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The rapid rise of resistance causes existing antibiotics to become dysfunctional. Therefore, search for new antimicrobial active ingredients has increased in recent years. In this study, flower extracts of Castanea sativa were examined for antimicrobial and anti-quorum sensing aspects. The antimicrobial properties of methanol, ethyl acetate, ethanol and hexane extracts of C. sativa against some gram-positive and gram-negative bacterial species, as well as yeasts (Candida albicans and Candida parapsilosis) were investigated by the agar well diffusion method. The minimum inhibition concentration (MIC) and minimum bactericidal concentrations (MBC) of C. sativa extracts were also determined. Chromobacterium violaceum ATCC 12472, C. violaceum 35352, C. violaceum VIR07 and C. violaceum CV026 indicator strains were used for determination of the quorum sensing inhibitions, and the Pseudomonas aeruginosa PAO1 strain was used for the swarming tests. Additionally, biofilm inhibition was detected by the spectrophotometric method using the P. aeruginosa PAO1 strain. Methanol, ethanol and ethyl acetate extracts of C. sativa was found to have high antibacterial and antifungal effects, while the methanol extract also had anti-quorum sensing, anti- swarming and biofilm inhibition effects, but no activity was found in the n- hexane extract. To the best of our knowledge this is the first report revealed that methanol extract obtained from C. sativa flowers induced anti-quorum sensing activities mainly inhibited the violacein production, swarming and biofilm formation. The present investigation provided evidence that the C. sativa flower extract maybe a potential source of antimicrobial agents. Therefore, much attention should be paid to C. sativa flower content, which could be used with high efficacy against microorganisms.

Rapidly increasing industrialization and technological developments cause hazardous wastes to spread to the environment at a high rate. When heavy metal accumulation in water and soil reaches undesirable levels, it causes universal health problems to occur and threaten societies. For this reason, there is a need for alternative biological control methods and biological resources to prevent heavy metal pollution, especially in soils used for agriculture. In our study, three bacterial (112O1, 5O1, 5O8) strains isolated from the rhizoid region of the orchid plant (Dactyloriza urvilleana) were characterized by conventional and molecular methods (nuclear 16S rDNA intragenic gene regions sequence analysis). In order to characterize the isolates, primarily macroscopic, microscopic, some biochemical and physical properties were determined. The usability of the strains screened for their general properties as bioremediation strains, in the prevention of high copper accumulation in agricultural soils was investigated. For this purpose, especially metal tolerance levels and plant growth promoting properties were examined in the laboratory environment. With traditional and molecular studies, two of the strains were defined as species level (Bacillus mycoides, B. popilliae) and one at genus level. It was determined that all strains were tolerant to the tested metal salts (Fe, Zn, Cu, Pb and Ag salts in the 1-10 mM range) except 5O1 Ag, and 112O1 Zn salt. The highest copper tolerance was observed in 5O1, 112O1 and 5O8 strains, respectively. The strains were determined that the copper MIC values were 12.5-25 and the MBC value was 50 mM / L. It gave good results in terms of properties such as IAA, ACC Deaminase, phosphate solubility that stimulate plant growth. When the germination success of corn seeds in the presence of copper was examined, it was concluded that positive results were obtained, there was no significant difference between strains and therefore strains could be used in copper bioremediation.