eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2016-12-22 13 4 1871 1878 10.13005/bbra/2342 16723 article Prapassorn Bussaman 1 Paweena Rattanasena 2 Biocontrol Research Unit, Department of Biotechnology, Faculty of Technology, Mahasarakham University, Maha Sarakham 44150, Thailand. Community Public Health Sub-Department, Department of Applied Sciences, Faculty of Science and Technology, Rajabhat Phranakhon Si Ayutthaya University, Ayutthaya 13000, Thailand. Xenorhabdus bacteria isolated from entomopathogenic nematodes have been found to produce several antimicrobial agents for inhibiting pathogenic bacteria. In this study, X. stockiae strains PB09, SS7 and UV58 (UV-mutant of PB09) were evaluated for antibacterial activities against cow mastitis-causing isolates of Bacillus subtilis, Staphylococcus aureus, Staphylococcus intermedius, Streptococcus agalactiae, Enterococcus faecalis, Klebsiella pneumoniae, and Escherichia coli. The paper disc diffusion showed that cell-free supernatants of all X. stockiae strains cultivated for 48, 72 and 96 h had anti-mastitis activities, but 72- and 96-h supernatants were more effective and tended to inhibit gram-positive bacteria. The maximal activities were found when X. stockiae PB09 were evaluated against S. agalactiae (12.00±2.16 mm), X. stockiae SS7 and X. stockiae UV58 against S. aureus (11.75±1.71 mm and 12.50±0.58 mm, respectively). The overlay assay also showed that X. stockiae colonies were more likely to inhibit gram-positive bacteria. Also, live X. stockiae UV58 colonies were more effective than X. stockiae PB09 and X. stockiae SS7 colonies for suppressing S. intermedius, S. agalactiae and E. coli (31.33±1.53, 22.67±1.53, 18.33±0.58 mm, respectively). This study may suggest that X. stockiae can be used for future effective suppression of mastitis infection in dairy cows. https://www.biotech-asia.org/vol13no4/additional-property-of-xenorhabdus-stockiae-for-inhibiting-cow-mastitis-causing-bacteria/ Xenorhabdus stockiae; cow mastitis bacteria; paper disc diffusion assay; overlay assay