Antibacterial activity of Cuminum cyminum essential oil and Nisin on Streptococcus inaie in lab and fillets of rainbow trout

The antibacterial activity of different concentrations of Cuminum cyminum essential oil (0, 0.005, 0.015, 0.045, 0.135, 0.405%) and nisin (0, 0.125, 0.25, 0.75 μg/ml) was explored in lab and food model (fillets of rainbow trout) in controling Streptococcus iniae for 15 days at 8 ºC. The micro-dilution method was used to determine MIC and MBC for nisin and the essential oil, so used for food model. Results showed that MIC and MBC for essential oil and nisin were 0.015, 0.005% and 0.25, 0.125 μg/ml, respectively. For the duration of 15 days no statistical significance was recorded between the different concentrations of nisin and essential oil and control treatment. Results showed that the bacterial growth was delayed in different samples being treated with nisin and essential oil from 3 to 6 days for the given compounds and 6 days for nisin and essential oil in combination. The highest synergistic effect of nisin with essential oil was found in 0.135 and 0.405% concentrations for essential oil and 0.75 μg/ml for nisin at 8 ºC.