Isolation and identification of bacteria with pgpr characteristics isolated from solanaceae family member plants

This study aimed to investigate the effects of bacteria with PGPR (Plant Growth Promoting Rhizobacteria) properties isolated from the Solanaceae family on lettuce (Lactuca sativa L.) plants. Bacteria isolated from the rhizosphere regions of plants belonging to the Solanaceae family, collected from different locations within the Çukurova University campus, were identified using the MALDI- TOF MS method. Among these isolates, the species K. cowanii was selected for experimental studies. Six different groups were formed in the research: 1. control group, 2. 20-20-20 NPK fertilizer group, 3. P+K+Bacteria application group, 4. fertilizer-free immersion method group, 5. 300 mL bacteria application group, and 6. 600 mL bacteria application group. Throughout the study, parameters such as SPAD, chlorophyll, sugar (fructose, glucose, sucrose), total phenol, antioxidant activity, organic acids (citric acid, D-malic acid, succinic acid), root length, total weight, and leaf number were examined. The findings revealed that the application of K. cowanii with PGPR properties had positive effects on the growth and metabolic activities of lettuce plants. Especially the application with a 300 mL dose provided the highest values in parameters such as root length, total weight, SPAD value, and sugar content compared to the control group and commercial fertilizer applications (p<0.05). In organic acid analyses, it was determined that D-malic acid and succinic acid contents significantly increased in the bacterial groups. Moreover, the highest levels of total phenol content and antioxidant activity were reached in the 600 mL bacterial group. In conclusion, this study clearly demonstrated the growth-promoting effects of the species K. cowanii on lettuce plants and showed the potential of this bacterium to be used as a biofertilizer in agricultural applications. In this context, the effectiveness of PGPR bacteria can be evaluated more comprehensively with further research to be conducted on different plant species and field conditions.