Kefir; is a fermented milk product which is produced by granules containing a wide variety of microorganisms such as lactic acid bacteria, acetic acid bacteria and yeasts. It is traditionally consumed in many countries. It has been shown in many studies that the polysaccharide structure surrounding the granules which is composed mainly of kefiran molecule has antimicrobial effect against various pathogens as well as many health promoting effects. In this study, 24 h fermented kefir was used with two types of kefir granules for production of kefiran extract. One of them is being sold commercially and the other was collected from private households in a different region of Turkey. Kefiran extraction was carried out from matured kefir granules using three different temperatures, 80°C, 90°C and 100°C. Also, the protein contents of the extracted solutions were determined by Bradford method. Protein content of the extract solutions obtained were measured as 0.001 g/ml. The antibacterial effect of 0.05, 0.1, 1 and 2 mg of this extract against several plant pathogenic bacterial strains belonging to genus Pseudomonas, Xanthomonas, Erwinia ve Clavibacter was investigated in vitro for the first time. For this purpose, two methods, disc diffusion method and spreading method were used. The AN and SD kefir supernatants used as the positive controls in the experiments showed an average of 13-17 mm and 10-14 mm inhibition zones on the isolates, respectively, but the antibacterial effect of kefiran extracts was not observed.

In this study, antibacterial effects of semi-parasitic plant common mistletoe (Viscum album L.), collected from different woody host, extracts on the tomato bacterial cancer and wilt disease agent Clavibacter michiganensis subsp. michiganensis, pepper and tomato bacterial leaf spot disease agent Xanthomonas axonopodis pv. vesicatoria and tomato bacterial leaf spot disease agent Pseudomonas syringae pv.tomato were determined. The common mistletoe collected from pine, pear, acacia and mahaleb trees. The leaves and stems water extracts of common mistletoe were added to Nutrinet agar medium before autoclaving at the final concentrations of 1%, 2.5%, 5% and 10%. The bacterial concentration was adjusted to 108 cfu/ml with spectrophotometer to within an 0.2 at 600 nm. Then, 100 µl of bacterial inoculums were spread over the extracts amended media plates. As a control group, pathogens were plated on the unamended media. The study was established in 3 repetitions and repeated 2 times. At the end of the incubation period, bacteria growing on all treated petri dishes were collected and their density was measured in a spectrophotometer. Based on the results of the study, 1% and 2.5% concentration of the extracts obtained from leaves and stems of common mistletoe collected from different trees were not effective on the bacteria tested, while 5% and 10% concentration of them inhibited the bacterial growth completely (100%). Also, it was observed that there wasn’t difference on the pathogens on the basis of the host where mistletoe was collected. According to the results of this study conducted under in vitro conditions, in vivo studies should be carried out with the common mistletoe extract, which is effective on the bacterial pathogens.