Research of the Photostimulation Effect on the Lactobacillus Lactis Culture Productivity and Resulting Nisin Activity

Abstract

The article concerns the study results of the photostimulation influence of the Lactobacillus lactis inoculum on the cultural effervescence and obtained nisin activity. The researchers used frozen Lactobacillus lactis inoculum to produce nisin. They activated the culture in a 5.0 ml sterile MRS tube kept in an incubator at 37 °C for 48 hours. Before incubation, Lactobacillus lactis culture was treated with blue spectrum light with a wavelength of 430–470 nm and a luminous flux intensity of 35 MW/cm2 for 1 hour (experimental group). Bacterial samples of the control group were not treated with light. A man used the MRS medium for fermentation. To determine the culture titer, the authors run sowing on the MRS medium. The researchers defined an oxidative stress influence on the Lactobacillus lactis stability by cultivation on an agar medium using 5 mmol of hydrogen peroxide. To identify the titer and resistance to oxidative stress before sowing, the cultures were treated with blue light with the specified characteristics and processing time. It enables to increase the nisin activity after 24 hours of bacterial cultivation compared to the control group by 19.3%, or by 558 IU/ml. The researchers proved that the titer of Lactobacillus lactis culture against the background of preliminary irradiation with blue spectrum light before cultivation is 56.3% higher than the samples of the control group. Treatment of Lactobacillus lactis culture with blue spectrum light increases its viability under oxidative stress by 75%.