1, 6/3 and R 3/3), B. megaterium (21/3, K5E and 35/6), P. polymyxa (R2/2), and P. putida (55/2, 3/10 and 53/5) may be used instead of mineral fertilizer as bio-fertilizers in sustainable organic oregano cultivation.
